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Liu YJ, Li R, Xiao D, Yang C, Li YL, Chen JL, Wang Z, Zhao XG, Shan ZG. Incorporating machine learning and PPI networks to identify mitochondrial fission-related immune markers in abdominal aortic aneurysms. Heliyon 2024; 10:e27989. [PMID: 38590878 PMCID: PMC10999885 DOI: 10.1016/j.heliyon.2024.e27989] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2023] [Revised: 02/26/2024] [Accepted: 03/09/2024] [Indexed: 04/10/2024] Open
Abstract
Purpose The aim of this study is to investigate abdominal aortic aneurysm (AAA), a disease characterised by inflammation and progressive vasodilatation, for novel gene-targeted therapeutic loci. Methods To do this, we used weighted co-expression network analysis (WGCNA) and differential gene analysis on samples from the GEO database. Additionally, we carried out enrichment analysis and determined that the blue module was of interest. Additionally, we performed an investigation of immune infiltration and discovered genes linked to immune evasion and mitochondrial fission. In order to screen for feature genes, we used two PPI network gene selection methods and five machine learning methods. This allowed us to identify the most featrue genes (MFGs). The expression of the MFGs in various cell subgroups was then evaluated by analysis of single cell samples from AAA. Additionally, we looked at the expression levels of the MFGs as well as the levels of inflammatory immune-related markers in cellular and animal models of AAA. Finally, we predicted potential drugs that could be targeted for the treatment of AAA. Results Our research identified 1249 up-regulated differential genes and 3653 down-regulated differential genes. Through WGCNA, we also discovered 44 genes in the blue module. By taking the point where several strategies for gene selection overlap, the MFG (ITGAL and SELL) was produced. We discovered through single cell research that the MFG were specifically expressed in T regulatory cells, NK cells, B lineage, and lymphocytes. In both animal and cellular models of AAA, the MFGs' mRNA levels rose. Conclusion We searched for the AAA novel targeted gene (ITGAL and SELL), which most likely function through lymphocytes of the B lineage, NK cells, T regulatory cells, and B lineage. This analysis gave AAA a brand-new goal to treat or prevent the disease.
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Affiliation(s)
- Yi-jiang Liu
- The First Affiliated Hospital of Xiamen University, School of Medicine Xiamen University, NO.55, Zhenhai Road, Siming District, Xiamen, Fujian, 361003, China
| | - Rui Li
- The First Affiliated Hospital of Xiamen University, School of Medicine Xiamen University, NO.55, Zhenhai Road, Siming District, Xiamen, Fujian, 361003, China
| | - Di Xiao
- The First Affiliated Hospital of Xiamen University, School of Medicine Xiamen University, NO.55, Zhenhai Road, Siming District, Xiamen, Fujian, 361003, China
| | - Cui Yang
- The First Affiliated Hospital of Xiamen University, School of Medicine Xiamen University, NO.55, Zhenhai Road, Siming District, Xiamen, Fujian, 361003, China
| | - Yan-lin Li
- The First Affiliated Hospital of Xiamen University, School of Medicine Xiamen University, NO.55, Zhenhai Road, Siming District, Xiamen, Fujian, 361003, China
| | - Jia-lin Chen
- Department of General Surgery, Fujian Medical University Union Hospital, No. 29 Xinquan Road, Fuzhou, 350001, China
| | - Zhan Wang
- The First Affiliated Hospital of Xiamen University, School of Medicine Xiamen University, NO.55, Zhenhai Road, Siming District, Xiamen, Fujian, 361003, China
| | - Xin-guo Zhao
- Yinan County People's Hospital, Linyi, 276300, China
| | - Zhong-gui Shan
- The First Affiliated Hospital of Xiamen University, School of Medicine Xiamen University, NO.55, Zhenhai Road, Siming District, Xiamen, Fujian, 361003, China
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2
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Li SC, Cheng YT, Wang CY, Wu JY, Chen ZW, Wang JP, Lin JH, Hsuan SL. Actinobacillus pleuropneumoniae exotoxin ApxI induces cell death via attenuation of FAK through LFA-1. Sci Rep 2021; 11:1753. [PMID: 33462305 PMCID: PMC7813829 DOI: 10.1038/s41598-021-81290-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2020] [Accepted: 01/05/2021] [Indexed: 01/15/2023] Open
Abstract
ApxI exotoxin is an important virulence factor derived from Actinobacillus pleuropneumoniae that causes pleuropneumonia in swine. Here, we investigate the role of lymphocyte function-associated antigen 1 (LFA-1, CD11a/CD18), a member of the β2 integrin family, and the involvement of the integrin signaling molecules focal adhesion kinase (FAK) and Akt in ApxI cytotoxicity. Using Western blot analysis, we found that ApxI downregulated the activity of FAK and Akt in porcine alveolar macrophages (AMs). Preincubation of porcine AMs with an antibody specific for porcine CD18 reduced ApxI-induced cytotoxicity as measured by a lactate dehydrogenase release assay and decreased ApxI-induced FAK and Akt attenuation, as shown by Western blot analysis. Pretreatment with the chemical compounds PMA and SC79, which activate FAK and Akt, respectively, failed to overcome the ApxI-induced attenuation of FAK and Akt and death of porcine AMs. Notably, the transfection experiments revealed that ectopic expression of porcine LFA-1 (pLFA-1) conferred susceptibility to ApxI in ApxI-insensitive cell lines, including human embryonic kidney 293T cells and FAK-deficient mouse embryonic fibroblasts (MEFs). Furthermore, ectopic expression of FAK significantly reduced ApxI cytotoxicity in pLFA-1-cotransfected FAK-deficient MEFs. These findings show for the first time that pLFA-1 renders cells susceptible to ApxI and ApxI-mediated attenuation of FAK activity via CD18, thereby contributing to subsequent cell death.
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Affiliation(s)
- Siou-Cen Li
- Graduate Institute of Veterinary Pathobiology, College of Veterinary Medicine, National Chung Hsing University, Taichung City, 402, Taiwan.,Animal Technology Laboratories, Agricultural Technology Research Institute, Hsinchu City, 300, Taiwan
| | - Yu-Tsen Cheng
- Graduate Institute of Veterinary Pathobiology, College of Veterinary Medicine, National Chung Hsing University, Taichung City, 402, Taiwan
| | - Ching-Yang Wang
- Graduate Institute of Veterinary Pathobiology, College of Veterinary Medicine, National Chung Hsing University, Taichung City, 402, Taiwan
| | - Jia-Ying Wu
- Graduate Institute of Veterinary Pathobiology, College of Veterinary Medicine, National Chung Hsing University, Taichung City, 402, Taiwan
| | - Zeng-Weng Chen
- Animal Technology Laboratories, Agricultural Technology Research Institute, Hsinchu City, 300, Taiwan
| | - Jyh-Perng Wang
- Animal Technology Laboratories, Agricultural Technology Research Institute, Hsinchu City, 300, Taiwan
| | - Jiunn-Horng Lin
- Animal Technology Laboratories, Agricultural Technology Research Institute, Hsinchu City, 300, Taiwan
| | - Shih-Ling Hsuan
- Graduate Institute of Veterinary Pathobiology, College of Veterinary Medicine, National Chung Hsing University, Taichung City, 402, Taiwan.
