adrenomedullin and Glomerulonephritis--Membranoproliferative

Adrenomedullin (ADM) is a vasodilator peptide that is abundantly expressed in the kidney. ADM has antiproliferative effects on glomerular mesangial cells (MC) in vitro. Whether or not treatment with ADM can reduce MC proliferation in vivo [i.e., in mesangioproliferative glomerulonephritis (GN)] is unknown. We tested the hypothesis that ADM substitution reduces MC proliferation in GN.. GN in rats was induced by injection of an anti-Thy-1.1 antibody. Rats received osmotic minipumps, which continuously delivered rat ADM (500 ng/hour, N = 11), or vehicle (N = 13) from day 3 to day 6 after GN induction. Rats were sacrificed 6 days after induction of GN. On kidney sections, cells staining positive for proliferating cell nuclear antigen, mesangial cells, monocytes, and apoptotic cells were counted. Parameters of inflammation and fibrosis were measured in renal cortex and sieved glomeruli by real-time polymerase chain reaction (PCR).. Systolic blood pressure, diuresis, albuminuria, creatinine clearance, microaneurysm formation, and mesangial matrix expansion were not influenced by ADM infusion. However, ADM treatment significantly reduced the number of MC, showed a tendency to reduce total glomerular cell proliferation, and significantly increased apoptosis. ADM-treated GN animals showed significantly less glomerular monocyte infiltration. ADM treatment normalized transforming growth factor (TGF)-beta1 mRNA expression and reduced monocyte chemoattractant protein-1 (MCP-1), osteopontin, plasminogen activator inhibitor-1 (PAI-1), collagen I, and collagen III mRNA expression significantly.. Exogenous ADM infusion reduces MC number and glomerular monocyte infiltration in the state of mesangial proliferation during acute experimental mesangioproliferative GN. These findings indicate that ADM can influence the course of mesangioproliferative GN.

Topics: Adrenomedullin; Animals; Body Weight; Cell Count; Fibrosis; Glomerular Mesangium; Glomerulonephritis, Membranoproliferative; Male; Peptides; Rats; Rats, Sprague-Dawley; Urine; Vasodilator Agents

We studied the effects of mycophenolate mofetil, a specific inhibitor of inosine monophosphate dehydrogenase, on the mercuric chloride induced autoimmune glomerulonephritis in Brown Norway rats and also on the renal contents of adrenomedullin. In the rats with autoimmune glomerulonephritis, plasma and renal tissue adrenomedullin levels were increased significantly. Coadministration of mycophenolate mofetil resulted in prevention of autoimmune glomerulonephritis and also in maintaining of plasma and renal tissue adrenomedullin levels at control levels. Adrenomedullin mRNA expressions in the renal cortex were also higher in the rats with autoimmune glomerulonephritis. Significant positive correlations were found between renal cortical adrenomedullin levels and urinary Na+ and N-acetyl-beta-D-glucosaminidase excretion. A significant negative correlation between renal cortical adrenomedullin levels and creatinine clearance was also found. These results suggest that mycophenolate mofetil suppresses the renal damage in rats with autoimmune glomerulonephritis and renal adrenomedullin may participate in the pathophysiology of autoimmune glomerulonephritis.

Topics: Adrenomedullin; Animals; Blotting, Northern; Glomerulonephritis, Membranoproliferative; Immunosuppressive Agents; IMP Dehydrogenase; Kidney; Male; Mercuric Chloride; Mycophenolic Acid; Peptides; Proteinuria; Purines; Radioimmunoassay; Rats; Rats, Inbred BN

Adrenomedullin (AM) has antiproliferative and proapoptotic effects on mesangial cells in culture, but the regulation of AM and its receptors in glomeruli with glomerulonephritis have not been clarified.. We examined sequential changes in the mRNA expression of AM and its receptors (receptor-activity-modifying proteins; RAMPs), and AM production in the glomeruli of Thy.1 glomerulonephritis, using quantitative reverse transcription-polymerase chain reaction (RT-PCR) and immunoradiometric assay (IRMA).. Both the mRNA and the protein levels of AM in glomeruli isolated from rats 7 days after injection with anti-thymocyte serum (ATS), when mesangial cell proliferation peaked, were unchanged compared with those in control rats. However, on day 14, when almost all glomeruli had appeared to return to normal, AM mRNA expression was significantly increased (day 14 vs control: 51.2 +/- 9.1 vs 28.4 +/- 7.1 (mmol/mol glyceraldehyde-3-phosphate dehydrogenase; GAPDH); P < 0.05), as was the AM concentration (12.0 +/- 0.8 vs 8.4 +/- 0.4 fmol/10(4) glomeruli; P < 0.01). Subsequently, by 28 days after ATS injection, both levels decreased to the control ones. The mRNA expression of AM and RAMP2, in the glomeruli of Thy.1 glomerulonephritis changed similarly over time. Immunohistochemical staining revealed that AM production in mesangial cells was increased predominantly on day 14.. AM and RAMP increased during the reso-lution phase of increased mesangial proliferation in Thy.1 glomerulonephritis, but not during the mesangial proliferative phase. Considering the antiproliferative and proapoptotic effects of AM, its action on mesangial cells may be related to the amelioration of glomerulonephritis.

Topics: Adrenomedullin; Animals; Glomerular Mesangium; Glomerulonephritis, Membranoproliferative; Humans; Intracellular Signaling Peptides and Proteins; Kidney Glomerulus; Male; Membrane Proteins; Peptides; Rats; Rats, Wistar; Receptor Activity-Modifying Protein 2; Receptor Activity-Modifying Proteins; Receptors, Adrenomedullin; Receptors, Peptide; RNA, Messenger