Temporal trends in the inflammatory cytokine profile of human breastmilk

Association between maternal stress and premature milk cortisol, milk IgA, and infant health: a cohort study

Background

Maternal stress is pervasive in the neonatal intensive care unit (NICU). Maternal stress is associated with changes in human milk (HM) immunomodulatory agents, which may impact neonatal health. We sought to determine the association between maternal stress, HM immunoglobulin A (IgA) and cortisol, and to assess how these milk components correlate with infant immune and neurodevelopmental outcomes. We then compared how these associations persist over time.

Methods

The study design involved a cohort study of exclusively breastfeeding mothers and their singleton moderately preterm (28-34 weeks) infants admitted to the NICU. We collected maternal serum, maternal saliva, and first-morning whole milk samples, and administered maternal stress questionnaires at 1 and 5 weeks postpartum. We analyzed the samples for HM IgA (using a customized immunoassay in skim milk) and for HM and salivary cortisol (using a chemiluminescent immunoassay). Infant illness was assessed using the Score for Neonatal Acute Physiology II (SNAP II) and SNAP II with Perinatal Extension (SNAPPE II), and infant neurodevelopment were assessed using the Test of Infant Motor Performance. We analyzed changes in HM IgA and cortisol over time using paired t-tests. Furthermore, we performed correlation and regression analyses after adjusting for gestational age (GA), corrected GA, and infant days of life.

Results

In our study, we enrolled 26 dyads, with a mean maternal age of 28.1 years, consisting of 69% white, 19% Black, and 8% Hispanic. Cortisol: Salivary and HM cortisol were closely associated in week 1 but not in week 5. Though mean salivary cortisol remained stable over time [2.41 ng/mL (SD 2.43) to 2.32 (SD 1.77), p = 0.17], mean HM cortisol increased [1.96 ng/mL (SD 1.93) to 5.93 ng/mL (SD 3.83), p < 0.001]. Stress measures were inversely associated with HM cortisol at week 1 but not at week 5. IgA: HM IgA decreased over time (mean = -0.14 mg/mL, SD 0.53, p < 0.0001). High maternal stress, as measured by the Parental Stressor Scale: neonatal intensive care unit (PSS:NICU), was positively associated with HM IgA at week 5 (r = 0.79, P ≤ 0.001). Higher IgA was associated with a lower (better) SNAP II score at week 1 (r = -0.74, p = 0.05). No associations were found between maternal stress, salivary cortisol, HM cortisol, or HM IgA and neurodevelopment at discharge (as assessed using the TIMP score). Furthermore, these relationships did not differ by infant sex.

Conclusion

Maternal stress showed associations with HM cortisol and HM IgA. In turn, HM IgA was associated with lower measures of infant illness.

Inflammatory Markers in Mother's Own Milk and Infant Stool of Very Low Birthweight Infants

BACKGROUND

Mother's breastmilk is the gold standard for feeding preterm infants. Preterm delivery may be precipitated by inflammatory maternal states, but little is known about milk cytokine profiles and how they correlate with markers of infant gut inflammation (i.e., stool calprotectin) in this vulnerable population.

RESEARCH AIM

To assess cytokines and inflammatory markers in milk from parents of very preterm infants over time as well as correlations between milk and infant's stool calprotectin.

METHOD

This is a secondary analysis of milk samples collected during OptiMoM, a triple-blind randomized clinical trial of infants born < 1250 g (NCT02137473). Longitudinally collected samples were analyzed for cytokines, choline, and inflammatory markers (C-reactive protein [CRP], IFN-γ, IL-10, IL-1β, IL-1ra, IL-6, IL-8, TNF-α). Infant stools were collected for longitudinal calprotectin analysis. Generalized estimating equations quantified longitudinal profiles of milk markers and stool calprotectin, their associations, and the correlation between free choline and C-reactive protein over follow-up.

RESULT

Participants included 92 parents and infants (median weeks of gestation 27.3, median birth weight 845 g, and prevalence of male infants 45%). In all, 212 milk samples and 94 corresponding stool calprotectin levels were collected 1-11 weeks postpartum. C-reactive protein was present in much higher concentrations than other markers, and was highest in Week 1 postpartum. It decreased over time. IL-8 and free choline also changed over time while other markers did not. There was no correlation between any milk markers and stool calprotectin.

