Bacterial Imprinting of the Neonatal Immune System: Lessons From Maternal Cells?

Abstract

Bacterial translocation is a unique physiologic event, which is increased during pregnancy and lactation in rodents. Human breast milk cells contain a limited number of viable bacteria but a range of bacterial DNA signatures, as also found in maternal peripheral blood mononuclear cells. Those peripheral blood mononuclear cells showed greater biodiversity than did peripheral blood mononuclear cells from control women. Taken together, our results suggest that intestinally derived bacterial components are transported to the lactating breast within mononuclear cells. We speculate that this programs the neonatal immune system to recognize specific bacterial molecular patterns and to respond appropriately to pathogens and commensal organisms.

Gut microbiota: a source of novel tools to reduce the risk of human disease?

“…Maternal microbial transmission is known to happen in the entire animal kingdom, including invertebrates and vertebrates (11). Experimental evidence in mice has been reported to support this notion (12,13). Maternal bacteria present in blood would reach the placenta tissue, from which microbes could reach the amniotic fluid and be swallowed by the fetus (3,4,8) or transfer into the fetal circulation, as has been demonstrated from maternal cells (14) and fetal transfer DNA material to maternal serum (15).…”

Maternal weight and excessive weight gain during pregnancy modify the immunomodulatory potential of breast milk

“…Breast milk has been to shown to be a source of microbes such as staphylococci, streptococci, lactic acid bacteria, and bifidobacteria (4). Bacterial translocation has been demonstrated in different parts of the body, including the gut (27,28). Dendritic cells that penetrate the intestinal epithelium take up commensal bacteria from the gut lumen and reach the systemic circulation, retaining even live bacteria for days (29).…”

“…Dendritic cells that penetrate the intestinal epithelium take up commensal bacteria from the gut lumen and reach the systemic circulation, retaining even live bacteria for days (29). More recently, their transfer to the mammary glands has been reported (27,28,30). Bifidobacteria are the hallmark of the gut microbiota in healthy breast-fed infants, and, apart from bifidogenic oligosaccharides, specific and distinctive species of Bifidobacterium are present in breast milk (4).…”

Human milk and infant intestinal mucosal glycans guide succession of the neonatal intestinal microbiota

“…Also, with the exclusion of skin as the origin, the source of the bacteria in milk remained uncertain. To address these issues, viable bacteria were cultured by plating; 10 3 /ml colony forming units were found in breast milk aseptically collected from healthy lactating mothers (29). Temporal temperature gradient gel electrophoresis indicated the presence of DNA from a diverse pool of enteric bacteria in maternal blood and milk.…”