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Gandhi S, Puravankara S, Mondal AK, Chauhan A, Yadav SP, Chattopadhyay K, Mukhopadhaya A. Vibrio cholerae cytolysin induces pro-inflammatory and death signals through novel TLR assembly. PLoS Pathog 2025; 21:e1013033. [PMID: 40184418 PMCID: PMC12002540 DOI: 10.1371/journal.ppat.1013033] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2024] [Revised: 04/16/2025] [Accepted: 03/10/2025] [Indexed: 04/06/2025] Open
Abstract
Vibrio cholerae cytolysin (VCC) is a potent exotoxin secreted by Vibrio cholerae, the etiological agent of the severe diarrheal disease cholera. VCC is a membrane-damaging pore-forming toxin by nature, and is well known for its ability to cause host cell death. Using wild type V. cholerae and VCC-deleted mutant variant of the bacteria, we show that VCC plays an important role in the inflammatory responses during infection in mice. This observation supports that VCC can function as a pathogen-associated molecular pattern (PAMP). Toll-like receptors (TLRs) are the key initiators of inflammation. Upon ligand recognition, TLR1 and TLR6 generally form heterodimers with TLR2 for triggering pro-inflammatory signals. In the present study, we show that VCC engages novel TLR1/4 heterodimer assembly, and elicits pro-inflammatory responses in both dendritic cells (DCs) and macrophages. Along with TLR1/4, VCC-induced pro-inflammatory response in macrophages also involves TLR2. It has been shown earlier that VCC is implicated in the V. cholerae-mediated killing of the immune cells following biofilm formation. Here we show that TLRs play an important role in VCC-mediated killing of DCs and macrophages following V. cholerae infection. Interestingly, we find that TLR1/4 signalling is specifically crucial for the VCC-induced inflammatory and death responses in DCs, as well as in mice. Additionally, we observe that similar to DCs and macrophages, TLR1/4-MyD88 play an important role in VCC-mediated inflammatory responses in another crucial immune cell type, neutrophils. Taken together, our study shows novel TLR heterodimer formation, differential recognition of the same ligand by different TLR combination in cell type-dependent manner, and their implications in the context of V. cholerae and VCC-induced immune cell death and mortality.
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Affiliation(s)
- Shraddha Gandhi
- Department of Biological Sciences, Indian Institute of Science Education and Research Mohali, Mohali, Punjab, India
| | - Sindhoora Puravankara
- Department of Biological Sciences, Indian Institute of Science Education and Research Mohali, Mohali, Punjab, India
| | - Anish Kumar Mondal
- Department of Biological Sciences, Indian Institute of Science Education and Research Mohali, Mohali, Punjab, India
| | - Aakanksha Chauhan
- Department of Biological Sciences, Indian Institute of Science Education and Research Mohali, Mohali, Punjab, India
| | - Shashi Prakash Yadav
- Department of Biological Sciences, Indian Institute of Science Education and Research Mohali, Mohali, Punjab, India
| | - Kausik Chattopadhyay
- Department of Biological Sciences, Indian Institute of Science Education and Research Mohali, Mohali, Punjab, India
| | - Arunika Mukhopadhaya
- Department of Biological Sciences, Indian Institute of Science Education and Research Mohali, Mohali, Punjab, India
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Escartín-Gutiérrez JR, Ponce-Figueroa M, Torres-Vega MÁ, Aguilar-Faisal L, Figueroa-Arredondo P. Transcriptional Activation of a Pro-Inflammatory Response (NF-κB, AP-1, IL-1β) by the Vibrio cholerae Cytotoxin (VCC) Monomer through the MAPK Signaling Pathway in the THP-1 Human Macrophage Cell Line. Int J Mol Sci 2023; 24:ijms24087272. [PMID: 37108435 PMCID: PMC10139130 DOI: 10.3390/ijms24087272] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2023] [Revised: 03/23/2023] [Accepted: 04/02/2023] [Indexed: 04/29/2023] Open
Abstract
This study describes, to some extent, the VCC contribution as an early stimulation of the macrophage lineage. Regarding the onset of the innate immune response caused by infection, the β form of IL-1 is the most important interleukin involved in the onset of the inflammatory innate response. Activated macrophages treated in vitro with VCC induced the activation of the MAPK signaling pathway in a one-hour period, with the activation of transcriptional regulators for a surviving and pro-inflammatory response, suggesting an explanation inspired and supported by the inflammasome physiology. The mechanism of IL-1β production induced by VCC has been gracefully outlined in murine models, using bacterial knockdown mutants and purified molecules; nevertheless, the knowledge of this mechanism in the human immune system is still under study. This work shows the soluble form of 65 kDa of the Vibrio cholerae cytotoxin (also known as hemolysin), as it is secreted by the bacteria, inducing the production of IL-1β in the human macrophage cell line THP-1. The mechanism involves triggering the early activation of the signaling pathway MAPKs pERK and p38, with the subsequent activation of (p50) NF-κB and AP-1 (cJun and cFos), determined by real-time quantitation. The evidence shown here supports that the monomeric soluble form of the VCC in the macrophage acts as a modulator of the innate immune response, which is consistent with the assembly of the NLRP3 inflammasome actively releasing IL-1β.
