高迁移率族蛋白1在人腺病毒55型感染肺炎的过度炎症反应中的作用和机制研究

Human adenovirus type 55 (HAdV-55) was identified by whole genome sequencing recently, which was recombined by HAdV-11 and HAdV-14. HAdV-55 is more contagious and most patient infected by HAdV-55 would progress to pneumonia and some of them would progress to acute respiratory distress syndrome (ARDS) or respiratory failure. Recent research reported that there were no more difference between the sequences of HAdV-55 isolated from patients with minor symptoms or heavy symptoms. The excess inflammation responses were considered as the main cause of disease progression and death. Our previous publication reported the immune system of patients with heavy symptoms was more activated, but the precise mechanism was not clear by now. High mobility group box-1 protein (HMGB1) was a member of danger/damage associated molecules pattern (DAMP) molecules, it’s excess secretion could lead to abnormal immune activation which played a pivotal roles in many inflammation associated diseases, such as autoimmune diseases, ARDS, sepsis et, al. Some recent studies demonstrated that the injection of HMGB1 could lead to pneumonia in mice and excess HMGB1 could aggravate the inflammation induced by influenza virus infection (H5N1 and H1N1), and its concentration in serum of patients could predict the outcome of ARDS independently. Our primary study showed that HAdV-55 infection could promote the release of HMGB1 from human respiratory tract epithelial cell lines. And also, the serum concentration of HMGB1 in patients with pneumonia was higher. So, we hypothesized that HMGB1 was involved in the inflammation mechanism of HAdV-55 infection. We proposed to investigate the relationship between serum HMGB1 and the adenoviral pneumonia caused by HAdV-55 infection and to explore if HMGB1 could enhance the immune response to HAdV-55. This study would provide more evidence to the research of inflammation mechanism of HAdV-55 infection and give more information for the research of therapeutic target of HAdV-55 infection with excess inflammation.

人腺病毒55型（HAdV-55）传染性强，肺炎发生率及严重程度均较高，重症患者可发生急性呼吸窘迫综合征（ARDS）和死亡。我们研究发现重症感染者免疫激活水平升高，提示过度炎症反应在HAdV-55感染病情加重过程中起到重要作用，但相关炎症机制尚不完全清楚。高迁移率族蛋白1（HMGB1）在病理状况下促进免疫过度激活使患者病情加重，其参与ARDS、甲型流感病毒感染肺炎等多种炎症相关疾病的发生，可作为ARDS的死亡预测指标。本研究预实验结果表明HAdV-55感染可诱导HMGB1释放，且其在HAdV-55感染肺炎患者中表达水平升高，据此推测HMGB1在HAdV-55感染肺炎的发展过程中起到促进炎症反应的作用。本课题拟研究HMGB1与HAdV-55感染肺炎的关系，探索HMGB1在HAdV-55诱导免疫过度激活中的作用，为明确HAdV-55感染的过度炎症反应机制和发现重症感染者新的治疗靶点提供实验依据。

人腺病毒传染性强，人群普遍易感。呼吸道腺病毒感染者可发生腺病毒肺炎，重症患者可发生急性呼吸窘迫综合征（ARDS）、弥散性感染甚至死亡。过度炎症反应是腺病毒感染者病情加重的重要因素之一，但目前相关炎症机制尚不完全清楚。本课题首先采用了转录组学研究对腺病毒感染患者炎症反应特征和机制进行了相关研究；然后对腺病毒感染者外周血中HMGB1及其相关分子的表达及其与患者病情的关系进行了探讨。.本课题的研究发现，腺病毒肺炎的患者的IL-1alpha、IL-18、IL-36b，IL-17以及TNFSF10、TNFSF11、TNFSF14、TNFSF15等多种炎症因子基因的表达水平均显著高于其他患者及健康对照者。进而本研究通过腺病毒感染细胞模型，进一步研究了细胞代谢组的变化，发现与炎症反应相关的神经鞘磷脂信号通路发生显著的改变。为了阐明HMGB1在腺病毒感染炎症反应中的作用，本研究采用腺病毒感染细胞模型，发现腺病毒感染可促进HMGB1的释放。进而，我们对一组7型腺病毒感染者外周血HMGB1、sRAGE（HMGB1的可溶性受体，其内源性阻断分子）以及MMP9（促进sRAGE生成的关键蛋白酶之一）的表达情况进行了研究。结果发现腺病毒感染可诱导外周血HMGB1在患者发病后1-3天时表达升高，而sRAGE的表达水平则在感染后显著降低。进一步的分析发现，HMGB1的浓度在肺炎与非肺炎患者间的差异不显著，但sRAGE以及MMP9在肺炎患者的表达水平显著低于非肺炎患者。进而，研究发现外源性给予sRAGE可降低腺病毒感染诱导的呼吸道上皮细胞炎症因子TNF-alpha的分泌水平。.本课题研究提示腺病毒感染可促进患者炎症因子表达水平，促进炎症相关通路的激活。本研究还显示腺病毒感染可提高HMGB1的表达水平，降低MMP9和sRAGE的表达，提高机体炎症反应水平，促进腺病毒肺炎的发生。HMGB1及其相关分子等可作为腺病毒肺炎治疗的新靶点进一步研究。