HTRA1+ Macrophages Induce T-cell Egress through CRIP1/NF-κB/CXCL12 to Limit the Effects of Immunotherapy in Triple-Negative Breast Cancer

The variation in immunotherapy responses among patients with triple-negative breast cancer (TNBC) is attributed to the high heterogeneity of tumor immune components, in which macrophages play a key role. Hence, identification of key macrophage subpopulations associated with immunotherapy efficacy could provide important biological and therapeutic insights. In this study, using single-cell and spatial transcriptomes, we identified, at the single-cell level, a subpopulation of macrophages related to T-cell expansion during immunotherapy, characterized by high expression of high-temperature requirement A1 (HTRA1), and correlated with clinical and immunotherapy outcomes in TNBC. Loss of macrophage-specific Htra1 in transgenic mice resulted in delayed TNBC growth, improved immunotherapy efficacy, and increased CD8+ T-cell infiltration. Mechanistically, HTRA1 associated with cysteine-rich protein 1 (CRIP1) to facilitate CRIP1 binding to NF-κB, thereby activating the NF-κB pathway and downstream CXCL12 transcription, leading to T-cell exit from tumors. Endothelial cell-derived CX3CL1 was implicated in the recruitment of HTRA1+ macrophages to tumor sites. Pharmacologic antagonism of the CXCL12/CXCR4 axis potentiated the immunotherapy efficacy in orthotopic TNBC mouse models. In conclusion, this study highlights an HTRA1+ macrophage subpopulation that can limit T-cell infiltration and immunotherapy efficacy via the CXCL12/CXCR4 axis, which offers new leads to improve immunotherapeutic interventions in TNBC.