Breast milk microRNAs: Potential players in oral tolerance development

Risk of Fat Mass- and Obesity-Associated Gene-Dependent Obesogenic Programming by Formula Feeding Compared to Breastfeeding

It is the purpose of this review to compare differences in postnatal epigenetic programming at the level of DNA and RNA methylation and later obesity risk between infants receiving artificial formula feeding (FF) in contrast to natural breastfeeding (BF). FF bears the risk of aberrant epigenetic programming at the level of DNA methylation and enhances the expression of the RNA demethylase fat mass- and obesity-associated gene (FTO), pointing to further deviations in the RNA methylome. Based on a literature search through Web of Science, Google Scholar, and PubMed databases concerning the dietary and epigenetic factors influencing FTO gene and FTO protein expression and FTO activity, FTO's impact on postnatal adipogenic programming was investigated. Accumulated translational evidence underscores that total protein intake as well as tryptophan, kynurenine, branched-chain amino acids, milk exosomal miRNAs, NADP, and NADPH are crucial regulators modifying FTO gene expression and FTO activity. Increased FTO-mTORC1-S6K1 signaling may epigenetically suppress the WNT/β-catenin pathway, enhancing adipocyte precursor cell proliferation and adipogenesis. Formula-induced FTO-dependent alterations of the N6-methyladenosine (m6A) RNA methylome may represent novel unfavorable molecular events in the postnatal development of adipogenesis and obesity, necessitating further investigations. BF provides physiological epigenetic DNA and RNA regulation, a compelling reason to rely on BF.

Science and Faith to Understand Milk Bioactivity for Infants

Milk bioactivity refers to the specific health effects of milk components beyond nutrition. The science of milk bioactivity involves the systematic study of these components and their health effects, as verified by empirical data, controlled experiments, and logical arguments. Conversely, 'faith in milk bioactivity' can be defined as personal opinion, meaning, value, trust, and hope for health effects that are beyond investigation by natural, social, or human sciences. Faith can be strictly secular, but also influenced by spirituality or religion. The aim of this paper is to show that scientific knowledge is frequently supplemented with faith convictions to establish personal and public understanding of milk bioactivity. Mammalian milk is an immensely complex fluid containing myriad proteins, carbohydrates, lipids, and micronutrients with multiple functions across species, genetics, ages, environments, and cultures. Human health includes not only physical health, but also social, mental, and spiritual health, requiring widely different fields of science to prove the relevance, safety, and efficacy of milk interventions. These complex relationships between milk feeding and health outcomes prevent firm conclusions based on science and logic alone. Current beliefs in and understanding of the value of breast milk, colostrum, infant formula, or isolated milk proteins (e.g., immunoglobulins, α-lactalbumin, lactoferrin, and growth factors) show that both science and faith contribute to understand, stimulate, or restrict the use of milk bioactivity. The benefits of breastfeeding for infants are beyond doubt, but the strong beliefs in its health effects rely not only on science, and mechanisms are unclear. Likewise, fear of, or trust in, infant formula may rely on both science and faith. Knowledge from science safeguards individuals and society against 'milk bioactivity superstition'. Conversely, wisdom from faith-based convictions may protect science from unrealistic 'milk bioactivity scientism'. Honesty and transparency about the potentials and limitations of both scientific knowledge and faith convictions are important when informing individuals and society about the nutritious and bioactive qualities of milk.

Recent insights into breast milk microRNA: their role as functional regulators

Breast milk (BM) is a primary biofluid that plays a crucial role in infant development and the regulation of the immune system. As a class of rich biomolecules in BM, microRNAs (miRNAs) are regarded as active factors contributing to infant growth and development. Surprisingly, these molecules exhibit resilience in harsh conditions, providing an opportunity for infants to absorb them. In addition, many studies have shown that miRNAs in breast milk, when absorbed into the gastrointestinal system, can act as a class of functional regulators to effectively regulate gene expression. Understanding the absorption pattern of BM miRNA may facilitate the creation of formula with a more optimal miRNA balance and pave the way for novel drug delivery techniques. In this review, we initially present evidence of BM miRNA absorption. Subsequently, we compile studies that integrate both in vivo and in vitro findings to illustrate the bioavailability and biodistribution of BM miRNAs post-absorption. In addition, we evaluate the strengths and weaknesses of previous studies and discuss potential variables contributing to discrepancies in their outcomes. This literature review indicates that miRNAs can be absorbed and act as regulatory agents.

