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

The hormonal physiology of immune components in breast milk and their impact on the infant immune response

During pregnancy, the maternal body undergoes a considerable transformation regarding the anatomy, metabolism, and immune profile that, after delivery, allows for protection and nourishment of the offspring via lactation. Pregnancy hormones are responsible for the development and functionality of the mammary gland for breast milk production, but little is known about how hormones control its immune properties. Breast milk composition is highly dynamic, adapting to the nutritional and immunological needs that the infant requires in the first months of life and is responsible for the main immune modeling of breastfed newborns. Therefore, alterations in the mechanisms that control the endocrinology of mammary gland adaptation for lactation could disturb the properties of breast milk that prepare the neonatal immune system to respond to the first immunologic challenges. In modern life, humans are chronically exposed to endocrine disruptors (EDs), which alter the endocrine physiology of mammals, affecting the composition of breast milk and hence the neonatal immune response. In this review, we provide a landscape of the possible role of hormones in the control of passive immunity transferred by breast milk and the possible effect of maternal exposure to EDs on lactation, as well as their impacts on the development of neonatal immunity.

Cytokines and Chemokines in Breastmilk of SARS-CoV-2 Infected or COVID-19 Vaccinated Mothers

INTRODUCTION

The COVID-19 disease and anti-SARS-CoV-2 vaccination were accompanied by alterations in several inflammatory markers. The aim of our research was to check to what extent such cytokines are transferred to infants via the breastmilk of SARS-CoV-2-infected or vaccinated mothers. Thus, we wanted to check if breastfeeding is safe during SARS-CoV-2 infection or after COVID-19 mRNA-vaccination.

MATERIAL AND METHOD

The Luminex Multiplexing Assay was used for quantifying 10 cytokine in the human breastmilk of SARS-CoV-2-infected or COVID-19-vaccinated mothers, compared with anti-SARS-CoV-2 IgG naïve mothers. Two milk samples were collected at 30 and 60 days either after the booster dose or afterthe onset of symptoms. A single milk sample was collected from the mothers within the control group.

RESULTS

The cytokine concentrations were mostly found within the reference intervals for all mothers. The status of the vaccinated/infected mother, the age of the breastfed child, the parity of the mother and the maternal age were variation factors of the above-mentioned cytokine concentrations. The type of birth and the presence of IgG in the milk had no influence on these cytokine concentrations in milk. Furthermore, no statistically significant differences were recorded between the cytokine concentrations of the two milk samples.

CONCLUSION

Our study provides data that support the safety of breastfeeding in the case of mild COVID-19 infection or after Pfizer or Moderna vaccinations.

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

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

Human Milk Glucose, Leptin, and Insulin Predict Cessation of Full Breastfeeding and Initiation of Formula Use

Objective: We aimed to investigate prospective associations between milk bioactives related to metabolic health (glucose, insulin, leptin, C reactive protein [CRP], and interleukin 6 [IL-6]) and incident formula initiation at 3 and 6 months postpartum. Design: This study included 363 mother-infant dyads who were fully breastfed at 1 month and participated in the prospective Mothers and Infants Linked for Healthy Growth study from pregnancy to 6 months postpartum. Associations between milk glucose, leptin, insulin, CRP, and IL-6 at 1 and 3 months and incident formula feeding (FF) at 3 and 6 months, respectively, were tested using multiple logistic regression, adjusting for numerous potential confounders such as maternal age and prepregnancy body mass index. Results: At 3 months postpartum, 1-month glucose (odds ratio [OR] 0.45 [95% confidence interval (CI): 0.27-0.75], p ≤ 0.01) and smaller decreases in glucose from 1 to 3 months (OR 0.51 [95% CI: 0.28-0.92], p = 0.03) were associated with lower odds of FF, whereas 1-month leptin (OR 2.30 [95% CI: 1.30-4.07], p < 0.01) and larger increase in insulin (OR 1.86 [95% CI: 1.23-2.81], p < 0.01) and leptin (OR 2.17 [95% CI: 1.29-3.68], p < 0.01) from 1 to 3 months were associated with increased odds of FF. At 6 months, insulin increases (OR 2.08 [95% CI: 1.03-4.17], p = 0.04) were associated with higher odds of FF. Conclusions: In a cohort of women with established lactation, 1-month milk glucose, insulin, and leptin predicted initiation of FF at 3 months. Early milk composition may provide a window into mammary gland function, allowing identification of women at risk of not meeting their breastfeeding goals.

