Simvastatin ameliorates glomerulosclerosis in Adriamycin-induced-nephropathy rats

Serotonin 5HT2A receptor antagonism mediated anti-inflammatory and anti-fibrotic effect in adriamycin-induced CKD in rats

A selective 5-HT2A receptor antagonist ketanserin has been used preclinically to improve renal blood flow because of its beneficial effect on autoregulation in various chronic kidney disease models. Ketanserin might be able to turn down adriamycin-induced chronic kidney disease, which is characterized by renal fibrosis, inflammation and structural and functional changes in glomeruli. In the present study, we investigated whether ketanserin suppresses these renal alterations or not. Wistar rats were administered with a single dose of adriamycin (6 mg/kg/i.v), which leads to development of severe tubulointerstitial fibrosis with altered renal function. Subsequent ketanserin treatment (5 mg/kg/p.o) for 4 weeks shown significant change in oxidative stress, serum and urine parameters in adriamycin-induced chronic kidney disease rats. Additionally, results showed that mRNA expression of TGF-β and collagen IV, which are known to promote fibrosis via various signaling pathways involved in the progression of renal disease, was suppressed by ketanserin treatment. Furthermore, expression levels of 5-HT2A and pro-inflammatory marker IL-6 have also been reduced significantly after ketanserin administration in adriamycin-treated animals. Moreover, histopathological studies also reveal the considerable structural changes after ketanserin treatment, and these results are further supported via data obtained from the percentage of glomeruli size changes. In conclusion, ketanserin reduces renal fibrosis and inflammation in adriamycin-induced chronic kidney disease by suppressing 5-HT2A, IL-6, TGF-β and collagen IV expression in renal tissue.

CD36 Promotes Podocyte Apoptosis by Activating the Pyrin Domain-Containing-3 (NLRP3) Inflammasome in Primary Nephrotic Syndrome

BACKGROUND CD36 plays a critical role in many sterile inflammatory diseases, including type 2 diabetes mellitus, atherosclerosis, and primary nephrotic syndrome. This study investigated whether CD36 activates the nucleotide-binding domain leucine-rich repeat-containing family, pyrin domain-containing-3 (NLRP3) inflammasome and promotes podocytes apoptosis in primary nephrotic syndrome. MATERIAL AND METHODS The mouse podocyte cell line MPC5 was used as a model. mRNA and protein expression of CD36 and NLRP3 was quantified by real-time PCR and Western blotting, respectively. Levels of caspase-1 activity and total cholesterol were determined using commercial kits. Intracellular lipid droplets were detected by Oil Red O staining. CD36 expression was also examined in nephrotic mouse kidney tissue by immunohistochemistry and immunofluorescence. Intracellular lipid droplet was examined by Oil Red O staining. RESULTS CD36 expression was increased in nephrotic mouse kidney tissue. Treatment with interleukin-1b increased expression of CD36 and total cholesterol in MPC5 cells. Moreover, this treatment increased expression of NLRP3 and the percentage of apoptotic cells, both of which were inhibited by co-treatment with an anti-CD36 antibody. CONCLUSIONS CD36 might play an important role in podocyte apoptosis by activating the NLRP3 inflammasome in primary nephrotic syndrome.

Calcitriol Prevents Cardiovascular Repercussions in Puromycin Aminonucleoside-Induced Nephrotic Syndrome

Puromycin aminonucleoside-induced nephrotic syndrome (PAN-NS) is characterized by cardiac remodeling and increased local inflammatory activity. Patients with NS and animal models of NS have vitamin D3 deficiency. The aim of the present study was to evaluate the influence of calcitriol on cardiac remodeling and local inflammatory state in PAN-NS rat model. Male Sprague-Dawley rats were injected with PAN or vehicle on day 0. PAN and control rats were divided into two subgroups for the administration of calcitriol (PAN-D and Ct-D groups) or the vehicle (PAN-V and Ct-V groups) during 21 days. On day 21, the renal function, metabolic balance, calcitriol and FGF-23 plasma levels, prohypertrophy and proinflammatory markers (ET-1, TGF-β1, TNF-α, and IL-1β), and calcium signaling molecules (PLB and SERCA-2a) were evaluated. Twenty-one days after injection, PAN-V group presented cardiac hypertrophy and a modulation of proinflammatory markers local expression. Calcitriol treatment of PAN rats prevented cardiac hypertrophy and was associated with marked reduction in the cardiac expression levels of proinflammatory markers. Our results suggest that vitamin D3 deficiency in PAN-NS may contribute to cardiac remodeling and to the increase in local inflammatory activity. Calcitriol treatment prevents both cardiac repercussions and local inflammatory processes in PAN-NS.

