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Resko ZJ, Suhi RF, Thota AV, Kroken AR. Evidence for intracellular Pseudomonas aeruginosa. J Bacteriol 2024; 206:e0010924. [PMID: 38597609 PMCID: PMC11112991 DOI: 10.1128/jb.00109-24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/11/2024] Open
Abstract
Pseudomonas aeruginosa is a significant cause of global morbidity and mortality. Although it is often regarded as an extracellular pathogen toward human cells, numerous investigations report its ability to survive and replicate within host cells, and additional studies demonstrate specific mechanisms enabling it to adopt an intracellular lifestyle. This ability of P. aeruginosa remains less well-investigated than that of other intracellular bacteria, although it is currently gaining attention. If intracellular bacteria are not killed after entering host cells, they may instead receive protection from immune recognition and experience reduced exposure to antibiotic therapy, among additional potential advantages shared with other facultative intracellular pathogens. For this review, we compiled studies that observe intracellular P. aeruginosa across strains, cell types, and experimental systems in vitro, as well as contextualize these findings with the few studies that report similar observations in vivo. We also seek to address key findings that drove the perception that P. aeruginosa remains extracellular in order to reconcile what is currently understood about intracellular pathogenesis and highlight open questions regarding its contribution to disease.
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Affiliation(s)
- Zachary J. Resko
- Department of Microbiology and Immunology, Loyola University Chicago, Maywood, Illinois, USA
| | - Rachel F. Suhi
- Department of Microbiology and Immunology, Loyola University Chicago, Maywood, Illinois, USA
| | - Adam V. Thota
- Department of Microbiology and Immunology, Loyola University Chicago, Maywood, Illinois, USA
| | - Abby R. Kroken
- Department of Microbiology and Immunology, Loyola University Chicago, Maywood, Illinois, USA
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Kroken AR, Klein KA, Mitchell PS, Nieto V, Jedel EJ, Evans DJ, Fleiszig SMJ. Intracellular replication of Pseudomonas aeruginosa in epithelial cells requires suppression of the caspase-4 inflammasome. mSphere 2023; 8:e0035123. [PMID: 37589460 PMCID: PMC10597407 DOI: 10.1128/msphere.00351-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2023] [Accepted: 06/30/2023] [Indexed: 08/18/2023] Open
Abstract
Pathogenesis of Pseudomonas aeruginosa infections can include bacterial survival inside epithelial cells. Previously, we showed that this involves multiple roles played by the type three secretion system (T3SS), and specifically the effector ExoS. This includes ExoS-dependent inhibition of a lytic host cell response that subsequently enables intracellular replication. Here, we studied the underlying cell death response to intracellular P. aeruginosa, comparing wild-type to T3SS mutants varying in capacity to induce cell death and that localize to different intracellular compartments. Results showed that corneal epithelial cell death induced by intracellular P. aeruginosa lacking the T3SS, which remains in vacuoles, correlated with the activation of nuclear factor-κB as measured by p65 relocalization and tumor necrosis factor alpha transcription and secretion. Deletion of caspase-4 through CRISPR-Cas9 mutagenesis delayed cell death caused by these intracellular T3SS mutants. Caspase-4 deletion also countered more rapid cell death caused by T3SS effector-null mutants still expressing the T3SS apparatus that traffic to the host cell cytoplasm, and in doing so rescued intracellular replication normally dependent on ExoS. While HeLa cells lacked a lytic death response to T3SS mutants, it was found to be enabled by interferon gamma treatment. Together, these results show that epithelial cells can activate the noncanonical inflammasome pathway to limit proliferation of intracellular P. aeruginosa, not fully dependent on bacterially driven vacuole escape. Since ExoS inhibits the lytic response, the data implicate targeting of caspase-4, an intracellular pattern recognition receptor, as another contributor to the role of ExoS in the intracellular lifestyle of P. aeruginosa. IMPORTANCE Pseudomonas aeruginosa can exhibit an intracellular lifestyle within epithelial cells in vivo and in vitro. The type three secretion system (T3SS) effector ExoS contributes via multiple mechanisms, including extending the life of invaded host cells. Here, we aimed to understand the underlying cell death inhibited by ExoS when P. aeruginosa is intracellular. Results showed that intracellular P. aeruginosa lacking T3SS effectors could elicit rapid cell lysis via the noncanonical inflammasome pathway. Caspase-4 contributed to cell lysis even when the intracellular bacteria lacked the entire T33S and were consequently unable to escape vacuoles, representing a naturally occurring subpopulation during wild-type infection. Together, the data show the caspase-4 inflammasome as an epithelial cell defense against intracellular P. aeruginosa, and implicate its targeting as another mechanism by which ExoS preserves the host cell replicative niche.
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Affiliation(s)
- Abby R. Kroken
- Department of Microbiology and Immunology, Loyola University Chicago, Maywood, Illinois, USA
- Herbert Wertheim School of Optometry & Vision Science, University of California, Berkeley, California, USA
| | - Keith A. Klein
- Department of Microbiology and Immunology, Loyola University Chicago, Maywood, Illinois, USA
| | - Patrick S. Mitchell
- Department of Microbiology, University of Washington, Seattle, Washington, USA
| | - Vincent Nieto
- Herbert Wertheim School of Optometry & Vision Science, University of California, Berkeley, California, USA
| | - Eric J. Jedel
- Herbert Wertheim School of Optometry & Vision Science, University of California, Berkeley, California, USA
| | - David J. Evans
- Herbert Wertheim School of Optometry & Vision Science, University of California, Berkeley, California, USA
- College of Pharmacy, Touro University California, Vallejo, California, USA
| | - Suzanne M. J. Fleiszig
- Herbert Wertheim School of Optometry & Vision Science, University of California, Berkeley, California, USA
- Graduate Groups in Vision Sciences, Microbiology, and Infectious Diseases & Immunity, University of California, Berkeley, California, USA
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Kroken AR, Klein KA, Mitchell PS, Nieto V, Jedel EJ, Evans DJ, Fleiszig SMJ. Intracellular replication of Pseudomonas aeruginosa in epithelial cells requires suppression of the caspase-4 inflammasome. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.02.13.528260. [PMID: 36824932 PMCID: PMC9948977 DOI: 10.1101/2023.02.13.528260] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/15/2023]
Abstract
Pathogenesis of Pseudomonas aeruginosa infections can include bacterial survival inside epithelial cells. Previously, we showed this involves multiple roles played by the type three-secretion system (T3SS), and specifically the effector ExoS. This includes ExoS-dependent inhibition of a lytic host cell response that subsequently enables intracellular replication. Here, we studied the underlying cell death response to intracellular P. aeruginosa, comparing wild-type to T3SS mutants varying in capacity to induce cell death and that localize to different intracellular compartments. Results showed that corneal epithelial cell death induced by intracellular P. aeruginosa lacking the T3SS, which remains in vacuoles, correlated with activation of NF-κB as measured by p65 relocalization and TNFα transcription and secretion. Deletion of caspase-4 through CRISPR-Cas9 mutagenesis delayed cell death caused by these intracellular T3SS mutants. Caspase-4 deletion also countered more rapid cell death caused by T3SS effector-null mutants still expressing the TSSS apparatus that traffic to the host cell cytoplasm, and in doing so rescued intracellular replication normally dependent on ExoS. While HeLa cells lacked a lytic death response to T3SS mutants, it was found to be enabled by interferon gamma treatment. Together, these results show that epithelial cells can activate the noncanonical inflammasome pathway to limit proliferation of intracellular P. aeruginosa, not fully dependent on bacterially-driven vacuole escape. Since ExoS inhibits the lytic response, the data implicate targeting of caspase-4, an intracellular pattern recognition receptor, as another contributor to the role of ExoS in the intracellular lifestyle of P. aeruginosa.
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Affiliation(s)
- Abby R Kroken
- Department of Microbiology and Immunology, Loyola University Chicago, Maywood, IL USA
- Herbert Wertheim School of Optometry & Vision Science, University of California, Berkeley, CA USA
| | - Keith A Klein
- Department of Microbiology and Immunology, Loyola University Chicago, Maywood, IL USA
| | | | - Vincent Nieto
- Herbert Wertheim School of Optometry & Vision Science, University of California, Berkeley, CA USA
| | - Eric J Jedel
- Herbert Wertheim School of Optometry & Vision Science, University of California, Berkeley, CA USA
| | - David J Evans
- Herbert Wertheim School of Optometry & Vision Science, University of California, Berkeley, CA USA
- College of Pharmacy, Touro University California, Vallejo, CA USA
| | - Suzanne M J Fleiszig
- Herbert Wertheim School of Optometry & Vision Science, University of California, Berkeley, CA USA
- Graduate Groups in Vision Sciences, Microbiology, and Infectious Diseases & Immunity, University of California, Berkeley, CA USA
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Englisch CN, Wadood NA, Pätzold L, Gallagher A, Krasteva-Christ G, Becker SL, Bischoff M. Establishing an Experimental Pseudomonas aeruginosa Keratitis Model in Mice - Challenges and Solutions. Ann Anat 2023; 249:152099. [PMID: 37105406 DOI: 10.1016/j.aanat.2023.152099] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2023] [Revised: 03/27/2023] [Accepted: 03/28/2023] [Indexed: 04/29/2023]
Abstract
BACKGROUND With the ongoing increase in antimicrobial resistances seen in bacterial isolates causing a keratitis in humans, animal models have become an important tool to study new antimicrobial therapies. Nevertheless, the establishment of experimental keratitis is difficult. Here, we discuss the impact of different arrangements, including animal age, bacterial strain and dose as well as epithelium removal on the outcome of experimental keratitis. We therefore present the methods and results of our establishing experiments. METHODS Bacterial load determination and flow cytometry were performed using eye homogenate gained from a 72hours lasting murine Pseudomonas aeruginosa keratitis model. Additionally, the intensity of the infection was scored from 0 to 5, the mice weighed, and blood immune cells counted. RESULTS We found that older C57BL/6N mice (8-11 months) are more susceptible to develop a keratitis than younger mice (5-6 weeks). Epithelium removal has no major impact on infectivity and disease progression in aged mice. P. aeruginosa exoU+ strains, such as PA54, should preferentially be used and highly concentrated (∼ 5×107 CFU). Establishing an infection with the exoU- PAO1 derivative DSM 19880 was not possible. CONCLUSIONS We present a replicable method to achieve a successful experimental P. aeruginosa keratitis in C57BL/6N mice that is sustained or aggravated over the observation period of 3 days in 80% of all animals tested. Our work is of particular interest to all researchers planning the establishment of such experimental models. We show some key aspects that can simplify and quicken the procedure, ultimately saving costs and animal life.
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Affiliation(s)
- Colya N Englisch
- Institute for Medical Microbiology and Hygienics, Saarland University, 66421, Homburg/Saar, Germany.
| | - Noran Abdel Wadood
- Institute for Medical Microbiology and Hygienics, Saarland University, 66421, Homburg/Saar, Germany; Institute of Anatomy and Cell Biology, Saarland University, 66421, Homburg/Saar, Germany.
| | - Linda Pätzold
- Institute for Medical Microbiology and Hygienics, Saarland University, 66421, Homburg/Saar, Germany.
| | | | | | - Sören L Becker
- Institute for Medical Microbiology and Hygienics, Saarland University, 66421, Homburg/Saar, Germany.
| | - Markus Bischoff
- Institute for Medical Microbiology and Hygienics, Saarland University, 66421, Homburg/Saar, Germany.
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Ramadan A, Cao Z, Hassan M, Zetterberg F, Nilsson UJ, Gadjeva M, Rathinam V, Panjwani N. Galectin-8 Downmodulates TLR4 Activation and Impairs Bacterial Clearance in a Mouse Model of Pseudomonas aeruginosa Keratitis. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2023; 210:398-407. [PMID: 36603009 PMCID: PMC9898164 DOI: 10.4049/jimmunol.2200706] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/20/2022] [Accepted: 11/15/2022] [Indexed: 01/06/2023]
Abstract
Pseudomonas aeruginosa provokes a painful, sight-threatening corneal infection. It progresses rapidly and is difficult to treat. In this study, using a mouse model of P. aeruginosa keratitis, we demonstrate the importance of a carbohydrate-binding protein, galectin-8 (Gal-8), in regulation of the innate immune response. First, using two distinct strains of P. aeruginosa, we established that Gal-8-/- mice are resistant to P. aeruginosa keratitis. In contrast, mice deficient in Gal-1, Gal-3, and Gal-9 were fully susceptible. Second, the addition of exogenous rGal-8 to LPS (TLR4 ligand)-stimulated bone marrow-derived macrophages suppressed 1) the activation of the NF-κB pathway, and 2) formation of the MD-2/TLR4 complex. Additionally, the expression level of reactive oxygen species was substantially higher in infected Gal-8-/- bone marrow neutrophils (BMNs) compared with the Gal-8+/+ BMNs, and the P. aeruginosa killing capacity of Gal-8-/- BMNs was considerably higher compared with that of Gal-8+/+ BMNs. In the bacterial killing assays, the addition of exogenous rGal-8 almost completely rescued the phenotype of Gal-8-/- BMNs. Finally, we demonstrate that a subconjunctival injection of a Gal-8 inhibitor markedly reduces the severity of infection in the mouse model of P. aeruginosa keratitis. These data lead us to conclude that Gal-8 downmodulates the innate immune response by suppressing activation of the TLR4 pathway and clearance of P. aeruginosa by neutrophils. These findings have broad implications for developing novel therapeutic strategies for treatment of conditions resulting from the hyperactive immune response both in ocular as well as nonocular tissues.
