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Verma P, Chauhan A, Thakur R, Lata K, Sharma A, Chattopadhyay K, Mukhopadhaya A. Vibrio parahaemolyticus thermostable direct haemolysin induces non-classical programmed cell death despite caspase activation. Mol Microbiol 2023; 120:845-873. [PMID: 37818865 DOI: 10.1111/mmi.15180] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2023] [Revised: 09/02/2023] [Accepted: 09/25/2023] [Indexed: 10/13/2023]
Abstract
Thermostable direct haemolysin (TDH) is the key virulence factor secreted by the human gastroenteric bacterial pathogen Vibrio parahaemolyticus. TDH is a membrane-damaging pore-forming toxin. It evokes potent cytotoxicity, the mechanism of which still remains under-explored. Here, we have elucidated the mechanistic details of cell death response elicited by TDH. Employing Caco-2 intestinal epithelial cells and THP-1 monocytic cells, we show that TDH induces some of the hallmark features of apoptosis-like programmed cell death. TDH triggers caspase-3 and 7 activations in the THP-1 cells, while caspase-7 activation is observed in the Caco-2 cells. Interestingly, TDH appears to induce caspase-independent cell death. Higher XIAP level and lower Smac/Diablo level upon TDH intoxication provide plausible explanation for the functional inability of caspases in the THP-1 cells, in particular. Further exploration reveals that mitochondria play a central role in the TDH-induced cell death. TDH triggers mitochondrial damage, resulting in the release of AIF and endonuclease G, responsible for the execution of caspase-independent cell death. Among the other critical mediators of cell death, ROS is found to play an important role in the THP-1 cells, while PARP-1 appears to play a critical role in the Caco-2 cells. Altogether, our work provides critical new insights into the mechanism of cell death induction by TDH, showing a common central theme of non-classical programmed cell death. Our study also unravels the interplay of crucial molecules in the underlying signalling processes. Our findings add valuable insights into the role of TDH in the context of the host-pathogen interaction processes.
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Affiliation(s)
- Pratima Verma
- 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
| | - Reena Thakur
- Department of Biological Sciences, Indian Institute of Science Education and Research Mohali, Mohali, Punjab, India
| | - Kusum Lata
- Department of Biological Sciences, Indian Institute of Science Education and Research Mohali, Mohali, Punjab, India
| | - Arpita Sharma
- 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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2
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Characteristic Metabolic Changes in Skeletal Muscle Due to Vibrio vulnificus Infection in a Wound Infection Model. mSystems 2023; 8:e0068222. [PMID: 36939368 PMCID: PMC10153474 DOI: 10.1128/msystems.00682-22] [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: 03/21/2023] Open
Abstract
Vibrio vulnificus is a bacterium that inhabits warm seawater or brackish water environments and causes foodborne diseases and wound infections. In severe cases, V. vulnificus invades the skeletal muscle tissue, where bacterial proliferation leads to septicemia and necrotizing fasciitis with high mortality. Despite this characteristic, information on metabolic changes in tissue infected with V. vulnificus is not available. Here, we elucidated the metabolic changes in V. vulnificus-infected mouse skeletal muscle using capillary electrophoresis time-of-flight mass spectrometry (CE-TOFMS). Metabolome analysis revealed changes in muscle catabolites and energy metabolites during V. vulnificus infection. In particular, succinic acid accumulated but fumaric acid decreased in the infected muscle. However, the virulence factor deletion mutant revealed that changes in metabolites and bacterial proliferation were abolished in skeletal muscle infected with a multifunctional-autoprocessing repeats-in-toxin (MARTX) mutant. On the other hand, mice that were immunosuppressed via cyclophosphamide (CPA) treatment exhibited a similar level of bacterial counts and metabolites between the wild type and MARTX mutant. Therefore, our data indicate that V. vulnificus induces metabolic changes in mouse skeletal muscle and proliferates by using the MARTX toxin to evade the host immune system. This study indicates a new correlation between V. vulnificus infections and metabolic changes that lead to severe reactions or damage to host skeletal muscle. IMPORTANCE V. vulnificus causes necrotizing skin and soft tissue infections (NSSTIs) in severe cases, with high mortality and sign of rapid deterioration. Despite the severity of the infection, the dysfunction of the host metabolism in skeletal muscle triggered by V. vulnificus is poorly understood. In this study, by using a mouse wound infection model, we revealed characteristic changes in muscle catabolism and energy metabolism in skeletal muscle associated with bacterial proliferation in the infected tissues. Understanding such metabolic changes in V. vulnificus-infected tissue may provide crucial information to identify the mechanism via which V. vulnificus induces severe infections. Moreover, our metabolite data may be useful for the recognition, identification, or detection of V. vulnificus infections in clinical studies.
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Verma P, Chattopadhyay K. Current Perspective on the Membrane-Damaging Action of Thermostable Direct Hemolysin, an Atypical Bacterial Pore-forming Toxin. Front Mol Biosci 2021; 8:717147. [PMID: 34368235 PMCID: PMC8343067 DOI: 10.3389/fmolb.2021.717147] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2021] [Accepted: 07/12/2021] [Indexed: 11/13/2022] Open
Abstract
Thermostable direct hemolysin (TDH) is the major virulence determinant of the gastroenteric bacterial pathogen Vibrio parahaemolyticus. TDH is a membrane-damaging pore-forming toxin (PFT). TDH shares remarkable structural similarity with the actinoporin family of eukaryotic PFTs produced by the sea anemones. Unlike most of the PFTs, it exists as tetramer in solution, and such assembly state is crucial for its functionality. Although the structure of the tetrameric assembly of TDH in solution is known, membrane pore structure is not available yet. Also, the specific membrane-interaction mechanisms of TDH, and the exact role of any receptor(s) in such process, still remain unclear. In this mini review, we discuss some of the unique structural and physicochemical properties of TDH, and their implications for the membrane-damaging action of the toxin. We also present our current understanding regarding the membrane pore-formation mechanism of this atypical bacterial PFT.
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Affiliation(s)
- Pratima Verma
- Department of Biological Sciences, Indian Institute of Science Education and Research Mohali, Mohali, India
| | - Kausik Chattopadhyay
- Department of Biological Sciences, Indian Institute of Science Education and Research Mohali, Mohali, India
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Xu D, Zhao Z, Zhou Z, Lin Y, Zhang X, Zhang Y, Zhang Y, li J, Mao F, Xiao S, Ma H, Zhiming X, Yu Z. Mechanistic molecular responses of the giant clam Tridacna crocea to Vibrio coralliilyticus challenge. PLoS One 2020; 15:e0231399. [PMID: 32276269 PMCID: PMC7148125 DOI: 10.1371/journal.pone.0231399] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2019] [Accepted: 03/22/2020] [Indexed: 12/29/2022] Open
Abstract
Vibrio coralliilyticus is a pathogen of coral and mollusk, contributing to dramatic losses worldwide. In our study, we found that V. coralliilyticus challenge could directly affect adult Tridacna crocea survival; there were dead individuals appearing at 6 h post infection, and there were 45.56% and 56.78% mortality rates in challenged groups after 36 h of infection. The apoptosis rate of hemocytes was significantly increased by 1.8-fold at 6 h after V. coralliilyticus injection. To shed light on the mechanistic molecular responses of T. crocea to V. coralliilyticus infection, we used transcriptome sequencing analysis and other relevant techniques to analyze T. crocea hemocytes at 0 h, 6 h, 12 h and 24 h after V. coralliilyticus challenge. Our results revealed that the total numbers of unigenes and DEGs were 195651 and 3446, respectively. Additional details were found by KEGG pathway enrichment analysis, where DEGs were significantly enriched in immune-related signaling pathways, such as the TLR signaling pathway, and some were associated with signaling related to apoptosis. Quantitative validation results illustrated that with exposure to V. coralliilyticus, the expression of TLR pathway members, TLR, MyD88, IRAK4, TRAF6, and IкB-α, were significantly upregulated (by 22.9-, 9.6-, 4.0-, 3.6-, and 3.9-fold, respectively) at 6 h. The cytokine-related gene IL-17 exhibited an increase of 6.3-fold and 10.5-fold at 3 h and 6 h, respectively. The apoptosis-related gene IAP1 was dramatically increased by 2.99-fold at 6 h. These results indicate that adult T. crocea could initiate the TLR pathway to resist V. coralliilyticus, which promotes the release of inflammatory factors such as IL-17 and leads to the activation of a series of outcomes, such as apoptosis. The response mechanism is related to the T. crocea immunoreaction stimulated by V. coralliilyticus, providing a theoretical basis for understanding T. crocea immune response mechanisms.