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O'Boyle N, Berry CC, Davies RL. Differentiated ovine tracheal epithelial cells support the colonisation of pathogenic and non-pathogenic strains of Mannheimia haemolytica. Sci Rep 2020; 10:14971. [PMID: 32917945 PMCID: PMC7486916 DOI: 10.1038/s41598-020-71604-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2020] [Accepted: 08/07/2020] [Indexed: 11/15/2022] Open
Abstract
Mannheimia haemolytica is the primary bacterial species associated with respiratory disease of ruminants. A lack of cost-effective, reproducible models for the study of M. haemolytica pathogenesis has hampered efforts to better understand the molecular interactions governing disease progression. We employed a highly optimised ovine tracheal epithelial cell model to assess the colonisation of various pathogenic and non-pathogenic M. haemolytica isolates of bovine and ovine origin. Comparison of single representative pathogenic and non-pathogenic ovine isolates over ten time-points by enumeration of tissue-associated bacteria, histology, immunofluorescence microscopy and scanning electron microscopy revealed temporal differences in adhesion, proliferation, bacterial cell physiology and host cell responses. Comparison of eight isolates of bovine and ovine origin at three key time-points (2 h, 48 h and 72 h), revealed that colonisation was not strictly pathogen or serotype specific, with isolates of serotype A1, A2, A6 and A12 being capable of colonising the cell layer regardless of host species or disease status of the host. A trend towards increased proliferative capacity by pathogenic ovine isolates was observed. These results indicate that the host-specific nature of M. haemolytica infection may result at least partially from the colonisation-related processes of adhesion, invasion and proliferation at the epithelial interface.
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Affiliation(s)
- Nicky O'Boyle
- Institute of Infection, Immunity and Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK
| | - Catherine C Berry
- Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK
| | - Robert L Davies
- Institute of Infection, Immunity and Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK.
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Tang B, Bojesen AM. Immune Suppression Induced by Gallibacterium anatis GtxA During Interaction with Chicken Macrophage-Like HD11 Cells. Toxins (Basel) 2020; 12:toxins12090536. [PMID: 32825511 PMCID: PMC7551249 DOI: 10.3390/toxins12090536] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2020] [Revised: 08/12/2020] [Accepted: 08/18/2020] [Indexed: 12/13/2022] Open
Abstract
The RTX toxin GtxA expressed by Gallibacterium anatis biovar haemolytica has been proposed a major virulence factor during disease manifestations in the natural host, the chicken. To better understand the role of GtxA in the pathogenesis of G. anatis, we compared the GtxA expressing wildtype strain with its isogenic ∆gtxA mutant that was unable to express GtxA during exposure to chicken macrophage-like HD11 cells. From adhesion and invasion assays, we showed that GtxA appears to promote adhesion and invasion of HD11 cells. By using quantitative RT-PCR, we also demonstrated that the G. anatis expressing GtxA induced a mainly anti-inflammatory (IL-10) host cell response as opposed to the pro-inflammatory (IL-1β, IL-6 and TNF-α) response induced by the GtxA deletion mutant. Interestingly, these results, at least partly, resemble recent responses observed from spleen tissue of chickens infected with the same two bacterial strains. The effect of the GtxA toxin on the type of cell death was less clear. While GtxA clearly induced cell death, our efforts to characterize whether this was due to primarily necrosis or apoptosis through expression analysis of a broad range of apoptosis genes did not reveal clear answers.
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Frey J. RTX Toxins of Animal Pathogens and Their Role as Antigens in Vaccines and Diagnostics. Toxins (Basel) 2019; 11:toxins11120719. [PMID: 31835534 PMCID: PMC6950323 DOI: 10.3390/toxins11120719] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2019] [Revised: 12/03/2019] [Accepted: 12/04/2019] [Indexed: 01/19/2023] Open
Abstract
Exotoxins play a central role in the pathologies caused by most major bacterial animal pathogens. The large variety of vertebrate and invertebrate hosts in the animal kingdom is reflected by a large variety of bacterial pathogens and toxins. The group of repeats in the structural toxin (RTX) toxins is particularly abundant among bacterial pathogens of animals. Many of these toxins are described as hemolysins due to their capacity to lyse erythrocytes in vitro. Hemolysis by RTX toxins is due to the formation of cation-selective pores in the cell membrane and serves as an important marker for virulence in bacterial diagnostics. However, their physiologic relevant targets are leukocytes expressing β2 integrins, which act as specific receptors for RTX toxins. For various RTX toxins, the binding to the CD18 moiety of β2 integrins has been shown to be host specific, reflecting the molecular basis of the host range of RTX toxins expressed by bacterial pathogens. Due to the key role of RTX toxins in the pathogenesis of many bacteria, antibodies directed against specific RTX toxins protect against disease, hence, making RTX toxins valuable targets in vaccine research and development. Due to their specificity, several structural genes encoding for RTX toxins have proven to be essential in modern diagnostic applications in veterinary medicine.
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Affiliation(s)
- Joachim Frey
- Vetsuisse Facutly, University of Bern, 3012 Bern, Switzerland
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6
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Katsafadou AI, Tsangaris GT, Anagnostopoulos AK, Billinis C, Barbagianni MS, Vasileiou NGC, Spanos SA, Mavrogianni VS, Fthenakis GC. Differential quantitative proteomics study of experimental Mannheimia haemolytica mastitis in sheep. J Proteomics 2019; 205:103393. [PMID: 31154024 DOI: 10.1016/j.jprot.2019.103393] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2018] [Revised: 05/12/2019] [Accepted: 05/14/2019] [Indexed: 02/08/2023]
Abstract
Objective was the differential quantitative proteomics study of ovine mastitis induced by Mannheimia haemolytica; clinical, microbiological, cytological and histopathological methods were employed for confirmation and monitoring. Proteins were separated by two-dimensional gel electrophoresis (2-DE) for all samples and differentially abundant proteins were identified by mass spectrometry; comparisons were performed with pre- (blood, milk) and post- (milk of contralateral gland) inoculation findings. Animals developed mastitis, confirmed by isolation of challenge strain and increase of neutrophils in milk and by histopathological evidence. In blood plasma, 33 differentially abundant proteins (compared to findings before challenge) were identified: 6 with decrease, 13 with new appearance and 14 with varying abundance. In a post-challenge milk whey protein reference map, 65 proteins were identified; actin cytoplasmic-1, beta-lactoglobulin-1/B, cathelicidin-1 predominated. Further, 89 differentially abundant proteins (compared to findings before challenge) were identified: 18 with decrease, 53 with new appearance, 3 with increase and 15 with varying abundance; 15 proteins showed status changes in blood plasma and milk whey. Differential abundance from inoculated and contralateral glands revealed 74 proteins only from the inoculated gland. Most differentially abundant proteins in milk whey were involved in cell organisation and biogenesis (n = 17) or in inflammatory and defence response (n = 13). SIGNIFICANCE: The proteomes of blood and milk from ewes with experimental mastitis caused by Mannheimia haemolytica and the differential proteomics in sequential samples after challenge are presented for the first time. This is the first detailed proteomics study in M. haemolytica-associated mastitis in ewes. An experimental model fully simulating natural mastitis has been used. Use of experimentally induced mastitis minimised potential variations and allowed consistency of results. The study included evaluation of changes in blood plasma and milk whey. Protein patterns have been studied, indicating with great accuracy changes that had occurred as part of the disease process and development, during the acute phase of infection. Relevant protein-protein interactions were studied. The entirety of proteomics findings has suggested that affected ewes had mounted a defence response that had been regulated by many proteins (e.g., cathelicidins, haptoglobin, serum amyloid A) and through various pathways (e.g., acute phase response, binding and transporting significant ions and molecules); these were interdependent at various points. Potential biomarkers have been indicated for use in diagnostic assays of mastitis.
