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Yiemchavee S, Wong-Arce A, Romero-Maldonado A, Shanmugaraj B, Monsivais-Urenda AE, Phoolcharoen W, Rosales-Mendoza S. Expression and immunogenicity assessment of a plant-made immunogen targeting the cytotoxic T-lymphocyte associated antigen-4: a possible approach for cancer immunotherapy. J Biotechnol 2021; 329:29-37. [PMID: 33485860 DOI: 10.1016/j.jbiotec.2021.01.016] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2020] [Revised: 01/13/2021] [Accepted: 01/14/2021] [Indexed: 01/08/2023]
Abstract
Cancer immunotherapy is a promising intervention to fight against this global health problem. In particular targeting immune checkpoints, such as cytotoxic T-lymphocyte associated antigen-4 (CTLA-4) and programmed-death protein 1 (PD-1), by specific monoclonal antibodies is a current treatment for many malignances. A possible innovation in this field is based on the induction of humoral responses in the host by suppressing the effects of such immune checkpoints and as consequence favoring the activation of cellular immunity against the tumor cells. In this study, chimeric protein comprising the B subunit of Escherichia coli heat-labile enterotoxin as carrier and the extracellular domain of CTLA-4 (LTB-CTLA4) was produced in Nicotiana benthamiana by transient expression. The recombinant protein was accumulated up to 1.29 μg/g of leaves fresh weight on 4 day-post-infiltration. The integrity of the plant-made LTB-CTLA4 antigen was confirmed by western blot analysis and ELISA. Immunogenicity of the plant-made LTB-CTLA4 was assessed in BALB/c mice and the results showed that humoral responses were induced against both the LTB and CTLA-4 moieties. The plant-made LTB-CTLA4 stands as a promising candidate for the design of advanced protection studies against cancer in murine models.
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Affiliation(s)
- Sutita Yiemchavee
- Research unit for Plant-produced Pharmaceuticals, Chulalongkorn University, Bangkok, Thailand; Department of Pharmacognosy and Pharmaceutical Botany, Faculty of Pharmaceutical Sciences, Chulalongkorn University, Bangkok, Thailand
| | - Alejandra Wong-Arce
- Facultad de Ciencias Químicas, Universidad Autónoma de San Luis Potosí, Av.Dr. Manuel Nava 6, San Luis Potosí, 78210, Mexico; Centro de Investigación en Ciencias de la Salud y Biomedicina, Universidad Autónoma de San Luis Potosí, Av. Sierra Leona 550, Lomas 2ª. Sección, San Luis Potosí, 78210, Mexico
| | - Andrea Romero-Maldonado
- Facultad de Ciencias Químicas, Universidad Autónoma de San Luis Potosí, Av.Dr. Manuel Nava 6, San Luis Potosí, 78210, Mexico; Centro de Investigación en Ciencias de la Salud y Biomedicina, Universidad Autónoma de San Luis Potosí, Av. Sierra Leona 550, Lomas 2ª. Sección, San Luis Potosí, 78210, Mexico
| | - Balamurugan Shanmugaraj
- Research unit for Plant-produced Pharmaceuticals, Chulalongkorn University, Bangkok, Thailand; Department of Pharmacognosy and Pharmaceutical Botany, Faculty of Pharmaceutical Sciences, Chulalongkorn University, Bangkok, Thailand
| | - Adriana E Monsivais-Urenda
- Centro de Investigación en Ciencias de la Salud y Biomedicina, Universidad Autónoma de San Luis Potosí, Av. Sierra Leona 550, Lomas 2ª. Sección, San Luis Potosí, 78210, Mexico; Facultad de Medicina, Universidad Autónoma de San Luis Potosí, Mexico
| | - Waranyoo Phoolcharoen
- Research unit for Plant-produced Pharmaceuticals, Chulalongkorn University, Bangkok, Thailand; Department of Pharmacognosy and Pharmaceutical Botany, Faculty of Pharmaceutical Sciences, Chulalongkorn University, Bangkok, Thailand.
| | - Sergio Rosales-Mendoza
- Facultad de Ciencias Químicas, Universidad Autónoma de San Luis Potosí, Av.Dr. Manuel Nava 6, San Luis Potosí, 78210, Mexico; Centro de Investigación en Ciencias de la Salud y Biomedicina, Universidad Autónoma de San Luis Potosí, Av. Sierra Leona 550, Lomas 2ª. Sección, San Luis Potosí, 78210, Mexico.