Cytokines-Biogenesis and Their Role in Human Breast Milk and Determination

Cytokines play a huge role in many biological processes. Their production, release and interactions are subject to a very complex mechanism. Cytokines are produced by all types of cells, they function very differently and they are characterized by synergism in action, antagonism, and aggregation activity, opposing action of one cytokine, overlapping activity, induction of another cytokine, inhibition of cytokine synthesis at the mRNA level as well as autoregulation-stimulation or inhibition of own production. The predominance of pro-inflammatory cytokines leads to a systemic inflammatory response, and anti-inflammatory-to an anti-inflammatory response. They regulate the organism's immune response and protect it against sudden disturbances in homeostasis. The synthesis and activity of cytokines are influenced by the central nervous system through the endocrine system (pituitary gland, adrenal glands).

Breastfeeding Contributes to Physiological Immune Programming in the Newborn

The first 1,000 days in the life of a human being are a vulnerable stage where early stimuli may program adverse health outcomes in future life. Proper maternal nutrition before and during pregnancy modulates the development of the fetus, a physiological process known as fetal programming. Defective programming promotes non-communicable chronic diseases in the newborn which might be prevented by postnatal interventions such as breastfeeding. Breast milk provides distinct bioactive molecules that contribute to immune maturation, organ development, and healthy microbial gut colonization, and also secures a proper immunological response that protects against infection and inflammation in the newborn. The gut microbiome provides the most critical immune microbial stimulation in the newborn in early life, allowing a well-trained immune system and efficient metabolic settings in healthy subjects. Conversely, negative fetal programming by exposing mothers to diets rich in fat and sugar has profound effects on breast milk composition and alters the immune profiles in the newborn. At this new stage, newborns become vulnerable to immune compromise, favoring susceptibility to defective microbial gut colonization and immune response. This review will focus on the importance of breastfeeding and its immunological biocomponents that allow physiological immune programming in the newborn. We will highlight the importance of immunological settings by breastfeeding, allowing proper microbial gut colonization in the newborn as a window of opportunity to secure effective immunological response.

The impact of maternal obesity and breast milk inflammation on developmental programming of infant growth

Background:

Little is known about how maternal obesity impacts breast milk (BM) composition and how BM composition may impact growth. We sought to determine the role of maternal body mass index (BMI) on BM inflammatory and oxidative stress markers and to delineate the role of these BM markers on infant growth.

Methods:

This was a secondary analysis of 40 mother-infant dyads. We first assessed the association between maternal BMI and BM marker (omega-6:omega-3 polyunsaturated fatty acid ratio (n-6:n-3 PUFA), leptin, interleukin (IL)-8, IL-6, IL-1β and malondialdehyde (MDA)) concentration at one (V1) and four (V4) months postpartum. We then examined the association between BM markers on infant growth trajectory from birth to seven months.

Results:

Higher maternal BMI was associated with higher BM n-6:n-3 PUFA (V1 β=0.12, 95% CI 0.01, 0.2; V4 β=0.13, 95% CI 0.01, 0.3) and leptin (V1 β=107, 95% CI 29, 184; V4 β=254, 95% CI 105, 403) concentrations. Infants exposed to high BM n-6:n-3 PUFA had higher BMI z-scores over time (p=0.01). Higher BM leptin was associated with lower infant percent fat mass at V4 (β=−9, 95% CI −17, −0.6). Infants exposed to high BM IL-8, IL-6, or IL-1β had higher weight z-scores over time (IL-8 p<0.001; IL-6 p<0.001; IL-1β p=0.02). There was no association between BM MDA and maternal BMI or infant growth.

Conclusions:

Higher maternal BMI is associated with higher BM n-6:n-3 PUFA and leptin concentrations. In addition, higher BM n-6:n-3 PUFA and inflammatory cytokines were associated with accelerated weight gain in infancy.

Cytokines and Soluble Receptors in Breast Milk as Enhancers of Oral Tolerance Development

The postpartum period is an important window during which environmental factors can shape the life-long health of the infant. This time period often coincides with substantial milk consumption either in the form of breast milk or from cow's milk sources, such as infant formulas. Although breast milk is the most beneficial source of nutrients for infants during the first 6 months after birth, its role in regulating food allergy development, through regulation of oral tolerance, is still controversial. Breast milk contains several factors that can impact mucosal immune function, including immune cells, antibodies, microbiota, oligosaccharides, cytokines, and soluble receptors. However, there is considerable variation in the assessed levels of cytokines and soluble receptors between studies and across the lactation period. Most of these cytokines and soluble receptors are absent, or only found in limited quantities, in commercial baby formulas. Differences in content of these pluripotent factors, which impact on both the mother and the neonate, could contribute to the controversy surrounding the role of breast milk regulating oral tolerance. This review highlights current knowledge about the importance of cytokines and soluble receptors in breast milk on the development of oral tolerance and tolerance-relateddisorders. Understanding the mechanisms by which such milk components might promote oral tolerance could aid in the development of improved strategies for allergy prevention.

