HDAC1 and Arthritis: Emerging studies show that butyrate plays an important role in the regulation of Tregs in various diseases; for example, it is involved in promoting the polarization of Tregs in arthritis [29], maintaining the Th17/Treg balance by inhibiting histone deacetylase 1 in inflammatory bowel disease [45], and stimulating bone formation via Treg-mediated regulation of WNT10B expression [24].