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Papatheodorou P, Minton NP, Aktories K, Barth H. An Updated View on the Cellular Uptake and Mode-of-Action of Clostridioides difficile Toxins. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2024; 1435:219-247. [PMID: 38175478 DOI: 10.1007/978-3-031-42108-2_11] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2024]
Abstract
Research on the human gut pathogen Clostridioides (C.) difficile and its toxins continues to attract much attention as a consequence of the threat to human health posed by hypervirulent strains. Toxin A (TcdA) and Toxin B (TcdB) are the two major virulence determinants of C. difficile. Both are single-chain proteins with a similar multidomain architecture. Certain hypervirulent C. difficile strains also produce a third toxin, namely binary toxin CDT (C. difficile transferase). C. difficile toxins are the causative agents of C. difficile-associated diseases (CDADs), such as antibiotics-associated diarrhea and pseudomembranous colitis. For that reason, considerable efforts have been expended to unravel their molecular mode-of-action and the cellular mechanisms responsible for their uptake. Many of these studies have been conducted in European laboratories. Here, we provide an update on our previous review (Papatheodorou et al. Adv Exp Med Biol, 2018) on important advances in C. difficile toxins research.
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Affiliation(s)
- Panagiotis Papatheodorou
- Institute of Experimental and Clinical Pharmacology, Toxicology and Pharmacology of Natural Products, Ulm University Medical Center, Ulm, Germany.
| | - Nigel P Minton
- BBSRC/EPSRC Synthetic Biology Research Centre, University of Nottingham, Nottingham, UK
| | - Klaus Aktories
- Institute of Experimental and Clinical Pharmacology and Toxicology, University of Freiburg, Freiburg, Germany
| | - Holger Barth
- Institute of Experimental and Clinical Pharmacology, Toxicology and Pharmacology of Natural Products, Ulm University Medical Center, Ulm, Germany
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Azimirad M, Noori M, Amirkamali S, Nasiri G, Asadzadeh Aghdaei H, Yadegar A, Klionsky DJ, Zali MR. Clostridioides difficile PCR ribotypes 001 and 084 can trigger autophagy process in human intestinal Caco-2 cells. Microb Pathog 2023; 185:106450. [PMID: 37979713 DOI: 10.1016/j.micpath.2023.106450] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2023] [Revised: 10/25/2023] [Accepted: 11/10/2023] [Indexed: 11/20/2023]
Abstract
Autophagy is a homeostatic process that can promote cell survival or death. However, the exact role of autophagy in Clostridioides difficile infection (CDI) is still not precisely elucidated. Here, we investigate the role of distinct C. difficile ribotypes (RTs) in autophagy induction using Caco-2 cells. The expression analysis of autophagy-associated genes and related miRNAs were examined following treatment of Caco-2 cells with C. difficile after 4 and 8 h using RT-qPCR. Toxin production was assessed using enzyme-linked immunosorbent assay (ELISA). Immunofluorescence analysis was performed to detect MAP1LC3B/LC3B, followed by an autophagic flux analysis. C. difficile significantly reduced the viability of Caco-2 cells in comparison with untreated cells. Elevated levels of LC3-II and SQSTM1/p62 by C. difficile RT001 and RT084 in the presence of E64d/leupeptin confirmed the induction of autophagy activity. Similarly, the immunofluorescence analysis demonstrated that C. difficile RT001 and RT084 significantly increased the amount of LC3-positive structures in Caco-2 cells. The induction of autophagy was further demonstrated by increased levels of LC3B, ULK1, ATG12, PIK3C3/VPS34, BECN1 (beclin 1), ATG5, and ATG16L1 transcripts and reduced levels of AKT and MTOR gene expression. The expression levels of MIR21 and MIR30B, microRNAs that suppress autophagy, were differentially affected by C. difficile. In conclusion, the present work revealed that C. difficile bacteria can induce autophagy through both toxin-dependent and -independent mechanisms. Also, our results suggest the potential role of other C. difficile virulence factors in autophagy modulation using intestinal cells in vitro.
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Affiliation(s)
- Masoumeh Azimirad
- Foodborne and Waterborne Diseases Research Center, Research Institute for Gastroenterology and Liver Diseases, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Maryam Noori
- Foodborne and Waterborne Diseases Research Center, Research Institute for Gastroenterology and Liver Diseases, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Sahar Amirkamali
- Foodborne and Waterborne Diseases Research Center, Research Institute for Gastroenterology and Liver Diseases, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Gelareh Nasiri
- 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
| | - Abbas Yadegar
- Foodborne and Waterborne Diseases Research Center, Research Institute for Gastroenterology and Liver Diseases, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
| | - Daniel J Klionsky
- Life Sciences Institute, University of Michigan, Ann Arbor, MI, 48109, USA; Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, MI, 48109, USA.
| | - 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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3
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Fettucciari K, Dini F, Marconi P, Bassotti G. Role of the Alteration in Calcium Homeostasis in Cell Death Induced by Clostridioides difficile Toxin A and Toxin B. BIOLOGY 2023; 12:1117. [PMID: 37627001 PMCID: PMC10452684 DOI: 10.3390/biology12081117] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/11/2023] [Revised: 08/05/2023] [Accepted: 08/08/2023] [Indexed: 08/27/2023]
Abstract
Clostridioides difficile (C. difficile), responsible for 15-25% of gastrointestinal infections, causes health problems mainly due to the toxic activity of toxins A and B (Tcds). These are responsible for its clinical manifestations, including diarrhea, pseudomembranous colitis, toxic megacolon and death, with a mortality of 5-30% in primary infection, that increase following relapses. Studies on Tcd-induced cell death have highlighted a key role of caspases, calpains, and cathepsins, with involvement of mitochondria and reactive oxygen species (ROS) in a complex signaling pathway network. The complex response in the execution of various types of cell death (apoptosis, necrosis, pyroptosis and pyknosis) depends on the amount of Tcd, cell types, and Tcd receptors involved, and could have as initial/precocious event the alterations in calcium homeostasis. The entities, peculiarities and cell types involved in these alterations will decide the signaling pathways activated and cell death type. Calcium homeostasis alterations can be caused by calcium influx through calcium channel activation, transient intracellular calcium oscillations, and leakage of calcium from intracellular stores. These increases in cytoplasmic calcium have important effects on all calcium-regulated molecules, which may play a direct role in several cell death types and/or activate other cell death effectors, such as caspases, calpains, ROS and proapoptotic Bcl-2 family members. Furthermore, some support for the possible role of the calcium homeostasis alteration in Tcd-induced cell death originates from the similarity with cytotoxic effects that cause pore-forming toxins, based mainly on calcium influx through plasma membrane pores.
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Affiliation(s)
- Katia Fettucciari
- Biosciences & Medical Embryology Section, Department of Medicine and Surgery, University of Perugia, 06129 Perugia, Italy;
| | - Fabrizio Dini
- School of Biosciences and Veterinary Medicine, University of Camerino, 62024 Matelica, Italy;
| | - Pierfrancesco Marconi
- Biosciences & Medical Embryology Section, Department of Medicine and Surgery, University of Perugia, 06129 Perugia, Italy;
| | - Gabrio Bassotti
- Gastroenterology, Hepatology & Digestive Endoscopy Section, Department of Medicine and Surgery, University of Perugia, 06129 Perugia, Italy;
- Gastroenterology & Hepatology Unit, Santa Maria Della Misericordia Hospital, 06129 Perugia, Italy
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Bhadra K. A Mini Review on Molecules Inducing Caspase-Independent Cell Death: A New Route to Cancer Therapy. Molecules 2022; 27:molecules27196401. [PMID: 36234938 PMCID: PMC9572491 DOI: 10.3390/molecules27196401] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2022] [Revised: 09/17/2022] [Accepted: 09/21/2022] [Indexed: 11/16/2022] Open
Abstract
Most anticancer treatments trigger tumor cell death through apoptosis, where initiation of proteolytic action of caspase protein is a basic need. But under certain circumstances, apoptosis is prevented by the apoptosis inhibitor proteins, survivin and Hsp70. Several drugs focusing on classical programmed death of the cell have been reported to have low anti-tumorogenic potency due to mutations in proteins involved in the caspase-dependent programmed cell death with intrinsic and extrinsic pathways. This review concentrates on the role of anti-cancer drug molecules targeting alternative pathways of cancer cell death for treatment, by providing a molecular basis for the new strategies of novel anti-cancer treatment. Under these conditions, active agents targeting alternative cell death pathways can be considered as potent chemotherapeutic drugs. Many natural compounds and other small molecules, such as inorganic and synthetic compounds, including several repurposing drugs, are reported to cause caspase-independent cell death in the system. However, few molecules indicated both caspase-dependent as well caspase-free cell death in specific cancer lines. Cancer cells have alternative methods of caspase-independent programmed cell death which are equally promising for being targeted by small molecules. These small molecules may be useful leads for rational therapeutic drug design, and can be of potential interest for future cancer-preventive strategies.
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Affiliation(s)
- Kakali Bhadra
- Department of Zoology, University of Kalyani, Nadia, Kalyani 741235, India
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Loureiro AV, Moura-Neto LI, Martins CS, Silva PIM, Lopes MB, Leitão RFC, Coelho-Aguiar JM, Moura-Neto V, Warren CA, Costa DV, Brito GAC. Role of Pannexin-1-P2X7R signaling on cell death and pro-inflammatory mediator expression induced by Clostridioides difficile toxins in enteric glia. Front Immunol 2022; 13:956340. [PMID: 36072579 PMCID: PMC9442043 DOI: 10.3389/fimmu.2022.956340] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2022] [Accepted: 08/01/2022] [Indexed: 11/13/2022] Open
Abstract
Clostridioides difficile (C. difficile) produces toxins A (TcdA) and B (TcdB), both associated with intestinal damage and diarrhea. Pannexin-1 (Panx1) channels allows the passage of messenger molecules, such as adenosine triphosphate (ATP), which in turn activate the P2X7 receptors (P2X7R) that regulate inflammation and cell death in inflammatory bowel diseases. The aim of this study was to verify the effect of C. difficile infection (CDI) in the expression of Panx1 and P2X7R in intestinal tissues of mice, as well as their role in cell death and IL-6 expression induced by TcdA and TcdB in enteric glial cells (EGCs). Male C57BL/6 mice (8 weeks of age) were infected with C. difficile VPI10463, and the control group received only vehicle per gavage. After three days post-infection (p.i.), cecum and colon samples were collected to evaluate the expression of Panx1 by immunohistochemistry. In vitro, EGCs (PK060399egfr) were challenged with TcdA or TcdB, in the presence or absence of the Panx1 inhibitor (10Panx trifluoroacetate) or P2X7R antagonist (A438079), and Panx1 and P2X7R expression, caspase-3/7 activity and phosphatidylserine binding to annexin-V, as well as IL-6 expression were assessed. CDI increased the levels of Panx1 in cecum and colon of mice compared to the control group. Panx1 inhibitor decreased caspase-3/7 activity and phosphatidylserine-annexin-V binding, but not IL-6 gene expression in TcdA and TcdB-challenged EGCs. P2X7 receptor antagonist accentually reduced caspase-3/7 activity, phosphatidylserine-annexin-V binding, and IL-6 gene expression in TcdA and TcdB-challenged EGCs. In conclusion, Panx1 is increased during CDI and plays an important role in the effects of C. difficile toxins in EGCs, participating in cell death induced by both toxins by promoting caspase-3/7 activation via P2X7R, which is also involved in IL-6 expression induced by both toxins.
