Colchicine vs. Omega-3 Fatty Acids for Prevention of Chronic Cyclosporine Nephrotoxicity in Sprague Dawley Rats: An Experimental Animal Model

Capybara Oil Improves Renal Pathophysiology and Inflammation in Obese Mice

Obesity is an inflammatory disease associated with secondary diseases such as kidney disease, which can cause lipotoxicity, inflammation and loss of organ function. Polyunsaturated fatty acids act in the production of lipid mediators and have anti-inflammatory characteristics. In this work, the objective was to evaluate renal histopathology in obese mice and the effects of treatment with capybara oil (CO) (5000 mg/kg/day for 4 weeks). Parameters such as body mass, lipid profile, systolic blood pressure, urinary creatinine and protein excretion, structure and ultrastructure of the renal cortex, fibrosis, tissue inflammation and oxidative stress were analyzed. CO treatment in obese mice showed improvement in the lipid profile and reduction in systolic blood pressure levels, in addition to beneficial remodeling of the renal cortex. Our data demonstrated that CO decreased inflammation, oxidative stress and renal fibrosis, as evidenced by quantifying the expression of TNF-α, IL-10, CAT, SOD, α-SMA and TGF-β. Although treatment with CO did not show improvement in renal function, ultrastructural analysis showed that the treatment was effective in restoring podocytes and pedicels, with restructuring of the glomerular filtration barrier. These results demonstrate, for the first time, that treatment with CO is effective in reducing kidney damage, being considered a promising treatment for obesity.

Pomegranate attenuates kidney injury in cyclosporine-induced nephrotoxicity in rats by suppressing oxidative stress

To investigate the effect of pomegranate juice (PJ) on the cyclosporine (CsA)-induced nephrotoxicity in rats, 80 rats were divided into four groups. The first group was regarded a negative control group, and the others were as follows: group 2 (CsA group) received CsA in a dose of 25 mg/kg/day orally, group 3 (treated group) received CsA in a dose of 25 mg/kg/day plus 2.5 mL/day of PJ, and group 4 (PJ group) received 2.5 mL of PJ daily. By the end of the 21st day, plasma creatinine, blood urea nitrogen (BUN), creatinine clearance, urinary KIM-1, and NGAL were determined. Histopathological investigation and the determination of malondialdehyde and antioxidant enzymes were analyzed in kidney tissues. The results show that plasma creatinine, BUN, creatinine clearance, and kidney injury molecule-1 and neutrophil gelatinase-associated lipocalin were significantly altered in the CsA group. The supplement of PJ attenuated the alteration in these parameters. The treatment with PJ also prohibits the CsA-induced alteration in the histopathology, lipid peroxidation, and antioxidant enzymes. We can conclude that PJ protects against CsA-induced nephrotoxicity due to its antioxidant effects.

Novel Omega-3 Fatty Acid Epoxygenase Metabolite Reduces Kidney Fibrosis

Cytochrome P450 (CYP) monooxygenases epoxidize the omega-3 polyunsaturated fatty acid (PUFA) docosahexaenoic acid into novel epoxydocosapentaenoic acids (EDPs) that have multiple biological actions. The present study determined the ability of the most abundant EDP regioisomer, 19,20-EDP to reduce kidney injury in an experimental unilateral ureteral obstruction (UUO) renal fibrosis mouse model. Mice with UUO developed kidney tubular injury and interstitial fibrosis. UUO mice had elevated kidney hydroxyproline content and five-times greater collagen positive fibrotic area than sham control mice. 19,20-EDP treatment to UUO mice for 10 days reduced renal fibrosis with a 40%-50% reduction in collagen positive area and hydroxyproline content. There was a six-fold increase in kidney α-smooth muscle actin (α-SMA) positive area in UUO mice compared to sham control mice, and 19,20-EDP treatment to UUO mice decreased α-SMA immunopositive area by 60%. UUO mice demonstrated renal epithelial-to-mesenchymal transition (EMT) with reduced expression of the epithelial marker E-cadherin and elevated expression of multiple mesenchymal markers (FSP-1, α-SMA, and desmin). Interestingly, 19,20-EDP treatment reduced renal EMT in UUO by decreasing mesenchymal and increasing epithelial marker expression. Overall, we demonstrate that a novel omega-3 fatty acid metabolite 19,20-EDP, prevents UUO-induced renal fibrosis in mice by reducing renal EMT.

