Milk exosomes: beyond dietary microRNAs

Bovine milk consumption affects the transcriptome of porcine adipose stem cells: Do exosomes play any role?

The potential association of milk with childhood obesity has been widely debated and researched. Milk is known to contain many bioactive compounds as well as bovine exosomes rich in micro-RNA (miR) that can have effects on various cells, including stem cells. Among them, adipose stem cells (ASC) are particularly interesting due to their role in adipose tissue growth and, thus, obesity. The objective of this study was to evaluate the effect of milk consumption on miR present in circulating exosomes and the transcriptome of ASC in piglets. Piglets were supplemented for 11 weeks with 750 mL of whole milk (n = 6; M) or an isocaloric maltodextrin solution (n = 6; C). After euthanasia, ASC were isolated, quantified, and characterized. RNA was extracted from passage 1 ASC and sequenced. Exosomes were isolated and quantified from the milk and plasma of the pigs at 6-8 hours after milk consumption, and miRs were isolated from exosomes and sequenced. The transfer of exosomes from milk to porcine plasma was assessed by measuring bovine milk-specific miRs and mRNA in exosomes isolated from the plasma of 3 piglets during the first 6h after milk consumption. We observed a higher proportion of exosomes in the 80 nM diameter, enriched in milk, in M vs. C pigs. Over 500 genes were differentially expressed (DEG) in ASC isolated from M vs. C pigs. Bioinformatic analysis of DEG indicated an inhibition of the immune, neuronal, and endocrine systems and insulin-related pathways in ASC of milk-fed pigs compared with maltodextrin-fed pigs. Of the 900 identified miRs in porcine plasma exosomes, only 3 miRs were differentially abundant between the two groups and could target genes associated with neuronal functions. We could not detect exosomal miRs or mRNA transfer from milk to porcine-circulating plasma exosomes. Our data highlights the significant nutrigenomic role of milk consumption on ASC, a finding that does not appear to be attributed to miRs in bovine milk exosomes. The downregulation of insulin resistance and inflammatory-related pathways in the ASC of milk-fed pigs should be further explored in relation to milk and human health. In conclusion, the bioinformatic analyses and the absence of bovine exosomal miRs in porcine plasma suggest that miRs are not vertically transferred from milk exosomes.

Milk-derived exosomes in the regulation of nutritional and immune functions

Milk-derived exosomes (MDEs), being a component of milk, have the potential to support immune system maturation in offspring and enhance immune cell proliferation. Through the transport and transmission of essential signaling molecules, MDEs contribute to the regulation of intergenerational and intraspecies communication, thereby impacting nutrient uptake and metabolic functions. A comprehensive comprehension of MDE functionalities is imperative for enhancing the quality of the dairy industry. A systematic search of the databases PubMed/Medline, Web of Science, and Scopus utilizing predetermined keywords resulted in the identification of 418 articles, of which 67 were chosen for inclusion in this review, which specifically explores the intersection of immune response and nutrition. This article provides a critical analysis of the classification of extracellular vesicles, the mechanisms underlying the biosynthesis of microvesicular dietary exosomes (MDEs), the components of MDEs, and their relevance in the contexts of nutrition and immune modulation. The primary aim of this review was to offer valuable scholarly insights to support the advancement and practical application of MDEs.

Role of MicroRNAs in Dietary Interventions for Obesity and Obesity-Related Diseases

Obesity and related metabolic syndromes pose a serious threat to human health and quality of life. A proper diet is a safe and effective strategy to prevent and control obesity, thus maintaining overall health. However, no consensus exists on the connotations of proper diet, and it is attributed to various factors, including "nutritional dark matter" and the "matrix effect" of food. Accumulating evidence confirms that obesity is associated with the in vivo levels of miRNAs, which serve as potential markers and regulatory targets for obesity onset and progression; food-derived miRNAs can regulate host obesity by targeting the related genes or gut microbiota across the animal kingdom. Host miRNAs mediate food nutrient-gut microbiota-obesity interactions. Thus, miRNAs are important correlates of diet and obesity onset. This review outlines the recent findings on miRNA-mediated food interventions for obesity, thereby elucidating their potential applications. Overall, we provide new perspectives and views on the evaluation of dietary nutrition, which may bear important implications for dietary control and obesity prevention.

Extracellular Vesicles from Animal Milk: Great Potentialities and Critical Issues

Other than representing the main source of nutrition for newborn mammals, milk delivers a sophisticated signaling system from mother to child that promotes postnatal health. The bioactive components transferred through the milk intake are important for the development of the newborn immune system and include oligosaccharides, lactoferrin, lysozyme, α-La, and immunoglobulins. In the last 15 years, a pivotal role in this mother-to-child exchange has been attributed to extracellular vesicles (EVs). EVs are micro- and nanosized structures enclosed in a phospholipidic double-layer membrane that are produced by all cell types and released in the extracellular environment, reaching both close and distant cells. EVs mediate the intercellular cross-talk from the producing to the receiving cell through the transfer of molecules contained within them such as proteins, antigens, lipids, metabolites, RNAs, and DNA fragments. The complex cargo can induce a wide range of functional modulations in the recipient cell (i.e., anti-inflammatory, immunomodulating, angiogenetic, and pro-regenerative modulations) depending on the type of producing cells and the stimuli that these cells receive. EVs can be recovered from every biological fluid, including blood, urine, bronchoalveolar lavage fluid, saliva, bile, and milk, which is one of the most promising scalable vesicle sources. This review aimed to present the state-of-the-art of animal-milk-derived EV (mEV) studies due to the exponential growth of this field. A focus on the beneficial potentialities for human health and the issues of studying vesicles from milk, particularly for the analytical methodologies applied, is reported.