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Affiliation(s)
- Duo Xu
- Key Laboratory of Tropical Marine Bio-resources and Ecology, Guangdong Provincial Key Laboratory of Applied Marine Biology, Chinese Academy of Science, South China Sea Institute of Oceanology, Guangzhou, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Zehui Zhao
- Key Laboratory of Tropical Marine Bio-resources and Ecology, Guangdong Provincial Key Laboratory of Applied Marine Biology, Chinese Academy of Science, South China Sea Institute of Oceanology, Guangzhou, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Zihua Zhou
- Key Laboratory of Tropical Marine Bio-resources and Ecology, Guangdong Provincial Key Laboratory of Applied Marine Biology, Chinese Academy of Science, South China Sea Institute of Oceanology, Guangzhou, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Yue Lin
- Key Laboratory of Tropical Marine Bio-resources and Ecology, Guangdong Provincial Key Laboratory of Applied Marine Biology, Chinese Academy of Science, South China Sea Institute of Oceanology, Guangzhou, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Xiangyu Zhang
- Key Laboratory of Tropical Marine Bio-resources and Ecology, Guangdong Provincial Key Laboratory of Applied Marine Biology, Chinese Academy of Science, South China Sea Institute of Oceanology, Guangzhou, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Yang Zhang
- Key Laboratory of Tropical Marine Bio-resources and Ecology, Guangdong Provincial Key Laboratory of Applied Marine Biology, Chinese Academy of Science, South China Sea Institute of Oceanology, Guangzhou, China
- Southern Marine Science and Engineering Guangdong Laboratory, Guangzhou, China
- Innovation Academy of South China Sea Ecology and Environmental Engineering (ISEE), Chinese Academy of Sciences, Guangzhou, China
| | - Yuehuan Zhang
- Key Laboratory of Tropical Marine Bio-resources and Ecology, Guangdong Provincial Key Laboratory of Applied Marine Biology, Chinese Academy of Science, South China Sea Institute of Oceanology, Guangzhou, China
- Southern Marine Science and Engineering Guangdong Laboratory, Guangzhou, China
- Innovation Academy of South China Sea Ecology and Environmental Engineering (ISEE), Chinese Academy of Sciences, Guangzhou, China
| | - Jun li
- Key Laboratory of Tropical Marine Bio-resources and Ecology, Guangdong Provincial Key Laboratory of Applied Marine Biology, Chinese Academy of Science, South China Sea Institute of Oceanology, Guangzhou, China
- Southern Marine Science and Engineering Guangdong Laboratory, Guangzhou, China
- Innovation Academy of South China Sea Ecology and Environmental Engineering (ISEE), Chinese Academy of Sciences, Guangzhou, China
| | - Fan Mao
- Key Laboratory of Tropical Marine Bio-resources and Ecology, Guangdong Provincial Key Laboratory of Applied Marine Biology, Chinese Academy of Science, South China Sea Institute of Oceanology, Guangzhou, China
- Southern Marine Science and Engineering Guangdong Laboratory, Guangzhou, China
- Innovation Academy of South China Sea Ecology and Environmental Engineering (ISEE), Chinese Academy of Sciences, Guangzhou, China
| | - Shu Xiao
- Key Laboratory of Tropical Marine Bio-resources and Ecology, Guangdong Provincial Key Laboratory of Applied Marine Biology, Chinese Academy of Science, South China Sea Institute of Oceanology, Guangzhou, China
- Southern Marine Science and Engineering Guangdong Laboratory, Guangzhou, China
- Innovation Academy of South China Sea Ecology and Environmental Engineering (ISEE), Chinese Academy of Sciences, Guangzhou, China
| | - Haitao Ma
- Key Laboratory of Tropical Marine Bio-resources and Ecology, Guangdong Provincial Key Laboratory of Applied Marine Biology, Chinese Academy of Science, South China Sea Institute of Oceanology, Guangzhou, China
- Southern Marine Science and Engineering Guangdong Laboratory, Guangzhou, China
- Innovation Academy of South China Sea Ecology and Environmental Engineering (ISEE), Chinese Academy of Sciences, Guangzhou, China
| | - Xiang Zhiming
- Key Laboratory of Tropical Marine Bio-resources and Ecology, Guangdong Provincial Key Laboratory of Applied Marine Biology, Chinese Academy of Science, South China Sea Institute of Oceanology, Guangzhou, China
- Southern Marine Science and Engineering Guangdong Laboratory, Guangzhou, China
- Innovation Academy of South China Sea Ecology and Environmental Engineering (ISEE), Chinese Academy of Sciences, Guangzhou, China
- * E-mail: (ZNY); (ZMX)
| | - Ziniu Yu
- Key Laboratory of Tropical Marine Bio-resources and Ecology, Guangdong Provincial Key Laboratory of Applied Marine Biology, Chinese Academy of Science, South China Sea Institute of Oceanology, Guangzhou, China
- Southern Marine Science and Engineering Guangdong Laboratory, Guangzhou, China
- Innovation Academy of South China Sea Ecology and Environmental Engineering (ISEE), Chinese Academy of Sciences, Guangzhou, China
- * E-mail: (ZNY); (ZMX)
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Yang M, Liang Y, Huang S, Zhang J, Wang J, Chen H, Ye Y, Gao X, Wu Q, Tan Z. Isolation and Characterization of the Novel Phages vB_VpS_BA3 and vB_VpS_CA8 for Lysing Vibrio parahaemolyticus. Front Microbiol 2020; 11:259. [PMID: 32153543 PMCID: PMC7047879 DOI: 10.3389/fmicb.2020.00259] [Citation(s) in RCA: 50] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2019] [Accepted: 02/04/2020] [Indexed: 01/01/2023] Open
Abstract
Accumulating evidence has indicated that the multiple drug resistant Vibrio parahaemolyticus may pose a serious threat to public health and economic concerns for humans globally. Here, two lytic bacteriophages, namely vB_VpS_BA3 and vB_VpS_CA8, were isolated from sewage collected in Guangzhou, China. Electron microscopy studies revealed both virions taxonomically belonged to the Siphoviridae family with icosahedral head and a long non-contractile tail. The double-stranded DNA genome of phage BA3 was composed of 58648 bp with a GC content of 46.30% while phage CA8 was 58480 bp with an average GC content of 46.42%. In total, 85 putative open reading frames (ORFs) were predicted in the phage BA3 genome while 84 were predicted in that of CA8. The ORFs were associated with phage structure, packing, host lysis, DNA metabolism, and additional functions. Furthermore, average nucleotide identity analysis, comparative genomic features and phylogenetic analysis revealed that BA3 and CA8 represented different isolates but novel members of the family, Siphoviridae. Regarding the host range of the 61 V. parahaemolyticus isolates, BA3 and CA8 had an infectivity of 8.2 and 36.1%, respectively. Furthermore, ∼100 plaque-forming units (pfu)/cell for phage BA3 and ∼180 pfu/cell for phage CA8 were determined to be the viral load under laboratory growth conditions. Accordingly, the phage-killing assay in vitro revealed that phage CA8 achieved approximately 3.65 log unit reductions. The present results indicate that CA8 is potentially applicable for biological control of multidrug resistant V. parahaemolyticus.
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Affiliation(s)
- Meiyan Yang
- College of Agriculture, South China Agricultural University, Guangzhou, China
- State Key Laboratory of Applied Microbiology Southern China, Guangdong Provincial Key Laboratory of Microbiology Culture Collection and Application, Guangdong Open Laboratory of Applied Microbiology, Guangdong Institute of Microbiology, Guangzhou, China
| | - Yongjian Liang
- College of Agriculture, South China Agricultural University, Guangzhou, China
- State Key Laboratory of Applied Microbiology Southern China, Guangdong Provincial Key Laboratory of Microbiology Culture Collection and Application, Guangdong Open Laboratory of Applied Microbiology, Guangdong Institute of Microbiology, Guangzhou, China
| | - Shixuan Huang
- State Key Laboratory of Applied Microbiology Southern China, Guangdong Provincial Key Laboratory of Microbiology Culture Collection and Application, Guangdong Open Laboratory of Applied Microbiology, Guangdong Institute of Microbiology, Guangzhou, China
| | - Jumei Zhang
- College of Agriculture, South China Agricultural University, Guangzhou, China
- State Key Laboratory of Applied Microbiology Southern China, Guangdong Provincial Key Laboratory of Microbiology Culture Collection and Application, Guangdong Open Laboratory of Applied Microbiology, Guangdong Institute of Microbiology, Guangzhou, China
| | - Jing Wang
- State Key Laboratory of Applied Microbiology Southern China, Guangdong Provincial Key Laboratory of Microbiology Culture Collection and Application, Guangdong Open Laboratory of Applied Microbiology, Guangdong Institute of Microbiology, Guangzhou, China
| | - Hanfang Chen
- College of Agriculture, South China Agricultural University, Guangzhou, China
- State Key Laboratory of Applied Microbiology Southern China, Guangdong Provincial Key Laboratory of Microbiology Culture Collection and Application, Guangdong Open Laboratory of Applied Microbiology, Guangdong Institute of Microbiology, Guangzhou, China
| | - Yuanming Ye
- College of Agriculture, South China Agricultural University, Guangzhou, China
- State Key Laboratory of Applied Microbiology Southern China, Guangdong Provincial Key Laboratory of Microbiology Culture Collection and Application, Guangdong Open Laboratory of Applied Microbiology, Guangdong Institute of Microbiology, Guangzhou, China
| | - Xiangyang Gao
- Guangdong Provincial Key Laboratory of Nutraceuticals and Functional Foods, College of Food Science, South China Agricultural University, Guangzhou, China
| | - Qingping Wu
- College of Agriculture, South China Agricultural University, Guangzhou, China
- State Key Laboratory of Applied Microbiology Southern China, Guangdong Provincial Key Laboratory of Microbiology Culture Collection and Application, Guangdong Open Laboratory of Applied Microbiology, Guangdong Institute of Microbiology, Guangzhou, China
| | - Zhiyuan Tan
- College of Agriculture, South China Agricultural University, Guangzhou, China
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He Y, Wang S, Zhang J, Zhang X, Sun F, He B, Liu X. Integrative and Conjugative Elements-Positive Vibrio parahaemolyticus Isolated From Aquaculture Shrimp in Jiangsu, China. Front Microbiol 2019; 10:1574. [PMID: 31379767 PMCID: PMC6657232 DOI: 10.3389/fmicb.2019.01574] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2019] [Accepted: 06/24/2019] [Indexed: 11/13/2022] Open
Abstract
The development of multidrug- and toxin-resistant bacteria as a result of increasing industrialization and sustained and intense antimicrobial use in aquaculture results in human health problems through increased incidence of food-borne illnesses. Integrative and conjugative elements (ICEs) are self-transmissible mobile genetic elements that allow bacteria to acquire complex new traits through horizontal gene transfer and encode a wide variety of genetic information, including resistance to antibiotics and heavy metals; however, there is a lack of studies of ICEs of environmental origin in Asia. Here, we determined the prevalence, genotypes, heavy metal resistance and antimicrobial susceptibility of 997 presumptive strains of Vibrio parahaemolyticus (tlh+, tdh–), a Gram-negative bacterium that causes gastrointestinal illness in humans, isolated from four species of aquaculture shrimp in Jiangsu, China. We found that 59 of the 997 isolates (5.9%) were ICE-positive, and of these, 9 isolates tested positive for all resistance genes. BLAST analysis showed that similarity for the eight strains to V. parahaemolyticus was 99%. Tracing the V. parahaemolyticus genotypes, showed no significant relevance of genotype among the antimicrobial resistance strains bearing the ICEs or not. Thus, in aquaculture, ICEs are not the major transmission mediators of resistance to antibiotics or heavy metals. We suggest future research to elucidate mechanisms that drive transmission of resistance determinants in V. parahaemolyticus.
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Affiliation(s)
- Yu He
- College of Food Biological Engineering, Xuzhou University of Technology, Xuzhou, China.,Key Construction Laboratory of Food Resources Development and the Quality Safety in Jiangsu, Xuzhou University of Technology, Xuzhou, China
| | - Shuai Wang
- College of Food Biological Engineering, Xuzhou University of Technology, Xuzhou, China.,Key Construction Laboratory of Food Resources Development and the Quality Safety in Jiangsu, Xuzhou University of Technology, Xuzhou, China
| | - Jianping Zhang
- College of Food Biological Engineering, Xuzhou University of Technology, Xuzhou, China.,Key Construction Laboratory of Food Resources Development and the Quality Safety in Jiangsu, Xuzhou University of Technology, Xuzhou, China
| | - Xueyang Zhang
- College of Environmental Engineering, Xuzhou University of Technology, Xuzhou, China
| | - Fengjiao Sun
- Logistics & Security Department, Shanghai Civil Aviation College, Shanghai, China
| | - Bin He
- Environment Monitoring Station, Zaozhuang Municipal Bureau of Ecology and Environment, Zaozhuang, China
| | - Xiao Liu
- Henan Key Laboratory of Cold Chain Food Quality and Safety Control, Zhengzhou University of Light Industry, Zhengzhou, China
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Zhang Y, Hu L, Qiu Y, Osei-Adjei G, Tang H, Zhang Y, Zhang R, Sheng X, Xu S, Yang W, Yang H, Yin Z, Yang R, Huang X, Zhou D. QsvR integrates into quorum sensing circuit to control Vibrio parahaemolyticus virulence. Environ Microbiol 2019; 21:1054-1067. [PMID: 30623553 DOI: 10.1111/1462-2920.14524] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2018] [Revised: 12/22/2018] [Accepted: 01/05/2019] [Indexed: 11/29/2022]
Abstract
Vibrio parahaemolyticus, the leading cause of seafood-associated gastroenteritis worldwide, requires the two type-III secretion systems (T3SS1 and T3SS2) and a thermostable direct hemolysin (encoded by tdh1 and tdh2) for full virulence. The tdh genes and the T3SS2 gene cluster constitute an 80 kb pathogenicity island known as Vp-PAI located on the chromosome II. Expression of T3SS1 and Vp-PAI is regulated in a quorum sensing (QS)-dependent manner but its detailed mechanisms remain unknown. Herein, we show that three factors (QS regulators AphA and OpaR and an AraC-type transcriptional regulator QsvR) form a complex regulatory network to control the expression of T3SS1 and Vp-PAI genes. At low cell density (LCD), whereas Vp-PAI expression is repressed, T3SS1 genes are induced by AphA, which directly binds (an operator region of) the exsBAD-vscBCD operon. At high cell density (HCD), the bacterium turns off T3SS1 expression by replacing AphA with OpaR, triggering the induction of Vp-PAI. Furthermore, QsvR binds to the regulatory regions of all the tested T3SS1 and Vp-PAI genes to activate their transcription at HCD. Taken together, our data highlight how multiple QS regulators contribute to the pathogenicity of V. parahaemolyticus by precisely controlling the expression of major virulence determinants during different stages of growth.