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.

Breast Milk Cytokines and Early Growth in Gambian Infants

Background: Breast milk provides nutrition for infants but also delivers other bioactive factors that have key protective and developmental benefits. In particular, cytokines are thought to play a role in immunomodulation, although little is known about their impact on health outcomes in early life. Objective: The purpose of this pilot study was to evaluate the relationship between cytokines in breast milk and infant growth outcomes in a low-income setting. Methods: 100 mother-infant pairs were followed up to 2-3 months postpartum as part of a prospective longitudinal cohort study in urban Gambia, West Africa. The concentrations of 9 pro-inflammatory cytokines (IL-1β, IL-2, IL-4, IL-6, IL-10, IL-12, IL-13, IFN-γ, TNFα), IGF-1 and TGFβ2 were measured in colostrum within 12 h of birth and in breast milk at the final visit, scheduled between day 60 and 89 postpartum. Infant weight was recorded and converted to weight-for-age Z-scores (WAZ) at the same time points. Growth outcomes were defined in our study as (a) change in WAZ between birth and final visit (b) WAZ at final visit. Linear regression analysis was used to determine the ability of colostrum and breast milk cytokine concentrations to predict growth outcomes up to 2-3 months postpartum. Results: Gambian infants demonstrated growth faltering across the first 2-3 months postpartum. There was no significant relationship between cytokines in colostrum and subsequent change in WAZ between birth and the final visit, in either unadjusted or adjusted models. However, cytokines in mature breast milk, TNFα, IFNγ, IL1β, IL2, IL4, and IL6, were weak negative predictors of WAZ scores at the final visit, in unadjusted models (p < 0.05). When adjusted for maternal anemia (as a proxy for maternal nutrition), TNFα and IL6 remained significant predictors (p < 0.05). Conclusions: Variations in breast milk cytokine levels do not play a substantial role in the growth faltering observed across early infancy. The potential contribution of other factors, such as micronutrients, hormones or human milk oligosaccharides, must be elucidated. Cytokine levels in mature breast milk were weakly predictive of poor infant growth, possibly reflecting a "read-out" of suboptimal maternal health and nutrition.

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.

Leukocytes in expressed breast milk of asthmatic mothers

OBJECTIVE

Infants are born immunologically immature. However, breastfeeding mothers retain an immunological link to their infants. While it is generally accepted that infants are at an immunological advantage when compared with formula-fed infants, the benefit of long-term exclusive breastfeeding by atopic mothers remains controversial. Inconsistency in the conferral of benefit may be due to differences in the immunological constituents passed to the recipient infant. The aim of this investigation was to examine the profile of human milk cells and cytokines from asthmatic compared to non-asthmatic mothers.

METHODS

Twenty-five exclusively breastfeeding mothers with a clinical diagnosis of asthma were postpartum age matched in a double-control 2:1 design with 50 non-asthmatic controls. Each mother provided a single milk sample which was assayed for cell differential by flow cytometry, for ex vivo cytokine production in culture and for aqueous phase cytokines.

RESULTS

Milks from asthmatic mothers differed from non-asthmatics in that they contained a higher proportion of polymorphonuclear (PMN) cells and lower proportion of lymphocytes, predominantly CD3⁺/CD4⁺ T helper cells, reflected by a decrease in the chemokine CCL5 in the milk aqueous phase. More PMN and lymphocytes from asthmatic mothers expressed the adhesion molecule CD11b and lymphocytes the IgE receptor CD23, than those from non-asthmatic mothers.

CONCLUSIONS

Changes to human milk leucocyte prevalence, activation state and cytokines due to maternal asthma may result in changes to immunological priming in the infant. Consequently, the protective effect of long-term breastfeeding may be altered in these mother-infant pairs.

