Intestinal barrier biomarkers in clinical evaluation of patients with inflammatory bowel disease

Background: Inflammatory bowel disease (IBD) is associated with chronic intestinal barrier dysfunction, though its non-invasive assessment remains challenging. This study aimed to determine how four putative circulating markers vary across differing states of intestinal inflammation and with therapy in patients with IBD.

Methods: Plasma samples from one prospective cross-sectional and four longitudinal studies, including healthy controls, were analysed for markers of lipopolysaccharide translocation, lipopolysaccharide-binding protein (LBP) and soluble-CD14 (sCD14), and markers of epithelial injury, syndecan-1 and intestinal-type fatty acid-binding protein (IFABP). Inflammatory activity was determined using objective measures.

Results: Compared with healthy subjects, concentrations of LBP and sCD14 were higher in patients with active (P < 0.001) and severe ulcerative colitis (UC) (P < 0.0001) and active Crohn's disease (CD) (P < 0.001). In UC in remission, LBP was less than in active disease (P = 0.011) LBP levels decreased longitudinally before and after induction of medical therapy in patients with IBD (P = 0.030) and as severe UC was brought into remission at weeks 2 and 12 (P ≤ 0.022). Response to treatment was associated with higher baseline levels of LBP (P = 0.019) and soluble-CD14 (P = 0.014). Concentrations of syndecan-1 and IFABP were or tended to be lower in UC and CD in active disease and did not change with successful therapy.

Conclusion: While markers of epithelial injury were subnormal with active disease and did not change with therapy, markers of lipopolysaccharide translocation directly reflected intestinal inflammation, reduced with successful therapy and predicted treatment response.