IL-17 Expression in the Time Course of Acute Anti-Thy1 Glomerulonephritis

BACKGROUND

Interleukin-17 (IL-17) is a new pro-inflammatory cytokine involved in immune response and inflammatory disease. The main source of IL-17 is a subset of CD4+ T-helper cells, but is also secreted by non-immune cells. The present study analyzes expression of IL-17 in the time course of acute anti-thy1 glomerulonephritis and the role of IL-17 as a potential link between inflammation and fibrosis.

METHODS

Anti-thy1 glomerulonephritis was induced into male Wistar rats by OX-7 antibody injection. After that, samples were taken on days 1, 5, 10 (matrix expansion phase), 15 and 20 (resolution phase). PBS-injected animals served as controls. Proteinuria and histological matrixes score served as the main markers for disease severity. In in vitro experiments, NRK-52E cells were used. For cytokine expressions, mRNA and protein levels were analyzed by utilizing RT-PCR, in situ hybridization and immunofluorescence.

RESULTS

Highest IL-17 mRNA-expression (6.50-fold vs. con; p<0.05) was found on day 5 after induction of anti-thy1 glomerulonephritis along the maximum levels of proteinuria (113 ± 13 mg/d; p<0.001), histological glomerular-matrix accumulation (82%; p<0.001) and TGF-β1 (2.2-fold; p<0.05), IL-6 mRNA expression (36-fold; p<0.05). IL-17 protein expression co-localized with the endothelial cell marker PECAM in immunofluorescence. In NRK-52E cells, co-administration of TGF-β1 and IL-6 synergistically up-regulated IL-17 mRNA 4986-fold (p<0.001).

CONCLUSIONS

The pro-inflammatory cytokine IL-17 is up-regulated in endothelial cells during the time course of acute anti-thy1 glomerulonephritis. In vitro, NRK-52E cells secrete IL-17 under pro-fibrotic and pro-inflammatory conditions.

Tyrosine kinases inhibition by Imatinib slows progression in chronic anti-thy1 glomerulosclerosis of the rat

Background

Chronic progressive mesangioproliferative nephropathy represents a major cause of end-stage renal disease worldwide. Until now, effective approaches to stop or even slow its progression are limited. We tested the effects of an inhibitor of PDGF receptor, abl and c-kit tyrosine kinases, Imatinib, in a chronic progressive model of mesangioproliferative glomerulosclerosis.

Methods

Anti-thy1 glomerulosclerosis was induced by injection of anti-thy1 antibody into uninephrectomized Wistar rats. One week after disease induction, according to the degree of proteinuria, animals were stratified and assigned to chronic glomerulosclerosis (cGS) and cGS plus Imatinib (10 mg/kg body weight/day). In week 20, renoprotective actions of Imatinib were analyzed by a set of functional, histological and molecular biological parameters.

Results

Untreated cGS rats showed elevation of systolic blood pressure and marked progression in proteinuria, renal fibrosis, cell infiltration, cell proliferation and function lost. Administration of Imatinib went along significantly with lower systolic blood pressure (−10 mmHg) and proteinuria (−33%). Imatinib administration was paralled by significant reductions in tubulointerstitial accumulation of matrix proteins (−44%), collagen I deposition (−86%), expression of TGF-beta1 (−30%), production of fibronectin (−23%), myofibroblast differentiation (−87%), macrophage infiltration (−36%) and cell proliferation (−45%), respectively. In comparison with untreated cGS animals, Imatinib therapy lowered also blood creatinine (−41%) and blood urea concentrations (−36%) and improved creatinine clearance (+25%). Glomerular fibrotic changes were lowered moderately by Imatinib.

Conclusions

Therapy with Imatinib limits the progressive course of chronic anti-thy1 glomerulosclerosis towards tubulointerstitial fibrosis and renal insufficiency. This was paralleled by direct and indirect sign of TGF-β1 and PDGF inhibition. The findings suggest that the pharmacological principal of inhibition of tyrosine kinases with drugs such as Imatinib might serve as approach for limiting progression of human mesangioproliferative glomerulosclerosis.

Impact of biological gender and soluble guanylate cyclase stimulation on renal recovery after relief of unilateral ureteral obstruction

PURPOSE

Gender difference and nitric oxide deficiency contribute to the progression of many chronic kidney diseases. In a model of unilateral ureteral obstruction relief we analyzed the impact of biological gender and nitric oxide/cyclic guanosine monophosphate signaling stimulation on renal disease severity and restoration.

