Kolitis induzierende T-Zellen migrieren verstärkt in den Appendix

Abstract

Background: Previous studies showed a distinct role of the cecum and appendix in the development of colitis [3] [2]. Transferred CD45RBhigh T cells targeting the colon induce colitis in scid mice [4]. However, the proportional distribution of migrating cells into colon, cecum and appendix has not been clarified. Purpose of the study was to investigate the proportion of migrated T cells into appendix and cecum vs. colon in vivo. Methods: CD4+ cells were isolated from the spleen of Balb/c mice using magnetic activated cell sorting (MACS). Then CD45Rbhigh cells were purified and labeled by a fluorescence kit. After control of purity and cell viability by FACS, Balb/c SCID mice were reconstituted with 500,000 CD45RBhigh cells i.p. (Tcell transfer). After onset of colitis (8 weeks) in vivo microscopy was performed. In inhalation anesthesia the colon was mobilized and exteriorized for investigation [1]. T cell migration into mucosa of appendix, cecum and colon and additionally into the spleen was quantified in vivo (T cells/mm² mucosa). Lamina propria CD4+ cells were reisolated and adhesion molecule expression was analysed by flow cytometry. To reveal onset of colitis histologic specimens and clinical signs were scored. Results: Eight weeks after CD45RBhigh T cell transfer SCID mice showed severe signs of colitis clinically and by histology. Quantification by in vivo microscopy showed an increased predominant migration of fluorescence labelled T cells into the mucosa of cecum and appendix compared to the rest of the colon. Transferred T cells were not found in the spleen. Reisolation of lamina propria CD4+ cells from the different compartments showed that Tcell migration was significantly enhanced in the appendix and cecum compared to the colon (38,6 ± 2,8 appendix tissue vs. 10,8±0,7/μg colon tissue). Reisolated T cells from both compartments showed high expression of LFA-1 and ICAM-1 and low expression of a4β7 and costimulatory receptor CD154. Conclusion: The present study shows for the first time migration of colitis inducing T cells in vivo over a longer time period. Predominant migration of T cells into the appendix compared to the rest of the colon were found in vivo and in vitro. Our results support the pivotal role of the appendix in the pathogenesis of colitis. The specific interaction of appendix tissue and T cells must be the content of further studies.