Intracellular secretory leukoprotease inhibitor modulates inositol 1,4,5-triphosphate generation and exerts an anti-inflammatory effect on neutrophils of individuals with cystic fibrosis and chronic obstructive pulmonary disease.
Secretory leukoprotease inhibitor (SLPI) is an anti-inflammatory protein present in respiratory secretions. Whilst epithelial cell SLPI is extensively studied, neutrophil associated SLPI is poorly characterised. Neutrophil function including chemotaxis and degranulation of proteolytic enzymes involves changes in cytosolic calcium (Ca(2+)) levels which is mediated by production of inositol 1,4,5-triphosphate (IP3) in response to G-protein-coupled receptor (GPCR) stimuli. The aim of this study was to investigate the intracellular function of SLPI and the mechanism-based modulation of neutrophil function by this antiprotease. Neutrophils were isolated from healthy controls (n = 10), individuals with cystic fibrosis (CF) (n = 5) or chronic obstructive pulmonary disease (COPD) (n = 5). Recombinant human SLPI significantly inhibited fMet-Leu-Phe (fMLP) and interleukin(IL)-8 induced neutrophil chemotaxis (P < 0.05) and decreased degranulation of matrix metalloprotease-9 (MMP-9), hCAP-18, and myeloperoxidase (MPO) (P < 0.05). The mechanism of inhibition involved modulation of cytosolic IP3 production and downstream Ca(2+) flux. The described attenuation of Ca(2+) flux was overcome by inclusion of exogenous IP3 in electropermeabilized cells. Inhibition of IP3 generation and Ca(2+) flux by SLPI may represent a novel anti-inflammatory mechanism, thus strengthening the attractiveness of SLPI as a potential therapeutic molecule in inflammatory airway disease associated with excessive neutrophil influx including CF, non-CF bronchiectasis, and COPD.
Respiratory Research Division, Department of Medicine, Royal College of Surgeons in Ireland, Education & Research Centre, Beaumont Hospital, Dublin 9, Ireland.
Emer P
EP
Reeves
Nessa
N
Banville
Dorothy M
DM
Ryan
Niamh
N
O'Reilly
David A
DA
Bergin
Kerstin
K
Pohl
Kevin
K
Molloy
Oliver J
OJ
McElvaney
Khalifah
K
Alsaleh
Ahmed
A
Aljorfi
Osama
O
Kandalaft
Eimear
E
O'Flynn
Patrick
P
Geraghty
Shane J
SJ
O'Neill
Noel G
NG
McElvaney
D000328:Adult; D000893:Anti-Inflammatory Agents / Q000378:metabolism* / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism; D015550:Cell Degranulation / Q000187:drug effects; D002633:Chemotaxis / Q000187:drug effects; D003550:Cystic Fibrosis / Q000378:metabolism / Q000473:pathology*; D003599:Cytoskeleton / Q000187:drug effects / Q000378:metabolism; D003600:Cytosol / Q000187:drug effects / Q000378:metabolism; D005260:Female; D006801:Humans; D007155:Immunologic Factors / Q000378:metabolism / Q000494:pharmacology; D015544:Inositol 1,4,5-Trisphosphate / Q000096:biosynthesis*; D042541:Intracellular Space / Q000187:drug effects / Q000378:metabolism*; D008297:Male; D008954:Models, Biological; D018375:Neutrophil Activation / Q000187:drug effects; D009504:Neutrophils / Q000187:drug effects / Q000378:metabolism* / Q000502:physiology; D010084:Oxidation-Reduction / Q000187:drug effects; D029424:Pulmonary Disease, Chronic Obstructive / Q000378:metabolism / Q000473:pathology*; D011994:Recombinant Proteins / Q000494:pharmacology; D053481:Secretory Leukocyte Peptidase Inhibitor / Q000378:metabolism*
D000893:Anti-Inflammatory Agents; D007155:Immunologic Factors; D011994:Recombinant Proteins; D053481:Secretory Leukocyte Peptidase Inhibitor; D015544:Inositol 1,4,5-Trisphosphate; D002118:Calcium