RNA sequencing of the human milk fat layer transcriptome reveals distinct gene expression profiles at three stages of lactation

Human milk proteins differentiate over the sex of newborns and across stages of lactation

BACKGROUND & AIMS

Human milk (HM) is a complete food that meets the nutritional and energy demands of the newborns. It contains numerous bioactive components, including functional proteins. Variations in HM energy and lipid content have already been reported related to the newborn's sex, but differences between protein profiles are still scarce. This work aimed to identify differences between HM proteins produced by mothers of female and male newborns, in the lactation stages of colostrum and mature milk, and the metabolic pathways involved.

METHODS

A total of 98 HM samples were collected from 39 lactating women and classified according to the newborn's sex, stages of lactation, and three mothers' age groups, and evaluated about protein concentration and one-dimensional electrophoretic profile. Next, to assess samples with the greatest differences, the HM proteins regarding the newborn's sex and the stages of lactation were compared using nano-LC-MS/MS, in 24 HM samples randomly rearranged into four groups: female and male infants, and colostrum and mature milk. Functional classification, metabolic pathways, and protein interaction networks were analyzed by Gene Ontology, KEGG, and STRING, respectively.

RESULTS

The soluble protein content of HM decreased throughout lactation, with differences regarding isolated factors, such as mothers' age group, child's sex and stages of lactation, and also in terms of their interactions. A total of 146 proteins were identified, 42 of which showed different abundances over the sexes of newborns and 53 between the stages of lactation. In general, proteins related to metabolic processes were up-regulated for mothers of male infants and in the mature stage of lactation, while proteins related to defense were up-regulated in mothers of female infants and in the colostrum phase.

CONCLUSION

This study indicated that there are differentiated and specific nutritional and defense needs of newborns, by sex and by lactation phase, which is highly relevant for a more appropriate supply of food to infants receiving HM from donor mothers.

scCDC: a computational method for gene-specific contamination detection and correction in single-cell and single-nucleus RNA-seq data

In droplet-based single-cell and single-nucleus RNA-seq assays, systematic contamination of ambient RNA molecules biases the quantification of gene expression levels. Existing methods correct the contamination for all genes globally. However, there lacks specific evaluation of correction efficacy for varying contamination levels. Here, we show that DecontX and CellBender under-correct highly contaminating genes, while SoupX and scAR over-correct lowly/non-contaminating genes. Here, we develop scCDC as the first method to detect the contamination-causing genes and only correct expression levels of these genes, some of which are cell-type markers. Compared with existing decontamination methods, scCDC excels in decontaminating highly contaminating genes while avoiding over-correction of other genes.

Fused in sarcoma (FUS) inhibits milk production efficiency in mammals

Efficient milk production in mammals confers evolutionary advantages by facilitating the transmission of energy from mother to offspring. However, the regulatory mechanism responsible for the gradual establishment of milk production efficiency in mammals, from marsupials to eutherians, remains elusive. Here, we find that mammary gland of the marsupial sugar glider contained milk components during adolescence, and that mammary gland development is less dynamically cyclic compared to that in placental mammals. Furthermore, fused in sarcoma (FUS) is found to be partially responsible for this establishment of low efficiency. In mouse model, FUS inhibit mammary epithelial cell differentiation through the cyclin-dependent kinase inhibitor p57Kip2, leading to lactation failure and pup starvation. Clinically, FUS levels are negatively correlated with milk production in lactating women. Overall, our results shed light on FUS as a negative regulator of milk production, providing a potential mechanism for the establishment of milk production from marsupial to eutherian mammals.

Maternal Cannabis Use during Lactation and Potential Effects on Human Milk Composition and Production: A Narrative Review

Cannabis use has increased sharply in the last 20 y among adults, including reproductive-aged women. Its recent widespread legalization is associated with a decrease in risk perception of cannabis use during breastfeeding. However, the effect of cannabis use (if any) on milk production and milk composition is not known. This narrative review summarizes current knowledge related to maternal cannabis use during breastfeeding and provides an overview of possible pathways whereby cannabis might affect milk composition and production. Several studies have demonstrated that cannabinoids and their metabolites are detectable in human milk produced by mothers who use cannabis. Due to their physicochemical properties, cannabinoids are stored in adipose tissue, can easily reach the mammary gland, and can be secreted in milk. Moreover, cannabinoid receptors are present in adipocytes and mammary epithelial cells. The activation of these receptors directly modulates fatty acid metabolism, potentially causing changes in milk fatty acid profiles. Additionally, the endocannabinoid system is intimately connected to the endocrine system. As such, it is probable that interactions of exogenous cannabinoids with the endocannabinoid system might modify release of critical hormones (e.g., prolactin and dopamine) that regulate milk production and secretion. Nonetheless, few studies have investigated effects of cannabis use (including on milk production and composition) in lactating women. Additional research utilizing robust methodologies are needed to elucidate whether and how cannabis use affects human milk production and composition.

Gestational age at birth influences protein and RNA content in human milk extracellular vesicles

Human milk extracellular vesicles (HM EVs) are proposed to protect against disease development in infants. This protection could in part be facilitated by the bioactive EV cargo of proteins and RNA. Notably, mothers birth infants of different gestational ages with unique needs, wherein the EV cargo of HM may diverge. We collected HM from lactating mothers within two weeks of a term or preterm birth. Following purification of EVs, proteins and mRNA were extracted for proteomics and sequencing analyses, respectively. Over 2000 protein groups were identified, and over 8000 genes were quantified. The total number of proteins and mRNA did not differ significantly between the two conditions, while functional bioinformatics of differentially expressed cargo indicated enrichment in immunoregulatory cargo for preterm HM EVs. In term HM EVs, significantly upregulated cargo was enriched in metabolism-related functions. Based on gene expression signatures from HM-contained single cell sequencing data, we proposed that a larger portion of preterm HM EVs are secreted by immune cells, whereas term HM EVs contain more signatures of lactocyte epithelial cells. Proposed differences in EV cargo could indicate variation in mother's milk based on infants' gestational age and provide basis for further functional characterisation.

Breastfeeding Associated with Lower Prevalence of Metabolic Syndrome in Women with Gestational Diabetes in the Very Early Postpartum Period

OBJECTIVE

 The aim of this study is to examine the association of breastfeeding with metabolic syndrome (MetS) in women with recent gestational diabetes mellitus (GDM) in the very early postpartum (PP) period.

STUDY DESIGN

 We performed a secondary analysis of the Balance After Baby Intervention (BABI) study which enrolled women with recent GDM. Data collected during an early (~8 weeks) PP visit were used in this analysis. At this visit, weight, height, waist circumference (WC), blood pressure (BP), fasting plasma glucose (FPG), and lipids were obtained. MetS was classified per National Cholesterol Education Program Adult Treatment Program III (NCEP-ATP III) criteria. We defined breastfeeding as currently breastfeeding or not currently breastfeeding for the main analysis.

RESULTS

 Of 181 women enrolled in BABI, 178 were included in this analysis (3 excluded for missing lipids). Thirty-four percent were Hispanic. Of non-Hispanics, 31.5% were White, 18.5% Asian, and 12.9% Black/African American. The prevalence of MetS was 42.9% in women not breastfeeding versus 17.1% in women breastfeeding (p < 0.001; adjusted odds ratio [aOR] = 0.16 [95% confidence interval (CI): 0.06-0.41]). Breastfeeding women had significantly lower odds of FPG ≥100 mg/dL (aOR = 0.36 [95% CI: 0.14-0.95], p = 0.039), HDL < 50 mg/dL (aOR = 0.19 [95% CI: 0.08-0.46], p < 0.001), and triglycerides (TG) ≥ 150 mg/dL (aOR = 0.26 [95% CI: 0.10-0.66], p = 0.005). When evaluated as continuous variables, WC, FPG, and TG were significantly lower and HDL significantly higher in women breastfeeding in the very early PP period (vs. not breastfeeding).

CONCLUSION

 In a diverse population of women with recent GDM, there was lower prevalence of MetS in women breastfeeding compared with those not breastfeeding in the very early PP period. This study extends the findings of an association of breastfeeding with MetS previously reported at time points more remote from pregnancy to the very early PP period and to an ethnically and racially diverse population.

KEY POINTS

· MetS prevalence in women with recent GDM was lower in breastfeeding than not breastfeeding women.. · FPG, HDL, WC, and TG were improved in the breastfeeding group.. · This study extends prior findings to the very early PP period and to a diverse population..

