To address whether neutralization of TNF-α affects the levels of serum markers of gut permeability, we tested the concentration of LPS, LBP, and I-FABP in the serum of a longitudinal cohort of TNF-α inhibitor (etanercept)-treated RA patients before and 6 months after the start of treatment (6 months is a sufficient time to determine response to therapy; Figures S1E–S1G). Here, FABP2 is linked to rheumatoid arthritis.