Nawal M. Al-Rasheed

C-peptide reverses TGF-β1-induced changes in renal proximal tubular cells: implications for treatment of diabetic nephropathy

The crucial pathology underlying progressive chronic kidney disease in diabetes is tubulointerstitial fibrosis. Central to this process is epithelial-mesenchymal transformation (EMT) of proximal tubular epithelial cells driven by maladaptive transforming growth factor-beta1 (TGF-beta1) signaling. Novel signaling roles for C-peptide have recently been discovered with evidence emerging that C-peptide may mitigate microvascular complications of diabetes. We studied the potential for C-peptide to interrupt injurious TGF-beta1 signaling pathways and thus block development of EMT in HK2 human kidney proximal tubular cells. Cells were incubated with TGF-beta1 either alone or with C-peptide in low or high glucose. Changes in cell morphology, TGF-beta1 receptor expression, vimentin, E-cadherin, and phosphorylated Smads were assessed. Luciferase reporters were used to assess Smad activity. The cytoskeleton was visualized by TRITC-phalloidin staining. The typical TGF-beta1-stimulated, EMT-associated morphological alterations of proximal tubular cells, including increased vimentin expression, decreased E-cadherin expression, and cytoskeletal rearrangements, were prevented by C-peptide treatment. C-peptide also blocked TGF-beta1-induced upregulation of expression of both type I and type II TGF-beta1 receptors and attenuated TGF-beta1-mediated Smad phosphorylation and Smad transcriptional activity. These effects of C-peptide were inhibited by pertussis toxin. The results demonstrate that C-peptide almost completely reversed the morphological changes in PT cells induced by TGF-beta1 and suggest a role or C-peptide as a renoprotective agent in diabetic nephropathy.

Sitagliptin attenuates cardiomyopathy by modulating the JAK/STAT signaling pathway in experimental diabetic rats

Sitagliptin, a dipeptidyl peptidase-4 inhibitor, has been reported to promote cardioprotection in diabetic hearts by limiting hyperglycemia and hyperlipidemia. However, little is known about the involvement of the Janus kinase/signal transducer and activator of transcription (JAK/STAT) pathway modulation in the cardioprotective effects of sitagliptin. The current study aimed to investigate the protective effects of sitagliptin against diabetic cardiomyopathy (DCM), focusing on the modulation of the JAK/STAT pathway. Diabetes was induced by streptozotocin injection, and rats received sitagliptin orally and daily for 90 days. Diabetic rats exhibited hyperglycemia, hyperlipidemia, and a significant increase in heart-to-body weight (HW/BW) ratio. Serum troponin I and creatine kinase MB, cardiac interleukin-6 (IL-6), lipid peroxidation, and nitric oxide levels showed significant increase in diabetic rats. In contrast, both enzymatic and nonenzymatic antioxidant defenses were significantly declined in the heart of diabetic rats. Histopathological study revealed degenerations, increased collagen deposition in the heart of diabetic rats. Sitagliptin alleviated hyperglycemia, hyperlipidemia, HW/BW ratio, histological architecture, oxidative stress, and inflammation, and rejuvenated the antioxidant defenses. In addition, cardiac levels of pJAK2 and pSTAT3 were increased in diabetic rats, an effect which was remarkably decreased after sitagliptin treatment. In conclusion, these results confer an evidence that sitagliptin has great therapeutic potential on DCM through down-regulation of the JAK/STAT signaling pathway.

Aqueous Date Flesh or Pits Extract Attenuates Liver Fibrosis via Suppression of Hepatic Stellate Cell Activation and Reduction of Inflammatory Cytokines, Transforming Growth Factor-β1 and Angiogenic Markers in Carbon Tetrachloride-Intoxicated Rats

Previous data indicated the protective effect of date fruit extract on oxidative damage in rat liver. However, the hepatoprotective effects via other mechanisms have not been investigated. This study was performed to evaluate the antifibrotic effect of date flesh extract (DFE) or date pits extract (DPE) via inactivation of hepatic stellate cells (HSCs), reducing the levels of inflammatory, fibrotic and angiogenic markers. Coffee was used as reference hepatoprotective agent. Liver fibrosis was induced by injection of CCl4 (0.4 mL/kg) three times weekly for 8 weeks. DFE, DPE (6 mL/kg), coffee (300 mg/kg), and combination of coffee + DFE and coffee + DPE were given to CCl4-intoxicated rats daily for 8 weeks. DFE, DPE, and their combination with coffee attenuated the elevated levels of inflammatory cytokines including tumor necrosis factor-α, interleukin-6, and interleukin-1β. The increased levels of transforming growth factor-β1 and collagen deposition in injured liver were alleviated by both extracts. CCl4-induced expression of α-smooth muscle actin was suppressed indicating HSCs inactivation. Increased angiogenesis was ameliorated as revealed by reduced levels and expression of vascular endothelial growth factor and CD31. We concluded that DFE or DPE could protect liver via different mechanisms. The combination of coffee with DFE or DPE may enhance its antifibrotic effects.

