: J Clin Invest 2002 Mar 1;109(5):661-670 Related Articles, Books, LinkOut
Elastase-mediated phosphatidylserine receptor cleavage impairs apoptotic cell clearance in cystic fibrosis and bronchiectasis.
Vandivier RW, Fadok VA, Hoffmann PR, Bratton DL, Penvari C, Brown KK, Brain JD, Accurso FJ, Henson PM.
Division of Pulmonary Sciences and Critical Care Medicine, Department of Medicine, University of Colorado Health Sciences Center, Denver, Colorado, USA. Program in Cell Biology, Department of Pediatrics, and. Department of Pediatrics, National Jewish Medical and Research Center, Denver, Colorado, USA. Department of Pediatrics, University of Colorado Health Sciences Center, Mike McMorris Cystic Fibrosis Center, Children's Hospital, Denver, Colorado, USA. Department of Medicine, National Jewish Medical and Research Center, Denver, Colorado, USA. Physiology Program, Department of Environmental Health, Harvard School of Public Health, Boston, Massachusetts, USA.
Cystic fibrosis is characterized by an early and sustained influx of inflammatory cells into the airways and by release of proteases. Resolution of inflammation is normally associated with the orderly removal of dying apoptotic inflammatory cells through cell recognition receptors, such as the phosphatidylserine receptor, CD36, and alphav integrins. Accordingly, removal of apoptotic inflammatory cells may be impaired in persistent inflammatory responses such as that seen in cystic fibrosis airways. Examination of sputa from cystic fibrosis and non--cystic fibrosis bronchiectasis patients demonstrated an abundance of apoptotic cells, in excess of that seen in patients with chronic bronchitis. In vitro, cystic fibrosis and bronchiectasis airway fluid directly inhibited apoptotic cell removal by alveolar macrophages in a neutrophil elastase-dependent manner, suggesting that elastase may impair apoptotic cell clearance in vivo. Flow cytometry demonstrated that neutrophil elastase cleaved the phosphatidylserine receptor, but not CD36 or CD32 (FcgammaRII). Cleavage of the phosphatidylserine receptor by neutrophil elastase specifically disrupted phagocytosis of apoptotic cells, implying a potential mechanism for delayed apoptotic cell clearance in vivo. Therefore, defective airway clearance of apoptotic cells in cystic fibrosis and bronchiectasis may be due to elastase-mediated cleavage of phosphatidylserine receptor on phagocytes and may contribute to ongoing airway inflammation.
Am J Respir Cell Mol Biol 2002 Mar 1;26(3):290-297 Related Articles, Books, LinkOut
Protection Against Acute Lung Injury by Intravenous or Intratracheal Pretreatment with EPI-HNE-4, a New Potent Neutrophil Elastase Inhibitor.
Delacourt C, Herigault S, Delclaux C, Poncin A, Levame M, Harf A, Saudubray F, Lafuma C.
Institut National de la Sante et de la Recherche Scientifique, Faculte de Medecine, Creteil, France; Service de Pediatrie, Hopital Intercommunal, Creteil, France; Service de Physiologie, Hopital Henri-Mondor, Creteil, France; Eurogentec, Serain, Belgium; and Debiopharm SA, Lausanne, Switzerland.
Excessive accumulation of active neutrophil elastase (NE) in pulmonary fluids and tissues of patients with cystic fibrosis (CF) is thought to act on the lungs, compromising their structure and function. The aim of this study was to investigate the in vitro and in vivo protective effect of a new, rapidly acting, potent (Ki = 5.45 x 10(minus sign)(12) M and Kon = 8 x 10(6) M(minus sign)(1) s(minus sign)(1)) and specific human NE inhibitor, EPI-HNE-4, engineered from the Kunitz domain. The results demonstrated that this inhibitor was able to (i) effectively inhibit in vitro the high levels of active NE present in a medium as complex as sputum from children with CF, with a measured IC(50) equal or close to the calculated IC(50) in 60% of cases, and (ii) almost completely block (91%) the N-formyl-methionine-leucine-phenylalanine-induced migration of purified human neutrophils across a Matrigel basement membrane. Intratracheal administration (250, 175, or 100 mug per rat) of the inhibitor 5 min before instillation of pure human NE (HNE) (150 mug per rat) to rats induced effective, dose-dependent protection of the lungs, 4 h later, from hemorrhage, serum albumin leakage, residual active NE, and discrete neutrophil influx in air spaces induced by instillation of pure HNE. Intravenous administration (3 mg per rat) of EPI-HNE-4, 15 min before instillation of the soluble fraction of pooled sputum (delivering 120 mug of active NE per rat) from children with CF, effectively reduced (64%), 4 h later, the massive neutrophil influx induced by sputum instillation. Overall, these data strongly suggest that associated aerosol and systemic administration of EPI-HNE-4 would be beneficial in the treatment of CF. |
