ABSENCE OF CD39 MAY INDUCE A PRE-EXHAUSTED PHENOTYPE ON TUMOR-INFILTRATING CD8+ T LYMPHOCYTES.

Buenos Aires

Congreso; Reunión Conjunta de Ciencias Biomédicas; 2021

SAI - SAIC - AAFE - NANOMED

We previously demonstrated that CD39KO tumor-bearing mice exhibit a higher % of tumor-infiltrating (TI) CD8+ T cells with effector phenotype as well as a higher % of specific TI-CD8+ T cells than Wild type (WT). CD39 participates in the generation of adenosine, an immunosuppressive molecule that interferes in the anti-tumor response. In this work, we evaluated the role of CD39 on TI-CD8+ T cells. C57BL/6 WT and CD39KO mice were injected with 1x106 B16F10-OVA tumor cells, 17 days after injection, we evaluated by flow cytometry the expression of inhibitor receptors (IRc) (PD-1 and TIM-3), transcription factors (TF) related to exhaustion (TOX, TCF-1, EOMES, T-bet and IRF-4) and cytotoxic related molecules (granzime B (GzB), perforin, and CD107) on TI-CD8+ T cells. CD39 KO and WT tumor bearing mice exhibited two PD-1 expressing populations: a PD-1high and PD-1low; however, CD39KO mice exhibited a higher % of PD-1low TI-CD8+ T cells than WT(p<0.005). CD39KO and WT mice showed a high % of PD-1high cells co-expressed TIM-3 (82,4±6,1 and 80,3±17,9 respectively), an IRc related to terminal exhaustion, while a low % of PD-1low cells were TIM-3+ (17,5±11,2 and 34,0±19,9). PD-1low cells from CD39 and WT mice also exhibited lower expression of TBET, EOMES, and IRF-4 than PD-1high cells (p<0.05). Whereas most PD-1low TI-CD8+ T cells from CD39 KO and WT were TCF-1+ (65.4±14.4 and 71.4±11.5), a TF related to pre-exhaustion, PD-1high CD8+ cells were TOX+ and TCF-1- (92.8±4.2 and 86.4±7.5). TI-CD8+ T cells cytotoxicity increase as they become more exhausted, accordingly, a higher % of CD8+ GzB+, perforin+ and CD107+ cells were found within PD-1high cells compared to PD-1low (p<0.05) TI-CD8+ T cells. Our results suggest that the absence of CD39 may favor a pre-exhausted phenotype on TI-CD8+ T cells, which are known to respond better than terminal exhausted T cells to anti-checkpoints, reinforcing the idea that CD39 could be consider as a promising target in anti-tumor immunotherapy.