Escherichia Coli Nissle 1917 Research Articles

Non-pathogenic Trojan horse Nissle1917 triggers mitophagy through PINK1/Parkin pathway to discourage colon cancer

Bacteria-mediated antitumor therapy has gained widespread attention for its innate tumor-targeting capability and excellent immune activation properties. Nevertheless, the clinical approval of bacterial therapies remains elusive primarily due to the formidable challenge of balancing safety with enhancing in vivo efficacy. In this study, leveraging the probiotic Escherichia coli Nissle1917 (EcN) emerges as a promising approach for colon cancer therapy, offering a high level of safety attributed to its lack of virulence factors and its tumor-targeting potential owing to its obligate anaerobic nature. Specifically, we delineate the erythrocyte (RBC) membrane-camouflaged EcN, termed as Trojan horse EcN@RBC, which triggers apoptosis in tumor cells by mitigating mitochondrial membrane potential (MMP) and subsequently activating the PINK1/Parkin pathway associated with mitophagy. Concurrently, the decline in MMP induced by mitophagy disrupts the mitochondrial permeability transition pore (MPTP), leading to the release of Cytochrome C and subsequent apoptosis induction. Moreover, synergistic effects were observed through the combination of the autophagy activator rapamycin, bolstering the antitumor efficacy in vivo. These findings offer novel insights into probiotic-mediated antitumor mechanisms and underscore the therapeutic potential of EcN@RBC for colon cancer patients.

Alginate-based injectable probiotic/squid ink composite hydrogels for accelerated wound healing of MRSA infected abscess through photothermally synergized probiotic therapy

Methicillin-resistant Staphylococcus aureus (MRSA) infections pose great challenges to skin wound care due to the severe drug resistance developed in the clinic. There is an urgent need to exploit next-generation bactericidal therapeutics that are both antibiotic-free and multifunctional for enhanced wound healing. Herein, we designed a Ca2+-crosslinked alginate hydrogel (EcNSIN@Alg) containing two naturally derived bioactive components, probiotics Escherichia coli Nissle1917 (EcN) and Squid ink nanoparticles (SIN), to treat MRSA-infected wounds. The injectable composite hydrogel displayed excellent biocompatibility, photothermal antibacterial activity, and reactive oxygen species (ROS) scavenging property. Importantly, the probiotic EcN can enhance the photothermal SIN to promote immune regulatory activities, shifting pro-inflammatory macrophages (M1) to anti-inflammatory macrophages (M2). In an MRSA-infected abscess model, EcNSIN@Alg can reduce the expression level of wound inflammatory factors and ROS, increase the number of anti-inflammatory macrophages, accelerate collagen deposition and promote wound healing. This work offers a new perspective on developing safe, antibiotic-free, multifunctional bactericides using fully bioderived materials, with potential applications in clinical practice.

Extracellular Vesicles of the Probiotic Escherichia coli Nissle 1917 Reduce PepT1 Levels in IL-1β-Treated Caco-2 Cells via Upregulation of miR-193a-3p.

PepT1, a proton-coupled oligopeptide transporter, is crucial for intestinal homeostasis. It is mainly expressed in small intestine enterocytes, facilitating the absorption of di/tri-peptides from dietary proteins. In the colon, PepT1 expression is minimal to prevent excessive responses to proinflammatory peptides from the gut microbiota. However, increased colonic PepT1 is linked to chronic inflammatory diseases and colitis-associated cancer. Despite promising results from animal studies on the benefits of extracellular vesicles (EVs) from beneficial gut commensals in treating IBD, applying probiotic EVs as a postbiotic strategy in humans requires a thorough understanding of their mechanisms. Here, we investigate the potential of EVs of the probiotic Nissle 1917 (EcN) and the commensal EcoR12 in preventing altered PepT1 expression under inflammatory conditions, using an interleukin (IL)-1-induced inflammation model in Caco-2 cells. The effects are evaluated by analyzing the expression of PepT1 (mRNA and protein) and miR-193a-3p and miR-92b, which regulate, respectively, PepT1 mRNA translation and degradation. The influence of microbiota EVs on PepT1 expression is also analyzed in the presence of bacterial peptides that are natural substrates of colonic PepT1 to clarify how the regulatory mechanisms function under both physiological and pathological conditions. The main finding is that EcN EVs significantly decreases PepT1 protein via upregulation of miR-193a-3p. Importantly, this regulatory effect is strain-specific and only activates in cells exposed to IL-1β, suggesting that EcN EVs does not control PepT1 expression under basal conditions but can play a pivotal role in response to inflammation as a stressor. By this mechanism, EcN EVs may reduce inflammation in response to microbiota in chronic intestinal disorders by limiting the uptake of bacterial proinflammatory peptides.