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Affiliation(s)
- Julio Rodrigo Escartín-Gutiérrez
- Doctorate Program in Medical Research, Research Department, Escuela Superior de Medicina, Instituto Politécnico Nacional, Mexico City 07320, Mexico
| | - Mariana Ponce-Figueroa
- Masters in Health Sciences, Postgraduate Studies and Research Section, Escuela Superior de Medicina, Instituto Politécnico Nacional, Mexico City 07320, Mexico
| | - Miguel Ángel Torres-Vega
- Departament of Gastroenterology, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Mexico City 14080, Mexico
| | - Leopoldo Aguilar-Faisal
- Doctorate Program in Medical Research, Research Department, Escuela Superior de Medicina, Instituto Politécnico Nacional, Mexico City 07320, Mexico
- Masters in Health Sciences, Postgraduate Studies and Research Section, Escuela Superior de Medicina, Instituto Politécnico Nacional, Mexico City 07320, Mexico
| | - Paula Figueroa-Arredondo
- Doctorate Program in Medical Research, Research Department, Escuela Superior de Medicina, Instituto Politécnico Nacional, Mexico City 07320, Mexico
- Masters in Health Sciences, Postgraduate Studies and Research Section, Escuela Superior de Medicina, Instituto Politécnico Nacional, Mexico City 07320, Mexico
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Daboul J, Weghorst L, DeAngelis C, Plecha SC, Saul-McBeth J, Matson JS. Characterization of Vibrio cholerae isolates from freshwater sources in northwest Ohio. PLoS One 2020; 15:e0238438. [PMID: 32881972 PMCID: PMC7470319 DOI: 10.1371/journal.pone.0238438] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2020] [Accepted: 08/17/2020] [Indexed: 01/22/2023] Open
Abstract
Vibrio cholerae is a natural inhabitant of aquatic ecosystems worldwide, typically residing in coastal or brackish water. While more than 200 serogroups have been identified, only serogroups O1 and O139 have been associated with epidemic cholera. However, infections other than cholera can be caused by nonepidemic, non-O1/non-O139 V. cholerae strains, including gastroenteritis and extraintestinal infections. While V. cholerae can also survive in freshwater, that is typically only observed in regions of the world where cholera is endemic. We recently isolated V. cholerae from several locations in lakes and rivers in northwest Ohio. These isolates were all found to be non-O1/non-O139 V. cholerae strains, that would not cause cholera. However, these isolates contained a variety of virulence genes, including ctxA, rtxA, rtxC, hlyA, and ompU. Therefore, it is possible that some of these isolates have the potential to cause gastroenteritis or other infections in humans. We also investigated the relative motility of the isolates and their ability to form biofilms as this is important for V. cholerae survival in the environment. We identified one isolate that forms very robust biofilms, up to 4x that of our laboratory strains. Finally, we investigated the susceptibility of these isolates to a panel of antibiotics. We found that many of the isolates showed decreased susceptibility to some of the antibiotics tested, which could be of concern. While we do not know if these isolates are pathogenic to humans, increased surveillance to better understand the public health risk to the local community should be considered.
