Natural Killer Cells Induce CD8+ T Cell Dysfunction via Galectin-9/TIM-3 in Chronic Hepatitis B Virus Infection
Siyu Liu, Chang Xu, Fan Yang, Lu Zong, Yizu Qin, Yufeng Gao, Qian Su, Tuantuan Li, Ye Li, Yuanhong Xu, Meijuan Zheng
Abstract
The antiviral response of natural killer (NK) cells and CD8 + T cells is weak in patients with chronic hepatitis B (CHB) infection. However, the specific characteristics of these cells and the association between NK cells and CD8 + T cell dysfunction is not well known. In this study, higher galectin-9 (Gal-9) expression was observed in circulating NK cells from CHB patients than from healthy controls and was found to contribute to NK cell dysfunction. In addition, circulating CD8 + T cells showed obvious dysfunction and overexpressed TIM-3, the natural receptor of Gal-9, during active CHB infection. Gal-9 + and Gal-9 - NK cells from active CHB patients were sorted and cocultured with autologous CD8 + T cells. The proportion of tetramer + CD8 + T cells and the cytokines production of CD8 + T cells were lower after cocultivation with Gal-9 + than with Gal-9 - NK cells. We showed that in vitro depletion of NK cells increased circulating hepatitis B virus (HBV)-specific CD8 + T cell responses in patients with active CHB infection. Because Gal-9 is increased in the serum of CHB patients, CD8 + T cells were sorted and cultured with exogenous Gal-9, resulting in lower IFN-γ, TNF-α, CD107a, and granzyme B levels, decreased expression of the activation receptor CD69, increased expression of TIM-3, and a high percentage of early apoptotic CD8 + T cells. Blocking Gal-9 or TIM-3 in vitro in a culture of peripheral blood mononuclear cells (PBMCs) stimulated with HBV peptide from active CHB patients restored CD8 + T cell function. However, blocking Gal-9 in vitro after removal of NK cells from PBMCs did not rescue CD8 + T cells exhaustion. Furthermore, NK and CD8 + T cells from active CHB patients were sorted and cocultured in vitro , and the exhaustion of CD8 + T cells were alleviated after blocking Gal-9 or TIM-3. In summary, overexpression of Gal-9 on NK cells, which interacts with TIM-3 + CD8 + T cells and likely contributes to antiviral CD8 + T cell dysfunction, may be a potential target for the treatment of CHB patients.