SPLUNC1 and Neutrophilic Inflammation in Cystic Fibrosis

描述(申请人提供)：囊性纤维化(CF)，是美国最常见的致命性遗传病。CF患者的主要死亡原因是以持续性炎症和中性粒细胞浸润为特征的CF肺部疾病。导致CF中性粒细胞增多的机制尚不清楚，抗炎治疗也是有限的。短腭、肺和鼻上皮克隆1 SPLunc1是一种丰富的呼吸道蛋白，具有宿主保护功能，可能在CF肺部疾病的发生发展中起重要作用。SPLunc1在过敏性炎症患者的呼吸道中含量很低，根据我们的初步工作，它似乎在调节中性粒细胞呼吸道炎症方面发挥了作用。在野生型小鼠中，SPLunc1被内毒素和常见的呼吸道病原体迅速降低，这是一种潜在的保护机制，可以限制急性呼吸道炎症期间的中性粒细胞损伤。有趣的是，在接受肺移植的CF患者发炎、感染的肺中，SPLunc1的表达增加，这表明SPLunc1的下调，从而对中性粒细胞炎症的保护作用可能受到损害。与CF患者相似，在CF特异性动物模型的支气管肺泡灌洗液中，SPLunc1的表达增加。SPLunc1基因缺陷(Splunc1-/-)小鼠和CF特异性动物模型似乎对脂多糖有不同的反应：SPLunc1缺陷小鼠的中性粒细胞炎症有限，而CF特异性小鼠的中性粒细胞炎症增加。研究人员推测，SPLunc1的高水平可能与在CF呼吸道观察到的夸大的中性粒细胞反应有关。本研究的目的是了解SPLunc1的调控及其在中性粒细胞趋化、移行和中性粒细胞炎症存活中的分子相互作用的分子细节，以期提出一种初步的途径来调控SPLunc1在慢性阻塞性肺疾病中的治疗作用。本项目的具体目标是：1)通过对Splunc1-/-中性粒细胞和呼吸道上皮细胞进行中性粒细胞功能分析，确定SPLunc1如何控制肺内的中性粒细胞炎症；2)通过建立SPLunc1表达的动力学，并剖析调节SPLunc1表达的细胞因子的信号通路，确定SPLunc1调节的机制；以及3)通过建立CF中SPLunc1增加的机制，以及在CF特异性动物模型中，通过siRNA或阻断SPLunc1增加机制来确定SPLunc1增加对CF的影响，以及测量SPLunc1减少后的气道炎症。这项工作将为深入了解这种丰富的气道蛋白在调节气道炎症中的作用，它的调节机制，以及它在CF肺部疾病发病机制中的作用。如果成功，该项目将确定SPLunc1控制CF中性粒细胞增多的机制，为预防和治疗CF肺部疾病的新的治疗靶点奠定基础。(摘要结束)

DESCRIPTION (provided by applicant): Cystic fibrosis (CF), is the most common fatal genetic disease in the United States. The main cause of mortality in CF patients is CF lung disease, which is characterized by persistent inflammation and neutrophilic infiltration. The mechanisms that lead to increased airway neutrophilia in CF are not well understood, and antiinflammatory therapies are limited. Short Palate, Lung and Nasal epithelium Clone 1 (SPLUNC1) is an abundant airway protein with host protective functions that may be important in the development of CF lung disease. SPLUNC1 is low in the airways of patients with allergic inflammation, and based on our preliminary work, it appears to play a role in regulating neutrophilic airway inflammation. SPLUNC1 is rapidly decreased by LPS and common respiratory pathogens in wild-type mice, a potentially protective mechanism that limits neutrophilic injury during acute airway inflammation. Interestingly, SPLUNC1 is increased in the inflamed, infected lungs of CF patients undergoing lung transplantation suggesting that the downregulation of SPLUNC1, and thus its protective effect against neutrophilic inflammation, may be impaired. Similarly to CF patients, SPLUNC1 is increased in the bronchoalveolar lavage fluid of CF-specific animal models. SPLUNC1- deficient (splunc1-/-) mice and CF-specific animal models seem to have divergent responses to LPS: SPLUNC1-deficient mice have limited neutrophilic inflammation, whereas CF-specific mouse models have increased neutrophilic inflammation. The researchers hypothesize that high levels of SPLUNC1 may contribute to the exaggerated neutrophilic responses observed in CF airways. The objective of this proposal is to discern the molecular details of the regulatin of SPLUNC1 and its molecular interactions in neutrophil chemotaxis, transmigration and survival in airway inflammation, in order to propose an initial approach to modulate SPLUNC1 with therapeutic purposes in CF. The specific aims of this project are: 1) Define how SPLUNC1 controls neutrophilic inflammation in the lungs by performing neutrophil function assays with splunc1-/- neutrophils and airway epithelial cells~ 2) Define mechanisms of SPLUNC1 regulation by establishing the kinetics of SPLUNC1 expression, and dissecting signaling pathways of cytokines that regulate SPLUNC1 expression, and 3) Define the effects of increased SPLUNC1 in CF by establishing mechanisms of increased SPLUNC1 in CF, and measuring airway inflammation after SPLUNC1 is decreased by siRNA or blocking SPLUNC1-increasing mechanisms in CF-specific animal models. This work will provide insights into the role of this abundant airway protein in modulating airway inflammation, its regulatory mechanisms, and its role in CF lung disease pathogenesis. If successful, this project will identify the mechanisms by which SPLUNC1 controls neutrophilia in CF, laying a foundation for new therapeutic targets in the prevention and treatment of CF lung disease. (End of Abstract)