Poster abstracts
Poster number 8 submitted by Madeline Burghaze
Right ventricular fibroblasts display unique metabolic signaling and activation in vitro
Madeline Burghaze (Department of Surgery, Cellular Molecular and Biochemical Sciences Training Program, Ohio State University Wexner Medical Center, Columbus, OH), Matthew Gorr (Department of Surgery, Ohio State University Wexner Medical Center, Columbus, OH)
Abstract:
Pulmonary hypertension is a cardiopulmonary disease that can lead to right ventricular (RV) fibrosis and failure due to pressure overload. The RV develops more severe fibrosis in response to pressure overload than the left ventricle (LV), which may contribute to the fact that clinical outcomes of RV failure are much worse than those found in left heart disease. As the RV has recently been found to contain a unique molecular and cellular makeup, we hypothesize that RV fibroblasts (RVfibs) carry out distinct mechanisms of activation that lead to exaggerated fibrosis in disease. To characterize fibroblast activation in vitro, we isolated LV fibroblasts (LVfibs) and RVfibs from the hearts of Sprague Dawley rats and found that RVfibs display greater proliferation, migration, mitochondrial and nonmitochondrial metabolic rates (p<0.05 via paired t-test). Additionally, they exhibit altered fibrotic gene expression profiles and an amplified response to stimulation with TGFβ (p<0.05 via paired t-test). To investigate the molecular mechanisms driving this hyperactive phenotype, we identified the Duox1 enzyme as an ROS source upregulated in RVfibs compared to LVfibs, which sustains TGFβ signaling in other cell types. We discovered that siRNA-mediated Duox1 knockdown promotes baseline fibrotic gene expression and attenuates RVfib TGFβ-induced expression (p<0.05 via paired t-test), in addition to reducing RVfib proliferation (p=0.06 via paired t-test). In contrast, Duox1 overexpression suppresses baseline fibrotic gene expression while exacerbating TGFβ-induced fibrotic gene expression (p<0.05 via paired t-test). Together, these results suggest that RVfibs are hyperactive, in part due to ROS-driven amplified TGFβ signaling, which may lead to their overactivation in disease to cause severe RV fibrosis. Duox1 may then be a novel target for effective treatment of pulmonary hypertension.
Keywords: Cardiovascular Disease, Fibrosis, TGFb Signaling