Identification of sociodemographic and clinical factors associated with the levels of human β-defensin-1 and human β-defensin-2 in the human milk of Han Chinese

Infant Feeding, Gut Permeability, and Gut Inflammation Markers

OBJECTIVES

Increased gut permeability and gut inflammation have been linked to the development of type 1 diabetes. Little is known on whether and how intake of different foods is linked to these mechanisms in infancy. We investigated whether the amount of breast milk and intake of other foods are associated with gut inflammation marker concentrations and permeability.

METHODS

Seventy-three infants were followed from birth to 12 months of age. Their diet was assessed with structured questionnaires and 3-day weighed food records at the age of 3, 6, 9, and 12 months. Gut permeability was assessed with the lactulose/mannitol test and fecal calprotectin and human β-defensin-2 (HBD-2) concentrations were analyzed from stool samples at the age of 3, 6, 9, and 12 months. The associations between foods and gut inflammation marker concentrations and permeability were analyzed using generalized estimating equations.

RESULTS

Gut permeability and gut inflammation marker concentrations decreased during the first year of life. Intake of hydrolyzed infant formula ( P = 0.003) and intake of fruits and juices ( P = 0.001) were associated with lower intestinal permeability. Intake of fruits and juices ( P < 0.001), vegetables ( P < 0.001), and oats ( P = 0.003) were associated with lower concentrations of HBD-2. Higher intake of breast milk was associated with higher fecal calprotectin concentrations ( P < 0.001), while intake of fruits and juices ( P < 0.001), vegetables ( P < 0.001), and potatoes ( P = 0.007) were associated with lower calprotectin concentrations.

CONCLUSIONS

Higher intake of breast milk may contribute to higher calprotectin concentration, whereas several complementary foods may decrease gut permeability and concentrations of calprotectin and HBD-2 in infant gut.

Dynamic change, influencing factors, and clinical impact of cellular components in human breast milk

BACKGROUND

Numerous cellular components have been well demonstrated in human breast milk. However, little is known about their dynamic change, influencing factors, and potential clinical impacts on infants.

METHODS

Sixty and forty-five healthy mother-infant pairs were enrolled in the colostrum group and mature milk group, respectively. Participants' demographic and clinical information were collected by questionnaires, and the infants were followed up until 6 months after birth through telephone interview. Colostrum and mature milk were collected, and the percentage of various cell components were determined by flow cytometric analysis.

RESULTS

The results showed that, the total cell numbers, and the percentages of some stem cells, including CD34+, CD117+, CD133+, CD90+, CD105+, and CD146+ cells, were different in colostrum and mature milk. Besides, participants' characteristics had influence on the cellular components. Finally, high-CD34+ cells in colostrum, as well as the high-CD133+ cells and low-CD105+ cells in mature milk were associated with a significantly increased risk of infantile eczema within their first 3 months after birth.

CONCLUSIONS

Our data showed a dynamic change of cellular components, identified some of their influencing factors and their potential clinical impacts on infantile eczema, which helps to better understand the cellular components in human breast milk.

IMPACT

Some stem cell markers were dynamically changed in human colostrum and mature milk. Different cellular components were shown to be influenced by different participants' characteristics. High percentage of CD34+ cells in colostrum, as well as high percentage of CD133+ cells and low percentage of CD105+ cells in mature milk, were associated with a significantly increased risk of infantile eczema within their first 3 months after birth. To our knowledge, this is the first study on the clinical impacts of stem cells on infantile diseases, which helps to give a better understanding of human breast milk.

Antimicrobial Peptides in Early-Life Host Defense, Perinatal Infections, and Necrotizing Enterocolitis—An Update

