Phenotypic profile of peripheral blood lymphocytes in patients with inflammatory bowel diseases

Abstract

Mechanisms of recognition and effector responses of immune system upon initiation and maintenance of immune-mediated inflammation and tissue damage in inflammatory bowel diseases, including Crohn’s disease and ulcerative colitis (UC), have been actively studied over recent time. Existing evidence suggests these diseases to be caused by abnormal immune response against intestinal flora microorganisms in genetically susceptible individuals. Despite available data on the features of immune disorders in ulcerative colitis and Crohn’s disease, there are still many questions about the involved minor lymphocyte subpopulations and contribution of various functionally active molecules, which play a key role in recognition and initiation of the immune response and can be considered biomarkers of a pathological process in inflammatory bowel diseases. The populations of T lymphocytes with γδT cell receptor, B1 cells and NK T lymphocytes are of greatest interest, as well as functionally active TLRs (Toll-like receptors), CD89, CD314, etc. Due to substantial progress in studying the nature of recognition and activation of the immune cells, the paper presents phenotypic and functional characteristics of major and minor subpopulations of peripheral blood lymphocytes observed in 25 patients treated at the Surgery Department of the State Institution “Minsk Regional Clinical Hospital” (Republic of Belarus) from 2018 to 2020. The detected changes in peripheral blood lymphocyte phenotype of inflammatory bowel diseases patients suggest distinct immunological profiles prevailing in the damage mechanisms in Crohn’s disease and ulcerative colitis. I.e., in Crohn’s disease patients, B1 lymphocytes with CD19+CD5+ and NK cells in combination with increased CD56bright population, as well as NK T cells with anti-inflammatory and regulatory activity are involved into genesis of the disease. In ulcerative colitis, T, B, NK lymphocytes with pro-inflammatory phenotype and T lymphocytes with γδ T cell receptor may play a pathogenetic role in maintenance of chronic inflammation. With respect to functional significance of activating receptors, the number of TLR4- и CD89-positive cells may be used for developing immunological criteria/ biomarkers of therapeutic efficacy of new drugs. Studying interactions between innate and adaptive immunity will open new perspectives in understanding immunological disorders associated with chronic gastrointestinal inflammation.