High-Content Analysis to Accelerate Mechanistic and Therapeutic Identification for ABCA3 Deficiency

Project Summary Rare, biallelic, pathogenic variants in the ATP binding cassette transporter A3 gene (ABCA3) are the most common monogenic cause of neonatal respiratory failure in term infants and childhood interstitial lung disease (chILD). ABCA3 transports phospholipids across the lamellar body membrane in alveolar type 2 cells in the lung and is required for assembly of functional surfactant. Pathogenic ABCA3 variants encode disruption of intracellular ABCA3 trafficking or impairment of ATPase mediated, phospholipid transport into the lamellar body. Current treatments (surfactant replacement, steroids, azithromycin, and hydroxychloroquine) are non-specific and ineffective. Lung transplantation, with a 5 year survival of ~50%, or comfort care remain the only treatment options for progressive respiratory failure in affected infants and children. Development of personalized, variant-specific therapies for patients with pathogenic variants in the cystic fibrosis transmembrane conductance regulator gene (CFTR), a member of the ABC transporter superfamily (also known as ABCC7), can provide a model for development of variant-specific therapies for ABCA3 deficiency, although pharmacologic correctors will likely be gene- and variant-specific. The premise of this proposal is to accelerate mechanistic classification and therapeutic identification for ABCA3 deficiency using a genetically-versatile, human pulmonary epithelial cell line (A549), high content analysis (HCA)/deep cellular phenotyping, and high throughput screening (HTS) of FDA-approved compounds. Specifically, we will use human pulmonary epithelial cell lines (A549) that stably express individual ABCA3 pathogenic variants for fluorescence-based, quantitative, high content analysis and high throughput screening of FDA-approved compounds for rescue of variant-encoded ABCA3 mutants to test the hypothesis that ABCA3 variant-encoded disruption can be mechanistically classified and corrected using FDA-approved compounds. These studies will provide proof-of-principle for a high-content, scalable, functional, physiologically- relevant platform to discover variant-specific therapies for infants and children with ABCA3 deficiency.