Theragnostic Applications of Mammal and Plant-Derived Extracellular Vesicles: Latest Findings, Current Technologies, and Prospects

The way cells communicate is not fully understood. However, it is well-known that extracellular vesicles (EVs) are involved. Researchers initially thought that EVs were used by cells to remove cellular waste. It is now clear that EVs function as signaling molecules released by cells to communicate with one another, carrying a cargo representing the mother cell. Furthermore, these EVs can be found in all biological fluids, making them the perfect non-invasive diagnostic tool, as their cargo causes functional changes in the cells upon receiving, unlike synthetic drug carriers. EVs last longer in circulation and instigate minor immune responses, making them the perfect drug carrier. This review sheds light on the latest development in EVs isolation, characterization and, application as therapeutic cargo, novel drug loading techniques, and diagnostic tools. We also address the advancement in plant-derived EVs, their characteristics, and applications; since plant-derived EVs only recently gained focus, we listed the latest findings. Although there is much more to learn about, EV is a wide field of research; what scientists have discovered so far is fascinating. This paper is suitable for those new to the field seeking to understand EVs and those already familiar with it but wanting to review the latest findings.

Recent Advances on the Function and Purification of Milk Exosomes: A Review

Exosomes are nano-scale extracellular vesicles, which can be used as drug carriers, tumor treatment, intestinal development and immune regulator. That is why it has great potential in pharmacy, functional foods, nutritional supplements, especially those for infants, postoperative patients, chemotherapy patients and the elderly. In addition, abnormal exosome level is also related to diseases such as cardiovascular diseases, tumor, diabetes, neurodegenerative and autoimmune diseases, as well as infectious diseases. Despite its high biological significance, pharmaceutical and nutritional value, the low abundancy of exosomes in milk is one of the bottlenecks restricting its in-depth research and real-life application. At present, there is no unified standard for the extraction of breast milk exosomes. Therefore, choosing the proper extraction method is very critical for its subsequent research and development. Based on this, this paper reviewed the purification techniques, the function and the possible applications of milk exosomes based on 47 latest references. Humble advices on future directions, prospects on new ideas and methods which are useful for the study of exosomes are proposed at the end of the paper as well.

A novel concept of human antiviral protection: It's all about RNA (Review)

The comparative analysis of the antiviral protective mechanisms, including protozoa and RNA interference in multicellular organisms, has revealed their similarity and provided a basic understanding of adaptive immunity. The present article summarizes the latest studies on RNA-guided gene regulation in human antiviral protection, and its importance. Additionally, the role of both neutralizing antibodies and the interferon system in viral invasion is considered. The interferon system is an additional mechanism for suppressing viral infections in humans, which shifts cells into an 'alarm' mode to attempt to prevent further contagion. The primary task of the human central immune system is to maintain integrity and to protect against foreign organisms. In this review, a novel concept is proposed: Antiviral protection in all organisms can be achieved through an intracellular RNA-guided mechanism. A simple and effective defence against viruses is incorporation of a part of a virus's DNA (spacer) into the hosts chromosomes. Following reinfection, RNA transcripts of this spacer are created to direct nuclease enzymes to destroy the viral genome. This is an example of real-time adaptive immunity potentially possessed by every cell with a full complement of chromosomes, and an indicator that antiviral immunity is not only mediated by the presence of neutralizing antibodies and memory B- and T-cells, but also by the presence of specific spacers in the DNA of individuals who have recovered from a viral infection.

Transcriptomic Characterization of Cow, Donkey and Goat Milk Extracellular Vesicles Reveals Their Anti-Inflammatory and Immunomodulatory Potential

Milk extracellular vesicles (mEVs) seem to be one of the main maternal messages delivery systems. Extracellular vesicles (EVs) are micro/nano-sized membrane-bound structures enclosing signaling molecules and thus acting as signal mediators between distant cells and/or tissues, exerting biological effects such as immune modulation and pro-regenerative activity. Milk is also a unique, scalable, and reliable source of EVs. Our aim was to characterize the RNA content of cow, donkey, and goat mEVs through transcriptomic analysis of mRNA and small RNA libraries. Over 10,000 transcripts and 2000 small RNAs were expressed in mEVs of each species. Among the most represented transcripts, 110 mRNAs were common between the species with cow acting as the most divergent. The most represented small RNA class was miRNA in all the species, with 10 shared miRNAs having high impact on the immune regulatory function. Functional analysis for the most abundant mRNAs shows epigenetic functions such as histone modification, telomere maintenance, and chromatin remodeling for cow; lipid catabolism, oxidative stress, and vitamin metabolism for donkey; and terms related to chemokine receptor interaction, leukocytes migration, and transcriptional regulation in response to stress for goat. For miRNA targets, shared terms emerged as the main functions for all the species: immunity modulation, protein synthesis, cellular cycle regulation, transmembrane exchanges, and ion channels. Moreover, donkey and goat showed additional terms related to epigenetic modification and DNA maintenance. Our results showed a potential mEVs immune regulatory purpose through their RNA cargo, although in vivo validation studies are necessary.

Milk Exosome-Derived MicroRNA-2478 Suppresses Melanogenesis through the Akt-GSK3β Pathway

Exosomes participate in intercellular communication by transferring molecules from donor to recipient cells. Exosomes are found in various body fluids, including blood, urine, cerebrospinal fluid and milk. Milk exosomes contain many endogenous microRNA molecules. MicroRNAs are small noncoding RNAs and have important roles in biological processes. The specific biological functions of milk exosomes are not well understood. In this study, we investigated the effects of milk exosomes on melanin production in melanoma cells and melanocytes. We found that milk exosomes decreased melanin contents, tyrosinase activity and the expression of melanogenesis-related genes in melanoma cells and melanocytes. Bovine-specific miR-2478 in exosomes inhibited melanin production. We found that Rap1a is a direct target gene of miR-2478 in melanoma cells and melanocytes. MiR-2478 overexpression decreased Rap1a expression, which led to downregulated melanin production and expression of melanogenesis-related genes. Inhibition of Rap1a expression decreased melanogenesis through the Akt-GSK3β signal pathway. These results support the role of miR-2478 derived from milk exosomes as a regulator of melanogenesis through direct targeting of Rap1a. These results show that milk exosomes could be useful cosmeceutical ingredients to improve whitening.

