SIRT2 Deficiency Modulates Macrophage Polarization and Susceptibility to Experimental Colitis

Background: SIRT2 belongs to a highly conserved family of NAD(+)-dependent deacylases, consisting of seven members (SIRT1-SIRT7), which vary in subcellular localizations and have substrates ranging from histones to transcription factors and enzymes. Recently SIRT2 was revealed to play an important role in inflammation, directly binding, deacetylating, and inhibiting the p65 subunit of NF-kB. Methods: A Sirt2 deficient mouse line (Sirt2(-/-)) was generated by deleting exons 5-7, encoding part of the SIRT2 deacetylase domain, by homologous recombination. Age-and sex-matched Sirt2(-/-) and Sirt2(+/+) littermate mice were subjected to dextran sulfate sodium (DSS)-induced colitis and analyzed for colitis susceptibility. Results: Sirt2(-/-) mice displayed more severe clinical and histological manifestations after DSS colitis compared to wild type littermates. Notably, under basal condition, Sirt2 deficiency does not affect the basal phenotype and intestinal morphology Sirt2 deficiency, however, affects macrophage polarization, creating a pro-inflammatory milieu in the immune cells compartment. Conclusion: These data confirm a protective role for SIRT2 against the development of inflammatory processes, pointing out a potential role for this sirtuin as a suppressor of colitis. In fact, SIRT2 deletion promotes inflammatory responses by increasing NF-kappa B acetylation and by reducing the M2-associated anti-inflammatory pathway. Finally, we speculate that the activation of SIRT2 may be a potential approach for the treatment of inflammatory bowel disease.