Introduction: tight junctions and secretory activation in the mammary gland

Biomarker-based text messages to promote lactation success in mothers of critically Ill infants: a randomized controlled pilot study

OBJECTIVE

Infrequent breast pumping limits mother's own milk production in mothers of infants admitted to the neonatal intensive care unit. We aimed to determine the feasibility and benefit of biomarker-based personalized text messages on pumping frequency and milk sodium levels. A secondary aim examined lactation outcomes.

STUDY DESIGN

In this randomized controlled pilot study, 51 mothers were randomized to receive personalized text messages regarding pumping frequency or standard care.

RESULTS

There were no differences in pumped milk volume or sodium level, however, there was a trend towards the intervention group pumping more frequently, which was significant on day 5 (p = 0.035), and they lactated nearly 9 days longer. Post-hoc analysis found the intervention group tended to be more likely to pump ≥ 500 mL by day14 (p = 0.08), a marker of long-term lactation success.

CONCLUSION

Personalized biomarker-based text messages are feasible and may support lactation in mothers of critically ill infants.

The Utilization of Sodium Concentration in Human Milk from Pump-Dependent Mothers of Preterm Infants as a Measure of Milk Production

Objective: This study investigated changes in sodium concentrations in human milk from mothers of premature infants using different breast pumps for 14 days postpartum, and the correlation between the sodium concentration in mother's own milk (MOM) and the volume pumped. Study Design: This randomized controlled study recruited 66 mothers of premature infants delivered in our hospital from February to December 2018, and we assigned them to three groups using an envelope method. In intervention group 1, a hospital-grade electric breast pump was used from postpartum day 1 to 14; in intervention group 2, a hospital-grade electric breast pump was used on postpartum days 1 to 5 and a normal personal electric breast pump on postpartum days 6 to 14; in the control group, a personal normal electric breast pump was used from postpartum day 1 to 14. Data recorded included the breast milk volume pumped and milk sodium concentration. Results: The average daily volume of MOM pumped differed statistically (p < 0.05) between the intervention and control groups at postpartum days 7 and 14. The average daily volume pumped did not differ between intervention groups 1 and 2 by postpartum day 14 (p > 0.05). However, the time taken for the sodium concentrations to normalize differed significantly (p < 0.01). At postpartum day 5, the sodium concentrations of 73% of intervention group 1 and 2 mothers were within normal limits, and they were maintained until day 14. In comparison, only 41% of the controls had normal MOM sodium levels on day 5, and they were still high on day 7 in 27.3% of controls. Conclusions: In the early stage of lactation initiation (within 5 days postpartum), using a hospital-grade electric breast pump promotes lactation in mothers who deliver prematurely and the sodium concentrations normalize more quickly. Sodium can be used as an objective biomarker of MOM to evaluate the possibility of delayed lactation in mothers of premature infants, and it could assist interventions in the early postpartum period. Trial Registration: Chinese Clinical Trial Registry, ChiCTR2200061384.

Effects of Galohgor Nutraceutical Lactation Cookies on Breast Milk Volume and Lactose Concentration

Background

Galohgor nutraceutical lactation cookies (NLC) contain polyherbal which is believed and consumed by postpartum mothers of Sundanese Ethnic in Indonesia to increase breast milk production. This study was aimed to analyze the effects of NLC cookies on breast milk volume and lactose concentrations of postpartum mothers.

Methods

The experimental study with post-controlled design was conducted. Twenty eligible mother-infant pairs were enrolled and divided into two groups. They were randomly assigned to receive NLC (n=9) or original cookies (ORC, n=11). Each subjects consumed 4 pieces/d of NLC which containing 1 g galohgor nutraceutical powder/ pieces or ORC (without galohgor nutraceutical powder), for 14 days intervention period since the first day of giving birth. The measurement of breast milk production was carried out by baby weighing method using SECA 334 digital baby scale (SECA, Hamburg, Germany). A high-performance liquid chromatography method was used to determine lactose concentrations in breast milk. Data were analyzed by parametric Independent T-test or the nonparametric Mann-Whitney U-test and adjusted analysis of covariance.

