Abstract
Cystic Fibrosis (CF) is a fatal autosomal recessive disease characterized by abnormal ion transport across epithelia, viscous mucus secretions, chronic bacterial infections, and inflammation in the airways that result from misprocessed or nonfunctional CFTR (Cystic Fibrosis Transmembrane conductance Regulator) chloride channels, normally located at the apical membrane of epithelial cells in exocrine tissues. CFTR activity is regulated by the Vasoactive Intestinal Peptide (VIP), a neuropeptide with potent anti-inflammatory, bronchodilatory and immunomodulatory functions. In airway sub-mucosal glands and other exocrine tissues, VIP is the major physiological activator for CFTR-dependent secretions, which contribute to local innate defense. When CFTR is defective or absent from the apical membrane of epithelial cells, due to mutations in the CFTR gene, airway glands no longer secrete in response to VIP stimulation and synergy with acetylcholine is lost. Although it is thought that VIP receptors are not altered in CF epithelial tissues, early studies have demonstrated that innervations by VIP-containing nerve fibers of the skin sweat glands, nasal and intestinal mucosa of CF patients is almost absent compared to healthy individuals, suggesting that absence of VIP stimulation could play a central role in the development of CF pathology.
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