Expression and functional significance of the cystic fibrosis transmembrane conductance regulator (CFTR) in human mast cells

• Main Author: Dry, Ren
• Other Authors: Dr. A. Dean Befus (Medicine)
• Format: Others
• Language: en
• Published: 2009
• Subjects: cystic fibrosis; cftr; mast cells
• Online Access: http://hdl.handle.net/10048/792

Mast cells (MC) are present in nearly all tissues in the body and participate in many physiological processes including allergy, tissue remodelling, fibrosis, angiogenesis, and autoimmunity. They can be activated by many stimuli, including allergic and innate immune stimulation. When activated, MC release mediators through which they can regulate inflammatory processes. Recently, we have discovered that rat and human MC express the Cystic Fibrosis Transmembrane Conductance Regulator (CFTR), the gene responsible for Cystic Fibrosis (CF). We showed that CFTR had functional activity in MC and its expression was differentially regulated by IFNg. In this thesis, we compared CFTR expression between MC and epithelial cells (EC) by Western blot analysis and found that CFTR expression in MC is similar to that in EC, but there are some differences which suggest either glycosylation or post-transcriptional/translational differences between MC and EC. We also explored the role of CFTR in human MC secretion from various cellular compartments, in response to various stimuli. When we blocked CFTR using pharmacological inhibitors, there was an inhibition of cAMP-dependent Cl- flux. Our data also shows that CFTR pharmacological inhibition had no effect on IgE/anti-IgE-mediated b-hexosaminidase or eicosanoid release from MC. When we stimulated MC with either IgE/anti-IgE or the adenosine receptor agonist NECA (3 uM) for 24h in the presence of CFTR inhibitors, secretion of several mediators appeared to be dysregulated including IL-8, MIF, IL-13, IL-16, PAI-1 and CCL1. To add to these findings, we also used short hairpin RNA (shRNA) to reduce CFTR expression in MC. CFTR deficient MC were unresponsive to NECA and showed reduced constitutive IL-6 secretion. Finally, we cultured MC from CF and non-CF donor peripheral blood progenitors and compared several phenotypic and functional aspects of the cells. We saw no difference in growth, protease content and surface marker expression between CF and non-CF MC, but stimulation of the cells with IgE/anti-IgE or Pseudomonas aeruginosa appeared to differentially induce cytokine synthesis and secretion from CF and non-CF MC. These findings suggest that MC function is dysregulated in CF and that CF MC may be involved in the pathophysiology of CF. === Experimental Medicine