Protective Role of Passively Transferred Maternal Cytokines against Bordetella pertussis Infection in Newborn Piglets

Maternal vaccination represents a potential strategy to protect both the mother and the offspring against life-threatening infections. This protective role has mainly been associated with antibodies, but the role of cell-mediated immunity, in particular passively transferred cytokines, is not well understood. Here, using a pertussis model, we have demonstrated that immunization of pregnant sows with heat-inactivated bacteria leads to induction of a wide range of cytokines (e.g., tumor necrosis factor alpha [TNF-α], gamma interferon [IFN-γ], interleukin-6 [IL-6], IL-8, and IL-12/IL-23p40) in addition to pertussis-specific antibodies. These cytokines can be detected in the sera and colostrum/milk of vaccinated sows and subsequently were detected at significant levels in the serum and bronchoalveolar lavage fluid of piglets born to vaccinated sows together with pertussis-specific antibodies. In contrast, active vaccination of newborn piglets with heat-inactivated bacteria induced high levels of specific IgG and IgA but no cytokines. Although the levels of antibodies in vaccinated piglets were comparable to those of passively transferred antibodies, no protection against Bordetella pertussis infection was observed. Thus, our results demonstrate that a combination of passively transferred cytokines and antibodies is crucial for disease protection. The presence of passively transferred cytokines/antibodies influences the cytokine secretion ability of splenocytes in the neonate, which provides novel evidence that maternal immunization can influence the newborn's cytokine milieu and may impact immune cell differentiation (e.g., Th1/Th2 phenotype). Therefore, these maternally derived cytokines may play an essential role both as mediators of early defense against infections and possibly as modulators of the immune repertoire of the offspring.

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.

Prebiotic consumption in pregnant and lactating women increases IL-27 expression in human milk

The consumption of probiotics by pregnant and lactating women may prevent the onset of allergic disorders in their children by increasing the concentrations of immunoactive agents such as cytokines in breast milk. Prebiotics such as fructo-oligosaccharides (FOS) increase the number of beneficial organisms such as bifidobacteria. Thus, prebiotics may have an effect similar to that of probiotics. The objective of the present study was to carry out a comprehensive analysis of mRNA expression in human milk cells to identify changes in the concentrations of cytokines in breast milk after the consumption of FOS (4 g × 2 times/d) by pregnant and lactating women. The microarray analysis of human milk cells demonstrated that the expression levels of five genes in colostrum samples and fourteen genes in 1-month breast milk samples differed more than 3-fold between the FOS and control groups (sucrose group). The mRNA expression level of IL-27, a cytokine associated with immunoregulatory function, was significantly higher in 1-month breast milk samples obtained from the FOS group than in those obtained from the control group. In addition, the protein concentrations of IL-27 in colostrum and 1-month breast milk samples were significantly higher in the FOS group than in the control group. In conclusion, the consumption of FOS by pregnant and lactating women increases the production of IL-27 in breast milk. Future studies will address the association of this phenomenon with the onset of allergic disorders in children.

Prototypic long pentraxin PTX3 is present in breast milk, spreads in tissues, and protects neonate mice from Pseudomonas aeruginosa lung infection

Newborns and infants present a higher susceptibility to infection than adults, a vulnerability associated with deficiencies in both the innate and adaptive immune systems. Innate immune receptors are sensors involved in the recognition and elimination of microbes that play a pivotal role at the interface between innate and adaptive immunity. Pentraxin 3 (PTX3), the prototypic long pentraxin, is a soluble pattern recognition receptor involved in the initiation of protective responses against selected pathogens. Because neonates are generally resistant to these pathogens, we suspected that PTX3 may be provided by a maternal source during the early life times. We observed that human colostrum contains high levels of PTX3, and that mammary epithelial cell and CD11b(+) milk cells constitutively produce PTX3. Interestingly, PTX3 given orally to neonate mice was rapidly distributed in different organs, and PTX3 ingested during lactation was detected in neonates. Finally, we observed that orally administered PTX3 provided protection against Pseudomonas aeruginosa lung infection in neonate mice. Therefore, breastfeeding constitutes, during the early life times, an important source of PTX3, which actively participates in the protection of neonates against infections. In addition, these results suggest that PTX3 might represent a therapeutic tool for treating neonatal infections and support the view that breastfeeding has beneficial effects on the neonates' health.

Breast milk cellular HIV-specific interferon γ responses are associated with protection from peripartum HIV transmission

OBJECTIVE

Breast milk is a major route of infant HIV infection, yet the majority of breast-fed, HIV-exposed infants escape infection by unknown mechanisms. This study aimed to investigate the role of HIV-specific breast milk cells in preventing infant HIV infection.

