Eosinophils Localize to Nerves in Patients with IBD Through Specifc Neurally Expressed Adhesion Molecules and Chemoattractants

Introduction: The role of the eosinophil, which is a common inflammatory cell in inflamed gastrointestinal mucosa in inflammatory bowel disease (IBD) is uncertain. We have previously shown that eosinophils specifically localize to nerves in patients with IBD. The aim of this study was to define the mechanism of this localization.

Methods: Using formalin-fixed paraffin-embedded tissue from patients who had previously undergone colonic resection for intractable IBD, the mechanisms of recruitment to enteric nerves were assessed. Paraffin-embedded tissue was stained for nerves using S100, then dissected using Arcturus laser capture micro-dissection system. The RNA was reverse transcribed and the cDNA amplified using TAQ and specific primers for ICAM-1 and eotaxin-3.

Results: Compared with controls (n=5), ICAM-1 was increased 7-fold in patients with ulcerative colitis (n=4), (P=0.03), and 10-fold in those with Crohn's disease (n=3), (p=0.05). Eotaxin-3 was increased 9-fold in the patients with ulcerative colitis (p=0.04) and 15-fold in those with Crohn's disease (p=0.06) compared with controls.

Conclusions: Specific neurally expressed adhesion molecules and a specific eosinophil chemoattractant appear to mediate localization of eosinophils to nerves. The significance of these specific neuro-immunological interactions will require further investigation. Neurally mediated eosinophil chemoattractants may contribute to the inflammatory cascade in IBD.