Previous studies have identified several miRNAs that can upregulate or downregulate RA-FLS [26,27,39,40,41,42], through various effects, such as Treg/Th17 balance, NF-kappaB regulatory circuit, TLR4-dependent cytokine release, affecting lymphocyte function and targeting other inflammatory mediators. Here, TLR4 is linked to rheumatoid arthritis.