Moreover, current studies have shown that lung tissue macrophages express TRIM21 and increased TRIM21 expression in monocytes has been found to promote Th1 and Th17 differentiation in other diseases, which seems to predict that TRIM21 positively regulates the disease process of RA-ILD in the course of RA-ILD, but the specific mechanism has not yet been reported in any study (126, 184). Here, TRIM21 is linked to rheumatoid arthritis.