Comparative proteomic analysis of human milk fat globules and paired membranes and mouse milk fat globules identifies core cellular systems contributing to mammary lipid trafficking and secretion

Introduction: Human milk delivers critical nutritional and immunological support to human infants. Milk fat globules (MFGs) and their associated membranes (MFGMs) contain the majority of milk lipids and many bioactive components that contribute to neonatal development and health, yet their compositions have not been fully defined, and the mechanisms responsible for formation of these structures remain incompletely understood. Methods: In this study, we used untargeted mass spectrometry to quantitatively profile the protein compositions of freshly obtained MFGs and their paired, physically separated MFGM fractions from 13 human milk samples. We also quantitatively profiled the MFG protein compositions of 9 pooled milk samples from 18 lactating mouse dams. Results: We identified 2,453 proteins and 2,795 proteins in the majority of human MFG and MFGM samples, respectively, and 1,577 proteins in mouse MFGs. Using paired analyses of protein abundance in MFGMs compared to MFGs (MFGM-MFG; 1% FDR), we identified 699 proteins that were more highly abundant in MFGMs (MFGM-enriched), and 201 proteins that were less abundant in MFGMs (cytoplasmic). MFGM-enriched proteins comprised membrane systems (apical plasma membrane and multiple vesicular membranes) hypothesized to be responsible for lipid and protein secretion and components of membrane transport and signaling systems. Cytoplasmic proteins included ribosomal and proteasomal systems. Comparing abundance between human and mouse MFGs, we found a positive correlation (R 2 = 0.44, p < 0.0001) in the relative abundances of 1,279 proteins that were found in common across species. Discussion: Comparative pathway enrichment analyses between human and mouse samples reveal similarities in membrane trafficking and signaling pathways involved in milk fat secretion and identify potentially novel immunological components of MFGs. Our results advance knowledge of the composition and relative quantities of proteins in human and mouse MFGs in greater detail, provide a quantitative profile of specifically enriched human MFGM proteins, and identify core cellular systems involved in milk lipid secretion.

Prolactin does not seem to mediate the improvement on insulin resistance markers and blood glucose levels related to breastfeeding

Introduction

The prevalence of type 2 diabetes mellitus (T2DM) is increasing worldwide. Strategies to decrease this risk should be strongly encouraged. Lactation has been associated, for the mother, with reduction in future T2DM risk in several studies. The mechanisms behind this phenomenon, however, are poorly understood. The aims of this study were, first, to compare blood glucose levels and markers of insulin resistance (MIR) in early postpartum women with overweight/obesity according to their breastfeeding status and, second, to evaluate whether prolactin (PRL) levels could mediate improvements in these parameters.

Methods

The prospective study followed 95 women older than 18 years from early pregnancy for up to 60 to 180 days postpartum. All participants had a BMI > 25 kg/m2 and a singleton pregnancy. At each visit, questionnaires and clinical and biochemical evaluations were performed. Participants were divided into two groups according to the breastfeeding status as "yes" for exclusive or predominant breastfeeding, and "no" for not breastfeeding.

Results

Breastfeeding women (n = 44) had significantly higher PRL levels [47.8 (29.6-88.2) vs. 20.0 (12.0-33.8), p< 0.001]. They also had significantly lower fasting blood glucose levels [89.0 (8.0) vs. 93.9 (12.6) mg/dl, p = 0.04], triglycerides (TG) [92.2 (37.9) vs. 122.4 (64.4) mg/dl, p = 0.01], TG/HDL ratio [1.8 (0.8) vs. 2.4 (1.6) mg/dl, p = 0.02], TyG index [8.24 (0.4) vs. 8.52 (0.53), p = 0.005], fasting serum insulin [8.9 (6.3-11.6) vs. 11.4 (7.7-17.0), p = 0.048], and HOMA-IR [2.0 (1.3-2.7) vs. 2.6 (1.6-3.9), p = 0.025] in the postpartum period compared to the non-breastfeeding group. Groups were homogeneous in relation to prevalence of GDM, pre-gestational BMI, as well as daily caloric intake, physical activity, and weight loss at postpartum. Linear regression analysis with adjustments for confounders showed a statistically significant association of breastfeeding with fasting blood glucose [-6.37 (-10.91 to -1.83), p = 0.006], HOMA-IR [-0.27 (-0.51 to -0.04), p = 0.024], TyG index [-0.04 (-0.06 to -0.02), p = 0.001], and TG/HDL ratio [-0.25 (-0.48 to -0.01), p = 0.038]. Mediation analysis showed that PRL did not mediate these effects. Sensitivity analyses considering different cutoffs for PRL levels also did not show modification effect in the mediation analyses.

Conclusion

Breastfeeding was associated with improvement in glucose metabolism and MIR 60 to 180 days after birth in overweight and obese women, even when adjusted for confounders. PRL levels were not found to mediate the association between breastfeeding and improvement in MIR.

Human Cytomegalovirus in breast milk is associated with milk composition, the infant gut microbiome, and infant growth

Human cytomegalovirus (CMV) is a highly prevalent herpesvirus that is often transmitted to the neonate via breast milk. Postnatal CMV transmission can have negative health consequences for preterm and immunocompromised infants, but any effects on healthy term infants are thought to be benign. Furthermore, the impact of CMV on the composition of the hundreds of bioactive factors in human milk has not been tested. Here, we utilize a cohort of exclusively breastfeeding full term mother-infant pairs to test for differences in the milk transcriptome and metabolome associated with CMV, and the impact of CMV in breast milk on the infant gut microbiome and infant growth. We find upregulation of the indoleamine 2,3- dioxygenase (IDO) tryptophan-to-kynurenine metabolic pathway in CMV+ milk samples, and that CMV+ milk is associated with decreased Bifidobacterium in the infant gut. Our data indicate a complex relationship between milk CMV, milk kynurenine, and infant growth; with kynurenine positively correlated, and CMV viral load negatively correlated, with infant weight-for-length at 1 month of age. These results suggest CMV transmission, CMV-related changes in milk composition, or both may be modulators of full term infant development.

Parental factors that impact the ecology of human mammary development, milk secretion, and milk composition-a report from "Breastmilk Ecology: Genesis of Infant Nutrition (BEGIN)" Working Group 1

The goal of Working Group 1 in the Breastmilk Ecology: Genesis of Infant Nutrition (BEGIN) Project was to outline factors influencing biological processes governing human milk secretion and to evaluate our current knowledge of these processes. Many factors regulate mammary gland development in utero, during puberty, in pregnancy, through secretory activation, and at weaning. These factors include breast anatomy, breast vasculature, diet, and the lactating parent's hormonal milieu including estrogen, progesterone, placental lactogen, cortisol, prolactin, and growth hormone. We examine the effects of time of day and postpartum interval on milk secretion, along with the role and mechanisms of lactating parent-infant interactions on milk secretion and bonding, with particular attention to the actions of oxytocin on the mammary gland and the pleasure systems in the brain. We then consider the potential effects of clinical conditions including infection, pre-eclampsia, preterm birth, cardiovascular health, inflammatory states, mastitis, and particularly, gestational diabetes and obesity. Although we know a great deal about the transporter systems by which zinc and calcium pass from the blood stream into milk, the interactions and cellular localization of transporters that carry substrates such as glucose, amino acids, copper, and the many other trace metals present in human milk across plasma and intracellular membranes require more research. We pose the question of how cultured mammary alveolar cells and animal models can help answer lingering questions about the mechanisms and regulation of human milk secretion. We raise questions about the role of the lactating parent and the infant microbiome and the immune system during breast development, secretion of immune molecules into milk, and protection of the breast from pathogens. Finally, we consider the effect of medications, recreational and illicit drugs, pesticides, and endocrine-disrupting chemicals on milk secretion and composition, emphasizing that this area needs much more research attention.

Human Milk Lipids and Small Metabolites: Maternal and Microbial Origins

Although there has been limited application in the field to date, human milk omics research continues to gain traction. Human milk lipidomics and metabolomics research is particularly important, given the significance of milk lipids and metabolites for infant health. For researchers conducting compositional milk analyses, it is important to consider the origins of these compounds. The current review aims to provide a summary of the existing evidence on the sources of human milk lipids and small metabolites. Here, we describe five major sources of milk lipids and metabolites: de novo synthesis from mammary cells, production by the milk microbiota, dietary consumption, release from non-mammary tissue, and production by the gut microbiota. We synthesize the literature to provide evidence and understanding of these pathways in the context of mammary gland biology. We recommend future research focus areas to elucidate milk lipid and small metabolite synthesis and transport pathways. Better understanding of the origins of human milk lipids and metabolites is important to improve translation of milk omics research, particularly regarding the modulation of these important milk components to improve infant health outcomes.

