Multimodality Molecular Profiling Nominates Targetable Mechanisms in Progressive RV Dysfunction

BACKGROUND: Right ventricular dysfunction (RVD) is a robust predictor of mortality in multiple cardiovascular diseases. Currently, it remains unclear whether the severity of RVD corresponds to distinct cellular and molecular alterations, and this has important implications for defining optimal therapeutic targets. To address this knowledge gap, we performed a multiomic evaluation of pulmonary artery banded pigs with differing degrees of right ventricular (RV) compromise. METHODS: Pulmonary artery banded pigs were stratified into mild and severe RVD groups based on RV ejection fraction (mild RVD, 38±4%; severe RVD, 20±8%). RV tissue from control, mild RVD, and severe RVD animals was analyzed using single-nucleus RNA sequencing, mitochondrial and cytoplasmic proteomics, and phosphoproteomics. Histological analyses corroborated multiomic findings. RESULTS: Cardiac magnetic resonance imaging revealed progressive structural and functional alterations in mild and severe RVD pigs. Single-nucleus RNA sequencing demonstrated that advancing RVD was associated with loss of cardiomyocytes, accumulation of efferocytosis-impaired macrophages, and dysregulated endothelial cells and pericytes. Combined transcriptomic and proteomic analyses showed escalating impairments of complex cardiomyocyte metabolism with worsening RVD. RV microvasculature was compromised with severe RVD as there were alterations in endothelial cell/pericyte genetic regulation, colocalization patterns in RV sections, and increased cardiomyocyte HIF1A (hypoxia-inducible factor 1 alpha) transcript expression. Analysis of both mitochondrial and global proteostasis revealed greater compromise in mitochondrial proteostasis, including downregulation of mitochondrial proteases, chaperones, and ribosomes. Paradoxically, cytoplasmic ribosomes were upregulated in severe RVD. The predicted kinome and phosphatome were uniquely altered in mild RVD as compared with severe RVD. Finally, integration of multiomic approaches identified activation of the ribotoxic stress response, impaired macrophage efferocytosis, and insufficient mitochondrial unfolded protein response as potential contributors to severe RVD. Multispecies comparison suggested that the ribotoxic stress response was the most conserved pathogenic response in RVD. CONCLUSIONS: Our multiomic analysis defines the cellular and molecular landscape of progressive RVD and nominates druggable pathways that may promote progressive RVD. Future studies are needed to determine how engaging these pathways influences RV phenotypes.