title: Defective CFTR expression and function are detectable in blood monocytes: development of a new blood test for cystic fibrosis.
abstract: BACKGROUND
  Evaluation of cystic fibrosis transmembrane conductance regulator (CFTR) functional activity to assess new therapies and define diagnosis of cystic fibrosis (CF) is cumbersome. It is known that leukocytes express detectable levels of CFTR but the molecule has not been characterized in these cells. In this study we aim at setting up and validating a blood test to evaluate CFTR expression and function in leukocytes.
  
  
  METHODS
  Western blot, PCR, immunofluorescence and cell membrane depolarization analysis by single-cell fluorescence imaging, using the potential-sensitive DiSBAC(2)(3) probe were utilized. Expression of PKA phosphorylated, cell membrane-localized CFTR was detected in non-CF monocytes, being undetectable or present in truncated form in monocytes derived from CF patients presenting with nonsense mutations. CFTR agonist administration induced membrane depolarization in monocytes isolated from non-CF donors (31 subjects) and, to a lesser extent, obligate CFTR heterozygous carriers (HTZ: 15 subjects), but it failed in monocytes from CF patients (44 subjects). We propose an index, which values in CF patients are significantly (p<0.001) lower than in the other two groups. Nasal Potential Difference, measured in selected subjects had concordant results with monocytes assay (Kappa statistic 0.93, 95%CI: 0.80-1.00).
  
  
  CONCLUSIONS
  CFTR is detectable and is functional in human monocytes. We also showed that CFTR-associated activity can be evaluated in 5 ml of peripheral blood and devise an index potentially applicable for diagnostic purposes and both basic and translational research: from drug development to evaluation of functional outcomes in clinical trials.
authors.affiliation: Sezione di Patologia Generale, Dipartimento di Patologia e Diagnostica, University of Verona, Verona, Italy. claudio.sorio@univr.it
authors.forename: Claudio
authors.initials: C
authors.lastname: Sorio
authors.forename: Mario
authors.initials: M
authors.lastname: Buffelli
authors.forename: Chiara
authors.initials: C
authors.lastname: Angiari
authors.forename: Michele
authors.initials: M
authors.lastname: Ettorre
authors.forename: Jan
authors.initials: J
authors.lastname: Johansson
authors.forename: Marzia
authors.initials: M
authors.lastname: Vezzalini
authors.forename: Laura
authors.initials: L
authors.lastname: Viviani
authors.forename: Mario
authors.initials: M
authors.lastname: Ricciardi
authors.forename: Genny
authors.initials: G
authors.lastname: Verzè
authors.forename: Baroukh Maurice
authors.initials: BM
authors.lastname: Assael
authors.forename: Paola
authors.initials: P
authors.lastname: Melotti
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000584:Amiloride / Q000494:pharmacology; D002460:Cell Line; D002648:Child; D002675:Child, Preschool; D003550:Cystic Fibrosis / Q000097:blood* / Q000175:diagnosis / Q000503:physiopathology*; D019005:Cystic Fibrosis Transmembrane Conductance Regulator / Q000097:blood* / Q000378:metabolism*; D004847:Epithelial Cells / Q000187:drug effects / Q000378:metabolism; D005260:Female; D005453:Fluorescence; D006403:Hematologic Tests / Q000379:methods*; D006579:Heterozygote; D006801:Humans; D007223:Infant; D008297:Male; D008564:Membrane Potentials / Q000187:drug effects; D008875:Middle Aged; D009000:Monocytes / Q000187:drug effects / Q000378:metabolism*; D010641:Phenotype; D059010:Single-Cell Analysis; D055815:Young Adult
chemical_list: D019005:Cystic Fibrosis Transmembrane Conductance Regulator; D000584:Amiloride