Non-native Pathway Engineering with CRISPRi for Carbon Dioxide Assimilation and Valued 5-Aminolevulinic Acid Synthesis in Escherichia coli Nissle.

Carbon dioxide emission and acidification during chemical biosynthesis are critical challenges toward microbial cell factories' sustainability and efficiency. Due to its acidophilic traits among workhorse lineages, the probiotic Escherichia coli Nissle (EcN) has emerged as a promising chemical bioproducer. However, EcN lacks a CO2-fixing system. Herein, EcN was equipped with a simultaneous CO2 fixation system and subsequently utilized to produce low-emission 5-aminolevulinic acid (5-ALA). Two different artificial CO2-assimilating pathways were reconstructed: the novel ribose-1,5-bisphosphate (R15P) route and the conventional ribulose-5-phosphate (Ru5P) route. CRISPRi was employed to target the pfkAB and zwf genes in order to redirect the carbon flux. As expected, the CRISPRi design successfully strengthened the CO2 fixation. The CO2-fixing route via R15P resulted in high biomass, while the engineered Ru5P route acquired the highest 5-ALA and suppressed the CO2 release by 77%. CO2 fixation during 5-ALA production in EcN was successfully synchronized through fine-tuning the non-native pathways with CRISPRi.

Modulation of Serotonin-Related Genes by Extracellular Vesicles of the Probiotic Escherichia coli Nissle 1917 in the Interleukin-1β-Induced Inflammation Model of Intestinal Epithelial Cells.

Inflammatory bowel disease (IBD) is a chronic inflammatory condition involving dysregulated immune responses and imbalances in the gut microbiota in genetically susceptible individuals. Current therapies for IBD often have significant side-effects and limited success, prompting the search for novel therapeutic strategies. Microbiome-based approaches aim to restore the gut microbiota balance towards anti-inflammatory and mucosa-healing profiles. Extracellular vesicles (EVs) from beneficial gut microbes are emerging as potential postbiotics. Serotonin plays a crucial role in intestinal homeostasis, and its dysregulation is associated with IBD severity. Our study investigated the impact of EVs from the probiotic Nissle 1917 (EcN) and commensal E. coli on intestinal serotonin metabolism under inflammatory conditions using an IL-1β-induced inflammation model in Caco-2 cells. We found strain-specific effects. Specifically, EcN EVs reduced free serotonin levels by upregulating SERT expression through the downregulation of miR-24, miR-200a, TLR4, and NOD1. Additionally, EcN EVs mitigated IL-1β-induced changes in tight junction proteins and oxidative stress markers. These findings underscore the potential of postbiotic interventions as a therapeutic approach for IBD and related pathologies, with EcN EVs exhibiting promise in modulating serotonin metabolism and preserving intestinal barrier integrity. This study is the first to demonstrate the regulation of miR-24 and miR-200a by probiotic-derived EVs.

Oral probiotics microgel plus Galunisertib reduced TGF-β blockade resistance and enhanced anti-tumor immune responses in colorectal cancer

Transforming growth factor β (TGF-β), a versatile immunosuppressive cytokine, has gained increasing attention as a potential target for cancer immunotherapy. However, current strategies are constrained by tumor heterogeneity and drug resistance. Therapeutic probiotics, such as Escherichia coli Nissle1917 (EcN), not only regulate the gut microbiota to increase beneficial bacteria with anti-tumor effects, but also modulate immune factors within the body, thereby enhancing immunity. In this study, we developed an oral microgel delivery system of EcN@(CS-SA)2 by electrostatic interaction between chitosan (CS) and sodium alginate (SA), aiming to enhance its bioavailability in the gastrointestinal tract (GIT). Notably, EcN@(CS-SA)2 microgel showed a synergistic enhancement of the anti-tumor efficacy of Galunisertib (Gal, a TGF-β inhibitor) by inducing apoptosis and immunogenic cell death (ICD) in tumor cells, as well as promoting increased infiltration of CD8+ T cells into the tumor microenvironment (TME).

