title: Induction of CFTR gene expression by 1,25(OH)2vitamin D3, 25OH vitamin D3, and vitamin D3in cultured human airway epithelial cells and in mouse airways.
abstract: Cystic fibrosis (CF) is an autosomal recessive disorder caused by mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene, which often leads to protein misfolding and no CFTR surface localization. This then leads to chronic airway infections, inflammation, and tissue damage. Although vitamin D has been explored as a therapy to treat CF due to its antimicrobial-inducing and anti-inflammatory properties, the effect of 1,25-dihydroxyvitamin D3(1α,25(OH)2D3) on CFTR directly has not been studied. We treated cultured healthy and diseased bronchial epithelial cells (BEC) with 10nM 1α,25(OH)2D3for 6 and 24h and found that 1α,25(OH)2D3increases both mRNA and protein CFTR levels using RT-qPCR, flow cytometry and fluorescence immunohistochemistry. Treatment of CF cells with 10nM 1α,25(OH)2D3led to an increase in both total and surface CFTR expression, suggesting 1α,25(OH)2D3could be used to increase properly localized CFTR in airway cells. To determine if BEC could convert the more clinically relevant cholecalciferol to 25OHD3, cultured non-CF and CF BECs were treated with a range of cholecalciferol concentrations, and 25OHD3levels were quantified by ELISA. We found that 25OHD3levels increased in a concentration-dependent manner. Treatment of BEC with 10μM cholecalciferol led to increases in both CYP24A1 and CFTR mRNA levels, even when added to the apical surface of cells grown in an air-liquid interface, suggesting that topical administration of vitamin D could be used therapeutically. To demonstrate this in vivo, we intranasally delivered 1μM 1α,25(OH)2D3into mice. After 6h, we observed induction of both Cyp24A1 and CFTR expression in the tracheas of treated mice. The major findings of this study are that vitamin D can be converted to the active form when topically administered to the airway, and this could be used to increase CFTR levels in patients with CF. This could potentially be useful as an adjunctive therapy, together with newly developed CF treatments.
authors.affiliation: Department of Oral Biology, University of Florida, Gainesville, FL 32610, United States, United States.
authors.forename: Kristina M
authors.initials: KM
authors.lastname: DiFranco
authors.affiliation: Department of Otolaryngology, Head and Neck Surgery, Medical University of South Carolina, Charleston, SC 29425, United States.
authors.forename: Jennifer K
authors.initials: JK
authors.lastname: Mulligan
authors.affiliation: Department of Otolaryngology, Head and Neck Surgery, Medical University of South Carolina, Charleston, SC 29425, United States.
authors.forename: Aman S
authors.initials: AS
authors.lastname: Sumal
authors.affiliation: Department of Oral Biology, University of Florida, Gainesville, FL 32610, United States, United States. Electronic address: gdiamond@dental.ufl.edu.
authors.forename: Gill
authors.initials: G
authors.lastname: Diamond
mesh_terms: D000818:Animals; D002112:Calcifediol / Q000494:pharmacology*; D002117:Calcitriol / Q000494:pharmacology*; D002460:Cell Line; D002762:Cholecalciferol / Q000494:pharmacology*; D019005:Cystic Fibrosis Transmembrane Conductance Regulator / Q000235:genetics*; D004847:Epithelial Cells / Q000378:metabolism; D006801:Humans; D051379:Mice; D008810:Mice, Inbred C57BL; D012333:RNA, Messenger / Q000235:genetics; D014132:Trachea / Q000378:metabolism; D015854:Up-Regulation; D065668:Vitamin D3 24-Hydroxylase / Q000235:genetics; D014815:Vitamins / Q000494:pharmacology*
chemical_list: D012333:RNA, Messenger; D014815:Vitamins; D019005:Cystic Fibrosis Transmembrane Conductance Regulator; D002762:Cholecalciferol; D065668:Vitamin D3 24-Hydroxylase; D002117:Calcitriol; D002112:Calcifediol
keywords: 1-Alpha-hydroxylase; 25-Hydroxylase; Airway epithelium; Cystic fibrosis