TLR5 and rheumatoid arthritis: TLR5 expression is reported to be upregulated in the inner layer fibroblasts and macrophages of patients with RA (Kim et al. 2014, 2013; Chamberlain et al. 2012), TNF and IL-17 upregulate the TLR5 expression levels in the peripheral blood mononuclear cells and differentiated macrophages of patients with RA in vitro.