Breast milk mesenchymal stem cells abate cisplatin-induced cardiotoxicity in adult male albino rats via modulating the AMPK pathway

Myocardial injury influenced by cisplatin (Cis) is a compelling reason to hunt out a treatment modality to overcome such a threat in cisplatin-treated patients. Breast Milk mesenchymal stem cells (Br-MSCs) are a non-invasive, highly reproducible source of stem cells. Herein, we investigate Br-MSCs' role in cardiotoxicity induced by cisplatin. Rats were divided into; control, Cis-treated (received 12 mg/kg single intraperitoneal injection), BrMSCs-treated (received single intraperitoneal injection of 0.5 ml sterilized phosphate-buffered saline containing 2 × 107 cells of Br-MSCs); metformin-treated (received 250 mg/kg/day orally) and BrMSCs + metformin + Cis treated groups. At the experiment end, serum creatine kinase (CK-MB) and cardiac troponin T (cTnT) activates were estimated, cardiac malondialdehyde (MDA), superoxide dismutase (SOD), interleukin-1ß (IL-1ß), tumor necrosis factor-α (TNF-α) levels were measured, cardiac expression of Bax and Bcl-2 and AMP-activated protein kinase (AMPK), as well as heart histopathology, were evaluated. Study results showed that Cis explored acute cardiotoxicity evidenced by deteriorated cardiac indices, induction of oxidative stress, and inflammation with myocardium histological alterations. Treatment with Br-MSCs restored heart function and structure deteriorated by Cis injection. The antioxidant/anti-inflammatory/anti-apoptotic results of Br-MSCs were supported by AMPK activation denoting their protective role against cisplatin-induced cardiac injury. These results were superior when metformin was added to the treatment protocol.

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.

Resolving Human Lactation Heterogeneity Using Single Milk-Derived Cells, a Resource at the Ready

Single cell RNA sequencing (scRNAseq) of human milk-derived cells (HMDCs) makes highly detailed analyses of the biology of human lactation possible. We explore this powerful application as an exciting tool to inspect the cellular composition of human milk. We point out some important challenges unique to this approach and highlight the importance of collaborations between biologists and well-trained bioinformaticians to utilize these data to their maximum potential. We extend this focus by discussing the first two such studies that describe HMDCs via scRNAseq and a variety of important questions in the field that warrant attention through further research. The stage is set to apply scRNAseq in human lactation biology, potentially leading to new insights regarding the molecular and cellular diversity of human secretory mammary epithelial cells.

Single Cell RNA Sequencing of Human Milk-Derived Cells Reveals Sub-Populations of Mammary Epithelial Cells with Molecular Signatures of Progenitor and Mature States: a Novel, Non-invasive Framework for Investigating Human Lactation Physiology

Cells in human milk are an untapped source, as potential "liquid breast biopsies", of material for investigating lactation physiology in a non-invasive manner. We used single cell RNA sequencing (scRNA-seq) to identify milk-derived mammary epithelial cells (MECs) and their transcriptional signatures in women with diet-controlled gestational diabetes (GDM) with normal lactation. Methodology is described for coordinating milk collections with single cell capture and library preparation via cryopreservation, in addition to scRNA-seq data processing and analyses of MEC transcriptional signatures. We comprehensively characterized 3740 cells from milk samples from two mothers at two weeks postpartum. Most cells (>90%) were luminal MECs (luMECs) expressing lactalbumin alpha and casein beta and positive for keratin 8 and keratin 18. Few cells were keratin 14⁺ basal MECs and a small immune cell population was present (<10%). Analysis of differential gene expression among clusters identified six potentially distinct luMEC subpopulation signatures, suggesting the potential for subtle functional differences among luMECs, and included one cluster that was positive for both progenitor markers and mature milk transcripts. No expression of pluripotency markers POU class 5 homeobox 1 (POU5F1, encoding OCT4) SRY-box transcription factor 2 (SOX2) or nanog homeobox (NANOG), was observed. These observations were supported by flow cytometric analysis of MECs from mature milk samples from three women with diet-controlled GDM (2-8 mo postpartum), indicating a negligible basal/stem cell population (epithelial cell adhesion molecule (EPCAM)^-/integrin subunit alpha 6 (CD49f)⁺, 0.07%) and a small progenitor population (EPCAM⁺/CD49f⁺, 1.1%). We provide a computational framework for others and future studies, as well as report the first milk-derived cells to be analyzed by scRNA-seq. We discuss the clinical potential and current limitations of using milk-derived cells as material for characterizing human mammary physiology.

Morphological Analysis of Human Milk Membrane Enclosed Structures Reveals Diverse Cells and Cell-like Milk Fat Globules

Over the past decade, the cellular content of human milk has been a focus in lactation research due to the benefit a potential non-invasive stem cell compartment could provide either to the infant or for therapeutic applications. Despite an increase in the number of studies in this field, fundamental knowledge in regard to milk cell identification and characterisation is still lacking. In this project, we investigated the nature, morphology and content of membrane enclosed structures (MESs) and explored different methods to enrich human milk cells (HMCs) whilst reducing milk fat globule (MFG) content. Using both flow cytometry and immunofluorescence imaging, we confirmed previous reports and showed that nucleated HMCs make up a minority of milk-isolated MESs and are indistinguishable from MFGs without the use of a nuclear stain. HMC heterogeneity was demonstrated by differential uptake of nuclear stains Hoechst 33258 and DRAQ5™ using a novel technique of imaging milk MESs (by embedding them in agar), that enabled examination of both extracellular and intracellular markers. We found that MESs often contain multiple lipid droplets of various sizes and for the first time report that late post-partum human milk contains secretory luminal binucleated cells found across a number of participants. After investigation of different techniques, we found that viably freezing milk cells is an easy and effective method to substantially reduce MFG content of samples. Alternatively, milk MESs can be filtered using a MACS® filter and return a highly viable, though reduced population of milk cells. Using the techniques and findings we've developed in this study; future research may focus on further characterising HMCs and the functional secretory mammary epithelium during lactation.

Granulocytic Myeloid-Derived Suppressor Cells in Breast Milk (BM-MDSC) Correlate with Gestational Age and Postnatal Age and Are Influenced by Infant's Sex

BACKGROUND

Infections are the main cause of death in preterm infants. Causative agents often descend from the intestinal flora of the infected neonate, indicating insufficient protection by the mucosal barrier. Breast milk (BM) contains different subsets of immune cells. We recently showed that BM contains significant numbers of myeloid-derived suppressor cells (MDSC)-immune cells that actively suppress pro-inflammatory immune responses-and hypothesized that the transfer of BM-MDSC may modulate the mucosal immunity of the newborn.

METHODS

Percentages of MDSC in the BM from mothers of 86 preterm infants between 23 + 0 and 36 + 6 weeks of gestation during their first five postnatal weeks were analyzed by flow cytometry and correlated with maternal and infant characteristics.

