angiotensinogen and Kidney-Diseases

Multiple types of renin-angiotensin system (RAS) blockers exist, allowing interference with the system at the level of renin, angiotensin-converting enzyme, or the angiotensin II receptor. Yet, in particular, for the treatment of hypertension, the number of patients with uncontrolled hypertension continues to rise, either due to patient noncompliance or because of the significant renin rises that may, at least partially, overcome the effect of RAS blockade (RAS escape). New approaches to target the RAS are either direct antisense oligonucleotides that inhibit angiotensinogen RNA translation, or small interfering RNA (siRNA) that function via the RNA interference pathway. Since all angiotensins stem from angiotensinogen, lowering angiotensinogen has the potential to circumvent the RAS escape phenomenon. Moreover, antisense oligonucleotides and small interfering RNA require injections only every few weeks to months, which might reduce noncompliance. Of course, angiotensinogen suppression also poses a threat in situations where the RAS is acutely needed, for instance in women becoming pregnant during treatment, or in cases of emergency, when severe hypotension occurs. This review discusses all preclinical data on angiotensinogen suppression, as well as the limited clinical data that are currently available. It concludes that it is an exciting new tool to target the RAS with high specificity and a low side effect profile. Its long-term action might revolutionize pharmacotherapy, as it could overcome compliance problems. Preclinical and clinical programs are now carefully investigating its efficacy and safety profile, allowing an optimal introduction as a novel drug to treat cardiovascular and renal diseases in due time.

Topics: Angiotensinogen; Female; Humans; Hypertension; Kidney Diseases; Oligonucleotides, Antisense; Pregnancy; Renin; Renin-Angiotensin System; RNA, Small Interfering

Excess adiposity can induce adverse sequelae in multiple cell types and organ systems. The transition from the lean to the obese state is characterized by fundamental cellular changes at the level of the adipocyte. These changes affect the local microenvironment within the respective adipose tissue but can also affect nonadipose systems. Adipocytes within fat pads respond to chronic nutrient excess through hyperplasia or hypertrophy, which can differentially affect interorgan crosstalk between various adipose depots and other organs. This crosstalk is dependent on the unique ability of the adipocyte to coordinate metabolic adjustments throughout the body and to integrate responses to maintain metabolic homeostasis. These actions occur through the release of free fatty acids and metabolites during times of energy need - a process that is altered in the obese state. In addition, adipocytes release a wide array of signalling molecules, such as sphingolipids, as well as inflammatory and hormonal factors (adipokines) that are critical for interorgan crosstalk. The interactions of adipose tissue with the kidney - referred to as the adipo-renal axis - are important for normal kidney function as well as the response of the kidney to injury. Here, we discuss the mechanistic basis of this interorgan crosstalk, which clearly has great therapeutic potential given the increasing rates of chronic kidney disease secondary to obesity and type 2 diabetes mellitus.

Topics: Adipokines; Adiponectin; Adipose Tissue; AMP-Activated Protein Kinases; Angiotensin II; Angiotensinogen; Ceramidases; Diabetes Mellitus, Type 2; Humans; Inflammation; Kidney Diseases; Leptin; Macrophages; Obesity; Receptors, Adiponectin; Signal Transduction

Renin-angiotensin-aldosterone system (RAAS) plays important roles in regulating renal hemodynamics and functions, as well as in the pathophysiology of hypertension and renal disease. In the kidney, angiotensin II (Ang II) production is controlled by independent multiple mechanisms. Ang II is compartmentalized in the renal interstitial fluid with much higher concentrations than those existing in the circulation. Inappropriate activation of the intrarenal RAAS is an important contributor to the pathogenesis of hypertension and renal injury. It has been revealed that intrarenal Ang II levels are predominantly regulated by angiotensinogen and therefore, urinary angiotensinogen could be a biomarker for intrarenal Ang II generation. In addition, recent studies have demonstrated that aldosterone contributes to the progression of renal injury via direct actions on glomerular podocytes, mesangial cells, proximal tubular cells and tubulo-interstitial fibroblasts through the activation of locally expressed mineralocorticoid receptor. Thus, it now appears that intrarenal RAAS is independently regulated and its inappropriate activation contributes to the pathogenesis of the development of hypertension and renal disease. This short review article will focus on the independent regulation of the intrarenal RAAS with an emphasis on the specific role of angiotensinogen.

Topics: Angiotensin II; Angiotensinogen; Enzyme-Linked Immunosorbent Assay; Humans; Hypertension; Kidney; Kidney Diseases; Renin; Renin-Angiotensin System

The intrarenal renin-angiotensin system (RAS) has many well-documented pathophysiologic functions in both blood pressure regulation and renal disease development. Angiotensin II (Ang II) is the major bioactive product of the RAS. It induces inflammation, renal cell growth, mitogenesis, apoptosis, migration, and differentiation. In addition, Ang II regulates the gene expression of bioactive substances and activates multiple intracellular signaling pathways that are involved in renal damage. Activation of the Ang II type 1 (AT1) receptor pathway results in the production of proinflammatory mediators, intracellular formation of reactive oxygen species, cell proliferation, and extracellular matrix synthesis, which in turn facilities renal injury. Involvement of angiotensinogen (AGT) in intrarenal RAS activation and development of renal disease has previously been reported. Moreover, studies have demonstrated that the urinary excretion rates of AGT provide a specific index of the intrarenal RAS status. Enhanced intrarenal AGT levels have been observed in experimental models of renal disease, supporting the concept that AGT plays an important role in the development and progression of renal disease. In this review, we focus on the role of intrarenal RAS activation in the pathophysiology of renal disease. Additionally, we explored the potential of urinary AGT as a novel biomarker of intrarenal RAS status in renal disease.

Topics: Angiotensin II; Angiotensinogen; Animals; Biomarkers; Disease Progression; Humans; Kidney; Kidney Diseases; Receptor, Angiotensin, Type 1; Renin-Angiotensin System; Signal Transduction

In angiotensin (Ang)-II-dependent hypertension, collecting duct renin synthesis and secretion are stimulated despite suppression of juxtaglomerular (JG) renin. This effect is mediated by Ang II type 1 (AT1) receptor independent of blood pressure. Although the regulation of JG renin is known, the mechanisms by which renin is regulated in the collecting duct are not completely understood. The presence of renin activity in the collecting duct may provide a pathway for intratubular Ang II formation since angiotensinogen substrate and angiotensin converting enzyme are present in the distal nephron. The recently named new member of the renin-angiotensin system (RAS), the (pro)renin receptor [(P)RR], is able to bind renin and the inactive prorenin, thus enhancing renin activity and fully activating prorenin. We have demonstrated that renin and (P)RR are augmented in renal tissues from rats infused with Ang II and during sodium depletion, suggesting a physiological role in intrarenal RAS activation. Importantly, (P)RR activation also causes activation of intracellular pathways associated with increased cyclooxygenase 2 expression and induction of profibrotic genes. In addition, renin and (P)RR are upregulated by Ang II in collecting duct cells. Although the mechanisms involved in their regulation are still under study, they seem to be dependent on the intrarenal RAS activation. The complexities of the mechanisms of stimulation also depend on cyclooxygenase 2 and sodium depletion. Our data suggest that renin and (P)RR can interact to increase intratubular Ang II formation and the activation of profibrotic genes in renal collecting duct cells. Both pathways may have a critical role in the development of hypertension and renal disease.

Topics: Angiotensin II; Angiotensinogen; Animals; Blood Pressure; Humans; Hypertension; Kidney Diseases; Peptidyl-Dipeptidase A; Rats; Receptors, Cell Surface; Renin; Renin-Angiotensin System; Vacuolar Proton-Translocating ATPases

Experimental models of hypertension and patients with inappropriately increased renin formation due to a stenotic kidney, arteriosclerotic narrowing of the renal arterioles or a rare juxtaglomerular cell tumor have shown a progressive augmentation of the intrarenal/intratubular renin-angiotensin system (RAS). The increased intrarenal angiotensin II (Ang II) elicits renal vasoconstriction and enhanced tubular sodium reabsorption in proximal and distal nephron segments. The enhanced intrarenal Ang II levels are due to both increased Ang II type 1 (AT1) receptor mediated Ang II uptake and AT1 receptor dependent stimulation of renal angiotensinogen (AGT) mRNA and augmented AGT production. The increased AGT formation and secretion into the proximal tubular lumen leads to local formation of Ang II, which stimulates proximal transporters such as the sodium/hydrogen exchanger. Enhanced AGT production also leads to spillover of AGT into the distal nephron segments as reflected by AGT in the urine, which provides an index of intrarenal RAS activity. There is also increased Ang II concentration in distal nephron with stimulation of distal sodium transport. Increased urinary excretion of AGT has been demonstrated in patients with hypertension, type 1 and type 2 diabetes mellitus, and several types of chronic kidney diseases indicating an upregulation of intrarenal RAS activity.

Topics: Angiotensin II; Angiotensinogen; Animals; Biological Transport; Humans; Hypertension; Kidney Diseases; Receptor, Angiotensin, Type 1; Renin; Renin-Angiotensin System; Sodium; Vasoconstriction

Topics: Angiotensin II; Angiotensin-Converting Enzyme 2; Angiotensinogen; Animals; Biomarkers; Humans; Hypertension; Kidney; Kidney Diseases; Peptidyl-Dipeptidase A; Prorenin Receptor; Receptors, Cell Surface; Renin; Renin-Angiotensin System; Serine Proteases

In recent years, the focus of interest on the role of the renin-angiotensin system (RAS) in the pathophysiology of hypertension and organ injury has changed to a major emphasis on the role of the local RAS in specific tissues. In the kidney, all of the RAS components are present and intrarenal angiotensin II (Ang II) is formed by independent multiple mechanisms. Proximal tubular angiotensinogen, collecting duct renin, and tubular angiotensin II type 1 (AT1) receptors are positively augmented by intrarenal Ang II. In addition to the classic RAS pathways, prorenin receptors and chymase are also involved in local Ang II formation in the kidney. Moreover, circulating Ang II is actively internalized into proximal tubular cells by AT1 receptor-dependent mechanisms. Consequently, Ang II is compartmentalized in the renal interstitial fluid and the proximal tubular compartments with much higher concentrations than those existing in the circulation. Recent evidence has also revealed that inappropriate activation of the intrarenal RAS is an important contributor to the pathogenesis of hypertension and renal injury. Thus, it is necessary to understand the mechanisms responsible for independent regulation of the intrarenal RAS. In this review, we will briefly summarize our current understanding of independent regulation of the intrarenal RAS and discuss how inappropriate activation of this system contributes to the development and maintenance of hypertension and renal injury. We will also discuss the impact of antihypertensive agents in preventing the progressive increases in the intrarenal RAS during the development of hypertension and renal injury.

Topics: Angiotensin II; Angiotensinogen; Animals; Antihypertensive Agents; Chronic Disease; Disease Models, Animal; Humans; Hypertension; Hypertension, Renal; Kidney; Kidney Diseases; Receptors, Angiotensin; Renin; Renin-Angiotensin System

Topics: Angiotensinogen; Animals; Blood Pressure; Cardiovascular Diseases; Gene Expression Regulation; Humans; Hypertension; Kidney Diseases; Mutation; Polymorphism, Genetic; Promoter Regions, Genetic; Transcription, Genetic

Topics: Angiotensinogen; Cytochrome P-450 CYP11B2; Disease Progression; Genetic Markers; Humans; Kidney Diseases; Nitric Oxide Synthase; Nitric Oxide Synthase Type III; Peptidyl-Dipeptidase A; Polymorphism, Genetic; Receptor, Angiotensin, Type 1; Renin-Angiotensin System

As the only ex utero mechanism for the removal of nitrogenous waste, the mammalian kidney achieves some 50-fold increase in urine production during the perinatal period when the placental circulation becomes no longer available as a functional dialyzer. This urine is efficiently removed from the kidney by the renal pelvis, a smooth muscle structure unique to mammals, which develops during the perinatal period. We found that mutant mice completely devoid of angiotensinogen or its type 1 receptor, as well as wild-type neonates given an ACE inhibitor, fail to develop a renal pelvis or a ureteral peristaltic movement. These structural and functional defects in the urinary tract are followed by severe obstructive injury of the renal parenchyma. The ability of angiotensin to directly induce the pelvis is demonstrated in an organ culture system, in which treatment with angiotensin induces the characteristic smooth muscle layer in the wild type, but not in homozygous null mutants. Upregulation of both renal angiotensin content and type 1 receptor at the renal hilum are also demonstrated in the wild type during the transition from intra- to extra-uterine life. By inducing the timely development of the renal pelvis, angiotensin thus facilitates the removal from the renal parenchyma of the urine that promptly increases at birth, thereby effectively preventing a buildup of intrarenal pressure and a consequent development of dysmorphic kidney.

Topics: Angiotensin-Converting Enzyme Inhibitors; Angiotensinogen; Angiotensins; Animals; Animals, Newborn; Kidney Diseases; Kidney Pelvis; Mice; Mice, Mutant Strains; Receptor, Angiotensin, Type 1; Receptor, Angiotensin, Type 2; Receptors, Angiotensin; Urinary Tract

In this meta-analysis, we attempted to derive pooled estimates for the putative associations between various cardiovascular-renal disorders and the M235T polymorphism of the angiotensinogen gene.. Case-control studies were combined, using the Mantel and Haenszel approach. Joint P values for continuous variables were calculated by Stouffer's method. Continuous measurements reported in different units were expressed on a percentage scale using the intrastudy mean of the MM genotype as denominator.. The computerized database used for this analysis included 69 reports with an overall sample size of 27,906 subjects. Overall, possession of the T allele was associated with an increased risk of hypertension. In comparison with the MM reference group (number of studies, n = 32), the excess risk was 31% (P = 0.001) in TT homozygotes and 11% (P = 0.03) in TM heterozygotes. The sensitivity analysis showed that this association was present only in whites (T allelic frequency, f = 42.2%), but not in blacks (f = 77.0%) or Asians (f = 78.0%). Atherosclerotic complications (n = 12), renal microvascular disorders (n = 13), cardiomyopathy (n = 2) or diabetic retinopathy (n = 3) were not correlated with the M235T polymorphism. Publication bias was observed for hypertension, but not for coronary heart disease, including myocardial infarction, and for microvascular nephropathy. Furthermore, in comparison with the MM control group, the circulating angiotensinogen levels (n = 8) were raised by 11 and 7% (P = 0.01) in TT and TM subjects, respectively. In contrast, plasma levels of the angiotensin I converting enzyme (n = 4) and body mass index (n = 15) were not associated with the T allele.. The T allele encoding angiotensinogen is not associated with atherosclerotic or microvascular complications, but in Caucasians behaves as a marker for hypertension. This association, which may have been inflated by publication bias, does not necessarily imply causality.

