Chemokines in gastrointestinal disorders.

The intestine is constantly challenged by food antigens and pathogens and is therefore in need of a good working innate and adaptive immune response. Chemokines are important modulators as they assure the directed movement of immune cells within the body. In addition, chemokines play an important role in hematopoiesis, angiogenesis and tumor metastasis. This review focuses on chemokines and gastrointestinal disorders, more particularly on inflammatory bowel diseases and gastrointestinal tumors. In a first part, the current knowledge on chemokine expression in inflammatory bowel diseases is summarized. Idiopathic inflammatory bowel diseases are characterized by an uncontrolled immune response. The resulting chronic inflammation of the intestine involves massive infiltration of immune cells, causing intestinal damage by the release of cytokines and proteolytic enzymes. Chemokines are believed to be key mediators in this process of aberrant leukocyte recruitment. Chemokine expression in inflammatory bowel disease strongly correlates with the grade of disease activity. The potential therapeutic use of chemokines in gastrointestinal tumors by the use of gene therapy is also reviewed. Chemokines have therapeutic potential in anti-tumor therapy by their angiostatic effect. On the other hand, chemokines can augment the cell-mediated adaptive immune response and thereby exert anti-tumor activity. However, chemokines can passively favor escape of tumor cells by stimulating the release of tissue degrading matrix metalloproteinases and can actively promote metastasis of chemokine receptor-expressing tumor cells.