Podocytes

Podocytes are highly specialized cells of the kidney glomerulus that wrap around capillaries and that neighbor cells of the Bowman’s capsule. When it comes to glomerular filtration, podocytes play an active role in preventing plasma proteins from entering the urinary ultrafiltrate by providing a barrier comprising filtration slits between foot processes, which in aggregate represent a dynamic network of cellular extensions. Foot processes interdigitate with foot processes from adjacent podocytes and form a network of narrow and rather uniform gaps. The fenestrated endothelial cells retain blood cells but permit passage of small solutes and an overlying basement membrane less permeable to macromolecules, in particular to albumin. The cytoskeletal dynamics and structural plasticity of podocytes as well as the signaling between each of these distinct layers are essential for an efficient glomerular filtration and thus for proper renal function. The genetic or acquired impairment of podocytes may lead to foot process effacement (podocyte fusion or retraction), a morphological hallmark of proteinuric renal diseases. Here, we briefly discuss aspects of a contemporary view of podocytes in glomerular filtration, the patterns of structural changes in podocytes associated with common glomerular diseases, and the current state of basic and clinical research.

Simvastatin ameliorates renal lipidosis through the suppression of renal CXCL16 expression in mice with adriamycin-induced nephropathy

AIMS

To investigate the roles of CXCL16 and ox-LDL in adriamycin (ADR)-induced nephropathy mice and to explore the mechanism of simvastatin on the renal protective effects of ADR nephropathy.

METHODS

Fifteen male Balb/c mice were randomly divided into normal control (NC), ADR nephropathy and simvastatin-treated ADR nephropathy (ADR-SIM) groups. ADR nephropathy was induced by a single intravenous injection of ADR into the tail vein. All mice were sacrificed at the end of the 7th week, with the blood, 24-h urine and kidneys collected. The levels of ox-LDL and total cholesterol in the serum, the serum CXCL16, ox-LDL and NF-κB expression were detected.

RESULTS

Compared with the NC group, the levels of serum total cholesterol and ox-LDL in the ADR and ADR-SIM groups were significantly higher, the level of serum albumin was significantly lower and the expression of CXCL16, ox-LDL and NF-κB in the renal tissue of ADR and ADR-SIM groups was significantly increased. Compared with the ADR group, the expressions of renal CXCL16, ox-LDL and NF-κB in the ADR-SIM group were significantly decreased. Levels of serum total cholesterol and ox-LDL were not significantly different between the two groups.

CONCLUSIONS

Simvastatin exerts a protective effect on renal function and structure in mice with ADR nephropathy. The beneficial effects of simvastatin might be related to the decreasing expression of CXCL16 in glomerular podocytes followed by the decreasing endocytosis of ox-LDL in podocytes and inhibition of NF-κB pathway activation.

Protective role of atorvastatin against doxorubicin-induced cardiotoxicity and testicular toxicity in mice

Doxorubicin (DOX), a potent chemotherapeutic agent, is widely used for the treatment of various malignancies. However, its clinical uses are limited due to its dose-dependent adverse effects particularly cardiac and testicular toxicities. DOX-induced toxicity is mainly due to the induction of oxidative stress. Atorvastatin (ATV), a 3-hydroxy 3-methyl glutaryl coenzyme A reductase inhibitor, with lipid-lowering activity, acts as an antioxidant at lower doses. It possesses pleiotropic effects independent of cholesterol-lowering property usually shown at lower doses, which include antioxidant and anti-inflammatory activities. The present study was aimed to investigate the possible protection exerted by atorvastatin against oxidative stress and DNA damage induced by DOX in the heart and testes of mice. The protective role of ATV in the heart and testes of DOX-treated mice was evident from the amelioration of oxidative stress, DNA and cellular damage. The present study clearly indicates that ATV offers a significant protection against DOX-induced oxidative stress and DNA damage in the heart and testes of mice.

