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

Chronological changes of serum exosome in preterm infants: A prospective study

BACKGROUND

Exosomes, which are observed in all human fluid, including serum, are nanosized extracellular vesicles with a mechanism of intercellular communication. Potential clinical applications of exosomes in neonatal diseases have recently been discussed. However, the characteristics of exosomes in serum during early infancy is unclear.

METHODS

In this prospective study, we evaluated the chronological changes in the concentration of serum-derived exosomes of 20 infants for 12 months after birth.

RESULTS

The average concentration of serum-derived exosomes was 4.6 × 10¹⁰ particles/mL at birth and increased significantly until the age of 48 weeks. There was a moderate correlation between the gestational age and the concentration of serum-derived exosomes both at birth (r = 0.54, P = 0.01) and during the 8 weeks after birth (r = 0.48, P < 0.001). A multivariable analysis showed that gestational age at birth was associated with the concentration of serum-derived exosomes at birth (partial regression coefficient, 0.86; 95% confidence interval, 0.37-1.37; P = 0.002).

CONCLUSIONS

The concentration of serum-derived exosomes in preterm infants increased both chronologically and by gestational age after birth. These basic data may help to further understand physiology of exosomes in preterm infants.

Highest concentration of breast-milk-derived exosomes in colostrum

BACKGROUND

Exosomes are nanosized extracellular vesicles, that play important roles in intercellular immune regulation. They have potential therapeutic utility for neonatal diseases including necrotizing enterocolitis. Breast-milk-derived exosomes have recently shown beneficial effects on intestinal damage in vitro and in vivo. However, the chronological change in breast-milk-derived exosome concentrations after delivery are unclear.

METHODS

In this prospective study, we enrolled 17 mothers who delivered premature infants admitted to a neonatal intensive care unit in Japan. We measured the consecutive concentrations of breast-milk-derived exosomes in the mothers for 48 weeks after delivery.

RESULTS

The median concentration of breast-milk-derived exosomes was 1.62 × 10⁸ particles/ml in colostrum, showing a significant decrease after 2 weeks (P < 0.01). There was no association between the exosome concentration in colostrum and maternal perinatal factors including parity, mode of delivery, maternal age, and gestational age at delivery.

CONCLUSIONS

We concluded that breast-milk-derived exosomes were the richest in colostrum. Our basic data regarding breast-milk-derived exosomes are expected to aid in the clinical application of exosomes for treating neonatal diseases.

Amniotic fluid stem cells: A novel treatment for necrotizing enterocolitis

Necrotizing enterocolitis (NEC) is a gastrointestinal disease frequently prevalent in premature neonates. Despite advances in research, there is a lack of accurate, early diagnoses of NEC and the current therapeutic approaches remain exhausted and disappointing. In this review, we have taken a close look at the regenerative medical literature available in the context of NEC treatment. Stem cells from amniotic fluid (AFSC) administration may have the greatest protective and restorative effects on NEC. This review summarizes the potential protection and restoration AFSCs have on NEC-induced intestinal injury while comparing various components within AFSCs like conditioned medium (CM) and extracellular vesicles (EVs). In addition to therapeutic interventions that focus on targeting intestinal epithelial damage and regeneration, a novel discovery that AFSCs act in a Wnt-dependent manner provides insight into this mechanism of protection. Finally, we have highlighted the most important aspects that remain unknown that should be considered to guide future research on the translational application of AFSC-based therapy. We hope that this will be a beneficial frame of reference for the guidance of future studies and towards the clinical application of AFSC and/or its derivatives as a treatment against NEC.

The Impact of MicroRNAs in Neonatal Necrotizing Enterocolitis and other Inflammatory Conditions of Intestine: A Review

The understanding of necrotizing enterocolitis (NEC) etiopathogenesis is incomplete, contributing to the lack of early biomarkers and therapeutic options. Micro RNAs (miRNAs) are a class of RNAs that can alter gene expression and modulate various physiological and pathological processes. Several studies have been performed to evaluate the role of miRNA in the pathogenesis of NEC. In this article, we review the information on miRNAs that have been specifically identified in NEC or have been noted in other inflammatory bowel disorders that share some of the histopathological abnormalities seen frequently in NEC. This review highlights miRNAs that could be useful as early biomarkers of NEC and suggests possible approaches for future translational studies focused on these analytes. It is a novel field with potential for immense translational and clinical relevance in preventing, detecting, or treating NEC in very premature infants. Impact • Current information categorizes necrotizing enterocolitis (NEC) as a multifactorial disease, but microRNAs (miRNAs) may influence the risk of occurrence of NEC. • MiRNAs may alter the severity of the intestinal injury and the clinical outcome of NEC. • The literature on intestinal diseases of adults suggests additional miRNAs that have not been studied in NEC yet but share some features and deserve further exploration in human NEC, especially if affecting gut dysbiosis, intestinal perfusion, and coagulation disorders.

