adrenomedullin and Kidney-Diseases

Intermedin/adrenomedullin-2 (IMD/AM2) belongs to the calcitonin gene-related peptide (CGRP) / adrenomedullin (AM) family. The biological actions of this family are attributed to their actions at three receptor subtypes comprising the calcitonin receptor-like receptor (CLR) complexed with one of three receptor activity modifying proteins. In contrast to AM and CGRP, IMD binds non-selectively to all three receptor subtypes: CGRP, AM1, AM2. The peptide displays an overlapping but differential and more restricted distribution across the healthy systemic and pulmonary vasculature, heart and kidney relative to CGRP and AM. This, combined with tissue, regional and cell-type specific receptor expression, underpins differences in regard to magnitude, potency and duration of haemodynamic, cardiac and renal effects of IMD relative to those of AM and CGRP, and receptor-subtype involvement. In common with other family members, IMD protects the mammalian vasculature, myocardium and kidney from acute ischaemia-reperfusion injury, chronic oxidative stress and pressure-loading; IMD inhibits apoptosis, attenuates maladaptive tissue remodelling and preserves cardiac and renal function. Robust upregulation of IMD expression in rodent models of cardiovascular and renal disease argues strongly for the pathophysiological relevance of this particular counter-regulatory peptide. Such findings are likely to translate well to the clinic: early reports indicate that IMD is expressed in and protects cultured human vascular and cardiac non-vascular cells from simulated ischaemia-reperfusion injury, primarily via the AM1 receptor, and may have utility as a plasma biomarker in cardiovascular disease. These observations should provide the rationale for short-term administration of the peptide in acute disease, including myocardial infarction, cerebrovascular insult, cardiac and renal failure.

Topics: Adrenomedullin; Animals; Calcitonin Gene-Related Peptide; Cardiovascular Diseases; Cardiovascular System; Humans; Inflammation; Kidney Diseases; Lung Diseases; Organ Specificity; Oxidative Stress; Peptide Hormones; Protective Agents; Receptors, Adrenomedullin; Receptors, Calcitonin Gene-Related Peptide; Reperfusion Injury

Topics: Adrenomedullin; Animals; Blood Pressure; Genetic Therapy; Humans; Hypertension; Kidney Diseases; Kidney Tubules; Peptides; Receptors, Adrenomedullin; Receptors, Peptide; Renal Circulation; Vasodilation

Adrenomedullin (AM) is a peptide that possesses potentially beneficial properties. Since the initial discovery of the peptide by Kitamura et al. in 1993, the literature has been awash with reports describing its novel mechanisms of action and huge potential as a therapeutic target. Strong evidence now exists that AM is able to act as an autocrine, paracrine, or endocrine mediator in a number of biologically significant functions, including the endothelial regulation of blood pressure, protection against organ damage in sepsis or hypoxia, and the control of blood volume through the regulation of thirst. Its early promise as a potential mediator/modulator of disease was not, however, entirely as a result of the discovery of physiological functions but due more to the observation of increasing levels measured in plasma in direct correlation with disease progression. In health, AM circulates at low picomolar concentrations in plasma in 2 forms, a mature 52-amino acid peptide and an immature 53-amino acid peptide. Plasma levels of AM have now been shown to be increased in a number of pathological states, including congestive heart failure, sepsis, essential hypertension, acute myocardial infarction, and renal impairment. These earliest associations have been further supplemented with evidence of a role for AM in other pathologies including, most intriguingly, cancer. In this review, we offer a timely review of our current knowledge on AM and give a detailed account of the putative role of AM in those clinical areas in which the best therapeutic opportunities might exist.

Topics: Adrenomedullin; Animals; Cardiovascular Diseases; Clinical Trials as Topic; Diabetes Mellitus; Humans; Inflammation; Kidney Diseases; Neoplasms; Neovascularization, Pathologic; Peptides; Sepsis

Topics: Adrenomedullin; Animals; Antioxidants; Cardiovascular Diseases; Disease Models, Animal; Homozygote; Humans; Insulin Resistance; Kidney Diseases; Mice; Mice, Knockout; Oxidative Stress; Peptides

Topics: Adrenomedullin; Calcitonin Receptor-Like Protein; Cell Division; Cyclic AMP; Diuresis; Fibrosis; Genetic Therapy; Glomerular Mesangium; Humans; Hypertension, Renal; Intracellular Signaling Peptides and Proteins; Kidney; Kidney Diseases; Membrane Proteins; Natriuresis; Nitric Oxide; Peptides; Receptor Activity-Modifying Proteins; Receptors, Calcitonin; Renal Artery; Vasodilation

Topics: Adrenomedullin; Amino Acid Sequence; Humans; Kidney Diseases; Molecular Sequence Data; Peptides

Adrenomedullin (AM), a potent vasorelaxing, natriuretic and cell growth-modulating peptide, is thought to act as an autocrine/paracrine regulator in renal glomeruli and tubules. AM receptors comprise the calcitonin receptor-like receptor (CRLR) and a family of receptor-activity-modifying proteins (RAMPs 1-3); however, the pathophysiological role of AM and its receptor system in the kidney remains to be clarified. We examined the regulation of their expression in a rat model of renal injury and found that RAMP1, RAMP2 and CRLR expressions were markedly upregulated upon induction of fibrosis during obstructive nephropathy. Since AM exerts potent antiproliferative effects in various cell types, upregulation of the AM receptor system may play important roles in modulating the progression of renal diseases.

