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Paparella AS, Brew I, Hong HA, Ferriera W, Cutting S, Lamiable-Oulaidi F, Popadynec M, Tyler PC, Schramm VL. Isofagomine Inhibits Multiple TcdB Variants and Protects Mice from Clostridioides difficile-Induced Mortality. ACS Infect Dis 2024; 10:928-937. [PMID: 38334357 DOI: 10.1021/acsinfecdis.3c00507] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/10/2024]
Abstract
Clostridioides difficile causes life-threatening diarrhea and is one of the leading causes of nosocomial infections. During infection, C. difficile releases two gut-damaging toxins, TcdA and TcdB, which are the primary determinants of disease pathogenesis and are important therapeutic targets. Once in the cytosol of mammalian cells, TcdA and TcdB use UDP-glucose to glucosylate host Rho GTPases, which leads to cytoskeletal changes that result in a loss of intestinal integrity. Isofagomine inhibits TcdA and TcdB as a mimic of the glucocation transition state of the glucosyltransferase reaction. However, sequence variants of TcdA and TcdB across the clades of infective C. difficile continue to be identified, and therefore, evaluation of isofagomine inhibition against multiple toxin variants is required. Here, we show that isofagomine inhibits the glucosyltransferase domain of multiple TcdB variants and protects TcdB-induced cell rounding of the most common full-length toxin variants. Furthermore, we demonstrate that isofagomine protects against C. difficile-induced mortality in two murine models of C. difficile infection. Isofagomine treatment of mouse C. difficile infection also permitted the recovery of the gastrointestinal microbiota, an important barrier to preventing recurring C. difficile infection. The broad specificity of isofagomine supports its potential as a prophylactic to protect against C. difficile-induced morbidity and mortality.
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Affiliation(s)
- Ashleigh S Paparella
- Department of Biochemistry, Albert Einstein College of Medicine, Bronx, New York 10461, United States
| | - Isabella Brew
- Department of Biochemistry, Albert Einstein College of Medicine, Bronx, New York 10461, United States
| | - Huynh A Hong
- SporeGen Ltd., The London BioScience Innovation Centre, London NW1 0NH, U.K
| | - William Ferriera
- SporeGen Ltd., The London BioScience Innovation Centre, London NW1 0NH, U.K
| | - Simon Cutting
- SporeGen Ltd., The London BioScience Innovation Centre, London NW1 0NH, U.K
| | - Farah Lamiable-Oulaidi
- The Ferrier Research Institute, Victoria University of Wellington, Lower Hutt 5010, New Zealand
| | - Michael Popadynec
- The Ferrier Research Institute, Victoria University of Wellington, Lower Hutt 5010, New Zealand
| | - Peter C Tyler
- The Ferrier Research Institute, Victoria University of Wellington, Lower Hutt 5010, New Zealand
| | - Vern L Schramm
- Department of Biochemistry, Albert Einstein College of Medicine, Bronx, New York 10461, United States
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Aminzadeh A, Hilgers L, Paul Platenburg P, Riou M, Perrot N, Rossignol C, Cauty A, Barc C, Jørgensen R. Immunogenicity and safety in rabbits of a Clostridioides difficile vaccine combining novel toxoids and a novel adjuvant. Vaccine 2024; 42:1582-1592. [PMID: 38336558 DOI: 10.1016/j.vaccine.2024.01.076] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2022] [Revised: 12/12/2023] [Accepted: 01/23/2024] [Indexed: 02/12/2024]
Abstract
Clostridioides difficile infection (CDI) is a serious healthcare-associated disease, causing symptoms such as diarrhea and pseudomembranous colitis. The major virulence factors responsible for the disease symptoms are two secreted cytotoxic proteins, TcdA and TcdB. A parenteral vaccine based on formaldehyde-inactivated TcdA and TcdB supplemented with alum adjuvant, has previously been investigated in humans but resulted in an insufficient immune response. In search for an improved response, we investigated a novel toxin inactivation method and a novel, potent adjuvant. Inactivation of toxins by metal-catalyzed oxidation (MCO) was previously shown to preserve neutralizing epitopes and to annihilate reversion to toxicity. The immunogenicity and safety of TcdA and TcdB inactivated by MCO and combined with a novel carbohydrate fatty acid monosulphate ester-based (CMS) adjuvant were investigated in rabbits. Two or three intramuscular immunizations generated high serum IgG and neutralizing antibody titers against both toxins. The CMS adjuvant increased antibody responses to both toxins while an alum adjuvant control was effective only against TcdA. Systemic safety was evaluated by monitoring body weight, body temperature, and analysis of red and white blood cell counts shortly after immunization. Local safety was assessed by histopathologic examination of the injection site at the end of the study. Body weight gain was constant in all groups. Body temperature increased up to 1 ˚C one day after the first immunization but less after the second or third immunization. White blood cell counts, and percentage of neutrophils increased one day after immunization with CMS-adjuvanted vaccines, but not with alum. Histopathology of the injection sites 42 days after the last injection did not reveal any abnormal tissue reactions. From this study, we conclude that TcdA and TcdB inactivated by MCO and combined with CMS adjuvant demonstrated promising immunogenicity and safety in rabbits and could be a candidate for a vaccine against CDI.
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Affiliation(s)
- Aria Aminzadeh
- Proxi Biotech ApS, Egeskellet 6, 2000 Frederiksberg, Denmark; Department of Science and Environment, University of Roskilde, 4000 Roskilde, Denmark
| | - Luuk Hilgers
- LiteVax BV, Akkersestraat 50, 4061BJ Ophemert, the Netherlands
| | | | - Mickaël Riou
- INRAE, UE-1277 Plateforme d'Infectiologie expérimentale (PFIE), Centre Val de Loire, 37380 Nouzilly, France
| | - Noémie Perrot
- INRAE, UE-1277 Plateforme d'Infectiologie expérimentale (PFIE), Centre Val de Loire, 37380 Nouzilly, France
| | - Christelle Rossignol
- INRAE-Université de Tours, UMR-1282 Infectiologie et Santé publique (ISP), équipe IMI, Centre Val de Loire, 37380 Nouzilly, France
| | - Axel Cauty
- INRAE, UE-1277 Plateforme d'Infectiologie expérimentale (PFIE), Centre Val de Loire, 37380 Nouzilly, France
| | - Céline Barc
- INRAE, UE-1277 Plateforme d'Infectiologie expérimentale (PFIE), Centre Val de Loire, 37380 Nouzilly, France
| | - René Jørgensen
- Proxi Biotech ApS, Egeskellet 6, 2000 Frederiksberg, Denmark; Department of Science and Environment, University of Roskilde, 4000 Roskilde, Denmark.
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Sapa D, Brosse A, Coullon H, Péan de Ponfilly G, Candela T, Le Monnier A. A Streamlined Method to Obtain Biologically Active TcdA and TcdB Toxins from Clostridioides difficile. Toxins (Basel) 2024; 16:38. [PMID: 38251254 PMCID: PMC10821508 DOI: 10.3390/toxins16010038] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2023] [Revised: 12/15/2023] [Accepted: 12/30/2023] [Indexed: 01/23/2024] Open
Abstract
The major virulence factors of Clostridioides difficile (C. difficile) are enterotoxins A (TcdA) and B (TcdB). The study of toxins is a crucial step in exploring the virulence of this pathogen. Currently, the toxin purification process is either laborious and time-consuming in C. difficile or performed in heterologous hosts. Therefore, we propose a streamlined method to obtain functional toxins in C. difficile. Two C. difficile strains were generated, each harboring a sequence encoding a His-tag at the 3' end of C. difficile 630∆erm tcdA or tcdB genes. Each toxin gene is expressed using the Ptet promoter, which is inducible by anhydro-tetracycline. The obtained purification yields were 0.28 mg and 0.1 mg per liter for rTcdA and rTcdB, respectively. In this study, we successfully developed a simple routine method that allows the production and purification of biologically active rTcdA and rTcdB toxins with similar activities compared to native toxins.
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Affiliation(s)
- Diane Sapa
- Micalis Institute, Université Paris-Saclay, INRAE, AgroParisTech, 78350 Jouy-en-Josas, France; (D.S.); (H.C.); (G.P.d.P.); (T.C.); (A.L.M.)
| | - Anaïs Brosse
- Micalis Institute, Université Paris-Saclay, INRAE, AgroParisTech, 78350 Jouy-en-Josas, France; (D.S.); (H.C.); (G.P.d.P.); (T.C.); (A.L.M.)
| | - Héloïse Coullon
- Micalis Institute, Université Paris-Saclay, INRAE, AgroParisTech, 78350 Jouy-en-Josas, France; (D.S.); (H.C.); (G.P.d.P.); (T.C.); (A.L.M.)
| | - Gauthier Péan de Ponfilly
- Micalis Institute, Université Paris-Saclay, INRAE, AgroParisTech, 78350 Jouy-en-Josas, France; (D.S.); (H.C.); (G.P.d.P.); (T.C.); (A.L.M.)
- Service de Microbiologie Clinique, GH Paris Saint-Joseph, 75674 Paris, France
| | - Thomas Candela
- Micalis Institute, Université Paris-Saclay, INRAE, AgroParisTech, 78350 Jouy-en-Josas, France; (D.S.); (H.C.); (G.P.d.P.); (T.C.); (A.L.M.)
| | - Alban Le Monnier
- Micalis Institute, Université Paris-Saclay, INRAE, AgroParisTech, 78350 Jouy-en-Josas, France; (D.S.); (H.C.); (G.P.d.P.); (T.C.); (A.L.M.)
