adrenomedullin and Diabetic-Nephropathies

The studies concerning the structure and variations of the human adrenomedullin (AM) gene are reviewed, and their relations to the gene function and genetic predisposition to cardiovascular diseases are discussed. The genomic human AM gene is composed of four exons, and the whole nucleotide sequence corresponding to mature AM resides in the fourth exon. In chromosomal sublocalization, the AM gene is located in the distal portion of the short arm of chromosome 11 (11p15.1-3). Analysis of the promoter region of the AM gene has revealed that two transcription factors, nuclear factor for interleukin-6 expression (NF-IL6) and activator protein 2 (AP-2), participate in the regulation of AM gene expression. It is surmised that NF-IL6 mediates inflammatory stimuli and AP-2 mediates signals of phospholipase C and protein kinase C activation. In addition to these factors, hypoxia induces AM gene expression via the hypoxia inducible factor-1 (HIF-1) binding site. The 3'-end of the AM gene is flanked by a microsatellite marker of cytosine adenine (CA) repeats. In Japanese, there are four types of alleles with different CA-repeat numbers: 11, 13, 14 and 19. It is suggested that existence of the 19-repeat allele is associated with genetic predispositions to develop essential hypertension and diabetic nephropathy.

Topics: Adrenomedullin; Diabetic Nephropathies; Heart Failure; Humans; Hypertension, Renal; Peptides; Polymorphism, Genetic

Intermedin(IMD) is a novel member of the calcitonin/calcitonin gene-related peptide (CT/CGRP) family that has anti-inflammatory, antioxidant and anti-apoptosis properties. This study aimed to evaluate the renoprotective effects of IMD on podocyte apoptotic loss and slit diaphragm protein deficiency the kidneys of rats with in streptozotocin (STZ) induced diabetes in high glucose-exposed podocytes. Our results showed that IMD significantly attenuated proteinuria, and alleviated the abnormal alterations in glomerular ultrastructure in vivo. IMD also improved the induction of slit diaphragm proteins, and restored the decreased Bcl-2 expression and suppressed Bax and caspase-3 induction in the diabetic glomeruli. In addition, IMD attenuated podocyte apoptosis and filamentous actin (F-actin) rearrangement in high glucose-exposed podocytes. Exposure to high glucose elevated the unfolded protein response (UPR) to endoplasmic reticulum (ER) stress in renal podocytes, and IMD treatment blocked such ER stress responses pertinent to podocyte apoptosis and reduced synthesis of slit diaphragm proteins in vivo and in vitro. These observations demonstrate that targeting ER stress is an underlying mechanism of IMD-mediated amelioration of diabetes-associated podocyte injury and dysfunction.

Topics: Adrenomedullin; Animals; bcl-2-Associated X Protein; Caspase 3; Diabetes Mellitus, Experimental; Diabetic Nephropathies; Disease Models, Animal; Endoplasmic Reticulum Stress; Glucose; Male; Podocytes; Proto-Oncogene Proteins c-bcl-2; Random Allocation; Rats; Streptozocin; Unfolded Protein Response

Production of adrenomedullin (ADM), a vasodilator peptide, increases in response to ischemia and hypoxia in the vascular wall and the kidney. This may be an adaptive response providing protection against organ damage. We investigated the hypothesis that ADM has a nephroprotective effect in two prospective cohorts of patients with type 2 diabetes recruited in France. The highest tertile of plasma MR-proADM (a surrogate for ADM) concentration at baseline was associated with the risk of renal outcomes (doubling of plasma creatinine concentration and/or progression to end-stage renal disease) during follow-up in both cohorts. Four SNPs in the ADM gene region were associated with plasma MR-proADM concentration at baseline and with eGFR during follow-up in both cohorts. The alleles associated with lower eGFR were also associated with lower plasma MR-proADM level. In conclusion, plasma MR-proADM concentration was associated with renal outcome in patients with type 2 diabetes. Our data suggest that the ADM gene modulates the genetic susceptibility to nephropathy progression. Results are consistent with the hypothesis of a reactive rise of ADM in diabetic nephropathy, blunted in risk alleles carriers, and with a nephroprotective effect of ADM. A possible therapeutic effect of ADM receptor agonists in diabetic renal disease would be worth investigating.

