Introduction and Objective: The hallmark of T1D is the destruction of pancreatic insulin producing β-cells by autoreactive T cells. The quest for new antigen-specific autoreactive cells as well as for strategies that may target them are highly required to provide a more successful therapeutic option for T1D. Starting from many evidence suggesting a potential role of glial glutamate transporter 1 (GLT-1) in autoimmunity, this study aims to identify and mechanistically characterize GLT-1 autoreactive T cells in vitro and in vivo.Methods: In vitro: GLT-1-derived peptides immunogenicity was tested by ELISPOT and proliferation assay, while GLT-1 autoreactive T cells were characterized by scRNA-seq and subsequently isolated with newly designed dextramers. In vivo: GLT-1-derived peptides ability to modify T1D onset was tested in NOD mice and NOD SCID animals, a more stringent model of disease. Autoimmune response was evaluated as well as insulitis score.Results: GLT-1-derived peptides were able to significantly increase the number of CD4+ IFN-g producing T cells, stimulate proliferation and expression of key genes involved in T cell activation/cytotoxicity (GZMA, CXCR6, CCL5, GZMK, KLRG1, KLRB1, PRF1) in a subpopulation of CD4+ T cells in T1D patients. Moreover, we were able to identify of GLT-1 autoreactive T cells with our newly designed dextramers. In vivo, GLT-1-derived peptides treatment significantly increased the autoimmune response in splenocytes from GLT-1-treated NOD animals compared to untreated mice. Finally, in the more stringent model, splenocytes obtained from normoglycemic GLT-1-treated NOD mice injected in NOD SCID animals induce a more severe diabetes compared to NOD SCID receiving splenocytes from normoglycemic NOD mice.Conclusion: Our findings indicate the existence of the new population of GLT-1 autoreactive T cells both in human and mice establishing a future blueprint for a novel therapy for T1D aimed at targeting these cells, thus preventing islet destruction.
E. Assi: None. F. D’Addio: Other – Founder and consultant; Ended; Enthera srl. V. Usuelli: None. C. Loretelli: None. M. Ben Nasr: None. M. Zocchi: None. A. Petrazzuolo: None. A. Maestroni: None. G. Rossi: None. I. Pastore: Advisory Panel; Ended; Sanofi. Board Member; Ended; Novo Nordisk. A. Rossi: Consultant; Ended; Roche Diabetes Care, Abbott Diabetes. L. Montefusco: None. G. Zuccotti: None. P. Fiorina: Board Member; Ended; Novo Nordisk, Lilly, AstraZeneca, Boehringer Ingelheim International GmbH.
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