Regulation of Airway Lactoperoxidase Host Defense

乳过氧化物酶（LPO）系统是气道宿主防御细菌的重要贡献者， 也是呼吸道H2 O2的主要消耗者，而H2 O2又与呼吸道疾病相关。 炎症LPO活性的丧失可能导致气道感染增加，而LPO的任何增加都可能导致呼吸道感染。 会产生有害的后果。该应用程序将测试LPO的所有组件 系统，包括LPO酶的表达和分泌，SCN~-跨上皮转运和H_2O_2 在囊性纤维化中， (CF)可能会导致发病。这一假设得到了LPO系统计算模型的支持 预测组分中任何不平衡的气道表面液体中的活动将使系统 不足以防御宿主。该假设和模型得到初步数据的支持，表明： 气道上皮缺乏正常的LPO底物SCN~-向顶面的转运，这可能有助于 气道感染和炎症; B）气道上皮细胞通过Duox产生H2 O2，Duox是一种NADPH氧化酶， c）活性氧（ROS）增加LPO的表达;和 d）Duox和LPO mRNA在CF气道上皮中上调。具体目标1将涉及以下方面的监管： 正常和CF气道上皮细胞中通过[Ca 2 +]j、cAMP、SCN~-或 促炎和感染相关刺激。具体目标2将检验有缺陷的SCN~ 在体内CF气道上皮中的转运导致CF气道分泌物中SCN~-的减少， 危及主机防御。将在呼出气中测定SCN~和过氧化物酶终产物 使用液相色谱串联电喷雾电离-质谱法测定冷凝物。具体 目的3将检验ROS和/或SCN增加正常和CF中LPO mRNA表达的假设。 通过使用周转研究和核径流测定来检测气道上皮细胞。LPO mRNA的5'端将被 通过RACE和上游序列中鉴定的启动子元件定位。第4章测试 假设降低CF气道SCN-水平有助于嗜中性粒细胞介导的氧化损伤， CF气道中观察到的定植细菌表型。总结：这些实验将提供 关于囊性纤维化患者生理缺陷的新信息，可能导致新的治疗方法 治疗这种疾病的方法。

The lactoperoxidase (LPO) system is a significant contributor to airway host defense against bacteria, viruses and fungi and also is a major consumer of airway H2O2 that in turn is associated with airway inflammation. A loss of LPO activity may lead to increased airway infection, while any increase in LPO could have injurious consequences. This application will test the hypothesis that all components of the LPO system, including LPO enzyme expression and secretion, SCN~ transport across the epithelium and H2O2 production, are coordinately regulated and that an absence of the LPO substrate, SCN~, in cystic fibrosis (CF) may contribute to pathogenesis. This hypothesis is supported by a computational model of LPO system activity in airway surface liquid that predicts any unbalance in the components will render the system inadequate for host defense. The hypothesis and model are supported by preliminary data showing: a) CF airway epithelia lack normal transport of LPO's substrate, SCN~, to the apical surface that may contribute to airway infections and inflammation; b) airway epithelia produce H2O2 through Duox, an NADPH oxidase that may be regulated by intracellular [Ca2+]; c) reactive oxygen species (ROS) increase expression of LPO; and d) Duox and LPO mRNAs are up-regulated in CF airway epithelia. Specific Aim 1 will address regulation of Duox H2O2 production in normal and CF airway epithelial cells by changes in [Ca2+]j, cAMP, SCN~ or proinflammatory and infection related stimuli. Specific Aim 2 will test the hypothesis that defective SCN~ transport in CF airway epithelia results in decreased SCN~ in CF airway secretions in vivo that then may compromise host defense. SCN~ and peroxidase endproducts will be determined in exhaled breath condensate using liquid chromatography in tandem with electrospray ionization-mass spectrometry. Specific Aim 3 will test the hypothesis that ROS and/or SCN" increases LPO mRNA expression in normal and CF airway epithelia by using turnover studies and nuclear runoff assays. The 5' end of LPO mRNA will be mapped by RACE and promoter elements in upstream sequences identified. Specific Aim 4 will test the hypothesis that depressed CF airway SCN" levels contribute to neutrophil-mediated oxidative damage and to the phenotype of colonizing bacteria observed in CF airways. Lav Summary: These experiments will provide new information about physiological defects in cystic fibrosis patients that may lead to new therapeutic approaches to treating this disease.