慢性B型肝炎小鼠動物模式共抑制性受體所誘發CD8 + T細胞耗竭之免疫代謝功能失調之研究

Abstract

B型肝炎病毒(Hepatitis B virus)是一種雙股DNA病毒，世界上大約兩億五千七百萬人處於B型肝炎感染當中。大多數成人感染B型肝炎之後會康復，但是大約5%~10%的比例會無法完全清除HBV病毒的感染，形成慢性感染，並且為罹患肝硬化或是肝癌的高危險群，然而現行已經有安全且有保護效力的疫苗存在可以預防B型肝炎，卻還沒有能有效清除已感染B型肝炎病人病毒的醫療方法。從先前的研究中發現，在HBV慢性感染小鼠動物模式之下，可以分析出表現PD-1(Programmed Death 1)、TIM-3(T-cell immunoglobulin and mucin-domain containing-3)等co-inhibitory受器的肝內CD8+ T細胞族群，並且具有葡萄糖代謝作用功能失調的現象，而之後在PD-1基因剔除的LCMV慢性感染小鼠研究中顯示葡萄糖代謝作用功能可以被部分回復，顯示出PD-1影響了葡萄糖代謝功能的作用，成為發展至後期的exhaustion現象的關鍵，而在小鼠癌症動物模式當中，也發現了co-inhibitory受器PD-1、TIM-3表現的程度、數量與粒腺體質量下降和葡萄糖的攝取呈正相關。然而是否共抑制性受體會影響粒線體功能仍然不清楚。 在我們實驗室先前的研究當中，對於HBV慢性感染小鼠處理anti-PD-1抗體可以加強小鼠對於HBV的清除能力，然而無法完全清除，顯示可能透過其它途徑影響了清除病毒的能力。在我們的結果顯示，HBV慢性感染小鼠中，肝內淋巴細胞CD8+ T細胞表現PD-1、TIM-3表面受器，並且表現出粒線體呼吸作用功能失調的現象，體外處理HBV慢性感染小鼠CD8+ T細胞抗PD-1、Tim-3抗體或是粒線體抗氧化劑回復CD8+ T細胞粒線體膜電位以及IFNγ的產生量。綜上所述，HBV慢性感染中共抑制性受體的表現與CD8+ T細胞粒線體呼吸作用失調現象關聯，影響T細胞的細胞激素的分泌，並且透過阻斷PD-1以及Tim-3或者是處理粒線體抗氧化劑得以回復肝內淋巴細胞CD8+ T細胞粒線體膜電位。顯示出在B型肝炎病毒感染中所造成T細胞衰竭的現象可能涉及細胞能量代謝的異常，經由免疫代謝的調節可能可提升這些T細胞的功能，並作為治療的一個方向。

Hepatitis B virus is a double-stranded DNA virus. About 257 million people in the world are infected with hepatitis B virus. Most adults recover from hepatitis B infection, but approximately 5% to 10% of the population will not completely eliminate HBV infection, develop chronic infections, and are at high risk of cirrhosis or liver cancer. However, there are currently safe and protective vaccines can prevent hepatitis B, but it has not yet been able to effectively remove the virus from infected patients with hepatitis B. From previous studies, it has been found that PD-1 (Programmed Death 1) and TIM-3 (T-cell immunoglobulin and mucin-domain containing-3) can be detected under the HBV chronic infected mouse animal model, and displayed dysfunctional glucose metabolism. Subsequent studies in PD-1 knockout mice challenged with LCMV have shown that glucose metabolism of CD8+ T cells can be partially restored compared to wildtype LCMV infected mice, indicating PD -1 affects the function of glucose metabolism and becomes the key to the development of exhaustion in the later period. In mouse cancer animal models, the degree, number, and extent of expression of co-inhibitory receptors PD-1 and TIM-3 have also been found that positively correlated with decreased mitochondrial mass and rate of glucose uptake. However, whether co-inhibitory receptors affect mitochondrial function is still unclear. In previous studies in our laboratory, treatment of anti-PD-1 antibodies in mice chronically infected with HBV enhanced the ability of mice to remove HBV, but it could not be completely eliminated, indicating that the ability to eliminate the virus may be affected by other pathways. Our results show that in chronically HBV infected mice, intrahepatic CD8+ T cells expressed PD-1, Tim-3 surface co-inhibitory receptors and displayed dysfunctional mitochondrial function. In vitro treating CD8+ T cells from HBV chronic infected mice with anti-PD-1, anti-Tim-3 or antioxidant can increase CD8+ T cells mitochondrial membrane potential and IFNγ production. In summary, the expression of co-inhibitory receptors in chronic HBV infected mice is associated with the dysregulation of mitochondrial function and cytokine production in CD8+ T cells and through blocking PD-1 and Tim-3 or treating mitochondrial antioxidant can partially restore T cell response. It has been shown that the phenomenon of sputum cell exhaustion caused by hepatitis B virus infection may involve in cellular energy metabolism, and regulation of immune metabolism may enhance the function of these sputum cells and serve as a direction of treatment.