Antifibrotic Effect of CCN5 in a Murine Model of Heart Failure

Abstract

CCN family members are matricellular proteins with diverse roles in cell function. Recently, we showed that the differential expression of CCN2 and CCN5 during cardiac remodeling suggests that these two members of the CCN family play opposing roles during the development of cardiac hypertrophy and fibrosis. Since it is reported that an underlying morphological correlate of diastolic dysfunction is cardiac fibrosis, which leads to increased stiffness of the heart, we aimed to evaluate the role of CCN5 on cardiac fibrosis and function by the gene delivery using the cardiotropic AAV9 vector. We generated pressure-overload heart failure models in mouse by TAC operation. After 8-10 weeks of TAC on mice, HF was confirmed by Echocardiography. In those HF mice, AAV9-GFP (control) and AAV9-CCN5 were addressed by IV. Two more months later, cardiac function was evaluated by echocardiography and invasive hemodynamics. Protein and RNA expression levels of CCN5, several types of collagen and conventional TGF-beta signaling related genes were evaluated by western blot and quantitative real time PCR analysis. First, we were able to achieve about 4-5 fold increase of CCN5 expression by AAV9-CCN5 injection without any change in heart function. Second, CCN5 expression level in blood was not significantly altered after AAV9-CCN5 gene transfer because it may be the result of the cardiac tropism of the vector used. The HF model by TAC surgery was confirmed with echocardiography (FS (%)). Overall average FS (%) in HF was 41.87+/− 5.27 (n=16) and in non-surgery control mice was 58.39 +/− 2.06(n=4). After AAV9 injection, cardiac function of CCN5 injected mice was sustained but AAV9-GFP injected mice showed severe cardiac dysfunction and dilation (AAV-GFP (24.29+/− 9.11) vs AAV-CCN5 (42.66 +/− 4.73)). Third, western blot analysis showed that the downstream effectors, namely TGF-beta signaling pathways were significantly down-regulated in CCN5 injected mice. In addition, fibrotic area of the heart was tremendously reduced. Finally, CCN5 expression is significantly decreased in human heart failure patients compared to those in nonfailing donors. Taken together our data would indicate that CCN5 may be a promising therapeutic target to reduce cardiac fibrosis.