Extracellular Vesicles in Human Milk

Milk supports the growth and development of infants. An increasing number of mostly recent studies have demonstrated that milk contains a hitherto undescribed component called extracellular vesicles (EVs). This presents questions regarding why milk contains EVs and what their function is. Recently, we showed that EVs in human milk expose tissue factor, the protein that triggers coagulation or blood clotting, and that milk-derived EVs promote coagulation. Because bovine milk, which also contains EVs, completely lacks this coagulant activity, important differences are present in the biological functions of human milk-derived EVs between species. In this review, we will summarize the current knowledge regarding the presence and biochemical composition of milk EVs, their function(s) and potential clinical applications such as in probiotics, and the unique problems that milk EVs encounter in vivo, including survival of the gastrointestinal conditions encountered in the newborn. The main focus of this review will be human milk-derived EVs, but when available, we will also include information regarding non-human milk for comparison.

The therapeutic triad of extracellular vesicles: As drug targets, as drugs, and as drug carriers

Rapidly growing interest in the study of extracellular vesicles (EVs) has led to the accumulation of evidence on their critical roles in various pathologies, as well as opportunities to design novel therapeutic EV-based applications. Efficiently exploiting the constantly expanding knowledge of the biology and function of EVs requires a deep understanding of the various possible strategies of using EVs for therapeutic purposes. Accordingly, in the present work, we have narrowed the broad therapeutic potential of EVs and consider the similarities and differences of various strategies as we articulate three major aspects (i.e., a triad) of their therapeutic uses: (i) EVs as drug targets, whereby we discuss therapeutic targeting of disease-promoting EVs; (ii) EVs as drugs, whereby we consider the natural medicinal properties of EVs and the available options for their optimization; and (iii) EVs as drug carriers, whereby we highlight the advantages of EVs as vehicles for efficacious drug delivery of natural compounds. Finally, after conducting a comprehensive review of the latest literature on each of these aspects, we outline opportunities, limitations, and potential solutions.

A complete proteomic profile of human and bovine milk exosomes by liquid chromatography mass spectrometry

BACKGROUND

The present study investigates the proteomic content of milk-derived exosomes. A detailed description of the content of milk exosomes is essential to improve our understanding of the various components of milk and their role in nutrition.

METHODS

The exosomes used in this study were isolated as previously described and characterized by their morphology, particle concentration, and the presence of exosomal markers. Human and bovine milk exosomes were evaluated using Information-Dependent Acquisition (IDA) Mass Spectrometry. A direct comparison is made between their proteomic profiles.

RESULTS

IDA analyses revealed similarities and differences in protein content. About 229 and 239 proteins were identified in the human and bovine milk exosome proteome, respectively, of which 176 and 186 were unique to each species. Fifty-three proteins were common in both groups. These included proteins associated with specific biological processes and molecular functions. Most notably, the 4 abundant milk proteins lactadherin, butyrophilin, perilipin-2, and xanthine dehydrogenase/oxidase were present in the top 20 list for both human and bovine milk exosomes.

CONCLUSION

The milk exosome protein profiles we have provided are crucial new information for the field of infant nutrition. They provide new insight into the components of milk from both humans and bovines.

Mucin 1 and interleukin-11 protein expression and inflammatory reactions in the intestinal mucosa of necrotizing enterocolitis children after surgery

BACKGROUND

Necrotizing enterocolitis (NEC) of the newborn is a frequently occurring clinical disease in infants. The mortality rate of NEC in premature infants is as high as 50%, and the morbidity rate is on the rise. NEC has already caused serious impacts on newborn survival and poses serious threats to both children and families.

AIM

To investigate the expression and significance of mucin 1 (MUC1) and interleukin-11 (IL-11) in the intestinal mucosa of infants with neonatal NEC after surgery.

METHODS

Forty-eight postoperative intestinal mucosal specimens from children with NEC (NEC group) and twenty-two intestinal mucosal specimens from children with congenital intestinal atresia (control group) were collected in our hospital. Immunohistochemical staining and Western blot analysis were used to examine the protein expression of MUC-1 and IL-11 in the two groups. The serum levels of tumor necrosis factor-α (TNF-α) and IL-1β in the two groups were measured by enzyme-linked immunosorbent assay, and the relationship between MUC-1 and IL-11 protein expression and serum TNF-α and IL-1β levels was analyzed by the linear correlation method.

RESULTS

The protein expression of MUC-1 and IL-11 in the NEC group was significantly lower than that in the control group, and the difference was statistically significant (P < 0.05). The levels of serum TNF-α and IL-1β in the NEC group were significantly higher than those in the control group (P < 0.05). The protein expression of MUC-1 and IL-11 in the NEC group negatively correlated with serum TNF-α and IL-1β levels (P < 0.05). There was a significant negative correlation between the protein expression of MUC-1 and IL-11 and the levels of serum TNF-α and IL-1β in the NEC group.

CONCLUSION

The protein expression of MUC1 and IL-11 in the intestinal mucosa of children with NEC is significantly downregulated after surgery. This downregulation may be involved in the pathogenesis of this disease and has a certain correlation with inflammatory response factors in children with NEC.

Malnutrition, poor post-natal growth, intestinal dysbiosis and the developing lung

In extremely preterm infants, poor post-natal growth, intestinal dysbiosis and bronchopulmonary dysplasia are common, and each is associated with long-term complications. The central hypothesis that this review will address is that these three common conditions are interrelated. Challenges to studying this hypothesis include the understanding that malnutrition and poor post-natal growth are not synonymous and that there is not agreement on what constitutes a normal intestinal microbiota in this evolutionarily new population. If this hypothesis is supported, further study of whether "correcting" intestinal dysbiosis in extremely preterm infants reduces postnatal growth restriction and/or bronchopulmonary dysplasia is indicated.

