HDAC inhibitors inhibit IL-6 release by bone marrow-derived macrophages exposed to microbial products such as lipopolysaccharides (LPS) and heat-killed Escherichia coli and Staphylococcus aureus [35,36] and decrease both IL-6 and TNF production in PBMCs isolated from RA patients [19,37]. This evidence concerns the gene HDAC9 and rheumatoid arthritis.