Neutrophil Collagenase in Sepsis and Ventilator Induced Lung Injury

描述(由申请人提供)：败血症是美国每年约70万人发病和死亡的主要原因。脓毒症患者的急性肺损伤(ALL)很常见，死亡率很高(-40%)。充分和及时的中性粒细胞对感染部位的反应可以限制患者的败血症，但这些细胞的不受控制的积累也可能导致终末器官损害，这是多器官衰竭的主要原因之一，包括中性粒细胞对感染或炎症部位的所有趋化作用在这一过程中是必不可少的。在这项研究中，我们将研究在脓毒症、呼吸机诱导的肺损伤(VILI)以及脓毒症所致的肺损伤与随后的VILI合并的模型中，基质金属蛋白酶-8在中性粒细胞趋化中的中心作用。我们的初步数据表明，基质金属蛋白酶-8限制中性粒细胞对炎症/感染部位的趋化作用。在我们的盲肠结扎和穿孔的脓毒症模型中，基质金属蛋白酶-8的这一特性是有害的，在该模型中，基质金属蛋白酶-8缺乏的小鼠具有显著的生存优势。另一方面，基质金属蛋白酶-8的缺乏导致机械通气小鼠肺组织中性粒细胞的不适当积聚，并导致明显的VILI。该研究提案将作为申请人的培训计划，重点是在临床相关问题的设置方面的基质金属蛋白酶-8生物学，非常适合候选人在成为临床医生-科学家的道路上。该应用程序利用匹兹堡大学医学部和重症监护医学系内可用资源的多样性，为首席研究人员提供独特的培训计划，旨在促进在Steven D.Shapiro博士的指导下成功的研究生涯。该实验方法的独特之处在于，它利用(I)肺外脓毒症、(Ii)呼吸机诱导的肺损伤和(Iii)伴随机械通气在脓毒症相关性ALI中的调节作用的小鼠模型来研究基质金属蛋白酶-8的作用。具体目标包括：1)脓毒症模型中依赖于MMP8的细菌清除机制，2)MMP8在VILI中的作用，以及3)依赖于MMP8的细胞因子失活，包括蛋白质组学方法。这些结果有望在临床相关疾病模型中获得对基质金属蛋白酶-8生物学的基本见解，并可能为开发新的脓毒症和ALI的抗炎治疗策略提供基础。 全身感染和炎症(如脓毒症)导致的急性肺损伤具有很高的死亡风险。在这个方案中，我们将研究一个关键分子，即基质金属蛋白酶-8，在脓毒症小鼠模型中，急性肺损伤，以及使用机械通气可能造成的损伤。

DESCRIPTION (provided by applicant): Sepsis is a major cause of morbidity and mortality occurring in around 700,000 individuals per year in US. Acute lung injury (All) in patients with sepsis is common, and carries a high mortality (-40%). Adequate and timely neutrophil response to the site of infection could limit sepsis in patients, yet uncontrolled accumulation of these cells could also lead to end-organ damage, one of the major reasons for multiple organ failure, including ALL Chemotaxis of neutrophils to the site of infection or inflammation are essential to this process. In this proposal we are going to study the central role of matrix metalloproteinase (MMP)-8 in neutrophil chemotaxis in models of sepsis, ventilator-induced lung injury (VILI) and the combination of sepsis-induced lung injury with subsequent VILI. Our preliminary data suggests that MMP-8 limits the neutrophil chemotaxis into sites of inflammation/infection. This property of MMP-8 is deleterious in our sepsis model of cecal- ligation and puncture, where the MMP-8 deficient mice had a significant survival advantage. On the other hand, the lack of MMP-8 led to inappropriate accumulation of neutrophils in the lung tissues in mice on mechanical ventilation and led to significant VILI. The research proposal will serve as a training program for the applicant with a focus on MMP-8 biology in the setting of clinically relevant questions, a perfect fit for a candidate on the path of becoming a clinician-scientist. This application takes advantage of the diversity of resources available within the Department of Medicine and Critical Care Medicine at the University of Pittsburgh to provide the principal investigator with a unique training program designed to foster a successful research career under the mentorship of Dr. Steven D. Shapiro. The experimental approach is unique in that it utilizes a murine model of (i) extra-pulmonary sepsis, (ii) ventilator-induced lung injury, and (iii) the modulating effects of concomitant mechanical ventilation in the setting of sepsis-related ALI to study the role of MMP-8. Specific aims include: 1) mechanism of MMP-8 dependent bacterial clearance in a sepsis model, 2) role of MMP-8 in VILI, and 3) MMP-8 dependent cytokine inactivation, including proteomic approaches. Results are expected to yield fundamental insights into the MMP-8 biology in clinically relevant disease models and possibly provide the basis for development of novel anti-inflammatory therapeutic strategies for sepsis and ALI. Acute lung injury in the setting of systemic infection and inflammation such as sepsis carries a high risk for mortality. In this proposal, we will study a key molecule, namely matrix metalloproteinase (MMP)-8 in mouse models of sepsis, acute lung injury and the possible injury inflicted by the use of mechanical ventilation.