Host defense against early-life infections such as chorioamnionitis, neonatal sepsis, or necrotizing enterocolitis (NEC) relies primarily on innate immunity, in which antimicrobial peptides (AMPs) play a major role. AMPs that are important for the fetus and neonate include α and β defensins, cathelicidin LL-37, antiproteases (elafin, SLPI), and hepcidin. They can be produced by the fetus or neonate, the placenta, chorioamniotic membranes, recruited neutrophils, and milk-protein ingestion or proteolysis. They possess antimicrobial, immunomodulating, inflammation-regulating, and tissue-repairing properties. AMPs are expressed as early as the 13th week and increase progressively through gestation. Limited studies are available on AMP expression and levels in the fetus and neonate. Nevertheless, existing evidence supports the role of AMPs in pathogenesis of chorioamnionitis, neonatal sepsis, and NEC, and their association with disease severity. This suggests a potential role of AMPs in diagnosis, prevention, prognosis, and treatment of sepsis and NEC. Herein, we present an overview of the antimicrobial and immunomodulating properties of human AMPs, their sources in the intrauterine environment, fetus, and neonate, and their changes during pre- and post-natal infections and NEC. We also discuss emerging data regarding the potential utility of AMPs in early-life infections, as diagnostic or predictive biomarkers and as therapeutic alternatives or adjuncts to antibiotic therapy considering the increase of antibiotic resistance in neonatal intensive care units.

Human β-Defensin 2 and Its Postulated Role in Modulation of the Immune Response

Studies described so far suggest that human β-defensin 2 is an important protein of innate immune response which provides protection for the human organism against invading pathogens of bacterial, viral, fungal, as well as parasitical origin. Its pivotal role in enhancing immunity was proved in infants. It may also be considered a marker of inflammation. Its therapeutic administration has been suggested for maintenance of the balance of systemic homeostasis based on the appropriate composition of the microbiota. It has been suggested that it may be an important therapeutic tool for modulating the response of the immune system in many inflammatory diseases, offering new treatment modalities. For this reason, its properties and role in the human body discussed in this review should be studied in more detail.

Alternative Methods of Evaluation of Antimicrobial Activity of Breast Milk Serum

Antimicrobial properties are traditionally evaluated by the seeding technique, which is laborious, time-consuming, and rather imprecise. We studied the possibility of using microscopy and spectrophotometry methods for evaluation of cytotoxic activity of breast milk serum against opportunistic microbes. Activity of 50 breast milk samples obtained from healthy women at different lactation stages was tested against opportunistic yeast C. albicans. Microscopy showed that incubation of cell suspension with lactoserum led to destruction of cell walls and cytoplasmic membranes with the formation of vesicular debris that absorbed the dye from the medium. Spectrophotometric measurement of the dye remained in the medium revealed a dose-depended effect of the lactoserum on C. albicans cells and strong inverse correlation between the lactation period and cytotoxic activity of the lactoserum (r=-0.948). These methods can be used in veterinary and food processing for estimation of biological activity of milk.

Maternal Microbiota, Early Life Colonization and Breast Milk Drive Immune Development in the Newborn

The innate immune system is the oldest protection strategy that is conserved across all organisms. Although having an unspecific action, it is the first and fastest defense mechanism against pathogens. Development of predominantly the adaptive immune system takes place after birth. However, some key components of the innate immune system evolve during the prenatal period of life, which endows the newborn with the ability to mount an immune response against pathogenic invaders directly after birth. Undoubtedly, the crosstalk between maternal immune cells, antibodies, dietary antigens, and microbial metabolites originating from the maternal microbiota are the key players in preparing the neonate’s immunity to the outer world. Birth represents the biggest substantial environmental change in life, where the newborn leaves the protective amniotic sac and is exposed for the first time to a countless variety of microbes. Colonization of all body surfaces commences, including skin, lung, and gastrointestinal tract, leading to the establishment of the commensal microbiota and the maturation of the newborn immune system, and hence lifelong health. Pregnancy, birth, and the consumption of breast milk shape the immune development in coordination with maternal and newborn microbiota. Discrepancies in these fine-tuned microbiota interactions during each developmental stage can have long-term effects on disease susceptibility, such as metabolic syndrome, childhood asthma, or autoimmune type 1 diabetes. In this review, we will give an overview of the recent studies by discussing the multifaceted emergence of the newborn innate immune development in line with the importance of maternal and early life microbiota exposure and breast milk intake.