Topics: Adrenomedullin; Animals; Cells, Cultured; Humans; Kidney; Kidney Diseases; Peptides; Receptors, Adrenomedullin; Receptors, Peptide

Topics: Adrenomedullin; Animals; Humans; Kidney; Kidney Diseases; Membrane Proteins; Peptide Fragments; Peptides; Proteins; Receptors, Adrenomedullin; Receptors, Peptide; Tissue Distribution

Renal fibrosis promotes the progression of chronic renal disease to end-stage renal disease. Microvascular damage and loss play an important role in renal fibrosis. Intermedin (IMD) is expressed mainly in the heart and kidney. IMD has been shown to increase renal blood flow and reduce the loss of glomerular and surrounding renal tubules, but its role in mediating microvascular damage in renal fibrosis remains to be elucidated. Here, we investigated the effects of IMD on microvascular damage in a renal fibrosis model.. We created a rat model of unilateral ureteral obstruction (UUO) to clarify the effect of microvascular damage on renal fibrosis and the effect of intermedin on reversing renal vascular injury and promoting angiogenesis. Rats were divided randomly into three groups: sham, UUO, and UUO + IMD. The sham group underwent free ureteral ligation but not occlusion. Rats in the latter two groups underwent UUO, and rats in the IMD group were additionally administered intermedin (100 ng/kg/h) daily. On the 7th, 14th, 21st, and 28th days after surgery, abdominal aortic blood and the obstructed kidneys were harvested from the rats (n = 6) for analysis.. IMD was found to protect against renal vascular injury and to increase microvessel density. Molecularly, IMD upregulated vascular endothelial growth factor-vascular endothelial growth factor receptor (VEGF-VEGFR2) pathway activity. The VEGF-VEGFR2 pathway might be the underlying mechanism mediating the protective activities of IMD in promoting angiogenesis, delaying renal fibrosis, and improving renal function.. IMD could be a potential candidate treatment for renal fibrosis.

Topics: Adrenomedullin; Animals; Disease Models, Animal; Fibrosis; Kidney; Kidney Diseases; Kidney Tubules; Male; Neovascularization, Pathologic; Neuropeptides; Rats; Rats, Wistar; Up-Regulation; Ureteral Obstruction; Vascular Endothelial Growth Factor A; Vascular Endothelial Growth Factor Receptor-2

Intermedin [IMD, adrenomedullin-2 (ADM-2)] attenuates renal fibrosis by inhibition of oxidative stress. However, the precise mechanisms remain unknown. Heme oxygenase-1 (HO-1), an antioxidant agent, is associated with antifibrogenic effects. ADM is known to induce HO-1. Whether IMD has any effect on HO-1 is unclear. Herein, we determined whether the antifibrotic properties of IMD are mediated by induction of HO-1.. Renal fibrosis was induced by unilateral ureteral obstruction (UUO) performed on male Wistar rats. Rat proximal tubular epithelial cell line (NRK-52E) was exposed to rhTGF-β1 (10 ng/ml) to establish an in vitro model of epithelial-mesenchymal transition (EMT). IMD was over-expressed in vivo and in vitro using the vector pcDNA3.1-IMD. Zinc protoporphyrin (ZnPP) was used to block HO-1 enzymatic activity. IMD effects on HO-1 expression in the obstructed kidney of UUO rat and in TGF-β1-stimulated NRK-52E were analyzed by real-time RT-PCR, Western blotting or immunohistochemistry. HO activity in the obstructed kidney, contralateral kidney of UUO rat and NRK-52E was examined by measuring bilirubin production. Renal fibrosis was determined by Masson trichrome staining and collagen I expression. Macrophage infiltration and IL-6 expression were evaluated using immunohistochemical analysis. In vivo and in vitro EMT was assessed by measuring α-smooth muscle actin (α-SMA) and E-cadherin expression using Western blotting or immunofluorescence, respectively.. HO-1 expression and HO activity were increased in IMD-treated UUO kidneys or NRK-52E. The obstructed kidneys of UUO rats demonstrated significant interstitial fibrosis on day 7 after operation. In contrast, kidneys that were treated with IMD gene transfer exhibited minimal interstitial fibrosis. The obstructed kidneys of UUO rats also had greater macrophage infiltration and IL-6 expression. IMD restrained infiltration of macrophages and expression of IL-6 in UUO kidneys. The degree of EMT was extensive in obstructed kidneys of UUO rats as indicated by decreased expression of E-cadherin and increased expression of α-SMA. In vitro studies using NRK-52E confirmed these observations. EMT was suppressed by IMD gene delivery. However, all of the above beneficial effects of IMD were eliminated by ZnPP, an inhibitor of HO enzyme activity.. This study demonstrates that IMD attenuates renal fibrosis by induction of HO-1.