RESULTS

Percentages of BM-MDSC positively correlated with gestational age and postnatal age. The expression of activation markers on BM-MDSC did not change with gestational age, but it decreased with postnatal age. Mothers who received antepartum tocolytics had lower percentages of BM-MDSC, and infant's sex strongly influenced percentages of BM-MDSC.

CONCLUSION

Our results point toward a role of BM-MDSC for immune regulation in the neonatal gut, making them a potential target of immune-based therapies shortly after birth.

Distribution of Free and Esterified Oxylipins in Cream, Cell, and Skim Fractions of Human Milk

Human milk contains oxylipins involved in infant development. Although oxylipins have been identified in whole or skim milk, their localization within human milk cream, cell, and skim fractions is not known. This study determined the distribution of free and esterified oxylipins in cream, cell, and skim fractions of human milk. Out of 72 oxylipins probed by mass-spectrometry, 42, 29, and 41 oxylipins (free or bound) were detected in cream, cell, and skim fractions, respectively. Over 90% of free and bound oxylipins were derived from linoleic acid in all milk fractions. Other oxylipins were derived from n-6 arachidonic acid and dihomo-gamma-linolenic acid, and n-3 alpha-linolenic acid, eicosapentaenoic acid, and docosahexaenoic acid. Free oxylipins were more abundant in skim milk (59.9% of total oxylipins) compared to cream and cell pellet, whereas esterified oxylipins were most abundant in milk cream and cell pellets (74.9-76.9%). The heterogenous distribution of oxylipins in different fractions of human milk may regulate the guided release of these bioactive signaling molecules within infants.

T Cells in Preterm Infants and the Influence of Milk Diet

Preterm infants born before 32 weeks gestational age (GA) have high rates of late onset sepsis (LOS) and necrotizing enterocolitis (NEC) despite recent improvements in infection control and nutrition. Breast milk has a clear protective effect against both these outcomes likely due to multiple mechanisms which are not fully understood but may involve effects on both the infant's immune system and the developing gut microbiota. Congregating at the interface between the mucosal barrier and the microbiota, innate and adaptive T lymphocytes (T cells) participate in this interaction but few studies have explored their development after preterm delivery. We conducted a literature review of T cell development that focuses on fetal development, postnatal maturation and the influence of milk diet. The majority of circulating T cells in the preterm infant display a naïve phenotype but are still able to initiate functional responses similar to those seen in term infants. T cells from preterm infants display a skew toward a T-helper 2(Th2) phenotype and have an increased population of regulatory cells (Tregs). There are significant gaps in knowledge in this area, particularly in regards to innate-like T cells, but work is emerging: transcriptomics and mass cytometry are currently being used to map out T cell development, whilst microbiomic approaches may help improve understanding of events at mucosal surfaces. A rapid rise in organoid models will allow robust exploration of host-microbe interactions and may support the development of interventions that modulate T-cell responses for improved infant health.

Human Breast Milk-Derived Extracellular Vesicles in the Protection Against Experimental Necrotizing Enterocolitis

PURPOSE

Necrotizing enterocolitis (NEC) is a leading cause of death in premature infants. Breast feeding decreases the incidence of NEC but, even with aggressive promotion of nursing in Neonatal Intensive Care Units, morbidity and mortality remain high. Previous studies from our laboratory have demonstrated that extracellular vesicles (EVs) purified from mouse and rat stem cells can protect the intestines from NEC. The aim of this study was to determine whether human breast milk (BM)-derived EVs could prevent NEC.

METHODS

EVs were purified from human donor breast milk. NEC was induced in premature rat pups by exposure to asphyxia/hypothermia/hypercaloric feeds. Pups were randomized to: (1) breast fed, no injury, (2) NEC, (3) NEC + BM-derived EVs once intraperitoneally (IP), (4) NEC + BM-derived EVs enterally (PO) with each feed. Intestinal tracts were examined for histologic damage. Additionally, the effect of BM-derived EVs on intestinal epithelial cells (IEC) subjected to hypoxia/reoxygenation injury in vitro was examined.

RESULTS

NEC incidence was 0% in breast-fed pups and 62% in pups subjected to NEC. IP administration of BM-derived EVs decreased NEC incidence to 29% and enteral administration further decreased NEC incidence to 11.9%. (p < 0.05). BM-derived EVs significantly increased cell proliferation and decreased apoptosis in IEC in vitro.

CONCLUSION

Breast milk-derived EVs delivered either IP or enterally significantly decrease the incidence and severity of experimental NEC, protect IEC from injury in vitro, and may represent an innovative therapeutic option for NEC in the future.

TYPE OF STUDY

Basic science study.

LEVEL OF EVIDENCE

N/A.

Human Milk MicroRNAs/Exosomes: Composition and Biological Effects

Human milk contains a wide variety of bioactive components, including long-chain fatty acids, complex oligosaccharides, and bioactive proteins. More recently, it was discovered that breast milk also contains exosomes, i.e., microvesicles containing microRNAs (miRNAs) with sizes of ∼22 nucleotides. Several of these miRNAs have been shown to originate from the mammary gland, and many of them are involved in cellular development and immune function. Exosome-mediated transfer of miRNAs is a novel mechanism of genetic exchange between cells. It is therefore possible that exosomes in milk may survive digestion and deliver miRNAs to intestinal cells, or, if transferred into the blood stream, to cells in other tissues. In vitro work has shown that exosomes and their miRNA cargo can survive proteolytic digestion and that intestinal epithelial cells take up the exosomes and deliver them to the nucleus. Research on human adults consuming cow milk has shown that major bovine milk miRNAs are found in the circulation postprandially, further suggesting that exosomes can resist conditions in the gastrointestinal tract and be delivered to the systemic circulation. Thus, it is possible that milk miRNAs may transfer genetic material to the infant and thereby affect gene transcription and regulation of cellular events in several tissues.

Associations of Maternal Weight Status Before, During, and After Pregnancy with Inflammatory Markers in Breast Milk

OBJECTIVE

The goal of this study was to examine the associations of maternal weight status before, during, and after pregnancy with breast milk C-reactive protein (CRP) and interleukin 6 (IL-6), two bioactive markers of inflammation, measured at 1 and 3 months post partum.

METHODS

Participants were 134 exclusively breastfeeding mother-infant dyads taking part in the Mothers and Infants Linked for Health (MILK) study, who provided breast milk samples. Pre-pregnancy body mass index (BMI) and gestational weight gain (GWG) were assessed by chart abstraction; postpartum weight loss was measured at the 1- and 3-month study visits. Linear regression was used to examine the associations of maternal weight status with repeated measures of breast milk CRP and IL-6 at 1 and 3 months, after adjustment for potential confounders.