Unraveling the Multifaceted Roles of Extracellular Vesicles: Insights into Biology, Pharmacology, and Pharmaceutical Applications for Drug Delivery

Extracellular vesicles (EVs) are nanoparticles released from various cell types that have emerged as powerful new therapeutic option for a variety of diseases. EVs are involved in the transmission of biological signals between cells and in the regulation of a variety of biological processes, highlighting them as potential novel targets/platforms for therapeutics intervention and/or delivery. Therefore, it is necessary to investigate new aspects of EVs' biogenesis, biodistribution, metabolism, and excretion as well as safety/compatibility of both unmodified and engineered EVs upon administration in different pharmaceutical dosage forms and delivery systems. In this review, we summarize the current knowledge of essential physiological and pathological roles of EVs in different organs and organ systems. We provide an overview regarding application of EVs as therapeutic targets, therapeutics, and drug delivery platforms. We also explore various approaches implemented over the years to improve the dosage of specific EV products for different administration routes.

Human Breast Milk miRNAs: Their Diversity and Potential for Preventive Strategies in Nutritional Therapy

The endogenous miRNAs of breast milk are the products of more than 1000 nonprotein-coding genes, giving rise to mature small regulatory molecules of 19-25 nucleotides. They are incorporated in macromolecular complexes, loaded on Argonaute proteins, sequestrated in exosomes and lipid complexes, or present in exfoliated cells of epithelial, endothelial, or immune origins. Their expression is dependent on the stage of lactation; however, their detection depends on progress in RNA sequencing and the reappraisal of the definition of small RNAs. Some miRNAs from plants are detected in breast milk, opening the possibility of the stimulation of immune cells from the allergy repertoire. Each miRNA harbors a seeding sequence, which targets mRNAs, gene promoters, or long noncoding RNAs. Their activities depend on their bioavailability. Efficient doses of miRNAs are estimated to be roughly 100 molecules in the cytoplasm of target cells from in vitro and in vivo experiments. Each miRNA is included in networks of stimulation/inhibition/sequestration, driving the expression of cellular phenotypes. Three types of stress applied during lactation to manipulate miRNA supply were explored using rodent offspring: a foster mother, a cafeteria diet, and early weaning. This review presents the main mature miRNAs described from current mothers' cohorts and their bioavailability in experimental models as well as studies assessing the potential of miR-26 or miR-320 miRNA families to alter offspring phenotypes.

Anti-Inflammatory and Anti-Allergic Properties of Colostrum from Mothers of Full-Term and Preterm Babies: The Importance of Maternal Lactation in the First Days

Our narrative review focuses on colostrum components, particularly those that influence the neonatal immune system of newborns. Colostrum is secreted in small volumes by the alveolar cells of the breast during the first two to five days after birth. Colostrum is poor in fat and carbohydrates, with larger protein and bioactive compounds than mature milk. It plays a crucial role in driving neonates' immunity, transferring those immunological factors which help the correct development of the neonatal immune system and support establishing a healthy gut microbiome. The newborn has an innate and adaptive immune system deficiency, with a consequent increase in infection susceptibility. In particular, neonates born prematurely have reduced immunological competencies due to an earlier break in the maternal trans-placenta transfer of bioactive components, such as maternal IgG antibodies. Moreover, during pregnancy, starting from the second trimester, maternal immune cells are conveyed to the fetus and persist in small quantities post-natal, whereby this transfer is known as microchimerism (MMc). Thus, preterm newborns are deficient in this maternal heritage, and have their own immune system under-developed, but colostrum can compensate for the lack. Early breastfeeding, which should be strongly encouraged in mothers of preterm and full-term babies, provides those immunomodulant compounds that can act as a support, allowing the newborn to face immune needs, including fronting infections and establishing tolerance. Moreover, making mothers aware that administering colostrum helps their infants in building a healthy immune system is beneficial to sustain them in the difficult post-partum period.

