“Mother-Microbe-Infant-Microbe” Synchrony– A Mini Review

Is breast milk nutrition “alive”, dynamic and impossible to emulate? This question remains important in the context of the emergence of novel diseases and may be answered by comparing it to a few events that happen in nature, with parallels evident in the breast feeding dyad. Edified by nature, and its myriad coexisting species, including the microbes, there seems to be much interplay between species through symbiosis, perhaps, with a lofty purpose. This is compared to the breastfeeding infant’s gut that develops in symbiosis with the microbes that enter it through every feed. Breast milk not only nurtures the infant, but also nourishes the commensal microbes it provides. Milk microbes are influenced by maternal, infant and environmental variables, supporting them differently, parallel to the manner in which microbes and other elements in nature support ecosystems. Reviewing and synthesising information from two different but comparable ecosystems show parallels worthy of appraisal. The lactating mammary gland provides and supports beneficial microbes and microbial environments. Secretory immunoglobulin A (sIgA), the key molecule of mucosal gut immunity, is mutualistic with commensal microbes, capable of mucosal defences, yet preserving equilibrium between pathogen defences and commensal tolerance. Through microbial signals, the nursing mother shares her mucosal immune experiences, commenced in utero, transplacentally and then “translactionally”, to mature infant immunity, concluding an exceptional loop of nurture. Technology allows much appreciation that “immune cross- talk” between mother and infant does occur. In this review, commensal gut microbes in the infant are conceptualised as miniature ecosystems and, breastfeeding, as a vibrant compartment where being “alive” pivots in and around microbial existence and sustenance - a biological setting that, at best, may be emulated but not reproduced.