Presented at the Neonatal Society 2014 Autumn Meeting.
Andreas NJ1, Hyde MJ1, Jeffries S1, Garcia-Perez I2, Holmes E2, Modi N1
1 Section of Neonatal Medicine, Department of Medicine, Imperial College London, UK
2 Section of Computational and Systems Medicine, Faculty of Medicine, Imperial College London, UK
Background: Previous research has identified Human Milk Oligosaccharides (HMO) as a highly variable component of human breast milk. HMO are complex carbohydrates that serve multiple functions, including acting as an anti-infective agent for the infant. HMO biosynthesis is in large part determined by Lewis blood group and secretor status, which are genetically determined (1). We hypothesised that the diverse profiles of HMO could be assessed using 1H NMR spectroscopy, and that individual HMOs contributing to differences between profiles would be identifiable.
Methods: Human milk samples were obtained from 108 mothers, at 7 days and 3 months post-partum. Samples were solvent extracted and 1H NMR spectra acquired for the aqueous fraction. Data were analysed using Principal Component Analysis (PCA) to define clustering of data in relation to the component describing the largest proportion of variation. Data were modelled using Orthogonal Partial Least Squares-Discriminant Analysis (OPLS-DA) to compare different groups of mothers, defined by their spectral profiles. The study has received Research Ethics approval (12/LO/0203) and is funded by Westminster Medical School Research Trust.
Results: Large differences in the abundance of HMO were observed between the 7 day and 3 month time points. There was a substantial decrease in HMO quantity at 3 months. Furthermore, large differences in the specific types of HMO were identified. In the PCA plot, two broad groups of mothers were identified, each identified by distinct HMO profiles, known to be determined by maternal genotype. Based on the types of oligosaccharides produced one group, thought to be secretors (Se+), produced a preponderance of HMO known to be products of the gene fucosyltransferase 2, including 2’-fucosyllactose, lactodifucotetraose and lacto-N-fucopentaose 1. The other group, thought to be non-secretors (Se-), did not produce these HMO, but had an increased quantity of other HMO, including 3’-fucosylactose, present in their breast milk. Overlaying the NMR spectra, allows us to identify the types of HMO produced, associated with the Lewis blood groups. The interaction between the Lewis blood group (Le+/Le-) and secretor gene status produce four types of breast milk. All four types were present in our cohort, (Se+/Le+), (Se+/Le-), (Se-/Le+) and (Se-/Le-).
Conclusion: HMO are believed to have important prebiotic properties. Additionally, data show an association between maternal non-secretor status, and increased infant infection risk . We have shown that human milk HMO profile may be characterised rapidly using 1H NMR spectroscopy. This provides opportunity for a stratified medicine approach in future interventional studies involving manipulation of the infant microbiome to reduce infection risk.
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1. Kobata, A., Proc Jpn Acad Ser B Phys Biol Sci, 2010. 86(7): p. 731-47.
2. Morrow AL, et al. J Pediatr, 2004, 145: 297-303.