Interrogating the role of the milk microbiome in mastitis in the multi-omics era

There is growing interest in a functional understanding of milk-associated microbiota as there is ample evidence that host-associated microbial communities play an active role in host health and phenotype. Mastitis, characterized by painful inflammation of the mammary gland, is prevalent among lactating humans and agricultural animals and is associated with significant clinical and economic consequences. The etiology of mastitis is complex and polymicrobial and correlative studies have indicated alterations in milk microbial community composition. Recent evidence is beginning to suggest that a causal relationship may exist between the milk microbiota and host phenotype in mastitis. Multi-omic approaches can be leveraged to gain a mechanistic, molecular level understanding of how the milk microbiome might modulate host physiology, thereby informing strategies to prevent and ameliorate mastitis. In this paper, we review existing studies that have utilized omics approaches to investigate the role of the milk microbiome in mastitis. We also summarize the strengths and challenges associated with the different omics techniques including metagenomics, metatranscriptomics, metaproteomics, metabolomics and lipidomics and provide perspective on the integration of multiple omics technologies for a better functional understanding of the milk microbiome.

Expression profile of different classes of proteases in milk derived somatic cells across different lactation stages of indigenous cows (Bos indicus) and riverine buffaloes (Bubalus bubalis)

Proteases play a significant role in milk and its products by affecting flavor, texture and longevity. The expression of endogenous proteases varies across different stages of lactation. The study was conducted to understand the transcriptional pattern of different classes of protease-pathways associated genes (CTSB, CTSD, CTSH, CTSL, CTSK, CTSS, CTSZ, PLAU, PLAT) and potential protease inhibitors (SERPIN E2 and SERPIN F2) in 40 milk somatic cells (MSC) samples isolated during early, peak, mid and late lactation stages of Sahiwal cows and Murrah buffaloes - the two most important dairy breeds of India. In Sahiwal cows, except CTSK and PLAU, the expression of other proteases class was not affected significantly (p > 0.05) across lactation stages. However, in Murrah buffaloes, the expression of different proteases increased as the lactation progressed. Most of the proteases showed lower expression during early and peak lactation stages while their expression tends to increase during mid to late lactation stages. The overall trend was somewhat similar in both the dairy species albeit the level of expression was higher in buffalo MSC as compared to cow MSC. The study has provided valuable information on expression kinetics of different proteases in milk somatic cells of two major dairy breeds of India.

Associations of Secretory Activation Breast Milk Biomarkers with Breastfeeding Outcome Measures

OBJECTIVE

The objective of this study was to explore associations between day 10 postpartum (D10) secretory activation biomarkers and the breastfeeding outcome measures.

STUDY DESIGN

This prospective longitudinal descriptive study collected antepartum, D10, and day 60 postpartum (D60) questionnaire data and D10 milk samples. Protein, lactose, and citrate were analyzed with enzymatic spectrophotometric assays. Sodium and potassium were analyzed with inductively coupled plasma optical emission spectrophotometry. Group comparison data were analyzed using χ², Fisher exact, and independent sample t tests, as appropriate, using SPSS for Mac (version 28).

RESULTS

Participants (n = 92) provided a D10 breastmilk sample and completed D10 questionnaires, and 83 completed D60 questionnaires. Participants with D10 impaired secretory activation sodium (>23.0 mM) were more likely to report D10 perceived insufficient milk supply, χ² = 7.002, P < .05; and less D10 feeding/pumping frequency a day, P < .05; and partial breastfeeding at D60, P < .05. Additionally, participants with D10 impaired secretory activation sodium-to-potassium ratio (sodium: potassium) > 0.8 were more likely to partially breastfeed at D60, P < .05.

CONCLUSION

Elevated milk sodium and sodium: potassium are biomarkers related to variables indicative of low milk supply. Therefore, immediate milk testing can be useful in identifying lactation compromise and improving breastfeeding duration. Because breastfeeding affords maternal and infant health benefits, clinicians should identify ways to measure lactation compromise in conjunction with an examination and clinical history to provide early interventions to increase breastfeeding duration and exclusivity.

Human milk variation is shaped by maternal genetics and impacts the infant gut microbiome

Human milk is a complex mix of nutritional and bioactive components that provide complete nutrition for the infant. However, we lack a systematic knowledge of the factors shaping milk composition and how milk variation influences infant health. Here, we used multi-omic profiling to characterize interactions between maternal genetics, milk gene expression, milk composition, and the infant fecal microbiome in 242 exclusively breastfeeding mother-infant pairs. We identified 487 genetic loci associated with milk gene expression unique to the lactating mammary gland, including loci that impacted breast cancer risk and human milk oligosaccharide concentration. Integrative analyses uncovered connections between milk gene expression and infant gut microbiome, including an association between the expression of inflammation-related genes with IL-6 concentration in milk and the abundance of Bifidobacteria in the infant gut. Our results show how an improved understanding of the genetics and genomics of human milk connects lactation biology with maternal and infant health.

Hormonal regulation of mammary gland development and lactation

Lactation is critical to infant short-term and long-term health and protects mothers from breast cancer, ovarian cancer and type 2 diabetes mellitus. The mammary gland is a dynamic organ, regulated by the coordinated actions of reproductive and metabolic hormones. These hormones promote gland development from puberty onwards and induce the formation of a branched, epithelial, milk-secreting organ by the end of pregnancy. Progesterone withdrawal following placental delivery initiates lactation, which is maintained by increased pituitary secretion of prolactin and oxytocin, and stimulated by infant suckling. After weaning, local cytokine production and decreased prolactin secretion trigger large-scale mammary cell loss, leading to gland involution. Here, we review advances in the molecular endocrinology of mammary gland development and milk synthesis. We discuss the hormonal functions of the mammary gland, including parathyroid hormone-related peptide secretion that stimulates maternal calcium mobilization for milk synthesis. We also consider the hormonal composition of human milk and its associated effects on infant health and development. Finally, we highlight endocrine and metabolic diseases that cause lactation insufficiency, for example, monogenic disorders of prolactin and prolactin receptor mutations, maternal obesity and diabetes mellitus, interventions during labour and delivery, and exposure to endocrine-disrupting chemicals such as polyfluoroalkyl substances in consumer products and other oestrogenic compounds.

Dilemmas in initiation of very preterm infant enteral feeds-when, what, how?

With limited clinical evidence available to guide common nutritional decisions, significant variation exists in approaches to enteral feeding for very preterm infants, specifically when feedings are initiated, what is fed, and the method used for feedings. Preclinical studies have highlighted the benefits associated with avoiding nil per os and providing early-stage mother's own milk or colostrum. However, these recommended approaches are often mutually exclusive due to the delays in lactation associated with very preterm delivery, resulting in uncertainty regarding which approach should be prioritized. Few studies have evaluated feeding frequency in preterm infants, with limited generalizability to extremely preterm infants. Therefore, even evidence-based approaches to very preterm infant feed initiation can differ. Future research is needed to identify optimal strategies for enteral nutrition in very preterm infants, but, until then, evidence-informed approaches may vary depending on each neonatal intensive care unit's assessment of risk and benefit.

Transcriptomic changes underlying glucocorticoid-induced suppression of milk production by dairy cows

Milk production by dairy cows is sensitive to increased levels of stress hormones such as glucocorticoids (GC) that also regulate the transcription of several genes required for milk synthesis. Whereas previous studies identified that an exogenous GC such as dexamethasone (DEX) transiently suppresses milk yield in several species without any pronounced effect on milk protein or fat percentage, the mechanism underlying this effect has not been established. In this study we sought to establish changes within the mammary glands of non-pregnant dairy cows in their second lactation (n = 3-4; 648-838 kg) following a single dose of exogenous DEX. Changes in the udder were monitored by serial biopsy of alternating quarters, concurrent with quarter-level monitoring of milk yield and composition. Dexamethasone increased serum glucose levels from 12-36 h (p <0 .05), reduced milk yield from 12-48 h (p <0 .05), increased % milk protein content at 24 h post-DEX, and transiently decreased both milk lactose and α-lactalbumin content, while not altering the level of milk fat. After 72 h, all aspects of milk production had returned to pre-treatment levels. Transcriptomic changes in the mammary glands in response to DEX were identified by RNA sequencing followed by differential gene expression analysis. Coincident with the milk yield and composition changes was the differential expression of 519 and 320 genes at 12 and 24 h after DEX (adjusted p <0 .05), respectively, with the return of all gene expression to baseline levels by 72 h. Among the transcriptomic changes in response to DEX, there was notable downregulation of elements in the lactose synthesis pathway, specifically AQP3, GALE and LALBA (α-lactalbumin) at 12 h, and sustained downregulation of LALBA at 24 h. One gene in the pathway, UGP2, was upregulated at 12-24 h post-DEX. This work supports the hypothesis that there is a direct relationship between the response to DEX and the concurrent suppression of milk yield due to the reduced synthesis of α-lactalbumin and lactose by the mammary epithelium. The ability of glucocorticoids to modulate the homeorrhetic requirements for glucose during stressful states concurrent with immune activation bears significance for dairy animals as well as a broad range of lactating mammals.

