title: Poractant alfa (Curosurf®) increases phagocytosis of apoptotic neutrophils by alveolar macrophages in vivo.
abstract: BACKGROUND
  Clearance of apoptotic neutrophils in the lung is an essential process to limit inflammation, since they could become a pro-inflammatory stimulus themselves. The clearance is partially mediated by alveolar macrophages, which phagocytose these apoptotic cells. The phagocytosis of apoptotic immune cells by monocytes in vitro has been shown to be augmented by several constituents of pulmonary surfactant, e.g. phospholipids and hydrophobic surfactant proteins. In this study, we assessed the influence of exogenous poractant alfa (Curosurf®) instillation on the in vivo phagocytosis of apoptotic neutrophils by alveolar macrophages.
  
  
  METHODS
  Poractant alfa (200 mg/kg) was instilled intratracheally in the lungs of three months old adult male C57/Black 6 mice, followed by apoptotic neutrophil instillation. Bronchoalveloar lavage was performed and alveolar macrophages and neutrophils were counted. Phagocytosis of apoptotic neutrophils was quantified by determining the number of apoptotic neutrophils per alveolar macrophages.
  
  
  RESULTS
  Exogenous surfactant increased the number of alveolar macrophages engulfing apoptotic neutrophils 2.6 fold. The phagocytosis of apoptotic neutrophils was increased in the presence of exogenous surfactant by a 4.7 fold increase in phagocytosed apoptotic neutrophils per alveolar macrophage.
  
  
  CONCLUSIONS
  We conclude that the anti-inflammatory properties of surfactant therapy may be mediated in part by increased numbers of alveolar macrophages and increased phagocytosis of apoptotic neutrophils by alveolar macrophages.
authors.affiliation: Department of Pediatrics, School for Mental Health and Neuroscience (NUTRIM), School for Oncology and Developmental Biology (GROW), Maastricht University Medical Centre, Maastricht, The Netherlands.
authors.forename: Coen Hmp
authors.initials: CH
authors.lastname: Willems
authors.forename: Florian
authors.initials: F
authors.lastname: Urlichs
authors.forename: Silvia
authors.initials: S
authors.lastname: Seidenspinner
authors.forename: Steffen
authors.initials: S
authors.lastname: Kunzmann
authors.forename: Christian P
authors.initials: CP
authors.lastname: Speer
authors.forename: Boris W
authors.initials: BW
authors.lastname: Kramer
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D001688:Biological Products / Q000494:pharmacology*; D001992:Bronchoalveolar Lavage Fluid / Q000166:cytology; D002478:Cells, Cultured; D016676:Macrophages, Alveolar / Q000187:drug effects*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D009504:Neutrophils / Q000187:drug effects*; D010587:Phagocytosis / Q000187:drug effects*; D010743:Phospholipids / Q000494:pharmacology*; D011663:Pulmonary Surfactants / Q000494:pharmacology*
chemical_list: D001688:Biological Products; D010743:Phospholipids; D011663:Pulmonary Surfactants; C068291:poractant alfa