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Affiliation(s)
- Judy Daboul
- Department of Medical Microbiology and Immunology, University of Toledo, Toledo, Ohio, United States of America
| | - Logan Weghorst
- Department of Medical Microbiology and Immunology, University of Toledo, Toledo, Ohio, United States of America
| | - Cara DeAngelis
- Department of Medical Microbiology and Immunology, University of Toledo, Toledo, Ohio, United States of America
| | - Sarah C. Plecha
- Department of Medical Microbiology and Immunology, University of Toledo, Toledo, Ohio, United States of America
| | - Jessica Saul-McBeth
- Department of Medical Microbiology and Immunology, University of Toledo, Toledo, Ohio, United States of America
| | - Jyl S. Matson
- Department of Medical Microbiology and Immunology, University of Toledo, Toledo, Ohio, United States of America
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Che R, Ding S, Zhang Q, Yang W, Yan J, Lin X. Haemolysin Sph2 of Leptospira interrogans induces cell apoptosis via intracellular reactive oxygen species elevation and mitochondrial membrane injury. Cell Microbiol 2018; 21:e12959. [PMID: 30278102 DOI: 10.1111/cmi.12959] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2017] [Revised: 09/18/2018] [Accepted: 09/19/2018] [Indexed: 12/13/2022]
Abstract
Leptospira interrogans causes widespread leptospirosis in humans and animals, with major symptoms of jaundice and haemorrhage. Sph2, a member of the sphingomyelinase haemolysins, is an important virulence factor for leptospire. In this study, the function and mechanism of Sph2 in the pathogenesis of leptospirosis were investigated to further understand the pathogenesis of leptospire. Real-time PCR analysis of expression levels during cell invasion showed that sph2 gene expression was transiently induced in human umbilical vein endothelial cells (HUVECs), human embryo liver cells (L02), and human epithelial lung cells (L132), with expression levels reaching a peak after 45 min of infection. Further functional analysis of recombinant Sph2 (rSph2) by LDH assays and confocal microscopy showed that rSph2 can be internalised by cells both by causing cell membrane damage and by a damage-independent clathrin-mediated endocytosis pathway. Subsequently, rSph2 is able to translocate to mitochondria, which led to an increase in the levels of reactive oxygen species (ROS) and a decrease of the mitochondrial membrane potential (ΔΨm ). Further flowcytometry analyses after rSph2 exposure showed that 28.7%, 31%, and 27.3% of the HUVEC, L02, and L132 cells, respectively, became apoptotic. Because apoptosis could be decreased with the ROS inhibitor N-acetyl cysteine, these experiments suggested that rSph2 triggers apoptosis through mitochondrial membrane damage and ROS elevation. The ability of leptospiral haemolysin rSph2 to cause apoptosis likely contributes to the pathogenesis of leptospirosis.
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Affiliation(s)
- Rongbo Che
- Department of Medical Microbiology and Parasitology, School of Medicine, Zhejiang University, Hangzhou, China
| | - Shibiao Ding
- Department of Medical Microbiology and Parasitology, School of Medicine, Zhejiang University, Hangzhou, China.,Department of Clinical Laboratory, Hospital of integrated traditional Chinese and Western, Hangzhou, China
| | - Qinchao Zhang
- Department of Medical Microbiology and Parasitology, School of Medicine, Zhejiang University, Hangzhou, China
| | - Weiqun Yang
- Department of Medical Microbiology and Parasitology, School of Medicine, Zhejiang University, Hangzhou, China
| | - Jie Yan
- Department of Medical Microbiology and Parasitology, School of Medicine, Zhejiang University, Hangzhou, China.,Basic Medical Microbiology Division, State Key Laboratory for Diagnosis and Treatment of Infectious Diseases, School of Medicine, Zhejiang University, Hangzhou, China
| | - Xu'ai Lin
- Department of Medical Microbiology and Parasitology, School of Medicine, Zhejiang University, Hangzhou, China.,Basic Medical Microbiology Division, State Key Laboratory for Diagnosis and Treatment of Infectious Diseases, School of Medicine, Zhejiang University, Hangzhou, China
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Yap WY, Hwang JS. Response of Cellular Innate Immunity to Cnidarian Pore-Forming Toxins. Molecules 2018; 23:E2537. [PMID: 30287801 PMCID: PMC6222686 DOI: 10.3390/molecules23102537] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2018] [Revised: 09/24/2018] [Accepted: 09/28/2018] [Indexed: 12/11/2022] Open
Abstract
A group of stable, water-soluble and membrane-bound proteins constitute the pore forming toxins (PFTs) in cnidarians. They interact with membranes to physically alter the membrane structure and permeability, resulting in the formation of pores. These lesions on the plasma membrane causes an imbalance of cellular ionic gradients, resulting in swelling of the cell and eventually its rupture. Of all cnidarian PFTs, actinoporins are by far the best studied subgroup with established knowledge of their molecular structure and their mode of pore-forming action. However, the current view of necrotic action by actinoporins may not be the only mechanism that induces cell death since there is increasing evidence showing that pore-forming toxins can induce either necrosis or apoptosis in a cell-type, receptor and dose-dependent manner. In this review, we focus on the response of the cellular immune system to the cnidarian pore-forming toxins and the signaling pathways that might be involved in these cellular responses. Since PFTs represent potential candidates for targeted toxin therapy for the treatment of numerous cancers, we also address the challenge to overcoming the immunogenicity of these toxins when used as therapeutics.