RESULTS

Pre-pregnancy BMI and excessive GWG, but not total GWG or postpartum weight loss, were independently associated with breast milk CRP after adjustment (β = 0.49, P < 0.001 and β = 0.51, P = 0.011, respectively). No associations were observed for IL-6.

CONCLUSIONS

High pre-pregnancy BMI and excessive GWG are associated with elevated levels of breast milk CRP. The consequences of infants receiving varying concentrations of breast milk inflammatory markers are unknown; however, it is speculated that there are implications for the intergenerational transmission of disease risk.

Cellular Components, Including Stem-Like Cells, of Preterm Mother's Mature Milk as Compared with Those in Her Colostrum: A Pilot Study

PARTICIPATING AND STUDY OBJECTIVE

Whether the preterm mothers' mature milk retains the same cellular components as those in colostrum including stem-like cell, cell adhesion molecules, and immune cells.

PARTICIPANTS

A total of five preterm mothers were recruited for the study having an average age of 30.2 years and gestational age of 29.8 weeks from the Pristine Women's Hospital, Kolhapur. Colostrum milk was collected within 2-5 days and matured milk was collected 20-30 days after delivery from the same mothers.

METHODOLOGY

Integral cellular components of 22 markers including stem cells, immune cells, and cell adhesion molecules were measured using flowcytometry.

OUTCOME

Preterm mature milk was found to possess higher expressions of hematopoietic stem cells, mesenchymal stem-like cells, immune cells, few cell adhesion molecules, and side population cells than colostrum.

CONCLUSION

The increased level of these different cell components in mature milk may be important in the long-term preterm baby's health growth. Further similar research in a larger population of various gestational ages and lactation stages of preterm mothers is warranted to support these pilot findings.

Extracellular vesicles in blood, milk and body fluids of the female and male urogenital tract and with special regard to reproduction

Extracellular vesicles (EVs) are released from almost all cells and tissues. They are able to transport substances (e.g. proteins, RNA or DNA) at higher concentrations than in their environment and may adhere in a receptor-controlled manner to specific cells or tissues in order to release their content into the respective target structure. Blood contains high concentrations of EVs mainly derived from platelets, and, at a smaller amount, from erythrocytes. The female and male reproductive tracts produce EVs which may be associated with fertility or infertility and are released into body fluids and mucosas of the urogenital organs. In this review, the currently relevant detection methods are presented and critically compared. During pregnancy, placenta-derived EVs are dynamically detectable in peripheral blood with changing profiles depending upon progress of pregnancy and different pregnancy-associated pathologies, such as preeclampsia. EVs offer novel non-invasive diagnostic tools which may reflect the situation of the placenta and the foetus. EVs in urine have the potential of reflecting urogenital diseases including cancers of the neighbouring organs. Several methods for detection, quantification and phenotyping of EVs have been established, which include electron microscopy, flow cytometry, ELISA-like methods, Western blotting and analyses based on Brownian motion. This review article summarises the current knowledge about EVs in blood and cord blood, in the different compartments of the male and female reproductive tracts, in trophoblast cells from normal and pre-eclamptic pregnancies, in placenta ex vivo perfusate, in the amniotic fluid, and in breast milk, as well as their potential effects on natural killer cells as possible targets.

[Research advances in breastfeeding]

Human breast milk is the most natural and ideal food for the baby. Breastfeeding provides benefits for maternal and child health, child immune function, growth and development, and society. The operation of human milk bank and the use of donor human milk undoubtedly provides a new way of nutrition support for the preterm infants without their own mother's milk and a new kind of treatment for other diseases. Present research on the composition of breast milk focuses on the variety and quantity of proteins, bioactive substances, probiotics and cell population.Future research may focus on the bioactive substances, the mechanism of regulation and effect of cell population, the application of probiotics and the clinical application of donor human milk.

Human Milk Cells and Lipids Conserve Numerous Known and Novel miRNAs, Some of Which Are Differentially Expressed during Lactation

Human milk (HM) is rich in miRNAs, which are thought to contribute to infant protection and development. We used deep sequencing to profile miRNAs in the cell and lipid fractions of HM obtained post-feeding from 10 lactating women in months 2, 4, and 6 postpartum. In both HM fractions, 1,195 mature known miRNAs were identified, which were positively associated with the cell (p = 0.048) and lipid (p = 0.010) content of HM. An additional 5,167 novel miRNA species were predicted, of which 235 were high-confidence miRNAs. HM cells contained more known miRNAs than HM lipids (1,136 and 835 respectively, p<0.001). Although the profile of the novel miRNAs was very different between cells and lipids, with the majority conserved in the cell fraction and being mother-specific, 2/3 of the known miRNAs common between cells and lipids were similarly expressed (p>0.05). Great similarities between the two HM fractions were also found in the profile of the top 20 known miRNAs. These were largely similar also between the three lactation stages examined, as were the total miRNA concentration, and the number and expression of the known miRNAs common between cells and lipids (p>0.05). Yet, approximately a third of all known miRNAs were differentially expressed during the first 6 months of lactation (p<0.05), with more pronounced miRNA upregulation seen in month 4. These findings indicate that although the total miRNA concentration of HM cells and lipids provided to the infant does not change in first 6 months of lactation, the miRNA composition is altered, particularly in month 4 compared to months 2 and 6. This may reflect the remodeling of the gland in response to infant feeding patterns, which usually change after exclusive breastfeeding, suggesting adaptation to the infant’s needs.

IMMUNOPHENOTYPICAL CHARACTERISTICS OF CELLULAR COMPOSITION IN BREAST MILK

The morphology and immunophenotype of female colostrum adherent cells with the help of CD3, CD31, CD34, CD45, CD68, vimentin, and osteocalcin antibodies panel was studied in short-term (6—7 days) culture in vitro. Approximately equal (1 : 1) ratio of fibroblast-like and rounded cells was observed in 20 % of cultural flasks. The cells with regular shape mixed with single fibroblasts were noted in 80 % of cultural flasks. The diameter of spreaded cells varied within 10—100 mm. All cells adhered to plastics did not express CD3 and interacted slightly (sl) with antibodies to CD31, CD34, and CD45. At the same time, adherent cells with intensive CD68, vimentin and osteocalcin staining have been revealed. Literature data allows to interpret CD68+CD3–CD31slCD34slCD45sl immunophenotype of significant part of mother colostrum adherent cells as belonging to monocyte-macrophage lineage. Marked expression of stromal antigens (vimentin, osteocalcin) in 40—45 % adherent cells in cultural medium without osteogenic supplements (beta-glycerophosphate, ascorbic acid, dexamethasone) proposes an existence of osteoblasts fraction differentiated in colostrum from mesenchymal stem cells under an action of breast milk humoral factors.

