降钙素基因相关肽在脂多糖诱导幼鼠急性肺损伤中的作用及其信号转导机制

Acute lung injury (ALI) is a common critical illness. Many diseases such as H1N1 influenza, hand, foot and mouth disease, trauma and shock would cause ALI, which further develops into ARDS with a mortality rate up to 40% ~ 70%. The pathogensis is unclear at present, but expert consensuses are that excessive inflammation response in lung contributes to ALI. Calcitonin gene-related peptide (CGRP) is an important neurotransmitter released by the nerve endings. Latest studies show it has powerful anti-inflammatory effects and functions in tissue repairing. Our study is designed to employs lung epithelial cell lines and young rats as experimental subjects to establish cell and animal models of ALI induced by lipopolysaccharide (LPS). Following CGRP intervention (exogenous CGRP, plasmid transfection and siRNA), we detect the changes in CGRP secretion, levels of anti-inflammatory and proinflammatory cytokines, pathological change of lung tissue, aquaporins and signal molecules, etc, to comprehensively elucidate the roles and its mechanisms of CGRP in LPS-induced ALI. This research is expected to demonstrate its anti-inflammatory effect and rehabilitation-promoted function and hopeful to bring new sights on the prevention and control of ALI/ARDS. For the study involves many disciplines such as respirology, critical care medicine and pediatrics, the results will have important impacts on prevention and treatment of ALI/ARDS and basic application researches related to other critical illnesses.

急性肺损伤（ALI）是一种常见的危重病。各种疾病如甲流、手足口病、创伤、休克等最后都可能引起ALI，并发展至ARDS，死亡率可达40％～70％。其发病机制不明，目前认为肺部过度的炎症反应是主要原因。降钙素基因相关肽（CGRP）是体内神经末梢释放的重要递质，最新研究发现，CGRP有强大的抗炎及组织修复作用。本研究以肺上皮细胞株和幼年大鼠为实验对象，建立脂多糖（LPS）诱导ALI细胞和动物模型，用CGRP干预（外源性CGRP、质粒转染、siRNA技术），检测CGRP的分泌变化、抗炎及促炎因子水平、肺组织病理变化、水通道蛋白及信号分子等，全面阐明CGRP在LPS诱导ALI中的作用及机制。本研究有望发现CGRP的抗炎及促上皮修复作用，为ALI/ARDS的防治带来新的理论进展。内容涉及呼吸病学、重症医学及儿科学等多个学科，研究结果将对ALI/ARDS的防治及其它危重疾病的应用基础研究产生重要影响。

本项目执行四年来，按照项目计划书，顺利完成了各项研究内容。通过体外细胞和体内动物学实验，对CGRP在急性肺损伤作用及信号转导机制进行了系统研究和论证，并结合最新的研究进展，以内外源CGRP为调控对象，以抗细胞凋亡及炎症机制为出发点，通过多种生物学检测方法，研究了内外源性CGRP对急性肺损伤作用的分子机制。取得的主要成果如下：1，内外源性CGRP均能够抑制LPS诱导的新生SD幼鼠的MLE12细胞株的凋亡和炎症因子的分泌；其中CGRP能够调控STAT3、NF-kB和MAPK通路的变化，其可能同炎症相关；CGRP也能影响AQP家族成员的变化，其可能同肺水肿相关；2，利用LPS诱导的急性肺损伤模型，发现外源性或内源性CGRP能够降低LPS诱导的SD幼鼠肺损伤，降低肺部细胞的凋亡，降低肺上皮通透性，减轻肺部的损伤程度；进一步检测发现这同MAPK通路介导的炎症水平有关；此外，AQP家族因子也发生变化，这可能是肺水肿发生机制之一。本项目的研究结果不仅明确了CGRP在急性肺损伤的保护作用，也阐明了其作用的部分机制，为CGRP在急性肺损伤的治疗进行了有益的尝试，并为急性肺损伤药物筛选提供新的选择。