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Affiliation(s)
- Wei Yuen Yap
- Department of Biological Sciences, School of Science and Technology, Sunway University, No. 5 Jalan Universiti, Bandar Sunway, Selangor Darul Ehsan 47500, Malaysia.
| | - Jung Shan Hwang
- Department of Medical Sciences, School of Healthcare and Medical Sciences, Sunway University, No. 5 Jalan Universiti, Bandar Sunway, Selangor Darul Ehsan 47500, Malaysia.
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Castro-Alarcón N, Rodríguez-García R, Ruíz-Rosas M, Muñoz-Valle JF, Guzmán-Guzmán IP, Parra-Rojas I, Vázquez-Villamar M. Association between TLR4 polymorphisms (896 A>G, 1196 C>T, - 2570 A>G, - 2081 G>A) and virulence factors in uropathogenic Escherichia coli. Clin Exp Med 2018; 19:105-113. [PMID: 30220001 DOI: 10.1007/s10238-018-0527-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2018] [Accepted: 09/06/2018] [Indexed: 12/29/2022]
Abstract
Escherichia coli is the main etiological agent of urinary tract infections. Its virulence factors are important during the initial interaction stage with the host as they enable colonization of urinary tract tissues. The genetic markers evidencing susceptibility to develop recurrent infections have been previously described. Toll-like receptors are critical sensors of microbial attacks, and they are also effectors of the individual's innate defense for elimination of pathogens. The aim of this study was to evaluate the association between functional polymorphisms (896 A>G, 1196 C>T, - 2570 A>G, - 2081 G>A) and susceptibility to develop urinary tract infections as well as E. coli virulence factors. This study includes 100 samples from patients diagnosed with UTI and 100 samples from uninfected subjects. A conventional urine culture was performed and the isolates were identified by using the Vitek automated system. TLR4 gene polymorphisms were identified by the PCR-RFLP technique. The hlyA, fimH, papC, iutA and cnf1 virulence factors as well as the E. coli phylogenetic group were assessed by PCR. In this study, it was observed that the presence of the - 2570 polymorphism represents a risk of UTI (p < 0.01), whereas - 2081 confers protection (p < 0.01). The 896A>G and 1196C>T polymorphisms were associated with the E. coli virulence factors fimH and hlyA, respectively (p < 0.05). The B2 group was the most frequent in clinical isolates (51%), and it displayed more virulence factors regarding other phylogenetic groups (p ≤ 0.05). An interesting finding was that strains considered as commensals, belonging to groups A and B1, can cause UTI and present virulence factors. Polymorphisms occurring in the TLR4 promoter region are correlated with susceptibility or risk of UTI, whereas structural polymorphisms are associated with the recognition of virulence factors displayed by E. coli.
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Affiliation(s)
- Natividad Castro-Alarcón
- Facultad de Ciencias Químico Bilógicas, Universidad Autónoma de Guerrero, Lázaro Cárdenas S/N Col. La Haciendita, C.P. 39090, Chilpancingo, Guerrero, Mexico
| | - Rubén Rodríguez-García
- Facultad de Ciencias Químico Bilógicas, Universidad Autónoma de Guerrero, Lázaro Cárdenas S/N Col. La Haciendita, C.P. 39090, Chilpancingo, Guerrero, Mexico
| | - María Ruíz-Rosas
- Laboratorio Clínico, Área de Microbiología, Clínica Hospital ISSSTE, Chilpancingo, Guerrero, Mexico
| | - José Francisco Muñoz-Valle
- Instituto de Investigación en Ciencias Biomédicas, Centro Universitario de Ciencias de la Salud, Universidad de Guadalajara, Guadalajara, Jalisco, Mexico
| | - Iris Paola Guzmán-Guzmán
- Facultad de Ciencias Químico Bilógicas, Universidad Autónoma de Guerrero, Lázaro Cárdenas S/N Col. La Haciendita, C.P. 39090, Chilpancingo, Guerrero, Mexico
| | - Isela Parra-Rojas
- Facultad de Ciencias Químico Bilógicas, Universidad Autónoma de Guerrero, Lázaro Cárdenas S/N Col. La Haciendita, C.P. 39090, Chilpancingo, Guerrero, Mexico
| | - Mirna Vázquez-Villamar
- Facultad de Ciencias Químico Bilógicas, Universidad Autónoma de Guerrero, Lázaro Cárdenas S/N Col. La Haciendita, C.P. 39090, Chilpancingo, Guerrero, Mexico.