Topics: Alleles; Angiotensinogen; Asian People; Black People; Cardiovascular Diseases; Case-Control Studies; Cross-Sectional Studies; Female; Genetic Markers; Genotype; Humans; Kidney Diseases; Male; Middle Aged; Peptidyl-Dipeptidase A; Polymorphism, Genetic; Risk Factors; White People

The role of molecular genetics in the pathophysiology of various diseases is becoming clearer and clearer. In the field of cardiovascular diseases, molecular genetic aspects have been shown to play a definite role in the aetiology of these diseases. Several molecular-genetic variations called polymorphisms, occur in the population. The genes encoding the different components of the reninangiotensin-aldosterone system (RAAS), an important system in the regulation of the function and structure of the heart and vascular wall, also display polymorphisms. For some of these polymorphisms associations with various cardiovascular and renal diseases have been described. At present, this is particularly clear for the relation between angiotensin-converting-enzyme (ACE) polymorphism and the incidence of atherosclerotic complications and diabetic nephropathy, and for the relation between so-called M235 T-variant of the angiotensinogen gene and hypertension. Future research will have to show where it is worthwhile to use these and other polymorphisms as a marker for genetic risk. In what way the different RAAS-polymorphisms relate to functional abnormalities is as yet unclear, as are the potential therapeutic implications.

Topics: Angiotensin II; Angiotensinogen; Cardiovascular Diseases; Chromosome Mapping; Female; Genetic Markers; Humans; Kidney Diseases; Male; Peptidyl-Dipeptidase A; Point Mutation; Polymorphism, Genetic; Receptors, Angiotensin; Renin-Angiotensin System; Spondylitis, Ankylosing

The involvement of polymorphic variations in the structure of the renin angiotensin aldosterone system genes in the predisposition to cardiovascular disease is a particularly important field of investigation. A large number of studies have been published and their results are often contradictory. It is therefore important to identify the functional variants modifying the level of expression of these genes or the structure of the encoded proteins. This will allow the clear quantitation of their effect on quantitative phenotypes both in vitro and in vivo. It is also important to study in the future new phenotypes, particularly dynamic phenotypes, potentially influenced by these genotypes and to use them for building a new cardio-vascular pharmacogenetics.

Topics: Aldosterone; Angiotensinogen; Cardiovascular Diseases; Genotype; Humans; Kidney Diseases; Peptidyl-Dipeptidase A; Polymorphism, Genetic; Receptors, Angiotensin; Renin-Angiotensin System

We explored the association of novel urinary biomarkers with albumin-creatinine ratio (ACR) in adults with sickle cell anaemia. Of 37 participants, 13 (35.2%) had persistent albuminuria (PA). Urinary levels of clusterin (p = 0.002), retinol-binding protein 4 (p = 0.008), alpha-1 microglobulin (p = 0.002) and angiotensinogen (p = 0.006) were significantly higher in participants with PA than in those without PA. Although univariate analysis showed significant associations between both alpha-1 microglobulin (p = 0.035) and angiotensinogen (p = 0.0021) with ACR, only angiotensinogen was associated with ACR in multivariable analysis (p = 0.04). Our results suggest that urinary angiotensinogen may identify sickle cell anaemia patients at risk for kidney disease.

Topics: Adult; Albuminuria; Anemia, Sickle Cell; Angiotensinogen; Biomarkers; Creatinine; Humans; Kidney Diseases

Augmentation of intrarenal angiotensinogen (AGT) leads to further formation of intrarenal angiotensin II (Ang II) and the development of hypertensive kidney injury. Recent studies demonstrated that macrophages and the enhanced production of pro-inflammatory cytokines can be crucial mediators of renal AGT augmentation in hypertension. Accordingly, this study investigated the effects of immunosuppression by mycophenolate mofetil (MMF) on intrarenal AGT augmentation. Ang II (80 ng/min) was infused with or without daily administration of MMF (50 mg/kg) to Sprague-Dawley rats for 2 weeks. Mean arterial pressure (MAP) in Ang II infused rats was slightly higher (169.7 ± 6.1 mmHg) than the Ang II + MMF group (154.7 ± 2.0 mmHg), but was not statistically different from the Ang II + MMF group. MMF treatment suppressed Ang II-induced renal macrophages and IL-6 elevation. Augmentation of urinary AGT by Ang II infusion was attenuated by MMF treatment (control: 89.3 ± 25.2, Ang II: 1194 ± 305.1, and Ang II + MMF: 389 ± 192.0 ng/day). The augmentation of urinary AGT by Ang II infusion was observed before the onset of proteinuria. Elevated intrarenal AGT mRNA and protein levels in Ang II infused rats were also normalized by the MMF treatment (AGT mRNA, Ang II: 2.5 ± 0.2 and Ang II + MMF: 1.5 ± 0.1, ratio to control). Ang II-induced proteinuria, mesangial expansion and renal tubulointerstitial fibrosis were attenuated by MMF. Furthermore, MMF treatment attenuated the augmentation of intrarenal NLRP3 mRNA, a component of inflammasome. These results indicate that stimulated cytokine production in macrophages contributes to intrarenal AGT augmentation in Ang II-dependent hypertension, which leads to the development of kidney injury.

Topics: Angiotensin II; Angiotensinogen; Animals; Blood Pressure; Hypertension; Immunosuppression Therapy; Kidney; Kidney Diseases; Mycophenolic Acid; Proteinuria; Rats; Rats, Sprague-Dawley; RNA, Messenger

We investigated oxidative stress and RAAS biomarkers, as well as their association, in chronic heart failure (CHF) patients on optimized medical therapy, stratified by disease severity or by renal function. Since vitamin D has been shown to attenuate RAAS activation and oxidative stress, we further evaluated the relationship between vitamin D, RAAS and oxidative stress in CHF patients with or without renal impairment. Sixty CHF outpatients were included and stratified by disease severity or by renal function. We quantified urinary hydrogen peroxide, plasma and urinary isoprostanes, plasma total antioxidant status, urinary angiotensinogen (intrarenal RAAS activation biomarker) and plasma angiotensinogen, plasma renin and aldosterone concentration, serum angiotensin-converting enzyme (ACE) activity, plasma angiotensin peptides, and serum total 25-hydroxyvitamin D (S-total 25(OH)D). Severe CHF patients had higher urinary isoprostanes (p = 0.002) and lower S-total 25(OH)D (p = 0.006) compared to mild-to-moderate patients, but no differences were observed for other redox or RAAS biomarkers. Patients with impaired renal function (iRF) had higher urinary angiotensinogen (p = 0.003) and lower S-total 25(OH)D (p = 0.028) compared to those with normal renal function (nRF), while no differences were observed for the remaining RAAS and redox parameters. Several positive correlations between oxidative stress and RAAS biomarkers were detected in iRF patients, while in patients with nRF these correlations were primarily inverse. In CHF-iRF patients, S-25(OD)D was inversely associated with urinary isoprostanes, which in turn were positively associated with plasma angiotensinogen and serum ACE. In conclusion, CHF patients with renal function impairment have increased intrarenal RAAS activation and lower vitamin D values and might benefit from the combination of RAAS blockers with vitamin D and/or antioxidants.

Topics: Aged; Angiotensinogen; Biomarkers; Chronic Disease; Female; Glomerular Filtration Rate; Heart Failure; Humans; Isoprostanes; Kidney; Kidney Diseases; Male; Middle Aged; Oxidative Stress; Peptidyl-Dipeptidase A; Renin-Angiotensin System; Severity of Illness Index; Vitamin D

Circadian fluctuation disorder of the intrarenal renin-angiotensin system (RAS) causes that of blood pressure (BP) and renal damage. In renal damage with an impaired glomerular filtration barrier, liver-derived angiotensinogen (AGT) filtered through damaged glomeruli regulates intrarenal RAS activity. Furthermore, glomerular permeability is more strongly affected by glomerular hypertension than by systemic hypertension. Thus, we aimed to clarify whether the circadian rhythm of intrarenal RAS activity is influenced by AGT filtered through damaged glomeruli due to glomerular capillary pressure. Rats with adriamycin nephropathy and an impaired glomerular filtration barrier were compared with control rats. In adriamycin nephropathy rats, olmesartan medoxomil (an angiotensin II type 1 receptor blocker) or hydralazine (a vasodilator) was administered, and the levels of intrarenal RAS components in the active and rest phases were evaluated. Moreover, the diameter ratio of afferent to efferent arterioles (A/E ratio), an indicator of glomerular capillary pressure, and the glomerular sieving coefficient (GSC) based on multiphoton microscopy in vivo imaging, which reflects glomerular permeability, were determined. Mild renal dysfunction was induced, and the systemic BP increased, resulting in increased A/E ratios in the adriamycin nephropathy rats compared with the control rats. Fluctuations in intrarenal RAS activity occurred in parallel with circadian fluctuations in glomerular capillary pressure, which disappeared with olmesartan treatment and were maintained with hydralazine treatment. Furthermore, the GSCs for AGT also showed similar changes. In conclusion, intrarenal RAS activity is influenced by the filtration of liver-derived AGT from damaged glomeruli due to circadian fluctuation disorder of the glomerular capillary pressure.

Topics: Angiotensinogen; Animals; Circadian Rhythm; Doxorubicin; Glomerular Filtration Rate; Hydralazine; Hypertension; Kidney Diseases; Liver; Rats; Renin-Angiotensin System

Topics: Adolescent; Adult; Aged; Angiotensinogen; Female; Humans; Kidney Diseases; Lupus Nephritis; Male; Middle Aged; Prospective Studies; Young Adult

Using a transgenic cross, we evaluated features of preeclampsia, renal injury and the sFlt1/VEGF changes. Transgenic hAGT and hREN, or wild-type (WT) C57Bl/6 mice were cross-bred: female hAGT × male hREN for preeclampsia (PRE) model and female WT × male WT for pregnant controls (WTP). Samples were collected for plasma VEGF, sFlt1, and urine albumin. Blood pressures (BP) were monitored by telemetry. Vascular reactivity was investigated by wire myography. Kidneys and placenta were immunostained for sFlt1 and VEGF. Eleven PRE and 9 WTP mice were compared. PRE more frequently demonstrated albuminuria, glomerular endotheliosis (80% vs. 11%;

Topics: Albuminuria; Angiotensinogen; Animals; Blood Pressure; Disease Models, Animal; Endothelial Cells; Female; Genetic Predisposition to Disease; Gestational Age; Humans; Kidney Diseases; Kidney Glomerulus; Mice, Inbred C57BL; Mice, Transgenic; Phenotype; Placenta; Pre-Eclampsia; Pregnancy; Renin; Renin-Angiotensin System; Signal Transduction; Vascular Endothelial Growth Factor A; Vascular Endothelial Growth Factor Receptor-1; Vascular Remodeling; Vasoconstriction; Vasodilation

Urinary protein (UP) is widely used as a clinical marker for podocyte injury; however, not all proteinuric nephropathies fit this model. We previously described the elevation of urinary angiotensinogen (AGT) accompanied by AGT expression by injured podocytes in a nitric oxide inhibition rat model (Eriguchi M, Tsuruya K, Haruyama N, Yamada S, Tanaka S, Suehiro T, Noguchi H, Masutani K, Torisu K, Kitazono T. Kidney Int 87: 116-127, 2015). In this report, we performed the human and animal studies to examine the significance and origin of urinary AGT. In the human study, focal segmental glomerulosclerosis (FSGS) patients presented with higher levels of urinary AGT, corrected by UP, than minimal-change disease (MCD) patients. Furthermore, AGT was evident in podocin-negative glomerular segmental lesions. We also tested two different nephrotic models induced by puromycin aminonucleoside in Wistar rats. The urinary AGT/UP ratio and AGT protein and mRNA expression in sieved glomeruli from FSGS rats were significantly higher than in MCD rats. The presence of AGT at injured podocytes in FSGS rats was detected by immunohistochemistry and immunoelectron microscopy. Finally, we observed the renal tissue and urinary metabolism of exogenous injected human recombinant AGT (which is not cleaved by rodent renin) in FSGS and control rats. Significant amounts of human AGT were detected in the urine of FSGS rats, but not of control rats. Immunostaining for rat and human AGT identified that only rat AGT was detected in injured podocytes, and filtered human AGT was seen in superficial proximal tubules, but not in injured podocytes, suggesting AGT generation by injured podocytes. In conclusion, the urinary AGT/UP ratio represents a novel specific marker of podocyte injury.

Topics: Adult; Aged; Angiotensinogen; Animals; Antibiotics, Antineoplastic; Female; Glomerulosclerosis, Focal Segmental; Humans; Kidney; Kidney Diseases; Kidney Glomerulus; Kidney Tubules, Proximal; Male; Middle Aged; Nephrosis, Lipoid; Podocytes; Proteinuria; Puromycin Aminonucleoside; Rats; Rats, Wistar

The renal tissue renin-angiotensin system is activated in chronic kidney diseases. We previously demonstrated that intrarenal ANG II is synthesized primarily from liver-derived angiotensinogen filtered through the glomerulus and that podocyte injury increases the passage of angiotensinogen into the tubular lumen and generation of ANG II. In the present study, we tested the effect of cessation of glomerular filtration by ureteral obstruction on renal ANG II generation in kidneys with podocyte injury under two experimental conditions. Ureteral obstruction is known to activate the renin-angiotensin system in nonproteinuric kidneys. Transgenic mice expressing hCD25 in podocyte (NEP25) were injected with 1.25 or 10 ng/g body wt of LMB2, a hCD25-targeted immunotoxin, subjected to unilateral ureteral ligation on the following day, and euthanized 7 and 4 days later, respectively. In both experiments, compared with the kidney in untreated wild-type mice, renal angiotensinogen protein, as assessed by immunostaining and Western blot analysis, was increased in the contralateral unobstructed kidney. However, it was markedly decreased in the obstructed kidney. Whereas intrarenal ANG II content was increased in the contralateral kidney compared with the untreated kidney (248 ± 83 vs. 106 ± 21 and 298 ± 185 vs. 64.8 ± 20 fmol/g kidney, respectively), this increase was suppressed in the obstructed kidney (161 ± 75 and 113 ± 34 fmol/g kidney, respectively), a pattern opposite to what we expected in obstructed kidneys without podocyte injury. Thus, our study indicates that the major source of increased renal ANG II in podocyte injury is filtered angiotensinogen.

