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Bryson A, Gonzalez G, Al-Atoom N, Nashar N, Smith JR, Nashar T. Extracellular vesicles are conduits for E. coli heat-labile enterotoxin (LT) and the B-subunits of LT and cholera toxin in immune cell-to-cell communication. Microb Pathog 2023; 177:106038. [PMID: 36841487 PMCID: PMC10065948 DOI: 10.1016/j.micpath.2023.106038] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2022] [Revised: 02/04/2023] [Accepted: 02/20/2023] [Indexed: 02/26/2023]
Abstract
Several pathogens excrete their toxins either directly into the host or through extracellular vesicles. Enterotoxigenic E. coli is capable of secreting heat-labile toxin LT in extracellular vesicles (EVs) which are delivered to mammalian cells. LT and its B-subunit, LTB, and their structurally and functionally related toxin from Vibrio cholerae, CT and CTB, are potent immunogens and adjuvants. However, despite their reported remarkable effects on immune cells, the mechanisms by which they mediate their immunological properties are still unclear. We show that B cells incubated with LT or LTB secreted EVs in the cell culture medium. However, compared to unstimulated cells, EVs and their internal protein content were significantly reduced in recipient B cells. Analysis of protein markers of the vesicles secreted by B cells were found to be enriched in exosomes of endosomal origin. B cells incubated with FITC-CTB secreted CTB in EVs which were taken up by recipient B and T cells. FITC-CTB transfected into exosomes from mouse dendritic cells were also taken up by recipient B cells. Moreover, B cells incubated with FITC-CTB secreted CTB in EVs which increased the number of recipient B cells expressing higher levels of CD25 and CD86. These results suggest that EVs from B cells are conduits for the enterotoxins, and play an important role in the enterotoxins immune cell-to-cell communication. This is the first report which looked at EVs as a mean to deliver these proteins from and to immune cells.
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Affiliation(s)
- Andreya Bryson
- Tuskegee University, College of Veterinary Medicine, Department of Pathobiology, Tuskegee, AL, AL 36088, USA
| | - Gabrielle Gonzalez
- Tuskegee University, College of Veterinary Medicine, Department of Pathobiology, Tuskegee, AL, AL 36088, USA
| | - Nadia Al-Atoom
- Tuskegee University, College of Veterinary Medicine, Department of Pathobiology, Tuskegee, AL, AL 36088, USA
| | - Nijad Nashar
- The University at Buffalo, School of Pharmacy and Pharmaceutical Sciences, Buffalo, NY, 14215, USA
| | - Ja R'eika Smith
- Tuskegee University, College of Veterinary Medicine, Department of Pathobiology, Tuskegee, AL, AL 36088, USA
| | - Toufic Nashar
- Tuskegee University, College of Veterinary Medicine, Department of Pathobiology, Tuskegee, AL, AL 36088, USA.
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Ji J, Griffiths KL, Milburn PJ, Hirst TR, O'Neill HC. The B subunit of Escherichia coli heat-labile toxin alters the development and antigen-presenting capacity of dendritic cells. J Cell Mol Med 2015; 19:2019-31. [PMID: 26130503 PMCID: PMC4549052 DOI: 10.1111/jcmm.12599] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2015] [Accepted: 03/25/2015] [Indexed: 02/05/2023] Open
Abstract
Escherichia coli's heat-labile enterotoxin (Etx) and its non-toxic B subunit (EtxB) have been characterized as adjuvants capable of enhancing T cell responses to co-administered antigen. Here, we investigate the direct effect of intravenously administered EtxB on the size of the dendritic and myeloid cell populations in spleen. EtxB treatment appears to enhance the development and turnover of dendritic and myeloid cells from precursors within the spleen. EtxB treatment also gives a dendritic cell (DC) population with higher viability and lower activation status based on the reduced expression of MHC-II, CD80 and CD86. In this respect, the in vivo effect of EtxB differs from that of the highly inflammatory mediator lipopolysaccharide. In in vitro bone marrow cultures, EtxB treatment was also found to enhance the development of DC from precursors dependent on Flt3L. In terms of the in vivo effect of EtxB on CD4 and CD8 T cell responses in mice, the interaction of EtxB directly with DC was demonstrated following conditional depletion of CD11c(+) DC. In summary, all results are consistent with EtxB displaying adjuvant ability by enhancing the turnover of DC in spleen, leading to newly mature myeloid and DC in spleen, thereby increasing DC capacity to perform as antigen-presenting cells on encounter with T cells.
