Higher throughput drug screening for rare respiratory diseases: readthrough therapy in primary ciliary dyskinesia.

Background: 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 the 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 restricted by the limited number of basal cells that can be expanded from such biopsies.
Methods: We describe an immunofluorescence screening method, enabled by extensive expansion of basal cells from PCD patients and the directed differentiation of these cells into ciliated epithelium in miniaturised 96-well transwell format ALI cultures. As proof-of-principle, we performed a personalised investigation in a patient with a rare and severe form of PCD (reduced generation of motile cilia), in this case caused by a homozygous nonsense mutation in the MCIDAS gene.
Results: Initial analyses of ciliary ultrastructure, beat pattern and beat frequency in the 96-well transwell format ALI cultures indicate that a range of different PCD defects can be retained in these cultures. The screening system in our proof-of-principal investigation allowed drugs that induce translational readthrough to be evaluated alone or in combination with nonsense-mediated decay inhibitors. We observed restoration of basal body formation but not the generation of cilia in the patient's nasal epithelial cells in vitro. CONCLUSION: Our study provides a platform for higher throughput analyses of airway epithelia that is applicable in a range of settings and suggests novel avenues for drug evaluation and development in PCD caused by nonsense mutations.
Competing Interests: Conflict of interest: D.D.H. Lee has nothing to disclose. Conflict of interest: D. Cardinale has nothing to disclose. Conflict of interest: E. Nigro has nothing to disclose. Conflict of interest: C.R. Butler has nothing to disclose. Conflict of interest: A. Rutman has nothing to disclose. Conflict of interest: M.R. Fassad has nothing to disclose. Conflict of interest: R.A. Hirst has nothing to disclose. Conflict of interest: D. Moulding has nothing to disclose. Conflict of interest: A. Agrotis has nothing to disclose. Conflict of interest: E. Forsythe has nothing to disclose. Conflict of interest: D. Peckham has nothing to disclose. Conflict of interest: E. Robson has nothing to disclose. Conflict of interest: C.M. Smith has nothing to disclose. Conflict of interest: S. Somavarapu has nothing to disclose. Conflict of interest: P.L. Beales has nothing to disclose. Conflict of interest: S.L. Hart has nothing to disclose. Conflict of interest: S.M. Janes has nothing to disclose. Conflict of interest: H.M. Mitchison has nothing to disclose. Conflict of interest: R. Ketteler has nothing to disclose. Conflict of interest: R.E. Hynds has nothing to disclose. Conflict of interest: C. O'Callaghan has nothing to disclose.
(Copyright ©The authors 2021.)