USP25 deficiency promotes T cell dysfunction and transplant acceptance via mitochondrial dynamics

Background: During organ transplantation, pharmacologic drugs targeting T cell activation signal to inhibit T cell-mediated allo-rejection are insufficient and not durable to suppress chronic rejection. Recent advances highlight an exhausted or dysfunctional status of T cells, which favor transplant acceptance.

Methods: The models of MHC-mismatched (BALB/c to C57BL/6 or USP25 KO mice) heterotopic heart transplantation and skin transplantation were utilized to evaluate the regulatory effects of Ubiquitin-Specific Protease 25(USP25) deficiency in vivo. The consequences of USP25 deficiency on murine T-cell proliferation, activation, cytokine secretion, mixed lymphocyte reaction (MLR) and energy metabolism were investigated in vitro. The signaling pathway of T cells in knock out mice was detected by Western blotting and Co-IP.

Results: We found T cells were dysfunctional inUSP25KO mice. Due to T cell dysfunction, skin and heart graft had a longer survival. In these dysfunctional T cells, mitochondria number and cristae condensation were decreased. Impaired mitochondrial mass and function favored to allo-graft acceptance. Furthermore, USP25 interacted with ATP5A and ATP5B to promote their stability.

Conclusions: Our data suggest that USP25 is a potential target to induce T cell dysfunction and allo-graft tolerance. And USP25 mediated mitochondrial homeostasis may contribute to reverse T cell exhaustion or dysfunction in tumor and chronic Infection.

ATP5a1, ATP5b; Mitochondrial dynamics; USP25, T cell dysfunction.