Immunochemical analysis of mutant CFTR in lung explants.

BACKGROUND/AIMS Knowledge about the abundance and distribution of CFTR protein glycoforms in native lung tissue is scarce. For upcoming studies with correctors and potentiators for CFTR it is important to get more information about mutant CFTR protein biochemistry. Target for novel treatment is the most afflicted organ in cystic fibrosis (CF), the lung. METHODS Lung tissue sampled from patients with CF and non-CF donors prior to lung transplantation was examined for CFTR-immunoreactive signals by immunoblot. Quantitation of the immunoreactive signals was carried out by densitometry. RESULTS The complex-glycosylated and mannose-rich CFTR isoforms were present in all non-CF specimens, whereas no or only the immature CFTR isoform was visible in CF samples. Whereas some complex-glycosylated CFTR was often present in rectal biopsies of F508del homozygous subjects, no mature CFTR was detectable in CF lungs at the stage of terminal respiratory insufficiency. CONCLUSION Immunoblot analysis of CFTR in lung tissue is feasible, but in context of the upcoming studies of CFTR correctors and potentiators rectal biopsies seem to be a more appropriate choice because of their safe and repeatable excision.