Surfactant protein D is expressed and modulates inflammatory responses in human coronary artery smooth muscle cells.
Surfactant protein D (SP-D) is a constituent of the innate immune system that plays a role in the host defense against lung pathogens and in modulating inflammatory responses. While SP-D has been detected in extrapulmonary tissues, little is known about its expression and function in the vasculature. Immunostaining of human coronary artery tissue sections demonstrated immunoreactive SP-D protein in smooth muscle cells (SMCs) and endothelial cells. SP-D was also detected in isolated human coronary artery SMCs (HCASMCs) by PCR and immunoblot analysis. Treatment of HCASMCs with endotoxin (LPS) stimulated the release of IL-8, a proinflammatory cytokine. This release was inhibited >70% by recombinant SP-D. Overexpression of SP-D by adenoviral-mediated gene transfer in HCASMCs inhibited both LPS- and TNF-alpha-induced IL-8 release. Overexpression of SP-D also enhanced uptake of Chlamydia pneumoniae elementary bodies into HCASMCs while attenuating IL-8 production induced by bacterial exposure. Both LPS and TNF-alpha increased SP-D mRNA levels by five- to eightfold in HCASMCs, suggesting that inflammatory mediators upregulate the expression of SP-D. In conclusion, SP-D is expressed in human coronary arteries and functions as an anti-inflammatory protein in HCASMCs. SP-D may also participate in the host defense against pathogens that invade the vascular wall.
Snyder
Gary D
GD
Department of Internal Medicine, University of Iowa Carver College of Medicine, Iowa City, IA, USA.
Oberley-Deegan
Rebecca E
RE
Goss
Kelli L
KL
Romig-Martin
Sara A
SA
Stoll
Lynn L
LL
Snyder
Jeanne M
JM
Weintraub
Neal L
NL
D002478:Cells, Cultured; D016993:Chlamydophila pneumoniae / Q000378:metabolism / Q000472:pathogenicity; D003331:Coronary Vessels / Q000378:metabolism; D042783:Endothelial Cells / Q000378:metabolism; D006801:Humans; D007113:Immunity, Innate; D007249:Inflammation / Q000276:immunology / Q000378:metabolism* / Q000517:prevention & control; D016209:Interleukin-8 / Q000378:metabolism; D008070:Lipopolysaccharides / Q000494:pharmacology; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000276:immunology / Q000378:metabolism*; D032389:Myocytes, Smooth Muscle / Q000187:drug effects / Q000276:immunology / Q000378:metabolism*; D010587:Phagocytosis; D037663:Pulmonary Surfactant-Associated Protein D / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism; D011994:Recombinant Proteins / Q000378:metabolism; D015398:Signal Transduction; D013997:Time Factors; D014161:Transduction, Genetic; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism
D016209:Interleukin-8; D008070:Lipopolysaccharides; D037663:Pulmonary Surfactant-Associated Protein D; D012333:RNA, Messenger; D011994:Recombinant Proteins; D014409:Tumor Necrosis Factor-alpha