Mucosal Inflammation: Review

Background: Chronic intestinal inflammation due to noninfectious causes represents a growing health issue all over the world. Celiac disease as well as inflammatory bowel diseases (IBD) like Crohn’s disease and ulcerative and microscopic colitis involve uncontrolled T-cell activation and T-cell-mediated damage as common denominators. Therefore, diagnosis and treatment decisions clearly benefit from the knowledge of the intricacies of the systemic and the local T-cell activity. Summary: Depending on the cytokine milieu, CD4 + T cells can differentiate into proinflammatory T helper 1 (Th1), anti-inflammatory Th2, antimicrobial Th17, pleiotropic Th9, tissue-instructing Th22 cells, and in the regulatory compartment forkhead box protein 3 + Treg, suppressive Tr1 or Th3 cells. Additionally, follicular Th cells provide B-cell help in antibody class switching; cytotoxic CD8 + T cells target virus-infected or tumor cells. This review discusses our current knowledge on the contribution of defined T-cell subpopulations to establishing and maintaining chronic intestinal inflammation in either of the above entities. It also puts emphasis on the differences in the prevalence of these diseases Received: January 29, 2016 Accepted: March 2, 2016 Published online: April 9, 2016 Anja A. Kühl Medical Department (Gastroenterology/Infectious Diseases/Rheumatology) Campus Benjamin Franklin, Charité – Universitätsmedizin Berlin Hindenburgdamm 30, DE–12200 Berlin (Germany) E-Mail anja.kuehl @ charite.de © 2016 S. Karger AG, Basel 2296–9403/16/0012–0052$39.50/0 www.karger.com/iid T. Hisamatsu and A.A. Kühl contributed equally to this work.