Tertiary Lymphoid Structure-Associated B Cells Enhance CXCL13+CD103+CD8+ Tissue-Resident Memory T-Cell Response to Programmed Cell Death Protein 1 Blockade in Cancer Immunotherapy.

BACKGROUND & AIMS: Although the presence of tertiary lymphoid structures (TLS) correlates with positive responses to immunotherapy in many solid malignancies, the mechanism by which TLS enhances antitumor immunity is not well understood. The present study aimed to investigate the underlying cross talk circuits between B cells and tissue-resident memory T (Trm) cells within the TLS and to understand their role in the context of immunotherapy. METHODS: Immunostaining and H&E staining of TLS and chemokine (C-X-C motif) ligand 13 (CXCL13)+ cluster of differentiation (CD)103+CD8+ Trm cells were performed on tumor sections from patients with gastric cancer (GC). The mechanism of communication between B cells and CXCL13+CD103+CD8+ Trm cells was determined in vitro and in vivo. The effect of CXCL13+CD103+CD8+ Trm cells in suppressing tumor growth was evaluated through anti-programmed cell death protein (PD)-1 therapy. RESULTS: The presence of TLS and CXCL13+CD103+CD8+ Trm cells in tumor tissues favored a superior response to anti-PD-1 therapy in patients with GC. Additionally, our research identified that activated B cells enhanced CXCL13 and granzyme B secretion by CD103+CD8+ Trm cells. Mechanistically, B cells facilitated the glycolysis of CD103+CD8+ Trm cells through the lymphotoxin-α/tumor necrosis factor receptor 2 (TNFR2) axis, and the mechanistic target of rapamycin signaling pathway played a critical role in CD103+CD8+ Trm cells glycolysis during this process. Moreover, the presence of TLS and CXCL13+CD103+CD8+ Trm cells correlated with potent responsiveness to anti-PD-1 therapy in a TNFR2-dependent manner. CONCLUSIONS: This study further reveals a crucial role for cellular communication between TLS-associated B cell and CXCL13+CD103+CD8+ Trm cells in antitumor immunity, providing valuable insights into the potential use of the lymphotoxin-α/TNFR2 axis within CXCL13+CD103+CD8+ Trm cells for advancing immunotherapy strategies in GC.

Gastric Microbiome Alterations Are Associated with Decreased CD8+ Tissue-Resident Memory T Cells in the Tumor Microenvironment of Gastric Cancer.

The host microbiota is closely associated with tumor initiation and progression in multiple solid tumors including gastric cancer. The aim of this study was to investigate in patients with gastric cancer whether there are alterations in gastric microbiota and any potential association these may have with immune dysregulation. 16S rRNA gene sequencing was used to analyze tumor microbiota of 53 patients with gastric cancer and gastric mucosal tissue microbiota of 30 patients with chronic gastritis. The effect of microbiota on the tumor microenvironment (TME) was studied by single-cell sequencing, immunohistochemistry, multiplex immunofluorescence staining, and flow cytometry, as well as in a mouse model of primary gastric cancer. The gastric cancer microbiota was characterized by reduced microbial diversity and enrichment of the Oceanobacter, Methylobacterium, and Syntrophomonas genera. Intratumoral Methylobacterium was significantly associated with poor prognoses in patients with gastric cancer. It also was inversely correlated with the frequency of CD8+ tissue-resident memory T (TRM) cells in the TME. TGFß was significantly reduced in gastric cancer samples with higher abundance of Methylobacterium. Finally, we verified that Methylobacterium can decrease TGFß expression and CD8+ TRM cells in the tumor by establishing a mouse model of primary gastric cancer. The results suggest that tumor microbiota and exhausted CD8+ TRM cells in the TME of gastric cancer are significantly correlated, and that Methylobacterium may play a role in gastric carcinogenesis.