The effect of C-reactive protein deposition on myocardium with ischaemia–reperfusion injury in rats

OBJECTIVES: We evaluated the effect of monomeric C-reactive protein (CRP) deposition on areas at risk (AAR) of myocardium with ischaemia-reperfusion injury. METHODS: Myocardial ischaemia-reperfusion injury model was produced by ligation of the left anterior descending coronary artery for 45 min followed by 45 min of reperfusion using female Sprague-Dawley rats. Tissue from non-ischaemic areas, areas at risk and infarct areas determined by Evans blue and 2,3,5-triphenyltetrazolium chloride staining was obtained from the sham group, the ischaemia-reperfusion injury without C-reactive protein (CRP) injection group (I/R only group), and the ischaemia-reperfusion injury with CRP injection group (I/R + CRP group). We assessed the effect of CRP injection on infarct size, CRP deposition, CRP and IL-6 mRNA expression, the third component of complement (C3) immunodeposition and mitochondrial structural remodelling with apoptosis by quantitative RT-PCR analyses, immunohistochemistry, direct immunofluorescence, electron microscopy and Terminal deoxynucleotide transferase dUTP Nick End Labelling assay, respectively. All images were analysed using an automated morphology tool. RESULTS: The infarct area significantly increased in the I/R + CRP group compared to the I/R only group. The anti CRP antibody confirmed that CRP deposition occurred in both the infarct and area at risk (AAR) of the I/R + CRP group. The myocardium did not exhibit CRP mRNA expression, and the CRP treatment group showed a tendency for IL-6 to increase without statistical significance. Activated C3, apoptosis and mitochondrial destruction increased on AAR and infarct area in the I/R + CRP group. CONCLUSIONS: These results strongly suggest the active participation of the deposition of CRP on AAR in the progression of myocardial infarction following ischaemia-reperfusion injury, accompanied by complement activation and mitochondrial change.