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Affiliation(s)
- Yiquan Zhang
- Department of Biochemistry, School of Medicine, Jiangsu University, Zhenjiang 212013, Jiangsu, People's Republic of China
| | - Linghui Hu
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing 100071, People's Republic of China
| | - Yue Qiu
- Department of Biochemistry, School of Medicine, Jiangsu University, Zhenjiang 212013, Jiangsu, People's Republic of China
| | - George Osei-Adjei
- Department of Biochemistry, School of Medicine, Jiangsu University, Zhenjiang 212013, Jiangsu, People's Republic of China
| | - Hao Tang
- Department of Biochemistry, School of Medicine, Jiangsu University, Zhenjiang 212013, Jiangsu, People's Republic of China
| | - Ying Zhang
- Department of Biochemistry, School of Medicine, Jiangsu University, Zhenjiang 212013, Jiangsu, People's Republic of China
| | - Rui Zhang
- Department of Biochemistry, School of Medicine, Jiangsu University, Zhenjiang 212013, Jiangsu, People's Republic of China
| | - Xiumei Sheng
- Department of Biochemistry, School of Medicine, Jiangsu University, Zhenjiang 212013, Jiangsu, People's Republic of China
| | - Shungao Xu
- Department of Biochemistry, School of Medicine, Jiangsu University, Zhenjiang 212013, Jiangsu, People's Republic of China
| | - Wenhui Yang
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing 100071, People's Republic of China
| | - Huiying Yang
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing 100071, People's Republic of China
| | - Zhe Yin
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing 100071, People's Republic of China
| | - Ruifu Yang
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing 100071, People's Republic of China
| | - Xinxiang Huang
- Department of Biochemistry, School of Medicine, Jiangsu University, Zhenjiang 212013, Jiangsu, People's Republic of China
| | - Dongsheng Zhou
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing 100071, People's Republic of China
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8
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Zhang Y, Hu L, Osei-Adjei G, Zhang Y, Yang W, Yin Z, Lu R, Sheng X, Yang R, Huang X, Zhou D. Autoregulation of ToxR and Its Regulatory Actions on Major Virulence Gene Loci in Vibrio parahaemolyticus. Front Cell Infect Microbiol 2018; 8:291. [PMID: 30234024 PMCID: PMC6135047 DOI: 10.3389/fcimb.2018.00291] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2018] [Accepted: 07/30/2018] [Indexed: 11/24/2022] Open
Abstract
Vibrio parahaemolyticus, the leading causative agent of seafood-associated gastroenteritis, harbors two major virulence gene loci T3SS1 and Vp-PAI (T3SS2 and tdh2). ToxR is a virulence regulator of vibrios. Cell density-dependent transcriptional pattern of toxR and its regulatory actions on T3SS1 and Vp-PAI have been previously reported, but the detailed regulatory mechanisms are still obscure. In the present work, we showed that the highest transcription level of toxR occurs at an OD600 = 0.2–0.4, which may be due to the subtle repression of ToxR and the quorum-sensing (QS) master regulator AphA. We also showed that ToxR is involved in regulating the mouse lethality, enterotoxicity, cytotoxicity, and hemolytic activity of V. parahaemolyticus. ToxR binds to the multiple promoter-proximal DNA regions within the T3SS1 locus to repress their transcription. In addition, ToxR occupies the multiple promoter-proximal DNA regions of Vp-PAI locus to activate their transcription. Thus, ToxR regulates the multiple virulence phenotypes via directly acting on the T3SS1 and Vp-PAI genes. Data presented here provide a deeper understanding of the regulatory patterns of ToxR in V. parahaemolyticus.
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Affiliation(s)
- Yiquan Zhang
- School of Medicine, Jiangsu University, Zhenjiang, China
| | - Lingfei Hu
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
| | | | - Ying Zhang
- School of Medicine, Jiangsu University, Zhenjiang, China
| | - Wenhui Yang
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
| | - Zhe Yin
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
| | - Renyun Lu
- School of Medicine, Jiangsu University, Zhenjiang, China
| | - Xiumei Sheng
- School of Medicine, Jiangsu University, Zhenjiang, China
| | - Ruifu Yang
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
| | - Xinxiang Huang
- School of Medicine, Jiangsu University, Zhenjiang, China
| | - Dongsheng Zhou
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
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9
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Cai Q, Zhang Y. Structure, function and regulation of the thermostable direct hemolysin (TDH) in pandemic Vibrio parahaemolyticus. Microb Pathog 2018; 123:242-245. [PMID: 30031890 DOI: 10.1016/j.micpath.2018.07.021] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2018] [Revised: 07/17/2018] [Accepted: 07/17/2018] [Indexed: 01/25/2023]
Abstract
Vibrio parahaemolyticus is a leading cause of seafood-associated bacterial gastroenteritis. The pathogen produces the thermostable direct hemolysin (TDH), which is the sole cause of the Kanagawa phenomenon (KP), a special β-type haemolysis in the Wagatsuma agar. TDH also exerts several other biological activities, the major includes lethal toxicity, cytotoxicity, and enterotoxicity. The structure and roles of TDH and the transcriptional regulation of tdh genes, are summarized in this review, which will give a better understanding of the pathogenesis of V. parahaemolyticus.
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Affiliation(s)
- Qin Cai
- The Fourth People 's Hospital of Zhenjiang, Zhenjiang, 212001, Jiangsu, PR China; School of Medicine, Jiangsu University, Zhenjiang, 212013, Jiangsu, PR China
| | - Yiquan Zhang
- School of Medicine, Jiangsu University, Zhenjiang, 212013, Jiangsu, PR China.
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Wang R, Sun L, Wang Y, Deng Y, Fang Z, Liu Y, Liu Y, Sun D, Deng Q, Gooneratne R. Growth and Hemolysin Production Behavior of Vibrio parahaemolyticus in Different Food Matrices. J Food Prot 2018; 81:246-253. [PMID: 29360402 DOI: 10.4315/0362-028x.jfp-17-308] [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: 11/11/2022]
Abstract
The growth and hemolytic activity profiles of two Vibrio parahaemolyticus strains (ATCC 17802 and ATCC 33847) in shrimp, oyster, freshwater fish, pork, chicken, and egg fried rice were investigated, and a prediction system for accurate microbial risk assessment was developed. The two V. parahaemolyticus strains displayed a similar growth and hemolysin production pattern in the foods at 37°C. Growth kinetic parameters showed that V. parahaemolyticus displayed higher maximum specific growth rate and shorter lag time values in shrimp > freshwater fish > egg fried rice> oyster > chicken > pork. Notably, there was a similar number of V. parahaemolyticus in all of these samples at the stationary phase. The hemolytic activity of V. parahaemolyticus in foods increased linearly with time ( R2 > 0.97). The rate constant ( K) of hemolytic activity was higher in shrimp, oyster, freshwater fish, and egg fried rice than in pork and chicken. Significantly higher hemolytic activity of V. parahaemolyticus was evident in egg fried rice > shrimp > freshwater fish > chicken > oyster > pork. The above-mentioned results indicate that V. parahaemolyticus could grow well regardless of the food type and that contrary to current belief, it displayed a higher hemolytic activity in some nonseafood products (freshwater fish, egg fried rice, and chicken) than in one seafood (oyster). The prediction system consisting of the growth model and hemolysin production algorithm reported here will fill a gap in predictive microbiology and improve significantly the accuracy of microbial risk assessment of V. parahaemolyticus.
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Affiliation(s)
- Rundong Wang
- 1 College of Food Science and Technology, Guangdong Ocean University, Guangdong Provincial Key Laboratory of Aquatic Product Processing and Safety, Key Laboratory of Advanced Processing of Aquatic Products of Guangdong Higher Education Institution 524088, People's Republic of China
| | - Lijun Sun
- 1 College of Food Science and Technology, Guangdong Ocean University, Guangdong Provincial Key Laboratory of Aquatic Product Processing and Safety, Key Laboratory of Advanced Processing of Aquatic Products of Guangdong Higher Education Institution 524088, People's Republic of China
| | - Yaling Wang
- 1 College of Food Science and Technology, Guangdong Ocean University, Guangdong Provincial Key Laboratory of Aquatic Product Processing and Safety, Key Laboratory of Advanced Processing of Aquatic Products of Guangdong Higher Education Institution 524088, People's Republic of China
| | - Yijia Deng
- 1 College of Food Science and Technology, Guangdong Ocean University, Guangdong Provincial Key Laboratory of Aquatic Product Processing and Safety, Key Laboratory of Advanced Processing of Aquatic Products of Guangdong Higher Education Institution 524088, People's Republic of China
| | - Zhijia Fang
- 1 College of Food Science and Technology, Guangdong Ocean University, Guangdong Provincial Key Laboratory of Aquatic Product Processing and Safety, Key Laboratory of Advanced Processing of Aquatic Products of Guangdong Higher Education Institution 524088, People's Republic of China
| | - Yang Liu
- 2 National Marine Products Quality Supervision & Inspection Center, Zhanjiang 524000, People's Republic of China; and
| | - Ying Liu
- 1 College of Food Science and Technology, Guangdong Ocean University, Guangdong Provincial Key Laboratory of Aquatic Product Processing and Safety, Key Laboratory of Advanced Processing of Aquatic Products of Guangdong Higher Education Institution 524088, People's Republic of China
| | - Dongfang Sun
- 1 College of Food Science and Technology, Guangdong Ocean University, Guangdong Provincial Key Laboratory of Aquatic Product Processing and Safety, Key Laboratory of Advanced Processing of Aquatic Products of Guangdong Higher Education Institution 524088, People's Republic of China
| | - Qi Deng
- 1 College of Food Science and Technology, Guangdong Ocean University, Guangdong Provincial Key Laboratory of Aquatic Product Processing and Safety, Key Laboratory of Advanced Processing of Aquatic Products of Guangdong Higher Education Institution 524088, People's Republic of China
| | - Ravi Gooneratne
- 3 Centre for Food Research and Innovation, Department of Wine, Food and Molecular Biosciences, Lincoln University, Lincoln 7647, Canterbury, New Zealand
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Vibrio parahaemolyticus CalR down regulates the thermostable direct hemolysin (TDH) gene transcription and thereby inhibits hemolytic activity. Gene 2017; 613:39-44. [DOI: 10.1016/j.gene.2017.03.001] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2016] [Revised: 02/10/2017] [Accepted: 03/01/2017] [Indexed: 11/20/2022]
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12
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Godoy-Vitorino F, Rodriguez-Hilario A, Alves AL, Gonçalves F, Cabrera-Colon B, Mesquita CS, Soares-Castro P, Ferreira M, Marçalo A, Vingada J, Eira C, Santos PM. The microbiome of a striped dolphin (Stenella coeruleoalba) stranded in Portugal. Res Microbiol 2016; 168:85-93. [PMID: 27615066 DOI: 10.1016/j.resmic.2016.08.004] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2016] [Revised: 07/20/2016] [Accepted: 08/23/2016] [Indexed: 11/19/2022]
Abstract
Infectious diseases with epizootic consequences have not been fully studied in marine mammals. Presently, the unprecedented depth of sequencing, made available by high-throughput approaches, allows detailed comparisons of the microbiome in health and disease. This is the first report of the striped dolphin microbiome in different body sites. Samples from one striped female edematous dolphin were acquired from a variety of body niches, including the blowhole, oral cavity, oral mucosa, tongue, stomach, intestines and genital mucosa. Detailed 16S rRNA analysis of over half a million sequences identified 235 OTUs. Beta diversity analyses indicated that microbial communities vary in structure and cluster by sample origin. Pathogenic, Gram-negative, facultative and obligate anaerobic taxa were significantly detected, including Cetobacterium, Fusobacterium and Ureaplasma. Phocoenobacter and Arcobacter dominated the oral-type samples, while Cardiobacteriaceae and Vibrio were associated with the blowhole and Photobacterium were abundant in the gut. We report for the first time the association of Epulopiscium with a marine mammal gut. The striped dolphin microbiota shows variation in structure and diversity according to the organ type. The high dominance of Gram-negative anaerobic pathogens evidences a cetacean microbiome affected by human-related bacteria.