Leukocyte Populations in Human Preterm and Term Breast Milk Identified by Multicolour Flow Cytometry

Background

Extremely preterm infants are highly susceptible to bacterial infections but breast milk provides some protection. It is unknown if leukocyte numbers and subsets in milk differ between term and preterm breast milk. This study serially characterised leukocyte populations in breast milk of mothers of preterm and term infants using multicolour flow cytometry methods for extended differential leukocyte counts in blood.

Methods

Sixty mothers of extremely preterm (<28 weeks gestational age), very preterm (28–31 wk), and moderately preterm (32–36 wk), as well as term (37–41 wk) infants were recruited. Colostrum (d2–5), transitional (d8–12) and mature milk (d26–30) samples were collected, cells isolated, and leukocyte subsets analysed using flow cytometry.

Results

The major CD45+ leukocyte populations circulating in blood were also detectable in breast milk but at different frequencies. Progression of lactation was associated with decreasing CD45+ leukocyte concentration, as well as increases in the relative frequencies of neutrophils and immature granulocytes, and decreases in the relative frequencies of eosinophils, myeloid and B cell precursors, and CD16- monocytes. No differences were observed between preterm and term breast milk in leukocyte concentration, though minor differences between preterm groups in some leukocyte frequencies were observed.

Conclusions

Flow cytometry is a useful tool to identify and quantify leukocyte subsets in breast milk. The stage of lactation is associated with major changes in milk leukocyte composition in this population. Fresh preterm breast milk is not deficient in leukocytes, but shorter gestation may be associated with minor differences in leukocyte subset frequencies in preterm compared to term breast milk.

Decreased memory B cells and increased CD8 memory T cells in blood of breastfed children: the generation R study

Background

Breastfeeding provides a protective effect against infectious diseases in infancy. Still, immunological evidence for enhanced adaptive immunity in breastfed children remains inconclusive.

Objective

To determine whether breastfeeding affects B- and T-cell memory in the first years of life.

Methods

We performed immunophenotypic analysis on blood samples within a population-based prospective cohort study. Participants included children at 6 months (n=258), 14 months (n=166), 25 months (n=112) and 6 years of age (n=332) with both data on breastfeeding and blood lymphocytes. Total B- and T-cell numbers and their memory subsets were determined with 6-color flow cytometry. Mothers completed questionnaires on breastfeeding when their children were aged 2, 6, and 12 months. Multiple linear regression models with adjustments for potential confounders were performed.

Results

Per month continuation of breastfeeding, a 3% (95% CI -6, -1) decrease in CD27+IgM+, a 2% (95 CI % -5, -1) decrease in CD27+IgA+ and a 2% (95% CI -4, -1) decrease in CD27-IgG+ memory B cell numbers were observed at 6 months of age. CD8 T-cell numbers at 6 months of age were 20% (95% CI 3, 37) higher in breastfed than in non-breastfed infants. This was mainly found for central memory CD8 T cells and associated with exposure to breast milk, rather than duration. The same trend was observed at 14 months, but associations disappeared at older ages.

Conclusions

Longer breastfeeding is associated with increased CD8 T-cell memory, but not B-cell memory numbers in the first 6 months of life. This transient skewing towards T cell memory might contribute to the protective effect against infectious diseases in infancy.

Transcriptional implications of intragenic DNA methylation in the oestrogen receptor alpha gene in breast cancer cells and tissues

BACKGROUND

DNA methylation variability regions (MVRs) across the oestrogen receptor alpha (ESR1) gene have been identified in peripheral blood cells from breast cancer patients and healthy individuals. In contrast to promoter methylation, gene body methylation may be important in maintaining active transcription. This study aimed to assess MVRs in ESR1 in breast cancer cell lines, tumour biopsies and exfoliated epithelial cells from expressed breast milk (EBM), to determine their significance for ESR1 transcription.

METHODS

DNA methylation levels in eight MVRs across ESR1 were assessed by pyrosequencing bisulphite-converted DNA from three oestrogen receptor (ER)-positive and three ER-negative breast cancer cell lines. DNA methylation and expression were assessed following treatment with DAC (1 μM), or DMSO (controls). ESR1 methylation levels were also assayed in DNA from 155 invasive ductal carcinoma biopsies provided by the Breast Cancer Campaign Tissue Bank, and validated with DNA methylation profiles from the TCGA breast tumours (n = 356 ER-pos, n = 109 ER-neg). DNA methylation was profiled in exfoliated breast epithelial cells from EBM using the Illumina 450 K (n = 36) and pyrosequencing in a further 53 donor samples. ESR1 mRNA levels were measured by qRT-PCR.

RESULTS

We show that ER-positive cell lines had unmethylated ESR1 promoter regions and highly methylated intragenic regions (median, 80.45%) while ER-negative cells had methylated promoters and lower intragenic methylation levels (median, 38.62%). DAC treatment increased ESR1 expression in ER-negative cells, but significantly reduced methylation and expression of ESR1 in ER-positive cells. The ESR1 promoter was unmethylated in breast tumour biopsies with high levels of intragenic methylation, independent of ER status. However, ESR1 methylation in the strongly ER-positive EBM DNA samples were very similar to ER-positive tumour cell lines.

CONCLUSION

DAC treatment inhibited ESR1 transcription in cells with an unmethylated ESR1 promoter and reduced intragenic DNA methylation. Intragenic methylation levels correlated with ESR1 expression in homogenous cell populations (cell lines and exfoliated primary breast epithelial cells), but not in heterogeneous tumour biopsies, highlighting the significant differences between the in vivo tumour microenvironment and individual homogenous cell types. These findings emphasise the need for care when choosing material for epigenetic research and highlights the presence of aberrant intragenic methylation levels in tumour tissue.

Breastmilk is a novel source of stem cells with multilineage differentiation potential

The mammary gland undergoes significant remodeling during pregnancy and lactation, which is fuelled by controlled mammary stem cell (MaSC) proliferation. The scarcity of human lactating breast tissue specimens and the low numbers and quiescent state of MaSCs in the resting breast have hindered understanding of both normal MaSC dynamics and the molecular determinants that drive their aberrant self-renewal in breast cancer. Here, we demonstrate that human breastmilk contains stem cells (hBSCs) with multilineage properties. Breastmilk cells from different donors displayed variable expression of pluripotency genes normally found in human embryonic stem cells (hESCs). These genes included the transcription factors (TFs) OCT4, SOX2, NANOG, known to constitute the core self-renewal circuitry of hESCs. When cultured in the presence of mouse embryonic feeder fibroblasts, a population of hBSCs exhibited an encapsulated ESC-like colony morphology and phenotype and could be passaged in secondary and tertiary clonogenic cultures. While self-renewal TFs were found silenced in the normal resting epithelium, they were dramatically upregulated in breastmilk cells cultured in 3D spheroid conditions. Furthermore, hBSCs differentiated in vitro into cell lineages from all three germ layers. These findings provide evidence that breastmilk represents a novel and noninvasive source of patient-specific stem cells with multilineage potential and establish a method for expansion of these cells in culture. They also highlight the potential of these cells to be used as novel models to understand adult stem cell plasticity and breast cancer, with potential use in bioengineering and tissue regeneration.

