Role of Airway Epithelium in Mycoplasma Pathogenesis

粘液分泌过多是囊性纤维化、哮喘和COPD的主要临床症状。结果是在小气道中形成粘液栓，这是复发感染的部位。这些堵塞也会导致氧气不足。上述每种疾病的致死性都与过量粘液的存在直接相关。分泌过多的基质是气道粘液腺的病理性生长，这反映在这些患者尸检时一致发现的腺体：壁比增加。分子 成人气道中引起腺体生长的机制尚不清楚，但一旦了解，就可能为药物开发开辟道路，以帮助这些患者。基于我们的初步数据及其与其他系统中发现的相似性，我们提出支原体在上皮间充质连接处引起刺激的会聚，导致Lef-1/β连环蛋白过表达和随后在选择的上皮细胞中基因表达的变化。受影响的基因包括E-cadherin和EMMPRIN。虽然下调E-钙粘蛋白通过削弱粘附连接促进芽形成，但根据我们的体外观察，可以预期上调EMMPRIN增加非粘附细胞的运动性。 在目标1中，我们将使用针对每种蛋白质的选择性siRNA在体外和体内检查腺芽形成对Lef-1、β连环蛋白、wnt和EMMPRIN的依赖性。在目标2中，我们将测试的假设，Lef-1/β连环蛋白在腺芽的上调是直接负责的EMMPRIN，其启动子确实包含推定的Lef 1-β连环蛋白反应元件的上调。在目标3中，我们将确定EMMPRIN过表达上皮细胞的分子变化，这些变化有助于高运动表型。这些研究结果将为肺部疾病中粘液腺形成提供一个分子模型，并为开发药物以阻断分泌过多和延长生命提供新的靶点。

Mucus hypersecretion is a major clinical symptom of cystic fibrosis, asthma, and COPD. A consequence is the formation of mucus plugs in small airways, which are sites of recurrent infection. These plugs also bring about oxygen insufficiency. The lethality of each of the above conditions is directly linked to the presence of excessive mucus. The substrate for hypersecretion is the pathological growth of airway mucus glands, which is reflected in increased gland:wall ratios consistently found at autopsy in these patients. The molecular mechanisms responsible for initiating gland growth in adult airways are unknown, but once understood, could open the way for drug development to help these patients. Based on our preliminary data and its similarity to findings in other systems, we propose that Mycoplasma elicits a convergence of stimuli at epithelial mesenchymal junctions leading to Lef-1/beta catenin overexpression and subsequent changes in gene expression in select epithelial cells. Among the genes so affected are E-cadherin and EMMPRIN. While downregulation of E-cadherin promotes bud formation by weakening adherens junctions, upregulation of EMMPRIN can be expected, based on our in vitro observations, to increase motility of the non-adherent cells. In Aim 1, we will examine the dependence of gland bud formation on Lef-1, beta catenin, wnt and EMMPRIN, using selective siRNAs directed against each protein both in vitro and in vivo. In Aim 2, we will test the hypothesis that Lef-1/beta catenin upregulation in gland buds is directly responsible for upregulation of EMMPRIN, whose promoter indeed contains putative Lef1-beta catenin response elements. In Aim 3, we will identify the molecular changes in EMMPRIN-overexpressing epithelial cells contributing to the hypermotile phenotype. The results of the proposed studies should provide a molecular model of mucus gland formation in lung disease and suggest novel targets for the development of drugs to block hypersecretion and prolong life.