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Affiliation(s)
- Filipa Godoy-Vitorino
- Microbial Ecology and Genomics Lab, Department of Natural Sciences, Inter American University of Puerto Rico, Metropolitan Campus, P.O. Box 191293, 00919-1293 San Juan, Puerto Rico.
| | - Arnold Rodriguez-Hilario
- Microbial Ecology and Genomics Lab, Department of Natural Sciences, Inter American University of Puerto Rico, Metropolitan Campus, P.O. Box 191293, 00919-1293 San Juan, Puerto Rico.
| | - Ana Luísa Alves
- Department of Biology and Centre for Molecular and Environmental Biology (CBMA), University of Minho, Campus de Gualtar, 4710-087 Braga, Portugal.
| | - Filipa Gonçalves
- Department of Biology and Centre for Molecular and Environmental Biology (CBMA), University of Minho, Campus de Gualtar, 4710-087 Braga, Portugal.
| | - Beatriz Cabrera-Colon
- Microbial Ecology and Genomics Lab, Department of Natural Sciences, Inter American University of Puerto Rico, Metropolitan Campus, P.O. Box 191293, 00919-1293 San Juan, Puerto Rico.
| | - Cristina Sousa Mesquita
- Department of Biology and Centre for Molecular and Environmental Biology (CBMA), University of Minho, Campus de Gualtar, 4710-087 Braga, Portugal.
| | - Pedro Soares-Castro
- Department of Biology and Centre for Molecular and Environmental Biology (CBMA), University of Minho, Campus de Gualtar, 4710-087 Braga, Portugal.
| | - Marisa Ferreira
- Department of Biology and Centre for Molecular and Environmental Biology (CBMA), University of Minho, Campus de Gualtar, 4710-087 Braga, Portugal; Portuguese Wildlife Society (SPVS), Quiaios Field Station, Apartado 16 EC Quiaios, 3081-101 Figueira da Foz, Portugal.
| | - Ana Marçalo
- Department of Biology and CESAM, University of Aveiro, 3810-193 Aveiro, Portugal.
| | - José Vingada
- Portuguese Wildlife Society (SPVS), Quiaios Field Station, Apartado 16 EC Quiaios, 3081-101 Figueira da Foz, Portugal; Department of Biology and CESAM, University of Minho, Campus de Gualtar, 4710-087 Braga, Portugal.
| | - Catarina Eira
- Portuguese Wildlife Society (SPVS), Quiaios Field Station, Apartado 16 EC Quiaios, 3081-101 Figueira da Foz, Portugal; Department of Biology and CESAM, University of Aveiro, 3810-193 Aveiro, Portugal.
| | - Pedro Miguel Santos
- Department of Biology and Centre for Molecular and Environmental Biology (CBMA), University of Minho, Campus de Gualtar, 4710-087 Braga, Portugal.
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Silveira DR, Milan C, Rosa JVD, Timm CD. Fatores de patogenicidade de Vibrio spp. de importância em doenças transmitidas por alimentos. ARQUIVOS DO INSTITUTO BIOLÓGICO 2016. [DOI: 10.1590/1808-1657001252013] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
RESUMO: As bactérias do gênero Vibrio habitam ambiente tipicamente marinho e estuarino, sendo comumente isoladas de pescados. As principais espécies de Vibrio reportadas como agentes de infecções em humanos são V. vulnificus , V. parahaemolyticus , V. cholerae e V. mimicus . V. vulnificus é considerado o mais perigoso, podendo causar septicemia e levar à morte. V. parahaemolyticus é um patógeno importante nas regiões costeiras de clima temperado e tropical em todo o mundo e tem sido responsável por casos de gastroenterites associadas ao consumo de peixes, moluscos e crustáceos marinhos. V. cholerae causa surtos, epidemias e pandemias relacionados com ambientes estuarinos. V. mimicus pode causar episódios esporádicos de gastroenterite aguda e infecções de ouvido. A patogenicidade das bactérias está ligada à habilidade do micro-organismo em iniciar uma doença (incluindo entrada, colonização e multiplicação no corpo humano). Para que isso ocorra, os micro-organismos fazem uso de diversos fatores. O objetivo desta revisão foi sintetizar o conhecimento disponível na literatura sobre os fatores de patogenicidade de V. vulnificus , V. parahaemolyticus , V. cholerae e V. mimicus .
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Huang SC, Wang YK, Huang WT, Kuo TM, Yip BS, Li THT, Wu TK. Potential antitumor therapeutic application of Grimontia hollisae thermostable direct hemolysin mutants. Cancer Sci 2015; 106:447-54. [PMID: 25640743 PMCID: PMC4409889 DOI: 10.1111/cas.12623] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2014] [Revised: 01/14/2015] [Accepted: 01/25/2015] [Indexed: 11/28/2022] Open
Abstract
We report on the preparation of a new type of immunotoxin by conjugation of an epidermal growth factor receptor (EGFR)-binding peptide and an R46E mutation of thermostable direct hemolysin from Grimontia hollisae, (Gh-TDHR46E/EB). The hybrid immunotoxin was purified to homogeneity and showed a single band with slight slower mobility than that of Gh-TDHR46E. Cytotoxicity assay of Gh-TDHR46E/EB on EGFR highly, moderately, low, and non-expressed cells, A431, MDA-MB-231, HeLa, and HEK293 cells, respectively, showed apparent cytotoxicity on A431 and MDA-MB-231 cells but not on HeLa or HEK293 cells. In contrast, no cytotoxicity was observed for these cells treated with either Gh-TDHR46E or EB alone, indicating enhanced cytotoxic efficacy of Gh-TDHR46E by the EGFR binding moiety. Further antitumor activity assay of Gh-TDHR46E/EB in a xenograft model of athymic nude mice showed obvious shrinkage of tumor size and degeneration, necrosis, and lesions of tumor tissues compared to the normal tissues. Therefore, the combination of Gh-TDHR46E with target affinity agents opens new possibilities for pharmacological treatment of cancers and potentiates the anticancer drug's effect.
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Affiliation(s)
- Sheng-Cih Huang
- Department of Biological Science and Technology, National Chiao Tung University, Hsin-Chu, Taiwan
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15
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El-Malah SS, Yang Z, Hu M, Li Q, Pan Z, Jiao X. Vibrio parahaemolyticus strengthens their virulence through modulation of cellular reactive oxygen species in vitro. Front Cell Infect Microbiol 2014; 4:168. [PMID: 25566508 PMCID: PMC4269196 DOI: 10.3389/fcimb.2014.00168] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2014] [Accepted: 11/14/2014] [Indexed: 02/05/2023] Open
Abstract
Vibrio parahaemolyticus (Vp) is one of the emergent food-borne pathogens that are commensally associated with various shellfish species throughout the world. It is strictly environmental and many strains are pathogenic to humans. The virulent strains cause distinct diseases, including wound infections, septicemia, and most commonly, acute gastroenteritis, which is acquired through the consumption of raw or undercooked seafood, especially shellfish. Vp has two type three secretion systems (T3SSs), which triggering its cytotoxicity and enterotoxicity via their effectors. To better understand the pathogenesis of Vp, we established a cell infection model in vitro using a non-phagocytic cell line. Caco-2 cells were infected with different strains of Vp (pandemic and non-pandemic strains) and several parameters of cytotoxicity were measured together with adhesion and invasion indices, which reflect the pathogen's virulence. Our results show that Vp adheres to cell monolayers and can invade non-phagocytic cells. It also survives and persists in non-phagocytic cells by modulating reactive oxygen species (ROS), allowing its replication, and resulting in complete cellular destruction. We conclude that the pathogenicity of Vp is based on its capacities for adhesion and invasion. Surprisingly's; enhanced of ROS resistance period could promote the survival of Vp inside the intestinal tract, facilitating tissue infection by repressing the host's oxidative stress response.