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2
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Conte FL, Santiago KB, Conti BJ, Cardoso EDO, Oliveira LPG, Feltran GDS, Zambuzzi WF, Golim MDA, Cruz MT, Sforcin JM. Propolis from southeastern Brazil produced by Apis mellifera affects innate immunity by modulating cell marker expression, cytokine production and intracellular pathways in human monocytes. J Pharm Pharmacol 2020; 73:135-144. [PMID: 33793799 DOI: 10.1093/jpp/rgaa023] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2020] [Accepted: 10/15/2020] [Indexed: 12/28/2022]
Abstract
OBJECTIVES Propolis is a bee-made product used for centuries due to its diverse biological properties, including its immunomodulatory action. This work aimed at investigating whether propolis may affect monocyte functions challenged with retinoic acid (RA), B subunit of Escherichia coli heat-labile enterotoxin (EtxB), human melanoma-associated antigen-1 (MAGE-1) and lipopolysaccharide (LPS). METHODS Monocytes from healthy donors were treated with the stimuli separately or in the presence of propolis. Cell viability was evaluated by MTT assay, cell marker expression was assessed by flow cytometry, cytokine production by ELISA, gene expression by RT-qPCR. KEY FINDINGS Propolis alone maintained TLR-2, TLR-4, HLA-DR, CD40 and CD80 expression in the monocytes; however, its combination with either MAGE-1 or LPS decreased CD40 expression triggered by the stimuli. Propolis maintained RA action on cell marker expression. Propolis inhibited TNF-α (with either EtxB or MAGE-1) and IL-6 (with either RA or MAGE-1), and increased IL-10 (with MAGE-1) production. Propolis downmodulated LC3 expression induced by LPS. It also induced a lower NF-kB expression than control cells and its combination with RA induced a higher expression than the stimulus alone. CONCLUSIONS Propolis potentially affected innate immunity by downmodulating the monocytes pro-inflammatory activity.
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Affiliation(s)
- Fernanda Lopes Conte
- Department of Chemical and Biological Sciences, Institute of Biosciences, São Paulo State University (UNESP), Botucatu, São Paulo, Brazil
| | - Karina Basso Santiago
- Department of Chemical and Biological Sciences, Institute of Biosciences, São Paulo State University (UNESP), Botucatu, São Paulo, Brazil
| | - Bruno José Conti
- Department of Chemical and Biological Sciences, Institute of Biosciences, São Paulo State University (UNESP), Botucatu, São Paulo, Brazil
| | - Eliza de Oliveira Cardoso
- Department of Chemical and Biological Sciences, Institute of Biosciences, São Paulo State University (UNESP), Botucatu, São Paulo, Brazil
| | - Lucas Pires Garcia Oliveira
- Department of Chemical and Biological Sciences, Institute of Biosciences, São Paulo State University (UNESP), Botucatu, São Paulo, Brazil
| | - Geórgia da Silva Feltran
- Department of Chemical and Biological Sciences, Institute of Biosciences, São Paulo State University (UNESP), Botucatu, São Paulo, Brazil
| | - Willian Fernando Zambuzzi
- Department of Chemical and Biological Sciences, Institute of Biosciences, São Paulo State University (UNESP), Botucatu, São Paulo, Brazil
| | - Marjorie de Assis Golim
- Botucatu Blood Center, School of Medicine, São Paulo State University (UNESP), São Paulo, Brazil
| | - Maria Teresa Cruz
- Center for Neurosciences and Cellular Biology, Faculty of Pharmacy, University of Coimbra, Coimbra, Portugal
| | - José Maurício Sforcin
- Department of Chemical and Biological Sciences, Institute of Biosciences, São Paulo State University (UNESP), Botucatu, São Paulo, Brazil
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3
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Duan Q, Xia P, Nandre R, Zhang W, Zhu G. Review of Newly Identified Functions Associated With the Heat-Labile Toxin of Enterotoxigenic Escherichia coli. Front Cell Infect Microbiol 2019; 9:292. [PMID: 31456954 PMCID: PMC6700299 DOI: 10.3389/fcimb.2019.00292] [Citation(s) in RCA: 48] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2019] [Accepted: 07/29/2019] [Indexed: 12/11/2022] Open
Abstract
Heat-labile toxin (LT) is a well-characterized powerful enterotoxin produced by enterotoxigenic Escherichia coli (ETEC). This toxin is known to contribute to diarrhea in young children in developing countries, international travelers, as well as many different species of young animals. Interestingly, it has also been revealed that LT is involved in other activities in addition to its role in enterotoxicity. Recent studies have indicated that LT toxin enhances enteric pathogen adherence and subsequent intestinal colonization. LT has also been shown to act as a powerful adjuvant capable of upregulating vaccine antigenicity; it also serves as a protein or antigenic peptide display platform for new vaccine development, and can be used as a naturally derived cell targeting and protein delivery tool. This review summarizes the epidemiology, secretion, delivery, and mechanisms of action of LT, while also highlighting new functions revealed by recent studies.
