Maternal IgA2 Recognizes Similar Fractions of Colostrum and Fecal Neonatal Microbiota

Microbiota acquired during labor and through the first days of life contributes to the newborn’s immune maturation and development. Mother provides probiotics and prebiotics factors through colostrum and maternal milk to shape the first neonatal microbiota. Previous works have reported that immunoglobulin A (IgA) secreted in colostrum is coating a fraction of maternal microbiota. Thus, to better characterize this IgA-microbiota association, we used flow cytometry coupled with 16S rRNA gene sequencing (IgA-Seq) in human colostrum and neonatal feces. We identified IgA bound bacteria (IgA+) and characterized their diversity and composition shared in colostrum fractions and neonatal fecal bacteria. We found that IgA2 is mainly associated with Bifidobacterium, Pseudomonas, Lactobacillus, and Paracoccus, among other genera shared in colostrum and neonatal fecal samples. We found that metabolic pathways related to epithelial adhesion and carbohydrate consumption are enriched within the IgA2+ fecal microbiota. The association of IgA2 with specific bacteria could be explained because these antibodies recognize common antigens expressed on the surface of these bacterial genera. Our data suggest a preferential targeting of commensal bacteria by IgA2, revealing a possible function of maternal IgA2 in the shaping of the fecal microbial composition in the neonate during the first days of life.

Maternal IgA2 Association with Colostrum Microbiota Contributes to Bacteria Establishment During Intestinal Colonization in the Neonate.

Background: Microbiota colonization during labor and through the first meals contributes to immune maturation and development of the newborn. Mother provides probiotics and prebiotics factors through colostrum and maternal milk to shape the first neonatal microbiota. Previous works have reported that immunoglobulin A (IgA) secreted in colostrum is coating a fraction of maternal microbiota. Methods: Thus, to better characterize the IgA-associated microbiota, we used flow cytometry coupled with 16S rDNA gene sequencing (IgA-Seq) in human colostrum and neonatal feces. We identified IgA-bound bacteria (IgA+) and characterized its diversity to elucidate possible role of IgA subclasses during neonatal bacterial colonization of the colon.Results: We found that IgA2 in the colostrum has an active role during microbiota colonization. Colostrum IgA2 is mainly associated with Bifidobacterium, Lactobacillus, and Bacteroidetes genera. This association seems to give these bacteria an advantage during their establishment since metabolic pathways related to epithelial adhesion and carbohydrate consumption are enriched within fecal IgA2+ microbiota. Association with specific bacteria could be explained since IgA2 recognizes common antigens expressed on surfaces among bacteria genera.Conclusions: Our data suggest a specific targeting of commensal bacteria by IgA2 revealing a specialized function of IgA microbiota association during neonatal intestinal colonization during the first days of life.

Total and Sn-2 Fatty Acid Profile in Human Colostrum and Mature Breast Milk of Women Living in Inland and Coastal Areas of China

Introduction: Although lipid is the major energy source and exerts beneficial effects on infant growth, research on the composition of fatty acid (FA) at the sn-2 position of human milk (HM) in China and abroad is limited. Objectives: This study aimed to investigate the FA positional distribution in colostrum and mature HM of women living in the inland and coastal areas of China and explore the potential influences of geographical region and lactation stage on the FA profile of Chinese women. Methods: Colostrum milk (n = 61) and mature milk (n = 56) samples were obtained longitudinally from healthy lactating women in Guangzhou and Chengdu, China. Gas chromatography was used to determine the total and sn-2 FA composition. Results: Significant differences were observed in the FA profile of HM between different regions and lactation stages, with differences in polyunsaturated FA levels being the most pronounced. Nearly 70% of sn-2 FAs were saturated FAs, of which C16:0 accounted for approximately 75%. C8:0, C10:0, C18:0, C20:0, C22:0, and all of the unsaturated FAs were mainly located at the sn-1 and sn-3 positions, while C14:0, C15:0, and C16:0 were mainly at the sn-2 position. The proportion of C12:0 and C17:0 at sn-2 was approximately equivalent to that at the sn-1, 3 positions. Conclusions: The results indicate the variability in the FA profile of HM between regions and lactation stages. The contents of polyunsaturated FAs and sn-2 FAs, especially palmitic acid, should be paid more attention when optimizing infant formula.

The Gut‒Breast Axis: Programming Health for Life

The gut is a pivotal organ in health and disease. The events that take place in the gut during early life contribute to the programming, shaping and tuning of distant organs, having lifelong consequences. In this context, the maternal gut plays a quintessence in programming the mammary gland to face the nutritional, microbiological, immunological, and neuroendocrine requirements of the growing infant. Subsequently, human colostrum and milk provides the infant with an impressive array of nutrients and bioactive components, including microbes, immune cells, and stem cells. Therefore, the axis linking the maternal gut, the breast, and the infant gut seems crucial for a correct infant growth and development. The aim of this article is not to perform a systematic review of the human milk components but to provide an insight of their extremely complex interactions, which render human milk a unique functional food and explain why this biological fluid still truly remains as a scientific enigma.

Human Colostrum and Derived Extracellular Vesicles Prevent Infection by Human Rotavirus and Respiratory Syncytial Virus in Vitro

Background It is known that breastfeeding protects the infant from enteric and respiratory infections; however, the antiviral properties of human milk against enteric and respiratory viruses are largely unexplored. Research aims To explore the antiviral activity of human preterm colostrum against rotavirus and respiratory syncytial virus and to assess whether the derived extracellular vesicle contribute to this activity. Methods We used a cross-sectional, prospective two-group non-experimental design. Colostra were collected from mothers of preterm newborns ( N = 10) and extracellular vesicles were purified and characterized. The antiviral activity of colostra and derived extracellular vesicles were tested in vitro against rotavirus and respiratory syncytial virus and the step of viral replication inhibited by extracellular vesicles was investigated. Results Each sample of colostrum and colostrum-derived extracellular vesicles had significant antiviral activity with a wide interpersonal variability. Mechanism of action studies demonstrated that extracellular vesicles acted by interfering with the early steps of the viral replicative cycle. Conclusion We demonstrated the intrinsic antiviral activity of human colostrum against rotavirus and respiratory syncytial virus and we showed that extracellular vesicles substantially contribute to the overall protective effect. Our results contribute to unravelling novel mechanisms underlying the functional role of human milk as a protective and therapeutic agent in preterm infants.