Ebtehal El-Demerdash

Vaspin and visfatin/Nampt are interesting interrelated adipokines playing a role in the pathogenesis of type 2 diabetes mellitus.

Recently, vaspin and visfatin/Nampt have been identified as interesting novel adipokines having insulin-sensitizing and insulin-mimetic effects, respectively. However, the relationship between them has not been elucidated; and their circulating levels in type 2 diabetes mellitus (T2DM) have not been adequately studied. Therefore, this study was designed to investigate whether their levels are altered in Egyptian T2DM patients and to study the correlation of these novel adipokines with each other and with insulin resistance, interleukin-6 (IL-6), and other biochemical parameters. The levels of vaspin, visfatin/Nampt, IL-6, insulin, and other parameters were measured in nonobese and obese T2DM patients together with matched healthy nondiabetic control subjects. Vaspin, visfatin/Nampt, and IL-6 levels were measured by enzyme-linked immunosorbent assay, whereas insulin levels were measured by chemiluminescence technique. Vaspin and visfatin/Nampt levels were found to be significantly elevated in nonobese (1.62 ± 0.22 and 25.9 ± 3.44 ng/mL, respectively) and obese T2DM patients (2.76 ± 0.38 and 45.4 ± 4.60 ng/mL, respectively) compared with control subjects (0.42 ± 0.05 and 9.37 ± 1.98 ng/mL, respectively) at P < .01. In addition, vaspin and visfatin/Nampt levels were found to be significantly positively correlated with each other and with other biochemical parameters. In conclusion, both vaspin and visfatin/Nampt might play an important role in the pathogenesis of T2DM. In addition, the 3 adipokines--vaspin, visfatin/Nampt, and IL-6--are significantly interrelated with each other. Other possible mechanisms of action for vaspin should be considered besides the inhibition of unknown substrate proteases.

Chrysin alleviates acute doxorubicin cardiotoxicity in rats via suppression of oxidative stress, inflammation and apoptosis.

Doxorubicin (DOX) is one of the most effective chemotherapeutic drugs; however, its incidence of cardiotoxicity compromises its therapeutic index. Chrysin, a natural flavone, possesses multiple biological activities, such as antioxidant, anti-inflammatory and anti-cancer. The present study was designed to investigate whether chrysin could protect against DOX-induced acute cardiotoxicity; and if so, unravel the molecular mechanisms of this protective effect. Chrysin was administered to male albino rats once daily for 12 consecutive days at doses of 25 and 50mg/kg orally. DOX (15 mg/kg; i.p.) was administered on day 12. Chrysin pretreatment significantly protected against DOX-induced myocardial damage which was characterized by conduction abnormalities, increased serum creatine kinase isoenzyme-MB (CK-MB), and lactate dehydrogenase (LDH) and myofibrillar disarrangement. As indicators of oxidative stress, DOX caused significant glutathione depletion, lipid peroxidation and reduction in activities of antioxidant enzymes; catalase (CAT) and superoxide dismutase (SOD). Chrysin pretreatment significantly attenuated DOX-induced oxidative injury. Additionally, DOX provoked inflammatory responses by increasing the expressions of nuclear factor kappa-B (NF-κB), inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) and the levels of tumor necrosis factor-alpha (TNF-α) and nitric oxide while chrysin pretreatment significantly inhibited these inflammatory responses. Furthermore, DOX induced apoptotic tissue damage by increasing Bax and cytochrome c expressions and caspase-3 activity while decreasing the expression of Bcl-2. Chrysin pretreatment significantly ameliorated these apoptotic actions of DOX. Collectively, these findings indicate that chrysin possesses a potent protective effect against DOX-induced acute cardiotoxicity via suppressing oxidative stress, inflammation and apoptotic tissue damage.