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Affiliation(s)
- Qiangde Duan
- College of Veterinary Medicine, Institute of Comparative Medicine, Yangzhou University, Yangzhou, China.,Joint International Research Laboratory of Agriculture and Agri-Product Safety of Ministry of Education of China, Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou, China
| | - Pengpeng Xia
- College of Veterinary Medicine, Institute of Comparative Medicine, Yangzhou University, Yangzhou, China.,Joint International Research Laboratory of Agriculture and Agri-Product Safety of Ministry of Education of China, Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou, China
| | - Rahul Nandre
- Department of Microbiology and Immunology, Uniformed Services University, Bethesda, MD, United States
| | - Weiping Zhang
- Department of Pathobiology, University of Illinois at Urbana-Champaign, Urbana, IL, United States
| | - Guoqiang Zhu
- College of Veterinary Medicine, Institute of Comparative Medicine, Yangzhou University, Yangzhou, China.,Joint International Research Laboratory of Agriculture and Agri-Product Safety of Ministry of Education of China, Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou, China
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4
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Samuels S, Alwan Z, Egnin M, Jaynes J, Connell TD, Bernard GC, Nashar T. Novel Therapeutic Approach for Inhibition of HIV-1 Using Cell-Penetrating Peptide and Bacterial Toxins. ACTA ACUST UNITED AC 2017; 8. [PMID: 29226013 PMCID: PMC5719890 DOI: 10.4172/2155-6113.1000737] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Despite advancements in our understanding of HIV-1 pathogenesis, critical virus components for immunity, vaccines trials, and drugs development, challenges remain in the fight against HIV-1. Of great importance is the inhibitory function of microbicidal cell penetrating peptides and bacterial toxins that interfere with production and neutralize infection of HIV-1 particles. We demonstrate that the neutralizing activity of a cationic 18 amino acids peptide, is similar to a broadly neutralizing human antibody, and inhibits production of two HIV-1 strains in human cell lines. Pretreatment of cells with bacterial toxins or toxoids derived from enterotoxigenic E. coli, boost subsequent activity of the peptide against HIV-1, to inhibit simultaneously production and infection. The synthetic peptide crosses the cell membrane into the cytoplasm and nucleus. In vitro analysis of a possible target for this peptide revealed specific binding to recombinant HIV-1 gag p24. This is the first demonstration of a synergy between bacterial toxins and a cell-penetrating peptide against HIV-1.
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Affiliation(s)
- Steven Samuels
- Environment and Nutrition Sciences, Faculty of Agriculture, Tuskegee University, Tuskegee, Alabama, USA.,Department of Life and Earth Sciences, Perimeter College at Georgia State University, 555 North Indian Creek Drive, Clarkston, USA
| | - Zainab Alwan
- Department of Pathobiology, College of Veterinary Medicine, Tuskegee University, Tuskegee, Alabama, USA.,Department of Community Health, Institute of Medical Technology, Middle Technical University Baghdad, Iraq
| | - Marceline Egnin
- Environment and Nutrition Sciences, Faculty of Agriculture, Tuskegee University, Tuskegee, Alabama, USA
| | - Jessie Jaynes
- Environment and Nutrition Sciences, Faculty of Agriculture, Tuskegee University, Tuskegee, Alabama, USA
| | - Terry D Connell
- Department of Microbiology and Immunology, The Witebsky Center for Microbial Pathogenesis and Immunology, Buffalo, New York, USA
| | - Gregory C Bernard
- Environment and Nutrition Sciences, Faculty of Agriculture, Tuskegee University, Tuskegee, Alabama, USA
| | - Toufic Nashar
- Department of Pathobiology, College of Veterinary Medicine, Tuskegee University, Tuskegee, Alabama, USA
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5
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Bignon A, Watt AP, Linterman MA. Escherichia coli Heat-Labile Enterotoxin B Limits T Cells Activation by Promoting Immature Dendritic Cells and Enhancing Regulatory T Cell Function. Front Immunol 2017; 8:560. [PMID: 28555139 PMCID: PMC5430108 DOI: 10.3389/fimmu.2017.00560] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2017] [Accepted: 04/26/2017] [Indexed: 01/24/2023] Open
Abstract
Treatments to limit T cell activation are essential for managing autoimmune and inflammatory disorders. The B subunit of Escherichia coli heat-labile enterotoxin (EtxB) is known to ameliorate inflammatory disease in vivo but the mechanism by which this is mediated is not well understood. Here, we show that following intranasal administration, EtxB acts on two key cellular regulators of T cell activation: regulatory T cells and dendritic cells (DCs). EtxB enhances the proliferation of lung regulatory T cells and doubles their suppressive function, likely through an increase in expression of the Treg effector molecule CTLA-4. EtxB supports the generation of interleukin-10-producing DCs that are unable to activate T cells. These data show, for the first time, that mucosal EtxB treatment limits T cells activation by acting jointly on two distinct types of immune cells.
