Background: CD8⁺ T lymphocytes are critical mediators of neuroinflammatory diseases. Understanding the mechanisms that govern the function of this T cell population is crucial to better understanding central nervous system autoimmune disease pathology. We recently identified a novel population of highly cytotoxic c-Met-expressing CD8⁺ T lymphocytes and found that hepatocyte growth factor (HGF) limits effective murine cytotoxic T cell responses in cancer models. Here, we examined the role of c-Met-expressing CD8⁺ T cells by using a MOG_35-55 T cell-mediated EAE model.

Methods: Mice were subcutaneously immunized with myelin oligodendrocyte glycoprotein peptide (MOG)_35-55 in complete Freund's adjuvant (CFA). Peripheral and CNS inflammation was evaluated at peak disease and chronic phase, and c-Met expression by CD8 was evaluated by flow cytometry and immunofluorescence. Molecular, cellular, and killing function analysis were performed by real-time PCR, ELISA, flow cytometry, and killing assay.

Results: In the present study, we observed that a fraction of murine effector CD8⁺ T cells expressed c-Met receptor (c-Met⁺ CD8⁺ ) in an experimental autoimmune encephalitis (EAE) model. Phenotypic and functional analysis of c-Met⁺ CD8⁺ T cells revealed that they recognize the encephalitogenic epitope myelin oligodendrocyte glycoprotein_37-50 . We demonstrated that this T cell population produces higher levels of interferon-γ and granzyme B ex vivo and that HGF directly restrains the cytolytic function of c-Met⁺ CD8⁺ T cells in cell-mediated cytotoxicity reactions CONCLUSIONS: Altogether, our findings suggest that the HGF/c-Met pathway could be exploited to modulate CD8⁺ T cell-mediated neuroinflammation.