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Stimulation of soluble guanylate cyclase slows progression in anti-thy1-induced chronic glomerulosclerosis. Background. A critical role of soluble guanylate cyclase and nitric oxide–dependent cyclic 3′,5′-guanosine monophosphate (cGMP) production for glomerular matrix expansion has recently been documented in a rat model of acute anti-thy1 glomerulonephritis. The present study analyzes the renal activity of the nitric oxide-cGMP signaling cascade in and the effect of the specific soluble guanylate cyclase stimulator Bay 41-2272 on a progressive model of anti-thy1-induced chronic glomerulosclerosis. Methods. Anti-thy1 glomerulosclerosis was induced by injection of anti-thy1 antibody into uninephrectomized rats. One week after disease induction, animals were randomly assigned to chronic glomerulosclerosis, chronic glomerulosclerosis plus Bay 41-2272 (10 mg/kg body weight/day) or chronic glomerulosclerosis plus hydralazine (15 mg/kg body weight/day). In week 16, analysis included effects on systolic blood pressure, proteinuria, kidney function, glomerular and tubulointerstitial matrix protein accumulation, expression of transforming growth factor-β1 (TGF-β1), fibronectin and plasminogen activator inhibitor type 1 (PAI-1), macrophage infiltration, cell proliferation, basal and nitric oxide–stimulated cGMP production as well as tubulointerstitial mRNA expression of alpha 1 and beta 1 soluble guanylate cyclase. Results. The moderately elevated systolic blood pressure seen in the chronic glomerulosclerosis group was comparably decreased by both treatments. Compared to normal controls, soluble guanylate cyclase mRNA expression and nitric oxide–stimulated cGMP production were up-regulated in the tubulointerstitium of the untreated chronic glomerulosclerosis animals, while its activity was decreased in glomeruli. Bay 41-2272 treatment enhanced glomerular and tubulointerstitial nitric oxide–cGMP signaling significantly. This went along with markedly reduced glomerular and tubulointerstitial macrophage infiltration, number of proliferating cells, matrix expression and accumulation, as well as improved kidney function. In contrast, hydralazine therapy did not significantly affect renal nitric oxide–cGMP signaling, macrophage number, cell proliferation, matrix protein expression and accumulation. Conclusion. Glomerular and tubulointerstitial soluble guanylate cyclase activity are discordantly altered in anti-thy1-induced chronic glomerulosclerosis. Stimulation of soluble guanylate cyclase signaling by Bay 41-2272 limits the progressive course of this model toward tubulointerstitial fibrosis and impaired renal function at least in part in a blood pressure–independent manner. The results suggest that soluble guanylate cyclase activation counteracts fibrosis and progression in chronic renal disease. [ABSTRACT FROM AUTHOR]

The lymphocyte migration inhibitor FFY720 attenuates experimental hypertensive nephropathy. Infiltration with lymphocytes is found in both immune and nonimmune chronic kidney diseases. In a rat model of immune-initiated progressive glomerulosclerosis, selective inhibition of lymphocyte infiltration by FTY720 showed significant beneficial effects on renal fibrosis. To test whether this translates into hypertensive nephropathy (HN), the lymphocyte migration inhibitor was administered to rats following ⅚ nephrectomy. Two days after surgery, male Wistar rats were allocated to the following groups: Sham surgery, ⅚ nephrectomy (HN), and HN + FFY720 (0.3 mg/kg body wt). Therapy was continued for 6 wk. Treatment with FFY720 was found to selectively reduce blood lymphocyte counts by 85% (P < 0.001 vs. HN) and renal lymphocyte infiltration (CD-3 positive cells) by 63% (P < 0.01 vs. HN) as was anticipated. Lymphocyte depletion went along with a significant reduction in proteinuria (-28%), whereas hypertensive systemic blood pressure remained unchanged (160 ± 5 vs. 161 ± 5 mmHg, P = not significant). The markedly increased histological tubulointerstitial and glomerular matrix protein accumulation, collagen, laminin, and fibronectin deposition were all significantly impeded in the FTY720-treated animals. The anti-fibrotic effects of FFY720 were paralleled by significant reductions in renal transforming growth factor (TGF)-β overexpression, macrophage infiltration, and cell proliferation. In conclusion, the lymphocyte migration inhibitor FFY720 significantly limits histological and molecular fibrosis in a model of hypertensive nephropathy without affecting increased systemic blood pressure. Prevention of renal lymphocytes' infiltration by FTY720 was followed by significant reductions in TGF-β overexpression, macrophage infiltration, and renal cell proliferation. These results suggest that infiltrating lymphocytes play an active, profibrotic role in the progression of hypertensive renal tissue injury. [ABSTRACT FROM AUTHOR]