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Affiliation(s)
- Alexandre Bignon
- Lymphocyte Signalling and Development, Babraham Institute, Babraham Research Campus, Cambridge, UK
| | - Alan P Watt
- Xenovium Limited, Chesterford Research Park, Little Chesterford, UK
| | - Michelle A Linterman
- Lymphocyte Signalling and Development, Babraham Institute, Babraham Research Campus, Cambridge, UK
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6
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El-Kassas S, Faraj R, Martin K, Hajishengallis G, Connell TD, Nashar T. Cell clustering and delay/arrest in T-cell division implicate a novel mechanism of immune modulation by E. coli heat-labile enterotoxin B-subunits. Cell Immunol 2015; 295:150-62. [PMID: 25880107 DOI: 10.1016/j.cellimm.2015.02.014] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2014] [Revised: 02/17/2015] [Accepted: 02/26/2015] [Indexed: 10/23/2022]
Abstract
The B-subunits of heat-labile enterotoxins LT-I (LT-IB) and LT-IIa (LT-IIaB) are strong adjuvants that bind to cell-surface receptors, including gangliosides G(M1) and GD1b, respectively. LT-IIaB also binds TLR-2. We demonstrate for the first time that co-incubation with the B-subunits induces significant clustering of B cells after only 4h, and B and T cells in 24h. Clustering was dependent on intact B-subunits, but not on the TLR-2 binding activity of LT-IIaB, indicating it was ganglioside-mediated. Treatment of B cells with LT-IB, a mixture of LT-IB+LT-IIaB, but not LT-IIaB alone, caused a delay in T cell division following ovalbumin endocytosis. B cell receptor-mediated uptake in presence of each treatment caused an arrest, but with increased production of IL-2. Further, treatments differentially increased the proportion of macrophages expressing MHC class-II. These results highlight the outcomes of interplay between signals involving different receptors and implicate a novel mechanism of adjuvanticity.
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Affiliation(s)
- Seham El-Kassas
- College of Veterinary Medicine, Nursing & Allied Health, Department of Pathobiology, Tuskegee University, 1200 Montgomery Road, Tuskegee, AL 36088, USA; Kafrelshikh University, College of Veterinary Medicine, Kafrelsheikh, Egypt
| | - Rawah Faraj
- College of Veterinary Medicine, Nursing & Allied Health, Department of Pathobiology, Tuskegee University, 1200 Montgomery Road, Tuskegee, AL 36088, USA; Middle Technical University, Institute of Medical Technology, Department of Community Health, Baghdad, Iraq
| | - Karmarcha Martin
- College of Veterinary Medicine, Nursing & Allied Health, Department of Pathobiology, Tuskegee University, 1200 Montgomery Road, Tuskegee, AL 36088, USA
| | - George Hajishengallis
- Pennsylvania School of Dental Medicine, Department of Microbiology, Philadelphia, PA 19104, USA
| | - Terry D Connell
- The Department of Microbiology & Immunology and The Witebsky Center for Microbial Pathogenesis and Immunology, School of Medicine and Biomedical Sciences, 138 Farber Hall, 3435 Main St., University at Buffalo, NY 14214, USA
| | - Toufic Nashar
- College of Veterinary Medicine, Nursing & Allied Health, Department of Pathobiology, Tuskegee University, 1200 Montgomery Road, Tuskegee, AL 36088, USA.
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8
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Nashar TO. The Quest for an HIV-1 Vaccine Adjuvant: Bacterial Toxins as New Potential Platforms. JOURNAL OF CLINICAL & CELLULAR IMMUNOLOGY 2014; 5. [PMID: 27375924 PMCID: PMC4929853 DOI: 10.4172/2155-9899.1000225] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
While tremendous efforts are undergoing towards finding an effective HIV-1 vaccine, the search for an HIV-1 vaccine adjuvant lags behind and is understudied. More recently, however, efforts have focused on testing adjuvant formulations that can boost the immune response and generate broadly neutralizing antibodies to HIV-1 ENV (gp160). Despite this, there remain a number of challenges towards achieving this goal. These include safety of adjuvant formulations; stability of the incorporated antigens; maintenance of ENV immunogenicity; optimal inoculation sites; the effective combination of adjuvants; stability of ENV neutralizing epitopes in some adjuvant formulations; mucosal immunity; and long-term maintenance of the immune response. A new class of adjuvants for HIV-1 proteins is suggested to overcome many of the limitations of some other adjuvants. Type 1 (LT-I) and type 2 (LT-II) human E. coli enterotoxins (HLTs) and their non-toxic B-subunits derivatives are strong systemic and mucosal adjuvants and effective carriers for other proteins and epitopes. Their stable molecular structure in the presence of fused proteins and epitopes, and their ability to target surface receptors on antigen presenting cells make them ideal for the delivery of HIV-1 ENV or HIV other proteins. Importantly, unlike some other adjuvants, HLTs and derivatives have well-defined modes of immune system activation. The challenges in finding optimal HIV-1 vaccine adjuvant formulation and the important properties of HLTs are discussed.