Probiotic Escherichia coli Nissle 1917 alleviates the neurotoxicity caused by acrylamide in zebrafish.

Neurotoxicity is caused by damage to the brain tissue by neurotoxic agents present in the environment and artificial substances produced by human beings. Acrylamide (ACR) is one such chemical substance that causes neurotoxicity, affecting the brain cells. This neurotoxicity causes damage to the sensory and metabolic functions. The current research investigates the favourable effect of probiotic EcN (Escherichia coli Nissle 1917) on ACR-induced neurotoxicity in zebrafish. The protective role of EcN against ACR induced toxicity was assessed based on behaviour, biochemical, and gene expression analysis. Initially, the colonisation period of EcN in the zebrafish gut was determined and EcN was given orally to the zebrafish only once prior to the ACR treatment. Very interestingly, this dosage was able to ameliorate the adverse effects of ACR significantly in the brain cells. Quantification of oxidative stress and neuronal cell death clearly vindicate the efficiency of probiotic EcN in reversing the damages caused by ACR. EcN is being explored largely in recent days for its therapeutic applications. This study strongly supports the view that EcN can be developed as a supplement to the patients diagnosed with neuronal cell toxicity.

Reduction of Fecal Calprotectin Levels Induced by a Short Course of Escherichia Coli Nissle is Associated with a Lower Likelihood of Disease Flares in Patients with Ulcerative Colitis in Clinical Remission.

Fecal calprotectin (FC) is a biomarker of gut inflammation, and Escherichia coli Nissle 1917 (EcN) is a probiotic strain able to reduce gut inflammation and maintain disease remission in patients with inflammatory bowel disease (IBD). The aim is to assess the effects of EcN administration in patients with IBD in clinical remission and altered FC values. We prospectively included 82 patients with ulcerative colitis (UC) (n=49) and Crohn's disease (CD) (n=33) in clinical remission and with FC values above 250 mcg/g (T0) who were treated with EcN alone for 2 months. FC values were assessed at the end of EcN treatment (T1) and clinical disease activity at 3 months (T2). At T1 median FC values were significantly lower compared to T0 both in patients with CD (312 mcg/g vs 626 mcg/g, p<0.0001) and UC (100 mcg/g vs 584 mcg/g; p<0.0001). Patients with UC who experienced disease relapse at T2 had lesser reduction in median FC values at T1 (-229 mcg/g, vs -397 mcg/g, p=0.049), while in patients with CD we observed no statistically significant difference (-358 mcg/g, vs -427; p=0.568). In patients with UC, a reduction of at least 532 mcg/g in FC had an accuracy of 69.7% and a positive predictive value of 65.7% in predicting maintenance of remission. A short course of EcN was associated with a reduction of FC values in patients with IBD in clinical remission and baseline altered FC values, and in patients with UC this decrease was associated with maintenance of clinical remission.

Redesign of an Escherichia coli Nissle treatment for phenylketonuria using insulated genomic landing pads and genetic circuits to reduce burden.

To build therapeutic strains, Escherichia coli Nissle (EcN) have been engineered to express antibiotics, toxin-degrading enzymes, immunoregulators, and anti-cancer chemotherapies. For efficacy, the recombinant genes need to be highly expressed, but this imposes a burden on the cell, and plasmids are difficult to maintain in the body. To address these problems, we have developed landing pads in the EcN genome and genetic circuits to control therapeutic gene expression. These tools were applied to EcN SYNB1618, undergoing clinical trials as a phenylketonuria treatment. The pathway for converting phenylalanine to trans-cinnamic acid was moved to a landing pad under the control of a circuit that keeps the pathway off during storage. The resulting strain (EcN SYN8784) achieved higher activity than EcN SYNB1618, reaching levels near when the pathway is carried on a plasmid. This work demonstrates a simple system for engineering EcN that aids quantitative strain design for therapeutics.