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Affiliation(s)
- Andrea V. Loureiro
- Department of Morphology, School of Medicine, Federal University of Ceará, Fortaleza, Ceará, Brazil
| | - Lauro I. Moura-Neto
- Department of Morphology, School of Medicine, Federal University of Ceará, Fortaleza, Ceará, Brazil
| | - Conceição S. Martins
- Department of Morphology, School of Medicine, Federal University of Ceará, Fortaleza, Ceará, Brazil
| | - Pedro I. M. Silva
- Department of Morphology, School of Medicine, Federal University of Ceará, Fortaleza, Ceará, Brazil
| | - Matheus B.S. Lopes
- Department of Morphology, School of Medicine, Federal University of Ceará, Fortaleza, Ceará, Brazil
| | - Renata F. C. Leitão
- Department of Morphology, School of Medicine, Federal University of Ceará, Fortaleza, Ceará, Brazil
| | - Juliana M. Coelho-Aguiar
- Paulo Niemeyer Brain Institute, Federal University of Rio de Janeiro, UFRJ, Rio de Janeiro, Rio de Janeiro, Brazil
| | - Vivaldo Moura-Neto
- Paulo Niemeyer Brain Institute, Federal University of Rio de Janeiro, UFRJ, Rio de Janeiro, Rio de Janeiro, Brazil
| | - Cirle A. Warren
- Division of Infectious Diseases and International Health, University of Virginia, Charlottesville, VA, United States
| | - Deiziane V.S. Costa
- Division of Infectious Diseases and International Health, University of Virginia, Charlottesville, VA, United States
- *Correspondence: Gerly A. C. Brito, ; Deiziane V.S. Costa,
| | - Gerly A. C. Brito
- Department of Morphology, School of Medicine, Federal University of Ceará, Fortaleza, Ceará, Brazil
- Department of Physiology and Pharmacology, School of Medicine, Federal University of Ceara, Fortaleza, Ceara, Brazil
- *Correspondence: Gerly A. C. Brito, ; Deiziane V.S. Costa,
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Clostridioides difficile toxin B alone and with pro-inflammatory cytokines induces apoptosis in enteric glial cells by activating three different signalling pathways mediated by caspases, calpains and cathepsin B. Cell Mol Life Sci 2022; 79:442. [PMID: 35864342 PMCID: PMC9304068 DOI: 10.1007/s00018-022-04459-z] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2021] [Revised: 06/22/2022] [Accepted: 06/29/2022] [Indexed: 11/03/2022]
Abstract
Clostridioides difficile infection (CDI) causes nosocomial/antibiotic-associated gastrointestinal diseases with dramatically increasing global incidence and mortality rates. The main C. difficile virulence factors, toxins A and B (TcdA/TcdB), cause cytopathic/cytotoxic effects and inflammation. We demonstrated that TcdB induces caspase-dependent, mitochondria-independent enteric glial cell (EGC) apoptosis that is enhanced by the pro-inflammatory cytokines TNF-α and IFN-γ (CKs) by increasing caspase-3/7/9 and PARP activation. Because this cytotoxic synergism is important for CDI pathogenesis, we investigated the apoptotic pathways involved in TcdB- and TcdB + CK-induced apoptosis indepth. EGCs were pre-treated with the inhibitors BAF or Q-VD-OPh (pan-caspase), Z-DEVD-fmk (caspase-3/7), Z-IETD-fmk (caspase-8), PD150606 (calpains), and CA-074Me (cathepsin B) 1 h before TcdB exposure, while CKs were given 1.5 h after TcdB exposure, and assays were performed at 24 h. TcdB and TcdB + CKs induced apoptosis through three signalling pathways activated by calpains, caspases and cathepsins, which all are involved both in induction and execution apoptotic signalling under both conditions but to different degrees in TcdB and TcdB + CKs especially as regards to signal transduction mediated by these proteases towards downstream effects (apoptosis). Calpain activation by Ca2+ influx is the first pro-apoptotic event in TcdB- and TcdB + CK-induced EGC apoptosis and causes caspase-3, caspase-7 and PARP activation. PARP is also directly activated by calpains which are responsible of about 75% of apoptosis in TcdB and 62% in TcdB + CK which is both effector caspase-dependent and -independent. Initiator caspase-8 activation mediated by TcdB contributes to caspase-3/caspase-7 and PARP activation and is responsible of about 28% of apoptosis in both conditions. Caspase-3/caspase-7 activation is weakly responsible of apoptosis, indeed we found that it mediates 27% of apoptosis only in TcdB. Cathepsin B contributes to triggering pro-apoptotic signal and is responsible in both conditions of about 35% of apoptosis by a caspase-independent manner, and seems to regulate the caspase-3 and caspase-7 cleaved fragment levels, highlighting the complex interaction between these cysteine protease families activated during TcdB-induced apoptosis. Further a relevant difference between TcdB- and TcdB + CK-induced apoptosis is that TcdB-induced apoptosis increased slowly reaching at 72 h the value of 18.7%, while TcdB + CK-induced apoptosis increased strongly reaching at 72 h the value of 60.6%. Apoptotic signalling activation by TcdB + CKs is enriched by TNF-α-induced NF-κB signalling, inhibition of JNK activation and activation of AKT. In conclusion, the ability of C. difficile to activate three apoptotic pathways represents an important strategy to overcome resistance against its cytotoxic activity.
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Kordus SL, Thomas AK, Lacy DB. Clostridioides difficile toxins: mechanisms of action and antitoxin therapeutics. Nat Rev Microbiol 2022; 20:285-298. [PMID: 34837014 PMCID: PMC9018519 DOI: 10.1038/s41579-021-00660-2] [Citation(s) in RCA: 53] [Impact Index Per Article: 26.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/21/2021] [Indexed: 01/03/2023]
Abstract
Clostridioides difficile is a Gram-positive anaerobe that can cause a spectrum of disorders that range in severity from mild diarrhoea to fulminant colitis and/or death. The bacterium produces up to three toxins, which are considered the major virulence factors in C. difficile infection. These toxins promote inflammation, tissue damage and diarrhoea. In this Review, we highlight recent biochemical and structural advances in our understanding of the mechanisms that govern host-toxin interactions. Understanding how C. difficile toxins affect the host forms a foundation for developing novel strategies for treatment and prevention of C. difficile infection.
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Affiliation(s)
- Shannon L. Kordus
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University Medical Center, Nashville, TN, USA,Center for Structural Biology, Vanderbilt University, Nashville, TN, USA,These authors contributed equally: Shannon L. Kordus, Audrey K. Thomas
| | - Audrey K. Thomas
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University Medical Center, Nashville, TN, USA,Center for Structural Biology, Vanderbilt University, Nashville, TN, USA,These authors contributed equally: Shannon L. Kordus, Audrey K. Thomas
| | - D. Borden Lacy
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University Medical Center, Nashville, TN, USA,Center for Structural Biology, Vanderbilt University, Nashville, TN, USA,The Veterans Affairs, Tennessee Valley Healthcare, System, Nashville, TN, USA,
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8
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Zhang L, Liu F, Xue J, Lee SA, Liu L, Riordan SM. Bacterial Species Associated With Human Inflammatory Bowel Disease and Their Pathogenic Mechanisms. Front Microbiol 2022; 13:801892. [PMID: 35283816 PMCID: PMC8908260 DOI: 10.3389/fmicb.2022.801892] [Citation(s) in RCA: 20] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2021] [Accepted: 01/25/2022] [Indexed: 12/17/2022] Open
Abstract
Inflammatory bowel disease (IBD) is a chronic inflammatory condition of the gastrointestinal tract with unknown etiology. The pathogenesis of IBD results from immune responses to microbes in the gastrointestinal tract. Various bacterial species that are associated with human IBD have been identified. However, the microbes that trigger the development of human IBD are still not clear. Here we review bacterial species that are associated with human IBD and their pathogenic mechanisms to provide an updated broad understanding of this research field. IBD is an inflammatory syndrome rather than a single disease. We propose a three-stage pathogenesis model to illustrate the roles of different IBD-associated bacterial species and gut commensal bacteria in the development of human IBD. Finally, we recommend microbe-targeted therapeutic strategies based on the three-stage pathogenesis model.
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Affiliation(s)
- Li Zhang
- School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, NSW, Australia
- *Correspondence: Li Zhang,
| | - Fang Liu
- School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, NSW, Australia
| | - Jessica Xue
- Faculty of Medicine, Monash University, Melbourne, VIC, Australia
| | - Seul A. Lee
- School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, NSW, Australia
| | - Lu Liu
- School of Medical Sciences, University of New South Wales, Sydney, NSW, Australia
| | - Stephen M. Riordan
- Gastrointestinal and Liver Unit, Prince of Wales Hospital, University of New South Wales, Sydney, NSW, Australia
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Song J, Shen X, Huang Z, Liu Y, Cui L, Cui X, Liu CY. Clostridium difficile toxin A and toxin B inhibit YAP in the colonic epithelial cells. J Biochem Mol Toxicol 2020; 35:e22652. [PMID: 33251692 DOI: 10.1002/jbt.22652] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2019] [Revised: 04/14/2020] [Accepted: 09/29/2020] [Indexed: 11/08/2022]
Abstract
Toxin A (TcdA) and toxin B (TcdB), the two exotoxins of Clostridium difficile, are main causal agents for the colonic epithelium damage in Clostridium difficile infection (CDI). The Hippo pathway is crucial for the control of tissue homeostasis and regeneration of intestines. However, the dysregulation of Hippo pathway in CDI is unclear. Here we show that YAP and TAZ, the transcriptional coactivators downstream of the Hippo pathway, are sequestered in the cytoplasm, degraded, and inactivated by treatment with TcdA and TcdB in colonic epithelial cells. The overexpression of YAP restores the messenger RNA expressions of YAP target genes, attenuates the disruption of cytoskeleton and cell rounding, and rescues the cell proliferation of colonic epithelial cells under exposure of the two toxins. Our results demonstrate that inhibition of YAP and TAZ is involved in the pathogenesis of CDI, implicating that increasing YAP activity could be a potential therapeutic strategy for the CDI treatment.
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Affiliation(s)
- Jinglue Song
- Department of Colorectal and Anal Surgery, Xinhua Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China.,Shanghai Colorectal Cancer Research Center, Shanghai, China
| | - Xia Shen
- Department of Colorectal and Anal Surgery, Xinhua Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China.,Shanghai Colorectal Cancer Research Center, Shanghai, China
| | - Zhenyu Huang
- Department of Colorectal and Anal Surgery, Xinhua Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China.,Shanghai Colorectal Cancer Research Center, Shanghai, China
| | - Yun Liu
- Department of Colorectal and Anal Surgery, Xinhua Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China.,Shanghai Colorectal Cancer Research Center, Shanghai, China
| | - Long Cui
- Department of Colorectal and Anal Surgery, Xinhua Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China.,Shanghai Colorectal Cancer Research Center, Shanghai, China
| | - Xuewei Cui
- Department of Anesthesiology, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Chen-Ying Liu
- Department of Colorectal and Anal Surgery, Xinhua Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China.,Shanghai Colorectal Cancer Research Center, Shanghai, China
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Gao X, Yang Q, Huang X, Yan Z, Zhang S, Luo R, Wang P, Wang W, Xie K, Jiang T, Gun S. Effects of Clostridium perfringens beta2 toxin on apoptosis, inflammation, and barrier function of intestinal porcine epithelial cells. Microb Pathog 2020; 147:104379. [DOI: 10.1016/j.micpath.2020.104379] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2020] [Revised: 05/12/2020] [Accepted: 07/01/2020] [Indexed: 12/19/2022]
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11
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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 PMCID: PMC7465811 DOI: 10.1186/s12866-020-01958-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [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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Bilverstone TW, Garland M, Cave RJ, Kelly ML, Tholen M, Bouley DM, Kaye P, Minton NP, Bogyo M, Kuehne SA, Melnyk RA. The glucosyltransferase activity of C. difficile Toxin B is required for disease pathogenesis. PLoS Pathog 2020; 16:e1008852. [PMID: 32960931 PMCID: PMC7531778 DOI: 10.1371/journal.ppat.1008852] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2020] [Revised: 10/02/2020] [Accepted: 08/03/2020] [Indexed: 01/01/2023] Open
Abstract
Enzymatic inactivation of Rho-family GTPases by the glucosyltransferase domain of Clostridioides difficile Toxin B (TcdB) gives rise to various pathogenic effects in cells that are classically thought to be responsible for the disease symptoms associated with C. difficile infection (CDI). Recent in vitro studies have shown that TcdB can, under certain circumstances, induce cellular toxicities that are independent of glucosyltransferase (GT) activity, calling into question the precise role of GT activity. Here, to establish the importance of GT activity in CDI disease pathogenesis, we generated the first described mutant strain of C. difficile producing glucosyltransferase-defective (GT-defective) toxin. Using allelic exchange (AE) technology, we first deleted tcdA in C. difficile 630Δerm and subsequently introduced a deactivating D270N substitution in the GT domain of TcdB. To examine the role of GT activity in vivo, we tested each strain in two different animal models of CDI pathogenesis. In the non-lethal murine model of infection, the GT-defective mutant induced minimal pathology in host tissues as compared to the profound caecal inflammation seen in the wild-type and 630ΔermΔtcdA (ΔtcdA) strains. In the more sensitive hamster model of CDI, whereas hamsters in the wild-type or ΔtcdA groups succumbed to fulminant infection within 4 days, all hamsters infected with the GT-defective mutant survived the 10-day infection period without primary symptoms of CDI or evidence of caecal inflammation. These data demonstrate that GT activity is indispensable for disease pathogenesis and reaffirm its central role in disease and its importance as a therapeutic target for small-molecule inhibition.