New therapeutic aspect for carvedilol: Antifibrotic effects of carvedilol in chronic carbon tetrachloride-induced liver damage

Portal hypertension is a common complication of chronic liver diseases associated with liver fibrosis and cirrhosis. At present, beta-blockers such as carvedilol remain the medical treatment of choice for protection against variceal bleeding and other complications. Since carvedilol has powerful antioxidant properties we assessed the potential antifibrotic effects of carvedilol and the underlying mechanisms that may add further benefits for its clinical usefulness using a chronic model of carbon tetrachloride (CCl4)-induced hepatotoxicity. Two weeks after CCl4 induction of chronic hepatotoxicity, rats were co-treated with carvedilol (10mg/kg, orally) daily for 6weeks. It was found that treatment of animals with carvedilol significantly counteracted the changes in liver function and histopathological lesions induced by CCl4. Also, carvedilol significantly counteracted lipid peroxidation, GSH depletion, and reduction in antioxidant enzyme activities; glutathione-S-transferase and catalase that was induced by CCl4. In addition, carvedilol ameliorated the inflammation induced by CCl4 as indicated by reducing the serum level of acute phase protein marker; alpha-2-macroglobulin and the liver expression of nuclear factor-kappa B (NF-κB). Finally, carvedilol significantly reduced liver fibrosis markers including hydroxyproline, collagen accumulation, and the expression of the hepatic stellate cell (HSC) activation marker; alpha smooth muscle actin. In conclusion, the present study provides evidences for the promising antifibrotic effects of carvedilol that can be explained by amelioration of oxidative stress through mainly, replenishment of GSH, restoration of antioxidant enzyme activities and reduction of lipid peroxides as well as amelioration of inflammation and fibrosis by decreasing collagen accumulation, acute phase protein level, NF-κB expression and finally HSC activation.

Protective effects of the angiotensin II receptor blocker losartan on cisplatin-induced kidney injury.

Background: In the present study, we investigated the possible modulatory effect of losartan, an angiotensin receptor blocker, on oxidative stress induced by cisplatin (CDDP) as well as on CDDP uptake by the kidney. Methods: Rats were injected with a single dose of CDDP (7 mg/kg) and/or losartan (in either a single dose of 60 mg/kg or divided doses (10 mg/kg daily for 6 days), starting 1 h before CDDP injection. In addition, rat renal cortical slices were incubated with CDDP (2 mM) and/or losartan (2 mM) for 4 h. Nephrotoxicity was evaluated by measuring serum creatinine and blood urea nitrogen (BUN) in vivo and lactate dehydrogenase (LDH) leakage in vitro; histopathological examination of kidney tissue was also done. Oxidative stress markers including reduced glutathione (GSH) and lipid peroxides were also assessed. Furthermore, CDDP uptake by renal cortical slices was determined. Results: Losartan has protective effects against CDDP-induced nephrotoxicity as evidenced by restoration of normal serum levels of creatinine and BUN, and LDH leakage. Histopathological examination of the kidney confirmed these results. Also, losartan significantly counteracted CDDP-induced lipid peroxidation and GSH depletion. However, losartan did not affect CDDP uptake by the kidney. Conclusion: Our results indicate that losartan has proved to be a promising drug for clinical use as a nephroprotectant against CDDP-induced nephrotoxicity.

Epigallocatechin-3-gallate pretreatment attenuates doxorubicin-induced cardiotoxicity in rats: A mechanistic study.

Doxorubicin (DOX) is a widely used chemotherapeutic agent however its clinical use is limited by cumulative cardiotoxicity. Epigallocatechin-3-gallate (EGCG), a main catechin in green tea, possesses a potent antioxidant, anti-apoptotic and anticancer properties. The current study aimed to investigate the potential protective effect of EGCG against DOX-induced cardiotoxicity. Firstly the potential cardioprotective dose of EGCG was screened at different doses (10, 20 and 40 mg/kg/day) against a single dose of DOX (15 mg/kg; i.p.). EGCG protected against DOX-induced ECG changes, leakage of cardiac enzymes (creatine kinase isoenzyme-MB, and lactate dehydrogenase) and histopathological changes. The dose of 40 mg/kg EGCG was selected for further assessment to address the EGCG cardioprotective mechanisms. EGCG was given orally 3 times/week for 4 consecutive weeks and DOX (2.5 mg/kg; i.p.) 3 times/week on the last 2 weeks. EGCG significantly ameliorated oxidative stress injury evoked by DOX as evidenced by inhibition of reduced glutathione depletion and lipid peroxidation as well as elevation of antioxidant enzyme activities. DOX caused down-regulation of ErbB2 expression while EGCG pretreatment significantly increased ErbB2 expression indicating its effect on pro-survival pathway. Furthermore, DOX provoked apoptotic responses evidenced by increasing the expression of nuclear factor kappa-B, tumor suppressor protein p53, calpain 2, caspases 3 and 12. Additionally basal level of Hsp70 was reduced in DOX-intoxicated group. EGCG pretreatment significantly ameliorated these apoptotic signals indicating its anti-inflammatory and anti-apoptotic actions. In conclusion, EGCG possesses cardioprotective action against DOX-induced cardiotoxicity by suppressing oxidative stress, inflammation and apoptotic signals as well as activation of pro-survival pathways.

