Advances in the protection of intestinal mucosal barrier function by milk-derived miRNAs.

Milk is a significant component of the human diet, providing an abundance of energy and nutrients and a variety of functional factors. Recent studies have revealed that milk is highly enriched in exosomes with intercellular communication functions, which can act on target cells in vivo by carrying and delivering miRNAs and critically participating in physiological processes such as host intestinal development, cell differentiation, and immune response. In recent years, the biosynthesis of milk-derived miRNAs and their cross-border uptake mechanisms, the biological functions of milk-derived miRNAs and the universality of their regulatory modalities, the extraction and identification of milk-derived miRNAs as novel active ingredients and their potential as biomarkers have been extensively studied. Accordingly, this paper compares and summarizes the cutting-edge research on the nutritional and health functions of milk-derived miRNAs, including the types and contents of milk-derived miRNAs, their transportability and stability in the digestive tract, with special attention to the molecular mechanisms of the milk-derived miRNAs in protecting the barrier function of the intestinal mucosa, and looks forward to the application of milk-derived miRNAs as novel dietary supplements in infant foods and functional foods. It will inform future efforts to elucidate the profound impact of milk-derived miRNAs on the human intestine and broader health.

Postbiotics derived from Lactobacillus plantarum 1.0386 ameliorate lipopolysaccharide-induced tight junction injury via MicroRNA-200c-3p mediated activation of the MLCK-MLC pathway in Caco-2 cells.

L. plantarum 1.0386 repairs intestinal epithelial tight junction injury, and the present study was designed to further explore the role of its postbiotics, including the surface protein (1.0386-Slp), peptidoglycan (1.0386-PG) and exopolysaccharide (1.0386-EPS). The results showed that they all could improve the lipopolysaccharide (LPS)-induced decrease of transepithelial electrical resistance, increase of paracellular permeability, release of inflammatory factors, and disruption of tight junctions in Caco-2 cells, and the repairing effect of 1.0386-Slp was better than those of 1.0386-PG and 1.0386-EPS, and was similar to that of L. plantarum 1.0386. Moreover, either L. plantarum 1.0386 or 1.0386-Slp intervention significantly increased the expression of miR-200c inhibited by LPS, while the miR-200c inhibitor weakened the ability of 1.0386-Slp to promote the expression of tight junction proteins (ZO-1, occludin and claudin-1). Meanwhile, 1.0386-Slp restored the distribution of tight junction proteins and inhibited the increase of NF-κB p65, MLC and pMLC protein expression evoked by LPS. However, the addition of miR-200c inhibitors or mimics weakened or strengthened the down-regulation of MLCK-MLC pathway protein expression by 1.0386-Slp, respectively. In summary, 1.0386-Slp may be the main efficacy component of L. plantarum 1.0386, and miR-200c may be involved in the process of 1.0386-Slp inhibiting the MLCK pathway to repair intestinal epithelial tight junction injury.

Comparative study on the immunomodulatory function of extracellular vesicles from different dairy products.

Bovine milk-derived extracellular vesicles (EVs) have been proved to have positive effects on innate immunity and intestinal health. However, the effect of different processing treatments on the biological function of EVs in dairy products remains unclear. Thus, we explored the immunomodulatory function of EVs from different dairy products (pasteurized milk, UHT milk, freeze-dried powder and organic milk powder) by constructing the RAW264.7 cell model, the most commonly used in vitro model to study immune responses and screen for anti-inflammatory active substances. The results showed that EVs from different dairy products had similar bidirectional immunomodulatory effects to EVs from raw milk, which not only promoted the normal macrophage proliferation and increased NO and cytokine (IL-1ß, IL-6 and TNF-α) levels, but also inhibited the lipopolysaccharide (LPS)-induced TLR4/NF-κB pathway and inflammatory cytokines. In particular, EVs from different dairy products also could regulate the expression of immune-related miR-155, miR-223 and miR-181a, which were involved in the anti-infection response. Although the immunomodulatory effects of EVs in the pasteurized milk and freeze-dried powder groups were lower than that of the raw milk group, they were superior to the UHT milk group and significantly higher than the organic milk powder group. Therefore, we hypothesize that pasteurization and freeze-drying treatments might have less effect on the physiological activity of EVs, making the potential health benefits of the corresponding products superior to those of other dairy products.

2'-Fucosyllactose promotes Lactobacillus rhamnosus KLDS 8001 to repair LPS-induced damage in Caco-2 cells.

