HDAC9 and renal fibrosis: An important epigenetic phenomenon in macrophages is the transient inflammatory stimulus-mediated changes that include histone deacetylase (HDAC) activation, which increases the production of pro-inflammatory cytokines in wide disease models, including septic shock, acute respiratory distress syndrome, renal fibrosis, and rheumatoid arthritis, where abrogation of HDAC activity reduced inflammatory cytokines10–12.