Results

NLC significantly increased (P<0.05) breast milk production, as shown by average breast milk volume of NLC compared to ORC, i.e., 557.0 (95% confidence interval [CI], 497.3–616.6) mL/d vs. 435.9 (95% CI, 382.3–489.6) mL/d. This result was supported by lactose concentration in breast milk of mothers who consumed NLC significantly higher (P<0.05), compared to ORC, i.e., 6.03% (95% CI, 5.66%–6.40%) vs. 5.18% (95% CI, 4.85%–5.51%).

Conclusion

NLC which containing galohgor nutraceutical can be recommended to increase breast milk volume and lactose concentration in the early postpartum period.

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.

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.

Relationship between Selected Trace Elements in Human Milk and Psychosocial Characteristics in Korean Early Postpartum Women

This study aimed to identify the relationship between selected trace elements in human milk and depression, breastfeeding self-efficacy, sleep satisfaction, and the demographic and obstetric characteristics of lactating mothers. Forty lactating mothers recovering after birth in two postpartum care centers located in Changwon, South Korea, were studied. Calcium, sodium, iron, and selenium concentrations in human milk were analyzed using inductively coupled plasma mass spectrometry at the analysis center of Kyungnam University. Data were analyzed using descriptive statistics, the Kruskal-Wallis test, the Mann-Whiney U test, and Spearman's correlation coefficients using an SPSS 23.0 program. There were no significant differences in concentration of selected trace elements (calcium, sodium, iron, and selenium) in human milk according to demographic and obstetric characteristics. Sodium concentration was negatively correlated with breastfeeding self-efficacy (r = -0.51, CI = -0.71 to -0.24). Selenium concentration was negatively correlated with calcium concentration (r = -0.34, CI = -0.58 to 0.38). Postpartum depression was negatively correlated with sleep satisfaction (r = -0.46, CI = -0.67 to -0.17) and with breastfeeding self-efficacy (r = -0.41, CI = -0.64 to -0.11). Breastfeeding self-efficacy was positively correlated with sleep satisfaction (r = 0.48, CI = 0.20 to 0.69). This study suggests that sodium concentration in human milk is associated with breastfeeding self-efficacy.

Strategies to increase the use of mother's own milk for infants at risk of necrotizing enterocolitis

High-dose mother's own milk (MOM) feedings during the first 14 days post birth reduce the risk of necrotizing enterocolitis in very low birthweight (VLBW; <1500 g birthweight). However, high-dose MOM feedings are only possible if mothers provide sufficient quantities of MOM in a timely manner, and data indicate that the lack of MOM during the early post-birth period is a global problem. This paper reviews the modifiable and unmodifiable barriers to accessing adequate quantities of MOM during the early post-birth period and proposes evidence-based strategies to increase and improve the use of MOM during the neonatal intensive care unit (NICU) hospitalization with an emphasis on the critical first 2 weeks post birth.

Strategies for the Preservation, Restoration and Modulation of the Human Milk Microbiota. Implications for Human Milk Banks and Neonatal Intensive Care Units

Studies carried in the last years have revealed that human milk contains a site-specific microbiota and constitutes a source of potentially beneficial bacteria to the infant gut. Once in the infant gut, these bacteria contribute to the assembly of a physiological gut microbiota and may play several functions, contributing to infant metabolism, protection against infections, immunomodulation or neuromodulation. Many preterm neonates are fed with pasteurized donor's human milk (DHM) or formula and, therefore, are devoid of contact with human milk microbes. As a consequence, new strategies are required to allow the exposition of a higher number of preterm infants to the human milk microbiota early in life. The first strategy would be to promote and to increase the use of own mother's milk (OMM) in Neonatal Intensive Care Units (NICUs). Even small quantities of OMM can be very valuable since they would be added to DHM in order to microbiologically "customize" it. When OMM is not available, a better screening of donor women, including routine cytomegalovirus (CMV) screening of milk, may help to avoid the pasteurization of the milk provided by, at least, a relevant proportion of donors. Finally, when pasteurized DHM or formula are the only feeding option, their supplementation with probiotic bacteria isolated from human milk, such as lactic acid bacteria or bifidobacteria, may be an alternative to try to restore a human milk-like microbiota before feeding the babies. In the future, the design of human milk bacterial consortia (minimal human milk microbiotas), including well characterized strains representative of a healthy human milk microbiota, may be an attractive strategy to provide a complex mix of strains specifically tailored to this target population.