Predictive usefulness of urinary biomarkers for the identification of cyclosporine A-induced nephrotoxicity in a rat model

The main side effect of cyclosporine A (CsA), a widely used immunosuppressive drug, is nephrotoxicity. Early detection of CsA-induced acute nephrotoxicity is essential for stop or minimize kidney injury, and timely detection of chronic nephrotoxicity is critical for halting the drug and preventing irreversible kidney injury. This study aimed to identify urinary biomarkers for the detection of CsA-induced nephrotoxicity. We allocated salt-depleted rats to receive CsA or vehicle for 7, 14 or 21 days and evaluated renal function and hemodynamics, microalbuminuria, renal macrophage infiltration, tubulointerstitial fibrosis and renal tissue and urinary biomarkers for kidney injury. Kidney injury molecule-1 (KIM-1), tumor necrosis factor-alpha (TNF-α), interleukin 6 (IL-6), fibronectin, neutrophil gelatinase-associated lipocalin (NGAL), TGF-β, osteopontin, and podocin were assessed in urine. TNF-α, IL-6, fibronectin, osteopontin, TGF-β, collagen IV, alpha smooth muscle actin (α -SMA) and vimentin were assessed in renal tissue. CsA caused early functional renal dysfunction and microalbuminuria, followed by macrophage infiltration and late tubulointerstitial fibrosis. Urinary TNF-α, KIM-1 and fibronectin increased in the early phase, and urinary TGF-β and osteopontin increased in the late phase of CsA nephrotoxicity. Urinary biomarkers correlated consistently with renal tissue cytokine expression. In conclusion, early increases in urinary KIM-1, TNF-α, and fibronectin and elevated microalbuminuria indicate acute CsA nephrotoxicity. Late increases in urinary osteopontin and TGF-β indicate chronic CsA nephrotoxicity. These urinary kidney injury biomarkers correlated well with the renal tissue expression of injury markers and with the temporal development of CsA nephrotoxicity.

Protective effect of docosahexaenoic acid against cyclosporine A-induced nephrotoxicity in rats: a possible mechanism of action

The aim of this experimental study was to investigate whether, and how then, docosahexaenoic acid (DHA) could alleviate the cyclosporine A (CsA)-induced nephrotoxicity. Three main groups of Sprague-Dawley rats were treated orally with CsA (25 mg/kg), DHA (100 mg/kg), and CsA along with DHA. A corresponding control group was also used. DHA administration significantly reduced CsA-induced nephrotoxicity and associated hyperlipidemia and proteinuria as assessed by estimating serum triacylglycerol, serum total cholesterol, serum total protein, serum urea, and creatinine clearance. Furthermore, urinary excretions of protein and N-acetyl-β-D-glucosaminidase were significantly inhibited following DHA administration. DHA supplementation slightly attenuated the oxidative damage in kidney tissues as evaluated by the levels of thiobarbituric acid-reacting substances and protein carbonyl content in the kidney homogenate, although there were no significant differences between CsA-intoxicated and DHA-treated animals. Moreover, DHA treatment significantly restored total nitric oxide (NO) levels in both renal tissues and urine. This study demonstrates the ability of DHA to ameliorate CsA-induced renal dysfunction, which might be beneficial to enhance the therapeutic index of CsA. The data suggest that the protective potential of DHA in the prevention of CsA nephrotoxicity in rats was mainly associated with the increase of total NO bioavailability in renal tissues. Nevertheless, the exact independent mechanism in which DHA exerts its beneficial effect is yet to be fully elucidated.

Macrophage depletion attenuates chronic cyclosporine A nephrotoxicity

BACKGROUND

Cyclosporine A (CsA)-induced chronic nephrotoxicity is characterized by renal dysfunction and interstitial fibrosis. Early and progressive renal macrophage influx, correlating with latter interstitial fibrotic areas, has been associated with CsA treatment. This study investigated the role of macrophages, the nitric oxide (NO) pathway, and the oxidative stress on chronic CsA nephrotoxicity.

METHODS

The macrophages were depleted by clodronate liposomes. Animals were distributed into four groups: vehicle (olive oil for 21 days), CsA 7.5 mg/kg per day (21 days), CsA plus clodronate (5 mg/mL intraperitoneally on days -4, 1, 4, 11, and 18 of CsA treatment), or vehicle plus clodronate. On day 22, glomerular filtration rate, renal blood flow, renal tubulointerstitial fibrosis, CsA blood levels, serum malondialdehyde and renal tissue immunohistochemistry for macrophages, inducible NO synthase, transforming growth factor-beta, nuclear factor-kbeta, alpha-smooth muscle actin, vimentin, and nitrotyrosine were assessed.

RESULTS

CsA-induced increase in the macrophage was prevented by clodronate. Macrophage depletion attenuated the reductions in the glomerular filtration rate and renal blood flow, the development of tubulointerstitial fibrosis, malondialdehyde increase and increases in nuclear factor-kbeta, transforming growth factor-beta, vimentin, inducible NO synthase, and nitrotyrosine expression provoked by CsA. Clodronate did not affect alpha-smooth muscle actin expression and CsA blood levels.

