November 11, 2011

Balancing act in the gut

Vanderbilt researchers have identified an antigen important to balancing the immune response to bacteria in the gut.

Illustration of human intestinal tract

The intestinal epithelial cells that line the gut form a barrier between the contents of the intestines – food, “good” microbes and harmful pathogens – and the rest of the body. Immune responses in this barrier must be appropriately balanced to protect against pathogens but not cause inflammatory diseases.

The immune response factor thymus leukemia antigen (TL) is selectively expressed in intestinal epithelial cells and interacts with T lymphocytes (white blood cells). Danyvid Olivares-Villagómez, research assistant professor of pathology, microbiology and immunology, Luc Van Kaer, professor of pathology, microbiology and immunology, and colleagues now report that TL expression promotes the development of inflammatory bowel disease and also protects against infection by the intestinal pathogen Citrobacter rodentium in mouse models. They demonstrate that TL expression pushes T cells toward a “Th17” response that contributes to inflammation and protection against pathogens.

The findings, reported in the Oct. 15 Journal of Immunology, identify TL as a critical factor for balancing the immune response in the gut, which could be important for the development of mucosal vaccines and therapies for inflammatory diseases of the gastrointestinal tract.