Following myocardial ischemia, extracellular matrix (ECM) deposition occurs at the site of the focal injury and at the border region.Methods and Results
We have applied a conceptually novel proteomic method for the analysis of ECM in cardiovascular tissues to a porcine model of ischemia-reperfusion injury. ECM proteins were sequentially extracted and identified by liquid chromatography tandem mass spectrometry. For the first time, ECM proteins, such as cartilage intermediate layer protein 1 (CILP-1), matrilin-4, extracellular adipocyte enhancer binding protein 1 (AEBP-1), collagen alpha-1 (XIV) and several members of the small leucine-rich proteoglycan family, including asporin and prolargin, were shown to contribute to cardiac remodeling. A comparison in two distinct cardiac regions at day 15 (the focal injury in the left ventricle and the border regionclose to the occluded coronary artery) revealed a discordant regulation of protein and messenger RNA levels: while gene expression for selected ECM proteins was similar in both regions, the corresponding protein levels were much higher in the focal lesion. Certain cartilage-related proteins, such as aggrecan, were only found at day 60 post injury. Principal component analysis and network inference based on more than hundred ECM proteins delineated asignature of early and late stage cardiac remodelling with transforming growth factor beta 1 (TGFβ-1) signalling being at the centre of the interaction network. Notably, interactions for CILP-1, asporin or aggrecan had to beinferred from experiments on other tissues, i.e. cartilage, since these proteins are currently not in public cardiac matrix interaction databases. Finally, novel cardiac ECM proteins identified by proteomics were validated in human left ventricular tissue acquired from ischemic cardiomyopathy patients at cardiac transplantation.Conclusions
Our proteomic analysis of cardiac ECM remodeling revealed previously unknown cardiac ECM components. This bio-signature of early and late stage ECM remodeling after myocardial ischemia-reperfusion injury may have clinical utility as prognostic markers and modifiable targets for drug discovery.