In vitro effects of resveratrol on oxidative stress in diabetic platelets

Opportunities and challenges of polyphenols and polysaccharides for type 1 diabetes intervention

Type 1 diabetes (T1D) is an autoimmune disorder characterized by the destruction of insulin-producing pancreatic β cell. It contributes to high mortality, frequent diabetic complications, poor quality of life in patients and also puts a significant economic burden on health care systems. Therefore, the development of new therapeutic strategies is urgently needed. Recently, certain dietary compounds with potential applications in food industry, particularly polyphenols and polysaccharides, have gained increasing attention with their prominent anti-diabetic effects on T1D by modulating β cell function, the gut microbiota and/or the immune system. In this review, we critically discuss the recent findings of several dietary polyphenols and polysaccharides with the potential to protect against T1D and the underlying anti-diabetic mechanisms. More importantly, we highlight the current trends, major issues, and future directions of industrial production of polyphenols- and polysaccharides-based functional foods for preventing or delaying T1D.

De Novo Hepatocellular Carcinoma in Hepatitis C-Related Cirrhosis: Are Advanced Glycation End Products a Key Driver?

Background and Purpose

The advanced glycation end products (AGEs) have been implicated in different diseases’ pathogenesis, but their role in hepatocellular carcinoma (HCC) is still a matter of debate. This study aims to investigate the association of AGEs with HCC development in patients with hepatitis C-related cirrhosis.

Methods

Only 153 of the 181 non-diabetic patients with cirrhosis were consecutively involved in this pilot cohort prospective study, along with 34 healthy control participants. Demographic characteristics, biochemical parameters, clinical data, and AGEs levels in all subjects at the starting point and every year after that for two years were assessed. Multivariable Cox regression analysis was used to settle variables that could predict HCC development within this period.

Results

HCC developed in 13 (8.5%) patients. Univariate Cox regression analysis reported that body mass index (P=0.013), homeostatic model assessment-insulin resistance (P=0.006), alpha-fetoprotein (P <0.001), and AGEs levels (P <0.001) were related to HCC development. After adjusting multiple confounders, the multivariable Cox regression model has revealed that AFP and AGEs were the powerful parameters related to the HCC occurrence (all P<0.05). AGEs at a cutoff value of more than 79.6 ng/ml had 100% sensitivity, 96.4% specificity, and 0.999 area under the curve (all P<0.001), using the receiver operating characteristic curve, for prediction of HCC development.

Conclusion

This work suggests that AGEs are associated with an increased incidence of HCC, particularly in cirrhosis, which is encouraging in decreasing the risk of HCC in these patients.

Advanced Glycation End Products as a Predictor of Diabetes Mellitus in Chronic Hepatitis C-Related Cirrhosis

Background and Aims: Advanced glycation end products (AGEs) were found to be involved in the pathogenesis of various disorders. Chronic hepatitis C virus infection is the major cause of liver cirrhosis development and glucose metabolism alteration. We aimed to explore the association of AGEs with the development of diabetes mellitus (DM) in patients with cirrhosis in this study.

Methods: Only 144 of the 165 non-diabetic patients with cirrhosis were consecutively included in this prospective cohort pilot study, in addition to 72 healthy control subjects. Clinical data and biochemical parameters including basal insulin secretion and insulin sensitivity indices together with AGEs were evaluated in all participants at baseline and every 1 year thereafter for 2 years. Multivariable Cox regression analysis was used to determine the parameters that could predict the development of DM within this period.

Results: DM developed in 14 (10%) patients only. Univariate Cox regression analysis showed that AGEs (P = 0.004), Homeostatic Model Assessment-Insulin Resistance (HOMA-IR) (P = 0.018), HOMA-β (P = 0.015), and age (P = 0.012) were associated with DM. After adjusting multiple confounders, the multivariable Cox regression model showed that AGEs, HOMA-IR, and age were the strongest variables associated with DM (all P < 0.05). Using the receiver operating characteristic curve, AGEs at a cutoff value of more than 82.4 ng/ml had 99.23% specificity, 100% sensitivity, and 0.992 area under the curve (AUC) (all P < 0.001) for DM prediction.