Cross-kingdom regulation by dietary plant miRNAs: an evidence-based review with recent updates

As non-coding RNA molecules, microRNAs (miRNAs) are widely known for their critical role in gene regulation. Recent studies have shown that plant miRNAs obtained through dietary oral administration can survive in the gastrointestinal (GI) tract, enter the circulatory system and regulate endogenous mRNAs. Diet-derived plant miRNAs have 2'-O-methylated modified 3'ends and high cytosine and guanine (GC) content, as well as exosomal packaging, which gives them high stability even in the harsh environment of the digestive system and circulatory system. The latest evidence shows that dietary plant miRNAs can not only be absorbed in the intestine, but also be absorbed and packaged by gastric epithelial cells and then secreted into the circulatory system. Alternatively, these biologically active plant-derived miRNAs may also affect the health of the host by affecting the function of the microbiome, while not need to be taken into the host's circulatory system and transferred to remote tissues. This cross-kingdom regulation of miRNAs gives us hope for exploring their therapeutic potential and as dietary supplements. However, doubts have also been raised about the cross-border regulation of miRNAs, suggesting that technical flaws in the experiments may have led to this hypothesis. In this article, we summarize the visibility of dietary plant miRNAs in the development of human health and recent research data on their use in therapeutics. The regulation of plant miRNAs across kingdoms is a novel concept. Continued efforts in this area will broaden our understanding of the biological role of plant miRNAs and will open the way for the development of new approaches to prevent or treat human diseases.

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.

Cow's milk may be delivering potentially harmful undetected cargoes to humans. Is it time to reconsider dairy recommendations?

Mammalian evolution has shaped milk into a species-specific vehicle for post-natal development, continuing what began within the mother's womb. Increased consumption of the mother's breast milk is associated with the most adequate metabolic programming and lowers the incidence of the diseases of civilization during adulthood. An abundance of short sequences of RNA, known as microRNA, exists in mammalian breast milk, enclosed within robust small extracellular vesicles known as exosomes. These microRNAs can epigenetically regulate over 60% of human genes. When cow's milk is consumed by humans, the bovine exosomes are transported through the gastrointestinal tract, detected intact in the blood stream, and taken up by target cells, where they alter protein expression. The aim of this review was to highlight the role of dairy exosomes and microRNA, and of the type of dairy product consumed, in human diseases. Given that microRNAs are involved in a vast array of physiological processes and associated with several diseases, perhaps caution should be practiced with regard to human consumption of dairy, particularly for individuals within developmentally critical time frames, such as pregnant and lactating mothers, and young children.

Comparative proteome profiling in exosomes derived from porcine colostrum versus mature milk reveals distinct functional proteomes

Exosomes are membranous vesicles of endocytic origin, recently been considered as major players in cell-cell communication. Milk is highly complex, and diverse biocomponents provide adequate nutrition, transfer immunity, and promote adequate neonate development. Milk exosomes are suggested to have a key role in these processes, yet to be further explored, and the alteration of the exosomes' cargo in different stages of lactation stages is important for understanding the factors relevant in nursing and also for improving milk replacer products both for humans and animals. We isolated exosomes from porcine milk in different lactation stages and analyzed their content using a TMT-based high-resolution quantitative proteomic approach. Exosomes were isolated using ultracentrifugation coupled with size exclusion chromatography to enrich milk-derived exosomes in samples obtained at day 0, 7, and 14 after parturition, and characterized by nanoparticle tracking analysis, transmission electron microscopy, and Western blotting. Quantitative proteomics analysis revealed different proteome profiles for colostrum exosomes and milk exosomes. The functional analysis highlighted pathways related to the regulation of homeostasis to be upregulated in colostrum exosomes, and pathways such as endothelial cell development and lipid metabolism to be upregulated in mature milk exosomes. This study endorses the importance of exosomes as active biocomponents of milk and provides knowledge for future studies exploring their role in the regulation of immunity and growth of the newborn. SIGNIFICANCE: The identified functional proteome and protein-protein interaction networks identified in our study help to elucidate the role of milk exosomes in different lactation periods. The results generated herein are of relevance for the basic understanding of their impact on the infant's development but also for bringing forward the manufacturing of milk replacers.

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.

Oral administration of bovine milk-derived extracellular vesicles induces senescence in the primary tumor but accelerates cancer metastasis

The concept that extracellular vesicles (EVs) from the diet can be absorbed by the intestinal tract of the consuming organism, be bioavailable in various organs, and in-turn exert phenotypic changes is highly debatable. Here, we isolate EVs from both raw and commercial bovine milk and characterize them by electron microscopy, nanoparticle tracking analysis, western blotting, quantitative proteomics and small RNA sequencing analysis. Orally administered bovine milk-derived EVs survive the harsh degrading conditions of the gut, in mice, and is subsequently detected in multiple organs. Milk-derived EVs orally administered to mice implanted with colorectal and breast cancer cells reduce the primary tumor burden. Intriguingly, despite the reduction in primary tumor growth, milk-derived EVs accelerate metastasis in breast and pancreatic cancer mouse models. Proteomic and biochemical analysis reveal the induction of senescence and epithelial-to-mesenchymal transition in cancer cells upon treatment with milk-derived EVs. Timing of EV administration is critical as oral administration after resection of the primary tumor reverses the pro-metastatic effects of milk-derived EVs in breast cancer models. Taken together, our study provides context-based and opposing roles of milk-derived EVs as metastasis inducers and suppressors.

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.

Perspective: Milk microRNAs as Important Players in Infant Physiology and Development

Evolutionary selective pressure on lactation has resulted in milk that provides far more than simply essential nutrients, delivering a complex repertoire of agents from hormones to intact cells. Human infants are born with low barrier integrity of their gut, which means that many of the complex biopolymer components of milk enter and circulate in lymph and blood, reaching organs throughout the body. Due to this state of gut maturation, all components of milk are potentially part of the crosstalk between mother and infants. This article highlights the functions of milk's complex biopolymers, more specifically the potential role of microRNAs (miRNAs) contained in extracellular vesicles in human milk. miRNAs are key effectors in the regulation of many biological processes during early-age development, and consequently milk-sourced miRNAs must be considered to provide unique biological assets to the infant during breastfeeding. This article interprets the evidence of the potential action of human milk miRNAs on infant development, taking into account their abundance in milk based on the literature and current knowledge. Human milk miRNAs appear to influence lipid and glucose metabolism, gut maturation, neurogenesis, and immunity. We also show growing evidence that human milk miRNAs are epigenetic modulators that play a pivotal role in the regulation of tissue-specific gene expression throughout life. Furthermore, this article addresses the ongoing debate regarding the potential influence of human milk miRNAs on viral infection as a new research area. This article highlights that these bioactive molecules are now being incorporated into our overall understanding of nutrient needs for healthy infant development, preparing each individual infant to succeed as a healthy and protected adult throughout its life. In essence, miRNAs are a new language in the Rosetta stone of health that is mammalian lactation.

