Rosiglitazone, peroxisome proliferator receptor-gamma agonist, ameliorates gentamicin-induced nephrotoxicity in rats

Involvement of oxidative stress and toll-like receptor-4 signaling pathways in gentamicin-induced nephrotoxicity in male Sprague Dawley rats

Gentamicin (GM) is an antibiotic belonging to an aminoglycoside family that might induce nephrotoxicity in human and animal models via oxidative stress. Toll-like receptors (TLRs) are part of innate immune systems that participate in inflammatory responses. In this regard, we investigated the effect of GM on kidney functional and structural parameters, enzymatic antioxidant levels, and mRNA expression of TLR4 and IL6 in the rat kidney. Adult male Sprague Dawley rats were randomly divided into two groups (n = 10): Control and Gentamicin (100 mg/kg, i.p.). After ten days of GM administration, a blood sample was taken, and the kidneys were removed. The serum levels of creatinine (Cr) and blood urea nitrogen (BUN) were measured. Furthermore, the right kidney was preserved in formalin 10% for hematoxylin and eosin (H&E) staining, and the left kidney was kept at -80 °C for molecular and oxidative indexes analysis. Administration of GM caused tubular damages and functional disturbance. So that, Cr and BUN values in the GM group were higher than Control group. Furthermore, molecular findings showed upregulation of TLR4 and IL-6 mRNA expression in renal tissue of the GM-received group. In this study, superoxide dismutase (SOD) activity was slightly increased as a compensatory mechanism in response to elevated malondialdehyde (MDA) levels in the GM-treated group. On the other hand, the activity of catalase (CAT) and glutathione peroxidase (GPx) were significantly declined. Our results demonstrated that oxidative stress and subsequent TLR4 upregulation signaling pathways are involved in GM-induced nephrotoxicity.

Telmisartan inhibits oxalate and calcium oxalate crystal-induced epithelial-mesenchymal transformation via PPAR-γ-AKT/STAT3/p38 MAPK-Snail pathway

AIMS

Telmisartan (TLM), a highly selective angiotensin II type 1 receptor blocker (ARB) and partial PPAR-γ agonist, has versatile beneficial effects against oxidative stress, apoptosis, inflammatory responses and epithelial-mesenchymal transition (EMT). However, its underlying mechanism of inhibiting oxalate and calcium oxalate (CaOx) crystal-induced EMT by activating the PPAR-γ pathway remains unclear.

MAIN METHODS

CCK-8 assays were used to evaluate the effects of TLM on cell viability. In addition, intracellular reactive oxygen species (ROS) levels were measured by the cell-permeable fluorogenic probe 2,7-dichlorofluorescein diacetate (DCFH-DA). Wound-healing and Transwell assays were used to evaluate the migration ability of HK2 cells exposed to oxalate. Moreover, immunofluorescence, immunohistochemistry and western blotting were used to examine the expression of E-cadherin, N-cadherin, vimentin and α-SMA and explore the underlying molecular mechanisms in HK2 cells and a stone-forming rat model.

KEY FINDINGS

Our results showed that TLM treatment could protect HK2 cells from oxalate-induced cytotoxicity and oxidative stress injury. Additionally, TLM prevented EMT induction by oxalate and CaOx crystals via the PPAR-γ-AKT/STAT3/p38 MAPK-Snail pathway in vitro and in vivo. However, knockdown of PPAR-γ with small interfering RNA or the PPAR-γ-specific antagonist GW9662 abrogated these protective effects of TLM.

SIGNIFICANCE

As a PPAR-γ agonist, TLM can ameliorate oxalate and CaOx crystal-induced EMT by exerting an antioxidant effect through the PPAR-γ-AKT/STAT3/p38 MAPK-Snail signaling pathway. Therefore, TLM can block EMT progression and could be a potential therapeutic agent for preventing and treating calcium oxalate urolithiasis formation and recurrence.

All-trans retinoic acid prevents cisplatin-induced nephrotoxicity in rats

The aim of this study is to investigate the effects of all-trans retinoic acid (ATRA) use on cisplatin (CP)-induced nephrotoxicty. Twenty-eight rats were randomly divided into four groups. The rats in the control group were injected a single dose of 1 ml/kg saline intra-peritoneally (IP) during 10 days. The rats in the ATRA group were injected a single dose of ATRA during 10 days. The rats in the ATRA+CP group were injected a single dose of CP on the fourth day of the 10 days of ATRA treatment. The rats in the CP group were injected a single dose of CP on the fourth day of 10 days without administering a treatment. After treatment, the groups were compared with regard to total antioxidant status (TAS), total oxidant status (TOS), and oxidative stress index (OSI) levels in renal tissue and renal histopathology. The serum creatinine and urea values were statistically significantly higher in the CP group compared to the other groups. The serum creatinine and urea values were statistically significantly lower in the ATRA+CP group when compared to the CP group. Although the TOS and OSI levels were found to be lower in the ATRA+CP group compared to the CP group, the difference was not statistically significant. Administration of ATRA together with CP was observed to reduce the histopathologic destruction in the kidney and lead to mild tubular degeneration, vacuolization, and necrosis (57.1% grade 1; 28.6% grade2, and 14.3% grade 3 necrosis). The results of the present study have revealed that ATRA administration ameliorates CP-induced nephrotoxicity; however, further studies are required to identify this issue before clinical application.

