A longitudinal 1H-NMR metabolomics analysis of urine from newborns with hypoxic-ischemic encephalopathy undergoing hypothermia therapy. Clinical and medical legal insights

Abstract

Perinatal asphyxia is an event affecting around four million newborns worldwide. The 0.5 to 2 per 1000 of full term asphyxiated newborns suffer from hypoxic-ischemic encephalopathy (HIE), which is a frequent cause of death or severe disability and, as consequence, the most common birth injury claim for obstetrics, gynaecologists, and paediatricians. Perinatal asphyxia results from a compromised gas exchange that leads to hypoxemia, hypercapnia, and metabolic acidosis. In this work, we applied a metabolomics approach to investigate the metabolic profiles of urine samples collected from full term asphyxiated newborns with HIE undergoing therapeutic hypothermia (TH), with the aim of identifying a pattern of metabolites associated with HIE and to follow their modifications over time. Urine samples were collected from 10 HIE newborns at birth, during hypothermia (48 hours), at the end of the therapeutic treatment (72 hours), at 1 month of life, and compared with a matched control population of 16 healthy full term newborns. The metabolic profiles were investigated by 1H NMR spectroscopy coupled with multivariate statistical methods such as principal component analysis and orthogonal partial least square discriminant analysis. Multivariate analysis indicated significant differences between the urine samples of HIE and healthy newborns at birth. The altered metabolic patterns, mainly originated from the depletion of cellular energy and homeostasis, seem to constitute a characteristic of perinatal asphyxia. The HIE urine metabolome changes over time reflected either the effects of TH and the physiological growth of the newborns. Of interest, the urine metabolic profiles of the HIE non-surviving babies, characterized by the increased excretion of lactate, resulted significantly different from the rest of HIE population.

How could metabolomics change pediatric health?

“…Finally, lactic acid, myo-inositol, betaine increased while citrate, α-ketoglutarate, succinate, acetone, dimethylamine, glutamine, pyruvate, arginine and acetate decreased in asphyxiated newborns' urinary profiles at 1 month of life [55]. These data highlight that determining a real threshold for survivals characterizing each metabolite could be highly useful.…”

“…Perinatal asphyxia is one of the most frequent causes of neonatal death or impaired outcome, potentially leading to severe disability, cerebral palsy and poor neurodevelopment [55]. Such topic was deeply investigated across several studies, speculating the potential occurrence of specific metabolic perturbations in the urine of asphyxiated newborns.…”

“…Finally, progressive modifications of urinary metabolome from n = 12 asphyxiated newborns were pointed out, compatible with the progression of clinical condition. Urinary samples were evaluated at birth, during and at the end of hypothermia, at a week and a month after birth through GC-MS [57] and 1 H-NMR [55]. In detail, taurine, hypotaurine, U1710, lactic acid, lysine, mannitol and ubiquinone showed the greatest variations [57].…”

“…The urinary metabolome of survivors was clearly different from that of neonates that died in the first 8 days of life, and these differences were already present at birth. These modifies could indicate irreversible asphyxia-related perturbations, indicated by metabolic fingerprints, such as lactic acid, taurine and other metabolites [55,57].…”

Clinical Metabolomics in Neonatology: From Metabolites to Diseases

“…This may be due to the high energy demand of the asphyxiated brain and reflects oxidative damage in the brain but also in other vital organs because of lack of oxygen [24,50].…”