Transcriptomic, phenotypical, and functional characterization of human liver sinusoidal CD69+CD4+ T cells

Abstract

Abstract Tissue-resident memory T (TRM) cells are non-circulating T cells that rapidly respond to the local antigen stimulation. Human liver CD8+ T cells have been reported to have phenotypes of TRM and respond to hepatotropic viruses. However, characteristics of human liver CD4+ T cells are still unclear. Here, we examined transcriptomic, phenotypical, and functional characteristics of human liver CD4+ T cells by analyzing liver sinusoidal mononuclear cells (LSMCs) from liver perfusates of healthy donors obtained during liver transplantation. The liver sinusoidal (LS) CD4+ T cell population had a significantly higher frequency of CD69+ cells than the peripheral blood (PB) counterpart. However, CD103 was barely expressed in the both populations. In transcriptomic analysis, LS CD69+CD4+ T cells were distinctly clustered and showed tissue-resident features. In flow cytometry analysis, we found that the LS CD69+CD4+ T cell population had significantly higher frequencies of CXCR6+, LFA-1+, or CD49a+ cells than the PB CD4+ T cell population and the LS CD69−CD4+ T cell population, confirming that LS CD69+CD4+ T cells have tissue-resident phenotypes. Moreover, LS CD69+CD4+ T cells were mostly PD-1+ effector memory cells, which is consistent with the characteristics of TRM cells. In functional analysis following anti-CD3 stimulation, we found that LS CD69+CD4+ T cells had a higher capacity for IFN-γ production than LS CD69− CD4+ T cells. In addition, TH1-associated gene sets were enriched in the LS CD69+CD4+ T cells. In summary, these findings indicate that LS CD69+CD4+ T cells are TRM-like cells with TH1 effector functions. Roles of LS CD69+CD4+ T cells in various liver diseases need to be further elucidated.