Activation Of Sirt1by Resveratrol Attenuates Bleomycin Induced Scleroderma

Scleroderma is an autoimmune disease, characterized by progressive fibrosis of skin and internal organs. Inflammation is another main mechanism of scleroderma, especially at the early stage, and it is also an important initiating agent of flbrosis. Matrix metalloproteinases (MMPs) and cytokines such as tumor necrosis factor alpha (TNF-a), interleukin (IL)-6were reported to be partly released from fibroblasts and inflammatory cells in sclerodema. These inflammatory factors have been suggested to play a central role in the initiation and the development of fibrosis in scleroderma. Suppression of inflammation is a promising resolution to treat the disease.Sirtl, aNAD+dependent deacetylase, is known to regulate caloric restriction mediated longevity. It has been shown to have an important role in regulation of inflammation. Resveratrol, a potent Sirtl activator, has been shown to have anti-inflammation property. However, the mechanism is not fully understood. In this study, we investigated the anti-inflammation role of Sirtl and resveratrol in TNF-a treated fibroblasts and bleomycin induced mouse experimental scleroderma.Upregulation of MMP9, IL-1β, IL-6and inducible nitric oxide synthase (iNOS) were observed in the3T3/NIH fibroblasts after being treated by TNF-a. Resveratrol suppressed the upregulation of inflammatory factors induced by TNF-a in a dose-dependent manner. And the suppression was significantly decreased if resveratrol was applied after the inflammation being induced. In the scleroderma mouse model, bleomycin induced significant inflammation and fibrosis in skin where infiltrated inflammatory cells, increased fiber bundles, upregulated collagen deposition were examined by HE staining and Masson’s trichrome staining. The pathological changes were attenuated by resveratrol treatment in a time and dose dependent manner. The bleomycin induced upregulation of inflammatory factors were also inhibited by resveratrol treatment in the mice skin. Importantly, upregulated expression of Sirtl protein was examined in the serum of scleroderma patients, compare to normal control.We further explored the potential anti-inflammatory mechanisms of resveratrol in vitro. The inflammatory inhibition of resveratrol was largely dependent on Sirtl expression. Knockdown of Sirtl caused cell sensitizing to TNF-a stimulation and diminished the inflammatory inhibition of resveratrol. Resveratrol reduced NF-κB subunit RelA/p65acetylation, which was also notably Sirtl dependent. Furthermore, in this study, we also found that resveratrol inhibited the phosphorylation of both mTOR and S6ribosomal protein while ameliorating the inflammation in TNF-a treated fibroblasts. And rapamycin, the specific inhibitor of mTOR, attenuated the TNF-a induced inflammation.The results suggest that Sirtl is an efficient target for suppression of inflammation and fibrosis in scleroderma. As a Sirtl activator, resveratrol may be used for therapy in scleroderma. Reduction of acetylated NF-κB and suppression of mTOR/S6RP phosphorylation may be involved in the mechanisms. This study provides a novel insight or treatment of scleroderma and other inflammation-related diseases.