Role of milk glycome in prevention, treatment, and recovery of COVID-19

Milk contains all essential macro and micro-nutrients for the development of the newborn. Its high therapeutic and antimicrobial content provides an important function for the prevention, treatment, and recovery of certain diseases throughout life. The bioactive components found in milk are mostly decorated with glycans, which provide proper formation and modulate the biological functions of glycosylated compounds. The glycome of milk consists of free glycans, glycolipids, and N- and O- glycosylated proteins. Recent studies have shown that both free glycans and glycan-containing molecules have antiviral characteristics based on different mechanisms such as signaling, microbiome modulation, natural decoy strategy, and immunomodulatory action. In this review, we discuss the recent clinical studies and potential mechanisms of free and conjugated glycans' role in the prevention, treatment, and recovery of COVID-19.

Identification and annotation of milk associated genes from milk somatic cells using expression and RNA-seq data

It is of interest to identify and annotate milk associated genes using expression profiling and RNA-Seq data from milk somatic cells. RNA-Seq data was pre-processed and mapping was done to identify differentially expressed genes (DEG). The functional insights about the up and down regulated genes were gleaned using the protein-protein interaction Network in the STRING database followed by CytoHubba analysis in Cytoscope. Gene ontology, annotation and pathway enrichment was completed using ShinyGO, David tool and QTL analysis. These analysis shows that 21 genes are linked with the secretion of milk.

The effect of preoperative oral carbohydrate on the time to colostrum and amount of vaginal bleeding after elective cesarean section

OBJECTIVE

To investigate the effect of oral carbohydrate at 2 h before elective cesarean section on postoperative recovery indicators such as the time to colostrum and vaginal bleeding.

METHODS

Women undergoing elective cesarean section under spinal-epidural anesthesia, aged 20-40 years, with a body mass index (BMI) of 19-30 kg/m² and an American Society of Anesthesiology (ASA) score of II were randomized to the oral carbohydrate group (the OC group), the oral placebo group (the OP group), or the control group (the C group). The OC group underwent oral carbohydrate preloading (300 mL/bottle), the OP group orally consumed 300 mL of distilled water, and the C group was forbidden from drinking or eating on the day of the operation. The time to colostrum, vaginal bleeding, time to exhaust, and complications were recorded.

RESULTS

A total of 38 participants in the OC group, 37 in the OP group, and 37 in the C group completed the study. Compared with the OP group and the C group, the OC group produced colostrum significantly earlier, had a lower amount of 24-h vaginal bleeding, and had a higher 24-h consumption of analgesics. Compared with OP and OC groups, the C group took longer to exhaust. No significant intergroup difference was observed for any other indicator.

CONCLUSION

Oral carbohydrates loading 2 h before elective cesarean section significantly reduces the time to produce colostrum and the amount of vaginal bleeding, which contributes to postoperative recovery.

Milking It for All It's Worth: The Effects of Environmental Enrichment on Maternal Nurturance, Lactation Quality, and Offspring Social Behavior

Breastfeeding confers robust benefits to offspring development in terms of growth, immunity, and neurophysiology. Similarly, improving environmental complexity, i.e., environmental enrichment (EE), contributes developmental advantages to both humans and laboratory animal models. However, the impact of environmental context on maternal care and milk quality has not been thoroughly evaluated, nor are the biological underpinnings of EE on offspring development understood. Here, Sprague Dawley rats were housed and bred in either EE or standard-housed (SD) conditions. EE dams gave birth to a larger number of pups, and litters were standardized and cross-fostered across groups on postnatal day (P)1. Maternal milk samples were then collected on P1 (transitional milk phase) and P10 (mature milk phase) for analysis. While EE dams spent less time nursing, postnatal enrichment exposure was associated with heavier offspring bodyweights. Milk from EE mothers had increased triglyceride levels, a greater microbiome diversity, and a significantly higher abundance of bacterial families related to bodyweight and energy metabolism. These differences reflected comparable transcriptomic changes at the genome-wide level. In addition to changes in lactational quality, we observed elevated levels of cannabinoid receptor 1 in the hypothalamus of EE dams, and sex-dependent and time-dependent effects of EE on offspring social behavior. Together, these results underscore the multidimensional impact of the combined neonatal and maternal environments on offspring development and maternal health. Moreover, they highlight potential deficiencies in the use of "gold standard" laboratory housing in the attempt to design translationally relevant animal models in biomedical research.

Profiling of mature-stage human breast milk cells identifies six unique lactocyte subpopulations

Breast milk is chock-full of nutrients, immunological factors, and cells that aid infant development. Maternal cells are the least studied breast milk component, and their unique properties are difficult to identify using traditional techniques. Here, we characterized the cells in mature-stage breast milk from healthy donors at the protein, gene, and transcriptome levels. Holistic analysis of flow cytometry, quantitative polymerase chain reaction, and single-cell RNA sequencing data identified the predominant cell population as epithelial with smaller populations of macrophages and T cells. Two percent of epithelial cells expressed four stem cell markers: SOX2, TRA-1-60, NANOG, and SSEA4. Furthermore, milk contained six distinct epithelial lactocyte subpopulations, including three previously unidentified subpopulations programmed toward mucosal defense and intestinal development. Pseudotime analysis delineated the differentiation pathways of epithelial progenitors. Together, these data define healthy human maternal breast milk cells and provide a basis for their application in maternal and infant medicine.

Measures of Maternal Metabolic Health as Predictors of Severely Low Milk Production

Background: A comprehensive approach to breastfeeding support requires elucidation of how metabolic health influences milk production. Objective: We compared metabolic health indicators in women with severely low milk output versus those with moderate/normal milk output using a case-control study design, with nested and external control groups. Design: Cases and nested controls were derived from women screened for a low milk supply trial, with cases defined as severely low milk output (<300 mL/24 hours), and nested controls defined as moderate/normal milk output (>300 mL/24 hours). In addition, we included an external control group of exclusively breastfeeding women. All were enrolled at 2-10 weeks postdelivery of a healthy term infant. Milk output and breast emptying frequency were recorded through test-weigh. Metabolic health variables included all components of the metabolic syndrome, homeostatic model assessment of insulin resistance (HOMA-IR), and diagnosis of gestational diabetes mellitus (GDM). Results: Maximum milk output, mL/24 hours, ranged as follows: 30-281 in cases (n = 18), 372-801 in nested controls (n = 12), and 661-915 in external controls (n = 12). Mean breast emptying frequency in cases was not significantly different from nested or external controls. All metabolic syndrome components and HOMA-IR were significantly worse in cases as compared with both nested and external control groups (p < 0.05). There was no significant difference between the nested and external control groups for these variables. GDM prevalence was 39%, 0%, and 8%, across cases, nested control, and external control groups, respectively (chi-square p-value = 0.02). Conclusion: Results from this small case-control study identify class 2+ obesity and poor metabolic health as strong risk factors for severely low milk production. These findings should be further validated in larger prospective cohort studies designed to identify individuals at risk for metabolically driven low milk supply. In addition, clinical and qualitative research studies aimed at improving patient-centered approaches to the management of persistent low milk supply are needed.

DHA Supplementation Attenuates Inflammation-Associated Gene Expression in the Mammary Gland of Lactating Mothers Who Deliver Preterm

BACKGROUND

In a randomized trial of DHA supplementation to lactating mothers who delivered preterm, there were significant increases in DHA status in the mother and her infant.

OBJECTIVES

Our objective here was to characterize the mammary gland transcriptomes from the above study. We hypothesized that proinflammatory gene expression would be attenuated in the increased DHA group compared with the standard DHA group.

