313 - Biomarker Discovery for Prognostication of Newborn Hypoxic Brain Injury in an Ovine Model

Publication Number: 313.3594

Eesha V. Natarajan, UCSF Benioff Children's Hospital San Francisco, San Bruno, CA, United States; Jana Mike, UCSF Benioff Children's Hospital San Francisco, san francisco, CA, United States; Yasmine White, Kaiser Foundation Hospital - Santa Clara, San Francisco, CA, United States; Emin Maltepe, UCSF, San Francisco, CA, United States

Background: Hypoxic-ischemic encephalopathy (HIE) is the leading cause of neonatal morbidity and mortality (~4 million neonates annually), and accounts for nearly 25% of neonatal deaths (~1 million newborns) globally. Nearly half of the survivors have neurodevelopmental disability, making it the second most common cause of neurologic disability worldwide. Roughly 96% of the disease burden lies in low- and middle-income countries (LMICs), where therapeutic hypothermia (TH), the standard of care, is often unavailable and potentially harmful. The current need for HIE is to define a tool that can be used in a narrow temporal window in LMICs to diagnose and prognosticate disease. Metabolomics, which is defined as the comprehensive analysis of metabolites in a biological specimen, is a promising modality.

Objective: The purpose of this study was to identify HIE biomarkers, characterize their temporal dynamics, and association with neurologic outcome severity in the ovine model.

Design/Methods: HIE was induced to near term lambs at 141-143 days gestation via umbilical cord occlusion (UCO). The lambs were divided into two cohorts. Cohort 1, n=71 UCO lambs, and n=19 controls. Validation cohort 2 included n=25 UCO lambs. Samples were collected at multiple timepoints from birth to 6 days and analyzed by liquid chromatography-mass spectrometry. Neurologic outcomes (development delay, cerebral palsy, spastic diparesis, death) studied were assessed daily.

Results: We analyzed ~50,000 molecules. 1219 hypoxia biomarkers at end of asphyxia were identified in cohort 1 using p< 1e-6 using paired t-test. A higher proportion of hypoxia biomarkers were elevated compared to reduced biomarkers. Most hypoxia biomarkers recovered after 48 hours. Hypoxia biomarkers identified in cohort 1 showed high significance in cohort 2. The time course of the biomarkers is highly consistent between the two cohorts (Fig 1.) Neurological outcome biomarkers that were significant in both studies (n=22) are indicative of outcome severity. The heatmap pattern derived from correlation of biomarker abundance is consistent between the two cohorts; this could result from common mechanisms. Hypoxanthine, a purine metabolism derivative, is one of the significantly changed biomarkers that strongly correlated with hypoxia and neurologic outcomes.

Conclusion(s): HIE triggers specific biomarker response. Further studies are needed to identify significant biomarkers, and define their role as diagnostic or prognostic markers, or therapeutic targets.

Figure 1: Hypoxia Biomarker Trend in Original vs Validation Cohort
The figure depicts the timepoints at which blood samples were collected. Of the 1219 hypoxia biomarkers identified at the end of asphyxia, a higher proportion were elevated (graphs on left) compared to reduced (graphs on right.) The blue line graphs depict biomarker trends in the UCO lambs, and the time course is highly consistent between the two cohorts. Most hypoxia biomarkers recovered after 48 hours. Thereafter, the metabolic profile of the UCO lambs resembled that of the control lambs (orange line graph.)

Figure 1: Hypoxia Biomarker Trend in Original vs Validation Cohort
The figure depicts the timepoints at which blood samples were collected. Of the 1219 hypoxia biomarkers identified at the end of asphyxia, a higher proportion were elevated (graphs on left) compared to reduced (graphs on right.) The blue line graphs depict biomarker trends in the UCO lambs, and the time course is highly consistent between the two cohorts. Most hypoxia biomarkers recovered after 48 hours. Thereafter, the metabolic profile of the UCO lambs resembled that of the control lambs (orange line graph.)