Ruminant Milk-Derived Extracellular Vesicles: A Nutritional and Therapeutic Opportunity?

Milk has been shown to contain a specific fraction of extracellular particles that are reported to resist digestion and are purposefully packaged with lipids, proteins, and nucleic acids to exert specific biological effects. These findings suggest that these particles may have a role in the quality of infant nutrition, particularly in the early phase of life when many of the foundations of an infant's potential for health and overall wellness are established. However, much of the current research focuses on human or cow milk only, and there is a knowledge gap in how milk from other species, which may be more commonly consumed in different regions, could also have these reported biological effects. Our review provides a summary of the studies into the extracellular particle fraction of milk from a wider range of ruminants and pseudo-ruminants, focusing on how this fraction is isolated and characterised, the stability and uptake of the fraction, and the reported biological effects of these fractions in a range of model systems. As the individual composition of milk from different species is known to differ, we propose that the extracellular particle fraction of milk from non-traditional and minority species may also have important and distinct biological properties that warrant further study.

Branched-chain fatty acids in the vernix caseosa and meconium of infants born at different gestational ages

The functional lipid components found in breast milk, vernix caseosa, and meconium are Branched-chain Fatty Acids (BCFA). The goal of this study was to establish the existence of BCFA in vernix and meconium in infants born at different gestational ages. TLC plates and GC-MS were examined for the lipids in vernix caseosa and meconium. The results indicated that there were nine BCFA in vernix caseosa, including iso-12:0, anteiso-13:0, iso-14:0, iso-15:0, anteiso-15:0, iso-16:0, anteiso-17:0, iso-18:0, and iso-20:0. Five BCFA (iso-12:0, anteiso-13:0, iso-14:0, iso-15:0, and anteiso-15:0) were not contained in the meconium, suggesting that some of the BCFA may be digested and consumed by infants. In the vernix caseosa, the content of BCFA in triacylglycerol (TAG) and free fatty acid (FFA) was 15.59% and 11.82%, respectively. The vernix caseosa's wax ester fraction contained the highest content of BCFA, reaching up to 16.81%. The carbon chain length of fatty acids (FA) ranged from 12 to 24 in the vernix caseosa and 14 to 22 in meconium samples. The gestational age was likely to affect BCFA concentrations, with the vernix caseosa and meconium BCFA content being significantly higher in full-term infants than in preterm infants (p < .001). Further research is required into the relationship between BCFA and gut microbiotas.

Biological Properties of Milk-Derived Extracellular Vesicles and Their Physiological Functions in Infant

Extracellular vesicles (EVs) are released by all cells under pathological and physiological conditions. EVs harbor various biomolecules, including protein, lipid, non-coding RNA, messenger RNA, and DNA. In 2007, mRNA and microRNA (miRNA) carried by EVs were found to have regulatory functions in recipient cells. The biological function of EVs has since then increasingly drawn interest. Breast milk, as the most important nutritional source for infants, contains EVs in large quantities. An increasing number of studies have provided the basis for the hypothesis associated with information transmission between mothers and infants via breast milk-derived EVs. Most studies on milk-derived EVs currently focus on miRNAs. Milk-derived EVs contain diverse miRNAs, which remain stable both in vivo and in vitro; as such, they can be absorbed across different species. Further studies have confirmed that miRNAs derived from milk-derived EVs can resist the acidic environment and enzymatic hydrolysis of the digestive tract; moreover, they can be absorbed by intestinal cells in infants to perform physiological functions. miRNAs derived from milk EVs have been reported in the maturation of immune cells, regulation of immune response, formation of neuronal synapses, and development of metabolic diseases such as obesity and diabetes. This article reviews current status and advances in milk-derived EVs, including their history, biogenesis, molecular contents, and biological functions. The effects of milk-derived EVs on growth and development in both infants and adults were emphasized. Finally, the potential application and future challenges of milk-derived EVs were discussed, providing comprehensive understanding and new insight into milk-derived EVs.

Exosome-Derived MicroRNAs of Human Milk and Their Effects on Infant Health and Development

Multiple biologically active components of human milk support infant growth, health and development. Milk provides a wide spectrum of mammary epithelial cell-derived extracellular vesicles (MEVs) for the infant. Although the whole spectrum of MEVs appears to be of functional importance for the growing infant, the majority of recent studies report on the MEV subfraction of milk exosomes (MEX) and their miRNA cargo, which are in the focus of this review. MEX and the dominant miRNA-148a play a key role in intestinal maturation, barrier function and suppression of nuclear factor-κB (NF-κB) signaling and may thus be helpful for the prevention and treatment of necrotizing enterocolitis. MEX and their miRNAs reach the systemic circulation and may impact epigenetic programming of various organs including the liver, thymus, brain, pancreatic islets, beige, brown and white adipose tissue as well as bones. Translational evidence indicates that MEX and their miRNAs control the expression of global cellular regulators such as DNA methyltransferase 1-which is important for the up-regulation of developmental genes including insulin, insulin-like growth factor-1, α-synuclein and forkhead box P3-and receptor-interacting protein 140, which is important for the regulation of multiple nuclear receptors. MEX-derived miRNA-148a and miRNA-30b may stimulate the expression of uncoupling protein 1, the key inducer of thermogenesis converting white into beige/brown adipose tissue. MEX have to be considered as signalosomes derived from the maternal lactation genome emitted to promote growth, maturation, immunological and metabolic programming of the offspring. Deeper insights into milk's molecular biology allow the conclusion that infants are both "breast-fed" and "breast-programmed". In this regard, MEX miRNA-deficient artificial formula is not an adequate substitute for breastfeeding, the birthright of all mammals.

