Therapeutic Use of High Molecular Weight Hyaluronic Acid in Acute Lung Injury Following Severe Bacterial Pneumonia or Sepsis

摘要 细菌性肺炎合并或不合并败血症是导致急性呼吸衰竭的最常见原因之一。 导致急性呼吸窘迫综合征(ARDS)的危重患者。尽管有改进，但 在支持性护理和适当使用抗生素的情况下，ARDS的死亡率仍高达40%。因此，新的 需要创新的治疗方法。透明质酸或透明质酸(HA)通常是以高水平合成的 分子量(HMW)非硫酸糖胺聚糖，是细胞外基质的主要成分 对维持肺泡气血屏障的正常结构至关重要。在多发性肺部疾病中 包括急性肺损伤(ALI)、哮喘、COPD或肺动脉高压，HA通过 透明质酸酶、活性氧和氮物种以及炎症介质。降解产物， 低分子(LMW)HA，具有炎症特性，可降低内皮细胞屏障 发挥炎症介质的作用并诱导其表达。在ARDS患者中，肺泡水平升高 低分子透明质酸与肺损伤评分增加有关。令人惊讶的是，HMW HA具有生物 与LMW HA相反的性能主要是由于其分子大小。因此，调查人员已经 以前研究了外源性HMW HA在肺部疾病中的治疗作用。尽管 前景看好的临床前数据，使用HMW HA治疗ARDS的一个主要限制因素仍然是 对严重感染患者给予免疫抑制治疗。在目前的提案中，我们假设 HMW HA的应用将进一步恢复重症细菌性肺炎和/或ALI的主要指标 脓毒症部分通过增加(1)抗菌活性和(2)通过中和炎性 细胞外小泡(EV)在ALI渗出期释放。在目标1中，我们将确定 HMW-HA对已建立的小鼠重症细菌性肺炎模型的治疗作用 我们推测，HMW HA治疗效果的潜在机制将是由于 先天免疫细胞的抗菌活性，渗出期早期释放的炎性肠病毒的结合 通过修复血管内皮细胞的糖帽层。为了让临床前的小动物 更具临床相关性的研究，在目标2中，我们将确定HMW HA给药的疗效 严重的大肠杆菌或铜绿假单胞菌致人肺损伤的体外实验 肺炎。为了克服人体肺灌流的一些局限性，如缺乏肝脏 和脾是HA降解的主要部位，在目标3中，我们将确定 HMW-HA在烟雾吸入致感染性休克绵羊模型中的应用 铜绿假单胞菌肺炎。如果成功，HMW HA，一种廉价的非免疫原性生物 已经用于其他无菌炎症性肺部疾病的临床试验，如COPD，可能会被证明 是治疗ARDS和/或脓毒症的可行方法。

ABSTRACT Bacterial pneumonia with or without sepsis is among the most common cause of acute respiratory failure in critically ill patients leading to acute respiratory distress syndrome (ARDS). Despite improvements in supportive care and appropriate antibiotic use, mortality from ARDS remains as high as 40%. Therefore, new innovative therapies are needed. Hyaluronan or hyaluronic acid (HA) is normally synthesized as a high molecular weight (HMW) nonsulfated glycosaminoglycan and is a chief component of the extracellular matrix and critical for maintaining the normal structure of alveolar air-blood barrier. In multiple pulmonary disorders including acute lung injury (ALI), asthma, COPD or pulmonary hypertension, HA undergoes degradation by hyaluronidases, reactive oxygen and nitrogen species and inflammatory mediators. The degradation products, low molecular weight (LMW) HA, has inflammatory properties and can decrease endothelial cell barrier function and induce expression of inflammatory mediators. In patients with ARDS, elevated levels of alveolar LMW HA have been associated with increased Lung Injury Score. Surprisingly, HMW HA has biologic properties opposite of LMW HA based primarily due to its molecular size. Therefore, investigators have previously studied the therapeutic use of exogenous administration of HMW HA in lung disorders. Despite promising pre-clinical data, a major limitation for the use of HMW HA for ARDS has remained the concern of giving an immunosuppressive therapy in patients with severe infection. In the current proposal, we hypothesize that administration of HMW HA will further restore major indices of ALI from severe bacterial pneumonia and/or sepsis in part through increased (1) antimicrobial activity and (2) through neutralization of inflammatory extracellular vesicles (EV) released during the exudative phase of ALI. In Aim 1, we will determine the therapeutic effects of HMW HA administration in established mouse models of severe bacterial pneumonia. We hypothesize that the mechanisms underlying the therapeutic effects of HMW HA will be due to increased antimicrobial activity of innate immune cells, binding of inflammatory EVs released early in the exudative phase of ALI, and through the restoration of the endothelial glycocalyx layer. To make the small pre-clinical animal studies more clinically relevant, in Aim 2, we will determine the therapeutic effects of HMW HA administration in an ex vivo perfused human lung injured with severe E.coli or Pseudomonas aeruginosa bacterial pneumonia. And to overcome some of the limitations of the perfused human lung such as a lack of the liver and spleen which are the major sites of HA degradation, in Aim 3, we will determine the therapeutic effects of HMW HA administration in a well-established ovine model of septic shock induced by smoke inhalation and Pseudomonas aeruginosa pneumonia. If successful, HMW HA, an inexpensive, non-immunogenic biologic already in use in clinical trials for other sterile inflammatory pulmonary disorders such as COPD, may prove to be a viable therapy for ARDS and/or sepsis.