P418 Lipopolysaccharide-Binding Protein (LBP) in Crohn's Disease (CD) Patients: A Promising Non-Invasive Biomarker Monitoring Disease Activity

Background Current biomarkers of inflammatory bowel disease (IBD) monitoring (serum C-reactive protein (CRP) and faecal calprotectin (FC)) have limitations in terms of specificity (SP) and sensitivity (SE), especially for Crohn’s disease (CD) patients. Lipopolysaccharide-binding protein (LBP) is a soluble acute-phase protein and is thought to partly reflect intestinal permeability by binding to bacterial lipopolysaccharides. The search for new biomarkers to monitor disease activity would improve the management of IBD patients. Methods This is a retrospective study including 69 IBD patients (43 CD and 26 ulcerative colitis (UC)) and 21 healthy controls (HC). Serum LBP levels were measured by enzyme-linked immunosorbent assay. Clinical, biological and endoscopic parameters were analysed for IBD patients. Statistical tests, including nonparametric tests and receiver operating characteristic (ROC) curve analysis, were used to evaluate the diagnostic accuracy of LBP. Results Demographics and baseline data of the overall cohort is presented in Table 1. IBD patients displayed a significantly higher LBP median (29.6 µg/mL [19.8-38.8] in CD and 22.8 [13.7-38.8] in UC) than HC (5.5 [4.4-6.5], P < 0.001) with no overlapping distributions, a finding supported by an AUC of 0.997 and 0.989, respectively for CD and UC patients (Figures 1A). In CD patients, LBP levels gradually increased with endoscopic severity, demonstrating a 1.7-fold rise in active patients compared to remitter patients (P=0.02) (Figure 1B). LBP levels were higher in Montreal B1 compared to B2 and B3 CD patients (P < 0.001) (Figure 1C). Overall, a robust correlation was observed between LBP and CRP (ρ=0.75, P < 0.001). The correlation increased upon the exclusion of cases with normal CRP levels but active endoscopic disease (ρ=0.79, P < 0.001). In those endoscopically active patients with normal CRP, LBP level was higher than in remitter patients (34.3 [29.4-37.6] vs 19.1 [10-24.7], P=0.01) with a discriminative cut-off of 25 µg/mL (SE of 100%, SP of 89%). Likewise, LBP level exhibited a positive correlation with FC (ρ=0.42, P < 0.01) which was further strengthened after excluding cases where FC measurements did not align with endoscopic activity (ρ=0.53, P < 0.01). The median LBP for those patients was 25.6 [18.5-31.5], reflecting again the interest of LBP measurement to evaluate CD activity when FC lacks sensibility. Conclusion Our study suggests that LBP might be a promising non-invasive biomarker for monitoring disease activity, especially in CD patients. Furthermore, in clinical situations where current biomarkers (CRP and FC) lack sensitivity for assessing disease activity, LBP could be discriminative and help filling the gap for reliable therapeutic decisions.