Eicosanoid Production By Infected Lung Epithelial Cells

Massachusetts General Hospital, Boston MA

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Abstract

DESCRIPTION (provided by applicant): Inflammatory mechanisms at mucosal surfaces have been a major focus over the past 9 years during my graduate and post-graduate studies. Recruitment of neutrophils (PMNs) to the airway mucosa is a pathological hallmark of diseases such as pneumonia, cystic fibrosis and chronic obstructive pulmonary disease. I am investigating a novel inflammatory pathway using an in vitro model consisting of lung epithelial cells grown on Transwell filters and isolated human PMNs. In this model, bacterial infection of lung epithelia cause epithelial secretion of a PMN chemo-attractant, which directs PMNs to cross the epithelium. During my post-doctoral training, we identified this PMN chemo-attractant as the eicosanoid, hepoxilin A3 (HXA3). This proposal delineates a focused approach to identify enzymes responsible for HXA3 synthesis in the infected lung epithelium. Specifically, phospholipase A2s (PLA2) and 12-lipoxygenases (12-LOs) will be analyzed. PLA2 enzymes are primarily responsible for generation arachidonic acid, which is the precursor of all eicosanoids and 12-LO mediates the conversion of arachidonic acid into HXA3. Both lung epithelial cells and pathogenic bacteria possess PLA2 activity and we will investigate the contribution of each source of PLA2 towards the production of HXA3 in this proposal. Future studies will evaluate to role of HXA3 using more complex and/or more disease relevant models such as air-liquid interface cultures, CFTR mutant epithelial cells, co-cultures with epithelial-endothelial monolayers, whole tissue, and whole animal. Also, an important future consideration involves the analysis of tissues from patients with mucosal inflammatory conditions to determine if an increased expression of enzymes critical for HXA3 production is observed. A thorough understanding of this unexplored pathway will lead to strategies that selectively block HXA3 production. My long-term career goal is to develop therapeutics that alleviates destructive inflammation at mucosal surfaces. Diseases that may benefit from this therapeutic strategy are not exclusive to the lung. Infections of the skin, urogenital tract, and gut, as well as idiopathic conditions such as psoriasis and inflammatory bowel disease all share destructive PMN infiltration at the epithelial surface and may involve dys-regulation of HXA3 production. These studies could ultimately result in the development of an entirely new series of anti-inflammatory drugs having efficacy towards a wide range of pathologies