title: Induction of macrophage matrix metalloproteinase biosynthesis by surfactant protein D.
abstract: Recent studies strongly suggest that surfactant protein D (SP-D) plays important roles in pulmonary host defense and the regulation of immune and inflammatory reactions in the lung. Although SP-D can bind to alveolar macrophages and can elicit their chemotaxis, relatively little is known about the direct cellular consequences of SP-D on the function of these cells. Because matrix metalloproteinases (MMPs) are synthesized in increased amounts in response to various proinflammatory stimuli, we investigated the capacity of SP-D to modulate the production of MMPs by freshly isolated human alveolar macrophages. Unexpectedly we found that recombinant rat SP-D dodecamers selectively induce the biosynthesis of collagenase-1 (MMP-1), stromelysin (MMP-3), and macrophage elastase (MMP-12) without significantly increasing the production of tumor necrosis factor alpha and interleukin-1beta. SP-D did not alter the production of these MMPs by fibroblasts. Phosphatidylinositol, a surfactant-associated ligand that interacts with the carboxyl-terminal neck and carbohydrate recognition domains of SP-D, inhibited the SP-D-dependent increase in MMP biosynthesis. A trimeric, recombinant protein consisting of only the neck and carbohydrate recognition domain did not augment metalloproteinase production, suggesting that the stimulatory effect on MMP production depends on an appropriate spatial presentation of trimeric lectin domains. Although SP-D dodecamers can selectively augment metalloproteinase activity in vitro, this effect may be competitively inhibited by tissue inhibitors of metalloproteinases or surfactant-associated ligands in vivo.
authors.affiliation: Department of Pediatrics, Washington University School of Medicine at St. Louis Children's and Barnes-Jewish Hospitals, St. Louis, Missouri 63110, USA.
authors.forename: B C
authors.initials: BC
authors.lastname: Trask
authors.forename: M J
authors.initials: MJ
authors.lastname: Malone
authors.forename: E H
authors.initials: EH
authors.lastname: Lum
authors.forename: H G
authors.initials: HG
authors.lastname: Welgus
authors.forename: E C
authors.initials: EC
authors.lastname: Crouch
authors.forename: S D
authors.initials: SD
authors.lastname: Shapiro
mesh_terms: D000818:Animals; D001704:Biopolymers; D016466:CHO Cells; D006224:Cricetinae; D004790:Enzyme Induction; D006023:Glycoproteins / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D016676:Macrophages, Alveolar / Q000187:drug effects* / Q000201:enzymology; D020782:Matrix Metalloproteinases / Q000096:biosynthesis*; D010716:Phosphatidylinositols / Q000494:pharmacology; D037663:Pulmonary Surfactant-Associated Protein D; D011663:Pulmonary Surfactants / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D051381:Rats; D011994:Recombinant Proteins / Q000037:antagonists & inhibitors / Q000494:pharmacology
chemical_list: D001704:Biopolymers; D006023:Glycoproteins; D010716:Phosphatidylinositols; D037663:Pulmonary Surfactant-Associated Protein D; D011663:Pulmonary Surfactants; D011994:Recombinant Proteins; D020782:Matrix Metalloproteinases