Topics: Adrenomedullin; Aged; Aged, 80 and over; Cohort Studies; Creatinine; Diabetes Mellitus, Type 2; Diabetic Nephropathies; Disease Progression; Female; Genetic Predisposition to Disease; Genetic Variation; Glomerular Filtration Rate; Humans; Kidney Failure, Chronic; Male; Middle Aged; Peptide Fragments; Prospective Studies; Protein Precursors; Renal Insufficiency, Chronic

The implication of pro-angiogenic factors including vascular endothelial growth factor (VEGF) and its receptor flk-1 has been reported in diabetic nephropathy as early event. Adrenomedullin (AM), a potent vasodilator peptide, enhances angiogenesis and high levels were seen in diabetic animals and humans. However, its exact role in diabetic nephropathy is unclear. The present study investigated the effects of adrenomedullin receptor antagonist (ADM-52-22) on the early phase angiogenesis-induced diabetic nephropathy.. 28 male Wistar rats were divided into: 1) Control non-diabetic, 2) Streptozotocin (STZ)-induced diabetic rats (55 mg/kg, i.p.), 3) Control non-diabetic+ADM-52-22, and 4) STZ-diabetes+ADM-52-22 (7 per group). ADM-52-22 was infused for two weeks (250 µg/rat/day, i.p.).. Diabetes caused an increase in kidney weight, renal VEGF levels, 24 hr urinary protein and nitric oxide excretion and hyperfiltration indicated by creatinine clearance (CrCl). ADM-22-52 reduced the rise in CrCl, total urinary protein and renal hypertrophy in diabetic rats, and attenuated early angiogenic response to diabetes: CD31 staining, flk1 protein and VEGF renal levels.. These results show that AM through its receptor mediates early angiogenesis-induced diabetic nephropathy which attributes to the early changes as hyperfiltration and hypertrophy.

Topics: Adrenomedullin; Animals; Diabetes Mellitus, Experimental; Diabetic Nephropathies; Kidney; Male; Neovascularization, Pathologic; Rats; Rats, Wistar; Receptors, Adrenomedullin; Streptozocin; Vascular Endothelial Growth Factor A

Adrenomedullin has an antioxidative action and protects organs in various diseases. To clarify the role of adrenomedullin in diabetic nephropathy, we investigated the NADPH oxidase expression, renin-secreting granular cell (GC) hyperplasia, and glomerular matrix expansion in the streptozotocin (STZ)-induced diabetic adrenomedullin gene knockout (AMKO) mice compared with the STZ-diabetic wild mice at 10 weeks. The NADPH oxidase p47phox expression and lipid peroxidation products were enhanced in the glomeruli of the diabetic mice compared with that observed in the controls in both wild and AMKO mice. These changes were more obvious in the AMKO mice than in the wild mice. Glomerular mesangial matrix expansion was more severe in the diabetic AMKO mice than in the diabetic wild mice and exhibited a positive correlation with the degree of lipid peroxidation products in the glomeruli. Proteinuria was significantly higher in the diabetic AMKO mice than in the diabetic wild mice. The GC hyperplasia score and the renal prorenin expression were significantly increased in the diabetic AMKO mice than in the diabetic wild mice, and a positive correlation was observed with the NADPH oxidase expression in the macula densa. The endogenous adrenomedullin gene exhibits an antioxidant action via the inhibition of NADPH oxidase probably by suppressing the local renin-angiotensin system.