Topics: Albuminuria; Angiotensin II; Angiotensinogen; Animals; Antibodies, Monoclonal; Disease Models, Animal; Down-Regulation; Exotoxins; Female; Glomerular Filtration Rate; Humans; Interleukin-2 Receptor alpha Subunit; Kidney Diseases; Mice, Inbred C57BL; Mice, Transgenic; Podocytes; Renin-Angiotensin System; RNA, Messenger; Signal Transduction; Time Factors; Ureteral Obstruction

Recurrent febrile urinary tract infections during infancy cause renal scarring, which is characterized by progressive focal interstitial fibrosis and may lead to renal failure. Renal scarring can be diagnosed through scintigraphy, although it seems impractical to perform renal scintigraphy for all infants with febrile urinary tract infections. Therefore, it is important to search for a biomarker to identify the presence of renal scarring. We hypothesized that urinary biomarkers of nephropathy may increase in infants with renal scarring following febrile urinary tract infections.. A total of 49 infants who underwent renal scintigraphy for febrile urinary tract infections were enrolled in the study. Several measurements were performed using urine samples, including total proteins, beta2-microglobulins, N-acetyl-β-D-glucosaminidase, neutrophil gelatinase associated lipocalin, liver-type fatty acid binding protein and angiotensinogen. Values were corrected by creatinine and compared between patients with and without renal scarring.. Among urinary biomarkers only angiotensinogen in patients with scarring (median 14.6 μg/gm creatinine) demonstrated significantly higher levels than in patients without scarring (3.6 μg/gm creatinine, p <0.001).. Urinary angiotensinogen may be useful for diagnosing the presence of renal scarring.

Topics: Adolescent; Angiotensinogen; Biomarkers; Child; Child, Preschool; Cicatrix; Female; Fever; Humans; Infant; Kidney Diseases; Male; Pilot Projects; Prospective Studies; Urinary Tract Infections

Both hyperuricaemia and activation of the intrarenal renin-angiotensin system (RAS) play an important role in the development of hypertension and renal damage. However, it has not been clear whether hyperuricaemia is associated with renal damage due to hypertension or intrarenal RAS activation, as well as their circadian rhythms.. We recruited 43 chronic kidney disease (CKD) patients who did not receive RAS blockers and antihyperuricaemic drugs, and investigated the relationship among serum uric acid (sUA) levels, the circadian rhythm of urinary angiotensinogen (U-AGT) excretion levels, and the levels of albuminuria (U-ACR) and proteinuria (U-P/Cr).. sUA levels were significantly associated with estimated glomerular filtration rate (eGFR) (P = 0.002), systolic blood pressure (SBP) (daytime, P = 0.031), and U-ACR (daytime, P = 0.006 and nighttime, P = 0.008) and U-P/Cr (daytime, P = 0.017 and nighttime, P = 0.013). However, there were no significant differences between sUA levels and SBP in nighttime and U-AGT excretion levels in both time periods. Multiple regression analyses for sUA levels were performed using age, sex, eGFR and each parameter (SBP, U-AGT/Cr, U-ACR or U-P/Cr). sUA levels were not associated with SBP or U-AGT/Cr in both time periods. sUA levels tended to correlate with U-P/Cr levels in nighttime, and were significantly associated with U-P/Cr in daytime (P = 0.026) and U-ACR in daytime (P = 0.017) and nighttime (P = 0.046). Moreover, no significant differences were found between sUA levels and night-to-day ratios of some parameters.. These data suggest that hyperuricaemia is associated with renal damage, independently of hypertension and intrarenal RAS activation, as well as their circadian rhythms.

Topics: Adult; Aged; Aged, 80 and over; Albuminuria; Angiotensinogen; Biomarkers; Blood Pressure; Circadian Rhythm; Female; Glomerular Filtration Rate; Humans; Hypertension; Hyperuricemia; Kidney; Kidney Diseases; Linear Models; Male; Middle Aged; Multivariate Analysis; Renin-Angiotensin System; Risk Factors; Time Factors; Uric Acid; Young Adult

Few studies have addressed the growing concerns of chronic kidney diseases in children with intrauterine growth restriction (IUGR). Therefore, the purpose of this study was to evaluate long-term kidney dysfunction and determine if urinary angiotensinogen (AGT) was suitable as a novel early biomarker for kidney dysfunction in IUGR offspring.. Pregnant rats underwent bilateral uterine artery ligation, and as a control group, sham surgeries were performed.. The birth weight was reduced, the urinary AGT to creatinine ratio was significantly higher at week 20, and urinary protein levels were significantly higher at week 32 in IUGR rats than in control rats. On the other hand, the histological findings at week 32 revealed long-term kidney dysfunction, more severe glomerulosclerosis, and greater glomerular diameters in IUGR rats. Moreover, AGT mRNA expression and immunohistological staining were significantly increased in IUGR rats; this suggests that the intrarenal renin-angiotensin system (RAS) contributes to renal dysfunction of IUGR offspring.. Urinary AGT elevation prior to urinary protein levels suggests that AGT is an early biomarker. At week 32, kidney dysfunction was severe in IUGR rats and intrarenal RAS appeared to be one of the causes.

Topics: Age Factors; Angiotensinogen; Animals; Biomarkers; Birth Weight; Creatinine; Disease Models, Animal; Early Diagnosis; Female; Fetal Growth Retardation; Kidney; Kidney Diseases; Ligation; Organ Size; Predictive Value of Tests; Pregnancy; Prenatal Exposure Delayed Effects; Proteinuria; Rats, Sprague-Dawley; Renin-Angiotensin System; Up-Regulation; Uterine Artery

The aims of this study were (1) to examine the renoprotective effects of alogliptin and (2) to establish urinary angiotensinogen (AGT) as a prognostic marker of renoprotective effects of alogliptin in patients with type 2 diabetes (T2D).. In 43 patients with T2D (18 women, 66.1 ± 1.71 years), 25 mg/day of alogliptin was added to the traditional hypoglycemic agents and/or nondrug treatments. Urinary concentrations of albumin (Alb) and AGT, normalized by urinary concentrations of creatinine (Cr) (UAlbCR and UAGTCR, respectively), were measured before and after the 12-week alogliptin treatment.. Alogliptin treatment tended to decrease UAlbCR (99.6 ± 26.8 versus 114.6 ± 36.0 mg/g Cr, P = 0.198). Based on % change in UAlbCR, patients were divided into two groups, responders (< -25%) and nonresponders (≥ -25%), and a logistic analysis of UAGTCR before treatment showed cutoff value of 20.8 µg/g Cr. When all patients were redivided into two groups, those with higher values of UAGTCR before the treatment (Group H, n = 20) and those with lower values (Group L), Group H showed significantly decreased UAlbCR in response to alogliptin (-14.6 ± 8.6 versus +22.8 ± 16.8%, P = 0.033).. Urinary AGT could be a prognostic marker of renoprotective effects of alogliptin in patients with T2D.

Topics: Aged; Albumins; Angiotensinogen; Biomarkers; Creatinine; Diabetes Mellitus, Type 2; Female; Humans; Hypoglycemic Agents; Japan; Kidney; Kidney Diseases; Logistic Models; Male; Middle Aged; Piperidines; Prognosis; Treatment Outcome; Uracil

The renin-angiotensin-aldosterone system (RAAS) plays pivotal roles in the pathogenesis of chronic kidney disease (CKD) progression. Aliskiren, a direct renin inhibitor, inhibits the rate-limiting step of the RAAS without any alternative pathway. It is proven to reduce albuminuria in CKD patients treated with angiotensin blockade. However, there are few reports which evaluate the advantage of aliskiren as the first-line drug against CKD progression in RAAS-activated hypertensive patients.. Tsukuba hypertensive mice (THM), double transgenic mice carrying both the human renin and human angiotensinogen genes, were fed a high-salt diet and treated with hydraladine, ramipril and aliskiren for 10 weeks. Blood pressure and urinary albumin excretion were measured every 2 weeks during the experimental period. We evaluated renal histological changes and gene expression. Plasma angiotensin concentration was measured to evaluate the RAAS inhibitory effect.. High-salt-loaded THM showed severe hypertension and renal injury. All antihypertensive drugs suppressed blood pressure and prevented renal disease progression. RAAS blockade showed a higher renoprotective effect than hydraladine despite an equivalent blood pressure lowering effect. Aliskiren exhibited even stronger renoprotection than ramipril. Plasma angiotensin concentration was increased in THM fed both normal salt and high salt. Hydraladine did not alter the plasma angiotensin concentration. Ramipril significantly decreased angiotensin II concentration. Aliskiren treatment almost completely suppressed angiotensin I and resulted in lower angiotensin II concentration than ramipril treatment.. Aliskiren prevents renal disease progression by suppressing both angiotensin I and II in RAAS-activated pathology. Our data suggest the application of a renin inhibitor for preventing kidney disease progression in CKD patients.

Topics: Albuminuria; Amides; Angiotensin I; Angiotensin II; Angiotensin-Converting Enzyme Inhibitors; Angiotensinogen; Animals; Antihypertensive Agents; Blood Pressure; Cytoprotection; Disease Models, Animal; Disease Progression; Down-Regulation; Fumarates; Humans; Hydralazine; Hypertension; Kidney; Kidney Diseases; Mice; Mice, Transgenic; Ramipril; Renin; Renin-Angiotensin System; Sodium Chloride, Dietary; Time Factors

Intrarenal angiotensin II is increased in kidney diseases independently of plasma angiotensin II and is thought to promote progressive deterioration of renal architecture. Here we investigated the mechanism of enhanced renal angiotensin II generation in kidney glomerular diseases. For this, kidney- or liver-specific angiotensinogen gene (Agt) knockout was superimposed on the mouse model of inducible podocyte injury (NEP25). Seven days after induction of podocyte injury, renal angiotensin II was increased ninefold in NEP25 mice with intact Agt, accompanied by increases in urinary albumin and angiotensinogen excretion, renal angiotensinogen protein, and its mRNA. Kidney Agt knockout attenuated renal Agt mRNA but not renal angiotensin II, renal, or urinary angiotensinogen protein. In contrast, liver Agt knockout markedly reduced renal angiotensin II to 18.7% of that of control NEP25 mice, renal and urinary angiotensinogen protein, but not renal Agt mRNA. Renal angiotensin II had no relationship with renal Agt mRNA, or with renal renin mRNA, which was elevated in liver Agt knockouts. Kidney and liver dual Agt knockout mice showed phenotypes comparable to those of liver Agt knockout mice. Thus, increased renal angiotensin II generation upon severe podocyte injury is attributed to increased filtered angiotensinogen of liver origin resulting from loss of macromolecular barrier function of the glomerular capillary wall that occurs upon severe podocyte injury.

Topics: Albuminuria; Angiotensin II; Angiotensinogen; Animals; Antibodies, Monoclonal; Disease Models, Animal; Exotoxins; Genotype; Kidney Diseases; Kidney Tubules, Proximal; Liver; Membrane Proteins; Mice, Knockout; Phenotype; Podocytes; RNA, Messenger; Sodium; Time Factors; Up-Regulation

The role of the circulating renin-angiotensin system (RAS) in regulating systemic blood pressure and sodium balance is well established. More recently, researchers have turned their focus to the local generation of angiotensin II (Ang II) in specific tissues. Matsusaka et al. revisit the renal RAS and provide evidence that liver-derived angiotensinogen (AGT) is a major determinant of renal Ang II levels in a model of podocyte injury.

Topics: Angiotensin II; Angiotensinogen; Animals; Kidney Diseases; Kidney Tubules, Proximal; Liver; Podocytes

Obstructive nephropathy due to congenital or acquired urinary tract obstruction is one of the most important causes of chronic renal failure in children. There is a need for identification of new noninvasive urinary biomarkers to provide the clinician with fast, specific and reliable diagnostic and prognostic tool. The aim of the study was to determine whether urinary angiotensinogen (uAGT) may be a useful marker of obstruction in children with hydronephrosis (HN) caused by ureteropelvic junction obstruction (UPJO).. The study cohort consisted of surgical group (SG): 31 children with severe HN who required surgery; nonsurgical group (NSG): 20 patients with mild HN, and reference group (RG): 19 healthy children. Urinary concentrations of angiotensinogen were measured using immunoenzymatic ELISA commercial kit and were expressed in ng/mg Cre (uAGT/uCre).. uAGT/uCre level was higher in SG when compared to NSG (p < 0.01) and healthy participants (SG vs. RG: p < 0.01). The difference between the uAGT/uCre in NSG and RG was not statistically significant (p > 0.05). uAGT/uCre was correlated negatively with differential renal function (r = -0.46; p < 0.01).. The present pilot study has clearly demonstrated that children with UPJO showed increased uAGT levels, which correlated negatively with differential renal function in radionuclide scan.

Topics: Adolescent; Angiotensinogen; Biomarkers; Case-Control Studies; Child; Child, Preschool; Confidence Intervals; Enzyme-Linked Immunosorbent Assay; Female; Follow-Up Studies; Humans; Hydronephrosis; Infant; Kidney Diseases; Male; Odds Ratio; Pilot Projects; Renal Insufficiency; Risk Assessment; ROC Curve; Sensitivity and Specificity; Severity of Illness Index; Ureteral Obstruction; Urinalysis

The aim of this study was to evaluate the relationship of local intrarenal renin angiotensin system (RAS) with proteinuria in patients with renal AA amyloidosis.. Thirty-two patients with renal AA amyloidosis (19 male, mean age: 45 ± 13 years) and sixteen healthy controls (5 male, mean age: 32 ± 5 years) were included in this study. Spot urine samples were obtained to measure urinary angiotensinogen (AGT) using human AGT-ELISA, urinary creatinine and protein levels. Logarithmic transformations of urinary AGT-creatinine ratio log(UAGT/Ucre) and urinary protein-to-creatinine ratio (UPCR) were done to obtain the normal distributions of these parameters.. Log(UAGT/UCre) was significantly higher in patients compared with the controls (1.88 ± 0.92 µg/g vs. 1.25 ± 0.70 µg/g; p = 0.023). Importantly a significantly positive correlation was found between log(UAGT/Ucre) and logUPCR in patients (r = 0.595, p = 0.006).. Urinary AGT levels are higher in renal AA amyloidosis patients than in controls. Also, there is a significant positive correlation between urinary AGT and proteinuria in renal AA amyloidosis.

