Recombinant Lactobacillus plantarum induces immune responses to cancer testis antigen NY-ESO-1 and maturation of dendritic cells

L. plantarum and L. lactis as a promising agent in treatment of inflammatory bowel disease and colorectal cancer

It has been understood for nearly a century that patients with intestinal inflammatory disease (IBD) have a higher risk of developing colorectal cancer (CRC). Recently, two species of lactic acid bacteria, Lactobacillus plantarum and Lactococcus lactis, have been investigated as therapeutic agents for IBD. These bacteria have been shown to survive gastric transit, to adhere and colonize in the intestinal tract of humans and modulate the intestinal microbiota and immune response. L. plantarum and L. lactis might be used as multifunctional drugs for the treatment of IBD and the prevention or treatment of CRC. This article summarizes current knowledge of L. plantarum and L. lactis as therapeutic and preventative agents for IBD and CRC, respectively.

The Oral Delivery System of Modified GLP-1 by Probiotics for T2DM

The glucagon-like peptide-1 (GLP-1) is a peptide with incretin activity and plays an important role in glycemic control as well as the improvement of insulin resistance in type 2 diabetes mellitus (T2DM). However, the short half-life of the native GLP-1 in circulation poses difficulties for clinical practice. To improve the proteolytic stability and delivery properties of GLP-1, a protease-resistant modified GLP-1 (mGLP-1) was constructed with added arginine to ensure the structural integrity of the released mGLP-1 in vivo. The model probiotic Lactobacillus plantarum WCFS1 was chosen as the oral delivery vehicle with controllable endogenous genetic tools driven for mGLP-1 secretory constitutive expression. The feasibility of our design was explored in db/db mice which showed an improvement in diabetic symptoms related to decreased pancreatic glucagon, elevated pancreatic β-cell proportion, and increased insulin sensitivity. In conclusion, this study provides a novel strategy for the oral delivery of mGLP-1 and further probiotic transformation.

Antitumor effect of invasive Lactobacillus plantarum delivering associated antigen gene sHSP between Trichinella spiralis and Lewis lung cancer cells

Cancer is a frequent disease that seriously harms human health, but there are no ideal therapies for it. Currently, some food-grade microorganisms such as Lactobacillus plantarum have shown better anti-tumor effects. Here, recombinant Lactobacillus plantarum lives vector vaccine NC8-sHSP was generated by using the invasive Lactobacillus plantarum NC8 expressing FnBPA to deliver the associated antigen gene sHSP between trichinella spiralis and Lewis lung cancer cells (LLC) to host cells. NC8-sHSP colonized the mouse intestine to deliver plasmids to intestinal epithelial cells and controlled the growth of LLC by inducing humoral, cellular, and mucosal immunity. The tumor inhibition rates were 62.36% and 68.37% in the prophylactic assay and 40.76% and 44.22% in the treatment assay, respectively. Recombination of Lactobacillus plantarum did not cause significant damage. In conclusion, the recombinant invasive Lactobacillus plantarum constructed in this study has better anti-Lewis lung cancer effects in mice, which will provide new ideas for the application of food-grade microorganisms in anti-tumor and the development of oral tumor vaccines.

Advances of bacteria-based delivery systems for modulating tumor microenvironment

The components and hospitable properties of tumor microenvironment (TME) are associated with tumor progression. Recently, TME modulating vectors and strategies have garnished significant attention in cancer therapy. Although a pilot work has reviewed TME regulation via nanoparticle-based delivery systems, there is no systematical review that summarizes the natural bacteria-based anti-tumor system to modulate TME. In this review, we conclude the strategies of bacterial carriers (including whole bacteria, bacterial skeleton and bacterial components) to regulate TME from the perspective of TME components and hospitable properties, and the clinical trials of bacteria-mediated cancer therapy. Current challenges and future prospects for the design of bacteria-based carriers are also proposed that provide critical insights into this natural delivery system and related translation from the bench to the clinic.

