Evolution of Immune Functions of the Mammary Gland and Protection of the Infant

Abstract

The evolution of immunological agents in milk is intertwined with the general aspects of the evolution of the mammary gland. In that respect, mammalian precursors emerged from basal amniotes some 300 million years ago. In contrast to the predominant dinosaurs, proto-mammals possessed a glandular skin. A secondary palate in the roof of the mouth that directed airflow from the nostrils to the oropharynx and thus allowed mammals to ingest and breathe simultaneously first appeared in cynodonts 230 million years ago. This set the stage for mammalian newborns to nurse from the future mammary gland. Interplays between environmental and genetic changes shaped mammalian evolution including the mammary gland from dermal glands some 160 millions of years ago. It is likely that secretions from early mammary glands provided nutrients and immunological agents for the infant. Natural selection culminated in milks uniquely suited to nourish and protect infants of each species. In human milk, antimicrobial, anti-inflammatory, and immunoregulatory agents and living leukocytes are qualitatively or quantitatively different from those in other mammalian milks. Those in human milk compensate for developmental delays in the immunological system of the recipient infant. Consequently, the immune system in human milk provided by evolution is much of the basis for encouraging breastfeeding for human infants.

Terminal glycotope expression on milk fibronectin differs from plasma fibronectin and changes over lactation

“…The fucosylated and sialylated glycotopes of human milk FN might act as soluble glycan receptor decoys and reduce pathogen attachment to infant tissues, and thus they may participate in protection of infants against infections [24,34,35]. The adherence of bacteria via adhesins (bacterial lectins) to host mucins and matrix proteins of the intestine is a crucial step in the colonization process of pathogens such as Streptococcus, Staphylococcus, Mycobacterium, Borrelia, Listeria, Clostridium and Campylobacter [36,37].…”

Breastfeeding and Health Outcomes for the Mother-Infant Dyad

“…Breast milk has evolved to provide the best nutrition, immune protection, and regulation of growth, development, and metabolism for the human infant (24). Breast milk is critical in compensating for developmental delays in immune function in the neonate, and responsible for reducing permeability of the intestine to prepare it for extrauterine life (25).…”

Imprinting, latchment and displacement: a mini review of early instinctual behaviour in newborn infants influencing breastfeeding success

“…This issue has been described as a commerciogenic problem as it is the provider of the dummy, the giver of the bottle or the depriver of the maternal nipple who as an adult is the one confused in their own understanding of infant care 45. Understanding oral tactile recognition of decoys as mother in the mouth directs attention to the mammalian norm evolved from precursors over a period of 300 million years to produce a species‐specific primate milk 46. The behavioural and health risks resulting from impairment of this defining mammalian relationship deserve attention as there is considerable contrary information provided by multinational commercial interests 47.…”