Neutrophil Collagenase in Sepsis and Ventilator Induced Lung Injury

描述（由申请人提供）：脓毒症是美国每年约70万人发病和死亡的主要原因。脓毒症患者中的急性肺损伤（ALL）是常见的，并且具有高死亡率（~ 40%）。中性粒细胞对感染部位的充分和及时的反应可以限制患者的脓毒症，但这些细胞的不受控制的积累也可能导致终末器官损伤，这是多器官衰竭的主要原因之一，包括ALL中性粒细胞对感染或炎症部位的趋化性对这一过程至关重要。本研究拟探讨基质金属蛋白酶（MMP）-8在脓毒症、呼吸机诱导的肺损伤（VILI）及脓毒症诱导的肺损伤合并VILI模型中中性粒细胞趋化性中的作用。我们的初步数据表明，MMP-8限制中性粒细胞趋化性进入炎症/感染部位。MMP-8的这种性质在我们的盲肠结扎和穿孔的脓毒症模型中是有害的，其中MMP-8缺陷小鼠具有显著的存活优势。另一方面，MMP-8的缺乏导致中性粒细胞在机械通气小鼠肺组织中的不适当的积聚，并导致显著的VILI。该研究提案将作为申请人的培训计划，重点是MMP-8生物学在临床相关问题的设置，非常适合成为临床科学家的候选人。该应用程序利用匹兹堡大学医学和重症监护医学系内可用资源的多样性，为主要研究者提供独特的培训计划，旨在促进Steven D博士指导下的成功研究生涯。夏皮罗该实验方法的独特之处在于，它利用了（i）肺外脓毒症、（ii）呼吸机诱导的肺损伤和（iii）脓毒症相关ALI背景下伴随机械通气的调节作用的小鼠模型来研究MMP-8的作用。具体目标包括：1）脓毒症模型中MMP-8依赖性细菌清除的机制，2）MMP-8在VILI中的作用，和3）MMP-8依赖性细胞因子失活，包括蛋白质组学方法。这些结果有望为临床相关疾病模型中MMP-8生物学提供基本见解，并可能为脓毒症和ALI的新型抗炎治疗策略的开发提供基础。 在全身感染和炎症如败血症的情况下，急性肺损伤具有高死亡风险。本课题主要研究一个关键分子--基质金属蛋白酶（MMP）-8在脓毒症、急性肺损伤及机械通气可能造成的损伤小鼠模型中的表达。

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.