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Affiliation(s)
- Shimaa S El-Malah
- Jiangsu Key Laboratory of Zoonosis/Jiangsu Co-Innovation Center for the Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou University Yangzhou, China
| | - Zhenquan Yang
- Jiangsu Key Laboratory of Zoonosis/Jiangsu Co-Innovation Center for the Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou University Yangzhou, China ; College of Food Science and Engineering, Yangzhou University Yangzhou, China
| | - Maozhi Hu
- Jiangsu Key Laboratory of Zoonosis/Jiangsu Co-Innovation Center for the Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou University Yangzhou, China ; Testing Center, Yangzhou University Yangzhou, China
| | - Qiuchun Li
- Jiangsu Key Laboratory of Zoonosis/Jiangsu Co-Innovation Center for the Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou University Yangzhou, China
| | - Zhiming Pan
- Jiangsu Key Laboratory of Zoonosis/Jiangsu Co-Innovation Center for the Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou University Yangzhou, China
| | - Xinan Jiao
- Jiangsu Key Laboratory of Zoonosis/Jiangsu Co-Innovation Center for the Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou University Yangzhou, China
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16
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Lin YR, Chen YL, Wang KB, Wu YF, Wang YK, Huang SC, Liu TA, Nayak M, Yip BS, Wu TK. The thermostable direct hemolysin from Grimontia hollisae causes acute hepatotoxicity in vitro and in vivo. PLoS One 2013; 8:e56226. [PMID: 23437095 PMCID: PMC3578849 DOI: 10.1371/journal.pone.0056226] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2012] [Accepted: 01/07/2013] [Indexed: 12/02/2022] Open
Abstract
Background G. hollisae thermostable direct hemolysin (Gh-TDH) is produced by most strains of G. hollisae. This toxin has been reported to be absorbed in the intestines in humans. Secondary liver injury might be caused by venous return of the toxin through the portal system. We aimed to firstly analyze the in vitro and in vivo hepatotoxicity of Gh-TDH. Methods Liver cells (primary human non-cancer cell and FL83B mouse cells) were treated and mice (BALB/c) were fed with this toxin to investigate its hepatotoxicity. Morphological examination and cytotoxicity assays using liver cells were also performed. Fluorescein isothiocyanate-conjugated toxin was used to analyze the localization of this protein in liver cells. Mice were subjected to liver function measurements and liver biopsies following toxin treatment and wild-type bacterial infection. PET (positron emission tomography)/CT (computed tomography) images were taken to assess liver metabolism during acute injury and recovery. Results The effect of hepatotoxicity was dose and time dependent. Cellular localization showed that the toxin was initially located around the cellular margins and subsequently entered the nucleus. Liver function measurements and liver biopsies of the mice following treatment with toxin or infection with wild-type Grimontia hollisae showed elevated levels of transaminases and damage to the periportal area, respectively. The PET/CT images revealed that the reconstruction of the liver continued for at least one week after exposure to a single dose of the toxin or bacterial infection. Conclusions The hepatotoxicity of Gh-TDH was firstly demonstrated. The damage was located in the periportal area of the liver, and the liver became functionally insufficient.
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Affiliation(s)
- Yan-Ren Lin
- Department of Biological Science and Technology, National Chiao Tung University, Hsin-Chu, Taiwan, Republic of China
- Department of Emergency Medicine, Changhua Christian Hospital, Changhua, Taiwan, Republic of China
- School of Medicine, Chung Shan Medical University, Taichung, Taiwan, Republic of China
| | - Yao-Li Chen
- Transplant Medicine and Surgery Research Centre, Changhua Christian Hospital, Changhua, Taiwan, Republic of China
- School of Medicine, Chung Shan Medical University, Taichung, Taiwan, Republic of China
| | - Keh-Bin Wang
- Department of Nuclear Medicine, Kuang Tien General Hospital, Taichung, Taiwan, Republic of China
| | - Yi-Fang Wu
- Department of Biological Science and Technology, National Chiao Tung University, Hsin-Chu, Taiwan, Republic of China
| | - Yu-Kuo Wang
- Department of Biological Science and Technology, National Chiao Tung University, Hsin-Chu, Taiwan, Republic of China
- * E-mail: (Y-KW); (B-SY); (T-KW)
| | - Sheng-Cih Huang
- Department of Biological Science and Technology, National Chiao Tung University, Hsin-Chu, Taiwan, Republic of China
| | - Tzu-An Liu
- Institute of Cellular and System Medicine, National Health Research Institutes, Zhunan, Miaoli County, Taiwan, Republic of China
| | - Manoswini Nayak
- Department of Biological Science and Technology, National Chiao Tung University, Hsin-Chu, Taiwan, Republic of China
| | - Bak-Sau Yip
- Department of Neurology, National Taiwan University Hospital Hsin Chu Branch, Hsin-Chu, Taiwan, Republic of China
- * E-mail: (Y-KW); (B-SY); (T-KW)
| | - Tung-Kung Wu
- Department of Biological Science and Technology, National Chiao Tung University, Hsin-Chu, Taiwan, Republic of China
- * E-mail: (Y-KW); (B-SY); (T-KW)
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17
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Deane EE, Jia A, Qu Z, Chen JX, Zhang XH, Woo NYS. Induction of apoptosis in sea bream fibroblasts by Vibrio harveyi haemolysin and evidence for an anti-apoptotic role of heat shock protein 70. JOURNAL OF FISH DISEASES 2012; 35:287-302. [PMID: 27081923 DOI: 10.1111/j.1365-2761.2012.01346.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
In this study, we exposed black sea bream, Mylio macrocephalus (Basilewsky), fibroblast (BSF) and silver sea bream, Sparus sarba Forsskål, fibroblast (SSF) cell lines to a recombinant Vibrio harveyi haemolysin (VHH) and investigated mechanisms involved in apoptosis. A decrease in mitochondrial membrane potential, followed by an increase in caspase 3 activity, occurred within 2-8 h of VHH exposure, in both cell lines; however, VHH did not alter cellular levels of reactive oxygen species. As heat shock protein 70 (HSP70) is known to prevent the onset of apoptosis in certain mammalian cells, we aimed to test whether such a protective effect is operative in VHH-exposed fibroblasts. The amounts of HSP70 were elevated in SSF and BSF via an acute heat shock or an acute heat shock followed by a 6 h recovery. It was found that the VHH-mediated reduction in mitochondrial membrane potential was suppressed in cells that had a 6 h post-heat shock recovery, and the protective effect of heat shock-induced HSP70 was attenuated following treatment of cells with the HSP70 inhibitor, quercetin. This study demonstrates how haemolysin causes cell death via induction of apoptosis and provides evidence as to the role of HSP70 as an anti-apoptotic factor.
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Affiliation(s)
- E E Deane
- School of Life Sciences, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong SAR, China Department of Marine Biology, Ocean University of China, Qingdao, China
| | - A Jia
- School of Life Sciences, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong SAR, China Department of Marine Biology, Ocean University of China, Qingdao, China
| | - Z Qu
- School of Life Sciences, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong SAR, China Department of Marine Biology, Ocean University of China, Qingdao, China
| | - J-X Chen
- School of Life Sciences, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong SAR, China Department of Marine Biology, Ocean University of China, Qingdao, China
| | - X-H Zhang
- School of Life Sciences, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong SAR, China Department of Marine Biology, Ocean University of China, Qingdao, China
| | - N Y S Woo
- School of Life Sciences, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong SAR, China Department of Marine Biology, Ocean University of China, Qingdao, China
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18
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Chowdhury P, Pore D, Mahata N, Karmakar P, Pal A, Chakrabarti MK. Thermostable direct hemolysin downregulates human colon carcinoma cell proliferation with the involvement of E-cadherin, and β-catenin/Tcf-4 signaling. PLoS One 2011; 6:e20098. [PMID: 21625458 PMCID: PMC3098874 DOI: 10.1371/journal.pone.0020098] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2011] [Accepted: 04/21/2011] [Indexed: 11/26/2022] Open
Abstract
BACKGROUND Colon cancers are the frequent causes of cancer mortality worldwide. Recently bacterial toxins have received marked attention as promising approaches in the treatment of colon cancer. Thermostable direct hemolysin (TDH) secreted by Vibrio parahaemolyticus causes influx of extracellular calcium with the subsequent rise in intracellular calcium level in intestinal epithelial cells and it is known that calcium has antiproliferative activity against colon cancer. KEY RESULTS In the present study it has been shown that TDH, a well-known traditional virulent factor inhibits proliferation of human colon carcinoma cells through the involvement of CaSR in its mechanism. TDH treatment does not induce DNA fragmentation, nor causes the release of lactate dehydrogenase. Therefore, apoptosis and cytotoxicity are not contributing to the TDH-mediated reduction of proliferation rate, and hence the reduction appears to be caused by decrease in cell proliferation. The elevation of E-cadherin, a cell adhesion molecule and suppression of β-catenin, a proto-oncogene have been observed in presence of CaSR agonists whereas reverse effect has been seen in presence of CaSR antagonist as well as si-RNA in TDH treated cells. TDH also triggers a significant reduction of Cyclin-D and cdk2, two important cell cycle regulatory proteins along with an up regulation of cell cycle inhibitory protein p27(Kip1) in presence of CaSR agonists. CONCLUSION Therefore TDH can downregulate colonic carcinoma cell proliferation and involves CaSR in its mechanism of action. The downregulation occurs mainly through the involvement of E-cadherin-β-catenin mediated pathway and the inhibition of cell cycle regulators as well as upregulation of cell cycle inhibitors.
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Affiliation(s)
- Pinki Chowdhury
- Division of Pathophysiology, National Institute of Cholera and Enteric Diseases, Beliaghata, Kolkata, India
| | - Debasis Pore
- Division of Pathophysiology, National Institute of Cholera and Enteric Diseases, Beliaghata, Kolkata, India
| | - Nibedita Mahata
- Division of Pathophysiology, National Institute of Cholera and Enteric Diseases, Beliaghata, Kolkata, India
| | - Poulomee Karmakar
- Division of Pathophysiology, National Institute of Cholera and Enteric Diseases, Beliaghata, Kolkata, India
| | - Amit Pal
- Division of Pathophysiology, National Institute of Cholera and Enteric Diseases, Beliaghata, Kolkata, India
| | - Manoj K. Chakrabarti
- Division of Pathophysiology, National Institute of Cholera and Enteric Diseases, Beliaghata, Kolkata, India
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Ohnishi K, Nakahira K, Unzai S, Mayanagi K, Hashimoto H, Shiraki K, Honda T, Yanagihara I. Relationship between heat-induced fibrillogenicity and hemolytic activity of thermostable direct hemolysin and a related hemolysin of Vibrio parahaemolyticus. FEMS Microbiol Lett 2011; 318:10-7. [PMID: 21291495 DOI: 10.1111/j.1574-6968.2011.02233.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
The formation of nonspecific ion channels by small oligomeric amyloid intermediates is toxic to the host's cellular membranes. Thermostable direct hemolysin (TDH) and TDH-related hemolysin (TRH) are major virulence factors of Vibrio parahaemolyticus. We have previously reported the crystal structure of TDH tetramer with the central channel. We have also identified the molecular mechanism underlying the paradoxical responses to heat treatment of TDH, known as the Arrhenius effect, which is the reversible amyloidogenic property. In the present report, we describe the biophysical properties of TRH, which displays 67% amino acid similarity with TDH. Molecular modeling provided a good fit of the overall structure of TDH and TRH. Size-exclusion chromatography, ultracentrifugation, and transmission electron microscopy revealed that TRH formed tetramer in solution. These toxins showed similar hemolytic activity on red blood cells. However, TRH had less amyloid-like structure than TDH analyzed by thioflavin T-binding assay and far-UV circular dichroism spectra. These data indicated that amyloidogenicity upon heating is not essential for the membrane disruption of erythrocytes, but the maintenance of tetrameric structure is indispensable for the hemolytic activity of the TDH and TRH.
