Anti-inflammatory activity of surface layer protein SlpA of Lactobacillus acidophilus CICC 6074 in LPS-induced RAW 264.7 cells and DSS-induced mice colitis

Deciphering Microbiome, Transcriptome, and Metabolic Interactions in the Presence of Probiotic Lactobacillus acidophilus against Salmonella Typhimurium in a Murine Model

Salmonella enterica serovar Typhimurium (S. Typhimurium), a foodborne pathogen that poses significant public health risks to humans and animals, presents a formidable challenge due to its antibiotic resistance. This study explores the potential of Lactobacillus acidophilus (L. acidophilus 1.3251) probiotics as an alternative strategy to combat antibiotic resistance associated with S. Typhimurium infection. In this investigation, twenty-four BALB/c mice were assigned to four groups: a non-infected, non-treated group (CNG); an infected, non-treated group (CPG); a group fed with L. acidophilus but not infected (LAG); and a group fed with L. acidophilus and challenged with Salmonella (LAST). The results revealed a reduction in Salmonella levels in the feces of mice, along with restored weight and improved overall health in the LAST compared to the CPG. The feeding of L. acidophilus was found to downregulate pro-inflammatory cytokine mRNA induced by Salmonella while upregulating anti-inflammatory cytokines. Additionally, it influenced the expression of mRNA transcript, encoding tight junction protein, oxidative stress-induced enzymes, and apoptosis-related mRNA expression. Furthermore, the LEfSe analysis demonstrated a significant shift in the abundance of critical commensal genera in the LAST, essential for maintaining gut homeostasis, metabolic reactions, anti-inflammatory responses, and butyrate production. Transcriptomic analysis revealed 2173 upregulated and 506 downregulated differentially expressed genes (DEGs) in the LAST vs. the CPG. Functional analysis of these DEGs highlighted their involvement in immunity, metabolism, and cellular development. Kyoto Encyclopedia of Genes and Genome (KEGG) pathway analysis indicated their role in tumor necrosis factor (TNF), mitogen-activated protein kinase (MAPK), chemokine, Forkhead box O (FOXO), and transforming growth factor (TGF-β) signaling pathway. Moreover, the fecal metabolomic analysis identified 929 differential metabolites, with enrichment observed in valine, leucine, isoleucine, taurine, glycine, and other metabolites. These findings suggest that supplementation with L. acidophilus promotes the growth of beneficial commensal genera while mitigating Salmonella-induced intestinal disruption by modulating immunity, gut homeostasis, gut barrier integrity, and metabolism.

Lactiplantibacillus plantarum postbiotic protects against Salmonella infection in broilers via modulating NLRP3 inflammasome and gut microbiota

Salmonella infection is a major concern in poultry production which poses potential risks to food safety. Our previous study confirmed that Lactiplantibacillus plantarum (LP) postbiotic exhibited a strong antibacterial capacity on Salmonella in vitro. This study aimed to investigate the beneficial effects and underlying mechanism of LP postbiotic on Salmonella-challenged broilers. A total of 240 one-day-old male yellow-feathered broilers were pretreated with 0.8% deMan Rogosa Sharpe (MRS) medium or 0.8% LP postbiotic (LP cell-free culture supernatant, LPC) in drinking water for 28 d, and then challenged with 1×109 CFU Salmonella enterica serovar Enteritidis (SE). Birds were sacrificed 3 d postinfection. Results showed that LPC maintained the growth performance by increasing body weight (BW), average daily gain (ADG), and average daily feed intake (ADFI) in broilers under SE challenge. LPC significantly attenuated SE-induced intestinal mucosal damage. Specifically, it decreased the intestinal injury score, increased villus length and villus/crypt, regulated the expression of intestinal injury-related genes (Villin, matrix metallopeptidase 3 [MMP3], intestinal fatty acid-binding protein [I-FABP]), and enhanced tight junctions (zona occludens-1 [ZO-1] and Claudin-1). SE infection caused a dramatic inflammatory response, as indicated by the up-regulated concentrations of interleukin (IL)-1β, IL-6, TNF-α, and the downregulation of IL-10, while LPC pretreatment markedly reversed this trend. We then found that LPC inhibited the activation of NOD-like receptor thermal protein domain associated protein 3 (NLRP3) inflammasome by decreasing the gene expression of Caspase-1, IL-lβ, and IL-18. Furthermore, LPC suppressed NLRP3 inflammasome activation by inhibiting nuclear factor-kappa B (NF-κB) signaling pathway (the reduced levels of toll-like receptor 4 [TLR4], myeloid differentiation factor 88 [MyD88], and NF-κB). Finally, our results showed that LPC regulated gut microbiota by enhancing the percentage of Ligilactobacillus and decreasing Alistipes and Barnesiella. In summary, we found that LP postbiotic was effective to protect broilers against Salmonella infection, possibly through suppressing NLRP3 inflammasome and optimizing gut microbiota. Our study provides the potential of postbiotics on prevention of Salmonella infection in poultry.

