Table_3_Involvement of Innate Immune Receptors in the Resolution of Acute Hepatitis B in Woodchucks.docx

The antiviral property of small agonist compounds activating pattern recognition receptors (PRRs), including toll-like and RIG-I receptors, have been preclinically evaluated and are currently tested in clinical trials against chronic hepatitis B (CHB). The involvement of other PRRs in modulating hepatitis B virus infection is less known. Thus, woodchucks with resolving acute hepatitis B (AHB) after infection with woodchuck hepatitis virus (WHV) were characterized as animals with normal or delayed resolution based on their kinetics of viremia and antigenemia, and the presence and expression of various PRRs were determined in both outcomes. While PRR expression was unchanged immediately after infection, most receptors were strongly upregulated during resolution in liver but not in blood. Besides well-known PRRs, including TLR7/8/9 and RIG-I, other less-characterized receptors, such as IFI16, ZBP1/DAI, AIM2, and NLRP3, displayed comparable or even higher expression. Compared to normal resolution, a 3–4-week lag in peak receptor expression and WHV-specific B- and T-cell responses were noted during delayed resolution. This suggested that PRR upregulation in woodchuck liver occurs when the mounting WHV replication reaches a certain level, and that multiple receptors are involved in the subsequent induction of antiviral immune responses. Liver enzyme elevations occurred early during normal resolution, indicating a faster induction of cytolytic mechanisms than in delayed resolution, and correlated with an increased expression of NK-cell and CD8 markers and cytolytic effector molecules. The peak liver enzyme level, however, was lower during delayed resolution, but hepatic inflammation was more pronounced and associated with a higher expression of cytolytic markers. Further comparison of PRR expression revealed that most receptors were significantly reduced in woodchucks with established and progressing CHB, and several RNA sensors more so than DNA sensors. This correlated with a lower expression of receptor adaptor and effector molecules, suggesting that persistent, high-level WHV replication interferes with PRR activation and is associated with a diminished antiviral immunity based on the reduced expression of immune cell markers, and absent WHV-specific B- and T-cell responses. Overall, the differential expression of PRRs during resolution and persistence of WHV infection emphasizes their importance in the ultimate viral control during AHB that is impaired during CHB.

小激动剂化合物激活模式识别受体（PRRs），包括TLR样受体和RIG-I受体，其抗病毒活性已在临床前研究中得到评估，目前正用于治疗慢性乙型肝炎（CHB）的临床试验中。关于其他PRRs在调节乙型肝炎病毒感染中的作用了解较少。因此，感染土拨鼠肝炎病毒（WHV）后急性乙型肝炎（AHB）缓解的土拨鼠被定义为具有正常或延迟缓解的动物，这基于其病毒血症和抗原血症的动力学，以及在不同结果中各种PRRs的存在和表达。尽管PRRs表达在感染后立即未发生变化，但在肝脏缓解过程中，大多数受体在肝脏而非血液中表现出强烈的上调。除了已知的PRRs，如TLR7/8/9和RIG-I，其他较少描述的受体，如IFI16、ZBP1/DAI、AIM2和NLRP3，也显示出相似甚至更高的表达。与正常缓解相比，延迟缓解期间峰值受体表达和WHV特异性B细胞和T细胞反应滞后3-4周。这表明PRRs在土拨鼠肝脏中的上调发生在WHV复制积累达到一定水平时，并且多个受体参与了随后抗病毒免疫反应的诱导。在正常缓解过程中，肝脏酶水平升高较早，表明细胞毒性机制的诱导速度快于延迟缓解，这与自然杀伤细胞和CD8标记物以及细胞毒性效应分子的表达增加相关。然而，在延迟缓解期间，峰值肝脏酶水平较低，但肝炎症更为明显，并与细胞毒性标记物的较高表达相关。进一步比较PRRs表达发现，在已建立和进展的CHB土拨鼠中，大多数受体显著减少，RNA传感器比DNA传感器减少得更多。这与受体适配子和效应分子表达的降低相关，表明持续的、高水平的WHV复制干扰了PRRs的激活，并与基于免疫细胞标记物表达减少以及WHV特异性B细胞和T细胞反应缺失的抗病毒免疫力的降低相关。总的来说，PRRs在缓解和WHV感染持续过程中的不同表达突出了它们在AHB最终病毒控制中的重要性，而这种控制能力在CHB期间受到损害。