- Service de Microbiologie Clinique, GH Paris Saint-Joseph, 75674 Paris, France
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Bharathkar SK, Miller MJ, Stadtmueller BM. Engineered Secretory Immunoglobulin A provides insights on antibody-based effector mechanisms targeting Clostridiodes difficile. bioRxiv 2023:2023.11.08.566291. [PMID: 37986930 PMCID: PMC10659285 DOI: 10.1101/2023.11.08.566291] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2023]
Abstract
Secretory (S) Immunoglobin (Ig) A is the predominant mucosal antibody, which mediates host interactions with commensal and pathogenic microbes, including Clostridioides difficile. SIgA adopts a polymeric IgA structure that is bound by secretory component (SC). Despite significance, how SIgA supports diverse effector mechanisms is poorly characterized and SIgA-based therapies nonexistent. We engineered chimeric (c) SIgAs, in which we replaced SC domain D2 with a single domain antibody or a monomeric fluorescent protein, allowing us to investigate and enhance SIgA effector mechanisms. cSIgAs exhibited increased neutralization potency against C. difficile toxins, promoted bacterial clumping and cell rupture, and decreased cytotoxicity. cSIgA also allowed us to visualize and/or quantify C. difficile morphological changes and clumping events. Results reveal mechanisms by which SIgA combats C. difficile infection, demonstrate that cSIgA design can modulate these mechanisms, and demonstrate cSIgA's adaptability to modifications that might target a broad range of antigens and effector mechanisms.
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Affiliation(s)
- Sonya Kumar Bharathkar
- Department of Biochemistry, University of Illinois Urbana-Champaign, Urbana, Illinois 61801 USA
| | - Michael J. Miller
- Carle R. Woese Institute of Genomic Biology
- Department of food science and Human Nutrition, University of Illinois Urbana-Champaign, Illinois 61801 USA
| | - Beth M. Stadtmueller
- Department of Biochemistry, University of Illinois Urbana-Champaign, Urbana, Illinois 61801 USA
- Department of Biomedical and Translational Sciences, Carle Illinois College of Medicine, University of Illinois Urbana-Champaign, Urbana, Illinois 61801 USA
- Carle R. Woese Institute of Genomic Biology
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Mavrogeni ME, Asadpoor M, Judernatz JH, van Ark I, Wösten MMSM, Strijbis K, Pieters RJ, Folkerts G, Braber S. Protective Effects of Alginate and Chitosan Oligosaccharides against Clostridioides difficile Bacteria and Toxin. Toxins (Basel) 2023; 15:586. [PMID: 37888617 PMCID: PMC10610568 DOI: 10.3390/toxins15100586] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2022] [Revised: 09/01/2023] [Accepted: 09/12/2023] [Indexed: 10/28/2023] Open
Abstract
Clostridioides difficile infection is expected to become the most common healthcare-associated infection worldwide. C. difficile-induced pathogenicity is significantly attributed to its enterotoxin, TcdA, which primarily targets Rho-GTPases involved in regulating cytoskeletal and tight junction (TJ) dynamics, thus leading to cytoskeleton breakdown and ultimately increased intestinal permeability. This study investigated whether two non-digestible oligosaccharides (NDOs), alginate (AOS) and chitosan (COS) oligosaccharides, possess antipathogenic and barrier-protective properties against C. difficile bacteria and TcdA toxin, respectively. Both NDOs significantly reduced C. difficile growth, while cell cytotoxicity assays demonstrated that neither COS nor AOS significantly attenuated the TcdA-induced cell death 24 h post-exposure. The challenge of Caco-2 monolayers with increasing TcdA concentrations increased paracellular permeability, as measured by TEER and LY flux assays. In this experimental setup, COS completely abolished, and AOS mitigated, the deleterious effects of TcdA on the monolayer's integrity. These events were not accompanied by alterations in ZO-1 and occludin protein levels; however, immunofluorescence microscopy revealed that both AOS and COS prevented the TcdA-induced occludin mislocalization. Finally, both NDOs accelerated TJ reassembly upon a calcium-switch assay. Overall, this study established the antipathogenic and barrier-protective capacity of AOS and COS against C. difficile and its toxin, TcdA, while revealing their ability to promote TJ reassembly in Caco-2 cells.
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Affiliation(s)
- Maria Eleni Mavrogeni
- Division of Pharmacology, Utrecht Institute for Pharmaceutical Sciences, Faculty of Science, Utrecht University, Universiteitsweg 99, 3584 CG Utrecht, The Netherlands
| | - Mostafa Asadpoor
- Division of Pharmacology, Utrecht Institute for Pharmaceutical Sciences, Faculty of Science, Utrecht University, Universiteitsweg 99, 3584 CG Utrecht, The Netherlands
| | - Jo H Judernatz
- Structural Biochemistry Group, Bijvoet Centre for Biomolecular Research, Utrecht University, Universiteitsweg 99, 3584 CG Utrecht, The Netherlands
| | - Ingrid van Ark
- Division of Pharmacology, Utrecht Institute for Pharmaceutical Sciences, Faculty of Science, Utrecht University, Universiteitsweg 99, 3584 CG Utrecht, The Netherlands
| | - Marc M S M Wösten
- Division of Infectious Diseases and Immunology, Department of Biomolecular Health Sciences, Faculty of Veterinary Medicine, Utrecht University, Yalelaan 1, 3584 CL Utrecht, The Netherlands
| | - Karin Strijbis
- Division of Infectious Diseases and Immunology, Department of Biomolecular Health Sciences, Faculty of Veterinary Medicine, Utrecht University, Yalelaan 1, 3584 CL Utrecht, The Netherlands
| | - Roland J Pieters
- Division of Medicinal Chemistry and Chemical Biology, Utrecht Institute for Pharmaceutical Sciences, Faculty of Science, Utrecht University, Universiteitsweg 99, 3584 CG Utrecht, The Netherlands
| | - Gert Folkerts
- Division of Pharmacology, Utrecht Institute for Pharmaceutical Sciences, Faculty of Science, Utrecht University, Universiteitsweg 99, 3584 CG Utrecht, The Netherlands
| | - Saskia Braber
- Division of Pharmacology, Utrecht Institute for Pharmaceutical Sciences, Faculty of Science, Utrecht University, Universiteitsweg 99, 3584 CG Utrecht, The Netherlands
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6
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Raeisi H, Azimirad M, Asadzadeh Aghdaei H, Zarnani AH, Abdolalizadeh J, Yadegar A, Zali MR. Development and characterization of phage display-derived anti-toxin antibodies neutralizing TcdA and TcdB of Clostridioides difficile. Microbiol Spectr 2023; 11:e0531022. [PMID: 37668373 PMCID: PMC10580902 DOI: 10.1128/spectrum.05310-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2022] [Accepted: 06/08/2023] [Indexed: 09/06/2023] Open
Abstract
TcdA and TcdB are known as the major virulence attributes of Clostridioides difficile. Hence, neutralizing the TcdA and TcdB activities can be considered as an efficient therapeutic approach against C. difficile infection (CDI). In this work, we utilized phage display technique to select single-chain fragment variable (scFv) fragments as recombinant antibodies displayed on the surface of phages, which specifically target native TcdA, or TcdB (nTcdA and nTcdB), and their recombinant C-terminal combined repetitive oligopeptide (CROP) domains (rTcdA and rTcdB). After three rounds of biopanning, abundance of phage clones displaying high reactivity with TcdA or TcdB was quantified through enzyme-linked immunosorbent assay (ELISA). Furthermore, selected scFvs were characterized by cell viability and neutralization assays. The gene expression of immunological markers, IL-8 and TNF-α, was examined in treated Caco-2 cells by RT-qPCR. The epitopes of neutralizing scFvs were also identified by molecular docking. Totally, 18 scFv antibodies (seven for TcdA and 11 for TcdB) were identified by ELISA. Among selected scFvs, two clones for TcdA (rA-C2, A-C9) and three clones for TcdB (rB-B4, B-F5, B-F11) exhibited the highest neutralizing activity in Caco-2 and Vero cells. Moreover, the cocktail of anti-TcdA and anti-TcdB antibodies notably decreased the mRNA expression of TNF-α and IL-8 in Caco-2 cells. Molecular docking revealed that the interaction between scFv and toxin was mostly restricted to CROP domain of TcdA or TcdB. Our results collectively provided more insights for the development of neutralizing scFvs against C. difficile toxins using phage display. Further research is needed to meticulously evaluate the potential of scFvs as an alternative treatment for CDI using animal models and clinical trials.IMPORTANCETargeting the major toxins of Clostridioides difficile by neutralizing antibodies is a novel therapeutic approach for CDI. Here, we report a panel of new anti-TcdA (rA-C2, A-C9) and anti-TcdB (rB-B4, B-F5, and B-F11) recombinant antibody fragments (scFvs) isolated from Tomlinson I and J libraries using phage display technique. These scFv antibodies were capable of neutralizing their respective toxin and showed promise as potential therapeutics against TcdA and TcdB of C. difficile in different in vitro models. In addition, in silico analysis showed that at least two neutralization mechanisms, including inhibiting cell surface binding of toxins and inhibiting toxin internalization can be proposed for the isolated scFvs in this work. These findings provide more insights for the applicability of specific scFvs toward C. difficile toxins at in vitro level. However, further research is required to evaluate the potential application of these scFvs as therapeutic agents for CDI treatment in clinical setting.