Conclusion: Our study suggests that AGEs are related to increased incidence of DM, especially in patients with cirrhosis, which is very promising in lowering the risk of DM in these patients.

Resveratrol ameliorates renal damage by inhibiting oxidative stress-mediated apoptosis of podocytes in diabetic nephropathy

Diabetic nephropathy (DN) is the major cause of end-stage renal disease. Resveratrol (RSV) has been shown to exert a renoprotective effect against DN, but despite research progress, the protective mechanisms of RSV have not been fully elucidated. Here, we demonstrated that RSV relieved a series of pathological characteristics of DN and attenuated oxidative stress and apoptosis in the renal tissues of diabetic (db/db) mice. In addition, RSV inhibited oxidative stress production and apoptosis in human podocytes exposed to high glucose. Furthermore, inhibition of reactive oxygen species generation by reactive oxygen species scavengers N-acetylcysteine and 2,2,6,6-tetramethyl-1-piperidinyloxy had the same anti-apoptosis effects on podocytes as did RSV. Finally, we found that 5' adenosine monophosphate-activated protein kinase (AMPK) was activated by RSV in db/db mice and podocytes exposed to high glucose. The protective effects of RSV on podocytes were suppressed by Compound C, a pharmacological inhibitor of AMPK. Together, our results indicate that RSV effectively attenuated renal damage by suppressing oxidative stress-mediated apoptosis of podocytes, which was dependent on AMPK activation. This study revealed a possible mechanism to protect podocytes against apoptosis in DN.

Obesity and ultrasound-estimated visceral fat deposits in women undergoing Assisted Reproductive Technology (ART) procedures

The aim of this study was to evaluate the influence of body mass index (BMI) and ultrasound-estimated visceral adipose tissue deposits on oocyte quality and pregnancy rate in women undergoing Assisted Reproductive Technology (ART) procedures. The study included 58 women who underwent ART procedures. According to their BMI, the women were divided into normal weight and overweight/obese; an ultrasound evaluation of preperitoneal fat thickness (PFT) was also performed for each patient. The oocyte quality was then assessed, and samples of follicular fluid were collected from each woman, in order to evaluate the intrafollicular concentration of reactive oxygen species (ROS) as markers of oxidative stress and pro-inflammatory cytokines (IL-1β and IL-6) as markers of chronic inflammation. A negative correlation was found between BMI (as well as PFT) and the number of retrieved oocytes (r = -0.3; p <0.05 and r = -0.5; p < 0.001, respectively), good quality oocytes (r = -0.4; p = <0.05) and obtained embryos (r = -0.3; p < 0.05). In women undergoing ART procedures, BMI and PFT negatively influence the number of oocytes retrieved and their quality. However, on multivariable analysis, only age, PFT and number of retrieved oocytes affect the success rate of ART procedures.

Effects of long-term resveratrol-induced SIRT1 activation on insulin and apoptotic signalling in aged skeletal muscle

AIMS

Activation of Foxo1 is known to promote apoptosis and disturbances to insulin signalling. However, their modulating roles in aged skeletal muscle are not clear. The present study tested the hypothesis that long-term (i.e. 8 month) resveratrol supplementation would improve physical traits including exercise capacity and basal voluntary activity of aged mice and modulate insulin/apoptotic signalling in aged skeletal muscle. This study also examined whether these resveratrol-associated alterations would involve orchestration of the SIRT1-Foxo1 signalling axis.

METHODS

Two-month-old SAMP8 mice were randomly assigned to young, aged and aged with resveratrol treatment (AR) groups. The AR mice were supplemented with 4.9 mg(-1) kg(-1) day(-1) resveratrol for 8 months. All animals were subject to endurance capacity test and voluntary motor behaviour assessment. The lateral gastrocnemius muscle tissues were harvested for further analyses.

RESULTS

Long-term resveratrol treatment significantly alleviated the age-associated reductions in exercise capacity and voluntary motor behaviour. The protein content, but not the deacetylase activity of SIRT1 was increased with concomitant elevations of p300 acetylase and acetylation of Foxo1 in aged muscle. The aged muscle also manifested signs of impaired insulin signalling including attenuated phosphorylation of Akt, activity of pyruvate dehydrogenase and membrane trafficking of GLUT4 and elevated levels of phosphorylated IRS1 and iNOS and apoptotic activation measured as Bim, p53 and apoptotic DNA fragmentation. Intriguingly, all these age-related adverse changes were mitigated with the activation of SIRT1 deacetylase activity after long-term resveratrol treatment.