Integrated Profiling of Gram-Positive and Gram-Negative Probiotic Genomes, Proteomes and Metabolomes Revealed Small Molecules with Differential Growth Inhibition of Antimicrobial-Resistant Pathogens

Probiotics produce small molecules that may serve as alternatives to conventional antibiotics by suppressing growth of antimicrobial resistant (AMR) pathogens. The objective of this study was to identify and examine antimicrobials produced and secreted by probiotics using ‘omics’ profiling with computer-based metabolic flux analyses. The cell-free supernatant of Gram-positive Lacticaseibacillus rhamnosus GG (LGG) and Gram-negative Escherichia coli Nissle (ECN) probiotics inhibited growth of AMR Salmonella Typhimurium, Escherichia coli, and Klebsiella oxytoca ranging between 28.85 − 41.20% (LGG) and 11.48 − 29.45% (ECN). A dose dependent analysis of probiotic supernatants showed LGG was 6.27% to 20.55% more effective at reducing AMR pathogen growth when compared to ECN. Principal component analysis showed clear separation of ECN and LGG cell free supernatant metabolomes. Among 667 metabolites in the supernatant, 304 were differentially abundant between LGG and ECN probiotics. Proteomics identified 87 proteins, whereby 67 (ECN) and 14 (LGG) showed differential expression as enzymes related to carbohydrate and energy metabolic pathways. The whole genomes and metabolomes were next used for in-silico metabolic network analysis. The model predicted the production of 166 metabolites by LGG and ECN probiotics across amino acid, carbohydrate/energy, and nucleotide metabolism with antimicrobial functions. The predictive accuracy of the metabolic flux analysis highlights the novel utility for profiling probiotic supplements as dietary-based antimicrobial alternatives in the control of AMR pathogen growth.

Escherichia coli Nissle 1917 Enhances Efficacy of Oral Attenuated Human Rotavirus Vaccine in a Gnotobiotic Piglet Model.

Human rotavirus (HRV) infection is a major cause of viral gastroenteritis in young children worldwide. Current oral vaccines perform poorly in developing countries where efficacious vaccines are needed the most. Therefore, an alternative affordable strategy to enhance efficacy of the current RV vaccines is necessary. This study evaluated the effects of colonization of neonatal gnotobiotic (Gn) pigs with Escherichia coli Nissle (EcN) 1917 and Lacticaseibacillus rhamnosus GG (LGG) probiotics on immunogenicity and protective efficacy of oral attenuated (Att) HRV vaccine. EcN-colonized pigs had reduced virulent HRV (VirHRV) shedding and decreased diarrhea severity compared with the LGG-colonized group. They also had enhanced HRV-specific IgA antibody titers in serum and antibody secreting cell numbers in tissues pre/post VirHRV challenge, HRV-specific IgA antibody titers in intestinal contents, and B-cell subpopulations in tissues post VirHRV challenge. EcN colonization also enhanced T-cell immune response, promoted dendritic cells and NK cell function, reduced production of proinflammatory cytokines/Toll like receptor (TLR), and increased production of immunoregulatory cytokines/TLR expression in various tissues pre/post VirHRV challenge. Thus, EcN probiotic adjuvant with AttHRV vaccine enhances the immunogenicity and protective efficacy of AttHRV to a greater extent than LGG and it can be used as a safe and economical oral vaccine adjuvant.

Native and Engineered Probiotics: Promising Agents against Related Systemic and Intestinal Diseases.

Intestinal homeostasis is a dynamic balance involving the interaction between the host intestinal mucosa, immune barrier, intestinal microecology, nutrients, and metabolites. Once homeostasis is out of balance, it will increase the risk of intestinal diseases and is also closely associated with some systemic diseases. Probiotics (Escherichia coli Nissle 1917, Akkermansia muciniphila, Clostridium butyricum, lactic acid bacteria and Bifidobacterium spp.), maintaining the gut homeostasis through direct interaction with the intestine, can also exist as a specific agent to prevent, alleviate, or cure intestinal-related diseases. With genetic engineering technology advancing, probiotics can also show targeted therapeutic properties. The aims of this review are to summarize the roles of potential native and engineered probiotics in oncology, inflammatory bowel disease, and obesity, discussing the therapeutic applications of these probiotics.

