ABSTRACT: While Lymphotoxin ? (TNF-?), a product of lymphocytes, is known to play a pivotal role in inflammatory joint environment, resveratrol has been shown to possess anti-inflammatory and chondroprotective effects via activation of the histondeacetylase Sirt1. Whether TNF-? induction of inflammatory pathways in primary human chondrocytes (PCH) can be modulated by resveratrol, was investigated. Monolayer and alginate cultures of PCH were treated with TNF-?, anti-TNF-?, nicotinamide (NAM), antisense oligonucleotides against Sirt1 (Sirt1-ASO) and/or resveratrol and co-cultured with T-lymphocytes. We found that resveratrol suppressed, similar to anti-TNF-?, TNF-?-induced increased adhesiveness in an inflammatory microenvironment of T-lymphocytes and PCH. In contrast, knockdown of Sirt1 by mRNA abolished the inhibitory effects of resveratrol on the TNF-?-induced adhesiveness, suggesting the essential role of this enzyme for resveratrol-mediated anti-inflammatory signaling. Similar results were obtained in PCH stimulated with TNF-?. Sirt1-ASO, NAM or TNF-?, similar to T-lymphocytes induced inflammatory microenvironment by down-regulation of cartilage-specific proteins, Sox9, Ki67 and enhanced NF-?B-regulated gene products involved in inflammatory and degradative processes in cartilage (MMP-9/-13, COX-2, caspase-3), NF-?B activation and its translocation to the nucleus. Moreover, resveratrol reversed the TNF-?-, NAM-, T-lymphocytes-induced up-regulation of various NF-?B-regulated gene products. Down-regulation of Sirt1 by mRNA interference abrogated the effect of resveratrol on TNF-?-induced effects. Ultrastructural and cell viability assay investigations revealed that resveratrol revoked TNF-?-induced dose-dependent degradative/apoptotic morphological changes, cell viability and proliferation in PCH. Taken together, suppression of TNF-?-induced inflammatory microenvironment in PCH by resveratrol/Sirt1 might be a novel therapeutic approach for targeting inflammation during rheumatoid arthritis.