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Gao H, Xu J, Lu X, Li J, Lou J, Zhao H, Diao B, Shi Q, Zhang Y, Kan B. Expression of Hemolysin Is Regulated Under the Collective Actions of HapR, Fur, and HlyU in Vibrio cholerae El Tor Serogroup O1. Front Microbiol 2018; 9:1310. [PMID: 29971055 PMCID: PMC6018088 DOI: 10.3389/fmicb.2018.01310] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2018] [Accepted: 05/29/2018] [Indexed: 12/19/2022] Open
Abstract
The biotype El Tor of serogroup O1 and most of the non-O1/non-O139 strains of Vibrio cholerae can produce an extracellular pore-forming toxin known as cholera hemolysin (HlyA). Expression of HlyA has been previously reported to be regulated by the quorum sensing (QS) and the regulatory proteins HlyU and Fur, but lacks the direct evidence for their binding to the promoter of hlyA. In the present work, we showed that the QS regulator HapR, along with Fur and HlyU, regulates the transcription of hlyA in V. cholerae El Tor biotype. At the late mid-logarithmic growth phase, HapR binds to the three promoters of fur, hlyU, and hlyA to repress their transcription. At the early mid-logarithmic growth phase, Fur binds to the promoters of hlyU and hlyA to repress their transcription; meanwhile, HlyU binds to the promoter of hlyA to activate its transcription, but it manifests direct inhibition of its own gene. The highest transcriptional level of hlyA occurs at an OD600 value of around 0.6–0.7, which may be due to the subtle regulation of HapR, Fur, and HlyU. The complex regulation of HapR, Fur, and HlyU on hlyA would be beneficial to the invasion and pathogenesis of V. cholerae during the different infection stages.
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Affiliation(s)
- He Gao
- State Key Laboratory of Infectious Disease Prevention and Control, National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing, China
| | - Jialiang Xu
- Key Laboratory of Cleaner Production and Integrated Resource Utilization of China National Light Industry, School of Food and Chemical Engineering, Beijing Technology and Business University, Beijing, China
| | - Xin Lu
- State Key Laboratory of Infectious Disease Prevention and Control, National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing, China
| | - Jie Li
- State Key Laboratory of Infectious Disease Prevention and Control, National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing, China
| | - Jing Lou
- State Key Laboratory of Infectious Disease Prevention and Control, National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing, China
| | - Hongqun Zhao
- State Key Laboratory of Infectious Disease Prevention and Control, National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing, China
| | - Baowei Diao
- State Key Laboratory of Infectious Disease Prevention and Control, National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing, China
| | - Qiannan Shi
- State Key Laboratory of Infectious Disease Prevention and Control, National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing, China
| | - Yiquan Zhang
- School of Medicine, Jiangsu University, Zhenjiang, China
| | - Biao Kan
- State Key Laboratory of Infectious Disease Prevention and Control, National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing, China
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Analysis of the Human Mucosal Response to Cholera Reveals Sustained Activation of Innate Immune Signaling Pathways. Infect Immun 2018; 86:IAI.00594-17. [PMID: 29133347 DOI: 10.1128/iai.00594-17] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2017] [Accepted: 11/03/2017] [Indexed: 12/16/2022] Open
Abstract
To better understand the innate immune response to Vibrio cholerae infection, we tracked gene expression in the duodenal mucosa of 11 Bangladeshi adults with cholera, using biopsy specimens obtained immediately after rehydration and 30 and 180 days later. We identified differentially expressed genes and performed an analysis to predict differentially regulated pathways and upstream regulators. During acute cholera, there was a broad increase in the expression of genes associated with innate immunity, including activation of the NF-κB, mitogen-activated protein kinase (MAPK), and Toll-like receptor (TLR)-mediated signaling pathways, which, unexpectedly, persisted even 30 days after infection. Focusing on early differences in gene expression, we identified 37 genes that were differentially expressed on days 2 and 30 across the 11 participants. These genes included the endosomal Toll-like receptor gene TLR8, which was expressed in lamina propria cells. Underscoring a potential role for endosomal TLR-mediated signaling in vivo, our pathway analysis found that interferon regulatory factor 7 and beta 1 and alpha 2 interferons were among the top upstream regulators activated during cholera. Among the innate immune effectors, we found that the gene for DUOX2, an NADPH oxidase involved in the maintenance of intestinal homeostasis, was upregulated in intestinal epithelial cells during cholera. Notably, the observed increases in DUOX2 and TLR8 expression were also modeled in vitro when Caco-2 or THP-1 cells, respectively, were stimulated with live V. cholerae but not with heat-killed organisms or cholera toxin alone. These previously unidentified features of the innate immune response to V. cholerae extend our understanding of the mucosal immune signaling pathways and effectors activated in vivo following cholera.