Stem cells and exosomes: promising candidates for necrotizing enterocolitis therapy

Necrotizing enterocolitis (NEC) is a devastating disease predominately affecting neonates. Despite therapeutic advances, NEC remains the leading cause of mortality due to gastrointestinal conditions in neonates. Stem cells have been exploited in various diseases, and the application of different types of stem cells in the NEC therapy is explored in the past decade. However, stem cell transplantation possesses several deficiencies, and exosomes are considered potent alternatives. Exosomes, especially those derived from stem cells and breast milk, demonstrate beneficial effects for NEC both in vivo and in vitro and emerge as promising options for clinical practice. In this review, the function and therapeutic effects of stem cells and exosomes for NEC are investigated and summarized, which provide insights for the development and application of novel therapeutic strategies in pediatric diseases. Further elucidation of mechanisms, improvement in preparation, bioengineering, and administration, as well as rigorous clinical trials are warranted.

Review of Methodological Approaches to Human Milk Small Extracellular Vesicle Proteomics

Proteomics can map extracellular vesicles (EVs), including exosomes, across disease states between organisms and cell types. Due to the diverse origin and cargo of EVs, tailoring methodological and analytical techniques can support the reproducibility of results. Proteomics scans are sensitive to in-sample contaminants, which can be retained during EV isolation procedures. Contaminants can also arise from the biological origin of exosomes, such as the lipid-rich environment in human milk. Human milk (HM) EVs and exosomes are emerging as a research interest in health and disease, though the experimental characterization and functional assays remain varied. Past studies of HM EV proteomes have used data-dependent acquisition methods for protein detection, however, improvements in data independent acquisition could allow for previously undetected EV proteins to be identified by mass spectrometry. Depending on the research question, only a specific population of proteins can be compared and measured using isotope and other labelling techniques. In this review, we summarize published HM EV proteomics protocols and suggest a methodological workflow with the end-goal of effective and reproducible analysis of human milk EV proteomes.

Porcine Milk-Derived Small Extracellular Vesicles Promote Intestinal Immunoglobulin Production through pIgR

Simple Summary

As the irreplaceable nutrient source for young mammals, milk has a number of biological functions. Milk derived extracellular vesicles are a recently discovered component of milk and have potential regulatory effects on intestinal health and immunity. In this study, in vivo and in vitro experiments were performed to examine the effects of porcine milk small extracellular vesicles (PM-sEVs) on intestinal immunity. As a result, PM-sEVs promoted intestinal secretory immunoglobulin A (SIgA) levels, and increased the expression levels of the polymeric immunoglobulin receptor (pIgR) both in mice and piglet. We identified circ-XPO4 in PM-sEVs as a crucial circRNA, which promotes the expression of pIgR via the suppression of miR-221-5p in the intestinal cell. In conclusion, our research provides a new understanding of the nutritional physiology of porcine milk in intestinal immunity.

Abstract

Secretory immunoglobulin A (SIgA) plays an important role in gut acquired immunity and mucosal homeostasis. Breast milk is the irreplaceable nutritional source for mammals after birth. Current studies have shown the potential functional role of milk-derived small extracellular vesicles (sEVs) and their RNAs cargo in intestinal health and immune regulation. However, there is a lack of studies to demonstrate how milk-derived sEVs affect intestinal immunity in recipient. In this study, through in vivo experiments, we found that porcine milk small extracellular vesicles (PM-sEVs) promoted intestinal SIgA levels, and increased the expression levels of polymeric immunoglobulin receptor (pIgR) both in mice and piglet. We examined the mechanism of how PM-sEVs increased the expression level of pIgR in vitro by using a porcine small intestine epithelial cell line (IPEC-J2). Through bioinformatics analysis, dual-luciferase reporter assays, and overexpression or knockdown of the corresponding non-coding RNAs, we identified circ-XPO4 in PM-sEVs as a crucial circRNA, which leads to the expression of pIgR via the suppression of miR-221-5p in intestinal cells. Importantly, we also observed that oral administration of PM-sEVs increased the level of circ-XPO4 and decreased the level of miR-221-5p in small intestine of piglets, indicating that circRNAs in milk-derived sEVs act as sponge for miRNAs in recipients. This study, for the first time, reveals that PM-sEVs have a capacity to stimulate intestinal SIgA production by delivering circRNAs to receptors and sponging the recipient’s original miRNAs, and also provides valuable data for insight into the role and mechanism of animal milk sEVs in intestinal immunity.