Preventive Effects of Selenium Yeast, Chromium Picolinate, Zinc Sulfate and their Combination on Oxidative Stress, Inflammation, Impaired Angiogenesis and Atherogenesis in Myocardial Infarction in Rats

PURPOSE Accumulating evidences suggest a critical role of trace metal dyshemostasis in oxidative stress and cardiac dysfunction after myocardial infarction (MI). This study investigated the cardioprotective effects of selenium yeast (Se), chromium picolinate Cr(pic)3, zinc sulfate (Zn) and their combination on isoproterenol (ISO)-induced MI. METHODS Rats were divided into six groups: normal control, ISO control, Se-pretreated (0.1 mg/kg), Cr(pic)3-pretreated (400 µg/kg), Zn-pretreated (30 mg/kg) and metal combination-pretreated groups. All metals were administered for 28 days and at the 27th day, MI was induced by subcutaneous injection of ISO (85 mg/kg) once for two consecutive days. RESULTS ISO control group showed hyperlipidemia, elevation of cardiac biomarkers and lipid peroxidation and increased immunostaining of p47 phox NADPH oxidase subunit in addition to decreased levels of glutathione (GSH), superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx). Cardiac levels of tumor necrosis factor-α (TNF-α) were increased, while vascular endothelial growth factor (VEGF, the major angiogenic factor) was decreased. Pretreatment with Se normalized the cardiac enzymes, lipid peroxidation, GSH, SOD, CAT, GPx, TNF-α and VEGF (P<0.001) and reduced the immunostaining of p47 phox subunit. However, Se failed to correct the dyslipidemia. Cr(pic)3 significantly improved lipid profile (P<0.001) and all other biochemical deviations except for VEGF. Zn, but to lesser extent, reduced the oxidative damage and TNF-α levels and improved both dyslipidemia and angiogenesis. Combination therapy exhibited less prominent protection compared to individual metals. CONCLUSION Daily supplementation with trace metals is promising for improving myocardial performance via preventing oxidative damage, induction of angiogenesis, anti-inflammatory and/or anti-hyperlipidemic mechanisms.

Simvastatin prevents isoproterenol-induced cardiac hypertrophy through modulation of the JAK/STAT pathway.

Simvastatin (SIM) is a lipid-soluble inhibitor of hydroxy-3-methylglutaryl coenzyme A reductase with multiple reported therapeutic benefits. The present study was designed to investigate the effect of pretreatment with SIM on isoproterenol (ISO)-induced cardiac hypertrophy in rats. Twenty-four male albino Wistar rats weighing 180–200 g were divided into four groups. Groups I and III received normal saline while groups II and IV received SIM (10 mg/kg body weight) for 30 days per gavage. In the last 7 days, rats of groups III and IV were administered ISO (5 mg/kg) intraperitoneally to induce cardiac hypertrophy. Administration of ISO induced an increase in heart-to-body weight (HW/BW) ratio, an increase in serum interleukin-6, and elevated systolic and diastolic blood pressure. Serum levels of lipids, cardiovascular risk indices, and cardiac troponin I and creatine phosphokinase-MB showed significant increase in ISO-induced hypertrophic rats. Histopathological examination of heart tissue revealed focal areas of subendocardium degeneration, mononuclear cellular infiltrations, fibrous tissue deposition, and increased thickness of the myocardium of left ventricle. In addition, ISO-administered rats exhibited significant upregulation of cardiac Janus kinase, phosphorylated signal transducer and activator of transcription, and nuclear factor-kappa B. Pretreatment with SIM significantly prevented ISO-induced cardiac hypertrophy, alleviated the altered biochemical parameters, and improved the heart architecture. In conclusion, our study provides evidence that SIM prevented the development of cardiac hypertrophy via modulation of the Janus kinase/signal transducer and activator of transcription-signaling pathway in the heart of ISO-administered animals.

Ruboxistaurin attenuates diabetic nephropathy via modulation of TGF-β1/Smad and GRAP pathways.

To investigate whether ruboxistaurin (a selective PKC‐β inhibitor) mediates renoprotective effect via interference with TGF‐β1/Smad‐GRAP cross‐signalling.