METHODS

In the original trial, mothers delivering at <29 wk gestation at the University of Cincinnati Medical Center and intending to express their milk were randomly assigned to supplementation with 200 mg/d DHA (standard group: STD) or 1000 mg/d DHA (experimental group: EXP) within 7 d of delivery. Here, we conducted RNA-seq transcriptome analysis of n = 5 EXP and n = 4 STD extracellular mammary mRNA samples extracted from the fat layer of milk samples obtained 4 wk postenrollment. Transcripts were assessed for differential expression (false discovery rate adjusted P value <0.05) and clustering between EXP compared with STD groups. Ontological analysis of all differentially expressed genes (DEGs) was performed with Toppcluster.

RESULTS

There were 409 DEGs. We observed 5 main groups of biological processes that were upregulated, including those associated with improved immune regulation and management of oxidative stress; and 3 main groups of biological processes that were downregulated, including 1 associated with immune dysregulation. For example, we observed upregulation of inflammation-inhibiting genes including NFKB inhibitor alpha (NFKBIA; fold-change (FC), adjusted P value: FC = 1.70, P = 0.007) and interleukin-18 binding protein (IL18BP: FC = 2.2, adjusted P = 0.02); and downregulation of proinflammatory genes including interleukin 7 receptor (IL7R: FC = -1.9, adjusted P = 0.02) and interleukin 1 receptor like 1 (IL1RL1: FC = -13.0, adjusted P = 0.02).

CONCLUSIONS

Increased DHA supplementation during lactation can modulate the expression of inflammation-related genes within the mammary gland. This might translate to milk composition with a more optimal inflammasome profile. Future research with a larger clinical trial and greater interrogation of clinical outcomes is warranted.

Time-resolved quantitative phosphoproteomics reveals cellular responses induced by caffeine and coumarin

Protein phosphorylation is a critical way that cells respond to external signals and environmental stresses. However, the patterns of cellular response to chemicals at different times were largely unknown. Here, we used quantitative phosphoproteomics to analyze the cellular response of kinases and signaling pathways, as well as pattern change of phosphorylated substrates in HepG2 cells that were exposed to caffeine and coumarin for 10 min and 24 h. Comparing the 10 min and 24 h groups, 33 kinases were co-responded and 32 signaling pathways were co-enriched in caffeine treated samples, while 48 kinases and 34 signaling pathways were co-identified in coumarin treated samples. Instead, the percentage of co-identified phosphorylated substrates only accounted for 4.31% and 9.57% between 10 min and 24 h in caffeine and coumarin treated samples, respectively. The results showed that specific chemical exposure led to a bunch of the same kinases and signaling pathways changed in HepG2 cells, while the phosphorylated substrates were different. In addition, it was found that insulin signaling pathway was significantly enriched by both the caffeine and coumarin treatment. The pattern changes in phosphorylation of protein substrates, kinases and signaling pathways with varied chemicals and different time course shed light on the potential mechanism of cellular responses to endless chemical stimulation.

Elucidating Human Milk Oligosaccharide biosynthetic genes through network-based multi-omics integration

Human Milk Oligosaccharides (HMOs) are abundant carbohydrates fundamental to infant health and development. Although these oligosaccharides were discovered more than half a century ago, their biosynthesis in the mammary gland remains largely uncharacterized. Here, we use a systems biology framework that integrates glycan and RNA expression data to construct an HMO biosynthetic network and predict glycosyltransferases involved. To accomplish this, we construct models describing the most likely pathways for the synthesis of the oligosaccharides accounting for >95% of the HMO content in human milk. Through our models, we propose candidate genes for elongation, branching, fucosylation, and sialylation of HMOs. Our model aggregation approach recovers 2 of 2 previously known gene-enzyme relations and 2 of 3 empirically confirmed gene-enzyme relations. The top genes we propose for the remaining 5 linkage reactions are consistent with previously published literature. These results provide the molecular basis of HMO biosynthesis necessary to guide progress in HMO research and application with the goal of understanding and improving infant health and development.

Human milk oligosaccharides are fundamental to infant health. Here the authors deploy a multi-omics systems biology approach to elucidate their biosynthetic network, including the associated enzymes and likely structures of ambiguous oligosaccharides.

Reliability of an Ion-Selective Electrode as a Simple Diagnostic Tool for Mastitis

BACKGROUND

Developing a simple quantitative tool for mastitis diagnosis is essential. The Ion-Selective Electrode for sodium has been reported to reliably measure sodium concentrations in human milk.

RESEARCH AIM

To determine whether an Ion-Selective Electrode measurement of sodium:potassium ratios could serve as a diagnostic tool for mastitis and, if so, to determine the diagnostic cut-off value.

METHODS

A total of 107 milk samples, including 55 from milk bank donors and 52 from participants with mastitis, were studied. The sodium:potassium ratios were determined in 33 samples (without mastitis n = 15; with mastitis n = 18) by the Ion-Selective Electrode and ion chromatography. The remaining 74 samples (donor milk n = 40; participants with mastitis n = 34) were analyzed by Ion-Selective Electrode only. Values were averaged over three measurements for each method.

RESULTS

The median postpartum months of donors and participants with mastitis were 2 and 3 months, respectively. The mean (SD) sodium:potassium ratios without and with mastitis were 0.5 (0.1) and 1.7 (1.2), respectively. A positive correlation existed between sodium:potassium ratios obtained from the two methods (r = 0.98). Area under the curve values were 0.951 (95% CI [0.904, 0.986]) for the Ion-Selective Electrode (N = 107) and 0.978 (95% CI [0.926, 1.000]) for the ion chromatography (n = 33) methods. The optimal cut-off value for the Ion-Selective Electrode method was 0.60, with 86.5% sensitivity and 92.7% specificity.

CONCLUSIONS

The Ion-Selective Electrode was sufficiently accurate for the diagnosis of mastitis. Cohort studies are needed to explore the relationship between sodium:potassium ratios and clinical outcomes.

Cellular and transcriptional diversity over the course of human lactation

Human breast milk (hBM) is a dynamic fluid that contains millions of cells, but their identities and phenotypic properties are poorly understood. We generated and analyzed single-cell RNA-sequencing (scRNA-seq) data to characterize the transcriptomes of cells from hBM across lactational time from 3 to 632 d postpartum in 15 donors. We found that the majority of cells in hBM are lactocytes, a specialized epithelial subset, and that cell-type frequencies shift over the course of lactation, yielding greater epithelial diversity at later points. Analysis of lactocytes reveals a continuum of cell states characterized by transcriptional changes in hormone-, growth factor-, and milk production-related pathways. Generalized additive models suggest that one subcluster, LC1 epithelial cells, increases as a function of time postpartum, daycare attendance, and the use of hormonal birth control. We identify several subclusters of macrophages in hBM that are enriched for tolerogenic functions, possibly playing a role in protecting the mammary gland during lactation. Our description of the cellular components of breast milk, their association with maternal–infant dyad metadata, and our quantification of alterations at the gene and pathway levels provide a detailed longitudinal picture of hBM cells across lactational time. This work paves the way for future investigations of how a potential division of cellular labor and differential hormone regulation might be leveraged therapeutically to support healthy lactation and potentially aid in milk production.

Human Breast Milk: From Food to Active Immune Response With Disease Protection in Infants and Mothers

Breastfeeding is associated with long-term wellbeing including low risks of infectious diseases and non-communicable diseases such as asthma, cancer, autoimmune diseases and obesity during childhood. In recent years, important advances have been made in understanding the human breast milk (HBM) composition. Breast milk components such as, non-immune and immune cells and bioactive molecules, namely, cytokines/chemokines, lipids, hormones, and enzymes reportedly play many roles in breastfed newborns and in mothers, by diseases protection and shaping the immune system of the newborn. Bioactive components in HBM are also involved in tolerance and appropriate inflammatory response of breastfed infants if necessary. This review summarizes the current literature on the relationship between mother and her infant through breast milk with regard to disease protection. We will shed some light on the mechanisms underlying the roles of breast milk components in the maintenance of health of both child and mother.

Antiviral properties of whey proteins and their activity against SARS-CoV-2 infection

Native and chemically modified whey proteins and their peptide derivatives are encountering the interest of nutraceutical and pharmaceutical industries, due to the numerous properties, ranging from antimicrobial to immunological and antitumorigenic, that result in the possibility to employ milk and its protein components in a wide range of treatment and prevention strategies. Importantly, whey proteins were found to exert antiviral actions against different enveloped and non-enveloped viruses. Recently, the scientific community is focusing on these proteins, especially lactoferrin, since in vitro studies have demonstrated that they exert an important antiviral activity also against SARS-CoV-2. Up-to date, several studies are investigating the efficacy of lactoferrin and other whey proteins in vivo. Aim of this review is to shed light on the most relevant findings concerning the antiviral properties of whey proteins and their potential applications in human health, focussing on their application in prevention and treatment of SARS-CoV-2 infection.