DESIGN

A prospective study was designed to measure associations between maternal breast milk HIV-specific interferon-γ (IFN-γ) responses and infant HIV-1 detection at 1 month of age.

METHODS

In a Kenyan cohort of HIV-infected mothers, blood and breast milk HIV-gag IFN-γ ELISpot responses were measured. Logistic regression was used to measure associations between breast milk IFN-γ responses and infant HIV infection at 1 month of age.

RESULTS

IFN-γ responses were detected in breast milk from 117 of 170 (69%) women. IFN-γ responses were associated with breast milk viral load, levels of macrophage inflammatory protein (MIP) 1α, MIP-1β, regulated upon activation, normal T-cell expressed, and secreted and stromal-cell derived factor 1 and subclinical mastitis. Univariate factors associated with infant HIV infection at 1 month postpartum included both detection and breadth of breast milk IFN-γ response (P = 0.08, P = 0.04, respectively), breast milk MIP-1β detection (P = 0.05), and plasma (P = 0.004) and breast milk (P = 0.004) viral load. In multivariate analyses adjusting for breast milk viral load and MIP-1β, breast milk IFN-γ responses were associated with an approximately 70% reduction in infant HIV infection [adjusted odds ratio (aOR) 0.29, 95% confidence interval (CI) 0.092-0.91], and each additional peptide pool targeted was associated with an approximately 35% reduction in infant HIV (aOR 0.65, 95% CI 0.44-0.97).

CONCLUSION

These data show breast milk HIV-gag-specific IFN-γ cellular immune responses are prevalent and may contribute to protection from early HIV transmission. More broadly, these data suggest breast milk cellular responses are potentially influential in decreasing mother-to-child transmission of viruses.

Changes in immunomodulatory constituents of human milk in response to active infection in the nursing infant

INTRODUCTION

To investigate whether immunologic factors in breast milk change in response to nursing infants' infection.

RESULTS

Total CD45 leukocyte count dropped from 5,655 (median and interquartile range: 1,911; 16,871) in the acute phase to 2,122 (672; 6,819) cells/ml milk after recovery with macrophage count decreasing from 1,220 (236; 3,973) to 300 (122; 945) cells/ml. Tumor necrosis factor-α (TNFα) levels decreased from 3.66 ± 1.68 to 2.91 ± 1.51 pg/ml. The decrease in lactoferrin levels was of borderline statistical significance. Such differences were not recorded in samples of the controls. Interleukin-10 levels decreased in the sick infants' breast milk after recovery, but also in the healthy controls, requiring further investigation. Secretory immunoglobulin A levels did not change significantly in the study or control group.

DISCUSSION

During active infection in nursing infants, the total number of white blood cells, specifically the number of macrophages, and TNFα levels increase in their mothers' breast milk. These results may support the dynamic nature of the immune defense provided by breastfeeding sick infants.

METHODS

Breast milk from mothers of 31 infants, up to 3 months of age, who were hospitalized with fever, was sampled during active illness and recovery. Milk from mothers of 20 healthy infants served as controls.

Immune markers in breast milk and fetal and maternal body fluids: a systematic review of perinatal concentrations

Breastfeeding represents the continued exposure of the infant to the maternal immune environment.Uterine, perinatal, and postnatal exposure to immune factors may contribute to an infant’s risk of developing immune-mediated disorders, including allergies. A PubMed search was conducted to review studies in humans and analyze concentrations of immune markers (TGF-beta, IFN-gamma, eotaxin, CCL5, CXCL10, TNF-alpha, MCP-1, IL-1beta, IL-4, IL-5, IL-6,IL-8, IL-10, IL-12, IL-13, sCD14, sIgA, IgG4, IgM) found in maternal serum, amniotic fluid, cord serum, colostrum, transition and mature milk. Concentrations of immune markers showed large variations across samples and studies. Reports documented conflicting results. Small sample sizes, differences in population characteristics, inconsistent sample collection times, and various sample collection and measurement methods may have led to wide variations in the concentrations of immune markers. Studies analyzing the associations between immune markers in maternal fluids and infant allergies remain inconclusive because of gaps in knowledge and a lack of standardized methods.

