Role of mitophagy regulator USP30 on mitochondrial health and airway epithelial function

Mitochondrial dysfunction has been linked to COPD through findings of imbalanced mitochondrial dynamics and impaired mitophagy in patient-derived tissues and cells, leading to oxidative stress and altered metabolism. The deubiquitinase USP30 limits Parkin-mediated mitophagy and has been investigated in pre-clinical models of age-related diseases including cardiovascular and kidney disease. The aim of this project is to elucidate the role of USP30 in airway epithelial mitochondrial dysfunction of COPD patients, which to date is unexplored. Human bronchial epithelial cells (HBECs) from healthy as well as individuals with COPD were cultured in submerged conditions or at air-liquid interface (ALI). Cells were treated with USP30 inhibitors CPD39 and FT385, with oxidative stress (hydrogen peroxide or cigarette smoke extract) introduced as disease relevant challenge. Mitochondrial dynamics and multiple aspects of airway epithelial functionality were assessed by methods including flow cytometry and confocal imaging using mitochondrial dyes and markers. In HBECs, USP30 inhibition caused slight increase in mitophagy and improved mitochondrial function. Furthermore, USP30 inhibition restored the hydrogen peroxide-induced loss of proliferative capacity in HBECs in submerged culture. For a more in vivo-mimicking system, models and readouts are being developed in HBEC-ALI cultures with first results showing that USP30 inhibition partly rescues a drop in mitochondrial membrane potential caused by cigarette smoke extract. Results obtained thus far indicate that inhibition of USP30 improves mitochondrial health and function in airway epithelial cells and suggests a link to airway epithelial function in COPD.