Topics: Adult; Amyloidosis; Angiotensinogen; Biomarkers; Case-Control Studies; Creatinine; Familial Mediterranean Fever; Female; Humans; Kidney Diseases; Male; Middle Aged; Proteinuria; Regression Analysis; Serum Amyloid A Protein

Activation of the intrarenal renin-angiotensin system (RAS) and increased renal medullary hydrogen peroxide (H(2) O(2) ) contribute to hypertension. We examined whether H(2) O(2) mediated hypertension and intrarenal RAS activation induced by angiotensin II (Ang II).. Ang II (200 ng·kg(-1) ·min(-1) ) or saline were infused in Sprague Dawley rats from day 0 to day 14. Polyethylene glycol (PEG)-catalase (10 000 U·kg(-1) ·day(-1) ) was given to Ang II-treated rats, from day 7 to day 14. Systolic blood pressure was measured throughout the study. H(2) O(2) , angiotensin AT(1) receptor and Nox4 expression and nuclear factor-κB (NF-κB) activation were evaluated in the kidney. Plasma and urinary H(2) O(2) and angiotensinogen were also measured.. Ang II increased H(2) O(2) , AT(1) receptor and Nox4 expression and NF-κB activation in the renal medulla, but not in the cortex. Ang II raised plasma and urinary H(2) O(2) levels, increased urinary angiotensinogen but reduced plasma angiotensinogen. PEG-catalase had a short-term antihypertensive effect and transiently suppressed urinary angiotensinogen. PEG-catalase decreased renal medullary expression of AT(1) receptors and Nox4 in Ang II-infused rats. Renal medullary NF-κB activation was correlated with local H(2) O(2) levels and urinary angiotensinogen excretion. Loss of antihypertensive efficacy was associated with an eightfold increase of plasma angiotensinogen.. The renal medulla is a major target for Ang II-induced redox dysfunction. H(2) O(2) appears to be the key mediator enhancing intrarenal RAS activation and decreasing systemic RAS activity. The specific control of renal medullary H(2) O(2) levels may provide future grounds for the treatment of hypertension.

Topics: Angiotensin II; Angiotensinogen; Animals; Biomarkers; Catalase; Gene Expression Regulation; Hydrogen Peroxide; Hypertension; Kidney Diseases; Kidney Medulla; Male; NADH, NADPH Oxidoreductases; NADPH Oxidase 1; NADPH Oxidase 4; NADPH Oxidases; NF-kappa B; Polyethylene Glycols; Rats; Rats, Sprague-Dawley; Receptor, Angiotensin, Type 1; Renin-Angiotensin System

We investigated the impact of heterogeneous nuclear ribonucleoprotein F (hnRNP F) overexpression on angiotensinogen (Agt) gene expression, hypertension, and renal proximal tubular cell (RPTC) injury in high-glucose milieu both in vivo and in vitro. Diabetic Akita transgenic (Tg) mice specifically overexpressing hnRNP F in their RPTCs were created, and the effects on systemic hypertension, Agt gene expression, renal hypertrophy, and interstitial fibrosis were studied. We also examined immortalized rat RPTCs stably transfected with control plasmid or plasmid containing hnRNP F cDNA in vitro. The results showed that hnRNP F overexpression attenuated systemic hypertension, suppressed Agt and transforming growth factor-β1 (TGF-β1) gene expression, and reduced urinary Agt and angiotensin II levels, renal hypertrophy, and glomerulotubular fibrosis in Akita hnRNP F-Tg mice. In vitro, hnRNP F overexpression prevented the high-glucose stimulation of Agt and TGF-β1 mRNA expression and cellular hypertrophy in RPTCs. These data suggest that hnRNP F plays a modulatory role and can ameliorate hypertension, renal hypertrophy, and interstitial fibrosis in diabetes. The underlying mechanism is mediated, at least in part, via the suppression of intrarenal Agt gene expression in vivo. hnRNP F may be a potential target in the treatment of hypertension and kidney injury in diabetes.

Topics: Angiotensinogen; Animals; Diabetes Mellitus, Experimental; Diabetic Nephropathies; Fibrosis; Gene Expression; Heterogeneous-Nuclear Ribonucleoprotein Group F-H; Hypertension; Kidney; Kidney Diseases; Mice; Mice, Transgenic; Renin-Angiotensin System; Transforming Growth Factor beta1

Renal dysfunction due to acute rejection (AR), acute tubular necrosis, or calcineurin inhibitors toxicity is related to development of interstitial fibrosis/tubular atrophy (IF/TA) and graft survival. Determination of serum creatinine (sCr) displays poor sensitivity as a marker for early detection of graft dysfunction. Kidney biopsy is an accurate but invasive procedure for the diagnosis. The levels of urinary mRNA of genes that regulate epithelial-mesenchymal transition (EMT) can reflect early damage and detect the development of IF/TA. Repeated studies of these genes can provide noninvasive information about the evolution of the graft, facilitating early diagnosis and treatment.. To analyze the relationships between early and 1-year graft evolution in relation to gene expression of EMT biomarkers.. Seventy-one kidney transplant recipients were monitored during 1 year recording analytical, clinical, and histological (if available) data. We determined RNA gene expression of EMT, angiotensinogen, E-cadherin, N-cadherin, transforming growth factor (TGF) beta and bone morphogenetic patients 7 (BMP7).. At 3 months, angiotensinogen (mean [standard deviation]), (2.42 [.66] versus 8.58 [3.24]; P = .017) and N-cadherin (0.59 [0.26] versus 3.15 [1.35]; P = .016) discriminate a good evolution from AR episodes BMP-7 discriminated a good evolution versus AR (0.72 [0.29] versus 4.53 [2.23]; P = .006) and delayed graft function versus AR (1.14 [0.79] versus 4.53 [2.23]; P = .049). After 1 year, the ratio TGF-beta/BMP7 discriminated patients with an sCr > 1.5 mg/dL (6614.6 [1063.6] versus 3378.7 [1019]; P = .034). There was a positive correlation between urinary and tissue TGF-beta [r = 59; P = .003].. The expression of studied genes reverting EMT at 3 months postransplantation showed differences in initial graft evolution. At 1 year, the TGF-beta/BMP7 ratio suggested activation of EMT, possible early marker of renal dysfunction.

Topics: Angiotensinogen; Antigens, CD; Bone Morphogenetic Protein 7; Cadherins; Creatinine; Delayed Graft Function; Epithelial-Mesenchymal Transition; Fibrosis; Gene Expression Regulation; Genetic Markers; Humans; Kidney; Kidney Diseases; Kidney Transplantation; RNA, Messenger; Time Factors; Transforming Growth Factor beta; Treatment Outcome

Polycystic ovary syndrome (PCOS) is the most common reproductive dysfunction in premenopausal women. PCOS is also associated with increased risk of cardiovascular disease when PCOS first occurs and later in life. Hypertension, a common finding in women with PCOS, is a leading risk factor for cardiovascular disease. The mechanisms responsible for hypertension in women with PCOS have not been elucidated.. This study characterized the cardiovascular-renal consequences of hyperandrogenemia in a female rat model.. Female Sprague-Dawley rats (aged 4-6 weeks) were implanted with dihydrotestosterone or placebo pellets lasting 90 days. After 10 to 12 weeks, blood pressure (by radiotelemetry), renal function (glomerular filtration rate, morphology, protein, and albumin excretion), metabolic parameters (plasma insulin, glucose, leptin, cholesterol, and oral glucose tolerance test), inflammation (plasma tumor necrosis factor-α), oxidative stress (mRNA expression of nicotinamide adenine dinucleotide phosphate (NADPH) oxidase subunits, p22(phox), p47(phox), gp91(phox), and NOX4), nitrate/nitrite excretion and mRNA expression of components of the renin-angiotensin system (angiotensinogen, angiotensin-I-converting enzyme [ACE], and AT1 receptor) were determined.. Plasma dihydrotestosterone increased 3-fold in hyperandrogenemic female (HAF) rats, whereas plasma estradiol levels did not differ compared with control females. HAF rats exhibited estrus cycle dysfunction. They also had increased food intake and body weight, increased visceral fat, glomerular filtration rate, renal injury, insulin resistance and metabolic dysfunction, oxidative stress, and increased expression of angiotensinogen and ACE and reduced AT1 receptor expression.. The HAF rat is a unique model that exhibits many of the characteristics of PCOS in women and is a useful model to study the mechanisms responsible for PCOS-mediated hypertension.

Topics: Angiotensinogen; Animals; Blood Glucose; Blood Pressure; Cardiovascular Diseases; Dihydrotestosterone; Disease Models, Animal; Estradiol; Female; Glomerular Filtration Rate; Glucose Tolerance Test; Kidney Diseases; Leptin; Metabolic Syndrome; Oxidative Stress; Polycystic Ovary Syndrome; Rats; Rats, Sprague-Dawley; Renin-Angiotensin System

Some studies suggest that polymorphisms in angiotensin-converting enzyme (ACE), angiotensinogen (AGT), angiotensin II type I receptor (AGTR1) and angiotensin II type II receptor (AGTR2) genes may contribute to renal function variation.. Genotyping for single nucleotide polymorphisms (SNPs) in these candidate genes was performed in 2,847 participants from four racial/ethnic groups (African American, Chinese, White and Hispanic) without known cardiovascular disease in the Multi-Ethnic Study of Atherosclerosis. SNP and haplotype analyses were performed to determine associations between genotypes and cross-sectional renal function measurements, including urine albumin excretion (UAE) and estimated glomerular filtration rate (eGFR) using serum creatinine and cystatin C.. Twenty-four ACE SNPs, 10 AGT SNPs, 15 AGTR1 SNPs and 6 AGTR2 SNPs were typed successfully. After adjusting for ancestry, age and gender, 3 SNPs (AGT M235T, AGT rs2148582 and AGTR1 rs2131127) showed associations with an empiric p value <0.05 with the same phenotype in multiple racial/ethnic groups, suggesting replication. The AGT M235T SNP has been shown previously to be associated with diabetic and hypertensive nephropathy.. These data suggest that genetic polymorphisms in the renin-angiotensin system are associated with renal phenotypes in the general population, but that many associations differ across racial/ethnic groups.

Topics: Aged; Angiotensinogen; Atherosclerosis; Cohort Studies; Ethnicity; Female; Genetic Variation; Humans; Kidney Diseases; Kidney Function Tests; Male; Middle Aged; Peptidyl-Dipeptidase A; Phenotype; Polymorphism, Single Nucleotide; Receptor, Angiotensin, Type 1; Receptor, Angiotensin, Type 2; Renin-Angiotensin System

Increased activation of the renin-angiotensin system (RAS) may be important in promoting coronary heart disease (CHD) and renal dysfunction, but limited data are available on associations between angiotensin type 1 receptor (AGT1R) and angiotensinogen (AGT) genotypes in type 2 diabetes.. Study participants were diabetics from the Health Professionals Follow-Up Study (HPFS) and the Nurses' Health Study (NHS). We analyzed single nucleotide polymorphisms (SNPs) associated with cardiovascular pathophysiology (including AGT1R T573C, AGT1R A1166C, and AGT M235T) and presence of renal dysfunction (eGFR<60 ml/min/1.73 m2) or history of CHD.. The AGT1R 1166 C-allele was associated with eGFR<60 ml/min/1.73 m2 (multivariable OR 1.63 [1.01, 2.65]) in the HPFS men (n = 733) and in the combined dataset (n = 1566) (OR 1.42 [1.02, 1.98]). The AGT1R 1166 C-allele was also associated with CHD in men (OR 1.57 [1.10, 2.24]). In NHS women (n = 833), AGT 235T-allele was associated with CHD (OR 1.72 [1.20, 2.47]). Removal of hypertension from the fully adjusted models did not influence results, suggesting that the associations may not be mediated by hypertension. There were significant interactions between sex and AGT1R 1166 C-allele (p = 0.008) and AGT M235T (p = 0.03) in models for CHD. No significant associations were seen between AGT1R T573 C-allele and renal dysfunction or CHD.. Polymorphisms in AGT1R and AGT genes are associated with renal dysfunction and CHD in type 2 diabetes and further support the important role of the RAS in these complications. Sex may modify associations between AGT1R 1166 C-allele and AGT 235T and CHD in type 2 diabetes.

Topics: Adult; Aged; Aged, 80 and over; Alleles; Angiotensinogen; Coronary Disease; Diabetes Mellitus, Type 2; Diabetic Angiopathies; Diabetic Nephropathies; Female; Follow-Up Studies; Gene Frequency; Genotype; Glomerular Filtration Rate; Health Personnel; Humans; Kidney Diseases; Male; Middle Aged; Mutation, Missense; Nurses; Polymorphism, Single Nucleotide; Receptor, Angiotensin, Type 1; Renin-Angiotensin System; Risk; Sex Factors

Kidney androgen-regulated protein (KAP), a proximal tubule androgen-regulated gene, codes for a protein of unknown function.. To investigate the consequences of KAP overexpression in kidney, we produced KAP transgenic mice and performed microarray expression analyses in kidneys of control and transgenic males. Downregulation of the androgen-sensitive Cyp4A14 monooxygenase gene in KAP transgenic mice prompted us to analyze blood pressure levels, and we observed that transgenic mice were hypertensive. Inhibition of 20-hydroxyeicosatetraenoic acid synthesis by N-hydroxy-N'-(4-n-butyl-2-methylphenyl) formamidine (HET0016) reduced the increased 20-hydroxyeicosatetraenoic acid levels in urine and normalized arterial pressure in transgenic mice, as did the NADPH oxidase inhibitor apocynin. Increased oxidative stress in transgenic mice was demonstrated by (1) enhanced excretion of urinary markers of oxidative stress, 8-iso-prostaglandin F2alpha, 8-hydroxydeoxyguanosine, and thiobarbituric acid-reacting substances; (2) augmented mitochondrial DNA damage and malondialdehyde levels in kidneys; and (3) diminished catalase and glutathione peroxidase activity in transgenic kidneys. Mice exhibited renal defects that included focal segmental glomerulosclerosis, proteinuria, glycosuria, and fibrosis.. Taken together, these results indicate that KAP expression is critical for cardiovascular-renal homeostasis maintenance and that hypertension is associated with increased oxidative stress. This is the first report showing that overexpression of an androgen-regulated, proximal tubule-specific gene induces hypertension. These observations may shed light on the molecular pathophysiology of gender differences in the prevalence and severity of hypertension and chronic renal disease.