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Affiliation(s)
- Hamideh Raeisi
- Foodborne and Waterborne Diseases Research Center, Research Institute for Gastroenterology and Liver Diseases, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Masoumeh Azimirad
- Foodborne and Waterborne Diseases Research Center, Research Institute for Gastroenterology and Liver Diseases, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Hamid Asadzadeh Aghdaei
- Basic and Molecular Epidemiology of Gastrointestinal Disorders Research Center, Research Institute for Gastroenterology and Liver Diseases, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Amir-Hassan Zarnani
- Department of Immunology, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran
| | - Jalal Abdolalizadeh
- Immunology Research Center, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Abbas Yadegar
- Foodborne and Waterborne Diseases Research Center, Research Institute for Gastroenterology and Liver Diseases, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Mohammad Reza Zali
- Gastroenterology and Liver Diseases Research Center, Research Institute for Gastroenterology and Liver Diseases, Shahid Beheshti University of Medical Sciences, Tehran, Iran
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Bronnec P, Sousa J, Henry T. Inducing Pyroptosis Via the Pyrin Inflammasome. Methods Mol Biol 2023; 2641:37-47. [PMID: 37074640 DOI: 10.1007/978-1-0716-3040-2_4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/20/2023]
Abstract
The pyrin inflammasome detects bacterial toxins and effectors that inhibit RhoA GTPases and triggers inflammatory cytokine release and a fast cell death termed pyroptosis. In addition, various endogenous molecules, drugs, synthetic molecules, or mutations can trigger pyrin inflammasome activation. The pyrin protein differs between humans and mice, and the repertoire of pyrin activators is also species-specific. Here, we present the various pyrin inflammasome activators, inhibitors, the kinetics of pyrin activation in response to the various activators, and their species specificity. In addition, we present different methods to monitor pyrin-mediated pyroptosis.
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Affiliation(s)
- Pauline Bronnec
- CIRI, Centre International de Recherche en Infectiologie, Inserm U1111, Univ Lyon, Université Claude Bernard Lyon 1, CNRS, UMR5308, ENS de Lyon, Lyon, France
| | - Jeremy Sousa
- CIRI, Centre International de Recherche en Infectiologie, Inserm U1111, Univ Lyon, Université Claude Bernard Lyon 1, CNRS, UMR5308, ENS de Lyon, Lyon, France
| | - Thomas Henry
- CIRI, Centre International de Recherche en Infectiologie, Inserm U1111, Univ Lyon, Université Claude Bernard Lyon 1, CNRS, UMR5308, ENS de Lyon, Lyon, France.
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8
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Chen B, Perry K, Jin R. Neutralizing epitopes on Clostridioides difficile toxin A revealed by the structures of two camelid VHH antibodies. Front Immunol 2022; 13:978858. [PMID: 36466927 PMCID: PMC9709291 DOI: 10.3389/fimmu.2022.978858] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2022] [Accepted: 10/31/2022] [Indexed: 11/18/2022] Open
Abstract
Toxin A (TcdA) and toxin B (TcdB) are two key virulence factors secreted by Clostridioides difficile, which is listed as an urgent threat by the CDC. These two large homologous exotoxins are mainly responsible for diseases associated with C. difficile infection (CDI) with symptoms ranging from diarrhea to life threatening pseudomembranous colitis. Single-domain camelid antibodies (VHHs) AH3 and AA6 are two potent antitoxins against TcdA, which when combined with two TcdB-targeting VHHs showed effective protection against both primary and recurrent CDI in animal models. Here, we report the co-crystal structures of AH3 and AA6 when they form complexes with the glucosyltransferase domain (GTD) and a fragment of the delivery and receptor-binding domain (DRBD) of TcdA, respectively. Based on these structures, we find that AH3 binding enhances the overall stability of the GTD and interferes with its unfolding at acidic pH, and AA6 may inhibit the pH-dependent conformational changes in the DRBD that is necessary for pore formation of TcdA. These studies reveal two functionally critical epitopes on TcdA and shed new insights into neutralizing mechanisms and potential development of epitope-focused vaccines against TcdA.
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Affiliation(s)
- Baohua Chen
- Department of Physiology and Biophysics, School of Medicine, University of California, Irvine, CA, United States
| | - Kay Perry
- NE-CAT, Advanced Photon Source, Argonne National Laboratory, Argonne, IL, United States,Department of Chemistry and Chemical Biology, Cornell University, Argonne, IL, United States
| | - Rongsheng Jin
- Department of Physiology and Biophysics, School of Medicine, University of California, Irvine, CA, United States,*Correspondence: Rongsheng Jin,
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9
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Stieglitz F, Gerhard R, Hönig R, Giehl K, Pich A. TcdB of Clostridioides difficile Mediates RAS-Dependent Necrosis in Epithelial Cells. Int J Mol Sci 2022; 23:ijms23084258. [PMID: 35457076 PMCID: PMC9024770 DOI: 10.3390/ijms23084258] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2022] [Revised: 04/01/2022] [Accepted: 04/04/2022] [Indexed: 02/06/2023] Open
Abstract
A Clostridioides difficile infection (CDI) is the most common nosocomial infection worldwide. The main virulence factors of pathogenic C. difficile are TcdA and TcdB, which inhibit small Rho-GTPases. The inhibition of small Rho-GTPases leads to the so-called cytopathic effect, a reorganization of the actin cytoskeleton, an impairment of the colon epithelium barrier function and inflammation. Additionally, TcdB induces a necrotic cell death termed pyknosis in vitro independently from its glucosyltransferases, which are characterized by chromatin condensation and ROS production. To understand the underlying mechanism of this pyknotic effect, we conducted a large-scale phosphoproteomic study. We included the analysis of alterations in the phosphoproteome after treatment with TcdA, which was investigated for the first time. TcdA exhibited no glucosyltransferase-independent necrotic effect and was, thus, a good control to elucidate the underlying mechanism of the glucosyltransferase-independent effect of TcdB. We found RAS to be a central upstream regulator of the glucosyltransferase-independent effect of TcdB. The inhibition of RAS led to a 68% reduction in necrosis. Further analysis revealed apolipoprotein C-III (APOC3) as a possible crucial factor of CDI-induced inflammation in vivo.
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Affiliation(s)
- Florian Stieglitz
- Institute of Toxicology, Hannover Medical School, Carl-Neuberg-Str. 1, 30625 Hannover, Germany; (F.S.); (R.G.)
- Core Facility Proteomics, Hannover Medical School, Carl-Neuberg-Str. 1, 30625 Hannover, Germany
| | - Ralf Gerhard
- Institute of Toxicology, Hannover Medical School, Carl-Neuberg-Str. 1, 30625 Hannover, Germany; (F.S.); (R.G.)
| | - Rabea Hönig
- Signal Transduction of Cellular Motility, Internal Medicine V, Justus Liebig University Giessen, Aulweg 128, 35392 Giessen, Germany; (R.H.); (K.G.)
| | - Klaudia Giehl
- Signal Transduction of Cellular Motility, Internal Medicine V, Justus Liebig University Giessen, Aulweg 128, 35392 Giessen, Germany; (R.H.); (K.G.)
| | - Andreas Pich
- Institute of Toxicology, Hannover Medical School, Carl-Neuberg-Str. 1, 30625 Hannover, Germany; (F.S.); (R.G.)
- Core Facility Proteomics, Hannover Medical School, Carl-Neuberg-Str. 1, 30625 Hannover, Germany
- Correspondence: ; Tel.: +49-511-532-2808; Fax: +49-511-532-2879
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Marquardt I, Jakob J, Scheibel J, Hofmann JD, Klawonn F, Neumann-Schaal M, Gerhard R, Bruder D, Jänsch L. Clostridioides difficile Toxin CDT Induces Cytotoxic Responses in Human Mucosal-Associated Invariant T (MAIT) Cells. Front Microbiol 2022; 12:752549. [PMID: 34992584 PMCID: PMC8727052 DOI: 10.3389/fmicb.2021.752549] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2021] [Accepted: 11/24/2021] [Indexed: 12/31/2022] Open
Abstract
Clostridioides difficile is the major cause of antibiotic-associated colitis (CDAC) with increasing prevalence in morbidity and mortality. Severity of CDAC has been attributed to hypervirulent C. difficile strains, which in addition to toxin A and B (TcdA, TcdB) produce the binary toxin C. difficile transferase (CDT). However, the link between these toxins and host immune responses as potential drivers of immunopathology are still incompletely understood. Here, we provide first experimental evidence that C. difficile toxins efficiently activate human mucosal-associated invariant T (MAIT) cells. Among the tested toxins, CDT and more specifically, the substrate binding and pore-forming subunit CDTb provoked significant MAIT cell activation resulting in selective MAIT cell degranulation of the lytic granule components perforin and granzyme B. CDT-induced MAIT cell responses required accessory immune cells, and we suggest monocytes as a potential CDT target cell population. Within the peripheral blood mononuclear cell fraction, we found increased IL-18 levels following CDT stimulation and MAIT cell response was indeed partly dependent on this cytokine. Surprisingly, CDT-induced MAIT cell activation was found to be partially MR1-dependent, although bacterial-derived metabolite antigens were absent. However, the role of antigen presentation in this process was not analyzed here and needs to be validated in future studies. Thus, MR1-dependent induction of MAIT cell cytotoxicity might be instrumental for hypervirulent C. difficile to overcome cellular barriers and may contribute to pathophysiology of CDAC.