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Affiliation(s)
- Abdulraouf Ramadan
- New England Eye Center/Department of Ophthalmology, Tufts University School of Medicine, Boston, MA. 02111, USA
| | - Zhiyi Cao
- New England Eye Center/Department of Ophthalmology, Tufts University School of Medicine, Boston, MA. 02111, USA
| | - Mujtaba Hassan
- Centre for Analysis and Synthesis, Department of Chemistry, Lund University, Lund, Sweden
| | | | - Ulf J. Nilsson
- Centre for Analysis and Synthesis, Department of Chemistry, Lund University, Lund, Sweden
| | - Mihaela Gadjeva
- Department of Medicine, Division of Infectious Diseases, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA. 02115, USA
| | - Vijay Rathinam
- Department of Immunology, UConn Health School of Medicine, Farmington, CT
| | - Noorjahan Panjwani
- New England Eye Center/Department of Ophthalmology, Tufts University School of Medicine, Boston, MA. 02111, USA
- Department of Developmental, Molecular and Chemical Biology, Tufts University School of Medicine, Boston, MA, 02111, USA
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Pseudomonas aeruginosa Can Diversify after Host Cell Invasion to Establish Multiple Intracellular Niches. mBio 2022; 13:e0274222. [PMID: 36374039 PMCID: PMC9765609 DOI: 10.1128/mbio.02742-22] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Within epithelial cells, Pseudomonas aeruginosa depends on its type III secretion system (T3SS) to escape vacuoles and replicate rapidly in the cytosol. Previously, it was assumed that intracellular subpopulations remaining T3SS-negative (and therefore in vacuoles) were destined for degradation in lysosomes, supported by data showing vacuole acidification. Here, we report in both corneal and bronchial human epithelial cells that vacuole-associated bacteria can persist, sometimes in the same cells as cytosolic bacteria. Using a combination of phase-contrast, confocal, and correlative light-electron microscopy (CLEM), we also found they can demonstrate biofilm-associated markers: cdrA and cyclic-di-GMP (c-di-GMP). Vacuolar-associated bacteria, but not their cytosolic counterparts, tolerated the cell-permeable antibiotic ofloxacin. Surprisingly, use of mutants showed that both persistence in vacuoles and ofloxacin tolerance were independent of the biofilm-associated protein CdrA or exopolysaccharides (Psl, Pel, alginate). A T3SS mutant (ΔexsA) unable to escape vacuoles phenocopied vacuole-associated subpopulations in wild-type PAO1-infected cells, with results revealing that epithelial cell death depended upon bacterial viability. Intravital confocal imaging of infected mouse corneas confirmed that P. aeruginosa formed similar intracellular subpopulations within epithelial cells in vivo. Together, these results show that P. aeruginosa differs from other pathogens by diversifying intracellularly into vacuolar and cytosolic subpopulations that both contribute to pathogenesis. Their different gene expression and behavior (e.g., rapid replication versus slow replication/persistence) suggest cooperation favoring both short- and long-term interests and another potential pathway to treatment failure. How this intracellular diversification relates to previously described "acute versus chronic" virulence gene-expression phenotypes of P. aeruginosa remains to be determined. IMPORTANCE Pseudomonas aeruginosa can cause sight- and life-threatening opportunistic infections, and its evolving antibiotic resistance is a growing concern. Most P. aeruginosa strains can invade host cells, presenting a challenge to therapies that do not penetrate host cell membranes. Previously, we showed that the P. aeruginosa type III secretion system (T3SS) plays a pivotal role in survival within epithelial cells, allowing escape from vacuoles, rapid replication in the cytoplasm, and suppression of host cell death. Here, we report the discovery of a novel T3SS-negative subpopulation of intracellular P. aeruginosa within epithelial cells that persist in vacuoles rather than the cytoplasm and that tolerate a cell-permeable antibiotic (ofloxacin) that is able to kill cytosolic bacteria. Classical biofilm-associated markers, although demonstrated by this subpopulation, are not required for vacuolar persistence or antibiotic tolerance. These findings advance our understanding of how P. aeruginosa hijacks host cells, showing that it diversifies into multiple populations with T3SS-negative members enabling persistence while rapid replication is accomplished by more vulnerable T3SS-positive siblings. Intracellular P. aeruginosa persisting and tolerating antibiotics independently of the T3SS or biofilm-associated factors could present additional challenges to development of more effective therapeutics.
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A Model of Intracellular Persistence of Pseudomonas aeruginosa in Airway Epithelial Cells. Cell Microbiol 2022. [DOI: 10.1155/2022/5431666] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Pseudomonas aeruginosa (P.a.) is a major human pathogen capable of causing chronic infections in hosts with weakened barrier functions and host defenses, most notably airway infections commonly observed in individuals with the genetic disorder cystic fibrosis (CF). While mainly described as an extracellular pathogen, previous in vitro studies have described the molecular events leading to P.a. internalization in diverse epithelial cell types. However, the long-term fate of intracellular P.a. remains largely unknown. Here, we developed a model allowing for a better understanding of long-term (up to 120 h) intracellular bacterial survival in the airway epithelial cell line BEAS-2B. Using a tobramycin protection assay, we characterized the internalization, long-term intracellular survival, and cytotoxicity of the lab strain PAO1, as well as clinical CF isolates, and conducted analyses at the single-cell level using confocal microscopy and flow cytometry techniques. We observed that infection at low multiplicity of infection allows for intracellular survival up to 120 h post-infection without causing significant host cytotoxicity. Finally, infection with clinical isolates revealed significant strain-to-strain heterogeneity in intracellular survival, including a high persistence phenotype associated with bacterial replication within host cells. Future studies using this model will further elucidate the host and bacterial mechanisms that promote P. aeruginosa intracellular persistence in airway epithelial cells, a potentially unrecognized bacterial reservoir during chronic infections.
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Paškevičius Š, Dapkutė V, Misiūnas A, Balzaris M, Thommes P, Sattar A, Gleba Y, Ražanskienė A. Chimeric bacteriocin S5-PmnH engineered by domain swapping efficiently controls Pseudomonas aeruginosa infection in murine keratitis and lung models. Sci Rep 2022; 12:5865. [PMID: 35440606 PMCID: PMC9018753 DOI: 10.1038/s41598-022-09865-8] [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: 01/13/2022] [Accepted: 03/22/2022] [Indexed: 11/29/2022] Open
Abstract
Rampant rise of multidrug resistant strains among Gram-negative bacteria has necessitated investigation of alternative antimicrobial agents with novel modes of action including antimicrobial proteins such as bacteriocins. The main hurdle in the clinical development of bacteriocin biologics is their narrow specificity and limited strain activity spectrum. Genome mining of bacteria for broadly active bacteriocins have identified a number of promising candidates but attempts to improve these natural multidomain proteins further, for example by combining domains of different origin, have so far met with limited success. We have found that domain swapping of Pseudomonas bacteriocins of porin type, when carried out between phylogenetically related molecules with similar mechanism of activity, allows the generation of highly active molecules with broader spectrum of activity, for example by abolishing strain resistance due to the presence of immunity proteins. The most broadly active chimera engineered in this study, S5-PmnH, exhibits excellent control of Pseudomonas aeruginosa infection in validated murine keratitis and lung infection models.
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Affiliation(s)
- Šarūnas Paškevičius
- Nomads UAB, Geležinio vilko 29A, 01112, Vilnius, Lithuania.,Institute of Biotechnology, Vilnius University, Saulėtekio al. 7, 10257, Vilnius, Lithuania
| | - Viktorija Dapkutė
- Nomads UAB, Geležinio vilko 29A, 01112, Vilnius, Lithuania.,Institute of Biotechnology, Vilnius University, Saulėtekio al. 7, 10257, Vilnius, Lithuania
| | | | | | - Pia Thommes
- Evotec (UK) Ltd., Block 23, Alderley Park, Macclesfield, SK10 4TG, Cheshire, UK
| | - Abdul Sattar
- Evotec (UK) Ltd., Block 23, Alderley Park, Macclesfield, SK10 4TG, Cheshire, UK
| | - Yuri Gleba
- Nomad Bioscience GmbH, Biozentrum Halle, Weinbergweg 22, 06120, Halle (Saale), Germany
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Kroken AR, Gajenthra Kumar N, Yahr TL, Smith BE, Nieto V, Horneman H, Evans DJ, Fleiszig SMJ. Exotoxin S secreted by internalized Pseudomonas aeruginosa delays lytic host cell death. PLoS Pathog 2022; 18:e1010306. [PMID: 35130333 PMCID: PMC8853526 DOI: 10.1371/journal.ppat.1010306] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2021] [Revised: 02/17/2022] [Accepted: 01/25/2022] [Indexed: 12/22/2022] Open
Abstract
The Pseudomonas aeruginosa toxin ExoS, secreted by the type III secretion system (T3SS), supports intracellular persistence via its ADP-ribosyltransferase (ADPr) activity. For epithelial cells, this involves inhibiting vacuole acidification, promoting vacuolar escape, countering autophagy, and niche construction in the cytoplasm and within plasma membrane blebs. Paradoxically, ExoS and other P. aeruginosa T3SS effectors can also have antiphagocytic and cytotoxic activities. Here, we sought to reconcile these apparently contradictory activities of ExoS by studying the relationships between intracellular persistence and host epithelial cell death. Methods involved quantitative imaging and the use of antibiotics that vary in host cell membrane permeability to selectively kill intracellular and extracellular populations after invasion. Results showed that intracellular P. aeruginosa mutants lacking T3SS effector toxins could kill (permeabilize) cells when extracellular bacteria were eliminated. Surprisingly, wild-type strain PAO1 (encoding ExoS, ExoT and ExoY) caused cell death more slowly, the time extended from 5.2 to 9.5 h for corneal epithelial cells and from 10.2 to 13.0 h for HeLa cells. Use of specific mutants/complementation and controls for initial invasion showed that ExoS ADPr activity delayed cell death. Triggering T3SS expression only after bacteria invaded cells using rhamnose-induction in T3SS mutants rescued the ExoS-dependent intracellular phenotype, showing that injected effectors from extracellular bacteria were not required. The ADPr activity of ExoS was further found to support internalization by countering the antiphagocytic activity of both the ExoS and ExoT RhoGAP domains. Together, these results show two additional roles for ExoS ADPr activity in supporting the intracellular lifestyle of P. aeruginosa; suppression of host cell death to preserve a replicative niche and inhibition of T3SS effector antiphagocytic activities to allow invasion. These findings add to the growing body of evidence that ExoS-encoding (invasive) P. aeruginosa strains can be facultative intracellular pathogens, and that intracellularly secreted T3SS effectors contribute to pathogenesis. While the ADPr domain of the T3SS effector ExoS plays multiple roles in the intracellular lifestyle of P. aeruginosa, ExoS can also be cytotoxic and/or antiphagocytic. Here, we show that when P. aeruginosa enters the cytosol of epithelial cells, cell death is triggered independently of T3SS effector toxins, but ExoS ADPr activity delays this to enable continued intracellular survival and replication. Using rhamnose induction to express the T3SS only after invasion restored this ExoS-dependent phenotype, showing that intracellularly secreted effectors can enable intracellular pathogenesis. ExoS ADPr activity also countered antiphagocytic activity of ExoS and ExoT RhoGAP domains. These results show two additional roles for ExoS ADPr activity in promoting internalization of P. aeruginosa and protecting the intracellular niche, continuing to challenge the notions that P. aeruginosa is exclusively an extracellular pathogen, that it needs to inject T3SS effectors across plasma membranes, and that ExoS is necessarily cytotoxic to host cells.
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Affiliation(s)
- Abby R. Kroken
- School of Optometry, University of California, Berkeley, Berkeley, California, United States of America
- Department of Microbiology and Immunology, Loyola University Chicago, Maywood, Illinois, United States of America
| | - Naren Gajenthra Kumar
- School of Optometry, University of California, Berkeley, Berkeley, California, United States of America
| | - Timothy L. Yahr
- Department of Microbiology and Immunology, University of Iowa, Iowa City, Iowa, United States of America
| | - Benjamin E. Smith
- Vision Science Program, University of California, Berkeley, Berkeley, California, United States of America
| | - Vincent Nieto
- School of Optometry, University of California, Berkeley, Berkeley, California, United States of America
| | - Hart Horneman
- School of Optometry, University of California, Berkeley, Berkeley, California, United States of America
| | - David J. Evans
- School of Optometry, University of California, Berkeley, Berkeley, California, United States of America
- College of Pharmacy, Touro University California, Vallejo, California, United States of America
| | - Suzanne M. J. Fleiszig
- School of Optometry, University of California, Berkeley, Berkeley, California, United States of America
- Vision Science Program, University of California, Berkeley, Berkeley, California, United States of America
- Graduate Groups in Microbiology, and Infectious Diseases & Immunity, University of California, Berkeley, Berkeley, California, United States of America
- * E-mail:
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Fakhkhari P, Tajeddin E, Azimirad M, Salmanzadeh-Ahrabi S, Abdi-Ali A, Nikmanesh B, Eshrati B, Gouya MM, Owlia P, Zali MR, Alebouyeh M. Involvement of Pseudomonas aeruginosa in the occurrence of community and hospital acquired diarrhea, and its virulence diversity among the stool and the environmental samples. INTERNATIONAL JOURNAL OF ENVIRONMENTAL HEALTH RESEARCH 2022; 32:61-71. [PMID: 32073302 DOI: 10.1080/09603123.2020.1726300] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/11/2019] [Accepted: 02/03/2020] [Indexed: 06/10/2023]
Abstract
Transmission of Pseudomonas aeruginosa along the food chain could cause gastrointestinal infections. To show this involvement, the prevalence, putative virulence genotype, and antibiotic resistance phenotype of P. aeruginosa isolates from stool of 1482 patients with community and hospital acquired diarrhea were compared with 87 isolates from the environmental samples. The results showed infection with P. aeruginosa in 3.4% of the cases, while 57.4% of vegetable samples were contaminated. Significantly higher frequency of lasB (98%), aprA (98%), exoY (98%), and exoS (90%), but lower rate of exoT (39.2%), was detected among the stool isolates. Multi-drug resistance (MDR) phenotype was detected in 25.5% and 4% of the stool and vegetable isolates, respectively. A higher rate of studied virulence genes was detected among the MDR strains vs non-MDR strains. These results indicate P. aeruginosa as a causative agent of diarrhea either among the hospitalized patients and those with community-acquired diarrhea.