Topics: Angiotensinogen; Animals; Blood Pressure; Catalase; DNA Damage; Exons; Gene Expression Regulation; Glutathione Peroxidase; Hemodynamics; Humans; Hypertension; Immunohistochemistry; Kidney; Kidney Diseases; Male; Mice; Mice, Transgenic; Microscopy, Confocal; Oligonucleotide Array Sequence Analysis; Oxidative Stress; Polymerase Chain Reaction; Proteins; Reverse Transcriptase Polymerase Chain Reaction; RNA; Superoxide Dismutase

To determine how angiotensin II (Ang II) contributes to renal interstitial fibrosis, the inflammatory response, and tubular cell apoptosis and proliferation in unilateral ureteral obstruction using mice genetically deficient in angiotensinogen (Agt(-/-)).. The left kidney of wild-type mice (WT; C57BL/6) and Agt(-/-) mice was obstructed for 2 weeks, and then both kidneys were harvested. The serum Ang II levels were determined by radioimmunoassay. The expression of transforming growth factor-beta in renal tissue was assessed using enzyme-linked immunosorbent assay. The renal tissue was stained with Masson's trichrome. Renal tubular proliferation and apoptosis was detected by immunostaining for proliferating cell nuclear antigen and single-stranded DNA, respectively. Interstitial leukocyte and macrophage infiltration was investigated by immunostaining for CD45 and F4/80, respectively.. The serum Ang II levels in the Agt(-/-) mice were significantly lower than those in the WT mice (P < .01), and tissue transforming growth factor-beta in the obstructed kidney of Agt(-/-) mice was significantly lower than that in WT mice (P < .05). Interstitial collagen deposition was significantly lower in the Agt(-/-) obstructed kidneys than in the WT obstructed kidneys (P < .01). Tubular proliferation was significantly greater and tubular apoptosis was significantly lower in the Agt(-/-) obstructed kidneys than in the WT obstructed kidneys (P < .01 and P < .01, respectively). Interstitial infiltration by leukocytes and macrophages was significantly lower in the Agt(-/-) obstructed kidneys than in the WT obstructed kidneys (P < .01 and P < .01, respectively).. The results of the present study support the targeting of Ang II as a reasonable approach by which to prevent renal tissue damage in unilateral ureteral obstruction.

Topics: Angiotensin II; Angiotensinogen; Animals; Female; Fibrosis; Kidney Diseases; Mice; Mice, Inbred C57BL; Ureteral Obstruction

In essential hypertensive patients, blunted renal plasma flow responsiveness to angiotensin II suggests a pathologic increase in angiotensin II in the kidneys. This blunting has been associated with the angiotensinogen 235TT genotype. As several measures of renal function decline with age, we sought to determine the interaction of age and genotype on this intermediate phenotype.. Three hundred fifteen participants had renal plasma flow response to subpressor doses of angiotensin II (3 ng/kg/min) measured by para-aminohippuric acid clearance in high-sodium balance. Individuals were divided by median age into young (<45 years) and older (> or =45 years) sets. A subset of participants was also studied after administration of captopril.. Age, baseline renal plasma flow, BMI and angiotensinogen 235 genotype independently predicted renal plasma flow responsiveness to angiotensin II. Renal plasma flow responses were lower in older individuals than younger (P = 0.03, hypertensive patients; P = 0.004, normotensive individuals). Both hypertensive patients and normotensive individuals carrying either angiotensinogen 235MM or MT genotypes showed this inverse association (P = 0.005, hypertensive patients; P = 0.05, normotensive individuals). However, among angiotensinogen 235TT homozygotes the pattern differed: normotensive individuals had a fall in renal vascular responsiveness with age (P = 0.01) but hypertensive patients did not (P = 0.72). Young hypertensive patients already showed blunted responses. Of all genotype subsets, only angiotensinogen 235TT hypertensive patients showed enhancement (P = 0.03) of the renal vascular responsiveness to angiotensin II after captopril.. The angiotensinogen 235TT variant predicts premature blunting of renal vascular responsiveness among young hypertensive patients. This abnormal response is corrected by angiotensin-converting enzyme inhibition. This first report of age and genotype interaction may have important implications in the profiling and management of essential hypertension.

Topics: Adult; Age Factors; Angiotensin II; Angiotensin-Converting Enzyme Inhibitors; Angiotensinogen; Captopril; Female; Genotype; Humans; Hypertension; Kidney; Kidney Diseases; Male; Middle Aged; Phenotype; Polymorphism, Genetic; Renal Circulation; Renin-Angiotensin System; Vasoconstrictor Agents

Controlling hypertension by angiotensin converting enzyme inhibitors (ACEI) or angiotensin receptor blockers (ARB), mechanisms that inhibit later pathway steps in the renin-angiotensin system (RAS), have clinically afforded protection against cardiac and renal disease.. In order to determine if blocking the RAS rate-limiting step of angiotensin II generation via renin inhibition could afford similar end organ protection in a human-relevant preclinical model, this study investigated the cardiac and renal effects of a nonpeptide, piperidine renin inhibitor (RI; 100 mg/kg/day PO) in double transgenic mice (dTGM) which express both human renin and angiotensinogen genes. RI was compared to the ARB, candesartan (3 mg/kg/day PO), and to the ACEI, enalapril (60 mg/kg/day PO) in a 4-week dosing paradigm. These doses of RI, ACEI and ARB were previously found to normalize mean blood pressure (MBP) to 110 + 3, 109 + 7 and 107 + 6 mmHg, respectively, after 1 day of treatment.. In the dTGM, PRA, plasma aldosterone, GFR, microalbuminuria and left ventricular free wall thickness (LVH) were higher than in the wild type C57BL/6 mice. Microalbuminuria and LVH were significantly reduced by 93% and 9% for the RI, 83% and 13% for enalapril and 73% and 6% for candesartan, respectively. PRA and aldosterone were reduced by the RI 56% and 23%, respectively. These results suggest that the RI provides protection against cardiac and renal disease, similar to ARB and ACEI.

Topics: Administration, Oral; Albuminuria; Aldosterone; Angiotensin II Type 1 Receptor Blockers; Angiotensin-Converting Enzyme Inhibitors; Angiotensinogen; Animals; Benzimidazoles; Biphenyl Compounds; Blood Pressure; Cardiotonic Agents; Drug Administration Schedule; Enalapril; Female; Glomerular Filtration Rate; Humans; Hypertrophy, Left Ventricular; Kidney Diseases; Mice; Mice, Inbred C57BL; Mice, Transgenic; Molecular Structure; Piperidines; Quinolines; Renin; Renin-Angiotensin System; Tetrazoles; Time Factors; Ultrasonography

The aim of this study is to examine whether the ACE-I/D, AGT-M235T, and AT1R-A1166C polymorphisms of the renin-angiotensin system (RAS) genes are associated with cardiovascular and renal-related risk factors in Mexican Americans. Study participants (N = 848) were genotyped by Taqman assays. Association analyses were performed by measured genotype approach. Of the phenotypes examined, the ACE-I/D, AGT-M235T, and AT1R-A1166C polymorphisms exhibited significant association with systolic blood pressure, glomerular filtration rate and body mass index, respectively. The data suggest that the polymorphisms examined in the RAS may modulate the risk factors associated with cardiovascular-renal disease.

Topics: Albuminuria; Alleles; Angiotensinogen; Cardiovascular Diseases; Diabetes Mellitus, Type 2; Female; Gene Frequency; Genetic Variation; Genotype; Humans; Hypertension; INDEL Mutation; Kidney Diseases; Male; Mexican Americans; Peptidyl-Dipeptidase A; Polymorphism, Single Nucleotide; Receptor, Angiotensin, Type 1; Renin-Angiotensin System; Risk Factors; Texas

Patients with glycogen storage disease type Ia (GSD-Ia) develop renal disease of unknown etiology despite intensive dietary therapies. This renal disease shares many clinical and pathological similarities to diabetic nephropathy. We studied the expression of angiotensinogen, angiotensin type 1 receptor, transforming growth factor-beta1, and connective tissue growth factor in mice with GSD-Ia and found them to be elevated compared to controls. While increased renal expression of angiotensinogen was evident in 2-week-old mice with GSD-Ia, the renal expression of transforming growth factor-beta and connective tissue growth factor did not increase for another week; consistent with upregulation of these factors by angiotensin II. The expression of fibronectin and collagens I, III, and IV was also elevated in the kidneys of mice with GSD-Ia, compared to controls. Renal fibrosis was characterized by a marked increase in the synthesis and deposition of extracellular matrix proteins in the renal cortex and histological abnormalities including tubular basement membrane thickening, tubular atrophy, tubular dilation, and multifocal interstitial fibrosis. Our results suggest that activation of the angiotensin system has an important role in the pathophysiology of renal disease in patients with GSD-Ia.

Topics: Angiotensin II; Angiotensinogen; Angiotensins; Animals; Connective Tissue Growth Factor; Extracellular Matrix; Fibrosis; Glucose-6-Phosphatase; Glycogen Storage Disease Type I; Immediate-Early Proteins; Intercellular Signaling Peptides and Proteins; Kidney; Kidney Diseases; Mice; Mice, Mutant Strains; Receptor, Angiotensin, Type 1; Transforming Growth Factor beta1

Upper urinary tract obstruction results in tubulointerstitial fibrosis and a progressive decline in renal function. Although several inflammatory mediators have been implicated in the pathophysiology of renal obstruction, the contribution of TNF-alpha to obstruction-induced fibrosis and renal dysfunction has not been thoroughly evaluated. To study this, male Sprague-Dawley rats were subjected to left unilateral ureteral obstruction vs. sham operation. Rats received either vehicle or a pegylated form of soluble TNF receptor type 1 (PEG-sTNFR1) every 84 h. The kidneys were harvested 1, 3, or 7 days postoperatively, and tissue samples were analyzed for TNF-alpha expression (ELISA), macrophage infiltration (ED-1 staining), transforming growth factor-beta(1) expression (ELISA, RT-PCR), collagen I and IV activity (Western Blot, immunohistochemistry), alpha-smooth muscle actin accumulation (immunohistochemistry, Western blot analysis), and angiotensinogen expression (Western blot). In a separate arm, the glomerular filtration rate (inulin clearance) of rats subjected to unilateral ureteral obstruction in the presence of either vehicle or PEG-sTNFR1 was determined. Renal obstruction induced increased tissue TNF-alpha and transforming growth factor-beta(1) levels, collagen I and IV activity, interstitial volume, alpha-smooth muscle actin accumulation, angiotensinogen expression, and renal dysfunction, whereas treatment with PEG-sTNFR1 significantly reduced each of these markers of renal fibrosis. These results demonstrate that TNF-alpha mediates obstruction-induced renal fibrosis and identify TNF-alpha neutralization as a potential therapeutic option for the amelioration of obstruction-induced renal injury.

Topics: Actins; Angiotensinogen; Animals; Biomarkers; Blotting, Western; Collagen Type I; Collagen Type IV; Enzyme-Linked Immunosorbent Assay; Escherichia coli; Fibrosis; Half-Life; Immunohistochemistry; Kidney Cortex; Kidney Diseases; Kinetics; Macrophages; Male; Molecular Weight; Polyethylene Glycols; Protein Structure, Tertiary; Rats; Rats, Sprague-Dawley; Receptors, Tumor Necrosis Factor, Type I; Recombinant Proteins; Solubility; Transforming Growth Factor beta1; Tumor Necrosis Factor-alpha; Ureter; Ureteral Obstruction

We investigated whether or not p38 mitogen-activated protein kinase inhibition ameliorates angiotensin II-induced target organ damage. We used double transgenic rats harboring both human renin and angiotensinogen genes (dTGRs). dTGR, with or without p38 inhibitor (BIRB796; 30 mg/kg per day in the diet), and nontransgenic Sprague-Dawley rats were studied in 2 protocols. In protocol 1 (week 7), systolic blood pressure of untreated dTGRs was 204+/-4 mm Hg, but partially reduced after BIRB796 treatment (166+/-7 mm Hg), whereas Sprague-Dawley rats were normotensive. The cardiac hypertrophy index was unchanged in untreated and BIRB796-treated dTGRs. The beta-myosin heavy chain expression of BIRB796-treated hearts was significantly lower in BIRB796 compared with dTGRs, indicating a delayed switch to the fetal isoform. BIRB796 treatment significantly reduced cardiac fibrosis, connective tissue growth factor, tumor necrosis factor-alpha, interleukin-6, and macrophage infiltration. Albuminuria was not reduced in BIRB796-treated dTGRs. Tubular and glomerular damage with tumor necrosis factor-alpha expression was unaltered, although serum creatinine and cystatin C were normalized. Renal macrophage infiltration, fibrosis, and vessel damage were reduced. In protocol 2 (week 8), we focused on mortality and arrhythmogenic electrical remodeling. Mortality of untreated dTGRs was 100% but was reduced to 10% in the BIRB796 group. Cardiac magnetic field mapping showed prolongation of depolarization and repolarization in untreated dTGRs compared with Sprague-Dawley rats with a partial reduction by BIRB796. Programmed electrical stimulation elicited ventricular tachycardias in 81% of untreated dTGRs but only in 48% of BIRB796-treated dTGRs. In conclusion, BIRB796 improved survival, target organ damage, and arrhythmogenic potential in angiotensin II-induced target organ damage.

Topics: Angiotensin II; Angiotensinogen; Animals; Animals, Genetically Modified; Cardiovascular Diseases; Disease Models, Animal; Kidney Diseases; Male; Naphthalenes; p38 Mitogen-Activated Protein Kinases; Protein Kinase Inhibitors; Pyrazoles; Rats; Rats, Sprague-Dawley; Renin

Chronic allograft nephropathy (CAN) is a cause of graft loss. The multistage processes that result in CAN are poorly understood. Noninvasive assays for detecting allograft dysfunction and predicting long-term outcomes are a priority in transplantation (Tx).. Renal tissue from kidney transplant patients (KTP) with CAN (n=11) and normal kidneys (NK; n=7) were studied using microarrays. Markers resulting from the microarray analysis (transforming growth factor [TGF]-beta, epidermal growth factor receptor [EGFR], angiotensinogen [AGT]) were tested in urine (Ur) and peripheral blood (PB) samples from the CAN patients (collected at the biopsy time) using reverse-transcriptase real-time polymerase chain reaction. Ur and PB samples from long-term KTP with stable renal function (SRF; n=20) were used as control.. Assuming unequal variances between CAN and NK, using a false discovery rate of 0.005, and running 1,000 of all possible permutations, 728 probe sets were differentially expressed. Genes related to fibrosis and extracellular matrix deposition (i.e., TGF-beta, laminin, gamma 2, metalloproteinases-9, and collagen type IX alpha 3) were up-regulated. Genes related to immunoglobulins, B cells, T-cell receptor, nuclear factor of activated T cells, and cytokine and chemokines receptors were also upregulated. EGFR and growth factor receptor activity (FGFR)2 were downregulated in CAN samples. AGT, EGFR, and TGF-beta levels were statistical different in urine but not in blood samples of CAN patients when compared to KTP with SRF (P<0.001, P=0.04, and P<0.001, respectively).. Genes related to fibrosis, extracellular matrix deposition, and immune response were found up-regulated in CAN. Markers resulting from the microarray analysis were differentially expressed in Ur samples of the CAN patients and in concordance with the microarray profiles.