Immunoregulatory effect of human β-defensin 1 on neonatal cord blood monocyte-derived dendritic cells and T cells

The relationship between breastfeeding and infant health has been well elucidated in past decades. Our previous study has shown that human β-defensin 1 (hBD-1) in human breast milk plays a protective role in reducing the incidence of upper respiratory infection in infants younger than 6 months. In the present study, we aim to reveal the mechanism underlying the protective role of hBD-1 by focusing on its immunoregulatory function in neonates. Cord blood (CB) from newborns' umbilical cords, which can simulate many of the neonatal symptoms, was used to study the immunomodulatory role of hBD-1 in neonates in vitro. Our results showed that hBD-1 promotes the GM-CSF- and IL-4-driven differentiation of neonatal umbilical CB monocytes to immature dendritic cells (DCs) and the final maturation of CB monocyte-derived DCs (moDCs) induced by LPS but not inflammatory cytokine production. In addition, hBD-1 inhibits apoptosis in neonatal moDCs through CCR6, which might be a possible mechanism of the hBD-1-induced phenotypes in moDCs. Furthermore, we found that hBD-1 promotes the proliferation and activation, but not the maturation, of neonatal CB CD4 + T cells. These results extend the immunoregulatory effects of hBD-1 and provide a potential mechanism for the protective role of hBD-1 in early infants, which will inform the development of infant nutrition, novel vaccines and anti-infective strategies in the future.

Innate Immunity and Breast Milk

Human milk is a dynamic source of nutrients and bioactive factors; unique in providing for the human infant's optimal growth and development. The growing infant's immune system has a number of developmental immune deficiencies placing the infant at increased risk of infection. This review focuses on how human milk directly contributes to the infant's innate immunity. Remarkable new findings clarify the multifunctional nature of human milk bioactive components. New research techniques have expanded our understanding of the potential for human milk's effect on the infant that will never be possible with milk formulas. Human milk microbiome directly shapes the infant's intestinal microbiome, while the human milk oligosaccharides drive the growth of these microbes within the gut. New techniques such as genomics, metabolomics, proteomics, and glycomics are being used to describe this symbiotic relationship. An expanded role for antimicrobial proteins/peptides within human milk in innate immune protection is described. The unique milieu of enhanced immune protection with diminished inflammation results from a complex interaction of anti-inflammatory and antioxidative factors provided by human milk to the intestine. New data support the concept of mucosal-associated lymphoid tissue and its contribution to the cellular content of human milk. Human milk stem cells (hMSCs) have recently been discovered. Their direct role in the infant for repair and regeneration is being investigated. The existence of these hMSCs could prove to be an easily harvested source of multilineage stem cells for the study of cancer and tissue regeneration. As the infant's gastrointestinal tract and immune system develop, there is a comparable transition in human milk over time to provide fewer immune factors and more calories and nutrients for growth. Each of these new findings opens the door to future studies of human milk and its effect on the innate immune system and the developing infant.

The Importance of Human Milk for Immunity in Preterm Infants

The immune system of preterm infants is immature, placing them at increased risk for serious immune-related complications. Human milk provides a variety of immune protective and immune maturation factors that are beneficial to the preterm infant's poorly developed immune system. The most studied immune components in human milk include antimicrobial proteins, maternal leukocytes, immunoglobulins, cytokines and chemokines, oligosaccharides, gangliosides, nucleotides, and long-chain polyunsaturated fatty acids. There is growing evidence that these components contribute to the lower incidence of immune-related conditions in the preterm infant. Therefore, provision of these components in human milk, donor milk, or formula may provide immunologic benefits.

Levels of innate immune factors in preterm and term mothers' breast milk during the 1st month postpartum

There is a paucity of data on the effect of preterm birth on the immunological composition of breast milk throughout the different stages of lactation. We aimed to characterise the effects of preterm birth on the levels of immune factors in milk during the 1st month postpartum, to determine whether preterm milk is deficient in antimicrobial factors. Colostrum (days 2-5 postpartum), transitional milk (days 8-12) and mature milk (days 26-30) were collected from mothers of extremely preterm (<28 weeks of gestation, n 15), very preterm (28-<32 weeks of gestation, n 15), moderately preterm (32-<37 weeks of gestation, n 15) and term infants (37-41 weeks of gestation, n 15). Total protein, lactoferrin, secretory IgA, soluble CD14 receptor (sCD14), transforming growth factor-β2 (TGF-β2), α defensin 5 (HD5), β defensins 1 (HBD1) and 2, IL-6, IL-10, IL-13, interferon-γ, TNF-α and lysozyme (LZ) were quantified in milk. We examined the effects of lactation stage, gestational age, volume of milk expressed, mode of delivery, parity and maternal infection on milk immune factor concentrations using repeated-measures regression analysis. The concentrations of all factors except LZ and HD5 decreased over the 1st month postpartum. Extremely preterm mothers had significantly higher concentrations of HBD1 and TGF-β2 in colostrum than term mothers did. After controlling for other variables in regression analyses, preterm birth was associated with higher concentrations of HBD1, LZ and sCD14 in milk samples. In conclusion, preterm breast milk contains significantly higher concentrations of some immune proteins than term breast milk.

