T-cell-mediated Immune Regulation in the GI Tract

A team of Swiss researchers recently set out to examine the nature of T cell-mediated immuno-regulation in the gastrointestinal tract. The research team was made up of doctors L. Saurer and C. Mueller of the Institute of Pathology at the University of Bern in Switzerland.

In the human intestinal tract, just a single layer of epithelial cells divides innate and adaptive immune effector cells from a wide array of antigens. Here, the immune system faces a tall task in accepting beneficial flora and dietary antigens while preventing the dissemination of potential pathogens. When the tightly controlled process of immune system reactions breaks down, harmful inflammation and damage may result.

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In light of this, a great deal of focus has shifted toward 'conventional' regulatory CD4+ T cells, including naturally occurring and adaptive CD4+ CD25+ Foxp3+ T cells, Th3 and Tr1 cells.

However, control mechanisms in the intestinal mucosa are highly intricate, and include adaptations of non-haematopoietic cells and innate immune cells in addition to the presence of unconventional T cells with regulatory properties such as resident TCRγδ or TCRαβ CD8+ intraepithelial lymphocytes.

In the study, L. Saurer and C. Mueller seek to provide an overview of the present body of knowledge on standard and non-standard regulatory T cell subsets (Tregs), with particular focus on clinical data and the potential role or malfunctioning of Tregs in four major human gastrointestinal diseases, i.e. inflammatory bowel diseases, celiac disease, food allergy and colorectal cancer.

Their data confirms most of the findings derived from experimental animal models, and has implications for clinical immunology, food allergy, immunoregulation, immunotherapy, mucosal immunology, and regulatory T cell protocols. Their findings appear in the February 2009 issue of Allergy.