Tumor-draining lymph nodes respond to immune checkpoint inhibition and orchestrate tumor immune remodeling

Immune checkpoint inhibitors have traditionally been understood to exert their effects primarily within the tumor microenvironment, particularly targeting CD8 + T cells. However, recent studies have highlighted a pivotal role of tumor-draining lymph nodes in mediating responses to immune checkpoint inhibitor therapy. This study aimed to elucidate the specific mechanisms by which tumor-draining lymph nodes respond to immune checkpoint inhibitor therapy and regulate the tumor microenvironment in human colorectal cancer.

We performed single-cell RNA sequencing and T cell receptor sequencing on tumor-draining lymph nodes and tumor tissues from patients with colorectal cancer. Through in-depth analysis of the single-cell data, we established the connection between TDLNs and tumor, and explored the impact of immune checkpoint inhibitor therapy on the immune microenvironment of tumor-draining lymph nodes. In addition, we conducted animal experiments to validate these findings.

Our findings revealed that immune checkpoint inhibitor treatment induced the expansion of tumor-specific CD8 + effector memory T cells within tumor-draining lymph nodes, which may serve as a source for the progenitor-exhausted CD8 + T cells in the tumor microenvironment. Moreover, conventional dendritic cells type 1 and macrophages within tumor-draining lymph nodes facilitated this process. We also observed that immune checkpoint inhibitor therapy promoted the expansion of tumor-specific CD4 + follicular helper T cells in tumor-draining lymph nodes, which may explain the increase of CD4 + follicular helper T cells in the tumor microenvironment after immune checkpoint inhibitor therapy. These hypotheses were corroborated through experiments in mice.

Our findings delineate the critical regulatory function of tumor-draining lymph nodes in modulating the tumor microenvironment during Immune checkpoint inhibitor therapy.