Upregulated KAT7 in synovial fibroblasts promotes Th17 cell differentiation and infiltration in rheumatoid arthritis.

Rheumatoid arthritis (RA) is a chronic autoimmune disease involving multiple cellular participants, of which synovial fibroblasts (SFs) are tightly connected with the development and progression of RA. Here, we provide evidence confirming that KAT7, an H4-specific histone acetylase, is upregulated in SFs of RA patients, which is at least attributed to the stimulation by RA-associated proinflammatory cytokines, such as TNF-α, IL-1β or IFN-γ. In addition, KAT7 overexpression in cultured human fibroblast-like synoviocytes (HFLSs) induces IL-6 and TGF-β expression through an epigenetic mechanism, and in vitro T helper 17 (Th17) cell polarization cultured in these supernatants shows promoted cell differentiation. Moreover, KAT7 overexpression in HFLSs induces CCL20 expression via p44/42 MAPK pathway, whereby promoting Th17 cell migration. These two activities of KAT7 in RA SFs indicate its potential roles in accelerating RA pathology. Overall, these results demonstrate some connections between KAT7 upregulated in RA SFs and RA progression and present the inhibition of KAT7 activity as a novel therapeutic target for interfering RA disease.