Tanja Loof

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 AT(1) blocker 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)-beta served as the main marker of disease progression. Compared with the untreated GS rats (475 +/- 52 pg/ml), tubulointerstitial TGF-beta(1) protein 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-beta(1) expression (-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 AT(1) antagonist candesartan. Combined treatment yields significantly greater actions on renal TGF-beta overexpression and matrix accumulation, cell proliferation, and macrophage infiltration. The results suggest that rosuvastatin and an AT(1) blocker independently interfere with separate key pathways involved in the progression of chronic mesangioproliferative GS.

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.

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.

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.

Soluble guanylate cyclase stimulator BAY 41-8543 and female sex ameliorate uremic aortic remodeling in a rat model of mild uremia.

Background: Cardiovascular disease is the leading comorbidity in renal patients and has been related to impaired nitric oxide signaling. Estrogens exert protective effects on the vascular system. This study investigates the effects of biological sex and nitric oxide-independent soluble guanylate cyclase (sGC) stimulator BAY 41-8543 on aortic remodeling in experimental mild uremia. Method: Age-matched male and female Wistar rats were assigned for 18 weeks into sham-operated, subtotally nephrectomized (SNX), SNX + BAY 41-8543 and SNX + hydralazine. Analysis involved functional, histological, and molecular kidney and thoracic aorta parameters. Results: SNX significantly increased SBP, which was comparably reduced to control levels by BAY 41-8543 and hydralazine. In SNX males, uremic aortic remodeling was characterized by marked media thickening and increased media-to-lumen ratio (P < 0.01), vascular smooth muscle cell (VSMC) proliferation, macrophage infiltration, extracellular matrix turnover, decreased aortic elastin-to-collagen ratio (P < 0.01) and endothelial nitric oxide-synthase (eNOS) mRNA expression (P < 0.05). No significant alterations of aortic media-to-lumen ratio, VSMC proliferation, macrophage infiltration, matrix metalloproteinase-2, and eNOS mRNA expressions were seen in female uremic animals. BAY 41-8543 significantly ameliorated uremic aortic remodeling and stiffening involving reduced VSMC proliferation, collagen I-deposition, extracellular matrix turnover, and increased elastin content and eNOS mRNA expression. Hydralazine treatment did not substantially alter aortic remodeling. Conclusion: Experimental mild uremia leads to pronounced aortic hypertrophic remodeling and stiffening with sex-dependent alternations, and these are more severe in male rats. BAY 41-8543 ameliorates uremic aortic remodeling in a blood pressure-independent manner. The results suggest that sGC-stimulators may offer a novel treatment mode for pathological arterial wall remodeling in patients with impaired renal function.

Stimulation of soluble guanylate cyclase accelerates renal recovery following relief of unilateral ureteral obstruction

Background Unilateral ureteral obstruction (UUO) is characterized by progressive renal atrophy, tubular apoptosis and tubulointerstitial fibrosis. Pharmacological stimulation of soluble guanylate cyclase (sGC) and subsequent cGMP production have recently been found to be renoprotective. In this study, the sGC stimulator BAY 41-8543 was given to rats after relief of UUO in order to analyze the effects of enhanced NO/sGC/cGMP signaling on the subsequent renal disease recovery, concerning the renal atrophy, tubular apoptosis and tubulointerstitial fibrosis.

