Advances in microscopy, genetically modified mice, and single-cell RNA sequencing have begun to deconvolute the composition and function of tissue immune niches. Here we discuss the evidence that the adventitia, the outermost layer of larger blood vessels, is a conserved niche and tissue immune outpost for multiple immune cells, including group 2 innate lymphoid cells (ILC2) and subsets of tissue-resident memory T cells, macrophages, and dendritic cells. We also describe the unique non-immune composition at adventitial regions, including fibroblast-like stromal cell subsets, lymphatic and blood endothelial cells, and neurons, and review how immune-stromal crosstalk impacts regional tissue immunity, organ adaptation, and disease.

中文翻译：

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外膜中的免疫前哨：一只脚在海里，一只脚在岸上。

显微镜、转基因小鼠和单细胞 RNA 测序的进展已经开始解卷积组织免疫微环境的组成和功能。在这里，我们讨论的证据表明，外膜是较大血管的最外层，是多种免疫细胞的保守生态位和组织免疫前哨，包括第 2 组先天淋巴细胞 (ILC2) 和组织驻留记忆 T 细胞亚群、巨噬细胞, 和树突状细胞。我们还描述了外膜区域独特的非免疫成分，包括成纤维细胞样基质细胞亚群、淋巴和血液内皮细胞以及神经元，并回顾了免疫基质串扰如何影响区域组织免疫、器官适应和疾病。