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Joon A, Chandel S, Ghosh S. Role of TLRs in EGFR-mediated IL-8 secretion by enteroaggregative Escherichia coli-infected cultured human intestinal epithelial cells. J Cell Commun Signal 2023:10.1007/s12079-023-00776-5. [PMID: 37347390 DOI: 10.1007/s12079-023-00776-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2022] [Accepted: 05/31/2023] [Indexed: 06/23/2023] Open
Abstract
Enteroaggregative Escherichia coli (EAEC) is an emerging enteric pathogen associated with persistent diarrhea in travelers, immunocompromised patients and children worldwide. However, the pathogenesis of this organism is yet to be established. In this study, the role of Toll-like receptors (TLRs) was evaluated in epidermal growth factor receptor (EGFR)-mediated IL-8 secretion by EAEC-infected human small intestinal and colonic epithelial cells (INT-407 and HCT-15, respectively). We observed that EAEC-induced upregulation of TLR2, TLR4 and TLR5 transcripts in both types of cells, and the maximum level of these transcripts was seen in cells infected with EAEC-T8 (an invasive clinical isolate). All these TLRs made a significant contribution to the EAEC-T8-mediated EGFR activation in these cells. Furthermore, these TLRs were found to be associated with activation of the downstream effectors (ERK-1/2, PI3 kinase and Akt) and transcription factors (NF-κB, c-Jun, c-Fos and STAT-3) of EGFR-mediated signal transduction pathways. Moreover, the involvement of these TLRs was also noted in IL-8 secretion by both EAEC-T8-infected cell types. Our findings suggest that EAEC-induced upregulation of TLR2, TLR4 and TLR5 is important for the IL-8 response via EGFR-mediated signal transduction pathways in these cells.
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Affiliation(s)
- Archana Joon
- Department of Experimental Medicine and Biotechnology, Post Graduate Institute of Medical Education and Research, Chandigarh, 160012, India
| | - Shipra Chandel
- Department of Experimental Medicine and Biotechnology, Post Graduate Institute of Medical Education and Research, Chandigarh, 160012, India
| | - Sujata Ghosh
- Department of Experimental Medicine and Biotechnology, Post Graduate Institute of Medical Education and Research, Chandigarh, 160012, India.
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2
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Sundaram E, Kathiravan S, Manna A, Chinnaiah A, Vasantha V. Designing of New Optical Immunosensors Based on 2-Amino-4-(anthracen-9-yl)-7-hydroxy-4 H-chromene-3-carbonitrile for the Detection of Aeromonas hydrophila in the Organs of Oreochromis mossambicus Fingerlings. ACS OMEGA 2019; 4:4814-4824. [PMID: 31459665 PMCID: PMC6648643 DOI: 10.1021/acsomega.8b02467] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/29/2018] [Accepted: 01/14/2019] [Indexed: 05/27/2023]
Abstract
A one-pot greener methodology has been adopted for the synthesis of a simple 4H-chromene core-based fluorescent tag of (S)-2-amino-4-(anthracen-9-yl)-7-hydroxy-4H-chromene-3-carbonitrile (AHC), and its structure has been analyzed using NMR spectroscopy. The physicochemical properties of AHC were well-studied by UV-vis and fluorescent spectroscopy techniques. As a result of excellent emitting property (ϕ ≈ 0.75), it has been coupled with anti-AH through amide linkage, and the AHC-tagged anti-AH has been used as an immunoassay for the selective detection of Aeromonas hydrophila in the presence of interfering pathogens. Under optimized conditions, immunosensors could successfully quantify A. hydrophila from 4 to 736 CFU/mL, and the LOD was 2 CFU/mL. Saliently, the immunoassay has been successfully demonstrated for the analysis of A. hydrophila in the organs of Oreochromis mossambicusfingerlings, and results have shown a very good agreement with our optimized neat AH fluorimetric titration results.