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Affiliation(s)
- Angeliki I Katsafadou
- Veterinary Faculty, University of Thessaly, 43100 Karditsa, Greece; Proteomics Research Unit, Biomedical Research Foundation of Academy of Athens, 11527 Athens, Greece
| | - George Th Tsangaris
- Proteomics Research Unit, Biomedical Research Foundation of Academy of Athens, 11527 Athens, Greece
| | | | | | | | | | - Stavros A Spanos
- Veterinary Faculty, University of Thessaly, 43100 Karditsa, Greece
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7
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8
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Gelasakis AI, Mavrogianni VS, Petridis IG, Vasileiou NGC, Fthenakis GC. Mastitis in sheep--The last 10 years and the future of research. Vet Microbiol 2015. [PMID: 26216457 DOI: 10.1016/j.vetmic.2015.07.009] [Citation(s) in RCA: 106] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Bacterial mastitis is a significant welfare and financial problem in sheep flocks. This paper reviews the recently published literature, including publications that highlight the significance and virulence factors of the causal agents, especially Staphylococcus aureus and Mannheimia haemolytica, the primary causes of the disease. Research has also contributed to the understanding of risk factors, including genetic susceptibility of animals to infections, supporting future strategies for sustainable disease control. Pathogenetic mechanisms, including the role of the local defenses in the teat, have also been described and can assist formulation of strategies that induce local immune responses in the teat of ewes. Further to well-established diagnostic techniques, i.e., bacteriological tests and somatic cell counting, advanced methodologies, e.g., proteomics technologies, will likely contribute to more rapid and accurate diagnostics, in turn enhancing mastitis control efforts.
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Affiliation(s)
- A I Gelasakis
- Veterinary Faculty, University of Thessaly, 43100 Karditsa, Greece
| | - V S Mavrogianni
- Veterinary Faculty, University of Thessaly, 43100 Karditsa, Greece
| | - I G Petridis
- Veterinary Faculty, University of Thessaly, 43100 Karditsa, Greece
| | - N G C Vasileiou
- Veterinary Faculty, University of Thessaly, 43100 Karditsa, Greece
| | - G C Fthenakis
- Veterinary Faculty, University of Thessaly, 43100 Karditsa, Greece.
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9
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Hemolysin of enterohemorrhagic Escherichia coli: Structure, transport, biological activity and putative role in virulence. Int J Med Microbiol 2014; 304:521-9. [DOI: 10.1016/j.ijmm.2014.05.005] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2014] [Revised: 05/09/2014] [Accepted: 05/11/2014] [Indexed: 11/19/2022] Open
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10
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Bielaszewska M, Rüter C, Kunsmann L, Greune L, Bauwens A, Zhang W, Kuczius T, Kim KS, Mellmann A, Schmidt MA, Karch H. Enterohemorrhagic Escherichia coli hemolysin employs outer membrane vesicles to target mitochondria and cause endothelial and epithelial apoptosis. PLoS Pathog 2013; 9:e1003797. [PMID: 24348251 PMCID: PMC3861543 DOI: 10.1371/journal.ppat.1003797] [Citation(s) in RCA: 128] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2013] [Accepted: 10/14/2013] [Indexed: 01/08/2023] Open
Abstract
Enterohemorrhagic Escherichia coli (EHEC) strains cause diarrhea and hemolytic uremic syndrome resulting from toxin-mediated microvascular endothelial injury. EHEC hemolysin (EHEC-Hly), a member of the RTX (repeats-in-toxin) family, is an EHEC virulence factor of increasingly recognized importance. The toxin exists as free EHEC-Hly and as EHEC-Hly associated with outer membrane vesicles (OMVs) released by EHEC during growth. Whereas the free toxin is lytic towards human endothelium, the biological effects of the OMV-associated EHEC-Hly on microvascular endothelial and intestinal epithelial cells, which are the major targets during EHEC infection, are unknown. Using microscopic, biochemical, flow cytometry and functional analyses of human brain microvascular endothelial cells (HBMEC) and Caco-2 cells we demonstrate that OMV-associated EHEC-Hly does not lyse the target cells but triggers their apoptosis. The OMV-associated toxin is internalized by HBMEC and Caco-2 cells via dynamin-dependent endocytosis of OMVs and trafficked with OMVs into endo-lysosomal compartments. Upon endosome acidification and subsequent pH drop, EHEC-Hly is separated from OMVs, escapes from the lysosomes, most probably via its pore-forming activity, and targets mitochondria. This results in decrease of the mitochondrial transmembrane potential and translocation of cytochrome c to the cytosol, indicating EHEC-Hly-mediated permeabilization of the mitochondrial membranes. Subsequent activation of caspase-9 and caspase-3 leads to apoptotic cell death as evidenced by DNA fragmentation and chromatin condensation in the intoxicated cells. The ability of OMV-associated EHEC-Hly to trigger the mitochondrial apoptotic pathway in human microvascular endothelial and intestinal epithelial cells indicates a novel mechanism of EHEC-Hly involvement in the pathogenesis of EHEC diseases. The OMV-mediated intracellular delivery represents a newly recognized mechanism for a bacterial toxin to enter host cells in order to target mitochondria. During the last 30 years, enterohemorrhagic Escherichia coli (EHEC) emerged as worldwide causes of diarrhea and hemolytic uremic syndrome, the most common cause of acute kidney failure in children. EHEC hemolysin (EHEC-Hly) is one of the toxins produced by EHEC during infection that afflict the human host. EHEC-Hly belongs to a large family of toxins, whose members typically kill target cells by inserting themselves into the cell membranes, which results in pore formation and ultimately cell lysis. Here we show that EHEC-Hly associated with outer membrane vesicles (OMVs) secreted by EHEC during growth does not lyse human microvascular endothelial and intestinal epithelial cells, which are the major targets in EHEC-mediated human diseases. Instead, the OMV-associated EHEC-Hly uses the OMVs to enter the cells and acts intracellularly. The toxin separates from its carriers in lysosomes, translocates into mitochondria and triggers apoptotic death of the target cells via the mitochondrial pathway. EHEC-Hly is the first known bacterial toxin, which enters host cells via OMVs in order to attack mitochondria. The apoptotic potential of OMV-associated EHEC-Hly indicates a novel mechanism for this toxin to cause cell death during human EHEC infections.