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Affiliation(s)
- Parisa Fakhkhari
- Department of Microbiology, Faculty of Biological Sciences, Alzahra University, Tehran, Iran
| | - Elahe Tajeddin
- Foodborne and Waterborne Diseases Research Center, Research Institute for Gastroenterology and Liver Diseases, Shahid Beheshti University of Medical Sciences, Tehran, Iran
- National Nutrition and Food Technology Research Institute, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Masoumeh Azimirad
- Foodborne and Waterborne Diseases Research Center, Research Institute for Gastroenterology and Liver Diseases, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | | | - Ahya Abdi-Ali
- Department of Microbiology, Faculty of Biological Sciences, Alzahra University, Tehran, Iran
| | - Bahram Nikmanesh
- Department of Medical Laboratory Sciences, School of Allied Medical Sciences, Tehran University of Medical Sciences, Tehran, Iran
| | - Babak Eshrati
- Center for Communicable Disease Control, Ministry of Health and Medical Education, Tehran, Iran
| | - Mohammad Mehdi Gouya
- Center for Communicable Disease Control, Ministry of Health and Medical Education, Tehran, Iran
| | - Parviz Owlia
- Molecular Microbiology Research Center (MMRC), Shahed University, Tehran, Iran
| | - Mohammad Reza Zali
- Gastroenterology and Liver Diseases Research Center, Research Institute for Gastroenterology and Liver Diseases, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Masoud Alebouyeh
- Foodborne and Waterborne Diseases Research Center, Research Institute for Gastroenterology and Liver Diseases, Shahid Beheshti University of Medical Sciences, Tehran, Iran
- Pediatric Infections Research Center, Research Institute for Children's Health, Shahid Beheshti University of Medical Sciences, Tehran, Iran
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Shen E, Yang J, Tsuei KSC. The role of Type III secretion system in the pathogenesis of Pseudomonas aeruginosa microbial keratitis. Tzu Chi Med J 2022; 34:8-14. [PMID: 35233350 PMCID: PMC8830546 DOI: 10.4103/tcmj.tcmj_47_21] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2021] [Revised: 03/11/2021] [Accepted: 03/17/2021] [Indexed: 11/22/2022] Open
Abstract
Pseudomonas aeruginosa is the most commonly isolated Gram-negative pathogen causing sight-threatening microbial keratitis (MK). Contact lens wear is the most significant risk factor associated with pseudomonal MK. Understanding the pathogenesis of MK due to P. aeruginosa and its interactions with contact lenses is crucial in preventing these often rapidly progressive and highly antibiotic-resistant infections. Bacterial virulence factor Type III secretion system (T3SS) has significant interplays between contact lens material, antibiotic sensitivity, disinfectant selectivity, and bacterial cell invasion. Depending on the T3SS exotoxins produced, P. aeruginosa strains are divided into cytotoxic or invasive strains. Cytotoxic strains are relatively resistant to commercial disinfectants, while invasive strains are more antibiotic resistant. Therefore, contact lens wearers are more predisposed to cytotoxic P. aeruginosa infections, and patients with trauma or previous surgery are more prone to infection by invasive strains. Previous studies with mutant P. aeruginosa strains unable to produce T3SS exotoxins were more susceptible to disinfectants and less able to adhere to soft contact lenses, indicating an essential role of T3SS in bacterial virulence. Invasion of P. aeruginosa intracellularly was found to be associated with control of scaffold protein IQ-domain GTPase-activating protein 1 (IQGAP1) and human corneal epithelial cell tight junctions. Knockdown of IQGAP1 strengthened tight junctions that prevented intracellular survival of invasive P. aeruginosa strains and enhanced corneal epithelial cell survival. These novel findings of the vital role of T3SS in the pathogenesis of pseudomonal MKs will provide new guidelines in both prevention and treatment of this common eye-blinding infection.
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Potential Therapeutic Targets for Combination Antibody Therapy against Pseudomonas aeruginosa Infections. Antibiotics (Basel) 2021; 10:antibiotics10121530. [PMID: 34943742 PMCID: PMC8698887 DOI: 10.3390/antibiotics10121530] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2021] [Revised: 12/03/2021] [Accepted: 12/09/2021] [Indexed: 12/12/2022] Open
Abstract
Despite advances in antimicrobial therapy and even the advent of some effective vaccines, Pseudomonas aeruginosa (P. aeruginosa) remains a significant cause of infectious disease, primarily due to antibiotic resistance. Although P. aeruginosa is commonly treatable with readily available therapeutics, these therapies are not always efficacious, particularly for certain classes of patients (e.g., cystic fibrosis (CF)) and for drug-resistant strains. Multi-drug resistant P. aeruginosa infections are listed on both the CDC’s and WHO’s list of serious worldwide threats. This increasing emergence of drug resistance and prevalence of P. aeruginosa highlights the need to identify new therapeutic strategies. Combinations of monoclonal antibodies against different targets and epitopes have demonstrated synergistic efficacy with each other as well as in combination with antimicrobial agents typically used to treat these infections. Such a strategy has reduced the ability of infectious agents to develop resistance. This manuscript details the development of potential therapeutic targets for polyclonal antibody therapies to combat the emergence of multidrug-resistant P. aeruginosa infections. In particular, potential drug targets for combinational immunotherapy against P. aeruginosa are identified to combat current and future drug resistance.
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Ramírez-Granillo A, Bautista-Hernández LA, Bautista-De Lucío VM, Magaña-Guerrero FS, Domínguez-López A, Córdova-Alcántara IM, Pérez NO, Martínez-Rivera MDLA, Rodríguez-Tovar AV. Microbial Warfare on Three Fronts: Mixed Biofilm of Aspergillus fumigatus and Staphylococcus aureus on Primary Cultures of Human Limbo-Corneal Fibroblasts. Front Cell Infect Microbiol 2021; 11:646054. [PMID: 34485167 PMCID: PMC8415486 DOI: 10.3389/fcimb.2021.646054] [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: 12/24/2020] [Accepted: 07/19/2021] [Indexed: 11/08/2022] Open
Abstract
Background Coinfections with fungi and bacteria in ocular pathologies are increasing at an alarming rate. Two of the main etiologic agents of infections on the corneal surface, such as Aspergillus fumigatus and Staphylococcus aureus, can form a biofilm. However, mixed fungal–bacterial biofilms are rarely reported in ocular infections. The implementation of cell cultures as a study model related to biofilm microbial keratitis will allow understanding the pathogenesis in the cornea. The cornea maintains a pathogen-free ocular surface in which human limbo-corneal fibroblast cells are part of its cell regeneration process. There are no reports of biofilm formation assays on limbo-corneal fibroblasts, as well as their behavior with a polymicrobial infection. Objective To determine the capacity of biofilm formation during this fungal–bacterial interaction on primary limbo-corneal fibroblast monolayers. Results The biofilm on the limbo-corneal fibroblast culture was analyzed by assessing biomass production and determining metabolic activity. Furthermore, the mixed biofilm effect on this cell culture was observed with several microscopy techniques. The single and mixed biofilm was higher on the limbo-corneal fibroblast monolayer than on abiotic surfaces. The A. fumigatus biofilm on the human limbo-corneal fibroblast culture showed a considerable decrease compared to the S. aureus biofilm on the limbo-corneal fibroblast monolayer. Moreover, the mixed biofilm had a lower density than that of the single biofilm. Antibiosis between A. fumigatus and S. aureus persisted during the challenge to limbo-corneal fibroblasts, but it seems that the fungus was more effectively inhibited. Conclusion This is the first report of mixed fungal–bacterial biofilm production and morphological characterization on the limbo-corneal fibroblast monolayer. Three antibiosis behaviors were observed between fungi, bacteria, and limbo-corneal fibroblasts. The mycophagy effect over A. fumigatus by S. aureus was exacerbated on the limbo-corneal fibroblast monolayer. During fungal–bacterial interactions, it appears that limbo-corneal fibroblasts showed some phagocytic activity, demonstrating tripartite relationships during coinfection.
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Affiliation(s)
- Adrián Ramírez-Granillo
- Medical Mycology Laboratory, National School of Biological Sciences (ENCB)-Instituto Politécnico Nacional (IPN), Department of Microbiology, Mexico City, Mexico
| | - Luis Antonio Bautista-Hernández
- Ocular Microbiology and Proteomics Laboratory, Research Unit, "Conde de Valenciana Private Assistance Foundation", Mexico City, Mexico
| | - Víctor Manuel Bautista-De Lucío
- Ocular Microbiology and Proteomics Laboratory, Research Unit, "Conde de Valenciana Private Assistance Foundation", Mexico City, Mexico
| | - Fátima Sofía Magaña-Guerrero
- Cell Biology and Amniotic Membrane Laboratory, Research Unit, "Conde de Valenciana Private Assistance Foundation", Mexico City, Mexico
| | - Alfredo Domínguez-López
- Cell Biology and Amniotic Membrane Laboratory, Research Unit, "Conde de Valenciana Private Assistance Foundation", Mexico City, Mexico
| | - Itzel Margarita Córdova-Alcántara
- Medical Mycology Laboratory, National School of Biological Sciences (ENCB)-Instituto Politécnico Nacional (IPN), Department of Microbiology, Mexico City, Mexico
| | - Néstor O Pérez
- Research and Development Department Probiomed SA de CV, Tenancingo Edo de Mex, Mexico
| | - María de Los Angeles Martínez-Rivera
- Medical Mycology Laboratory, National School of Biological Sciences (ENCB)-Instituto Politécnico Nacional (IPN), Department of Microbiology, Mexico City, Mexico
| | - Aída Verónica Rodríguez-Tovar
- Medical Mycology Laboratory, National School of Biological Sciences (ENCB)-Instituto Politécnico Nacional (IPN), Department of Microbiology, Mexico City, Mexico
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Arshad M, Carnt N, Tan J, Stapleton F. Effect of Water Exposure on Contact Lens Storage Case Contamination in Soft Lens Wearers. Optom Vis Sci 2021; 98:1002-1010. [PMID: 34570032 DOI: 10.1097/opx.0000000000001772] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
SIGNIFICANCE Water exposure during contact lens wear can transfer pathogenic microorganisms to the eye, causing ocular complications. This study determined that water exposure is prevalent among lens wearers and is independently associated with higher case contamination. Contact lens compliance education to minimize water exposure should be reenforced by contact lens organizations and practitioners. PURPOSE Given the increasing association between water exposure and contact lens disease, this study aimed to explore the effect of water exposure and storage case contamination in soft contact lens users. METHODS A total of 165 daily soft lens wearers completed a self-administered questionnaire on contact lens hygiene. Lens cases were collected, and microbial analysis was conducted using an adenosine triphosphate assay (for overall microbial bioburden) and limulus amebocyte lysate assay (for endotoxin levels). The lens hygiene (excellent, >35; moderate, 28 to 35; poor, <28) and water contact (≤1, good; >1, poor) scores measured the compliance and water exposure during lens wear, respectively. Multiple regression determined the association between water behaviors and case contamination. RESULTS The average (standard deviation) age of participants was 28 (13.5) years (18 to 78 years), and 65% were female. The average overall microbial bioburden of storage cases was 3.10 (0.98) log colony-forming unit/mL (1.09 to 5.94 log colony-forming unit/mL). Forty-five percent of participants reported showering, 49.7% reported swimming while wearing lenses (65.4% of whom swam without goggles), 27.8% used wet hands to handle lenses, and 17.5% used tap water to rinse storage cases. Showering with lenses significantly increased the risk of higher storage case bioburden (P = .001), whereas using wet hands (P = .01) doubled the risk of higher case endotoxin levels (odds ratio, 2.41; confidence interval 1.19 to 4.86). CONCLUSIONS Water contact behavior while wearing lenses is prevalent among soft lens wearers and is associated with higher case contamination. Practitioners may improve contact lens education to reduce water exposure and case contamination to reduce the risk of lens-related adverse events.
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Affiliation(s)
- Memoona Arshad
- School of Optometry and Vision Science, University of New South Wales, Sydney, New South Wales, Australia
| | - Nicole Carnt
- School of Optometry and Vision Science, University of New South Wales, Sydney, New South Wales, Australia
| | - Jacqueline Tan
- School of Optometry and Vision Science, University of New South Wales, Sydney, New South Wales, Australia
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Abstract
PURPOSE To evaluate the antifungal properties of topical antibiotics (already being used successfully to prevent bacterial endophthalmitis) and some promising antiseptics for antifungal prophylaxis in the setting of artificial corneal implantation. METHODS Several commonly used antibiotics for antimicrobial prophylaxis after artificial corneal implantation, in addition to antiseptics [benzalkonium chloride (BAK), povidone-iodine (PI), and some ionic liquids (ILs)], were tested in vitro against Candida albicans, Fusarium solani, and Aspergillus fumigatus. The time-kill activity was determined. Toxicity was assayed in vitro on human corneal epithelial cultures using trypan blue. Adhesion and tissue invasion experiments were also carried out on porcine corneas and commonly used contact lenses, with or without gamma irradiation, and by analysis with fluorescence microscopy. RESULTS Polymyxin B (PMB)/trimethoprim/BAK (Polytrim), PMB alone, gatifloxacin with BAK (Zymaxid), and same-concentration BAK alone exhibited antifungal activity in vitro. Moxifloxacin (MOX) or gatifloxacin without BAK-as well as trimethoprim, vancomycin, and chloramphenicol-had no effect. 1% PI and ILs had the highest efficacy/toxicity ratios (>1), and Polytrim was species dependent. Subfungicidal concentrations of Polytrim reduced adhesion of C. albicans to Kontur contact lenses. Gamma-irradiated corneas showed enhanced resistance to fungal invasion. CONCLUSIONS Of antibiotic preparations already in use for bacterial prophylaxis after KPro surgery, Polytrim is a commonly used antibiotic with antifungal effects mediated by both PMB and BAK and may be sufficient for prophylaxis. PI as a 1% solution seems to be promising as a long-term antifungal agent. Choline-undecanoate IL is effective and virtually nontoxic and warrants further development.
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Ung L, Chodosh J. Foundational concepts in the biology of bacterial keratitis. Exp Eye Res 2021; 209:108647. [PMID: 34097906 PMCID: PMC8595513 DOI: 10.1016/j.exer.2021.108647] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2021] [Revised: 04/28/2021] [Accepted: 05/27/2021] [Indexed: 12/12/2022]
Abstract
Bacterial infections of the cornea, or bacterial keratitis (BK), are notorious for causing rapidly fulminant disease and permanent vision loss, even among treated patients. In the last sixty years, dramatic upward trajectories in the frequency of BK have been observed internationally, driven in large part by the commercialization of hydrogel contact lenses in the late 1960s. Despite this worsening burden of disease, current evidence-based therapies for BK - including broad-spectrum topical antibiotics and, if indicated, topical corticosteroids - fail to salvage vision in a substantial proportion of affected patients. Amid growing concerns of rapidly diminishing antibiotic utility, there has been renewed interest in urgently needed novel treatments that may improve clinical outcomes on an individual and public health level. Bridging the translational gap in the care of BK requires the identification of new therapeutic targets and rational treatment design, but neither of these aims can be achieved without understanding the complex biological processes that determine how bacterial corneal infections arise, progress, and resolve. In this chapter, we synthesize the current wealth of human and animal experimental data that now inform our understanding of basic BK pathophysiology, in context with modern concepts in ocular immunology and microbiology. By identifying the key molecular determinants of clinical disease, we explore how novel treatments can be developed and translated into routine patient care.
