Increased occludin after anti-TNF was associated with baseline DAS28-CRP (β=0.314) and IL-1β (β=0.416); claudin-1 with male sex (β=-0.342); and zonulin with lower IL-1β (β=-0.313) and higher resistin (β=0.294).<h4>Conclusions</h4>Biomarkers of intestinal integrity, especially serum occludin, are altered in patients with RA and were associated with response to anti-TNF. Here, CLDN1 is linked to rheumatoid arthritis.