Krämer S, Wang-Rosenke Y, Scholl V, Binder E, Loof T, Khadzhynov D, Kawachi H, Shimizu F, Diekmann F, Budde K, Neumayer H-H, Peters H. Low-dose mTOR inhibition by rapamycin attenuates progression in anti-thyl-induced chronic glomeruloscierosis of the rat. Am J Physiol Renal Physiol 294: F440-F449, 2008. First published December 19, 2007; doi:10.1152/ajprenal.00379.2007.—Treatment options in human mesangioproliferative glomerulonephritis/sclerosis, mostly IgA nephropathy, are limited. Progressive mesangioproliferative nephropathy represents a major cause of end-stage kidney disease. The present study explores the efficacy of low-dose mTOR inhibition by rapamycin in a chronic-progressive model of mesangioproliferative glomerulosclerosis (cGS). cGS was induced by high-dose anti-thyl antibody injection into uninephrectomized rats. Rapamycin administration (2.5 mg·kg-1·body wt-1) was started 10 days after antibody injection and continued until week 20. cGS was characterized by advancing proteinuria, increased blood pressure, marked tubulointerstitial and glomerular fibrosis, cell proliferation and round cell infiltration, and impaired renal function. Kruskal-Wallis and Mann-Whitney U-tests were used for statistical analysis. The course of chronic anti-thyl-induced glomerulosclerosis was significantly attenuated by low-dose rapamycin treatment. In week 20, this was demonstrated by improvements in proteinuria (-38%), systolic blood pressure (-16 mmHg), tubulointerstitial and glomerular histological matrix accumulation (-61 and -24%), transforming growth factor-β1 overexpression (-41 and -47%), collagen I deposition (-53 and -65%), cell proliferation (-90 and -76%), and leukocyte number (macrophages -52 and -53%; lymphocytes -58 and 51%), respectively. Rapamycin improved renal function as well (blood creatinine -0.68 mg/dl, urea -66.7 mg/day, and creatinine clearance +0.13 ml·min-1·100 g body wt-1). In conclusion, low-dose mTOR inhibition by rapamycin limits the progressive course of anti-thyI-induced renal disease toward chronic glomerulosclerosis, tubulointerstitial fibrosis, and renal insufficiency. Renoprotection by rapamycin involved significant beneficial effects on multiple key pathways in the progression of chronic renal disease, i.e., proteinuria, extracellular matrix accumulation, renal cell proliferation, and inflammatory cell infiltration. [ABSTRACT FROM AUTHOR]

Tubulointerstitial inflammation and fibrosis are hallmarks of chronic progressive renal diseases. To characterize the functional interaction between cell infiltration and matrix expansion, this study compared the immunosuppressant mycophenolate mofetil (MMF), intended as primarily anti-inflammatory intervention, the angiotensin-converting enzyme inhibitor enalapril, intended as primarily an anti-fibrotic drug, and a combination of both as anticipated anti-inflammatory/anti-fibrotic intervention. The model used was anti-thy1-induced chronic-progressive glomerulosclerosis (cGS) in the rat, where a brief anti-thy1-induced glomerular injury progresses spontaneously toward tubulointerstitial fibrosis and renal insufficiency, cGS was induced by injection of anti-thy 1 antibody into uninephrectomized Wistar rats. One week after disease induction, animals were randomly assigned to the following groups: cGS, cGS plus MMF (20 mg·kg body wt-1·day-1), cGS plus high-dose enalapril (12 mg·kg body wt-1·day-1), and cGS plus both. At week 16 after disease induction, MMF or enalapril alone reduced signs of chronic renal disease significantly and similarly compared with the untreated cGS group. Variables measured included proteinuria, blood pressure, tubulointerstitial and glomerular matrix accumulation, expression of transforming growth factor-β1, fibronectin, and plasminogen activator inhibitor-1, infiltration of lymphocytes and macrophages, plasma creatinine and urea levels, and glomerular filtration rate. Combined MMF and enalapril treatment was not superior to single therapy. In conclusion, MMF slows the progression of chronic renal fibrosis and renal insufficiency as effectively as high-dose enalapril in the anti-thy1-induced chronic-progressive glomerulosclerosis model. The dual anti-inflammatory/anti-fibrotic intervention does not yield additive renoprotective effects, indicating that MMF and enalapril interfere with similar or very closely related pathways involved in progression of renal disease. [ABSTRACT FROM AUTHOR]