Molecular regulation of immunoproteasome assembly in inflammatory diseases

严重细菌感染是全球死亡率和发病率的主要原因。宿主对感染的异常反应导致破坏性炎症和广泛的组织损伤，导致器官功能障碍和多器官衰竭。在过去的二十年里，革兰氏阴性菌（GNB）对抗生素耐药性的发生率增加与世界上死亡率增加和重大公共卫生问题有关。不可控的炎症是GNB肺炎引起的急性呼吸窘迫综合征（ARDS）的一个重要特征，ARDS是严重脓毒症的一种毁灭性并发症。由于没有特定的治疗方法，目前的研究重点是确定新的药物靶点，以减少促炎反应。免疫系统中蛋白质稳态的失调是全身性炎症的发病机制之一。蛋白质降解主要由蛋白酶体控制。最近，一个特定的亚组的蛋白酶体称为免疫蛋白酶体已被确定发挥关键作用的炎症反应，包括抗原呈递。在前期研究中，我们发现内毒素可增加免疫蛋白酶体结构组装，但免疫蛋白酶体结构组装的分子调控及其在ARDS发病机制中的作用尚未揭示。我们假设去泛素化酶USP14决定免疫蛋白酶体的结构组装，并且免疫蛋白酶体的抑制减少NLPR3炎性体活化和GNB诱导的炎症。我们将确定USP14激活调节LPS诱导的免疫蛋白酶体结构组装的分子机制。接下来，我们将确定PKCδ对USP14的磷酸化如何促进免疫蛋白酶体结构组装和GNB诱导的肺损伤和脓毒症的严重程度的潜在机制。我们将使用最先进的分子方法，人类样本和临床前动物模型。这些数据将为通过调节诱导型免疫蛋白酶体结构组装来调节促炎反应的分子机制进展奠定基础，这与急性细菌感染的发病机制有关。

Severe bacterial infections are a major cause of global mortality and morbidity. An aberrant host response to infection leads to destructive inflammation and extensive tissue damage, resulting in organ dysfunction and multi- organ failure. An increasing incidence of gram-negative bacteria (GNB) resistance to antibiotics has been associated with increased mortality and significant public health problems in the world over last two decades. Uncontrollable inflammation is a critical feature of GNB pneumonia-induced acute respiratory distress syndrome (ARDS), a devastating complication of severe sepsis. Since there are no specific treatment available, current research focuses on identifying new drug targets to diminish pro-inflammatory responses. Dysfunction of protein homeostasis in immune system has been known to contribute to the pathogenesis of systemic inflammation. Protein degradation is mainly controlled by the proteasome. Recently, a specific subgroup of the proteasome called the immunoproteasome has been identified to play a critical role in inflammatory responses including antigen presentation. In the preliminary study, we found that endotoxin increases immunoproteasome structural assembly; however, the molecular regulation of immunoproteasome structural assembly and its role in the pathogenesis of ARDS have not been revealed. We hypothesize that deubiquitinase USP14 determines immunoproteasome structural assembly, and that inhibition of the immunoproteasome diminishes NLPR3 inflammasome activation and GNB-induced inflammation. We will determine molecular mechanisms by which USP14 activation regulates LPS-induced immunoproteasome structural assembly. Next, we will determine the mechanisms underlying how the phosphorylation of USP14 by PKCδ promotes immunoproteasome structural assembly and severity of GNB-induced lung injury and sepsis. We will use state-of the art molecular approaches, human samples, and preclinical animal models. The data will lay the foundation for a significant mechanistic advancement regarding the molecular regulation of the pro-inflammatory responses through the modulation of the inducible immunoproteasome structural assembly, which are implicated in the pathogenesis of acute bacterial infection.