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Affiliation(s)
- Jing Ji
- Research School of Biology, Australian National University, Canberra, ACT, Australia
| | - Kristin L Griffiths
- Research School of Biology, Australian National University, Canberra, ACT, Australia
| | - Peter J Milburn
- John Curtin School of Medical Research, Australian National University, Canberra, ACT, Australia
| | - Timothy R Hirst
- John Curtin School of Medical Research, Australian National University, Canberra, ACT, Australia
| | - Helen C O'Neill
- Faculty of Health Sciences and Medicine, Bond University, Gold Coast, QLD 4229, Australia
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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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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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Martin K, Nashar TO. E. coli Heat-labile Enterotoxin B Subunit as a Platform for the Delivery of HIV Gag p24 Antigen. ACTA ACUST UNITED AC 2013; 4. [PMID: 27375923 PMCID: PMC4929988 DOI: 10.4172/2155-9899.1000140] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Multiple vaccination strategies have been devised against HIV-1 including delivery of HIV moieties in attenuated or replication defective recombinant microbial agents alone or in combination with priming agents in form of soluble proteins or naked DNA. For the priming agents to be effective, adjuvants might be essential in directing the immune response to a desired outcome. E. coli enterotoxin B subunit (LTB) is an effective adjuvant and carrier for other proteins and epitopes. Here we show that conjugation of HIV gag p24 to LTB enhances the T cell response to gag p24 by increasing rate of T cell division compared to other treatments. Because HIV vaccines are likely to be multivalent, we further investigated whether gag p24 inhibits antigen presentation of an unrelated antigen, OVA. Addition of gag p24 to OVA-responsive DO.11.10 cell culture did not have adverse effects on antigen presentation. Interestingly, the presence of LTB in these cultures significantly increased proliferation of DO.11.10 cells. In all, the results suggest the use of LTB to boost immune responses against HIV gag p24 in systemic priming regimens with oral recombinant HIV vaccines.
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Affiliation(s)
- Karmarcha Martin
- College of Veterinary Medicine, Nursing and Allied Health, Department of Pathobiology, Tuskegee University, Tuskegee, AL 36088, USA
| | - Toufic O Nashar
- College of Veterinary Medicine, Nursing and Allied Health, Department of Pathobiology, Tuskegee University, Tuskegee, AL 36088, USA
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Sun JB, Flach CF, Czerkinsky C, Holmgren J. B Lymphocytes Promote Expansion of Regulatory T Cells in Oral Tolerance: Powerful Induction by Antigen Coupled to Cholera Toxin B Subunit. THE JOURNAL OF IMMUNOLOGY 2008; 181:8278-87. [DOI: 10.4049/jimmunol.181.12.8278] [Citation(s) in RCA: 117] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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Tanaka T, Furutama D, Sakai R, Fujita A, Kimura F, Tagami M, Ohsawa N, Hanafusa T. Biological roles of anti-GM1 antibodies in patients with Guillain-Barré syndrome for nerve growth factor signaling. Biochim Biophys Acta Mol Basis Dis 2007; 1772:543-8. [PMID: 17355906 DOI: 10.1016/j.bbadis.2007.01.011] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2006] [Revised: 12/28/2006] [Accepted: 01/23/2007] [Indexed: 11/29/2022]
Abstract
To reveal the biological and pathological roles of anti-GM1 antibody in Guillain-Barré syndrome (GBS), we examined its effects on nerve growth factor (NGF) induced TrkA autophosphorylation (NGF-TrkA signaling) in PC12 cells, a sympathetic nerve cell line. The NGF-TrkA signaling is enhanced by exogenous GM1 ganglioside and this phenomenon is regarded as one of the functional aspects of GM1. The IgGs purified from patients' sera inhibited the NGF-TrkA signaling in GM1 pre-incubated PC12 cells. The degrees of inhibition by IgGs from patients paralleled their immunological reactivity to GM1. In addition, the IgGs also inhibited the neurite outgrowth of NGF-treated PC12 cells. Immunoglobulins in the rabbit sera, which were immunized by GM1, also caused a similar suppressive phenomenon. These results suggested that the anti-GM1 antibody could play roles in pathophysiology in anti-GM1 antibody positive GBS through interfering with the neurotrophic action of NGF and GM1 mediated signal modulation including NGF-TrkA signaling. It is suggested that the modulation of GM1 function is one important action of antibodies and could be one of the important mechanisms in GBS.
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Affiliation(s)
- Toshifumi Tanaka
- Aino Institute for Aging Research, Oda 27, Ibaraki-city, Osaka 567-0018, Japan
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