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Affiliation(s)
| | - Christian Rüter
- Institute of Infectiology, Center for Molecular Biology of Inflammation (ZMBE), University of Münster, Münster, Germany
| | - Lisa Kunsmann
- Institute of Hygiene, University of Münster, Münster, Germany
| | - Lilo Greune
- Institute of Infectiology, Center for Molecular Biology of Inflammation (ZMBE), University of Münster, Münster, Germany
| | - Andreas Bauwens
- Institute of Hygiene, University of Münster, Münster, Germany
| | - Wenlan Zhang
- Institute of Hygiene, University of Münster, Münster, Germany
| | | | - Kwang Sik Kim
- Division of Pediatric Infectious Diseases, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
| | | | - M. Alexander Schmidt
- Institute of Infectiology, Center for Molecular Biology of Inflammation (ZMBE), University of Münster, Münster, Germany
| | - Helge Karch
- Institute of Hygiene, University of Münster, Münster, Germany
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An assessment of opportunities to dissect host genetic variation in resistance to infectious diseases in livestock. Animal 2012; 3:415-36. [PMID: 22444313 DOI: 10.1017/s1751731108003522] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
This paper reviews the evidence for host genetic variation in resistance to infectious diseases for a wide variety of diseases of economic importance in poultry, cattle, pig, sheep and Atlantic salmon. Further, it develops a method of ranking each disease in terms of its overall impact, and combines this ranking with published evidence for host genetic variation and information on the current state of genomic tools in each host species. The outcome is an overall ranking of the amenability of each disease to genomic studies that dissect host genetic variation in resistance. Six disease-based assessment criteria were defined: industry concern, economic impact, public concern, threat to food safety or zoonotic potential, impact on animal welfare and threat to international trade barriers. For each category, a subjective score was assigned to each disease according to the relative strength of evidence, impact, concern or threat posed by that particular disease, and the scores were summed across categories. Evidence for host genetic variation in resistance was determined from available published data, including breed comparison, heritability studies, quantitative trait loci (QTL) studies, evidence of candidate genes with significant effects, data on pathogen sequence and on host gene expression analyses. In total, 16 poultry diseases, 13 cattle diseases, nine pig diseases, 11 sheep diseases and three Atlantic salmon diseases were assessed. The top-ranking diseases or pathogens, i.e. those most amenable to studies dissecting host genetic variation, were Salmonella in poultry, bovine mastitis, Marek's disease and coccidiosis, both in poultry. The top-ranking diseases or pathogens in pigs, sheep and Atlantic salmon were Escherichia coli, mastitis and infectious pancreatic necrosis, respectively. These rankings summarise the current state of knowledge for each disease and broadly, although not entirely, reflect current international research efforts. They will alter as more information becomes available and as genome tools become more sophisticated for each species. It is suggested that this approach could be used to rank diseases from other perspectives as well, e.g. in terms of disease control strategies.
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Aulik NA, Atapattu DN, Czuprynski CJ, McCaslin DR. Brief heat treatment causes a structural change and enhances cytotoxicity of theEscherichia coliα-hemolysin. Immunopharmacol Immunotoxicol 2012; 35:15-27. [DOI: 10.3109/08923973.2012.723009] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
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13
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Frey J. The role of RTX toxins in host specificity of animal pathogenic Pasteurellaceae. Vet Microbiol 2011; 153:51-8. [PMID: 21645978 DOI: 10.1016/j.vetmic.2011.05.018] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2010] [Revised: 04/29/2011] [Accepted: 05/10/2011] [Indexed: 10/18/2022]
Abstract
RTX toxins are bacterial pore-forming toxins that are particularly abundant among pathogenic species of Pasteurellaceae, in which they play a major role in virulence. RTX toxins of several primary pathogens of the family of Pasteurellaceae are directly involved in causing necrotic lesions in the target organs. Many RTX toxins are known as haemolysins because they lyse erythrocytes in vitro, an effect that is non-specific, but which serves as a useful marker in bacteriological identification and as an easily measurable signal in vitro in experimental studies. More recent studies have shown that the specific targets of most RTX toxins are leukocytes, with RTX toxins binding to the corresponding β-subunit (CD18) of β2 integrins and then exerting cytotoxic activity. After uptake by the target cell, at sub-lytic concentrations, some RTX toxins are transported to mitochondria and induce apoptosis. For several RTX toxins the binding to CD18 has been shown to be host specific and this seems to be the basis for the host range specificity of these RTX toxins. Observations on two very closely related species of the Pasteurellaceae family, Actinobacillus suis, a porcine pathogen particularly affecting suckling pigs, and Actinobacillus equuli subsp. haemolytica, which causes pyosepticaemia in new-born foals (sleepy foal disease), have revealed that they express different RTX toxins, named ApxI/II and Aqx, respectively. These RTX toxins are specifically cytotoxic for porcine and equine leukocytes, respectively. Furthermore, the ApxI and Aqx toxins of these species, when expressed in an isogenetic background in Escherichia coli, are specifically cytotoxic for leukocytes of their respective hosts. These data indicate the determinative role of RTX toxins in host specificity of pathogenic species of Pasteurellaceae.
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Affiliation(s)
- Joachim Frey
- Institute of Veterinary Bacteriology, University of Bern, Laenggasstrasse 122, CH-3012 Bern, Switzerland.
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14
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Porta H, Cancino-Rodezno A, Soberón M, Bravo A. Role of MAPK p38 in the cellular responses to pore-forming toxins. Peptides 2011; 32:601-6. [PMID: 20599578 PMCID: PMC2994946 DOI: 10.1016/j.peptides.2010.06.012] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/16/2010] [Revised: 06/17/2010] [Accepted: 06/17/2010] [Indexed: 12/16/2022]
Abstract
Understanding the mechanism of action of pore-forming toxins (PFTs) produced by different bacteria, as well as the host responses to toxin action, would provide ways to deal with these pathogenic bacteria. PFTs affect the permeability of target cells by forming pores in their plasma membrane. Target organisms may overcome these effects by triggering intracellular responses that have evolved as defense mechanisms to PFT. Among them it is well documented that stress-activated protein kinases, and specially MAPK p38 pathway, play a crucial role triggering defense responses to several PFTs in different eukaryotic cells. In this review we describe different intracellular effects induced by PFTs in eukaryotic cells and highlight diverse responses activated by p38 pathway.
