HDAC9 and colitis: According to existing studies, butyrate metabolic defects contributed to the development of colon inflammatory diseases.29,30 Besides, butyrate exerted anti-oxidant, anti-inflammatory, and anti-carcinogenic effects in vitro and in vivo based on several mechanisms.31-33 The inhibition of nuclear factor kappa B (NF-κB) and histone deacetylase (HDAC) has been the most studied mechanism of butyrate exerting anti-inflammatory effect.34,35 However, recent studies revealed that immune modulation might be another significance mechanism of butyrate in mitigating intestinal and colonic inflammation.