Topics: Adult; Angiotensinogen; Biomarkers; Chronic Disease; ErbB Receptors; Female; Gene Expression Profiling; Gene Expression Regulation; Graft Rejection; Humans; Kidney Diseases; Kidney Transplantation; Male; Middle Aged; RNA, Messenger; Signal Transduction; Transforming Growth Factor beta; Transplantation, Homologous

Steroid refractory acute rejection (SRAR) is a major vital factor in renal transplantation recipients. The pathogenesis of SRAR may involve both immune and non-immune mechanisms. A decreased renal allograft function has also been associated with increased activity of renin-angiotensin-aldosterone system (RAS), which may be genetically determined. A total 206 renal transplant recipients, 116 males and 90 females, were included. The effects of gene polymorphisms of the four components of RAS including angiotensinogen (AGT), angiotensin-converting enzyme (ACE), angiotensin type 1 receptor (AT1R), and aldosterone synthase (CYP11B2) were investigated in 19 cases of renal transplant patients with SRAR. The association between SRAR and the activating antibodies targeting the AT1R were also investigated. Genotyping was performed for the M235T-AGT, the I/D-ACE, the A1166C-AT1R, and the -344T/C-CYP11B2 gene polymorphisms using polymerase chain reaction. Our results showed that renal allograft recipients with SRAR had significantly higher occurrences of the DD genotype of ACE and CC genotype of AT1R than recipients without SRAR. The other genetic polymorphisms of the RAS were not associated with SRAR. Activating antibodies targeting the AT1R were detected in the sera from 14 SRAR victims with malignant hypertension and without anti-HLA antibodies. This study provides evidence that determination before transplantation of the polymorphism of the gene encoding components of RAS may help identify patients who are at risk for SRAR. The detection of the antibodies of AT1R may contribute to the prevention of SRAR.

Topics: Adult; Angiotensinogen; Cytochrome P-450 CYP11B2; Female; Graft Rejection; Humans; Hypertension; Immunosuppressive Agents; Kidney Diseases; Kidney Transplantation; Male; Middle Aged; Peptidyl-Dipeptidase A; Polymorphism, Genetic; Receptor, Angiotensin, Type 1; Renin-Angiotensin System

The renin-angiotensin system (RAS) regulates BP and may affect chronic kidney disease (CKD) through induction of tissue growth and fibrosis. The angiotensinogen (AGT) promoter G(-6) allele lowers transcription and is inversely associated with hypertension. In white individuals, the A1166C 3'-UTR variant of angiotensin II type 1 receptor (AT1R) has been associated with CKD. CKD associations with these RAS genes are uncertain in high-risk black populations. A prospective population-based study of CKD risk was conducted among 3706 black individuals without severe renal dysfunction at baseline (serum creatinine > or =177 micromol/L [2.0 mg/dl] for men, > or =159 micromol/L [1.8 mg/dl] for women) to examine associations with AGT and AT1R. Incident CKD progression was defined as kidney disease hospitalization or increase in serum creatinine level > or =35 micromol/L (0.4 mg/dl) above baseline. During mean follow-up of 10.2 yr, CKD progression incidence rate (per 1000 person-years) was 8.2 (n = 312 cases). Risk was lower for AGT G(-6) carriers compared with A(-6) (incidence 6.9 versus 9.0; log-rank P = 0.03) and nonsignificantly higher among AT1R C1166 carriers. Adjusting for hypertension and major CKD risk factors, AGT G(-6)decreased risk (relative risk 0.75; 95% confidence interval 0.57 to 0.98). AT1R C1166 increased risk only among those with hypertension (relative risk 1.65; 95% confidence interval 1.14 to 2.39). The AGT G(-6)A polymorphism may play a role in CKD progression in black individuals, consistent with in vitro effects on AGT levels and renal remodeling but independent of BP. The AT1R C1166 allele may increase susceptibility but only in the presence of hypertension.

Topics: Angiotensinogen; Atherosclerosis; Black or African American; Chronic Disease; Female; Genetic Variation; Genotype; Humans; Kidney Diseases; Male; Middle Aged; Prospective Studies; Receptor, Angiotensin, Type 1; Renin-Angiotensin System; Risk Assessment

The clinical course of Henoch-Schönlein Purpura (HSP) in children is variable, with some patients having a much more rapidly progressing course than others. We investigated whether polymorphisms of the renin-angiotensin system (RAS) genes are involved in HSP. Three RAS genotypes were examined in 114 children with HSP and in 164 healthy children: the angiotensin I converting enzyme (ACE) insertion/deletion polymorphism, the M235T mutation in the angiotensinogen gene (Agt), and the A1166C in the angiotensin II type I receptor (AT1R) gene. Significant differences were observed between HSP patients and control group in the frequency of ACE and Agt genotypes (p=0.004 and p=0.003, respectively). The TT genotype of Agt gene was associated with a 3.5-fold increased risk for Henoch-Schönlein nephritis (HSN) compared with the MM/MT genotype (odds ratio, 3.5; 95% confidence interval, 1.2-10.4). There was a trend to a higher prevalence of the TT genotype of the Agt gene among patients with nephrotic range proteinuria when compared to the patients with mild proteinuria, although the difference did not reach a statistical significance. The results of this study suggest that polymorphisms of ACE gene and Agt gene likely influence the risk of developing HSP. However, among the three genes of the RAS studies, only Agt gene was associated with the susceptibility to HSN. RAS gene polymorphisms studied are not associated with the presence of nephrotic range proteinuria. Additional studies are warranted to verify the correlation between RAS gene polymorphisms and susceptibility to HSP.

Topics: Adolescent; Alanine; Angiotensinogen; Child; Child, Preschool; Cysteine; DNA Transposable Elements; Female; Gene Deletion; Gene Frequency; Genetic Predisposition to Disease; Genotype; Humans; IgA Vasculitis; Kidney Diseases; Male; Methionine; Nephrotic Syndrome; Peptidyl-Dipeptidase A; Polymorphism, Genetic; Proteinuria; Receptor, Angiotensin, Type 1; Renin-Angiotensin System; Severity of Illness Index; Threonine

Angiotensinogen (ANG) is the sole substrate of the renin-angiotensin system (RAS). Clinical studies have shown that RAS activation may lead to hypertension, a major cardiovascular and renal risk factor. To delineate the underlying mechanisms of hypertension-induced nephropathy, we generated transgenic mice that overexpress rat ANG (rANG) in the kidney to establish whether intrarenal RAS activation alone can evoke hypertension and kidney damage and whether RAS blockade can reverse these effects. Transgenic mice overexpressing renal rANG were generated by employing the kidney-specific, androgen-regulated protein promoter linked to rANG cDNA. This promoter targets rANG cDNA to renal proximal tubules and responds to androgen stimulation. Transgenic mice displayed kidney-specific expression of rANG, significantly increased blood pressure (BP) and albuminuria in comparison to non-transgenic littermates. Administration of losartan (an angiotensin II (type 1)-receptor antagonist) or perindopril (an angiotensin-converting enzyme inhibitor) reversed these abnormalities in transgenic animals. Renal injury was evident on examination of the kidneys in transgenic mice, and attenuated by losartan and perindopril treatment. We conclude that the overproduction of ANG alone in the kidney induces an increase in systemic BP, proteinuria, and renal injury. RAS blockers prevent these abnormalities. These data support the role of the intrarenal RAS in the development of hypertension and renal injury.

Topics: Angiotensin II Type 1 Receptor Blockers; Angiotensin-Converting Enzyme Inhibitors; Angiotensinogen; Animals; Blood Pressure; Blotting, Western; DNA, Complementary; Female; Gene Expression Regulation; Hypertension; Immunohistochemistry; Kidney; Kidney Diseases; Losartan; Male; Mice; Mice, Inbred C57BL; Mice, Transgenic; Perindopril; Proteins; Proteinuria; Rats; Renin-Angiotensin System

Recent findings related to the renin-angiotensin system have provided a more elaborated understanding of the pathophysiology of hypertension and kidney diseases. These findings have led to unique concepts and issues regarding the intrarenal renin-angiotensin system. Angiotensinogen is the only known substrate for renin that is the rate-limiting enzyme of the renin-angiotensin system. Because the level of angiotensinogen in human beings is close to the Michaelis-Menten constant value for renin, changes in angiotensinogen levels can control the activity of the renin-angiotensin system, and its upregulation may lead to elevated angiotensin peptide levels and increases in blood pressure. Enhanced intrarenal angiotensinogen mRNA or protein levels or both have been observed in multiple models of hypertension including angiotensin II-dependent hypertensive rats, Dahl salt-sensitive hypertensive rats, and spontaneously hypertensive rats, as well as in kidney diseases including diabetic nephropathy, immunoglobulin A (IgA) nephropathy, and radiation nephropathy. Renal angiotensinogen is formed primarily in proximal tubular cells and is secreted into the tubular fluid. Urinary angiotensinogen excretion rates show a clear relationship to kidney angiotensin II contents and kidney angiotensinogen levels, suggesting that urinary angiotensinogen may serve as an index of the intrarenal renin-angiotensin system status. Establishment of concise and accurate methods to measure human angiotensinogen may allow clinical studies that would provide important information regarding the roles of intrarenal angiotensinogen in the development and progression of hypertension and kidney diseases.

Topics: Angiotensinogen; Animals; Biomarkers; Humans; Hypertension; Kidney Diseases; Kidney Tubules; Renin-Angiotensin System

This study was performed to determine whether augmented intrarenal angiotensinogen may contribute to the enhanced renal angiotensin II (Ang II) and associated tissue injury in spontaneously hypertensive rats (SHR). SHR and Wistar-Kyoto rats (WKY) were maintained on a normal diet and killed at either 7 or 14 wk of age. Two groups of SHR received either an Ang II type 1 receptor blocker (ARB; olmesartan, 5 mg/d) or a triple therapy (hydralazine 7.5 mg/d, reserpine 0.15 mg/d, and hydrochlorothiazide 3 mg/d [HRH]) during weeks 7 through 14. Systolic BP and renal Ang II were significantly increased in SHR-14 (n = 8) compared with WKY-7, WKY-14, and SHR-7 (n = 8 each), and ARB treatment prevented these increases (n = 8). However, whereas HRH treatment prevented the development of hypertension in SHR, this combination therapy failed to decrease renal Ang II (n = 8). With the use of urine samples or fixed renal sections, renal injuries in rats were quantified in a semiautomated manner by the following six parameters: (1) urinary excretion rate of total protein, (2) glomerular sclerosis, (3) interstitial expansion, (4) and (5) numbers of monocytes/macrophages in interstitium or glomeruli, and (6) arterial proliferation. Angiotensinogen mRNA and protein levels in kidney cortex, measured by real-time reverse transcriptase-PCR and Western blot analysis, respectively, and all six parameters of renal damage were changed in parallel, and ARB treatment also prevented these increases. However, HRH treatment failed to prevent these increases. These results indicate that SHR have enhanced intrarenal angiotensinogen production that contributes to increased Ang II levels leading to the development of hypertension and renal injury in this strain.

Topics: Angiotensin II; Angiotensin II Type 1 Receptor Blockers; Angiotensinogen; Animals; Hypertension; Kidney Diseases; Male; Rats; Rats, Inbred SHR

Aldosterone and angiotensin (Ang) II both may cause organ damage. Circulating aldosterone is produced in the adrenals; however, local cardiac synthesis has been reported. Aldosterone concentrations depend on the activity of aldosterone synthase (CYP11B2). We tested the hypothesis that reducing aldosterone by inhibiting CYP11B2 or by adrenalectomy (ADX) may ameliorate organ damage. Furthermore, we investigated how much local cardiac aldosterone originates from the adrenal gland.. We investigated the effect of the CYP11B2 inhibitor FAD286, losartan, and the consequences of ADX in transgenic rats overexpressing both the human renin and angiotensinogen genes (dTGR). dTGR-ADX received dexamethasone and 1% salt. Dexamethasone-treated dTGR-salt served as a control group in the ADX protocol. Untreated dTGR developed hypertension and cardiac and renal damage and had a 40% mortality rate (5/13) at 7 weeks. FAD286 reduced mortality to 10% (1/10) and ameliorated cardiac hypertrophy, albuminuria, cell infiltration, and matrix deposition in the heart and kidney. FAD286 had no effect on blood pressure at weeks 5 and 6 but slightly reduced blood pressure at week 7 (177+/-6 mm Hg in dTGR+FAD286 and 200+/-5 mm Hg in dTGR). Losartan normalized blood pressure during the entire study. Circulating and cardiac aldosterone levels were reduced in FAD286 or losartan-treated dTGR. ADX combined with dexamethasone and salt treatment decreased circulating and cardiac aldosterone to barely detectable levels. At week 7, ADX-dTGR-dexamethasone-salt had a 22% mortality rate compared with 73% in dTGR-dexamethasone-salt. Both groups were similarly hypertensive (190+/-9 and 187+/-4 mm Hg). In contrast, cardiac hypertrophy index, albuminuria, cell infiltration, and matrix deposition were significantly reduced after ADX (P<0.05).. Aldosterone plays a key role in the pathogenesis of Ang II-induced organ damage. Both FAD286 and ADX reduced circulating and cardiac aldosterone levels. The present results show that aldosterone produced in the adrenals is the main source of cardiac aldosterone.