CONCLUSION

Milk from mothers of very preterm infants has detectable inflammatory markers, some of which change over time. Research is needed to determine if infant outcomes are associated with these markers.

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.

Influenza Vaccine Associated with the Gene Expression of T Cell Surface Markers in Human Milk

Background: The function of neonatal T cells is reduced compared to adult T cells. T cells could be transferred to the infants through human milk and compensate for their immature T cells. As the subsets of T cells present in human milk have been incompletely described, this study investigated the association between the maternal factors (influenza vaccine, maternal age, and lactation time), the gene expression of T cell surface markers (cluster of differentiation [CD] and chemokine receptors [CCR]), and the concentrations of T cell-related cytokines in human milk. Materials and Methods: The gene expressions of T cell markers and the concentrations of T cell-related cytokines were determined in milk samples from 16 women. Eight donors received influenza vaccine, and eight were not vaccinated during 2019-2020 for the flu season 2020. Results: For T cell surface markers, the gene expression of CD8A was higher than CD4, CCR6, CD25, CXCR5, CD62L, and CD44 in human milk. CD44 copy gene was lower than CCR7 and CXCR3, while CD4 copy gene was lower than CXCR3 in human milk. Women with influenza vaccine had higher copy genes of CD44, CD8A, CD62L, and CD25 and lower CCR7 copy gene in milk than in women without influenza vaccine. Interleukin-17 concentration in human milk decreased with increasing lactation time. Gene expression of T cell markers and cytokine concentrations varied between lactating women. Conclusions: Although a larger study is needed, it appears that the influenza vaccine is associated with the gene expression of T cell markers in human milk.

Increased Colostral Concentration of Macrophage Migration Inhibitory Factor in Mothers with Premature Rupture of Membranes

Objective: The colostrum contains macrophage migration inhibitory factor (MIF), which plays an important role in protecting newborns from infections. As such, colostrum may be specifically important to prevent early onset neonatal sepsis among neonates born after premature rupture of membranes (PROM). However, the effect of PROM on the colostral MIF concentration has not been previously described. The aim of this study is to compare the concentration of MIF in the colostrum of mothers with and without PROM. Methods: The study group consisted of 44 women, 22 of whom had PROM. Colostrum was expressed and collected within 72 hours of birth. MIF concentration was measured using the enzyme-linked immunosorbent assay method and compared between mothers with and without PROM. Results: There were no differences between the two groups (PROM group n = 22, control group n = 22) with regard to the age of mothers, mode of delivery, neonatal gestational age, birth weight, and sex of the infants (p > 0.05). The colostral MIF concentration was significantly higher among mothers with than without PROM (p = 0.0001). There was a positive and significant correlation between the colostral MIF concentration and PROM duration (r = 0.314, p = 0.038). Conclusions: PROM was associated with a higher colostral MIF concentration, with this concentration being positively correlated with the duration of PROM. This increased concentration may be important in offering these neonates additional protection against early onset infections, which is a risk associated with PROM.

Ontogeny of plasma cytokine and chemokine concentrations across the first week of human life

Introduction/background & aims:

Early life is marked by distinct and rapidly evolving immunity and increased susceptibility to infection. The vulnerability of the newborn reflects development of a complex immune system in the face of rapidly changing demands during the transition to extra-uterine life. Cytokines and chemokines contribute to this dynamic immune signaling network and can be altered by many factors, such as infection. Newborns undergo dynamic changes important to health and disease, yet there is limited information regarding human neonatal plasma cytokine and chemokine concentrations over the first week of life. The few available studies are limited by small sample size, cross-sectional study design, or focus on perturbed host states like severe infection or prematurity. To characterize immune ontogeny among healthy full-term newborns, we assessed plasma cytokine and chemokine concentrations across the first week of life in a robust longitudinal cohort of healthy, full-term African newborns.

Methods:

We analyzed a subgroup of a cohort of healthy newborns at the Medical Research Council Unit in The Gambia (West Africa; N = 608). Peripheral blood plasma was collected from all study participants at birth (day of life (DOL) 0) and at one follow-up time point at DOL 1, 3, or 7. Plasma cytokine and chemokine concentrations were measured by bead-based cytokine multiplex assay. Unsupervised clustering was used to identify patterns in plasma cytokine and chemokine ontogeny during early life.