Plant-derived xenomiRs and cancer: Cross-kingdom gene regulation

Exosomal microRNAs (miRNAs) critically regulate several major intracellular and metabolic activities, including cancer evolution. Currently, increasing evidence indicates that exosome harbor and transport these miRNAs from donor cells to neighboring and distantly related recipient cells, often in a cross-species manner. Several studies have reported that plant-based miRNAs can be absorbed into the serum of humans, where they hinder the expression of human disease-related genes. Moreover, few recent studies have demonstrated the role of these xenomiRs in cancer development and progression. However, the cross-kingdom gene regulation hypothesis remains highly debatable, and many follow up studies fail to reproduce the same. There are reports that show no effect of plant-derived miRNAs on mammalian cancers. The foremost cause of this controversy remains the lack of reproducibility of the results. Here, we reassess the latest developments in the field of cross-kingdom transference of miRNAs, emphasizing on the role of the diet-based xenomiRs on cancer progression.

Ancient Evolutionary Origin and Properties of Universally Produced Natural Exosomes Contribute to Their Therapeutic Superiority Compared to Artificial Nanoparticles

Extracellular vesicles (EVs), such as exosomes, are newly recognized fundamental, universally produced natural nanoparticles of life that are seemingly involved in all biologic processes and clinical diseases. Due to their universal involvements, understanding the nature and also the potential therapeutic uses of these nanovesicles requires innovative experimental approaches in virtually every field. Of the EV group, exosome nanovesicles and larger companion micro vesicles can mediate completely new biologic and clinical processes dependent on the intercellular transfer of proteins and most importantly selected RNAs, particularly miRNAs between donor and targeted cells to elicit epigenetic alterations inducing functional cellular changes. These recipient acceptor cells are nearby (paracrine transfers) or far away after distribution via the circulation (endocrine transfers). The major properties of such vesicles seem to have been conserved over eons, suggesting that they may have ancient evolutionary origins arising perhaps even before cells in the primordial soup from which life evolved. Their potential ancient evolutionary attributes may be responsible for the ability of some modern-day exosomes to withstand unusually harsh conditions, perhaps due to unique membrane lipid compositions. This is exemplified by ability of the maternal milk exosomes to survive passing the neonatal acid/enzyme rich stomach. It is postulated that this resistance also applies to their durable presence in phagolysosomes, thus suggesting a unique intracellular release of their contained miRNAs. A major discussed issue is the generally poorly realized superiority of these naturally evolved nanovesicles for therapies when compared to human-engineered artificial nanoparticles, e.g., for the treatment of diseases like cancers.

MILK Symposium review: The importance of milk and dairy foods in the diets of infants, adolescents, pregnant women, adults, and the elderly

The ongoing increase in life expectancy is not always accompanied by an increase in healthy life span. There is increasing evidence that dietary exposure in early life can substantially affect chronic disease risk in later life. Milk and dairy foods are important suppliers of a range of key nutrients, with some being particularly important at certain life stages. It is now recognized that milk protein can stimulate insulin-like growth factor-1 (IGF-1), essential for longitudinal bone growth and bone mass acquisition in young children, thus reducing the risk of stunting. Low milk consumption during adolescence, particularly by girls, may contribute to suboptimal intake of calcium, magnesium, iodine, and other important nutrients. Given the generally low vitamin D status of European populations, this may have already affected bone development, and any resulting reduced bone strength may become a big issue when the populations are much older. Suboptimal iodine status of many young women has already been reported together with several observational studies showing an association between suboptimal iodine status during pregnancy and reduced cognitive development in the offspring. There is now good evidence that consumption of milk and dairy foods does not lead to an increased risk of cardiovascular diseases and type 2 diabetes. Indeed, some negative associations are seen, notably between yogurt consumption and type 2 diabetes, which should be researched with urgency. Greater emphasis should be placed on reducing malnutrition in the elderly and on dietary approaches to reduce their loss of muscle mass, muscle functionality, and bone strength. Whey protein has been shown to be particularly effective for reducing muscle loss; this needs to be developed to provide simple dietary regimens for the elderly to follow. There is an ongoing, often too simplistic debate about the relative value of animal versus plant food sources for protein in particular. It is important that judgments on the replacement of dairy products with those from plants also include the evidence on relative functionality, which is not expressed in simple nutrient content (e.g., hypotensive and muscle synthesis stimulation effects). Only by considering such functionality will a true comparison be achieved.

Casein-enhanced uptake and disease-modifying bioactivity of ingested extracellular vesicles

Extracellular vesicles (EVs) from cardiac stromal cells, developed as therapeutic candidates, improve dystrophic muscle function when administered parenterally, but oral delivery remains untested. We find that casein, the dominant protein in breast milk, enhances the uptake and bioactivity of ingested heart-derived EVs, altering gene expression in blood cells and enhancing muscle function in mdx mice with muscular dystrophy. Thus, EVs, administered orally, are absorbed and exert disease-modifying bioactivity in vivo. Formulating EVs with casein enhances uptake and markedly expands the range of potential therapeutic applications.

