Neutrophils in cystic fibrosis. Are they intrinsically defective?
Résumé
Cystic fibrosis (CF) is a recessive genetic disorder caused by mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene. CF lungs are characterized by chronic colonization by opportunistic pathogens and a neutrophilic infiltration that results in excessive neutrophil protease release and lung tissue destruction. Previous studies have reported neutrophil dysfunction in CF. However, the exact etiology of the altered functionality of CF neutrophils (i.e.a result of the genetic defect or a consequence of chronic infection, remains unclear. Recently, a CFTR-/- knockout pig model has been developed that displays most of the features of the human CF disease1. We and others have shown that at birth these animals do not show early signs of systemic or lung infection. This fact and the similarities between human and pig neutrophils3 make them a suitable model to develop a research project aimed to answer the following key question: are CF neutrophils intrinsically defective? Blood neutrophils will be collected from CFTR-/- and wild-type (WT) newborn piglets and differences in their proteomic profiling will be evaluated using Intact Cell MALDI-TOF MS (ICM-MS). MS spectra will be further processed and analyzed with ClinProTools v3.0. Our preliminary data shows that ICM-MS-based analysis discriminates CFTR-/- and WT neutrophils suggesting differences in their protein composition. Further analysis will include the characterization of the molecular composition of the spectra through high-throughput top-down protein by nanoLC-MS/MS on a LTQ Orbitrap Velos. Functional assays will be performed on neutrophils in order to establish a link between differentially-expressed proteins and neutrophil activity. The expected data could provide a molecular target for CF therapies modulating neutrophil function.