Results:

We observed an increase across the first week of life in plasma Th1 cytokines such as IFNγ and CXCL10 and a decrease in Th2 and anti-inflammatory cytokines such as IL-6 and IL-10, and chemokines such as CXCL8. In contrast, other cytokines and chemokines (e.g. IL-4 and CCL5, respectively) remained unchanged during the first week of life. This robust ontogenetic pattern did not appear to be affected by gestational age or sex.

Conclusions:

Ontogeny is a strong driver of newborn plasma-based levels of cytokines and chemokines throughout the first week of life with a rising IFNγ axis suggesting post-natal upregulation of host defense pathways. Our study will prove useful to the design and interpretation of future studies aimed at understanding the neonatal immune system during health and disease.

Associations between Physiological Biomarkers and Psychosocial Measures of Pregnancy-Specific Anxiety and Depression with Support Intervention

Stress and anxiety significantly impact the hypothalamic–pituitary axis, and in pregnancy, the subsequent maternal–fetal response can lead to poor outcomes. The objective of this study was to assess the association between psychosocial measures of pregnancy-specific anxiety and physiologic inflammatory responses. Specifically, to determine the effectiveness of the Mentors Offering Maternal Support (M-O-M-S^TM) program to reduce psychosocial anxiety and associated inflammatory response. In conjunction with measures of pregnancy-specific anxiety and depression, serum biomarkers (IL-2, IL-6, IL-10, IL1-B, TNF-α, CRH, CRP, and cortisol) were analyzed for each trimester throughout pregnancy. Results demonstrated that women receiving the M-O-M-S^TM intervention had longitudinally sustained lower TNF-α/IL-10 ratios than the control group, and it was significantly associated with psychosocial measures of anxiety, specifically for fears of labor and spouse/partner relationships. Additionally, the anxiety of spouse/partner relationships was significantly associated with IL-6/IL-10 ratios. The findings highlight the important counter-regulatory relationship between anti- and pro-inflammatory cytokines and provide insight into the distinct physiologic responses to pregnancy-specific anxiety with early prenatal intervention.

Immediate Pre-Partum SARS-CoV-2 Status and Immune Profiling of Breastmilk: A Case-Control Study

Objetive

To address the prevalence of SARS-CoV-2 and the evolutionary profile of immune compounds in breastmilk of positive mothers according to time and disease state.

Methods

Forty-five women with term pregnancies with confirmed non-severe SARS-CoV-2 infection (case group), and 96 SARS-CoV-2 negative women in identical conditions (control group) were approached, using consecutive sample. Weekly (1st to 5th week postpartum) reverse transcription polymerase chain reaction (RT-PCR) in nasopharyngeal swabs (cases) and breastmilk (cases and controls) were obtained. Concentration of cytokines, chemokines, and growth factors in breastmilk (cases and controls) were determined at 1st and 5th week post-partum.

Results

Thirty-seven (study group) and 45 (control group) women were enrolled. Symptomatic infection occurred in 56.8% of women in the study group (48% fever, 48% anosmia, 43% cough). SARS-CoV-2 RNA was not found in breastmilk samples. Concentrations of cytokines (IFN-γ, IL-1ra, IL-4, IL-6, IL-9, IL-13, and TNF-α) chemokines (eotaxin, IP-10, MIP-1α, and RANTES) and growth factors (FGF, GM-CSF, IL7, and PDGF-BB) were higher in breastmilk of the study compared with the control group at 1st week postpartum. Immune compounds concentrations decreased on time, particularly in the control group milk samples. Time of nasopharyngeal swab to become negative influenced the immune compound concentration pattern. Severity of disease (symptomatic or asymptomatic infection) did not affect the immunological profile in breast milk.

Conclusions

This study confirms no viral RNA and a distinct immunological profile in breastmilk according to mother’s SARS-CoV-2 status. Additional studies should address whether these findings indicate efficient reaction against SARS-CoV-2 infection, which might be suitable to protect the recipient child.

