Date Published: April 18, 2019
Publisher: Public Library of Science
Author(s): Kyong-Mi Chang, Daniel Traum, Jang-June Park, Suzanne Ho, Keisuke Ojiro, David K. Wong, Abdus S. Wahed, Norah A. Terrault, Mandana Khalili, Richard K. Sterling, Harry L. A. Janssen, Margaret C. Shuhart, Daryl T. Lau, Lewis R. Roberts, Geoffrey S. Johnson, David E. Kaplan, Michael R. Betts, William M. Lee, Anna S. F. Lok, Christopher M. Walker.
Hepatitis B virus (HBV) persists with global and virus-specific T-cell dysfunction, without T-cell based correlates of outcomes. To determine if γδT-cells are altered in HBV infection relative to clinical status, we examined the frequency, phenotype and function of peripheral blood Vδ1+ and Vδ2+γδT-cells by multi-parameter cytometry in a clinically diverse North American cohort of chronic hepatitis B (CHB), acute hepatitis B (AHB) and uninfected control subjects. We show that circulating γδT-cells were comprised predominantly of CD3hiCD4- Vδ2+γδT-cells with frequencies that were 2–3 fold higher among Asian than non-Asian Americans and inversely correlated with age, but without differences between CHB, AHB and control subjects. However, compared to control subjects, CHB was associated with increased TbethiEomesdim phenotype in Vδ2+γδT-cells whereas AHB was associated with increased TbethiEomesdim phenotype in Vδ1+γδT-cells, with significant correlations between Tbet/Eomes expression in γδT-cells with their expression of NK and T-cell activation and regulatory markers. As for effector functions, IFNγ/TNF responses to phosphoantigens or PMA/Ionomycin in Vδ2+γδT-cells were weaker in AHB but preserved in CHB, without significant differences for Vδ1+γδT-cells. Furthermore, early IFNγ/TNF responses in Vδ2+ γδT-cells to brief PMA/Ionomycin stimulation correlated inversely with serum ALT but not HBV DNA. Accordingly, IFNγ/TNF responses in Vδ2+γδT-cells were weaker in patients with CHB with hepatitis flare compared to those without hepatitis flares, and this functional deficit persisted beyond clinical resolution of CHB flare. We conclude that circulating γδT-cells show distinct activation and differentiatiation in acute and chronic HBV infection as part of lymphoid stress surveillance with potential role in clinical outcomes.
Hepatitis B virus (HBV) is an important human pathogen with a global impact in morbidity and mortality. As HBV is generally non-cytopathic, liver disease pathogenesis is largely immune-mediated with rapid progression to cirrhosis and cancer in some and minimal disease progression in others [1–3]. A critical role for conventional T-cells in viral clearance and liver disease has been shown in animal models and inferred in patients [4–9]. However, in patients with chronic hepatitis B (CHB), both HBV-specific and global T-cells are functionally suppressed due to continued antigenic stimulation, inflammation and the induction of multiple regulatory pathways [4–12]. Furthermore, there are no distinct T-cell based immune signatures for the dynamic clinical and virological phases of CHB . These findings also raised the possiblity for alternate mechanisms beyond conventional T-cells in CHB pathogenesis.
While T-cells play a critical role in disease pathogenesis and viral clearance in acute HBV infection, their role in chronic HBV infection is less clear due to functional impairment with the induction of multiple immune regulatory pathways [4–12]. As γδT-cells are non-conventional T-cells that participate in lymphoid stress surveillance [29, 30] and microbial pathogenesis , we asked if γδT-cells contribute to HBV pathogenesis. To this end, we examined the frequency, phenotype and effector function of circulating γδT-cells in a North American cohort of HBV-infected and uninfected subjects. Our findings show that γδT-cells are preserved in circulating frequency regardless of HBV infection, with CD3hiCD4- Vδ2+ γδT-cells as the predominant subset. We further show distinct phenotypic and functional characteristics of γδT-cells in acute and chronic HBV infection with potential pathogenetic relevance.