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Deposition of aggregated amyloid beta (Aβ) protein is considered to be a major causative factor that is associated with the development of oxidative stress and neuroinflammation in the pathogenesis of Alzheimer's disease (AD). Selenium nanoparticles (SeNPs) have been experimentally using for treatment of neurological disease due to their low toxicity, high bioavailability, and multiple bioactivities. This study was conducted to investigate the protective effects of biogenic SeNPs by Lactobacillus casei ATCC 393 against Aβ25–35-induced toxicity in PC12 cells and its association with oxidative stress and inflammation. The results showed that SeNPs had no cytotoxicity on PC12 cells. Moreover, SeNPs entered cells through cellular endocytosis, which effectively attenuated Aβ25–35-induced toxicity in PC12 cells. In addition, compared with Aβ25–35 model group, SeNP pretreatment significantly enhanced the antioxidant capacity, inhibited the overproduction of reactive oxygen species (ROS), effectively regulated the inflammatory response, decreased the activity of acetylcholinesterase, significantly reduced the expression level of caspase-1 and the ratio of Bcl-2/Bax, and upregulated the expression level of p53. Furthermore, compared with Aβ25–35 model group, SeNPs effectively promoted the phosphorylation of Akt and cAMP-response element-binding protein (CREB), and upregulated the expression level of brain-derived neurotrophic factor (BDNF). In addition, the Akt inhibitor (AKT inhibitor VIII, AKTi-1/2) could reverse the protective effects of SeNPs on PC12 cells. The Akt agonist (SC79) had a similar effect on PC12 cells as that of SeNPs. Overall, this study demonstrated that biogenic SeNPs can effectively alleviate the Aβ25–35-induced toxicity in PC12 cells via Akt/CREB/BDNF signaling pathway. [ABSTRACT FROM AUTHOR]

Vasoactive intestinal peptide (VIP) plays an important role in the neuro-endocrine-immune system. Mast cells (MCs) are important immune effector cells. This study was conducted to investigate the protective effect of L. casei ATCC 393 on Enterotoxigenic Escherichia coli (ETEC) K88-induced intestinal mucosal immune barrier injury and its association with VIP/MC signaling by in vitro experiments in cultures of porcine mucosal mast cells (PMMCs) and in vivo experiments using VIP receptor antagonist (aVIP) drug. The results showed that compared with the ETEC K88 and lipopolysaccharides (LPS)-induced model groups, VIP pretreatment significantly inhibited the activation of MCs and the release of β-hexosaminidase (β-hex), histamine and tryptase. Pretreatment with aVIP abolished the protective effect of L. casei ATCC 393 on ETEC K88-induced intestinal mucosal immune barrier dysfunction in C57BL/6 mice. Also, with the blocking of VIP signal transduction, the ETEC K88 infection increased serum inflammatory cytokines, and the numbers of degranulated MCs in ileum, which were decreased by administration of L. casei ATCC 393. In addition, VIP mediated the regulatory effect of L. casei ATCC 393 on intestinal microbiota in mice. These findings suggested that VIP may mediate the protective effect of L.casei ATCC 393 on intestinal mucosal immune barrier dysfunction via MCs. [ABSTRACT FROM AUTHOR]

Lactococcus lactis (L. lactis) NZ9000, which has been genetically modified, is the most commonly used host strain for nisin regulated gene expression. Selenium (Se) is an essential trace element in the diet of humans and animals important for the maintenance of health and growth. Biosynthesized Se nanoparticles (SeNPs) that use microorganisms as a vehicle are uniquely advantages in terms of low costs, low toxicity and high bioavailability. This study was aimed at preparing novel functionalized SeNPs by L. lactis NZ9000 through eco-friendly and economic biotechnology methods. Moreover, its physicochemical characteristics, antioxidant and anti-inflammatory activities were investigated. L. lactis NZ9000 synthesized elemental red SeNPs when co-cultivated with sodium selenite under anaerobic conditions. Biosynthesized SeNPs by L. lactis NZ9000 were mainly capped with polysaccharides and significantly alleviated the increase of malondialdehyde (MDA) concentration, the decrease of glutathione peroxidase (GPx) and total superoxide dismutase (T-SOD) activity in porcine intestinal epithelial cells (IPEC-J2) challenged by hydrogen peroxide (H2O2). SeNPs also prevented the H2O2-caused reduction of transepithelial electrical resistance (TEER) and the increase of FITC-Dextran fluxes across IPEC-J2. Moreover, SeNPs attenuated the increase of reactive oxygen species (ROS), the reduction of adenosine triphosphate (ATP) and the mitochondrial membrane potential (MMP) and maintained intestinal epithelial permeability in IPEC-J2 cells exposed to H2O2. In addition, SeNPs pretreatment alleviated the cytotoxicity of Enterotoxigenic Escherichia coli (ETEC) K88 on IPEC-J2 cells and maintained the intestinal epithelial barrier integrity by up-regulating the expression of Occludin and Claudin-1 and modulating inflammatory cytokines. Biosynthesized SeNPs by L. lactis NZ9000 are a promising selenium supplement with antioxidant and anti-inflammatory activities. [ABSTRACT FROM AUTHOR]