Topics: Adrenomedullin; Animals; Diabetes Mellitus, Experimental; Diabetic Nephropathies; Kidney; Lipid Peroxidation; Mice; Mice, Knockout; NADPH Oxidases; Renin; Renin-Angiotensin System

Subjects with type 2 diabetes are at risk for vascular injury. Several vasoactive factors (e.g., angiotensin) have been implicated. We hypothesize that adrenomedullin, a novel vascoactive factor, is deranged in subjects with type 2 diabetes.. Using a new immunoluminometric method, plasma midregional proadrenomedullin (MR-proADM) was measured in four groups of Chinese subjects: healthy (n = 100, fasting plasma glucose [FPG] <5.6 mmol/l), impaired fasting glucose (IFG) (n = 60, FPG 5.6-6.9 mmol/l), and diabetic subjects with (n = 100) and without (n = 100) nephropathy. Resting forearm cutaneous microcirculatory perfusion (RCMP) was quantified in vivo using 2-dimensional laser Doppler flowmetry. We investigated the relationship between plasma MR-proADM concentrations, multiple metabolic factors, and vascular function.. We observed a stepwise increase in MR-proADM among the groups: healthy group mean +/- SD 0.27 +/- 0.09, IFG group 0.29 +/- 0.13, diabetic group 0.42 +/- 0.13, and diabetic nephropathy group 0.81 +/- 0.54 nmol/l (diabetic vs. healthy and IFG groups, P = 0.04; and diabetic nephropathy group vs. all, P < 0.01). Statistical adjustment for sex, age, BMI, and blood pressure did not affect the conclusions. Multiple linear regression analysis revealed that highly sensitive C-reactive protein (beta = 0.11; P = 0.01), insulin resistance index (beta = 0.20; P = 0.001), LDL cholesterol (beta = 0.31; P < 0.001), and adiponectin (beta = 0.33; P < 0.001) were significant predictors of plasma MR-proADM concentrations among nondiabetic individuals. Among subjects with diabetes, plasma MR-proADM concentrations correlated significantly with RCMP (r = 0.43, P = 0.002).. Plasma MR-proADM concentration was elevated in subjects with type 2 diabetes. This was further accentuated when nephropathy set in. MR-proADM was related to multiple metabolic factors and basal microcirculatory perfusion. Adrenomedullin might play a role in the pathogenesis of diabetic vasculopathy.

Topics: Adrenomedullin; Adult; Blood Pressure; Blood Vessels; Body Mass Index; Diabetes Mellitus, Type 2; Diabetic Angiopathies; Diabetic Nephropathies; Female; Glucose Intolerance; Humans; Male; Middle Aged; Protein Precursors; Proteins; Reference Values

Since adrenomedullin (AM) elicits vasodilatation by binding to specific AM receptors consisted of calcitonin-receptor-like receptor (CRLR)/receptor-activity-modifying protein 2 (RAMP2) or CRLR/receptor-activity-modifying protein 3 (RAMP3) on endothelial cells and stimulating nitric oxide production, AM possibly involves in glomerular capillary dilatation in early phase of diabetic nephropathy.. Streptozotocin (STZ)-induced diabetic Sprague-Dawley rats at 4 weeks after the injection were employed for expression studies of AM, RAPM2, and RAMP3. The measurement of AM peptide levels in kidney tissue, plasma, and urine was performed. Human aortic endothelial cells (HAEC) were used to investigate functional link between glucose-induced AM production and nitric oxide release.. STZ rats showed glomerular hypertrophy and increased urinary NO2- and NO3- excretion. By Northern blot analyses, AM and RAPM2 mRNAs significantly increased in the kidneys of STZ rats, while RAMP3 mRNA was not altered. In STZ rats, AM peptide was actively secreted into urine (1280 +/- 360 fmol/day vs. control 110 +/- 36 fmol/day). AM peptide was mainly detected on cortical and medullary collecting duct cells in control rat kidneys and AM peptide and mRNA were up-regulated on afferent arterioles and glomeruli of STZ rats. RAMP2 expression was detected on afferent arterioles and not in glomeruli in control rats and it was up-regulated on glomerular endothelial cells in STZ rats. In HAEC culture, d-glucose stimulated AM and nitric oxide production and they were suppressed by addition of AM antisense oligodeoxynucleotides.. Up-regulated expression of AM and RAMP2 in afferent arterioles and glomeruli may be related to selective dilatation of glomerular capillary in acute phase of type 1 diabetes.