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Affiliation(s)
- Helena Porta
- Instituto de Biotecnología, Universidad Nacional Autónoma de México, Apdo. Postal 510-3, Cuernavaca 62250, Morelos, Mexico
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15
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Aulik NA, Hellenbrand KM, Kisiela D, Czuprynski CJ. Mannheimia haemolytica leukotoxin binds cyclophilin D on bovine neutrophil mitochondria. Microb Pathog 2011; 50:168-78. [PMID: 21220005 DOI: 10.1016/j.micpath.2011.01.001] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2010] [Revised: 12/28/2010] [Accepted: 01/03/2011] [Indexed: 01/03/2023]
Abstract
Mannheimia haemolytica is an important member of the bovine respiratory disease (BRD) complex that causes fibrinous and necrotizing pleuropneumonia in cattle. BRD is characterized by abundant neutrophil infiltration into the alveoli and fibrin deposition. The most important virulence factor of M. haemolytica is its leukotoxin. Previous research in our laboratory has shown that the leukotoxin is able to enter into and traffic to the mitochondria of a bovine lymphoblastoid cell line (BL-3). In this study, we evaluated the ability of LKT to be internalized and travel to mitochondria in bovine neutrophils. We demonstrate that LKT binds bovine neutrophil mitochondria and co-immunoprecipitates with TOM22 and TOM40, which are members of the translocase of the outer mitochondrial (TOM) membrane family. Upon entry into mitochondria, LKT co-immunoprecipitates with cyclophilin D, a member of the mitochondria permeability transition pore. Unlike BL-3 cells, bovine neutrophil mitochondria are not protected against LKT by the membrane-stabilizing agent cyclosporin A, nor were bovine neutrophil mitochondria protected by the permeability transition pore antagonist bongkrekic acid. In addition, we found that bovine neutrophil cyclophilin D is significantly smaller than that found in BL-3 cells. Bovine neutrophils were protected against LKT by protein transfection of an anti-cyclophilin D antibody directed at the C-terminal amino acids, but not an antibody against the first 50 N-terminal amino acids. In contrast, BL-3 cells were protected by antibodies against either the C-terminus or N-terminus of cyclophilin. These data confirm that LKT binds to bovine neutrophil mitochondria, but indicate there are distinctions between neutrophil and BL-3 mitochondria that might reflect differences in cyclophilin D.
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Affiliation(s)
- Nicole A Aulik
- Microbiology Doctoral Training Program, University of Wisconsin-Madison, Madison, WI 53706, USA
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16
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Linhartová I, Bumba L, Mašín J, Basler M, Osička R, Kamanová J, Procházková K, Adkins I, Hejnová-Holubová J, Sadílková L, Morová J, Sebo P. RTX proteins: a highly diverse family secreted by a common mechanism. FEMS Microbiol Rev 2011; 34:1076-112. [PMID: 20528947 PMCID: PMC3034196 DOI: 10.1111/j.1574-6976.2010.00231.x] [Citation(s) in RCA: 355] [Impact Index Per Article: 27.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Repeats-in-toxin (RTX) exoproteins of Gram-negative bacteria form a steadily growing family of proteins with diverse biological functions. Their common feature is the unique mode of export across the bacterial envelope via the type I secretion system and the characteristic, typically nonapeptide, glycine- and aspartate-rich repeats binding Ca2+ ions. In this review, we summarize the current state of knowledge on the organization of rtx loci and on the biological and biochemical activities of therein encoded proteins. Applying several types of bioinformatic screens on the steadily growing set of sequenced bacterial genomes, over 1000 RTX family members were detected, with the biological functions of most of them remaining to be characterized. Activities of the so far characterized RTX family members are then discussed and classified according to functional categories, ranging from the historically first characterized pore-forming RTX leukotoxins, through the large multifunctional enzymatic toxins, bacteriocins, nodulation proteins, surface layer proteins, up to secreted hydrolytic enzymes exhibiting metalloprotease or lipase activities of industrial interest.
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Affiliation(s)
- Irena Linhartová
- Institute of Microbiology AS CR v.v.i., Academy of Sciences of the Czech Republic, Prague, Czech Republic
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Forman MS, Nishikubo JB, Han RK, Le A, Balashova NV, Kachlany SC. Gangliosides block Aggregatibacter Actinomycetemcomitans leukotoxin (LtxA)-mediated hemolysis. Toxins (Basel) 2010; 2:2824-36. [PMID: 22069577 PMCID: PMC3153184 DOI: 10.3390/toxins2122824] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2010] [Revised: 11/24/2010] [Accepted: 12/10/2010] [Indexed: 01/22/2023] Open
Abstract
Aggregatibacter actinomycetemcomitans is an oral pathogen and etiologic agent of localized aggressive periodontitis. The bacterium is also a cardiovascular pathogen causing infective endocarditis. A. actinomycetemcomitans produces leukotoxin (LtxA), an important virulence factor that targets white blood cells (WBCs) and plays a role in immune evasion during disease. The functional receptor for LtxA on WBCs is leukocyte function antigen-1 (LFA-1), a β-2 integrin that is modified with N-linked carbohydrates. Interaction between toxin and receptor leads to cell death. We recently discovered that LtxA can also lyse red blood cells (RBCs) and hemolysis may be important for pathogenesis of A. actinomycetemcomitans. In this study, we further investigated how LtxA might recognize and lyse RBCs. We found that, in contrast to a related toxin, E. coli α-hemolysin, LtxA does not recognize glycophorin on RBCs. However, gangliosides were able to completely block LtxA-mediated hemolysis. Furthermore, LtxA did not show a preference for any individual ganglioside. LtxA also bound to ganglioside-rich C6 rat glioma cells, but did not kill them. Interaction between LtxA and C6 cells could be blocked by gangliosides with no apparent specificity. Gangliosides were only partially effective at preventing LtxA-mediated cytotoxicity of WBCs, and the effect was only observed when a high ratio of ganglioside:LtxA was used over a short incubation period. Based on the results presented here, we suggest that because of the similarity between N-linked sugars on LFA-1 and the structures of gangliosides, LtxA may have acquired the ability to lyse RBCs.
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Affiliation(s)
- Michael S Forman
- Department of Oral Biology, New Jersey Dental School, University of Medicine and Dentistry of New Jersey, 185 South Orange Avenue, Newark, NJ, USA.
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Mannheimia haemolytica and its leukotoxin cause neutrophil extracellular trap formation by bovine neutrophils. Infect Immun 2010; 78:4454-66. [PMID: 20823211 DOI: 10.1128/iai.00840-10] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Mannheimia haemolytica is an important member of the bovine respiratory disease complex, which is characterized by abundant neutrophil infiltration into the alveoli and fibrin deposition. Recently several authors have reported that human neutrophils release neutrophil extracellular traps (NETs), which are protein-studded DNA matrices capable of trapping and killing pathogens. Here, we demonstrate that the leukotoxin (LKT) of M. haemolytica causes NET formation by bovine neutrophils in a CD18-dependent manner. Using an unacylated, noncytotoxic pro-LKT produced by an ΔlktC mutant of M. haemolytica, we show that binding of unacylated pro-LKT stimulates NET formation despite a lack of cytotoxicity. Inhibition of LKT binding to the CD18 chain of lymphocyte function-associated antigen 1 (LFA-1) on bovine neutrophils reduced NET formation in response to LKT or M. haemolytica cells. Further investigation revealed that NETs formed in response to M. haemolytica are capable of trapping and killing a portion of the bacterial cells. NET formation was confirmed by confocal microscopy and by scanning and transmission electron microscopy. Prior exposure of bovine neutrophils to LKT enhanced subsequent trapping and killing of M. haemolytica cells in bovine NETs. Understanding NET formation in response to M. haemolytica and its LKT provides a new perspective on how neutrophils contribute to the pathogenesis of bovine respiratory disease.
