• INVADEseq captures host transcriptomes and bacterial signatures • Intracellular bacteria impact immune activity and immunotherapy efficacy • GZMK+ CD8 + T cells serve as biomarkers for immunotherapy response • Intracellular bacteria disrupt cDC1 and GZMK+ CD8 + T cell crosstalk INVADEseq captures host transcriptomes and bacterial signatures Intracellular bacteria impact immune activity and immunotherapy efficacy GZMK+ CD8 + T cells serve as biomarkers for immunotherapy response Intracellular bacteria disrupt cDC1 and GZMK+ CD8 + T cell crosstalk Neoadjuvant immune checkpoint blockade (NICB) therapy has shown significant efficacy in oral squamous cell carcinoma (OSCC); however, the mechanisms by which intracellular microbiota influence immune function within the tumor microenvironment remain unclear. In this study, we employ invasion-adhesion-directed expression sequencing (INVADEseq) technology to simultaneously capture host single-cell RNA sequencing data and bacterial signatures, revealing that intracellular bacteria inhibit PDCD1 expression, enhance infection responses, promote antigen presentation and macrophage activation, and reduce T cell-related immune gene expression. The key genera, Fusobacterium , Streptococcus , and Capnocytophaga , are associated with increased risks and adverse outcomes in immunotherapy across multiple tumor types. We identify GZMK+ CD8 + T cells and ZBTB16 + TAMs as markers of complete response to NICB. However, intracellular bacteria weaken the communication between cDC1 and these immune cells, potentially reducing therapeutic efficacy. Our study provides a foundation for further investigation into the mechanisms by which intracellular bacteria mediate effective responses to NICB in OSCC.
Wang et al. (Fri,) studied this question.