Human Milk Biomarkers of Secretory Activation in Breast Pump-Dependent Mothers of Premature Infants

OBJECTIVE

Mothers of premature infants confront barriers to coming to volume (CTV; ≥500 mL/day mother's own milk [MOM] by postpartum day 14), a strong predictor of continued MOM provision at neonatal intensive care unit (NICU) discharge. We sought to determine concentrations of secretory activation biomarkers (MOM sodium, total protein, lactose, and citrate) during the first 14 postpartum days and to describe relationships among these biomarkers, pumped MOM volume, CTV, and pumping frequency.

STUDY DESIGN

This descriptive observational study collected serial MOM samples, pumped MOM volume, and pumping frequency during the first 14 postpartum days in 16 breast pump-dependent mothers who delivered <33 weeks gestation. Daily biomarker concentrations were compared to published normal values for mothers of term infants. Relationships among biomarkers, pumped MOM volume, and pumping frequency were determined.

RESULTS

On postpartum day 5, only 40% of MOM samples revealed normal concentrations of all four biomarkers, and normalcy was not maintained throughout the first 14 days. All eight mothers (50%) who achieved CTV had normal concentrations for four biomarkers at 5.4 ± 3.5 days postpartum and had more cumulative pumping sessions by day 5 (p = 0.03). A dose-response relationship between number of normal biomarkers and pumped MOM volume was demonstrated for postpartum days 3 (p = 0.01) and 5 (p = 0.04).

CONCLUSION

Secretory activation is delayed in mothers who deliver prematurely and is closely tied to CTV, MOM volume, and pumping frequency. MOM biomarkers hold promise as objective research outcome measures and for point-of-care testing to identify and proactively manage mothers at risk for compromised lactation.

MicroRNA roles in signalling during lactation: an insight from differential expression, time course and pathway analyses of deep sequence data

The study examined microRNA (miRNA) expression and regulatory patterns during an entire bovine lactation cycle. Total RNA from milk fat samples collected at the lactogenesis (LAC, day1 [D1] and D7), galactopoiesis (GAL, D30, D70, D130, D170 and D230) and involution (INV, D290 and when milk production dropped to 5 kg/day) stages from 9 cows was used for miRNA sequencing. A total of 475 known and 238 novel miRNAs were identified. Fifteen abundantly expressed miRNAs across lactation stages play regulatory roles in basic metabolic, cellular and immunological functions. About 344, 366 and 209 miRNAs were significantly differentially expressed (DE) between GAL and LAC, INV and GAL, and INV and LAC stages, respectively. MiR-29b/miR-363 and miR-874/miR-6254 are important mediators for transition signals from LAC to GAL and from GAL to INV, respectively. Moreover, 58 miRNAs were dynamically DE in all lactation stages and 19 miRNAs were significantly time-dependently DE throughout lactation. Relevant signalling pathways for transition between lactation stages are involved in apoptosis (PTEN and SAPK/JNK), intracellular signalling (protein kinase A, TGF-β and ERK5), cell cycle regulation (STAT3), cytokines, hormones and growth factors (prolactin, growth hormone and glucocorticoid receptor). Overall, our data suggest diverse, temporal and physiological signal-dependent regulatory and mediator functions for miRNAs during lactation.

Evidence-Based Methods That Promote Human Milk Feeding of Preterm Infants: An Expert Review

Best practices translating the evidence for high-dose human milk (HM) feeding for preterm infants during neonatal intensive care unit (NICU) hospitalization have been described, but their implementation has been compromised. Although the rates of any HM feeding have increased over the last decade, efforts to help mothers maintain HM provision through to NICU discharge have remained problematic. Special emphasis should be placed on prioritizing the early lactation period of coming to volume so that mothers have sufficient HM volume to achieve their personal HM feeding goals. Donor HM does not provide the same risk reduction as own mother's HM.