I. A, Elbehi AM, Cash E, Adeyeye A. The Impact of Diet on the Involvement of Non-Coding RNAs, Extracellular Vesicles, and Gut Microbiome-Virome in Colorectal Cancer Initiation and Progression

Cancer is the major cause of morbidity and mortality in the world today. The third most common cancer and which is most diet related is colorectal cancer (CRC). Although there is complexity and limited understanding in the link between diet and CRC, the advancement in research methods have demonstrated the involvement of non-coding RNAs (ncRNAs) as key regulators of gene expression. MicroRNAs (miRNAs) which are a class of ncRNAs are key players in cancer related pathways in the context of dietary modulation. The involvement of ncRNA in cancer progression has recently been clarified throughout the last decade. ncRNAs are involved in biological processes relating to tumor onset and progression. The advances in research have given insights into cell to cell communication, by highlighting the pivotal involvement of extracellular vesicle (EV) associated-ncRNAs in tumorigenesis. The abundance and stability of EV associated ncRNAs act as a new diagnostic and therapeutic target for cancer. The understanding of the deranging of these molecules in cancer can give access to modulating the expression of the ncRNAs, thereby influencing the cancer phenotype. Food derived exosomes/vesicles (FDE) are gaining interest in the implication of exosomes in cell-cell communication with little or no understanding to date on the role FDE plays. There are resident microbiota in the colon; to which the imbalance in the normal intestinal occurrence leads to chronic inflammation and the production of carcinogenic metabolites that lead to neoplasm. Limited studies have shown the implication of various types of microbiome in CRC incidence, without particular emphasis on fungi and protozoa. This review discusses important dietary factors in relation to the expression of EV-associated ncRNAs in CRC, the impact of diet on the colon ecosystem with particular emphasis on molecular mechanisms of interactions in the ecosystem, the influence of homeostasis regulators such as glutathione, and its conjugating enzyme-glutathione S-transferase (GST) polymorphism on intestinal ecosystem, oxidative stress response, and its relationship to DNA adduct fighting enzyme-0-6-methylguanine-DNA methyltransferase. The understanding of the molecular mechanisms and interaction in the intestinal ecosystem will inform on the diagnostic, preventive and prognosis as well as treatment of CRC.

Anti-Inflammatory Potential of Cow, Donkey and Goat Milk Extracellular Vesicles as Revealed by Metabolomic Profile

In recent years, extracellular vesicles (EVs), cell-derived micro and nano-sized structures enclosed in a double-layer membrane, have been in the spotlight for their high potential in diagnostic and therapeutic applications. Indeed, they act as signal mediators between cells and/or tissues through different mechanisms involving their complex cargo and exert a number of biological effects depending upon EVs subtype and cell source. Being produced by almost all cell types, they are found in every biological fluid including milk. Milk EVs (MEVs) can enter the intestinal cells by endocytosis and protect their labile cargos against harsh conditions in the intestinal tract. In this study, we performed a metabolomic analysis of MEVs, from three different species (i.e., bovine, goat and donkey) by mass spectroscopy (MS) coupled with Ultrahigh-performance liquid chromatography (UHPLC). Metabolites, both common or specific of a species, were identified and enriched metabolic pathways were investigated, with the final aim to evaluate their anti-inflammatory and immunomodulatory properties in view of prospective applications as a nutraceutical in inflammatory conditions. In particular, metabolites transported by MEVs are involved in common pathways among the three species. These metabolites, such as arginine, asparagine, glutathione and lysine, show immunomodulating effects. Moreover, MEVs in goat milk showed a greater number of enriched metabolic pathways as compared to the other kinds of milk.

Perspective: The Role of Human Breast-Milk Extracellular Vesicles in Child Health and Disease

Human breast milk (HM) contains multiple bioactive substances determining its impact on children's health. Extracellular vesicles (EVs) are a heterogeneous group of secreted nanoparticles that are present in HM and may be partially responsible for its beneficial effects. The precise roles and content of EVs in HM remain largely unknown. To examine this, we performed a short narrative review on the literature focusing on HM EVs to contextualize the available data, followed by a scoping review of MEDLINE and Embase databases. We identified 424 nonduplicate citations with 19 original studies included. In this perspective, we summarize the evidence around HM EVs, highlight some theoretical considerations based on existing evidence, and provide an overview of some challenges associated with the complexity and heterogeneity of EV research. We consider how the existing data from HM studies conform to the minimal information for studies of EVs (MISEV) guidelines. Across the studies a variety of research methods were utilized involving both bench-based and translational methods, and a range of different EV contents were examined including RNA, proteins, and glycopeptides. We observed a variety of health outcomes in these studies, including allergy and atopy, necrotizing enterocolitis, and HIV. While some promising results have been demonstrated, the heterogeneity in outcomes of interest, methodological limitations, and relatively small number of studies in the field make comparison between studies or further translational work problematic. To date, no studies have examined normative values of HM EVs in a large, diverse population or with respect to potentially important influencing factors such as timing (hind- vs. foremilk), stage (colostrum vs. mature milk), and infant age (preterm vs. term), which makes extrapolation from bench or "basic" research impossible. Future research should focus on addressing the current inadequacies in the literature and utilize MISEV guidelines to inform study design.

SIDT1-dependent absorption in the stomach mediates host uptake of dietary and orally administered microRNAs

Dietary microRNAs have been shown to be absorbed by mammals and regulate host gene expression, but the absorption mechanism remains unknown. Here, we show that SIDT1 expressed on gastric pit cells in the stomach is required for the absorption of dietary microRNAs. SIDT1-deficient mice show reduced basal levels and impaired dynamic absorption of dietary microRNAs. Notably, we identified the stomach as the primary site for dietary microRNA absorption, which is dramatically attenuated in the stomachs of SIDT1-deficient mice. Mechanistic analyses revealed that the uptake of exogenous microRNAs by gastric pit cells is SIDT1 and low-pH dependent. Furthermore, oral administration of plant-derived miR2911 retards liver fibrosis, and this protective effect was abolished in SIDT1-deficient mice. Our findings reveal a major mechanism underlying the absorption of dietary microRNAs, uncover an unexpected role of the stomach and shed light on developing small RNA therapeutics by oral delivery.