Key role of oxidative stress in animal models of aminoglycoside nephrotoxicity revealed by a systematic analysis of the antioxidant-to-nephroprotective correlation

The clinical utility of aminoglycoside antibiotics is partly limited by their nephrotoxicity. Co-administration of a variety of candidate nephroprotectants has been tested at the preclinical level. According to a recent meta-analytic study, antioxidants are the only family of compounds with enough preclinical documentation to draw solid conclusions on their class nephroprotective capacity in animal models. In this study a systematic analysis of the relation between the level of antioxidation and the level of nephroprotection was performed. A regression model is presented which crosses the y-axis (i.e. the axis representing the level of nephroprotection) very nearly the zero value, meaning that maximal prevention of the oxidative stress induced by aminoglycosides results in almost maximal nephroprotection. This indicates that oxidative stress plays a central role in the hierarchy of pathophysiological mechanisms underlying aminoglycoside nephrotoxicity. In addition, this model may potentially serve: i) as a standard to evaluate the role of the antioxidant effect of candidate nephroprotectants; ii) to reveal additional, antioxidant-independent effects among those compounds providing more nephroprotection than that expected from its antioxidant activity; and thus iii) to discriminate and focus most effective nephroprotectants on clinical usage.

A systematic meta-analysis on the efficacy of pre-clinically tested nephroprotectants at preventing aminoglycoside nephrotoxicity

Nephrotoxicity limits the use of aminoglycoside antibiotics. Kidney damage is produced mainly in the renal tubule due to an inflammatory and oxidative process. At preclinical level, many drugs and natural products have been tested as prospective protectors of aminoglycoside nephrotoxicity. The main objective of this work was to make a systematic literature review of preclinical studies about aminoglycoside nephrotoxicity protection and a statistical analysis based on the meta-analysis methodology. Studies published up to January 2016 were identified. After applying inclusion criteria, 54 studies were chosen. The size of the experimental groups, means and standard deviations of data on renal function (i.e. plasma creatinine and blood urea nitrogen [BUN] concentrations) were extracted and registered in a database. The studies were grouped according to the mechanism of nephroprotection and their route of administration. The Mean Difference (95% confidence interval) was calculated for each study and group. 40 of 54 products tested produced an amelioration of aminoglycoside nephrotoxicity based on creatinine results. Also a dose dependent protective effect was observed (both in creatinine and BUN). Products orally administered were more effective than via i.p. Products with attributed antioxidant activity were the most used and those which proved statistically significant nephroprotection as a class effect. Aminoglycoside tubular reuptake inhibitors, excretion inducers and calcium channel blockers also showed a promising and rather homogeneous class tendency towards nephroprotection, although more research is necessary to obtain solid and conclusive results, based on a larger number of studies.

In-vivo antioxidant and anti-inflammatory activity of rosiglitazone, a peroxisome proliferator-activated receptor-gamma (PPAR-γ) agonists in animal model of bronchial asthma

OBJECTIVES

Peroxisome proliferator activated receptor-gamma (PPAR-γ) has been shown to play an important role in the control of immunological and inflammatory responses. This study aims at investigating the potential role of rosiglitazone, a strong PPAR-γ agonist in a murine model of bronchial asthma.

METHODS

Adult male guinea pigs were administered ovalbumin 100 mg/kg subcutaneous (SC) and 100 mg/kg intraperitoneal (IP). Treatment with rosiglitazone [5 mg/kg/day, per oral (PO)] was assessed for 21 days. On day 21, the animals were challenged with the same dose of ovalbumin. The forced expiratory volume in 1 s (FEV1 ) to forced vital capacity (FVC), FEV1 /FVC, was measured using a spirometer to diagnosis lung obstruction. Serum levels of interleukin-5 (IL-5) and immunoglobulin E (IgE) were assessed. The activity of superoxide dismutase (SOD) and catalase and the level of reduced glutathione (GSH) were determined in lung tissue homogenates.

