Myeloperoxidase-dependent inactivation of surfactant protein D in vitro and in vivo

Academic Article

Abstract

  • Surfactant protein D (SP-D) plays diverse and important roles in innate immunity and pulmonary homeostasis. Neutrophils and myeloperoxidase (MPO) colocalized with SP-D in a murine bacterial pneumonia model of acute inflammation, suggesting that MPO-derived reactive species might alter the function of SP-D. Exposure of SP-D to the completeMPO-H2O 2-halide system caused loss of SP-D-dependent aggregating activity. Hypochlorous acid (HOCI), the major oxidant generated by MPO, caused a similar loss of aggregating activity, which was accompanied by the generation of abnormal disulfide-cross-linked oligomers. A full-length SP-D mutant lacking N-terminal cysteine residues and truncation mutants lacking the N-terminal domains were resistant to the oxidant-induced alterations in disulfide bonding. Mass spectroscopy of HOCI-treated human SP-D demonstrated several modifications, but none involved key ligand binding residues. There was detectable oxidation of cysteine 15, but no HOCl-induced cysteine modifications were observed in the C-terminal lectin domain. Together, the findings localize abnormal disulfide cross-links to the N-terminal domain. MPO-deficient mice showed decreased cross-linking of SP-D and increased SP-D-dependent aggregating activity in the pneumonia model. Thus, MPO-derived oxidants can lead to modifications of SP-D structure with associated alterations in its characteristic aggregating activity. © 2010 by The American Society for Biochemistry and Molecular Biology, Inc.
  • Authors

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    Digital Object Identifier (doi)

    Author List

  • Crouch EC; Hirche TO; Shao B; Boxio R; Wartelle J; Benabid R; McDonald B; Heinecke J; Matalon S; Belaaouaj A
  • Start Page

  • 16757
  • End Page

  • 16770
  • Volume

  • 285
  • Issue

  • 22