Identification and Peptidomic Profiling of Exosomes in Preterm Human Milk: Insights Into Necrotizing Enterocolitis Prevention

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.

Immunomodulatory significance of natural peptides in mammalians: Promising agents for medical application

Modulation of immune responses by immunoregulatory agents, such as the natural or synthetic immunomodulatory peptides, has been suggested as a potential strategy to modulate immune system against infection and other immune-related diseases. These compositionally simple peptides have attracted much attention for many drug developers, due to their high activity, low toxicity and clear target specificity. Host defence peptides and milk-derived peptides are two kinds of natural immunomodulatory peptides which have been widely studied in mammalians. They could participate at the interface of innate and adaptive immunity by regulating immune effector cells. This review summarizes the recent advances in host defence peptides and milk-derived peptides as well as their general characteristics, immunomodulatory functions and possible applications.

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.

Breast Milk Lipids and Fatty Acids in Regulating Neonatal Intestinal Development and Protecting against Intestinal Injury

Human breast milk is the optimal source of nutrition for infant growth and development. Breast milk fats and their downstream derivatives of fatty acids and fatty acid-derived terminal mediators not only provide an energy source but also are important regulators of development, immune function, and metabolism. The composition of the lipids and fatty acids determines the nutritional and physicochemical properties of human milk fat. Essential fatty acids, including long-chain polyunsaturated fatty acids (LCPUFAs) and specialized pro-resolving mediators, are critical for growth, organogenesis, and regulation of inflammation. Combined data including in vitro, in vivo, and human cohort studies support the beneficial effects of human breast milk in intestinal development and in reducing the risk of intestinal injury. Human milk has been shown to reduce the occurrence of necrotizing enterocolitis (NEC), a common gastrointestinal disease in preterm infants. Preterm infants fed human breast milk are less likely to develop NEC compared to preterm infants receiving infant formula. Intestinal development and its physiological functions are highly adaptive to changes in nutritional status influencing the susceptibility towards intestinal injury in response to pathological challenges. In this review, we focus on lipids and fatty acids present in breast milk and their impact on neonatal gut development and the risk of disease.

Human breast milk exosomes attenuate intestinal damage

BACKGROUND

Human breast milk (HBM), which contains an abundant supply of exosomes, is known to prevent necrotizing enterocolitis (NEC). Preterm infants are commonly given pasteurized donor milk when HBM is unavailable. However, pasteurization can disrupt its components. This study investigates the effects of both raw and pasteurized HBM-derived exosomes on intestinal inflammation.

METHODS

HBM exosomes were isolated and characterized by positive CD63 and negative calnexin markers from western blot, nanoparticle tracking analysis and transmission electron microscopy. Mouse intestine organoids were established and treated with exosomes from raw or pasteurized HBM in healthy and injury conditions. Following ethical approval (#44032), mice pups were randomly assigned to (1) breastfed control; (2) NEC; (3) NEC receiving raw HBM exosomes; (4) NEC receiving pasteurized HBM exosomes. NEC was induced by hypoxia, gavage feeding and lipopolysaccharide (LPS). Ileum was evaluated. Data were analyzed using one-way ANOVA with Bonferroni post-test.

RESULTS

Both raw and pasteurized HBM exosomes decreased inflammation in hypoxia and LPS-treated organoids compared to control. In vivo, NEC-induced mucosal injury, inflammation and mucous production were improved by raw and pasteurized HBM-derived exosomes.

CONCLUSIONS

Exosomes derived from raw and pasteurized HBM equally reduced intestinal damage. Exosome administration in clinical practice requires further investigation.