Oral vaccination with invasive Lactobacillus plantarum delivered nucleic acid vaccine co-expressing SS1 and murine interleukin-4 elicits protective immunity against Trichinella spiralis in BALB/c mice

Trichinellosis is a foodborne zoonosis caused by Trichinella spiralis (T. spiralis) that not only causes considerable economic losses for the global pig breeding and food industries, but also seriously threats the health of human. Therefore, it is very necessary to develop an effective vaccine to prevent trichinellosis. In this study, the invasive Lactobacillus plantarum (L. plantarum) expressing fibronectin-binding protein A (FnBPA) was served as a live bacterial vector to deliver DNA to the host to produce a novel oral DNA vaccine. Co-expressing T. spiralis SS1 and murine interleukin-4 (mIL-4) of DNA vaccine were constructed and subsequently delivered to intestinal epithelial cells via invasive L. plantarum. At 10 days after the third immunization, the experimental mice were challenged with 350 T. spiralis infective larvae. The results found that the mice orally vaccinated with invasive L. plantarum harboring pValac-SS1/pSIP409-FnBPA not only stimulated the production of anti-SS1-specific IgG, Th1/Th2 cell cytokines, and secreted(s) IgA but also decreased worm burden and intestinal damage. However, the mice inoculated with invasive L. plantarum co-expressing SS1 and mIL-4 (pValac-SS1-IL-4/pSIP409-FnBPA) induced the highest protective immune response against T. spiralis infection. The DNA vaccine delivered by invasive L. plantarum provides a novel idea for the prevention of T. spiralis infection.

Immunoprotective effects of invasive Lactobacillus plantarum delivered nucleic acid vaccine coexpressing Trichinella spiralis CPF1 and murine interleukin-4

Trichinellosis is a very important food-borne parasitic disease, that seriously endangers animal husbandry and food safety. Therefore, it is necessary to develop a safe and effective vaccine against Trichinella spiralis infection. In this experiment, invasive Lactobacillus plantarum carrying the FnBPA gene served as a live bacterial vector to deliver nucleic acids to the host to produce a novel oral nucleic acid vaccine. Coexpression of the T. spiralis cathepsin F-like protease 1 gene (TsCPF1) and murine IL-4 (mIL-4) by the nucleic acid vaccine was constructed and subsequently delivered to intestinal epithelial cells via invasive L. plantarum. Thirty-seven days after the first immunization, the experimental mice were challenged with 350 T. spiralis infective larvae by oral gavage. The results showed that mice orally immune-stimulated with invasive L. plantarum pValac-TsCPF1/pSIP409-FnBPA not only produce anti-TsCPF1-specific IgG antibodies, sIgA, Th1/Th2 cytokine distinctly increased but also intestinal damage and worm burden relieved compare to non-invasive TsCPF1 group (pValac-TsCPF1/pSIP409). Most notably, experimental mice immunized with invasive L. plantarum coexpressing TsCPF1 and mIL-4 (pValac-TsCPF1-IL-4/pSIP409-FnBPA) exhibited the highest protection efficiency against T. spiralis infection. The above results reveal that invasive L. plantarum-expressing the FnBPA protein improved mucosal and cellular immunity and enhanced resistance to T. spiralis. The nucleic acid vaccine delivered by invasive L. plantarum described in this study offers a novel idea for the prevention of T. spiralis.

Harnessing the potential of Lactobacillus species for therapeutic delivery at the lumenal-mucosal interface

Lactobacillus species have been studied for over 30 years in their role as commensal organisms in the human gut. Recently there has been a surge of interest in their abilities to natively and recombinantly stimulate immune activities, and studies have identified strains and novel molecules that convey particular advantages for applications as both immune adjuvants and immunomodulators. In this review, we discuss the recent advances in Lactobacillus-related activity at the gut/microbiota interface, the efforts to probe the boundaries of the direct and indirect therapeutic potential of these bacteria, and highlight the continued interest in harnessing the native capacity for the production of biogenic compounds shown to influence nervous system activity. Taken together, these aspects underscore Lactobacillus species as versatile therapeutic delivery vehicles capable of effector production at the lumenal-mucosal interface, and further establish a foundation of efficacy upon which future engineered strains can expand.