Essential Role for Zinc Transporter 2 (ZnT2)-mediated Zinc Transport in Mammary Gland Development and Function during Lactation

The zinc transporter ZnT2 (SLC30A2) imports zinc into vesicles in secreting mammary epithelial cells (MECs) and is critical for zinc efflux into milk during lactation. Recent studies show that ZnT2 also imports zinc into mitochondria and is expressed in the non-lactating mammary gland and non-secreting MECs, highlighting the importance of ZnT2 in general mammary gland biology. In this study we used nulliparous and lactating ZnT2-null mice and characterized the consequences on mammary gland development, function during lactation, and milk composition. We found that ZnT2 was primarily expressed in MECs and to a limited extent in macrophages in the nulliparous mammary gland and loss of ZnT2 impaired mammary expansion during development. Secondly, we found that lactating ZnT2-null mice had substantial defects in mammary gland architecture and MEC function during secretion, including fewer, condensed and disorganized alveoli, impaired Stat5 activation, and unpolarized MECs. Loss of ZnT2 led to reduced milk volume and milk containing less protein, fat, and lactose compared with wild-type littermates, implicating ZnT2 in the regulation of mammary differentiation and optimal milk production during lactation. Together, these results demonstrate that ZnT2-mediated zinc transport is critical for mammary gland function, suggesting that defects in ZnT2 not only reduce milk zinc concentration but may compromise breast health and increase the risk for lactation insufficiency in lactating women.

[Development and evaluation of breastfeeding promotion program for mothers with breast engorgement following cesarean birth]

PURPOSE

This study was to develop a breastfeeding promotion program and to test effects of the program on levels of breast discomfort, breast size, sodium in breast milk, and type of feeding in mothers with breast engorgement following cesarean birth.

METHODS

A non-synchronized non-equivalent control group pretest-posttest design was used in this study. The participants were 70 postpartum mothers who were admitted to a postpartum care center and experienced breast engorgement following cesarean birth. The planned nursing intervention was the breastfeeding promotion program consisting of breast massage and 1:1 breastfeeding education, counseling, and support focusing on individualized problem solving provided for 10 days. Fifty-three women completed the program (experimental group 26, control group, 27). Measurements were level of breast discomfort, breast size, sodium in breast milk and type of feeding at pre and posttest.

RESULTS

Women who participated in the program experienced lower scores for breast discomfort, greater decrease in breast size, lower levels of sodium in breast milk, and practiced breastfeeding more than those in the control group.

CONCLUSION

Results indicate that this breastfeeding promotion program is effective in reducing breast engorgement and improving breastfeeding practices, and is therefore recommended to enhance breastfeeding promotion practice in postpartum care centers.

An integrated genomics approach to identify genetic regions associated with neonatal growth trait in mice

Neonatal growth during the early post-partum period is closely associated with lactation performance. Neonatal growth reflects milk output and is a complex variable trait among inbred mouse strains, but few studies have compared this trait systematically across more than a few strains. In the present study, 11 inbred strains of mice were measured for a neonatal growth phenotype during the first eight days of lactation. Significant differences in neonatal growth trait were observed with QSi5 (3.71±0.05 g) and DBA/1J (2.67±0.06 g) strains defining the two extremes of the phenotype. In silico association analysis was performed for trait variability using the high density SNP information on inbred strains of mice. We found strong evidence to refine a previously identified large neonatal growth QTL on mouse chromosome 9, Neogq1. When an integrated strategy that combined fine mapping and analysis of mammary transcriptome expression profiles of lactating mice with divergent phenotypes was applied, we identified neogenin (Neo1), a gene important for mammary gland morphogenesis, as a likely quantitative trait gene (QTG) underlying the Neogq1 QTL in mice.

