Abstract 056: The Impact of Periostin as A Regulator of Cardiac Remodeling

Background: Periostin (PN) is a matricellular protein that is induced by mechanostress and regulates organ remodeling. We previously documented that over-expression of full-length periostin (periostin1:Pn1) resulted in ventricular dilation with enhanced interstitial collagen deposition. Controversially, supplement of PN splicing variant lacking exon 17 (periostin2:Pn2) was reported to accelerate cardiac repair with the induction of cardiomyocyte proliferation and angiogenesis. The aim of this study was to investigate the different roles of PN splicing isoforms in cardiac remodeling. Methods: Coronary ligation was employed to induce cardiac remodeling in rat. A neutralizing antibody against exon17 (Pn1Ab) was injected intravenously every 6 days until day 21. Mice were followed ultrasonographically and then euthanized for histological analysis at day 56. In vitro study, the effect of each PN splicing isoform was assessed in rat cardiac fibroblast and HUVEC. Results: Administration of Pn1Ab resulted in 24.1 % decrease in infarct size and 38.2 % decrease in fibrotic area at day 56 post-operation (n=21, P<0.05). Consistently, echocardiography demonstrated 26.3 % better ejection fraction (P<0.05). Inhibition of fibrosis was associated with suppressed fibrosis-related gene expression such as collagen I, collagen III and TGF-beta1. Importantly, the number of myofibroblasts was significantly reduced in the Pn1Ab group, while neither cardiomyocyte proliferation nor angiogenesis was detected. In vitro study, Pn2 administration for HUVEC induced proliferation and tube formation however Pn1 did not. Pn1 administration accelerated maturation of myofibroblast more than Pn2. Conclusions: Pn1Ab preserved cardiac function through anti-fibrotic effect without cardiomyocyte proliferation and angiogenesis. Specific blockade of Pn1 without Pn2 will potentially lead to new therapeutic targets on a molecular basis to limit cardiac remodeling.