Expression of the genes encoding kinin receptors are increased in human carotid atherosclerotic plaques

There is increasing evidence showing that inflammation occurs in atherosclerosis and contributes to the formation of atherosclerotic plaques. As important inflammatory peptides, kinins are increased in inflammation, eliciting vasodilation, increasing vascular permeability and recruiting inflammatory cells to the injury sites by activating specific receptors, B1 and B2. The two receptors have been reported to increase in inflammation, but their expressions remain to be defined in human carotid atherosclerotic plaques (CAP). In order to assess the gene expression of kinin receptors in human CAP, 47 CAP specimens were collected from patients undergoing endarterectomy and classified into stable and unstable plaque groups, respectively, with 10 mesenteric arteries used as controls. Total mRNA of B1R and B2R was extracted from CAPs and their levels were determined using reverse transcription-polymerase chain reaction. The expression of B1R and B2R mRNA was significantly upregulated in human CAPs compared to the control arteries. In the unstable plaques, the ratios of B1R to the β-actin mRNA level were significantly increased relative to the stable plaques. However, no notable differences were observed in the ratios of B2R to β-actin in mRNA expression between the stable and unstable plaques. The present study suggests that kinin-mediated inflammation involves the formation of atherosclerotic plaque and B1R plays an important role in plaque instability, indicating that kinin receptors can be used as potential targets for future therapeutic interventions.