Bacteria-related Events and the Immunological Response of Onset and Relapse Adult Crohn’s Disease Patients

BACKGROUND AND AIMS: Crohn's disease CD is a chronic, systemic inflammatory disease characterised by periods of remission and flare-ups. It has been associated with a disturbed gastrointestinal barrier function, an increase in the transport of luminal contents into the tissue, and lower immune tolerance. METHODS: Peripheral blood samples were collected from healthy controls and 33 adult active flare-up CD patients. We classified patients as onset or relapse flare-up subjects, according to the days of disease evolution. Plasma levels of lipopolysaccharide-binding protein LBP, fatty acid-binding proteins FABP, and antibodies against bacterial lysates, interferons IFN and interleukin-6 IL6 were measured by enzyme-linked immunosorbent assay ELISA in each group of patients. RESULTS: Onset CD patients had higher plasma levels of LBP 57.32 ± 38.86 vs 30.22 ± 9.80 µg/ml and IFNα 1.25 ± 0.23 vs 0.95 ± 0.36 log10pg/ml and lower levels of immunoglobulins G and A IgG and IgA antibodies against bacterial lysates than relapse CD patients. We also observed a subgroup of onset patients with the highest levels of LBP. In this subgroup, LBP correlated negatively with C-reactive protein CRP. Onset and relapse CD patients had similar levels of FABP6 and FABP2, though LBP and FABP6 correlated positively only in relapse patients. In relapse patients, anti-E coli IgG antibodies correlated positively with systemic IL6 and IFNα levels. CONCLUSIONS: Our findings suggest that onset and relapse flare-ups in adult CD patients are related to different systemic immune-related bacterial events. Characterising these differences may provide insights into the aetiology of Crohn's disease, and would help in the selection of appropriate therapies.