Incidence and correlates of HIV-1 RNA detection in the breast milk of women receiving HAART for the prevention of HIV-1 transmission

BACKGROUND

The incidence and correlates of breast milk HIV-1 RNA detection were determined in intensively sampled women receiving highly active antiretroviral therapy (HAART) for the prevention of mother-to-child HIV-1 transmission.

METHODS

Women initiated HAART at 34 weeks of pregnancy. Breast milk was collected every 2-5 days during 1 month postpartum for measurements of cell-associated HIV DNA and cell-free HIV RNA. Plasma and breast milk were also collected at 2 weeks, 1, 3 and 6 months for concurrent HIV-1 RNA and DNA measurements. Regression was used to identify cofactors for breast milk HIV-1 RNA detection.

RESULTS

Of 259 breast milk specimens from 25 women receiving HAART, 34 had detectable HIV-1 RNA (13%, incidence 1.4 episodes/100 person-days 95% CI = 0.97-1.9). Fourteen of 25 (56%) women had detectable breast milk HIV-1 RNA [mean 2.5 log(10) copies/ml (range 2.0-3.9)] at least once. HIV-1 DNA was consistently detected in breast milk cells despite HAART, and increased slowly over time, at a rate of approximately 1 copy/10(6) cells per day (p = 0.02). Baseline CD4, plasma viral load, HAART duration, and frequency of breast problems were similar in women with and without detectable breast milk HIV-1 RNA. Women with detectable breast milk HIV-1 RNA were more likely to be primiparous than women without (36% vs 0%, p = 0.05). Plasma HIV-1 RNA detection (OR = 9.0, 95%CI = 1.8-44) and plasma HIV-1 RNA levels (OR = 12, 95% CI = 2.5-56) were strongly associated with concurrent detection of breast milk HIV-1 RNA. However, no association was found between breast milk HIV-1 DNA level and concurrent breast milk HIV-1 RNA detection (OR = 0.96, 95%CI = 0.54-1.7).

CONCLUSIONS

The majority of women on HAART had episodic detection of breast milk HIV-1 RNA. Breast milk HIV-1 RNA detection was associated with systemic viral burden rather than breast milk HIV-1 DNA.

Human milk fortifiers in very low birth weight infants

The use of HMF remains an important option and has become common practice in all neonatal intensive care units. However, optimal composition of fortifiers is still undefined and more data are needed on safety and long-term benefits. Further research should be directed toward comparisons between different proprietary preparations, evaluating both short-term and long-term outcomes and adverse effects, in search of the best method of fortification.

Throughput expression of multiple G-protein coupled receptors for HIV infection in choriocarcinoma cells, trophoblasts, and breast milk cells

The chemokine receptors, which belong to G-protein coupled receptors (GPCRs) and become co-receptors when HIV enters the cell, have been mentioned in recent research. Numerous studies have reported that the cellular mechanism of HIV crossing the placental barrier is still not totally understood. This study was conducted to investigate whether the mRNAs of nineteen typs of GPCRs and CD4 were expressed in choriocarcinoma cell lines, trophoblasts, and breast milk cells by using RT-PCR. It was found that the expression of GPCRs varied in different cell lines. Of note is that CD4 could not be expressed in either choriocarcinoma cells or trophoblasts. It was noteworthy that mRNAs of multiple GPCRs were identified in choriocarcinoma cells, trophoblasts, and breast milk cells for the first time. The expression amounts of these mRNAs were further measured by quantitative RT-PCR. Interestingly, mRNAs of CCR9/CCR10 were strongly expressed in trophoblasts. This study provided further insights to the cellular mechanism of mother-to-child transmission of HIV.

Expression of M-Ficolin in human monocytes and macrophages

M-Ficolin is a member of the ficolin family of proteins, which is expressed by monocytes. We have determined the expression of this gene in various populations of this lineage in man and found lower levels of M-Ficolin mRNA in the more mature CD14(+)CD16(+) monocytes as compared to the classical CD14(++) monocytes. Monocyte-derived macrophages generated by in vitro culture for 5 days strongly reduced M-Ficolin mRNA and protein. Mature tissue macrophages from the lung and from breast milk also showed a very low level of M-Ficolin transcripts. When cells of the monocytic cell line Mono Mac 6 cell were treated with TLR2 and TLR4 ligands for 24 h then there was an average of 6- and 9-fold induction of the M-Ficolin mRNA, respectively. After 72 h induction was in average 30- and 80-fold for TLR2 and TLR4 stimulation, respectively. Treatment of monocyte-derived macrophages for 3 days with TLR4 ligand gave an average 4-fold induction and alveolar macrophages treated with TLR4 ligand showed a 12-fold induction. These data show that M-Ficolin expression is silenced in macrophages but can be re-activated after prolonged activation via TLRs.

The bioactive nature of human breastmilk

Human breastmilk is widely accepted to be the optimal source for nutrition for the newborn infant, containing all the proteins, lipids, carbohydrates, micronutrients and trace elements required for growth, development and immune protection. In addition human breastmilk plays a significant role in the prevention of medical conditions such as childhood cancers, obesity and gastrointestinal diseases. The importance of breastmilk and its superiority as a source of infant nutrition is highlighted in the recent overhaul of teh World Health Organization growth charts that are now based on exclusively breastfed infants. Human breastmilk also contains a population of cells, the importance of which is often not considered when the bioactivity of breastmilk is discussed.

Exosomes with immune modulatory features are present in human breast milk

Breast milk is a complex liquid with immune-competent cells and soluble proteins that provide immunity to the infant and affect the maturation of the infant's immune system. Exosomes are nanovesicles (30-100 nm) with an endosome-derived limiting membrane secreted by a diverse range of cell types. Because exosomes carry immunorelevant structures, they are suggested to participate in directing the immune response. We hypothesized that human breast milk contain exosomes, which may be important for the development of the infant's immune system. We isolated vesicles from the human colostrum and mature breast milk by ultracentrifugations and/or immuno-isolation on paramagnetic beads. We found that the vesicles displayed a typical exosome-like size and morphology as analyzed by electron microscopy. Furthermore, they floated at a density between 1.10 and 1.18 g/ml in a sucrose gradient, corresponding to the known density of exosomes. In addition, MHC classes I and II, CD63, CD81, and CD86 were detected on the vesicles by flow cytometry. Western blot and mass spectrometry further confirmed the presence of several exosome-associated molecules. Functional analysis revealed that the vesicle preparation inhibited anti-CD3-induced IL-2 and IFN-gamma production from allogeneic and autologous PBMC. In addition, an increased number of Foxp3(+)CD4(+)CD25(+) T regulatory cells were observed in PBMC incubated with milk vesicle preparations. We conclude that human breast milk contains exosomes with the capacity to influence immune responses.