Effects of oropharyngeal administration of colostrum on the incidence of necrotizing enterocolitis, late-onset sepsis, and death in preterm infants: a meta-analysis of RCTs

Necrotizing enterocolitis (NEC) and late-onset sepsis (LOS) are two major contributors to death among preterm infants. Oropharyngeal administration of colostrum (OAC) has been proved as an easy, safe, and economically viable technique to help preterm neonates to build up their immunity. In this review, we assessed the effects of OAC on preterm infants. Several mainstream databases were searched including PubMed, EMBASE, Cochrane Central Register of Controlled Trials (CENTRAL), and a website of clinical trials. Randomized controlled trials (RCTs) comparing OAC vs. placebo or no intervention in preterm infants (gestation age <34 weeks or birth weight <1500 g) were eligible. Overall, nine RCTs (n = 689) were included in the review. Meta-analysis showed no statistical significance in terms of the incidence of NEC (RR = 0.59, 95% CI = 0.33-1.06, p = 0.08), LOS (RR = 0.78, 95% CI = 0.60-1.03, p = 0.08) and mortality rate (RR = 0.63, 95% CI = 0.38-1.05, p = 0.07). No significant difference was found in the subgroup analysis, apart from the group of the undeveloped region in NEC and mortality. In addition, time was significantly reduced in terms of achieving full enteral feeding (MD = -3.60, 95% CI = -6.55-0.64, p = 0.02) and hospital stay (MD = -10.38, 95% CI = -18.47-2.29, p = 0.01). The results show that OAC does not reduce the incidences of NEC, LOS, and death in preterm infants, but there is a trend toward a positive effect. It is therefore recommended as routine care for preterm infants in the NICU.

A comparison of exosomes derived from different periods breast milk on protecting against intestinal organoid injury

AIM OF THE STUDY

Human breast milk reduces the risk and severity of necrotizing enterocolitis (NEC). Exosomes are extracellular vesicles (EVs) found in high concentrations in milk, and they mediate intercellular communication and immune responses. The aim of this study is to compare the protective effects of exosomes that are derived from different time periods of breast milk production against intestinal injury using an ex vivo intestinal organoid model.

METHODS

Colostrum, transitional and mature breast milk samples from healthy lactating mothers were collected. Exosomes were isolated using serial ultracentrifugation and filtration. Exosomes' presence was confirmed using transmission electron microscopy (TEM) and western blot. To form the intestinal organoids, terminal ileum was harvested from neonatal mice pups at postnatal day 9, crypts were isolated and organoids were cultured in matrigel. Organoids were either cultured with exposure to lipopolysaccharide (LPS), or in treatment groups where both LPS and exosomes were added in the culturing medium. Inflammatory markers and organoids viability were evaluated.

MAIN RESULTS

Human milk-derived exosomes were successfully isolated and characterized. LPS administration reduced the size of intestinal organoids, induced inflammation through increasing TNFα and TLR4 expression, and stimulated intestinal regeneration. Colostrum, transitional and mature human milk-derived exosome treatment all prevented inflammatory injury, while exosomes derived from colostrum were most effective at reducing inflammatory cytokine.

CONCLUSIONS

Human breast milk-derived exosomes were able to protect intestine organoids against epithelial injury induced by LPS. Colostrum exosomes offer the best protective effect among the breast-milk derived exosomes. Human milk exosomes can be protective against the development of intestinal injury such as that seen in NEC.

Extracellular Vesicles as a Potential Therapy for Neonatal Conditions: State of the Art and Challenges in Clinical Translation

Despite advances in intensive care, several neonatal conditions typically due to prematurity affect vital organs and are associated with high mortality and long-term morbidities. Current treatment strategies for these babies are only partially successful or are effective only in selected patients. Regenerative medicine has been shown to be a promising option for these conditions at an experimental level, but still warrants further exploration for the development of optimal treatment. Although stem cell-based therapy has emerged as a treatment option, studies have shown that it is associated with potential risks and hazards, especially in the fragile population of babies. Recently, extracellular vesicles (EVs) have emerged as an attractive therapeutic alternative that holds great regenerative potential and is cell-free. EVs are nanosized particles endogenously produced by cells that mediate intercellular communication through the transfer of their cargo. Currently, EVs are garnering considerable attention as they are the key effectors of stem cell paracrine signaling and can epigenetically regulate target cell genes through the release of RNA species, such as microRNA. Herein, we review the emerging literature on the therapeutic potential of EVs derived from different sources for the treatment of neonatal conditions that affect the brain, retinas, spine, lungs, and intestines and discuss the challenges for the translation of EVs into clinical practice.