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Breastmilk-Saliva Interactions Boost Innate Immunity by Regulating the Oral Microbiome in Early Infancy
Saad S Al-Shehri1, Christine L Knox2, Helen G Liley3
1School of Pharmacy, The University of Queensland, Brisbane, Australia; College of Applied Medical Science, Taif University, Taif, Saudi Arabia.
Plos One
|September 2, 2015
Summary
Neonatal saliva, rich in xanthine oxidase substrates, reacts with breastmilk to generate hydrogen peroxide, boosting infant immunity. This milk-saliva interaction supports beneficial oral bacteria while inhibiting pathogens.
Area of Science:
- Biochemistry
- Immunology
- Microbiology
Background:
- Xanthine oxidase (XO) is active in mammalian milk, generating hydrogen peroxide (H2O2).
- Adult saliva has low XO substrates (hypoxanthine, xanthine) but high thiocyanate.
- Neonatal saliva composition and its interaction with milk were previously unexamined.
Purpose of the Study:
- To investigate the biochemical composition of neonatal saliva.
- To explore the interaction between neonatal saliva and breastmilk.
- To understand the role of milk-saliva interaction in early infant immunity and microbiota development.
Main Methods:
- Quantification of hypoxanthine, xanthine, H2O2, and peroxidase activity in neonatal and adult saliva.
- Analysis of nucleosides and nucleobases in neonatal saliva.
- In vitro assessment of saliva-milk interaction effects on microbial growth.
- Comparative analysis of saliva from domesticated mammals.
Main Results:
- Neonatal saliva showed significantly higher concentrations of hypoxanthine and xanthine compared to adults.
- Mixing neonatal saliva with breastmilk generated substantial H2O2, inhibiting Staphylococcus aureus and Salmonella spp.
- Neonatal saliva contained growth-promoting nucleosides/nucleobases for Lactobacillus but inhibitory effects on opportunistic pathogens.
- A transition to adult saliva patterns was observed during weaning.
Conclusions:
- Breast-feeding involves a synergistic milk-saliva interaction producing reactive oxygen species and beneficial metabolites.
- This interaction regulates early oral and gut microbiota, promoting innate immunity in infants.
- Milk's role extends beyond nutrition, contributing to early immune defense through biochemical interactions with infant saliva.
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