KEY FINDINGS

Our results demonstrated that treatment with rosiglitazone resulted in a statistically significant improvement in lung function and histopathological features. Significant decrease in the serum levels of IL-5 and IgE were observed. The activity of SOD and catalase as well as the GSH level were significantly increased in the lung tissues of treated animals compared with untreated asthmatic animals. Serum IgE concentrations and IL-5 levels were directly correlated to each other and inversely correlated to the SOD, GSH and catalase levels in the all studied guinea pigs.

CONCLUSIONS

Our results provide evidence that the PPAR-γ agonist rosiglitazone may have potential in the development of therapies for bronchial asthma.

Pioglitazone improves cognitive function via increasing insulin sensitivity and strengthening antioxidant defense system in fructose-drinking insulin resistance rats

Insulin resistance (IR) links Alzheimer’s disease (AD) with oxidative damage, cholinergic deficit, and cognitive impairment. Peroxisome proliferator-activated receptor γ (PPARγ) agonist pioglitazone previously used to treat type 2 diabetes mellitus (T2DM) has also been demonstrated to be effective in anti-inflammatory reaction and anti-oxidative stress in the animal models of AD and other neuroinflammatory diseases. Here, we investigated the effect of pioglitazone on learning and memory impairment and the molecular events that may cause it in fructose-drinking insulin resistance rats. We found that long-term fructose-drinking causes insulin resistance, oxidative stress, down-regulated activity of cholinergic system, and cognitive deficit, which could be ameliorated by pioglitazone administration. The results from the present study provide experimental evidence for using pioglitazone in the treatment of brain damage caused by insulin resistance.

Induction of oxidative stress in kidney

Oxidative stress has a critical role in the pathophysiology of several kidney diseases, and many complications of these diseases are mediated by oxidative stress, oxidative stress-related mediators, and inflammation. Several systemic diseases such as hypertension, diabetes mellitus, and hypercholesterolemia; infection; antibiotics, chemotherapeutics, and radiocontrast agents; and environmental toxins, occupational chemicals, radiation, smoking, as well as alcohol consumption induce oxidative stress in kidney. We searched the literature using PubMed, MEDLINE, and Google scholar with “oxidative stress, reactive oxygen species, oxygen free radicals, kidney, renal injury, nephropathy, nephrotoxicity, and induction”. The literature search included only articles written in English language. Letters or case reports were excluded. Scientific relevance, for clinical studies target populations, and study design, for basic science studies full coverage of main topics, are eligibility criteria for articles used in this paper.

PPARγ as a therapeutic target in diabetic nephropathy and other renal diseases

PURPOSE OF REVIEW

Peroxisome proliferator-activated receptor gamma (PPARγ) is a ligand-activated nuclear transcription factor that regulates many important physiological processes including glucose and lipid metabolism, energy homeostasis, cell proliferation, inflammation, immunity and reproduction. The current review aims to summarize and discuss recent findings evaluating the protective effects of PPARγ against kidney diseases with a focus on diabetic nephropathy. We will also delineate the potential underlying mechanisms.

RECENT FINDINGS

PPARγ plays important roles in renal physiology and pathophysiology. Agonists of PPARγ exert protective effects against various kidney diseases including diabetic nephropathy, ischemic renal injury, IgA nephropathy, chemotherapy-associated kidney damage, polycystic kidney diseases and age-related kidney diseases via both systemic and renal actions.

SUMMARY

PPARγ agonists are effective in delaying and even preventing the progression of many renal diseases, especially diabetic nephropathy. PPARγ may represent a promising target for the treatment of renal diseases.

Protective effect of hydrogen-rich water against gentamicin-induced nephrotoxicity in rats using blood oxygenation level-dependent MR imaging

PURPOSE

We assessed intrarenal oxygenation in gentamicin-induced nephrotoxicity (GIN) and the protective effect of hydrogen-rich water (HW) against GIN using blood oxygenation level-dependent magnetic resonance (MR) imaging.

MATERIALS AND METHODS

We acquired T(2)*-weighted images (T(2)*WI) of 21 rats on Days 0, 2, 4, and 7 using a 1.5-tesla MR imaging system. The rats were divided into 3 groups of seven each: control rats had free access to standard water and no gentamicin (GM) injection; rats designated the GM group had free access to standard water and were injected with GM (80 mg/kg/day) subcutaneously for 7 days; and the third group, designated the GM+HW group, had free access to HW and were injected with GM. R(2)* (=1/T(2)*) was estimated from T(2)*WI.

RESULTS

R(2)* values in the cortex were significantly decreased on Days 2, 4, and 7 compared with those on Day 0 in the GM group but not significantly changed in the control and GM+HW groups. R(2)* values in the medulla did not change significantly in any group.

CONCLUSIONS

Our findings suggested reduced oxygen utility, mainly in the cortex, in gentamicin-induced nephrotoxicity and an ameliorative effect of hydrogen-rich water against GIN.