Protective effects of oral administration of lactic acid bacteria strains against methylmercury-induced intestinal toxicity in a murine model

The utilization of lactic acid bacteria has been proposed to mitigate the burden of heavy metal exposure through processes probably involving chelation and reduced metal bioaccessibility. We evaluated the effects of daily intake of two strains of lactobacilli (Lactobacillus intestinalis LE1 or Lactobacillus johnsonii LE2) on intestinal toxicity during methylmercury (MeHg) exposure through drinking water (5 mg/L) for two months in mice. MeHg exposure resulted in inflammation and oxidative stress at the colon, as well as an increase in intestinal permeability accompanied by decreased fecal short-chain fatty acids (SCFA). The administration of the strains resulted in a differential protective effect that, based on their chelation capacity, supported the existence of additional mechanisms of action besides chelation. Both strains reduced IL-1β levels and oxidative stress, while LE1 lowered TNF-α, diminished MeHg-induced mucus over-secretion triggered by the IL-4/IL-13/STAT6 pathway, reduced intestinal permeability, and ameliorated inflammation and oxidative stress, probably by acting on the Keap1/Nrf2/ARE pathway. Administration of LE1 partially restored SCFA contents, which could be partly responsible for the positive effects of this strain in alleviating MeHg toxicity. These results demonstrate that lactobacilli strains can be useful tools in reducing the intestinal toxicity of MeHg, the main mercurial form conveyed by food.

The Protective Effect of Pumpkin and Fermented Whey Mixture against AFB1 and OTA Immune Toxicity In Vitro. A Transcriptomic Approach

SCOPE

The aim of the study is to investigate in Jurkat cells the possible beneficial effect of pumpkin (P) and fermented milk whey (FW) mixture against aflatoxin B1 (AFB1) and ochratoxin A (OTA) induced alterations in gene expression profile.

METHODS AND RESULTS

Human T cells are exposed for 7 days to digested bread extracts containing P-FW mixture along with AFB1 and OTA, individually and in combination. The results of RNA sequencing show that AFB1 P-FW exposure resulted in 34 differentially expressed genes (DEGs) while 3450 DEGs are found in OTA P-FW exposure and 3264 DEGs in AFB1-OTA P-FW treatment. Gene ontology analysis reveals biological processes and molecular functions related to immune system and inflammatory response. Moreover, PathVisio analysis points to eicosanoid signaling via lipoxygenase as the main pathway altered by AFB1 P-FW exposure whereas interferon signaling is the most affected pathway after OTA P-FW and AFB1-OTA P-FW treatments.

CONCLUSIONS

The mitigation of genes and inherent pathways typically associated with the inflammatory response suggest not only the anti-inflammatory and protective role of P-FW mixture but also their possible application in food industry to counteract AFB1 and OTA toxic effects on human and animal health.

Mucosal immunization with lactiplantibacillus plantarum-displaying recombinant SARS-CoV-2 epitopes on the surface induces humoral and mucosal immune responses in mice

BACKGROUND

The use of probiotic lactic acid bacteria as a mucosal vaccine vector is considered a promising alternative compared to the use of other microorganisms because of its "Generally Regarded as Safe" status, its potential adjuvant properties, and its tolerogenicity to the host. Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which causes coronavirus disease (COVID-19), is highly transmissible and pathogenic. This study aimed to determine the potential of Lactiplantibacillus plantarum expressing SARS-CoV-2 epitopes as a mucosal vaccine against SARS-CoV-2.

RESULTS

In this study, the possible antigenic determinants of the spike (S1-1, S1-2, S1-3, and S1-4), membrane (ME1 and ME2), and envelope (E) proteins of SARS-CoV-2 were predicted, and recombinant L. plantarum strains surface-displaying these epitopes were constructed. Subsequently, the immune responses induced by these recombinant strains were compared in vitro and in vivo. Most surface-displayed epitopes induced pro-inflammatory cytokines [tumor necrosis factor alpha (TNF-α and interleukin (IL)-6] and anti-inflammatory cytokines (IL-10) in lipopolysaccharide-induced RAW 264.7, with the highest anti-inflammatory to pro-inflammatory cytokine ratio in the S1-1 and S1-2 groups, followed by that in the S1-3 group. When orally administered of recombinant L. plantarum expressing SARS-CoV-2 epitopes in mice, all epitopes most increased the expression of IL-4, along with induced levels of TNF-α, interferon-gamma, and IL-10, specifically in spike protein groups. Thus, the surface expression of epitopes from the spike S1 protein in L. plantarum showed potential immunoregulatory effects, suggesting its ability to potentially circumvent hyperinflammatory states relevant to monocyte/macrophage cell activation. At 35 days post immunization (dpi), serum IgG levels showed a marked increase in the S1-1, S1-2, and S1-3 groups. Fecal IgA levels increased significantly from 21 dpi in all the antigen groups, but the boosting effect after 35 dpi was explicitly observed in the S1-1, S1-2, and S1-3 groups. Thus, the oral administration of SARS-CoV-2 antigens into mice induced significant humoral and mucosal immune responses.

