Deacetylation of IRF8 inhibits iNOS expression and inflammation via SIRT1 in macrophages

Aims: Dysregulated interferon regulatory factor 8 (IRF8) mediated inducible nitric oxide synthase (iNOS) tran-scription is crucial to the pathogenesis of several inflammatory disorders. However, the molecular mechanism that control the transcription activity of IRF8 in the regulation of iNOS is not fully elucidated. This study is undertaken to determine whether SIRT1 impacts IRF8 acetylation level in the macrophages.Main methods: The silver stain, mass spectrum, bone marrow-derived monocytes differentiation, lentiviral transduction, immunoprecipitation and chromatin immunoprecipitation assay were used to investigate the relationship between IRF8 and SIRT1.Key findings: We demonstrate that deacetylation of IRF8 is induced by lipopolysaccharide (LPS) and suppresses iNOS expression. Macrophages expressing acetylation-defective iNOS are highly septic upon transfer to macro-phages cleaned up mice. Mechanistically, deacetylation IRF8 facilitates the binding of silent information regu-lator 1 (SIRT1) to the iNOS promoter and restricts iNOS transcription. The expression of iNOS was enhanced in the macrophages from SIRT1 conditional knockout mice and the progression of sepsis is more serious.Significance: The discovery of the IRF8-SIRT1 interaction that governs iNOS expression may exploit new thera-peutic strategies for inflammatory disorders.

Automated summary

The IRF8-SIRT1 regulation plays a crucial role in the expression of iNOS, which could provide new therapeutic strategies for inflammatory disorders.