Topics: Adrenal Glands; Adrenalectomy; Aldosterone; Angiotensin II; Angiotensinogen; Animals; Animals, Genetically Modified; Cytochrome P-450 CYP11B2; Enzyme Inhibitors; Fibrosis; Heart Diseases; Humans; Inflammation; Kidney Diseases; Losartan; Mineralocorticoid Receptor Antagonists; Myocardium; Rats; Renin

Cytochrome P450 (CYP)-dependent arachidonic acid (AA) metabolites are involved in the regulation of renal vascular tone and salt excretion. The epoxygenation product 11,12-epoxyeicosatrienoic acid (EET) is anti-inflammatory and inhibits nuclear factor-kappa B activation. We tested the hypothesis that the peroxisome proliferator-activated receptor-alpha-activator fenofibrate (Feno) induces CYP isoforms, AA hydroxylation, and epoxygenation activity, and protects against inflammatory organ damage. Double-transgenic rats (dTGRs) overexpressing human renin and angiotensinogen genes were treated with Feno. Feno normalized blood pressure, albuminuria, reduced nuclear factor-kappa B activity, and renal leukocyte infiltration. Renal epoxygenase activity was lower in dTGRs compared to nontransgenic rats. Feno strongly induced renal CYP2C23 protein and AA-epoxygenase activity under pathological and nonpathological conditions. In both cases, CYP2C23 was the major isoform responsible for 11,12-EET formation. Moreover, we describe a novel CYP2C23-dependent pathway leading to hydroxy-EETs (HEETs), which may serve as endogenous peroxisome proliferator-activated receptor-alpha activators. The capacity to produce HEETs via CYP2C23-dependent epoxygenation of 20-HETE and CYP4A-dependent hydroxylation of EETs was reduced in dTGR kidneys and induced by Feno. These results demonstrate that Feno protects against angiotensin II-induced renal damage and acts as inducer of CYP2C23-mediated epoxygenase activities. We propose that CYP-dependent EET/HEET production may serve as an anti-inflammatory control mechanism.

Topics: 8,11,14-Eicosatrienoic Acid; Angiotensin II; Angiotensinogen; Animals; Animals, Genetically Modified; Arachidonic Acid; Blotting, Western; Chromatography, Liquid; Cytochrome P-450 CYP2J2; Cytochrome P-450 Enzyme System; Fenofibrate; Humans; Hypertension; Hypolipidemic Agents; Immunohistochemistry; Kidney; Kidney Diseases; Mass Spectrometry; NF-kappa B; Polymerase Chain Reaction; Rats; Receptors, Cytoplasmic and Nuclear; Renin; Transcription Factors; Vasoconstrictor Agents

Locally generated angiotensin II (AngII) may be involved in the pathogenic mechanisms of chronic renal diseases. Renal expression of AngII and other components of the renin-angiotensin system (RAS) were analyzed by immunohistochemistry and Western blot in a model of chronic progressive nephropathy induced by inhibition of nitric oxide synthesis. Renal injury was evaluated by histology and albumin excretion. Systemic RAS status was evaluated through plasma renin activity (PRA) and plasma AngII concentration. In addition, the effects of enalapril, losartan, and mycophenolate mofetil (MMF) on AngII expression in animals with chronic renal disease was also analyzed. Plasma renin activity and plasma AngII were not different between rats with nephropathy and controls (2.08 +/- 0.7 versus 2.03 +/- 0.5 ng/ml/h and 94.3 +/- 18 versus 78.9 +/- 16 fmol/ml, respectively). However, rats with chronic progressive nephropathy showed augmented renal content of angiotensinogen protein (13.5 +/- 3.5 versus 2.2 +/- 0.4 pixels in control rats; P < 0.05), enhanced expression of cathepsin D-a renin-like enzyme-in cortical collecting tubules (103.5 +/- 27.0 versus 66.2 +/- 3.6 cells/mm2 in controls; P < 0.01), and increased expression of AT1 receptor in interstitium (54.7 +/- 7.8 versus 1.3 +/- 0.4 cells/mm2 in controls; P < 0.001). Kidney angiotensin-converting enzyme content did not differ among the groups. Notably, an increased number of interstitial cells expressing AngII was detected in the renal interstitium (9.5 +/- 1.6 versus 1.7 +/- 0.6 cells/mm2 in controls; P < 0.05). Rats treated with Nomega-nitro-L-arginine-methyl-esther and losartan presented a decreased local AngII formation, in contrast to its known effect on plasma AngII. Moreover, mycophenolate mofetil lowered interstitial AngII expression, suggesting that inflammatory signaling may be involved in interstitial AngII generation. This study demonstrates the upregulation of local RAS in the kidney in a model of chronic progressive nephropathy.

Topics: Albumins; Angiotensin-Converting Enzyme Inhibitors; Angiotensinogen; Angiotensins; Animals; Antihypertensive Agents; Blood Pressure; Blotting, Western; Cathepsin D; Enalapril; Enzyme Inhibitors; Glomerulonephritis; Immunohistochemistry; Kidney; Kidney Diseases; Losartan; Male; Mycophenolic Acid; NG-Nitroarginine Methyl Ester; Nitric Oxide; Rats; Rats, Wistar; Renin; Renin-Angiotensin System; Time Factors; Up-Regulation

Genotypes of the renin-angiotensin system have been implicated in essential hypertension and in progression of native kidney diseases, but gene effects on progression in chronic renal allograft dysfunction are unclear.. To examine gene effects on long-term renal allograft function, we conducted a prospective cohort study of 210 nondiabetic renal allograft recipients younger than 36 years of age who underwent transplantation between 1980 and 1993 and were followed up through 1999. All grafts survived more than 1 year and all subjects received cyclosporine-based immunosuppression. DNA was analyzed by polymerase chain reaction for the angiotensin-converting enzyme insertion/deletion and angiotensinogen (AGT) M235T polymorphisms. Linear regression multivariate modeling of the slope of the inverse creatinine-versus-time, survival analyses for time-to-sustained doubling of baseline serum creatinine, time-to-graft loss, and a composite endpoint including patient death were performed.. Mean follow-up time was 8.4+/-3 years. Genotype frequencies for each marker system did not deviate significantly from the Hardy-Weinberg equilibrium. The slope of the inverse creatinine-versus-time for AGT 235T/T and M/T was significantly increased compared with M/M ( <0.0001). The AGT 235T/T genotype was also associated with a shorter time-to-sustained doubling of serum creatinine ( =0.001). When subjects were divided into quartiles based on slope magnitude, the frequency of the AGT 235T/T genotype was overrepresented in the fastest progressing group compared with the slowest ( =0.001). The AGT 235T/T genotype was also associated with shorter time-to-graft loss ( =0.007) and the composite endpoint ( =0.001).. The AGT 235 T allele independently influences long-term decline in renal allograft function.

Topics: Adolescent; Adult; Aged; Angiotensinogen; Child; Child, Preschool; Disease Progression; Genotype; Graft Survival; Humans; Kidney Diseases; Kidney Transplantation; Middle Aged; Transplantation, Homologous

Blockade of the renin-angiotensin system (RAS) is well documented to be renoprotective; however, not all patients with glomerulonephritis respond well to this therapy. The interindividual variation in response to the RAS blockade may be in part genetically determined, whereas the results have been controversial.. We investigated whether the therapeutic efficacy of angiotensin-converting enzyme (ACE) inhibitors and/or angiotensin receptor blocker on renal prognosis is modified by the angiotensinogen gene (AGT) polymorphism in immunoglobulin A nephropathy (IgAN). In total, 259 patients with histologically proven IgAN were analyzed for clinical manifestations, renal survival, and their associations with AGT A(-20)C and M235T.. The renal prognosis of 110 patients, who received ACE inhibitors/angiotensin receptor blocker during their clinical course, was significantly better than those without ACE inhibitors/angiotensin receptor blockers despite higher blood pressures and heavier proteinuria. The Cox proportional hazards regression model showed an increased hazard ratio (HR) for urinary protein (more than 1.0 g/day) of 3.346 (P = 0.0001), hypertension of 1.949 (P = 0.01), deteriorated renal function of 3.040 (P < 0.0001), no ACE inhibitor/angiotensin receptor blocker administration of 2.725 (P = 0.0004), and the T235 and C(-20) haplotype of 1.608 (P = 0.0322). Only in patients carrying at least one M235 and A(-20) haplotype did the administration of ACE inhibitors/angiotensin receptor blockers have no significant effect on the prognosis of renal function (Kaplan-Meier, log rank test, chi2 = 0.700; P = 0.4028), whereas it was significant in patients who had other haplotypes of AGT (chi2 = 11.805; P = 0.0006).. This study provides evidence that the M235T and A(-20)C genotype of AGT can influence the therapeutic efficacy of a RAS blockade on the renal survival in IgAN.

Topics: Adenine; Adult; Alleles; Angiotensin Receptor Antagonists; Angiotensin-Converting Enzyme Inhibitors; Angiotensinogen; Cytoprotection; Female; Gene Frequency; Genetic Variation; Genotype; Glomerulonephritis, IGA; Guanine; Haplotypes; Humans; Kidney; Kidney Diseases; Male; Methionine; Middle Aged; Polymorphism, Genetic; Renin-Angiotensin System; Risk Factors; Threonine

Angiotensin (Ang) II promotes renal infiltration by immunocompetent cells in double-transgenic rats (dTGRs) harboring both human renin and angiotensinogen genes. To elucidate disease mechanisms, we investigated whether or not dexamethasone (DEXA) immunosuppression ameliorates renal damage. Untreated dTGRs developed hypertension, renal damage, and 50% mortality at 7 weeks. DEXA reduced albuminuria, renal fibrosis, vascular reactive oxygen stress, and prevented mortality, independent of blood pressure. In dTGR kidneys, p22phox immunostaining co-localized with macrophages and partially with T cells. dTGR dendritic cells expressed major histocompatibility complex II and CD86, indicating maturation. DEXA suppressed major histocompatibility complex II+, CD86+, dendritic, and T-cell infiltration. In additional experiments, we treated dTGRs with mycophenolate mofetil to inhibit T- and B-cell proliferation. Reno-protective actions of mycophenolate mofetil and its effect on dendritic and T cells were similar to those obtained with DEXA. We next investigated whether or not Ang II directly promotes dendritic cell maturation in vitro. Ang II did not alter CD80, CD83, and MHC II expression, but increased CCR7 expression and cell migration. To explore the role of tumor necrosis factor (TNF)-alpha on dendritic cell maturation in vivo, we treated dTGRs with the soluble TNF-alpha receptor etanercept. This treatment had no effect on blood pressure, but decreased albuminuria, nuclear factor-kappaB activation, and infiltration of all immunocompetent cells. These data suggest that immunosuppression prevents dendritic cell maturation and T-cell infiltration in a nonimmune model of Ang II-induced renal damage. Ang II induces dendritic migration directly, whereas in vivo TNF-alpha is involved in dendritic cell infiltration and maturation. Thus, Ang II may initiate events leading to innate and acquired immune response.

Topics: Angiotensin II; Angiotensinogen; Animals; Animals, Genetically Modified; Antigens, CD; B7-2 Antigen; Blood Pressure; Dendritic Cells; Dexamethasone; Etanercept; Histocompatibility Antigens Class II; Humans; Immunoglobulin G; Immunosuppressive Agents; Inflammation; Kidney; Kidney Diseases; Kinetics; Macrophage Migration-Inhibitory Factors; Male; Membrane Glycoproteins; Membrane Transport Proteins; Mycophenolic Acid; NADPH Dehydrogenase; NADPH Oxidases; NF-kappa B; Phosphoproteins; Protective Agents; Rats; Rats, Sprague-Dawley; Reactive Oxygen Species; Receptors, Tumor Necrosis Factor; Renin; T-Lymphocytes

Hypertension-induced damage of kidney and heart is of major clinical relevance, but its pathophysiology is only partially understood. As there is considerable evidence for involvement of angiotensin II, we generated a new mouse model by breeding angiotensinogen (AOGEN) deficient mice with transgenic animals expressing the rat AOGEN gene only in brain and liver. This genetic manipulation overcame the hypotension of AOGEN-deficient mice and even caused hypertension indistinguishable in its extent from the parent transgenic mice with an intact endogenous AOGEN gene. In contrast to normal mice, however, crossbred animals lacked detectable expression of AOGEN in kidney and heart. As a consequence they showed markedly reduced cardiac hypertrophy and fibrosis. Furthermore, hypertension-induced alterations in kidney histology and function were less pronounced in crossbred mice than in equally hypertensive animals expressing AOGEN locally. The dysmorphogenesis observed in kidneys from AOGEN-deficient mice was absent in mice expressing this gene only in liver and brain. Our results support an important role of local AOGEN expression in hypertension-induced end-organ damage but not in the development of the kidney.

Topics: Angiotensinogen; Animals; Brain; Cardiomegaly; Disease Models, Animal; Fibrosis; Heart Diseases; Hypertension; Kidney Diseases; Liver; Mice; Mice, Transgenic; Myocardium; Organ Size; Organ Specificity; Renin-Angiotensin System

Topics: Angiotensin II; Angiotensinogen; Animals; Animals, Genetically Modified; Aspirin; CD4-Positive T-Lymphocytes; CD8-Positive T-Lymphocytes; Gene Expression; Heart Diseases; Humans; I-kappa B Kinase; Kidney; Kidney Diseases; Macrophages; Monocytes; Myocarditis; Myocardium; Nephritis; NF-kappa B; Protein Serine-Threonine Kinases; Rats; Renin; Transcription Factor AP-1; Vascular Cell Adhesion Molecule-1

Topics: Angiotensin II; Angiotensin-Converting Enzyme Inhibitors; Angiotensinogen; Animals; Disease Models, Animal; Fibrosis; Kidney Diseases; Mice; Plasminogen Activator Inhibitor 1; Renin-Angiotensin System; Transforming Growth Factor beta; Ureteral Obstruction

A novel approach was employed to assess the contribution of the renin-angiotensin system (RAS) to obstructive nephropathy in neonatal mice having zero to four functional copies of the angiotensinogen gene (Agt). Two-day-old mice underwent unilateral ureteral obstruction (UUO) or sham operation; 28 days later, renal interstitial fibrosis and tubular atrophy were quantitated. In all Agt genotypes, UUO reduced ipsilateral renal mass and increased that of the opposite kidney. Renal interstitial collagen increased after UUO linearly with Agt expression, from a fractional area of 25% in zero-copy mice to 54% in two-copy mice. Renal expression of transforming growth factor-beta1 was increased by ipsilateral UUO in mice expressing Agt, but not in zero-copy mice. However, the prevalence of atrophic tubules due to UUO did not vary with Agt expression. Blood pressure was not different in all groups, except for a reduction in sham zero-copy mice. We conclude that a functional RAS is not necessary for compensatory renal growth. This study demonstrates conclusively that angiotensin regulates at least 50% of the renal interstitial fibrotic response in obstructive nephropathy, an effect independent of systemic hemodynamic changes. Angiotensin-induced fibrosis likely is a mechanism common to the progression of many forms of renal disease.