New mechanism in the modulation of carbon tetrachloride hepatotoxicity in rats using different natural antioxidants

Abstract Transforming growth factor-β (TGF-β1) enhances the expression of apoptosis induced by certain cytokines and oncogenes. Activation of small mother against decapentaplegic (Smads) by TGF-β results in fibrotic, apoptotic processes. PI-3/AKT focal adhesion kinase-phosphatidylinositol3-kinase (AKT), the mitogen-activated protein kinase (MAPK) and signal transducer and activator of transcription-3 (STAT3) pathways are influence in COX-2 and VEGF-stimulating pathways. NF-E2-related factor-2 (Nrf2) is an essential transcription factor that regulates an array of detoxifying and antioxidant defense genes expression in the liver. The objective of this study is to examine whether silymarin alone or in combination with vitamin E and/or curcumin plays a modulatory role against MAPK, STAT3, AKT, Smad-2 and TGF-β protein expressions that produced apoptotic damage in rat’s liver by the administration of carbon tetrachloride (CCl4). The results of the present work revealed that CCl4-induced an elevation of serum alanine aminotransferase (ALT) with concomitant increase in MAPK, STAT3, AKT, Smad-2 and TGF-β hepatic protein expression, administration of silymarin alone down regulates these expressions. Treatment with vitamin E and/or curcumin along with silymarin produced best results in this concern. On the other hand, Nrf2 protein expression was down regulated by CCl4 whereas concurrent treatment with vitamin E and/or curcumin along with silymarin increased this expression. It was concluded that CCl4-induced protein expression of apoptotic and fibenorgenic factors. Whereas administration of silymarin alone or in combination with vitamin E and/or curcumin plays a modulatory role against the previous aforementioned apoptotic factors expressions. The use of vitamin E and/or curcumin potentiates the anti-apoptotic action of silymarin. So this combination can be used as hepatoprotective agent against other hepatotoxic substances.

Simvastatin Ameliorates Diabetic Cardiomyopathy by Attenuating Oxidative Stress and Inflammation in Rats

Simvastatin is a lipid-lowering agent used to treat hypercholesterolemia and to reduce the risk of heart disease. This study scrutinized the beneficial effects of simvastatin on experimental diabetic cardiomyopathy (DCM), pointing to the role of hyperglycemia-induced oxidative stress and inflammation. Diabetes was induced by intraperitoneal injection of streptozotocin and both control and diabetic rats received simvastatin for 90 days. Diabetic rats showed significant cardiac hypertrophy, body weight loss, hyperglycemia, and hyperlipidemia. Serum creatine kinase MB (CK-MB) and troponin I showed a significant increase in diabetic rats. Simvastatin significantly improved body weight, attenuated hyperglycemia and hyperlipidemia, and ameliorated CK-MB and troponin I. Simvastatin prevented histological alterations and deposition of collagen in the heart of diabetic animals. Lipid peroxidation and nitric oxide were increased in the heart of diabetic rats whereas antioxidant defenses were decreased. These alterations were significantly reversed by simvastatin. In addition, simvastatin decreased serum inflammatory mediators and expression of NF-κB in the diabetic heart. Cardiac caspase-3 was increased in the diabetic heart and decreased following treatment with simvastatin. In conclusion, our results suggest that simvastatin alleviates DCM by attenuating hyperglycemia/hyperlipidemia-induced oxidative stress, inflammation, and apoptosis.

Date fruits inhibit hepatocyte apoptosis and modulate the expression of hepatocyte growth factor, cytochrome P450 2E1 and heme oxygenase-1 in carbon tetrachloride-induced liver fibrosis

Abstract Context: Date fruits have protective effects against liver fibrosis; however their anti-apoptotic effects have not been investigated. Objective: To investigate the modulating effects of date fruits on pro- and anti-apoptotic markers, cytochrome P450 2E1 (CYP2E1) and hepatocyte growth factor (HGF) in liver fibrosis. Materials and methods: Liver fibrosis was induced by injection of carbon tetrachloride (CCl4) for eight weeks. Date flesh extract (DFE) and pits extract (DPE) were taken daily concomitant with CCl4. Hepatocyte apoptosis was determined by measuring the expression of Fas, caspase-3, Bax, Bcl2 and hemeoxygenase-1 (HO-1). Hepatic levels of HGF and CYP2E1 were determined. Results: Treatment with DFE and DPE significantly attenuated the elevated levels of Fas, caspase 3, Bax and CYP2E1 induced by CCl4. In addition, they alleviated the reduction in Bcl2, HGF and HO-1, the cytoprotective and anti-apoptotic factors in liver. Conclusions DFE and DPE treatment can ameliorate liver fibrosis by inhibiting hepatocyte apoptosis.

Pulmonary prophylactic impact of melatonin and/or quercetin: A novel therapy for inflammatory hypoxic stress in rats

Abstract The study aims to compare, through histological and biochemical studies, the effects of quercetin, melatonin and their combination in regulation of immuno-inflammatory mediators and heat shock protein expressions in sodium nitrite induced hypoxia in rat lungs. The results revealed that NaNO2 injection caused a significant decrease in Hb in rats, while serum levels of TNF-α, IL-6 and CRP, VEGF and HSP70 were elevated compared to the control group. Administration of melatonin, quercetin or their combination before NaNO2 injection markedly reduced these parameters. Histopathological examination of the lung tissue supported these biochemical findings. The study suggests that melatonin and/or quercetin are responsible for lung tissue protection in hypoxia by downregulation of immuno-inflammatory mediators and heat shock protein expressions. Pre-treatment of hypoxic animals with a combination of melatonin and quercetin was effective in modulating most of the studied parameters to near-normal levels.