Altered expression of aEss7 integrin on intra-epithelial and lamina propria lymphocytes in patients with Crohn's disease

Objective: To compare the expression of adhesion molecules on intestinal intra-epithelial (IEL) and lamina propria T cells (LPL) from ileum and colon, in patients with Crohn's disease (CD) versus healthy controls, with special reference for the aEss7 integrin. Methods: IEL and LPL were obtained from 18 CD patients and 20 controls by enzymatic extraction, and subsequently characterized by flow cytometry for CD3, CD4, CD8, CD25, LFA-1a (CD11a), CD44, a4 and aEss7 integrin. Resufts: In LPL of controls, a decreased CD4/CD8 ratio was noted in ileum compared to colon. This regional difference was accompanied by a higher expression of aEss7 integrin in ileum versus colon. In LPL from left hemicolon of CD patients, a decreased CD4/CD8 ratio was noted versus controls. aEss7 expression on T cells of LPL did not discriminate CD from controls. However, an overexpression of this ss7 integrin member was observed on CD25+ T cell subsets from lamina propria of left hemicolon, in CD versus controls. Moreover, in IEL, profound alterations in aEss7 integirin were observed in CD, compared to controls. A decreased expression of aEss7 was noted in IEL of ileum of CD patients. This was also apparent in non-inflamed mucosa. Conclusion : The observed changes of aEss7 integrin expression in CD patients versus controls are of pathogenic relevance, especially the decreased expression of aEss7 in IEL of non-inflamed CD mucosa. This may be one of the earliest events in the pathogenesis of this disease.