Oropharyngeal administration of colostrum to extremely low birth weight infants: theoretical perspectives

Studies in adults have shown that the oropharyngeal route can be used to effectively and safely administer interferon-alpha, an immune cell-derived cytokine, to patients who are unable to tolerate its parenteral administration. The mechanism for this appears to be the stimulatory effects of the cytokine, on the oropharyngeal-associated lymphoid tissue system. Own mother's colostrum (OMC) is rich in cytokines and other immune agents that provide bacteriostatic, bacteriocidal, antiviral, anti-inflammatory and immunomodulatory protection against infection. OMC may be especially protective for the extremely low birth weight (ELBW) infant in the first days of life; however clinical instability typically precludes enteral feedings during this period. Oropharyngeal administration is a potential alternative method of providing OMC. Oropharyngeal administration of OMC may have immunomodulatory effects on the recipient infant, and would be especially beneficial to the ELBW infant who would otherwise remain nil per os during the first days of life.

The immunological components of human milk

Breast-feeding is generally accepted as the optimal method of feeding infants. However, we have yet to fully understand the complex mixture of bioactive compounds contained in human milk. Epidemiological studies have indicated that breast-feeding is associated with health benefits in the infant for many immune-related conditions. Breast milk contains various antimicrobial substances, factors that promote immune development, constituents that promote tolerance/priming of the infant immune system, as well as anti-inflammatory components. This chapter identifies and discusses the immunological compounds in human milk and the available evidence for their effect on the immune system of the infant. Current feeding regimens recommended for infants are based primarily on the current understanding of the nutritional requirements of the neonate, but perhaps will be modified to reflect the consequences on immune function both immediate and later in life.

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.

Bactericidal activity of macrophages against Streptococcus uberis is different in mammary gland secretions of lactating and drying off cows

The aim of this study was to compare the ability of milk macrophages and macrophages from the mammary gland secretions during the mid-dry period for their interaction with the mastitis-causing Streptococcus uberis. We also aimed to determine if S. uberis induced the release of the cytokine tumour necrosis alpha (TNF-alpha) and the bactericidal moiety nitric oxide (NO) from milk macrophages of lactating cows and macrophages from the mammary gland secretions at the mid-dry period. Macrophages were isolated from the mammary gland secretions of cows during the mid-lactation or mid-dry period, and compared with blood monocytes for their interaction with the important mastitis-causing pathogen S. uberis. When infected in vitro with S. uberis, milk macrophages from lactating cows with S. uberis released modest amounts of the cytokine tumour necrosis factor alpha (TNF-alpha) (139 pg/ml) and the bactericidal moiety nitric oxide (NO) (3-4 microM of nitrite). Blood monocytes from lactating cows released significantly higher amounts of TNF-alpha (345 +/- 143 pg/ml) and NO (7 +/- 2 microM of nitrite) after interaction with S. uberis, compared to milk macrophages (P < 0.01 for both TNF-alpha and NO). Stimulation of blood monocytes with the cytokine interferon-gamma (IFN-gamma) enhanced significantly the release of NO and TNF-alpha, but IFN-gamma did not significantly enhance the production of NO and TNF-alpha by milk macrophages from lactating cows. Milk macrophages from all lactating cows failed to kill S. uberis efficiently, and this lack of killing was unaffected by prior treatment with gamma interferon (IFN-gamma) (P > 0.05). Rather, S. uberis multiplied significantly inside infected milk macrophages from lactating cows, with a two-fold increase in bacterial numbers at 2 h post-infection. Milk macrophages from lactating cows were able however, to kill a significant proportion (50-60%, P < 0.01) of phagocytosed Staphylococcus aureus. Blood monocytes from all cows were found to exert significant bactericidal activity against S. uberis. There were no significant differences in the bactericidal activity of milk macrophages obtained from lactating cows with low somatic cell counts (SCC; < 10(5) ml(-1)) compared with those with a mildly elevated SCC (> 10(5) ml(-1)) (P > 0.05). In contrast, mammary gland secretion macrophages isolated from the same cows in the mid-dry period killed a significant proportion of phagocytosed S. uberis (50-65% of ingested S. uberis killed, P < 0.01) although cytokine production in response to in vitro bacterial infection was low. We conclude that the bactericidal activity of mammary gland secretion macrophages against a virulent strain of S. uberis is low during the lactation period. In addition, our data indicate that S. uberis is not a strong inducer of NO and TNF-alpha in macrophages from the milk or mammary gland secretions of cows during the drying off period. Finally, IFN-gamma does not activate milk macrophages or macrophages from cows during the lactating period or mammary gland secretions during the drying off period.

