Galvani, R. G. A. | Search bioRxiv

bioRxiv2026

LysoDCs in Peyer's patches program compartmentalized microbiota-specific Th17 responses

Segmented filamentous bacteria (SFB) are a canonical model of microbiota-driven Th17 immunity, but how distinct gut-associated lymphoid tissues shape the quality and effector potential of commensal-specific T-cell responses remains unclear. Here we show that Peyers patches (PPs) and mesenteric lymph nodes (MLNs) generate transcriptionally, clonally, and functionally distinct SFB-reactive CD4 T-cell programs. In PPs, CCR2-dependent monocyte-derived LysoDCs capture luminal SFB and locally prime antigen-specific CD4 T cells. PP priming drives robust T cell activation, Th17 differentiation with type 1 regulatory (Tr1)-like features, preferential clonal expansion within Th17-Tfh17 lineages, and tissue-retention programs. In contrast, CCR2-independent MLN priming induces a less differentiated, recirculating profile dominated by non-expanded clonotypes. Notably, these distinct programs carry functional consequences. Upon transfer into Citrobacter rodentium-infected lymphopenic mice, PP-primed T cells preserve barrier integrity and limit pathology, whereas MLN-primed cells from the same donors fail to provide equivalent protection. Together, these findings establish PP LysoDCs as specialized orchestrators of compartmentalized microbiota-specific immunity and identify the anatomical site of commensal priming as a key determinant of T-cell functional diversification and mucosal immune outcome. HIGHLIGHTSSFB colonization drives compartmentalized effector and regulatory CD4 T-cell programs in PPs versus MLNs. Embigin LysoDCs in PPs directly sample SFB antigens and prime SFB-reactive CD4 T cells locally. PP priming induces Tr1-like Th17 differentiation, preferential Th17-Tfh17 clonal expansion, and tissue residency. PP-primed CD4 T cells ameliorate colitis-associated pathology during enteric infection, whereas MLN-primed cells do not. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=121 SRC="FIGDIR/small/734008v1_ufig1.gif" ALT="Figure 1000"> View larger version (44K): org.highwire.dtl.DTLVardef@8d59dborg.highwire.dtl.DTLVardef@6643borg.highwire.dtl.DTLVardef@19e63a7org.highwire.dtl.DTLVardef@1a0a64b_HPS_FORMAT_FIGEXP M_FIG C_FIG

immunology↗

bioRxiv2025

The Single-Cell Landscape of Peripheral and Tumor-infiltrating Immune Cells in HPV- HNSCC

Head and neck squamous cell carcinoma (HNSCC) is the sixth most common cancer worldwide. HPV-negative HNSCC, which arises in the upper airway mucosa, is particularly aggressive, with nearly half of patients succumbing to the disease within five years and limited response to immune checkpoint inhibitors compared to other cancers. There is a need to further explore the complex immune landscape in HPV-negative HNSCC to identify potential therapeutic targets. Here, we integrated two single-cell RNA sequencing datasets from 29 samples and nearly 300,000 immune cells to investigate immune cell dynamics across tumor progression and lymph node metastasis. Notable shifts toward adaptative immune cell populations were observed in the 14 distinct HNSCC-associated peripheral blood mononuclear (PBMCs) and 21 tumor-infiltrating immune cells (TICs) considering disease stages. All PBMCs and TICs revealed unique molecular signatures correlating with lymph node involvement; however, broadly, TICs increased ligand expression among effector cytokines, growth factors, and interferon-related genes. Pathway analysis comparing PBMCs and TICs further confirmed active cell signaling among Monocyte-Macrophage, Dendritic cell, Natural Killer (NK), and T cell populations. Receptor-ligand analysis revealed significant communication patterns shifts among TICs, between CD8+ T cells and NK cells, showing heightened immunosuppressive signaling that correlated with disease progression. In locally invasive HPV-negative HNSCC samples, highly multiplexed immunofluorescence assays highlighted peri-tumoral clustering of exhausted CD8+ T and NK cells, alongside their exclusion from intra-tumoral niches. These findings emphasize cytotoxic immune cells as valuable biomarkers and therapeutic targets, shedding light on the mechanisms by which the HNSCC sustainably evades immune responses.

cancer biology↗