Oral nanozyme-engineered probiotics for the treatment of ulcerative colitis.

Probiotic-based therapy for ulcerative colitis (UC) is a novel and promising approach that has gained much popularity in recent years. However, probiotics may be easily captured and destroyed by the harsh in vivo environment, which limits their application prospects to a large extent. This work introduces a versatile facile approach for decorating individual probiotics with nanozyme coatings, named Pt-Lipid@EcN. A bimolecular lipid coating is deposited on the surface of probiotics used in the oral treatment of UC using simple self-assembly with a liposome under cytocompatible conditions, and it acts as armor to effectively protect the probiotics from strong digestive acids and enzymes. The obtained results indicated that the liposome-coated Escherichia coli Nissle (EcN) 1917 could significantly improve the colonization rate of the microorganisms in the intestinal tract. We also explored the specific mechanism of Pt-Lipid@EcN to improve the behavior of murine UC models, including reduction of inflammatory effects and histological injury, and regulation of epithelial barrier homeostasis in the intestine. The nanozyme-shielded probiotic exhibited enhanced anti-inflammatory ability in vivo, introducing novel strategies for the application of nanozyme biomedicine in the treatment of colonic inflammatory diseases.

Elafin-expressing probiotic Escherichia coli Nissle 1917 protects against experimental colitis

Objective: To construct the gene modified probiotic Escherichia coli nissle1917 (EcN) which can express human Elafin protein and to explore its protective effect on the acute colitis in mice. Methods: The recombinant plasmid with human Elafin gene was constructed and then transferred to EcN. Western blot results confirmed that the engineered probiotic expressed Elafin successfully in vitro. C57/BL6J mouse was used in this study and were randomly divided into 4 groups according to different treatment: PBS gavage (PBS group); DSS administrated (DSS group); DSS administrated with wild-type EcN (EcN-WT) gavage (EcN-WT group); DSS administrated with EcN-Elafin gavage (EcN-Elafin group). Body weight and disease activity index (DAI) were measured every day. The length of mice colons in each group were measured after euthanasia. The degree of inflammation of intestinal mucosa in each group was measured through histopathological scoring. The proportion of neutrophils and macrophages infiltrated into colon lamina propria was detected by flow cytometry. The protein expression levels of pro-inflammatory cytokines TNF-α, IL-6 and chemokine CXCL-1 in colonic tissue were quantified by enzyme-linked immunosorbent assay. Results: Elafin protein could be detected in the supernatant of EcN-Elafin culture medium and EcN-Elafin homogenates. Compared with DSS group, the weight loss and DAI score of EcN-Elafin group and EcN-WT group were both significantly improved. The colon length of EcN-Elafin group was significantly longer than that of DSS group. The histological score of colitis in EcN-Elafin group was significantly lower than that in DSS group (5.3±2.3 vs 9.3±1.4, P<0.05). In EcN-Elafin group, the proportion of neutrophils[(8.65±1.49)% vs (17.60±2.16)%, P<0.01]and macrophages[(3.79±0.26)% vs (5.73±0.45)%, P<0.01]infiltrated into the colon lamina propria was significantly decreased compared with DSS group. The protein expression levels of TNF-α, IL-6 and CXCL-1 in EcN-Elafin group and EcN-WT group were significantly lower than those in DSS group. Conclusion: Elafin-expressing EcN can protect against DSS-induced acute colitis in mice and may have provided an effective and cost-efficient method for the treatment of IBD.

Improvement of a synthetic live bacterial therapeutic for phenylketonuria with biosensor-enabled enzyme engineering

In phenylketonuria (PKU) patients, a genetic defect in the enzyme phenylalanine hydroxylase (PAH) leads to elevated systemic phenylalanine (Phe), which can result in severe neurological impairment. As a treatment for PKU, Escherichia coli Nissle (EcN) strain SYNB1618 was developed under Synlogic’s Synthetic Biotic™ platform to degrade Phe from within the gastrointestinal (GI) tract. This clinical-stage engineered strain expresses the Phe-metabolizing enzyme phenylalanine ammonia lyase (PAL), catalyzing the deamination of Phe to the non-toxic product trans-cinnamate (TCA). In the present work, we generate a more potent EcN-based PKU strain through optimization of whole cell PAL activity, using biosensor-based high-throughput screening of mutant PAL libraries. A lead enzyme candidate from this screen is used in the construction of SYNB1934, a chromosomally integrated strain containing the additional Phe-metabolizing and biosafety features found in SYNB1618. Head-to-head, SYNB1934 demonstrates an approximate two-fold increase in in vivo PAL activity compared to SYNB1618.