CONCLUSION

This study suggests that L. plantarum is a potential vector that can effectively deliver SARS-CoV-2 epitopes to intestinal mucosal sites and could serve as a novel approach for SARS-CoV-2 mucosal vaccine development.

S-layer proteins as immune players: tales from pathogenic and non-pathogenic bacteria

In bacteria, as in other microorganisms, surface compounds interact with different pattern recognition receptors expressed by host cells, which usually triggers a variety of cellular responses that result in immunomodulation. The S-layer is a two-dimensional macromolecular crystalline structure formed by (glyco)-protein subunits that covers the surface of many species of Bacteria and almost all Archaea. In Bacteria, the presence of S-layer has been described in both pathogenic and non-pathogenic strains. As surface components, special attention deserves the role that S-layer proteins (SLPs) play in the interaction of bacterial cells with humoral and cellular components of the immune system. In this sense, some differences can be predicted between pathogenic and non-pathogenic bacteria. In the first group, the S-layer constitutes an important virulence factor, which in turn makes it a potential therapeutic target. For the other group, the growing interest to understand the mechanisms of action of commensal microbiota and probiotic strains has prompted the studies of the role of the S-layer in the interaction between the host immune cells and bacteria bearing this surface structure. In this review, we aim to summarize the main latest reports and the perspectives of bacterial SLPs as immune players, focusing on those from pathogenic and commensal/probiotic most studied species.

Inflammatory Bowel Diseases and Gut Microbiota

Inflammatory bowel disease (IBD) is an inflammatory disease of the gastrointestinal tract, the incidence of which has rapidly increased worldwide, especially in developing and Western countries. Recent research has suggested that genetic factors, the environment, microbiota, and immune responses are involved in the pathogenesis; however, the underlying causes of IBD are unclear. Recently, gut microbiota dysbiosis, especially a decrease in the abundance and diversity of specific genera, has been suggested as a trigger for IBD-initiating events. Improving the gut microbiota and identifying the specific bacterial species in IBD are essential for understanding the pathogenesis and treatment of IBD and autoimmune diseases. Here, we review the different aspects of the role played by gut microbiota in the pathogenesis of IBD and provide a theoretical basis for modulating gut microbiota through probiotics, fecal microbiota transplantation, and microbial metabolites.

Inflammatory bowel disease therapeutic strategies by modulation of the microbiota: how and when to introduce pre-, pro-, syn-, or postbiotics?

Inflammatory bowel diseases (IBD), a heterogeneous group of inflammatory conditions that encompass both ulcerative colitis and Crohn's disease, represent a major public health concern. The etiology of IBD is not yet fully understood and no cure is available, with current treatments only showing long-term effectiveness in a minority of patients. A need to increase our knowledge on IBD pathophysiology is growing, to define preventive measures, to improve disease outcome, and to develop new effective and lasting treatments. IBD pathogenesis is sustained by aberrant immune responses, associated with alterations of the intestinal epithelial barrier (IEB), modifications of the enteric nervous system, and changes in microbiota composition. Currently, most of the treatments target the inflammation and the immune system, but holistic approaches targeting lifestyle and diet improvements are emerging. As dysbiosis is involved in IBD pathogenesis, pre-, pro-, syn-, and postbiotics are used/tested to reduce the inflammation or strengthen the IEB. The present review will resume these works, pointing out the stage of life, the duration, and the environmental conditions that should go along with microbiota or microbiota-derived treatments.

Different Effects of Different Lactobacillus acidophilus Strains on DSS-Induced Colitis

Inflammatory bowel disease (IBD) is a worldwide chronic intestinal inflammatory immune-related disease. In this study, mice with dextran sulfate sodium (DSS)-induced colitis were used to evaluate the effect of Lactobacillus acidophilus on colitis. The results revealed that L. acidophilus CCFM137 and FAHWH11L56 show potential for relieving colitis symptoms, while L. acidophilus FGSYC48L79 did not show a protective effect. Moreover, L. acidophilus NCFM and FAHWH11L56 showed similar effects on various indicators of DSS-induced colitis, increasing the IL-10 and IL-17 in the colon, and modifying the CCL2/CCR2 axis and CCL3/CCR1 axis. For L. acidophilus CCFM137, its effects on colitis were different from the above two strains. Moreover, L. acidophilus FGSYC48L79 had negative effects on colitis by increasing the abundance of harmful bacteria in the gut microbiota and may promote the signaling of chemokines and their receptors. This may be related to its special genome compared to the other strains.

