Semaphorin 3A causes immune suppression by inducing cytoskeletal paralysis in tumour-specific CD8+ T cells

Semaphorin 3A causes immune suppression by inducing cytoskeletal paralysis in tumour-specific CD8+ T cells

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Abstract Semaphorin-3A (SEMA3A) functions as a chemorepulsive signal during development and can affect T cells by altering their filamentous sun decal for wall actin (F-actin) cytoskeleton.The exact extent of these effects on tumour-specific T cells are not completely understood.Here we demonstrate that Neuropilin-1 (NRP1) and Plexin-A1 and Plexin-A4 are upregulated on stimulated CD8+ T cells, allowing tumour-derived SEMA3A to inhibit T cell migration and assembly of the immunological synapse.Deletion of NRP1 in both CD4+ and CD8+ T cells enhance CD8+ T-cell infiltration into tumours and restricted tumour growth in animal models.

Conversely, over-expression of SEMA3A inhibit CD8+ T-cell infiltration.We further show that SEMA3A affects CD8+ T cell F-actin, leading to inhibition of immune synapse formation and motility.Examining a clear cell renal cell carcinoma patient cohort, we find that SEMA3A expression is associated with reduced survival, and that T-cells appear trapped in SEMA3A rich regions.Our study establishes SEMA3A as an inhibitor of effector CD8+ T cell tumour infiltration, suggesting that s2720 blocking NRP1 could improve T cell function in tumours.