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Affiliation(s)
- Terry W. Bilverstone
- Clostridia Research Group, BBSRC/EPSRC Synthetic Biology Research Centre, School of Life Sciences, Centre for Biomolecular Sciences, The University of Nottingham, Nottingham, United kingdom
| | - Megan Garland
- Cancer Biology Program, Stanford School of Medicine, Stanford, CA, United States of America
- Department of Pathology, Stanford School of Medicine, Stanford, CA, United States of America
| | - Rory J. Cave
- Clostridia Research Group, BBSRC/EPSRC Synthetic Biology Research Centre, School of Life Sciences, Centre for Biomolecular Sciences, The University of Nottingham, Nottingham, United kingdom
| | - Michelle L. Kelly
- Clostridia Research Group, BBSRC/EPSRC Synthetic Biology Research Centre, School of Life Sciences, Centre for Biomolecular Sciences, The University of Nottingham, Nottingham, United kingdom
| | - Martina Tholen
- Department of Pathology, Stanford School of Medicine, Stanford, CA, United States of America
| | - Donna M. Bouley
- Department of Comparative Medicine, Stanford School of Medicine, Stanford, CA, United States of America
| | - Philip Kaye
- Department of Histopathology, Nottingham University Hospitals and University of Nottingham NDDC NIHR BRC, Nottingham, United Kingdom
| | - Nigel P. Minton
- Clostridia Research Group, BBSRC/EPSRC Synthetic Biology Research Centre, School of Life Sciences, Centre for Biomolecular Sciences, The University of Nottingham, Nottingham, United kingdom
- NIHR Nottingham Biomedical Research Centre, Nottingham University Hospitals NHS Trust and the University of Nottingham, Nottingham, United Kingdom
| | - Matthew Bogyo
- Department of Pathology, Stanford School of Medicine, Stanford, CA, United States of America
- Department of Microbiology and Immunology, Stanford School of Medicine, Stanford, CA, United States of America
| | - Sarah A. Kuehne
- Oral Microbiology Group, School of Dentistry and Institute of Microbiology and Infection, College of Medical and Dental Sciences, The University of Birmingham, Birmingham, United Kingdom
| | - Roman A. Melnyk
- Department of Biochemistry, University of Toronto, and Program in Molecular Medicine, The Hospital for Sick Children, Toronto, ON, Canada
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13
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Identification of the role of toxin B in the virulence of Clostridioides difficile based on integrated bioinformatics analyses. Int Microbiol 2020; 23:575-587. [PMID: 32388701 DOI: 10.1007/s10123-020-00128-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2019] [Revised: 03/03/2020] [Accepted: 04/13/2020] [Indexed: 02/08/2023]
Abstract
PURPOSE Clostridioides difficile toxin B (TcdB) plays a critical role in C. difficile infection (CDI), a common and costly healthcare-associated disease. The aim of the current study was to explore the intracellular and potent systemic effects of TcdB on human colon epithelial cells utilizing Gene Expression Omnibus and bioinformatic methods. METHODS Two datasets (GSE63880 and GSE29008) were collected to extract data components of mRNA of TcdB-treated human colon epithelial cells; "limma" package of "R" software was used to screen the differential genes, and "pheatmap" package was applied to construct heat maps for the differential genes; Metascape website was utilized for protein-protein interaction network and Molecular Complex Detection analysis, and Genome Ontology (GO) was used to analyze the selected differential genes. Quantitative real-time PCR (qRT-PCR) and Western blot were performed to validate the expression of hub genes. RESULTS GO terms involved in DNA replication and cell cycle were identified significantly enriched in TcdB-treated human colon epithelial cells. Moreover, the decreased expression of DNA replication-related genes, MCM complex, and CDC45 in C. difficile (TcdA-/TcdB+)-infected Caco-2 cells were validated via qRT-PCR and Western blot assays. CONCLUSIONS In conclusion, the integrated analysis of different gene expression datasets allowed us to identify a set of genes and GO terms underlying the mechanisms of CDI induced by TcdB. It would aid in understanding of the molecular mechanisms underlying TcdB-exposed colon epithelial cells and provide the basis for developing diagnosis biomarkers, treatment, and prevention strategies.
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14
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Asadzadeh Z, Safarzadeh E, Safaei S, Baradaran A, Mohammadi A, Hajiasgharzadeh K, Derakhshani A, Argentiero A, Silvestris N, Baradaran B. Current Approaches for Combination Therapy of Cancer: The Role of Immunogenic Cell Death. Cancers (Basel) 2020; 12:E1047. [PMID: 32340275 PMCID: PMC7226590 DOI: 10.3390/cancers12041047] [Citation(s) in RCA: 85] [Impact Index Per Article: 21.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2020] [Revised: 04/08/2020] [Accepted: 04/17/2020] [Indexed: 12/31/2022] Open
Abstract
Cell death resistance is a key feature of tumor cells. One of the main anticancer therapies is increasing the susceptibility of cells to death. Cancer cells have developed a capability of tumor immune escape. Hence, restoring the immunogenicity of cancer cells can be suggested as an effective approach against cancer. Accumulating evidence proposes that several anticancer agents provoke the release of danger-associated molecular patterns (DAMPs) that are determinants of immunogenicity and stimulate immunogenic cell death (ICD). It has been suggested that ICD inducers are two different types according to their various activities. Here, we review the well-characterized DAMPs and focus on the different types of ICD inducers and recent combination therapies that can augment the immunogenicity of cancer cells.
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Affiliation(s)
- Zahra Asadzadeh
- Immunology Research Center, Tabriz University of Medical Sciences, Tabriz 5165665811, Iran; (Z.A.); (S.S.); (K.H.); (A.D.)
| | - Elham Safarzadeh
- Department of Immunology and Microbiology, Faculty of Medicine, Ardabil University of Medical Sciences, Ardabil 5618985991, Iran;
| | - Sahar Safaei
- Immunology Research Center, Tabriz University of Medical Sciences, Tabriz 5165665811, Iran; (Z.A.); (S.S.); (K.H.); (A.D.)
| | - Ali Baradaran
- Research & Development Lab, BSD Robotics, 4500 Brisbane, Australia;
| | - Ali Mohammadi
- Department of Cancer and Inflammation Research, Institute for Molecular Medicine, University of Southern Denmark, 5230 Odense, Denmark;
| | - Khalil Hajiasgharzadeh
- Immunology Research Center, Tabriz University of Medical Sciences, Tabriz 5165665811, Iran; (Z.A.); (S.S.); (K.H.); (A.D.)
| | - Afshin Derakhshani
- Immunology Research Center, Tabriz University of Medical Sciences, Tabriz 5165665811, Iran; (Z.A.); (S.S.); (K.H.); (A.D.)
| | | | - Nicola Silvestris
- IRCCS Istituto Tumori “Giovanni Paolo II” of Bari, 70124 Bari, Italy;
- Department of Biomedical Sciences and Human Oncology, University of Bari “Aldo Moro”, 70124 Bari, Italy
| | - Behzad Baradaran
- Immunology Research Center, Tabriz University of Medical Sciences, Tabriz 5165665811, Iran; (Z.A.); (S.S.); (K.H.); (A.D.)
- Department of Immunology, Faculty of Medicine, Tabriz University of Medical Sciences, Tabriz 5166614766, Iran
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15
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Cole LE, Li L, Jetley U, Zhang J, Pacheco K, Ma F, Zhang J, Mundle S, Yan Y, Barone L, Rogers C, Beltraminelli N, Quemeneur L, Kleanthous H, Anderson SF, Anosova NG. Deciphering the domain specificity of C. difficile toxin neutralizing antibodies. Vaccine 2019; 37:3892-3901. [PMID: 31122858 DOI: 10.1016/j.vaccine.2019.05.040] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2019] [Revised: 04/10/2019] [Accepted: 05/13/2019] [Indexed: 12/21/2022]
Abstract
Clostridium difficile infection (CDI) is the principal cause of nosocomial diarrhea and pseudomembranous colitis associated with antibiotic therapy. The pathological effects of CDI are primarily attributed to toxins A (TcdA) and B (TcdB). Adequate toxin-specific antibody responses are associated with asymptomatic carriage, whereas insufficient humoral responses are associated with recurrent CDI. While the data supporting the importance of anti-toxin antibodies are substantial, clarity about the toxin domain specificity of these antibodies is more limited. To investigate this matter, combinations of human mAbs targeting multiple domains of TcdB were assessed using toxin neutralization assays. These data revealed that a combination of mAbs specific to all major toxin domains had improved neutralizing potency when compared to equivalent concentrations of a single mAb or a combination of mAbs against one or two domains. The function and toxin domain binding specificity of serum antibodies elicited by immunization of hamsters with a toxoid vaccine candidate was also assessed. Immunization with a toxoid vaccine candidate provoked toxin neutralizing antibodies specific to multiple domains of both TcdA and TcdB. When assessed in a toxin neutralization assay, polyclonal sera displayed greater activity against elevated concentrations of toxins than equivalent concentrations of individual mAbs. These data suggest a potential benefit of any antibody based therapeutic or prophylactic treatment that targets multiple toxin domains.
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Affiliation(s)
- Leah E Cole
- Sanofi Pasteur, Research North America, 38 Sidney Street, Cambridge, MA 02139, USA
| | - Lu Li
- Sanofi Pasteur, Research North America, 38 Sidney Street, Cambridge, MA 02139, USA
| | - Utsav Jetley
- Sanofi Pasteur, Research North America, 38 Sidney Street, Cambridge, MA 02139, USA; Momenta Pharmaceuticals, INC., Research, 675 W Kendall St, Cambridge, MA 02142, USA
| | - Jinrong Zhang
- Sanofi Pasteur, Research North America, 38 Sidney Street, Cambridge, MA 02139, USA
| | - Kristl Pacheco
- Sanofi Pasteur, Research North America, 38 Sidney Street, Cambridge, MA 02139, USA
| | - Fuqin Ma
- Sanofi Pasteur, Research North America, 38 Sidney Street, Cambridge, MA 02139, USA
| | - Jianxin Zhang
- Sanofi Pasteur, Research North America, 38 Sidney Street, Cambridge, MA 02139, USA
| | - Sophia Mundle
- Sanofi Pasteur, Research North America, 38 Sidney Street, Cambridge, MA 02139, USA
| | - Yanhua Yan
- Sanofi Pasteur, Research North America, 38 Sidney Street, Cambridge, MA 02139, USA
| | - Lucianna Barone
- Sanofi Pasteur, Research North America, 38 Sidney Street, Cambridge, MA 02139, USA; Harvard Vanguard Medical Associates, 230 Worcester Street, Wellesley, MA 02481, USA
| | - Christopher Rogers
- Sanofi Pasteur, Research North America, 38 Sidney Street, Cambridge, MA 02139, USA; Maine Medical Center, Department of Pediatrics, 22 Bramhall Street, Portland, ME 04102, USA
| | - Nicola Beltraminelli
- BliNK Biomedical SAS, R&D, Gerland Plaza Techsud, 70, rue Saint Jean de Dieu, 69007 Lyon, France
| | - Laurence Quemeneur
- Sanofi Pasteur, Research Europe, 1541, Avenue Marcel Mérieux, 68280 Marcy l'Etoile, France
| | - Harry Kleanthous
- Sanofi Pasteur, Research North America, 38 Sidney Street, Cambridge, MA 02139, USA
| | - Stephen F Anderson
- Sanofi Pasteur, Research North America, 38 Sidney Street, Cambridge, MA 02139, USA; Anokion US, Inc., Development and Analytics, 50 Hampshire Street, Cambridge, MA 02139, USA
| | - Natalie G Anosova
- Sanofi Pasteur, Research North America, 38 Sidney Street, Cambridge, MA 02139, USA.
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16
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Mileto S, Das A, Lyras D. Enterotoxic Clostridia: Clostridioides difficile Infections. Microbiol Spectr 2019; 7:10.1128/microbiolspec.gpp3-0015-2018. [PMID: 31124432 PMCID: PMC11026080 DOI: 10.1128/microbiolspec.gpp3-0015-2018] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2018] [Indexed: 12/17/2022] Open
Abstract
Clostridioides difficile is a Gram-positive, anaerobic, spore forming pathogen of both humans and animals and is the most common identifiable infectious agent of nosocomial antibiotic-associated diarrhea. Infection can occur following the ingestion and germination of spores, often concurrently with a disruption to the gastrointestinal microbiota, with the resulting disease presenting as a spectrum, ranging from mild and self-limiting diarrhea to severe diarrhea that may progress to life-threating syndromes that include toxic megacolon and pseudomembranous colitis. Disease is induced through the activity of the C. difficile toxins TcdA and TcdB, both of which disrupt the Rho family of GTPases in host cells, causing cell rounding and death and leading to fluid loss and diarrhea. These toxins, despite their functional and structural similarity, do not contribute to disease equally. C. difficile infection (CDI) is made more complex by a high level of strain diversity and the emergence of epidemic strains, including ribotype 027-strains which induce more severe disease in patients. With the changing epidemiology of CDI, our understanding of C. difficile disease, diagnosis, and pathogenesis continues to evolve. This article provides an overview of the current diagnostic tests available for CDI, strain typing, the major toxins C. difficile produces and their mode of action, the host immune response to each toxin and during infection, animal models of disease, and the current treatment and prevention strategies for CDI.
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Affiliation(s)
- S Mileto
- Infection and Immunity Program, Monash Biomedicine Discovery Institute and Department of Microbiology, Monash University, Clayton, Victoria, Australia, 3800
| | - A Das
- Infection and Immunity Program, Monash Biomedicine Discovery Institute and Department of Microbiology, Monash University, Clayton, Victoria, Australia, 3800
| | - D Lyras
- Infection and Immunity Program, Monash Biomedicine Discovery Institute and Department of Microbiology, Monash University, Clayton, Victoria, Australia, 3800
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17
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Junemann J, Just I, Gerhard R, Pich A. Quantitative Phosphoproteome Analysis of Clostridioides difficile Toxin B Treated Human Epithelial Cells. Front Microbiol 2018; 9:3083. [PMID: 30619164 PMCID: PMC6304397 DOI: 10.3389/fmicb.2018.03083] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2018] [Accepted: 11/29/2018] [Indexed: 01/02/2023] Open
Abstract
The large clostridial glucosylating toxin B (TcdB) is a major virulence factor of the nosocomial pathogen Clostridioides difficile. TcdB inhibits small GTPases by glucosylation leading to impaired downstream signaling. TcdB also possesses a glucosyltransferase independent effect described as pyknosis. To elucidate the impact of TcdB and its glucosylation-inactive mutant TcdBNXN on the kinome of human cells, SILAC labeled HEp-2 cells were treated with 2 nM TcdB for 8 h. Phosphopeptides were enriched using SCX chromatography, IMAC and TiO2 followed shotgun mass spectrometry analysis. Overall 4,197 phosphopeptides were identified; more than 1,200 phosphosites responded to treatment with TcdB or TcdBNXN. The data suggested that predominantly stress-activated MAPK-dependent signaling pathways were triggered by toxin B treatment.