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Ou L, Lin S, Song B, Liu J, Lai R, Shao L. The mechanisms of graphene-based materials-induced programmed cell death: a review of apoptosis, autophagy, and programmed necrosis. Int J Nanomedicine 2017; 12:6633-6646. [PMID: 28924347 PMCID: PMC5595361 DOI: 10.2147/ijn.s140526] [Citation(s) in RCA: 144] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Graphene-based materials (GBMs) are widely used in many fields, including biomedicine. To date, much attention had been paid to the potential unexpected toxic effects of GBMs. Here, we review the recent literature regarding the impact of GBMs on programmed cell death (PCD). Apoptosis, autophagy, and programmed necrosis are three major PCDs. Mechanistic studies demonstrated that the mitochondrial pathways and MAPKs (JNK, ERK, and p38)- and TGF-β-related signaling pathways are implicated in GBMs-induced apoptosis. Autophagy, unlike apoptosis and necroptosis which are already clear cell death types, plays a vital pro-survival role in cell homeostasis, so its role in cell death should be carefully considered. However, GBMs always induce unrestrained autophagy accelerating cell death. GBMs trigger autophagy through inducing autophagosome accumulation and lysosome impairment. Mitochondrial dysfunction, ER stress, TLRs signaling pathways, and p38 MAPK and NF-κB pathways participate in GBMs-induced autophagy. Programmed necrosis can be activated by RIP kinases, PARP, and TLR-4 signaling in macrophages after GBMs exposure. Though apoptosis, autophagy, and necroptosis are distinguished by some characteristics, their numerous signaling pathways comprise an interconnected network and correlate with each other, such as the TLRs, p53 signaling pathways, and the Beclin-1 and Bcl-2 interaction. A better understanding of the mechanisms of PCD induced by GBMs may allow for a thorough study of the toxicology of GBMs and a more precise determination of the consequences of human exposure to GBMs. These determinations will also benefit safety assessments of the biomedical and therapeutic applications of GBMs.
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Affiliation(s)
- Lingling Ou
- Department of Stomatology, Nanfang Hospital, Southern Medical University, Guangzhou, People’s Republic of China
- Department of Stomatology, the First Affiliated Hospital of Jinan University, Guangzhou, People’s Republic of China
| | - Shaoqiang Lin
- Department of Stomatology, the First Affiliated Hospital of Jinan University, Guangzhou, People’s Republic of China
| | - Bin Song
- Department of Stomatology, Nanfang Hospital, Southern Medical University, Guangzhou, People’s Republic of China
| | - Jia Liu
- Department of Stomatology, Nanfang Hospital, Southern Medical University, Guangzhou, People’s Republic of China
| | - Renfa Lai
- Department of Stomatology, the First Affiliated Hospital of Jinan University, Guangzhou, People’s Republic of China
| | - Longquan Shao
- Department of Stomatology, Nanfang Hospital, Southern Medical University, Guangzhou, People’s Republic of China
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Mukherjee A, Ganguly S, Chatterjee NS, Banerjee KK. Vibrio cholerae hemolysin: The β-trefoil domain is required for folding to the native conformation. Biochem Biophys Rep 2016; 8:242-248. [PMID: 28955962 PMCID: PMC5614477 DOI: 10.1016/j.bbrep.2016.09.009] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2016] [Revised: 09/04/2016] [Accepted: 09/17/2016] [Indexed: 11/16/2022] Open
Abstract
Vibrio cholerae cytolysin/hemolysin (VCC) is a 65 kDa β-pore-forming toxin causing lysis and death of eukaryotic cells. Apart from the core cytolysin domain, VCC has two lectin domains with β-trefoil and β-prism folds. The β-prism domain binds to cell surface carbohydrate receptors; the role of the β-trefoil domain is unknown. Here, we show that the pro-VCC mutant without the β-trefoil domain formed aggregates highly susceptible to proteolysis, suggesting lack of a properly folded compact structure. The VCC variants with Trp532Ala or Trp534Ala mutation in the β-trefoil domain formed hemolytically inactive, protease-resistant, ring-shaped SDS-labile oligomers with diameters of ~19 nm. The Trp mutation induced a dramatic change in the global conformation of VCC, as indicated by: (a) the change in surface polarity from hydrophobic to hydrophilic; (b) movement of core Trp residues to the protein-water interface; and (c) decrease in reactivity to the anti-VCC antibody by >100-fold. In fact, the mutant VCC had little similarity to the wild toxin. However, the association constant for the carbohydrate-dependent interaction mediated by the β-prism domain decreased marginally from ~3×108 to ~5×107 M-1. We interpret the observations by proposing: (a) the β-trefoil domain is critical to the folding of the cytolysin domain to its active conformation; (b) the β-prism domain is an autonomous folding unit.
