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      Activation of Sirt1 by Resveratrol Inhibits TNF-α Induced Inflammation in Fibroblasts

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          Abstract

          Inflammation is one of main mechanisms of autoimmune disorders and a common feature of most diseases. Appropriate suppression of inflammation is a key resolution to treat the diseases. Sirtuin1 (Sirt1) has been shown to play a role in regulation of inflammation. Resveratrol, a potent Sirt1 activator, has anti-inflammation property. However, the detailed mechanism is not fully understood. In this study, we investigated the anti-inflammation role of Sirt1 in NIH/3T3 fibroblast cell line. Upregulation of matrix metalloproteinases 9 (MMP-9), interleukin-1beta (IL-1β), IL-6 and inducible nitric oxide synthase (iNOS) were induced by tumor necrosis factor alpha (TNF-α) in 3T3 cells and resveratrol suppressed overexpression of these pro-inflammatory molecules in a dose-dependent manner. Knockdown of Sirt1 by RNA interference caused 3T3 cells susceptible to TNF-α stimulation and diminished anti-inflammatory effect of resveratrol. We also explored potential anti-inflammatory mechanisms of resveratrol. Resveratrol reduced NF-κB subunit RelA/p65 acetylation, which is notably Sirt1 dependent. Resveratrol also attenuated phosphorylation of mammalian target of rapamycin (mTOR) and S6 ribosomal protein (S6RP) while ameliorating inflammation. Our data demonstrate that resveratrol inhibits TNF-α-induced inflammation via Sirt1. It suggests that Sirt1 is an efficient target for regulation of inflammation. This study provides insight on treatment of inflammation-related diseases.

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          Most cited references 70

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          Radiographic, clinical, and functional outcomes of treatment with adalimumab (a human anti-tumor necrosis factor monoclonal antibody) in patients with active rheumatoid arthritis receiving concomitant methotrexate therapy: a randomized, placebo-controlled, 52-week trial.

          Tumor necrosis factor (TNF) is an important proinflammatory cytokine that mediates inflammatory synovitis and articular matrix degradation in rheumatoid arthritis (RA). We investigated the ability of adalimumab, a human anti-TNF monoclonal antibody, to inhibit the progression of structural joint damage, reduce the signs and symptoms, and improve physical function in patients with active RA receiving concomitant treatment with methotrexate (MTX). In this multicenter, 52-week, double-blind, placebo-controlled study, 619 patients with active RA who had an inadequate response to MTX were randomized to receive adalimumab 40 mg subcutaneously every other week (n = 207), adalimumab 20 mg subcutaneously every week (n = 212), or placebo (n = 200) plus concomitant MTX. The primary efficacy end points were radiographic progression at week 52 (total Sharp score by a modified method [TSS]), clinical response at week 24 (improvements of at least 20% in the American College of Rheumatology core criteria [ACR20]), and physical function at week 52 (disability index of the Health Assessment Questionnaire [HAQ]). At week 52, there was statistically significantly less radiographic progression, as measured by the change in TSS, in the patients receiving adalimumab either 40 mg every other week (mean +/- SD change 0.1 +/- 4.8) or 20 mg weekly (0.8 +/- 4.9) as compared with that in the placebo group (2.7 +/- 6.8) (P < or = 0.001 for each comparison). In addition, there were statistically significant changes in the components of the TSS. At week 24, ACR20 responses were achieved by 63% and 61% of patients in the adalimumab 40 mg every other week and 20 mg weekly groups, respectively, versus 30% of patients in the placebo group (P < or = 0.001 for each comparison). At week 52, ACR20 responses were achieved by 59% and 55% of patients taking adalimumab 40 mg every other week and 20 mg weekly, respectively, versus 24% of patients taking placebo (P < or = 0.001 for each comparison). At week 52, physical function as measured by the HAQ demonstrated statistically significant improvement with adalimumab 40 mg every other week and 20 mg weekly compared with placebo (mean change in HAQ score -0.59 and -0.61, respectively, versus -0.25; P < or = 0.001 for each comparison). A total of 467 patients (75.4%) completed 52 weeks of treatment. Adalimumab was generally well tolerated. Discontinuations occurred in 22.0% of adalimumab-treated patients and in 30.0% of placebo-treated patients. The rate of adverse events (both serious and nonserious) was comparable in the adalimumab and placebo groups, although the proportion of patients reporting serious infections was higher in patients receiving adalimumab (3.8%) than in those receiving placebo (0.5%) (P < or = 0.02), and was highest in the patients receiving 40 mg every other week. In this 52-week trial, adalimumab was more effective than placebo at inhibiting the progression of structural joint damage, reducing the signs and symptoms, and improving physical function in patients with active RA who had demonstrated an incomplete response to MTX.
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            Mechanism of human SIRT1 activation by resveratrol.