Escherichiacoli Nissle 1917 as a Novel Microrobot for Tumor-Targeted Imaging and Therapy.

Highly efficient drug delivery systems with excellent tumor selectivity and minimal toxicity to normal tissues remain challenging for tumor treatment. Although great effort has been made to prolong the blood circulation and improve the delivery efficiency to tumor sites, nanomedicines are rarely approved for clinical application. Bacteria have the inherent properties of homing to solid tumors, presenting themselves as promising drug delivery systems. Escherichia coli Nissle 1917 (EcN) is a commonly used probiotic in clinical practice. Its facultative anaerobic property drives it to selectively colonize in the hypoxic area of the tumor for survival and reproduction. EcN can be engineered as a bacteria-based microrobot for molecular imaging, drug delivery, and gene delivery. This review summarizes the progress in EcN-mediated tumor imaging and therapy and discusses the prospects and challenges for its clinical application. EcN provides a new idea as a delivery vehicle and will be a powerful weapon against cancer.

Probiotic Escherichia coli Nissle inhibits IL-6 and MAPK-mediated cardiac hypertrophy during STZ-induced diabetes in rats.

Escherichia coli Nissle (EcN), a probiotic bacterium protects against several disorders. Multiple reports have studied the pathways involved in cardiac hypertrophy. However, the effects of probiotic EcN against diabetes-induced cardiac hypertrophy remain to be understood. We administered five weeks old Wistar male (271±19.4 g body weight) streptozotocin-induced diabetic rats with 109 cfu of EcN via oral gavage every day for 24 days followed by subjecting the rats to echocardiography to analyse the cardiac parameters. Overexpressed interleukin (IL)-6 induced the MEK5/ERK5, JAK2/STAT3, and MAPK signalling cascades in streptozotocin-induced diabetic rats. Further, the upregulation of calcineurin, NFATc3, and p-GATA4 led to the elevation of hypertrophy markers, such as atrial and B-type natriuretic peptides. In contrast, diabetic rats supplemented with probiotic EcN exhibited significant downregulated IL-6. Moreover, the MEK5/ERK5 and JAK2/STAT3 cascades involved during eccentric hypertrophy and MAPK signalling, including phosphorylated MEK, ERK, JNK, and p-38, were significantly attenuated in diabetic rats after supplementation of EcN. Western blotting and immunofluorescence revealed the significant downregulation of NFATc3 and downstream mediators, thereby resulting in the impairment of cardiac hypertrophy. Taken together, the findings demonstrate that supplementing probiotic EcN has the potential to show cardioprotective effects by inhibiting diabetes-induced cardiomyopathies.

Prevention of recurrence of enteric peritonitis in peritoneal dialysis with Escherichia coli Nissle 1917: A case-series study.

Peritonitis is still a major cause of drop-out in peritoneal dialysis (PD) and is often the consequence of the migration of bacteria across the intestinal wall, configuring an enteric peritonitis (EP). EP is usually caused by commensals of the gastrointestinal (GI) tract, it relapses commonly and may result in catheter removal. Currently, no specific therapeutic measures are available to effectively prevent recurrence of EP, thus we reported our clinical experience with use of probiotics Escherichia coli Nissle (EcN). This is a case-series study performed in PD patients affected by recurrent peritonitis due to GI commensals. In these patients, we added prophylactic treatment with EcN 100 mg twice a day (in addition to 10 days monthly of 200 mg rifaximin) to the standard management of peritonitis. We enrolled 14 PD patients (mean age: 53.1 ± 11.9 years; 67% males; dialysis vintage: 7.5 (3.1-27.7) months; 64% automated PD). Causative organisms were Escherichia coli (N=5), Klebsiella pneumoniae (N=3), Enterococcus faecalis (N=2), Enterobacter cloacae (N=2), Aeromonas caviae (N=1), Streptococcus gallolyticus (N=1). No exit-site infection was associated with peritonitis. Patients were successfully treated with intra-peritoneal antibiotics adjusted to culture results and antibiotic sensitivities for 14-21 days. During the subsequent 18 months of follow-up, no recurrence of EP was registered. No adverse effect was reported. In PD patients, the use of EcN is associated with no recurrence of EP. Further studies or clinical trials are needed to confirm our results.

