Recruitment of activated neutrophils correlates with disease severity in adult Crohn’s disease

• Published in: Clinical and experimental immunology Vol. 195; no. 2; pp. 251 - 264
• Main Authors: Therrien, A., Chapuy, L., Bsat, M., Rubio, M., Bernard, G., Arslanian, E., Orlicka, K., Weber, A., Panzini, B.‐P., Dorais, J., Bernard, E.‐J., Soucy, G., Bouin, M., Sarfati, M.
• Format: Journal Article
• Language: English
• Published: England Oxford University Press 01-02-2019; John Wiley and Sons Inc
• Subjects: Adult; Aged; Antigens, CD - analysis; Biomarkers - blood; Blood; CD64; CD66b; Cell activation; Cell Adhesion Molecules - analysis; Colon; Colon - immunology; Colon - pathology; Colonoscopy; Crohn Disease - immunology; Crohn Disease - pathology; Crohn’s disease; Endoscopy; Female; Flow cytometry; GPI-Linked Proteins - analysis; Humans; Intestinal Mucosa - pathology; Leukocytes (neutrophilic); Male; Medical treatment; Middle Aged; Mucosa; neutrophil; Neutrophil Activation - immunology; Neutrophils; Neutrophils - immunology; Original; Patients; Prospective Studies; Receptors, IgG - analysis; SES‐CD; Severity of Illness Index; CD64; SES-CD; neutrophil; CD66b; Crohn’s disease
• ISSN: 0009-9104; 1365-2249
• DOI: 10.1111/cei.13226

Summary
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 the Montreal classification. Harvey–Bradshaw Index (HBI) and Simple Endoscopic Score for Crohn’s Disease (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 reflected disease activity more clearly. 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.
In this prospective single‐cell analysis study, neutrophils up‐regulated CD66b expression in inflamed CD mucosa while CD64 expression was augmented on circulating neutrophils in CD patients with endoscopic active disease relative to control groups. Neutrophil CD66b expression in mucosa and, conversely, neutrophil CD64 expression in blood correlated with SES‐CD in CD patients. We thus propose that recruitment of activated neutrophils in inflamed mucosa is associated with disease severity in Crohn’s disease.