Ulcerative Colitis: Steinhoff U

Visekruna A, Joeris T, Schmidt N, Lawrenz M, Ritz JP, Buhr HJ, Steinhoff U. · Department of Surgery I, Charité-Medical School, Campus Benjamin Franklin, Berlin, Germany. · Inflamm Bowel Dis. · Pubmed #19067411 No free full text.

Abstract: BACKGROUND: The diagnostic differentiation between Crohn's disease (CD) and ulcerative colitis (UC) is sometimes difficult. To date, there are no serological markers that are specific and sensitive enough to differentiate between these 2 diseases. Early and safe prediction of the inflammatory bowel disease (IBD) type is of great importance for the specific treatment of IBD patients. We thus analyzed and compared the expression of catalytic proteasome subunits in the gut of mice and in the normal and inflamed intestines of CD and UC patients and assessed whether the subunit pattern is suitable for diagnostic differentiation. METHODS: The 20S proteasomes were isolated from surgical tissue specimens derived from terminal ileum and colon of IBD patients and controls. Spots of 20S proteasomes separated by 2D electrophoresis were analyzed by mass spectrometry. Quick detection of catalytic beta2, beta2i, and beta5i subunits was performed by incubating proteasomes with a biotinylated inhibitor (AdaK(Bio)Ahx3L3VS) and subsequently by streptavidin-horseradish peroxide. RESULTS: 20S proteasomes were isolated from the human liver, colon, and terminal ileum. Low expression of the immunosubunits beta1i and beta2i was found in the liver and colon but high amounts in the small intestine. In colon and liver beta5i was found to be associated with the constitutive beta1, beta2 subunits, indicating the existence of mixed proteasomes. Further, inflammation in CD but not UC patients induced massive upregulation of beta1i and beta2i in the colon and terminal ileum, indicating the importance of this protein complex as a disease marker. CONCLUSIONS: We here show that CD and UC patients display a characteristic pattern of proteasome subunit composition which can be used as diagnostic tool to differentiate between CD and UC.

Visekruna A, Joeris T, Seidel D, Kroesen A, Loddenkemper C, Zeitz M, Kaufmann SH, Schmidt-Ullrich R, Steinhoff U. · Max Planck Institute of Infection Biology, Berlin, Germany. · J Clin Invest. · Pubmed #17124531 links to  free full text

Abstract: Enhanced NF-kappaB activity is involved in the pathology of both forms of inflammatory bowel disease (IBD), Crohn disease (CD) and ulcerative colitis (UC). Here we analyzed the mechanism of proteasome-mediated NF-kappaB activation in CD and UC. Our studies demonstrate that the subunit composition and the proteolytic function of proteasomes differ between UC and CD. High expression of the immunoproteasome subunits beta1i and beta2i is characteristic of the inflamed mucosa of CD. In line with this, we found enhanced processing of NF-kappaB precursor p105 and degradation of inhibitor of NF-kappaB, IkappaBalpha, by immunoproteasomes isolated from the mucosa of CD patients. In comparison with healthy controls and CD patients, UC patients exhibited an intermediate phenotype regarding the proteasome-mediated processing/degradation of NF-kappaB components. Finally, increased expression of the NF-kappaB family member c-Rel in the inflamed mucosa of CD patients suggests that p50/c-Rel is important for IFN-gamma-mediated induction of immunoproteasomes via IL-12-driven Th1 responses. These findings suggest that distinct proteasome subunits influence the intensity of NF-kappaB-mediated inflammation in IBD patients.

Prinz I, Klemm U, Kaufmann SH, Steinhoff U. · Department of Immunology, Max Planck Institute for Infection Biology, Berlin, Germany. · Gastroenterology. · Pubmed #14699498 No free full text.

Abstract: BACKGROUND AND AIMS: An unconventional CD4+ TCRalpha(-)beta(+) cell population mediates the development of colitis resembling ulcerative colitis in T-cell receptor alpha mutant (TCRalpha(-/-)) mice. However, the significance of such T cells in individuals with an intact TCRalpha locus remains unclear. Because a substantial proportion of naturally rearranged TCRalpha chains fails to pair with TCRbeta chains, the aim of this study was to analyze the development of CD4+ TCRalpha(-)beta(+) cells and the course of colitis in the presence of such a TCRalpha chain. METHODS: TCR chain transgenic TCRalpha(-/-) mice were generated and compared with wild-type and TCRalpha(-/-) mice by flow cytometric analysis of T lymphocytes with respect to their TCR expression and activation status and by histological analysis of colon tissue. The colitogenic potential of the unconventional CD4+ TCRalpha(-)beta(+) cells was assessed by adoptive transfer experiments. Furthermore, the half-life of TCRbeta chains was determined by pulse-chase labeling and immunoprecipitation. RESULTS: Transgenic expression of a TCR Valpha7.2 chain led to increased frequencies of CD4+ TCRalpha(-)beta(+) cells that caused rapid onset of colitis, reminiscent of, but even more severe than, that in TCRalpha(-/-) mice. This unconventional T-cell population displayed a constitutively activated phenotype in normal and transgenic TCRalpha(-/-) mice. An extended half-life of newly synthesized TCRbeta chains suggests a chaperone function of the TCR Valpha7.2 chain in TCRalpha(-/-) mice. CONCLUSIONS: Physiological TCRalpha rearrangement can promote the formation of chronically activated CD4+ TCRalpha(-)beta(+) T cells and may play a role in the etiology of UC.