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Singh K, Ritchey JW, Confer AW. Mannheimia haemolytica: bacterial-host interactions in bovine pneumonia. Vet Pathol 2010; 48:338-48. [PMID: 20685916 DOI: 10.1177/0300985810377182] [Citation(s) in RCA: 93] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Mannheimia haemolytica serotype S1 is considered the predominant cause of bovine pneumonic pasteurellosis, or shipping fever. Various virulence factors allow M haemolytica to colonize the lungs and establish infection. These virulence factors include leukotoxin (LKT), lipopolysaccharide, adhesins, capsule, outer membrane proteins, and various proteases. The effects of LKT are species specific for ruminants, which stem from its unique interaction with the bovine β2 integrin receptor present on leukocytes. At low concentration, LKT can activate bovine leukocytes to undergo respiratory burst and degranulation and stimulate cytokine release from macrophages and histamine release from mast cells. At higher concentration, LKT induces formation of transmembrane pores and subsequent oncotic cell necrosis. The interaction of LKT with leukocytes is followed by activation of these leukocytes to undergo oxidative burst and release proinflammatory cytokines such as interleukins 1, 6, and 8 and tumor necrosis factor α. Tumor necrosis factor α and other proinflammatory cytokines contribute to the accumulation of leukocytes in the lung. Formation of transmembrane pores and subsequent cytolysis of activated leukocytes possibly cause leakage of products of respiratory burst and other inflammatory mediators into the surrounding pulmonary parenchyma and so give rise to fibrinous and necrotizing lobar pneumonia. The effects of LKT are enhanced by lipopolysaccharide, which is associated with the release of proinflammatory cytokines from the leukocytes, activation of complement and coagulation cascade, and cell cytolysis. Similarly, adhesins, capsule, outer membrane proteins, and proteases assist in pulmonary colonization, evasion of immune response, and establishment of the infection. This review focuses on the roles of these virulence factors in the pathogenesis of shipping fever.
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Affiliation(s)
- K Singh
- Department of Pathobiology, College of Veterinary Medicine, University of Illinois, Urbana, IL 61802, USA.
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Kisiela DI, Aulik NA, Atapattu DN, Czuprynski CJ. N-terminal region of Mannheimia haemolytica leukotoxin serves as a mitochondrial targeting signal in mammalian cells. Cell Microbiol 2010; 12:976-87. [PMID: 20109159 DOI: 10.1111/j.1462-5822.2010.01445.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Mannheimia haemolytica leukotoxin (LktA) is a member of the RTX toxin family that specifically kills ruminant leukocytes. Previous studies have shown that LktA induces apoptosis in susceptible cells via a caspase-9-dependent pathway that involves binding of LktA to mitochondria. In this study, using the bioinformatics tool MitoProt II we identified an N-terminal amino acid sequence of LktA that represents a mitochondrial targeting signal (MTS). We show that expression of this sequence, as a GFP fusion protein within mammalian cells, directs GFP to mitochondria. By immunoprecipitation we demonstrate that LktA interacts with the Tom22 and Tom40 components of the translocase of the outer mitochondrial membrane (TOM), which suggests that import of this toxin into mitochondria involves a classical import pathway for endogenous proteins. We also analysed the amino acid sequences of other RTX toxins and found a MTS in the N-terminal region of Actinobacillus pleuropneumoniae ApxII and enterohaemorrhagic Escherichia coli EhxA, but not in A. pleuropneumoniae ApxI, ApxIII, Aggregatibacter actinomycetemcomitans LtxA or the haemolysin (HlyA) from uropathogenic strains of E. coli. These findings provide a new evidence for the importance of the N-terminal region in addressing certain RTX toxins to mitochondria.
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Affiliation(s)
- Dagmara I Kisiela
- Department of Pathobiological Sciences, School of Veterinary Medicine, University of Wisconsin-Madison, 2015 Linden Drive, Madison, WI 53706, USA
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21
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Abstract
AbstractBovine respiratory disease (BRD) involves complex interactions amongst viral and bacterial pathogens that can lead to intense pulmonary inflammation (fibrinous pleuropneumonia). Viral infection greatly increases the susceptibility of cattle to secondary infection of the lung with bacterial pathogens likeMannheimia haemolyticaandHistophilus somni. The underlying reason for this viral/bacterial synergism, and the manner in which cattle respond to the virulence strategies of the bacterial pathogens, is incompletely understood. Bovine herpesvirus type 1 (BHV-1) infection of bronchial epithelial cellsin vitroenhances the binding ofM. haemolyticaand triggers release of inflammatory mediators that attract and enhance binding of neutrophils. An exotoxin (leukotoxin) released fromM. haemolyticafurther stimulates release of inflammatory mediators and causes leukocyte death. Cattle infected withH. somnifrequently display vasculitis. Exposure of bovine endothelial cells toH. somniior its lipooligosaccharide (LOS) increases endothelium permeability, and makes the surface of the endothelial cells pro-coagulant. These processes are amplified in the presence of platelets. The above findings demonstrate that bovine respiratory pathogens (BHV-1,M. haemolyticaandH. somni) interact with leukocytes and other cells (epithelial and endothelial cells) leading to the inflammation that characterizes BRD.
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Bovine herpesvirus type 1 infection of bovine bronchial epithelial cells increases neutrophil adhesion and activation. Vet Immunol Immunopathol 2009; 131:167-76. [PMID: 19406483 DOI: 10.1016/j.vetimm.2009.04.002] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2009] [Revised: 03/28/2009] [Accepted: 04/03/2009] [Indexed: 01/13/2023]
Abstract
Respiratory infection of cattle with bovine herpesvirus type 1 (BHV-1) predisposes cattle to secondary pneumonia with Mannheimia haemolytica as part of the bovine respiratory disease complex (BRD). One cell type that has received limited investigation for its role in the inflammation that accompanies BRD is the respiratory epithelial cell. In the present study we investigated mechanisms by which BHV-1 infection of respiratory epithelial cells contributes to the recruitment and activation of bovine polymorphonuclear neutrophils (PMNs) in vitro. Primary cultures of bovine bronchial epithelial (BBE) cells were infected with BHV-1 and assessed for cytokine expression by real-time PCR. We found that BHV-1 infection elicits a rapid IL-1, IL-8 and TNF-alpha mRNA response by BBE cells. Bovine PMNs exhibited greater adherence to BHV-1 infected BBE cells than uninfected cells. The increased adherence was significantly reduced by the addition of an anti-IL-1beta antibody or human soluble TNF-alpha receptor (sTNF-alphaR). Pre-incubation of bovine PMNs with conditioned media from BHV-1 infected BBE cells increased PMN migration, which was inhibited by addition of an anti-IL-1beta antibody, sTNF-alphaR, or an IL-8 peptide inhibitor. Conditioned media from BHV-1 infected BBE cells activated bovine PMNs in vitro as demonstrated by PMN shape change, production of reactive oxygen species and degranulation. PMNs also exhibited increased LFA-1 expression and susceptibility to M. haemolytica LKT following incubation with BHV-1 infected BBE cell conditioned media. Our results suggest that BHV-1 infection of BBE cells triggers cytokine expression that contributes to the recruitment and activation of neutrophils, and amplifies the detrimental effects of M. haemolytica LKT.