Immunomodulatory constituents of human milk change in response to infant bronchiolitis

Although epidemiological evidence is generally supportive of a causal association between respiratory syncytial virus (RSV) bronchiolitis during infancy and the development of persistent wheeze/asthma, if not allergy, the mechanism by which this occurs and an explanation for why all children do not succumb remains to be elucidated. Breast feeding has been found to confer a protective effect against respiratory infections such as RSV bronchiolitis and allergy; however, again there is little direct evidence and no clear mechanism. In this study, we examined whether human milk immunomodulatory factors (cells, cytokines) change in response to clinically diagnosed, severe bronchiolitis in the recipient breast-fed infant. We examined milk from 36 breast feeding mothers of infants hospitalized with bronchiolitis and compared them with milk from 63 mothers of postpartum age-matched healthy controls. Milks from mothers of infants hospitalized with bronchiolitis had significantly greater numbers of viable cells when compared with the milks obtained from mothers of healthy infants (1.3 +/- 0.4 vs. 0.3 +/- 0.03 x 10(6) cells/ml, mean +/- s.e.m.; p < or = 0.001). Further, the cells obtained from the mothers of infants hospitalized with bronchiolitis were found to produce a skewed cytokine profile ex vivo in response to stimulation by live RSV but not when cultured with a non-specific mitogen (concanavalin A). This study provides preliminary evidence for an immunological link between mothers and their breast-fed infants during severe respiratory infections as well as a possible contributing factor to the development of persistent wheeze in these infants.

Veterinary field test as screening tool for mastitis and HIV-1 viral load in breastmilk from HIV-infected Zambian women

Clinical and subclinical mastitis increase the risk of mother-to-child transmission (MTCT) of HIV-1 through breastfeeding. We hypothesized that a field test for mastitis used for bovine milk, the California Mastitis Test, would detect high cell counts in milk of HIV-infected women. We also investigated whether total milk cell count would positively correlate with viral HIV-1 RNA in the milk of 128 HIV-positive Zambian women. Mean cell counts in each California Mastitis Test scoring category were significantly different (p < 0.01, n = 232). In a subset of 4-month postpartum milk samples tested for HIV-1 RNA, viral RNA levels did not significantly correlate with total cell count (r = 0.166, p = .244). The CMT may serve as a screening tool for mastitis in breastmilk, but total cell count does not correlate with HIV-1 RNA levels. Since both cell-free and cell-associated virus are associated with increased risk of MTCT, investigation of the relationship between total milk cell count and HIV-1 proviral DNA is warranted before a conclusive determination is made regarding use of the CMT as a clinical screening tool to detect cases at high risk for breastmilk transmission.

Viability of infectious viral particles of HIV and BMCs in breast milk

BACKGROUND

Infectious factors in breast milk such as viral particles and living infected cells are of prime importance in the transmission of HIV by breastfeeding.

OBJECTIVES

To perform effective approaches for reducing HIV transmission via breastfeeding, we investigated the biological importance of infectious viral particles and infected BMCs in breast milk.

STUDY DESIGN

Alteration of viral infectivity was monitored using a modified experimental infection assay that exploited the cytotoxicity of breast milk, and BMC viability was evaluated by flow-cytometric analysis.

RESULTS

Infectious viral particles were found to decrease time-dependently after contact with breast milk, whereas BMCs showed prolonged survival in breast milk.

CONCLUSIONS

The biological importance of infected BMCs in breast milk for the transmission of HIV via breastfeeding was considered.

Identification of nestin-positive putative mammary stem cells in human breastmilk

Stem cells in mammary tissue have been well characterised by using the mammary stem cell marker, cytokeratin (CK) 5 and the mature epithelial markers CK14, CK18 and CK19. As these markers have never been reported in cells from breastmilk, the aim of this study has been to determine whether mammary stem cells are present in expressed human breastmilk. Cultured cells from human breastmilk were studied by using immunofluorescent labelling and reverse transcription/polymerase chain reaction (RT-PCR). We found a heterogeneous population of cells with differential expression of CK5, CK14, CK18 and CK19. Further, by using the multipotent stem cell marker, nestin, we identified cells in culture that were positive only for nestin or double-positive for CK5/nestin, whereas no co-staining was observed for CK14, CK18 and CK19 with nestin. When cells isolated from breastmilk were analysed by using RT-PCR prior to culture, only nestin and CK18 were detected, thereby indicating that breastmilk contained differentiated epithelial and putative stem cells. Furthermore, fluorescence-activated cell-sorting analysis demonstrated, in breastmilk, a small side-population of cells that excluded Hoechst 33342 (a key property of multipotent stem cells). When stained for nestin, the cells in the side-population were positive, whereas those not in the side-population were negative. The presence of nestin-positive putative mammary stem cells suggests that human breastmilk is a readily available and non-invasive source of putative mammary stem cells that may be useful for research into both mammary gland biology and more general stem cell biology.

Breast milk CD4+ T cells express high levels of C chemokine receptor 5 and CXC chemokine receptor 4 and are preserved in HIV-infected mothers receiving highly active antiretroviral therapy

BACKGROUND

Transmission of human immunodeficiency virus (HIV) to the infant through breast-feeding is a major problem worldwide; however, the biological circumstances of such transmission remain unclear. Little characterization of breast milk CD4(+) T lymphocytes has been done so far.

METHODS

We performed a detailed immunophenotypic analysis of T lymphocytes in the breast milk, compared with the blood, of HIV-uninfected (n=9) and HIV-infected (n=10) women receiving highly active antiretroviral therapy, by use of multiparameter flow cytometry. Descriptive statistics and nonparametric comparisons were performed using SAS software (version 9.1; SAS Institute).

RESULTS

In uninfected women, 44%-78% of breast milk CD4(+) T cells expressed the C chemokine receptor 5 (CCR5), whereas 26%-73% of cells coexpressed CCR5 and CXC chemokine receptor 4 (CXCR4). In contrast, only 7%-20% of peripheral blood CD4(+) T cells expressed CCR5 and 1%-20% coexpressed CCR5 and CXCR4. The level of CCR5 expression in CD4(+) T cells in breast milk was higher than in blood. In HIV-infected women, the high frequency of CD4(+)CCR5(+) T cells in breast milk was preserved.

CONCLUSIONS

A majority of CD4(+) T cells in breast milk express high levels of CCR5 and CXCR4. Unlike other mucosal immune sites, in which CD4(+)CCR5(+) T cells are rapidly eliminated by HIV, these cells are preserved in breast milk during HIV infection.