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Affiliation(s)
- Kiyouhisa Ohnishi
- Department of Developmental Medicine, Osaka Medical Center for Maternal and Child Health, Research Institute, Osaka, Japan
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Wang YK, Huang SC, Wu YF, Chen YC, Chen WH, Lin YL, Nayak M, Lin YR, Li TTH, Wu TK. Purification, crystallization and preliminary X-ray analysis of a thermostable direct haemolysin from Grimontia hollisae. Acta Crystallogr Sect F Struct Biol Cryst Commun 2011; 67:224-7. [PMID: 21301091 PMCID: PMC3034613 DOI: 10.1107/s1744309110050219] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2010] [Accepted: 12/01/2010] [Indexed: 11/10/2022]
Abstract
Vibrio hollisae, a halophilic species recently reclassified as Grimontia hollisae, is a causative agent of gastroenteritis and septicaemia. One important pathogenic Vibrio factor, thermostable direct haemolysin (TDH), has been purified and crystallized in two crystal forms using the vapour-diffusion method. The crystals belonged to an orthorhombic space group, with unit-cell parameters a = 104.8, b = 112.4, c = 61.3 Å and a = 122.9, b = 123.3, c = 89.8 Å. The crystals contained either four or eight molecules per asymmetric unit, with predicted solvent contents of 49.4 and 46.3% and Matthews coefficients (V(M)) of 2.4 and 2.3 Å(3) Da(-1), respectively. These crystals were suitable for structure determination, which would yield structural details related to the cytotoxicity and oligomeric structure of this pore-forming toxin.
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Affiliation(s)
- Yu-Kuo Wang
- Department of Biological Science and Technology, National Chiao Tung University, 30068 Hsin-Chu, Taiwan
| | - Sheng-Cih Huang
- Department of Biological Science and Technology, National Chiao Tung University, 30068 Hsin-Chu, Taiwan
| | - Yi-Fang Wu
- Department of Biological Science and Technology, National Chiao Tung University, 30068 Hsin-Chu, Taiwan
| | - Yu-Ching Chen
- Department of Biological Science and Technology, National Chiao Tung University, 30068 Hsin-Chu, Taiwan
| | - Wen-Hung Chen
- Department of Biological Science and Technology, National Chiao Tung University, 30068 Hsin-Chu, Taiwan
| | - Yan-Ling Lin
- Department of Biological Science and Technology, National Chiao Tung University, 30068 Hsin-Chu, Taiwan
| | - Manoswini Nayak
- Department of Biological Science and Technology, National Chiao Tung University, 30068 Hsin-Chu, Taiwan
| | - Yan Ren Lin
- Department of Biological Science and Technology, National Chiao Tung University, 30068 Hsin-Chu, Taiwan
| | | | - Tung-Kung Wu
- Department of Biological Science and Technology, National Chiao Tung University, 30068 Hsin-Chu, Taiwan
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21
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Development of a rapid detection method to detect tdh gene in Vibrio parahaemolyticus using 2-step ultrarapid real-time polymerase chain reaction. Diagn Microbiol Infect Dis 2011; 69:21-9. [DOI: 10.1016/j.diagmicrobio.2010.08.020] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2010] [Revised: 08/03/2010] [Accepted: 08/23/2010] [Indexed: 11/23/2022]
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Gotoh K, Kodama T, Hiyoshi H, Izutsu K, Park KS, Dryselius R, Akeda Y, Honda T, Iida T. Bile acid-induced virulence gene expression of Vibrio parahaemolyticus reveals a novel therapeutic potential for bile acid sequestrants. PLoS One 2010; 5:e13365. [PMID: 20967223 PMCID: PMC2954181 DOI: 10.1371/journal.pone.0013365] [Citation(s) in RCA: 95] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2010] [Accepted: 09/07/2010] [Indexed: 11/19/2022] Open
Abstract
Vibrio parahaemolyticus, a bacterial pathogen, causes human gastroenteritis. A type III secretion system (T3SS2) encoded in pathogenicity island (Vp-PAI) is the main contributor to enterotoxicity and expression of Vp-PAI encoded genes is regulated by two transcriptional regulators, VtrA and VtrB. However, a host-derived inducer for the Vp-PAI genes has not been identified. Here, we demonstrate that bile induces production of T3SS2-related proteins under osmotic conditions equivalent to those in the intestinal lumen. We also show that bile induces vtrA-mediated vtrB transcription. Transcriptome analysis of bile-responsive genes revealed that bile strongly induces expression of Vp-PAI genes in a vtrA-dependent manner. The inducing activity of bile was diminished by treatment with bile acid sequestrant cholestyramine. Finally, we demonstrate an in vivo protective effect of cholestyramine on enterotoxicity and show that similar protection is observed in infection with a different type of V. parahaemolyticus or with non-O1/non-O139 V. cholerae strains of vibrios carrying the same kind of T3SS. In summary, these results provide an insight into how bacteria, through the ingenious action of Vp-PAI genes, can take advantage of an otherwise hostile host environment. The results also reveal a new therapeutic potential for widely used bile acid sequestrants in enteric bacterial infections.
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Affiliation(s)
- Kazuyoshi Gotoh
- Laboratory of Genomic Research on Pathogenic Bacteria, International Research Center for Infectious Diseases, Research Institute for Microbial Diseases, Osaka University, Osaka, Japan
| | - Toshio Kodama
- Department of Bacterial Infections, Research Institute for Microbial Diseases, Osaka University, Osaka, Japan
- * E-mail:
| | - Hirotaka Hiyoshi
- Laboratory of Genomic Research on Pathogenic Bacteria, International Research Center for Infectious Diseases, Research Institute for Microbial Diseases, Osaka University, Osaka, Japan
| | - Kaori Izutsu
- Laboratory of Genomic Research on Pathogenic Bacteria, International Research Center for Infectious Diseases, Research Institute for Microbial Diseases, Osaka University, Osaka, Japan
| | - Kwon-Sam Park
- Department of Bacterial Infections, Research Institute for Microbial Diseases, Osaka University, Osaka, Japan
- Department of Food Science and Bio Technology, College of Ocean Science and Technology, Kunsan National University, Kunsan, Korea
| | - Rikard Dryselius
- Laboratory of Genomic Research on Pathogenic Bacteria, International Research Center for Infectious Diseases, Research Institute for Microbial Diseases, Osaka University, Osaka, Japan
- Department of Cell and Molecular Biology, Karolinska Institutet, Stockholm, Sweden
| | - Yukihiro Akeda
- Department of Bacterial Infections, Research Institute for Microbial Diseases, Osaka University, Osaka, Japan
- Laboratory of Clinical Research on Infectious Disease, International Research Center for Infectious Diseases, Research Institute for Microbial Diseases, Osaka University, Osaka, Japan
| | - Takeshi Honda
- Department of Bacterial Infections, Research Institute for Microbial Diseases, Osaka University, Osaka, Japan
| | - Tetsuya Iida
- Laboratory of Genomic Research on Pathogenic Bacteria, International Research Center for Infectious Diseases, Research Institute for Microbial Diseases, Osaka University, Osaka, Japan
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23
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Bai F, Sun B, Woo NYS, Zhang XH. Vibrio harveyi hemolysin induces ultrastructural changes and apoptosis in flounder (Paralichthys olivaceus) cells. Biochem Biophys Res Commun 2010; 395:70-5. [PMID: 20350525 DOI: 10.1016/j.bbrc.2010.03.141] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2010] [Accepted: 03/23/2010] [Indexed: 11/30/2022]
Abstract
Vibrio harveyi hemolysin (VHH) is considered a major pathogenic virulence factor to fish. However, the VHH active-site mutant has lost all hemolytic and phospholipase activities as well as pathogenicity. In this study, the effect of VHH on erythrocytes and a gill cell line from flounder was elucidated. Erythrocyte membranes formed thin tubular protrusions immediately after exposure to VHH, and membrane corrugations were evident after extended incubation. In contrast, the mutant VHH did not induce any gross morphological changes. With VHH-treated FG-9307 cells, a cell line derived from flounder gill, destruction of organelles and formation of features resembling apoptotic bodies were observed. Immunogold staining showed that a large amount of VHH was deposited on the membranes and membrane debris of erythrocytes and FG-9307 cells after treatment with VHH. Apoptotic features, such as chromatin condensation and apoptotic bodies, were observed in VHH-treated FG-9307 cells using DAPI staining. Moreover, cell cycle analysis showed that VHH increased the proportion of cells in G1 phase. In addition, VHH significantly increased the percentage of apoptosis, the number of TUNEL positive apoptotic cells, and caspase-3 activity in FG-9307 cells when compared with the untreated controls. These data suggested that VHH killed the cells through apoptosis via the caspase activation pathway.
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Affiliation(s)
- Fangfang Bai
- Department of Marine Biology, Ocean University of China, 5 Yushan Road, Qingdao, China
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24
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Kodama T, Gotoh K, Hiyoshi H, Morita M, Izutsu K, Akeda Y, Park KS, Cantarelli VV, Dryselius R, Iida T, Honda T. Two regulators of Vibrio parahaemolyticus play important roles in enterotoxicity by controlling the expression of genes in the Vp-PAI region. PLoS One 2010; 5:e8678. [PMID: 20084267 PMCID: PMC2800187 DOI: 10.1371/journal.pone.0008678] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2009] [Accepted: 12/02/2009] [Indexed: 01/21/2023] Open
Abstract
Vibrio parahaemolyticus is an important pathogen causing food-borne disease worldwide. An 80-kb pathogenicity island (Vp-PAI), which contains two tdh (thermostable direct hemolysin) genes and a set of genes for the type III secretion system (T3SS2), is closely related to the pathogenicity of this bacterium. However, the regulatory mechanisms of Vp-PAI's gene expression are poorly understood. Here we report that two novel ToxR-like transcriptional regulatory proteins (VtrA and VtrB) regulate the expression of the genes encoded within the Vp-PAI region, including those for TDH and T3SS2-related proteins. Expression of vtrB was under control of the VtrA, as vector-expressed vtrB was able to recover a functional protein secretory capacity for T3SS2, independent of VtrA. Moreover, these regulatory proteins were essential for T3SS2-dependent biological activities, such as in vitro cytotoxicity and in vivo enterotoxicity. Enterotoxic activities of vtrA and/or vtrB deletion strains derived from the wild-type strain were almost absent, showing fluid accumulation similar to non-infected control. Whole genome transcriptional profiling of vtrA or vtrB deletion strains revealed that the expression levels of over 60 genes were downregulated significantly in these deletion mutant strains and that such genes were almost exclusively located in the Vp-PAI region. These results strongly suggest that VtrA and VtrB are master regulators for virulence gene expression in the Vp-PAI and play critical roles in the pathogenicity of this bacterium.
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Affiliation(s)
- Toshio Kodama
- Department of Bacterial Infections, Research Institute for Microbial Diseases, Osaka University, Suita, Osaka, Japan.
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25
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Association of Vibrio parahaemolyticus thermostable direct hemolysin with lipid rafts is essential for cytotoxicity but not hemolytic activity. Infect Immun 2009; 78:603-10. [PMID: 19933828 DOI: 10.1128/iai.00946-09] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Thermostable direct hemolysin (TDH), a major virulence factor of Vibrio parahaemolyticus, induces cytotoxicity in cultured cells. However, the mechanism of TDH's cytotoxic effect including its target molecules on the plasma membrane of eukaryotic cells remains unclear. In this study, we identified the role of lipid rafts, cholesterol- and sphingolipid-enriched microdomains, in TDH cytotoxicity. Treatment of cells with methyl-beta-cyclodextrin (MbetaCD), a raft-disrupting agent, inhibited TDH cytotoxicity. TDH was associated with detergent-resistant membranes (DRMs), and MbetaCD eliminated this association. In contrast, there was no such association between a nontoxic TDH mutant and DRMs. The disruption of lipid rafts neither affected hemolysis nor inhibited Ca(2+) influx into HeLa cells induced by TDH. These findings indicate that the cytotoxicity but not the hemolytic activity of TDH is dependent on lipid rafts. The exogenous and endogenous depletion of cellular sphingomyelin also prevented TDH cytotoxicity, but a direct interaction between TDH and sphingomyelin was not detected with either a lipid overlay assay or a liposome absorption test. Treatment with sphingomyelinase (SMase) at 100 mU/ml disrupted the association of TDH with DRMs but did not affect the localization of lipid raft marker proteins (caveolin-1 and flotillin-1) with DRMs. These results suggest that sphingomyelin is important for the association of TDH with lipid rafts but is not a molecular target of TDH. We hypothesize that TDH may target a certain group of rafts that are sensitive to SMase at a certain concentration, which does not affect other types of rafts.