CONCLUSIONS

These data suggest that modulation of the SIRT1-Foxo1 axis by long-term resveratrol treatment enhances physical traits and alleviates the unfavourable changes in insulin and apoptotic signalling in aged muscle.

Advanced glycation end product (AGE)-induced hepatic stellate cell activation via autophagy contributes to hepatitis C-related fibrosis

AIMS

Advanced glycation end products (AGEs) have been implicated in pulmonary and renal fibrosis. Herein, we investigated whether AGEs are associated with liver fibrosis and examined the underlying mechanism by focusing on hepatic stellate cell (HSC) activation and autophagy induction.

METHODS

Liver fibrosis was assessed by transient elastography (FibroScan). Serum AGE levels were determined by ELISA. Rat primary HSCs and HSC-T6 were treated with BSA-AGEs, cell proliferation was examined by WST-1 assay, and cell activation was evaluated by qPCR for transcripts of α-SMA and collagen type Iα1 and by Western blotting. Autophagy was measured by detection of LC3-II lipidation, p62 degradation, and puncta GFP-LC3 formation. Receptor of AGE (RAGE)-blocking antibodies and soluble RAGE were employed to inhibit AGE-RAGE signaling.

RESULTS

First, elevated AGE levels were observed in CHC patients than patients with chronic hepatitis B, especially in those with insulin resistance. Second, compared to controls, AGE-treated rat primary HSCs displayed an enhanced cell proliferation (1.39-fold), increased transcripts of α-SMA (2.40-fold) and proCOL1A1 (1.76-fold), and a higher level of α-SMA protein (1.85-fold). Moreover, AGE-induced HSC activation improved autophagy flux, as evidenced by significantly more LC3-II lipidation, p62 degradation, as well as GFP-LC3 puncta formations. In addition, our results showed that AGE-induced HSC autophagy and HSC activation could be reduced by RAGEs.

CONCLUSION

AGEs were found to induce autophagy and activation of HSCs, which subsequently contributes to the fibrosis in CHC patients. Blocking AGE-RAGE signaling may be a promising way to alleviate fibrosis.

Effects of in vitro supplementation with Syzygium cumini (L.) on platelets from subjects affected by diabetes mellitus

The aim of this study was to assess the in vitro effects of Syzygium cumini (L.) (Sc) incubation on platelets from patients with diabetes, in order to test its efficacy as a potential adjuvant therapy. This study was performed on 77 patients with diabetes [29 in good (DMgc) and 48 in poor glycemic control (DMpc)] and 85 controls. In patients, platelets were analyzed at recruitment and after in vitro Sc incubation (final concentration of 200 µg/ml for 3 hours at 37 °C), whereas in controls only basal evaluation was performed. Lipoperoxide and nitric oxide (NO) levels, superoxide dismutase (SOD) and Na(+)/K(+) ATPase activities, total antioxidant capacity (TAC), and membrane fluidity tested by anisotropy of fluorescent probes 1-(4-trimethylaminophenyl)-6-phenyl-1,3,5-hexatriene (TMA-DPH) and 1-6-phenyl-1,3,5-hexatriene (DPH) were determined. Collagen-induced platelet aggregation was also evaluated. In vitro Sc activity counteracts oxidative damage, by improving platelet function through augmented membrane fluidity and Na(+)/K(+) ATPase activity; it also enhances antioxidant system functionality by increasing NO levels, SOD activity, and TAC and by decreasing lipoperoxide levels both in whole samples and in DMgc and DMpc. In addition, a slight tendency towards collagen-induced platelet aggregation decrease after Sc was observed. However, all these parameters, even after improvement, did not reach the levels of control subjects. Our results suggest that Sc may have a preventive and protective effect in oxidative damage progression associated with diabetes mellitus and its complications. If our data will be confirmed, Sc supplementation might become a further tool in the management of this disease, especially in view of its easy availability, safety, low cost, and absence of side effects.