Topics: Adrenomedullin; Animals; Cells, Cultured; Enzyme Induction; Fibrosis; Gene Transfer Techniques; Heme Oxygenase (Decyclizing); Kidney Diseases; Male; Neuropeptides; Random Allocation; Rats; Rats, Wistar; Ureteral Obstruction

NADPH oxidase Nox4-derived reactive oxygen species (ROS) play important roles in renal fibrosis. Our previous study demonstrated that intermedin (IMD) alleviated unilateral ureteral obstruction (UUO)-induced renal fibrosis by inhibition of ROS. However, the precise mechanisms remain unclear. Herein, we investigated the effect of IMD on Nox4 expression and NADPH oxidase activity in rat UUO model, and explored if these effect were achieved through cAMP-PKA pathway, the important post-receptor signal transduction pathway of IMD, in TGF-β1-stimulated rat proximal tubular cell (NRK-52E). Renal fibrosis was induced by UUO. NRK-52E was exposed to rhTGF-β1 to establish an in vitro model of fibrosis. IMD was overexpressed in the kidney and in NRK-52E by IMD gene transfer. We studied UUO-induced ROS by measuring dihydroethidium levels and lipid peroxidation end-product 4-hydroxynonenal expression. Nox4 expression in the obstructed kidney of UUO rat or in TGF-β1-stimulated NRK-52E was measured by quantitative RT-PCR and Western blotting. We analyzed NADPH oxidase activity using a lucigenin-enhanced chemiluminescence system. We showed that UUO-stimulated ROS production was remarkably attenuated by IMD gene transfer. IMD overexpression inhibited UUO-induced up-regulation of Nox4 and activation of NADPH oxidase. Consistent with in vivo results, TGF-β1-stimulated increase in Nox4 expression and NADPH oxidase activity was blocked by IMD. In NRK-52E, these beneficial effects of IMD were abolished by pretreatment with N-[2-(p-bromocinnamylamino)ethyl]-5-isoquinolinesulfonamide hydrochloride (H-89), a PKA inhibitor, and mimicked by a cell-permeable cAMP analog dibutyl-cAMP. Our results indicate that IMD exerts anti-oxidant effects by inhibition of Nox4, and the effect can be mediated by cAMP-PKA pathway.

Topics: 8-Bromo Cyclic Adenosine Monophosphate; Adrenomedullin; Aldehydes; Animals; Cell Line; Cyclic AMP; Cyclic AMP-Dependent Protein Kinases; Ethidium; Fibrosis; Gene Transfer Techniques; Isoquinolines; Kidney; Kidney Diseases; Lipid Peroxidation; Male; NADPH Oxidase 4; Neuropeptides; Oxidative Stress; Rats; Rats, Wistar; Reactive Oxygen Species; Real-Time Polymerase Chain Reaction; Signal Transduction; Sulfonamides; Transforming Growth Factor beta1; Up-Regulation

We explored the prognostic value of three circulating candidate biomarkers-midregional-proadrenomedullin (MR-proADM), soluble tumor necrosis factor receptor 1 (sTNFR1), and N-terminal prohormone brain natriuretic peptide (NT-proBNP)-for change in renal function in patients with type 2 diabetes.. Outcomes were defined as renal function loss (RFL), ≥40% decline of estimated glomerular filtration rate (eGFR) from baseline, and rapid renal function decline (RRFD), absolute annual eGFR slope <-5 mL/min/year. We used a proportional hazard model for RFL and a logistic model for RRFD. Adjustments were performed for established risk factors (age, sex, diabetes duration, HbA. Among 1,135 participants (mean eGFR 76 mL/min, median uACR 2.6 mg/mmol, and median GFR slope -1.6 mL/min/year), RFL occurred in 397, RRFD developed in 233, and 292 died during follow-up. Each biomarker predicted RFL and RRFD. When combined, MR-proADM, sTNFR1, and NT-proBNP predicted RFL independently from the established risk factors (adjusted hazard ratio 1.59 [95% CI 1.34-1.89],. In addition to established risk factors, MR-proADM, sTNFR1, and NT-proBNP improve risk prediction of loss of renal function in patients with type 2 diabetes.

Topics: Adrenomedullin; Aged; Albumins; Biomarkers; Body Mass Index; Creatinine; Diabetes Mellitus, Type 2; Female; Follow-Up Studies; France; Glomerular Filtration Rate; Humans; Kidney Diseases; Kidney Function Tests; Logistic Models; Male; Middle Aged; Natriuretic Peptide, Brain; Peptide Fragments; Prognosis; Proportional Hazards Models; Prospective Studies; Receptors, Tumor Necrosis Factor, Type I; Risk Factors

Transforming growth factor-β1 (TGF-β1) plays a pivotal role in the progression of renal fibrosis. Reactive oxygen species mediate profibrotic action of TGF-β1. Intermedin (IMD) has been shown to inhibit oxidative stress, but its role in renal fibrosis remains unclear. Here, we investigated the effects of IMD on renal fibrosis in a rat model of unilateral ureteral obstruction (UUO).. The expression of IMD and its receptors, calcitonin receptor-like receptor (CRLR) and receptor activity-modifying proteins (RAMP1/2/3), in the obstructed kidney was detected by real-time polymerase chain reaction (PCR), western blotting and immunohistochemistry. To evaluate the effects of IMD on renal fibrosis, we locally overexpressed exogenous IMD in the obstructed kidney using an ultrasound-microbubble-mediated delivery system. Renal fibrosis was determined by Masson trichrome staining. The expression of TGF-β1, connective tissue growth factor (CTGF), α-smooth muscle actin (α-SMA) and fibronectin was measured. Smad2/3 activation and macrophage infiltration were evaluated. We also studied oxidative stress by measuring superoxide dismutase (SOD) activity and malondialdehyde (MDA) content.. mRNA and protein expression of IMD increased after UUO. CRLR, RAMP1, RAMP2 and RAMP3 were also induced by ureteral obstruction. IMD overexpression remarkably attenuated UUO-induced tubular injury and blunted fibrotic response as shown by decreased interstitial collagen deposition and downregulation of fibronectin. Macrophage infiltration, α-SMA and CTGF upregulation caused by UUO were all relieved by IMD, whereas TGF-β1 upregulation and Smad2/3 activation were not affected. Meanwhile, we noted increased oxidative stress in obstruction, which was also attenuated by IMD gene delivery.. Our results indicate that IMD is upregulated after UUO. IMD plays a protective role in renal fibrosis via its antioxidant effects.