Probiotic Supplementation and Human Milk Cytokine Profiles in Japanese Women: A Retrospective Study from an Open-Label Pilot Study

The benefits of probiotic supplementation to lactating mothers on human milk cytokines are inconclusive. Thus, we performed a comprehensive open-label pilot trial analysis of 27 human milk cytokines in lactating women with allergies (one to three months postpartum) to determine the effect of supplementation with a mixture of new probiotic strains. Participants voluntarily joined the probiotic (n = 41) or no supplementation control (n = 19) groups. The probiotic group took three probiotic tablets (Lactobacillus casei LC5, Bifidobacterium longum BG7, and Bacillus coagulans SANK70258) daily for one to three months postpartum. Milk samples were collected at one, two, and three months postpartum, and cytokine levels were measured using multiplex assays. The effects were analyzed using multivariate regression models. Eleven cytokines showed a positive rate of over 50% in the milk samples throughout testing in both groups. The positive rates of IL-1 receptor antagonist and IL-7 changed significantly with lactation progression in logistic regression models after adjusting for time and supplementation, whereas rates of other cytokines showed no significant differences. The lactational change patterns of IL-10 concentrations differed significantly between the two groups. A short-term supplementation of probiotics affects human milk cytokine levels in lactating women with a possible placebo effect still existing. Future placebo-controlled studies are needed to support these results, based on the estimated sample sizes in this study.

Best Practices for Human Milk Collection for COVID-19 Research

In addition to providing life-giving nutrients and other substances to the breastfed infant, human milk can also represent a vehicle of pathogen transfer. As such, when an infectious disease outbreak, epidemic, or pandemic occurs-particularly when it is associated with a novel pathogen-the question will naturally arise as to whether the pathogen can be transmitted through breastfeeding. Until high-quality data are generated to answer this question, abandonment of breastfeeding due to uncertainty can result. The COVID-19 pandemic, which was in full swing at the time this document was written, is an excellent example of this scenario. During these times of uncertainty, it is critical for investigators conducting research to assess the possible transmission of pathogens through milk, whether by transfer through the mammary gland or contamination from respiratory droplets, skin, breast pumps, and milk containers, and/or close contact between mother and infant. To promote the most rigorous science, it is critical to outline optimal methods for milk collection, handling, storage, and analysis in these situations, and investigators should openly share their methods in published materials. Otherwise, the risks of inconsistent test results from preanalytical and analytical variation, false positives, and false negatives are unacceptably high and the ability to provide public health guidance poor. In this study, we provide "best practices" for collecting human milk samples for COVID-19 research with the intention that this will also be a useful guide for future pandemics.

Immune Responses and Risk of Triple-negative Breast Cancer: Implications for Higher Rates among African American Women

The etiology of triple-negative breast cancers (TNBC) is poorly understood. As many TNBCs develop prior to the initiation of breast cancer screening or at younger ages when the sensitivity of mammography is comparatively low, understanding the etiology of TNBCs is critical for discovering novel prevention approaches for these tumors. Furthermore, the higher incidence rate of estrogen receptor-negative breast cancers, and specifically, of TNBCs, among young African American women (AAW) versus white women is a source of racial disparities in breast cancer mortality. Whereas immune responses to TNBCs have received considerable attention in relation to prognosis and treatment, the concept that dysregulated immune responses may predispose to the development of TNBCs has received limited attention. We present evidence that dysregulated immune responses are critical in the pathogenesis of TNBCs, based on the molecular biology of the cancers and the mechanisms proposed to mediate TNBC risk factors. Furthermore, proposed risk factors for TNBC, especially childbearing without breastfeeding, high parity, and obesity, are more prevalent among AAW than white women. Limited data suggest genetic differences in immune responses by race, which favor a stronger Thr type 2 (Th2) immune response among AAW than white women. Th2 responses contribute to wound-healing processes, which are implicated in the pathogenesis of TNBCs. Accordingly, we review data on the link between immune responses and TNBC risk and consider whether the prevalence of risk factors that result in dysregulated immunity is higher among AAW than white women.

Timing of milk expression following delivery in mothers delivering preterm very low birth weight infants: a randomized trial

OBJECTIVE

To determine the effect of timing of expression initiation on mother's own milk production and time to secretory activation in mothers of preterm infants.

STUDY DESIGN

180 mothers delivering infants ≤1500 grams and ≤32 weeks gestation were randomized to begin expression within 60 (early), 61-180 (intermediate) or 181-360 (late) minutes following delivery. Milk volume was measured on days 1-7 and weekly for 6 weeks. Time to secretory activation was determined through self-report.