Blood pressure-independent effects of enhanced NO/cGMP signalling and gender on aortic remodelling in experimental renal hypertension

Results SNX led to increases in systolic blood pressure, with lower levels in F rats (F-SNX 129 ± 13 mmHg vs. M-SNX 140 ± 11 mmHg). Bay 41-8543 and hydralazine reduced blood pressure to control levels. Aortic remodelling was characterized by marked media thickening in both SNX groups, with a more pronounced increase in M versus F (127 ± 9 vs. 108 ± 6% of control; p < 0.001). Intima-media ratio was reduced in both uremic groups, with significant sex differences (M-SNX 66 ± 7% vs. F-SNX 80 ± 8% of control; p < 0.01). Furthermore, gender differences were observed in media-to-lumen ratio as indicator of aortic hypertrophy. The ratio was significantly higher in SNX males only (M-SNX 131 ± 9% vs. F-SNX 107 ± 15% of control; p < 0.001). Bay 41-8543 significantly ameliorated media thickness (111 ± 10 vs. 127 ± 9% of control in M; 101 ± 7 vs. 108 ± 6% of control in F; p < 0.05), intima-media ratio (85 ± 10 vs. 66 ± 7% of control in M; 91 ± 6 vs. 80 ± 8% of control in F, p < 0.01) and media-to-lumen ratio (107 ± 9 vs. 131 ± 9% of control in M; p < 0.001). Despite a similar reduction in blood pressure, hydralazine treatment did not alter aortic wall remodelling. These morphological changes were accompanied by elevated collagen I and reduced elastin protein expression at the level of aortic media, with decreased elastin/collagen ratio in untreated SNX groups, as marker of aortic wall stiffening. Bay 41-8543 treatment successfully prevented these molecular alterations (collagen I protein expression: 9.4 ± 0.3 vs. 14.5 ± 1.1% in females and 9.6 ± 0.4 vs. 16.1 ± 1.0% in males), while hydralazine showed no effects. SNX was characterized by increased extracellular matrix turnover with up-regulation of MMP2 and TIMP1 genes, more pronounced in males than in females (M-SNX 1.8 ± 0.1 vs. F-SNX 1.1 ± 0.1 for MMP2; M-SNX 4.2 ± 0.8 vs. F-SNX 2.7 ± 0.6 for TIMP1; both expressed as relative values vs. controls). In the male Bay 41-8543-treated group, expression of these genes was significantly lower (1.4 ± 0.1 MMP2from 4th International Conference of cGMP Generators, Effectors and Therapeutic Implications Regensburg, Germany. 19–21 June 2009

Activation of the nitric oxide-cGMP signaling pathway precedes resolution in acute anti-thy1 glomerulonephritis

Methods Rats with anti-thy1 glomerulonephritis were sacrificed at 0.5 and 1 day (injury), 5 and 10 days (matrix expansion) and 15 and 20 days (resolution) after OX-7 antibody injection. Measures of disease activity included glomerular matrix accumulation, transforming growth factorbeta1 (TGF-beta1) expression as well as glomerular platelet deposition, macrophage infiltration and cell proliferation. NO-cGMP signaling was characterized by measuring glomerular NO and cGMP production as well as glomerular mRNA expression of endothelial NO synthase (eNOS), inducible NOS (iNOS), alpha1 and beta1 soluble guanylate cyclase (sGC) and phosphodiesterase-5 (PDE-5). Results are expressed in relation to normal day 0 controls (=100%) (*p < 0.05 versus normal day 0 controls).

Enhancing cGMP in anti-thy1-induced, chronic-progressive glomerulosclerosis: sGC stimulation versus PDEs inhibition

Results Compared to normal controls, sGC mRNA expression (alpha1 sGC +260% and beta1 sGC +310%) and NOstimulated cGMP production (+270%) were up-regulated in the tubulointerstitium of the untreated cGS animals, while its activity was depressed in glomeruli (-50%). As compared to untreated the cGS group, Bay 41-2272 treatment significantly enhanced glomerular and tubulointerstitial NO-cGMP (+92% and +88%) signaling. This went along with markedly reduced glomerular and tubulointerstitial macrophage infiltration (-42% and -50%), number of proliferating cells (-31% and -30%), matrix protein expression (TGF-β protein -36% and -50%) and accumulation (histological matrix score -47% and -42%) as well as improved kidney function (plasma creatinine -57%). In contrast, PTX therapy only moderately, but not significantly affected the above parameters.