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Affiliation(s)
- Isabel Marquardt
- Cellular Proteomics, Helmholtz Centre for Infection Research, Braunschweig, Germany.,Institute of Medical Microbiology and Hospital Hygiene, Infection Immunology, Health Campus Immunology, Infectiology and Inflammation, Otto-von-Guericke University Magdeburg, Magdeburg, Germany.,Immune Regulation, Helmholtz Centre for Infection Research, Braunschweig, Germany
| | - Josefine Jakob
- Cellular Proteomics, Helmholtz Centre for Infection Research, Braunschweig, Germany.,Institute of Medical Microbiology and Hospital Hygiene, Infection Immunology, Health Campus Immunology, Infectiology and Inflammation, Otto-von-Guericke University Magdeburg, Magdeburg, Germany.,Immune Regulation, Helmholtz Centre for Infection Research, Braunschweig, Germany
| | - Jessica Scheibel
- Cellular Proteomics, Helmholtz Centre for Infection Research, Braunschweig, Germany
| | - Julia Danielle Hofmann
- Braunschweig Integrated Centre of Systems Biology (BRICS), Department of Bioinformatics and Biochemistry, Technical University Braunschweig, Braunschweig, Germany
| | - Frank Klawonn
- Cellular Proteomics, Helmholtz Centre for Infection Research, Braunschweig, Germany
| | - Meina Neumann-Schaal
- Braunschweig Integrated Centre of Systems Biology (BRICS), Department of Bioinformatics and Biochemistry, Technical University Braunschweig, Braunschweig, Germany.,Metabolomics, Leibniz Institute DSMZ-German Collection of Microorganisms and Cell Cultures, Braunschweig, Germany
| | - Ralf Gerhard
- Institute of Toxicology, Hannover Medical School, Hannover, Germany
| | - Dunja Bruder
- Institute of Medical Microbiology and Hospital Hygiene, Infection Immunology, Health Campus Immunology, Infectiology and Inflammation, Otto-von-Guericke University Magdeburg, Magdeburg, Germany.,Immune Regulation, Helmholtz Centre for Infection Research, Braunschweig, Germany
| | - Lothar Jänsch
- Cellular Proteomics, Helmholtz Centre for Infection Research, Braunschweig, Germany
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11
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Aminzadeh A, Larsen CE, Boesen T, Jørgensen R. High-resolution structure of native toxin A from Clostridioides difficile. EMBO Rep 2022; 23:e53597. [PMID: 34817920 PMCID: PMC8728606 DOI: 10.15252/embr.202153597] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2021] [Revised: 11/09/2021] [Accepted: 11/10/2021] [Indexed: 01/07/2023] Open
Abstract
Clostridioides difficile infections have emerged as the leading cause of healthcare-associated infectious diarrhea. Disease symptoms are mainly caused by the virulence factors, TcdA and TcdB, which are large homologous multidomain proteins. Here, we report a 2.8 Å resolution cryo-EM structure of native TcdA, unveiling its conformation at neutral pH. The structure uncovers the dynamic movement of the CROPs domain which is induced in response to environmental acidification. Furthermore, the structure reveals detailed information about the interaction area between the CROPs domain and the tip of the delivery and receptor-binding domain, which likely serves to shield the C-terminal part of the hydrophobic pore-forming region from solvent exposure. Similarly, extensive interactions between the globular subdomain and the N-terminal part of the pore-forming region suggest that the globular subdomain shields the upper part of the pore-forming region from exposure to the surrounding solvent. Hence, the TcdA structure provides insights into the mechanism of preventing premature unfolding of the pore-forming region at neutral pH, as well as the pH-induced inter-domain dynamics.
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Affiliation(s)
- Aria Aminzadeh
- Department of Bacteria, Parasites and FungiStatens Serum InstitutCopenhagenDenmark
| | - Christian Engelbrecht Larsen
- Interdisciplinary Nanoscience Center (iNANO)Aarhus UniversityAarhusDenmark
- Department of Molecular Biology and GeneticsAarhus UniversityAarhusDenmark
| | - Thomas Boesen
- Interdisciplinary Nanoscience Center (iNANO)Aarhus UniversityAarhusDenmark
- Department of Molecular Biology and GeneticsAarhus UniversityAarhusDenmark
| | - René Jørgensen
- Department of Bacteria, Parasites and FungiStatens Serum InstitutCopenhagenDenmark
- Department of Science and EnvironmentUniversity of RoskildeRoskildeDenmark
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12
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Granata G, Mariotti D, Ascenzi P, Petrosillo N, di Masi A. High Serum Levels of Toxin A Correlate with Disease Severity in Patients with Clostridioides difficile Infection. Antibiotics (Basel) 2021; 10:1093. [PMID: 34572675 DOI: 10.3390/antibiotics10091093] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2021] [Revised: 08/30/2021] [Accepted: 09/07/2021] [Indexed: 12/13/2022] Open
Abstract
Cloistridioides difficile (CD) represents a major public healthcare-associated infection causing significant morbidity and mortality. The pathogenic effects of CD are mainly caused by the release of two exotoxins into the intestine: toxin A (TcdA) and toxin B (TcdB). CD infection (CDI) can also cause toxemia, explaining the systemic complications of life-threatening cases. Currently, there is a lack of sensitive assays to detect exotoxins circulating in the blood. Here, we report a new semi-quantitative diagnostic method to measure CD toxins serum levels. The dot-blot assay was modified to separately detect TcdA and TcdB in human serum with a limit of detection at the pg/mL levels. TcdA and TcdB concentrations in the plasma of 35 CDI patients were measured at the time of CDI diagnosis and at the fourth and tenth day after CDI diagnosis and initiation of anti-CDI treatment. TcdA and TcdB levels were compared to those determined in nine healthy blood donors. Toxemia was detected in the plasma of 33 out of the 35 CDI cases. We also assessed the relationship between TcdA serum levels and CDI severity, reporting that at the time of CDI diagnosis the proportion of severe CDI cases with a TcdA serum level > 60 pg/µL was higher than in mild CDI cases (29.4% versus 66.6%, p = 0.04). In conclusion, data reported here demonstrate for the first time that toxemia is much more frequent than expected in CDI patients, and specifically that high serum levels of TcdA correlate with disease severity in patients with CDI.
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13
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Aminzadeh A, Jørgensen R. Systematic Evaluation of Parameters Important for Production of Native Toxin A and Toxin B from Clostridioides difficile. Toxins (Basel) 2021; 13:240. [PMID: 33801738 DOI: 10.3390/toxins13040240] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2021] [Revised: 03/19/2021] [Accepted: 03/25/2021] [Indexed: 12/26/2022] Open
Abstract
In the attempt to improve the purification yield of native toxin A (TcdA) and toxin B (TcdB) from Clostridioides difficile (C. difficile), we systematically evaluated culture parameters for their influence on toxin production. In this study, we showed that culturing C. difficile in a tryptone-yeast extract medium buffered in PBS (pH 7.5) that contained 5 mM ZnCl2 and 10 mM glucose supported the highest TcdB production, measured by the sandwich ELISA. These culture conditions were scalable into 5 L and 15 L dialysis tube cultures, and we were able to reach a TcdB concentration of 29.5 µg/mL of culture. Furthermore, we established a purification protocol for TcdA and TcdB using FPLC column chromatography, reaching purities of >99% for both toxins with a yield around 25% relative to the starting material. Finally, by screening the melting temperatures of TcdA and TcdB in various buffer conditions using differential scanning fluorimetry, we found optimal conditions for improving the protein stability during storage. The results of this study present a complete protocol for obtaining high amounts of highly purified native TcdA and TcdB from C. difficile.
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14
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Shokoohizadeh L, Alvandi F, Yadegar A, Azimirad M, Hashemi SH, Alikhani MY. Frequency of toxin genes and antibiotic resistance pattern of Clostridioides difficile isolates in diarrheal samples among hospitalized patients in Hamadan, Iran. Gastroenterol Hepatol Bed Bench 2021; 14:165-173. [PMID: 33968344 PMCID: PMC8101526] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
AIM This study was designed to investigate the prevalence of Clostridioides difficile, its toxin-producing genes, and antibiotic resistance patterns in diarrheal samples from hospitalized patients in Hamadan, Iran. BACKGROUND Today, concerns over Clostridioides difficile infection (CDI) have significantly increased due to reduced susceptibility to antibiotics used for CDI treatment. Toxins produced by C. difficile strains are associated with disease severity and outcome. METHODS In this cross-sectional study, a total of 130 diarrheal samples of patients admitted to different wards of three hospitals in Hamadan from November 2018 to September 2019 were collected. C. difficile isolates were identified by culture on CCFA and PCR (Polymerase chain reaction). The presence of toxin-encoding genes (tcdA and tcdB) and binary toxin genes (cdtA and cdtB) was analyzed by PCR. Resistance of the isolates to metronidazole, vancomycin and clindamycin antibiotics was determined using agar dilution method. RESULTS Out of 130 diarrheal samples from hospitalized patients, 16 (12.3%) C. difficile isolates were obtained. PCR results were positive for two toxin-producing genes, tcdA and tcdB, in all (100%) C. difficile isolates, and the binary toxin genes cdtA and cdtB were detected in 6 (37.5%) and 8 (50%) isolates, respectively. The results of antibiotic susceptibility testing showed resistance to metronidazole, vancomycin, and clindamycin in 3 (18.7%), 3 (18.7%), and 2 (12.5%) isolates, respectively, and all isolates were resistant to rifampicin. CONCLUSION The results of this study showed toxigenic C. difficile with tcdA + /tcdB + profile is a major cause of nosocomial diarrhea in Hamadan, and clinical laboratories should routinely perform C. difficile diagnostic testing on diarrheal specimens of hospitalized patients. Resistance to conventional antibiotic therapy against C. difficile should be considered as a warning to prevent irrational administration of antibiotics.