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Affiliation(s)
| | - Ingo Just
- Hannover Medical School, Institute for Toxicology, Hanover, Germany
| | - Ralf Gerhard
- Hannover Medical School, Institute for Toxicology, Hanover, Germany
| | - Andreas Pich
- Hannover Medical School, Institute for Toxicology, Hanover, Germany
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18
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Tam J, Hamza T, Ma B, Chen K, Beilhartz GL, Ravel J, Feng H, Melnyk RA. Host-targeted niclosamide inhibits C. difficile virulence and prevents disease in mice without disrupting the gut microbiota. Nat Commun 2018; 9:5233. [PMID: 30531960 PMCID: PMC6286312 DOI: 10.1038/s41467-018-07705-w] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2018] [Accepted: 11/19/2018] [Indexed: 12/13/2022] Open
Abstract
Clostridium difficile is the leading cause of nosocomial diarrhea and colitis in the industrialized world. Disruption of the protective gut microbiota by antibiotics enables colonization by multidrug-resistant C. difficile, which secrete up to three different protein toxins that are responsible for the gastrointestinal sequelae. Oral agents that inhibit the damage induced by toxins, without altering the gut microbiota, are urgently needed to prevent primary disease and break the cycle of antibiotic-induced disease recurrence. Here, we show that the anthelmintic drug, niclosamide, inhibits the pathogenesis of all three toxins by targeting a host process required for entry into colonocytes by each toxin. In mice infected with an epidemic strain of C. difficile, expressing all three toxins, niclosamide reduced both primary disease and recurrence, without disrupting the diversity or composition of the gut microbiota. Given its excellent safety profile, niclosamide may address an important unmet need in preventing C. difficile primary and recurrent diseases. Clostridium difficile causes diarrhea and colitis by producing up to three different protein toxins. Here, Tam et al. show that an anthelmintic drug, niclosamide, inhibits the pathogenesis of all three toxins by targeting a host process required for toxin entry into host cells, without disrupting the gut microbiota.
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Affiliation(s)
- John Tam
- Molecular Medicine, Hospital for Sick Children, 686 Bay St., Toronto, ON, M5G 0A4, Canada.,Department of Biochemistry, University of Toronto, Toronto, ON, M5S 1A8, Canada
| | - Therwa Hamza
- Department of Microbial Pathogenesis, University of Maryland Dental School, Baltimore, MD, 21201, USA
| | - Bing Ma
- Institute for Genome Sciences, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Kevin Chen
- Department of Microbial Pathogenesis, University of Maryland Dental School, Baltimore, MD, 21201, USA
| | - Greg L Beilhartz
- Molecular Medicine, Hospital for Sick Children, 686 Bay St., Toronto, ON, M5G 0A4, Canada
| | - Jacques Ravel
- Institute for Genome Sciences, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Hanping Feng
- Department of Microbial Pathogenesis, University of Maryland Dental School, Baltimore, MD, 21201, USA
| | - Roman A Melnyk
- Molecular Medicine, Hospital for Sick Children, 686 Bay St., Toronto, ON, M5G 0A4, Canada. .,Department of Biochemistry, University of Toronto, Toronto, ON, M5S 1A8, Canada.
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19
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Apoptosis of intestinal epithelial cells restricts Clostridium difficile infection in a model of pseudomembranous colitis. Nat Commun 2018; 9:4846. [PMID: 30451870 PMCID: PMC6242954 DOI: 10.1038/s41467-018-07386-5] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2018] [Accepted: 10/26/2018] [Indexed: 12/11/2022] Open
Abstract
Clostridium difficile is the leading cause of pseudomembranous colitis in hospitalized patients. C. difficile enterotoxins TcdA and TcdB promote this inflammatory condition via a cytotoxic response on intestinal epithelial cells (IECs), but the underlying mechanisms are incompletely understood. Additionally, TcdA and TcdB engage the Pyrin inflammasome in macrophages, but whether Pyrin modulates CDI pathophysiology is unknown. Here we show that the Pyrin inflammasome is not functional in IECs and that Pyrin signaling is dispensable for CDI-associated IEC death and for in vivo pathogenesis. Instead, our studies establish that C. difficile enterotoxins induce activation of executioner caspases 3/7 via the intrinsic apoptosis pathway, and demonstrate that caspase-3/7-mediated IEC apoptosis is critical for in vivo host defense during early stages of CDI. In conclusion, our findings dismiss a critical role for inflammasomes in CDI pathogenesis, and identify IEC apoptosis as a host defense mechanism that restricts C. difficile infection in vivo.
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20
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Xi Y, Ma Z, Zhang H, Yuan M, Wang L. Effects of Clostridium difficile toxin A on K562/A02 cell proliferation, apoptosis and multi-drug resistance. Oncol Lett 2018; 15:4215-4220. [PMID: 29545897 PMCID: PMC5841023 DOI: 10.3892/ol.2018.7921] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2017] [Accepted: 01/24/2018] [Indexed: 12/20/2022] Open
Abstract
The aim of the present study was to investigate the cytotoxic effect and multi-drug resistance (MDR) of Clostridium difficile toxin A (TcdA) on K562/A02 cells, and understand its underlying molecular pathways. K562/A02 cells were treated with TcdA at different concentrations for 24, 48 and 72 h, and the inhibition effect and drug resistance of TcdA on K562/A02 cell proliferation was assessed by methyl thiazolyl tetrazolium colorimetric assay. Furthermore, cell cycle-apoptosis was analyzed by flow cytometry, P-glycoprotein (P-gp) expression was determined by western blot analysis and caspase-3 activity was measured using a caspase-3 activity kit. TcdA inhibited K562/A02 cell proliferation in a time- and dose-dependent manner. The inhibition rate of K562/A02 cells reached 8.76±0.76, 28.55±0.43, 47.89±0.27, 58.08±0.06 and 57.70±0.79% following treatment with 50, 100, 200, 400 and 800 ng/ml TcdA, respectively, for 24 h. K562/A02 cells in the G0/G1 phase increased and cells in the S phase decreased following treatment with TcdA (P<0.05), and the apoptotic rates in the 200 and 400 ng/ml concentration groups were 14.05 and 22.89%, respectively. In addition, TcdA (50 ng/ml) significantly inhibited the proliferation of K562/A02 cells and reduced the half maximal inhibitory concentration of these drugs in combination with chemotherapy drugs. The reversal folds were 3.09, 2.89 and 2.79, respectively. Furthermore, TcdA treatment was associated with the upregulation of P-gp in K562/A02 cells, and caspase-3 activity was observed to increase in K562/A02 cells following TcdA treatment, when compared with untreated controls (P<0.05). These findings suggested that TcdA may be able to inhibit K562/A02 cell growth, induce cell apoptosis by decreasing P-gp levels and caspase-3 activation, and partially reverse MDR. Further studies are required to evaluate the potential of TcdA as a candidate for the chemotherapy of hematologic malignancies.
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Affiliation(s)
- Yaming Xi
- Department of Hematology, The First Hospital of Lanzhou University, Lanzhou, Gansu 730000, P.R. China
| | - Zhuanzhen Ma
- Department of Hematology, The First Hospital of Lanzhou University, Lanzhou, Gansu 730000, P.R. China
| | - Hao Zhang
- Department of Hematology, The First Hospital of Lanzhou University, Lanzhou, Gansu 730000, P.R. China
| | - Maowen Yuan
- Department of Hematology, The First Hospital of Lanzhou University, Lanzhou, Gansu 730000, P.R. China
| | - Lina Wang
- Department of Hematology, The First Hospital of Lanzhou University, Lanzhou, Gansu 730000, P.R. China
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21
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Chandrasekaran R, Lacy DB. The role of toxins in Clostridium difficile infection. FEMS Microbiol Rev 2017; 41:723-750. [PMID: 29048477 PMCID: PMC5812492 DOI: 10.1093/femsre/fux048] [Citation(s) in RCA: 200] [Impact Index Per Article: 28.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2017] [Accepted: 10/10/2017] [Indexed: 02/06/2023] Open
Abstract
Clostridium difficile is a bacterial pathogen that is the leading cause of nosocomial antibiotic-associated diarrhea and pseudomembranous colitis worldwide. The incidence, severity, mortality and healthcare costs associated with C. difficile infection (CDI) are rising, making C. difficile a major threat to public health. Traditional treatments for CDI involve use of antibiotics such as metronidazole and vancomycin, but disease recurrence occurs in about 30% of patients, highlighting the need for new therapies. The pathogenesis of C. difficile is primarily mediated by the actions of two large clostridial glucosylating toxins, toxin A (TcdA) and toxin B (TcdB). Some strains produce a third toxin, the binary toxin C. difficile transferase, which can also contribute to C. difficile virulence and disease. These toxins act on the colonic epithelium and immune cells and induce a complex cascade of cellular events that result in fluid secretion, inflammation and tissue damage, which are the hallmark features of the disease. In this review, we summarize our current understanding of the structure and mechanism of action of the C. difficile toxins and their role in disease.
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Affiliation(s)
- Ramyavardhanee Chandrasekaran
- Department of Pathology, Microbiology and Immunology, Vanderbilt University School of Medicine, Nashville, TN 37232, USA
| | - D. Borden Lacy
- Department of Pathology, Microbiology and Immunology, Vanderbilt University School of Medicine, Nashville, TN 37232, USA
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, TN 37232, USA
- The Veterans Affairs Tennessee Valley Healthcare System, Nashville, TN 37232, USA
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22
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Gupta P, Zhang Z, Sugiman-Marangos SN, Tam J, Raman S, Julien JP, Kroh HK, Lacy DB, Murgolo N, Bekkari K, Therien AG, Hernandez LD, Melnyk RA. Functional defects in Clostridium difficile TcdB toxin uptake identify CSPG4 receptor-binding determinants. J Biol Chem 2017; 292:17290-17301. [PMID: 28842504 DOI: 10.1074/jbc.m117.806687] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2017] [Revised: 08/11/2017] [Indexed: 12/11/2022] Open
Abstract
Clostridium difficile is a major nosocomial pathogen that produces two exotoxins, TcdA and TcdB, with TcdB thought to be the primary determinant in human disease. TcdA and TcdB are large, multidomain proteins, each harboring a cytotoxic glucosyltransferase domain that is delivered into the cytosol from endosomes via a translocation domain after receptor-mediated endocytosis of toxins from the cell surface. Although there are currently no known host cell receptors for TcdA, three cell-surface receptors for TcdB have been identified: CSPG4, NECTIN3, and FZD1/2/7. The sites on TcdB that mediate binding to each receptor are not defined. Furthermore, it is not known whether the combined repetitive oligopeptide (CROP) domain is involved in or required for receptor binding. Here, in a screen designed to identify sites in TcdB that are essential for target cell intoxication, we identified a region at the junction of the translocation and the CROP domains that is implicated in CSPG4 binding. Using a series of C-terminal truncations, we show that the CSPG4-binding site on TcdB extends into the CROP domain, requiring three short repeats for binding and for full toxicity on CSPG4-expressing cells. Consistent with the location of the CSPG4-binding site on TcdB, we show that the anti-TcdB antibody bezlotoxumab, which binds partially within the first three short repeats, prevents CSPG4 binding to TcdB. In addition to establishing the binding region for CSPG4, this work ascribes for the first time a role in TcdB CROPs in receptor binding and further clarifies the relative roles of host receptors in TcdB pathogenesis.
