Fulya Cakalagaoglu

Renal Protective Effects of Leukotriene Receptor Blockers in an Experimental Model of Cyclosporine Nephrotoxicity

BACKGROUND Chronic cyclosporine (CsA) nephrotoxicity is associated with renal fibrosis and hyaline arteriolopathy. Fibrogenic cytokines, such as transforming growth factor-beta (TGF-beta) and vascular endothelial growth factor (VEGF), play a pivotal role in CsA nephrotoxicity. Previous studies have demonstrated the possible role of leukotrienes (LT) in chronic CsA nephrotoxicity. The aim of this study was to examine the possible beneficial effects of LT blockers in attenuating the morphological and histochemical effects induced by CsA in a rat model of CsA nephrotoxicity. MATERIALS AND METHODS Twenty-four male Wistar rats were divided into 3 groups (n = 8). The first group (G1) was treated with vehicle intraperitoneally (IP) for 60 days. The second group (G2) was treated with 15 mg/kg CsA IP for 60 days. The third group (G3) was treated with the same dose of CsA plus 4 mg/kg montelukast administered by oral gavage for 60 days. RESULTS There was a statistically significant decrease in glomerular filtration rate (GFR) among G2 compared with G1 animals: 0.41 +/- 0.03 vs 1.63 +/- 0.12 mL/min (P < .001), or G3 hosts: 0.41 +/- 0.03 vs 0.95 +/- 0.05 mL/min (P < .005), respectively. The percentage of hyaline arteriolopathic changes was higher in G2 than G1 or G3: 81.66% +/- 8.2% vs 11.83% +/- 0.87% (P < .01) or 37.0% +/- 8.8% (P < .01), respectively. Fibrosis score was higher in G2 compared with G1 or G3: 1.5 +/- 0.04 vs 0.16 +/- 0.02 (P < .001) and 1.0 +/- 0.05 (P < .05), respectively. TGF-beta and VEGF immunoexpression were significantly increased in G2 compared with G1 (P < .05) or G3 (P < .05). CONCLUSIONS Our study suggested that LT may play a critical role in the pathogenesis of chronic CsA nephrotoxicity; the administration of montelukast, a LT receptor blocker, may prevent CsA-induced nephrotoxicity.

Effects of spironolactone in an experimental model of chronic cyclosporine nephrotoxicity.

BACKGROUND Cyclosporine (CsA)-associated nephrotoxicity is a long-term complication in transplant patients. Chronic CsA nephrotoxicity is associated with renal fibrosis and hyaline arteriolopathy. The aim of this study was to investigate the effect of spironolactone on functional and structural alterations as well as on platelet-derived growth factor B (PDGF-B) and transforming growth factor (TGF) beta expression induced by CsA in a rat model of chronic CsA nephrotoxicity. MATERIALS AND METHODS Twenty-four rats were divided into 3 groups. Group 1 (G1) received vehicle only (V); G2, CsA (15 mg/kg/d; CsA) by intraperitoneal (IP) injection; and G3, a similar CsA dosage + spironolactone (20 mg/kg/d; CsA + Ald.) by the oral route. At the end of 28 days, glomerular filtration rate (GFR) and blood CsA levels were measured as well as histopathological and immunohistochemical analyses performed on renal tissue. RESULTS Mean CsA trough levels in G2 and G3 were both above 2000 ng/mL. In G2, GFR was lower than G1 and G3 (0.35 +/- 0.05, 1.64 +/- 0.24, and 1.20 +/- 0.25 mL/min, respectively; P < .001). There was a significantly increased number of arteriolopathic changes in G2 and G3 vs G1 (16% +/- 3.7%, 15% +/- 6.8%, 3% +/- 1.2%, respectively; P < .001). Interstitial fibrosis was significantly increased in G2 vs G1 and G3 (52%, 0%, 27%, respectively; P < .05). Marked by up-regulated PDGF-B and TGF beta expressions were observed in G2 vs G1 or G3: 100%, 0%, 37.5%, respectively, for PDGF-B (P < .001) and 87.5%, 0%, 12.5%, respectively, for TGF beta (P < .001). CONCLUSION Our results suggested that chronic CsA nephrotoxicity may be mitigated by aldosterone receptor blockade which seemed to be associated with down-regulation of PDGF-B and TGF beta expression.

Protective effect of the vasopressin agonist terlipressin in a rat model of contrast-induced nephropathy.

Background/Aims: Contrast-induced nephropathy (CIN) remains a leading cause of iatrogenic acute renal failure. Terlipressin, a long-acting analog of vasopressin, may improve renal function. This study aimed to investigate the possible protective effect of terlipressin against the development of experimental CIN in rats. Methods: Wistar albino rats (n = 32) were allocated randomly into four equal groups of 8 each, i.e. control, terlipressin, contrast media (CM), and terlipressin plus contrast media (TCM). CIN was induced by intravenous administration of indomethacin (10 mg/kg), N-nitro L-arginine methyl ester (L-NAME, 10 mg/kg, twice at 15 and 30 min), and high-osmolar contrast media meglumine amidotrizoate 60%. Renal function parameters, kidney histology, and tubular expression of vascular endothelial growth factor (VEGF) were determined. Results: Mean serum creatinine levels were decreased (p < 0.05) and creatinine clearance (p < 0.05) increased in the TCM group compared with the CM group. Notably, rats in the TCM group displayed less tubular necrosis (p < 0.05), medullary congestion (p < 0.05), and a reduced tubular expression of VEGF (p < 0.05) compared with the CM group. Conclusion: These results demonstrate that terlipressin can inhibit the development of CIN.