CONCLUSIONS

Renal macrophage influx plays an important role in CsA-induced chronic nephrotoxicity. The NO pathway and oxidative stress are likely mechanisms involved in the genesis of this form of renal injury.

Omega-3 polyunsaturated fatty acids in the treatment of kidney disease

After more than 25 years of published investigation, including randomized controlled trials, the role of omega-3 polyunsaturated fatty acids in the treatment of kidney disease remains unclear. In vitro and in vivo experimental studies support the efficacy of omega-3 polyunsaturated fatty acids on inflammatory pathways involved with the progression of kidney disease. Clinical investigations have focused predominantly on immunoglobulin A (IgA) nephropathy. More recently, lupus nephritis, polycystic kidney disease, and other glomerular diseases have been investigated. Clinical trials have shown conflicting results for the efficacy of omega-3 polyunsaturated fatty acids in IgA nephropathy, which may relate to varying doses, proportions of eicosapentaenoic acid and docosahexaenoic acid, duration of therapy, and sample size of the study populations. Meta-analyses of clinical trials using omega-3 polyunsaturated fatty acids in IgA nephropathy have been limited by the quality of available studies. However, guidelines suggest that omega-3 polyunsaturated fatty acids should be considered in progressive IgA nephropathy. Omega-3 polyunsaturated fatty acids decrease blood pressure, a known accelerant of kidney disease progression. Well-designed, adequately powered, randomized, controlled clinical trials are required to further investigate the potential benefits of omega-3 polyunsaturated fatty acids on the progression of kidney disease and patient survival.

Colchicine update: 2008

OBJECTIVES

To review recent advances in the understanding of molecular mechanisms of drug disposition and cellular mechanisms of action and targets of colchicine, and disease applications and guidelines for oral colchicine use.

METHODS

Summarized and interpreted here is the pertinent English and non-English language literature on MEDLINE since the last update of colchicine in this journal in 1998 and published up to July 2008 regarding colchicine pharmacology, toxicology, mechanisms of action, and clinical applications in gout and other medical conditions.

RESULTS

Assessment, after review of 1512 publications, is that oral colchicine therapy is being refined by attention to novel targets such as NALP3 and pyrin. The drug has a narrow therapeutic-toxicity window, and potentially serious drug-drug interactions (eg, with clarithromycin and cyclosporine) are better recognized and therefore preventable. Reviewed here are recent advances in colchicine pharmacogenomics, and recognition of drug-drug interactions and predictors of potential toxicities, including alterations in the P-glycoprotein multidrug transporter ABCB1, cytochrome P450 3A4 isoenzyme, and hepatobiliary and renal function. Current understanding of optimization of colchicine dosing is reviewed, as are recent findings on colchicine therapy of nonrheumatic cardiovascular, hepatic, and renal diseases (eg, lowering of C-reactive protein, and treatment of acute and recurrent pericarditis). Finally, the article reviews the recent U.S. Food and Drug Administration-mandated cessation of marketing of injectable colchicine.

CONCLUSIONS

Oral colchicine has unique anti-inflammatory and antiproliferative effects with broad ramifications for rheumatic and nonrheumatic disease applications. Significant advances in the last decade have increased understanding of predictors of both colchicine efficacy and toxicity.

Nigella sativa oil for prevention of chronic cyclosporine nephrotoxicity: an experimental model

Nephrotoxicity is the main secondary effect of cyclosporine A (CsA) treatment. The antioxidant action of Nigella sativa oil (NSO) may explain the protective effect of these agents against various hepatotoxic and nephrotoxic models in vivo and in vitro. This study was designed to investigate the possible protective effects of NSO, in prevention of chronic CsA-induced nephrotoxicity in rats. Animals were randomly divided into four experimental groups: the control group received sunflower oil, the other groups were treated with CsA (25 mg/kg/day b.w. orally) or NSO (2 ml/kg orally) or CsA + NSO, respectively. Urine and serum creatinine levels, tissue superoxide dismutase, glutathione peroxidase and catalase enzyme activities, and nitric oxide and malondialdehyde levels were measured, and histological examination was performed. In our study, CsA caused a significant deterioration in the renal function, morphology and gave rise to severe oxidative stress in the kidney. NSO significantly improved the functional and histological parameters and attenuated the oxidative stress induced by CsA. In conclusion, our study demonstrated for the first time that NSO protects kidney tissue against oxygen free radicals, preventing renal dysfunction and morphological abnormalities associated with chronic CsA administration.