Effect of taurine supplementation on hyperhomocysteinemia and markers of oxidative stress in high fructose diet induced insulin resistance

BackgroundHigh intake of dietary fructose is accused of being responsible for the development of the insulin resistance (IR) syndrome. Concern has arisen because of the realization that fructose, at elevated concentrations, can promote metabolic changes that are potentially deleterious. Among these changes is IR which manifests as a decreased biological response to normal levels of plasma insulin.MethodsOral glucose tolerance tests (OGTT) were carried out, homeostasis model assessment of insulin resistance (HOMA) was calculated, homocysteine (Hcy), lipid concentrations and markers of oxidative stress were measured in male Wistar rats weighing 170-190 g. The rats were divided into four groups, kept on either control diet or high fructose diet (HFD), and simultaneously supplemented with 300 mg/kg/day taurine via intra-peritoneal (i.p.) route for 35 days.ResultsFructose-fed rats showed significantly impaired glucose tolerance, impaired insulin sensitivity, hypertriglyceridemia, hypercholesterolemia, hyperhomocysteinemia (HHcy), lower total antioxidant capacity (TAC), lower paraoxonase (PON) activity, and higher nitric oxide metabolites (NOx) concentration, when compared to rats fed on control diet. Supplementing the fructose-fed rats with taurine has ameliorated the rise in HOMA by 56%, triglycerides (TGs) by 22.5%, total cholesterol (T-Chol) by 11%, and low density lipoprotein cholesterol (LDL-C) by 21.4%. Taurine also abolished any significant difference of TAC, PON activity and NOx concentration among treated and control groups. TAC positively correlated with PON in both rats fed on the HFD and those received taurine in addition to the HFD. Fructose-fed rats showed 34.7% increase in Hcy level. Taurine administration failed to prevent the observed HHcy in the current dosage and duration.ConclusionOur results indicate that HFD could induce IR which could further result in metabolic syndrome (MS), and that taurine has a protective role against the metabolic abnormalities induced by this diet model except for HHcy.

Thymoquinone blocks lung injury and fibrosis by attenuating bleomycin-induced oxidative stress and activation of nuclear factor Kappa-B in rats

Pulmonary fibrosis is one of the most common chronic interstitial lung diseases with high mortality rate after diagnosis and limited successful treatment. The present study was designed to assess the potential antifibrotic effect of thymoquinone (TQ) and whether TQ can attenuate the severity of oxidative stress and inflammatory response during bleomycin-induced pulmonary fibrosis. Male Wister rats were treated intraperitoneally with either bleomycin (15 mg/kg, 3 times a week for 4 weeks) and/or thymoquinone (5mg/kg/day, 1 week before and until the end of the experiment). Bleomycin significantly increased lung weight and the levels of Lactate dehydrogenase, total leucocytic count, total protein and mucin in bronchoalveolar lavage and these effects were significantly ameliorated by TQ treatment. As markers of oxidative stress, bleomycin caused a significant increase in the levels of lipid peroxides and nitric oxide accompanied with a significant decrease in the antioxidant enzyme activity of superoxide dismutase and glutathione transferase. TQ treatment restored these markers toward normal values. TQ also counteracted emphysema in air alveoli, inflammatory cell infiltration, lymphoid hyperplastic cells activation surrounding the bronchioles and the over expression of activated form of nuclear factor kappa-B (NF-B) in lung tissue that was induced by bleomycin. Fibrosis was assessed by measuring hydroxyproline content, which increased markedly in the bleomycin group and significantly reduced by concurrent treatment with TQ. Furthermore, histopathological examination confirmed the antifibrotic effect of TQ. Collectively these findings indicate that TQ has potential antifibrotic effect beside its antioxidant activity that could be through NF-κB inhibition.