MiR-148a-3p Promotes Colorectal Cancer Cell Ferroptosis by Targeting SLC7A11

Ferroptosis, an iron-dependent form of cell death, and dysregulated microRNA (miRNA) expression correlate with colorectal cancer (CRC) development and progression. The tumor suppressor ability of miR-148a-3p has been reported for several cancers. Nevertheless, the role of miR-148a-3p in CRC remains largely undetermined. Here, we aim at investigating the molecular mechanisms and regulatory targets of miR-148a-3p in the CRC cell death mechanism(s). To this end, miR-148a-3p expression was evaluated in SW480 and SW620 cells and normal colon epithelial CCD 841 CoN cells with quantitative real-time polymerase chain reaction (qRT-PCR). Data reported a reduction of miR-148a-3p expression in SW480 and SW620 cells compared to non-tumor cells (p < 0.05). Overexpression of miR-148a selectively inhibited CRC cell viability (p < 0.001), while weakly affecting normal CCD 841 CoN cell survival (p < 0.05). At the cellular level, miR-148a-3p mimics promoted apoptotic cell death via caspase-3 activation (p < 0.001), accumulation of mitochondrial reactive oxygen species (ROS) (p < 0.001), and membrane depolarization (p < 0.001). Moreover, miR-148a-3p overexpression induced lipid peroxidation (p < 0.01), GPX4 downregulation (p < 0.01), and ferroptosis (p < 0.01), as revealed by intracellular and mitochondrial iron accumulation and ACSL4/TFRC/Ferritin modulation. In addition, levels of SLC7A11 mRNA and protein, the cellular targets of miR-148a-3p predicted by bioinformatic tools, were suppressed by miR-148a-3p's overexpression. On the contrary, the downregulation of miR-148a-3p boosted SLC7A11 gene expression and suppressed ferroptosis. Together, these in vitro findings reveal that miR-148a-3p can function as a tumor suppressor in CRC by targeting SLC7A11 and activating ferroptosis, opening new perspectives for the rationale of therapeutic strategies through targeting the miR-148a-3p/SLC7A11 pathway.

The Protective Role of Exosome-Derived MicroRNAs and Proteins from Human Breast Milk against Infectious Agents

Human breast milk (HBM)-derived exosomes contain various biological and immunological components. However, comprehensive immune-related and antimicrobial factor analysis requires transcriptomic, proteomic, and multiple databases for functional analyses, and has yet to be conducted. Therefore, we isolated and confirmed HBM-derived exosomes by detecting specific markers and examining their morphology using western blot and transmission electron microscopy. Moreover, we implemented small RNA sequencing and liquid chromatography-mass spectrometry to investigate substances within the HBM-derived exosomes and their roles in combating pathogenic effects, identifying 208 miRNAs and 377 proteins associated with immunological pathways and diseases. Integrated omics analyses identified a connection between the exosomal substances and microbial infections. In addition, gene ontology and the Kyoto Encyclopedia of Genes and Genomes pathway analyses demonstrated that HBM-derived exosomal miRNA and proteins influence immune-related functions and pathogenic infections. Finally, protein-protein interaction analysis identified three primary proteins (ICAM1, TLR2, and FN1) associated with microbial infections mediating pro-inflammation, controlling infection, and facilitating microbial elimination. Our findings determine that HBM-derived exosomes modulate the immune system and could offer therapeutic strategies for regulating pathogenic microbial infection.