Protective effect of surface-layer proteins from four Lactobacillus strains on tumor necrosis factor-α-induced intestinal barrier dysfunction

BACKGROUND

The intestinal epithelium is considered the first defense protection against exogenous harmful substances, playing an indispensable role in regulating intestinal health. The protection offered by surface-layer proteins (Slps) from different Lactobacillus strains on an impaired intestinal barrier was investigated in this study.

RESULTS

Four Slps pre-incubated for 6 h significantly prevented the reduced transepithelial electrical resistance value and increased paracellular permeability in tumor necrosis factor (TNF)-α-induced Caco-2 monolayers. TNF-α induced lower protein expression of occludin and zonula occludens-1, and abnormal distributions of occludin and zonula occludens-1 were ameliorated by four Slps as well. Additionally, four Slps weakened TNF-α-evoked interleukin-8 secretion and nuclear factor-κB activation.

CONCLUSION

Four Slps from different strains prevent the intestinal barrier from TNF-α-induced dysfunction through blocking the nuclear factor-κB signaling pathway. © 2022 Society of Chemical Industry.

Structure and Anti-Inflammation Potential of Lipoteichoic Acids Isolated from Lactobacillus Strains

Lactobacillus are normal inhabitants of the gastrointestinal tract and confer a variety of health effects. Lipoteichoic acid (LTA), an amphiphilic substance located in the cell membrane, is a key molecule in probiotic–host crosstalk. Through the characterization of structural characteristics of LTA molecules derived from Lactobacillus plantarum A3, Lactobacillus reuteri DMSZ 8533, and Lactobacillus acidophilus CICC 6074, there exists some heterogeneity in LTA molecules, which perhaps contributes to the distinguishable adhesion properties of Lactobacillus strains based on fluorescence microscopy observations. In LPS-induced RAW 264.7 cells, LTAs derived from three Lactobacillus strains obviously alleviated inflammatory responses as evidenced by the altered inflammatory cytokine levels of TNF-α, IL-6, and IL-10. Western blotting demonstrated that L. reuteri LTA blocked LPS-triggered expression of the MAPK and NF-κB pathways. The findings further validated that LTA is an important effector molecule and deserves further consideration as an alternative therapeutic for ulcerative colitis treatment.

Effect of Surface Layer Proteins Derived from Paraprobiotic Kefir Lactic Acid Bacteria on Inflammation and High-Fat Diet-Induced Obesity

The antiobesity action of nonviable probiotic lactic acid bacteria (PLAB) may be attributed to bacterial cellular components recognized by host cells. The anti-inflammation and antiobesity properties of surface layer proteins (SLPs) that are cellular components isolated from kefir PLAB were determined in macrophage RAW 264.7 cells and obese mice. Kefir SLPs significantly decreased secretion of IL-6 and production of NF-kB p65 protein by LPS-stimulated RAW 264.7 cells in a dose-response manner. C57BL/6J mice were fed a high-fat (HF) diet with oral administration of either saline (CON) or kefir SLPs for 6 weeks. SLPs significantly improved body weight gain and adipose tissue weight, plasma triglyceride concentrations, and insulin resistance. Profiling of adipocyte gene expression showed that the antiobesity effect was significantly related to the expression of genes associated with adipogenesis, autophagy, and inflammatory/immune response, and fatty acid oxidation. Taken together, SLPs are a novel bioactive component in kefir PLABs to target obesity and obesity-related disorders.

SlpB Protein Enhances the Probiotic Potential of L. lactis NCDO 2118 in Colitis Mice Model