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Affiliation(s)
- Pulkit Gupta
- From Merck & Co., Inc., Kenilworth, New Jersey 07033
| | - Zhifen Zhang
- Molecular Medicine, The Hospital for Sick Children, Ontario M5G 0A4, Canada.,the Department of Biochemistry, University of Toronto, Toronto, Ontario M5S 1A8, Canada, and
| | | | - John Tam
- Molecular Medicine, The Hospital for Sick Children, Ontario M5G 0A4, Canada
| | - Swetha Raman
- Molecular Medicine, The Hospital for Sick Children, Ontario M5G 0A4, Canada
| | - Jean-Phillipe Julien
- Molecular Medicine, The Hospital for Sick Children, Ontario M5G 0A4, Canada.,the Department of Biochemistry, University of Toronto, Toronto, Ontario M5S 1A8, Canada, and
| | - Heather K Kroh
- the Departments of Pathology, Microbiology, and Immunology, Vanderbilt University School of Medicine, Nashville, Tennessee 37212
| | - D Borden Lacy
- the Departments of Pathology, Microbiology, and Immunology, Vanderbilt University School of Medicine, Nashville, Tennessee 37212
| | | | | | | | | | - Roman A Melnyk
- Molecular Medicine, The Hospital for Sick Children, Ontario M5G 0A4, Canada, .,the Department of Biochemistry, University of Toronto, Toronto, Ontario M5S 1A8, Canada, and
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23
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Orrell KE, Zhang Z, Sugiman-Marangos SN, Melnyk RA. Clostridium difficile toxins A and B: Receptors, pores, and translocation into cells. Crit Rev Biochem Mol Biol 2017; 52:461-473. [DOI: 10.1080/10409238.2017.1325831] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Affiliation(s)
- Kathleen E. Orrell
- Molecular Medicine Program, The Hospital for Sick Children Research Institute, Toronto, ON, Canada
- Department of Biochemistry, University of Toronto, Toronto, ON, Canada
| | - Zhifen Zhang
- Molecular Medicine Program, The Hospital for Sick Children Research Institute, Toronto, ON, Canada
- Department of Biochemistry, University of Toronto, Toronto, ON, Canada
| | | | - Roman A. Melnyk
- Molecular Medicine Program, The Hospital for Sick Children Research Institute, Toronto, ON, Canada
- Department of Biochemistry, University of Toronto, Toronto, ON, Canada
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24
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Fettucciari K, Ponsini P, Gioè D, Macchioni L, Palumbo C, Antonelli E, Coaccioli S, Villanacci V, Corazzi L, Marconi P, Bassotti G. Enteric glial cells are susceptible to Clostridium difficile toxin B. Cell Mol Life Sci 2017; 74:1527-1551. [PMID: 27891552 PMCID: PMC11107567 DOI: 10.1007/s00018-016-2426-4] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2016] [Revised: 10/27/2016] [Accepted: 11/21/2016] [Indexed: 02/06/2023]
Abstract
Clostridium difficile causes nosocomial/antibiotic-associated diarrhoea and pseudomembranous colitis. The major virulence factors are toxin A and toxin B (TcdB), which inactivate GTPases by monoglucosylation, leading to cytopathic (cytoskeleton alteration, cell rounding) and cytotoxic effects (cell-cycle arrest, apoptosis). C. difficile toxins breaching the intestinal epithelial barrier can act on underlying cells, enterocytes, colonocytes, and enteric neurons, as described in vitro and in vivo, but until now no data have been available on enteric glial cell (EGC) susceptibility. EGCs are crucial for regulating the enteric nervous system, gut homeostasis, the immune and inflammatory responses, and digestive and extradigestive diseases. Therefore, we evaluated the effects of C. difficile TcdB in EGCs. Rat-transformed EGCs were treated with TcdB at 0.1-10 ng/ml for 1.5-48 h, and several parameters were analysed. TcdB induces the following in EGCs: (1) early cell rounding with Rac1 glucosylation; (2) early G2/M cell-cycle arrest by cyclin B1/Cdc2 complex inactivation caused by p27 upregulation, the downregulation of cyclin B1 and Cdc2 phosphorylated at Thr161 and Tyr15; and (3) apoptosis by a caspase-dependent but mitochondria-independent pathway. Most importantly, the stimulation of EGCs with TNF-α plus IFN-γ before, concomitantly or after TcdB treatment strongly increased TcdB-induced apoptosis. Furthermore, EGCs that survived the cytotoxic effect of TcdB did not recover completely and showed not only persistent Rac1 glucosylation, cell-cycle arrest and low apoptosis but also increased production of glial cell-derived neurotrophic factor, suggesting self-rescuing mechanisms. In conclusion, the high susceptibility of EGCs to TcdB in vitro, the increased sensitivity to inflammatory cytokines related to apoptosis and the persistence of altered functions in surviving cells suggest an important in vivo role of EGCs in the pathogenesis of C. difficile infection.
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Affiliation(s)
- Katia Fettucciari
- Department of Experimental Medicine, Histology and Medical Embryology Section, Perugia University, Piazza Lucio Severi 1, Edificio B IV piano, Sant'Andrea delle Fratte, 06132, Perugia, Italy.
| | - Pamela Ponsini
- Department of Experimental Medicine, Histology and Medical Embryology Section, Perugia University, Piazza Lucio Severi 1, Edificio B IV piano, Sant'Andrea delle Fratte, 06132, Perugia, Italy
| | - Davide Gioè
- Department of Experimental Medicine, Histology and Medical Embryology Section, Perugia University, Piazza Lucio Severi 1, Edificio B IV piano, Sant'Andrea delle Fratte, 06132, Perugia, Italy
| | - Lara Macchioni
- Department of Experimental Medicine, Physiology and Biochemistry Section, Perugia University, Perugia, Italy
| | - Camilla Palumbo
- Department of Clinical Sciences and Translational Medicine, Tor Vergata University, Rome, Italy
| | | | - Stefano Coaccioli
- Department of Medicine, Internal Medicine, Rheumatology and Medical Therapy of Pain Section, Perugia University, District of Terni, Perugia, Italy
| | | | - Lanfranco Corazzi
- Department of Experimental Medicine, Physiology and Biochemistry Section, Perugia University, Perugia, Italy
| | - Pierfrancesco Marconi
- Department of Experimental Medicine, Histology and Medical Embryology Section, Perugia University, Piazza Lucio Severi 1, Edificio B IV piano, Sant'Andrea delle Fratte, 06132, Perugia, Italy
| | - Gabrio Bassotti
- Department of Medicine, Gastroenterology, Hepatology and Digestive Endoscopy Section, Perugia University, Perugia, Italy
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Epitopes and Mechanism of Action of the Clostridium difficile Toxin A-Neutralizing Antibody Actoxumab. J Mol Biol 2017; 429:1030-1044. [PMID: 28232034 DOI: 10.1016/j.jmb.2017.02.010] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [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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Chandrasekaran R, Kenworthy AK, Lacy DB. Clostridium difficile Toxin A Undergoes Clathrin-Independent, PACSIN2-Dependent Endocytosis. PLoS Pathog 2016; 12:e1006070. [PMID: 27942025 PMCID: PMC5152916 DOI: 10.1371/journal.ppat.1006070] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2016] [Accepted: 11/17/2016] [Indexed: 12/18/2022] Open
Abstract
Clostridium difficile infection affects a significant number of hospitalized patients in the United States. Two homologous exotoxins, TcdA and TcdB, are the major virulence factors in C. difficile pathogenesis. The toxins are glucosyltransferases that inactivate Rho family-GTPases to disrupt host cellular function and cause fluid secretion, inflammation, and cell death. Toxicity depends on receptor binding and subsequent endocytosis. TcdB has been shown to enter cells by clathrin-dependent endocytosis, but the mechanism of TcdA uptake is still unclear. Here, we utilize a combination of RNAi-based knockdown, pharmacological inhibition, and cell imaging approaches to investigate the endocytic mechanism(s) that contribute to TcdA uptake and subsequent cytopathic and cytotoxic effects. We show that TcdA uptake and cellular intoxication is dynamin-dependent but does not involve clathrin- or caveolae-mediated endocytosis. Confocal microscopy using fluorescently labeled TcdA shows significant colocalization of the toxin with PACSIN2-positive structures in cells during entry. Disruption of PACSIN2 function by RNAi-based knockdown approaches inhibits TcdA uptake and toxin-induced downstream effects in cells indicating that TcdA entry is PACSIN2-dependent. We conclude that TcdA and TcdB utilize distinct endocytic mechanisms to intoxicate host cells. Clostridium difficile is a bacterial pathogen that causes nearly half a million infections each year in the United States. It infects the human colon and causes diarrhea, colitis and, in some cases, death. C. difficile infection is mediated by the action of two large homologous toxins, TcdA and TcdB. Disruption of host cell function by these toxins requires entry into cells. There are multiple ways for pathogens and virulence factors such as viruses and toxins to enter host cells. The entry mechanism is often directed by a cell surface receptor and can impact the trafficking and virulence properties of the pathogenic factor. Investigating the internalization strategy can provide critical insight into the mechanism of action for specific pathogens and virulence factors. In our current study, we sought to determine the strategy utilized by TcdA to enter host cells. We show that TcdA uptake occurs by a clathrin- and caveolae-independent endocytic mechanism that is mediated by PACSIN2 and dynamin. We also show that TcdA and TcdB can utilize different routes of entry, which may have implications regarding their cytotoxic mechanisms. In summary, our results provide new insights into the mechanism of cellular intoxication by TcdA and the role of PACSIN2 in endocytosis.
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Affiliation(s)
- Ramyavardhanee Chandrasekaran
- Department of Pathology, Microbiology and Immunology, Vanderbilt University School of Medicine, Nashville, TN, United States of America
| | - Anne K. Kenworthy
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN, United States of America
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, TN, United States of America
- Epithelial Biology Program, Vanderbilt University School of Medicine, Nashville, TN, United States of America
| | - D. Borden Lacy
- Department of Pathology, Microbiology and Immunology, Vanderbilt University School of Medicine, Nashville, TN, United States of America
- Epithelial Biology Program, Vanderbilt University School of Medicine, Nashville, TN, United States of America
- The Veterans Affairs Tennessee Valley Healthcare System, Nashville, TN, United States of America
- * E-mail:
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27
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Clostridium difficile Toxins TcdA and TcdB Cause Colonic Tissue Damage by Distinct Mechanisms. Infect Immun 2016; 84:2871-7. [PMID: 27456833 PMCID: PMC5038081 DOI: 10.1128/iai.00583-16] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2016] [Accepted: 07/19/2016] [Indexed: 02/04/2023] Open
Abstract
As the major cause of antibiotic-associated diarrhea, Clostridium difficile is a serious problem in health care facilities worldwide. C. difficile produces two large toxins, TcdA and TcdB, which are the primary virulence factors in disease. The respective functions of these toxins have been difficult to discern, in part because the cytotoxicity profiles for these toxins differ with concentration and cell type. The goal of this study was to develop a cell culture model that would allow a side-by-side mechanistic comparison of the toxins. Conditionally immortalized, young adult mouse colonic (YAMC) epithelial cells demonstrate an exquisite sensitivity to both toxins with phenotypes that agree with observations in tissue explants. TcdA intoxication results in an apoptotic cell death that is dependent on the glucosyltransferase activity of the toxin. In contrast, TcdB has a bimodal mechanism; it induces apoptosis in a glucosyltransferase-dependent manner at lower concentrations and glucosyltransferase-independent necrotic death at higher concentrations. The direct comparison of the responses to TcdA and TcdB in cells and colonic explants provides the opportunity to unify a large body of observations made by many independent investigators.
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Di Bella S, Ascenzi P, Siarakas S, Petrosillo N, di Masi A. Clostridium difficile Toxins A and B: Insights into Pathogenic Properties and Extraintestinal Effects. Toxins (Basel) 2016; 8:E134. [PMID: 27153087 PMCID: PMC4885049 DOI: 10.3390/toxins8050134] [Citation(s) in RCA: 147] [Impact Index Per Article: 18.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2016] [Revised: 04/22/2016] [Accepted: 04/25/2016] [Indexed: 02/06/2023] Open
Abstract
Clostridium difficile infection (CDI) has significant clinical impact especially on the elderly and/or immunocompromised patients. The pathogenicity of Clostridium difficile is mainly mediated by two exotoxins: toxin A (TcdA) and toxin B (TcdB). These toxins primarily disrupt the cytoskeletal structure and the tight junctions of target cells causing cell rounding and ultimately cell death. Detectable C. difficile toxemia is strongly associated with fulminant disease. However, besides the well-known intestinal damage, recent animal and in vitro studies have suggested a more far-reaching role for these toxins activity including cardiac, renal, and neurologic impairment. The creation of C. difficile strains with mutations in the genes encoding toxin A and B indicate that toxin B plays a major role in overall CDI pathogenesis. Novel insights, such as the role of a regulator protein (TcdE) on toxin production and binding interactions between albumin and C. difficile toxins, have recently been discovered and will be described. Our review focuses on the toxin-mediated pathogenic processes of CDI with an emphasis on recent studies.
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Affiliation(s)
- Stefano Di Bella
- 2nd Infectious Diseases Division, National Institute for Infectious Diseases "L. Spallanzani", Rome 00149, Italy.
| | - Paolo Ascenzi
- Department of Science, Roma Tre University, Rome 00154, Italy.
| | - Steven Siarakas
- Department of Microbiology and Infectious Diseases, Concord Repatriation General Hospital, Sydney 2139, Australia.
| | - Nicola Petrosillo
- 2nd Infectious Diseases Division, National Institute for Infectious Diseases "L. Spallanzani", Rome 00149, Italy.
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29
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Zhang Y, Feng H. Pathogenic effects of glucosyltransferase from Clostridium difficile toxins. Pathog Dis 2016; 74:ftw024. [PMID: 27044305 DOI: 10.1093/femspd/ftw024] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/30/2016] [Indexed: 01/13/2023] Open
Abstract
The glucosyltransferase domain ofClostridium difficiletoxins modifies guanine nucleotide-binding proteins of Rho family. It is the major virulent domain of the holotoxins. Various pathogenic effects ofC. difficiletoxins in response to Rho glucosylation have been investigated including cytoskeleton damage, cell death and inflammation. The most recent studies have revealed some significant characteristics of the holotoxins that are independent of glucosylating activity. These findings arouse discussion about the role of glucosyltransferase activity in toxin pathogenesis and open up new insights for toxin mechanism study. In this review, we summarize the pathogenic effects of glucosyltransferase domain of the toxins in the past years.
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Affiliation(s)
- Yongrong Zhang
- Department of Microbial Pathogenesis, University of Maryland Baltimore, 650 W. Baltimore Street, Baltimore, MD 21201, USA
| | - Hanping Feng
- Department of Microbial Pathogenesis, University of Maryland Baltimore, 650 W. Baltimore Street, Baltimore, MD 21201, USA
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30
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Sensitive assays enable detection of serum IgG antibodies against Clostridium difficile toxin A and toxin B in healthy subjects and patients with Clostridium difficile infection. Bioanalysis 2016; 8:611-23. [PMID: 26964649 DOI: 10.4155/bio-2015-0033] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
BACKGROUND Pathogenic Clostridium difficile produces two proinflammatory exotoxins, toxin A and toxin B. Low level of serum antitoxin IgG antibodies is a risk factor for the development of primary and recurrent C. difficile infection (CDI). RESULTS We developed and validated two sensitive, titer-based electrochemiluminescence assays for the detection of serum antibody levels against C. difficile toxins A and B. These assays demonstrated excellent precision. The sensitivity of the assays allowed the detection of antitoxin A and antitoxin B IgG antibodies in all tested serum samples during assay validation. CONCLUSION The validated titer-based assays enable assessment of antitoxin A and antitoxin B IgG antibodies as potential biomarkers to identify patients with CDI at increased risk for CDI recurrence.