Quality control of banked milk in Brasilia, Brazil

The authors studied quality control procedures at human milk banks and nutritional profiles of 909 milk samples (from 195 donors, aged 15 to 45 years) from banked human milk (BHM) in Brasília, Brazil. Number of donations per donor ranged from 1 to > 10 that consisted mostly of mature milk (90.9%) with a mean total energy of 529 +/- 85 kcal/L and a mean total lipid of 22.7 g/L +/- 13.2. Microbiological quality (titrable acidity-Dornic, degrees D) was suitable for infant feeding in 99.2% of samples (< 8 degrees D), ranging from 2 degrees D to 8 degrees D (mean 4.8 +/- 1.4 degrees D). Most BHM (98.1%) samples were dispensed to inpatient infants (1-7 days) diagnosed with respiratory distress (30.1%), prematurity (20.7%), metabolic distress (16.0%), jaundice (14.4%), bacterial infection (6.0%), pneumonia (3.3%), congenital cardiac distress (2.2%), or other conditions (6.2%). Well-motivated mothers and trained staff are serving and sustaining an important life-saving network with long-lasting impact on public health.

Transmission of cell-free and cell-associated HIV-1 through breast-feeding

BACKGROUND

Transmission through breast-feeding is an important cause of infant HIV-1 infections in developing countries; however, its mechanism remains largely unknown. We have explored the association between cell-free virus (CFV) and cell-associated virus (CAV) levels in breast milk (BM), as reflected by viral RNA and proviral DNA, respectively, and the risk of infant HIV-1 infection after 6 weeks postpartum.

METHODS

Sixty-one HIV-positive mothers who transmitted HIV-1 by BM were matched to 61 HIV-positive nontransmitting mothers based on their infant's age at sample collection. CFV and CAV were quantified in a single milk specimen per mother preceding the infant's first HIV-positive result.

RESULTS

After adjusting for maternal CD4 cell counts and disease stage, each 10-fold increase in CFV or CAV load was associated with an almost 3-fold increase in BM transmission. Whereas CAV load was predictive of transmission before and after 9 months postpartum, CFV was a significant predictor of transmission occurring only after 9 months. Phylogenetic analyses of the C2 to C5 env region showed that 85% of infants (11 of 13 infants) harboring viruses that clustered with CFV in their mother's milk were infected after 9 months postpartum.

CONCLUSION

A reduction in milk CAV and CFV loads might significantly decrease HIV-1 transmission by breast-feeding.

Genetic analysis of human milk by fluorescence in situ hybridization

Ductal lavage is a technique for early breast cancer detection in high-risk women. During this procedure, exfoliated epithelial cells are flushed out of the milk ducts of nonlactating women and the collected cells are analyzed for cellular changes associated with breast cancer. A recently developed protocol uses interphase fluorescence in situ hybridization (I-FISH) to detect specific chromosomal aneusomies known to be associated with breast cancer. The ability to perform I-FISH on breast milk will prove to be valuable to lactating women who are at high risk for breast cancer or who develop symptoms while breastfeeding. Using established protocols for analyzing peripheral blood lymphocytes, amniocytes, and epithelial cells in urine and breast duct lavage samples as a guide, a protocol for I-FISH of human breast milk has been developed. Cell isolation, fixation, pretreatment, denaturation, hybridization, and washings were optimized to produce slides of high quality, sensitivity, and specificity.

What caused the epidemic of Pneumocystis pneumonia in European premature infants in the mid-20th century?

An epidemic of interstitial pneumonia principally involving premature infants occurred in Germany and nearby European countries between the 1920s and 1960s. Fatalities were due to Pneumocystis. Because the principal defenses against Pneumocystis are T cells, an acquired T-cell deficiency was postulated. A number of potential causes including malnutrition were considered. All were implausible except for a retrovirus that was benign in adults but virulent in premature infants. Furthermore, we suspect that the virus was imported into Germany from former German African colonies. Premature infants were vulnerable because of the developmental status of their T cells. Given the practices in that part of Europe at that time, the virus was most likely transmitted by contaminated blood transfusions and subsequent contamination of reusable needles and syringes used in injections. Although the epidemic ended 4 decades ago, a search for the postulated retrovirus can be conducted if tissues from affected infants are available.

Breast Milk-Derived Antigen-Specific CD8+ T Cells: An Extralymphoid Effector Memory Cell Population in Humans

Although mouse studies have demonstrated the presence of an effector memory population in nonlymphoid tissues, the phenotype of human CD8(+) T cells present in such compartments has not been characterized. Because of the relatively large number of CD8(+) T cells present in breast milk, we were able to characterize the phenotype of this cell population in HIV-infected and uninfected lactating women. CMV, influenza virus, EBV, and HIV-specific CD8(+) T cells as measured by the IFN-gamma ELISPOT and MHC class I tetramer staining were all present at greater frequencies in breast milk as compared with blood. Furthermore, a greater percentage of the breast milk CD8(+) T cells expressed the intestinal homing receptor, CD103, and the mucosal homing receptor CCR9. Breast milk T cells were predominantly CD45RO(+)HLADR(+) and expressed low levels of CD45RA, CD62L, and CCR7 consistent with an effector memory population. Conversely, T cells derived from blood were mainly characterized as central memory cells (CCR7(+)CD62L(+)). These results demonstrate a population of extralymphoid CD8(+) T cells with an effector memory phenotype in humans, which could contribute to enhanced local virologic control and the relative lack of HIV transmission via this route.

Transmission of macrophage-tropic HIV-1 by breast-milk macrophages via DC-SIGN

Recent findings suggest that macrophage-tropic human immunodeficiency virus type 1 (HIV-1) produced in colostrum/early breast milk may hold a clue to determine the mechanisms of transmission of HIV-1 via breast-feeding. Here, we show that the majority of CD4(+) cells in the colostrum are CD14(+) macrophages expressing both chemokine receptors and DC-SIGN, a dendritic cell-specific receptor for HIV-1. The R5-type macrophage-tropic HIV-1 isolate NL(AD8) infected such breast-milk macrophages and caused them to secrete virus particles efficiently; however, the secreted virions showed only a weak transmissibility to their susceptible target, MAGIC-5 cells. When stimulated with interleukin-4, the breast-milk macrophages demonstrated a striking enhancement of expression of DC-SIGN and showed a strong capacity to transmit NL(AD8) virions to MAGIC-5 cells, which was specifically blocked by anti-DC-SIGN-specific antibody. These results suggest that HIV-1 virions captured by DC-SIGN, but not secreted cell-free virions, may be more efficiently transmitted to other compartments, such as the gastrointestinal tract, through acidic gastric juice.

