Recruitment of Activated Neutrophils Correlates with Disease Severity in Adult Crohn's Disease.

Neutrophils are detected in inflamed colon in Crohn's disease (CD). However, whether the frequency and/or activation of circulating or gut tissue neutrophils correlate with endoscopic severity remains to be investigated. A cohort of 73 CD patients was prospectively enrolled according to endoscopic severity and treatment history. Individuals with active disease were stratified using Montreal classification. Harvey Bradshaw Index (HBI) and Simple Endoscopic score (SES-CD) were performed at the time of ileocolonoscopy. Frequency of neutrophils and their expression of CD66b and CD64 were assessed in paired blood and colonic biopsies using flow cytometry. The percentage of neutrophils increased in inflamed colon and correlated with SES-CD in the entire cohort of patients examined as well as in the subgroup with inflammatory (B1) active disease. SES-CD further correlated with neutrophil CD66b expression in mucosa but not blood and conversely, with neutrophil CD64 expression in blood but not mucosa. However, the evaluation of neutrophil activation in mucosa when compared to blood better reflected disease activity. Finally, a neutrophil activation power index (CD66b in mucosa X CD64 in blood) that correlated with SES-CD discriminated between patients with mild and severe disease. In conclusion, the frequency and activation of colonic neutrophils correlated with SES-CD, highlighting that mucosal neutrophils are associated with disease severity in CD. This article is protected by copyright. All rights reserved.