The human liver microenvironment shapes the homing and function of CD4⁺T-cell populations

Abstract

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.

Single cell profiling of functionally cured Chronic Hepatitis B patients reveals the emergence of activated innate and an altered adaptive immune response in the intra-hepatic environment

“…2F’ and as described in (24)), suggesting a gain of innate-like function in CD4-CTLs. Additionally, we observed an increase in KLRG1 and CD81 in FC patients indicating antigen exposure of these cells (25) compared to other cluster-defining marker genes ( PRF1, NCR3, TCF7, TNF, IFNG, EOMES ) that remain unchanged between CHB and FC patients (Fig. 2F”).…”

HIV-1 Vpr drives a tissue residency-like phenotype during selective infection of resting memory T cells

“…As expected, there was no upregulation of S1PR1 or KLF2 mRNA by either HIV-1 WT or ΔVpr virus ( Figure S5 I). Vpr also mediated spontaneous production of IFN-γ by infected CD4 + memory T cells ( Figure 3 F), characteristic of T RM cells ( FitzPatrick et al., 2021 ; Wiggins et al., 2021 ). Importantly, Vpr-dependent changes were also observed using tonsil-derived tissue memory T cells as targets for cell-to-cell spread ( Figures 3 G, S5 K, and S5L).…”

“…We are mindful to term these cells “T RM -like” T cells since no single phenotypic marker might faithfully identify a cell as tissue-resident. While differentiation of T RM cells in vitro has been reported previously ( Pallett et al., 2017 ; Wiggins et al., 2021 ), bona fide T RM cells in vivo are defined by their anatomical location in tissues. Future work will be required to determine to what extent HIV-1 infection and/or expression of Vpr alone is able to induce this T RM -like state in vivo and whether HIV-1 infection reprograms resting T cells to adopt a T RM profile and localization in situ .…”

“…Functionally, T RM cells are poised for rapid production of cytokines (IFN-γ, IL-2, and TNF) following antigenic-stimulation ( Christo et al., 2021 ; FitzPatrick et al., 2021 ; Wiggins et al., 2021 ). Notably, we found that HIV-1-induced T RM -like cells produced these cytokines faster and to higher levels following recall stimulation compared with HIV-1-infected CD69 − non-T RM cells ( Figure 2 P) and also showed a greater propensity to produce multiple cytokines per cell ( Figure 2 Q).…”

Intrahepatic activated leukocyte cell adhesion molecule induces CD6highCD4+ T cell infiltration in autoimmune hepatitis

“…Liver microenvironment plays a crucial role in establishing and maintaining phenotypes of infiltrating CD4 + cells (40). Under pathological conditions, injured hepatocytes provide an environment for cytotoxic cells differentiation and proliferation.…”