RESULTS

The late group produced more milk than the early group in the first 3 days (p = 0.015-0.031) and over 6 weeks (p = 0.045). The late group had more expressions on day 1 (early: p = 0.049; intermediate; p = 0.048).

CONCLUSION

Initiation of expression at 181-360 min following delivery was associated with increased milk production for 6 weeks following delivery. Further research is needed to determine the effect of expression frequency on milk production in the first days following birth.

γδ T cells are the predominant T cell type in opossum mammaries during lactation

Milk provides mammalian neonates with nutritional support and passive immunity. This is particularly true in marsupials where young are born highly altricial and lacking many components of a fully functional adaptive immune system. Here we investigated the T cell populations in the mammaries of a lactating marsupial, the gray short-tailed opossum Monodelphis domestica. Immunohistochemistry confirmed the presence of T cells within the opossum mammaries throughout lactation. Results of quantifying transcript abundance for lymphocyte markers are consistent with γδ T cells being the most common T cell type within lactating mammaries. Numbers of γδ T cells appear to peak early during the first postnatal week, and then decline throughout lactation until weaning. In contrast, numbers of αβ T cells and γμ T cells appear to be low to non-existent in the lactating mammaries. The results support an ancient and conserved role of immune cells in the evolution and function of mammalian mammary tissue.

The impact of environmental pollution on the quality of mother's milk

Breastfeeding is a gold standard of neonate nutrition because human milk contains a lot of essential compounds crucial for proper development of a child. However, milk is also a biofluid which can contain environmental pollution, which can have effects on immune system and consequently on the various body organs. Polychlorinated biphenyls are organic pollutants which have been detected in human milk. They have lipophilic properties, so they can penetrate to fatty milk and ultimately to neonate digestive track. Another problem of interest is the presence in milk of heavy metals-arsenic, lead, cadmium, and mercury-as these compounds can lead to disorders in production of cytokines, which are important immunomodulators. The toxicants cause stimulation or suppression of this compounds. This can lead to health problems in children as allergy, disorders in the endocrine system, end even neurodevelopment delay and disorder. Consequently, correlations between pollutants and bioactive components in milk should be investigated. This article provides an overview of environmental pollutants found in human milk as well as of the consequences of cytokine disorder correlated with presence of heavy metals. Graphical abstract.

Pro-inflammatory cytokines and growth factors in human milk: an exploratory analysis of racial differences to inform breast cancer etiology

BACKGROUND

Analysis of cytokines and growth factors in human milk offers a noninvasive approach for studying the microenvironment of the postpartum breast, which may better reflect tissue levels than testing blood samples. Given that Black women have a higher incidence of early-onset breast cancers than White women, we hypothesized that milk of the former contains higher levels of pro-inflammatory cytokines, adipokines, and growth factors.

METHODS

Participants included 130 Black and 162 White women without a history of a breast biopsy who completed a health assessment questionnaire and donated milk for research. Concentrations of 15 analytes in milk were examined using two multiplex and 4 single-analyte electrochemiluminescent sandwich assays to measure pro-inflammatory cytokines, angiogenesis factors, and adipokines. Mixed-effects ordinal logistic regression was used to identify determinants of analyte levels and to compare results by race, with adjustment for confounders. Factor analysis was used to examine covariation among analytes.

RESULTS

Thirteen of 15 analytes were detected in ≥ 25% of the human milk specimens. In multivariable models, elevated BMI was significantly associated with increased concentrations of 5 cytokines: IL-1β, bFGF, FASL, EGF, and leptin (all p-trend < 0.05). Black women had significantly higher levels of leptin and IL-1β, controlling for BMI. Factor analysis of analyte levels identified two factors related to inflammation and growth factor pathways.

CONCLUSION

This exploratory study demonstrated the feasibility of measuring pro-inflammatory cytokines, adipokines, and angiogenesis factors in human milk, and revealed higher levels of some pro-inflammatory factors, as well as increased leptin levels, among Black as compared with White women.

Oropharyngeal Colostrum Administration in Very Low Birth Weight Infants: A Randomized Controlled Trial

OBJECTIVES

Studies have confirmed the safety of oropharyngeal administration of colostrum in very low birth weight infants. However, the effect of oropharyngeal administration of colostrum on immune system is inconclusive. This study aims to evaluate the effect of oropharyngeal administration of colostrum on secretory immunoglobulin A and lactoferrin in very low birth weight infants.