Use of a Portable Point-of-Care Instrumentation to Measure Human Milk Sodium and Potassium Concentrations

Objective: Human milk (HM) sodium (Na) and potassium (K) concentrations, as well as the Na and K ratio (Na:K), are associated with stages of lactation and breast health. Portable point-of-care instruments to measure HM biomarkers related to secretory activation or tight junction disturbances would supply clinicians immediate information for individualized lactation care. This study compared HM concentrations of Na and K and Na:K measured by a biochemist with inductively coupled plasma optical emission spectrometry (ICP-OES) and measured by a clinician with ion-selective electrode probes (ISEPs). Design: HM samples (n = 92) were participant collected and donated on day 10 postpartum through a convenience sample of breastfeeding women in West Michigan. Na and K concentrations were determined using ICP-OES and ISEPs. Bland-Altman plots, paired sample t-test, and logistic regressions were completed using R 3.4.4 and R Studio 1.2.1335 with package Lattice. Results: Na concentrations were not significantly different with ICP-OES (13.0 ± 14.8 mM) and ISEPs (12.6 ± 13.7 mM, p = 0.06), whereas K concentrations (ICP-OES 16.1 ± 1.9 mM, ISEPs 14.4 ± 2.4 mM, p < 0.001) and Na:K (ICP-OES 0.81 ± 0.92, ISEPs 1.01 ± 1.62, p = 0.011) were significantly different. Between both methods, the Na, K, and Na: K linear relationships were statistically significant. Conclusion: With additional longitudinal and clinical usefulness research clinicians could use ISEPs to collect and interpret relevant lactation data to support individualized lactation interventions.

Quantification of FAM20A in human milk and identification of calcium metabolism proteins

BACKGROUND

FAM20A, a recently discovered protein, is thought to have a fundamental role in inhibiting ectopic calcification. Several studies have demonstrated that variants of FAM20A are causative for the rare autosomal recessive disorder, enamel-renal syndrome (ERS). ERS is characterized by defective mineralization of dental enamel and nephrocalcinosis suggesting that FAM20A is an extracellular matrix protein, dysfunction of which causes calcification of the secretory epithelial tissues. FAM20A is a low-abundant protein that is difficult to detect in biofluids such as blood, saliva, and urine. Thus, we speculated the abundance of FAM20A to be high in human milk, since the secretory epithelium of lactating mammary tissue is involved in the secretion of highly concentrated calcium. Therefore, the primary aim of this research is to describe the processes/methodology taken to quantify FAM20A in human milk and identify other proteins involved in calcium metabolism.

METHOD

This study used mass spectrometry-driven quantitative proteomics: (1) to quantify FAM20A in human milk of three women and (2) to identify proteins associated with calcium regulation by bioinformatic analyses on whole and milk fat globule membrane fractions.

RESULTS

Shotgun MS/MS driven proteomics identified FAM20A in whole milk, and subsequent analysis using targeted proteomics also successfully quantified FAM20A in all samples. Combination of sample preparation, fractionation, and LC-MS/MS proteomics analysis generated 136 proteins previously undiscovered in human milk; 21 of these appear to be associated with calcium metabolism.

CONCLUSION

Using mass spectrometry-driven proteomics, we successfully quantified FAM20A from transitional to mature milk and obtained a list of proteins involved in calcium metabolism. Furthermore, we show the value of using a combination of both shotgun and targeted driven proteomics for the identification of this low abundant protein in human milk.

Impaired Lactation: Review of Delayed Lactogenesis and Insufficient Lactation

It is estimated that as many as 1 in 20 women worldwide are unable to successfully breastfeed or provide adequate nutrition for their infants through their breast milk alone. Compromised nutrition in the early stages of life places the infant at risk for insufficient growth as well as serious and potentially disabling or life-threatening complications. This review summarizes risk factors associated with impaired lactation that may result in either delayed lactogenesis or insufficient lactation. The risk factors for insufficient lactation are categorized into preglandular, glandular, and postglandular causes. Impaired lactation can occur despite maternal motivation, knowledge, support, and appropriate breastfeeding technique. Although there is no clear way to predict who will experience impaired lactation, knowledge about the risk factors can enable health care professionals to better identify at-risk mother-infant dyads. Early intervention may help prevent infant complications associated with inadequate nutritional intake.

Metabolic Conditions Including Obesity, Diabetes, and Polycystic Ovary Syndrome: Implications for Breastfeeding and Breastmilk Composition

Breastfeeding is internationally recognized as the recommended standard for infant nutrition, informed by evidence of its multiple benefits for both mother and baby. In the context of common metabolic conditions such as polycystic ovary syndrome, diabetes (type 1, type 2, and gestational), and obesity, breastfeeding may be particularly beneficial for both mother and infant. However, there is evidence of delayed lactogenesis and reduced breastfeeding rates and duration in women with these conditions, and the effects of altered maternal metabolic environments on breastmilk composition (and potentially infant outcomes) are incompletely understood. In this review, we explore the relationships between maternal metabolic conditions, lactogenesis, breastfeeding, and breastmilk composition. We examine relevant potential mechanisms, including the central role of insulin both in lactogenesis and as a milk-borne hormone. We also describe the bioactive and hormonal components of breastmilk and how these may link maternal and infant health.

Breastfeeding support and barriers to women with gestational diabetes mellitus: a nationwide cross-sectional survey of hospitals in Japan

BACKGROUND

Despite the benefits of breastfeeding for women with Gestational Diabetes Mellitus (GDM) and their infants, breastfeeding is less likely to be performed by this group. This study aimed to examine the current levels of implementation of breastfeeding support to women with GDM in Japan and to clarify barriers to promoting breastfeeding among this population.

METHODS

A 25-item questionnaire was developed by the authors to investigate the current levels of implementation of breastfeeding support for women with GDM provided in hospitals, and to explore barriers for promoting breastfeeding among these women. The questionnaire was sent to all 1046 hospitals facilitating childbirth in Japan. Descriptive statistics were used to analyze the quantitative data, and content analysis was used to analyze qualitative data from the open-ended questions.

RESULTS

All 296 respondents were included in this study. Regarding breastfeeding support, 95.2% of the respondents provided general information on breastfeeding to GDM women during antenatal midwife consultations. However, the benefits of breastfeeding for preventing type 2 diabetes were addressed by only 48.0%. Likewise, although follow-up services (e.g., telephone support or breastfeeding consultations) were conducted in 88.9% of hospitals, only 50.7% of hospitals informed women that breastfeeding decreases the risk of developing type 2 diabetes after GDM. Regarding barriers, seven categories and 20 subcategories about promoting breastfeeding for women with GDM were extracted and abstracted into the following three themes: Barriers associated with mother and infant, Barriers associated with health professionals, and Organizational barriers.

CONCLUSIONS

In Japan, most hospitals that responded provided general breastfeeding support from the antenatal to postpartum periods. However, the benefits of breastfeeding in terms of preventing the incidence of type 2 diabetes following GDM were insufficiently communicated to women with GDM. Furthermore, there were numerous barriers to promoting breastfeeding among women with GDM.

Characterization and comparative analysis of transcriptional profiles of porcine colostrum and mature milk at different parities

BACKGROUND

Porcine milk is a complex fluid, containing a myriad of immunological, biochemical, and cellular components, made to satisfy the nutritional requirements of the neonate. Whole milk contains many different cell types, including mammary epithelial cells, neutrophils, macrophages, and lymphocytes, as well nanoparticles, such as milk exosomes. To-date, only a limited number of livestock transcriptomic studies have reported sequencing of milk. Moreover, those studies focused only on sequencing somatic cells as a proxy for the mammary gland with the goal of investigating differences in the lactation process. Recent studies have indicated that RNA originating from multiple cell types present in milk can withstand harsh environments, such as the digestive system, and transmit regulatory molecules from maternal to neonate. Transcriptomic profiling of porcine whole milk, which is reflective of the combined cell populations, could help elucidate these mechanisms. To this end, total RNA from colostrum and mature milk samples were sequenced from 65 sows at differing parities. A stringent bioinformatic pipeline was used to identify and characterize 70,841 transcripts.

RESULTS

The 70,841 identified transcripts included 42,733 previously annotated transcripts and 28,108 novel transcripts. Differential gene expression analysis was conducted using a generalized linear model coupled with the Lancaster method for P-value aggregation across transcripts. In total, 1667 differentially expressed genes (DEG) were identified for the milk type main effect, and 33 DEG were identified for the milk type x parity interaction. Several gene ontology (GO) terms related to immune response were significant for the milk type main effect, supporting the well-known fact that immunoglobulins and immune cells are transferred to the neonate via colostrum.

