Urinary gas chromatography mass spectrometry metabolomics in asphyxiated newborns undergoing hypothermia: from the birth to the first month of life

Abstract

Background: Perinatal asphyxia is a severe clinical condition affecting around four million newborns worldwide.It consists of an impaired gas exchange leading to three biochemical components: hypoxemia, hypercapnia and metabolic acidosis. Methods:The aim of this longitudinal experimental study was to identify the urine metabolome of newborns with perinatal asphyxia and to follow changes in urine metabolic profile over time. Twelve babies with perinatal asphyxia were included in this study; three babies died on the eighth day of life. Total-body cooling for 72 hours was carried out in all the newborns. Urine samples were collected in each baby at birth, after 48 hours during hypothermia, after the end of the therapeutic treatment (72 hours), after 1 week of life, and finally after 1 month of life. Urine metabolome at birth was considered the reference against which to compare metabolic profiles in subsequent samples. Quantitative metabolic profiling in urine samples was measured by gas chromatography mass spectrometry (GC-MS). The statistical approach was conducted by using the multivariate analysis by means of principal component analysis (PCA) and orthogonal partial least square discriminant analysis (OPLS-DA). Pathway analysis was also performed. Results:The most important metabolites depicting each time collection point were identified and compared each other. At birth before starting therapeutic hypothermia (TH), urine metabolic profiles of the three babies died after 7 days of life were closely comparable each other and significantly different from those in survivors. Conclusions:In conclusion, a plethora of data have been extracted by comparing the urine metabolome at birth with those observed at each time point collection. The modifications over time in metabolites composition and concentration, mainly originated from the depletion of cellular energy and homeostasis, seems to constitute a fingerprint of perinatal asphyxia.

Exploring Perinatal Asphyxia by Metabolomics

“…Lactate Plasma, urine, cord blood, CSF, brain tissue, ocular tissues [25,26,29,30,32,33,35,[38][39][40][41][42][45][46][47]49,51] Succinate Plasma, urine, cord blood, brain tissue [29,30,37,38,[40][41][42][43]45,47,49,50] Alanine Plasma, urine, cord blood, CSF, brain tissue [25,26,29,30,[37][38][39][40]48,49,52] Urine [36,38,45] BCAA, Branched Chain Amino Acids.…”

“…A longitudinal study of the urinary metabolome of 12 HIE-diagnosed full term newborns was performed by GC-MS [46] and 1 H NMR [47]. According to the local guidelines, these neonates underwent TH starting in the first 6 h and maintained this during 72 h after the hypoxic-ischemic event.…”

How could metabolomics change pediatric health?

“…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].…”

“…Moreover, energy deficiency, variations in the cycle of tricarboxylic acids (TCA) and the increase in lactic acid represent negative predictors, while their decrease during post-natal time may represent indicators of aerobic metabolism and homeostasis restoring in surviving infants with the best outcomes [57].…”