Dendritic Cells Targeting Lactobacillus plantarum Strain NC8 with a Surface-Displayed Single-Chain Variable Fragment of CD11c Induce an Antigen-Specific Protective Cellular Immune Response

Influenza A virus (H1N1) is an acute, highly contagious respiratory virus. The use of lactic acid bacteria (LAB) to deliver mucosal vaccines against influenza virus infection is a research hot spot. In this study, two recombinant Lactobacillus plantarum strains expressing hemagglutinin (HA) alone or coexpressing aCD11c-HA to target HA protein to dendritic cells (DCs) by fusion to an anti-CD11c single-chain antibody (aCD11c) were constructed. The activation of bone marrow dendritic cells (BMDCs) by recombinant strains and the interaction of activated BMDCs and sorted CD4⁺ or CD8⁺ T cells were evaluated through flow cytometry in vitro, and cellular supernatants were assessed by using an enzyme-linked immunosorbent assay kit. The results demonstrated that, compared to the HA strain, the aCD11c-HA strain significantly increased the activation of BMDCs and increased the production of CD4⁺ gamma interferon-positive (IFN-γ⁺) T cells, CD8⁺ IFN-γ⁺ T cells, and IFN-γ in the cell culture supernatant in vitro Consistent with these results, the aCD11c-HA strain clearly increased the activation and maturation of DCs, the HA-specific responses of CD4⁺ IFN-γ⁺ T cells, CD8⁺ IFN-γ⁺ T cells, and CD8⁺ CD107a⁺ T cells, and the proliferation of T cells in the spleen, finally increasing the levels of specific antibodies and neutralizing antibodies in mice. In addition, the protection of immunized mice was observed after viral infection, as evidenced by improved weight loss, survival, and lung pathology. The adoptive transfer of CD8⁺ T cells from the aCD11c-HA mice to NOD/Lt-SCID mice resulted in a certain level of protection after influenza virus infection, highlighting the efficacy of the aCD11c targeting strategy.

Recombinant invasive Lactobacillus plantarum expressing fibronectin binding protein A induce specific humoral immune response by stimulating differentiation of dendritic cells

Recombinant lactic acid bacteria (LAB), especially Lactococcus lactis, have been genetically engineered to express heterogeneous invasion proteins, such as the fibronectin binding protein A (FnBPA) from Staphylococcus aureus, to increase the invasion ability of the host strains, indicating a promising approach for DNA vaccine delivery. The presence of FnBPA has been also shown to be an adjuvant for co-delivered antigens, however, the underlying mechanisms are still not clear. To explore the above underlying mechanisms, in this study, we constructed a novel Lactobacillus plantarum strain with surface displayed FnBPA, which could significantly improve the adhesion and invasion ratios of L. plantarum strain on a porcine intestinal epithelial cell line (IPEC-J2) about two-fold compared with the empty vector. At the same time, the presence of FnBPA significantly stimulated the differentiation of bone marrow-derived dendritic cells (DCs) and increased the secretion of interleukin (IL)-6 and mRNA level of IL-6 gene, which were proved by flow cytometry, enzyme-linked immunosorbent assay (ELISA) and quantitative reverse transcription PCR (qRT-PCR). With regard to in vivo study, the presence of FnBPA significantly stimulated the differentiation of DCs in the Peyer's patch (PP) and the percentages of IL-4⁺ and IL-17A⁺ T helper (Th) cells of splenocytes in flow cytometry assay. In consistent with these results, the levels of IL-4 and IL-17A in serum as measured via ELISA also increased in mice treated with FnBPA⁺ L. plantarum. Finally, the FnBPA strain increased the production of B220⁺ B cells in mesenteric lymph node (MLN) and PP and the levels of FnBPA-specific IgG and sIgA antibodies, indicating the its possible application in vaccine field. This study demonstrated that the invasive L. plantarum with surface displayed FnBPA could modulate host immune response by stimulating the differentiation of DCs and Th cells which could possibly be responsive for the adjuvant effects of FnBPA.