MATERIALS AND METHODS

Female and male rats underwent sham surgery or unilateral ureteral obstruction. After 5-day unilateral ureteral obstruction female and male rats were assigned to obstruction relief alone or obstruction relief plus 7-day treatment with the soluble guanylate cyclase stimulator BAY 41-8543.

RESULTS

Compared to male rats with obstruction relief renal disease was less severe in female rats, which had significantly less tubulointerstitial matrix accumulation and tubular atrophy. In each gender group α1 and β1-soluble guanylate cyclase was comparably and significantly increased but female rats produced significantly more cyclic guanosine monophosphate after treatment with the soluble guanylate cyclase stimulator. In each group BAY 41-8543 treatment was associated with significant amelioration of renal matrix protein expansion, macrophage infiltration, tubular apoptosis and atrophy.

CONCLUSIONS

Female gender is protective for unilateral ureteral obstruction relief. This was linked to higher sensitivity of the soluble guanylate cyclase enzyme and cyclic guanosine monophosphate production in response to BAY 41-8543. In these female and male rats enhancing the signaling of nitric oxide/cyclic guanosine monophosphate with BAY 41-8543 significantly accelerated the restoration of renal architecture after obstruction relief and largely ameliorated the differences in disease severity due to the gender disparity.

Stimulation of soluble guanylate cyclase improves renal recovery after relief of unilateral ureteral obstruction

PURPOSE

The antifibrotic effects of soluble guanylate cyclase stimulation and cyclic guanosine monophosphate production have been observed in cases of anti-thy1-induced renal disease. We analyzed the action of the specific soluble guanylate cyclase stimulator BAY 41-8543 on the renal recovery phase in rats with unilateral ureteral obstruction after obstruction was relieved.

MATERIALS AND METHODS

Sprague-Dawley® rats underwent reversible unilateral ureteral obstruction for 5 days, after which obstruction was relieved. Rats were randomly assigned to unilateral ureteral obstruction and unilateral ureteral obstruction plus BAY 41-8543 (10 mg/kg body weight daily). Seven days after relief of obstruction we determined treatment effects on renal atrophy, apoptosis, fibrosis and nitric oxide/cyclic guanosine monophosphate signaling.

RESULTS

Untreated obstructed rats showed mildly increased systolic blood pressure, marked tubular atrophy and apoptosis, tubulointerstitial macrophage infiltration and fibrosis. Plasma cyclic guanosine monophosphate levels were unaltered in untreated rats with obstruction while renal soluble guanylate cyclase mRNA expression was increased. BAY 41-8543 administration significantly increased plasma cyclic guanosine monophosphate, which was paralleled by significant decreases in systolic blood pressure, renal tubular diameter, apoptosis and renal macrophage infiltration. Also, soluble guanylate cyclase stimulation decreased tubulointerstitial fibrosis, as shown by tubulointerstitial volume, matrix protein accumulation, α-smooth muscle actin expression, collagen IV deposition and transforming growth factor-β1 mRNA expression.

CONCLUSIONS

Soluble guanylate cyclase stimulation by BAY 41-8543 increases cyclic guanosine monophosphate production and subsequently enhances renal recovery after unilateral ureteral obstruction relief through an array of pathways. This finding suggests that soluble guanylate cyclase stimulation may serve as a novel treatment approach to restore or preserve renal structure and function in cases of obstructive kidney disease.

The lymphocyte migration inhibitor FTY720 attenuates experimental hypertensive nephropathy

The lymphocyte migration inhibitor FTY720 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 nephrectomy. Two days after surgery, male Wistar rats were allocated to the following groups: Sham surgery, nephrectomy (HN), and HN + FTY720 (0.3 mg/kg body wt). Therapy was continued for 6 wk. Treatment with FTY720 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 FTY720 were paralleled by significant reductions in renal transforming growth factor (TGF)-beta overexpression, macrophage infiltration, and cell proliferation. In conclusion, the lymphocyte migration inhibitor FTY720 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-beta 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.

