Histone deacetylase 3 regulates microglial function through histone deacetylation

Abstract

AbstractBackgroundAs the primary innate immune cells of the brain microglia respond to damage and disease through pro-inflammatory release of cytokines and neuroinflammatory molecules. Histone acetylation is an activating transcriptional mark that regulates gene expression, which is altered in states of disease. Inhibition of histone deacetylase 3 (Hdac3) has been utilized in pre-clinical models of disease to dampen inflammation, but the molecular mechanisms underlying Hdac3’s regulation of inflammatory gene expression in microglia is not well understood.MethodsFunctional changes in immortalized microglia were characterized using a Hdac3 specific inhibitor RGFP966 in response to an immune challenge lipopolysaccharide (LPS). Flow cytometry and cleavage under tags & release using nucleases (CUT & RUN) were used to investigate global and promoter-specific histone acetylation changes, resulting in altered gene expression.ResultsHdac3 inhibition enhanced neuroprotective functions of microglia in response to LPS through reduced nitric oxide release and increased baseline phagocytosis. Inhibition of Hdac3 enhanced histone acetylation globally and at specific gene loci, resulting in the release of gene repression at baseline and enhanced responses to LPS.ConclusionThe findings suggest Hdac3 serves as a negative regulator of microglial gene expression, and that inhibition of Hdac3 facilitates the microglial response to inflammation and its subsequent resolution. Together, this work provides new mechanistic insights into therapeutic applications of Hdac3 inhibition which mediate reduced neuroinflammatory insults through microglial response.