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31
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Frädrich C, Beer LA, Gerhard R. Reactive Oxygen Species as Additional Determinants for Cytotoxicity of Clostridium difficile Toxins A and B. Toxins (Basel) 2016; 8:toxins8010025. [PMID: 26797634 PMCID: PMC4728547 DOI: 10.3390/toxins8010025] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2015] [Revised: 01/07/2016] [Accepted: 01/13/2016] [Indexed: 12/18/2022] Open
Abstract
Clostridium difficile infections can induce mild to severe diarrhoea and the often associated characteristic pseudomembranous colitis. Two protein toxins, the large glucosyltransferases TcdA and TcdB, are the main pathogenicity factors that can induce all clinical symptoms in animal models. The classical molecular mode of action of these homologous toxins is the inhibition of Rho GTPases by mono-glucosylation. Rho-inhibition leads to breakdown of the actin cytoskeleton, induces stress-activated and pro-inflammatory signaling and eventually results in apoptosis of the affected cells. An increasing number of reports, however, have documented further qualities of TcdA and TcdB, including the production of reactive oxygen species (ROS) by target cells. This review summarizes observations dealing with the production of ROS induced by TcdA and TcdB, dissects pathways that contribute to this phenomenon and speculates about ROS in mediating pathogenesis. In conclusion, ROS have to be considered as a discrete, glucosyltransferase-independent quality of at least TcdB, triggered by different mechanisms.
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Affiliation(s)
- Claudia Frädrich
- Postgraduate Course for Toxicology and Environmental Toxicology, Institute for Legal Medicine, University of Leipzig, Johannisallee 28, Leipzig 04103, Germany.
| | - Lara-Antonia Beer
- Institute of Toxicology, Hannover Medical School, Carl-Neuberg-Str. 1, Hannover 30625, Germany.
| | - Ralf Gerhard
- Postgraduate Course for Toxicology and Environmental Toxicology, Institute for Legal Medicine, University of Leipzig, Johannisallee 28, Leipzig 04103, Germany.
- Institute of Toxicology, Hannover Medical School, Carl-Neuberg-Str. 1, Hannover 30625, Germany.
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32
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Identification of an epithelial cell receptor responsible for Clostridium difficile TcdB-induced cytotoxicity. Proc Natl Acad Sci U S A 2015; 112:7073-8. [PMID: 26038560 DOI: 10.1073/pnas.1500791112] [Citation(s) in RCA: 126] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Clostridium difficile is the leading cause of hospital-acquired diarrhea in the United States. The two main virulence factors of C. difficile are the large toxins, TcdA and TcdB, which enter colonic epithelial cells and cause fluid secretion, inflammation, and cell death. Using a gene-trap insertional mutagenesis screen, we identified poliovirus receptor-like 3 (PVRL3) as a cellular factor necessary for TcdB-mediated cytotoxicity. Disruption of PVRL3 expression by gene-trap mutagenesis, shRNA, or CRISPR/Cas9 mutagenesis resulted in resistance of cells to TcdB. Complementation of the gene-trap or CRISPR mutants with PVRL3 resulted in restoration of TcdB-mediated cell death. Purified PVRL3 ectodomain bound to TcdB by pull-down. Pretreatment of cells with a monoclonal antibody against PVRL3 or prebinding TcdB to PVRL3 ectodomain also inhibited cytotoxicity in cell culture. The receptor is highly expressed on the surface epithelium of the human colon and was observed to colocalize with TcdB in both an explant model and in tissue from a patient with pseudomembranous colitis. These data suggest PVRL3 is a physiologically relevant binding partner that can serve as a target for the prevention of TcdB-induced cytotoxicity in C. difficile infection.
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Critical roles of Clostridium difficile toxin B enzymatic activities in pathogenesis. Infect Immun 2014; 83:502-13. [PMID: 25404023 DOI: 10.1128/iai.02316-14] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
TcdB is one of the key virulence factors of Clostridium difficile that is responsible for causing serious and potentially fatal colitis. The toxin contains at least two enzymatic domains: an effector glucosyltransferase domain for inactivating host Rho GTPases and a cysteine protease domain for the delivery of the effector domain into host cytosol. Here, we describe a novel intrabody approach to examine the role of these enzymes of TcdB in cellular intoxication. By screening a single-domain heavy chain (V(H)H) library raised against TcdB, we identified two V(H)H antibodies, 7F and E3, that specifically inhibit TcdB cysteine protease and glucosyltransferase activities, respectively. Cytoplasmic expression of 7F intrabody in Vero cells inhibited TcdB autoprocessing and delayed cellular intoxication, whereas E3 intrabody completely blocked the cytopathic effects of TcdB holotoxin. These data also demonstrate for the first time that toxin autoprocessing occurs after cysteine protease and glucosyltransferase domains translocate into the cytosol of target cells. We further determined the role of the enzymatic activities of TcdB in in vivo toxicity using a sensitive systemic challenge model in mice. Consistent with these in vitro results, a cysteine protease noncleavable mutant, TcdB-L543A, delayed toxicity in mice, whereas glycosyltransferase-deficient TcdB demonstrated no toxicity up to 500-fold of the 50% lethal dose (LD50) when it was injected systemically. Thus, glucosyltransferase but not cysteine protease activity is critical for TcdB-mediated cytopathic effects and TcdB systemic toxicity, highlighting the importance of targeting toxin glucosyltransferase activity for future therapy.
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Sun C, Wang H, Chen S, Li Z, Li S, Wang J. Recombinant Clostridium difficile toxin B induces endoplasmic reticulum stress in mouse colonal carcinoma cells. Acta Biochim Biophys Sin (Shanghai) 2014; 46:973-81. [PMID: 25274332 DOI: 10.1093/abbs/gmu091] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
Clostridium difficile is the main cause of antibiotic-associated diarrhea and pseudomembranous colitis in humans and animals. Its pathogenicity is primarily linked to the secretion of two exotoxins (TcdA and TcdB). Although great progress in the toxic mechanism of TcdA and TcdB has been achieved, there are many conflicting reports about the apoptotic mechanism. More importantly, apoptotic endoplasmic reticulum (ER) stress has been reported in cells treated with Shiga toxins-another kind of cytotoxins that can cause diarrhea and colitis. Herein we checked whether TcdB can induce ER stress. The results showed that recombinant TcdB (rTcdB) activated molecular markers of unfolded protein response, suggesting that rTcdB induced ER stress in CT26 cells. However, rTcdB did not induce the up-regulation of C/EBP homologous protein (CHOP), a classic mediator of apoptotic ER stress, but it activated the precursor of cysteine aspartic acid-specific protease 12 (caspase-12), a controversial mediator of apoptotic ER stress. Besides, glucosyltransferase activity-deficient mutant recombinant TcdB induced ER stress, though it has no cytotoxic or cytopathic effect on CT26 cells. Altogether, these data demonstrated that ER stress induced by rTcdB is glucosyltransferase-independent, indicating that ER stress induced by rTcdB is non-apoptotic. This work also offers us a new insight into the molecular mechanism of CHOP protein expression regulation and the role of CHOP expression in ER stress.
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Affiliation(s)
- Chunli Sun
- School of Bioscience and Bioengineering, South China University of Technology, Guangzhou 510006, China
| | - Haiying Wang
- School of Light Industry and Food Sciences, South China University of Technology, Guangzhou 510006, China
| | - Shuyi Chen
- School of Bioscience and Bioengineering, South China University of Technology, Guangzhou 510006, China
| | - Zhendong Li
- School of Bioscience and Bioengineering, South China University of Technology, Guangzhou 510006, China
| | - Shan Li
- School of Bioscience and Bioengineering, South China University of Technology, Guangzhou 510006, China School of Light Industry and Food Sciences, South China University of Technology, Guangzhou 510006, China
| | - Jufang Wang
- School of Bioscience and Bioengineering, South China University of Technology, Guangzhou 510006, China
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Huang T, Li S, Li G, Tian Y, Wang H, Shi L, Perez-Cordon G, Mao L, Wang X, Wang J, Feng H. Utility of Clostridium difficile toxin B for inducing anti-tumor immunity. PLoS One 2014; 9:e110826. [PMID: 25340750 PMCID: PMC4207755 DOI: 10.1371/journal.pone.0110826] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2014] [Accepted: 08/01/2014] [Indexed: 12/22/2022] Open
Abstract
Clostridium difficile toxin B (TcdB) is a key virulence factor of bacterium and induces intestinal inflammatory disease. Because of its potent cytotoxic and proinflammatory activities, we investigated the utility of TcdB in developing anti-tumor immunity. TcdB induced cell death in mouse colorectal cancer CT26 cells, and the intoxicated cells stimulated the activation of mouse bone marrow-derived dendritic cells and subsequent T cell activation in vitro. Immunization of BALB/c mice with toxin-treated CT26 cells elicited potent anti-tumor immunity that protected mice from a lethal challenge of the same tumor cells and rejected pre-injected tumors. The anti-tumor immunity generated was cell-mediated, long-term, and tumor-specific. Further experiments demonstrated that the intact cell bodies were important for the immunogenicity since lysing the toxin-treated tumor cells reduced their ability to induce antitumor immunity. Finally, we showed that TcdB is able to induce potent anti-tumor immunity in B16-F10 melanoma model. Taken together, these data demonstrate the utility of C. difficile toxin B for developing anti-tumor immunity.
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Affiliation(s)
- Tuxiong Huang
- School of Bioscience and Bioengineering, South China University of Technology (SCUT), Guangzhou, China
- Department of Microbial Pathogenesis, University of Maryland Dental School, Baltimore, Maryland, United States of America
| | - Shan Li
- School of Bioscience and Bioengineering, South China University of Technology (SCUT), Guangzhou, China
- Department of Microbial Pathogenesis, University of Maryland Dental School, Baltimore, Maryland, United States of America
| | - Guangchao Li
- School of Bioscience and Bioengineering, South China University of Technology (SCUT), Guangzhou, China
| | - Yuan Tian
- School of Bioscience and Bioengineering, South China University of Technology (SCUT), Guangzhou, China
| | - Haiying Wang
- School of Bioscience and Bioengineering, South China University of Technology (SCUT), Guangzhou, China
| | - Lianfa Shi
- Department of Microbial Pathogenesis, University of Maryland Dental School, Baltimore, Maryland, United States of America
| | - Gregorio Perez-Cordon
- Department of Microbial Pathogenesis, University of Maryland Dental School, Baltimore, Maryland, United States of America
| | - Li Mao
- Department of Oncology and Diagnostics, University of Maryland Dental School, Baltimore, Maryland, United States of America
| | - Xiaoning Wang
- Institute of Life Science, General Hospital of the People’s Liberation Army, Beijing, China
| | - Jufang Wang
- School of Bioscience and Bioengineering, South China University of Technology (SCUT), Guangzhou, China
- * E-mail: (JW); (HF)
| | - Hanping Feng
- Department of Microbial Pathogenesis, University of Maryland Dental School, Baltimore, Maryland, United States of America
- * E-mail: (JW); (HF)
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Screening of potent antibacterial agents targeting Clostridium difficile virulence factor toxin B: an in silico approach. Med Chem Res 2014. [DOI: 10.1007/s00044-014-1017-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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The P2Y6 receptor mediates Clostridium difficile toxin-induced CXCL8/IL-8 production and intestinal epithelial barrier dysfunction. PLoS One 2013; 8:e81491. [PMID: 24278446 PMCID: PMC3838400 DOI: 10.1371/journal.pone.0081491] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2013] [Accepted: 10/14/2013] [Indexed: 02/06/2023] Open
Abstract
C. difficile is a Gram-positive spore-forming anaerobic bacterium that is the leading cause of nosocomial diarrhea in the developed world. The pathogenesis of C. difficile infections (CDI) is driven by toxin A (TcdA) and toxin B (TcdB), secreted factors that trigger the release of inflammatory mediators and contribute to disruption of the intestinal epithelial barrier. Neutrophils play a key role in the inflammatory response and the induction of pseudomembranous colitis in CDI. TcdA and TcdB alter cytoskeletal signaling and trigger the release of CXCL8/IL-8, a potent neutrophil chemoattractant, from intestinal epithelial cells; however, little is known about the surface receptor(s) that mediate these events. In the current study, we sought to assess whether toxin-induced CXCL8/IL-8 release and barrier dysfunction are driven by the activation of the P2Y6 receptor following the release of UDP, a danger signal, from intoxicated Caco-2 cells. Caco-2 cells express a functional P2Y6 receptor and release measurable amounts of UDP upon exposure to TcdA/B. Toxin-induced CXCL8/IL-8 production and release were attenuated in the presence of a selective P2Y6 inhibitor (MRS2578). This was associated with inhibition of TcdA/B-induced activation of NFκB. Blockade of the P2Y6 receptor also attenuated toxin-induced barrier dysfunction in polarized Caco-2 cells. Lastly, pretreating mice with the P2Y6 receptor antagonists (MSR2578) attenuated TcdA/B-induced inflammation and intestinal permeability in an intrarectal toxin exposure model. Taken together these data outline a novel role for the P2Y6 receptor in the induction of CXCL8/IL-8 production and barrier dysfunction in response to C. difficile toxin exposure and may provide a new therapeutic target for the treatment of CDI.