Topics: Adrenomedullin; Animals; Aorta; Blood Glucose; Blotting, Northern; Cells, Cultured; Diabetes Mellitus, Experimental; Diabetes Mellitus, Type 1; Diabetic Nephropathies; DNA, Antisense; Endothelium, Vascular; Gene Expression; Humans; Hypertrophy; Intracellular Signaling Peptides and Proteins; Kidney Glomerulus; Male; Membrane Proteins; Nitrates; Nitric Oxide; Nitric Oxide Synthase; Nitric Oxide Synthase Type III; Nitrites; Peptides; Rats; Rats, Sprague-Dawley; Receptor Activity-Modifying Protein 2; Receptor Activity-Modifying Protein 3; Receptor Activity-Modifying Proteins; Receptors, Adrenomedullin; Receptors, Peptide; RNA, Messenger

Adrenomedullin (AM) is a hypotensive peptide widely produced in the cardiovascular organs and tissues such as the heart, kidney, and the vascular cells. We have previously cloned and sequenced the genomic DNA encoding human AM gene, and determined that the gene is located in the short arm of chromosome 11. The 3'-end of the gene is flanked by the microsatellite marker of cytosine adenine (CA) repeats. In this study, we investigated the association between DNA variations in AM gene and the predisposition to develop nephropathy in type 2 diabetes mellitus.. Genomic DNA was obtained from the peripheral leukocytes of 233 normal healthy subjects (NH), 139 type 2 diabetic patients on hemodialysis (DM-HD), 106 control patients with type 2 diabetes without nephropathy (DM-C) and 318 hemodialysis patients due to chronic glomerulonephritis (CGN-HD). The genomic DNA was subject to polymerase chain reaction (PCR) using a fluorescence-labeled primer, and the number of CA repeats were determined by polyacrylamide gel electrophoresis (PAGE).. In our Japanese subjects, there existed four types of alleles with different CA-repeat number; 11, 13, 14, and 19. The frequencies of these alleles were 11: 27.7%, 13: 32.8%, 14: 35.6%, and 19: 3.9% in NH. These allele frequencies were not significantly different in DM-C and CGN-HD. However, DM-HD showed significantly different distribution of allele frequency from other groups (chi 2 = 18.9, P = 0.026). Namely, the frequency of 19-repeat allele in DM-HD was higher (9.0%) than NH, DM-C, and CGN-HD (P = 0.005, 0.041, and 0.004, respectively).. The microsatellite DNA polymorphism of AM gene may be associated with the genetic predisposition to develop nephropathy in Japanese patients with type 2 diabetes mellitus.

Topics: Adrenomedullin; Adult; Aged; Diabetes Mellitus, Type 2; Diabetic Nephropathies; Female; Gene Frequency; Genetic Predisposition to Disease; Genotype; Humans; Japan; Male; Microsatellite Repeats; Middle Aged; Peptides; Polymorphism, Genetic; Renal Insufficiency

Adrenomedullin (AM) is a potent vasodilating peptide and is involved in cardiovascular and renal disease. In the present study, we investigated the role of AM in cardiac and renal function in streptozotocin (STZ)-induced diabetic rats. A single tail-vein injection of adenoviral vectors harboring the human AM gene (Ad.CMV-AM) was administered to the rats 1-wk post-STZ treatment (65 mg/kg iv). Immunoreactive human AM was detected in the plasma and urine of STZ-diabetic rats treated with Ad.CMV-AM. Morphological and chemical examination showed that AM gene delivery significantly reduced glycogen accumulation within the hearts of STZ-diabetic rats. AM gene delivery improved cardiac function compared with STZ-diabetic rats injected with control virus, as observed by decreased left ventricular end-diastolic pressure, increased cardiac output, cardiac index, and heart rate. AM gene transfer significantly increased left ventricular long axis (11.69 +/- 0.46 vs. 10.31 +/- 0.70 mm, n = 10, P < 0.05) and rate of pressure rise and fall (+6,090.1 +/- 597.3 vs. +4,648.5 +/- 807.1 mmHg/s), (-4,902.6 +/- 644.2 vs. -3,915.5 +/- 805.8 mmHg/s, n = 11, P < 0.05). AM also significantly attenuated renal glycogen accumulation and tubular damage in STZ-diabetic rats as well as increased urinary cAMP and cGMP levels, along with increased cardiac cAMP and Akt phosphorylation. We also observed that delivery of the AM gene caused an increase in body weight along with phospho-Akt and membrane-bound GLUT4 levels in skeletal muscle. These results suggest that AM plays a protective role in hyperglycemia-induced glycogen accumulation and cardiac and renal dysfunction via Akt signal transduction pathways.