            The NAD+-dependent protein deacetylase family, Sir2 (or sirtuins), is important for many cellular processes including gene silencing, regulation of p53, fatty acid metabolism, cell cycle regulation, and life span extension. Resveratrol, a polyphenol found in wines and thought to harbor major health benefits, was reported to be an activator of Sir2 enzymes in vivo and in vitro. In addition, resveratrol was shown to increase life span in three model organisms through a Sir2-dependent pathway. Here, we investigated the molecular basis for Sir2 activation by resveratrol. Among the three enzymes tested (yeast Sir2, human SIRT1, and human SIRT2), only SIRT1 exhibited significant enzyme activation ( approximately 8-fold) using the commercially available Fluor de Lys kit (BioMol). To examine the requirements for resveratrol activation of SIRT1, we synthesized three p53 acetylpeptide substrates either lacking a fluorophore or containing a 7-amino-4-methylcoumarin (p53-AMC) or rhodamine 110 (p53-R110). Although SIRT1 activation was independent of the acetylpeptide sequence, resveratrol activation was completely dependent on the presence of a covalently attached fluorophore. Substrate competition studies indicated that the fluorophore decreased the binding affinity of the peptide, and, in the presence of resveratrol, fluorophore-containing substrates bound more tightly to SIRT1. Using available crystal structures, a model of SIRT1 bound to p53-AMC peptide was constructed. Without resveratrol, the coumarin of p53-AMC peptide is solvent-exposed and makes no significant contacts with SIRT1. We propose that binding of resveratrol to SIRT1 promotes a conformational change that better accommodates the attached coumarin group.
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              SRT1720, SRT2183, SRT1460, and resveratrol are not direct activators of SIRT1.

              Sirtuins catalyze NAD(+)-dependent protein deacetylation and are critical regulators of transcription, apoptosis, metabolism, and aging. There are seven human sirtuins (SIRT1-7), and SIRT1 has been implicated as a key mediator of the pathways downstream of calorie restriction that have been shown to delay the onset and reduce the incidence of age-related diseases such as type 2 diabetes. Increasing SIRT1 activity, either by transgenic overexpression of the Sirt1 gene in mice or by pharmacological activation by small molecule activators resveratrol and SRT1720, has shown beneficial effects in rodent models of type 2 diabetes, indicating that SIRT1 may represent an attractive therapeutic target. Herein, we have assessed purported SIRT1 activators by employing biochemical assays utilizing native substrates, including a p53-derived peptide substrate lacking a fluorophore as well as the purified native full-length protein substrates p53 and acetyl-CoA synthetase1. SRT1720, its structurally related compounds SRT2183 and SRT1460, and resveratrol do not lead to apparent activation of SIRT1 with native peptide or full-length protein substrates, whereas they do activate SIRT1 with peptide substrate containing a covalently attached fluorophore. Employing NMR, surface plasmon resonance, and isothermal calorimetry techniques, we provide evidence that these compounds directly interact with fluorophore-containing peptide substrates. Furthermore, we demonstrate that SRT1720 neither lowers plasma glucose nor improves mitochondrial capacity in mice fed a high fat diet. SRT1720, SRT2183, SRT1460, and resveratrol exhibit multiple off-target activities against receptors, enzymes, transporters, and ion channels. Taken together, we conclude that SRT1720, SRT2183, SRT1460, and resveratrol are not direct activators of SIRT1.
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                Author and article information

                Contributors
                Role: Editor
                Journal
                PLoS One
                plos
                plosone
                PLoS ONE
                Public Library of Science (San Francisco, USA )
                1932-6203
                2011
                1 November 2011
                : 6
                : 11
                Affiliations
                [1 ]Division of Rheumatology, Shanghai Medical College, Fudan University, Huashan Hospital, Shanghai, China
                [2 ]Institute of Rheumatology, Immunology and Allergy, Shanghai Medical College, Fudan University, Huashan Hospital, Shanghai, China
                [3 ]Department of Human Anatomy, Histology and Embryology, Shanghai Medical College, Fudan University, Shanghai, China
                [4 ]Division of Rheumatology, Dongnan University, Zhongda Hospital, Nanjing, China
                [5 ]Department of Neurology and Radiology, Harvard Medical School, Massachusetts General Hospital, Charlestown, Massachusetts, United States of America
                Charité-University Medicine Berlin, Germany
                Author notes

                Conceived and designed the experiments: HZ JQ. Performed the experiments: XZ QL. Analyzed the data: XZ MW. Contributed reagents/materials/analysis tools: XZ ML XY XX. Wrote the paper: XZ HZ JQ.

                Article
                PONE-D-11-19409
                10.1371/journal.pone.0027081
                3206084
                22069489
                850b8b87-f214-4493-aafa-bde45152b993
                Zhu et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
                Page count
                Pages: 7
                Categories
                Research Article
                Biology
                Anatomy and Physiology
                Immune Physiology
                Cytokines
                Biochemistry
                Chemical Biology
                Enzymes
                Small Molecules
                Immunology
                Immune System
                Cytokines
                Immunity
                Inflammation
                Chemistry
                Phytochemistry
                Phytopharmacology
                Medicine
                Clinical Immunology
                Immunity
                Inflammation
                Drugs and Devices
                Pharmacodynamics

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