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Affiliation(s)
- Leili Shokoohizadeh
- Department of Microbiology, Faculty of Medicine, Hamadan University of Medical Sciences, Hamadan, Iran
| | - Fatemeh Alvandi
- Department of Microbiology, Faculty of Medicine, Hamadan University of Medical Sciences, Hamadan, Iran
| | - Abbas Yadegar
- Foodborne and Waterborne Diseases Research Center, Research Institute for Gastroenterology and Liver Diseases, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Masoumeh Azimirad
- Foodborne and Waterborne Diseases Research Center, Research Institute for Gastroenterology and Liver Diseases, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Seyed Hamid Hashemi
- Department of Microbiology, Faculty of Medicine, Hamadan University of Medical Sciences, Hamadan, Iran,Brucellosis Research Center, Hamadan University of Medical Sciences, Hamadan, Iran
| | - Mohammad Yousef Alikhani
- Department of Microbiology, Faculty of Medicine, Hamadan University of Medical Sciences, Hamadan, Iran
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15
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Ahmed UKB, Shadid TM, Larabee JL, Ballard JD. Combined and Distinct Roles of Agr Proteins in Clostridioides difficile 630 Sporulation, Motility, and Toxin Production. mBio 2020; 11:e03190-20. [PMID: 33443122 DOI: 10.1128/mBio.03190-20] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The Clostridioides difficile accessory gene regulator 1 (agr1) locus consists of two genes, agrB1 and agrD1, that presumably constitute an autoinducing peptide (AIP) system. Typically, AIP systems function through the AgrB-mediated processing of AgrD to generate a processed form of the AIP that provides a concentration-dependent extracellular signal. Here, we show that the C. difficile 630 Agr1 system has multiple functions, not all of which depend on AgrB1. CRISPR-Cas9n deletion of agrB1, agrD1, or the entire locus resulted in changes in transcription of sporulation-related factors and an overall loss in spore formation. Sporulation was recovered in the mutants by providing supernatant from stationary-phase cultures of the parental strain. In contrast, C. difficile motility was reduced only when both AgrB1 and AgrD1 were disrupted. Finally, in the absence of AgrB1, the AgrD1 peptide accumulated within the cytoplasm and this correlated with increased expression of tcdR (15-fold), as well as tcdA (20-fold) and tcdB (5-fold), which encode the two major C. difficile toxins. The combined deletion of agrB1/agrD1 or deletion of only agrD1 did not significantly alter expression of tcdR or tcdB but did show a minor effect on tcdA expression. Overall, these data indicate that the Agr1-based system in C. difficile 630 carries out multiple functions, some of which are associated with prototypical AIP signaling and others of which involve previously undescribed mechanisms of action.IMPORTANCE C. difficile is a spore-forming, toxigenic, anaerobic bacterium that causes severe gastrointestinal illness. Understanding the ways in which C. difficile senses growth conditions to regulate toxin expression and sporulation is essential to advancing our understanding of this pathogen. The Agr1 system in C. difficile has been thought to function by generating an extracellular autoinducing peptide that accumulates and exogenously activates two-component signaling. The absence of the peptide or protease should, in theory, result in similar phenotypes. However, in contrast to longstanding assumptions about Agr, we found that mutants of individual agr1 genes exhibit distinct phenotypes in C. difficile These findings suggest that the Agr1 system may have other regulatory mechanisms independent of the typical Agr quorum sensing system. These data not only challenge models for Agr's mechanism of action in C. difficile but also may expand our conceptions of how this system works in other Gram-positive pathogens.
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16
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Liang J, Ning Y, Dong L, Ma X, Li S, Yang H, Li Q, Chen L, Gao L, Xu Y. The role of the globular heads of the C1q receptor in TcdA-induced human colonic epithelial cell apoptosis via a mitochondria-dependent pathway. BMC Microbiol 2020; 20:274. [PMID: 32878596 DOI: 10.1186/s12866-020-01958-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2020] [Accepted: 08/25/2020] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Clostridioides (formerly Clostridium) difficile infection is the leading cause of antibiotic-associated colitis. Studies have demonstrated that C. difficile toxin A (TcdA) can cause apoptosis of many human cell types. The purpose of this study was to investigate the relationships among exposure to TcdA, the role of the receptor for the globular heads of C1q (gC1qR) gene and the underlying intracellular apoptotic mechanism in human colonic epithelial cells (NCM 460). In this study, gC1qR expression was examined using real-time polymerase chain reaction (PCR), western blotting and immunohistochemical staining. Cell viability was assessed by the water-soluble tetrazolium salt (WST-1) assay, and cell apoptosis was assessed by flow cytometry and the terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick-end labeling (TUNEL) assay. Mitochondrial function was assessed based on reactive oxygen species (ROS) generation, changes in the mitochondrial membrane potential (ΔΨm) and the content of ATP. RESULTS Our study demonstrated that increasing the concentration of TcdA from 10 ng/ml to 20 ng/ml inhibited cell viability and induced cell apoptosis (p < 0.01). Moreover, the TcdA-induced gC1qR expression and enhanced expression of gC1qR caused mitochondrial dysfunction (including production of ROS and decreases in the ΔΨm and the content of ATP) and cell apoptosis. However, silencing of the gC1qR gene reversed TcdA-induced cell apoptosis and mitochondrial dysfunction. CONCLUSION These data support a mechanism by which gC1qR plays a crucial role in TcdA-induced apoptosis of human colonic epithelial cells in a mitochondria-dependent manner.
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17
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Li Z, Lee K, Rajyaguru U, Jones CH, Janezic S, Rupnik M, Anderson AS, Liberator P. Ribotype Classification of Clostridioides difficile Isolates Is Not Predictive of the Amino Acid Sequence Diversity of the Toxin Virulence Factors TcdA and TcdB. Front Microbiol 2020; 11:1310. [PMID: 32636819 PMCID: PMC7318873 DOI: 10.3389/fmicb.2020.01310] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2019] [Accepted: 05/25/2020] [Indexed: 12/18/2022] Open
Abstract
Clostridioides (Clostridium) difficile is the most commonly recognized cause of infectious diarrhea in healthcare settings. Currently there is no vaccine to prevent initial or recurrent C. difficile infection (CDI). Two large clostridial toxins, TcdA and TcdB, are the primary virulence factors for CDI. Immunological approaches to prevent CDI include antibody-mediated neutralization of the cytotoxicity of these toxins. An understanding of the sequence diversity of the two toxins expressed by disease causing isolates is critical for the interpretation of the immune response to the toxins. In this study, we determined the whole genome sequence (WGS) of 478 C. difficile isolates collected in 12 countries between 2004 and 2018 to probe toxin variant diversity. A total of 44 unique TcdA variants and 37 unique TcdB variants were identified. The amino acid sequence conservation among the TcdA variants (≥98%) is considerably greater than among the TcdB variants (as low as 86.1%), suggesting that different selection pressures may have contributed to the evolution of the two toxins. Phylogenomic analysis of the WGS data demonstrate that isolates grouped together based on ribotype or MLST code for multiple different toxin variants. These findings illustrate the importance of determining not only the ribotype but also the toxin sequence when evaluating strain coverage using vaccine strategies that target these virulence factors. We recommend that toxin variant type and sequence type (ST), be used together with ribotype data to provide a more comprehensive strain classification scheme for C. difficile surveillance during vaccine development objectives.
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Affiliation(s)
- Zhenghui Li
- Vaccine Research and Development, Pfizer Inc., Pearl River, NY, United States
| | - Kwok Lee
- Vaccine Research and Development, Pfizer Inc., Pearl River, NY, United States
| | - Urvi Rajyaguru
- Vaccine Research and Development, Pfizer Inc., Pearl River, NY, United States
| | - C Hal Jones
- Vaccine Research and Development, Pfizer Inc., Pearl River, NY, United States
| | - Sandra Janezic
- National Laboratory for Health, Environment and Food, Maribor, Slovenia.,Faculty of Medicine, University of Maribor, Maribor, Slovenia
| | - Maja Rupnik
- National Laboratory for Health, Environment and Food, Maribor, Slovenia.,Faculty of Medicine, University of Maribor, Maribor, Slovenia
| | | | - Paul Liberator
- Vaccine Research and Development, Pfizer Inc., Pearl River, NY, United States
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18
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Edwards AN, Krall EG, McBride SM. Strain-Dependent RstA Regulation of Clostridioides difficile Toxin Production and Sporulation. J Bacteriol 2020; 202:e00586-19. [PMID: 31659010 DOI: 10.1128/JB.00586-19] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2019] [Accepted: 10/21/2019] [Indexed: 02/04/2023] Open
Abstract
The anaerobic spore former Clostridioides difficile causes significant diarrheal disease in humans and other mammals. Infection begins with the ingestion of dormant spores, which subsequently germinate within the host gastrointestinal tract. There, the vegetative cells proliferate and secrete two exotoxins, TcdA and TcdB, which cause disease symptoms. Although spore formation and toxin production are critical for C. difficile pathogenesis, the regulatory links between these two physiological processes are not well understood and are strain dependent. Previously, we identified a conserved C. difficile regulator, RstA, that promotes sporulation initiation through an unknown mechanism and directly and indirectly represses toxin and motility gene transcription in the historical isolate 630Δerm To test whether perceived strain-dependent differences in toxin production and sporulation are mediated by RstA, we created an rstA mutant in the epidemic ribotype 027 strain R20291. RstA affected sporulation and toxin gene expression similarly but more robustly in R20291 than in 630Δerm In contrast, no effect on motility gene expression was observed in R20291. Reporter assays measuring transcriptional regulation of tcdR, the sigma factor gene essential for toxin gene expression, identified sequence-dependent effects influencing repression by RstA and CodY, a global nutritional sensor, in four diverse C. difficile strains. Finally, sequence- and strain-dependent differences were evident in RstA negative autoregulation of rstA transcription. Altogether, our data suggest that strain-dependent differences in RstA regulation contribute to the sporulation and toxin phenotypes observed in R20291. Our data establish RstA as an important regulator of C. difficile virulence traits.IMPORTANCE Two critical traits of Clostridioides difficile pathogenesis are toxin production, which causes disease symptoms, and spore formation, which permits survival outside the gastrointestinal tract. The multifunctional regulator RstA promotes sporulation and prevents toxin production in the historical strain 630Δerm Here, we show that RstA exhibits stronger effects on these phenotypes in an epidemic isolate, R20291, and additional strain-specific effects on toxin and rstA expression are evident. Our data demonstrate that sequence-specific differences within the promoter for the toxin regulator TcdR contribute to the regulation of toxin production by RstA and CodY. These sequence differences account for some of the variability in toxin production among isolates and may allow strains to differentially control toxin production in response to a variety of signals.