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Affiliation(s)
- Ellairaja Sundaram
- Department
of Natural Products Chemistry, School of Chemistry, and Department of
Animal Behaviour and Physiology, School of Biological Sciences, Madurai Kamaraj University, Madurai 625 021, Tamilnadu, India
| | - Shenbagavalli Kathiravan
- Department
of Natural Products Chemistry, School of Chemistry, and Department of
Animal Behaviour and Physiology, School of Biological Sciences, Madurai Kamaraj University, Madurai 625 021, Tamilnadu, India
| | - Abhijit Manna
- Department
of Natural Products Chemistry, School of Chemistry, and Department of
Animal Behaviour and Physiology, School of Biological Sciences, Madurai Kamaraj University, Madurai 625 021, Tamilnadu, India
| | - Amutha Chinnaiah
- Department
of Natural Products Chemistry, School of Chemistry, and Department of
Animal Behaviour and Physiology, School of Biological Sciences, Madurai Kamaraj University, Madurai 625 021, Tamilnadu, India
| | - VairathevarSivasamy Vasantha
- Department
of Natural Products Chemistry, School of Chemistry, and Department of
Animal Behaviour and Physiology, School of Biological Sciences, Madurai Kamaraj University, Madurai 625 021, Tamilnadu, India
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Shelly A, Banerjee C, Saurav GK, Ray A, Rana VS, Raman R, Mazumder S. Aeromonas hydrophila-induced alterations in cytosolic calcium activate pro-apoptotic cPKC-MEK1/2-TNFα axis in infected headkidney macrophages of Clarias gariepinus. DEVELOPMENTAL AND COMPARATIVE IMMUNOLOGY 2017; 76:392-402. [PMID: 28713009 DOI: 10.1016/j.dci.2017.07.015] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/22/2017] [Revised: 07/12/2017] [Accepted: 07/12/2017] [Indexed: 06/07/2023]
Abstract
Alterations in intracellular-calcium (Ca2+)i homeostasis is critical to Aeromonas hydrophila-induced headkidney macrophages (HKM) apoptosis of Clarias gariepinus, though the implications are poorly understood. Here, we describe the role of intermediate molecules of Ca2+-signaling pathway that are involved in HKM apoptosis. We observed phosphoinositide-3-kinase/phospholipase C is critical for (Ca2+)i release in infected HKM. Heightened protein kinase-C (PKC) activity and phosphorylation of MEK1/2-ERK1/2 was noted which declined in presence of 2-APB, Go6976 and PD98059, inhibitors to IP3-receptor, conventional PKC isoforms (cPKC) and MEK1/2 respectively implicating Ca2+/cPKC/MEK-ERK1/2 axis imperative in A. hydrophila-induced HKM apoptosis. Significant tumor necrosis factor-α (TNFα) production and its subsequent reduction in presence of MEK-ERK1/2 inhibitor U0126 suggested TNFα production downstream to cPKC-mediated signaling via MEK1/2-ERK1/2 pathway. RNAi and inhibitor studies established the role of TNFα in inducing caspase-8-mediated apoptosis of infected HKM. We conclude, alterations in A. hydrophila-induced (Ca2+)i alterations activate cPKC-MEK1/2-ERK1/2-TNFα signaling cascade triggering HKM apoptosis.
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Affiliation(s)
- Asha Shelly
- Immunobiology Laboratory, Department of Zoology, University of Delhi, Delhi 110 007, India
| | - Chaitali Banerjee
- Immunobiology Laboratory, Department of Zoology, University of Delhi, Delhi 110 007, India
| | - Gunjan Kumar Saurav
- Gut Biology Laboratory, Department of Zoology, University of Delhi, Delhi 110 007, India
| | - Atish Ray
- Immunobiology Laboratory, Department of Zoology, University of Delhi, Delhi 110 007, India
| | - Vipin Singh Rana
- Gut Biology Laboratory, Department of Zoology, University of Delhi, Delhi 110 007, India
| | - Rajagopal Raman
- Gut Biology Laboratory, Department of Zoology, University of Delhi, Delhi 110 007, India
| | - Shibnath Mazumder
- Immunobiology Laboratory, Department of Zoology, University of Delhi, Delhi 110 007, India.
