Background & Aims: Tissue-resident memory T cells (TRM) are important immune sentinels that provide efficient in situ immunity. Liver-resident CD8+ TRM have been previously described, and contribute to viral control in persistent hepatotropic infections. However, little is known regarding liver CD4+ TRM cells. Here we profiled resident and non-resident intrahepatic CD4+ T cell subsets, assessing their phenotype, function, differential generation requirements and roles in hepatotropic infection. Methods: Liver tissue was obtained from 173 subjects with (n=109) or without (n=64) hepatic pathology. Multiparametric flow cytometry and immunofluorescence imaging examined T cell phenotype, functionality and location. Liver T cell function was determined after stimulation with anti-CD3/CD28 and PMA/Ionomycin. Co-cultures of blood-derived lymphocytes with hepatocyte cell lines, primary biliary epithelial cells, and precision-cut autologous liver slices were used to investigate the acquisition of liver-resident phenotypes. Results: CD69 expression delineated two distinct subsets in the human liver. CD69HI cells were identified as CD4+ TRM due to exclusion from the circulation, a residency-associated phenotype (CXCR6+CD49a+S1PR1-PD-1+), restriction to specific liver niches, and ability to produce robust type-1 multifunctional cytokine responses. Conversely, CD69INT were an activated T cell population also found in the peripheral circulation, with a distinct homing profile (CX3CR1+CXCR3+CXCR1+), and a bias towards IL-4 production. Frequencies of CD69INT cells correlated with the degree of fibrosis in chronic hepatitis B virus infection. Interaction with hepatic epithelia was sufficient to generate CD69INT cells, while additional signals from the liver microenvironment were required to generate liver-resident CD69HI cells. Conclusions: Intermediate and high CD69 expression demarcates two discrete intrahepatic CD4+ T cell subsets with distinct developmental and functional profiles.

中文翻译：

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人类肝脏微环境影响CD4 + T细胞群体的归巢和功能

背景与目的：组织驻留记忆T细胞（TRM）是重要的免疫哨兵，可提供有效的原位免疫。先前已经描述了肝脏驻留CD8 + TRM，它有助于持续性肝病感染的病毒控制。但是，关于肝脏CD4 + TRM细胞知之甚少。在这里，我们分析了常驻和非常驻肝内CD4 + T细胞亚群，评估了它们的表型，功能，差异生成要求和在肝细胞感染中的作用。方法：从173名有（n = 109）或没有（n = 64）肝病理的受试者中获取肝组织。多参数流式细胞仪和免疫荧光成像检查了T细胞的表型，功能和位置。用抗CD3 / CD28和PMA /伊诺霉素刺激后测定肝T细胞功能。血液来源的淋巴细胞与肝细胞系，原发性胆管上皮细胞和精确切割的自体肝切片的共培养用于研究肝驻留表型的获取。结果：CD69表达描绘了人类肝脏中两个不同的亚群。由于从循环中排除，与居住相关的表型（CXCR6 + CD49a + S1PR1-PD-1 +），对特定肝liver的限制以及产生强大的1型多功能细胞因子反应的能力，CD69HI细胞被鉴定为CD4 + TRM。相反，CD69INT是一种在外周循环中也发现的活化的T细胞群体，具有独特的归巢模式（CX3CR1 + CXCR3 + CXCR1 +），并且对IL-4的产生产生偏向。CD69INT细胞的频率与慢性乙型肝炎病毒感染中的纤维化程度相关。与肝上皮的相互作用足以产生CD69INT细胞，而从肝脏微环境产生的其他信号则需要产生肝脏驻留CD69HI细胞。结论：中度和高表达CD69区分了两个离散的肝内CD4 + T细胞亚群，具有不同的发育和功能特征。