Orally Administered Exosomes Suppress Mouse Delayed-Type Hypersensitivity by Delivering miRNA-150 to Antigen-Primed Macrophage APC Targeted by Exosome-Surface Anti-Peptide Antibody Light Chains

We previously discovered suppressor T cell-derived, antigen (Ag)-specific exosomes inhibiting mouse hapten-induced contact sensitivity effector T cells by targeting antigen-presenting cells (APCs). These suppressive exosomes acted Ag-specifically due to a coating of antibody free light chains (FLC) from Ag-activated B1a cells. Current studies are aimed at determining if similar immune tolerance could be induced in cutaneous delayed-type hypersensitivity (DTH) to the protein Ag (ovalbumin, OVA). Intravenous administration of a high dose of OVA-coupled, syngeneic erythrocytes similarly induced CD3⁺CD8⁺ suppressor T cells producing suppressive, miRNA-150-carrying exosomes, also coated with B1a cell-derived, OVA-specific FLC. Simultaneously, OVA-immunized B1a cells produced an exosome subpopulation, originally coated with Ag-specific FLC, that could be rendered suppressive by in vitro association with miRNA-150. Importantly, miRNA-150-carrying exosomes from both suppressor T cells and B1a cells efficiently induced prolonged DTH suppression after single systemic administration into actively immunized mice, with the strongest effect observed after oral treatment. Current studies also showed that OVA-specific FLC on suppressive exosomes bind OVA peptides suggesting that exosome-coating FLC target APCs by binding to peptide-Ag-major histocompatibility complexes. This renders APCs capable of inhibiting DTH effector T cells. Thus, our studies describe a novel immune tolerance mechanism mediated by FLC-coated, Ag-specific, miRNA-150-carrying exosomes that act on the APC and are particularly effective after oral administration.

Delineating effect of corn microRNAs and matrix, ingested as whole food, on gut microbiota in a rodent model

Dietary microRNAs (miRNAs) are thought to regulate a wide range of biological processes, including the gut microbiota. However, it is difficult to separate specific effect(s) of miRNA from that of the food matrix. This study aims to elucidate the specific effect(s) of dietary corn miRNAs, ingested as a whole food, on the gut microbiota. We developed an autoclave procedure to remove 98% of miRNA from corn. A mouse feeding study was conducted comparing autoclaved corn to nonautoclaved corn and purified corn miRNA. Compared to nonspecific nucleotides and corn devoid of miRNAs, feeding purified corn miRNAs or corn to C57BL/6 mice via gavage or diet supplementation for two weeks lead to a decrease in total bacteria in the cecum. The effect appeared to be due to changes in Firmicutes. Additionally, corn matrix minus miRNA and processing also affected gut bacteria. In silico analysis identified corn miRNAs that aligned to Firmicutes genome sequences lending further support to the interaction between corn miRNAs and this bacterium. These data support interactions between plant food miRNA, as well as matrix, and the gut microbiota exist but complex. However, it provides additional support for mechanism by which bioactive dietary components interact with the gut microbiota.

Dietary bovine milk exosomes elicit changes in bacterial communities in C57BL/6 mice

Exosomes and exosome-like vesicles participate in cell-to-cell communication in animals, plant, and bacteria. Dietary exosomes in bovine milk are bioavailable in nonbovine species, but a fraction of milk exosomes reaches the large intestine. We hypothesized that milk exosomes alter the composition of the gut microbiome in mice. C57BL/6 mice were fed AIN-93G diets, defined by their content of bovine milk exosomes and RNA cargos: exosome/RNA-depleted (ERD) versus exosome/RNA-sufficient (ERS) diets. Feeding was initiated at age 3 wk, and cecum content was collected at ages 7, 15, and 47 wk. Microbial communities were identified by 16S rRNA gene sequencing. Milk exosomes altered bacterial communities in the murine cecum. The abundance of three phyla, seven families, and 52 operational taxonomic units (OTUs) was different in the ceca from mice fed ERD and ERS (P < 0.05). For example, at the phylum level, Tenericutes had more than threefold abundance in ERS mice at ages 15 and 47 wk compared with ERD mice (P < 0.05). At the family level, Verrucomicrobiaceae were much less abundant in ERS mice compared with ERD mice age 47 wk (P < 0.05). At the OTU level, four OTUs from the family of Lachnospiraceae were more than two times more abundant in ERS mice compared with ERD at age 7 and 47 wk (P < 0.05). We conclude that exosomes in bovine milk alter microbial communities in nonbovine species, suggesting that exosomes and their cargos participate in the crosstalk between bacterial and animal kingdoms.NEW & NOTEWORTHY This is the first report that exosomes from bovine milk alter microbial communities in mice. This report suggests that the gut microbiome facilitates cell-to-cell communication by milk exosomes across species boundaries, and milk exosomes facilitate communication across animal and bacteria kingdoms.

Concentrates of two subsets of extracellular vesicles from cow's milk modulate symptoms and inflammation in experimental colitis

Extracellular vesicles (EVs) are involved in cell-to-cell communication and modulation of numerous physiological and pathological processes. EVs are found in large quantities in milk and contain several inflammation- and immunity-modulating proteins and microRNAs, through which they exert beneficial effects in several inflammatory disease models. Here, we investigated the effects of two EV subsets, concentrated from commercial cow's milk, on a murine model of colitis induced with dextran sodium sulfate (DSS). P35K EVs, isolated by ultracentrifugation at 35,000 g, and P100K EVs, isolated at 100,000 g, were previously characterized and administered by gavage to healthy and DSS-treated mice. P35K EVs and, to a lesser extent, P100K EVs improved several outcomes associated to DSS-induced colitis, modulated the gut microbiota, restored intestinal impermeability and replenished mucin secretion. Also, P35K EVs modulated innate immunity, while P100K EVs decreased inflammation through the downregulation of colitis-associated microRNAs, especially miR-125b, associated with a higher expression of the NFκB inhibitor TNFAIP3 (A20). These results suggest that different milk EV subsets may improve colitis outcomes through different, and possibly complementary, mechanisms. Further unveiling of these mechanisms might offer new opportunities for improving the life of patients with colitis and be of importance for milk processing, infant milk formulation and general public health.