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19
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Edwards AN, Anjuwon-Foster BR, McBride SM. RstA Is a Major Regulator of Clostridioides difficile Toxin Production and Motility. mBio 2019; 10:e01991-18. [PMID: 30862746 PMCID: PMC6414698 DOI: 10.1128/mbio.01991-18] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2018] [Accepted: 01/25/2019] [Indexed: 01/05/2023] Open
Abstract
Clostridioides difficile infection (CDI) is a toxin-mediated diarrheal disease. Several factors have been identified that influence the production of the two major C. difficile toxins, TcdA and TcdB, but prior published evidence suggested that additional unknown factors were involved in toxin regulation. Previously, we identified a C. difficile regulator, RstA, that promotes sporulation and represses motility and toxin production. We observed that the predicted DNA-binding domain of RstA was required for RstA-dependent repression of toxin genes, motility genes, and rstA transcription. In this study, we further investigated the regulation of toxin and motility gene expression by RstA. DNA pulldown assays confirmed that RstA directly binds the rstA promoter via the predicted DNA-binding domain. Through mutational analysis of the rstA promoter, we identified several nucleotides that are important for RstA-dependent transcriptional regulation. Further, we observed that RstA directly binds and regulates the promoters of the toxin genes tcdA and tcdB, as well as the promoters for the sigD and tcdR genes, which encode regulators of toxin gene expression. Complementation analyses with the Clostridium perfringens RstA ortholog and a multispecies chimeric RstA protein revealed that the C. difficile C-terminal domain is required for RstA DNA-binding activity, suggesting that species-specific signaling controls RstA function. Our data demonstrate that RstA is a transcriptional repressor that autoregulates its own expression and directly inhibits transcription of the two toxin genes and two positive toxin regulators, thereby acting at multiple regulatory points to control toxin production.IMPORTANCEClostridioides difficile is an anaerobic, gastrointestinal pathogen of humans and other mammals. C. difficile produces two major toxins, TcdA and TcdB, which cause the symptoms of the disease, and forms dormant endospores to survive the aerobic environment outside the host. A recently discovered regulatory factor, RstA, inhibits toxin production and positively influences spore formation. Herein, we determine that RstA directly binds its own promoter DNA to repress its own gene transcription. In addition, our data demonstrate that RstA directly represses toxin gene expression and gene expression of two toxin gene activators, TcdR and SigD, creating a complex regulatory network to tightly control toxin production. This study provides a novel regulatory link between C. difficile sporulation and toxin production. Further, our data suggest that C. difficile toxin production is regulated through a direct, species-specific sensing mechanism.
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Affiliation(s)
- Adrianne N Edwards
- Department of Microbiology and Immunology, Emory Antibiotic Resistance Center, Emory University School of Medicine, Atlanta, Georgia, USA
| | - Brandon R Anjuwon-Foster
- Department of Microbiology and Immunology, University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, North Carolina, USA
| | - Shonna M McBride
- Department of Microbiology and Immunology, Emory Antibiotic Resistance Center, Emory University School of Medicine, Atlanta, Georgia, USA
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20
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Junemann J, Lämmerhirt CM, Polten F, Just I, Gerhard R, Genth H, Pich A. Quantification of small GTPase glucosylation by clostridial glucosylating toxins using multiplexed MRM analysis. Proteomics 2017; 17. [PMID: 28252257 DOI: 10.1002/pmic.201700016] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2017] [Revised: 02/10/2017] [Accepted: 02/28/2017] [Indexed: 12/29/2022]
Abstract
Large clostridial toxins mono-O-glucosylate small GTPases of the Rho and Ras subfamily. As a result of glucosylation, the GTPases are inhibited and thereby corresponding downstream signaling pathways are disturbed. Current methods for quantifying the extent of glucosylation include sequential [14 C]glucosylation, sequential [32 P]ADP-ribosylation, and Western Blot detection of nonglucosylated GTPases, with neither method allowing the quantification of the extent of glucosylation of an individual GTPase. Here, we describe a novel MS-based multiplexed MRM assay to specifically quantify the glucosylation degree of small GTPases. This targeted proteomics approach achieves a high selectivity and reproducibility, which allows determination of the in vivo substrate pattern of glucosylating toxins. As proof of principle, GTPase glucosylation was analyzed in CaCo-2 cells treated with TcdA, and glucosylation kinetics were determined for RhoA/B, RhoC, RhoG, Ral, Rap1, Rap2, (H/K/N)Ras, and R-Ras2.
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Affiliation(s)
- Johannes Junemann
- Hannover Medical School, Institute for Toxicology, Hannover, Germany
| | | | - Felix Polten
- Hannover Medical School, Institute for Toxicology, Hannover, Germany
| | - Ingo Just
- Hannover Medical School, Institute for Toxicology, Hannover, Germany
| | - Ralf Gerhard
- Hannover Medical School, Institute for Toxicology, Hannover, Germany
| | - Harald Genth
- Hannover Medical School, Institute for Toxicology, Hannover, Germany
| | - Andreas Pich
- Hannover Medical School, Institute for Toxicology, Hannover, Germany
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21
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Martz SL, Guzman-Rodriguez M, He SM, Noordhof C, Hurlbut DJ, Gloor GB, Carlucci C, Weese S, Allen-Vercoe E, Sun J, Claud EC, Petrof EO. A human gut ecosystem protects against C. difficile disease by targeting TcdA. J Gastroenterol 2017; 52:452-465. [PMID: 27329502 PMCID: PMC5177537 DOI: 10.1007/s00535-016-1232-y] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/22/2015] [Accepted: 06/06/2016] [Indexed: 02/07/2023]
Abstract
BACKGROUND A defined Microbial Ecosystem Therapeutic (MET-1, or "RePOOPulate") derived from the feces of a healthy volunteer can cure recurrent C. difficile infection (rCDI) in humans. The mechanisms of action whereby healthy microbiota protect against rCDI remain unclear. Since C. difficile toxins are largely responsible for the disease pathology of CDI, we hypothesized that MET-1 exerts its protective effects by inhibiting the effects of these toxins on the host. METHODS A combination of in vivo (antibiotic-associated mouse model of C. difficile colitis, mouse ileal loop model) and in vitro models (FITC-phalloidin staining, F actin Western blots and apoptosis assay in Caco2 cells, transepithelial electrical resistance measurements in T84 cells) were employed. RESULTS MET-1 decreased both local and systemic inflammation in infection and decreased both the cytotoxicity and the amount of TcdA detected in stool, without an effect on C. difficile viability. MET-1 protected against TcdA-mediated damage in a murine ileal loop model. MET-1 protected the integrity of the cytoskeleton in cells treated with purified TcdA, as indicated by FITC-phalloidin staining, F:G actin assays and preservation of transepithelial electrical resistance. Finally, co-incubation of MET-1 with purified TcdA resulted in decreased detectable TcdA by Western blot analysis. CONCLUSIONS MET-1 intestinal microbiota confers protection against C. difficile and decreases C. difficile-mediated inflammation through its protective effects against C. difficile toxins, including enhancement of host barrier function and degradation of TcdA. The effect of MET-1 on C. difficile viability seems to offer little, if any, contribution to its protective effects on the host.
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Affiliation(s)
- Sarah Lynn Martz
- Division of Infectious Diseases/GI Diseases Research Unit Wing, Department of Medicine, Kingston General Hospital, Queen's University, 76 Stuart Street, Kingston, ON, K7L 2V7, Canada
| | - Mabel Guzman-Rodriguez
- Division of Infectious Diseases/GI Diseases Research Unit Wing, Department of Medicine, Kingston General Hospital, Queen's University, 76 Stuart Street, Kingston, ON, K7L 2V7, Canada
| | - Shu-Mei He
- Division of Infectious Diseases/GI Diseases Research Unit Wing, Department of Medicine, Kingston General Hospital, Queen's University, 76 Stuart Street, Kingston, ON, K7L 2V7, Canada
| | - Curtis Noordhof
- Division of Infectious Diseases/GI Diseases Research Unit Wing, Department of Medicine, Kingston General Hospital, Queen's University, 76 Stuart Street, Kingston, ON, K7L 2V7, Canada
| | - David John Hurlbut
- Department of Pathology and Molecular Medicine, Queen's University, Kingston, ON, K7L 2V7, Canada
| | - Gregory Brian Gloor
- Department of Biochemistry, University of Western Ontario, London, ON, N6A 5C1, Canada
| | - Christian Carlucci
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, ON, N1G 2W1, Canada
| | - Scott Weese
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, ON, N1G 2W1, Canada
| | - Emma Allen-Vercoe
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, ON, N1G 2W1, Canada
| | - Jun Sun
- Division of Gastroenterology and Hepatology, Department of Medicine, University of Illinois at Chicago, Chicago, IL, 60612, USA
| | - Erika Chiong Claud
- Departments of Pediatrics and Medicine, University of Chicago, Chicago, IL, 60637, USA
| | - Elaine Olga Petrof
- Division of Infectious Diseases/GI Diseases Research Unit Wing, Department of Medicine, Kingston General Hospital, Queen's University, 76 Stuart Street, Kingston, ON, K7L 2V7, Canada.
