title: Treatment with activated protein C (aPC) is protective during the development of myocardial fibrosis: an angiotensin II infusion model in mice.
abstract: OBJECTIVE
  Myocardial fibrosis contributes to the development of heart failure. Activated Protein C (aPC) is a circulating anticoagulant with anti-inflammatory and cytoprotective properties. Using a model of myocardial fibrosis second to Angiotensin II (AngII) infusion, we investigated the novel therapeutic function aPC in the development of fibrosis.
  
  
  RESULTS
  C57Bl/6 and Tie2-EPCR mice were infused with AngII (2.0 µg/kg/min), AngII and aPC (0.4 µg/kg/min) or saline for 3d. Hearts were harvested and processed for analysis or used for cellular isolation. Basic histology and collagen deposition were assessed using histologic stains. Transcript levels of molecular mediators were analyzed by quantitative RT-PCR. Mice infused with AngII exhibited multifocal areas of myocardial cellular infiltration associated with significant collagen deposition compared to saline control animals (p<0.01). AngII-aPC infusion inhibited this cellular infiltration and the corresponding collagen deposition. AngII-aPC infusion also inhibited significant expression of the pro-fibrotic cytokines TGF-β1, CTGF and PDGF found in AngII only infused animals (p<0.05). aPC signals through its receptor, EPCR. Using Tie2-EPCR animals, where endothelial cells over-express EPCR and exhibit enhanced aPC-EPCR signaling, no significant reduction in cellular infiltration or fibrosis was evident with AngII infusion suggesting aPC-mediate protection is endothelial cell independent. Isolated infiltrating cells expressed significant EPCR transcripts suggesting a direct effect on infiltrating cells.
  
  
  CONCLUSIONS
  This data indicates that aPC treatment abrogates the fibrogenic response to AngII. aPC does not appear to confer protection by stimulating the endothelium but by acting directly on the infiltrating cells, potentially inhibiting migration or activation.
authors.affiliation: Department of Pathology, Dalhousie University, Halifax, Nova Scotia, Canada.
authors.forename: Mryanda J
authors.initials: MJ
authors.lastname: Sopel
authors.forename: Nicole L
authors.initials: NL
authors.lastname: Rosin
authors.forename: Alec G
authors.initials: AG
authors.lastname: Falkenham
authors.forename: Michael
authors.initials: M
authors.lastname: Bezuhly
authors.forename: Charles T
authors.initials: CT
authors.lastname: Esmon
authors.forename: Timothy D G
authors.initials: TD
authors.lastname: Lee
authors.forename: Robert S
authors.initials: RS
authors.lastname: Liwski
authors.forename: Jean-Francois
authors.initials: JF
authors.lastname: Légaré
mesh_terms: D000804:Angiotensin II / Q000008:administration & dosage*; D000818:Animals; D001483:Base Sequence; D016207:Cytokines / Q000378:metabolism; D017931:DNA Primers; D004195:Disease Models, Animal; D005355:Fibrosis / Q000378:metabolism / Q000517:prevention & control*; D005455:Fluorescent Antibody Technique; D006331:Heart Diseases / Q000378:metabolism / Q000517:prevention & control*; D020287:In Situ Nick-End Labeling; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D011486:Protein C / Q000494:pharmacology*; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: D016207:Cytokines; D017931:DNA Primers; D011486:Protein C; D000804:Angiotensin II