Human milk microbiota profiles in relation to birthing method, gestation and infant gender

BACKGROUND

Human milk is an important source of bacteria for the developing infant and has been shown to influence the bacterial composition of the neonate, which in turn can affect disease risk later in life. Very little is known about what factors shape the human milk microbiome. The goal of the present study was to examine the milk microbiota from a range of women who delivered vaginally or by caesarean (C) section, who gave birth to males or females, at term or preterm.

METHODS

Milk was collected from 39 Caucasian Canadian women, and microbial profiles were analyzed by 16S ribosomal RNA (rRNA) sequencing using the Illumina platform.

RESULTS

A diverse community of milk bacteria was found with the most dominant phyla being Proteobacteria and Firmicutes and at the genus level, Staphylococcus, Pseudomonas, Streptococcus and Lactobacillus. Comparison of bacterial profiles between preterm and term births, C section (elective and non-elective) and vaginal deliveries, and male and female infants showed no statistically significant differences.

CONCLUSIONS

The study revealed the diverse bacterial types transferred to newborns. We postulate that there may be a fail-safe mechanism whereby the mother is "ready" to pass along her bacterial imprint irrespective of when and how the baby is born.

Association between Genetic Polymorphisms in DEFB1 and Susceptibility to Digestive Diseases

Background

Aberrant expression of defensins is implicated in the pathogenesis of digestive diseases. However, the contribution of specific defensins and the influence of their genetic polymorphisms on the progression of digestive diseases remain controversial. In the present meta-analysis, we investigated the association between DEFB1 SNPs and the susceptibility to digestive diseases.

Material/Methods

Case-control studies that reported the correlation between DEFB1 SNPs and the susceptibility to digestive diseases were identified through electronic databases searches, and high-quality studies that satisfied our inclusion criteria were selected for this meta-analysis. Statistical analyses were performed utilizing STATA software version 12.0.

Results

The present meta-analysis revealed that patients with digestive diseases exhibited higher frequencies of the DEFB1 genetic variants rs11362G>A, rs1800972C>G, and rs1799946G>A compared to healthy controls under the allele model. Subgroup analysis based on country showed that the rs1800972C>G variant under allele model and rs1799946G>A are associated with the susceptibility to digestive diseases in Hungarian and Italian populations, respectively. Subgroup analysis based on disease type showed that: (1) rs11362G>A variant was strongly associated with severe acute pancreatitis (SAP) and chronic gastritis, (2) frequency of rs1800972C>G variant was higher in SAP subgroup, and (3) frequency of rs1799946G>A variant was positively associated with the susceptibility to Crohn’s disease (CD) under the allele model and with SAP.

Conclusions

Our meta-analysis provides evidence that DEFB1 genetic polymorphisms rs11362G>A, rs1800972C>G and rs1799946G>A are important contributing factors to the development of digestive diseases.

Antimicrobial protein and Peptide concentrations and activity in human breast milk consumed by preterm infants at risk of late-onset neonatal sepsis

Objective

We investigated the levels and antimicrobial activity of antimicrobial proteins and peptides (AMPs) in breast milk consumed by preterm infants, and whether deficiencies of these factors were associated with late-onset neonatal sepsis (LOS), a bacterial infection that frequently occurs in preterm infants in the neonatal period.

Study design

Breast milk from mothers of preterm infants (≤32 weeks gestation) was collected on days 7 (n = 88) and 21 (n = 77) postpartum. Concentrations of lactoferrin, LL-37, beta-defensins 1 and 2, and alpha-defensin 5 were measured by enzyme-linked immunosorbent assay. The antimicrobial activity of breast milk samples against Staphylococcus epidermidis, Staphylococcus aureus, Escherichia coli, and Streptococcus agalactiae was compared to the activity of infant formula, alone or supplemented with physiological levels of AMPs. Samples of breast milk fed to infants with and without subsequent LOS were compared for levels of AMPs and inhibition of bacterial growth.

