LAUSR

Histone deacetylase (HDAC) has been implicated in rheumatoid arthritis (RA) progression. We investigated the roles of histone deacetylase 3 (HDAC3) involved in RA-associated interstitial lung disease (ILD) fibrosis. Firstly, we measured the expression of HDAC3 and interleukin 17 receptor A (IL17RA) in lung tissue samples from normal controls, idiopathic pulmonary fibrosis (IPF) patients, and RA-ILD patients. Next, chromatin immunoprecipitation (ChIP) and dual luciferase reporter assay were employed to detect the interaction between HDAC3 and microRNA-19a-3p (miR-19a-3p) and between miR-19a-3p and IL17RA. Further, immunohistochemistry was used to localize HDAC3 and IL17RA expression in lung tissues. Additionally, functional assays were conducted followed by expression determination of HDAC3, miR-19a-3p, and IL17RA with reverse transcription quantitative PCR (RT-qPCR) and Western blot analysis. The effect of HDAC3 on RA-ILD in the constructed RA-ILD mouse model was also studied based on arthritis assessment. We found overexpressed HDAC3 and IL17RA as well as silenced miR-19a-3p in RA-ILD mouse model and RA-ILD patients. In the mouse model, HDAC3 downregulated miR-19a-3p in lung fibroblasts to promote the progression of RA-ILD fibrosis. In lung fibroblasts of RA-ILD mice, IL17RA was a target gene of miR-19a-3p. miR-19a-3p negatively regulated IL17RA, thereby increasing the expression of fibrosis markers, COL1A1, COL3A1, and FN, in lung fibroblasts of mice. Taken together, HDAC3 upregulated IL17RA expression by targeting miR-19a-3p to facilitate the RA-ILD fibrosis development, which sheds light on a new HDAC3/miR-19a-3p/IL17RA axis functioning in RA-ILD fibrosis.