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Affiliation(s)
- Lawson Ung
- Department of Ophthalmology, Massachusetts Eye and Ear, Harvard Medical School, Boston, MA, USA; Infectious Disease Institute, Massachusetts Eye and Ear, Harvard Medical School, Boston, MA, USA; Department of Epidemiology, Harvard T. H. Chan School of Public Health, Boston, MA, USA
| | - James Chodosh
- Department of Ophthalmology, Massachusetts Eye and Ear, Harvard Medical School, Boston, MA, USA; Infectious Disease Institute, Massachusetts Eye and Ear, Harvard Medical School, Boston, MA, USA.
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Tabor LM, Grosser MR, Metruccio MMME, Kumar NG, Wu YT, Nieto V, Evans DJ, Fleiszig SMJ. Human tear fluid modulates the Pseudomonas aeruginosa transcriptome to alter antibiotic susceptibility. Ocul Surf 2021; 22:94-102. [PMID: 34332149 PMCID: PMC10139757 DOI: 10.1016/j.jtos.2021.07.004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2021] [Revised: 06/08/2021] [Accepted: 07/26/2021] [Indexed: 11/24/2022]
Abstract
PURPOSE Previously, we showed that tear fluid protects corneal epithelial cells against Pseudomonas aeruginosa without suppressing bacterial viability. Here, we studied how tear fluid affects bacterial gene expression. METHODS RNA-sequencing was used to study the P. aeruginosa transcriptome after tear fluid exposure (5 h, 37 oC). Outcomes were further investigated by biochemical and physiological perturbations to tear fluid and tear-like fluid (TLF) and assessment of bacterial viability following tear/TLF pretreatment and antibiotic exposure. RESULTS Tear fluid deregulated ~180 P. aeruginosa genes ≥8 fold versus PBS including downregulating lasI, rhlI, qscR (quorum sensing/virulence), oprH, phoP, phoQ (antimicrobial resistance) and arnBCADTEF (polymyxin B resistance). Upregulated genes included algF (biofilm formation) and hemO (iron acquisition). qPCR confirmed tear down-regulation of oprH, phoP and phoQ. Tear fluid pre-treatment increased P. aeruginosa resistance to meropenem ~5-fold (4 μg/ml), but enhanced polymyxin B susceptibility ~180-fold (1 μg/ml), the latter activity reduced by dilution in PBS. Media containing a subset of tear components (TLF) also sensitized bacteria to polymyxin B, but only ~22.5-fold, correlating with TLF/tear fluid Ca2+ and Mg2+ concentrations. Accordingly, phoQ mutants were not sensitized by TLF or tear fluid. Superior activity of tear fluid versus TLF against wild-type P. aeruginosa was heat resistant but proteinase K sensitive. CONCLUSION P. aeruginosa responds to human tear fluid by upregulating genes associated with bacterial survival and adaptation. Meanwhile, tear fluid down-regulates multiple virulence-associated genes. Tears also utilize divalent cations and heat resistant/proteinase K sensitive component(s) to enhance P. aeruginosa sensitivity to polymyxin B.
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Affiliation(s)
- Lauren M Tabor
- School of Optometry, University of California, Berkeley, CA, USA
| | | | | | - Naren G Kumar
- School of Optometry, University of California, Berkeley, CA, USA
| | - Yvonne T Wu
- School of Optometry, University of California, Berkeley, CA, USA
| | - Vincent Nieto
- School of Optometry, University of California, Berkeley, CA, USA
| | - David J Evans
- School of Optometry, University of California, Berkeley, CA, USA; College of Pharmacy, Touro University California, Vallejo, CA, USA
| | - Suzanne M J Fleiszig
- School of Optometry, University of California, Berkeley, CA, USA; Graduate Groups in Vision Science, Microbiology, and Infectious Diseases & Immunity, University of California, Berkeley, CA, USA.
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Morin CD, Déziel E, Gauthier J, Levesque RC, Lau GW. An Organ System-Based Synopsis of Pseudomonas aeruginosa Virulence. Virulence 2021; 12:1469-1507. [PMID: 34180343 PMCID: PMC8237970 DOI: 10.1080/21505594.2021.1926408] [Citation(s) in RCA: 33] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Driven in part by its metabolic versatility, high intrinsic antibiotic resistance, and a large repertoire of virulence factors, Pseudomonas aeruginosa is expertly adapted to thrive in a wide variety of environments, and in the process, making it a notorious opportunistic pathogen. Apart from the extensively studied chronic infection in the lungs of people with cystic fibrosis (CF), P. aeruginosa also causes multiple serious infections encompassing essentially all organs of the human body, among others, lung infection in patients with chronic obstructive pulmonary disease, primary ciliary dyskinesia and ventilator-associated pneumonia; bacteremia and sepsis; soft tissue infection in burns, open wounds and postsurgery patients; urinary tract infection; diabetic foot ulcers; chronic suppurative otitis media and otitis externa; and keratitis associated with extended contact lens use. Although well characterized in the context of CF, pathogenic processes mediated by various P. aeruginosa virulence factors in other organ systems remain poorly understood. In this review, we use an organ system-based approach to provide a synopsis of disease mechanisms exerted by P. aeruginosa virulence determinants that contribute to its success as a versatile pathogen.
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Affiliation(s)
- Charles D Morin
- Centre Armand-Frappier Santé Biotechnologie, Institut National De La Recherche Scientifique (INRS), Laval, Quebec, Canada
| | - Eric Déziel
- Centre Armand-Frappier Santé Biotechnologie, Institut National De La Recherche Scientifique (INRS), Laval, Quebec, Canada
| | - Jeff Gauthier
- Département De Microbiologie-infectiologie Et Immunologie, Institut De Biologie Intégrative Et Des Systèmes (IBIS), Université Laval, Québec City, Quebec, Canada
| | - Roger C Levesque
- Département De Microbiologie-infectiologie Et Immunologie, Institut De Biologie Intégrative Et Des Systèmes (IBIS), Université Laval, Québec City, Quebec, Canada
| | - Gee W Lau
- Department of Pathobiology, University of Illinois at Urbana-Champaign, Urbana, IL, US
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Chemical Composition, Antipathogenic and Cytotoxic Activity of the Essential Oil Extracted from Amorpha fruticosa Fruits. Molecules 2021; 26:molecules26113146. [PMID: 34074063 PMCID: PMC8197342 DOI: 10.3390/molecules26113146] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2021] [Revised: 05/16/2021] [Accepted: 05/21/2021] [Indexed: 11/24/2022] Open
Abstract
The purpose of this paper was to characterize and investigate the antimicrobial potential of Amorpha fruticosa fruits essential oil (EO). The EO was extracted by hydrodistillation, analyzed by GC-MS, and then evaluated for its interaction with microbial and mammalian cells. The antimicrobial activity was assessed against bacterial and fungal strains, in a planktonic and adherent growth state, using qualitative and quantitative assays. The main components identified in A. fruticosa fruits EO were δ-cadinene, γ-muurolene, and α-muurolene. The Gram-positive strains proved to be more susceptible than Gram-negative bacteria and fungal strains. The EO exhibited good antibiofilm activity, inhibiting the microbial adherence to the inert (96-well plates and Foley catheter section) and cellular substrata. The flow cytometry analysis revealed as one of the possible mechanisms of antimicrobial action the alteration of cell membrane hydrophobicity. The cytotoxicity on the L929 cell line occurred at concentrations higher than 0.3 mg/mL. Taken together, our results demonstrate that A. fruticosa fruits EO contains active compounds with selective inhibitory effect on different microbial strains in planktonic and biofilm growth state, explained at least partially by the interference with microbial membranes due to their hydrophobic character.
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Willcox M, Thakur A, Holden B. Some potential pathogenic traits of gram‐negative bacteria isolated during ocular inflammation and infections. Clin Exp Optom 2021. [DOI: 10.1111/j.1444-0938.1998.tb06627.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Affiliation(s)
- Mdp Willcox
- Cooperative Research Centre for Eye Research and Technology, The University of New South Wales
| | - A. Thakur
- Cooperative Research Centre for Eye Research and Technology, The University of New South Wales
| | - Ba Holden
- Cooperative Research Centre for Eye Research and Technology, The University of New South Wales
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21
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Morphological and cytokine profiles as key parameters to distinguish between Gram-negative and Gram-positive bacterial keratitis. Sci Rep 2020; 10:20092. [PMID: 33208864 PMCID: PMC7674500 DOI: 10.1038/s41598-020-77088-w] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2019] [Accepted: 11/04/2020] [Indexed: 01/20/2023] Open
Abstract
Bacterial keratitis (BK) is an ocular disorder associated with poor visual prognosis. Quantification of the associated inflammatory response may provide insight into the pathogenesis of BK and guide treatment options. In this exploratory study, we evaluated 45 BK patients and 20 healthy controls by optical coherence tomography and pro-inflammatory tear cytokine analysis. The aim was to quantify the differential morphological and cytokine inflammatory response between Gram-negative and Gram-positive BK and to determine the diagnostic value of corneal thickness (CT) and infiltrate thickness (IT) in distinguishing Gram-ve BK in a clinical cohort. Greater CT and IT, at clinical presentation, were indicative of Gram-ve infection with values detected of ≥ 950 μm and ≥ 450 μm, respectively. Combination of these CT and IT values had a 100% sensitivity and 83.3% specificity as a diagnostic indicator of Gram-ve infection. Similarly, there were higher levels of IL-1β, IL-6 and IL-8 cytokines were quantified in keratitis caused by Gram-negative bacteria. Among the different tear cytokines analysed, a significant reduction after three days of treatment was detected for pro-inflammatory cytokines IL-1β, IL-2, IL-6, IL-8 and TNF-α, prior to starting with the administration of steroid drops. Overall, this study shows the potential value of serial OCT and tear cytokine measurements in the management of BK.
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Shen EP, Chu HS, Hsieh YT, Chen WL, Chang SC, Hu FR. Analysis of P. aeruginosa disinfectant sensitivity and microbial adhesions to worn cosmetic contact lenses. Cont Lens Anterior Eye 2020; 43:338-344. [DOI: 10.1016/j.clae.2019.10.137] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2019] [Revised: 10/15/2019] [Accepted: 10/27/2019] [Indexed: 12/22/2022]
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Mirzaei R, Mohammadzadeh R, Sholeh M, Karampoor S, Abdi M, Dogan E, Moghadam MS, Kazemi S, Jalalifar S, Dalir A, Yousefimashouf R, Mirzaei E, Khodavirdipour A, Alikhani MY. The importance of intracellular bacterial biofilm in infectious diseases. Microb Pathog 2020; 147:104393. [PMID: 32711113 DOI: 10.1016/j.micpath.2020.104393] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2020] [Revised: 07/07/2020] [Accepted: 07/08/2020] [Indexed: 12/17/2022]
Abstract
Various bacterial species, previously known as extracellular pathogens, can reside inside different host cells by adapting to intracellular modes by forming microbial aggregates with similar characteristics to bacterial biofilms. Additionally, bacterial invasion of human cells leads to failure in antibiotic therapy, as most conventional anti-bacterial agents cannot reach intracellular biofilm in normal concentrations. Various studies have shown that bacteria such as uropathogenic Escherichia coli, Pseudomonas aeruginosa, Borrelia burgdorferi,Moraxella catarrhalis, non-typeable Haemophilus influenzae, Streptococcus pneumonia, and group A Streptococci produce biofilm-like structures within the host cells. For the first time in this review, we will describe and discuss the new information about intracellular bacterial biofilm formation and its importance in bacterial infectious diseases.
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Affiliation(s)
- Rasoul Mirzaei
- Department of Microbiology, School of Medicine, Hamadan University of Medical Sciences, Hamadan, Iran; Student Research Committee, Hamadan University of Medical Sciences, Hamadan, Iran
| | - Rokhsareh Mohammadzadeh
- Department of Microbiology, School of Medicine, Iran University of Medical Sciences, Tehran, Iran
| | - Mohammad Sholeh
- Department of Microbiology, School of Medicine, Iran University of Medical Sciences, Tehran, Iran
| | - Sajad Karampoor
- Department of Virology, School of Medicine, Iran University of Medical Sciences, Tehran, Iran
| | - Milad Abdi
- Department of Microbiology, School of Medicine, Iran University of Medical Sciences, Tehran, Iran; Student Research Committee, Faculty of Medicine, Iran University of Medical Sciences, Tehran, Iran
| | - Eyup Dogan
- Department of Basic Biotechnology, Biotechnology Institute, Ankara, Turkey
| | - Mohammad Shokri Moghadam
- Department of Microbiology, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran
| | - Sima Kazemi
- Department of Microbiology, School of Medicine, Hamadan University of Medical Sciences, Hamadan, Iran
| | - Saba Jalalifar
- Department of Microbiology, School of Medicine, Iran University of Medical Sciences, Tehran, Iran
| | - Amine Dalir
- Department of Microbiology, School of Medicine, Iran University of Medical Sciences, Tehran, Iran
| | - Rasoul Yousefimashouf
- Department of Microbiology, School of Medicine, Hamadan University of Medical Sciences, Hamadan, Iran
| | - Ebrahim Mirzaei
- Department of Medical Genetics and Molecular Biology, School of Medicine, Iran University of Medical Sciences, Tehran, Iran
| | - Amir Khodavirdipour
- Division of Humann Genetics, Department of Anatomy, St. John's Hospital, Bangalore, India
| | - Mohammad Yousef Alikhani
- Department of Microbiology, School of Medicine, Hamadan University of Medical Sciences, Hamadan, Iran.
