Changes in the Immunology of Breast Milk From Obese or Overweight Women: a Brief Review

A systematic search was carried out through search platforms and specialized databases, such as Academic Google, PubMed, and Scopus, using thesauri: breast feeding, obesity, immunology, and human milk in English and Spanish, and those articles published from January 2000 to December 2021, in both languages. Only those reports that included quantitative data on immunological components in the milk of normal-weight and overweight women were considered. The PRISMA 2020 guides were used, and a total of 306 articles were reviewed, of which a total of 33 were included, according to the basic inclusion criteria. It was observed that in obese mothers, there is an increase in certain immune cells, such as B lymphocytes, cytotoxic T lymphocytes, and NK cells, and cytokines, such as IL-6 and IFN-γ; other alterations included the bacterial population and proteins with antibacterial action. Also, a decrease in growth factors such as TGF-β and IFG-1 was documented in overweight women. Immunoglobulin concentrations did not show substantial changes. This brief review shows that maternal overweight is associated with changes in the biochemical and immunological parameters of milk.

Effect of convection and microwave heating on the retention of bioactive components in human milk

Bioactive substances are very important components of human milk (HM), especially for premature newborns. The effects of convection (CH) and microwave heating (MWH) at 62.5 and 66 °C, on the level of selected bioactive components of HM: lysozyme (LZ), lactoferrin (LF), secretory immunoglobulin A (sIgA), basal lipase (BL), cytokine TGF-2, vitamin C and total antioxidant capacity (TAC) was compared. Regardless of the used heating methods the TAC of HM, determined by TEAC and ORAC-FL assay, proved to be insensitive to temperature pasteurization, in contrary to BL. MWH in the conditions of 62.5 for 5 min and 66 °C for 3 min are ensuring microbiological safety with a higher retention of most of the tested active HM proteins compared to CH. Only in the case of LZ the MWH had a more degradative effect on its concentration. Controlled conditions of MWH preserve the bioactive components of the HM better than CH.

The Effect of Prolonged Freezing and Holder Pasteurization on the Macronutrient and Bioactive Protein Compositions of Human Milk

Introduction: Human donor milk is widely used to feed premature and sick newborns when the milk of their own mothers is insufficient. All treatment processes involving human milk affect its composition. The aim of this study was to assess changes in the macronutrients and bioactive protein (lactoferrin and lysozyme) content in human milk caused by freezing and Holder pasteurization. Materials and Methods: Milk samples were collected from 42 mothers 14-16 days after delivery. Each sample was divided into two parts and tested twice for macronutrient content, once upon being freshly collected and again after freezing at -40°C, thawing and Holder pasteurization. The lysozyme and lactoferrin concentrations were first determined in the unpasteurized thawed human milk after it was stored frozen at -80°C for up to 10 months and again after Holder pasteurization. The macronutrient concentrations were determined by midinfrared spectrophotometry, and enzyme-linked immunosorbent assay was used to measure the lysozyme and lactoferrin concentrations. Results: Freezing and Holder pasteurization had no significant effects on the macronutrient concentrations. The mean lactoferrin content before and after pasteurization was 2.5 ± 1.07 and 0.03 ± 0.03 mg/mL, respectively (p < 0.001), and the lysozyme content was 19.57 ± 20.11 and 12.62 ± 14.14 μg/mL, respectively (p = 0.007). Conclusions: Freezing and Holder pasteurization did not decrease the nutritional value of human milk but caused considerable loss of lactoferrin and lysozyme. New methods for treating human milk are needed that ensure the destruction of pathogenic microorganisms while retaining the biological and nutritional value of the milk. The Clinical Trial Registration number: NCT04382989.

Impact of Holder pasteurization on immunological properties of human breast milk over the first year of lactation

BACKGROUND

The timing of milk donations to human milk banks ranges from a few days to more than 1 year after delivery, and the Holder method is used for pasteurization. We evaluated the effect of temporal variation and thermal treatment on the immunological properties of milk.

METHODS

We analyzed 73 milk samples, raw and after pasteurization, donated at different lactation stages. We studied antibodies, lysozyme, cytokines, soluble receptors, and factors with impact on barrier function. We also evaluated in vitro the capacity of milk to modulate nuclear factor-κB (NF-κB) signaling in an HT-29 epithelial cell line stimulated with tumor necrosis factor-α (TNF-α).

RESULTS

With few exceptions, immune components exhibited their highest levels in colostrum, and were stable in the various stages of mature milk. Pasteurization altered the immunological composition of milk, and very drastically for some components. Raw milk of the first year reduced NF-κB activation in HT-29 cells treated with TNF-α to approximately the same extent, and Holder pasteurization significantly affected this capacity.

CONCLUSIONS

Overall, the present work reports that mature donated milk is equally valuable over the first year of lactation, but warns about drastic losses of anti-inflammatory properties during Holder pasteurization that could be critical for the health of preterm infants.