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23
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Actinobacillus pleuropneumoniae serotype 10 derived ApxI induces apoptosis in porcine alveolar macrophages. Vet Microbiol 2009; 135:327-33. [DOI: 10.1016/j.vetmic.2008.09.071] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2008] [Revised: 08/04/2008] [Accepted: 09/19/2008] [Indexed: 11/22/2022]
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24
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Atapattu DN, Aulik NA, McCaslin DR, Czuprynski CJ. Brief heat treatment increases cytotoxicity of Mannheimia haemolytica leukotoxin in an LFA-1 independent manner. Microb Pathog 2009; 46:159-65. [PMID: 19185607 DOI: 10.1016/j.micpath.2008.12.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2008] [Revised: 12/16/2008] [Accepted: 12/30/2008] [Indexed: 11/25/2022]
Abstract
Mannheimia haemolytica is an important respiratory pathogen in cattle. Its predominant virulence factor is a leukotoxin (LKT) that is a member of the RTX family of exotoxins produced by a variety of Gram negative bacteria. LKT binds to the CD18 chain of beta(2) integrins on bovine leukocytes, resulting in cell death. In this study, we show that brief heat treatment of native LKT (95 degrees C for 3 min) results in increased cytotoxicity for BL-3 (bovine lymphoblastoid) cells. Similar heat treatment restored the activity of LKT that had been rendered inactive by incubation at 22 degrees C for 3 days. A hallmark of LKT is that its toxicity is restricted to leukocytes from cattle or other ruminant species. Surprisingly, heat treatment rendered LKT cytotoxic for human, porcine and canine leukocytes. Membrane binding studies suggested that heat-treated LKT binds to membrane proteins other than LFA-1, and is distributed diffusely along the BL-3 cell membrane. Circular Dichroism spectroscopy studies indicate that heat treatment induced a small change in the secondary structure of the LKT that was not reversed when the LKT was cooled to room temperature. Thus, we speculate that these structural changes might contribute to the altered biological properties of heat-treated LKT.
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Affiliation(s)
- Dhammika N Atapattu
- Department of Pathobiological Sciences, University of Wisconsin, 2015, Linden Drive, West, Madison, WI 53706, USA
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25
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Cancino-Rodezno A, Porta H, Soberón M, Bravo A. Defense and death responses to pore forming toxins. Biotechnol Genet Eng Rev 2009; 26:65-82. [DOI: 10.5661/bger-26-65] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
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26
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Atapattu DN, Albrecht RM, McClenahan DJ, Czuprynski CJ. Dynamin-2-dependent targeting of mannheimia haemolytica leukotoxin to mitochondrial cyclophilin D in bovine lymphoblastoid cells. Infect Immun 2008; 76:5357-65. [PMID: 18765728 PMCID: PMC2573345 DOI: 10.1128/iai.00221-08] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2008] [Revised: 06/09/2008] [Accepted: 08/26/2008] [Indexed: 11/20/2022] Open
Abstract
Exotoxins which belong to the family containing the RTX toxins (repeats in toxin) contribute to a variety of important human and animal diseases. One example of such a toxin is the potent leukotoxin (LKT) produced by the bovine respiratory pathogen Mannheimia haemolytica. LKT binds to CD18, resulting in the death of bovine leukocytes. In this study, we showed that internalized LKT binds to the outer mitochondrial membrane, which results in the release of cytochrome c and collapse of the mitochondrial membrane potential (psi(m)). Incubation of bovine lymphoblastoid cells (BL-3 cells) with the mitochondrial membrane-stabilizing agent cyclosporine (CSA) reduced LKT-mediated cytotoxicity, cytochrome c release, and collapse of the psi(m). Coimmunoprecipitation and intracellular binding studies suggested that LKT binds to the mitochondrial matrix protein cyclophilin D. We also demonstrated that LKT mobilizes the vesicle scission protein dynamin-2 from mitochondria to the cell membrane. Incubation with CSA depleted mitochondrial dynamin-2 in BL-3 cells, making it unavailable for vesicle scission and LKT internalization. The results of this study show that LKT trafficking and LKT-mediated cell death involve dynamin-2 and cyclophilin D, in a process that can be prevented by the mitochondrial membrane-protecting function of CSA.
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Affiliation(s)
- Dhammika N Atapattu
- Department of Pathobiological Sciences, 2015 Linden Drive West, University of Wisconsin-Madison, Madison, WI 53706, USA
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27
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Lu Y, Wu LQ, Wang SG, Lv ZH, Han B. Caspase-3 gene transfected with LIGHT gene: can it be used for therapy of human hepatocellular carcinoma? Clin Chem Lab Med 2008; 46:470-4. [PMID: 18298346 DOI: 10.1515/cclm.2008.094] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
BACKGROUND The aim of this study was to detect the expression of apoptosis factor caspase-3 in transferred HepG2 cells and provide feasible evaluation of the treatment for primary liver cancer with gene methods. METHODS The pcDNA4C-LIGHT cDNA was extracted from Escherichia coli JM-109; then, the pcDNA4C-LIGHT cDNA was transferred into the HepG2 cells by a cationic liposome mediated method. Meanwhile, the blank group was established as the control group and the HepG2 cells were collected after transfection at 12 h, 24 h, 48 h, 3 days and 5 days. The expression of caspase-3 was identified in the supernatants by ELISA. A standard curve was generated for the set of samples assayed. Statistical significance was analyzed by SPSS. RESULTS The quantity of caspase-3 protein was the greatest at 48 h and the least on day 5. The secretion of caspase-3 did not increase in the control group. The coefficient of correlation was equal to 0.9986 and had evident significance. CONCLUSIONS The pcDNA4C-LIGHT was effectively transfected in human HepG2 cells mediated by liposome. The expression of caspase-3 increased in the transfected group. This study provides necessary theoretic support for the treatment of liver cancer with gene methods.
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Affiliation(s)
- Yun Lu
- Department of Hepatobiliary Surgery, Affiliated Hospital of Medical College, Qingdao University, Qingdao, Shandong Province, China.
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28
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Nørgaard J, Theil P, Sørensen M, Sejrsen K. Cellular Mechanisms in Regulating Mammary Cell Turnover During Lactation and Dry Period in Dairy Cows. J Dairy Sci 2008; 91:2319-27. [DOI: 10.3168/jds.2007-0767] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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29
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Wiles TJ, Dhakal BK, Eto DS, Mulvey MA. Inactivation of host Akt/protein kinase B signaling by bacterial pore-forming toxins. Mol Biol Cell 2008; 19:1427-38. [PMID: 18234841 PMCID: PMC2291440 DOI: 10.1091/mbc.e07-07-0638] [Citation(s) in RCA: 75] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2007] [Revised: 11/01/2007] [Accepted: 01/23/2008] [Indexed: 01/13/2023] Open
Abstract
Uropathogenic Escherichia coli (UPEC) are the major cause of urinary tract infections (UTIs), and they have the capacity to induce the death and exfoliation of target uroepithelial cells. This process can be facilitated by the pore-forming toxin alpha-hemolysin (HlyA), which is expressed and secreted by many UPEC isolates. Here, we demonstrate that HlyA can potently inhibit activation of Akt (protein kinase B), a key regulator of host cell survival, inflammatory responses, proliferation, and metabolism. HlyA ablates Akt activation via an extracellular calcium-dependent, potassium-independent process requiring HlyA insertion into the host plasma membrane and subsequent pore formation. Inhibitor studies indicate that Akt inactivation by HlyA involves aberrant stimulation of host protein phosphatases. We found that two other bacterial pore-forming toxins (aerolysin from Aeromonas species and alpha-toxin from Staphylococcus aureus) can also markedly attenuate Akt activation in a dose-dependent manner. These data suggest a novel mechanism by which sublytic concentrations of HlyA and other pore-forming toxins can modulate host cell survival and inflammatory pathways during the course of a bacterial infection.