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Otero-Asman JR, Quesada JM, Jim KK, Ocampo-Sosa A, Civantos C, Bitter W, Llamas MA. The extracytoplasmic function sigma factor σ VreI is active during infection and contributes to phosphate starvation-induced virulence of Pseudomonas aeruginosa. Sci Rep 2020; 10:3139. [PMID: 32081993 PMCID: PMC7035377 DOI: 10.1038/s41598-020-60197-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2019] [Accepted: 02/07/2020] [Indexed: 12/27/2022] Open
Abstract
The extracytoplasmic function sigma factor σVreI of the human pathogen Pseudomonas aeruginosa promotes transcription of potential virulence determinants, including secretion systems and secreted proteins. Its activity is modulated by the VreR anti-σ factor that inhibits the binding of σVreI to the RNA polymerase in the absence of a (still unknown) inducing signal. The vreI-vreR genes are expressed under inorganic phosphate (Pi) starvation, a physiological condition often encountered in the host that increases P. aeruginosa pathogenicity. However, whether or not σVreI is active in vivo during infection and contributes to the Pi starvation-induced virulence of this pathogen has not been analyzed yet. Using zebrafish embryos and a human alveolar basal epithelial cell line as P. aeruginosa hosts, we demonstrate in this work that σVreI is active during infection and that lack of σVreI considerably reduces the Pi starvation-induced virulence of this pathogen. Surprisingly, lack of the σVreI inhibitor, the VreR anti-σ factor, also diminishes the virulence of P. aeruginosa. By transcriptomic analyses we show that VreR modulates gene expression not only in a σVreI-dependent but also in a σVreI-independent manner. This includes potential virulence determinants and transcriptional regulators that could be responsible for the reduced virulence of the ΔvreR mutant.
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Affiliation(s)
- Joaquín R Otero-Asman
- Department of Environmental Protection, Estación Experimental del Zaidín-Consejo Superior de Investigaciones Científicas, Granada, Spain
| | - José M Quesada
- Department of Environmental Protection, Estación Experimental del Zaidín-Consejo Superior de Investigaciones Científicas, Granada, Spain
| | - Kin K Jim
- Department of Medical Microbiology and Infection Control, Amsterdam University medical centers, location VU University, Amsterdam, The Netherlands
| | - Alain Ocampo-Sosa
- Service of Microbiology, Hospital Universitario Marqués de Valdecilla-Instituto de Investigación Sanitaria Valdecilla, Santander, Spain
| | - Cristina Civantos
- Department of Environmental Protection, Estación Experimental del Zaidín-Consejo Superior de Investigaciones Científicas, Granada, Spain
| | - Wilbert Bitter
- Department of Medical Microbiology and Infection Control, Amsterdam University medical centers, location VU University, Amsterdam, The Netherlands
| | - María A Llamas
- Department of Environmental Protection, Estación Experimental del Zaidín-Consejo Superior de Investigaciones Científicas, Granada, Spain.
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Draft Genome Sequences of Eight Pseudomonas aeruginosa Corneal Infection Isolates. Microbiol Resour Announc 2020; 9:9/1/e01253-19. [PMID: 31896638 PMCID: PMC6940290 DOI: 10.1128/mra.01253-19] [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] [Indexed: 11/20/2022] Open
Abstract
Pseudomonas aeruginosa is the major cause of bacterial keratitis, a sight-threatening ocular infection that can occur in contact lens wearers, as well as in others. Here, we report the draft genomes of 8 different P. aeruginosa corneal isolates, adding to the list of publicly available corneal infection-associated P. aeruginosa genomes.
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Fleiszig SMJ, Kroken AR, Nieto V, Grosser MR, Wan SJ, Metruccio MME, Evans DJ. Contact lens-related corneal infection: Intrinsic resistance and its compromise. Prog Retin Eye Res 2019; 76:100804. [PMID: 31756497 DOI: 10.1016/j.preteyeres.2019.100804] [Citation(s) in RCA: 56] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2019] [Revised: 11/05/2019] [Accepted: 11/12/2019] [Indexed: 12/20/2022]
Abstract
Contact lenses represent a widely utilized form of vision correction with more than 140 million wearers worldwide. Although generally well-tolerated, contact lenses can cause corneal infection (microbial keratitis), with an approximate annualized incidence ranging from ~2 to ~20 cases per 10,000 wearers, and sometimes resulting in permanent vision loss. Research suggests that the pathogenesis of contact lens-associated microbial keratitis is complex and multifactorial, likely requiring multiple conspiring factors that compromise the intrinsic resistance of a healthy cornea to infection. Here, we outline our perspective of the mechanisms by which contact lens wear sometimes renders the cornea susceptible to infection, focusing primarily on our own research efforts during the past three decades. This has included studies of host factors underlying the constitutive barrier function of the healthy cornea, its response to bacterial challenge when intrinsic resistance is not compromised, pathogen virulence mechanisms, and the effects of contact lens wear that alter the outcome of host-microbe interactions. For almost all of this work, we have utilized the bacterium Pseudomonas aeruginosa because it is the leading cause of lens-related microbial keratitis. While not yet common among corneal isolates, clinical isolates of P. aeruginosa have emerged that are resistant to virtually all currently available antibiotics, leading the United States CDC (Centers for Disease Control) to add P. aeruginosa to its list of most serious threats. Compounding this concern, the development of advanced contact lenses for biosensing and augmented reality, together with the escalating incidence of myopia, could portent an epidemic of vision-threatening corneal infections in the future. Thankfully, technological advances in genomics, proteomics, metabolomics and imaging combined with emerging models of contact lens-associated P. aeruginosa infection hold promise for solving the problem - and possibly life-threatening infections impacting other tissues.
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Affiliation(s)
- Suzanne M J Fleiszig
- School of Optometry, University of California, Berkeley, CA, USA; Graduate Group in Vision Science, University of California, Berkeley, CA, USA; Graduate Groups in Microbiology and Infectious Diseases & Immunity, University of California, Berkeley, CA, USA.
| | - Abby R Kroken
- School of Optometry, University of California, Berkeley, CA, USA
| | - Vincent Nieto
- School of Optometry, University of California, Berkeley, CA, USA
| | | | - Stephanie J Wan
- Graduate Group in Vision Science, University of California, Berkeley, CA, USA
| | | | - David J Evans
- School of Optometry, University of California, Berkeley, CA, USA; College of Pharmacy, Touro University California, Vallejo, CA, USA
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Ozer EA, Nnah E, Didelot X, Whitaker RJ, Hauser AR. The Population Structure of Pseudomonas aeruginosa Is Characterized by Genetic Isolation of exoU+ and exoS+ Lineages. Genome Biol Evol 2019; 11:1780-1796. [PMID: 31173069 PMCID: PMC6690169 DOI: 10.1093/gbe/evz119] [Citation(s) in RCA: 38] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/05/2019] [Indexed: 02/06/2023] Open
Abstract
The diversification of microbial populations may be driven by many factors including adaptation to distinct ecological niches and barriers to recombination. We examined the population structure of the bacterial pathogen Pseudomonas aeruginosa by analyzing whole-genome sequences of 739 isolates from diverse sources. We confirmed that the population structure of P. aeruginosa consists of two major groups (referred to as Groups A and B) and at least two minor groups (Groups C1 and C2). Evidence for frequent intragroup but limited intergroup recombination in the core genome was observed, consistent with sexual isolation of the groups. Likewise, accessory genome analysis demonstrated more gene flow within Groups A and B than between these groups, and a few accessory genomic elements were nearly specific to one or the other group. In particular, the exoS gene was highly overrepresented in Group A compared with Group B isolates (99.4% vs. 1.1%) and the exoU gene was highly overrepresented in Group B compared with Group A isolates (95.2% vs. 1.8%). The exoS and exoU genes encode effector proteins secreted by the P. aeruginosa type III secretion system. Together these results suggest that the major P. aeruginosa groups defined in part by the exoS and exoU genes are divergent from each other, and that these groups are genetically isolated and may be ecologically distinct. Although both groups were globally distributed and caused human infections, certain groups predominated in some clinical contexts.
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Affiliation(s)
- Egon A Ozer
- Division of Infectious Diseases, Department of Medicine, Northwestern University Feinberg School of Medicine
| | - Ekpeno Nnah
- Lurie Children's Hospital, Chicago, Illinois
| | - Xavier Didelot
- School of Life Sciences and Department of Statistics, University of Warwick, Coventry, United Kingdom
| | - Rachel J Whitaker
- Department of Microbiology and the Carl R. Woese Institute of Genomic Biology, University of Illinois, Urbana-Champaign
| | - Alan R Hauser
- Division of Infectious Diseases, Department of Medicine, Northwestern University Feinberg School of Medicine.,Department of Microbiology-Immunology, Northwestern University Feinberg School of Medicine
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Ruffin M, Brochiero E. Repair Process Impairment by Pseudomonas aeruginosa in Epithelial Tissues: Major Features and Potential Therapeutic Avenues. Front Cell Infect Microbiol 2019; 9:182. [PMID: 31214514 PMCID: PMC6554286 DOI: 10.3389/fcimb.2019.00182] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2018] [Accepted: 05/13/2019] [Indexed: 01/13/2023] Open
Abstract
Epithelial tissues protecting organs from the environment are the first-line of defense against pathogens. Therefore, efficient repair mechanisms after injury are crucial to maintain epithelial integrity. However, these healing processes can be insufficient to restore epithelial integrity, notably in infectious conditions. Pseudomonas aeruginosa infections in cutaneous, corneal, and respiratory tract epithelia are of particular concern because they are the leading causes of hospitalizations, disabilities, and deaths worldwide. Pseudomonas aeruginosa has been shown to alter repair processes, leading to chronic wounds and infections. Because of the current increase in the incidence of multi-drug resistant isolates of P. aeruginosa, complementary approaches to decrease the negative impact of these bacteria on epithelia are urgently needed. Here, we review the recent advances in the understanding of the impact of P. aeruginosa infections on the integrity and repair mechanisms of alveolar, airway, cutaneous and corneal epithelia. Potential therapeutic avenues aimed at counteracting this deleterious impact of infection are also discussed.
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Affiliation(s)
- Manon Ruffin
- Centre de Recherche du Centre Hospitalier de l'Université de Montréal (CRCHUM), Montréal, QC, Canada.,Département de Médecine, Université de Montréal, Montréal, QC, Canada.,INSERM, Centre de Recherche Saint-Antoine, CRSA, Sorbonne Université, Paris, France
| | - Emmanuelle Brochiero
- Centre de Recherche du Centre Hospitalier de l'Université de Montréal (CRCHUM), Montréal, QC, Canada.,Département de Médecine, Université de Montréal, Montréal, QC, Canada
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Subedi D, Kohli GS, Vijay AK, Willcox M, Rice SA. Accessory genome of the multi-drug resistant ocular isolate of Pseudomonas aeruginosa PA34. PLoS One 2019; 14:e0215038. [PMID: 30986237 PMCID: PMC6464166 DOI: 10.1371/journal.pone.0215038] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2019] [Accepted: 03/25/2019] [Indexed: 02/07/2023] Open
Abstract
Bacteria can acquire an accessory genome through the horizontal transfer of genetic elements from non-parental lineages. This leads to rapid genetic evolution allowing traits such as antibiotic resistance and virulence to spread through bacterial communities. The study of complete genomes of bacterial strains helps to understand the genomic traits associated with virulence and antibiotic resistance. We aimed to investigate the complete accessory genome of an ocular isolate of Pseudomonas aeruginosa strain PA34. We obtained the complete genome of PA34 utilising genome sequence reads from Illumina and Oxford Nanopore Technology followed by PCR to close any identified gaps. In-depth genomic analysis was performed using various bioinformatics tools. The susceptibility to heavy metals and cytotoxicity was determined to confirm expression of certain traits. The complete genome of PA34 includes a chromosome of 6.8 Mbp and two plasmids of 95.4 Kbp (pMKPA34-1) and 26.8 Kbp (pMKPA34-2). PA34 had a large accessory genome of 1,213 genes and had 543 unique genes not present in other strains. These exclusive genes encoded features related to metal and antibiotic resistance, phage integrase and transposons. At least 24 genomic islands (GIs) were predicated in the complete chromosome, of which two were integrated into novel sites. Eleven GIs carried virulence factors or replaced pathogenic genes. A bacteriophage carried the aminoglycoside resistance gene (AAC(3)-IId). The two plasmids carried other six antibiotic resistance genes. The large accessory genome of this ocular isolate plays a large role in shaping its virulence and antibiotic resistance.
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Affiliation(s)
- Dinesh Subedi
- School of Optometry and Vision Science, University of New South Wales, Sydney, Australia
- * E-mail:
| | - Gurjeet Singh Kohli
- The Singapore Centre for Environmental Life Sciences Engineering, Nanyang Technological University, Singapore, Singapore
| | - Ajay Kumar Vijay
- School of Optometry and Vision Science, University of New South Wales, Sydney, Australia
| | - Mark Willcox
- School of Optometry and Vision Science, University of New South Wales, Sydney, Australia
| | - Scott A. Rice
- The Singapore Centre for Environmental Life Sciences Engineering, Nanyang Technological University, Singapore, Singapore
- The School of Biological Sciences, Nanyang Technological University, Singapore, Singapore
- The ithree Institute, The University of Technology Sydney, Sydney, New South Wales, Australia
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Abstract
PURPOSE Pseudomonas aeruginosa produces pyoverdine, encoded by the pvdE gene, for high-affinity iron uptake from transferrin and lactoferrin. This study investigated the contribution of pyoverdine to P. aeruginosa keratitis pathogenesis using in vitro and in vivo models. METHODS The P. aeruginosa strains examined were parental strain PAO1 and isogenic mutant strain pvdE (ΔpvdE) defective in pyoverdine. Bacterial growth in vitro was determined by PAO1 and ΔpvdE optical densities in Luria-Bertani (LB) broth. PAO1 or ΔpvdE (10 colony-forming units/mL) was inoculated onto cultured human corneal epithelial cells (HCECs) for 1 hour. The monolayers were examined for bacterial adhesion and invasion. In addition, the corneas of C57BL/6 mice were infected with PAO1 or ΔpvdE. Corneal virulence was evaluated by determining clinical scores and bacterial counts during infection. RESULTS The growth of PAO1 and ΔpvdE in LB broth was similar. Although adhesion of ΔpvdE onto HCECs was significantly increased compared with PAO1, the invasive capacity of ΔpvdE was significantly decreased. Clinical scores and bacterial numbers were significantly lower in ΔpvdE-infected eyes compared with PAO1-infected eyes at 6, 24, and 48 hours (P < 0.001). ΔpvdE was not detected in mouse corneas and did not induce corneal opacity at 6, 24, or 48 hours. CONCLUSIONS ΔpvdE lost invasive ability toward HCECs. Moreover, ΔpvdE did not cause keratitis in vivo. Thus, pvdE pyoverdine synthesis has critical roles in proliferation and invasion on ocular surfaces and could be a target for prevention of P. aeruginosa keratitis.