Topics: Adenoviridae; Adrenomedullin; Animals; Blood Glucose; Body Weight; Cyclic AMP; Cyclic GMP; Diabetes Mellitus, Experimental; Diabetic Nephropathies; Disease Models, Animal; Gene Expression; Genetic Therapy; Genetic Vectors; Glucose Transporter Type 4; Glycogen; Heart; Heart Function Tests; Humans; Kidney; Male; Monosaccharide Transport Proteins; Muscle Proteins; Muscle, Skeletal; Myocardium; Peptides; Protein Serine-Threonine Kinases; Proto-Oncogene Proteins; Proto-Oncogene Proteins c-akt; Rats; Rats, Sprague-Dawley; Streptozocin; Ventricular Function, Left

Topics: Adrenomedullin; Aged; Diabetic Nephropathies; Female; Humans; Immunoradiometric Assay; Male; Middle Aged; Peptides; Proteinuria; Vasodilator Agents

To assess the relationship between plasma adrenomedullin (AM) levels and the presence of microvascular complications in type 1 diabetic patients.. We measured plasma AM and cAMP levels in 103 type 1 diabetic patients (46 without complications, 24 with retinopathy only, 14 with microalbuminuria but normal kidney function, and 19 with renal insufficiency) and 41 matched healthy control subjects.. Patients with renal insufficiency had higher levels of AM and cAMP than all other groups. Patients with only retinopathy showed a trend to have higher levels than patients without complications. There were no differences among all other groups. There was a significant correlation between AM and cAMP in the total diabetic group (rs = 0.36, P < 0.001) but not in the control group. In multiple regression analysis, plasma AM demonstrated significant relationships with creatinine clearance (beta = -0.31, P = 0.004) and duration of the disease (beta = 0.28, P = 0.008).. Plasma AM and cAMP are increased in type 1 diabetic patients with renal insufficiency. Creatinine clearance (CrClc) and duration of the disease are related to plasma AM levels in these patients.

Topics: Adrenomedullin; Adult; Albuminuria; Biomarkers; Body Mass Index; Cholesterol; Creatinine; Cyclic AMP; Diabetes Mellitus, Type 1; Diabetic Angiopathies; Diabetic Nephropathies; Diabetic Retinopathy; Female; Humans; Male; Middle Aged; Peptides; Proteinuria; Regression Analysis; Smoking

The present study was undertaken to determine plasma adrenomedullin levels in patients with non-insulin dependent diabetes mellitus (NIDDM) to elucidate the potential involvement in the pathogenesis of diabetic complications. The patients were 24 males and 21 females with ages of 55 +/- 2.1 years (mean +/- SEM). Plasma adrenomedullin levels were 5.94 +/- 0.44 pmol/l in patients with NIDDM, and were not affected by plasma glucose concentration. The plasma adrenomedullin increased dependent on the severity of diabetic nephropathy and retinopathy. Plasma levels of adrenomedullin positively correlated with various parameters, including serum creatinine levels, urinary excretion of protein, and systolic blood pressure. In contrast, there were negative correlations between the coefficient variation (CV) of RR intervals and plasma adrenomedullin, and between the conduction velocity of ulnar nerves and plasma adrenomedullin levels. These results indicate that the increase in plasma adrenomedullin was closely related to diabetic complications, which may be dependent on the development of microangiopathy.

Topics: Adrenomedullin; Albuminuria; Blood Glucose; Blood Pressure; Creatinine; Diabetes Mellitus, Type 2; Diabetic Nephropathies; Diabetic Retinopathy; Female; Humans; Kidney Failure, Chronic; Male; Middle Aged; Peptides; Proteinuria; Reference Values; Regression Analysis