Variability of lysozyme and lactoferrin bioactive protein concentrations in equine milk in relation to LYZ and LTF gene polymorphisms and expression

BACKGROUND

Equine milk is considered to be an interesting product for human nutrition, mainly owing to its low allergenicity and significant amounts of bioactive proteins, including lysozyme (LYZ) and lactoferrin (LTF). The present study assessed the effect of genetic factors on LYZ and LTF concentration variability in mare's milk.

RESULTS

Significant effects of horse breed and lactation stage on milk LYZ and LTF contents were observed. The highest level of LTF and the lowest concentration of LYZ were recorded for the Polish Warmblood Horse breed. The highest amounts of both proteins were found for the earliest investigated time point of lactation (5th week). Altogether 13 (nine novel) polymorphisms were found in the 5'-flanking regions of both genes, but they showed no significant relationship with milk LYZ and LTF contents. Several associations were found between selected SNPs and the LYZ gene relative transcript level.

CONCLUSION

While the present study indicated the existence of intra- and interbreed variability of LYZ and LTF contents in mare's milk, this variation is rather unrelated to the 5'-flanking variants of genes encoding both proteins. This study is a good introduction for broader investigations focused on the genetic background for variability of bioactive protein contents in mare's milk. © 2016 Society of Chemical Industry.

Longitudinal evolution of true protein, amino acids and bioactive proteins in breast milk: a developmental perspective

The protein content of breast milk provides a foundation for estimating protein requirements of infants. Because it serves as a guideline for regulatory agencies issuing regulations for infant formula composition, it is critical that information on the protein content of breast milk is reliable. We have therefore carried out a meta-analysis of the protein and amino acid contents of breast milk and how they evolve during lactation. As several bioactive proteins are not completely digested in the infant and therefore represent "non-utilizable" protein, we evaluated the quantity, mechanism of action and digestive fate of several major breast milk proteins. A better knowledge of the development of the protein contents of breast milk and to what extent protein utilization changes with age of the infant will help improve understanding of protein needs in infancy. It is also essential when designing the composition of infant formulas, particularly when the formula uses a "staging" approach in which the composition of the formula is modified in stages to reflect changes in breast milk and changing requirements as the infant ages.

The chemical composition of human milk from Inner Mongolia of China

In Inner Mongolia, China, the chemical composition of 66 breast milk samples at three lactation stages was analysed. Except for total nitrogen content, the contents of total solid, fat, NPN, lactose and ash were not significantly different between colostral, transitional and mature milk. Fatty acids did not vary over the three lactation stages, while unsaturated fatty acids accounted for 59.95-63.22% of the total fatty acids. Relatively low contents of vitamins were in the milk because the volunteer mothers did not take any vitamin supplementation over the entire lactation period. Besides sodium and phosphate, the concentrations of most minerals in the breast milk remained fairly constant across the three lactation stages.

A multinational study of alpha-lactalbumin concentrations in human milk

Alpha-lactalbumin, a 14-kD protein, plays a central biochemical role in the mammary gland as the regulatory subunit of lactose synthase, and also plays a nutritional role for the rapidly growing neonate as the protein in highest concentration in human milk. The current study was undertaken to better characterize alpha-lactalbumin concentrations in human milk from a variety of countries. Mature human milk (lactation duration > or =1 month) was collected from at least 50 women from nine different countries on five continents. Alpha-lactalbumin concentration was determined by HPLC. The mean +/- SD for 452 samples was 2.44 +/- 0.64 g/L. The mean value of the samples from the United States was significantly higher than that from any other country, and the mean in Mexico was significantly lower than that from every country except China and Canada. Alpha-lactalbumin concentration decreased with increasing duration of lactation and was positively correlated with total nitrogen. On average, alpha-lactalbumin contributed 16% of the total nitrogen content of human milk and consequently an important part of the amino acid content.

Changes in the mannan binding lectin (MBL) concentration in human milk during lactation

The mannan binding lectin (MBL) activates the complement system by the lectin pathway after the recognition of some structural motifs (saccharides) present on the surface of microorganisms. MBL has been mostly identified and quantified in human serum by ELISA or microparticle immunonephelometry assays. This article reports the MBL levels as assessed by a microparticle immunonephelometric assay in 76 human milk samples. Immunonephelometry was performed using skim-milk samples diluted 20 times over a calibration range of 0.07-4.82 mg/L. MBL is indeed present in human milk and its concentration decreases significantly during development from colostrum (0.55+/-0.09 mg/L) to transitional (0.18+/-0.02 mg/L) and mature milk (0.17+/-0.02 mg/L). This innate molecule may be involved in the primary defenses of the mammary gland and the neonate, whose immune system is immature. The high levels observed during the first days of lactation support the hypothesis that this molecule plays a key role in limiting the colonization of the newborn gut by pathogens.