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Worstell NC, Singla A, Saenkham P, Galbadage T, Sule P, Lee D, Mohr A, Kwon JSI, Cirillo JD, Wu HJ. Hetero-Multivalency of Pseudomonas aeruginosa Lectin LecA Binding to Model Membranes. Sci Rep 2018; 8:8419. [PMID: 29849092 PMCID: PMC5976636 DOI: 10.1038/s41598-018-26643-7] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2018] [Accepted: 05/16/2018] [Indexed: 12/29/2022] Open
Abstract
A single glycan-lectin interaction is often weak and semi-specific. Multiple binding domains in a single lectin can bind with multiple glycan molecules simultaneously, making it difficult for the classic “lock-and-key” model to explain these interactions. We demonstrated that hetero-multivalency, a homo-oligomeric protein simultaneously binding to at least two types of ligands, influences LecA (a Pseudomonas aeruginosa adhesin)-glycolipid recognition. We also observed enhanced binding between P. aeruginosa and mixed glycolipid liposomes. Interestingly, strong ligands could activate weaker binding ligands leading to higher LecA binding capacity. This hetero-multivalency is probably mediated via a simple mechanism, Reduction of Dimensionality (RD). To understand the influence of RD, we also modeled LecA’s two-step binding process with membranes using a kinetic Monte Carlo simulation. The simulation identified the frequency of low-affinity ligand encounters with bound LecA and the bound LecA’s retention of the low-affinity ligand as essential parameters for triggering hetero-multivalent binding, agreeing with experimental observations. The hetero-multivalency can alter lectin binding properties, including avidities, capacities, and kinetics, and therefore, it likely occurs in various multivalent binding systems. Using hetero-multivalency concept, we also offered a new strategy to design high-affinity drug carriers for targeted drug delivery.
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Affiliation(s)
- Nolan C Worstell
- Department of Chemical Engineering, Texas A&M University, College Station, Texas, USA
| | - Akshi Singla
- Department of Chemical Engineering, Texas A&M University, College Station, Texas, USA
| | - Panatda Saenkham
- Department of Microbial Pathogenesis and Immunology, Texas A&M Health Science Center, Bryan, Texas, USA
| | - Thushara Galbadage
- Department of Microbial Pathogenesis and Immunology, Texas A&M Health Science Center, Bryan, Texas, USA
| | - Preeti Sule
- Department of Microbial Pathogenesis and Immunology, Texas A&M Health Science Center, Bryan, Texas, USA
| | - Dongheon Lee
- Department of Chemical Engineering, Texas A&M University, College Station, Texas, USA
| | - Alec Mohr
- Department of Chemical Engineering, Texas A&M University, College Station, Texas, USA
| | - Joseph Sang-Il Kwon
- Department of Chemical Engineering, Texas A&M University, College Station, Texas, USA
| | - Jeffrey D Cirillo
- Department of Microbial Pathogenesis and Immunology, Texas A&M Health Science Center, Bryan, Texas, USA
| | - Hung-Jen Wu
- Department of Chemical Engineering, Texas A&M University, College Station, Texas, USA.
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The Impact of ExoS on Pseudomonas aeruginosa Internalization by Epithelial Cells Is Independent of fleQ and Correlates with Bistability of Type Three Secretion System Gene Expression. mBio 2018; 9:mBio.00668-18. [PMID: 29717012 PMCID: PMC5930308 DOI: 10.1128/mbio.00668-18] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Pseudomonas aeruginosa is internalized into multiple types of epithelial cell in vitro and in vivo and yet is often regarded as an exclusively extracellular pathogen. Paradoxically, ExoS, a type three secretion system (T3SS) effector, has antiphagocytic activities but is required for intracellular survival of P. aeruginosa and its occupation of bleb niches in epithelial cells. Here, we addressed mechanisms for this dichotomy using invasive (ExoS-expressing) P. aeruginosa and corresponding effector-null isogenic T3SS mutants, effector-null mutants of cytotoxic P. aeruginosa with and without ExoS transformation, antibiotic exclusion assays, and imaging using a T3SS-GFP reporter. Except for effector-null PA103, all strains were internalized while encoding ExoS. Intracellular bacteria showed T3SS activation that continued in replicating daughter cells. Correcting the fleQ mutation in effector-null PA103 promoted internalization by >10-fold with or without ExoS. Conversely, mutating fleQ in PAO1 reduced internalization by >10-fold, also with or without ExoS. Effector-null PA103 remained less well internalized than PAO1 matched for fleQ status, but only with ExoS expression, suggesting additional differences between these strains. Quantifying T3SS activation using GFP fluorescence and quantitative reverse transcription-PCR (qRT-PCR) showed that T3SS expression was hyperinducible for strain PA103ΔexoUT versus other isolates and was unrelated to fleQ status. These findings support the principle that P. aeruginosa is not exclusively an extracellular pathogen, with internalization influenced by the relative proportions of T3SS-positive and T3SS-negative bacteria in the population during host cell interaction. These data also challenge current thinking about T3SS effector delivery into host cells and suggest that T3SS bistability is an important consideration in studying P. aeruginosa pathogenesis. P. aeruginosa is often referred to as an extracellular pathogen, despite its demonstrated capacity to invade and survive within host cells. Fueling the confusion, P. aeruginosa encodes T3SS effectors with anti-internalization activity that, paradoxically, play critical roles in intracellular survival. Here, we sought to address why ExoS does not prevent internalization of the P. aeruginosa strains that natively encode it. Results showed that ExoS exerted unusually strong anti-internalization activity under conditions of expression in the effector-null background of strain PA103, often used to study T3SS effector activity. Inhibition of internalization was associated with T3SS hyperinducibility and ExoS delivery. PA103 fleQ mutation, preventing flagellar assembly, further reduced internalization but did so independently of ExoS. The results revealed intracellular T3SS expression by all strains and suggested that T3SS bistability influences P. aeruginosa internalization. These findings reconcile controversies in the literature surrounding P. aeruginosa internalization and support the principle that P. aeruginosa is not exclusively an extracellular pathogen.
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Madhu SN, Jha KK, Karthyayani AP, Gajjar DU. Ex vivo Caprine Model to Study Virulence Factors in Keratitis. J Ophthalmic Vis Res 2018; 13:383-391. [PMID: 30479706 PMCID: PMC6210866 DOI: 10.4103/jovr.jovr_131_17] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Purpose: To develop an infectious keratitis model using caprine (goat) corneas and to investigate the expression of virulence factors during infection. Methods: Goat eyes were surface-sterilized and dissected, and the corneas were placed on an agarose-gelatin solid support (0.5% in phosphate-buffered saline) in a 12-well culture plate containing 10% fetal bovine serum-supplemented culture medium for 3 weeks. Cell viability tests (trypan blue and MTT) were performed on the cultured corneas. Corneas were infected with Pseudomonas aeruginosa and Fusarium solani separately. Infection progression was observed via histological analysis and hematoxylin and eosin (H-E) staining. For Pseudomonas-infected corneas, expression of eight virulence genes (exoS, exoT, exoY, alpR, prpL, lasA, lasB, and algD) was determined via quantitative real-time PCR (qRT-PCR) at 48-h and 72-h time-points. For Fusarium-infected corneas, expression of five proteases (C7Z0E6, C7ZFW9, C7Z7U2, C7ZNV5, and C7YY94) was quantified via qRT-PCR at 2, 4, and 8 days after infection. Protease from infected corneas was detected via gelatin zymography. Results: Goat corneas with a viable epithelium could be maintained for 15 days. Pseudomonas infection progressed rapidly, and complete corneal degradation was observed on day 4 after infection. Fusarium infection progressed more slowly. Histological analysis and H-E staining of Fusarium-infected cornea revealed mycelia penetrating all layers of the cornea. qRT-PCR revealed expression of all eight virulence factors, and statistically significant difference in expression of prpL and alpR in Pseudomonas-infected corneas. Expression of C7ZNV5 was highest in Fusarium-infected corneas. Conclusion: Goat corneas can be used to evaluate the expression of virulence factors involved in Pseudomonas and Fusarium infection.
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Affiliation(s)
- Swati N Madhu
- Department of Microbiology and Biotechnology Centre, Faculty of Science, The Maharaja Sayajirao University of Baroda, Vadodara, Gujarat, India
| | - Kartik Kumar Jha
- Department of Microbiology and Biotechnology Centre, Faculty of Science, The Maharaja Sayajirao University of Baroda, Vadodara, Gujarat, India
| | - Annapoorna P Karthyayani
- Department of Microbiology and Biotechnology Centre, Faculty of Science, The Maharaja Sayajirao University of Baroda, Vadodara, Gujarat, India
| | - Devarshi Urvish Gajjar
- Department of Microbiology and Biotechnology Centre, Faculty of Science, The Maharaja Sayajirao University of Baroda, Vadodara, Gujarat, India
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Del Mar Cendra M, Christodoulides M, Hossain P. Effect of Different Antibiotic Chemotherapies on Pseudomonas aeruginosa Infection In Vitro of Primary Human Corneal Fibroblast Cells. Front Microbiol 2017; 8:1614. [PMID: 28878761 PMCID: PMC5572282 DOI: 10.3389/fmicb.2017.01614] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2017] [Accepted: 08/08/2017] [Indexed: 12/11/2022] Open
Abstract
Pseudomonas aeruginosa is a major cause of bacterial keratitis (BK) worldwide. Inappropriate or non-optimal antibiotic chemotherapy can lead to corneal perforation and rapid sight loss. In this study, we tested the hypothesis that P. aeruginosa strain PAO1 invades primary human corneal fibroblasts (hCFs) in vitro and persists intracellularly, despite chemotherapy with antibiotics used commonly to treat BK. In rank order, ciprofloxacin, levofloxacin and polymyxin B showed the highest activity against planktonic PAO1 growth (100% inhibitory concentration ≤10 μg/mL; 50% inhibitory concentration ≤1 μg/mL), followed by gentamicin and ofloxacin (100% inhibitory concentration ≤50 μg/mL; 50% inhibitory concentration ≤10 μg/mL). These bactericidal antibiotics (50–200 μg/mL concentrations) all killed PAO1 in the extracellular environment of infected hCF monolayers. By contrast, the bactericidal antibiotic cefuroxime and the bacteriostatic antibiotic chloramphenicol failed to sterilize both PAO1 broth cultures, even at a concentration of ≥200 μg/mL) and infected hCF monolayers. Statistically, all antibiotics were able to prevent LDH release from PAO1-infected hCF monolayers at both concentrations tested. Intracellular Pseudomonas were significantly reduced (>99%, P < 0.05) following treatment with ciprofloxacin, levofloxacin and ofloxacin, whereas gentamicin, polymyxin B and cefuroxime failed to clear intracellular bacteria over 24 h. Intracellular Pseudomonas infection was resistant to chloramphenicol, with hCF death observed by 9 h. Eventual growth of remaining intracellular Pseudomonas was observed in hCF after removal of all antibiotics, resulting in re-infection cycles and cell death by 48 h. All of the antibiotics reduced significantly (P < 0.05) IL-1β secretion by hCF infected with a Multiplicity Of Infection (MOI) = 1 of PAO1. With higher MOI, no pro-inflammatory effects were observed with antibiotic treatment, expect with polymyxin B and ofloxacin, which induced significant increased IL-1β secretion (P < 0.001). The findings from our study demonstrated that bactericidal and bacteriostatic antibiotics, routinely used to treat BK, failed to eradicate Pseudomonas infection of hCFs in vitro and that their bactericidal efficacies were influenced by the cellular location of the organism.
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Affiliation(s)
- Maria Del Mar Cendra
- Molecular Microbiology, Academic Unit of Clinical and Experimental Sciences, Faculty of Medicine, University of SouthamptonSouthampton, United Kingdom
| | - Myron Christodoulides
- Molecular Microbiology, Academic Unit of Clinical and Experimental Sciences, Faculty of Medicine, University of SouthamptonSouthampton, United Kingdom
| | - Parwez Hossain
- Eye Unit, Academic Unit of Clinical and Experimental Sciences, University Hospital Southampton NHS Foundation Trust, Southampton General HospitalSouthampton, United Kingdom
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Lamari F, Chakroun I, Rtimi S. Assessment of the correlation among antibiotic resistance, adherence to abiotic and biotic surfaces, invasion and cytotoxicity of Pseudomonas aeruginosa isolated from diseased gilthead sea bream. Colloids Surf B Biointerfaces 2017; 158:229-236. [PMID: 28697438 DOI: 10.1016/j.colsurfb.2017.06.044] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2017] [Revised: 05/28/2017] [Accepted: 06/26/2017] [Indexed: 11/27/2022]
Abstract
Improper uses of antibiotics to treat fish disease pose an increase of multidrug resistance in Pseudomonas aeruginosa. In order to escape host antimicrobial agents and induce cytotoxicity, different virulence properties are needed by these bacteria such as, biofilm formation, adhesion and invasion ability. This study was conducted to isolate Pseudomonas aeruginosa from diseased cultured gilthead sea bream. Seventeen isolates of Pseudomonas aeruginosa were identified by PCR. All of the isolates tested were susceptible to Gentamicin and Ciprofloxacin. Highest level of resistance was observed against Erythromycin, Ampicillin and Tetracycline. Among the 17 isolates, 11 showed multi-drug resistance. The isolates were screened for biofilm formation in abiotic surfaces, adherence, invasion and cytotoxicity against Hep-2 cells. We found that some strains were able to adhere to abiotic and biotic surface and to enter inside Hep-2 cells. Using cytochalasin D inhibitor, we observed a significant decrease in invasion of epithelial cells. The 17 washed bacterial cells induce variable degree of cytotoxicity. However, no cytotoxic effects on Hep-2 cells were obtained among the totality of cell free filtrate of Pseudomonas strains. By studying the relationship between different virulence properties, a significant positive correlation was obtained between both biofilm formation and adherence, and between adherence and invasion to epithelial cells. Subsequently, we found that the mean values of adhesion and invasion in the MDR group were significantly higher than those observed in the non-MDR group. Likewise, a significant positive correlation was found among adhesive and invasive capacities of Pseudomonas strains and their antibiotic resistance phenotypes.
