TLR1 and rheumatoid arthritis: Also, only the expression of the TLR2 gene was significantly higher in the RA than in the EA patients group but not the expression of TLR1 or TLR4. Although TNF-α stimulated TLR1 expression, differences between the stimulated and nonstimulated samples reached a significance level only when TLR1 gene expression was compared in the related samples of the whole cohort.