Variation among populations in the immune protein composition of mother’s milk reflects subsistence pattern

Abstract

Lay SummaryAdaptive immune proteins in mothers’ milk are more variable than innate immune proteins across populations and subsistence strategies. These results suggest that the immune defenses in milk are shaped by a mother’s environment throughout her life.Background and objectivesMother’s milk contains immune proteins that play critical roles in protecting the infant from infection and priming the infant’s developing immune system during early life. The composition of these molecules in milk, particularly the acquired immune proteins, is thought to reflect a mother’s immunological exposures throughout her life. In this study, we examine the composition of innate and acquired immune proteins in milk across seven populations with diverse disease and cultural ecologies.MethodologyMilk samples (n = 164) were collected in Argentina, Bolivia, Nepal, Namibia, Philippines, Poland and the USA. Populations were classified as having one of four subsistence patterns: urban-industrialism, rural-shop, horticulturalist-forager or agro-pastoralism. Milk innate (lactalbumin, lactoferrin and lysozyme) and acquired (Secretory IgA, IgG and IgM) protein concentrations were determined using triple-quadrupole mass spectrometry.ResultsBoth innate and acquired immune protein composition in milk varied among populations, though the acquired immune protein composition of milk differed more among populations. Populations living in closer geographic proximity or having similar subsistence strategies (e.g. agro-pastoralists from Nepal and Namibia) had more similar milk immune protein compositions. Agro-pastoralists had different milk innate immune protein composition from horticulturalist-foragers and urban-industrialists. Acquired immune protein composition differed among all subsistence strategies except horticulturist-foragers and rural-shop.Conclusions and implicationsOur results reveal fundamental variation in milk composition that has not been previously explored in human milk research. Further study is needed to understand what specific aspects of the local environment influence milk composition and the effects this variation may have on infant health outcomes.

Changes in Human Milk Immunoglobulin Profile During Prolonged Lactation

“…Additionally, the analysis of milk samples from more than 20 mothers in each group according to the duration of lactation was performed. Moreover, in contrast to the latest reports of Klein et al ( 48 ), who adopted triple–quadrupole time-of-flight mass spectrometry for immunoglobulin determinations, we used highly specific immunochemical ELISA methods, which we believe are better because they are cheaper, faster, more accessible, and can be routinely used in labs in milk banks, after appropriate adaptation, to characterize the immunological status of donor milk. The limitations of our study are its being a single-center, non-randomized controlled study and there being no short- and long-term health follow-up of the infants of this study.…”

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“…In a comparative study across seven ecologically and economically diverse populations, Klein et al. () demonstrated that acquired immune protein composition—which reflects both recent and lifelong maternal disease exposures—exhibited greater interpopulation variation than did innate composition. Miller () similarly found differences in levels of anti‐inflammatory milk bioactives between US and Kenyan (Ariaal) mothers, which further predicted differences in infant growth outcomes.…”