Topics: Adrenomedullin; Animals; Calcitonin Receptor-Like Protein; Collagen; Disease Models, Animal; Fibronectins; Fibrosis; Genetic Therapy; Kidney; Kidney Diseases; Male; Microbubbles; Neuropeptides; Oxidative Stress; Rats, Wistar; Receptor Activity-Modifying Protein 1; Receptor Activity-Modifying Protein 2; Receptor Activity-Modifying Protein 3; RNA, Messenger; Signal Transduction; Smad2 Protein; Smad3 Protein; Time Factors; Transfection; Transforming Growth Factor beta1; Ultrasonics; Up-Regulation; Ureteral Obstruction

Vasopressin, endothelin and adrenomedullin are vasoactive peptides that regulate vascular tone and might play a role in hypertensive diseases. Recently, laboratory assays have been developed to measure stable fragments of vasopressin, endothelin and adrenomedullin. Little is known about their diagnostic and prognostic value in hemodialysis patients. In this study, we measured the plasma concentration of copeptin, mid-regional-pro-adrenomedullin (MR-pro-ADM) and C-terminal pro-endothelin 1 (CT-pro-ET1) in stable ambulatory hemodialysis patients (n = 239) and investigated their associations with clinical factors and mortality. In all patients enrolled, the plasma concentrations of copeptin, MR-pro-ADM and CT-pro-ET1 were largely elevated with a median concentration of 132 pmol/L (interquartile range [IQR] 78-192) for copeptin, 1.26 nmol/L (IQR 1.02-1.80) for MR-pro-ADM and 149 pmol/L (IQR 121-181) for CT-pro-ET1. The plasma concentrations of all vasoactive peptide fragments correlated with time on dialysis and plasma β2-microglobulin concentration and were negatively correlated to residual diuresis. The plasma concentration of MR-pro-ADM was a strong predictor of all-cause (univariate hazard ratio for a 10-fold increase 9.94 [3.14;32], p<0.0001) and cardiovascular mortality (hazard ratio 34.87 [5.58;217], p = 0.0001) within a 3.8-year follow-up. The associations remained stable in models adjusted for dialysis specific factors and were attenuated in a full model adjusted for all prognostic factors. Plasma copeptin concentration was weakly associated with cardiovascular mortality (only in univariate analysis) and CT-pro-ET1 was not associated with mortality at all. In conclusion, vasoactive peptide fragments are elevated in hemodialysis patients because of accumulation and, most likely, increased release. Increased concentrations of MR-pro-ADM are predictive of mortality.

Topics: Adrenomedullin; Aged; Cause of Death; Comorbidity; Endothelin-1; Female; Follow-Up Studies; Glycopeptides; Humans; Kidney Diseases; Male; Middle Aged; Peptide Fragments; Prognosis; Prospective Studies; Protein Precursors; Renal Dialysis

Various bioactive peptides have been implicated in the homeostasis of organs and tissues. Adrenomedullin (AM) is a peptide with various bioactivities. AM-receptor, calcitonin-receptor-like receptor (CLR) associates with one of the subtypes of the accessory proteins, RAMPs. Among the RAMP subisoforms, only RAMP2 knockout mice ⁻/⁻ reproduce the phenotype of embryonic lethality of AM⁻/⁻, illustrating the importance of the AM-RAMP2-signaling system. Although AM and RAMP2 are abundantly expressed in kidney, their function there remains largely unknown. We used genetically modified mice to assess the pathophysiological functions of the AM-RAMP2 system. RAMP2⁺/⁻ mice and their wild-type littermates were used in a streptozotocin (STZ)-induced renal injury model. The effect of STZ on glomeruli did not differ between the 2 types of mice. On the other hand, damage to the proximal urinary tubules was greater in RAMP2⁺/⁻. Tubular injury in RAMP2⁺/⁻ was resistant to correction of blood glucose by insulin administration. We examined the effect of STZ on human renal proximal tubule epithelial cells (RPTECs), which express glucose transporter 2 (GLUT2), the glucose transporter that specifically takes up STZ. STZ activated the endoplasmic reticulum (ER) stress sensor protein kinase RNA-like endoplasmic reticulum kinase (PERK). AM suppressed PERK activation, its downstream signaling, and CCAAT/enhancer-binding homologous protein (CHOP)-induced cell death. We confirmed that the tubular damage was caused by ER stress-induced cell death using tunicamycin (TUN), which directly evokes ER stress. In RAMP2⁺/⁻ kidneys, TUN caused severe injury with enhanced ER stress. In wild-type mice, TUN-induced tubular damage was reversed by AM administration. On the other hand, in RAMP2⁺/⁻, the rescue effect of exogenous AM was lost. These results indicate that the AM-RAMP2 system suppresses ER stress-induced tubule cell death, thereby exerting a protective effect on kidney. The AM-RAMP2 system thus has the potential to serve as a therapeutic target in kidney disease.