Focal segmental glomerulosclerosis associated with idiopathic myelofibrosis.

A patient with idiopathic myelofibrosis with nephrotic syndrome is reported. Seven months after the initial diagnosis of myelofibrosis, the patient was presented with dyspnea, generalized edema, heavy proteinuria, massive pleural effusion, and ascites. Renal biopsy showed focal segmental glomerulosclerosis. After starting immunosuppressive therapy consisting of cyclosporine and steroids, his renal function and proteinuria improved and transfusion requirements decreased.

Pleiotropic and Renoprotective Effects of Erythropoietin Beta on Experimental Diabetic Nephropathy Model

Background: This study aimed at investigating the possible protective effect of erythropoietin beta on experimental diabetic nephropathy (DN) model in rats. Methods: Sprague Dawley rats (n = 32) were allocated into 4 equal groups of 8 each, the control (Group C), diabetes (Group D), erythropoietin beta (Group E), and erythropoietin beta treated DN (Group E + D) groups. Streptozocin (65 mg/kg) was used to induce diabetes in 10-week old rats. Erythropoietin beta was given intraperitoneally at a dose of 500 IU/kg/3 days of a week for 12 weeks. Renal function parameters, intrarenal levels and activities of oxidative stress biomarkers, serum inflammatory parameters and kidney histology were determined. Results: Group E + D had lower mean albumin-to-creatinine ratio (p < 0.001) as well as higher creatinine clearance (p = 0.035) than the diabetic rats (Group D). Intrarenal malondialdehyde levels were significantly lower (p = 0.004); glutathione (GSH) levels (p = 0.003), GSH peroxidase (p = 0.004) and superoxide dismutase (p < 0.005) activities of renal tissue were significantly higher in Group E + D than in Group D. The mean serum levels of interleukin-4 (p < 0.005), interleukin 1 beta (p = 0.012), interferon gamma (p = 0.018) and tumor necrosis factor alpha (p < 0.005) were significantly lower; serum levels of monocyte chemoattractant protein 1 (p = 0.018) was significantly higher in Group E + D when compared to Group D. The mean scores of tubulointerstitial inflammation (p = 0.004), tubular injury (p = 0.013) and interstitial fibrosis (p = 0.003) were also lower in Group E + D when compared to Group D. Conclusion: Our data seem to suggest a potential role of erythropoietin beta for reducing the progression of DN in an experimental rat model. This protective effect is, in part, attributable to the suppression of the inflammatory response and oxidative damage.

Effect of the Direct Renin Inhibitor Aliskiren in the Prevention of Experimental Contrast-Induced Nephropathy in the Rat

Background: Renal vasoconstriction, activated by the renin-angiotensin system, plays a pivotal role in the pathogenesis of contrast-induced nephropathy (CIN). The purpose of this study was to evaluate the effect of aliskiren, a direct renin inhibitor, for the prophylaxis of experimental CIN in the rat. Methods: Thirty-two Wistar albino rats were divided into four groups of 8 rats each, namely the control (C), aliskiren (A), contrast media (CM) and aliskiren plus contrast media (ACM) groups. Aliskiren was given orally at a dose of 50 mg/kg/day once daily for 5 consecutive days. CIN was induced by intravenous administration of indomethacin, N-nitro-L-arginine methyl ester and high-osmolar contrast medium meglumine amidotrizoate. Renal function parameters, kidney histology and tubular expression of vascular endothelial growth factor were determined. Results: Mean serum creatinine was significantly lower (p < 0.001) and mean creatinine clearance was higher (p < 0.001) in the ACM group compared with the CM group. However, there were no differences between the ACM and CM groups in terms of tubular necrosis, proteinaceous casts, medullary congestion and vascular endothelial growth factor expression. Conclusion: Our preliminary data seem to suggest a potential role of aliskiren for the prophylaxis of CIN in an experimental rat model.

Histopathological changes and tumour necrosis factor‐α, transforming growth factor‐β and tenascin expression in patients with primary type I membranoproliferative glomerulonephritis in remission

Aim:  Primary type I membranoproliferative glomerulonephritis (MPGN) is a rare cause of glomerular disease with a high relapse rate and poor prognosis. The aim of this study was: (i) to evaluate the histopathological findings associated with remission; and (ii) to document the possible clinical and histopathological factors predicting relapses.