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Affiliation(s)
| | | | | | - Kalyan K. Banerjee
- Division of Biochemistry, National Institute of Cholera and Enteric Diseases, Kolkata 700 010, India
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Khilwani B, Chattopadhyay K. Signaling beyond Punching Holes: Modulation of Cellular Responses by Vibrio cholerae Cytolysin. Toxins (Basel) 2015; 7:3344-58. [PMID: 26308054 PMCID: PMC4549754 DOI: 10.3390/toxins7083344] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2015] [Revised: 08/12/2015] [Accepted: 08/14/2015] [Indexed: 01/20/2023] Open
Abstract
Pore-forming toxins (PFTs) are a distinct class of membrane-damaging cytolytic proteins that contribute significantly towards the virulence processes employed by various pathogenic bacteria. Vibrio cholerae cytolysin (VCC) is a prominent member of the beta-barrel PFT (beta-PFT) family. It is secreted by most of the pathogenic strains of the intestinal pathogen V. cholerae. Owing to its potent membrane-damaging cell-killing activity, VCC is believed to play critical roles in V. cholerae pathogenesis, particularly in those strains that lack the cholera toxin. Large numbers of studies have explored the mechanistic basis of the cell-killing activity of VCC. Consistent with the beta-PFT mode of action, VCC has been shown to act on the target cells by forming transmembrane oligomeric beta-barrel pores, thereby leading to permeabilization of the target cell membranes. Apart from the pore-formation-induced direct cell-killing action, VCC exhibits the potential to initiate a plethora of signal transduction pathways that may lead to apoptosis, or may act to enhance the cell survival/activation responses, depending on the type of target cells. In this review, we will present a concise view of our current understanding regarding the multiple aspects of these cellular responses, and their underlying signaling mechanisms, evoked by VCC.
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Affiliation(s)
- Barkha Khilwani
- Centre for Protein Science, Design and Engineering, Department of Biological Sciences Indian Institute of Science Education and Research Mohali Sector 81, S. A. S. Nagar, Manauli PO 140306, Punjab, India.
| | - Kausik Chattopadhyay
- Centre for Protein Science, Design and Engineering, Department of Biological Sciences Indian Institute of Science Education and Research Mohali Sector 81, S. A. S. Nagar, Manauli PO 140306, Punjab, India.
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Transmembrane oligomeric form of Vibrio cholerae cytolysin triggers TLR2/TLR6–dependent proinflammatory responses in monocytes and macrophages. Biochem J 2015; 466:147-61. [DOI: 10.1042/bj20140718] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
We show that the transmembrane oligomeric form of VCC evokes potent proinflammatory responses in the monocytes and macrophages of the innate immune system. VCC oligomer-induced proinflammatory responses depend critically on the TLR2/TLR6-dependent signalling pathways.
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Vibrio cholerae Cytolysin: Structure–Function Mechanism of an Atypical β-Barrel Pore-Forming Toxin. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2015; 842:109-25. [DOI: 10.1007/978-3-319-11280-0_7] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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Mukherjee S, Biswas T. Activation of TOLLIP by porin prevents TLR2-associated IFN-γ and TNF-α-induced apoptosis of intestinal epithelial cells. Cell Signal 2014; 26:2674-82. [PMID: 25152369 DOI: 10.1016/j.cellsig.2014.08.009] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2014] [Accepted: 08/15/2014] [Indexed: 11/25/2022]
Abstract
Interferon (IFN)-γ and tumor necrosis factor (TNF)-α cause chronic inflammation of the intestine leading to progression of inflammatory bowel disease (IBD), which is manifested through rapid apoptosis of the intestinal epithelial cells (iECs). Here, we show inhibition of IFN-γ and TNF-α-induced apoptosis of INT-407 cells by porin, a microbe-associated molecular pattern (MAMP) with affinity for toll-like receptor (TLR)2 and commonly present in Gram-negative bacteria. Proinflammatory cytokines induce apoptosis by activation of caspase 8 that triggers caspase 9 through Bax finally leading to activation of caspase 3, the executioner caspase. Interestingly, while IFN-γ and TNF-α promotes Bax expression, in contrast porin up-regulates anti-apoptotic Bcl-xL resulting in iEC survivability. We show elevated expression of TLR2 is a key requisite for IFN-γ and TNF-α mediated caspase 8 up-regulation that contributes to apoptosis of iECs. Down-regulation of TLR2 expression is central for checking apoptosis which is achieved by elevated level of toll-interacting protein (TOLLIP) in presence of porin. Attempts to limit IBD is in progress with anti-IFN-γ and anti-TNF-α Abs or use of IL-10. Although probiotic bacterial proteins have shown to successfully reduce IFN-γ and TNF-α mediated apoptosis, the exact mechanism of their action has remained elusive. This study identifies the underlying sequential events of transient TLR2 stimulation followed by its blocking in response to the bacterial outer membrane protein, which advocates intervention at TLR-juncture is crucial for controlling IBD.
