%0 Journal Article %A Benjamin G Wiggins %A Laura J Pallett %A Xiaoyan Li %A Scott P Davies %A Oliver E Amin %A Upkar S Gill %A Stephanie Kucykowicz %A Arzoo M Patel %A Konstantinos Aliazis %A Yuxin S Liu %A Gary M Reynolds %A Brian R Davidson %A Amir Gander %A Tu Vinh Luong %A Gideon M Hirschfield %A Patrick T F Kennedy %A Yuehua Huang %A Mala K Maini %A Zania Stamataki %T The human liver microenvironment shapes the homing and function of CD4+ T-cell populations %D 2022 %R 10.1136/gutjnl-2020-323771 %J Gut %P 1399-1411 %V 71 %N 7 %X Objective Tissue-resident memory T cells (TRM) are vital immune sentinels that provide protective immunity. While hepatic CD8+ TRM have been well described, little is known about the location, phenotype and function of CD4+ TRM.Design We used multiparametric flow cytometry, histological assessment and novel human tissue coculture systems to interrogate the ex vivo phenotype, function and generation of the intrahepatic CD4+ T-cell compartment. We also used leukocytes isolated from human leukocyte antigen (HLA)-disparate liver allografts to assess long-term retention.Results Hepatic CD4+ T cells were delineated into three distinct populations based on CD69 expression: CD69−, CD69INT and CD69HI. CD69HICD4+ cells were identified as tissue-resident CD4+ T cells on the basis of their exclusion from the circulation, phenotypical profile (CXCR6+CD49a+S1PR1−PD-1+) and long-term persistence within the pool of donor-derived leukcoocytes in HLA-disparate liver allografts. CD69HICD4+ T cells produced robust type 1 polyfunctional cytokine responses on stimulation. Conversely, CD69INTCD4+ T cells represented a more heterogenous population containing cells with a more activated phenotype, a distinct chemokine receptor profile (CX3CR1+CXCR3+CXCR1+) and a bias towards interleukin-4 production. While CD69INTCD4+ T cells could be found in the circulation and lymph nodes, these cells also formed part of the long-term resident pool, persisting in HLA-mismatched allografts. Notably, frequencies of CD69INTCD4+ T cells correlated with necroinflammatory scores in chronic hepatitis B infection. Finally, we demonstrated that interaction with hepatic epithelia was sufficient to generate CD69INTCD4+ T cells, while additional signals from the liver microenvironment were required to generate liver-resident CD69HICD4+ T cells.Conclusions High and intermediate CD69 expressions mark human hepatic CD4+ TRM and a novel functionally distinct recirculating population, respectively, both shaped by the liver microenvironment to achieve diverse immunosurveillance.Data are available upon reasonable request. %U https://gut.bmj.com/content/gutjnl/71/7/1399.full.pdf