Abstract Body (Do not enter title and authors here): Background: Multiple studies of preclinical models and adults with pulmonary arterial hypertension (PAH) have shown new insights into PAH pathophysiology using high-throughput proteomics. However, application of similar techniques to pediatric PAH is lacking, limiting our understanding of the unique mechanisms and features of pediatric PAH and potentially improving outcomes.
Question: Can high-throughput proteomic profiling identify novel biomarkers of pediatric PAH that reflect disease severity and predict overall outcomes?
Methods: We used the Olink® Explore HT platform to analyze 86 serum samples from the NHLBI PAHbiobank (Table 1). This platform utilized Proximity Extension Assay (PEA) technology, which employs protein-specific antibodies linked to DNA tags in combination with Next Generation Sequencing (NGS), to quantify 5,440 unique proteins. Using pediatric PAH samples from the PAHBiobank (n=171), we partially validated our top protein candidates.
Results: T-test with false discovery rate correction identified the 10 eligible proteins based on the composite outcome of death, lung transplantation, atrial septostomy, or Pott’s shunt, with 7 proteins upregulated and 3 downregulated (Table 2, top). Initial validation confirmed BDNF and SDC4 were significantly lower, and REN, IGFBP2, and NT-proBNP were higher in those who experienced the composite outcome (all, p<0.01). Similarly, CTSB and CCL24 were increased in patients who experienced the composite outcome, but not significant (p=0.07 and 0.08, respectively) (Table 2, bottom). Kaplan-Meier survival analysis demonstrated a significantly reduced event-free survival among patients with lower BDNF and SDC4 levels (Log-Rank p=0.04). Similarly, elevated REN, IGFBP2, and NT-proBNP was associated with reduced survival (Log-Rank p=0.02, <0.01, and 0.04, respectively). CTSB and CCL24 were also elevated, but not significant (Log-Rank p=0.19 and 0.30, respectively) (Figure 1).
Conclusion: Using high-throughput proteomics, we identified several proteins that were significantly associated with survival in pediatric PAH that can represent new inflammatory, or heart failure pathways. Our early validation has identified new biomarkers such as BDNF and REN that could serve as potential new treatment targets, as inhibitors of the renin-angiotensin axis have shown efficacy in adult PAH and largely unused in children. Future studies will focus on analyzing other target proteins and further validate their clinical relevance.