Bacteria used in the production of fermented food products have been investigated for their potential role as modulators of inflammation in gastrointestinal tract disorders such as inflammatory bowel diseases (IBD) that cause irreversible changes in the structure and function of gut tissues. Ulcerative colitis (UC) is the most prevalent IBD in the population of Western countries, and it is marked by symptoms such as weight loss, rectal bleeding, diarrhea, shortening of the colon, and destruction of the epithelial layer. The strain Propionibacterium freudenreichii CIRM-BIA 129 recently revealed promising immunomodulatory properties that greatly rely on surface-layer proteins (Slp), notably SlpB. We, thus, cloned the sequence encoding the SlpB protein into the pXIES-SEC expression and secretion vector, and expressed the propionibacterial protein in the lactic acid bacterium Lactococcus lactis NCDO 2118. The probiotic potential of L. lactis NCDO 2118 harboring pXIES-SEC:slpB (L. lactis-SlpB) was evaluated in a UC-mice model induced by Dextran Sulfate Sodium (DSS). During colitis induction, mice receiving L. lactis-SlpB exhibited reduced severity of colitis, with lower weight loss, lower disease activity index, limited shortening of the colon length, and reduced histopathological score, with significant differences, compared with the DSS group and the group treated with L. lactis NCDO 2118 wild-type strain. Moreover, L. lactis-SlpB administration increased the expression of genes encoding tight junction proteins zo-1, cln-1, cln-5, ocln, and muc-2 in the colon, increased IL-10 and TGF-β, and decreased IL-17, TNF-α, and IL-12 cytokines in the colon. Therefore, this work demonstrates that SlpB recombinant protein is able to increase the probiotic potential of the L. lactis strain to alleviate DSS-induced colitis in mice. This opens perspectives for the development of new approaches to enhance the probiotic potential of strains by the addition of SlpB protein.

Ameliorative Effect of Surface Proteins of Probiotic Lactobacilli in Colitis Mouse Models

The increase in concern from viable cells of probiotics specifically in acute inflammatory conditions has led to the emergence of the concept of postbiotics as a safer alternative therapy in the field of health and wellness. The aim of the present study was to evaluate the efficacy of surface proteins from three probiotic strains in dextran sodium sulfate and trinitrobenzenesulphonic acid = induced colitis mouse models. The molecular weight of total surface proteins extracted from the three probiotic strains ranged from ∼25 to ∼250 kDa with the presence of negligible levels of endotoxins. Surface layer proteins (SLPs) (∼45 kDa) were found to be present only in the Lactobacillus acidophilus NCFM strain. In the in vivo study, significant differences were not observed in the weight loss and general appetite, however, the decrease in colon length was apparent in TNBS colitis control mice. Further, the administration of these surface proteins significantly reversed the histopathological damages induced by the colitogens and improved the overall histological score. The oral ingestion of these surface proteins also led to a decrease in myeloperoxidase activity and TNF-α expression while the IL-10 levels significantly increased for the strain NCFM followed by MTCC 5690 and MTCC 5689. Overall, the present study signifies the ameliorative role of probiotic surface proteins in colitis mice, thereby, offering a potential and safer alternative for the management of inflammatory bowel disorders.

Comparative Genomics and Specific Functional Characteristics Analysis of Lactobacillus acidophilus

Lactobacillus acidophilus is a common kind of lactic acid bacteria usually found in the human gastrointestinal tract, oral cavity, vagina, and various fermented foods. At present, many studies have focused on the probiotic function and industrial application of L. acidophilus. Additionally, dozens of L. acidophilus strains have been genome sequenced, but there has been no research to compare them at the genomic level. In this study, 46 strains of L. acidophilus were performed comparative analyses to explore their genetic diversity. The results showed that all the L. acidophilus strains were divided into two clusters based on ANI values, phylogenetic analysis and whole genome comparison, due to the difference of their predicted gene composition of bacteriocin operon, CRISPR-Cas systems and prophages mainly. Additionally, L. acidophilus was a pan-genome open species with a difference in carbohydrates utilization, antibiotic resistance, EPS operon, surface layer protein operon and other functional gene composition. This work provides a better understanding of L. acidophilus from a genetic perspective, and offers a frame for the biotechnological potentiality of this species.

Anti-Inflammatory Effects of Mytilus coruscus Polysaccharide on RAW264.7 Cells and DSS-Induced Colitis in Mice

Considerable literature has been published on polysaccharides, which play a critical role in regulating the pathogenesis of inflammation and immunity. In this essay, the anti-inflammatory effect of Mytilus coruscus polysaccharide (MP) on lipopolysaccharide-stimulated RAW264.7 cells and a dextran sulfate sodium (DSS)-induced ulcerative colitis model in mice was investigated. The results showed that MP effectively promoted the proliferation of RAW264.7 cells, ameliorated the excessive production of inflammatory cytokines (TNF-α, IL-6, and IL-10), and inhibited the activation of the NF-κB signaling pathway. For DSS-induced colitis in mice, MP can improve the clinical symptoms of colitis, inhibit the weight loss of mice, reduce the disease activity index, and have a positive effect on the shortening of the colon caused by DSS, meliorating intestinal barrier integrity and lowering inflammatory cytokines in serum. Moreover, MP makes a notable contribution to the richness and diversity of the intestinal microbial community, and also regulates the structural composition of the intestinal flora. Specifically, mice treated with MP showed a repaired Firmicutes/Bacteroidetes ratio and an increased abundance of some probiotics like Anaerotruncus, Lactobacillus, Desulfovibrio, Alistipe, Odoribacter, and Enterorhabdus in colon. These data suggest that the MP could be a promising dietary candidate for enhancing immunity and protecting against ulcerative colitis.