Escherichia coli Nissle 1917 administered as a dextranomar microsphere biofilm enhances immune responses against human rotavirus in a neonatal malnourished pig model colonized with human infant fecal microbiota

Human rotavirus (HRV) is a leading cause of diarrhea in children. It causes significant morbidity and mortality, especially in low- and middle-income countries (LMICs), where HRV vaccine efficacy is low. The probiotic Escherichia coli Nissle (EcN) 1917 has been widely used in the treatment of enteric diseases in humans. However, repeated doses of EcN are required to achieve maximum beneficial effects. Administration of EcN on a microsphere biofilm could increase probiotic stability and persistence, thus maximizing health benefits without repeated administrations. Our aim was to investigate immune enhancement by the probiotic EcN adhered to a dextranomar microsphere biofilm (EcN biofilm) in a neonatal, malnourished piglet model transplanted with human infant fecal microbiota (HIFM) and infected with rotavirus. To create malnourishment, pigs were fed a reduced amount of bovine milk. Decreased HRV fecal shedding and protection from diarrhea were evident in the EcN biofilm treated piglets compared with EcN suspension and control groups. Moreover, EcN biofilm treatment enhanced natural killer cell activity in blood mononuclear cells (MNCs). Increased frequencies of activated plasmacytoid dendritic cells (pDC) in systemic and intestinal tissues and activated conventional dendritic cells (cDC) in blood and duodenum were also observed in EcN biofilm as compared with EcN suspension treated pigs. Furthermore, EcN biofilm treated pigs had increased frequencies of systemic activated and resting/memory antibody forming B cells and IgA+ B cells in the systemic tissues. Similarly, the mean numbers of systemic and intestinal HRV-specific IgA antibody secreting cells (ASCs), as well as HRV-specific IgA antibody titers in serum and small intestinal contents, were increased in the EcN biofilm treated group. In summary EcN biofilm enhanced innate and B cell immune responses after HRV infection and ameliorated diarrhea following HRV challenge in a malnourished, HIFM pig model.

Probiotic Escherichia coli Nissle 1917-derived outer membrane vesicles enhance immunomodulation and antimicrobial activity in RAW264.7 macrophages

BackgroundProbiotic Escherichia coli Nissle 1917 (EcN) has been widely studied for the treatment of intestinal inflammatory diseases and infectious diarrhea, but the mechanisms by which they communicate with the host are not well-known. Outer membrane vesicles (OMVs) are produced by Gram-negative bacteria and deliver microbial molecules to distant target cells in the host, which play a very important role in mediating bacteria-host communication. Here, we aimed to investigate whether EcN-derived OMVs (EcN_OMVs) could mediate immune regulation in macrophages.ResultsIn this study, after the characterization of EcN_OMVs using electron microscopy, nanoparticle tracking and proteomic analyses, we demonstrated by confocal fluorescence microscopy that EcN_OMVs could be internalized by RAW 264.7 macrophages. Stimulation with EcN_OMVs at appropriate concentrations promoted proliferation, immune-related enzymatic activities and phagocytic functions of RAW264.7 cells. Moreover, EcN_OMVs induced more anti-inflammatory responses (IL-10) than pro-inflammatory responses (IL-6 and TNF-α) in vitro, and also modulated the production of Th1-polarizing cytokine (IL-12) and Th2-polarizing cytokine (IL-4). Treatments with EcN_OMVs effectively improved the antibacterial activity of RAW 264.7 macrophages.ConclusionsThese findings indicated that EcN_OMVs could modulate the functions of the host immune cells, which will enrich the existing body of knowledge of EVs as an important mechanism for the communication of probiotics with their hosts.