Enteral Feeding Interventions in the Prevention of Necrotizing Enterocolitis: A Systematic Review of Experimental and Clinical Studies

Necrotizing enterocolitis (NEC), which is characterized by severe intestinal inflammation and in advanced stages necrosis, is a gastrointestinal emergency in the neonate with high mortality and morbidity. Despite advancing medical care, effective prevention strategies remain sparse. Factors contributing to the complex pathogenesis of NEC include immaturity of the intestinal immune defense, barrier function, motility and local circulatory regulation and abnormal microbial colonization. Interestingly, enteral feeding is regarded as an important modifiable factor influencing NEC pathogenesis. Moreover, breast milk, which forms the currently most effective prevention strategy, contains many bioactive components that are known to support neonatal immune development and promote healthy gut colonization. This systematic review describes the effect of different enteral feeding interventions on the prevention of NEC incidence and severity and the effect on pathophysiological mechanisms of NEC, in both experimental NEC models and clinical NEC. Besides, pathophysiological mechanisms involved in human NEC development are briefly described to give context for the findings of altered pathophysiological mechanisms of NEC by enteral feeding interventions.

Yak milk-derived exosomes alleviate lipopolysaccharide-induced intestinal inflammation by inhibiting PI3K/AKT/C3 pathway activation

Intestinal epithelial cells (IEC) are important parts of the mucosal barrier, whose function can be impaired upon various injury factors such as lipopolysaccharide. Although food-derived exosomes are preventable against intestinal barrier injuries, there have been few studies on the effect of yak milk-derived exosomes and the underlying mechanism that remains poorly understood. This study aimed to characterize the effect of exosomal proteins derived from yak and cow milk on the barrier function of IEC-6 treated with lipopolysaccharide and the relevant mechanism involved. Proteomics study revealed 392 differentially expressed proteins, with 58 higher expressed and 334 lower expressed in yak milk-derived exosomes than those in cow exosomes. Additionally, the top 20 proteins with a relatively consistent higher expression in yak milk exosomes than cow milk exosomes were identified. Protein CD46 was found to be a regulator for alleviating inflammatory injury of IEC-6. In vitro assay of the role of yak milk exosomes on survival of IEC-6 in inflammation by 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyl tetrazolium bromide assay confirmed the effectiveness of yak milk exosomes to increase IEC-6 survival up to 18% for 12 h compared with cow milk exosomes (up to 12%), indicating a therapeutic effect of yak milk exosomes in the prevention of intestinal inflammation. Furthermore, yak and cow milk exosomes were shown to activate the PI3K/AKT/C3 signaling pathway, thus promoting IEC-6 survival. Our findings demonstrated an important relationship between yak and cow milk exosomes and intestinal inflammation, facilitating further understanding of the mechanisms of inflammation-driven epithelial homeostasis. Interestingly, compared with cow milk exosomes, yak milk exosomes activated the PI3K/AKT/C3 signaling pathway more to lower the incidence and severity of intestine inflammation, which might represent a potential innovative therapeutic option for intestinal inflammation.

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.

Breast milk stem cells: Are they magic bullets in neonatology?

Each mammal produces milk specific to its newborn that meets all nutritional needs. Breast milk is not only a secretory product but is also a complex liquid containing several components that provide enteral nutrition. The stage of lactation, the fullness of the breast, the feeding of the baby, and the health of the mother during the breastfeeding period cause differences in the composition of breast milk. Although the positive effects of breast milk on the physical and intellectual development of a child in the short and long term have been known for centuries, its mechanism has not been elucidated. Stem cells are defined as the cells that possess specific markers and have not undergone differentiation. Under suitable conditions and stimuli, they can differentiate into desired cells. The detection of stem cells, whose exact origin is not known, in breast milk and their demonstration in the baby's body have prompted the necessity of exploring the possible role of stem cells in the treatment of diseases. In this review, breast milk-derived stem cells and their possible role in neonatology are discussed.

A Simple and Quick Method for Loading Proteins in Extracellular Vesicles

Extracellular vesicles (EVs) mediate intercellular transport of biomolecular cargo in the body, making them promising delivery vehicles for bioactive compounds. Genetic engineering of producer cells has enabled encapsulation of therapeutic proteins in EVs. However, genetic engineering approaches can be expensive, time-consuming, and incompatible with certain EV sources, such as human plasma and bovine milk. The goal of this study was to develop a quick, versatile, and simple method for loading proteins in EVs post-isolation. Proteins, including CRISPR associated protein 9 (Cas9), were bound to cationic lipids that were further complexed with MDA-MB-231 cell-derived EVs through passive incubation. Size-exclusion chromatography was used to remove components that were not complexed with EVs. The ability of EVs to mediate intracellular delivery of proteins was compared to conventional methods, such as electroporation and commercial protein transfection reagents. The results indicate that EVs retain native features following protein-loading and obtain similar levels of intracellular protein delivery as conventional methods, but display less toxicity. This method opens up opportunities for rapid exploration of EVs for protein delivery.