Podocyte injury and overexpression of vascular endothelial growth factor and transforming growth factor-beta 1 in adriamycin-induced nephropathy in rats

The aim of this study is to investigate the expression of nephrin, vascular endothelial growth factor (VEGF), transforming growth factor-beta 1 (TGF-β1), and podocyte number in adriamycin (ADR)-induced nephropathy. A total of 60 male Sprague-Dawley rats were randomly divided into the control group and the ADR nephropathy group. The nephropathy was induced by tail-vein injection of ADR (4 mg/kg) twice at a 14-day interval. The expression levels of nephrin, VEGF, and TGF-β1 in glomeruli were assessed by immunohistochemistry and western blotting. The podocyte number was also evaluated after anti-Wilms' tumor-1 (WT1) immunohistochemical staining. In addition, the urinary protein content, biochemical parameters in serum samples and glomerular sclerosis index (SI) were compared between groups. In the ADR nephropathy group, the expression levels of nephrin was significantly decreased with the fusion of podocyte foot processes at 6 weeks after the first ADR injection, which was associated with a marked proteinuria. A decrease in podocyte number and an increase in SI with the overexpression of both VEGF and TGF-β1 were also observed in the glomeruli at 10 weeks after the first ADR injection. This was associated with focal segmental glomerulosclerosis (FSGS). The study data suggest that podocyte injury and decreased nephrin, as well as increased VEGF and TGF-β1, may contribute to the development of proteinuria and FSGS in ADR-induced nephropathy in rats.

Ezetimibe alone or in combination with pitavastatin prevents kidney dysfunction in 5/6 nephrectomized rats fed high-cholesterol

We attempted to elucidate the relationship between cholesterol absorption and kidney damage by investigating the renoprotective effect of ezetimibe, a cholesterol absorption inhibitor, in 5/6 nephrectomized rats (Nx). The Nx or sham-operated rats (Sham) were fed 1% high-cholesterol diet (HC) containing ezetimibe (10 mg/[kg d]), pitavastatin (3 mg/[kg d]), or both for 8 weeks. Pathological changes, endothelial nitric oxide synthase (eNOS) messenger RNA (mRNA), and oxidative stress were assessed in the kidney. The Sham fed HC exhibited hypercholesterolemia and glomerulosclerosis with macrophage infiltration in the kidney, and ezetimibe attenuated these changes. The Nx exhibited hypercholesterolemia, increased urinary 8-hydroxy-2'-deoxyguanosine (8-OHdG), glomerulosclerosis with macrophage infiltration and interstitial fibrosis, and downregulation of eNOS mRNA. The HC increased cholesterol further and worsened the kidney damage with increased 8-OHdG. Ezetimibe attenuated the hypercholesterolemia, kidney dysfunction, and pathological changes. The beneficial effects of ezetimibe were significantly associated with reduced 8-OHdG (P < .01). Pitavastatin did not reduce cholesterol or 8-OHdG, but it did significantly suppress the kidney damage with upregulated eNOS mRNA by 2.5-fold (P < .02). The combination of ezetimibe and pitavastatin synergistically ameliorated the kidney damage. The kidney dysfunction and pathological changes were significantly associated with cholesterol, markers of cholesterol absorption (campesterol and cholestanol), and 8-OHdG (P < .001-.05). Multiple regression analysis revealed that the markers of cholesterol absorption were independently associated with the kidney damage. Ezetimibe confers renoprotective effects by inhibiting cholesterol absorption, which in turn reduces oxidative stress; and pitavastatin additively ameliorates kidney damage by increasing NO production via mechanisms independent of cholesterol reduction.

apoE expression in glomerulus and correlation with glomerulosclerosis induced by adriamycin in rats

Lipid deposition in glomerulus plays an important role in the progression of glomerulosclerosis (GS), and apolipoprotein E (apoE) is an important protein in cholesterol homeostasis. This investigation was performed to explore whether there exists an association between apoE and GS susceptibility. Eighty Wistar rats were randomly divided into two groups: sham operation group and glomerulosclerosis model group, n = 40. The GS disease in rat was induced by uninephrectomy and injecting adriamycin (5 mg/kg) through the tail vein. At the end of 9 and 13 weeks, 20 rats in each group were killed and the relative samples were collected. Serum creatinine, blood urea nitrogen, and 24-h urine protein were determined. Immunohistochemical analysis was performed on renal tissue to detect the expression of apoE, collagen IV, fibronectin, α-smooth muscle actin, and transforming growth factor-β1 in glomerulus. Real-time reverse transcription polymerase chain reaction was conducted to detect the apoE mRNA expression in renal tissue. Compared with sham operation group at the end of 9/13 weeks, glomerulosclerosis model group exhibited levels of serum creatinine, blood urea nitrogen, 24-h urine protein, and a glomerulosclerosis index that were significantly elevated ( p < 0.01), and collagen IV, fibronectin, α-smooth muscle actin, and transforming growth factor-β1 protein expression and apoE expression (protein and mRNA) were significantly upregulated (p < 0.01). In conclusion, apoE can increase the accumulation of extracellular matrix in glomerulus and may take part in the progression of GS.

