The up-regulation of TLR-2 and/or TLR-4 has been shown in macrophages and gingival fibroblasts of inflamed periodontal tissue [15], which suggests that innate immune responses involving the TLRs as signalling receptors contribute to the inflammatory or immune response of periodontal tissue. Sirtuin 1 (SIRT1) is the human orthologue of the yeast Sir2 protein, the prototypic class III histone deacetylase. SIRT1 has been shown to play a central role in a variety of cellular processes such as stress resistance, metabolism, differentiation and ageing [16]. We have demonstrated previously that SIRT1 exerts anti-inflammatory

effects through R788 manufacturer the modulation of osteoclastogenic cytokine levels in human PDL cells [17]. Furthermore, SIRT1 has been implicated in the regulation of immune function, as it is expressed at high levels in the thymus, GSK-3 beta phosphorylation including in CD4+ and CD8+ thymocytes, and knocking out SIRT1 increases sensitivity to ionizing radiation-induced apoptosis [18]. Moreover, treatment of T cells with resveratrol, a SIRT1 activator, suppresses proliferation and cytokine production

in vitro[19]. Resveratrol also suppresses immune functions by inducing lymphocyte apoptosis [20]. These results suggest that SIRT1 may be involved in the production of immune defence genes in MS-stimulated PDL cells. We have reported previously that MS induces inflammatory cytokines including IL-1β, TNF-α and IL-6, as well as defence genes such as haem oxygenase-1 (HO-1), in human dental pulp cells [21]. Recently, we demonstrated that MS modulates odontoblastic/osteoblastic differentiation via modulation of the HO-1 pathway in dental pulp and PDL cells [22,23]. Although the activation of TLRs and production of anti-microbial peptides, cytokines and chemokines, as well as their receptors, are implicated in innate and adaptive immunity [24], there is little information on the involvement of SIRT1 in MS-induced immune genes of PDL cells. The aim of the present study was to investigate

the role of SIRT1 in the effects of MS on the expression Ureohydrolase of immune response genes in human PDL cells and to identify the underlying mechanisms involved. Dulbecco’s modified Eagle’s medium (DMEM), fetal bovine serum (FBS) and other tissue culture reagents were purchased from Gibco BRL (Grand Island, NY, USA). Resveratrol and sirtinol were purchased from Sigma-Aldrich (St Louis, MO, USA). Affinity purified polyclonal antibodies against mouse TLR-2, TLR-4, I-κBα, nuclear factor (NF)-κB p65 and β-actin monoclonal antibodies were obtained from Santa Cruz Biotechnology (Santa Cruz, CA, USA). Antibodies against phospho-extracellular-regulated kinase (p-ERK), ERK, phospho-p38 (p-p38), p38, phospho- c-Jun N-terminal kinase (p-JNK) and JNK were purchased from Cell Signaling Inc. (Beverly, MA, USA).