Role of cell cannibalism and non-canonical autophagy in antigen presentation: implications in T-cell selection and immune homeostasis

点击翻译按钮获取中文摘要

Theme: Bioscience for HealthAntigen acquisition and presentation is a vital part of the immune system which allows cells to distinguish self from non-self and mount a protective T-cell response against invading pathogens. Cells use a variety of mechanisms of acquiring antigens, involving the uptake of intracellular and extracellular material. This project will study the role of cell cannibalism in the acquisition and presentation of antigen in the context of T-cell selection. Cell cannibalism is a mechanism in which entire live cells are engulfed by other cells, resulting in the formation of cell-in-cell structures (1), and is a core interest of the Florey lab at the Babraham Institute (http://www.babraham.ac.uk/our-research/signalling/oliver-florey) . Examples of cell-in-cell structures are found in a variety of diseases (2, 3), but importantly also occur in physiological settings between thymocytes and epithelial nurse cells during T cell development in the thymus (4) and even between the embryo and uterus during implantation (5). In these examples, internalized cells can escape their engulfment, but more commonly their fate is death which involves the activation of a non-canonical autophagy pathway that promotes the lipidation of the protein LC3 to the vacuole housing the internalized cell (6-8).This project will test the hypothesis that cell cannibalism can act as a route of antigen presentation and can be regulated by a non-canonical autophagy pathway. This would potentially have major implications in shaping the immune repertoire by controlling T cell selection and therefore participate in generating an immune system capable of responding to infection while maintaining immune tolerance.The main aims will include the development and characterization of cell-cell interactions in model systems of cell cannibalism using microscopy based techniques. This will utilize existing cell cannibalism models of cultured human epithelial cells and the establishment of new models of primary mouse thymocytes interacting with a thymic nurse cell line. These systems will then be manipulated where by internalized cells are loaded with ovalbumin antigen, and subsequent presentation of antigen by hosts cells monitored using ovalbumin-specific T cells. Different aspects of cell-in-cell formation and fate will be manipulated to test for an effect on antigen presentation. The role of autophagy in cell-in-cell mediated antigen presentation will be tested using gene editing reagents developed by the lab that specifically inhibit non-canonical autophagy.This project will combine immunology and cell biology expertise and provide a strong training in cell biology techniques, with an emphasis on microscopy, and molecular biology, including CRISPR/Cas9 gene editing. Expected results will have impacts on our understanding of how T cells are selected and the molecular pathways underlying this important homeostatic event.