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Affiliation(s)
- Faouzi Lamari
- Laboratory of Analysis, Treatment and Valorization of Environment Polluants and Products, Faculty of Pharmacy, Monastir University, Monastir, 5000, Tunisia.
| | - Ibtissem Chakroun
- Laboratory of Analysis, Treatment and Valorization of Environment Polluants and Products, Faculty of Pharmacy, Monastir University, Monastir, 5000, Tunisia
| | - Sami Rtimi
- Ecole Polytechnique Fédérale de Lausanne (EPFL), STI-IMX-LTP, Station 12, 1015, Lausanne, Switzerland.
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Immune Recognition of the Epidemic Cystic Fibrosis Pathogen Burkholderia dolosa. Infect Immun 2017; 85:IAI.00765-16. [PMID: 28348057 DOI: 10.1128/iai.00765-16] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2016] [Accepted: 03/20/2017] [Indexed: 12/31/2022] Open
Abstract
Burkholderia dolosa caused an outbreak in the cystic fibrosis (CF) clinic at Boston Children's Hospital from 1998 to 2005 and led to the infection of over 40 patients, many of whom died due to complications from infection by this organism. To assess whether B. dolosa significantly contributes to disease or is recognized by the host immune response, mice were infected with a sequenced outbreak B. dolosa strain, AU0158, and responses were compared to those to the well-studied CF pathogen Pseudomonas aeruginosa In parallel, mice were also infected with a polar flagellin mutant of B. dolosa to examine the role of flagella in B. dolosa lung colonization. The results showed a higher persistence in the host by B. dolosa strains, and yet, neutrophil recruitment and cytokine production were lower than those with P. aeruginosa The ability of host immune cells to recognize B. dolosa was then assessed, B. dolosa induced a robust cytokine response in cultured cells, and this effect was dependent on the flagella only when bacteria were dead. Together, these results suggest that B. dolosa can be recognized by host cells in vitro but may avoid or suppress the host immune response in vivo through unknown mechanisms. B. dolosa was then compared to other Burkholderia species and found to induce similar levels of cytokine production despite being internalized by macrophages more than Burkholderia cenocepacia strains. These data suggest that B. dolosa AU0158 may act differently with host cells and is recognized differently by immune systems than are other Burkholderia strains or species.
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Zheng S, Eierhoff T, Aigal S, Brandel A, Thuenauer R, de Bentzmann S, Imberty A, Römer W. The Pseudomonas aeruginosa lectin LecA triggers host cell signalling by glycosphingolipid-dependent phosphorylation of the adaptor protein CrkII. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2017; 1864:1236-1245. [PMID: 28428058 DOI: 10.1016/j.bbamcr.2017.04.005] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/04/2016] [Revised: 04/11/2017] [Accepted: 04/12/2017] [Indexed: 12/16/2022]
Abstract
The human pathogen Pseudomonas aeruginosa induces phosphorylation of the adaptor protein CrkII by activating the non-receptor tyrosine kinase Abl to promote its uptake into host cells. So far, specific factors of P. aeruginosa, which induce Abl/CrkII signalling, are entirely unknown. In this research, we employed human lung epithelial cells H1299, Chinese hamster ovary cells and P. aeruginosa wild type strain PAO1 to study the invasion process of P. aeruginosa into host cells by using microbiological, biochemical and cell biological approaches such as Western Blot, immunofluorescence microscopy and flow cytometry. Here, we demonstrate that the host glycosphingolipid globotriaosylceramide, also termed Gb3, represents a signalling receptor for the P. aeruginosa lectin LecA to induce CrkII phosphorylation at tyrosine 221. Alterations in Gb3 expression and LecA function correlate with CrkII phosphorylation. Interestingly, phosphorylation of CrkIIY221 occurs independently of Abl kinase. We further show that Src family kinases transduce the signal induced by LecA binding to Gb3, leading to CrkY221 phosphorylation. In summary, we identified LecA as a bacterial factor, which utilizes a so far unrecognized mechanism for phospho-CrkIIY221 induction by binding to the host glycosphingolipid receptor Gb3. The LecA/Gb3 interaction highlights the potential of glycolipids to mediate signalling processes across the plasma membrane and should be further elucidated to gain deeper insights into this non-canonical mechanism of activating host cell processes.
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Affiliation(s)
- Shuangshuang Zheng
- Faculty of Biology, Schänzlestraβe 1, Albert-Ludwigs-University Freiburg, 79104 Freiburg, Germany; BIOSS Centre for Biological Signalling Studies, Schänzlestraβe 18, Albert-Ludwigs-University Freiburg, 79104 Freiburg, Germany
| | - Thorsten Eierhoff
- Faculty of Biology, Schänzlestraβe 1, Albert-Ludwigs-University Freiburg, 79104 Freiburg, Germany; BIOSS Centre for Biological Signalling Studies, Schänzlestraβe 18, Albert-Ludwigs-University Freiburg, 79104 Freiburg, Germany.
| | - Sahaja Aigal
- Faculty of Biology, Schänzlestraβe 1, Albert-Ludwigs-University Freiburg, 79104 Freiburg, Germany; BIOSS Centre for Biological Signalling Studies, Schänzlestraβe 18, Albert-Ludwigs-University Freiburg, 79104 Freiburg, Germany; International Max Planck Research School for Molecular and Cellular Biology, Max Planck Institute of Immunobiology and Epigenetics, Stübeweg 51, 79108 Freiburg, Germany
| | - Annette Brandel
- Faculty of Biology, Schänzlestraβe 1, Albert-Ludwigs-University Freiburg, 79104 Freiburg, Germany; BIOSS Centre for Biological Signalling Studies, Schänzlestraβe 18, Albert-Ludwigs-University Freiburg, 79104 Freiburg, Germany
| | - Roland Thuenauer
- Faculty of Biology, Schänzlestraβe 1, Albert-Ludwigs-University Freiburg, 79104 Freiburg, Germany; BIOSS Centre for Biological Signalling Studies, Schänzlestraβe 18, Albert-Ludwigs-University Freiburg, 79104 Freiburg, Germany
| | - Sophie de Bentzmann
- Laboratoire d'Ingénierie des Systèmes Macromoléculaires, Institut de Microbiologie de la Méditerranée, Aix-Marseille Université, CNRS UMR7255, Marseille, France
| | - Anne Imberty
- Centre de Recherches sur les Macromolécules Végétales, UPR5301 CNRS and University of Grenoble Alpes, BP53, 38041 Grenoble cédex 09, France
| | - Winfried Römer
- Faculty of Biology, Schänzlestraβe 1, Albert-Ludwigs-University Freiburg, 79104 Freiburg, Germany; BIOSS Centre for Biological Signalling Studies, Schänzlestraβe 18, Albert-Ludwigs-University Freiburg, 79104 Freiburg, Germany; International Max Planck Research School for Molecular and Cellular Biology, Max Planck Institute of Immunobiology and Epigenetics, Stübeweg 51, 79108 Freiburg, Germany.
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Lakhundi S, Siddiqui R, Khan NA. Pathogenesis of microbial keratitis. Microb Pathog 2017; 104:97-109. [DOI: 10.1016/j.micpath.2016.12.013] [Citation(s) in RCA: 86] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2016] [Revised: 11/30/2016] [Accepted: 12/05/2016] [Indexed: 01/03/2023]
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Fleming M, Bexton S. Conjunctival flora of healthy and diseased eyes of grey seals (Halichoerus grypus): implications for treatment. Vet Rec 2016; 179:99. [PMID: 27188623 DOI: 10.1136/vr.103690] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/24/2016] [Indexed: 11/04/2022]
Abstract
Ocular pathology is relatively common in stranded seals admitted to wildlife rehabilitation hospitals. Some have pre-existing problems, while others develop eye problems in captivity, and in particular ulcerative keratitis, due to factors such as large prominent eyes, suboptimal water quality, trauma and infighting. Despite treatment, corneal ulcerations can rapidly progress to 'melting' ulcers with subsequent rupture of the globe. In this case series, 32 grey seals (Halichoerus grypus) had conjunctival swabs taken on admission to a UK wildlife hospital to identify ocular bacterial flora and nine had subsequent swabs taken after four weeks to see if this changed in captivity. Additionally, nine seals with ocular pathology were also swabbed. Although a wide range of bacteria were cultured on admission, the most common isolates were Gemella haemolysans, Escherichia coli and Clostridium perfringens All 'melting' ulcers were associated with Pseudomonas aeruginosa, which suggests this bacterial species may be significant in the pathogenesis of progressive stromal ulceration in grey seals.
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Affiliation(s)
- M Fleming
- RSPCA East Winch Wildlife Centre, Station Road, East Winch, Kings Lynn, Norfolk PE32 1NR, UK
| | - S Bexton
- RSPCA East Winch Wildlife Centre, Station Road, East Winch, Kings Lynn, Norfolk PE32 1NR, UK
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Kautto L, Nguyen-Khuong T, Everest-Dass A, Leong A, Zhao Z, Willcox MD, Packer NH, Peterson R. Glycan involvement in the adhesion of Pseudomonas aeruginosa to tears. Exp Eye Res 2016; 145:278-288. [DOI: 10.1016/j.exer.2016.01.013] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2015] [Revised: 01/21/2016] [Accepted: 01/21/2016] [Indexed: 10/22/2022]
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Georgescu M, Gheorghe I, Curutiu C, Lazar V, Bleotu C, Chifiriuc MC. Virulence and resistance features of Pseudomonas aeruginosa strains isolated from chronic leg ulcers. BMC Infect Dis 2016; 16 Suppl 1:92. [PMID: 27169367 PMCID: PMC4890939 DOI: 10.1186/s12879-016-1396-3] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2016] [Accepted: 01/27/2016] [Indexed: 11/29/2022] Open
Abstract
Background The purpose of this study was to evaluate the virulence profiles of Pseudomonas aeruginosa clinical strains recently isolated from patients hospitalized for chronic leg ulcers in the Dermatology Department of Central Military Emergency University Hospital “Carol Davila”, Bucharest, Romania. Methods The phenotypic screening evaluated eight soluble virulence factors (haemolysins, lecithinase, lipase, caseinase, gelatinase, amylase, DNase, aesculin hydrolysis), as well as adherence ability (Cravioto adapted method) and invasion capacity on HeLa cells (gentamicin protection assay). Seven virulence genes encoding for protease IV, 3 exoenzymes (exoS, exoT, exoU), two phospholipases plcH- haemolytic phospholipase C and plcN- non-haemolytic phospholipase C) and alginate were investigated by PCR. Results The pore forming toxins and enzymes were expressed in variable proportions, the majority of the tested strains producing beta haemolysin (92.3 %), lipase (76.9 %) and lecithinase (61.5 %). The most frequent virulence genes detected in the analyzed strains were the ExoT (100 %) and AlgD (92.3 %) genes, genes codifying for phospholipases (84.6 % each of them) and for protease IV (61.5 %). Conclusions This study reveals that correlating virulence profiles and infection clinical outcome is very useful for setting up efficient preventive and therapeutic procedures for hospitalized patients with chronic leg ulcers and positive P. aeruginosa cultures.
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Affiliation(s)
- Mihaela Georgescu
- Dermatology Department, Central University Emergency Military Hospital Dr Carol Davila, Bucharest, Romania.,Microbiology Department, Faculty of Biology, University of Bucharest, Bucharest, Romania
| | - Irina Gheorghe
- Microbiology Department, Faculty of Biology, University of Bucharest, Bucharest, Romania.,Research Institute of the University of Bucharest -ICUB, Bucharest, Romania
| | - Carmen Curutiu
- Microbiology Department, Faculty of Biology, University of Bucharest, Bucharest, Romania.,Research Institute of the University of Bucharest -ICUB, Bucharest, Romania
| | - Veronica Lazar
- Microbiology Department, Faculty of Biology, University of Bucharest, Bucharest, Romania.,Research Institute of the University of Bucharest -ICUB, Bucharest, Romania
| | - Coralia Bleotu
- Microbiology Department, Faculty of Biology, University of Bucharest, Bucharest, Romania. .,Ștefan S Nicolau Institute of Virology, Romanian Academy, 030304, Bucharest, Romania.
| | - Mariana-Carmen Chifiriuc
- Microbiology Department, Faculty of Biology, University of Bucharest, Bucharest, Romania.,Research Institute of the University of Bucharest -ICUB, Bucharest, Romania
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A Novel Insight into Dehydroleucodine Mediated Attenuation of Pseudomonas aeruginosa Virulence Mechanism. BIOMED RESEARCH INTERNATIONAL 2015; 2015:216097. [PMID: 26640783 PMCID: PMC4658400 DOI: 10.1155/2015/216097] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/27/2015] [Revised: 09/09/2015] [Accepted: 09/30/2015] [Indexed: 11/17/2022]
Abstract
Increasing resistance of Pseudomonas aeruginosa (P. aeruginosa) to conventional treatments demands the search for novel therapeutic strategies. In this study, the antimicrobial activity of dehydroleucodine (DhL), a sesquiterpene lactone obtained from Artemisia (A.) douglasiana, was screened against several pathogenic virulence effectors of P. aeruginosa. In vitro, minimum inhibitory concentration of DhL was determined against P. aeruginosa strains PAO1, PA103, PA14, and multidrug resistant clinical strain, CDN118. Results showed that DhL was active against each strain where PAO1 and PA103 showed higher susceptibility (MIC 0.48 mg/mL) as compared to PA14 (MIC 0.96 mg/mL) and CDN118 (MIC 0.98 mg/mL). Also, when PAO1 strain was grown in the presence of DhL (MIC50, 0.12 mg/mL), a delay in the generation time was noticed along with significant inhibition of secretory protease and elastase activities, interruption in biofilm attachment phase in a stationary culture, and a significant decline in Type III effector ExoS. At MIC50, DhL treatment increased the sensitivity of P. aeruginosa towards potent antibiotics. Furthermore, treatment of P. aeruginosa with DhL prevented toxin-induced apoptosis in macrophages. These observations suggest that DhL activity was at the bacterial transcriptional level. Hence, antimicrobial activity of DhL may serve as leads in the development of new anti-Pseudomonas pharmaceuticals.