Fatty acids as modulators of the immune response

Research describing fatty acids as modulators of inflammation and immune responses abounds. Many of these studies have focused on one particular group of fatty acids, omega-3. The data from animal studies have shown that these fatty acids can have powerful anti-inflammatory and immunomodulatory activities in a wide array of diseases (e.g., autoimmunity, arthritis, and infection). However, the evidence from human trials is more equivocal. In this review, a historical framework for understanding how and why fatty acids may affect the immune system is provided. Second, highlights of two recent landmark reports from the Agency for Healthcare Research and Quality are presented. These reports critically evaluate the evidence from human clinical trials of omega-3 fatty acids and rheumatoid arthritis, asthma, and a few other immune-mediated diseases. Third, the data from human clinical trials investigating the impact of various bioactive fatty acids on ex vivo and in vivo immune response are reviewed. Limitations in experimental design and immune assays commonly used are discussed. The discordance between expectation and evidence in this field has been a disappointment. Recommendations for improving both animal-based and human studies are provided.

Interleukin-2 in human milk: a potential modulator of lymphocyte development in the breastfed infant

Development of lymphocyte subpopulations and response to antigen exposure will be influenced by the limited ability of neonates to produce cytokines. In the case of cytokines such as interleukin (IL)-2 which are potent T lymphocyte regulators but poorly produced by newborn infants, the supply of cytokines through human milk could alleviate an immunological deficit and potentially aid the maturation of the immune system. We analysed human milk from 52 mothers (15-357 days postpartum) by ELISA to determine levels of aqueous IL-2, as well as production by human milk cells. IL-2 was detectable (>8 pg/mL) in the aqueous phase of 81% of all day 1 samples with no significant difference found in the mean concentration over 3 consecutive days. IL-2 was produced constitutively at detectable levels by 57% of milk cell samples and production was significantly increased by stimulation with Con A (380%). No correlation was found between aqueous and cellular IL-2, however there was a significant correlation between milk aqueous IL-2 and serum IL-2. This is the first report of IL-2 in the aqueous phase of human milk. A supply of exogenous IL-2 in human milk may provide the suckling infant with important immunological signals during a significant stage of T cell development.

Role of breast milk in a mouse model of maternal transmission of asthma susceptibility

Epidemiologic data suggest a link between nursing by asthmatic mothers and increased risk of allergy in babies. We sought to experimentally test the potential contribution of breast milk mediator(s) in a mouse model of maternal transmission of asthma risk by evaluating the effect of adoptive nursing on asthma susceptibility in the offspring. We measured airway hyperresponsiveness (AHR) and allergic airway inflammation (AI) after an intentionally suboptimal OVA Ag sensitization, tested the allergen independence of the maternal effect by using a second allergen, casein, for sensitization of the baby mice, and tested the potential role of cytokines by measuring their levels in breast milk. Offspring of asthmatic, but not normal, mothers showed AHR and AI, indicating a maternal transfer of asthma risk. After adoptive nursing, both groups (litters born to asthmatic mothers and nursed by normal mothers, and normal babies nursed by asthmatic mothers) showed AHR (enhanced pause after methacholine aerosol, 50 mg/ml, 3.7 +/- 0.7, 4.2 +/- 0.5, respectively, vs 1.1 +/- 0.1 normal controls, n = 25, p < 0.01) and AI, seen as eosinophilia on histology and bronchoalveolar lavage (40.7 +/- 4.5%, 28.7 +/- 3.7%, vs 1.0 +/- 0.5% normals, n = 25, p < 0.01) after OVA sensitization. Similar results using casein allergen were observed. Multiplex assays for cytokines (IFN-gamma, IL-2, IL-4, IL-5, TNF-alpha, and IL-13) in breast milk were negative. Breast milk is sufficient, but not necessary, to mediate allergen-independent maternal transmission of asthma risk to offspring.

Persistency of high proinflammatory cytokine levels from colostrum to mature milk in preeclampsia

OBJECTIVES

Recent evidence suggests a role of an excessive maternal inflammatory response in the pathogenesis of preeclampsia. Whether this imbalance can be transferred from mother to breast milk remains to be established.

DESIGN AND METHODS

15 preeclamptic and 15 healthy pregnant women were recruited in this study. Colostrum and milk samples were collected postpartum in the first 48 h and at 30 days, respectively. Samples were analyzed for interleukin (IL)-1beta, IL-6, IL-8, tumor necrosis factor (TNF)-alpha and soluble IL-2R (sIL-2R) levels with chemiluminescence enzyme immunometric assays.

RESULTS

Colostrum cytokine levels corrected for gestational age and type of delivery were not significantly different in the two groups. Cytokine levels significantly decreased in mature milk versus colostrum in the control group (P < 0.05), but did not significantly decrease in the preeclampsia group (P > 0.05), except for TNF-alpha (P < 0.05). Mature milk IL-8 and TNF-alpha levels were higher in the preeclampsia group versus controls (P < 0.05).

