Background: Inflammation plays a critical role in all stages of atherogenesis, including plaque destabilization leading to the rupture and local thrombosis, clinically manifested as unstable angina (UA) or myocardial infarction (MI). Recent data report enhanced expression of numerous pro-inflammatory genes in patients with acute coronary syndrome (ACS) both in plaque and in inflammatory cells. Kinins are peptides involved in vasodilation, vascular permeability, pain and inflammation. Their effects are mediated by two receptors, B1 and B2. As the role of kinins in ACS is not clear, the aim of the study was to assess the expression of the genes encoding kinin receptors in patients with ACS.
Methods: The study was carried out on 40 patients with ACS and 10 age-matched healthy subjects (control (C)). To evaluate gene expression of B1 and B2 kinin receptors, total mRNA was extracted from peripheral blood mononuclear cells and the number of mRNA copies was assessed by quantitative reverse transcriptase-polymerase chain reaction.
Results: In patients with MI and UA, the B1 receptor (B1R)/B2 receptor (B2R) ratio was inversed compared with healthy subjects (C group) (MI vs C: 1.54 +/- 0.39 vs 0.36 +/- 0.04; P < 0.01; UA vs C: 2.13 +/- 0.98 vs 0.36 +/- 0.04; P < 0.05 respectively). B2R gene mRNA level was markedly lower in MI group versus C group (24 216 +/- 5409 copies/microg vs 39 908 +/- 5309 copies/microg; P < 0.05). The difference in B1R gene expression between MI and C group was negligible. We have not observed differences in studied genes expression between UA and C groups.
Conclusion: Patients with ACS show inverted B1R/B2R ratio. Such disturbance in kinin signalling may reflect increased activation of circulating mononuclears, which are important participants of atherosclerotic plaque development and eventually rupture.