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Functional genomic characterization of virulence factors from necrotizing fasciitis-causing strains of Aeromonas hydrophila. Appl Environ Microbiol 2014; 80:4162-83. [PMID: 24795370 DOI: 10.1128/aem.00486-14] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
The genomes of 10 Aeromonas isolates identified and designated Aeromonas hydrophila WI, Riv3, and NF1 to NF4; A. dhakensis SSU; A. jandaei Riv2; and A. caviae NM22 and NM33 were sequenced and annotated. Isolates NF1 to NF4 were from a patient with necrotizing fasciitis (NF). Two environmental isolates (Riv2 and -3) were from the river water from which the NF patient acquired the infection. While isolates NF2 to NF4 were clonal, NF1 was genetically distinct. Outside the conserved core genomes of these 10 isolates, several unique genomic features were identified. The most virulent strains possessed one of the following four virulence factors or a combination of them: cytotoxic enterotoxin, exotoxin A, and type 3 and 6 secretion system effectors AexU and Hcp. In a septicemic-mouse model, SSU, NF1, and Riv2 were the most virulent, while NF2 was moderately virulent. These data correlated with high motility and biofilm formation by the former three isolates. Conversely, in a mouse model of intramuscular infection, NF2 was much more virulent than NF1. Isolates NF2, SSU, and Riv2 disseminated in high numbers from the muscular tissue to the visceral organs of mice, while NF1 reached the liver and spleen in relatively lower numbers on the basis of colony counting and tracking of bioluminescent strains in real time by in vivo imaging. Histopathologically, degeneration of myofibers with significant infiltration of polymorphonuclear cells due to the highly virulent strains was noted. Functional genomic analysis provided data that allowed us to correlate the highly infectious nature of Aeromonas pathotypes belonging to several different species with virulence signatures and their potential ability to cause NF.
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Jagusztyn-Krynicka EK, Dadlez M, Grabowska A, Roszczenko P. Proteomic technology in the design of new effective antibacterial vaccines. Expert Rev Proteomics 2014; 6:315-30. [DOI: 10.1586/epr.09.47] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
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6
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Rosenzweig JA, Chopra AK. Modulation of host immune defenses by Aeromonas and Yersinia species: convergence on toxins secreted by various secretion systems. Front Cell Infect Microbiol 2013; 3:70. [PMID: 24199174 PMCID: PMC3812659 DOI: 10.3389/fcimb.2013.00070] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2013] [Accepted: 10/14/2013] [Indexed: 12/20/2022] Open
Abstract
Like other pathogenic bacteria, Yersinia and Aeromonas species have been continuously co-evolving with their respective hosts. Although the former is a bonafide human pathogen, the latter has gained notararity as an emerging disease-causing agent. In response to immune cell challenges, bacterial pathogens have developed diverse mechanism(s) enabling their survival, and, at times, dominance over various host immune defense systems. The bacterial type three secretion system (T3SS) is evolutionarily derived from flagellar subunits and serves as a vehicle by which microbes can directly inject/translocate anti-host factors/effector proteins into targeted host immune cells. A large number of Gram-negative bacterial pathogens possess a T3SS empowering them to disrupt host cell signaling, actin cytoskeleton re-arrangements, and even to induce host-cell apoptotic and pyroptotic pathways. All pathogenic yersiniae and most Aeromonas species possess a T3SS, but they also possess T2- and T6-secreted toxins/effector proteins. This review will focus on the mechanisms by which the T3SS effectors Yersinia outer membrane protein J (YopJ) and an Aeromonas hydrophila AexU protein, isolated from the diarrheal isolate SSU, mollify host immune system defenses. Additionally, the mechanisms that are associated with host cell apoptosis/pyroptosis by Aeromonas T2SS secreted Act, a cytotoxic enterotoxin, and Hemolysin co-regulated protein (Hcp), an A. hydrophila T6SS effector, will also be discussed.