Lactobacillus reuteri in its biofilm state promotes neurodevelopment after experimental necrotizing enterocolitis in rats

Necrotizing enterocolitis (NEC) is a devastating disease affecting premature newborns with no known cure. Up to half of survivors subsequently exhibit cognitive impairment and neurodevelopmental defects. We created a novel probiotics delivery system in which the probiotic Lactobacillus reuteri (Lr) was induced to form a biofilm [Lr (biofilm)] by incubation with dextranomer microspheres loaded with maltose (Lr-DM-maltose). We have previously demonstrated that a single dose of the probiotic Lr administered in its biofilm state significantly reduces the incidence of NEC and decreases inflammatory cytokine production in an animal model of the disease. The aim of our current study was to determine whether a single dose of the probiotic Lr administered in its biofilm state protects the brain after experimental NEC. We found that rat pups exposed to NEC reached developmental milestones significantly slower than breast fed pups, with mild improvement with Lr (biofilm) treatment. Exposure to NEC had a negative effect on cognitive behavior, which was prevented by Lr (biofilm) treatment. Lr administration also reduced anxiety-like behavior in NEC-exposed rats. The behavioral effects of NEC were associated with increased numbers of activated microglia, decreased myelin basic protein (MBP), and decreased neurotrophic gene expression, which were prevented by administration of Lr (biofilm). Our data indicate early enteral treatment with Lr in its biofilm state prevented the deleterious effects of NEC on developmental impairments.

•

Early treatment with Lr in its biofilm state improves cognitive function in pups that survive experimental NEC.

•

Lr in its biofilm state reduces microglia activation and MBP loss, and maintains memory and learning-related gene expression.

•

Administration of Lr in its biofilm state protects the brain, as well as intestines, during experimental NEC.

Comparison of isolation methods using commercially available kits for obtaining extracellular vesicles from cow milk

Extracellular vesicles (EV) are important for delivering biologically active substances to facilitate cell-to-cell communication. Milk-derived EV are widely known because of their potential for immune enhancement. However, procedures for isolating milk-derived EV have not been fully established. To obtain pure milk-derived EV and accurately reveal their function, such procedures must be established. The aim of the present study was to compare methods using commercially available kits for isolating milk-derived EV. Initially, we investigated procedures to remove casein, which is the major obstacle in determining milk-derived EV purity. We separated whey using centrifugation only, acetic acid precipitation, and EDTA precipitation. Then, we isolated milk-derived EV by ultracentrifugation, membrane affinity column, size exclusion chromatography (SEC), polymer-based isolation, or phosphatidylserine-affinity isolation. Using EV count per milligram of protein, which is a good indicator of purity, we determined that acetic acid precipitation was the best method for removing casein. Using nanoparticle tracking analysis, protein quantity analysis, and RNA quantity analysis, we comprehensively compared each isolation method for its purity and yield. We found that SEC-based qEV column (Izon Science) could collect purer milk-derived EV at higher quantities. Thus, a combination of acetic acid precipitation and qEV can effectively isolate high amounts of pure extracellular vesicles from bovine milk.

The Gut‒Breast Axis: Programming Health for Life

The gut is a pivotal organ in health and disease. The events that take place in the gut during early life contribute to the programming, shaping and tuning of distant organs, having lifelong consequences. In this context, the maternal gut plays a quintessence in programming the mammary gland to face the nutritional, microbiological, immunological, and neuroendocrine requirements of the growing infant. Subsequently, human colostrum and milk provides the infant with an impressive array of nutrients and bioactive components, including microbes, immune cells, and stem cells. Therefore, the axis linking the maternal gut, the breast, and the infant gut seems crucial for a correct infant growth and development. The aim of this article is not to perform a systematic review of the human milk components but to provide an insight of their extremely complex interactions, which render human milk a unique functional food and explain why this biological fluid still truly remains as a scientific enigma.

Intestinal Stem Cell Development in the Neonatal Gut: Pathways Regulating Development and Relevance to Necrotizing Enterocolitis

The intestine is extremely dynamic and the epithelial cells that line the intestine get replaced every 3–5 days by highly proliferative intestinal stem cells (ISCs). The instructions for ISCs to self-renew or to differentiate come as cues from their surrounding microenvironment or their niche. A small number of evolutionarily conserved signaling pathways act as a critical regulator of the stem cells in the adult intestine, and these pathways are well characterized. However, the mechanisms, nutritional, and environmental signals that help establish the stem cell niche in the neonatal intestine are less studied. Deciphering the key signaling pathways that regulate the development and maintenance of the stem cells is particularly important to understanding how the intestine regenerates from necrotizing enterocolitis, a devastating disease in newborn infants characterized by inflammation, tissues necrosis, and stem cell injury. In this review, we piece together current knowledge on morphogenetic and immune pathways that regulate intestinal stem cell in neonates and highlight how the cross talk among these pathways affect tissue regeneration. We further discuss how these key pathways are perturbed in NEC and review the scientific knowledge relating to options for stem cell therapy in NEC gleaned from pre-clinical experimental models of NEC.

Effects of Holder Pasteurization on Immune Composition of Human Milk

Background: Human milk (HM) is the ideal food for newborn (NB) nutrition, it provides all macro and micronutrients for human growth and development and also contains bioactive compounds, which influence the development of the neonatal digestive and immune systems. The holder pasteurization process is essential to prevent NB infection from donated milk. Therefore, the aim of this study was to check whether or not holder pasteurization could impact the concentration of immune components in HM and the capacity to induce epithelial cell growth. Materials and Methods: The study was performed on raw and holder pasteurized (62.5°C/30 minutes) paired milk samples after submission to the freezing process in both phases. For cytokine and adipokine measurements, ELISA was performed on 40 individual samples of HM from single donors. For analyzes of epithelial cell growth, HuTu-80 cells were cultivated in Minimum Essential Eagle medium with 15% of raw or pasteurized milk, eight pairs of milk were used. Results: The results showed that no alteration was observed in the concentration of cytokine after milk holder pasteurization, and leptin concentration was reduced in holder pasteurized milk. The heat treatment also did not impact the capacity of breast milk to promote intestinal epithelial cell growth. Conclusions: The results showed that donated breast milk pasteurization has a small impact on the HM bioactive concentration compounds. This technique is important to avoid NB infection.

