Online

White, Sierra Rose

Cellular, Molecular, and Biomedical Sciences Graduate Program

2022

Ph. D.

Asthma is a chronic inflammatory disease of the lungs that affects roughly 25 million Americans, costing the United States upwards of $80 billion annually in management and economic loss. The airway epithelium, which serves as the first line of defense against insults in the lung, are now appreciated as key contributors to initiation of this disease. A key regulator of the epithelial response to allergens and other inhaled irritants that can induce an allergic asthmatic response is the mitochondria. During an allergic response, the airway epithelial energy requirement changes, and mitochondrial function is altered, enhancing production of reactive oxygen species, and decreasing oxidative phosphorylation, critical to progression of the asthmatic phenotype. Interestingly, it has been observed that epithelial mitochondria are structurally altered as well, appearing smaller and damaged in asthmatics. Mitochondrial dynamic regulation is known to regulate proper distribution and function of the mitochondria, but has not been examined in depth in this context. We therefore aimed to determine the role of mitochondrial dynamic regulation in the epithelial pro-inflammatory response to allergen. To understand the role of mitochondrial dynamic regulation in initiation and propagation of the airway epithelial response to allergen, we utilized conditional deletion techniques to assess the regulatory roles of DRP1 and Miro1, regulators of mitochondrial fission and trafficking in the cell respectively. We demonstrated in vitro that following a single house dust mite (HDM) challenge, airway epithelial cells rapidly activate mitochondrial fission through DRP1, and that deletion of Drp1 suppresses the fission and enhances pro-inflammatory secretions. Deletion of Drp1 in airway club cells in vivo exhibited enhanced production of pro-inflammatory chemokine, Th2 inflammation, eosinophil and lymphocyte recruitment, mucin production, and epithelial apoptosis following acute HDM exposure. Miro1 epithelial deletion from airway epithelial cells also enhanced pro-inflammatory cytokine production and cell death following a single HDM challenge, as well as enhanced lymphocyte recruitment, pro-inflammatory chemokine signaling, and cell death following five consecutive HDM challenges. Additionally, both Drp1 and Miro1 deletion increased airway hyperresponsiveness, though Miro1 deletion had a less severe impact. Collectively, our data suggest that DRP1-mediated mitochondrial fission and Miro1-mediated trafficking are important for the regulation of the airway epithelial pro-inflammatory response, as well as airway epithelial survival after exposure to HDM. Mechanistic studies in the future will potentially reveal the delicate balance of DRP1/Miro1 functions in allergic airway disease.