DESIGN

Randomized controlled trial.

SETTING

Forty-bedded neonatal ICU in a university children's hospital in the People's Republic of China.

PATIENTS

Very low birth weight infants were allocated to the study group (n = 32) and control group (n = 32).

INTERVENTION

The intervention was oropharyngeal administration of 0.2 mL of their mother's colostrum every 4 hours for 7 days. The control group received saline solution.

MEASUREMENTS AND MAIN RESULTS

Secretory immunoglobulin A and lactoferrin in urine and saliva were measured within 24 hours of life (baseline) and at 7 and 21 days. Primary outcomes were changes of secretory immunoglobulin A and lactoferrin in urine and saliva between baseline and at 7 and 21 days. Infant's clinical data were also collected during hospitalization. Change from baseline in lactoferrin in saliva at 7 days (5.18 ± 7.07 vs -1.74 ± 4.67 µg/mL; p < 0.001) and 21 days (5.31 ± 9.74 vs -1.17 ± 10.38 µg/mL; p = 0.02) shows statistic difference. No differences were found of lactoferrin in urine and also no differences of secretory immunoglobulin A in urine and saliva. There were also no differences between days to full enteral feeding, occurrence rate of clinical sepsis, proven sepsis, and necrotizing enterocolitis.

CONCLUSIONS

Oropharyngeal administration of colostrum can increases the level of lactoferrin in saliva in very low birth weight infants. No effect could be documented of secretory immunoglobulin A and lactoferrin in urine. Larger trials are needed to better describe the benefit of oropharyngeal administration of colostrum, if any, in very low birth weight infants.

"Omics" in Human Colostrum and Mature Milk: Looking to Old Data with New Eyes

Human Milk (HM) is the best source for newborn nutrition until at least six months; it exerts anti-inflammatory and anti-infective functions, promotes immune system formation and supports organ development. Breastfeeding could also protect from obesity, diabetes and cardiovascular disease. Furthermore, human colostrum (HC) presents a peculiar role in newborn support as a protective effect against allergic and chronic diseases, in addition to long-term metabolic benefits. In this review, we discuss the recent literature regarding "omics" technologies and growth factors (GF) in HC and the effects of pasteurization on its composition. Our aim was to provide new evidence in terms of transcriptomics, proteomics, metabolomics, and microbiomics, also in relation to maternal metabolic diseases and/or fetal anomalies and to underline the functions of GF. Since HC results are so precious, particularly for the vulnerable pre-terms category, we also discuss the importance of HM pasteurization to ensure donated HC even to neonates whose mothers are unable to provide. To the best of our knowledge, this is the first review analyzing in detail the molecular pattern, microbiota, bioactive factors, and dynamic profile of HC, finding clinical correlations of such mediators with their possible in vivo effects and with the consequent impact on neonatal outcomes.

What's Normal? Immune Profiling of Human Milk from Healthy Women Living in Different Geographical and Socioeconomic Settings

Human milk provides a very wide range of nutrients and bioactive components, including immune factors, human milk oligosaccharides, and a commensal microbiota. These factors are essential for interconnected processes including immunity programming and the development of a normal infant gastrointestinal microbiome. Newborn immune protection mostly relies on maternal immune factors provided through milk. However, studies dealing with an in-depth profiling of the different immune compounds present in human milk and with the assessment of their natural variation in healthy women from different populations are scarce. In this context, the objective of this work was the detection and quantification of a wide array of immune compounds, including innate immunity factors (IL1β, IL6, IL12, INFγ, TNFα), acquired immunity factors (IL2, IL4, IL10, IL13, IL17), chemokines (IL8, Groα, MCP1, MIP1β), growth factors [IL5, IL7, epidermal growth factor (EGF), granulocyte colony-stimulating factor, granulocyte-macrophage colony-stimulating factor, TGFβ2], and immunoglobulins (IgA, IgG, IgM), in milk produced by healthy women of different ethnicities living in different geographic, dietary, socioeconomic, and environmental settings. Among the analyzed factors, IgA, IgG, IgM, EGF, TGFβ2, IL7, IL8, Groα, and MIP1β were detected in all or most of the samples collected in each population and, therefore, this specific set of compounds might be considered as the "core" soluble immune factors in milk produced by healthy women worldwide. This approach may help define which immune factors are (or are not) common in milk produced by women living in various conditions, and to identify host, lifestyle, and environmental factors that affect the immunological composition of this complex biological fluid. Clinical Trial Registration: www.ClinicalTrials.gov, identifier NCT02670278.