Bovine Milk Extracellular Vesicles (EVs) Modification Elicits Skeletal Muscle Growth in Rats

The current study investigated how bovine milk extracellular vesicles (EVs) affected rotarod performance and biomarkers of skeletal muscle physiology in young, growing rats. Twenty-eight-day Fisher 344 rats were provided an AIN-93G-based diet for 4 weeks that either remained unadulterated [EVs and RNA-sufficient (ERS; n = 12)] or was sonicated [EVs and RNA-depleted (ERD; n = 12)]. Prior to (PRE) and on the last day of the intervention (POST), animals were tested for maximal rotarod performance. Following the feeding period, the gastrocnemius muscle was analyzed at the histological, biochemical, and molecular levels and was also used to measure mitochondrial function and reactive oxygen species (ROS) emission. A main effect of time was observed for rotarod time (PRE > POST, p = 0.001). Terminal gastrocnemius mass was unaffected by diet, although gastrocnemius muscle fiber cross sectional area was 11% greater (p = 0.018) and total RNA (a surrogate of ribosome density) was 24% greater (p = 0.001) in ERD. Transcriptomic analysis of the gastrocnemius indicated that 22 mRNAs were significantly greater in ERS versus ERD (p < 0.01), whereas 55 mRNAs were greater in ERD versus ERS (p < 0.01). There were no differences in gastrocnemius citrate synthase activity or mitochondrial coupling (respiratory control ratio), although mitochondrial ROS production was lower in ERD gastrocnemius (p = 0.016), which may be explained by an increase in glutathione peroxidase protein levels (p = 0.020) in ERD gastrocnemius. Dietary EVs profiling confirmed that sonication in the ERD diet reduced EVs content by ∼60%. Our findings demonstrate that bovine milk EVs depletion through sonication elicits anabolic and transcriptomic effects in the gastrocnemius muscle of rapidly maturing rats. While this did not translate into a functional outcome between diets (i.e., rotarod performance), longer feeding periods may be needed to observe such functional effects.

Milk MicroRNAs in Health and Disease

MicroRNAs are small noncoding RNAs responsible for regulating 40% to 60% of gene expression at the posttranscriptional level. The discovery of circulating microRNAs in several biological fluids opened the path for their study as biomarkers and long-range cell-to-cell communication mediators. Their transfer between individuals in the case of blood transfusion, for example, and their high enrichment in milk have sparked the interest for microRNA transfer through diet, especially from mothers to infants during breastfeeding. The extension of such paradigm led to the study of milk microRNAs in the case of cow or goat milk consumption in adults. Here we provide a comprehensive critical review of the key findings surrounding milk microRNAs in human, cow, and goat milk among other species. We discuss the data on their biological properties, their use as disease biomarkers, their transfer between individuals or species, and their putative or verified functions in health and disease of infants and adult consumers. This work is based on all the literature available and integrates all the results, theories, debates, and validation studies available so far on milk microRNAs and related areas of investigations. We critically discuss the limitations and outline future aspects and avenues to explore in this rapidly growing field of research that could impact public health through infant milk formulations or new therapies. We hope that this comprehensive review of the literature will provide insight for all teams investigating milk RNAs' biological activities and help ensure the quality of future reports.

Bovine milk-derived extracellular vesicles enhance inflammation and promote M1 polarization following agricultural dust exposure in mice

Occupational agricultural dust exposure can cause severe lung injury, including COPD and asthma exacerbations. Cell-derived extracellular vesicles can mediate inflammatory responses and immune activation, but the contribution of diet-derived extracellular vesicles to these processes is poorly understood. We investigated whether bovine milk-derived extracellular vesicles modulate inflammatory responses to agricultural dust exposures in a murine model. C57BL/6 mice were fed either an extracellular vesicle-enriched modification of the AIN-93G diet with lyophilized bovine milk (EV) or a control diet wherein the milk was presonicated, disrupting the milk extracellular vesicles and thereby leading to RNA degradation (DEV). Mice were maintained on the diets for 5-7 weeks and challenged with a single (acute) intranasal instillation of a 12.5% organic dust extract (DE) or with 15 instillations over 3 weeks (repetitive exposure model). Through these investigations, we identified significant interactions between diet and DE when considering numerous inflammatory outcomes, including lavage inflammatory cytokine levels and cellular infiltration into the lung airways. DE-treated peritoneal macrophages also demonstrated altered polarization, with EV-fed mouse macrophages exhibiting an M1 shift compared to an M2 phenotype in DEV-fed mice (IL-6, TNF, IL-12/23 all significantly elevated, and IL-10 and arginase decreased in EV macrophages, ex vivo). In complementary in vitro studies, mouse macrophages treated with purified milk-derived EV were found to express similar polarization phenotypes upon DE stimulation. These results suggest a role for dietary extracellular vesicles in the modulation of lung inflammation in response to organic dust which may involve macrophage phenotype polarization.

Milk-Derived Exosomes and Metabolic Regulation

Exosomes are natural nanoparticles that play an important role in cell-to-cell communication. Communication is achieved through the transfer of cargos, such as microRNAs, from donor to recipient cells and binding of exosomes to cell surface receptors. Exosomes and their cargos are also obtained from dietary sources, such as milk. Exosome and cell glycoproteins are crucial for intestinal uptake. A large fraction of milk exosomes accumulates in the brain, whereas the tissue distribution of microRNA cargos varies among distinct species of microRNA. The fraction of milk exosomes that escapes absorption elicits changes in microbial communities in the gut. Dietary depletion of exosomes and their cargos causes a loss of circulating microRNAs and elicits phenotypes such as loss of cognitive performance, increase in purine metabolites, loss of fecundity, and changes in the immune response. Milk exosomes meet the definition of bioactive food compounds.

Identification of protein markers for extracellular vesicle (EV) subsets in cow's milk

Extracellular vesicles (EVs), like exosomes, are small membrane vesicles involved in cell-to-cell communications that modulate numerous biological processes. We previously discovered a new EV subset in milk (sedimenting at 35,000 g; 35 K) that protected its cargo (RNAs and proteins) during simulated digestion and was more enriched in microRNAs than exosomes (sedimenting at 100 K). Here, we used LC-MS/MS to push further the comparison between these two pellets. Commonly used EV markers were not differentially enriched between the pellets, questioning their use with cow's milk EVs. Similarly, the majority of the quantified proteins were equally enriched between the two pellets. Nevertheless, 20 proteins were specific to 35 K, while 41 were specifically enriched in 100 K (p < 0.05), suggesting their potential use as specific markers. Loaded with these proteins, the EVs in these pellets might regulate translation, proliferation and cell survival for 35 K, and metabolism, extracellular matrix turnover and immunity for 100 K. This approach also brought new insights into milk EV-associated integrins and their possible role in specifically targeting recipient cell types. These findings may help better discriminate between milk EVs, improve our understanding of milk EV-associated protein function and their possible use as therapeutic tools for the management of immunity- and metabolism-associated disorders. WEB PAGE: http://www.crchuq.ca/en/research/researchers/4691.

