title: Involvement of Angiotensin II Type 1 and 2 Receptors in Gelatinase Regulation in Human Carotid Atheroma in vitro.
abstract: OBJECTIVE
  Matrix metalloproteinases (MMPs), angiotensin II (AII) and its receptors are implicated in atherosclerotic plaque instability, however the roles of the two receptor subtypes, ATR1 and ATR2, in MMP regulation remain uncertain. In this study, we investigated the effect of ATR1 and ATR2 blockade on the expression and activity of MMP-2, MMP-3 and MMP-9, in human carotid atheroma.
  
  
  METHODS
  Atheroma samples (n=36) were obtained from patients undergoing carotid endarterectomy. The effects of ATR1 (irbesartan), ATR2 (PD123319) and combined ATR1 and ATR2 blockade on the expression and activity of the MMPs and the expression of tissue inhibitors of metalloproteinases (TIMPs) were investigated in explant culture experiments. Paired atheroma samples were incubated with the intervention or media control for 4 days. Protein levels (MMP-2, MMP-3, MMP-9, TIMP-1, TIMP-2, TIMP-4, ATR1 and ATR2) were determined by ELISA. Overall gelatinase activity and specific activation were measured by chromogenic activity assays and zymography, respectively.
  
  
  RESULTS
  ATR1 blockade, but not ATR2 blockade significantly reduced TIMP-1, TIMP-2 and TIMP-4 expression in atheroma supernatant. Combined ATR1 and ATR2 blockade significantly reduced MMP-2, MMP-3 and MMP-9 expression. MMP-2 and MMP-9 relative activation, and overall MMP-9 catalytic capacity were significantly increased by ATR1 blockade.
  
  
  CONCLUSIONS
  Our findings suggest that ATR1 blockade reduces TIMP expression and increases gelatinase activity in human carotid atheroma.
authors.affiliation: Health practitioners And Researchers Together-Blood, Endothelium And Tissue (HART-BEAT), Biomedicine, Australian Institute for Tropical Health and Medicine, College of Public Health, Medical & Veterinary Sciences, James Cook University.
authors.forename: Paula
authors.initials: P
authors.lastname: Clancy
authors.forename: Simon
authors.initials: S
authors.lastname: Koblar
authors.forename: Jonathan
authors.initials: J
authors.lastname: Golledge
mesh_terms: D000368:Aged; D000804:Angiotensin II / Q000378:metabolism*; D015153:Blotting, Western; D002340:Carotid Artery Diseases / Q000378:metabolism* / Q000503:physiopathology; D004797:Enzyme-Linked Immunosorbent Assay; D018093:Gelatinases / Q000378:metabolism*; D015971:Gene Expression Regulation, Enzymologic; D006801:Humans; D066298:In Vitro Techniques; D008297:Male; D058226:Plaque, Atherosclerotic / Q000378:metabolism* / Q000503:physiopathology; D044140:Receptor, Angiotensin, Type 1 / Q000378:metabolism*; D044139:Receptor, Angiotensin, Type 2 / Q000378:metabolism*
chemical_list: D044140:Receptor, Angiotensin, Type 1; D044139:Receptor, Angiotensin, Type 2; D000804:Angiotensin II; D018093:Gelatinases