CONCLUSIONS

This is the first study to perform global transcriptome analysis from whole milk samples in sows from different parities. Our results provide important information and insight into synthesis of milk proteins and innate immunity and potential targets for future improvement of swine lactation and piglet development.

Is There an Association Between Breast Hypoplasia and Breastfeeding Outcomes? A Systematic Review

Introduction: Insufficient milk supply is the most common reason for premature breastfeeding cessation. Breast hypoplasia is one reason why women may be inherently unable to make a full milk supply. This review aimed to systematically explore the relationship between breast hypoplasia and breastfeeding duration, milk supply, and lactation onset. Materials and Methods: Medline, CINAHL, ProQuest Central, and the Cochrane Library databases were searched using the keywords "insufficient glandular tissue" or "mammary hypoplasia" or "breast hypoplasia" or "mammary gland hypoplasia" or "droopy breasts" or "snoopy deformity" or "tubular breast*" or "tuberous breast*" AND breastfeeding or "breast feeding" or breast-feeding or lactation. After initially screening 20 records, including reference lists, 9 full texts were assessed for eligibility; 2 were excluded as no breastfeeding outcomes were reported, leaving 7 studies (N = 42 women). Results: The studies in this review drew on results from the oldest included study and plastic surgery literature to define breast hypoplasia. Most women in this review (40/42) ceased exclusive breastfeeding before 1 month postpartum. One case study reported 24-hour milk production, which was 52 mL at 26 weeks postpartum. Conclusion: The relationship between breast hypoplasia and breastfeeding outcomes is underresearched. The co-occurring medical conditions (e.g., polycystic ovary syndrome) of some women provide avenues for future research into the possible pathogenesis of breast hypoplasia resulting in insufficient milk supply. Research is needed to evaluate the reliability of measuring and classifying markers of breast hypoplasia, and prospective studies can help determine the role of breast hypoplasia in milk production. PROSPERO registration number CRD42020191228.

Indicators of Secretory Activation in Mothers of Preterm Very Low Birth Weight Infants

BACKGROUND

Inconsistent information exists regarding indicators of secretory activation in mothers delivering very low birth weight infants.

RESEARCH AIMS

To compare time to the onset of secretory activation using three separate indicators. A secondary aim examined the association between indicators of secretory activation and milk production.

METHODS

Indicators of secretory activation included maternal perception, volume attainment (production of ≥ 20 mL in two consecutive expression sessions) and biomarkers (sodium and lactose) obtained at volume attainment. Milk production was measured on Days 1-7 and then weekly for 6 weeks.

RESULTS

In 69 mothers of infants born ≤ 32 weeks' gestation and < 1500 g, we found no correlation in time to secretory activation between indicators. Earlier volume attainment was associated with increased milk production on Days 1-7, 14, 21, and 28 (all p < .007). Participants who exhibited both normal lactose and sodium levels produced more milk on Days 28 and 42 (p = .028 and .011), those with only normal lactose levels produced more on Day 42 (p = .026) and those with only normal sodium levels on Day 28 (p = .036). Earlier secretory activation by volume attainment was associated with increased expression frequency during Days 2-5 (all p < .014) and participants with normal biomarkers expressed more frequently during Days 2-5 (all p < .020).

CONCLUSION

Mothers of very low birth weight infants are at risk for delayed secretory activation, which may decrease their milk production. Frequent expression during the first 5 days postpartum may promote earlier secretory activation. Valid methods of determining secretory activation are necessary to develop interventions promoting earlier secretory activation.

Monitoring Human Milk β-Casein Phosphorylation and O-Glycosylation Over Lactation Reveals Distinct Differences between the Proteome and Endogenous Peptidome

Human milk is a vital biofluid containing a myriad of molecular components to ensure an infant’s best start at a healthy life. One key component of human milk is β-casein, a protein which is not only a structural constituent of casein micelles but also a source of bioactive, often antimicrobial, peptides contributing to milk’s endogenous peptidome. Importantly, post-translational modifications (PTMs) like phosphorylation and glycosylation typically affect the function of proteins and peptides; however, here our understanding of β-casein is critically limited. To uncover the scope of proteoforms and endogenous peptidoforms we utilized mass spectrometry (LC-MS/MS) to achieve in-depth longitudinal profiling of β-casein from human milk, studying two donors across 16 weeks of lactation. We not only observed changes in β-casein’s known protein and endogenous peptide phosphorylation, but also in previously unexplored O-glycosylation. This newly discovered PTM of β-casein may be important as it resides on known β-casein-derived antimicrobial peptide sequences.

Production of the infant formula ingredient 1,3-olein-2-palmitin in Arabidopsis thaliana seeds

In human milk fat, palmitic acid (16:0) is esterified to the middle (sn-2 or β) position on the glycerol backbone and oleic acid (18:1) predominantly to the outer positions, giving the triacylglycerol (TG) a distinctive stereoisomeric structure that is believed to assist nutrient absorption in the infant gut. However, the fat used in most infant formulas is derived from plants, which preferentially esterify 16:0 to the outer positions. We have previously showed that the metabolism of the model oilseed Arabidopsis thaliana can be engineered to incorporate 16:0 into the middle position of TG. However, the fatty acyl composition of Arabidopsis seed TG does not mimic human milk, which is rich in both 16:0 and 18:1 and is defined by the high abundance of the TG molecular species 1,3-olein-2-palmitin (OPO). Here we have constructed an Arabidopsis fatty acid biosynthesis 1-1 fatty acid desaturase 2 fatty acid elongase 1 mutant with around 20% 16:0 and 70% 18:1 in its seeds and we have engineered it to esterify more than 80% of the 16:0 to the middle position of TG, using heterologous expression of the human lysophosphatidic acid acyltransferase isoform AGPAT1, combined with suppression of LYSOPHOSPHATIDIC ACID ACYLTRANSFERASE 2 and PHOSPHATIDYLCHOLINE:DIACYLGLYCEROL CHOLINEPHOSPHOTRANSFERASE. Our data show that oilseeds can be engineered to produce TG that is rich in OPO, which is a structured fat ingredient used in infant formulas.

A Comparative Review of the Cell Biology, Biochemistry, and Genetics of Lactose Synthesis

Lactose is the primary carbohydrate in the milk of most mammals and is unique in that it is only synthesized by epithelial cells in the mammary glands. Lactose is also essential for the development and nutrition of infants. Across species, the concentration of lactose in milk holds a strong positive correlation with overall milk volume. Additionally, there is a range of examples where the onset of lactose synthesis as well as the content of lactose in milk varies between species and throughout a lactation. Despite this diversity, the precursors, genes, proteins and ions that regulate lactose synthesis have not received the depth of study they likely deserve relative to the significance of this simple and abundant molecule. Through this review, our objective is to highlight the requirements for lactose synthesis at the biochemical, cellular and temporal levels through a comparative approach. This overview also serves as the prelude to a companion review describing the dietary, hormonal, molecular, and genetic factors that regulate lactose synthesis.

Measures of Lactation Outcomes in Women Delivering Preterm Infants

BACKGROUND

Mother's own milk (MOM) is well known to decrease prematurity-related morbidities, yet mothers delivering preterm infants often produce insufficient quantities of milk to provide these benefits. Although a critical need exists for research to support lactation success in this vulnerable population, development and investigation of interventions to increase available MOM for infant consumption requires consistent, valid, and reliable measures of lactation outcomes.

OBJECTIVES

The aim of this study was to compare and contrast methods of measuring lactation outcomes in mothers of preterm infants and evaluate their advantages and disadvantages.

METHODS

Measures of lactation outcomes were reviewed and synthesized. Insights on best practices and future research directions are provided.

RESULTS

Volume of MOM produced, lactation duration, and time to onset of secretory activation are important measures of lactation success. The most valid and reliable measure of milk production is likely weighing each vial of expressed milk combined with test weighing when infants breastfeed. Measures of lactation duration should include actual days mothers lactated rather than limiting to infant consumption of MOM as a proxy for duration and include not only whether mothers are lactating at infant discharge but whether they are also lactating at other health-relevant time points during hospitalization. Although time to onset of secretory activation is an important lactation outcome, information regarding valid and reliable indicators of onset in women delivering preterm infants is limited, and investigation of such indicators is a research priority. Variables that may affect lactation outcomes, including time to initiation of expression following delivery, duration of expression sessions, expression method, time spent in skin-to-skin care, maternal demographics and comorbidities, as well as maternal intent to lactate, must be considered when researchers investigate lactation outcomes in mothers of very low birth weight infants.