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Affiliation(s)
- Travis J. Wiles
- Division of Cell Biology and Immunology, Department of Pathology, University of Utah, Salt Lake City, UT 84112-0565
| | - Bijaya K. Dhakal
- Division of Cell Biology and Immunology, Department of Pathology, University of Utah, Salt Lake City, UT 84112-0565
| | - Danelle S. Eto
- Division of Cell Biology and Immunology, Department of Pathology, University of Utah, Salt Lake City, UT 84112-0565
| | - Matthew A. Mulvey
- Division of Cell Biology and Immunology, Department of Pathology, University of Utah, Salt Lake City, UT 84112-0565
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30
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Effects of lipopolysaccharide and Mannheimia haemolytica leukotoxin on bovine lung microvascular endothelial cells and alveolar epithelial cells. CLINICAL AND VACCINE IMMUNOLOGY : CVI 2007; 15:338-47. [PMID: 18032592 DOI: 10.1128/cvi.00344-07] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Bovine respiratory disease resulting from infection with Mannheimia haemolytica commonly results in extensive vascular leakage into the alveoli. M. haemolytica produces two substances, lipopolysaccharide (LPS) and leukotoxin (LKT), that are known to be important in inducing some of the pathological changes. In the present study, we examined bovine pulmonary epithelial (BPE) cell and bovine lung microvascular endothelial cell monolayer permeability, as measured by trans-well endothelial and epithelial cell electrical resistance (TEER), after incubation with LPS, LKT, or LPS-activated neutrophils. Endothelial cell monolayers exposed to LPS exhibited significant decreases in TEER that corresponded with increased levels of proinflammatory cytokines, apoptosis, and morphological changes. In contrast, BPE cells exposed to LPS increased the levels of production of inflammatory cytokines but displayed no changes in TEER, apoptosis, or visible morphological changes. Both cell types appeared to express relatively equal levels of the LPS ligand Toll-like receptor 4. However, TEER in BPE cell monolayers was decreased when the cells were incubated with LPS-activated neutrophils. Although the incubation of BPE cells with LKT decreased TEER, this was not reduced by the incubation of LKT with a neutralizing antibody and was reversed when LKT was preincubated with the LPS-neutralizing compound polymyxin B. Because BPE cells did not express the LKT receptor CD11a/CD18, we infer that contaminating LPS was responsible for the decreased TEER. In conclusion, LPS triggered changes in endothelial cells that would be consistent with vascular leakage, but neither LPS nor LKT caused similar changes in epithelial cells, unless neutrophils were also present.
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31
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Atapattu DN, Czuprynski CJ. Mannheimia haemolytica leukotoxin binds to lipid rafts in bovine lymphoblastoid cells and is internalized in a dynamin-2- and clathrin-dependent manner. Infect Immun 2007; 75:4719-27. [PMID: 17682044 PMCID: PMC2044511 DOI: 10.1128/iai.00534-07] [Citation(s) in RCA: 25] [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
Mannheimia haemolytica is the principal bacterial pathogen of the bovine respiratory disease complex. Its most important virulence factor is a leukotoxin (LKT), which is a member of the RTX family of exotoxins produced by many gram-negative bacteria. Previous studies demonstrated that LKT binds to the beta(2)-integrin LFA-1 (CD11a/CD18) on bovine leukocytes, resulting in cell death. In this study, we demonstrated that depletion of lipid rafts significantly decreases LKT-induced bovine lymphoblastoid cell (BL-3) death. After binding to BL-3 cells, some of the LKT relocated to lipid rafts in an LFA-1-independent manner. We hypothesized that after binding to LFA-1 on BL-3 cells, LKT moves to lipid rafts and clathrin-coated pits via a dynamic process that results in LKT internalization and cytotoxicity. Knocking down dynamin-2 by small interfering RNA reduced both LKT internalization and cytotoxicity. Similarly, expression of dominant negative Eps15 protein expression, which is required for clathrin coat formation, reduced LKT internalization and LKT-mediated cytotoxicity to BL-3 cells. Finally, we demonstrated that inhibiting actin polymerization reduced both LKT internalization and LKT-mediated cytotoxicity. These results suggest that both lipid rafts and clathrin-mediated mechanisms are important for LKT internalization and cytotoxicity in BL-3 cells and illustrate the complex nature of LKT internalization by the cytoskeletal network.
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Affiliation(s)
- Dhammika N Atapattu
- Department of Pathobiological Sciences, University of Wisconsin, 2015, Linden Drive, West, Madison, WI 53706, USA
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32
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Kehl-Fie TE, St Geme JW. Identification and characterization of an RTX toxin in the emerging pathogen Kingella kingae. J Bacteriol 2006; 189:430-6. [PMID: 17098895 PMCID: PMC1797395 DOI: 10.1128/jb.01319-06] [Citation(s) in RCA: 90] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Kingella kingae is an emerging bacterial pathogen that is increasingly recognized as the causative agent of a variety of pediatric diseases, including septic arthritis and osteomyelitis. The pathogenesis of K. kingae disease is believed to begin with colonization of the upper respiratory tract. In the present study, we examined interactions between K. kingae and cultured respiratory epithelial cells and observed potent cytotoxicity, detected by both microscopy and lactic acid dehydrogenase (LDH) release assays. Experiments with synovial and macrophage cell lines revealed cytotoxicity for these cell types as well. Using mariner mutagenesis and a screen for loss of cytotoxicity, a genetic locus encoding an RTX toxin system was identified. Disruption of the K. kingae RTX locus resulted in a loss of cytotoxicity for respiratory epithelial, synovial, and macrophage cell lines. DNA sequence analysis demonstrated that the RTX locus is flanked by insertion elements and has a reduced G+C content compared to that of the whole genome. Two relatively less invasive Kingella species, K. oralis and K. denitrificans, were found to be noncytotoxic and to lack the RTX region, as determined by LDH release assays and Southern blotting. We concluded that K. kingae expresses an RTX toxin that has wide cellular specificity and was likely acquired horizontally. The possible roles for this toxin in the pathogenesis of K. kingae disease include breaching of the epithelial barrier and destruction of target tissues, such as synovium (joint lining).
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Affiliation(s)
- Thomas E Kehl-Fie
- Edward Mallinckrodt Department of Pediatrics, Washington University School of Medicine, St. Louis, Missouri 63310, USA
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