Rosuvastatin is additive to high-dose candesartan in slowing progression of experimental mesangioproliferative glomerulosclerosis

Rosuvastatin is additive to high-dose candesartan in slowing progression of experimental mesangioproliferative glomerulosclerosis (GS). Progressive mesangioproliferative glomerulonephritis, mostly IgA nephropathy, is a major cause of end-stage kidney disease worldwide. In a chronic-progressive model of mesangioproliferative GS, we tested the renoprotective efficacy of rosuvastatin alone and in combination with a high-dose of the AT1blocker candesartan. Treatment was started 1 wk after disease induction (anti-thy1 antibody injection into uninephrectomized rats) and continued until week 20. Tubulointerstitial expression of the key fibrosis mediator transforming growth factor (TGF)-β served as the main marker of disease progression. Compared with the untreated GS rats (475 ± 52 pg/ml), tubulointerstitial TGF-β1protein expression was significantly reduced by both single therapies (rosuvastatin −47%, candesartan −51%, P < 0.01). Tubulointerstitial matrix accumulation (matrix score in GS: 64 ± 7%) was relatively reduced by −45 and −52%, respectively ( P < 0.01). The combination of rosuvastatin and candesartan had significantly greater effects on tubulointerstitial TGF-β1expression (−82% vs. GS) and matrix accumulation (−83% vs. GS) ( P < 0.001 vs. GS, P < 0.05 vs. single therapy) than either drug alone. Similar additive beneficial effects were observed for renal fibronectin and tissue inhibitor of metalloproteinase-1 expression, cell proliferation, macrophage infiltration, proteinuria, and kidney function. In conclusion, rosuvastatin limits the progressive course of anti-thy1-induced GS toward chronic tubulointerstitial fibrosis and renal insufficiency to a degree comparable to the one achieved by a high dose of the AT1antagonist candesartan. Combined treatment yields significantly greater actions on renal TGF-β overexpression and matrix accumulation, cell proliferation, and macrophage infiltration. The results suggest that rosuvastatin and an AT1blocker independently interfere with separate key pathways involved in the progression of chronic mesangioproliferative GS.

Low-dose mTOR inhibition by rapamycin attenuates progression in anti-thy1-induced chronic glomerulosclerosis of the rat

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-thy1 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-thy1-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-thy1-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.

S1P modulator FTY720 limits matrix expansion in acute anti-thy1 mesangioproliferative glomerulonephritis

FTY720 is a novel immune modulator whose primary action is blood lymphocyte depletion through interaction with sphingosine-1-phosphate (S1P) receptors. The present study analyzes the effect of FTY720 on both the early mesangial cell injury and the subsequent matrix expansion phase of experimental mesangioproliferative glomerulonephritis. Disease was induced by injection of OX-7 anti-thy1 antibody into male Wistar rats. In both protocols, FTY720 administration (0.3 mg/kg body wt) resulted in a selective and very marked reduction in blood lymphocyte count. In the injury experiment, the S1P receptor modulator was given starting 5 days before and continued until 1 day after antibody injection. FTY720 did not significantly affect the degree of anti-thy1-induced mesangial cell lysis and glomerular-inducible nitric oxide production. In the matrix expansion experiment, FTY720 treatment was started 1 day after antibody injection and continued until day 7. In this protocol, the S1P modulator reduced proteinuria, histological matrix expansion, and glomerular protein expression of TGF-beta(1), fibronectin, and PAI-1. Glomerular collagen III staining intensity was decreased. FTY720 reduced markedly glomerular lymphocyte number per cross section and to a lesser degree macrophage infiltration. In conclusion, FTY720 significantly limits TGF-beta(1) overexpression and matrix protein expression following induction of acute anti-thy glomerulonephritis, involving reductions in blood and glomerular lymphocyte numbers. The results suggest that lymphocytes actively contribute to matrix expansion in experimental mesangioproliferative glomerulonephritis. Our study expands on findings on FTY720's beneficial effects on tubulointerstitial and functional disease progression previously reported in anti-thy1-induced chronic glomerulosclerosis.

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-beta1 (TGF-beta1), 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.

Mycophenolate mofetil slows progression in anti-thy1-induced chronic renal fibrosis but is not additive to a high dose of enalapril

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-thy1 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.

