High-content screening for rare respiratory diseases: readthrough therapy in primary ciliary dyskinesia

Development of therapeutic approaches for rare respiratory diseases is hampered by the lack of systems that allow medium-to-high-throughput screening of fully differentiated respiratory epithelium from affected patients. This is a particular problem for primary ciliary dyskinesia (PCD), a rare genetic disease caused by mutations in genes that adversely affect ciliary movement and consequently mucociliary transport. Primary cell culture of basal epithelial cells from nasal brush biopsies, followed by ciliated differentiation at air-liquid interface (ALI) has proven to be a useful tool in PCD diagnostics but the technique’s broader utility, including in pre-clinical PCD research, has been limited by the number of basal cells that it is possible to expand from such biopsies. Here, we describe a high-content, imaging-based screening method, enabled by extensive expansion of PCD patient basal cells and their culture into differentiated human respiratory epithelium in miniaturised 96-well transwell format ALI cultures. Analyses of ciliary beat pattern, beat frequency and ultrastructure indicate that a range of different PCD defects are retained in these cultures. We perform a proof-of-principle personalized investigation in reduced generation of motile cilia (RGMC), a rare and very severe form of PCD, in this case caused by a homozygous nonsense mutation (c.441C>A; p.Cys147*) in the MCIDAS gene. The screening system allowed multiple drugs inducing translational readthrough to be evaluated alone or in combination with inhibitors of nonsense-mediated decay. Restoration of basal body formation in the patient’s nasal epithelial cells was seen in vitro , suggesting a novel avenue for drug evaluation and development in PCD. Summary We describe primary cell culture of nasal epithelial cells from patients with primary ciliary dyskinesia including differentiatiation of these to a ciliary phenotype and high-content screening in miniaturised air-liquid interface cultures. * PCD : Primary ciliary dyskinesia RGMC : reduced generation of motile cilia ALI : air-liquid interface BEBM : bronchial epithelial basal cell medium BEGM : bronchial epithelial cell growth medium ROCK : Rho-associated protein kinase CBF : ciliary beat frequency NMD : nonsense-mediated decay IDA : inner dynein arm ODA : outer dynein arm MTD-L-IDA : microtubules disorganisation with lack of dynein arm