Topics: Adrenomedullin; Animals; Antibiotics, Antineoplastic; Cell Death; Cell Line; eIF-2 Kinase; Endoplasmic Reticulum Stress; Humans; Kidney Diseases; Kidney Glomerulus; Kidney Tubules, Proximal; Mice; Mice, Knockout; Receptor Activity-Modifying Protein 2; Streptozocin

Intermedin/adrenomedullin 2 (IMD/ADM2) is a newly discovered peptide closely related to adrenomedullin. We recently reported that IMD/ADM2 gene transfer could significantly reduce renal ischaemia/reperfusion injury. In this study, we evaluated the effect of IMD/ADM2 on cell proliferation and regeneration in a cultured rat renal tubular epithelial cell line (NRK-52E) of hypoxia-reoxygenation (H/R) injury.. The H/R model in NRK-52E cells consisted of hypoxia for 1 h and reoxygenation for 2 h. IMD/ADM2 was overexpressed in NRK-52E cells using the vector pcDNA3.1-IMD. Enzyme-linked immunosorbent assays were used to measure the concentration of IMD/ADM2 in the culture medium, and real-time PCR and Western blotting were used to determine mRNA and protein levels. In addition, luciferase reporter assays and electrophoretic mobility-shift assays were performed to measure cyclin D1 promoter activity and transcription factor activity.. We found that IMD/ADM2 gene transfer markedly promoted cell viability and decreased lactate dehydrogenase (LDH) activity and cell apoptosis compared with that of H/R. IMD/ADM2 increased the phosphorylation of ERK and decreased the phosphorylation of JNK and P38. Furthermore, IMD/ADM2 promoted cell cycle progression with concomitant increases in the levels of cyclin D1 and cyclin E, and these effects were blocked by the inhibition of ERK, or the agonist JNK and P38. IMD/ADM2 also increased cyclin D1 promoter activity and AP-1 DNA-binding activity.. We demonstrated that IMD/ADM2 promotes renal cell proliferation and regeneration after renal H/R injury by upregulating cyclin D1 and that this upregulation seems to be mediated by the ERK, JNK, and P38 MAPK signalling pathways.

Topics: Adrenomedullin; Animals; Apoptosis; Cell Hypoxia; Cell Line; Cell Proliferation; Cell Survival; Cyclin D1; Cyclin E; Enzyme Activation; Extracellular Signal-Regulated MAP Kinases; Genes, Reporter; JNK Mitogen-Activated Protein Kinases; Kidney Diseases; Kidney Tubules; L-Lactate Dehydrogenase; MAP Kinase Signaling System; p38 Mitogen-Activated Protein Kinases; Phosphorylation; Promoter Regions, Genetic; Rats; Regeneration; Reperfusion Injury; RNA, Messenger; Transcription Factor AP-1; Transfection; Up-Regulation

Acute renal failure secondary to ischemia and reperfusion (I/R) injury poses a significant burden on both surgeons and patients. It carries a high morbidity and mortality rate and no specific treatment currently exists. Major causes of renal I/R injury include trauma, sepsis, hypoperfusion, and various surgical procedures. We have demonstrated that adrenomedullin (AM), a novel vasoactive peptide, combined with AM binding protein-1 (AMBP-1), which augments the activity of AM, is beneficial in various disease conditions. However, it remains unknown whether human AM/AMBP-1 provides any beneficial effects in renal I/R injury. The objective of our study therefore was to determine whether administration of human AM/AMBP-1 can prevent and/or minimize damage in a rat model of renal I/R injury.. Male adult rats were subjected to renal I/R injury by bilateral renal pedicle clamping with microvascular clips for 60 min followed by reperfusion. Human AM (12 microg/kg BW) and human AMBP-1 (40 microg/kg BW) or vehicle (52 microg/kg BW human albumin) were given intravenously over 30 min immediately following the clip removal (i.e., reperfusion). Rats were allowed to recover for 24 h post-treatment, and blood and renal tissue samples were collected. Plasma levels of AM were measured using a radioimmunoassay specific for rat AM. Plasma AMBP-1 was measured by Western analysis. Renal water content and serum levels of systemic markers of tissue injury were measured. Serum and renal TNF-alpha levels were also assessed.. At 24 h after renal I/R injury, plasma levels of AM were significantly increased while plasma AMBP-1 was markedly decreased. Renal water content and systemic markers of tissue injury (e.g., creatinine, BUN, AST, and ALT) were significantly increased following renal I/R injury. Serum and renal TNF-alpha levels were also increased post injury. Administration of human AM/AMBP-1 decreased renal water content, and plasma levels of creatinine, BUN, AST, and ALT. Serum and renal TNF-alpha levels were also significantly decreased after AM/AMBP-1 treatment.. Treatment with human AM/AMBP-1 in renal I/R injury significantly attenuated organ injury and the inflammatory response. Thus, human AM combined with human AMBP-1 may be developed as a novel treatment for patients with acute renal I/R injury.