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Affiliation(s)
- Jason A Rosenzweig
- Department of Biology, Center for Bionanotechnology and Environmental Research, Texas Southern University Houston, TX, USA ; Department of Environmental and Interdisciplinary Sciences, Texas Southern University Houston, TX, USA
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Igbinosa IH, Igumbor EU, Aghdasi F, Tom M, Okoh AI. Emerging Aeromonas species infections and their significance in public health. ScientificWorldJournal 2012; 2012:625023. [PMID: 22701365 PMCID: PMC3373137 DOI: 10.1100/2012/625023] [Citation(s) in RCA: 199] [Impact Index Per Article: 16.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2012] [Accepted: 03/20/2012] [Indexed: 12/28/2022] Open
Abstract
Aeromonas species are ubiquitous bacteria in terrestrial and aquatic milieus. They are becoming renowned as enteric pathogens of serious public health concern as they acquire a number of virulence determinants that are linked with human diseases, such as gastroenteritis, soft-tissue, muscle infections, septicemia, and skin diseases. Proper sanitary procedures are essential in the prevention of the spread of Aeromonas infections. Oral fluid electrolyte substitution is employed in the prevention of dehydration, and broad-spectrum antibiotics are used in severe Aeromonas outbreaks. This review presents an overview of emerging Aeromonas infections and proposes the need for actions necessary for establishing adequate prevention measures against the infections.
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Affiliation(s)
- Isoken H. Igbinosa
- Applied and Environmental Microbiology Research Group (AEMREG), Department of Biochemistry and Microbiology, University of Fort Hare, Private Bag X1314, Alice 5700, South Africa
| | - Ehimario U. Igumbor
- School of Public Health, University of the Western Cape, Bellville 7535, Cape Town, South Africa
| | - Farhad Aghdasi
- Risk and Vulnerability Assessment Centre, University of Fort Hare, Private Bag X1314, Alice 5700, South Africa
| | - Mvuyo Tom
- Applied and Environmental Microbiology Research Group (AEMREG), Department of Biochemistry and Microbiology, University of Fort Hare, Private Bag X1314, Alice 5700, South Africa
| | - Anthony I. Okoh
- Applied and Environmental Microbiology Research Group (AEMREG), Department of Biochemistry and Microbiology, University of Fort Hare, Private Bag X1314, Alice 5700, South Africa
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8
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Goyal A, Konar M, Setia A, Narang A, Ghosh S. Galactose specific adhesin of enteroaggregative E. coli induces IL-8 secretion via activation of MAPK and STAT-3 in INT-407 cells. Biochim Biophys Acta Gen Subj 2010; 1800:574-9. [PMID: 20304034 DOI: 10.1016/j.bbagen.2010.03.009] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2009] [Revised: 03/10/2010] [Accepted: 03/12/2010] [Indexed: 11/26/2022]
Abstract
BACKGROUND Enteroaggregative Escherichia coli (EAEC) is one of the most common bacterial pathogens associated with the etiology of persistent diarrhea. A characteristic feature of EAEC-pathogenesis is the induction of profound inflammatory response in the intestinal epithelium. The present study was designed to investigate the underlying mechanism of inflammatory responses induced by a novel galactose specific adhesin of T7 strain of EAEC (EAEC-T7) in human intestinal epithelial cell line (INT-407). METHODS INT-407 cells were stimulated with the adhesin in the absence and presence of anti-adhesin (IgG(AD))/d-galactose/H7/staurosporin (inhibitor of PKC)/PD098059 (inhibitor of MEK)/SB203580 (inhibitor of p38-MAPkinase)/AG490 (inhibitor of JAK (-2,-3)/STAT-3 pathway). The expression of activated Raf-1, MEK-1, ERK1/2, JNK, p38-MAPK and STAT-3 was analyzed by Western immunoblot. Release of interleukin-8 (IL-8) was measured by ELISA. RESULTS The adhesin was found to induce activation of Raf-1, MEK-1, ERK1/2, p38-MAPK and STAT-3, which was reduced in the presence of IgG(AD)/d-galactose. The activation of Raf-1 was found to be attenuated in the presence of H7/staurosporin. The expression of phosphorylated STAT-3 was downregulated in the presence of AG490 and PD098059. Further, the adhesin induced IL-8 secretion was reduced in the presence of the inhibitors of MEK (PD098059), p38-MAPK (SB203580) and JAK (-2,-3)/STAT-3 pathway (AG490). CONCLUSIONS We propose that STAT-3 activation is quintessential for the galactose specific adhesin induced IL-8 secretion by INT-407 cells and must occur in concert with the activation of ERK1/2. GENERAL SIGNIFICANCE Our contribution regarding the galactose specific adhesin mediated signaling leads to an improved understanding of the EAEC-pathogenesis and may provide novel therapeutic approaches to combat EAEC infection.
