IADR Abstract Archives
SIRT2 is Secreted by Macrophages after Stimulation with TLR2 Agonists
Objectives: SIRT2 is an NAD-dependent lysine deacetylase concerned with the regulation of key intra-cellular proteins such as α-tubulin and NF-κB; as such, SIRT2 serves as a link between metabolism and key myeloid cell functions such as phagocytosis and pro-inflammatory signalling. We have determined that SIRT2 is elevated in the saliva of patients with periodontitis, and may therefore be a candidate biomarker. However, role of SIRT2 in the pathogenesis of periodontitis has not been systematically investigated. The aim of this study is to investigate the regulation of SIRT2 in macrophages by TLR agonists in an attempt to delineate novel pathways relevant to periodontal pathogenesis.
Methods: Macrophages were derived from THP-1 pro-monocytes by stimulation with phorbol myristate acetate (PMA). qPCR and western blotting were used to analyse SIRT2 mRNA and protein expression respectively in macrophages after stimulation with toll-like receptor (TLR) 2 agonists, Pam2CSK4 and lipoteichoic acid (LTA) and TLR 4 agonist, E. coli lipopolysaccharide (LPS). ELISA analysis of macrophage culture supernatants was used to quantify extracellular SIRT2.
Results: There was no evidence that that SIRT2 is regulated at the mRNA or protein level by either TLR2 or TLR4 signalling. We have, however, measured secretion of SIRT2 from macrophages stimulated with TLR2 agonists (both Pam2CSK4 and LTA) (p=<0.001), but not with the TLR4 agonist LPS, despite all 3 molecules eliciting a powerful pro-inflammatory response in macrophages as measured by TNF-a secretion.
Conclusions: SIRT2 is secreted from THP1 monocyte-derived macrophages in response to activation of TLR2, but not TLR4. This finding may represent a novel pathway relevant to periodontitis and may explain the elevated levels of SIRT2 in the saliva of patients with periodontitis.
Methods: Macrophages were derived from THP-1 pro-monocytes by stimulation with phorbol myristate acetate (PMA). qPCR and western blotting were used to analyse SIRT2 mRNA and protein expression respectively in macrophages after stimulation with toll-like receptor (TLR) 2 agonists, Pam2CSK4 and lipoteichoic acid (LTA) and TLR 4 agonist, E. coli lipopolysaccharide (LPS). ELISA analysis of macrophage culture supernatants was used to quantify extracellular SIRT2.
Results: There was no evidence that that SIRT2 is regulated at the mRNA or protein level by either TLR2 or TLR4 signalling. We have, however, measured secretion of SIRT2 from macrophages stimulated with TLR2 agonists (both Pam2CSK4 and LTA) (p=<0.001), but not with the TLR4 agonist LPS, despite all 3 molecules eliciting a powerful pro-inflammatory response in macrophages as measured by TNF-a secretion.
Conclusions: SIRT2 is secreted from THP1 monocyte-derived macrophages in response to activation of TLR2, but not TLR4. This finding may represent a novel pathway relevant to periodontitis and may explain the elevated levels of SIRT2 in the saliva of patients with periodontitis.
