Targeting LRRC25 enhances antitumor immunity of tumor-associated macrophages through CD8+ T cells [scRNA-seq]

Leucine-rich repeat containing 25 (LRRC25), a type I membrane protein, is specifically expressed in myeloid cells. The anti-inflammatory function of LRRC25 has been established in multiple sterile and pathogenic models, however, its role in cancer remains largely unexplored. In this study, we demonstrated that LRRC25 is highly expressed in tumor-associated macrophages (TAMs) across human and mouse tumors. Lrrc25 deficiency in mice suppressed various tumor types by reprogramming TAMs toward an antitumoral phenotype and enhancing CD8+ T cell activation. Lrrc25 deficiency facilitated the reprogramming of TAMs through activation of the Nox2-ROS-Nlrp3-Il1β signaling pathway. Additionally, our findings confirmed the host safety of Lrrc25 deficiency. Overall, our results elucidate the role of LRRC25 in orchestrating TAMs and suggest that LRRC25 could serve as an effective and safe immunotherapy target for cancer treatment. At day 14 after B16F10 cells inoculation, or day 26 after MC38 cells inoculation, the tumors from 3 WT and 3 Lrrc25-/- mice were harvested, and 100 mm3 of each tumor was collected. Tumor tissues from 3 mice of the same group were randomly pooled into one mixed sample, and dissociated. Cell counts and viability were determined after removal of erythrocytes , and then debris and dead cells were removed using commercial kit. Fresh cells were washed twice in RPMI1640 and then resuspended at 1×106 cells per ml in 1×PBS containing 0.04% bovine serum albumin (BSA). Finally, CD45+ immune cells were isolated using magnetic beads and mixed with the original cell suspension at a ratio of 5:1.