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Hfq regulates the expression of the thermostable direct hemolysin gene in Vibrio parahaemolyticus. BMC Microbiol 2008; 8:155. [PMID: 18803872 PMCID: PMC2561041 DOI: 10.1186/1471-2180-8-155] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2008] [Accepted: 09/21/2008] [Indexed: 01/14/2023] Open
Abstract
Background The hfq gene is conserved in a wide variety of bacteria and Hfq is involved in many cellular functions such as stress responses and the regulation of gene expression. It has also been reported that Hfq is involved in bacterial pathogenicity. However, it is not clear whether Hfq regulates virulence in Vibrio parahaemolyticus. To evaluate this, we investigated the effect of Hfq on the expression of virulence-associated genes including thermostable direct hemolysin (TDH), which is considered to be an important virulence factor in V. parahaemolyticus, using an hfq deletion mutant. Results The production of TDH in the hfq deletion mutant was much higher than in the parental strain. Quantification of tdh promoter activity and mRNA demonstrated that transcription of the tdh gene was up-regulated in the mutant strain. The hfq-complemented strain had a normal (parental) amount of tdh expression. The transcriptional activity of tdhA was particularly increased in the mutant strain. These results indicate that Hfq is closely associated with the expression level of the tdh gene. Interestingly, other genes involved in the pathogenicity of V. parahaemolyticus, such as VP1680, vopC, and vopT, were also up-regulated in the mutant strain. Conclusion Hfq regulates the expression of virulence-associated factors such as TDH and may be involved in the pathogenicity of V. parahaemolyticus.
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Identification of two translocon proteins of Vibrio parahaemolyticus type III secretion system 2. Infect Immun 2008; 76:4282-9. [PMID: 18541652 DOI: 10.1128/iai.01738-07] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The type III secretion system (T3SS) translocon complex is composed of several associated proteins, which form a translocation channel through the host cell plasma membrane. These proteins are key molecules that are involved in the pathogenicity of many T3SS-positive bacteria, because they are necessary to deliver effector proteins into host cells. A T3SS designated T3SS2 of Vibrio parahaemolyticus is thought to be related to the enterotoxicity of this bacterium in humans, but the effector translocation mechanism of T3SS2 is unclear because there is only one gene (the VPA1362 gene) in the T3SS2 region that is homologous to other translocon protein genes. It is also not known whether the VPA1362 protein is functional in the translocon of T3SS2 or whether it is sufficient to form the translocation channel of T3SS2. In this study, we identified both VPA1362 (designated VopB2) and VPA1361 (designated VopD2) as T3SS2-dependent secretion proteins. Functional analysis of these proteins showed that they are essential for T3SS2-dependent cytotoxicity, for the translocation of one of the T3SS2 effector proteins (VopT), and for the contact-dependent activity of pore formation in infected cells in vitro. Their targeting to the host cell membrane depends on T3SS2, and furthermore, they are necessary for T3SS2-dependent enterotoxicity in vivo. These results indicate that VopB2 and VopD2 act as translocon proteins of V. parahaemolyticus T3SS2 and hence have a critical role in the T3SS2-dependent enterotoxicity of this bacterium.
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Kimura B, Sekine Y, Takahashi H, Tanaka Y, Obata H, Kai A, Morozumi S, Fujii T. Multiple-locus variable-number of tandem-repeats analysis distinguishes Vibrio parahaemolyticus pandemic O3:K6 strains. J Microbiol Methods 2008; 72:313-20. [PMID: 18258320 DOI: 10.1016/j.mimet.2007.12.014] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2007] [Revised: 12/15/2007] [Accepted: 12/31/2007] [Indexed: 11/28/2022]
Abstract
A specific serotype of Vibrio parahaemolyticus, O3:K6, has recently been linked to epidemics of gastroenteritis in Southeast Asia, Japan, and North America. These pandemic O3:K6 strains appear to have recently spread across continents from a single origin to reach global coverage, based on profiling of strains by several molecular typing methods. In this study, variable-number tandem repeats (VNTR)-based fingerprinting was applied to clinical and environmental V. parahaemolyticus O3:K6 strains in an attempt to develop a molecular method with increased sensitivity for discriminating strains; the relative discriminatory powers were compared with ribotyping and pulsed-field gel electrophoresis (PFGE). All clinical strains tested were independent human isolates obtained from different outbreaks or from sporadic cases in Tokyo during the period from 1996 to 2003. Multiple-locus VNTR analysis (MLVA) was shown to have high resolution and reproducibility for typing of V. parahaemolyticus clones. MLVA analysis of 28 pandemic V. parahaemolyticus O3:K6 strains isolated from human cases produced 28 distinct VNTR patterns. The VNTR loci displayed between 2 and 15 alleles at each of eight loci with Nei's diversity index ranging from 0.35 and 0.91. These data demonstrated that MLVA is useful for individual strain typing of new O3:K6 strains, which appear to be closely related by other molecular methods.
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Affiliation(s)
- Bon Kimura
- Tokyo University of Marine Science and Technology, Department of Food Science and Technology, Minato Tokyo 108-8477, Japan.
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29
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Tanaka Y, Kimura B, Takahashi H, Watanabe T, Obata H, Kai A, Morozumi S, Fujii T. Lysine decarboxylase of Vibrio parahaemolyticus: kinetics of transcription and role in acid resistance. J Appl Microbiol 2007; 104:1283-93. [PMID: 18031521 DOI: 10.1111/j.1365-2672.2007.03652.x] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
AIM The aim of this study was to investigate the detailed mechanisms of acid resistance in Vibrio parahaemolyticus. METHODS AND RESULTS All 11 strains of V. parahaemolyticus survived lethal acidic conditions following acid adaptation, and accumulation of cadaverine was detected. The addition of lysine improved survival, suggesting that lysine decarboxylase plays a role in the adaptive acid tolerance response. Two open reading frames (ORF) in V. parahaemolyticus, which are separated by a noncoding region, were found to be highly homologous to bacterial lysine decarboxylase (cadA) and lysine/cadaverine antiporter (cadB) genes. Transcriptional analyses of this operon revealed acid induction and enhanced induction by external lysine. The relative expression ratio of each transcript was found to follow the trend of cadA mRNA > cadB mRNA > cadBA bi-cistronic mRNA. A mutated strain, with a disrupted cadA gene, showed attenuated acid survival. CONCLUSIONS We identified the lysine decarboxylase gene operon of V. parahaemolyticus. Expression of this operon was induced under acidic conditions. The cadA-mutated strain constructed in this study showed weaker tolerance to acidic conditions than the wild-type strain. SIGNIFICANCE AND IMPACT OF THE STUDY Vibrio parahaemolyticus utilizes the lysine decarboxylation pathway for survival in acidic conditions.
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Affiliation(s)
- Y Tanaka
- Tokyo University of Marine Science and Technology, Minato, Tokyo, Japan
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30
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Kodama T, Rokuda M, Park KS, Cantarelli VV, Matsuda S, Iida T, Honda T. Identification and characterization of VopT, a novel ADP-ribosyltransferase effector protein secreted via the Vibrio parahaemolyticus type III secretion system 2. Cell Microbiol 2007; 9:2598-609. [PMID: 17645751 DOI: 10.1111/j.1462-5822.2007.00980.x] [Citation(s) in RCA: 108] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Vibrio parahaemolyticus strain RIMD2210633 has two sets of genes encoding two separate type III secretion systems (T3SSs), called T3SS1 and T3SS2. T3SS2 has a role in enterotoxicity and is present only in Kanagawa phenomenon-positive strains, which are pathogenic to humans. Accordingly, T3SS2 is considered to be closely related to V. parahaemolyticus human pathogenicity. Despite this, the biological actions of T3SS2 and the identity of the effector protein(s) secreted by this system have not been well understood. Here we report that T3SS2 induces a cytotoxic effect in Caco-2 and HCT-8 cells. Moreover, it was revealed that VPA1327 (vopT), a gene encoded within the proximity of T3SS2, is partly responsible for this cytotoxic effect. The VopT shows approximately 45% and 44% identity with the ADP-ribosyltransferase (ADPRT) domain of ExoT and ExoS, respectively, which are two T3SS-secreted effectors of Pseudomonas aeruginosa. T3SS2 was found to be necessary not only for the secretion, but also for the translocation of the VopT into host cells. We also demonstrate that VopT ADP-ribosylates Ras, a member of the low-molecular-weight G (LMWG) proteins both in vivo and in vitro. These results indicate that VopT is a novel ADPRT effector secreted via V. parahaemolyticus T3SS.
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Affiliation(s)
- Toshio Kodama
- Department of Bacterial Infections, Research Institute for Microbial Diseases, Osaka University, 3-1 Yamadaoka, Suita, Osaka 565-0871, Japan
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31
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Hamada D, Higurashi T, Mayanagi K, Miyata T, Fukui T, Iida T, Honda T, Yanagihara I. Tetrameric Structure of Thermostable Direct Hemolysin from Vibrio parahaemolyticus Revealed by Ultracentrifugation, Small-angle X-ray Scattering and Electron Microscopy. J Mol Biol 2007; 365:187-95. [PMID: 17056060 DOI: 10.1016/j.jmb.2006.09.070] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2006] [Revised: 09/14/2006] [Accepted: 09/26/2006] [Indexed: 10/24/2022]
Abstract
The thermostable direct hemolysin (TDH) is a major virulence factor of Vibrio parahaemolyticus. We have characterized the conformational properties of TDH by small-angle X-ray scattering (SAXS), ultracentrifugation and transmission electron microscopy. Sedimentation equilibrium and velocity studies revealed that the protein is tetrameric in aqueous solvents. The Guinier plot derived from SAXS data provided a radius of gyration of 29.0 A. The elongated pattern with a shoulder of a pair distance distribution function derived from SAXS data suggested the presence of molecules with an anisotropic shape having a maximum diameter of 98 A. Electron microscopic image analysis of the negatively stained TDH oligomer showed the presence of C(4) symmetric particles with edge and diagonal lengths of 65 A and 80 A, respectively. Shape reconstruction was carried out by ab initio calculations using the SAXS data with a C(4) symmetric approximation. These results suggested that the tetrameric TDH assumes an oblate structure. The hydrodynamic parameters predicted from the ab initio model differed slightly from the experimental values, suggesting the presence of flexible segments.