Enhancing cGMP in experimental progressive renal fibrosis: soluble guanylate cyclase stimulation vs. phosphodiesterase inhibition

cGMP serves as the main second messenger of nitric oxide (NO). Antifibrotic effects of enhancing renal cGMP levels have recently been documented in experimental acute anti-Thy-1 glomerulonephritis. The present study compares the effects of the cGMP production-increasing soluble guanylate cyclase (sGC) stimulator BAY 41-2272 with those of the cGMP degradation-limiting phosphodiesterase inhibitor pentoxifylline (PTX) in a progressive model of renal fibrosis. At 1 wk after induction of anti-Thy-1-induced chronic glomerulosclerosis (cGS), rats were randomly assigned to groups as follows: cGS, cGS + BAY 41-2272 (10 mg x kg body wt(-1) x day(-1)), or cGS + PTX (50 mg x kg body wt(-1) x day(-1)). BAY 41-2272 and PTX reduced systolic blood pressure significantly. At 16 wk, tubulointerstitial expressions of sGC mRNA and NO-induced cGMP synthesis were increased in untreated cGS animals, whereas their glomerular activity was depressed compared with normal controls. Tubulointerstitial and glomerular cGMP production in response to NO were significantly enhanced in animals treated with BAY 41-2272, but not in those treated with PTX. BAY 41-2272 administration resulted in marked reductions of glomerular and tubulointerstitial histological matrix accumulation, expression of TGF-beta1 and fibronectin, macrophage infiltration, and cell proliferation as well as improved renal function. In contrast, only moderate and nonsignificant renoprotective changes were observed in the cGS + PTX group. In conclusion, increasing renal cGMP production through BAY 41-2272 significantly improved renal NO-cGMP signaling and limited progression in anti-Thy-1-induced chronic renal fibrosis, whereas inhibition of cGMP degradation by PTX was only moderately effective. The findings indicate that pharmacological enhancement of renal cGMP levels by sGC stimulation represents a novel and effective antifibrotic approach in progressive kidney disorders.

Expression and activity of soluble guanylate cyclase in injury and repair of anti-thy1 glomerulonephritis

BACKGROUND

Activation of soluble guanylate cyclase and generation of cyclic 3',5'-guanosine monophosphate (cGMP) is the main signal transducing event of the L-arginine-nitric oxide pathway. The present study analyzes the expression and activity of the nitric oxide-cGMP signaling cascade in and the effect of the specific soluble guanylate cyclase stimulator Bay 41-2272 on the early injury and subsequent repair phase of acute anti-thy1 glomerulonephritis.

METHODS

Anti-thy1 glomerulonephritis was induced by OX-7 antibody injection in rats. In protocol 1 (injury), Bay 41-2272 was given starting 6 days before antibody injection. One day after disease induction, parameters of mesangial cell injury (glomerular cell number and inducible nitric oxide synthesis) were analyzed. In protocol 2 (repair), Bay 41-2272 treatment was started one day after antibody injection. On day 7, parameters of glomerular repair [glomerular matrix score, expression of transforming growth factor (TGF)-beta1, fibronectin, and plasminogen-activator-inhibitor (PAI)-1, infiltration with macrophages and fibrinogen deposition (indicating platelet localization)] were determined. In both protocols, tail bleeding time, systolic blood pressure, plasma cGMP levels, glomerular mRNA expression of endothelial nitric oxide synthase (eNOS), alpha1 and beta1 soluble guanylate cyclase, and basal and nitric oxide-stimulated glomerular cGMP production were analyzed.

RESULTS

Bay 41-2272 prolonged bleeding time, reduced blood pressure, and increased plasma cGMP levels in both protocols. In the injury experiment, disease induction increased inducible nitric oxide synthesis and reduced glomerular cell number, while expression and activity of soluble guanylate cyclase was almost completely diminished. Bay 41-2272 did not affect parameters of mesangial cell injury and glomerular soluble guanylate cyclase expression and activity. In the repair protocol, expression and activity of soluble guanylate cyclase was markedly increased by disease. Bay 41-2272 further enhanced soluble guanylate cyclase expression and activity. This went along with significant reductions in proteinuria, glomerular matrix accumulation, expression of TGF-beta1, fibronectin, and PAI-1, macrophage infiltration and fibrinogen deposition as compared to the untreated anti-thy1 animals.

CONCLUSION

Glomerular nitric oxide signaling via cGMP is markedly impaired during injury of anti-thy1 glomerulonephritis, while it is highly up-regulated during subsequent repair. Further pharmacologic soluble guanylate cyclase stimulation limits glomerular TGF-beta overexpression and matrix expansion, suggesting that the soluble guanylate cyclase enzyme represents an important antifibrotic pathway in glomerular disease.