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Affiliation(s)
- Atul Goyal
- Department of Pediatrics, Post Graduate Institute of Medical Education and Research, Chandigarh, India
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Majumdar T, Chattopadhyay P, Saha DR, Sau S, Mazumder S. Virulence plasmid of Aeromonas hydrophila induces macrophage apoptosis and helps in developing systemic infection in mice. Microb Pathog 2009; 46:98-107. [DOI: 10.1016/j.micpath.2008.11.002] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2008] [Revised: 11/06/2008] [Accepted: 11/07/2008] [Indexed: 12/26/2022]
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10
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Figueiredo JF, Lawhon SD, Gokulan K, Khare S, Raffatellu M, Tsolis RM, Bäumler AJ, McCormick BA, Adams LG. Salmonella enterica Typhimurium SipA induces CXC-chemokine expression through p38MAPK and JUN pathways. Microbes Infect 2008; 11:302-10. [PMID: 19114119 DOI: 10.1016/j.micinf.2008.12.005] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2008] [Revised: 11/19/2008] [Accepted: 12/04/2008] [Indexed: 11/25/2022]
Abstract
The role of Salmonella typhimurium type III secretion system (T3SS-1)-translocated proteins in chemokines' expression and protein phosphorylation was investigated in HeLa cells. Infection of HeLa cells with S. typhimurium activated IL-8 and GRO-alpha expression at higher levels than infection with a S. typhimurium sipAsopABDE2 mutant, confirming that T3SS-1-secreted proteins are required to fully induce chemokine expression in HeLa cells. A S. typhimurium sipAsopABDE2 mutant complemented with sipA or a strain carrying a chromosomal copy of sipA (sopABDE2 mutant) activated chemokines at significantly higher levels than a S. typhimurium sipAsopABDE2 mutant. However, extracellular addition of recombinant SipA failed to induce IL-8 expression. Phosphorylation analyses revealed that S. typhimurium induced a twofold increase in the phosphorylation of B23, CREB1, ERK1, JUN, p38MAPK, and NR1. JUN and p38MAPK were phosphorylated by S. typhimurium carrying a chromosomal copy of sipA (sopABDE2 mutant) while none was more than twofold phosphorylated in cells infected with the S. typhimurium sipAsopABDE2 mutant. Treating cells with JUN and p38MAPK inhibitors significantly decreased IL-8 expression in sopABDE2 mutant infected cells. These data indicate that S. typhimurium SipA induces expression of CXC chemokines through phosphorylation of IL-8-transcription regulatory proteins, JUN and p38MAK.
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Affiliation(s)
- Josely F Figueiredo
- Department of Veterinary Pathobiology, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX 77843-4467, USA
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Chang YC, Wang JY, Selvam A, Kao SC, Yang SS, Shih DYC. Multiplex PCR detection of enterotoxin genes in Aeromonas spp. from suspect food samples in northern Taiwan. J Food Prot 2008; 71:2094-9. [PMID: 18939759 DOI: 10.4315/0362-028x-71.10.2094] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Aeromonads possess an array of virulence factors and are causative agents of a number of human infections. Among them, genes of one cytotoxic (Act) and two cytotonic (Alt, Ast) enterotoxins are implicated in a human diarrheal disease. A rapid, specific, simultaneous detection of these enterotoxin genes in suspected food poisoning samples is not yet reported. Hence, a multiplex PCR assay was designed to amplify the cytotoxic (act), heat-labile cytotonic (alt), and heat-stable cytotonic (ast) enterotoxin genes of aeromonads. The PCR assay was tested with 133 Aeromonas spp. isolated from suspect food poisoning samples and retail samples of poultry and fish from wet markets in and around Taipei, Northern Taiwan. The Aeromonas spp. isolates were divided into six genotypes based on absence or presence of one or more enterotoxin genes. Of these 133 isolates, Aeromonas caviae (52.5%) and Aeromonas hydrophila (43.4%) were the most frequently isolated species from food poisoning samples and retail samples, respectively. Among the species, A. hydrophila had a significantly higher proportion for harboring three enterotoxin genes than had the others, whereas Aeromonas encheleia, considered a nonpathogen, was found harboring three enterotoxin genes. The multiplex PCR assays are rapid and specific, and provide a useful tool for the detection and genotyping of enterotoxin genes of aeromonads.
