细菌或病毒感染导致的人中性粒细胞弹性蛋白酶（HNE）和其内源性抑制剂的失衡是引起炎性肺损伤的重要原因。前期我们发现天然五环三萜成分具有较好HNE抑制活性并在动物模型上有治疗炎性肺损伤作用，提示五环三萜及HNE抑制通路对治疗炎性肺损伤有重要意义。桔梗甘草汤源自《伤寒论》，在临床用于治疗肺炎等疾病。桔梗和甘草均含有大量的五环三萜成分，已有大量研究报道它们的抗炎作用和机制，但抑制HNE是否是其作用通路之一，是否存在HNE抑制活性更好的化合物还不清楚。本课题我们制备桔梗甘草汤复方、单味药中富含和去除五环三萜的提取物和单体，进行体外抑制HNE活性，体内不同模型小鼠肺泡灌洗液和血中NE活性变化和相关炎症细胞、细胞因子水平变化及肺部病理变化研究，观察五环三萜成分及HNE抑制机制在治疗炎性肺损伤中的重要性，为更好地阐明桔梗甘草汤抗炎药效物质基础，寻找强效的HNE抑制剂，研发治疗肺部炎症的中药新药打下基础。

The imbalance of Human neutrophil elsatase (HNE) and its endogenous inhibitor (HNEI) caused by bacterial and viral infection has been implicated as an important contributor of inflammatory lung injury. In the previous studies, we found some pentacyclic triterpene constituents have potential HNE inhibitory activity and cna treat inflammatory lung injury in animal models. It suggests that pentacyclic triterpenes and inhibition of HNE pathway is important in the treatment of inflammatory lung injury. Jiegeng-Ganchao-Tang, which is a TCM compound from “ Shang Han Lun ”, has the function of treatment of lung inflammation. Both Jiegeng (Platycodon grandifloras) and Ganchao (Glycyrrhizauralensis) contain large quantum of pentacyclic triterpenes. There are many reports on the anti-inflammatory function and their mechanism of the two TCMs. However, whether the inhibition of HNE pathway is one of the important anti-inflammatory mechanism, whether there is any potential HNE inhibitors of pentacyclic triterpenes in the two TCMs, is still unclear. In this program, we will take Jiegeng-Ganchao-Tang as the object of study, prepare the pentacyclicterpenesriched and removed extracts and single compounds from the two TCMs, investigate their HNE inhibitory effects in vitro. We will also establish different inflammatory lung injury model in normal and NE gene knockout mice, observe the NE activity, the pulmonary inflammatory cells numbers, factor pathological changes. By these results, we will better understand the importance of pentacyclic triterpenes and the inhibition of HNE pathway in inflammatory lung injury treatment. We will also have a chance to find powerful HNE inhibitor and potentially develop new drug in the treatment of lung inflammation based this study.