Salivary proteome profiling to assess growth and development in preterm infants under kangaroo mother care

Delivery of the baby before 37 weeks of completed gestation is deemed to be preterm birth. Admission of these preterm infants to the conventional neonatal intensive care unit (NICU) to manage their fragile physiology also tends to cause considerable stress that impedes the baby’s normal development. A recent innovation in neonatal care is the mother-neonatal ICU (MNICU), where the mother is not a mere visitor but has her bed inside the MNICU by the baby’s side. This study enrolled 200 low birth weight preterm babies (gestational age 28-37 weeks; weight 0.800–1.8 kg) randomized to MNICU & NICU. Saliva was collected from the 200 preterm neonates at the time of admission and discharge. We measured cortisol levels in the saliva of these samples, as the hormone is an established biomarker for stress. Salivary proteomics was also performed on 12 pairs of salivary samples chosen on basis of significant growth and development of these neonates. To study the differential proteome signature in these conditions MS-based data independent acquisition identified and quantified 342 and 308 protein groups, respectively. Differential protein analysis of these proteins revealed 41 differentially expressed proteins (DEPs). Pathway enrichment of unique DEPs in MNICU vs NICU comparison revealed improvement in immunity and metabolism-associated pathways at discharge. Quantitative analysis of the standard proteins from arrival and discharge groups revealed differential expression of these proteins. In differential expression analysis, we identified 28 upregulated and 16 downregulated proteins in neonates admitted to MNICU compared to NICU. A similar analysis for neonates at discharge identified 22 upregulated and 19 downregulated proteins. Further pathway enrichment of differential proteins unique to each group; 22 DEPs were present only in the arrival group, and 19 were in the discharge group. The data show a marked, statistically significant improvement in the overall well-being of preterm children admitted to MNICU and provided KMC compared to the NICU group. Thus, our study provides evidence in favor of easily available, cost-effective care that can make huge difference in the outcome of preterm neonates, particularly in low-income settings.