胃癌（GC）是一种主要癌症类型，其特征是肿瘤细胞和肿瘤免疫微环境（TIME）的高度异质性。一种难以治疗的GC亚型是胃粘液样环状细胞癌（GSRCC），这种癌症与预后不佳有关。然而，目前还不清楚GSRCC TIME的特征以及这些特征如何影响临床结果。我们招募了32例晚期不同亚型的GC患者，并使用免疫靶向单细胞分型策略对其TIME进行了分析，包括（i）免疫靶向单细胞RNA测序（scRNA-seq，n = 20例患者）和（ii）针对质谱细胞术（CyTOF，n = 12例患者）的靶向抗体组蛋白表达分型。我们还生成了匹配的T和B细胞的V(D)J测序。我们发现，与非GSRCC相比，GSRCC TIME似乎是静止的，CD4+和CD8+ T细胞都难以动员，这进一步削弱了B细胞的正常功能。CXCL13是由Thf、Th17和疲惫的CD8+ T细胞主要产生的，是这种转化的中心协调者。我们表明，CXCL13表达可以预测GC患者对免疫检查点阻滞的反应，这可能与其对第三淋巴结构的影响有关。我们的研究提供了先进GC患者中免疫细胞组分和细胞状态的全面分子肖像，突出了GSRCC中的适应性免疫不应答和CXCL13在TIME中的调节作用。我们的靶向单细胞转录组和蛋白质组分型代表着一种针对TIME的转化研究的强有力的方法。Copyright © 2023 AGA Institute. 发布Elsevier Inc保留所有权利。

Gastric cancer (GC) is a major cancer type characterized by high heterogeneity in both tumor cells and the tumor immune microenvironment (TIME). One intractable GC subtype is gastric signet-ring cell carcinoma (GSRCC), which is associated with poor prognosis. However, it remains unclear what the GSRCC TIME characteristics are and how these characteristics may contribute to clinical outcomes.We enrolled 32 patients with advanced GC of diverse subtypes and profiled their TIME using an immune-targeted single-cell profiling strategy, including (i) immune-targeted single-cell RNA sequencing (scRNA-seq, n = 20 patients) and (ii) protein expression profiling by a targeted antibody panel for mass cytometry (CyTOF, n = 12 patients). We also generated matched V(D)J sequencing of T and B cells along CD45+ immunocytes.We find that compared to non-GSRCC, the GSRCC TIME appears to be quiescent where both CD4+ and CD8+ T cells are difficult to be mobilized, which further impairs the proper functions of B cells. CXCL13, mainly produced by Tfh, Th17, and exhausted CD8+ T cells, is a central coordinator of this transformation. We show that CXCL13 expression can predict the response to immune checkpoint blockade in GC patients, which may be related to its effects on tertiary lymphoid structures.Our study provides a comprehensive molecular portrait of immune cell compositions and cell states in advanced GC patients, highlighting adaptive immune irresponsiveness in GSRCC and a mediator role of CXCL13 in TIME. Our targeted single-cell transcriptomic and proteomic profiling represents a powerful approach for TIME-oriented translational research.Copyright © 2023 AGA Institute. Published by Elsevier Inc. All rights reserved.