Chloroquine synergizes sunitinib cytotoxicity via modulating autophagic, apoptotic and angiogenic machineries

Tyrosine kinases play a pivotal role in oncogenesis. Although tyrosine kinase inhibitors as sunitinib malate are used in cancer therapy, emerging studies report compromised cytotoxicity when used as monotherapy and thus combinations with other anti-cancer agents is recommended. Chloroquine is a clinically available anti-malarial agent which has been shown to exhibit anti-cancer activity. In the current study, we questioned whether chloroquine can modulate sunitinib cytotoxicity. We found that chloroquine synergistically augmented sunitinib cytotoxicity on human breast (MCF-7 and T-47D), cervical (Hela), colorectal (Caco-2 and HCT116), hepatocellular (HepG2), laryngeal (HEp-2) and prostate (PC3) cancer cell lines as indicated by combination and concentration reduction indices. These results were also consistent with that of Ehrlich ascites carcinoma (EAC) Swiss albino mice models as confirmed by tumor volume, weight, histopathological examination and PCNA expression. Sunitinib induced autophagy via upregulating beclin-1 expression which was blocked by chloroquine as evidenced by accumulated SQTSM1/p62 level. Furthermore, chloroquine augmented sunitinib-induced apoptosis by decreasing survivin level and increasing caspase 3 activity. Chloroquine also enhanced the antiangiogenic capacity of sunitinib as indicated by decreased CD34 expression and peritoneal/skin angiogenesis. Sunitinib when combined with chloroquine also increased reactive nitrogen species production via increasing inducible nitric oxide synthase expression and nitric oxide level whilst reduced reactive oxygen species production by increasing GSH level, activities of glutathione peroxidase and catalase and reducing lipid peroxides compared to sunitinib-only treated group. Taken together, these findings suggest that chloroquine enhanced sunitinib cytotoxicity in a synergistic manner via inducing apoptosis while switching off autophagic and angiogenic machineries. Nevertheless, further studies are required to elucidate the efficacy and safety profile of such combination.

Anti-inflammatory activity of methyl palmitate and ethyl palmitate in different experimental rat models

Methyl palmitate (MP) and ethyl palmitate (EP) are naturally occurring fatty acid esters reported as inflammatory cell inhibitors. In the current study, the potential anti-inflammatory activity of MP and EP was evaluated in different experimental rat models. Results showed that MP and EP caused reduction of carrageenan-induced rat paw edema in addition to diminishing prostaglandin E2 (PGE2) level in the inflammatory exudates. In lipopolysaccharide (LPS)-induced endotoxemia in rats, MP and EP reduced plasma levels of tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6). MP and EP decreased NF-κB expression in liver and lung tissues and ameliorated histopathological changes caused by LPS. Topical application of MP and EP reduced ear edema induced by croton oil in rats. In the same animal model, MP and EP reduced neutrophil infiltration, as indicated by decreased myeloperoxidase (MPO) activity. In conclusion, this study demonstrates the effectiveness of MP and EP in combating inflammation in several experimental models.

Anti-inflammatory and antifibrotic effects of methyl palmitate.

Methyl palmitate (MP) has been shown earlier to inhibit Kupffer cells and rat peritoneal macrophages. To evaluate the potential of MP to inhibit the activation of other macrophages, RAW cells (macrophages of alveolar origin) were treated with varying concentrations of MP (0.25, 0.5, 1mM). Assessment of cytotoxicity using MTT assay revealed that 0.25 and 0.5mM are not toxic to RAW cells. MP was able to inhibit the phagocytic function of RAW cells. Treatment of cells with MP 24hours prior to LPS stimulation significantly decreased nitric oxide release and altered the pattern of cytokines release; there was a significant decrease in TNF-α and a significant increase in IL-10 compared to the controls. However, there is a non-significant change in IL-6 level. Furthermore, phosphorylation of inhibitory kappa B (IκBα) protein was significantly decreased in RAW cells treated with 0.5mM MP after LPS stimulation. Based upon the in-vitro results, it was examined whether MP treatment will be effective in preventing bleomycin-induced lung inflammation and fibrosis in-vivo. Bleomycin given by itself caused destruction of the lung architecture characterized by pulmonary fibrosis with collapse of air alveoli and emphysematous. Bleomycin induced a significant increase in hydroxyproline level and activated NF-κB, p65 expression in the lung. MP co-treatment significantly ameliorated bleomycin effects. These results suggest that MP has a potential of inhibiting macrophages in general. The present study demonstrated for the first time that MP has anti-inflammatory and antifibrotic effect that could be through NF-kB inhibition. Thus MP like molecule could be a promising anti-inflammatory and antifibrotic drug.