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Affiliation(s)
- Toufic O Nashar
- College of Veterinary Medicine, Nursing & Allied Health, Department of Pathobiology, Tuskegee University, Tuskegee, AL 36088, USA
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9
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Jeon BW, Jawale CV, Kim SH, Lee JH. Attenuated Salmonella Gallinarum secreting an Escherichia coli heat-labile enterotoxin B subunit protein as an adjuvant for oral vaccination against fowl typhoid. Vet Immunol Immunopathol 2012; 150:149-60. [PMID: 23083937 DOI: 10.1016/j.vetimm.2012.09.006] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2012] [Revised: 09/07/2012] [Accepted: 09/08/2012] [Indexed: 12/29/2022]
Abstract
In our previous study, we constructed a vaccine candidate (JOL916) for fowl typhoid (FT). A live adjuvant Salmonella Gallinarum (SG) strain was generated in the present study to facilitate efficacious oral vaccination with this vaccine. The Escherichia coli eltB gene secreting heat-labile enterotoxin B subunit (LTB) was cloned into an Asd(+) plasmid pJHL65. This was transformed into a Δlon ΔcpxR Δasd SG strain and the resulting strain was designated JOL1229. Secretion of LTB from JOL1229 was confirmed with an immunoblot assay. To determine the optimal dose of the strain, 50 six-week-old female chickens were divided into five groups (Groups A-E, n=10 per group) and orally inoculated with various doses of JOL1229 and JOL916. In Group B (consisting of four parts JOL916 and one part JOL1229), significant cell-mediated immune responses, plasma IgG levels and intestinal secretary IgA levels were induced after inoculation with both strains. On challenge with the wild-type strain, significant reductions in mortality were observed in the group. In addition, after inoculation the LTB strain was not recovered in feces samples, and resulted in no, or very mild, gross lesions in the liver and spleen. Both CD4(+) and CD8(+) T-cells were significantly increased in peripheral blood samples from the chickens immunized with the LTB strain. Expression of the interleukin-6 (IL-6) gene in splenocytes was induced in the chickens immunized with the LTB strain. These results suggest that oral immunization with the LTB-adjuvant strain, in particular with the four parts JOL916 and one part JOL1229 mixture, increased the immune response and provided efficient protection against FT in chickens.
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Affiliation(s)
- Byung Woo Jeon
- College of Veterinary Medicine, Chonbuk National University, Jeonju 561-756, Republic of Korea
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10
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da Hora VP, Conceição FR, Dellagostin OA, Doolan DL. Non-toxic derivatives of LT as potent adjuvants. Vaccine 2011; 29:1538-44. [DOI: 10.1016/j.vaccine.2010.11.091] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2010] [Revised: 11/10/2010] [Accepted: 11/30/2010] [Indexed: 12/21/2022]
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11
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Effective CD8+ T cell priming and tumor protection by enterotoxin B subunit-conjugated peptides targeted to dendritic cells. Vaccine 2009; 27:5252-8. [DOI: 10.1016/j.vaccine.2009.06.053] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2009] [Revised: 06/08/2009] [Accepted: 06/14/2009] [Indexed: 11/21/2022]
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12
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De Haan L, Hirst TR. Cholera toxin: A paradigm for multi-functional engagement of cellular mechanisms (Review). Mol Membr Biol 2009; 21:77-92. [PMID: 15204437 DOI: 10.1080/09687680410001663267] [Citation(s) in RCA: 123] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Cholera toxin (Ctx) from Vibrio cholerae and its closely related homologue, heat-labile enterotoxin (Etx) from Escherichia coli have become superb tools for illuminating pathways of cellular trafficking and immune cell function. These bacterial protein toxins should be viewed as conglomerates of highly evolved, multi-functional elements equipped to engage the trafficking and signalling machineries of cells. Ctx and Etx are members of a larger family of A-B toxins of bacterial (and plant) origin that are comprised of structurally and functionally distinct enzymatically active A and receptor-binding B sub-units or domains. Intoxication of mammalian cells by Ctx and Etx involves B pentamer-mediated receptor binding and entry into a vesicular pathway, followed by translocation of the enzymatic A1 domain of the A sub-unit into the target cell cytosol, where covalent modification of intracellular targets leads to activation of adenylate cyclase and a sequence of events culminating in life-threatening diarrhoeal disease. Importantly, Ctx and Etx also have the capacity to induce a wide spectrum of remarkable immunological processes. With respect to the latter, it has been found that these toxins activate signalling pathways that modulate the immune system. This review explores the complexities of the cellular interactions that are engaged by these bacterial protein toxins, and highlights some of the new insights to have recently emerged.
