宿主因素於慢性B型肝炎帶原患者自發性e抗原抗體血清轉換的影響

Abstract

背景: B型肝炎為全球健康的危害，它可以造成急性肝炎，猛爆性肝衰竭，慢性肝炎與其相關的併發症 (包括肝硬化與肝細胞癌等)，全球約有三億五千萬人為慢性B型肝炎帶原者，每年約有一百萬人口因為B型肝炎的併發症而死亡，在慢性B型肝炎病毒長期的感染中，B型肝炎e抗原抗體的血清轉換一般而言代表著患者體內病毒的複製減少，病毒量與肝炎活性的下降，然而人類宿主因素對於自發性B型肝炎e抗原抗體的血清轉換的影響仍然不清楚，因此在本研究中探討宿主賀爾蒙與細胞激素的影響。 研究設計與方法: 我們的研究以前瞻性長期世代追蹤的設計探討在慢性B型肝炎病毒感染的自然史中，影響及預測B型肝炎病毒血清病毒量下降，肝功能指數ALT變化的趨式與自發性e抗原抗體血清轉換的宿主因子(包括男性賀爾蒙與細胞激素)，為釐清宿主的影響，我們在分析時均考量病毒基因型與血清病毒量的影響。 在男性賀爾蒙因素方面我們檢測了早期(10歲)，中期(15歲)與晚期(20歲)青春期男性慢性B型肝炎帶原者血清睪固酮的濃度與病毒量，並同時分析SRD5A2基因多樣性與雄性激素接受子CAG重覆的數目等因子對自發性B型肝炎e抗原抗體的血清轉換的影響。 在細胞激素方面我們檢測了五個Th1與Th2所屬細胞激素基因的十一個細胞激素單一核酸多樣性，分析患者於免疫耐受期，發炎期到非活性期血清細胞激素的濃度與病毒量，並探討對自發性B型肝炎e抗原抗體的血清轉換的影響，同時研究介白質十與十二在肝細胞內與其它細胞激素的關聯性及對病毒precore/core基因於免疫發炎期產生突變的影響。 結果: 在一系列的研究中我們探討宿主雄性賀爾蒙相關因素與細胞激素的基因型及表現型對於慢性B型肝炎病毒感染的影響，並發現較早發生青春期與SRD5A2基因型於男性的慢性帶原者可預測較明顯的血清病毒量下降與與自發性e抗原抗體血清轉換的發生，也觀察到在青春期與慢性B型肝炎的病程中免疫耐受期與發炎期轉化過程的關連性。同時，細胞激素中的介白質十(-1082 G/G基因型)與十二(-10993 C/G 基因型)較高產量的基因型與血清表現型亦為預測e抗原抗體血清轉換的重要免疫因子，於肝臟內介白質十與十二均與丙型干擾素的表現呈現正相關，尤其以介白質十為主要的預測因子，高產量的介白質十基因型更於免疫發炎期預測較高的B型肝炎病毒precore/core基因C2189A的突變率。該突變的發生顯著與血清B型肝炎病毒血清病毒量減少相關。慢性B型肝炎病毒感染的肝臟內丙型干擾素同時預測較高的免疫調節因子PD-1/PD-L1的表現與較低的furin表現。 討論: 本研究為慢性B型肝炎病毒感染的自然史中，對宿主在賀爾蒙與細胞激素的影響提出鮮明的證據。不同的宿主免疫壓力造成不同的病毒突變型態與病程，並可能於自發性e抗原抗體血清轉換的免疫調節機轉中，由細胞破壞途徑(cytolytic pathway)轉換為非細胞破壞途徑(non-cytolytic pathway)的過程中提供了新的資訊。同時也發現furin可能為丙型干擾素抑制B型肝炎病毒之非細胞破壞途徑(non-cytolytic pathway)的方法之一。

Background: Hepatitis B virus (HBV) is a global health hazard, which may cause acutehepatitis, fulminant hepatic failure, chronic hepatitis, liver cirrhosis, and even hepatocellular carcinoma. There are 350 million chronic HBV infected patients in the world, and annually 1 million patients died of complication associated with HBV. During the chronic course of HBV infection, HBeAg seroconversion generally indicates the decrease in viral replication and subsidence of disease activity. However, the role of host factors on the process of spontaneous HBeAg seroconversion is unclear. Thus, we aimed to elucidate the possible roles of hormone and cytokine on the complex immune process. Study Design and Methods: This is a long-term prospective cohort study. To confirm the impacts of hormone, we investigated the serum testosterone levels and HBV viral load at early (10years), middle (15 years), and late (20years) puberty. We also checked the SRD5A2 V89L polymorphism and the CAG repeat number of androgen receptor exon-1. About the roles of cytokines, we checked 11 single nucleotide polymorphism located at 5 Th1 and Th2 cytokine gene (IL-2, IL-4, IL-10, IL-12β, IFN-γ), and the serum cytokine levels and viral load at immune tolerance phase, inflammatory/clearance phase, and post HBeAg-seroconversion inactive phase. We further investigated the association between IL-10 and IL-12 in the liver with HBV infection and the relationship with IFN-γ and possible downstream signals. The impact of different host immune stress (IL-10 genotype) on the mutation pattern of HBV precore/core gene was also done. Results: Earlier onset of puberty and higher SRD5A2 enzyme activity were associated with more viral load decrement during the puberty period (10-20 years) and earlier spontaneous HBeAg seroconversion. IL-10 -1082 G/G genotype and IL-12β C/G genotype were associated with higher baseline IL-10 serum levels and HBcAg inducible IL-12 levels, and both predict earlier onset of spontaneous HBeAg seroconversion. Intrahepatic IL-10 and IL-12βmRNA levels were associated with IFN-γ expression, which associated with lower furin and higher PD-1/PD-L1 expression in subjects with chronic HBV infection at the inflammatory phase. G/G genotype of IL-10 -1082 also associated with higher C2189A mutation rate at the HBV precore/core gene, which is also associated with lower HBV viral load. Discussion: This study provided some new evidence of the impacts of hormone and cytokine on the natural course of chronic HBV infection. We also demonstrated that, different host immune stress may associate with different HBV mutation pattern and clinical outcomes.