PROJECT SUMMARY/ABSTRACT
Portopulmonary Hypertension (PoPH) is a type of pulmonary arterial hypertension (PAH) that occurs
exclusively in patients with underlying liver disease. PoPH exhibits the highest morbidity and mortality of all
PAH subtypes, affecting 10% of all chronic liver disease patients, but the mechanisms that drive disease
pathogenesis are poorly understood. Liver portal hypertension and hepatocellular dysfunction are believed to
contribute to vascular remodeling in PoPH through dysregulation of important pathways such as vascular
endothelial growth factor (VEGF) signaling. The current diagnostic and prognostic biomarker used in clinical
practice (circulating brain natriuretic peptide, BNP) is a nonspecific marker of elevated pressure and weakly
correlated with disease severity (mean pulmonary arterial pressure, mPAP, and pulmonary vascular
resistance, PVR) in PoPH. Consequently, there is a critical need to develop new PoPH-specific biomarkers
with diagnostic and prognostic value. Next generation sequencing can isolate and study relevant stellate and
endothelial cell populations in PoPH, that are likely to affect important signaling pathways (such as VEGF) and
contribute to the pathogenesis of PoPH.
The purpose of this NIH K23 proposal is to use a multidisciplinary approach combining integrated next
generation sequencing analysis of liver tissue with biorepository validation to develop novel PoPH-specific
circulating peptide biomarkers with diagnostic and prognostic value. We will accomplish this goal by applying
single nuclear RNA sequencing to liver tissue and serum samples from PoPH and non-PoPH cirrhotic patients,
focusing on biologically plausible pathways such as VEGF signaling, to identify novel disease-specific
biomarkers. We will validate these biomarkers using biological samples and clinical data obtained from existing
large well-phenotyped disease biorepositories such as the PAH National Biological Sample and Data
Repository. Our preliminary data has identified circulating VEGF1 receptor protein (FLT1) and Protein Kinase
C Alpha subunit (PRKCA) as a promising PoPH-specific candidate biomarkers with diagnostic value. Using
BNP as a comparator, we will complete the following aims: Aim 1– Determine the differential gene expression
of PoPH endothelial and stellate cells; Aim 2 – Develop FLT1 and PRKCA as biomarkers able to discriminate
PoPH from liver cirrhosis and assess PoPH disease severity; Aim 3 – Develop FLT1 and PRKCA as predictive
biomarkers of treatment response in PoPH. This project is highly relevant to public health because of the
increasing incidence and prevalence, and clinical significance of PoPH and chronic liver disease. Successful
completion of these aims will develop novel PoPH-specific biomarkers with clinical value, train the candidate to
further develop these biomarkers as risk-stratification tools and therapeutic targets in PoPH, and ultimately
improve the clinical care of patients with pulmonary vascular disease due to liver disease.