To determine whether RA is accompanied by a loss of gut membrane integrity, we compared the serum levels of three biomarkers of gut permeability in RA patients and healthy controls: LPS, a gram-negative bacterial membrane component; LBP, an acute phase protein produced by the intestinal epithelium and the liver in response to translocation of LPS;28,29 and I-FABP, a specific biomarker of gut epithelial integrity.30 Here, FABP2 is linked to rheumatoid arthritis.