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Affiliation(s)
- Lolke De Haan
- Department of Pathology and Microbiology, School of Medical Sciences, University of Bristol, United Kingdom
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13
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Donaldson DS, Williams NA. Bacterial toxins as immunomodulators. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2009; 666:1-18. [PMID: 20054971 DOI: 10.1007/978-1-4419-1601-3_1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Bacterial toxins are the causative agent at pathology in a variety of diseases. Although not always the primary target of these toxins, many have been shown to have potent immunomodulatory effects, for example, inducing immune responses to co-administered antigens and suppressing activation of immune cells. These abilities of bacterial toxins can be harnessed and used in a therapeutic manner, such as in vaccination or the treatment of autoimmune diseases. Furthermore, the ability of toxins to gain entry to cells can be used in novel bacterial toxin based immuno-therapies in order to deliver antigens into MHC Class I processing pathways. Whether the immunomodulatory properties of these toxins arose in order to enhance bacterial survival within hosts, to aid spread within the population or is pure serendipity, it is interesting to think that these same toxins potentially hold the key to preventing or treating human disease.
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Affiliation(s)
- David S Donaldson
- Department of Cellular and Molecular Medicine, School of Medicine Sciences, University of Bristol, Bristol, UK
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Schnitzler AC, Burke JM, Wetzler LM. Induction of cell signaling events by the cholera toxin B subunit in antigen-presenting cells. Infect Immun 2007; 75:3150-9. [PMID: 17353279 PMCID: PMC1932910 DOI: 10.1128/iai.00581-06] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Cholera toxin (CT) is one of the most effective and widely studied mucosal adjuvants. Although the ADP-ribosylating A subunit has been implicated in augmenting immune responses, the receptor-binding B subunit (CT-B) has greater immunogenicity and may be a repository of adjuvant activity without potential toxicity. In order to elucidate mechanisms of immune modulation by CT-B alone, primary B cells and macrophages were assessed for responses to CT-B in vitro, as measured by the expression of cell surface markers, cellular signaling events, and cytokine secretion. Increased phosphorylation of multiple signaling molecules, including Erk1/2 and p38, was detected. CT-B also induced transactivation of the transcription elements cyclic AMP-responsive element and NF-kappaB, the latter of which was inhibited by phosphotyrosine inhibition. While specific inhibition of MEK1/2 did not reduce CT-B induction of cell surface marker expression, it did attenuate CT-B-mediated interleukin-6 secretion. These data show that CT-B induces a set of signaling events related to cellular activation, surface molecule expression, and cytokine production that has potential implications for elucidating CT-B adjuvant activity in the absence of enzymatically active holotoxin.
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Affiliation(s)
- Aletta C Schnitzler
- Evans Biomedical Research Center, Boston University School of Medicine, 650 Albany Street, Boston, MA 02118, USA
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15
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Daniel J, Marechal Y, Van Gool F, Andris F, Leo O. Nicotinamide inhibits B lymphocyte activation by disrupting MAPK signal transduction. Biochem Pharmacol 2006; 73:831-42. [PMID: 17188249 DOI: 10.1016/j.bcp.2006.11.024] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2006] [Revised: 11/08/2006] [Accepted: 11/27/2006] [Indexed: 01/16/2023]
Abstract
Nicotinamide (NAm) represents both a pharmacological agent known to express cell preserving and anti-inflammatory properties, and a useful investigational tool to elucidate cellular pathways regulating a wide range of cellular functions. We demonstrate in this study that exogenous NAm, when used at pharmacological doses, inhibits activation of primary murine B lymphocytes in response to multiple ligands. NAm appears to affect a membrane proximal event leading to MAPKs activation, a transduction pathway shared by multiple receptors including the antigen-specific B cell receptor, CD38, CD40 and TLR4 receptors. NAm inhibited phospho-ERK accumulation, and only marginally affected phospho-p38 and phospho-JNK induction upon BCR stimulation of naive B lymphocytes. Accordingly, NAm also affected the expression of known targets of the MAPK ERK pathway such as CD69 and cyclin D2. Based on a comparison with well-characterized pharmacological inhibitors, we suggest in this work that NAm may inhibit a post-translational modification mediated by a yet unidentified mono(ADP-ribose)transferase. Collectively, our observations indicate that in addition to its previously described effect on cells of the innate immune system, NAm is able to modulate the activity of B lymphocytes suggesting a potential role of this vitamin in regulating antibody-mediated autoimmune disorders.