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Affiliation(s)
- Subhadeep Mukherjee
- Division of Immunology, National Institute of Cholera and Enteric Diseases, P-33, CIT Road, Scheme-XM, Kolkata 700 010, West Bengal, India
| | - Tapas Biswas
- Division of Immunology, National Institute of Cholera and Enteric Diseases, P-33, CIT Road, Scheme-XM, Kolkata 700 010, West Bengal, India.
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Ganguly S, Mukherjee A, Mazumdar B, Ghosh AN, Banerjee KK. The β-prism lectin domain of Vibrio cholerae hemolysin promotes self-assembly of the β-pore-forming toxin by a carbohydrate-independent mechanism. J Biol Chem 2013; 289:4001-8. [PMID: 24356964 DOI: 10.1074/jbc.m113.522284] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Vibrio cholerae cytolysin/hemolysin (VCC) is an amphipathic 65-kDa β-pore-forming toxin with a C-terminal β-prism lectin domain. Because deletion or point mutation of the lectin domain seriously compromises hemolytic activity, it is thought that carbohydrate-dependent interactions play a critical role in membrane targeting of VCC. To delineate the contributions of the cytolysin and lectin domains in pore formation, we used wild-type VCC, 50-kDa VCC (VCC(50)) without the lectin domain, and mutant VCC(D617A) with no carbohydrate-binding activity. VCC and its two variants with no carbohydrate-binding activity moved to the erythrocyte stroma with apparent association constants on the order of 10(7) M(-1). However, loss of the lectin domain severely reduced the efficiency of self-association of the VCC monomer with the β-barrel heptamer in the synthetic lipid bilayer from ∼83 to 27%. Notably, inactivation of the carbohydrate-binding activity by the D617A mutation marginally reduced oligomerization to ∼77%. Oligomerization of VCC(50) was temperature-insensitive; by contrast, VCC self-assembly increased with increasing temperature, suggesting that the process is driven by entropy and opposed by enthalpy. Asialofetuin, the β1-galactosyl-terminated glycoprotein inhibitor of VCC-induced hemolysis, promoted oligomerization of 65-kDa VCC to a species that resembled the membrane-inserted heptamer in stoichiometry and morphology but had reduced global amphipathicity. In conclusion, we propose (i) that the β-prism lectin domain facilitated toxin assembly by producing entropy during relocation in the heptamer and (ii) that glycoconjugates inhibited VCC by promoting its assembly to a water-soluble, less amphipathic oligomer variant with reduced ability to penetrate the bilayer.
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Dutta S, Banerjee KK, Ghosh AN. Cryo-electron microscopy reveals the membrane insertion mechanism of V. cholerae hemolysin. J Biomol Struct Dyn 2013; 32:1434-42. [PMID: 24102290 DOI: 10.1080/07391102.2013.823564] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Vibrio cholerae hemolysin (HlyA) is a 65 kDa pore-forming toxin which causes lysis of target eukaryotic cells by forming heptameric channels in the plasma membrane. Deletion of the 15 kDa C-terminus β-prism carbohydrate-binding domain generates a 50 kDa truncated variant (HlyA50) with 1000-fold-reduced pore-forming activity. Previously, we showed by cryo-electron microscopy that the two toxin oligomers have central channels, but the 65 kDa toxin oligomer is a seven-fold symmetric structure with bowl-, ring-, and arm-like domains, whereas the 50 kDa oligomer is an asymmetric jar-like heptamer. In the present study, we determined three-dimensional(3D) structures of HlyA and HlyA50 in presence of erythrocyte stroma and observed that interaction of the 65 kDa toxin with the stroma induced a significant decrease in the height of the β-barrel oligomer with a change in conformation of the ring- and arm-like domains of HlyA. These features were absent in interaction of HlyA50 with stroma. We propose that this conformational transition is critical for membrane-insertion of the toxin.
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Affiliation(s)
- Somnath Dutta
- a Division of Electron Microscopy , National Institute of Cholera and Enteric Diseases , P-33, C.I.T. Road, Scheme-XM, Beleghata, Kolkata , 700010 , India
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