Recent Advances in Experimental Models of Breast Cancer Exosome Secretion, Characterization and Function

Breast cancer (BC) is responsible for 15% of all the cancer deaths among women in the USA. The tumor microenvironment (TME) has the potential to act as a driver of breast cancer progression and metastasis. The TME is composed of stromal cells within an extracellular matrix and soluble cytokines, chemokines and extracellular vesicles and nanoparticles that actively influence cell behavior. Extracellular vesicles include exosomes, microvesicles and large oncosomes that orchestrate fundamental processes during tumor progression through direct interaction with target cells. Long before tumor cell spread to future metastatic sites, tumor-secreted exosomes enter the circulation and establish distant pre-metastatic niches, hospitable and permissive milieus for metastatic colonization. Emerging evidence suggests that breast cancer exosomes promote tumor progression and metastasis by inducing vascular leakiness, angiogenesis, invasion, immunomodulation and chemoresistance. Exosomes are found in almost all physiological fluids including plasma, urine, saliva, and breast milk, providing a valuable resource for the development of non-invasive cancer biomarkers. Here, we review work on the role of exosomes in breast cancer progression and metastasis, and describe the most recent advances in models of exosome secretion, isolation, characterization and functional analysis. We highlight the potential applications of plasma-derived exosomes as predictive biomarkers for breast cancer diagnosis, prognosis and therapy monitoring. We finally describe the therapeutic approaches of exosomes in breast cancer.

The emerging role of exosomes in the pathogenesis, prognosis and treatment of necrotizing enterocolitis

Exosomes are a subtype of extracellular vesicles. They contain bioactive molecules, including nucleic acids, proteins and lipids. Among the currently described exosomes, a majority are potential candidates for the diagnosis and treatment of necrotizing enterocolitis (NEC). In this work, we reviewed existing literature reports on exosomes and explored their roles in NEC. Exosomes derived from intestinal epithelial cells (IECs) participates in the development of intestinal diseases, thus can potentially be utilized as biomarkers for NEC. Besides, exosomes of human milk have been demonstrated to protect IECs from oxidative stress, stimulate intestinal stem cells activity, improve the proliferation and migration of IECs, and lower the incidence and severity of experimental NEC. Further, exosomes produced by stem cells can reduce the severity of experimental NEC and protect the intestinal barrier function during NEC. Conclusively, exosomes have been shown to influence the pathogenesis of NEC and exert a protective effect on NEC. However, additional investigations would be urgently necessary to comprehensively elucidate the underlying mechanisms of exosomes in NEC.

Biological Characteristics and Roles of Noncoding RNAs in Milk-Derived Extracellular Vesicles

Extracellular vesicles (EVs) have diverse roles in the transport of proteins, lipids, and nucleic acids between cells, and they serve as mediators of intercellular communication. Noncoding RNAs (ncRNAs) that are present in EVs, including microRNAs, long noncoding RNAs, and circular RNAs, have been found to participate in complex networks of interactions and regulate a wide variety of genes in animals. Milk is an important source of nutrition for humans and other mammals. Evidence suggests that milk-derived EVs contain abundant ncRNAs, which are stable and can be transported to the offspring and other consumers. Current data suggest a strong link between milk EV ncRNAs and many biological processes, and these ncRNAs have been drawing increasing attention and might play an epigenetic regulatory role in recipients, though further research is still necessary to understand their precise roles. The present review introduces basic information about milk EV ncRNAs, summarizes their expression profiles, biological characteristics, and functions based on current knowledge, and discusses their biological roles, indeterminate issues, and perspectives. Our goal is to provide a deeper understanding of the physiological effects of milk EV ncRNAs on offspring and to provide a reference for future research in this field.

Circulating microRNAs in Breast Milk and Their Potential Impact on the Infant

MicroRNAs (MiRNAs) are small RNA molecules that can exert regulatory functions in gene expression. MiRNAs have been identified in diverse tissues and biological fluids, both in the context of health and disease. Breastfeeding has been widely recognized for its superior nutritional benefits; however, a number of bioactive compounds have been found to transcend these well-documented nutritional contributions. Breast milk was identified as a rich source of miRNAs. There has been increasing interest about their potential ability to transfer to the offspring as well as what their specific involvement is within the benefits of breast milk in the infant. In comparison to breast milk, formula milk lacks many of the benefits of breastfeeding, which is thought to be a result of the absence of some of these bioactive compounds. In recent years, the miRNA profile of breast milk has been widely studied, along with the possible transfer mechanisms throughout the infant's digestive tract and the role of miRNA-modulated genes and their potential protective and regulatory functions. Nonetheless, to date, the current evidence is not consistent, as many methodological limitations have been identified; hence, discrepancies exits about the biological functions of miRNAs. Further research is needed to provide thorough knowledge in this field.

