[γδ1 T cells derived from breast cancer tissue induce immunosenescence of naive CD4+ T cells by producing IL-17D].

Objective To investigate the mechanism underlying the immunosuppressive effect and its reverse of γδ1 T cells derived from breast cancer tissues by inducing immunosenescence. Methods After γδ1 T cells isolated from breast cancer tissues were co-cultured with peripheral blood-derived naive CD4+ T cells, the proliferation of treated CD4+ T cells was detected by CCK-8 assay, and the activity of senescence-associated β-galactosidase (SA-β-Gal) in treated CD4+ T cells was detected by SA-β-Gal staining. After the induced senescent CD4+ T cells were co-cultured with the naive CD4+ T cells, the proliferation, apoptosis, activity of the treated CD4+ T cells were examined by CCK-8 assay, flow cytometry and SA-β-Gal staining, respectively; the expression of cell cycle-associated proteins P53, P21 and P16 in the treated CD4+ T cells was detected by Western blot analysis in order to verify the immunosuppressive effect of the senescent CD4+ T cells. The expression levels of inhibitory cytokines interleukin 17D (IL-17D), IL-10, transforming growth factor-α (TGF-α) and so on, in the supernatant were analyzed by cytokine microarray after co-culture of γδ1 T cells with naive CD4+ T cells. After the co-culture system of γδ1 T cells and naive CD4+ T cells was treated with anti-IL-17D monoclonal antibody, the proliferation of the naive CD4+ T cells was determined by CCK-8 assay. The level of IL-17D secreted by γδ1 T cells treated by single-stranded RNA40 (ssRNA40), the ligand of Toll like receptor 8 (TLR8) and TLR8 short hairpin RNA (shRNA) lentiviral vector was detected by ELISA. The effects of ssRNA40 on the immunosenescence induced by γδ1T cells were confirmed by SA-β-Gal staining and Western blot analysis. Results γδ1 T cells derived from breast cancer tissues induced the immunosenescence of the naive CD4+T cells, and the senescent CD4+ T cells further exerted the immunosuppressive effect. The results of cytokine microarray showed that IL-17D concentration was at the highest level among inhibitory cytokines in the supernatant of γδ1 T cells from breast cancer tissues. The inhibitory effect of γδ1 T cells on the proliferation of CD4+ T cells could be reduced by anti-IL-17D monoclonal antibody. TLR8 ligand ssRNA40 inhibited the secretion of IL-17D, and then partially reversed the proliferating inhibition on the naive CD4+ T cells and immunosenescent induction by γδ1 T cells. Conclusion The γδ1 T cells derived from breast cancer tissues exert immunosuppressive effect by producing IL-17D to induce the immunosenescence of the naive CD4+ T cells. TLR8 ligand ssRNA40 can partially reduce the level of IL-17D secreted by γδ1 T cells, which can partially reverse the senescence and immunosuppression effect of γδ1 T cells on naive CD4+ T cells.