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Caspase activation as a versatile assay platform for detection of cytotoxic bacterial toxins. J Clin Microbiol 2013; 51:2970-6. [PMID: 23824772 DOI: 10.1128/jcm.01161-13] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Pathogenic bacteria produce several virulence factors that help them establish infection in permissive hosts. Bacterial toxins are a major class of virulence factors and hence are attractive therapeutic targets for vaccine development. Here, we describe the development of a rapid, sensitive, and high-throughput assay that can be used as a versatile platform to measure the activities of bacterial toxins. We have exploited the ability of these toxins to cause cell death via apoptosis of sensitive cultured cell lines as a readout for measuring toxin activity. Caspases (cysteine-aspartic proteases) are induced early in the apoptotic pathway, and so we used their induction to measure the activities of Clostridium difficile toxins A (TcdA) and B (TcdB) and binary toxin (CDTa-CDTb), Corynebacterium diphtheriae toxin (DT), and Pseudomonas aeruginosa exotoxin A (PEA). Caspase induction in the cell lines, upon exposure to toxins, was optimized by toxin concentration and intoxication time, and the specificity of caspase activity was established using a genetically mutated toxin and a pan-caspase inhibitor. In addition, we demonstrate the utility of the caspase assay for measuring toxin potency, as well as neutralizing antibody (NAb) activity against C. difficile toxins. Furthermore, the caspase assay showed excellent correlation with the filamentous actin (F-actin) polymerization assay for measuring TcdA and TcdB neutralization titers upon vaccination of hamsters. These results demonstrate that the detection of caspase induction due to toxin exposure using a chemiluminescence readout can support potency and clinical immunogenicity testing for bacterial toxin vaccine candidates in development.
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Zhang Y, Shi L, Li S, Yang Z, Standley C, Yang Z, ZhuGe R, Savidge T, Wang X, Feng H. A segment of 97 amino acids within the translocation domain of Clostridium difficile toxin B is essential for toxicity. PLoS One 2013; 8:e58634. [PMID: 23484044 PMCID: PMC3590123 DOI: 10.1371/journal.pone.0058634] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2012] [Accepted: 02/05/2013] [Indexed: 01/27/2023] Open
Abstract
Clostridium difficile toxin B (TcdB) intoxicates target cells by glucosylating Rho GTPases. TcdB (269 kDa) consists of at least 4 functional domains including a glucosyltransferase domain (GTD), a cysteine protease domain (CPD), a translocation domain (TD), and a receptor binding domain (RBD). The function and molecular mode of action of the TD, which is the largest segment of TcdB and comprises nearly 50% of the protein, remain largely unknown. Here we show that a 97-amino-acid segment (AA1756 – 1852, designated as ?97 or D97), located in the C-terminus of the TD and adjacent to the RBD, is essential for the cellular activity of TcdB. Deletion of this segment in TcdB (designated as TxB-D97), did not adversely alter toxin enzymatic activities or its cellular binding and uptake capacity. TxB-D97 bound to and entered cells in a manner similar to TcdB holotoxin. Both wild type and mutant toxins released their GTDs similarly in the presence of inositol hexakisphosphate (InsP6), and showed a similar glucosyltransferase activity in a cell-free glucosylating assay. Despite these similarities, the cytotoxic activity of TxB-D97 was reduced by more than 5 logs compared to wild type toxin, supported by the inability of TxB-D97 to glucosylate Rac1 of target cells. Moreover, the mutant toxin failed to elicit tumor necrosis factor alpha (TNF-α) in macrophages, a process dependent on the glucosyltransferase activity of the toxin. Cellular fractionation of toxin-exposed cells revealed that TxB-D97 was unable to efficiently release the GTD into cytosol. Thereby, we conclude the 97-amino-acid region of the TD C-terminus of TcdB adjacent to the RBD, is essential for the toxicity of TcdB.
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Affiliation(s)
- Yongrong Zhang
- School of Bioengineering, East China University of Science and Technology, Shanghai, China
| | - Lianfa Shi
- Department of Microbial Pathogenesis, University of Maryland Dental School, Baltimore, Maryland, United States of America
| | - Shan Li
- Department of Microbial Pathogenesis, University of Maryland Dental School, Baltimore, Maryland, United States of America
| | - Zhiyong Yang
- Department of Microbial Pathogenesis, University of Maryland Dental School, Baltimore, Maryland, United States of America
| | - Clive Standley
- University of Massachusetts Medical School, Worcester, Massachusetts, United States of America
| | - Zhong Yang
- School of Bioengineering, East China University of Science and Technology, Shanghai, China
| | - Ronghua ZhuGe
- University of Massachusetts Medical School, Worcester, Massachusetts, United States of America
| | - Tor Savidge
- Baylor College of Medicine, Houston, Texas, United States of America
| | - Xiaoning Wang
- School of Bioengineering, East China University of Science and Technology, Shanghai, China
| | - Hanping Feng
- Department of Microbial Pathogenesis, University of Maryland Dental School, Baltimore, Maryland, United States of America
- * E-mail:
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Rodrigues RS, Oliveira RAC, Li Y, Zaja-Milatovic S, Costa LB, Braga Neto MB, Kolling GL, Lima AA, Guerrant RL, Warren CA. Intestinal epithelial restitution after TcdB challenge and recovery from Clostridium difficile infection in mice with alanyl-glutamine treatment. J Infect Dis 2013; 207:1505-15. [PMID: 23359592 DOI: 10.1093/infdis/jit041] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
BACKGROUND Clostridium difficile is an anaerobic bacterium that causes antibiotic-associated diarrhea. It produces toxin A and toxin B (TcdB), which cause injury to the gut epithelium. Glutamine is a fundamental fuel for enterocytes, maintaining intestinal mucosal health. Alanyl-glutamine (AQ) is a highly soluble dipeptide derivative of glutamine. We studied whether administration of AQ ameliorates the effects of TcdB in the intestinal cells and improves the outcome of C. difficile infection in mice. METHODS WST-1 proliferation and cell-wounding-migration assays were assessed in IEC-6 cells exposed to TcdB, with or without AQ. Apoptosis and necrosis were assessed using Annexin V and flow cytometry. C57BL/6 mice were infected with VPI 10463 and treated with either vancomycin, AQ, or vancomycin with AQ. Intestinal tissues were collected for histopathologic analysis, apoptosis staining, and determination of myeloperoxidase activity. RESULTS AQ increased proliferation in intestinal cells exposed to TcdB, improved migration at 24 and 48 hours, and reduced apoptosis in intestinal cells challenged with TcdB. Infected mice treated with vancomycin and AQ had better survival and histopathologic findings than mice treated with vancomycin alone. CONCLUSIONS AQ may reduce intestinal mucosal injury in C. difficile-infected mice by partially reversing the effects of TcdB on enterocyte proliferation, migration, and apoptosis, thereby improving survival from C. difficile infection.
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Li S, Shi L, Yang Z, Feng H. Cytotoxicity of Clostridium difficile toxin B does not require cysteine protease-mediated autocleavage and release of the glucosyltransferase domain into the host cell cytosol. Pathog Dis 2013; 67:11-8. [PMID: 23620115 DOI: 10.1111/2049-632x.12016] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2012] [Revised: 11/26/2012] [Accepted: 11/29/2012] [Indexed: 01/05/2023] Open
Abstract
Clostridium difficile virulence requires secretion of two exotoxins: TcdA and TcdB. The precise mechanism of toxin uptake and delivery is undefined, but current models predict that the cysteine protease domain (CPD)-mediated autocleavage and release of glucosyltransferase domain (GTD) are crucial for intoxication. To determine the importance of CPD-mediated cleavage to TcdB cytotoxicity, we generated two mutant toxins--TcdB-C698S and TcdB-H653A--and assayed their abilities to intoxicate cells. The CPD mutants include an intact GTD but lack the cysteine protease activity. The mutants had reduced potency in that their effect on cells was delayed and required higher concentrations than wild-type TcdB. They did eventually cause cell rounding, glucosylation of Rho GTPases, and apoptosis that was indistinguishable from that caused by TcdB. Although the mutant toxins caused a complete cell rounding, they failed to release their GTD into cytosol, whereas wild-type TcdB displayed significant autocleavage and release of GTD. We conclude that the cysteine protease-mediated autocleavage and release of GTD is not a prerequisite for the cytotoxic activity of TcdB, but rather limits the potency and speed of Rho GTPase glucosylation. Our findings revise and refine the current model for the mode of the action and cellular trafficking of TcdB.
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Affiliation(s)
- Shan Li
- Department of Microbial Pathogenesis, University of Maryland Dental School, Baltimore, MD 21201, USA
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Chumbler NM, Farrow MA, Lapierre LA, Franklin JL, Haslam D, Goldenring JR, Lacy DB. Clostridium difficile Toxin B causes epithelial cell necrosis through an autoprocessing-independent mechanism. PLoS Pathog 2012; 8:e1003072. [PMID: 23236283 PMCID: PMC3516567 DOI: 10.1371/journal.ppat.1003072] [Citation(s) in RCA: 91] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2012] [Accepted: 10/22/2012] [Indexed: 01/21/2023] Open
Abstract
Clostridium difficile is the most common cause of antibiotic-associated nosocomial infection in the United States. C. difficile secretes two homologous toxins, TcdA and TcdB, which are responsible for the symptoms of C. difficile associated disease. The mechanism of toxin action includes an autoprocessing event where a cysteine protease domain (CPD) releases a glucosyltransferase domain (GTD) into the cytosol. The GTD acts to modify and inactivate Rho-family GTPases. The presumed importance of autoprocessing in toxicity, and the apparent specificity of the CPD active site make it, potentially, an attractive target for small molecule drug discovery. In the course of exploring this potential, we have discovered that both wild-type TcdB and TcdB mutants with impaired autoprocessing or glucosyltransferase activities are able to induce rapid, necrotic cell death in HeLa and Caco-2 epithelial cell lines. The concentrations required to induce this phenotype correlate with pathology in a porcine colonic explant model of epithelial damage. We conclude that autoprocessing and GTD release is not required for epithelial cell necrosis and that targeting the autoprocessing activity of TcdB for the development of novel therapeutics will not prevent the colonic tissue damage that occurs in C. difficile – associated disease. Clostridium difficile is an anaerobic spore-forming bacterium that infects the human colon and causes diarrhea, pseudomembranous colitis, and toxic megacolon. Most people that develop disease symptoms have undergone antibiotic treatment, which alters the normal gut flora and allows C. difficile to flourish. C. difficile secretes two toxins, TcdA and TcdB, that are responsible for the fluid secretion, inflammation, and colonic tissue damage associated with disease. The emergence of hypervirulent strains of C. difficile that are linked to increased morbidity and mortality highlights the need for new therapeutic strategies. One strategy is to inhibit the function of the toxins, thereby decreasing damage to the colon while the patient clears the infection with antibiotics. Toxin function is thought to depend on an autoprocessing event that releases a catalytic ‘effector’ portion of the toxin into the host cell. In the course of trying to identify small molecules that would inhibit such a function, we found that TcdB induces a rapid necrosis in epithelial cells that is not dependent on autoprocessing. The physiological relevance of this observation is confirmed in colonic explants and suggests that inhibiting TcdB autoprocessing will not prevent the colonic tissue damage observed in C. difficile associated diseases.
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Affiliation(s)
- Nicole M. Chumbler
- Chemical and Physical Biology Program, Vanderbilt University School of Medicine, Nashville, Tennessee, United States of America
| | - Melissa A. Farrow
- Department of Pathology, Microbiology and Immunology, Vanderbilt University School of Medicine, Nashville, Tennessee, United States of America
| | - Lynne A. Lapierre
- Department of Surgery, Vanderbilt University School of Medicine, Nashville, Tennessee, United States of America
| | - Jeffrey L. Franklin
- Department of Medicine, Vanderbilt University School of Medicine, Nashville, Tennessee, United States of America
- Department of Cell and Developmental Biology and the Epithelial Biology Center, Vanderbilt University School of Medicine, Nashville, Tennessee, United States of America
| | - David Haslam
- Department of Pediatrics, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - James R. Goldenring
- Department of Surgery, Vanderbilt University School of Medicine, Nashville, Tennessee, United States of America
- Department of Cell and Developmental Biology and the Epithelial Biology Center, Vanderbilt University School of Medicine, Nashville, Tennessee, United States of America
| | - D. Borden Lacy
- Department of Pathology, Microbiology and Immunology, Vanderbilt University School of Medicine, Nashville, Tennessee, United States of America
- * E-mail:
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Tomar N, De RK. Modeling host-pathogen interactions: H. sapiens as a host and C. difficile as a pathogen. J Mol Recognit 2012; 25:474-85. [DOI: 10.1002/jmr.2211] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Namrata Tomar
- Machine Intelligence Unit; Indian Statistical Institute; 203 B.T. Road; Kolkata; 700108; India
| | - Rajat K. De
- Machine Intelligence Unit; Indian Statistical Institute; 203 B.T. Road; Kolkata; 700108; India
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Köberle M, Göppel D, Grandl T, Gaentzsch P, Manncke B, Berchtold S, Müller S, Lüscher B, Asselin-Labat ML, Pallardy M, Sorg I, Langer S, Barth H, Zumbihl R, Autenrieth IB, Bohn E. Yersinia enterocolitica YopT and Clostridium difficile toxin B induce expression of GILZ in epithelial cells. PLoS One 2012; 7:e40730. [PMID: 22792400 PMCID: PMC3392236 DOI: 10.1371/journal.pone.0040730] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2011] [Accepted: 06/14/2012] [Indexed: 12/14/2022] Open
Abstract
Glucocorticoid induced-leucine zipper (GILZ) has been shown to be induced in cells by different stimuli such as glucocorticoids, IL-10 or deprivation of IL-2. GILZ has anti-inflammatory properties and may be involved in signalling modulating apoptosis. Herein we demonstrate that wildtype Yersinia enterocolitica which carry the pYV plasmid upregulated GILZ mRNA levels and protein expression in epithelial cells. Infection of HeLa cells with different Yersinia mutant strains revealed that the protease activity of YopT, which cleaves the membrane-bound form of Rho GTPases was sufficient to induce GILZ expression. Similarly, Clostridium difficile toxin B, another bacterial inhibitor of Rho GTPases induced GILZ expression. YopT and toxin B both increased transcriptional activity of the GILZ promoter in HeLa cells. GILZ expression could not be linked to the inactivation of an individual Rho GTPase by these toxins. However, forced expression of RhoA and RhoB decreased basal GILZ promoter activity. Furthermore, MAPK activation proved necessary for profound GILZ induction by toxin B. Promoter studies and gel shift analyses defined binding of upstream stimulatory factor (USF) 1 and 2 to a canonical c-Myc binding site (E-box) in the GILZ promoter as a crucial step of its trans-activation. In addition we could show that USF-1 and USF-2 are essential for basal as well as toxin B induced GILZ expression. These findings define a novel way of GILZ promoter trans-activation mediated by bacterial toxins and differentiate it from those mediated by dexamethasone or deprivation of IL-2.