Chromosomal integration of heterologous oxalate decarboxylase in Lactobacillus plantarum WCFS1 using mobile genetic element Ll.LtrB

Lactobacillus plantarum WCFS1 (L. plantarum WCFS1) is commonly used as a potential cell factory because of its 'generally recognized as safe' status. The plasmid instability and the presence of antibiotic selection marker complicate the application of genetically modified L. plantarum in human clinical trials. In the present study, we aimed to integrate oxalate decarboxylase (oxdC) gene of Bacillus subtilis origin by targeted chromosomal mutation in L. plantarum using mobile genetic element Ll.LtrB as a therapeutic tool against calcium oxalate stone disease. oxdC expression cassette was constructed and integrated into a targeted gene, thymidylate synthase (thyA) in the L. plantarum genome. The dependence on external thymidine for growth and survival was established by live dead population assay and SEM (scanning electron microscopy) analysis. The western blotting assay showed the secretion of 44 kDa OxdC protein in the culture supernatant of L. plantarum ∆thyA:OxdC. The biologically contained recombinant strain significantly reduced the oxalate concentration by 53% and exhibited a loss of viability when introduced to environmental samples. Biologically contained L. plantarum secreting OxdC constructed using group II intron has the ability to degrade oxalate present in the extracellular environment and could be used as a therapeutic tool for the calcium oxalate stone disease.

Development of oral cancer vaccine using recombinant Bifidobacterium displaying Wilms' tumor 1 protein

Several types of vaccine-delivering tumor-associated antigens (TAAs) have been developed in basic and clinical research. Wilms' tumor 1 (WT1), identified as a gene responsible for pediatric renal neoplasm, is one of the most promising TAA for cancer immunotherapy. Peptide and dendritic cell-based WT1 cancer vaccines showed some therapeutic efficacy in clinical and pre-clinical studies but as yet no oral WT1 vaccine can be administrated in a simple and easy way. In the present study, we constructed a novel oral cancer vaccine using a recombinant Bifidobacterium longum displaying WT1 protein. B. longum 420 was orally administered into mice inoculated with WT1-expressing tumor cells for 4 weeks to examine anti-tumor effects. To analyze the WT1-specific cellular immune responses to oral B. longum 420, mice splenocytes were isolated and cytokine production and cytotoxic activities were determined. Oral administrations of B. longum 420 significantly inhibited WT1-expressing tumor growth and prolonged survival in mice. Immunohistochemical study and immunological assays revealed that B. longum 420 substantially induced tumor infiltration of CD4+T and CD8+T cells, systemic WT1-specific cytokine production, and cytotoxic activity mediated by WT1-epitope specific cytotoxic T lymphocytes, with no apparent adverse effects. Our novel oral cancer vaccine safely induced WT1-specific cellular immunity via activation of the gut mucosal immune system and achieved therapeutic efficacy with several practical advantages over existing non-oral vaccines.

Immunogenic Properties of Lactobacillus plantarum Producing Surface-Displayed Mycobacterium tuberculosis Antigens

Tuberculosis (TB) remains among the most deadly diseases in the world. The only available vaccine against tuberculosis is the bacille Calmette-Guérin (BCG) vaccine, which does not ensure full protection in adults. There is a global urgency for the development of an effective vaccine for preventing disease transmission, and it requires novel approaches. We are exploring the use of lactic acid bacteria (LAB) as a vector for antigen delivery to mucosal sites. Here, we demonstrate the successful expression and surface display of a Mycobacterium tuberculosis fusion antigen (comprising Ag85B and ESAT-6, referred to as AgE6) on Lactobacillus plantarum The AgE6 fusion antigen was targeted to the bacterial surface using two different anchors, a lipoprotein anchor directing the protein to the cell membrane and a covalent cell wall anchor. AgE6-producing L. plantarum strains using each of the two anchors induced antigen-specific proliferative responses in lymphocytes purified from TB-positive donors. Similarly, both strains induced immune responses in mice after nasal or oral immunization. The impact of the anchoring strategies was reflected in dissimilarities in the immune responses generated by the two L. plantarum strains in vivo The present study comprises an initial step toward the development of L. plantarum as a vector for M. tuberculosis antigen delivery.