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Affiliation(s)
- Julien Daniel
- Laboratoire de Physiologie Animale, Institut de Biologie et Médecine Moléculaire IBMM, Faculté des Sciences, Université Libre de Bruxelles, Belgium
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Fingerut E, Gutter B, Goldway M, Eliahoo D, Pitcovski J. B subunit of E. coli enterotoxin as adjuvant and carrier in oral and skin vaccination. Vet Immunol Immunopathol 2006; 112:253-63. [PMID: 16701905 DOI: 10.1016/j.vetimm.2006.03.005] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2005] [Revised: 02/26/2006] [Accepted: 03/14/2006] [Indexed: 02/01/2023]
Abstract
Mucosal sites are one of the main natural ports of entry into the body. Stimulation of a local response by antibodies as the systemic protection may enhance the efficacy of non-living vaccines, and allow for vaccination by subunit vaccines without the need for injection. Mucosal or skin vaccination necessitates a suitable adjuvant and carrier. Escherichia coli heat-labile enterotoxin (LT) and its B subunit (LTB) have been found to be effective adjuvants. The aim of this study was to efficiently produce and purify recombinant LTB (brLTB), and examine its adjuvant and carrier properties. The gene encoding LTB was cloned and expressed in E. coli, and the product was found to have a pentameric form with the ability to bind the cell receptor, GM1 ganglioside. A one-step method for efficient purification and concentration of brLTB was developed. Both oral and intramuscular vaccination with purified brLTB yielded high antibody titers, which detected the whole toxin. In an attempt to test its adjuvant characteristics, brLTB was mixed with either BSA or a recombinant protein (rKnob of egg drop syndrome adenovirus) and delivered intramuscularly, orally or transcutaneously. The addition of brLTB significantly elevated the antibody response in groups vaccinated orally and transcutaneously, but had no influence in injected groups. Vaccination with another recombinant protein, (viral protein 2 of infectious bursal disease virus) supplemented with brLTB did not elevate the antibody response, as compared to vaccination with the antigen alone. These results demonstrate that the addition of brLTB makes oral and transcutaneous vaccination with protein antigens possible.
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Affiliation(s)
- E Fingerut
- Migal, P.O. Box 831, Kiryat Shmona 11016, Israel
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Cox E, Verdonck F, Vanrompay D, Goddeeris B. Adjuvants modulating mucosal immune responses or directing systemic responses towards the mucosa. Vet Res 2006; 37:511-39. [PMID: 16611561 DOI: 10.1051/vetres:2006014] [Citation(s) in RCA: 101] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2005] [Accepted: 01/10/2006] [Indexed: 12/21/2022] Open
Abstract
In developing veterinary mucosal vaccines and vaccination strategies, mucosal adjuvants are one of the key players for inducing protective immune responses. Most of the mucosal adjuvants seem to exert their effect via binding to a receptor/or target cells and these properties were used to classify the mucosal adjuvants reviewed in the present paper: (1) ganglioside receptor-binding toxins (cholera toxin, LT enterotoxin, their B subunits and mutants); (2) surface immunoglobulin binding complex CTA1-DD; (3) TLR4 binding lipopolysaccharide; (4) TLR2-binding muramyl dipeptide; (5) Mannose receptor-binding mannan; (6) Dectin-1-binding ss 1,3/1,6 glucans; (7) TLR9-binding CpG-oligodeoxynucleotides; (8) Cytokines and chemokines; (9) Antigen-presenting cell targeting ISCOMATRIX and ISCOM. In addition, attention is given to two adjuvants able to prime the mucosal immune system following a systemic immunization, namely 1alpha, 25(OH)2D3 and cholera toxin.
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Affiliation(s)
- Eric Cox
- Laboratory of Immunology, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, 9820 Merelbeke, Belgium.
