CCN5 Reverses Fibrosis and Cardiac Dysfunction Induced by Pressure Overload in Murine Models

Abstract

Introduction: Cardiac fibrosis (CF) is associated with increased stiffness and diastolic dysfunction in failing hearts, and its severity is an independent predictor for clinical outcomes of heart failure patients. We previously showed that a matricellular protein CCN5 is anti-fibrotic and anti-hypertrophic in the mouse heart. However, the mechanisms involved in the anti-fibrotic activity of CCN5 remains unknown.

Methods: In this study, we tested two different animal models. First, we generated pressure-overload heart failure models in mouse by TAC operation. Two months following gene transfer of CCN5, cardiac function was evaluated by echocardiography and invasive hemodynamics. Second, endothelial cells were recently shown to significantly contribute to CF through Endothelial-Mesenchymal Transition (EndoMT). Thus, we tested whether CCN5 inhibits EndoMT using the Scl-Cre-ERT; R26RstopYFP double Tg mouse, which is a widely used lineage traceable animal model. Protein and RNA expression levels of CCN5, several types of collagen and onventional TGF-beta signaling related genes were measured by western blot and RT-PCR analysis. Cell growth assay and apoptosis assay were also performed to evaluate the function of CCN5 in isolated rat adult cardiomyocytes and non-cardiomyocyte cells. Third, EndoMT and transdifferentiation assays were performed using human coronary endothelial cells (HCEC) and myofibroflast in vitro.

Results: First, CCN5 induces accelerated degradation of preformed fibrogenic materials like collagen in the heart. CCN5 reduces the fraction of Vimentin-positive fibroblasts that have already expanded in response to TAC. Second, our data showed that CCN5 can inhibit EndoMT both in vivo and in vitro. Finally, we found that CCN5 selectively induced apoptosis in myofibroblasts but not in cardiomyocytes or fibroblasts.

Conclusions: CCN5 evoked reversal of preformed CF, which was accompanied by functional recovery of the failing hearts through the inhibition of transdifferentiation into myofibroblast and selective induction of apoptosis on myofibroblasts. Taken together, our results that CCN5 can effectively target fibrosis in the setting of heart failure.