Early and sustained immunosuppressive macrophage responses to carcinogenic carbon nanotubes in a rat mesothelioma bioassay.
(2015) Beltox Annual Meeting. — Location: Antwerp, Belgium. (26.November.2015)
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- Abstract
- MM is a rare cancer caused by asbestos exposure affecting the serous membrane of pleural and peritoneal cavities. MM remains a highly refractory cancer to existing therapeutic strategies. The asbestos-like toxicity of engineered carbon nanotubes (CNT), notably their capacity to induce malignant mesothelioma (MM), is a serious cause of concern for public health. Intensive research efforts are therefore needed to better understand the pathomechanisms of CNT-induced MM. The present project deals with immunosuppression during the mesothelial response to CNT in rats. There is growing evidence that tumors harbor immunosuppressive cells that inhibit both innate and adaptive immunity, subverting immune surveillance and preventing efficient natural or therapeutic anti-tumor immune responses. We aim to determine if the carcinogenic response to Mitsui-7 CNT (CNT-7) is associated with the accumulation of immunosuppressive macrophages. We used a Wistar rat peritoneum model which allows directly exposing mesothelial cells to CNT or asbestos, and easily sampling the mesothelial cavity for monitoring macrophage responses during the carcinogenic process. We show that FACS-sorted CD11b/chigh and His48int macrophages present in CNT-7-induced mesothelioma microenvironment suppress polyclonal activation of T lymphocytes in vitro. These inhibitory macrophages are already present during the early response to carcinogenic CNT or asbestos (day 1 to 30), well before the establishment of mesothelioma (6 months). Immunosuppressive peritoneal macrophages were not observed in mice, which are resistant to mesothelioma development upon CNT-7. RTqPCR revealed that peritoneal macrophages purified from CNT-treated rats (day 1-30) highly expressed the immunosuppressive mediators IL-10 and Arginase-1 in comparison to naive peritoneal macrophages or macrophages obtained after silica, a particle that does not induce mesothelioma. Altogether, our data demonstrate that carcinogenic CNT possess the intrinsic capacity to induce a preferential, rapid and sustained accumulation of immunosuppressive macrophages before mesothelioma is established. These data provide new insight into the possible contribution of immunosuppression in the early pathogenic processes of CNT-induced mesothelioma.
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Parent, M.-A., & Huaux, F. (2015). Early and sustained immunosuppressive macrophage responses to carcinogenic carbon nanotubes in a rat mesothelioma bioassay. Beltox Annual Meeting., Antwerp, Belgium. https://hdl.handle.net/2078.5/180366