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22
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Ruhe F, Olling A, Abromeit R, Rataj D, Grieschat M, Zeug A, Gerhard R, Alekov A. Overexpression of the Endosomal Anion/Proton Exchanger ClC-5 Increases Cell Susceptibility toward Clostridium difficile Toxins TcdA and TcdB. Front Cell Infect Microbiol 2017; 7:67. [PMID: 28348980 PMCID: PMC5346576 DOI: 10.3389/fcimb.2017.00067] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2016] [Accepted: 02/21/2017] [Indexed: 12/30/2022] Open
Abstract
Virulent C. difficile toxins TcdA and TcdB invade host intestinal epithelia by endocytosis and use the acidic environment of intracellular vesicles for further processing and activation. We investigated the role of ClC-5, a chloride/proton exchanger expressed in the endosomes of gastrointestinal epithelial cells, in the activation and processing of C. difficile toxins. Enhanced intoxication by TcdA and TcdB was observed in cells expressing ClC-5 but not ClC-4, another chloride/proton exchanger with similar function but different localization. In accordance with the established physiological function of ClC-5, its expression lowered the endosomal pH in HEK293T cells by approximately 0.6 units and enhanced approximately 5-fold the internalization of TcdA. In colon HT29 cells, 34% of internalized TcdA localized to ClC-5-containing vesicles defined by colocalization with Rab5, Rab4a, and Rab7 as early and early-to-late of endosomes but not as Rab11-containing recycling endosomes. Impairing the cellular uptake of TcdA by deleting the toxin CROPs domain did not abolish the effects of ClC-5. In addition, the transport-incompetent mutant ClC-5 E268Q similarly enhanced both endosomal acidification and intoxication by TcdA but facilitated the internalization of the toxin to a lower extent. These data suggest that ClC-5 enhances the cytotoxic action of C. difficile toxins by accelerating the acidification and maturation of vesicles of the early and early-to-late endosomal system. The dispensable role of electrogenic ion transport suggests that the voltage-dependent nonlinear capacitances of mammalian CLC transporters serve important physiological functions. Our data shed light on the intersection between the endocytotic cascade of host epithelial cells and the internalization pathway of the large virulence C. difficile toxins. Identifying ClC-5 as a potential specific host ion transporter hijacked by toxins produced by pathogenic bacteria widens the horizon of possibilities for novel therapies of life-threatening gastrointestinal infections.
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Affiliation(s)
- Frederike Ruhe
- Institute for Neurophysiology, Hannover Medical SchoolHannover, Germany
| | - Alexandra Olling
- Institute for Toxicology, Hannover Medical SchoolHannover, Germany
| | - Rasmus Abromeit
- Institute for Neurophysiology, Hannover Medical SchoolHannover, Germany
| | - Dennis Rataj
- Institute for Toxicology, Hannover Medical SchoolHannover, Germany
| | | | - Andre Zeug
- Institute for Neurophysiology, Hannover Medical SchoolHannover, Germany
| | - Ralf Gerhard
- Institute for Toxicology, Hannover Medical SchoolHannover, Germany
| | - Alexi Alekov
- Institute for Neurophysiology, Hannover Medical SchoolHannover, Germany
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23
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Hernandez LD, Kroh HK, Hsieh E, Yang X, Beaumont M, Sheth PR, DiNunzio E, Rutherford SA, Ohi MD, Ermakov G, Xiao L, Secore S, Karczewski J, Racine F, Mayhood T, Fischer P, Sher X, Gupta P, Lacy DB, Therien AG. Epitopes and Mechanism of Action of the Clostridium difficile Toxin A-Neutralizing Antibody Actoxumab. J Mol Biol 2017; 429:1030-44. [PMID: 28232034 DOI: 10.1016/j.jmb.2017.02.010] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2016] [Revised: 02/14/2017] [Accepted: 02/14/2017] [Indexed: 12/17/2022]
Abstract
The exotoxins toxin A (TcdA) and toxin B (TcdB) are produced by the bacterial pathogen Clostridium difficile and are responsible for the pathology associated with C. difficile infection (CDI). The antitoxin antibodies actoxumab and bezlotoxumab bind to and neutralize TcdA and TcdB, respectively. Bezlotoxumab was recently approved by the FDA for reducing the recurrence of CDI. We have previously shown that a single molecule of bezlotoxumab binds to two distinct epitopes within the TcdB combined repetitive oligopeptide (CROP) domain, preventing toxin binding to host cells. In this study, we characterize the binding of actoxumab to TcdA and examine its mechanism of toxin neutralization. Using a combination of approaches including a number of biophysical techniques, we show that there are two distinct actoxumab binding sites within the CROP domain of TcdA centered on identical amino acid sequences at residues 2162-2189 and 2410-2437. Actoxumab binding caused the aggregation of TcdA especially at higher antibody:toxin concentration ratios. Actoxumab prevented the association of TcdA with target cells demonstrating that actoxumab neutralizes toxin activity by inhibiting the first step of the intoxication cascade. This mechanism of neutralization is similar to that observed with bezlotoxumab and TcdB. Comparisons of the putative TcdA epitope sequences across several C. difficile ribotypes and homologous repeat sequences within TcdA suggest a structural basis for observed differences in actoxumab binding and/or neutralization potency. These data provide a mechanistic basis for the protective effects of the antibody in vitro and in vivo, including in various preclinical models of CDI.
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24
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Loughney JW, Lancaster C, Price CE, Hoang VM, Ha S, Rustandi RR. Development of a non-radiolabeled glucosyltransferase activity assay for C. difficile toxin A and B using ultra performance liquid chromatography. J Chromatogr A 2017; 1498:169-175. [PMID: 28238427 DOI: 10.1016/j.chroma.2017.01.083] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2016] [Revised: 01/26/2017] [Accepted: 01/29/2017] [Indexed: 01/28/2023]
Abstract
Clostridium difficile infection (CDI) is the leading cause of gastroenteritis-associated death in the United States. The major virulent factors of C. difficile are toxin A (TcdA) and toxin B (TcdB). Toxicity is mediated by the glucosyltransferase domains on TcdA and TcdB wherein a glucose is transferred from UDP-glucose to Ras homolog family member A (RhoA) receptor. This modification results in disruption of critical cell signaling events. Vaccination against these toxins is considered the best way to combat the CDI. In order to produce non-toxic TcdA and TcdB antigens, their glucosyltransferase domains were genetically mutated to inactivate the toxin activity. We have developed a reverse phase ultra performance liquid chromatographic (RP-UPLC) method to measure this glucosyltransferase activity by separating RhoA and glucosylated RhoA. Glucosylated RhoA and RhoA have a retention time (RT) of 31.25 and 31.95min. We determine for the first time the glucosyltransferase kinetics (Km and kcat) of both full length TcdA and TcdB to RhoA and demonstrate that the genetically mutated TcdA and TcdB show no glucosyltransferase activity. Furthermore, two-dimensional electron microscopy (2D EM) data demonstrates that the overall global structures of mutated toxins do not change compared to native toxins.
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Affiliation(s)
- John W Loughney
- Biologics and Vaccines, Merck & Co., Inc., Kenilworth, NJ, USA.
| | | | - Colleen E Price
- Biologics and Vaccines, Merck & Co., Inc., Kenilworth, NJ, USA
| | - Van M Hoang
- Biologics and Vaccines, Merck & Co., Inc., Kenilworth, NJ, USA
| | - Sha Ha
- Biologics and Vaccines, Merck & Co., Inc., Kenilworth, NJ, USA
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25
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Lambert GS, Baldwin MR. Evidence for dual receptor-binding sites in Clostridium difficile toxin A. FEBS Lett 2016; 590:4550-4563. [PMID: 27861794 DOI: 10.1002/1873-3468.12487] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2016] [Revised: 10/10/2016] [Accepted: 10/24/2016] [Indexed: 12/24/2022]
Abstract
TcdA (308 kDa) and TcdB (270 kDa) disrupt the integrity of the intestinal epithelial barrier and provide an environment favorable for Clostridium difficile colonization. Recent evidence suggests that entry of TcdA into cells is mediated by at least two domains. Here, we report the characterization of a second receptor-binding domain (RBD2) for TcdA. While both the isolated combined repetitive oligopeptides (CROPs) and RBD2 fragments are rapidly internalized into cells under physiologic conditions, only the CROPs domain appreciably accumulates at the cell surface. Once internalized, CROPs and RBD2 are trafficked to late endosomal compartments. An internal deletion of RBD2 from TcdA holotoxin ablated toxicity in HT29 cells. These data are consistent with the recently proposed dual receptor model of cellular entry.
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Affiliation(s)
- Gregory S Lambert
- Department of Molecular Microbiology and Immunology, University of Missouri School of Medicine, Columbia, MO, USA
| | - Michael R Baldwin
- Department of Molecular Microbiology and Immunology, University of Missouri School of Medicine, Columbia, MO, USA
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26
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Chen S, Gu H, Sun C, Wang H, Wang J. Rapid detection of Clostridium difficile toxins and laboratory diagnosis of Clostridium difficile infections. Infection 2016; 45:255-262. [PMID: 27601055 DOI: 10.1007/s15010-016-0940-9] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2016] [Accepted: 08/11/2016] [Indexed: 02/08/2023]
Abstract
BACKGROUND Clostridium difficile is an anaerobic, spore-forming and Gram-positive bacillus. It is the major cause of antibiotic-associated diarrhea prevailing in hospital settings. The morbidity and mortality of C. difficile infection (CDI) has increased significantly due to the emergence of hypervirulent strains. Because of the poor clinical different between CDI and other causes of hospital-acquired diarrhea, laboratory test for C. difficile is an important intervention for diagnosis of CDI. OBJECTIVE Laboratory tests for CDI can broadly detect either the organisms or its toxins. Currently, several laboratory tests are used for diagnosis of CDI, including toxigenic culture, glutamate dehydrogenase detection, nucleic acid amplification testing, cell cytotoxicity assay, and enzyme immunoassay towards toxin A and/or B. This review focuses on the rapid testing of C. difficile toxins and currently available methods for diagnosis of CDI, giving an overview of the role that the toxins rapid detecting plays in clinical diagnosis of CDI.
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Affiliation(s)
- Shuyi Chen
- School of Bioscience and Bioengineering, South China University of Technology, Guangzhou, China
| | - Huawei Gu
- School of Bioscience and Bioengineering, South China University of Technology, Guangzhou, China
| | - Chunli Sun
- School of Bioscience and Bioengineering, South China University of Technology, Guangzhou, China
| | - Haiying Wang
- School of Bioscience and Bioengineering, South China University of Technology, Guangzhou, China
| | - Jufang Wang
- School of Bioscience and Bioengineering, South China University of Technology, Guangzhou, China.