Topics: Adrenomedullin; Alpha-Globulins; Animals; Complement Factor H; Humans; Kidney; Kidney Diseases; Male; Proteins; Rats; Reperfusion Injury; Tumor Necrosis Factor-alpha; Vasodilator Agents; Water

Mechanical ventilation (MV) is a life-saving intervention in acute respiratory failure without any alternative. However, even protective ventilation strategies applying minimal mechanical stress may evoke ventilator-induced lung injury (VILI). Adjuvant pharmacological strategies in addition to lung-protective ventilation to attenuate VILI are lacking. Adrenomedullin exhibited endothelial barrier-stabilising properties in vitro and in vivo.. In untreated mice (female C57/Bl6 mice, 11-15 weeks old) and animals treated with adrenomedullin, lung permeability, local and systemic inflammation and markers of distal organ function were assessed following 2 or 6 h of mechanical ventilation with 100% oxygen and protective or moderately injurious ventilator settings, respectively.. Adrenomedullin dramatically reduced lung permeability in VILI in mice, leading to improved oxygenation. Adrenomedullin treatment reduced myosin light chain phosphorylation, attenuated the accumulation of leucocytes in the lung and prevented the increase in lactate and creatinine levels in mice ventilated with high tidal volumes. Moreover, adrenomedullin protected against VILI even when treatment was initiated 2 h after the beginning of mechanical ventilation in a 6 h VILI mouse model.. Adjuvant treatment with adrenomedullin may be a promising new pharmacological approach to attenuate VILI.

Topics: Adrenomedullin; Animals; Bronchodilator Agents; Capillary Permeability; Cytokines; Drug Evaluation, Preclinical; Female; Kidney Diseases; Lactic Acid; Leukocyte Count; Lung; Mice; Mice, Inbred C57BL; Oxygen Consumption; Phosphorylation; Pulmonary Alveoli; Respiration, Artificial; Ventilator-Induced Lung Injury

The interplay between the heart and the kidneys has received widespread attention in recent years. A novel five-class definition of cardiorenal syndromes has been proposed. The ability of two markers of cardiac dysfunction to predict progression of primary kidney disease, described by Dieplinger and his co-workers, highlights the prognostic importance of the chronic cardiorenal (types 2 and 4) syndromes.

Topics: Adrenomedullin; Age Factors; Atrial Natriuretic Factor; Biomarkers; Creatinine; Disease Progression; Glomerular Filtration Rate; Heart; Heart Failure; Humans; Kidney; Kidney Diseases; Kidney Failure, Chronic; Proteinuria; Sex Factors

Systemic administration of the potent vasodilating peptide adrenomedullin reduces cardiac and renal fibrosis in hypertensive animals. Here, we investigated the effects of kidney-specific adrenomedullin gene delivery in normotensive rats after unilateral ureteral obstruction, an established model of renal tubulointerstitial fibrosis. Overexpression of exogenous adrenomedullin in the renal interstitium following ureteral obstruction significantly prevented fibrosis and proliferation of tubular and interstitial cells. In this model, there is upregulation of connective tissue growth factor (CTGF) mRNA expression and extracellular signal-regulated kinase (ERK) phosphorylation, and adrenomedullin overexpression suppressed both of these activities without altering the blood pressure. In NRK-49F renal fibroblasts, adrenomedullin reduced transforming growth factor-beta-induced CTGF and fibronectin mRNA upregulation through the cyclic AMP/protein kinase A signaling pathway, and suppressed ERK phosphorylation and cell proliferation. In the kidneys with an obstructed ureter, adrenomedullin receptor gene expression was upregulated along with cyclic AMP production in kidney slices. The latter effect was partially blocked by a neutralizing antibody to adrenomedullin, indicating that an endogenous peptide-receptor system was activated. Our results show that overexpression of exogenous adrenomedullin in the ureteral-obstructed kidney prevents tubulointerstitial fibrosis and cell proliferation through the cyclic AMP-mediated decrease of CTGF induction and ERK phosphorylation.

Topics: Adrenomedullin; Animals; Connective Tissue Growth Factor; Extracellular Signal-Regulated MAP Kinases; Fibrosis; Gene Expression Regulation; Humans; Immediate-Early Proteins; Intercellular Signaling Peptides and Proteins; Kidney Diseases; Male; Rats; Rats, Wistar; Transfection

Although adrenomedullin is an indicator of cardiac dysfunction in haemodialysis patients, the clinical significance of midregional proadrenomedullin has not been elucidated. Objectives. We evaluated whether midregional proadrenomedullin reflects cardiac dysfunction, systemic inflammation or blood volume in haemodialysis patients.. Plasma midregional proadrenomedullin, C-reactive protein and delta body weight (indicating excessive blood volume), and two-dimensional as well as Doppler echocardiographic variables were measured just before haemodialysis in 70 patients with cardiovascular disease.. The median value of midregional proadrenomedullin was 1.93 nmol/l before haemodialysis, and these levels were significantly reduced following haemodialysis. Log [midregional proadrenomedullin] was positively correlated with left ventricular end-systolic volume index, diameter of inferior vena cava, C-reactive protein and delta body weight (r = 0.328, r = 0.421, r = 0.356, r = 0.364), and negatively with blood pressure, deceleration time of an early diastolic filling wave, pulmonary venous flow velocity ratio and left ventricular ejection fraction (r = -0.330, r = -0.324, r = -0.479, r = -0.373). Multivariate regression analysis revealed that pulmonary venous flow velocity ratio, diameter of inferior vena cava and C-reactive protein were independently related factors for midregional proadrenomedullin concentration.. Plasma midregional proadrenomedullin levels increase in association with cardiac dysfunction, systemic inflammatory status and systemic blood volume in haemodialysis patients with concomitant cardiovascular disease.