Anti-inflammatory effect of a polysaccharide fraction from Craterellus cornucopioides in LPS-stimulated macrophages

Immunocytes-involved inflammation is considered to modulate the damage in various diseases. Oxidative stress is initiated by oxidative agents such as LPS and ROS, which are strongly involved in chronic inflammation. Our previous study found that a polysaccharide fraction from Craterellus cornucopioides (CCPP-1) showed good antioxidant activity. However, the anti-inflammatory effect of CCPP-1 was still elusive. The objective of this study was to evaluate the anti-inflammatory activity of CCPP-1 and its potential mechanism in LPS-stimulated RAW264.7 macrophages. The results showed that CCPP-1 could inhibit LPS-induced ROS and NO accumulation. Additionally, CCPP-1 could decrease pro-inflammatory cytokines production (TNF-α, IL-1β, and IL-18) and inflammatory mediator (iNOS) expression, which might be associated with its capacity to inhibit NF-κB signaling pathway and NLRP3 inflammasome activation. Therefore, this study suggested that CCPP-1 had an ameliorative effect on the inflammation response and was potential to develop into functional food for treating chronic inflammation. PRACTICAL APPLICATIONS: Craterellus cornucopioides is an edible fungus widely distributed in Southwestern China. It was reported that C. cornucopioides polysaccharide (CCPP-1), as important active ingredient, showed good antioxidant activity. However, the anti-inflammatory effect was still elusive. This study showed that CCPP-1 possessed anti-inflammatory activity. The molecular mechanism might be associated with its capacity to inhibit NF-κB signaling pathway and NLRP3 inflammasome activation. Therefore, polysaccharides from C. cornucopioides have potential to develop into functional food to combat inflammatory condition and thus indirectly halt the progression of various inflammatory response-related chronic diseases.

Protection of surface layer protein from Enterococcus faecium WEFA23 against Listeria monocytogenes CMCC54007 infection by modulating intestinal permeability and immunity

Enterococcus faecium WEFA23 was previously found effectively against adherence and colonization of Listeria monocytogenes CMCC54007, which might be closely related to its surface layer protein (SLP). In this study, the protective of SLP of E. faecium WEFA23 against infection of L. monocytogenes CMCC54007 was systemically investigated. In vitro assay showed that SLP actively inhibited L. monocytogenes internalization into Caco-2 cell line, with decreasing mRNA level of pro-inflammation cytokines and virulence factors and restoring destroyed intestinal barrier. In vivo assay through excluding SLP of E. faecium WEFA23 by 5 M LiCl represented that SLP increased body weight, reduced mortality and cell counts of L. monocytogenes CMCC54007 in tissues of mice. Further researches showed that SLP protected against L. monocytogenes CMCC54007 infection by modulation of intestinal permeability and immunity, namely, it decreased fluorescein isothiocyanate (FITC)-Dextran in serum, ameliorated destroyed colon structure, and increased number of goblet cells and protein level of TJ protein (Claudin-1, Occludin, and ZO-1) in colon. For immunity, SLP decreased number of CD4⁺ and CD8⁺ T cells in liver, mRNA level, and content of pro-inflammatory factors IL-6, IL-1β, IFN-γ ,TNF-α, and NO, and restored the structure of liver and spleen. Key Points•SLP of E. faecium inhibited L. monocytogenes internalization and colonization•SLP of E. faecium ameliorated host intestinal barrier dysfunction•SLP of E. faecium decreased pro-inflammatory cytokines and cells.

Coating function and stabilizing effects of surface layer protein from Lactobacillus acidophilus ATCC 4356 on liposomes

Surface layer proteins (SLPs) are crystalline arrays in the outermost layer of cell envelope in many archaea and bacteria. SLPs subunits have the ability to reassemble on the surface of lipid layers. In this work, the SLP from Lactobacillus acidophilus ATCC 4356 was extracted and reassembled on the surface of positively charged liposomes composed of dipalmitoyl phosphatidylcholine, cholesterol and octadecylamine. Zeta potentials and particle size were determined to describe the adsorption process of SLP on liposomes. The liposomes completely coated with SLP were observed by transmission electron microscope. To investigate the stabilizing effects of SLP on liposomes, carboxyfluorescein (CF) was encapsulated and its leakage was determined as an evaluation index. The results showed that the L. acidophilus ATCC 4356 SLP significantly (P < 0.05) increased the stability of the liposomes in the course of thermal challenge. Furthermore, SLP was able to reduce the aggregation of liposomes in serum. Storage stability of liposomes was performed at 25 °C, 4 °C and -20 °C for 90 days. And the SLP-coated liposomes released less CF than the control liposomes during storage at the three evaluated temperatures. Our findings extended the application field of Lactobacillus SLPs and introduced a novel nanocarrier system with good chemical stability.