Precision-based modeling approaches for necrotizing enterocolitis

Necrotizing enterocolitis (NEC) is the leading cause of death from gastrointestinal disease in premature infants and remains stubbornly difficult to treat in many cases. Much of our understanding of NEC pathogenesis has been gained through the study of highly translational animal models. However, most models of NEC are limited by their overall complexity and by the fact that they do not incorporate human tissue. To address these limitations, investigators have recently developed precision-based ex vivo models of NEC, also termed 'NEC-in-a-dish' models, which provide the opportunity to increase our understanding of this disease and for drug discovery. These approaches involve exposing intestinal cells from either humans or animals with or without NEC to a combination of environmental and microbial factors associated with NEC pathogenesis. This Review highlights the current progress in the field of NEC model development, introduces NEC-in-a-dish models as a means to understand NEC pathogenesis and examines the fundamental questions that remain unanswered in NEC research. By answering these questions, and through a renewed focus on precision model development, the research community may finally achieve enduring success in improving the outcome of patients with this devastating disease.

Developmental 2,3,7,8-tetrachlorodibenzo-p-dioxin exposure of either parent enhances the risk of necrotizing enterocolitis in neonatal mice

BACKGROUND

Necrotizing enterocolitis (NEC) is a rare, but potentially fatal intestinal inflammatory condition most often arising in premature infants. Infants provided formula are also at greater risk of developing this disease. Although the majority of formula-fed, preterm infants do not develop NEC, up to 30% of infants with the disease do not survive. Thus, identifying additional, currently unrecognized factors, which may predispose a specific infant to NEC development would be a significant clinical advancement. In this regard, we have previously reported that offspring of female or male mice with a history of developmental exposure to the environmental toxicant 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) exhibit altered sensitivity to inflammatory challenges and are frequently born premature. Herein, we examined the possibility that, compared to unexposed mice (F1_NONE ), developmental TCDD exposure of either parent (maternal, F1M_TCDD , or paternal, F1P_TCDD ) would enhance the risk of NEC in offspring (F2_TCDD mice) in association with supplemental formula feeding.

METHODS

Beginning on postnatal day 7, all neonates were randomized to maternal milk only or maternal milk with up to 20 supplemental formula feedings. All pups remained with the Dams and were additionally allowed to nurse ad libitum.

RESULTS

Formula-fed F2_NONE pups rarely developed NEC while this disease was common in formula-fed F2M_TCDD and F2P_TCDD mice. Unexpectedly, 50% of F2M_TCDD pups that were not provided supplemental formula also developed NEC.

CONCLUSIONS

Our studies provide evidence that a history of parental TCDD exposure enhances the risk of NEC in offspring and suggest exposure to environmental immunotoxicants such as TCDD may also contribute to this inflammatory disease in humans.

Milk Exosomes Prevent Intestinal Inflammation in a Genetic Mouse Model of Ulcerative Colitis: A Pilot Experiment

Background

Milk is rich in nutrients and anabolic mediators rendering it essential for postnatal growth and metabolic programming. However, in adults, excessive consumption of milk is controversial as civilization disorders such as diabetes or prostate cancer may be promoted. A cytoprotective effect of milk could be utilized in inflammatory conditions, that is, chronic colitis.

Objective

To evaluate the effect of bovine milk exosomes on intestinal inflammation in a genetic mouse model of ulcerative colitis.

Methods

Intestinal-specific kindlin 2 knockout (KO) mice were exposed for 4 days to tamoxifen for induction of an ulcerative colitis phenotype. At the same time 4 other kindlin 2 KO mice were exposed to 33 μg/g cow milk derived exosomes in PBS by oral gavage. Both groups were compared to untreated wild-type controls.

Results

Milk exosomes prevented the appearance of a severe ulcerative phenotype. The macroscopic colitis score dropped from a mean of 3.33 in untreated mice to 0.75 index points (p < 0.01) in exosome-treated mice, which included significant improvement of the subscores of stool improvement and colon weight and length. Treated mice featured a noninflamed appearance of the intestinal mucosa.

Key Message

Milk exosomes have cytoprotective/anti-inflammatory activity in a genetic mouse model of ulcerative colitis. The mechanisms behind this need to be elucidated. This pilot study needs verification before a therapeutic strategy is developed.

The Therapeutic Potential of Breast Milk-Derived Extracellular Vesicles

In the past few decades, interest in the therapeutic benefits of exosomes and extracellular vesicles (EVs) has grown exponentially. Exosomes/EVs are small particles which are produced and exocytosed by cells throughout the body. They are loaded with active regulatory and stimulatory molecules from the parent cell including miRNAs and enzymes, making them prime targets in therapeutics and diagnostics. Breast milk, known for years to have beneficial health effects, contains a population of EVs which may mediate its therapeutic effects. This review offers an update on the therapeutic potential of exosomes/EVs in disease, with a focus on EVs present in human breast milk and their remedial effect in the gastrointestinal disease necrotizing enterocolitis. Additionally, the relationship between EV miRNAs, health, and disease will be examined, along with the potential for EVs and their miRNAs to be engineered for targeted treatments.

de la Fuente J, Moros M. Nanoparticle-based biosensors for detection of extracellular vesicles in liquid biopsies

Selecting the appropriate nanoparticle, functionalization chemistry and sensing methodology can speed up the translation of liquid biopsies into the clinic.