Spatial and functional dissection of cancer-associated fibroblasts-mediated immune modulation in H. pylori-associated gastric cancer.

BACKGROUND

Cancer-associated fibroblasts (CAFs) are key regulators of the tumor microenvironment, yet their spatial organization and immunomodulatory functions in H. pylori-associated gastric cancer (GC) remain incompletely understood.

METHODS

We profiled formalin-fixed paraffin-embedded (FFPE) tumors from 71 GC patients using spatial transcriptomics and integrated single-cell RNA-seq from three independent cohorts (China, USA, and Singapore). CAF-immune cell colocalization was quantified by neighborhood enrichment and aggregation index score. Ligand-receptor inference and trajectory analysis resolved CAF signaling and state transitions. To delineate post-transcriptional control, ARE-motif scanning and expression correlations were combined with laser-assisted crosslinking and immunoprecipitation sequencing (LACE-seq) to nominate ZFP36 targets. Immune contexture and prognostic associations were evaluated using CIBERSORT-ABS and Kaplan-Meier analyses in The Cancer Genome Atlas (TCGA) and Asian Cancer Research Group (ACRG) cohorts.

RESULTS

We first defined the spatial distributions of the four CAF subtypes reported in prior studies and found that their immune associations varied across histologic and infection-defined GC subtypes. In H. pylori-positive tumors, THBS1⁺ CAFs were spatially enriched near regulatory T cells (Tregs) and were associated with local immunosuppression through WNT5-FZD interactions. In parallel, ZFP36 bound AU-rich elements within the FN1 3' untranslated region (3'UTR), destabilizing FN1 mRNA and thereby diminishing FN1⁺ CAF-mediated cytotoxic T lymphocyte (CTL) activation. Together, these axes promoted Treg accumulation and suppression of CTL activation.

CONCLUSIONS

These findings reveal infection-associated stromal programs that shape the immune landscape in GC and highlight CAF-directed pathways as potential therapeutic targets in H. pylori-associated GC.