Evolutionary concepts in the functional biotics arena: a mini-review

Over the years, the attempts to elucidate the role of beneficial microorganisms in shaping human health are becoming fairly apparent. The functional impact conferred by such microbes is not only transmitted by viable cells or their metabolites but also through non-viable cells. Extensive research to unveil the protective action of such wonder bugs has resulted in categorizing the beneficial microflora and their bioactive metabolites into a variety of functional biotic concepts based on their intended applications in various forms. In the modern era, these are often termed as probiotics, prebiotics, synbiotics, postbiotics, next-generation probiotics, psychobiotics, oncobiotics, pharmabiotics, and metabiotics. Currently, the concept of traditional probiotics is being widened to include microbes beyond lactic acid bacteria. Indeed, this diversification has broadened the functional food portfolio from food to pharmaceuticals. In this context, the present review aims to summarize the existing biotic concepts and their differences thereof.

Surface-layer protein produced by Lactobacillus crispatus JCM 2009 ameliorates lipopolysaccharide-induced inflammation through autophagy cross-talk with the NF-κB signaling pathway

In recent years, studies on immunomodulation by surface-layer proteins (Slps) have mainly focused on Lactobacillus acidophilus, there is little information on Slp from L. crispatus and its intestinal immunomodulatory mechanisms in macrophages. In our study, the anti-inflammatory actions of Slp derived from L. crispatus JCM 2009 and its related molecular mechanisms were investigated. We initially found that incubation with Slp (5-10 μg/mL) for 4 h significantly inhibited nitric oxide (NO) and prostaglandin E₂ (PGE₂) production in LPS-stimulated RAW264.7 cells (P < 0.001). We then found that Slp inhibited the inflammatory response by regulating the PI3K/AKT/mTOR signaling pathway and activating autophagy in lipopolysaccharide (LPS)-stimulated RAW264.7 cells. Furthermore, ELISA and Western blotting results demonstrated that the NF-κB signaling pathway positively regulated autophagic activity to inhibit the productions of PGE₂ and NO during this inflammatory response. And p65 was identified as a potentially important NF-κB signaling pathway molecule mediating the effects of Slp on the LPS-induced inflammatory response in RAW264.7 cells. Our findings provide the novel perspective that Slp exerts its anti-inflammatory effects through the activation of autophagy, making it a promising bioactive ingredient for the development of functional foods.

Quantitative Phosphoproteomics of Milk Fat Globule Membrane in Human Colostrum and Mature Milk: New Insights into Changes in Protein Phosphorylation during Lactation

Phosphorylation is a widespread posttranslational protein modification and is important in various biological processes. However, milk fat globule membrane (MFGM) phosphoproteins have not been explored systematically in human milk. Here, we used quantitative phosphoproteomics to analyze phosphorylation sites in human MFGM proteins and their differences at different stages of lactation; 305 phosphorylation sites on 170 proteins and 269 phosphorylation sites on 170 proteins were identified in colostrum and mature MFGM, respectively. Among these, 71 phosphorylation sites on 48 proteins were differentially expressed between the different stages of lactation. Osteopontin in human MFGM was the most heavily phosphorylated protein, with a total of 39 identified phosphorylation sites. Our results shed light on phosphorylation sites, composition, and biological functions of MFGM phosphoproteins in human colostrum and mature milk, and provide novel insights into the crucial roles of protein phosphorylation during infant development.

Effect of Lactobacillus acidophilus CICC 6074 S-Layer Protein on Colon Cancer HT-29 Cell Proliferation and Apoptosis

The objective of this research was to investigate the effects of Lactobacillus acidophilus CICC 6074 S-layer protein on the viability, adhesion, cell cycle, and apoptosis of human colon cancer HT-29 cells and to explore their molecular mechanism of tumor suppression. The S-layer protein at doses of 0, 25, 50, and 100 mg/L significantly suppressed the proliferation of HT-29 cells. The S-layer protein exerts its cytotoxic activities against colon cancer HT-29 cells by arresting the cell cycle in the G1 phase through upregulating the expression of p53, p21, and p16 and downregulating the expression of CDK1 (cyclin-dependent kinases) and cyclin B. Morphological changes were further observed by transmission electron microscopy, and the cells treated with the S-layer protein showed obvious characteristic changes of apoptosis including chromatin condensation, nuclear fragmentation, vacuoles, and so on. Furthermore, our mechanism studies indicated that the S-layer protein may induce HT-29 cell apoptosis through the death receptor apoptotic pathway and mitochondrial pathway and impede cell invasion by inhibiting the synthesis of the PI3K/AKT pathway and FasL. These results demonstrated that the L. acidophilus CICC 6074 S-layer protein may be a potential anticarcinogenic agent.

