Deficiency of lysosomal TMEM175 in myeloid macrophages exerts anti-tumor immunity via inflammasome and cross-presentation pathway

Discovering more targets is of great importance for developing alternative interventions for tumor therapy. The roles of transmembrane protein 175 (TMEM175) in neurodegeneration diseases have been reported, however its functions in tumor immune surveillance are not known. We show that TMEM175 conditional knockout in macrophages inhibits the tumor growth and metastasis through promoting the anti-tumor immunity in the tumor microenvironment (TME), including elevated M1-like polarization, reduced M2-like polarization, and facilitated recruitment and activation of T cells and nature killer cells (NKs). The anti-tumor immunity is abrogated by caspase-1 inhibitor VX-765, anti-IL-1β, and anti-IL-18. Tmem175−/− bone marrow-derived macrophages (BMDMs) show enhanced tumor antigen cross-presentation that is further strengthened by IL-1β and IL-18. NLRP3 is robustly elicited in Tmem175−/− BMDMs by the tumor cell debris through lysosomal permeabilization and cathepsin B leakage. Finally, Tmem175−/− mice are more responsive to anti-PD-1. Our works implies TMEM175 to be a potential target for immunotherapy. Alternative targets are required for tumor therapy. The authors here show that transmembrane protein 175 (TMEM175) knock out in macrophages improves aPD-1 treatment prognosis with the mechanism of enhanced NLRP3 expression and antigen cross-presentation of macrophages.