Ulcerative colitis (UC) is an inflammatory bowel disease (IBD) which is related to an immunological imbalance of the intestinal mucosa. Many clinical evidences indicate probiotics supplementation appears to be effective and safe in patients with UC. Vasoactive intestinal peptide (VIP) is an endogenous neuropeptide with multiple physiological and pathological effects. In this study, we investigated the protective effect of the combination of Lactobacillus casei ATCC 393 (L. casei ATCC 393) with VIP on dextran sodium sulfate (DSS)-induced UC in mice and the potential mechanism. The results showed that, compared with the control group, DSS treatment significantly shortened the colon length, caused inflammation and oxidative stress, and further resulted in the intestinal barrier dysfunction and gut microbiota dysbiosis. In addition, intervention with L. casei ATCC 393, VIP or L. casei ATCC 393 combined with VIP significantly reduced UC disease activity index. However, compared with L. casei ATCC 393 or VIP, L. casei ATCC 393 combined with VIP effectively relieved symptoms of UC by regulating immune response, enhancing antioxidant capacity, and regulating nuclear factor kappa-B (NF-κB) and nuclear factor erythroid-derived-2-like 2 (Nrf2) signaling pathways. In conclusion, this study suggests that L. casei ATCC 393 combined with VIP can effectively relieve DSS-induced UC, which is a promising treatment strategy for UC. [Display omitted] • L. casei ATCC 393 combined with VIP exert better anti-inflammatory effects than L. casei ATCC 393 or VIP in UC mice. • The mechanism is closely associated with NF-κB and Nrf2 signaling pathways. • L. casei ATCC 393 combined with VIP is a promising treatment strategy for UC. [ABSTRACT FROM AUTHOR]

The current studies have shown that the occurrence and development of chronic obstructive pulmonary disease (COPD) are closely related to the changes in gut health and its microenvironment, and even some gut diseases have significant clinical correlation with COPD. The dysbiosis of gut microbiota observed in COPD patients also suggests a potential bidirectional interaction between the gut and lung. Communication between the gut and lung may occur through circulating inflammatory cells, gut microbial metabolites, and circulating inflammatory mediators, but the mechanism of bidirectional communication between the gut and lung in COPD is still under study. Therefore, more research is still needed in this area. In this review, we summarize recent clinical studies and animal models on the role of the gut-lung axis in the occurrence and development of COPD and its mechanisms, so as to provide ideas for further research in this field. In addition, we also summarized the negative effects of COPD medication on gut microbiota and the gut microbiota risk factors for COPD and proposed the potential prevention and treatment strategies.