Subclinical mastitis occurs frequently in association with dramatic changes in inflammatory/anti-inflammatory breast milk components

BACKGROUND

Subclinical mastitis (SCM) is a frequent, but poorly characterized entity that may influence immune development of breastfed infants. Mechanisms driving the emergence of SCM and changes in immunological content of human milk during SCM remain to be explored. In this study, the breast milk environment was to describe during SCM.

METHODS

One hundred and ten samples of mature breast milk were collected from 44 healthy, HIV-negative mothers, included in a large infant feeding intervention cohort (ANRS 1271/Vertical Transmission Study). Immune markers related to inflammatory/anti-inflammatory balances and secreted in response to bacterial exposure were explored in SCM breast milk samples (Na/K ratio > 1) and compared to non-SCM controls.

RESULTS

SCM was observed in 23% of women (95% confidence interval (CI): 21-24) and associated with higher levels of inflammatory markers (β2 microgobulin, PS100A9, TNF-α, IL-6, IL-8, IL-17, and RANTES) and Th1-related cytokines (IL-2R, IL-12p40/70, IFN-α, IFN-γ, CXCL-9, andIP-10). High levels of factors secreted in response to bacteria and lipopolysaccharide (LPS) exposure were observed in SCM breast milk samples (MIP-1α, MIP-1β, LPS binding protein, α-defensins, and antileukoproteinase 1).

CONCLUSION

SCM is associated with important changes in breast milk microenvironment, with a proinflammatory/Th1-cytokine predominant profile. During SCM, cytokine imbalances in breast milk may have a notable influence on mucosal immune system of the infant early in life.

Maternal and pregnancy-related factors affecting human milk cytokines among Peruvian mothers bearing low-birth-weight neonates

Several cytokines have been detected in human milk but their relative concentrations differ among women and vary over time in the same person. The drivers of such differences have been only partially identified, while the effect of luminal cytokines in the fine-regulation of the intestinal immune system is increasingly appreciated. The aim of this study was to investigate the associations between obstetrical complications and human milk cytokine profiles in a cohort of Peruvian women giving birth to Low Birth Weight (LBW) infants. Colostrum and mature human milk samples were collected from 301 Peruvian women bearing LBW infants. The concentration of twenty-three cytokines was measured using the Luminex platform. Ninety-nine percent of women had at least one identified obstetrical complication leading to intra-uterine growth restriction and/or preterm birth. Median weight at birth was 1,420g; median gestational age 31 weeks. A core of 12 cytokines, mainly involved in innate immunity and epithelial cell integrity, was detectable in most samples. Maternal age, maternal infection, hypertensive disorders, preterm labor, and premature rupture of membranes were associated with specific cytokine profiles both in colostrum and mature human milk. Mothers of Very LBW (VLBW) neonates had significantly higher concentrations of chemokines and growth factor cytokines both in their colostrum and mature milk compared with mothers of larger neonates. Thus, maternal conditions affecting pregnancy duration and in utero growth are also associated with specific human milk cytokine signatures.

Potential of breastmilk analysis to inform early events in breast carcinogenesis: rationale and considerations

This review summarizes methods related to the study of human breastmilk in etiologic and biomarkers research. Despite the importance of reproductive factors in breast carcinogenesis, factors that act early in life are difficult to study because young women rarely require breast imaging or biopsy, and analysis of critical circulating factors (e.g., hormones) is often complicated by the requirement to accurately account for menstrual cycle date. Accordingly, novel approaches are needed to understand how events such as pregnancy, breastfeeding, weaning, and post-weaning breast remodeling influence breast cancer risk. Analysis of breastmilk offers opportunities to understand mechanisms related to carcinogenesis in the breast, and to identify risk markers that may inform efforts to identify high-risk women early in the carcinogenic process. In addition, analysis of breastmilk could have value in early detection or diagnosis of breast cancer. In this article, we describe the potential for using breastmilk to characterize the microenvironment of the lactating breast with the goal of advancing research on risk assessment, prevention, and detection of breast cancer.