A novel neutrophil derived inflammatory biomarker of pulmonary exacerbation in cystic fibrosis.
BACKGROUND
The focus of this study was to characterize a novel biomarker for cystic fibrosis (CF) that could reflect exacerbations of the disease and could be useful for therapeutic stratification of patients, or for testing of potential drug treatments. This study focused exclusively on a protein complex containing alpha-1 antitrypsin and CD16b (AAT:CD16b) which is released into the bloodstream from membranes of pro-inflammatory primed neutrophils.


METHODS
Neutrophil membrane expression and extracellular levels of AAT and CD16b were quantified by flow cytometry, Western blot analysis and by 2D-PAGE. Interleukin-8 (IL-8), tumor necrosis factor-alpha (TNF-alpha) and AAT:CD16b complex were quantified in CF plasma (n=38), samples post antibiotic treatment for 14 days (n=10), chronic obstructive pulmonary disease (n=10), AAT deficient (n=10) and healthy control (n=14) plasma samples by ELISA.


RESULTS
Cell priming with IL-8 and TNF-alpha caused release of the AAT:CD16b complex from the neutrophil cell membrane. Circulating plasma levels of IL-8, TNF-alpha and AAT:CD16b complex were significantly higher in patients with CF than in the other patient groups or healthy controls (P<0.05). Antibiotic treatment of pulmonary exacerbation in patients with CF led to decreased plasma protein concentrations of AAT:CD16b complex with a significant correlation with improved FEV1 (r=0.81, P=0.003).


CONCLUSIONS
The results of this study have shown that levels of AAT:CD16b complex present in plasma correlate to the inflammatory status of patients. The AAT:CD16b biomarker may become a useful addition to the clinical diagnosis of exacerbations in CF.
Respiratory Research Division, Department of Medicine, Royal College of Surgeons in Ireland, Education and Research Centre, Beaumont Hospital, Dublin 9, Ireland. emerreeves@rcsi.ie
Emer P
EP
Reeves
David A
DA
Bergin
Sean
S
Fitzgerald
Elaine
E
Hayes
Joanne
J
Keenan
Michael
M
Henry
Paula
P
Meleady
Isabel
I
Vega-Carrascal
Michelle A
MA
Murray
Teck Boon
TB
Low
Cormac
C
McCarthy
Emmet
E
O'Brien
Martin
M
Clynes
Cedric
C
Gunaratnam
Noel G
NG
McElvaney
D000328:Adult; D015703:Antigens, CD / Q000378:metabolism*; D015415:Biomarkers / Q000378:metabolism*; D015816:Cell Adhesion Molecules, Neuronal / Q000378:metabolism*; D003550:Cystic Fibrosis / Q000188:drug therapy / Q000378:metabolism*; D018450:Disease Progression; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D005326:Fetal Proteins / Q000378:metabolism*; D006801:Humans; D008297:Male; D009504:Neutrophils / Q000378:metabolism; D040901:Proteomics; D055815:Young Adult; D000515:alpha 1-Antitrypsin / Q000378:metabolism*; D020410:Activated-Leukocyte Cell Adhesion Molecule
D015703:Antigens, CD; D015415:Biomarkers; D015816:Cell Adhesion Molecules, Neuronal; D005326:Fetal Proteins; D000515:alpha 1-Antitrypsin; C105613:ALCAM protein, human; D020410:Activated-Leukocyte Cell Adhesion Molecule