Topics: Angiotensinogen; Animals; Blood Pressure; Body Weight; Collagen; Gene Dosage; Gene Targeting; Kidney Diseases; Kidney Tubules; Mice; Mice, Inbred Strains; Organ Size; Renin-Angiotensin System; RNA, Messenger; Transforming Growth Factor beta; Ureteral Obstruction

1. The role of the renin-angiotensin system (RAS) in cardiac hypertrophy and nephropathy was examined in Tsukuba hypertensive mice (THM) carrying both human renin and angiotensinogen genes. 2. Tsukuba hypertensive mice were treated with 20 mg/kg per day lisinopril, 30 mg/kg per day hydralazine or nothing. Administration of drugs was performed for 6 months from 12 weeks of age; water intake and urine volume were measured and urine albumin excretion, heart to bodyweight ratio and the glomerulosclerosis index were examined. 3. Systolic blood pressure was significantly lowered by treatment with lisinopril and hydralazine. Urine volume, water intake and urinary albumin excretion were significantly decreased by lisinopril. When hydralazine was administered to THM, these parameters were transiently decreased, but eventually reached almost the same levels as those in the untreated group. The heart to bodyweight ratio was significantly decreased by lisinopril, but not by hydralazine. The glomerulosclerosis index was significantly lowered by lisinopril, but the index in the hydralazine group was not significantly different from that in the untreated group. 4. These results suggest that the RAS plays an important role in the progression of cardiac hypertrophy in THM. In addition, the RAS may also play an important role in the progression of nephropathy; however, this may also be partially regulated by elevated blood pressure in the short term.

Topics: Angiotensin II; Angiotensinogen; Animals; Blood Pressure; Cardiomegaly; Humans; Hydralazine; Hypertension; Kidney Diseases; Lisinopril; Mice; Mice, Inbred C57BL; Renin; Renin-Angiotensin System; Survival Rate

Inhibition of angiotensin action, pharmacologically or genetically, during the neonatal period leads to renal anomalies involving hypoplastic papilla and dilated calyx. Recently, we documented that angiotensinogen (Agt -/-) or angiotensin type 1 receptor nullizygotes (Agtr1 -/-) do not develop renal pelvis nor ureteral peristaltic movement, both of which are essential for isolating the kidney from the high downstream ureteral pressure. We therefore examined whether these renal anomalies could be characterized as "obstructive" nephropathy.. Agtr1 -/- neonatal mice were compared with wild-type neonates, the latter subjected to surgical complete unilateral ureteral ligation (UUO), by analyzing morphometrical, immunohistochemical, and molecular indices. Agtr1 -/- mice were also subjected to a complete UUO and were compared with wild-type UUO mice by quantitative analysis. To assess the function of the urinary tract, baseline pelvic and ureteral pressures were measured.. The structural anomalies were qualitatively indistinguishable between the Agtr1 -/- without surgical obstruction versus the wild type with complete UUO. Thus, in both kidneys, the calyx was enlarged, whereas the papilla was atrophic; tubulointerstitial cells underwent proliferation and also apoptosis. Both were also characterized by interstitial macrophage infiltration and fibrosis, and within the local lesion, transforming growth factor-beta 1, platelet-derived growth factor-A and insulin-like growth factor-1 were up-regulated, whereas epidermal growth factor was down-regulated. Moreover, quantitative differences that exist between mutant kidneys without surgical obstruction and wild-type kidneys with surgical UUO were abolished when both underwent the same complete surgical UUO. The hydraulic baseline pressure was always lower in the pelvis than that in the ureter in the wild type, whereas this pressure gradient was reversed in the mutant.. The abnormal kidney structure that develops in neonates during angiotensin inhibition is attributed largely to "functional obstruction" of the urinary tract caused by the defective development of peristaltic machinery.

Topics: Actins; Angiotensin II; Angiotensin-Converting Enzyme Inhibitors; Angiotensinogen; Animals; Animals, Newborn; Apoptosis; Cell Division; Disease Models, Animal; Epidermal Growth Factor; Gene Expression Regulation, Developmental; In Situ Hybridization; In Situ Nick-End Labeling; Insulin-Like Growth Factor I; Kidney Diseases; Kidney Medulla; Kidney Pelvis; Macrophages; Mice; Mice, Knockout; Muscle, Smooth; Peptidyl-Dipeptidase A; Platelet-Derived Growth Factor; Pressure; RNA, Messenger; Transforming Growth Factor beta; Ureter; Ureteral Obstruction

Immunocytochemical studies have revealed that all components of the renin-angiotensin system are widely distributed in human tissues yet the information on the gene expression of the renin-angiotensin system in various types of cell remains scarce.. We explored the presence of a local renin-angiotensin system in human kidney.. We sought to determine the presence of messenger RNA (mRNA) encoding for renin, angiotensinogen, and angiotensin converting enzyme (ACE) in cultured human glomerular cells and human umbilical vein endothelial cells using a two-step polymerase chain reaction. The gene expression of the renin-angiotensin system in normal human kidney and in diseased kidney was studied by in-situ hybridization using synthetic oligonucleotides.. By using a two-step polymerase chain reaction, renin, angiotensinogen, and ACE mRNA were found in cultured mesangial and epithelial cells but only ACE mRNA was present in human umbilical vein endothelial cells. Renin mRNA was detected in juxtaglomerular granular cells and also in glomerular and tubular epithelia in normal kidney by in-situ hybridization. A similar tubular, but not mesangial, distribution was found with angiotensinogen and ACE mRNA. In contrast, stronger signals for renin, angiotensinogen and ACE mRNA were detected in mesangial and epithelial cells of kidney tissues from hypertensive patients and from patients with renal pathology characterized by mesangial proliferation (immunoglobulin A nephropathy, diabetes mellitus, or lupus nephritis).. That gene expression of the renin-angiotensin system occurs in resident glomerular cells supports the hypothesis that there is a local renin-angiotensin system in human kidney. Our findings support the previous speculation that the renin-angiotensin system could be a local factor involved in the progression of chronic renal failure and consequent development of hypertension.

Topics: Angiotensinogen; Base Sequence; Cells, Cultured; DNA Primers; Gene Expression; Humans; In Situ Hybridization; Kidney; Kidney Diseases; Kidney Glomerulus; Peptidyl-Dipeptidase A; Polymerase Chain Reaction; Renin; Renin-Angiotensin System; RNA, Messenger

This study examined the association between the development of nephropathy in non-insulin-dependent diabetes mellitus (NIDDM) patients and M235T polymorphism in the angiotensinogen gene. White NIDDM patients with diabetic nephropathy (case subjects, n = 117) and patients without any evidence of nephropathy and > or = 10 years of NIDDM (control subjects, n = 125) were selected from among patients of the Joslin Diabetes Center and examined. In addition to a standardized examination, blood was drawn for DNA and determination of M235T genotypes at the angiotensinogen locus. For the angiotensinogen gene, the frequency of the genotype 235T/235T, known to be associated with essential hypertension, was higher among case subjects with nephropathy than in control subjects without this complication. This difference, expressed as the odds ratio for nephropathy among 235T/235T homozygotes in comparison with all other genotypes, was 2.2 (95% confidence interval, 1.1 to 4.4). The difference, however, was confined to men (odds ratio, 4.8; 95% confidence interval, 1.5 to 14.9), with the distribution of genotypes in case and control subjects being equal among women (odds ratio, 1.1). DNA polymorphism M235T in the angiotensinogen gene, which is associated with higher expression of this gene, contributes to the risk of diabetic nephropathy in NIDDM men but not in women.

Topics: Adult; Angiotensinogen; Case-Control Studies; Diabetes Mellitus, Type 2; Diabetic Nephropathies; Female; Gene Frequency; Genotype; Humans; Hypertension; Kidney Diseases; Male; Middle Aged; Odds Ratio; Point Mutation; Polymorphism, Genetic; Sex Factors

To evaluate the relation of tissue-localized angiotensin II (Ang II) concentration with cardiac hypertrophy and glomerulosclerosis in Tsukuba hypertensive mice (THM) carrying both human renin and angiotensinogen genes.. Thirty THM aged 12 weeks were distributed equally to a lisinopril dosage group, a hydralazine dosage group, and an untreated group. Ten age-matched C57BL/6 mice were used as normal controls. Administration was performed for 8 weeks from 12 weeks of age. All mice were euthanized at 20 week of age, and the heart-to-body weight ratio, the renal glomerulosclerosis score, tissue Ang II concentration and tissue catecholamine concentration were measured.. In the untreated group, a significant increase in every examination item was found as compared with that in C57BL/6 mice. In the lisinopril group, the observed value of every item was significantly lower than that in the untreated group. In the hydralazine group, tissue Ang II and catecholamine concentrations and the heart-to-body weight ratio were not different from those in the untreated group. Although the glomerulosclerosis score in the hydralazine group was significantly less than that in the untreated group, this was significantly higher than that in the lisinopril group.. Tissue Ang II concentration is more important than hypertension in causing cardiac hypertrophy, and both tissue Ang II level and hypertension are important in causing glomerulosclerosis in THM.

Topics: Angiotensin II; Angiotensinogen; Animals; Antihypertensive Agents; Blood Pressure; Cardiomegaly; Catecholamines; Humans; Hydralazine; Hypertension; Kidney Diseases; Lisinopril; Mice; Mice, Inbred C57BL; Mice, Transgenic; Renin

The aim of this study was to determine whether elements of the human renin-angiotensin system (RAS) could functionally replace elements of the mouse RAS by complementing the reduced survival and renal abnormalities observed in mice carrying a gene-targeted deletion of the mouse angiotensinogen gene (mAgt). Double transgenic mice containing the human renin (HREN) and human angiotensinogen (HAGT) genes were bred to mice heterozygous for the mAgt deletion and the compound heterozygotes were identified and intercrossed. The resulting progeny (n = 139) were genotyped at each locus and the population was stratified into two groups: the first containing both human transgenes (RA+) and the second containing zero or one, but not both human transgenes (RA-). Despite appropriate Mendelian ratios of RA- mice that were wildtype (+/+), heterozygous (+/-), and homozygous (-/-) for the deletion of mAgt at birth, there was reduced survival of RA- mAgt-/- mice to adulthood (P < 0.001 by chi2). In contrast, we observed appropriate Mendelian ratios of RA+ mAgt+/+, RA+ mAgt+/-, and RA+ mAgt-/- mice at birth and in adults (P > 0.05 by chi2). These results demonstrate that the presence of both human transgenes rescues the postnatal lethality in mAgt-/- mice. The renal histopathology exhibited by RA- mAgt-/- mice, including thickened arterial walls, severe fibrosis, lymphocytic infiltration, and atrophied parenchyma, was also rescued in the RA+ mAgt-/- mice. Direct arterial blood pressure recordings in conscious freely moving mice revealed that BP (in mmHg) varied proportionally to mAgt gene copy number in RA+ mice (approximately 20 mmHg per mAgt gene copy, P < 0.001). BP in RA+ mAgt-/- mice (132+/-3, n = 14) was intermediate between wild-type (RA- mAgt+/+, 105+/-2, n = 9) and RA+ mAgt+/+ (174+/-3, n = 10) mice. These studies establish that the human renin and angiotensinogen genes can functionally replace the mouse angiotensinogen gene, and provides proof in principle that we can examine the regulation of elements of the human RAS and test the significance of human RAS gene variants by a combined transgenic and gene targeting approach.

Topics: Angiotensinogen; Animals; Breeding; Female; Genes, Lethal; Genetic Complementation Test; Genotype; Humans; Hypotension; Kidney Diseases; Male; Mice; Mice, Inbred C57BL; Mice, Transgenic; Pedigree; Phenotype; Renin; Transgenes

Ten patients with hepatorenal syndrome were evaluated before and after creation of a side-to-side portacaval shunt or insertion of a peritoneovenous shunt, procedures which produced an increase in plasma volume and cardiac output. In the seven patients who survived surgery, renal function improved significantly, plasma renin activity fell from high to normal levels, and low levels of plasma renin substrate increased. Prior to surgery, blockade of angiotension II by saralasin produced hypotension and an increase in plasma renin activity, whereas after surgery, saralasin had no effect on blood pressure or renin. Our findings suggest that decreased "effective" plasma volume may be important in the stimulation of renin release and possibly in the pathophysiology of renal failure in the hepatorenal syndrome.

Topics: Angiotensinogen; Blood Pressure; Creatinine; Female; Hemodynamics; Humans; Kidney Diseases; Liver Diseases; Male; Middle Aged; Plasma Volume; Portacaval Shunt, Surgical; Renin; Saralasin

Topics: 18-Hydroxydesoxycorticosterone; Adenoma; Adolescent; Adrenal Cortex Neoplasms; Adrenal Glands; Adult; Aged; Aging; Angiotensin II; Angiotensinogen; Carbon Dioxide; Corticosterone; Desoxycorticosterone; Female; Humans; Hyperaldosteronism; Hypertension; Kidney; Kidney Diseases; Male; Middle Aged; Potassium; Renin; Sodium; Urea; Vascular Diseases

Sheep renin substrate was prepared 28% pure, labelled with 125I and then diluted in concentrated unlabelled sheep substrate. Ten percent of the 125I-label was released as a small fragment on incubation with excess human renin. Adequate separation of the labelled fragment from the parent protein was accomplished with charcoal precipitation or gel filtration. Renin concentration in human plasma was assayed by incubating the 125I-labelled substrate with plasma under zero-order kinetic conditions. Renin was assayed in plasma that had been either acidified or untreated. The acidification procedure was employed to activate inactive renin which accounted for more than half of the total plasma renin concentration. The results of this radiochemical assay correlated closely with the results of bioassay. Specificity of the method was established with antirenin. The assay was sufficiently sensitive to measure suppressed plasma renin levels. The iodinated substrate was stable on storage at -10 degrees C over a six-month period. Because of its high affinity for human renin, ease of purification and stability of the iodinated product, sheep substrate provides a convenient means for routine determination of plasma renin concentration by radiochemical assay.

Topics: Angiotensin II; Angiotensinogen; Biological Assay; Charcoal; Humans; Iodine Radioisotopes; Kidney Diseases; Kinetics; Nephrectomy; Renin