1. Interleukin 8 Secretion from Monocytes of Subjects Heterozygous for the ΔF508 Cystic Fibrosis Transmembrane Conductance Regulator Gene Mutation Is Altered
- Author
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Brian O'Sullivan, Steven D. Freedman, Meredith M. Regan, Michel Warny, Munir M. Zaman, Ciaran P. Kelly, Andres Gelrud, Omer Junaidi, and Julie C. Shea
- Subjects
Adult ,Male ,Microbiology (medical) ,Heterozygote ,Interleukin-8 secretion ,MAP Kinase Signaling System ,CD14 ,Clinical Biochemistry ,Immunology ,Lipopolysaccharide Receptors ,Cystic Fibrosis Transmembrane Conductance Regulator ,Receptors, Cell Surface ,Gene mutation ,Cystic fibrosis ,Monocytes ,Proinflammatory cytokine ,medicine ,Humans ,Immunology and Allergy ,Prospective Studies ,ΔF508 ,Membrane Glycoproteins ,biology ,Interleukin-8 ,Toll-Like Receptors ,Heterozygote advantage ,Middle Aged ,medicine.disease ,Cystic fibrosis transmembrane conductance regulator ,Toll-Like Receptor 4 ,Case-Control Studies ,Immune-Mediated Responses and Disorders ,Mutation ,biology.protein ,Female - Abstract
Patients with cystic fibrosis (CF) exhibit an excessive host inflammatory response. The aim of this study was to determine (i) whether interleukin 8 (IL-8) secretion is increased from monocytes from subjects heterozygous as well as homozygous for cystic fibrosis transmembrane conductance regulator (CFTR) mutations and (ii) whether this is due to increased cell surface lipopolysaccharide (LPS) receptors or, alternatively, increased activation of mitogen-activated protein kinases (MAPK). The basal level of IL-8 secretion was higher from monocytes from CF patients than from monocytes from healthy controls (P 0.02) and obligate heterozygotes (parents of the CF patients). The 50% effective concentrations for LPS-induced IL-8 production for monocytes from both CF patients and obligate heterozygotes were 100-fold lower than those for monocytes from healthy controls (P < 0.05). No differences in the levels of IL-1 production were seen between these groups. Expression of the LPS surface receptors CD14 and Toll-like receptor 4 were not different between CF patients and healthy controls. In contrast, phosphorylation of the MAPKs p38 and ERK occurred at lower doses of LPS in monocytes from patients heterozygous and homozygous for CFTR mutations. These results indicate that a single allelic CFTR mutation is sufficient to augment IL-8 secretion in response to LPS. This is not a result of increased LPS receptor expression but, rather, is associated with alterations in MAPK signaling. Cystic fibrosis (CF) is an autosomal recessive disorder caused by mutations of the gene encoding the cystic fibrosis transmembrane conductance regulator (CFTR) (16). Patients with CF express a typical phenotype characterized by recurrent pulmonary infections that ultimately lead to pulmonary failure and death. It has become evident that in addition to poor clearance of bacteria, pulmonary disease in CF patients is characterized by an excessive inflammatory response to infection by Pseudomonas aeruginosa. Even in the absence of detectable lung infection, the bronchoalveolar lavage (BAL) fluid of CF patients contains increased levels of proinflammatory cytokines and neutrophils (10, 13). In addition, interleukin 8 (IL-8) levels in BAL fluids from children with CF are significantly higher than those in BAL fluids from non-CF children with bacterial infection of the lower airways (14). These data suggest that CFTR mutations may lead to an excessive inflammatory response in the lung. This appears to be a constitutive
- Published
- 2004
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