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Salmond RJ, Williams R, Hirst TR, Williams NA. The B subunit of Escherichia coli heat-labile enterotoxin induces both caspase-dependent and -independent cell death pathways in CD8+ T cells. Infect Immun 2004; 72:5850-7. [PMID: 15385486 PMCID: PMC517530 DOI: 10.1128/iai.72.10.5850-5857.2004] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2004] [Revised: 03/30/2004] [Accepted: 06/25/2004] [Indexed: 12/20/2022] Open
Abstract
The nontoxic B subunit of Escherichia coli heat-labile enterotoxin (EtxB) is a potent immunomodulatory molecule that acts both as an adjuvant and to stimulate immune deviation processes, resulting in the suppression of Th1-associated inflammatory responses. The ability of EtxB to alter immune reactivity is dependent on its ability to modulate immune cell function through binding to cell surface molecules, the principal receptor of which is the ubiquitous GM1-ganglioside. EtxB activates B cells and antigen-presenting cells and induces the selective apoptosis of murine CD8+ T cells. We postulated that these effects are mediated by the induction of intracellular signaling pathways following EtxB-receptor interaction. We have previously shown that CD8+ T-cell apoptosis induced by EtxB results from the activation of the transcription factor NF-kappaB and caspases. Here we report that while caspase activity is required for apoptosis, additional features of cell death are caspase independent. EtxB induces a rapid loss of mitochondrial membrane potential and cell viability that are unaffected by caspase inhibitors. In addition, our data suggest that these processes are independent of the activity of Bax and Bcl-2 but are mediated by nitric oxide synthase.
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Affiliation(s)
- Robert J Salmond
- Department of Pathology and Microbiology, School of Medical Sciences, University of Bristol, Bristol, United Kingdom
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Salmond RJ, Williams R, Hirst TR, Williams NA. Selective induction of CD8+CD4- thymocyte apoptosis mediated by the B-subunit of Escherichia coli heat-labile enterotoxin. Immunol Lett 2003; 88:43-6. [PMID: 12853160 DOI: 10.1016/s0165-2478(03)00049-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Receptor-binding by the B-subunit of Escherichia coli heat-labile enterotoxin (EtxB) induces apoptosis of peripheral CD8(+), but not CD4(+) T-cells. Given that peripheral CD8(+) and CD4(+) T cells arise from a common developmental pathway in the thymus, we investigated the effects of EtxB on different thymocyte populations. We show that the acquisition of sensitivity to EtxB-mediated cell death arises following transition of CD4(+)CD8(+) double positive cells into the CD4(-)CD8(+) pathway. Maturation of T cells into CD4(-)CD8(+) single positive cells is associated with upregulated expression of receptors for EtxB.
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Affiliation(s)
- Robert J Salmond
- Department of Pathology and Microbiology, School of Medical Sciences, University of Bristol, University Walk, Bristol, BS8 1TD, UK
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Fraser SA, de Haan L, Hearn AR, Bone HK, Salmond RJ, Rivett AJ, Williams NA, Hirst TR. Mutant Escherichia coli heat-labile toxin B subunit that separates toxoid-mediated signaling and immunomodulatory action from trafficking and delivery functions. Infect Immun 2003; 71:1527-37. [PMID: 12595472 PMCID: PMC148879 DOI: 10.1128/iai.71.3.1527-1537.2003] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The homopentameric B-subunit components of Escherichia coli heat-labile enterotoxin (EtxB) and cholera toxin (CtxB) possess the capacity to enter mammalian cells and to activate cell-signaling events in leukocytes that modulate immune cell function. Both properties have been attributed to the ability of the B subunits to bind to GM1-ganglioside receptors, a ubiquitous glycosphingolipid found in the plasma membrane. Here we describe the properties of EtxB(H57S), a mutant B subunit with a His-->Ser substitution at position 57. The mutant was found to be severely defective in inducing leukocyte signaling, as shown by failure to (i) trigger caspase 3-mediated CD8(+)-T-cell apoptosis, (ii) activate nuclear translocation of NF-kappaB in Jurkat T cells, (iii) induce a potent anti-B-subunit response in mice, or (iv) serve as a mucosal adjuvant. However, its GM1 binding, cellular uptake, and delivery functions remained intact. This was further validated by the finding that EtxB(H57S) was as effective as EtxB in delivering a conjugated model class I epitope into the major histocompatibility complex class I pathway of a dendritic cell line. These observations imply that GM1 binding alone is not sufficient to trigger the signaling events responsible for the potent immunomodulatory properties of EtxB. Moreover, they demonstrate that its signaling properties play no role in EtxB uptake and trafficking. Thus, EtxB(H57S) represents a novel tool for evaluating the complex cellular interactions and signaling events occurring after receptor interaction, as well as offering an alternative means of delivering attached peptides in the absence of the potent immunomodulatory signals induced by wild-type B subunits.
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Affiliation(s)
- Sylvia A Fraser
- Department of Pathology & Microbiology, School of Medical Sciences, University of Bristol, University Walk, Bristol BS8 1TD, United Kingdom
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