Pulmonary arterial hypertension (PAH) is a highly morbid cardiopulmonary disease characterized by an obliterative vasculopathy involving distal pulmonary arterials that promotes right heart failure. Complex and integrated pathobiological signaling pathways drive vascular remodeling in PAH: the arteriopathy includes numerous endophenotypes (i.e., specific features, such as fibrosis, cellular proliferation, others) that occur to differing extent across patients. Wide variability in the proteomic and genetic profile is also observed in PAH, which accounts for phenotypic heterogeneity and inconsistent clinical response to drug therapies reported in clinical trials and at point-of-care. Overall, these observations suggest that opportunity exists to improve clinical outcome by individualizing the pathobiology-clinical phenotype relationship. Nonetheless, precision medicine in PAH remains unrealized, which we postulate is due to limitations inherent in conventional analytical methods that average biological data and overlook functionally important signaling pathways. Work from our laboratory and others has demonstrated the importance of studying functionally significant signaling pathways using network medicine to discover novel and modifiable therapeutic targets in PAH. This approach differs from classic reductionist methods that infer functionality based on transcript or protein quantity alone, which may erroneously implicate molecular bystanders in the pathogenesis of disease. However we have innovated a precision-based network medicine strategy that generates patient-specific protein-protein interaction (PPI) networks (e.g., patient-level molecular wiring map). Our approach unmasks molecular interactions that distinguish (and group together) individual patients with the same clinical phenotype. We present novel preliminary data in the accompanying application to support the central hypothesis: Developing patient- specific PPI networks will personalize clinical phenotyping and optimize prognosis in PAH. Our findings will also clarify the relationship between PAH genetic risk and pathobiology on an individual-patient level, and inform rationale and personalized drug selection using the PPI networks. To test our hypothesis, we will leverage a rich dataset from the United Kingdom PAH Phenome Biobank. This dataset includes comprehensive proteomic, genomic, clinical, and outcome data across two timepoints (1 yr apart) for idiopathic PAH, hereditary PAH, asymptomatic family members of patients with PAH, including three patients that developed PAH during the study, and healthy volunteer controls (N=500 total).
The Aims are: (1) Profile patient-specific PPI networks using proteomic and genetic data, and analyze temporal differences in network features by patient group, (2) Develop, test, and validate a network score that informs phenotype and outcome of individual PAH patients. As an exploratory aim, we will use the PPI networks to predict patient-specific drug therapies. Overall, findings from this project will advance precision medicine in PAH with direct relevance to the clinical management of patients.

Public Health Relevance

Pulmonary arterial hypertension (PAH) is a highly morbid cardiopulmonary disease characterized by wide differences in biology that underlies inconsistent treatment response. This suggests that PAH is likely to benefit from precision medicine, which aims to link unique molecular features with patient-specific clinical characteristics. In this proposal, we will study a new approach to precision medicine developed by our laboratory that focuses on protein-protein interactions to predict clinical characteristics, outcome, and optimal drug selection in individual PAH patients.

National Institute of Health (NIH)
National Heart, Lung, and Blood Institute (NHLBI)
Research Project (R01)
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Special Emphasis Panel (ZRG1)
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Xiao, Lei
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Brigham and Women's Hospital
United States
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