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Affiliation(s)
- Yu-Chang Chang
- Food Microbiology Division, Bureau of Food and Drug Analysis, Department of Health, Executive Yuan, Taipei 115, Taiwan
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Fadl AA, Galindo CL, Sha J, Zhang F, Garner HR, Wang HQ, Chopra AK. Global transcriptional responses of wild-type Aeromonas hydrophila and its virulence-deficient mutant in a murine model of infection. Microb Pathog 2007; 42:193-203. [PMID: 17368824 DOI: 10.1016/j.micpath.2007.02.002] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2006] [Revised: 12/12/2006] [Accepted: 02/02/2007] [Indexed: 11/25/2022]
Abstract
We previously generated a double knockout mutant (act/aopB) of a diarrheal isolate SSU of A. hydrophila, in which the genes encoding Aeromonas outer membrane protein B (AopB), a structural component of the type III secretion system (T3SS), and a type II (T2)-secreted cytotoxic enterotoxin gene (act) were deleted. This mutant exhibited minimal virulence in mice, compared to animals infected with wild-type (WT) A. hydrophila. Based on microarray analyses, WT A. hydrophila altered the expression of 434 and 80 genes in murine macrophages (RAW 264.7) and human colonic epithelial cells (HT-29), respectively. Approximately half of these gene expression alterations were abrogated when host cells were infected instead with the act/aopB mutant. In this study, we used microarrays to examine early host transcriptional responses in spleens of mice infected for 3h with WT A. hydrophila or its act/aopB mutant. Our data indicated that expression of 221 genes was altered (158 up-regulated and 63 down-regulated) in spleens of WT bacteria-infected animals. There were 21 genes that were consistently more highly expressed in WT A. hydrophila-infected mice, compared to mice infected with its act/aopB mutant. Ten of these genes were either induced to a lesser extent (e.g., interleukin-6, macrophage inflammatory protein-2, and cyclooxygenase-2), not altered at all (e.g., killer cell lectin-like receptor subfamily B member A), or down-regulated (e.g., cytochrome P450) in animals infected with A. hydrophila, compared to phosphate-buffered saline-infected control animals, when the mutant was used instead of the WT. We verified the microarray results at the transcript level by performing real-time reverse transcriptase-polymerase chain reaction on selected genes and at the protein level by enzyme-linked immunosorbent assay (ELISA) and immunohistochemistry. This is the first study demonstrating in vivo gene regulation in mice infected with A. hydrophila and the contribution of virulence factors and host responses to the disease process.
