CTSB+ macrophage repress memory immune hub in the liver metastasis site of colorectal cancer patient revealed by multi-omics analysis

Colorectal cancer (CRC) is a lethal malignant tumor and 25-30% of CRC patients develop liver metastasis (LM) with a worse prognosis, but the metastasis mechanism is yet elucidated. To identify the potential immune regulatory mechanism of CRC liver metastasis, single-cell sequencing and multiplex immunohistochemistry were applied to identify key cell populations of the tumor microenvironment (TME) in the CRC and LM sites. We found memory CD8+ T cells, B cells, and CTSB + macrophages were enriched in the LM site, forming the memory immune hub, which was important for the anti-tumor response against LM. Therefore, our results revealed that memory immune responses were called in the LM sites and probably meditated by CTSB + macrophages.