Gene expression signals involved in ischemic injury, extracellular matrix composition and fibrosis defined by global mRNA profiling of the human left ventricular myocardium

Gene expression signals involved in ischemic injury, extracellular matrix composition and fibrosis defined by global mRNA profiling of the human left ventricular myocardium. The mechanism(s) by which acute and chronic myocardial ischemia translate into the characteristic features of ischemic cardiomyopathy is unresolved at present. We hypothesized that such translation relates to modification of specific gene expression programs during acute and chronic ischemic insults to the myocardium. Global mRNA expression profiles by Affymetrix HG_U133A GeneChip analysis on 33 samples was performed on non-failing human left ventricular myocardium during acute and chronic ischemia in 6 patients undergoing coronary artery by-pass grafting. Results were confirmed by real-time quantitative RT-PCR in 14 patients and supported by histology and immunohistochemistry analyses. Acute ischemia elicited an acute inflammatory response including IL-6, IL-8, MCP-1, VCAM-1 and CYR-61 with an attenuated increase of IL-6 and IL-8 in chronic ischemic myocardium compared to normal myocardium. High mRNA expression of connective tissue growth factor (CTGF) was present in chronic ischemic myocardium with a high degree of correlation between CTGF and mRNA expression of specific genes (e.g. thrombospondin 4, collagen type Ialpha2, versican, adlican, latent transforming growth factor beta binding protein 2 and fibronectin) involved in extracellular matrix remodelling. In conclusion, acute inflammatory induction (e.g. IL-8, IL-6, VCAM-1 and MCP-1) and an acute phase CCN family gene with effects on matrix interactions (CYR-61) might play important roles in the coupling between acute ischemic episodes and chronic myocardial remodelling. In addition, the findings support an important role of CTGF signalling in chronic extracellular matrix remodelling in chronic coronary artery disease.