Further gut permeability markers, in particular LPS, LBP and I-FABP, have been revealed to be increased in the serum of chronic RA patients, and partially in pre-RA (patients with seropositivity and joint pain) and/or early RA patients (with early, undifferentiated clinical arthritis) (Matei et al., 2021). Here, FABP2 is linked to rheumatoid arthritis.