Collagen Peptides Isolated from Salmo salar and Tilapia nilotica Skin Accelerate Wound Healing by Altering Cutaneous Microbiome Colonization via Upregulated NOD2 and BD14

Collagen peptides can promote wound healing and are closely related to microbiome colonization. We investigated the relationship among collagen peptides, wound healing, and wound microflora colonization by administering the murine wound model with Salmo salar skin collagen peptides (Ss-SCPs) and Tilapia nilotica skin collagen peptides (Tn-SCPs). We analyzed the vascular endothelial growth factor (VEGF), fibroblast growth factors (β-FGF), pattern recognition receptor (NOD2), antimicrobial peptides (β-defence14, BD14), proinflammatory (TNF-α, IL-6, and IL-8) and anti-inflammatory (IL-10) cytokines, macrophages, neutrophil infiltration levels, and microbial communities in the rat wound. The healing rates of the Ss-SCP- and Tn-SCP-treated groups were significantly accelerated, associated with decreased TNF-α, IL-6, and IL-8 and upregulated BD14, NOD2, IL-10, VEGF, and β-FGF. Accelerated healing in the collagen peptide group shows that the wound microflora such as Leuconostoc, Enterococcus, and Bacillus have a positive effect on wound healing (P < 0.01). Other microbiome species such as Stenotrophomonas, Bradyrhizobium, Sphingomonas, and Phyllobacterium had a negative influence and decreased colonization (P < 0.01). Altogether, these studies show that collagen peptide could upregulate wound NOD2 and BD14, which were implicated in microflora colonization regulation in the wound tissue and promoted wound healing by controlling the inflammatory reaction and increasing wound angiogenesis and collagen deposition.

A surface-layer protein from Lactobacillus acidophilus NCFM induces autophagic death in HCT116 cells requiring ROS-mediated modulation of mTOR and JNK signaling pathways

A surface-layer protein (Slp) derived from Lactobacillus acidophilus NCFM has been reported to possess multiple biological properties, including anti-inflammatory, inhibition of apoptosis in pathogen-invaded HT-29 cells and oxidative stress relief. However, its anti-tumor ability and underlying molecular mechanism are unknown. Here, we report that Slp suppresses cell proliferation and induces autophagic cell death in HCT116 cells. Accumulation of Beclin-1 and microtubule-associated protein 1 light chain 3 from II (LC3-II), and the degradation of p62 were observed when cells were treated with various concentrations of Slp (25, 50, 100 μg mL-1) for 24 h. We also found that the mammalian targets of rapamycin (mTOR) and c-Jun N-terminal kinase (JNK) signaling pathways were crucial mediators regulating Slp-induced autophagic cell death. Additionally, treatment with Slp resulted in the obvious formation of reactive oxygen species (ROS). SP600125, a JNK inhibitor, and N-acetylcysteine (NAC), a ROS inhibitor, attenuated Slp-induced autophagic cell death in HCT116 cells. Furthermore, NAC was found to prevent Slp-induced p70 and JNK phosphorylation. Taken together, our results suggest a novel mechanism of action of Slp induced autophagy, acting simultaneously through the ROS-mediated mTOR and JNK signaling pathways in HCT116 colon cancer cells.

Effect of soybean oligopeptide on the growth and metabolism of Lactobacillus acidophilus JCM 1132

Soybean protein (Pro) and soybean oligopeptide (Pep) were subjected to simulated digestion in vitro to study the effect of Pep on the growth and metabolism of Lactobacillus acidophilus JCM 1132. First, the molecular weight distribution differences of samples before and after digestion were compared, and the samples were used to replace the nitrogen source components in the culture media. Then, the viable cell numbers, lactic acid and acetic acid content, differential metabolites, and metabolic pathways during the culturing process were measured. Results showed that the digested soybean oligopeptide (dPep) was less efficient than MRS medium in promoting the growth, but by increasing the content of the intermediates during the tricarboxylic acid (TCA) cycle, its metabolic capacity was significantly improved. Besides, due to the low molecular weight of dPep, it can be better transported and utilized. And dPep significantly strengthened the amino acid metabolism and weakened the glycerol phospholipid metabolism, so the ability of dPep in promoting the growth and metabolism of Lactobacillus acidophilus JCM 1132 is higher than the digested soybean protein (dPro).

Exploring the effect of soybean oligopeptide on the growth and metabolism of Lactobacillus acidophilus JCM 1132 by metabolomics.