IMPORTANCE

This work presents the development of Lactobacillus plantarum as a candidate mucosal vaccine against tuberculosis. Tuberculosis remains one of the top infectious diseases worldwide, and the only available vaccine, bacille Calmette-Guérin (BCG), fails to protect adults and adolescents. Direct antigen delivery to mucosal sites is a promising strategy in tuberculosis vaccine development, and lactic acid bacteria potentially provide easy, safe, and low-cost delivery vehicles for mucosal immunization. We have engineered L. plantarum strains to produce a Mycobacterium tuberculosis fusion antigen and to anchor this antigen to the bacterial cell wall or to the cell membrane. The recombinant strains elicited proliferative antigen-specific T-cell responses in white blood cells from tuberculosis-positive humans and induced specific immune responses after nasal and oral administrations in mice.

Follistatin-like protein 1 contributes to dendritic cell and T-lymphocyte activation in nasopharyngeal carcinoma patients by altering nuclear factor κb and Jun N-terminal kinase expression

Follistatin‐like protein 1 (FSTL1) is a newly characterized protein that can regulate the immune response in various ways. Dendritic cells (DCs) are central to immune regulation. In this study, we explored the impact of FSTL1 on DC activity in nasopharyngeal carcinoma (NPC) patients. The surface expression of CD40, CD86, and HLA‐DR on DCs was analyzed and showed significantly elevated expression levels, indicating DC maturity. After FSTL1 was added to DCs collected from NPC patients (n = 50), controls (n = 47), and healthy donors (n = 10), interferon γ secretion and T‐cell receptor expression in cytotoxic T lymphocytes were also investigated. In the experimental groups, the expression of the critical immune protein nuclear factor (NF)‐κb was upregulated, whereas Jun N‐terminal kinase (JNK) was downregulated. Our findings demonstrate that FSTL1 plays a critical role in immune regulation, enhancing the antigen presentation ability of DCs by up‐regulating NF‐κb expression and down‐regulating JNK expression.

Display of a β-mannanase and a chitosanase on the cell surface of Lactobacillus plantarum towards the development of whole-cell biocatalysts

BACKGROUND

Lactobacillus plantarum is considered as a potential cell factory because of its GRAS (generally recognized as safe) status and long history of use in food applications. Its possible applications include in situ delivery of proteins to a host, based on its ability to persist at mucosal surfaces of the human intestine, and the production of food-related enzymes. By displaying different enzymes on the surface of L. plantarum cells these could be used as whole-cell biocatalysts for the production of oligosaccharides. In this present study, we aimed to express and display a mannanase and a chitosanase on the cell surface of L. plantarum.

RESULTS

ManB, a mannanase from Bacillus licheniformis DSM13, and CsnA, a chitosanase from Bacillus subtilis ATCC 23857 were fused to different anchoring motifs of L. plantarum for covalent attachment to the cell surface, either via an N-terminal lipoprotein anchor (Lp_1261) or a C-terminal cell wall anchor (Lp_2578), and the resulting fusion proteins were expressed in L. plantarum WCFS1. The localization of the recombinant proteins on the bacterial cell surface was confirmed by flow cytometry and immunofluorescence microscopy. The highest mannanase and chitosanase activities obtained for displaying L. plantarum cells were 890 U and 1360 U g dry cell weight, respectively. In reactions with chitosan and galactomannans, L. plantarum CsnA- and ManB-displaying cells produced chito- and manno-oligosaccharides, respectively, as analyzed by high performance anion exchange chromatography (HPAEC) and mass spectrometry (MS). Surface-displayed ManB is able to break down galactomannan (LBG) into smaller manno-oligosaccharides, which can support growth of L. plantarum.

CONCLUSION

This study shows that mannanolytic and chitinolytic enzymes can be anchored to the cell surface of L. plantarum in active forms. L. plantarum chitosanase- and mannanase-displaying cells should be of interest for the production of potentially 'prebiotic' oligosaccharides. This approach, with the enzyme of interest being displayed on the cell surface of a food-grade organism, may also be applied in production processes relevant for food industry.