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Affiliation(s)
- Daizo Hamada
- Department of Developmental Infectious Diseases, Research Institute, Osaka Medical Center for Maternal and Child Health, 840 Murodo, Izumi, Osaka 594-1011, Japan
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Ono T, Park KS, Ueta M, Iida T, Honda T. Identification of proteins secreted via Vibrio parahaemolyticus type III secretion system 1. Infect Immun 2006; 74:1032-42. [PMID: 16428750 PMCID: PMC1360304 DOI: 10.1128/iai.74.2.1032-1042.2006] [Citation(s) in RCA: 110] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Vibrio parahaemolyticus, a gram-negative marine bacterium, is an important pathogen causing food-borne gastroenteritis or septicemia. Recent genome sequencing of the RIMD2210633 strain (a Kanagawa phenomenon-positive clinical isolate of serotype O3:K6) revealed that the strain has two sets of gene clusters that encode the type III secretion system (TTSS) apparatus. The first cluster, TTSS1, is located on the large chromosome, and the second, TTSS2, is on the small chromosome. Previously, we reported that TTSS1 is involved in the cytotoxicity of the RIMD2210633 strain against HeLa cells. Here, we analyzed proteins secreted via the TTSS apparatus encoded by TTSS1 by using two-dimensional gel electrophoresis and identified the proteins encoded by genes VP1680, VP1686, and VPA450. To investigate the roles of those secreted proteins, we constructed and analyzed a series of deletion mutants. Flow cytometry analysis using fluorescence-activated cell sorting with fluorescein isothiocyanate-labeled annexin V demonstrated that the TTSS1-dependent cell death was by apoptosis. The cytotoxicity to HeLa cells was related to one of the newly identified secreted proteins encoded by VP1680. Adenylate cyclase fusion protein studies proved that the newly identified secreted proteins were translocated into HeLa cells. Thus, these appear to be the TTSS effector proteins in V. parahaemolyticus.
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Affiliation(s)
- Takahiro Ono
- Department of Bacterial Infections, Research Institute for Microbial Diseases, Osaka University, 3-1 Yamadaoka, Suita, Osaka 565-0871, Japan
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Fukui T, Shiraki K, Hamada D, Hara K, Miyata T, Fujiwara S, Mayanagi K, Yanagihara K, Iida T, Fukusaki E, Imanaka T, Honda T, Yanagihara I. Thermostable direct hemolysin of Vibrio parahaemolyticus is a bacterial reversible amyloid toxin. Biochemistry 2005; 44:9825-32. [PMID: 16026154 DOI: 10.1021/bi050311s] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Thermostable direct hemolysin (TDH), a major virulence factor of Vibrio parahaemolyticus, is detoxified by heating at approximately 60-70 degrees C but is reactivated by additional heating above 80 degrees C. This paradoxical phenomenon, known as the Arrhenius effect, has remained unexplained for approximately 100 years. We now demonstrate that the effect is related to structural changes in the protein that produce fibrils. The native TDH (TDHn) is transformed into nontoxic fibrils rich in beta-strands by incubation at 60 degrees C (TDHi). The TDHi fibrils are dissociated into unfolded states by further heating above 80 degrees C (TDHu). Rapid cooling of TDHu results in refolding of the protein into toxic TDHn, whereas the protein is trapped in the TDHi structure by slow cooling of TDHu. Transmission electron microscopy indicates the fibrillar structures of TDHi. The fibrils show both the property of the nucleation-dependent elongation and the increase in its thioflavin T fluorescence. Formation of beta-rich structures of TDH was also observed in the presence of lipid vesicles containing ganglioside G(T1b), a putative TDH receptor. Congo red was found to inhibit the hemolytic activity of TDH in a dose-dependent manner. These data reveal that the mechanism of the Arrhenius effect which is tightly related to the fibrillogenicity of TDH.
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Affiliation(s)
- Takashi Fukui
- Department of Developmental Infectious Diseases, Research Institute, Osaka Medical Center for Maternal and Child Health, 840 Murodo-cho, Izumi, Osaka 594-1101, Japan
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Lynch T, Livingstone S, Buenaventura E, Lutter E, Fedwick J, Buret AG, Graham D, DeVinney R. Vibrio parahaemolyticus disruption of epithelial cell tight junctions occurs independently of toxin production. Infect Immun 2005; 73:1275-83. [PMID: 15731024 PMCID: PMC1064919 DOI: 10.1128/iai.73.3.1275-1283.2005] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Vibrio parahaemolyticus is a leading cause of seafood-borne gastroenteritis worldwide. Virulence is commonly associated with the production of two toxins, thermostable direct hemolysin (TDH) and TDH-related hemolysin (TRH). Although the majority of clinical isolates produce TDH and/or TRH, clinical samples lacking toxin genes have been identified. In the present study, we investigated the effects of V. parahaemolyticus on transepithelial resistance (TER) and paracellular permeability in Caco-2 cultured epithelial cells. We found that V. parahaemolyticus profoundly disrupts epithelial barrier function in Caco-2 cells and that this disruption occurs independently of toxin production. Clinical isolates with different toxin genotypes all led to a significant decrease in TER, which was accompanied by an increased flux of fluorescent dextran across the Caco-2 monolayer, and profound disruption of actin and the tight junction-associated proteins zonula occludin protein 1 and occludin. Purified TDH, even at concentrations eightfold higher than those produced by the bacteria, had no effect on either TER or paracellular permeability. We used lactate dehydrogenase release as a measure of cytotoxicity and found that this parameter did not correlate with the ability to disrupt tight junctions. As the effect on barrier function occurs independently of toxin production, we used PCR to determine the toxin genotypes of V. parahaemolyticus isolates obtained from both clinical and environmental sources, and we found that 5.6% of the clinical isolates were toxin negative. These data strongly indicate that the effect on tight junctions is not due to TDH and suggest that there are other virulence factors.
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Affiliation(s)
- Tarah Lynch
- Department of Microbiology and Infectious Diseases, University of Calgary Health Sciences Centre, 3330 Hospital Dr. NW, Calgary AB, T2N 4N1 Canada
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Park KS, Ono T, Rokuda M, Jang MH, Iida T, Honda T. Cytotoxicity and enterotoxicity of the thermostable direct hemolysin-deletion mutants of Vibrio parahaemolyticus. Microbiol Immunol 2004; 48:313-8. [PMID: 15107542 DOI: 10.1111/j.1348-0421.2004.tb03512.x] [Citation(s) in RCA: 99] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The thermostable direct hemolysin (TDH) has been proposed to be a major virulence factor of Vibrio parahaemolyticus. We have recently completed the genome sequence of a TDH-producing V. parahaemolyticus strain, RIMD2210633. In this study, we constructed tdh-deletion mutants from the sequenced strain by homologous recombination and analyzed their phenotypes. Although the deletion of both copies of tdh completely abolished the hemolytic activity of the wild-type strain, the deletion did not affect the cytotoxicity to HeLa cells. Enterotoxicity, assayed by the rabbit ileal loop test, was lowered by tdh deletion, but the mutant still showed partial fluid accumulation in rabbit intestine. These results indicate that the cytotoxicity and enterotoxicity of TDH-producing V. parahaemolyticus are not explained by TDH alone, and suggest that an unknown virulence factor(s) could be involved in these pathogenic activities.
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Affiliation(s)
- Kwon-Sam Park
- Department of Bacterial Infections, Research Institute for Microbial Diseases, Osaka University, Japan
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Lang PA, Kaiser S, Myssina S, Birka C, Weinstock C, Northoff H, Wieder T, Lang F, Huber SM. Effect of Vibrio parahaemolyticus haemolysin on human erythrocytes. Cell Microbiol 2004; 6:391-400. [PMID: 15009030 DOI: 10.1111/j.1462-5822.2004.00369.x] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Haemolysin Kanagawa, a toxin from Vibrio parahaemolyticus, is known to trigger haemolysis. Flux studies indicated that haemolysin forms a cation channel. In the present study, channel properties were elucidated by patch clamp and functional significance of ion fluxes by fluorescence-activated cell sorting (FACS) analysis. Treatment of human erythrocytes with 1 U ml-1 haemolysin within minutes induces a non-selective cation permeability. Moreover, haemolysin activates clotrimazole-sensitive K+ channels, pointing to stimulation of Ca2+-sensitive Gardos channels. Haemolysin (1 U ml-1) leads within 5 min to slight cell shrinkage, which is reversed in Ca2+-free saline. Erythrocytes treated with haemolysin (0.1 U ml-1) do not undergo significant haemolysis within the first 60 min. Replacement of extracellular Na+ with NMDG+ leads to slight cell shrinkage, which is potentiated by 0.1 U ml-1 haemolysin. According to annexin binding, treatment of erythrocytes with 0.1 U ml-1 haemolysin leads within 30 min to breakdown of phosphatidylserine asymmetry of the cell membrane, a typical feature of erythrocyte apoptosis. The annexin binding is significantly blunted at increased extracellular K+ concentrations and by K+ channel blocker clotrimazole. In conclusion, haemolysin Kanagawa induces cation permeability and activates endogenous Gardos K+ channels. Consequences include breakdown of phosphatidylserine asymmetry, which depends at least partially on cellular loss of K+.
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Affiliation(s)
- Philipp A Lang
- Department of Physiology and Universitätsklinik für Anaesthesiologie und Transfusionsmedizin, University of Tübingen, Gmelinstrasse 5, D-72076 Tübingen, Germany
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Mattana A, Cappai V, Alberti L, Serra C, Fiori PL, Cappuccinelli P. ADP and other metabolites released from Acanthamoeba castellanii lead to human monocytic cell death through apoptosis and stimulate the secretion of proinflammatory cytokines. Infect Immun 2002; 70:4424-32. [PMID: 12117953 PMCID: PMC128125 DOI: 10.1128/iai.70.8.4424-4432.2002] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Monocytes/macrophages are thought to be involved in Acanthamoeba infections. The aim of this work was to study whether soluble metabolites (ADP and other compounds) released by Acanthamoeba castellanii trophozoites could induce morphological and biochemical changes in human monocytic cells in vitro. We demonstrate here that ADP constitutively released in the medium by A. castellanii, interacting with specific P2y(2) purinoceptors expressed on the monocytic cell membrane, caused a biphasic rise in [Ca(2+)](i), morphological changes characteristics of cells undergoing apoptosis, caspase-3 activation, and secretion of tumor necrosis factor alpha (TNF-alpha). The same results were found in monocytes exposed to purified ADP. Cell damage and TNF-alpha release induced by amoebic ADP were blocked by the P2y(2) inhibitor suramin. Other metabolites contained in amoebic cell-free supernatants, with molecular masses of, respectively, >30 kDa and between 30 and 10 kDa, also caused morphological modifications and activation of intracellular caspase-3, characteristics of programmed cell death. Nevertheless, mechanisms by which these molecules trigger cell damage appeared to differ from that of ADP. In addition, other amoebic thermolable metabolites with molecular masses of <10 kDa caused the secretion of interleukin-1beta. These findings suggest that pathogenic free-living A. castellanii by release of ADP and other metabolites lead to human monocytic cell death through apoptosis and stimulate the secretion of proinflammatory cytokines.
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Affiliation(s)
- A Mattana
- Department of Pharmaceutical Sciences, University of Sassari, Italy.
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