Results

Levels of most AMPs and antibacterial activity in preterm breast milk were higher at day 7 than at day 21. Lactoferrin was the only AMP that limited pathogen growth >50% when added to formula at a concentration equivalent to that present in breast milk. Levels of AMPs were similar in the breast milk fed to infants with and without LOS, however, infants who developed LOS consumed significantly less breast milk and lower doses of milk AMPs than those who were free from LOS.

Conclusions

The concentrations of lactoferrin and defensins in preterm breast milk have antimicrobial activity against common neonatal pathogens.

Airway mucosal immune-suppression in neonates of mothers receiving A(H1N1)pnd09 vaccination during pregnancy

BACKGROUND

It is recommended to vaccinate pregnant women against influenza. A possible impact on the immune expression of the fetus has never been studied. We aim to study the immune signature in the upper airways and the incidence of infections in neonates born to mothers receiving Influenza A(H1N1)pnd09 vaccination during pregnancy.

METHODS

One hundred and fifty-six women from the unselected Copenhagen Prospective Study on Asthma in Childhood (COPSAC2010) received Influenza A(H1N1)pnd09-vaccination during the 2009 pandemic. Fifty-one mothers received the vaccine during pregnancy and 105 after pregnancy; 332 neonates of nonvaccinated mothers were included as secondary controls. Nasal mucosal lining fluid was sampled in 488 neonates and assessed for interleukin (IL)-12p70, IP-10, interferon-gamma (IFN)-γ, tumor necrosis factor-alpha (TNF)-α, MIP-1β, MCP-1, MCP-4, IL-4, IL-5, IL-13, eotaxin-1, eotaxin-3, TARC, MDC, IL-17, IL-1β, IL-8, transforming growth factor beta (TGF)-β1, IL-10 and IL-2. Infections were monitored the first year of life by daily diary cards and clinical controls.

RESULTS

Neonates of mothers vaccinated during pregnancy had significant up-regulation of TGF-β1 [ratio = 1.52 (1.22-1.90), P = 0.0002], and corresponding down-regulation (P < 0.05) of IL-12p70, IFN-γ, IL-5, eotaxin-1, TARC, MDC, IL-8 in comparison to those vaccinated after pregnancy. The lag-time from vaccination during pregnancy to assessment of the immune signature showed significant and positive association to up-regulation of TGF-β1 levels (P = 0.0003) and significant negative association to other mediators. The study was not powered to study differences in the incidence of infections in early infancy which did not differ between the study groups.

CONCLUSION

Influenza A(H1N1)pnd09 vaccination during pregnancy up-regulates TGF-β1 and down-regulates key mediators of the protective immunity.

β-defensin-2 in breast milk displays a broad antimicrobial activity against pathogenic bacteria

OBJECTIVE

To describe the antimicrobial activity of β-defensin-2 produced in the mammary gland and secreted in human breast milk.

METHODS

The peptide production was performed by DNA cloning. β-defensin-2 levels were quantified in 61 colostrum samples and 39 mature milk samples from healthy donors, by an indirect enzyme-linked immunosorbent assay (ELISA). Using halo inhibition assay, this study assessed activity against seven clinical isolates from diarrheal feces of children between 0 and 2 years of age. The activity of β-defensin-2 against three opportunistic pathogens that can cause nosocomial infections was determined by microdilution test.

RESULTS

The peptide levels were higher in colostrum (n=61) than in mature milk samples (n=39), as follows: median and range, 8.52 (2.6-16.3) μg/ml versus 0.97 (0.22-3.78), p<0.0001; Mann-Whitney test. The recombinant peptide obtained showed high antimicrobial activity against a broad range of pathogenic bacteria. Its antibacterial activity was demonstrated in a disk containing between 1-4 μg, which produced inhibition zones ranging from 18 to 30 mm against three isolates of Salmonella spp. and four of E. coli. β-defensin-2 showed minimum inhibitory concentrations (MICs) of 0.25 μg/mL and 0.5 μg/mL for S. marcescen and P. aeruginosa, respectively, while a higher MIC (4 μg/mL) was obtained against an isolated of multidrug-resistant strain of A. baumannii.

CONCLUSIONS

To the authors' knowledge, this study is the first to report β-defensin-2 levels in Latin American women. The production and the activity of β-defensin-2 in breast milk prove its importance as a defense molecule for intestinal health in pediatric patients.