Topics: Adrenomedullin; Aged; Blood Volume; Body Weight; C-Reactive Protein; Echocardiography; Female; Heart Diseases; Humans; Inflammation; Kidney Diseases; Male; Middle Aged; Prospective Studies; Protein Precursors; Proteins; Renal Dialysis

Despite its safety and efficacy, the traumatic effects of high-energy shock waves (HESW) on renal morphology and function during long-term follow-up have yet to be elucidated. Although the main target of shock waves is the stone located in the kidney, the surrounding tissue and other organs are also subjected to trauma during this procedure. In contrast to renal blood flow evaluation after shock wave treatment, ischemic development, causing varying degrees of damage at the tissue level, has not been well evaluated. The renoprotective peptide adrenomedullin (AM) is a potent vasorelaxing, natriuretic and cell growth modulating peptide, which is thought to act as an autocrine/paracrine regulator in renal glomeruli and tubules. In this experimental study, renal parenchymal AM levels were assessed in an attempt to evaluate the effect of HESW on the tissue levels of this peptide, which may be responsible for the regulation of ischemia induced by extracorporeal shock wave lithotripsy(ESWL), in a rabbit model. Thirty white New Zealand rabbits, each weighing 3-5 kg were used. The animals were divided into three main groups, and varying numbers of shock waves (1000, 1500, 2000) were applied under fluoroscopic localization to the same kidney of all animals. Ketamine HCl anesthesia was administered (15-20 mg/kg) and all of the procedures were performed with a Multimed 2000 lithotriptor. Untreated contralateral kidneys were evaluated as controls. Following HESW application, the treated and untreated kidneys of each animal were removed through bilateral flank incisions under ketamine HCl anesthesia after 24 h and 7 days, respectively. Tissue AM levels were assessed with immunohistochemistry. During the early follow-up period (24 h), both treated and untreated kidneys showed a moderate to high degree of AM positivity. The number of tubules stained with AM increased as the number of shock waves increased and the expression of this protein became evident, possibly due to a higher degree of tissue damage. Additionally, a limited degree of AM positivity was noted in the contralateral kidneys although this was not as evident as the positivity seen in the treated kidneys. Assessment of tissue AM levels during late follow-up (7 days) in both kidneys demonstrated a moderate or limited degree of positivity in the treated kidneys. Limited or no positivity could be demonstrated in the contralateral kidneys at this time. Taking the certain traumatic effects of HESW, which causes tr

Topics: Adrenomedullin; Animals; Ischemia; Kidney; Kidney Diseases; Lithotripsy; Peptides; Rabbits; Renal Circulation

Topics: Adrenomedullin; Animals; Antihypertensive Agents; Autocrine Communication; Cardiotonic Agents; Heart; Heart Diseases; Humans; Kidney; Kidney Diseases; Mice; Mice, Knockout; Mice, Transgenic; Paracrine Communication; Peptides

Adrenomedullin (AM) is a potent vasodilator and natriuretic peptide with hypotensive effects. Immunoreactive AM in human plasma consists of the biologically active mature form, AM (1-52)-CONH2 (mAM) and the intermediate form, AM-gly-COOH (iAM). However, the different effects of mAM and iAM in patients on haemodialysis (HD) have remained unclear.. Thirty-nine patients on HD and 10 controls were included in this study. We determined plasma levels of mAM and iAM using an immunoradiometric assay that recognizes total AM (tAM) and another that is specific for only mAM.. The plasma concentrations of mAM and iAM in patients before HD were significantly higher than those in the controls (n=10) (4.76+/-0.28 vs 1.28+/-0.22 fmol/ml, P<0.001, 25.99+/-1.47 vs 8.52+/- 0.91 fmol/ml, P<0.001 respectively). The plasma levels of mAM and iAM before HD significantly and negatively correlated with systolic blood pressure (SBP) (r=-0.46, P<0.01, and r=-0.32, P<0.05 respectively) and diastolic blood pressure (DBP) (r=-0.32, P<0.05, and r=-0.35, P<0.05 respectively). After HD, plasma mAM and iAM levels as well as SBP and DBP were significantly lower than before HD. Plasma levels of mAM and iAM correlated significantly (r=0.73, P<0.001).. These data suggest that mAM and/or iAM are involved in blood pressure regulation in patients undergoing HD, and further work is needed to understand the precise role of adrenomedullin in this regulation.

