Skewing T helper cells exposed to asbestos fibers toward reduction of tumor immunity or activation of autoimmunity
Asbestos fibers cause malignant tumors such as lung cancer and malignant mesothelioma. Furthermore, with carcinogenic activity, they alter the human immune system. Our previous findings indicated that immune cells exposed to asbestos revealed cellular and molecular alterations that resulted in a reduction in anti-tumor immunity. Focusing on regulatory T cells (Tregs), we found enhanced function and proliferating activity resulting from asbestos exposure using an in vitro cell line model. Additionally, surface C-X-C motif chemokine receptor 3 (CXCR3) levels in T helper (Th) cells as well as the capacity to produce interferon γ were reduced, which lead to decreased anti-tumor immunity. However, our recent findings showed that IL-17 production in the intracellular CXCR3-rich fraction in Th cells was enhanced by asbestos exposure. Regarding alterations of autoimmunity, some investigators have reported the detection of autoantibodies against endothelial cells and mesothelial cells in an asbestosexposed mouse model and suggested that these autoantibodies contribute to the formation of pulmonary fibrosis. However, the precise mechanisms by which asbestos affects the human immune system and causes cancers and the production of certain autoantibodies to create pathophysiological conditions found in asbestos-exposed patients remains to be elucidated.