Cells from Mature Human Milk are Capable of Cytokine Production Following in Vitro Stimulation

Immunomodulatory Effects of Bacterial Toll-like Receptor Ligands on the Phenotype and Function of Milk Immune Cells in Dromedary Camel

(1) Toll-like receptors (TLR) are a family of pattern recognition receptors that sense distinct molecular patterns of microbial origin. Although the immune cell composition of camel milk has been recently described, host-pathogen interaction studies in the camel mammary gland are still scarce. The present study aimed to use a whole milk stimulation assay for investigating the modulatory effect of selected Toll-like receptor (TLR) ligands on the phenotype and function of milk immune cells. (2) Methods-camel milk samples (n = 7) were stimulated in vitro with the TLR4 ligand LPS or the TLR2/1 ligand Pam3CSK4, and separated milk cells were evaluated for stimulation-induced shape change, the expression of cell surface markers, phagocytosis, apoptosis, ROS production, and NETosis. Stimulation with PMA was used as a control stimulation. (3) Results-all stimulants induced shape change in milk cells, change in the expression of several cell markers, and increased cell apoptosis and NETosis. In addition, stimulation with Pam3CSK4 and PMA was associated with enhanced ROS production, while only PMA stimulation resulted in enhanced bacterial phagocytosis by milk immune cells. (4) Conclusions-our data indicates selective modulating effects of the TLR ligands LPS and Pam3CSK4 on camel milk phagocytes. These results may have implications for the use of synthetic TLR agonists as immunomodulatory adjuvants of the immune response to intra-mammary vaccines against mastitis pathogens.

In Vitro Stimulation of Whole Milk Specimens: A Field-Friendly Method to Assess Milk Immune Activity

BACKGROUND

The immune system of milk protects against infections and guides immune system development. A system-level understanding of milk immune activity is critical for research into infant infectious disease risk and lifelong health.

RESEARCH AIM

To describe a protocol to characterize immune activity in human milk via in vitro stimulation for use in population-based (rather than clinical) research.

METHODS

This study proceeded in two phases, each with a cross-sectional design. Human milk specimens were incubated for 24 hr at 37 °C in mammalian cell culture medium with stimuli (e.g., Salmonella enterica) in a CO₂-enriched environment. Immune responses to stimuli were characterized as the change in cytokine: [stimulated]/[baseline]. Predictors of cytokine responses were evaluated with generalized linear models.

RESULTS

Patterns were detectable across mother-child dyads: Interleukin-6 responses to stimuli were generally positively associated with child age and with maternal autoimmune disease.

CONCLUSIONS

Our method allows characterization of pro-inflammatory milk immune activity in vitro in population-based (rather than clinical) research settings. In vitro activity has a system-level interpretation and is likely to be of broad utility in global health research in settings with high infectious disease risk, where understanding the immune system of milk is critical to understanding maternal and child health.

Influence of Diabetes during Pregnancy on Human Milk Composition

Human milk (HM) is a unique nourishment believed to contain biological factors contributing to both short and long-term benefits. Considering that a mother's own milk is often considered the first choice for nutrition of neonates, an aspect of increased interest is the possible effect of diabetes on the mammary gland and therefore on breast milk composition. This article aims to review the published literature on this topic, and to offer additional insights on the role of this disease on the composition of HM. This review was performed by searching the MEDLINE, EMBASE, CINHAL and Cochrane Library databases. A total of 50 articles were selected, focused specifically on one of the two types of diabetes: gestational diabetes mellitus (21 studies) and insulin-dependent diabetes mellitus (8 studies). Overall, the findings from the literature suggest that diabetes can alter the composition of HM. Nevertheless, the studies in this field are scarce, and the related protocols present some limitations, e.g., evaluating the variability of just a few specific milk biochemical markers in association with this syndrome.

Adipokines in breast milk: an update

Epidemiological surveys indicate that nutrition in infancy is implicated in the long-term tendency to obesity and that a longer duration of breastfeeding is associated with a protective effect against metabolic disorders later in life. However, the precise cause of this association is not well understood. Recent studies on the compounds present in human breast milk have identified various adipokines, including leptin, adiponectin, resistin, obestatin, nesfatin, ghrelin and apelins. Some of these compounds are involved in the regulation of food intake and energy balance. The presence of these adipokines in breast milk suggests that they may be responsible for the regulation of growth in early infancy and that they could influence the energy balance and development of metabolic disorders in childhood and adulthood.

The presence of the peptides apelin, ghrelin and nesfatin-1 in the human breast milk, and the lowering of their levels in patients with gestational diabetes mellitus

Numerous bioactive peptides (such as ghrelins) have been identified in breast milk but there is no information concerning apelin and nesfatin-1. Therefore, present study was designated to explore whether breast milk contains apelin and nesfatin-1, to determine the concentrations and to compare these with serum levels. In addition, the concentrations of these peptides were compared in patients with gestational diabetes and normal lactating samples. Furthermore, this study explored the effectivity of various commercial diagnostic kits for determining ghrelin concentrations in breast milk. Ten gestational diabetic lactating women (29.1±2.2 years old and BMI: 33.2±4.8) and 10 control lactating women (28.2±1.8 years old and BMI: 39.48±1.7) were enrolled in the study. An ELISA was used to determine concentrations of apelin-36 and -12, nesfatin-1, and acylated and desacylated ghrelin in serum, colostrum and mature milk. Serum apelin-36 and -12 concentrations were correlated with colostrum and mature milk, and the same trends were observed for nesfatin-1. Apelins and nesfatin-1 concentrations were higher in mature milk than in colostrum (P<0.05). The concentration of apelins, ghrelins and nesfatin-1 in serum and milk in gestational diabetic lactating women was lower than in control samples. The majority of ghrelin circulating and in milk was the free form (desacylated) in both groups of women. This is the first report to describe the presence of apelins and nesfatin-1 in breast milk. It is suggested that the source of ghrelins, apelins and nesfatin-1 in breast milk is likely to be breast tissue (autonomous production). These bioactive peptides found in breast milk could be important for growth, energy regulation and maturation of the gastrointestinal system in neonates.

Ghrelin is present in human colostrum, transitional and mature milk

Ghrelin and its mRNA have recently been found in numerous human tissues including breast. The aim of this study was to compare the ghrelin levels in colostrum, mature and transitional milk and plasma in lactating women with plasma samples from non-lactating women. Venous blood samples were obtained from 17 healthy lactating women aged 22-35 years and from 16 age-matched controls. Colostrum, transitional and mature milk samples were collected just before suckling. The level of bioactive ghrelin was determined by RIA. Comparison of ghrelin values for lactating women showed significantly lower concentrations in colostrum (70.3 +/- 18 pg/ml), transitional milk (83.8 +/- 18pg/ml) and mature milk (97.3 +/- 13 pg/ml) than in the corresponding plasma samples (first day 95 +/- 16 pg/ml, 10th day 111 +/- 13 pg/ml and 15th day 135 +/- 16 pg/ml). The plasma concentrations were lower in the lactating than in the non-lactating women. Thus, the ghrelin levels in colostrum, transitional and mature milk were elavated concomitantly with increasing plasma ghrelin after delivery. The origin of milk ghrelin is not known, but it probably comes from the plasma.