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Affiliation(s)
- Amin A Fadl
- Department of Microbiology and Immunology, Medical Research Building, 301 University Boulevard, University of Texas Medical Branch, Galveston, TX 77555-1070, USA
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13
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Fadl AA, Galindo CL, Sha J, Erova TE, Houston CW, Olano JP, Chopra AK. Deletion of the genes encoding the type III secretion system and cytotoxic enterotoxin alters host responses to Aeromonas hydrophila infection. Microb Pathog 2006; 40:198-210. [PMID: 16626931 DOI: 10.1016/j.micpath.2006.01.003] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2005] [Revised: 01/09/2006] [Accepted: 01/16/2006] [Indexed: 12/21/2022]
Abstract
In our previous study, we deleted the gene encoding Aeromonas outer membrane protein B (AopB), a structural component of the type III secretion system (T3SS) from a cytotoxic enterotoxin gene (act)-minus diarrheal isolate SSU of Aeromonas hydrophila. Our laboratory also molecularly characterized the cytotoxic enterotoxin (Act), which is secreted by the bacterium utilizing the type II secretion system (T2SS). The act/aopB mutant exhibited significantly reduced cytotoxicity to cultured cells (e.g. RAW 264.7 murine macrophages and HT-29 human colonic epithelial cells) and was avirulent in mice. In this study, we developed additional A. hydrophila mutants in which T3SS-associated ascV and acrV genes were deleted, either individually or in combination with that of the act gene, to examine host-pathogen interactions. A significant reduction in the induction of inflammatory cytokines and chemokines was noted in the sera of mice infected with these mutants when compared to animals infected with wild-type (WT) A. hydrophila. After infection with the WT and act/aopB mutant, we performed microarray analyses on RNA from the above-mentioned murine macrophages and human colonic epithelial cells to examine global cellular transcriptional responses. Based on three independent experiments, WT A. hydrophila altered the expression of 434 genes in RAW 264.7 cells and 80 genes in HT-29 cells. Alteration in the expression of 209 macrophage and 32 epithelial cell genes was reduced when the act/aopB mutant was used, compared to when cells were infected with the WT bacterium, indicating the involvement of Act and/or AopB in transcriptional regulation of these genes. We verified up-regulation of 15 genes by real-time reverse transcriptase-polymerase chain reaction and confirmed A. hydrophila WT-versus mutant-induced production of cytokines/chemokines in supernatants from RAW 264.7 and HT-29 cells. This is the first description of host cell transcriptional responses to A. hydrophila infection.
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Affiliation(s)
- Amin A Fadl
- Department of Microbiology and Immunology, The University of Texas Medical Branch, Medical Research Building, 301 University Boulevard, Galveston, TX 77555-1070, USA
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14
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Galindo CL, Gutierrez C, Chopra AK. Potential involvement of galectin-3 and SNAP23 in Aeromonas hydrophila cytotoxic enterotoxin-induced host cell apoptosis. Microb Pathog 2006; 40:56-68. [PMID: 16426811 DOI: 10.1016/j.micpath.2005.11.001] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2005] [Revised: 11/03/2005] [Accepted: 11/07/2005] [Indexed: 11/23/2022]
Abstract
We investigated the potential of the cytotoxic enterotoxin (Act) of Aeromonas hydrophila to bind to 1869 human and 4319 yeast proteins, using protein microarray technology. Act was capable of binding nine different human proteins, including the SNARE complex scaffolding protein synaptosomal-associated protein 23 (SNAP23), galectin-3, and guanylate kinase 1 (GUK-1). Act was also able to bind to four of the yeast proteins examined, which included the vesicle tethering protein Vsp52. We verified interaction of Act with murine and human SNAP23, galectin-3, and GUK-1 by sandwich Western blot analysis. In order to determine the physiological relevance of Act binding to these three proteins, we performed small interfering RNA (siRNA) gene knockdown experiments in RAW 264.7 cells, a murine macrophage cell line in which Act-induced signaling and cell death is well characterized. Based on real-time reverse transcriptase-polymerase chain reaction, siRNA transfection of RAW 264.7 cells with specific oligonucleotides reduced the expression of genes encoding SNAP23, galectin-3, and GUK-1 by 62, 63, and 99%, respectively. Knockdown of galectin-3 and SNAP23, but not GUK-1, significantly reduced Act-induced apoptosis of host cells, as determined by TUNEL (TdT-mediated dUTP nick end labeling) assay, lactate dehydrogenase release, Giemsa staining, and reduction in activation of caspase 3, compared to toxin-treated macrophages that were transfected with a random sequence control siRNA. We also performed these assays using a human intestinal epithelial cell line (HT-29) and observed a similar trend of galectin-3 and SNAP23 association with Act-induced apoptosis. This is the first report of putative protein binding partners for this toxin and potential mediators/regulators of Act-induced apoptosis.
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Affiliation(s)
- C L Galindo
- Department of Microbiology and Immunology, The University of Texas Medical Branch, Medical Research Building, 301 University Boulevard, Galveston, Texas 77555-1070, USA
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Current Awareness on Comparative and Functional Genomics. Comp Funct Genomics 2005. [PMCID: PMC2447491 DOI: 10.1002/cfg.425] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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