title: Surfactant protein A suppresses lipopolysaccharide-induced IL-10 production by murine macrophages.
abstract: Upon LPS exposure, mononuclear phagocytes produce TNF-alpha and IL-10, two cytokines with pro- and anti-inflammatory activities, respectively. We previously described that murine resident alveolar macrophages, which play a central role in the immunosurveillance of the lung alveoli, do not synthesize IL-10 in vivo or in vitro when exposed to LPS. In the present report we demonstrate that during lung inflammation induced by the intranasal administration of LPS, bronchoalveolar cells collected between days 3 and 5 are able to synthesize IL-10 when exposed to LPS. We also show that depletion of resident alveolar macrophages by an intratracheal instillation of liposome-encapsulated clodronate is followed by subsequent replenishment of the airspaces by mononuclear phagocytes. This is accompanied by the transient competence of cells for IL-10 production. The cell capacity to produce IL-10 is evident up to 3 days and then decreases. This led us to hypothesize that the alveolar environment contains a down-regulator of LPS-induced IL-10 synthesis by recently emigrating mononuclear phagocytes. We show that the surfactant protein A, an airspace protein that has known immunomodulatory activities, dramatically inhibits LPS-induced IL-10 formation by bone marrow-derived macrophages. These data show a difference between resident and inflammatory macrophages with respect to IL-10 synthesis. Moreover, this study highlights for the first time the inhibitory role of surfactant protein A in the anti-inflammatory activity of macrophages through inhibition of IL-10 production.
authors.affiliation: Unité de Pharmacologie Cellulaire, Unité Associée Institut Pasteur/Institut National de la Santé et de la Recherche Médicale, Paris, France.
authors.forename: L
authors.initials: L
authors.lastname: Salez
authors.forename: V
authors.initials: V
authors.lastname: Balloy
authors.forename: N
authors.initials: N
authors.lastname: van Rooijen
authors.forename: M
authors.initials: M
authors.lastname: Lebastard
authors.forename: L
authors.initials: L
authors.lastname: Touqui
authors.forename: F X
authors.initials: FX
authors.lastname: McCormack
authors.forename: M
authors.initials: M
authors.lastname: Chignard
mesh_terms: D000818:Animals; D001854:Bone Marrow Cells / Q000276:immunology / Q000378:metabolism; D001992:Bronchoalveolar Lavage Fluid / Q000166:cytology / Q000276:immunology; D002465:Cell Movement / Q000276:immunology; D002469:Cell Separation; D006801:Humans; D007166:Immunosuppressive Agents / Q000494:pharmacology*; D007249:Inflammation / Q000276:immunology / Q000473:pathology; D016753:Interleukin-10 / Q000037:antagonists & inhibitors* / Q000096:biosynthesis*; D008070:Lipopolysaccharides / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D008168:Lung / Q000276:immunology / Q000473:pathology; D016676:Macrophages, Alveolar / Q000276:immunology* / Q000378:metabolism* / Q000473:pathology; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D009000:Monocytes / Q000276:immunology / Q000378:metabolism / Q000473:pathology; D011510:Proteolipids / Q000494:pharmacology*; D037661:Pulmonary Surfactant-Associated Proteins; D011663:Pulmonary Surfactants / Q000494:pharmacology*
chemical_list: D007166:Immunosuppressive Agents; D008070:Lipopolysaccharides; D011510:Proteolipids; D037661:Pulmonary Surfactant-Associated Proteins; D011663:Pulmonary Surfactants; D016753:Interleukin-10