Topics: Adrenomedullin; Adult; Aged; Aged, 80 and over; Blood Pressure; Female; Humans; Immunoassay; Kidney Diseases; Male; Middle Aged; Peptides; Renal Dialysis

We investigated the potential roles of adrenomedullin (AM) in cardiovascular and renal function by somatic gene delivery. We showed that a single intravenous injection of the human AM gene under the control of cytomegalovirus promoter/enhancer induces a prolonged delay in blood pressure rise for several weeks in spontaneously hypertensive rats, Dahl salt-sensitive, DOCA-salt, and two-kidney one-clip hypertensive rats as compared to their respective controls injected with a reporter gene. Expression of the human AM transcript was identified in the heart, kidney, lung, liver and aorta of the rat after adenovirus-mediated AM gene delivery by RT-PCR followed by Southern blot analysis. Immunoreactive human AM levels were measured in rat plasma and urine following AM gene delivery. AM gene delivery induced significant reduction of left ventricular mass in these hypertensive animal models. It also reduces urinary protein excretion and increases glomerular filtration rate, renal blood flow and urinary cAMP levels. AM gene transfer attenuated cardiomyocyte diameter and interstitial fibrosis in the heart, and reduced glomerular sclerosis, tubular disruption, protein cast accumulation and renal cell proliferation in the kidney. In the rat model with myocardial ischemia/reperfusion injury, AM gene delivery significantly reduced myocardial infarction, apoptosis, and superoxide production. Furthermore, local AM gene delivery significantly inhibited arterial thickening, promoted re-endothelialization and increased vascular cGMP levels in rat artery after balloon angioplasty. Collectively, these results indicate that human AM gene delivery attenuates hypertension, myocardial infarction, renal injury and cardiovascular remodeling in animal models via cAMP and cGMP signaling pathways. These findings provide new insights into the role of AM in cardiovascular and renal function.

Topics: Adenoviridae; Adrenomedullin; Animals; Cardiomegaly; Cardiomyopathies; Disease Models, Animal; Gene Transfer Techniques; Genetic Therapy; Genetic Vectors; Humans; Hypertension; Kidney Diseases; Male; Myocardial Infarction; Peptides; Rats; Rats, Inbred Dahl; Rats, Inbred SHR; Streptozocin; Tunica Intima; Ventricular Remodeling

Adrenomedullin (AM) is a potent vasodilator and natriuretic peptide that plays an important role in cardiorenal function. In this study, we explored the potential protective role of AM in volume-dependent hypertension by somatic gene delivery. Adenovirus containing the human AM cDNA under the control of the cytomegalovirus promoter/enhancer was administered into deoxycorticosterone acetate (DOCA)-salt hypertensive rats via tail vein injection. A single injection of the human AM gene resulted in a prolonged reduction of blood pressure with a maximal reduction of 41 mm Hg 9 days after gene delivery. Human AM gene delivery enhanced renal function, as indicated by a 3-fold increase in renal blood flow and a 2-fold increase in glomerular filtration rate (n=5, P<0.05). Histological examination of the kidney revealed a significant reduction in glomerular sclerosis, tubular injury, luminol protein cast accumulation, and interstitial fibrosis as well as urinary protein. Human AM gene delivery caused significant decreases in left ventricular weight and cardiomyocyte diameter, which were accompanied by reduced interstitial fibrosis and extracellular matrix formation within the heart. Expression of human AM mRNA was detected in the kidney, adrenal gland, heart, aorta, lung, and liver; immunoreactive human AM levels were measured in urine and plasma. Significant increases in urinary and cardiac cAMP levels were observed in DOCA-salt rats receiving the human AM gene, indicating activation of the AM receptor. These findings showed that AM gene delivery attenuates hypertension, protects against cardiac remodeling and renal damage in volume-overload hypertension, and may have significance in therapeutic applications in cardiovascular and renal diseases.

Topics: Adenoviridae; Adrenomedullin; Animals; Cardiomegaly; Cyclic AMP; Cyclic GMP; Desoxycorticosterone; Disease Models, Animal; Fibrosis; Gene Transfer Techniques; Genetic Therapy; Genetic Vectors; Humans; Hypertension; Kidney Diseases; Male; Peptides; Rats; Rats, Sprague-Dawley; Systole

Topics: Adrenomedullin; Animals; Antihypertensive Agents; Endothelium, Vascular; Heart Diseases; Humans; Hypertension; Kidney Diseases; Peptides; Vasodilator Agents

Adrenomedullin is a novel hypotensive peptide recently discovered in human pheochromocytoma. In the present study, we measured the plasma immunoreactive adrenomedullin of healthy subjects and patients with various diseases. Immunoreactive adrenomedullin was found to circulate in blood of the healthy subjects at a considerable concentration (3.3 +/- 0.3 fmol/ml). Plasma adrenomedullin was significantly increased in the patients with congestive heart failure (5.4 +/- 0.3 fmol/ml), essential hypertension (5.3 +/- 0.4 fmol/ml) and renal disease (4.9 +/- 0.4 fmol/ml). In healthy volunteers physical exercise significantly increased the plasma adrenomedullin concentration. The increase of adrenomedullin was inversely related to systolic blood pressure. These findings indicate that adrenomedullin participates in the circulation control in both physiological and diseased conditions. Although the exact origin of circulating adrenomedullin is still unknown, it is thought to be released rapidly by acute exercise, thereby regulating the cardiovascular system by its vasodilating activity.

Topics: Adrenomedullin; Antihypertensive Agents; Exercise; Heart Diseases; Humans; Hypertension; Kidney Diseases; Male; Peptides; Radioimmunoassay; Reference Values