Resveratrol prevents interleukin-1β-induced dysfunction of pancreatic β-cells

Abstract

Objective: Interleukin-1β (IL-1β) plays an important role in the development of type 1 and type 2 diabetes mellitus. Resveratrol, a polyphenol, is known to have a wide range of pharmacological properties in vitro. In this research, we examined the effects of resveratrol on IL-1β-induced β-cell dysfunction.

Methods: We first evaluated the effect of resveratrol on nitric oxide (NO) formation in RINm5F cells stimulated with IL-1β using the Griess method. Next, we performed transient transfection and reporter assays to measure the transcriptional activity of peroxisome proliferator-activated receptor-γ (PPAR-γ). We also used Western blotting analysis to assess the effect of resveratrol on inducible nitric oxide synthase (iNOS) expression and nuclear factor-κB (NF-κB) translocation to the nuclei in cells treated with IL-1β. In addition, we assessed the transcriptional activity of NF-κB using an electrophoretic mobility shift assay (EMSA). Finally, we evaluated the effect of resveratrol on IL-1β-induced inhibition of glucose-stimulated insulin secretion in freshly isolated rat pancreatic islets.

Results: Resveratrol significantly suppressed IL-1β-induced NO production, a finding that correlated well with reduced levels of iNOS mRNA and protein. The molecular mechanism by which resveratrol inhibited iNOS gene expression appeared to involve increased PPAR-γ activity, which resulted in the inhibition of NF-κB activation. Further analysis showed that resveratrol could prevent IL-1β-induced inhibition of glucose-stimulated insulin secretion in rat islets.

Conclusion: In this study, we demonstrated that resveratrol could protect against pancreatic β-cell dysfunction caused by IL-1β.

Keywords: interleukin-1β; nitric oxide; nuclear factor-κB.; peroxisome proliferator-activated receptor-γ; resveratrol.

Fig. 1. Resveratrol inhibited IL-1β-stimulated NO formation.

IL-1β significantly induced NO formation compared with the control group (*P < 0.05), and resveratrol reversed this induction effect in a dose-dependent manner in RINm5F cells (**P < 0.01). RSV: resveratrol; NO: nitric oxide.

Fig. 2. Resveratrol inhibited IL-1β-stimulated iNOS mRNA and protein expression.

A: IL-1β significantly induced iNOS mRNA expression (*P < 0.05), and resveratrol inhibited this effect (**P < 0.01). B: IL-1β induced iNOS protein expression in RINm5F cells; C: Resveratrol significantly inhibited IL-1β-induced iNOS protein expression in rat islets. RSV: resveratrol; iNOS: inducible nitric oxide synthase; IL-1β: interleukin-1β.

Fig. 3. Resveratrol attenuated IL-1β-induced change of PPAR-γ activity.

IL-1β significantly decreased the transcriptional activity of PPAR-γ (*P < 0.05) and resveratrol could inhibit this effect (^#P < 0.05). RSV: resveratrol; IL-1β: interleukin-1β.

Fig. 4. Resveratrol reversed NF-κB translocation from the cytoplasm to the nuclei induced by IL-1β.

A: Protein level of cytoplasmic NF-κB (p65) was decreased in RINm5F cells treated with IL-1β (0.5 ng/mL), and resveratrol reversed the effects remarkably. B: Protein level of p65 in the nucleus was increased in RINm5F cells treated with IL-1β (0.5 ng/mL), and the increase was reversed by resveratrol. C: protein levels of NF-κB in different groups. RSV: resveratrol; IL-1β: interleukin-1β; NS: Non-specific.

Fig. 5. Resveratrol improved glucose-stimulated insulin secretion of rat islet under treatment with IL-1β.

IL-1β significantly inhibited insulin secretion stimulated with high glucose (*P < 0.05) and resveratrol could improve the function of islets treated with IL-1β (**P < 0.01). RSV: resveratrol; IL-1β: interleukin-1β.