Functional Aspects of Epithelia in Cystic Fibrosis and Asthma
Sammanfattning: The cystic fibrosis transmembrane conductance regulator (CFTR), a cAMP activated chloride channel in the apical membrane of epithelial cells, is defective in patients with cystic fibrosis (CF). Research efforts are focused on chloride channel function in order to find a cure for the disease.Genistein increased chloride transport in normal and delF508-CFTR cultured airway epithelial cells without cAMP stimulation. Prior pretreatment with phenylbutyrate did not affect the rate of the genistein-stimulated chloride efflux in these cells.S-nitrosoglutathione is an endogenous bronchodilator, present in decreased amounts in the lungs of CF patients. We studied the effect of GSNO on chloride (Cl-) transport in primary nasal epithelial cells from CF patients homozygous for the delF508-CFTR mutation, as well as in two CF cell lines, using a fluorescent Cl- indicator and X-ray microanalysis. GSNO increased chloride efflux in the CF cell lines and in primary nasal epithelial cells from CF patients. This effect was partly mediated by CFTR. If the cells were exposed to GSNO in the presence of L-cysteine, Cl- transport was enhanced after 5 min, but not after 4 h. GSNO may be a candidate for pharmacological treatment of CF patients.Chloride transport properties of cultured NCL-SG3 sweat gland cells were investigated. The CFTR protein was neither functional nor expressed in these cells. Ca2+-activated chloride conductance was confirmed and the putative Ca2+-activated chloride channel (CaCC) was further characterized in term of its pharmacological sensitivity.Corticosteroids, the primary treatment for asthma, cause necrosis/apoptosis of airway epithelial cells. It was investigated whether a newer generation of drugs used in asthma, leukotriene receptor antagonists, had similar effects. Both montelukast and dexamethasone, but not beclomethasone or budesonide induced apoptosis/necrosis in superficial airway epithelial cells. Montelukast and corticosteroids also caused decreased expression of intercellular adhesion molecule -1 (ICAM-1) in epithelial but not endothelial cells.
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