RNase H2-Dependent Polymerase Chain Reaction and Elimination of Confounders in Sample Collection, Storage, and Analysis Strengthen Evidence That microRNAs in Bovine Milk Are Bioavailable in Humans

Background

Evidence suggests that dietary microRNAs (miRs) are bioavailable and regulate gene expression across species boundaries. Concerns were raised that the detection of dietary miRs in plasma might have been due to sample contamination or lack of assay specificity. Objectives: The objectives of this study were to assess potential confounders of plasma miR analysis and to detect miRs from bovine milk in human plasma.

Methods

Potential confounders of plasma miR analysis (circadian rhythm, sample collection and storage, calibration, and erythrocyte hemolysis) were assessed by quantitative reverse transcriptase polymerase chain reaction (PCR) by using blood from healthy adults (7 men, 6 women; aged 23-57 y). Bovine miRs were analyzed by RNase H2-dependent PCR (rhPCR) in plasma collected from a subcohort of 11 participants before and 6 h after consumption of 1.0 L of 1%-fat bovine milk.

Results

The use of heparin tubes for blood collection resulted in a complete loss of miRs. Circadian variations did not affect the concentrations of 8 select miRs. Erythrocyte hemolysis caused artifacts for some miRs if plasma absorbance at 414 nm was >0.300. The stability of plasma miRs depended greatly on the matrix in which the miRs were stored and whether the plasma was frozen before analysis. Purified miR-16, miR-200c, and cel-miR-39 were stable for ≤24 h at room temperature, whereas losses equaled ≤80% if plasma was frozen, thawed, and stored at room temperature for as little as 4 h. rhPCR distinguished between bovine and human miRs with small variations in the nucleotide sequence; plasma concentrations of Bos taurus (bta)-miR-21-5p and bta-miR-30a-5p were >100% higher 6 h after milk consumption than before milk consumption.

Conclusions

Confounders in plasma miR analysis include the use of heparin tubes, erythrocyte hemolysis, and storage of thawed plasma at room temperature. rhPCR is a useful tool to detect dietary miRs.

A subset of extracellular vesicles carries the bulk of microRNAs in commercial dairy cow's milk

MicroRNAs are small gene-regulatory RNAs that are found in various biological fluids, including milk, where they are often contained inside extracellular vesicles (EVs), like exosomes. In a previous study, we reported that commercial dairy cow's milk microRNAs resisted simulated digestion and were not exclusively associated with canonical exosomes. Here, we report the characterization of a milk EV subset that sediments at lower ultracentrifugation speeds and that contains the bulk of microRNAs. Milk EVs were isolated by differential ultracentrifugation and Iodixanol density gradient (IDG), and analysed for (1) microRNA enrichment by reverse transcription and quantitative polymerase chain reaction (RT-qPCR), and (2) EV-associated proteins by Western blot. Milk EVs were characterized further by dynamic light scattering (DLS), density measurements, fluorescent DiR and RNA labelling, high-sensitivity flow cytometry (HS-FCM), transmission electron microscopy (TEM), proteinase K and RNase A assay, and liquid chromatography tandem-mass spectrometry (LC-MS/MS). We found that the bulk of milk microRNAs (e.g., bta-miR-125b, bta-miR-148a, etc.) sediment at 12,000 g and 35,000 g. Their distribution pattern was different from that of exosome-enriched proteins, but similar to that of several proteins commonly found in milk fat globule membranes (MFGM), including xanthine dehydrogenase (XDH). These low-speed ultracentrifugation pellets contained cytoplasm-enclosing phospholipid bilayered membrane vesicles of a density comprised between 1.11 and 1.14 g/mL in Iodixanol. This milk EV subset of ~100 nm in diameter/~200 nm hydrodynamic size resisted to proteinase K digestion and protected their microRNA content from RNase A digestion. Our results support the existence of a milk EV subset pelleting at low ultracentrifugations speeds, with a protein coating comparable with MFGM, which contains and protects the bulk of milk microRNAs from degradation. This milk EV subset may represent a new EV population of interest, whose content in microRNAs and proteins supports its potential bioactivity.

Milk disrupts p53 and DNMT1, the guardians of the genome: implications for acne vulgaris and prostate cancer

There is accumulating evidence that milk shapes the postnatal metabolic environment of the newborn infant. Based on translational research, this perspective article provides a novel mechanistic link between milk intake and milk miRNA-regulated gene expression of the transcription factor p53 and DNA methyltransferase 1 (DNMT1), two guardians of the human genome, that control transcriptional activity, cell survival, and apoptosis. Major miRNAs of milk, especially miRNA-125b, directly target TP53 and complex p53-dependent gene regulatory networks. TP53 regulates the expression of key genes involved in cell homeostasis such as FOXO1, PTEN, SESN1, SESN2, AR, IGF1R, BAK1, BIRC5, and TNFSF10. Nuclear interaction of p53 with DNMT1 controls gene silencing. The most abundant miRNA of milk and milk fat, miRNA-148a, directly targets DNMT1. Reduced DNMT1 expression further attenuates the activity of histone deacetylase 1 (HDAC1) involved in the regulation of chromatin structure and access to transcription. The presented milk-mediated miRNA-p53-DNMT1 pathway exemplified at the promoter regulation of survivin (BIRC5) provides a novel explanation for the epidemiological association between milk consumption and acne vulgaris and prostate cancer. Notably, p53- and DNMT1-targeting miRNAs of bovine and human milk survive pasteurization and share identical seed sequences, which theoretically allows the interaction of bovine miRNAs with the human genome. Persistent intake of milk-derived miRNAs that attenuate p53- and DNMT1 signaling of the human milk consumer may thus present an overlooked risk factor promoting acne vulgaris, prostate cancer, and other p53/DNMT1-related Western diseases. Therefore, bioactive miRNAs of commercial milk should be eliminated from the human food chain.