CONCLUSION

Results of this study show that proinflammatory cytokines in breast milk exhibit biological variation at different periods of human lactation. In preeclampsia, high cytokine levels persist at least for 30 days. These results suggest that preeclampsia may affect milk cytokine balance and offer an immunological signal for the host defense in high-risk neonates.

Short-term effects on pro-inflammatory cytokine, lactoferrin and CD14 mRNA expression levels in bovine immunoseparated milk and blood cells treated by LPS

Leucocytes (WBC) are recruited from peripheral blood into milk as part of the inflammatory response, mediated through cytokines or interleukins (IL) synthesized by mammary tissue and the milk somatic cells (SC). The inflammatory response is related to the concentration of SC and the cytokines produced. To investigate and to compare the kinetics of cytokine production in SC and WBC during inflammation, cell culture models were established, where SC and WBC were cultured in parallel (n = 3). In addition, macrophages or monocytes were isolated from milk and blood with antibody-coated magnetic beads and cultivated separately. Isolated cells were pure, unaltered and viable. Cultures were activated with 10 microg/ml lipopolysaccharide (LPS). After 0, 1, 2, 3, 4 and 8 h cells were harvested for RNA isolation. Cytokine [tumour necrosis factor alpha (TNFalpha), IL-1beta, IL-6] mRNA expression responses and transcriptional activity of CD14 and lactoferrin (LF) were quantified via a one-step real-time RT-PCR. Significant cytokine mRNA increases were found in all four cell culture types and genes, with peaks after 1 and 2 h (TNFalpha > IL-6 > IL-1beta). In WBC or monocytes higher LPS responses and longer persistence could be found than in corresponding milk cells (IL-1beta > IL-6 > TNFalpha). SC and macrophages are less responsive to LPS stimulation than WBC or monocytes. The strength of the immune response in the blood system is much more prominent than in the mammary gland. This may be ascribed to the role of CD14 on the cytokine production of the investigated cells, or may be caused by the blood-to-milk diapedesis. The constitutive transcription of CD14 mRNA in WBC and monocytes was found to be 6 to 15 times higher than in adequate milk cells.

The immunological components of human milk and their effect on immune development in infants

There have been considerable advances in our understanding of the diverse mixture of bioactive components in human milk that influence the immune status of infants by not only providing protection but also facilitating development, tolerance, and an appropriate inflammatory response. It could be suggested that milk is the communication vehicle between the maternal immune system and the infant, a system actively directing and educating the immune, metabolic, and microflora systems within the infant, while conferring multiple means of protection from pathogens. The physiological and protective functions of many of the immune components in human milk have been deduced not from studies in infants but from what is known in other species and in vitro models. This update briefly reviews immune development in infants and focuses on current knowledge of how both the "classical" immune and the nonimmune ingredients found in mature human milk promote immune development, facilitate the development of tolerance, and regulate the inflammatory response of infants.

Characterization of breast milk received by infants with gross blood in stools

OBJECTIVE

The aim of this study was to ascertain factors that might be protective of the appearance of gross blood in the stools of breast-fed infants.

METHODS

Logistic regression models were formed to search for variables possibly explaining the condition. In addition to the analyzed breast milk factors, mother's allergic disease was introduced into the models to control for its possible confounding effect. The breast milk samples, collected from mothers of infants with gross blood in stools (n = 23) and from mothers of healthy age-matched infants (n = 71), were analyzed for concentrations of transforming growth factor-beta2, tumor necrosis factor-alpha, interleukin (IL)-4, IL-10, prostaglandin (PG)E2, cysteinyl leukotrienes (Cys-LTs) and fatty acid composition.

RESULTS AND CONCLUSIONS

Increase in the concentrations of PGE2 and Cys-LTs in the breast milk together with mother's allergic disease reduced the likelihood of gross blood in stools in the breast-fed infant. The results suggest that no single factor, but a combination of immunomodulatory factors may protect the child from gross blood in the stools of breast-fed infants. Allergic disease was not a risk factor as mother's allergic disease appeared to counterbalance the gross blood in stools. Due to the preliminary nature of the study, the results need to be verified in a larger setting. The challenge for the future lies in identifying of such active compounds for dietary modification to enforce particularly the properties of the breast milk which are immunoprotective for the infant and to reduce the likelihood of intestinal disorders in at risk infants.