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27
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Benedek O, Podbielski A, Warnke P. Laboratory Experience with the Liaison Analyzer in the Diagnosis of Clostridium Difficile-Associated Diarrhea. Eur J Microbiol Immunol (Bp) 2016; 6:215-218. [PMID: 27766170 PMCID: PMC5063014 DOI: 10.1556/1886.2016.00017] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2016] [Accepted: 05/30/2016] [Indexed: 12/18/2022] Open
Abstract
Background Chemiluminescent or enzyme-linked fluorescent immunoassays are commonly used to diagnose Clostridium difficile-associated diarrhea. Methods The LIAISON analyzer (DiaSorin, Italy) was compared to miniVIDAS (bioMérieux, France) and, furthermore, to culture of toxigenic strains. In total, 249 native stool samples were analyzed. Sensitivities, specificities, and positive and negative predictive values were investigated. Furthermore, performance under routine conditions was assessed. Results The glutamate dehydrogenase chemiluminescent immunoassay (GDH-CLIA) assay revealed a high sensitivity and negative predictive value. The toxins A&B assays exhibited approximately the same low sensitivity and high specificity. Technical drawbacks experienced with the LIAISON analyzer in 48% of the analyses considerably delayed the time to the first diagnostic report and interfered with laboratory routine workflow. Conclusion The analytical performance of the investigated platforms should be reflected in the context of implementation into the laboratory workflow.
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Affiliation(s)
- Orsolya Benedek
- Institute of Medical Microbiology, Virology and Hygiene, University Hospital Rostock , Rostock, Germany
| | - Andreas Podbielski
- Institute of Medical Microbiology, Virology and Hygiene, University Hospital Rostock , Rostock, Germany
| | - Philipp Warnke
- Institute of Medical Microbiology, Virology and Hygiene, University Hospital Rostock , Rostock, Germany
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28
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Abstract
High-performance size-exclusion chromatography (HPSEC or SEC) is a method that can be applied to measure size distribution of proteins, including aggregates, monomers, and fragments. In the biopharmaceutical industry the quantitation of aggregates contained in biotherapeutics and protein-based vaccines is critical given the potential impact on safety, immunogenicity, and efficacy. Hence, aggregation analysis of therapeutic proteins or protein-based vaccine products is almost always a requirement of regulatory agencies. SEC, also referred to as gel-filtration chromatography, separates molecules by size through a porous resin stationary phase. Under isocratic flow small molecules are retained on the column longer than large molecules. Here we describe the use of this SEC technique to characterize aggregation levels for four different protein antigens for a Clostridium difficile vaccine.
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Affiliation(s)
- Catherine Lancaster
- Vaccine Analytical Department, Merck Research Laboratories, Merck & Co., Inc., 770 Sumneytown Pike, P.O. Box 4, WP42A-30, West point, PA, 19486, USA.
| | - Richard R Rustandi
- Vaccine Analytical Department, Merck Research Laboratories, Merck & Co., Inc., 770 Sumneytown Pike, P.O. Box 4, WP42A-30, West point, PA, 19486, USA
| | - Paola Pannizzo
- Merck & Co., Inc., West point, PA, USA
- Johnson & Johnson, Spring House, PA, USA
| | - Sha Ha
- Vaccine Analytical Department, Merck Research Laboratories, Merck & Co., Inc., 770 Sumneytown Pike, P.O. Box 4, WP42A-30, West point, PA, 19486, USA
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29
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Kim S, Lee H, Park S. The Structure of Escherichia coli TcdA (Also Known As CsdL) Reveals a Novel Topology and Provides Insight into the tRNA Binding Surface Required for N(6)-Threonylcarbamoyladenosine Dehydratase Activity. J Mol Biol 2015; 427:3074-85. [PMID: 26101842 DOI: 10.1016/j.jmb.2015.06.005] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2015] [Revised: 06/01/2015] [Accepted: 06/15/2015] [Indexed: 11/22/2022]
Abstract
Escherichia coli TcdA (also known as CsdL) was previously shown to catalyze the ATP-dependent dehydration/cyclization of hypermodified tRNA N(6)-threonylcarbamoyladenosine into further cyclic N(6)-threonylcarbamoyladenosine. In this study, we report the X-ray crystal structures of E. coli TcdA with either AMP or ATP bound. The AMP/ATP-bound N-terminal sub-domain of TcdA resembles the ATP-binding Rossmann fold of E. coli ThiF and MoeB that are enzymes respectively taking part in the biosynthesis of thiamine and molybdopterin; however, the remaining C-terminal sub-domain of TcdA adopts a structure unrelated to any other known folds. In TcdA, the ATP-utilizing adenylation of tRNA N(6)-threonylcarbamoyladenosine and a subsequent thioester formation via an active cysteine, similar to the mechanisms in ThiF and MoeB, could take place for the dehydratase function. Analysis of the structure with sequence alignment suggests the disordered Cys234 of TcdA as the most likely catalytic residue. The structure further indicates that the C-terminal sub-domain can provide a binding interface for the tRNA substrate. Binding study using the surface mutants of TcdA and tRNA reveals that the positively charged regions of mainly the C-terminal sub-domain are important for the tRNA recognition.
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30
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Kim S, Kim KY, Park JK, Lee BI, Kim YG, Park S. Overproduction, crystallization and preliminary X-ray crystallographic analysis of Escherichia coli tRNA N6-threonylcarbamoyladenosine dehydratase. Acta Crystallogr F Struct Biol Commun 2014; 70:1517-20. [PMID: 25372820 DOI: 10.1107/s2053230x14020883] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/10/2014] [Accepted: 09/17/2014] [Indexed: 11/10/2022]
Abstract
Escherichia coli tRNA N6-threonylcarbamoyladenosine dehydratase (TcdA), previously called CsdL or YgdL, was overproduced and purified from E. coli and crystallized using polyethylene glycol 3350 as a crystallizing agent. X-ray diffraction data were collected to 2.70 Å resolution under cryoconditions using synchrotron X-rays. The crystals belonged to space group P2₁, with unit-cell parameters a=65.4, b=96.8, c=83.3 Å, β=111.7°. According to the Matthews coefficient, the asymmetric unit may contain up to four subunits of the monomeric protein, with a crystal volume per protein mass (VM) of 2.12 Å3 Da(-1) and 42.1% solvent content.
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Affiliation(s)
- Sunmin Kim
- School of Systems Biomedical Science, Soongsil University, Seoul 156-743, Republic of Korea
| | - Keon Young Kim
- School of Systems Biomedical Science, Soongsil University, Seoul 156-743, Republic of Korea
| | - Jeong Kuk Park
- School of Systems Biomedical Science, Soongsil University, Seoul 156-743, Republic of Korea
| | - Byung Il Lee
- Biomolecular Function Research Branch, Division of Convergence Technology, Research Institute, National Cancer Center, Goyang, Gyeonggi 410-769, Republic of Korea
| | - Yun-Gon Kim
- Department of Chemical Engineering, Soongsil University, Seoul 156-743, Republic of Korea
| | - SangYoun Park
- School of Systems Biomedical Science, Soongsil University, Seoul 156-743, Republic of Korea
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31
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Kuehne SA, Collery MM, Kelly ML, Cartman ST, Cockayne A, Minton NP. Importance of toxin A, toxin B, and CDT in virulence of an epidemic Clostridium difficile strain. J Infect Dis 2014; 209:83-6. [PMID: 23935202 PMCID: PMC3864386 DOI: 10.1093/infdis/jit426] [Citation(s) in RCA: 164] [Impact Index Per Article: 16.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2013] [Accepted: 07/12/2013] [Indexed: 12/17/2022] Open
Abstract
Clostridium difficile infection is the main cause of healthcare-acquired diarrhea in the developed world. In addition to the main virulence factors toxin A and B, epidemic, PCR Ribotype 027 strains, such as R20291, produce a third toxin, CDT. To develop effective medical countermeasures, it is important to understand the importance of each toxin. Accordingly, we created all possible combinations of isogenic toxin mutants of R20291 and assessed their virulence. We demonstrated that either toxin A or toxin B alone can cause fulminant disease in the hamster infection model and present tantalizing data that C. difficile toxin may also contribute to virulence.
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Affiliation(s)
- Sarah A Kuehne
- Clostridia Research Group, Nottingham Digestive Diseases Centre, NIHR Biomedical Research Unit, School of Life Sciences, University of Nottingham, United Kingdom
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32
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Abstract
We recently published our findings indicating that anti-TcdB antibodies were effective as treatment for C. difficile infection, but that anti-TcdA actually worsened prognosis in the gnotobiotic piglet model. To further investigate the roles of the two toxins, we administered purified toxins separately or together, systemically, to piglets and found that both toxins, either alone or together, are able to elicit severe lesions systemically and are also able to cross into the gut lumen and cause large intestinal lesions typical of infection. We also found that anti-TcdA administered before systemic challenge with TcdA again did not protect from development of disease, but, in this case, did not appear to worsen prognosis. Further work is still needed, but these findings add to the growing knowledge regarding the roles of the C. difficile toxins.
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Affiliation(s)
- Jennifer Steele
- Tufts Cummings School of Veterinary Medicine; Department of Infectious Disease and Global Health; North Grafton, MA USA
| | - Nicola Parry
- Massachussetts Institute of Technology; Division of Comparative Medicine; Cambridge, MA USA
| | - Saul Tzipori
- Tufts Cummings School of Veterinary Medicine; Department of Infectious Disease and Global Health; North Grafton, MA USA,Correspondence to: Saul Tzipori,
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