Gene regulation of UDP-galactose synthesis and transport: potential rate-limiting processes in initiation of milk production in humans

Lactose synthesis is believed to be rate limiting for milk production. However, understanding the molecular events controlling lactose synthesis in humans is still rudimentary. We have utilized our established model of the RNA isolated from breast milk fat globule from seven healthy, exclusively breastfeeding women from 6 h to 42 days following delivery to determine the temporal coordination of changes in gene expression in the carbohydrate metabolic processes emphasizing the lactose synthesis pathway in human mammary epithelial cell. We showed that milk lactose concentrations increased from 75 to 200 mM from 6 to 96 h. Milk progesterone concentrations fell by 65% at 24 h and were undetectable by day 3. Milk prolactin peaked at 36 h and then declined progressively afterward. In concordance with lactose synthesis, gene expression of galactose kinase 2, UDP-glucose pyrophosphorylase 2 (UGP2), and phosphoglucomutase 1 increased 18-, 10-, and threefold, respectively, between 6 and 72 h. Between 6 and 96 h, gene expression of UDP-galactose transporter 2 (SLC35A2) increased threefold, whereas glucose transporter 1 was unchanged. Gene expression of lactose synthase no. 3 increased 1.7-fold by 96 h, whereas α-lactalbumin did not change over the entire study duration. Gene expression of prolactin receptor (PRLR) and its downstream signal transducer and activator of transcription complex 5 (STAT5) were increased 10- and 2.5-fold, respectively, by 72 h. In summary, lactose synthesis paralleled the induction of gene expression of proteins involved in UDP-galactose synthesis and transport, suggesting that they are potentially rate limiting in lactose synthesis and thus milk production. Progesterone withdrawal may be the signal that triggers PRLR signaling via STAT5, which may in turn induce UGP2 and SLC35A2 expression.

A major prolactin-binding complex on human milk fat globule membranes contains cyclophilins A and B: the complex is not the prolactin receptor

Prolactin (PRL) in milk influences maturation of gastrointestinal epithelium and development of both the hypothalamo-pituitary and immune systems of offspring. Here, we demonstrate that most PRL in human milk is part of a novel, high-affinity, multicomponent binding complex found on the milk fat globule membrane and not in whey. To examine properties of the complex, a sensitive ELISA was developed such that human PRL (hPRL) binding to the complex was measured by loss of hPRL detectability; thus, as much as 50 ng of hPRL was undetectable in the presence of 10 μl of human milk. Using the same methodology, no comparable complex formation was observed with human serum or amniotic fluid. hPRL complexation in milk was rapid, time dependent, and cooperative. Antibodies to or competitors of the hPRL receptor (placental lactogen and growth hormone) showed the hPRL receptor was not involved in the complex. However, hPRL complexation was antagonized by cyclosporine A and anti-cyclophilins. The complex was very stable, resisting dissociation in SDS, urea, and dithiothreitol. Western analysis revealed an ∼75-kDa complex that included hPRL, cyclophilins A and B, and a 16-kDa cyclophilin A. Compared with noncomplexed hPRL, complexed hPRL in whole milk showed similar activation of STAT5 but markedly delayed activation of ERK. Alteration of signaling suggests that complex formation may alter hPRL biological activity. This is the first report of a unique, multicomponent, high-capacity milk fat reservoir of hPRL; all other analyses of milk PRL have utilized defatted milk.

Mammary gland ECM remodeling, stiffness, and mechanosignaling in normal development and tumor progression

Cells of the mammary gland are in intimate contact with other cells and with the extracellular matrix (ECM), both of which provide not only a biochemical context, but a mechanical context as well. Cell-mediated contraction allows cells to sense the stiffness of their microenvironment, and respond with appropriate mechanosignaling events that regulate gene expression and differentiation. ECM composition and organization are tightly regulated throughout development of the mammary gland, resulting in corresponding regulation of the mechanical environment and proper tissue architecture. Mechanical regulation is also at play during breast carcinoma progression, as changes in ECM deposition, composition, and organization accompany breast carcinoma. These changes result in stiffer matrices that activate mechanosignaling pathways and thereby induce cell proliferation, facilitate local tumor cell invasion, and promote progression. Thus, understanding the role of forces in the mammary gland is crucial to understanding both normal developmental and pathological processes.