[600] Foxp3 Expression in Microscopic Colitides: Clinicopathological Study of 69 Patients.

Shuting Bai, Gene P Siegal, Nirag Jhala. University of Alabama at Birmingham

Background: Microscopic colitides, including lymphocytic (LC) and collagenous colitis (CC) are well-described conditions. They show characteristic morphologic changes that distinguish the two and many similarities including expansion of lamina propria predominantly by T lymphocytes. Altered immune response has, therefore, implicated in the pathogenesis of these two entities. It is recently reported that CD8+ T-lymphocytes (CTLs) secret IL2 which stimulates regulatory T cells (Tregs) proliferation and Tregs inhibit CD8+ CTLs induced cytotoxic tissue damage. Foxp3 in Tregs regulates T cell related immune responses. The relationship and distribution of Tregs and CD8+ CTLs in microscopic colitides to date has remained unexplored. The specific aim of this study is to characterize differences in the distribution pattern of Foxp3 in biopsies from LC and CC.
Design: 71 colonic biopsies from 69 patients obtained over a 2 year period with clinical diagnosis of microscopic colitides were retrieved. All biopsies were categorized into one of three diagnoses: no significant histopathological abnormality (NSHPA), LC, or as CC. All biopsies were evaluated by immunohistochemistry using a panel of markers including CD8 and Foxp3. All immunopostive cells were counted within the epithelium (numbers/100 epithelial cells) and in lamina propria (numbers/HPF). Statistical significance was derived utilizing the student's t test.
Results: Microscopic colitides is predominantly noted in females (3:1). Our study demonstrates that there is significant difference in the expression of C8+ T cells both in lamina propria as well as in intraepithelial cells amongst three groups [Fig 1A & 1B]. In contrast to LC, recruitment of Foxp3 + Tregs is significantly more frequently noted in lamina propria of biopsies with CC [Fig 1C]. Interestingly, 2 LC patients demonstrated morphologic changes of CC on follow up with associated conversion in the distribution pattern of Foxp3.

Conclusions: This study shows that differences in immunologic recruitment of Foxp3 + Tregs in colonic mucosa correlates with differences in spectrum of morphologic changes of patients presenting with microscopic colitides, particularly, LC and CC.
Category: Gastrointestinal

Wednesday, March 2, 2011 9:30 AM

Poster Session V # 18, Wednesday Morning


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