DISCUSSION

Consistent and valid measures of lactation outcomes are required to produce reliable results from which evidence-based practice recommendations can be developed in order to improve lactation success in this vulnerable population.

ExHuMId: A curated resource and analysis of Exposome of Human Milk across India

Human milk is a vital source of nourishment for infants. However, numerous environmental contaminants also find their way into human milk, making up the major part of a newborn's external exposome. While there are chemical regulations in India and scientific literature on environmental contaminants is available, the systematic compilation, monitoring, and risk management of human milk contaminants are inadequate. We have harnessed the potential of this large body of literature to develop the Exposome of Human Milk across India (ExHuMId) version 1.0 containing detailed information on 101 environmental contaminants detected in human milk samples across 13 Indian states, compiled from 36 research articles. ExHuMId also compiles the detected concentrations of the contaminants, structural and physicochemical properties, and factors associated with the donor of the sample. We also present findings from a three-pronged analysis of ExHuMId and two other resources on human milk contaminants, with a focus on the Indian scenario. Through a comparative analysis with global chemical regulations and guidelines, we identify human milk contaminants of high concern, such as potential carcinogens, endocrine disruptors and neurotoxins. We then study the physicochemical properties of the contaminants to gain insights on their propensity to transfer into human milk. Lastly, we employ a systems biology approach to shed light on potential effects of human milk contaminants on maternal and infant health, by identifying contaminant-gene interactions associated with lactation, cytokine signalling and production, and protein-mediated transport. ExHuMId 1.0 is accessible online at: https://cb.imsc.res.in/exhumid/.

Breastfeeding Success Among Women with Gestational Diabetes Managed by Diet Only Compared with Those Requiring Medications

Objective: Breastfeeding is known to have a positive impact on maternal and neonatal health. Some have suggested that gestational diabetes mellitus (GDM) is associated with lower breastfeeding rates, but it is not known whether rates are further impacted by glucose control in pregnancy. Thus, we examined whether patients with GDM requiring medication (A2 GDM) were more likely to not initiate or discontinue breastfeeding compared with patients with GDM well controlled by diet (A1 GDM). Research Design and Methods: This is a secondary analysis of a prospective cohort study of 600 patients with GDM. Eligible patients were enrolled during their delivery hospitalization and followed prospectively postpartum. The primary outcome was exclusive breastfeeding at hospital discharge and secondary outcomes included breastfeeding rates at 3 months postpartum. Patients classified as A2 GDM were compared with those classified as A1 GDM. Results: Of the 600 patients enrolled, 301 had A2 GDM and 299 had A1 GDM. Patients who needed medication were observed to be older and more likely to be parous and obese. There were no significant differences in labor outcomes or neonatal complications. After adjusting for baseline differences between the two groups, adjusted odds ratios (aORs) for exclusive breastfeeding rates were similar in mothers with A2 GDM compared with those with A1 GDM at hospital discharge (aOR 0.83 [0.54-1.28]) and 3 months postpartum (aOR 0.58 [0.34-1.01]). Additionally, any breastfeeding rates were similar in mothers with A2 GDM compared with those with A1 GDM, both at hospital discharge (aOR 0.72 [0.44-1.16]) and 3 months postpartum (aOR 0.63 [0.34-1.17]). Conclusions: After adjusting for baseline differences, there was no difference in any or exclusive breastfeeding rates at hospital discharge or 3 months postpartum among patients with A2 GDM compared with those with A1 GDM.

Personalized Profiling Reveals Donor- and Lactation-Specific Trends in the Human Milk Proteome and Peptidome

BACKGROUND

Human milk is the most genuine form of personalized nutrition, whereby its nutritional and bioactive constituents support the changing needs of the growing infant. Personalized proteome profiling strategies may provide insights into maternal-infant relationships. Proteins and endogenous peptides in human milk play an important role as nutrients for growth and have distinct functionality such as immune defense. Comprehensive monitoring of all of the human milk proteinaceous components, including endogenous peptides, is required to fully understand the changing role of the human milk proteome throughout lactation.

OBJECTIVE

We aimed to investigate the personalized nature of the human milk proteome and peptidome for individual mother-infant dyads.

METHODS

Two individual healthy milk donors, aged 29 and 32 y and both of a normal BMI, were longitudinally observed over weeks 1, 2, 3, 4, 6, 8, 10, 12, and 16 postpartum. Milk collection was standardized. Comprehensive variations in the human milk proteinaceous components were assessed using quantitative LC-MS/MS methods.

RESULTS

We longitudinally profiled the concentrations of >1300 milk proteins and 2000 endogenous milk peptides spanning 16 wk of lactation for 2 individual donors. We observed many gradual and alike changes in both donors related to temporal effects, for instance early lactation was marked by high concentrations of proteins and peptides involved in lactose synthesis and immune development. Uniquely, in 1 of the 2 donors, we observed a substantial anomaly in the milk composition, exclusively at week 6, likely indicating a response to inflammation and/or infection.

CONCLUSIONS

Here, we provide a resource for characterizing the lactational changes in the human milk proteome, encompassing thousands of proteins and endogenous peptides. Further, we demonstrate the feasibility and benefit of personalized profiling to monitor the influence of milk on the development of the newborn, as well as the health status of each individual mother-infant pair.

First-Day Use of the Newborn Weight Loss Tool to Predict Excess Weight Loss in Breastfeeding Newborns

Background and Objectives: Exclusive breastfeeding is recommended for most newborns. However, exclusively breastfed newborns sometimes experience excess weight loss (EWL, loss ≥10% of birth weight) while lactation is being established. Our primary objective was to evaluate the sensitivity and specificity of the Newborn Weight Loss Tool (NEWT) in early identification of exclusively breastfed newborns who develop EWL; and secondarily, identify breastfeeding variables associated with an at-risk NEWT trajectory. Materials and Methods: We conducted a secondary analysis of prospective data from mother-infant dyads screened for inclusion in the U.S. site of the WHO Growth Reference Study. We excluded records if: NEWT-specific criteria not met, missing key data, or >60 mL formula consumed. We defined NEWT "test-positive" based on an in-hospital weight at about 24 hours falling within the NEWT trajectory consistent with eventual EWL. We defined cases as true EWL based on weight measured at home on day of life 4 (DoL4). Results: Of 280 original records, 60 were excluded (n = 27, NEWT-specific exclusion; n = 15, missing data; n = 18, >60 mL formula), resulting in 220 paired newborn weights measured in-hospital (17 ± 8 hours), and at DoL4 (84 ± 8 hours). NEWT status correctly identified 6/28 EWL cases (21% sensitivity [95% confidence interval, CI, 8-34%]), and 158/192 noncases (82% specificity [95% CI, 75-89%]). NEWT test-positive status was associated with greater weight loss, lower perceived breastfeeding support, and infant less often showing feeding cues on DoL4 (p < 0.05). Conclusion: Sensitivity in predicting EWL is low when applying NEWT at about 24 hours of life; however, early test-positive status is associated with indicators of breastfeeding difficulties on DoL4.

Evaluation of key miRNAs during early pregnancy in Kazakh horse using RNA sequencing

Background

miRNA has an important role in cell differentiation, biological development, and physiology. Milk production is an important quantitative trait in livestock and miRNA plays a role in the amount of milk produced.

Methods

The role of regulatory miRNAs involved in equine milk production is not fully understood. We constructed two miRNA libraries for Kazakh horse milk production from higher-producing (H group) and lower-producing (L group) individuals, and used RNA-Seq technology to identify the differentially expressed miRNAs between the two milk phenotypes of Kazakh horses.

Results

A total of 341 known and 333 novel miRNAs were detected from the H and L groups, respectively. Eighty-three differentially expressed miRNAs were identified between the H and L group s, of which 32 were known miRNAs (27 were up-regulated, five were down-regulated) and 51 were novel miRNAs (nine were up-regulated, 42 were down-regulated). A total of 2,415 genes were identified. The Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses showed that these genes were annotated to mammary gland development, mammary gland morphogenesis, tissue development and PI3K-Akt signaling pathways, insulin signaling pathway and TGF-beta signaling pathway, among others. Five miRNAs (miR-199a-3p, miR143, miR145, miR221, miR486-5p) were identified as affecting horse milk production and these five miRNAs were validated using qRT-PCR.

Conclusions

We described a methodology for the transcriptome-wide profiling of miRNAs in milk, which may help the design of new intervention strategies to improve the milk yield of Kazakh horses.