Effect of cancer-neurons on cytotoxic NK cell exhaustion and immunotherapy resistance in gastric cancer via spatial ECM trapping and neuropeptide signaling.

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Background: Immunotherapy resistance remains a critical clinical challenge in gastric cancer (GC). While tumor-associated neurons are emerging as key modulators of the tumor microenvironment (TME), their spatial and functional interactions with innate immune components, particularly cytotoxic natural killer cells, remain poorly defined. This study aims to delineate the spatial topography of the neural-NK cell axis to elucidate novel mechanisms of immune evasion and therapy resistance in GC. Methods: High-resolution spatial transcriptomics (Visium HD) was utilized to map the TME of GC patients treated with immunotherapy. Cohorts were stratified by clinical response (Responders vs. Nonresponders), utilizing patient IDs as the primary stratifier for robust inter-group differential comparisons. Computational spatial workflows, including neighborhood enrichment mapping, spatial cell-cell communication, and physical distance-based spatial pseudotime trajectory modeling, were employed to characterize the interactions between tumor-associated neurons and cytotoxic NK cells. Results: Spatial neighborhood enrichment mapping revealed a profound physical colocalization of cytotoxic NK cells within the immediate neural niche specifically in Nonresponders. Differential expression and communication analyses demonstrated that tumor-associated neurons construct a dense extracellular matrix "trap" by hyper-secreting COL6A3, COL14A1, and DCN, which physically anchors NK cells. Proximally trapped NK cells underwent significant transcriptional reprogramming, strongly upregulating neuropeptide and inhibitory receptors, including RAMP2, VIPR2, and TGFBR3, driven by neural-derived VIP and TGFB1 signaling. Furthermore, spatial pseudotime trajectories—modeling the physical migration of NK cells toward neurons—revealed a progressive functional collapse. Upon entering the neural niche, NK cells acquired a terminal exhaustion phenotype (upregulation of HAVCR2 and KLRC1) and exhibited a near-complete suppression of core effector weapons (downregulation of GZMB, PRF1, and IFNG). Conversely, NK cells in Responders, or those distal to nerves in Nonresponders, maintained robust cytotoxic profiles and successfully infiltrated the tumor parenchyma. Conclusions: Tumor-associated neurons orchestrate a complex "neural trap" that physically sequesters and functionally paralyzes cytotoxic NK cells via matrix remodeling and paracrine neuropeptide signaling. This neural-induced NK cell exhaustion prevents effective immune surveillance, driving an immune-excluded TME and subsequent immunotherapy resistance in GC. Targeting the neural-immune axis, particularly the VIP-RAMP2 signaling network, represents a promising therapeutic vulnerability to restore anti-tumor immunity in resistant patients.