The blockade of the renin-angiotensin system reverses tacrolimus related cardiovascular toxicity at the histopathological level

Introduction. In this study, we investigate the toxic effects of tacrolimus (FK506) on the cardiovascular system at the histopathological level in a rat model and whether these effects can be reversed by the blockade of the renin-angiotensin system (RAS) by either an angiotensin-converting enzyme inhibitor (ACE-inhibitors) or an angiotensin receptor antagonist (ARB). Methods and results. Thirty-one Wistar rats were divided into four groups. FK506 group was treated with FK506 intraperitoneally (i.p.), FK506+ACE-inhibitors and FK506+ARB groups were treated with either quinapril or valsartan orally in addition to FK506. Control group was treated with saline i.p. Histological and immunohistochemical staining of cardiovascular tissue in the FK506 group showed increased vacuolar degeneration (11.2 vs. 5.8, p=0.008), arterial hyalinosis (10.7 vs. 6. G 3, p=0.036), transforming growth factor-beta (TGF-β) (12.2 vs. 4.8, p=0.001) and vascular endothelial growth factor expression (VEGF) (10.7 vs. 6.3, p=0.036), elastic van Gieson (11.5 vs. 5.5, p=0.004), and periodic acid O Schiff stain scores (12.5 vs. 4.5, p<0.001) compared to the control group. Immunohistochemical scores showed that expression of TGF-β is up-regulated, and bone morphogenic protein (BMP-7) is down-regulated with FK506 toxicity. Adding RAS blockade with either an ACE-inhibitor or an ARB could reverse FK506 induced changes. Both FK506+ACE-inhibitors and FK506+ARB groups demonstrated decrease in arterial hyalinosis (22.1 vs. 14.4 (FK506+ACE-inhibitor) and 13.6 (FK506+ARB), p=0.09) and vacuolar degeneration (23.1 vs. 16.1 (FK506+ACE-inhibitor) and 12.4 (FK506+ARB), p=0.006) scores compared to the FK506 group. Conclusion. Blockade of RAS could reverse the histopathological signs of FK506 induced cardiac toxicity in a rat model.

Quantitative evaluation of interstitial fibrosis with Sirius Red in IgA nephritis

Abstract Objective: Tubulointerstitial fibrosis is one of the strongest independent predictive factors in determining the prognosis in IgA nephritis. Recently, software-based quantitative measurement of interstitial fibrosis with Sirius Red staining has entered the practice. The objective of this study was to investigate the prognostic value of measurement of interstitial nephritis with this method in IgA nephritis. Method: Forty-three patients diagnosed with IgA nephritis with renal biopsy between the years 2005 and 2009 were included in this retrospective observational study. The diagnostic biopsies of 37 patients were examined. Basal data included age, gender, creatinine level, glomerular filtration rate (GFR), presence of proteinuria, hypertension, glomerulosclerosis, mesangial proliferation, and interstitial fibrosis and fibrosis index calculated by the measurement of computed images of Sirius Red positive areas. Final visit included evaluation of development of end-stage renal disease (ESRD), and GFR (whether = 60 mL/min or <60 mL/min). Results: Numbers of patients with hypertension (75% vs. 34.5%; p = 0.050), ESRD development (62.5% vs. 20.7%, p = 0.035), GFR <60 mL/min (87.5% vs. 31%; p = 0.007) were greater; and basal GFR (34.25 ± 25.29 vs. 64.14 ± 35.34; p = 0.048) was lower in high-intensity interstitial fibrosis group (>1000 μm2) compared to low-intensity interstitial fibrosis group (≤1000 μm2). Conclusion: Quantitative analysis of computed imaging of areas of Sirius Red positive tubulointerstitial fibrosis might serve as an effective novel method to determine the prognosis in IgA nephritis.

Cysteinyl 1 Receptor Antagonist Montelukast, Does Not Prevent Peritoneal Membrane Damage in Experimental Chronic Peritoneal Dialysis Model in Rats

Background/Aims: Continuous ambulatory peritoneal dialysis (CAPD) induces structural changes in the peritoneal membrane such as fibrosis, vasculopathy and angioneogenesis with a reduction in ultrafiltration capacity. Leukotriene (LT) receptor antagonists have been found to be effective to prevent fibrosis in some nonperitoneal tissues. The aim of this study is to investigate the possible beneficial effect of montelukast, a LT receptor antagonist, on peritoneal membrane exposed to hypertonic peritoneal dialysis in uremic rats. Methods: Of the 48 male, 5/6 nephrectomized Wistar rats 29 remained alive and were included in the study. These studied rats were divided into 3 groups: Group I (n=7) was the control group, Group II (n=8) was treated with 20 ml hypertonic PDF intraperitoneally daily and Group III was treated with montelukast and similar PDF treatment protocol. The morphological and functional changes in the peritoneal membrane as well as cytokine expression were compared between groups. Results: Submesothelial thickness and the severity of the degree of hyaline vasculapathy were more prominent in group III when compared to group I. There were no significant differences between group II and other groups in terms of submesothelial thickness and the severity of the degree of hyaline vasculapathy. Increased expressions of TGF-β and VEGF in parietal peritoneal membrane were found in group II and group III when compared to group I. The amount of TGF-β and VEGF expression were similar in group II and group III. Conclusion: This study suggests that montelukast treatment does not prevent the peritoneal membrane from deleterious effects of hyperosmolar PDF in the uremic environment.