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Affiliation(s)
- Martin Köberle
- Interfaculty Institute of Microbiology and Infection Medicine, Eberhard Karls University of Tübingen, Tübingen, Germany
- Dermatology, Eberhard Karls University of Tübingen, Tübingen, Germany
| | - David Göppel
- Interfaculty Institute of Microbiology and Infection Medicine, Eberhard Karls University of Tübingen, Tübingen, Germany
| | - Tanja Grandl
- Interfaculty Institute of Microbiology and Infection Medicine, Eberhard Karls University of Tübingen, Tübingen, Germany
| | - Peer Gaentzsch
- Interfaculty Institute of Microbiology and Infection Medicine, Eberhard Karls University of Tübingen, Tübingen, Germany
| | - Birgit Manncke
- Interfaculty Institute of Microbiology and Infection Medicine, Eberhard Karls University of Tübingen, Tübingen, Germany
| | - Susanne Berchtold
- Interfaculty Institute of Microbiology and Infection Medicine, Eberhard Karls University of Tübingen, Tübingen, Germany
| | - Steffen Müller
- Interfaculty Institute of Microbiology and Infection Medicine, Eberhard Karls University of Tübingen, Tübingen, Germany
| | - Bernhard Lüscher
- Institut für Biochemie und Molekularbiologie, Universitätsklinikum RWTH Aachen, Aachen, Germany
| | - Marie-Liesse Asselin-Labat
- Universud, NSERM UMR-S 996, Faculte de Pharmacie Paris-Sud, Chatenay-Malabry, France
- The Walter and Eliza Hall Institute of Medical Research, Parkville, Melbourne, Australia
| | - Marc Pallardy
- Universud, NSERM UMR-S 996, Faculte de Pharmacie Paris-Sud, Chatenay-Malabry, France
| | - Isabel Sorg
- Biozentrum der Universität Basel, Basel, Switzerland
| | - Simon Langer
- Institute of Pharmacology and Toxicology, University of Ulm Medical Center, Ulm, Germany
| | - Holger Barth
- Institute of Pharmacology and Toxicology, University of Ulm Medical Center, Ulm, Germany
| | - Robert Zumbihl
- INRA, UMR1333, Laboratoire Diversité, Génomes et Interactions Microorganismes Insectes, Montpellier, France
- Université de Montpellier 2, Montpellier, France
| | - Ingo B. Autenrieth
- Interfaculty Institute of Microbiology and Infection Medicine, Eberhard Karls University of Tübingen, Tübingen, Germany
| | - Erwin Bohn
- Interfaculty Institute of Microbiology and Infection Medicine, Eberhard Karls University of Tübingen, Tübingen, Germany
- * E-mail:
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Pruitt RN, Lacy DB. Toward a structural understanding of Clostridium difficile toxins A and B. Front Cell Infect Microbiol 2012; 2:28. [PMID: 22919620 PMCID: PMC3417631 DOI: 10.3389/fcimb.2012.00028] [Citation(s) in RCA: 120] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2012] [Accepted: 02/27/2012] [Indexed: 12/17/2022] Open
Abstract
Clostridium difficile is a toxin-producing bacterium that is a frequent cause of hospital-acquired and antibiotic-associated diarrhea. The incidence, severity, and costs associated with C. difficile associated disease are substantial and increasing, making C. difficile a significant public health concern. The two primary toxins, TcdA and TcdB, disrupt host cell function by inactivating small GTPases that regulate the actin cytoskeleton. This review will discuss the role of these two toxins in pathogenesis and the structural and molecular mechanisms by which they intoxicate cells. A focus will be placed on recent publications highlighting mechanistic similarities and differences between TcdA, TcdB, and different TcdB variants.
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Affiliation(s)
- Rory N Pruitt
- Department of Pathology, Microbiology and Immunology, Vanderbilt University School of Medicine, Nashville TN, USA
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46
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Shen A. Clostridium difficile toxins: mediators of inflammation. J Innate Immun 2012; 4:149-58. [PMID: 22237401 DOI: 10.1159/000332946] [Citation(s) in RCA: 124] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2011] [Accepted: 09/06/2011] [Indexed: 12/18/2022] Open
Abstract
Clostridium difficile is a significant problem in hospital settings as the most common cause of nosocomial diarrhea worldwide. C. difficile infections (CDIs) are characterized by an acute intestinal inflammatory response with neutrophil infiltration. These symptoms are primarily caused by the glucosylating toxins, TcdA and TcdB. In the past decade, the frequency and severity of CDIs have increased markedly due to the emergence of so-called hypervirulent strains that overproduce cytotoxic glucosylating toxins relative to historical strains. In addition, these strains produce a third toxin, binary toxin or C. difficile transferase (CDT), that may contribute to hypervirulence. Both the glucosylating toxins and CDT covalently modify target cell proteins to cause disassembly of the actin cytoskeleton and induce severe inflammation. This review summarizes our current knowledge of the mechanisms by which glucosylating toxins and CDT disrupt target cell function, alter host physiology and stimulate immune responses.
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Affiliation(s)
- Aimee Shen
- Department of Microbiology and Molecular Genetics, University of Vermont, Burlington, Vt. 05401, USA.
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D'Auria KM, Donato GM, Gray MC, Kolling GL, Warren CA, Cave LM, Solga MD, Lannigan JA, Papin JA, Hewlett EL. Systems analysis of the transcriptional response of human ileocecal epithelial cells to Clostridium difficile toxins and effects on cell cycle control. BMC SYSTEMS BIOLOGY 2012; 6:2. [PMID: 22225989 PMCID: PMC3266197 DOI: 10.1186/1752-0509-6-2] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/16/2011] [Accepted: 01/06/2012] [Indexed: 12/12/2022]
Abstract
Background Toxins A and B (TcdA and TcdB) are Clostridium difficile's principal virulence factors, yet the pathways by which they lead to inflammation and severe diarrhea remain unclear. Also, the relative role of either toxin during infection and the differences in their effects across cell lines is still poorly understood. To better understand their effects in a susceptible cell line, we analyzed the transciptome-wide gene expression response of human ileocecal epithelial cells (HCT-8) after 2, 6, and 24 hr of toxin exposure. Results We show that toxins elicit very similar changes in the gene expression of HCT-8 cells, with the TcdB response occurring sooner. The high similarity suggests differences between toxins are due to events beyond transcription of a single cell-type and that their relative potencies during infection may depend on differential effects across cell types within the intestine. We next performed an enrichment analysis to determine biological functions associated with changes in transcription. Differentially expressed genes were associated with response to external stimuli and apoptotic mechanisms and, at 24 hr, were predominately associated with cell-cycle control and DNA replication. To validate our systems approach, we subsequently verified a novel G1/S and known G2/M cell-cycle block and increased apoptosis as predicted from our enrichment analysis. Conclusions This study shows a successful example of a workflow deriving novel biological insight from transcriptome-wide gene expression. Importantly, we do not find any significant difference between TcdA and TcdB besides potency or kinetics. The role of each toxin in the inhibition of cell growth and proliferation, an important function of cells in the intestinal epithelium, is characterized.
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Affiliation(s)
- Kevin M D'Auria
- Department of Biomedical Engineering, University of Virginia, Charlottesville, Virginia 22908, USA
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Rational design of inhibitors and activity-based probes targeting Clostridium difficile virulence factor TcdB. ACTA ACUST UNITED AC 2011; 17:1201-11. [PMID: 21095570 DOI: 10.1016/j.chembiol.2010.09.011] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2010] [Revised: 09/30/2010] [Accepted: 09/30/2010] [Indexed: 01/05/2023]
Abstract
Clostridium difficile is a leading cause of nosocomial infections. The major virulence factors of this pathogen are the multi-domain toxins TcdA and TcdB. These toxins contain a cysteine protease domain (CPD) that autoproteolytically releases a cytotoxic effector domain upon binding intracellular inositol hexakisphosphate. Currently, there are no known inhibitors of this protease. Here, we describe the rational design of covalent small molecule inhibitors of TcdB CPD. We identified compounds that inactivate TcdB holotoxin function in cells and solved the structure of inhibitor-bound protease to 2.0 Å. This structure reveals the molecular basis of CPD substrate recognition and informed the synthesis of activity-based probes for this enzyme. The inhibitors presented will guide the development of therapeutics targeting C. difficile, and the probes will serve as tools for studying the unique activation mechanism of bacterial toxin CPDs.
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Difference in the biological effects of Clostridium difficile toxin B in proliferating and non-proliferating cells. Naunyn Schmiedebergs Arch Pharmacol 2011; 383:275-83. [PMID: 21212934 DOI: 10.1007/s00210-010-0595-5] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2010] [Accepted: 12/21/2010] [Indexed: 02/07/2023]
Abstract
Toxin A (TcdA) and toxin B (TcdB) from Clostridium difficile are the causative agents of the C. difficile-associated diarrhea (CDAD) and its severe form, the pseudomembranous colitis. TcdA and TcdB both glucosylate and thereby inactivate low molecular weight GTP-binding proteins of the Rho, Rac, and Cdc42 subfamilies. In cultured cell lines, TcdB induces actin re-organization and bi-nucleation ("cytopathic effects") and cell death ("cytotoxic effects"). In this study, the role of cell cycle progression in the cytopathic and the cytotoxic effects of TcdB is evaluated by a differential analysis of these effects in proliferating and non-proliferating cells. Density-synchronized murine fibroblasts and confluent HT29 colonocytes are exploited as cell culture models for non-proliferating cells. Cell death is analyzed in terms of a loss of cell viability, phosphatidylserine exposure, and DNA fragmentation. In proliferating cells, TcdB blocks cell proliferation and induces apoptotic cell death. In contrast, TcdB induces non-apoptotic cell death in non-proliferating cells. TcdB-induced cell rounding turns out to be independent of cell cycle progression. Cell cycle progression is an important determinant in the biological effects of TcdB. With respect to the pathology of CDAD, this study leads to the new hypothesis that necrotic cell death of terminally differentiated colonocytes and inhibition of epithelial renewal of the colon contribute to the pathogenesis of CDAD.
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50
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Sun X, Savidge T, Feng H. The enterotoxicity of Clostridium difficile toxins. Toxins (Basel) 2010; 2:1848-80. [PMID: 22069662 PMCID: PMC3153265 DOI: 10.3390/toxins2071848] [Citation(s) in RCA: 74] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2010] [Revised: 06/23/2010] [Accepted: 07/09/2010] [Indexed: 02/06/2023] Open
Abstract
The major virulence factors of Clostridium difficile infection (CDI) are two large exotoxins A (TcdA) and B (TcdB). However, our understanding of the specific roles of these toxins in CDI is still evolving. It is now accepted that both toxins are enterotoxic and proinflammatory in the human intestine. Both purified TcdA and TcdB are capable of inducing the pathophysiology of CDI, although most studies have focused on TcdA. C. difficile toxins exert a wide array of biological activities by acting directly on intestinal epithelial cells. Alternatively, the toxins may target immune cells and neurons once the intestinal epithelial barrier is disrupted. The toxins may also act indirectly by stimulating cells to produce chemokines, proinflammatory cytokines, neuropeptides and other neuroimmune signals. This review considers the mechanisms of TcdA- and TcdB-induced enterotoxicity, and recent developments in this field.
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Affiliation(s)
- Xingmin Sun
- Tufts Cummings School of Veterinary Medicine, North Grafton, MA, 01536, USA;
| | - Tor Savidge
- The University of Texas Medical Branch, Galveston, TX, 77555, USA;
| | - Hanping Feng
- Tufts Cummings School of Veterinary Medicine, North Grafton, MA, 01536, USA;
- Author to whom correspondence should be addressed; ; Tel.: +1-508-887-4252; Fax: +1-508-839-7911
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