Microarray analysis of human milk cells: persistent high expression of osteopontin during the lactation period

To continue the search for immunological roles of breast milk, cDNA microarray analysis on cytokines and growth factors was performed for human milk cells. Among the 240 cytokine-related genes, osteopontin (OPN) gene ranked top of the expression. Real-time PCR revealed that the OPN mRNA levels in colostrum cells were approximately 100 times higher than those in PHA-stimulated peripheral blood mononuclear cells (PBMNCs), and 10 000 times higher than those in PB CD14(+) cells. The median levels of OPN mRNA in early milk or mature milk cells were more than three times higher than those in colostrum cells. Western blot analysis of human milk showed appreciable expression of full-length and short form proteins of OPN. The concentrations of full-length OPN in early milk or mature milk whey continued to be higher than those in colostrum whey and plasma as assessed by ELISA. The early milk (3-7 days postpartum) contained the highest concentrations of OPN protein, while the late mature milk cells (1 years postpartum) had the highest expression of OPN mRNA of all the lactating periods. The results of immunohistochemical and immunocytochemical staining indicated that OPN-producing epithelial cells and macrophages are found in actively lactating mammary glands. These results suggest that the persistently and extraordinarily high expression of OPN in human milk cells plays a potential role in the immunological development of breast-fed infants.

Association of levels of HIV-1-infected breast milk cells and risk of mother-to-child transmission

Understanding how the level of human immunodeficiency virus type 1 (HIV-1)-infected breast milk cells (BMCs) affects HIV transmission via breast-feeding can shed light on the mechanism of infection and aid in establishing effective interventions. The proportion of infected cells to total cells was measured in serial breast milk samples collected from 291 HIV-1-infected women in Nairobi, Kenya, by use of real-time DNA polymerase chain reaction amplification of BMCs. The number of infected BMCs per million cells was associated with levels of cell-free viral RNA in breast milk (R=.144; P=.032), levels of cell-free virus in blood plasma (R=.365; P<.001), and the detection of proviral DNA in cervical and vaginal secretions (P<.001 and P = .030, respectively). The number of infected BMCs per million cells was lower in colostrum or early milk than in mature milk (P<.001). Previous studies demonstrated that the concentration of BMCs varies throughout lactation, and we used these data to transform infected BMCs per million cells to infected BMCs per milliliter. The estimated concentration of infected BMCs per milliliter was higher in colostrum or early milk than in mature milk (P<.001). Each log10 increase in infected BMCs per milliliter was associated with a 3.19-fold-increased risk of transmission (P=.002), after adjustment for cell-free virus in plasma (hazard ratio [HR], 2.09; P=.03) and breast milk (HR, 1.01; P=1.00). This suggests that infected BMCs may play a more important role in transmission of HIV via breast-feeding than does cell-free virus.

Osteoprotegerin in human milk: a potential role in the regulation of bone metabolism and immune development

Osteoprotegerin (OPG) is a member of the tumor necrosis factor superfamily. It is a soluble "decoy" receptor for tumor necrosis factor-related apoptosis-inducing ligand and ligand of the receptor activator of NF-kappaB. As such, OPG inhibits osteoclast activity and regulates the immune system. Human milk is a complex biologic fluid that supplies nutritional and protective factors to the breast-fed infant. In the present study, human milk samples at various times postpartum were assessed for the presence of OPG. Using biochemical as well as immunologic and biologic techniques we showed that human milk contains OPG at a level that is 1000-fold higher than that found in normal human serum. We observed that human breast milk cells and the human mammary epithelial cell line MCF-7 express OPG, indicating that both cell types are possible sources of milk OPG in vivo. In vitro studies demonstrated that milk OPG is biologically active and suggested that it may contribute to the antiresorptive activity of milk on bone, as well as tumor necrosis factor-related apoptosis-inducing ligand-induced inhibition of T cell proliferation. OPG-like activity was also observed in bovine colostrum and milk. Furthermore, we were able to detect human OPG in the sera of rats gavaged with human milk. We discuss the relevance of our findings for the breast-fed infant and for the prevention of immune and bone disorders.

Eosinophil cationic protein in human milk is associated with development of cow's milk allergy and atopic eczema in breast-fed infants

The precise role of leukocytes and mediators in human milk is still unresolved. Eosinophils are uncommonly detected in human milk and their presence has previously been associated with maternal atopy and development of cow's milk allergy (CMA) in the breast-fed infant. The purpose of this study was to examine the levels of eosinophil cationic protein (ECP) in human milk and to compare the levels with development of allergic diseases in breast-fed infants. Altogether 94 breast-feeding mothers (58 atopic, 36 nonatopic) with their babies were prospectively followed from birth for development of CMA or atopic dermatitis. Colostrum and mature milk samples (at 3 mo of lactation), together with mother's peripheral blood samples, were collected. Milk and blood leukocyte content was evaluated with a light microscope. ECP concentration in human milk was measured by commercial UniCAP method. By the end of a 2-y follow-up, 51 mothers had an infant with CMA, 24 had an infant with atopic dermatitis, and 19 had a healthy infant. ECP concentration in milk was under the detection limit (2 microg/L) in all the mothers with a healthy infant, whereas detectable levels were found in 27% of mothers with a CMA infant and in 42% of those with a baby with atopic dermatitis. Measurable ECP in milk was detected in 26% of the atopic and 25% of the nonatopic mothers. Presence of ECP in human milk is associated with development of CMA and atopic dermatitis in the breast-fed infant, but has no direct association with the maternal atopy.

Human immunodeficiency virus type 1 RNA in breast-milk components

We conducted the present study to determine which of the 4 components of breast milk (whole milk, skim milk, lipid layer, and breast-milk cells) had the highest sensitivity and concentration of human immunodeficiency virus (HIV) type 1 RNA burden and to determine biological correlates to these factors. The probability of detection of HIV (sensitivity) and the concentration of HIV-1 RNA were both associated with the choice of milk component, CD4(+) cell count, concentration of blood serum HIV-1 RNA, and the presence of breast inflammation. Whole milk demonstrated higher sensitivity and mean concentration than any other single component. Sensitivity was enhanced by analyzing all 4 components of breast milk.

Cytokine production by human milk cells and peripheral blood mononuclear cells from the same mothers

Samples of milk (n = 80) and venous blood were collected at 5 weeks postpartum from 82 lactating mothers. Human milk cells and peripheral blood mononuclear cells were isolated and the production of interleukin-1beta, interleukin-6, and tumor necrosis factor-a in the absence and presence of lipopolysaccharide was determined by enzyme-linked immunosorbent assay. Human milk cells spontaneously produced significantly less interleukin-1beta, interleukin-6, and tumor necrosis factor-alpha than peripheral blood mononuclear cells in the absence of stimulation. In vitro stimulation of human milk cells with lipopolysaccharide (500 ng/ml) for 24 hr increased cytokine production by approximately 40-50%, whereas peripheral blood mononuclear cells responded to lipopolysaccharide (200 ng/ml) with increased cytokine production of up to 350%. These observations suggest that cells in milk are capable of active involvement in the production of the interleukin-1beta, interleukin-6, and tumor necrosis factor-a in the mammary gland and have the capacity to respond to further stimulation after leaving the breast.