Microorganisms capable of converting toxic selenite into elemental selenium (Se 0 ) are considered an important and effective approach for bioremediation of Se contamination. In this study, we investigated the mechanism of reducing selenite to Se 0 and forming Se nanoparticles (SeNPs) by food-grade probiotic Lactobacillus casei ATCC 393 ( L. casei ATCC 393) through proteomics analysis. The results showed that selenite added during the exponential growth period of bacteria has the highest reduction efficiency, and 4.0 mM selenite decreased by nearly 95% within 72 h and formed protein-capped-SeNPs. Proteomics analysis revealed that selenite induced a significant increase in the expression of glutaredoxin, oxidoreductase, and ATP binding cassette (ABC) transporter, which can transport glutathione (GSH) and selenite. Selenite treatment significantly increased the CydC and CydD (putative cysteine and glutathione importer, ABC transporter) mRNA expression level, GSH content, and GSH reductase activity. Furthermore, supplementation with an additional GSH significantly increased the reduction rate of selenite, while GSH depletion significantly inhibited the reduction of selenite, indicating that GSH-mediated Painter-type reaction may be the main pathway of selenite reduction in L. casei ATCC 393. Moreover, nitrate reductase also participates in the reduction process of selenite, but it is not the primary factor. Overall, L. casei ATCC 393 effectively reduced selenite to SeNPs by GSH and nitrate reductase-mediated reduction pathway, and the GSH pathway played the decisive role, which provides an environmentally friendly biocatalyst for the bioremediation of Se contamination. IMPORTANCE Due to the high solubility and bioavailability of selenite, and its widespread use in industrial and agricultural production, it is easy to cause selenite to accumulate in the environment and reach toxic levels. Although the bacteria screened from special environments have high selenite tolerance, their safety has not been fully verified. It is necessary to screen out strains with selenite-reducing ability from nonpathogenic, functionally known, and widely used strains. Herein, we found food-grade probiotic L. casei ATCC 393 effectively reduced selenite to SeNPs by GSH and nitrate reductase-mediated reduction pathway, which provides an environmentally friendly biocatalyst for the bioremediation of Se contamination., Competing Interests: The authors declare no conflict of interest.

Nanoparticles (NPs), which have unique properties due to their extremely small size and high surface area to volume ratio, have attracted considerable attention and become an important tool for innovation in various fields. Traditionally, NPs are synthesized by physical and chemical processes, but these methods have high capital costs and energy demand, and involve the use of toxic and hazardous chemicals, which are prone to secondary pollution of the environment. In recent years, the use of microorganism-mediated methods has emerged as an alternative to traditional physical and chemical methods. The synthesis of NPs by microorganism has the advantages of non-toxicity, eco-friendliness, low-cost, reproducibility in production, easy amplification, and well-defined morphology. Probiotics are a kind of active microorganisms beneficial to the host. Compared with other microorganisms, probiotics are characterized by non-pathogenicity, rapid growth and regulation of gene expression, and produce a variety of proteins and enzymes involved in the synthesis of NPs. Therefore, the production of NPs using probiotics is an environmentally friendly and commercially attractive method, which provides new ideas and approaches for the application of NPs in the fields of biomedicine, agriculture and environmental remediation. This review aims to summarize the literature on the biosynthesis of NPs by probiotics and their synthetic mechanisms and applications., Competing Interests: Declaration of competing interest The authors declare no competing interests., (Copyright © 2022 Elsevier Inc. All rights reserved.)

Composite microecological agents have received widespread attention due to their advantageous properties, including safety, multiple effects, and low cost. This study was conducted to evaluate the protective effects of selenium (Se) nanoparticle (SeNP)-enriched Lactococcus lactis NZ9000 (L. lactis NZ9000-SeNPs) against enterotoxigenic Escherichia coli (ETEC) K88-induced intestinal barrier damage in C57BL/6 mice. The oral administration of L. lactis NZ9000-SeNPs significantly increased the villus height and the number of goblet cells in the ileum; reduced the levels of serum and ileal interleukin-1β (IL-1β), tumor necrosis factor alpha (TNF-α), and interferon gamma (IFN-γ); and increased the activities of thioredoxin reductase (TrxR) and glutathione peroxidase (GSH-Px) compared with the ETEC K88-infected group not treated with L. lactis NZ9000-SeNPs. In addition, L. lactis NZ9000-SeNPs significantly attenuated the reduction of the expression levels of occludin and claudin-1, dysbiosis of the gut microbiome, and activation of the Toll-like receptor (TLR)/nuclear factor kappa B (NF-κB)-mediated signaling pathway induced by ETEC K88. These findings suggested that L. lactis NZ9000-SeNPs may be a promising and safe Se supplement for food or feed additives. IMPORTANCE The beneficial effects of microecological agents have been widely proven. Se, which is a nutritionally essential trace element for humans and animals, is incorporated into selenoproteins that have a wide range of pleiotropic effects, ranging from antioxidant to anti-inflammatory effects. However, sodium selenite, a common addition form of Se in feed and food, has disadvantages such as strong toxicity and low bioavailability. We investigated the protective effects of L. lactis NZ9000-SeNPs against ETEC K88-induced intestinal barrier injury in C57BL/6 mice. Our results show that L. lactis NZ9000-SeNPs effectively alleviate ETEC K88-induced intestinal barrier dysfunction. This study highlights the importance of developing a promising and safe Se supplement for the substitution of sodium selenite applied in food, feed, and biomedicine.