The inflammatory cytokines TWEAK and TNFα reduce renal klotho expression through NFκB

Proinflammatory cytokines contribute to renal injury, but the downstream effectors within kidney cells are not well understood. One candidate effector is Klotho, a protein expressed by renal cells that has antiaging properties; Klotho-deficient mice have an accelerated aging-like phenotype, including vascular injury and renal injury. Whether proinflammatory cytokines, such as TNF and TNF-like weak inducer of apoptosis (TWEAK), modulate Klotho is unknown. In mice, exogenous administration of TWEAK decreased expression of Klotho in the kidney. In the setting of acute kidney injury induced by folic acid, the blockade or absence of TWEAK abrogated the injury-related decrease in renal and plasma Klotho levels. TWEAK, TNFα, and siRNA-mediated knockdown of IκBα all activated NFκB and reduced Klotho expression in the MCT tubular cell line. Furthermore, inhibition of NFκB with parthenolide prevented TWEAK- or TNFα-induced downregulation of Klotho. Inhibition of histone deacetylase reversed TWEAK-induced downregulation of Klotho, and chromatin immunoprecipitation showed that TWEAK promotes RelA binding to the Klotho promoter, inducing its deacetylation. In conclusion, inflammatory cytokines, such as TWEAK and TNFα, downregulate Klotho expression through an NFκB-dependent mechanism. These results may partially explain the relationship between inflammation and diseases characterized by accelerated aging of organs, including CKD.

Effects of dietary protein and fat contents on renal function and inflammatory cytokines in rats with adriamycin-induced nephrotic syndrome

The effects of dietary protein and fat on renal function-related blood and urine parameters, such as albumin, urinary protein,and inflammatory cytokines were investigated in adriamycin- (ADR) induced nephrotic syndrome rats. ADR (2 mg/kg BW) was injected i.p. weekly for six weeks to develop nephrotic syndrome; thereafter rats were fed low-protein/high-fat (LPHF) or high-protein/low-fat (HPLF) diets for five weeks. Renal function-related blood and urine parameters were measured before and after dietary intervention. Serum levels of albumin, TG, and creatinine were significantly higher in the LPHF group than in the HPLF group. Serum levels of albumin were low and urinary protein excretion protein was high in HPLF group. BUN and UUN levels were higher in the HPLF group than in the LPHF. Urinary excretion of creatinine was significantly higher in the HPLF group than in the LPHF group. Serum inflammatory cytokine levels did not differ between the two groups, however the levels of IL-6, TNF-α, and IL-13 in splenocyte supernatants were significantly higher in the LPHF group than in the HPLF group. We confirmed that protein and fat contents in diet affect renal function-related blood and urine parameters and splenocyte inflammatory cytokine levels in ADR-induced nephrotic syndrome rats.

Beneficial effect of triple treatment plus immunoglobulin in experimental nephrotic syndrome

Combinations of antiproteinurics, including angiotensin I-converting enzyme inhibitors + angiotensin II receptor antagonist + statins, are promising choices in the treatment of steroid-resistant nephrotic syndrome. We aimed to investigate the effects of high doses of immunoglobulin in addition to these combinations in rats with adriamycin-induced nephrosis. The study included 40 rats allocated into five groups: control, nephrotic syndrome without treatment, dual therapy (DT) with enalapril + losartan, triple therapy (TT) with enalapril + losartan + simvastatin, and quadruple therapy (QT) with enalapril + losartan + simvastatin + a high dose of immunoglobulin. The proteinuria levels were not statistically different between DT, TT and QT groups at weeks 5, 8, 12 and 16. At week 16, serum creatinine levels in the QT group were significantly lower than those in the control, DT and TT groups. The glomerulosclerosis index in the DT group was significantly lower than in the TT and QT groups. The scores for interstitial fibrosis and TGF-beta staining were similar among treatment groups. In conclusion, we showed that quadruple therapy including immunoglobulin had a beneficial effect on renal function in the late phase, but it had no additional effects in reducing proteinuria or in glomerulosclerosis score in experimental nephrotic syndrome. Further studies with angiotensin I-converting enzyme inhibitors (ACEIs), angiotensin II receptor antagonists (AIIRAs) and immunoglobulin combinations would offer some benefits in the treatment of nephrotic syndrome.