The aim of this study was to investigate the effect of 2'-fucosyllactose (2'-FL) on the repair of monolayer barrier damage in Caco-2 cells by Lactobacillus rhamnosus KLDS 8001 (KLDS 8001). The results showed that the addition of 2'-FL not only promoted the adhesion ability of KLDS 8001 to Caco-2 cells but also improved the anti-adhesive effect of pathogenic bacteria. Compared with 2'-FL or KLDS 8001 alone, 2'-FL+KLDS 8001 significantly reduced lipopolysaccharide (LPS)-induced malondialdehyde (MDA), lactate dehydrogenase (LDH) release, and cytokine (IL-1ß, IL-6, and TNF-α) production. In addition, 2'-FL effectively promoted the transmembrane electrical resistance (TEER), cell viability, and cellular permeability of KLDS 8001 repaired damaged cells with dose-dependent properties. The mRNA and protein expression of Zonula Occludens-1 (ZO-1), Occludin, and Claudin-1 were also upregulated in the KLDS 8001 and 2'-FL co-treated treatment group. It was speculated that 2'-FL could effectively regulate the interaction between KLDS 8001 and intestinal epithelial cells to play a role in maintaining intestinal barrier function and avoiding pathogenic bacteria invasion. PRACTICAL APPLICATIONS: As the most widely used human milk oligosaccharides (HMOs), 2'-FL is vital for maintaining infant intestinal health. Our study found that the addition of 2'-FL promoted KLDS 8001 adhesion, anti-adhesion of pathogenic bacteria, anti-inflammatory capacity, repair of barrier damage, and tight junction protein expression, providing a new strategy to protect infant intestinal health and prevent various intestinal diseases.

Effects of Lactobacillus fermentum HY01 on the quality characteristics and storage stability of yak yogurt.

Lactobacillus fermentum HY01 is a probiotic strain screened from traditional yak yogurt, which can effectively relieve enteritis and constipation. This study aimed to evaluate the effects of HY01 as an adjunct starter on the quality and storage of yak yogurt. A total of 36 main volatile flavor substances were detected in all samples. In particular, more aldehydes, esters, and alcohols were detected in yak yogurt prepared by mixed fermentation of L. fermentum HY01 and starter MY105 (including Streptococcus thermophilus and Lactobacillus delbrueckii ssp. bulgaricus). The rheological results showed that the yak yogurt prepared by mixed fermentation of L. fermentum HY01 and starter MY105 had higher apparent viscosity and lower tan δ value compared with compared with traditional yak yogurt, yak yogurt with only L. fermentum HY01, and cow yogurt with L. fermentum HY01 and starter MY105. Meanwhile, the conjugated linoleic acid in the yak yogurt prepared by mixed fermentation of L. fermentum HY01 and starter was significantly higher than those in the HY01 group or the yogurt starter group alone. After 28 d of storage at 4°C, the number of HY01 in the yak yogurt prepared by mixed fermentation of L. fermentum HY01 and starter was still higher than 107 cfu/mL, its acidity was lower than 110°T, and its syneresis was the lowest. The results indicated that L. fermentum HY01 could improve the flavor, texture, and storage properties of yak yogurt.

Lactobacillus acidophilus KLDS 1.0738 inhibits TLR4/NF-κB inflammatory pathway in ß-lactoglobulin-induced macrophages via modulating miR-146a.

Our previous study has confirmed that Lactobacillus acidophilus KLDS 1.0738 (La KLDS 1.0738) could alleviate ß-lactoglobulin (ß-Lg)-induced allergic inflammation. This study further explored its molecular regulation mechanism through an in vitro macrophage model. ß-Lg-induced macrophages were treated with strains of viable or non-viable L. acidophilus and Toll-like receptor 4 (TLR4) inhibitor or miR-146a inhibitor. Our results revealed that ß-Lg stimulation led to the increased expression of TLR4/NF-κB signal pathway in macrophages. Similar to TLR4 inhibitor treatment, La KLDS 1.0738 interventions significantly reduced the allergic inflammation by inhibition of TLR4 pathway, which was superior to the commercial L. acidophilus GMNL-185 strains (La GMNL-185) or the control, especially in living L. acidophilus-treated group. Furthermore, La KLDS 1.0738 strains could remarkably reduce transduction of TLR4 and inflammatory cytokine production, which was closely associated with up-regulation of miR-146a levels. MiR-146a inhibitor attenuated the alleviative effect of La KLDS 1.0738, indicating miR-146a might be a crucial mediator of L. acidophilus strains to reduce ß-Lg-induced inflammation in macrophages through TLR4 pathway. In conclusion, these observations highlighted that probiotics might regulate host miRNA levels to down-regulate TLR4/NF-κB-dependent inflammation. PRACTICAL APPLICATIONS: Cow's milk allergy (CMA) is one of the most common diseases of food allergy, which has a high prevalence in infants and young children. La KLDS 1.0738 has been shown to be effective in alleviating ß-Lg-induced allergic inflammation. Our study further found that treatment with La KLDS 1.0738 could suppress the TLR4/NF-κB signaling pathway via modulating miR-146a expression, thereby reducing the overexpression of downstream inflammatory factors. This study not only elucidates the specific pathway of La KLDS 1.0738 to relieve allergic inflammation, but also provides a new insight into the molecular mechanism for the remission and treatment of CMA by probiotics.