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Yuan Q, Wu Y, Wang Y, Chen L, Qu M, Duan K, Zhao G. Protective efficacy of a peptide derived from a potential adhesin of Pseudomonas aeruginosa against corneal infection. Exp Eye Res 2015; 143:39-48. [PMID: 26500187 DOI: 10.1016/j.exer.2015.10.011] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2015] [Revised: 10/09/2015] [Accepted: 10/12/2015] [Indexed: 10/22/2022]
Abstract
Dissecting the interactions between Pseudomonas aeruginosa and corneal cells is important to identify a novel target for prevention and treatment of Pseudomonas keratitis. The current study began with a peptide identified by phage display, and was to investigate the protective efficacy against P. aeruginosa infection in cornea. The original peptide Pc-E, with high homology to a hypothetical membrane protein (HmpA) in P. aeruginosa, and the derived peptide Pc-EP, with the same sequence as a region in HmpA, were synthesized. Peptide Pc-EP could directly bind to HCEC, stronger than Pc-E, and specifically activate toll-like receptor 5, and thereby significantly induce the production of pro-inflammatory factors, such as IL-1β, IL-6, IFN-γ and IL-17. Moreover, Pc-EP could act as an antagonist to inhibit the adhesion of wild-type P. aeruginosa to HCEC and mouse corneas. No inhibitory effect was observed on the adhesion of the strain loss of HmpA. When compared to the wild-type strain, the adhesion of the hmpA mutant to corneal cells was significantly decreased. Treatment of infected mouse corneas with Pc-EP before infection significantly decreased the bacterial load in the cornea and attenuated the corneal pathology. These results indicate that Pc-EP can be a useful prophylactic agent for P. aeruginosa keratitis.
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Affiliation(s)
- Qing Yuan
- Shandong Provincial Key Laboratory of Ophthalmology, Shandong Provincial Excellent Innovation Team Program, Shandong Eye Institute, Shandong Academy of Medical Sciences, Qingdao 266071, China
| | - Yuting Wu
- Key Laboratory of Resources Biology and Biotechnology in Western China, Ministry of Education, College of Life Sciences, Northwest University, Xi'an 710069, China
| | - Yiqiang Wang
- Key Laboratory of Thrombosis and Hemostasis of Ministry of Health, Jiangsu Institute of Hematology, First Affiliated Hospital of Soochow University, Suzhou 215006, China
| | - Lin Chen
- Key Laboratory of Resources Biology and Biotechnology in Western China, Ministry of Education, College of Life Sciences, Northwest University, Xi'an 710069, China
| | - Mingli Qu
- Shandong Provincial Key Laboratory of Ophthalmology, Shandong Provincial Excellent Innovation Team Program, Shandong Eye Institute, Shandong Academy of Medical Sciences, Qingdao 266071, China
| | - Kangmin Duan
- Key Laboratory of Resources Biology and Biotechnology in Western China, Ministry of Education, College of Life Sciences, Northwest University, Xi'an 710069, China
| | - Ge Zhao
- Shandong Provincial Key Laboratory of Ophthalmology, Shandong Provincial Excellent Innovation Team Program, Shandong Eye Institute, Shandong Academy of Medical Sciences, Qingdao 266071, China; China Animal Health and Epidemiology Center, Qingdao, 266114, China.
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The importance of the Pseudomonas aeruginosa type III secretion system in epithelium traversal depends upon conditions of host susceptibility. Infect Immun 2015; 83:1629-40. [PMID: 25667266 DOI: 10.1128/iai.02329-14] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Pseudomonas aeruginosa is invasive or cytotoxic to host cells, depending on the type III secretion system (T3SS) effectors encoded. While the T3SS is known to be involved in disease in vivo, how it participates remains to be clarified. Here, mouse models of superficial epithelial injury (tissue paper blotting with EGTA treatment) and immunocompromise (MyD88 deficiency) were used to study the contribution of the T3SS transcriptional activator ExsA to epithelial traversal. Corneas of excised eyeballs were inoculated with green fluorescent protein (GFP)-expressing PAO1 or isogenic exsA mutants for 6 h ex vivo before bacterial traversal and epithelial thickness were quantified by using imaging. In the blotting-EGTA model, exsA mutants were defective in capacity for traversal. Accordingly, an ∼16-fold variability in exsA expression among PAO1 isolates from three sources correlated with epithelial loss. In contrast, MyD88-/- epithelia remained susceptible to P. aeruginosa traversal despite exsA mutation. Epithelial lysates from MyD88-/- mice had reduced antimicrobial activity compared to those from wild-type mice with and without prior antigen challenge, particularly 30- to 100-kDa fractions, for which mass spectrometry revealed multiple differences, including (i) lower baseline levels of histones, tubulin, and lumican and (ii) reduced glutathione S-transferase, annexin, and dermatopontin, after antigen challenge. Thus, the importance of ExsA in epithelial traversal by invasive P. aeruginosa depends on the compromise enabling susceptibility, suggesting that strategies for preventing infection will need to extend beyond targeting the T3SS. The data also highlight the importance of mimicking conditions allowing susceptibility in animal models and the need to monitor variability among bacterial isolates from different sources, even for the same strain.
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45
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Aldebasi YH, Mohamed HA, Aly SM. Histopathological Studies on Rabbits Infected by Bacteria Causing Infectious Keratitis in Human through Eye Inoculation. Int J Health Sci (Qassim) 2014; 8:257-67. [PMID: 25505861 DOI: 10.12816/0023978] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Abstract
AIM This study aimed to investigate the pathogenic effect of bacteria causing infectious keratitis among patients through experimental study conducted on rabbits' eyes with the aid of histopathology as eye infection is a common disease in developing countries that may complicate to loss of vision. METHODOLOGY 100 swab samples were collected from human infected eyes, at Qassim region during 2012, for the isolation of Pseudomonas aeruginosa and Staphylococcus aureus. The isolated pathogenic bacteria were tested to various antibiotics using some selected antibiotics discs through agar-well diffusion method. Then, experimental study conducted on 27 rabbits. The rabbits were divided randomly into three equal groups, each containing 9 rabbits. Rabbits of group (1) served as control group (Negative Control) and their eyes were inoculated with the buffer only. Rabbits of group (2) were inoculated through eyes with the isolated Pseudomonas aeruginosa. Rabbits of group (3) were inoculated through eyes with the isolated Staphylococcus aureus. RESULTS Out of 100 collected swab samples from human infected eyes, Pseudomonas aeruginosa and Staphylococcus aureus were isolated with a total percentage of 25.21% and 15.65%; respectively and used in this study. Both bacterial isolates were sensitive to Gentamicin and Cefuroxime. Clinically, experimentally infected rabbits by Pseudomonas aeruginosa, revealed varying degree corneal abrasions, corneal abscess and dense corneal opacity. Histopathologically, at 3(rd) day post-infection (PI), the cornea revealed polymorpho-nuclear cells infiltration with loss of the outer epithelial lining. At 7(th) day PI, neutrophils were seen in the stroma. At 15(th) day PI, proliferation of fibroblasts and new vascularisation were seen in the stroma. Clinically, rabbits experimentally infected with Staphylococcus aureus, revealed corneal ulcers and focal abscesses. Histopathologically, at 3(rd) and 7(th) day PI, the cornea revealed edema and infiltration of leukocytes. At 15(th) day PI, hyperplasia of corneal epithelium and proliferation of keratocytes were evident. The liver and kidneys of experimented rabbits revealed no remarkable histopathological alterations along the period of experiment. CONCLUSION Pseudomonas aeruginosa and Staphylococcus aureus are common eye infection in human, both induced severe lesions in the eyes of rabbits that could interfere with vision, therefore, strict measures to control these infections in human is recommended.
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Affiliation(s)
- Yousef H Aldebasi
- Dept of Optometry, College of Applied Medical Sciences, Qassim University, KSA.Dept of Pathology, Faculty of Medicine, Suez Canal University, Ismailia, Egypt
| | - Hala A Mohamed
- Dept of Optometry, College of Applied Medical Sciences, Qassim University, KSA.Dept of Pathology, Faculty of Medicine, Suez Canal University, Ismailia, Egypt
| | - Salah M Aly
- Dept of Medical Laboratories, College of Applied Medical Sciences, Qassim University, KSA.Dept of Pathology, Faculty of Medicine, Suez Canal University, Ismailia, Egypt
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Ahmed GF, Elkhatib WF, Noreddin AM. Inhibition of Pseudomonas aeruginosa PAO1 adhesion to and invasion of A549 lung epithelial cells by natural extracts. J Infect Public Health 2014; 7:436-44. [PMID: 24894307 DOI: 10.1016/j.jiph.2014.01.009] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2010] [Revised: 09/23/2013] [Accepted: 01/25/2014] [Indexed: 11/26/2022] Open
Abstract
Pseudomonas aeruginosa colonizes the lungs in cystic fibrosis (CF) and mechanically ventilated patients by binding to the cellular receptors on the surface of the lung epithelium. Studies have shown that blocking this interaction could be achieved with sub-minimum inhibitory concentrations of antibiotics such as ciprofloxacin. The development of bacterial resistance is a probable drawback of such an intervention. The use of natural extracts to interfere with bacterial adhesion and invasion has recently gained substantial attention and is hypothesized to inhibit bacterial binding and consequently prevent or reduce pathogenicity. This study used an A549 lung epithelial cell infection model, and the results revealed that a combination of aqueous cranberry extract with ciprofloxacin could completely prevent the adhesion and invasion of P. aeruginosa PAO1 compared to the untreated control. All of the natural extracts (cranberry, dextran, and soybean extracts) and ciprofloxacin showed a significant reduction (P<0.0001) in P. aeruginosa PAO1 adhesion to and invasion of lung epithelial cells relative to the control. The cranberry, dextran, and soybean extracts could substantially increase the anti-adhesion and anti-invasion effects of ciprofloxacin to the averages of 100% (P<0.0001), 80% (P<0.0001), and 60% (P<0.0001), respectively. Those extracts might result in a lower rate of the development of bacterial resistance; they are relatively safe and inexpensive agents, and utilizing such extracts, alone or in combination with ciprofloxacin, as potential anti-adhesion and anti-invasion remedies, could be valuable in preventing or reducing P. aeruginosa lung infections.
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Affiliation(s)
- Ghada F Ahmed
- Department of Experimental and Clinical Pharmacology, College of Pharmacy, University of Minnesota, 717 Delaware St. SE, Minneapolis, MN 55414, USA
| | - Walid F Elkhatib
- Department of Microbiology & Immunology, Faculty of Pharmacy, Ain Shams University, Cairo, Egypt; Department of Pharmacy Practice, School of Pharmacy, Hampton University, Hampton, VA 23668, USA.
| | - Ayman M Noreddin
- Department of Pharmacy Practice, School of Pharmacy, Hampton University, Hampton, VA 23668, USA
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Cao Q, Wang Y, Chen F, Xia Y, Lou J, Zhang X, Yang N, Sun X, Zhang Q, Zhuo C, Huang X, Deng X, Yang CG, Ye Y, Zhao J, Wu M, Lan L. A novel signal transduction pathway that modulates rhl quorum sensing and bacterial virulence in Pseudomonas aeruginosa. PLoS Pathog 2014; 10:e1004340. [PMID: 25166864 PMCID: PMC4148453 DOI: 10.1371/journal.ppat.1004340] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2014] [Accepted: 07/15/2014] [Indexed: 01/10/2023] Open
Abstract
The rhl quorum-sensing (QS) system plays critical roles in the pathogenesis of P. aeruginosa. However, the regulatory effects that occur directly upstream of the rhl QS system are poorly understood. Here, we show that deletion of gene encoding for the two-component sensor BfmS leads to the activation of its cognate response regulator BfmR, which in turn directly binds to the promoter and decreases the expression of the rhlR gene that encodes the QS regulator RhlR, causing the inhibition of the rhl QS system. In the absence of bfmS, the Acka-Pta pathway can modulate the regulatory activity of BfmR. In addition, BfmS tunes the expression of 202 genes that comprise 3.6% of the P. aeruginosa genome. We further demonstrate that deletion of bfmS causes substantially reduced virulence in lettuce leaf, reduced cytotoxicity, enhanced invasion, and reduced bacterial survival during acute mouse lung infection. Intriguingly, specific missense mutations, which occur naturally in the bfmS gene in P. aeruginosa cystic fibrosis (CF) isolates such as DK2 strains and RP73 strain, can produce BfmS variants (BfmSL181P, BfmSL181P/E376Q, and BfmSR393H) that no longer repress, but instead activate BfmR. As a result, BfmS variants, but not the wild-type BfmS, inhibit the rhl QS system. This study thus uncovers a previously unexplored signal transduction pathway, BfmS/BfmR/RhlR, for the regulation of rhl QS in P. aeruginosa. We propose that BfmRS TCS may have an important role in the regulation and evolution of P. aeruginosa virulence during chronic infection in CF lungs. The rhl quorum-sensing (QS) system allows P. aeruginosa to regulate diverse metabolic adaptations and virulence. However, how rhl QS system is regulated remains largely unknown. Here, we report that two-component sensor BfmS controls rhl QS system by repressing its cognate response regulator BfmR, which directly suppresses the expression of rhl QS regulator RhlR gene and reduces the production of QS signal molecule N-butanoyl-L-homoserine lactone (C4-HSL). We find that BfmS is critical to the ability of P. aeruginosa to modulate the expression of virulence-associated traits and adapt to the host. Intriguingly, although wild-type BfmS is a repressor of BfmR, naturally occurring missense mutation (L181P, L181P/E376Q, or R393H) can convert its function from a repressor to an activator of BfmR, leading to BfmR activation, which in turn reduces the level of rhl QS signal C4-HSL. These results, therefore, provide important and novel insight into the regulation and evolution of P. aeruginosa virulence.
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Affiliation(s)
- Qiao Cao
- Hainan University, Haikou, Hainan, China
- Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China
| | - Yue Wang
- Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China
- Institute of Chemistry and BioMedical Sciences, State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University, Nanjing, China
| | - Feifei Chen
- Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China
| | - Yongjie Xia
- Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China
| | - Jingyu Lou
- Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China
| | - Xue Zhang
- Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China
| | - Nana Yang
- Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China
| | - Xiaoxu Sun
- Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China
| | - Qin Zhang
- State Key Laboratory of Respiratory Diseases and the First Affiliated Hospital of Guangzhou Medical College, Guangzhou, China
| | - Chao Zhuo
- State Key Laboratory of Respiratory Diseases and the First Affiliated Hospital of Guangzhou Medical College, Guangzhou, China
| | - Xi Huang
- Hainan University, Haikou, Hainan, China
| | - Xin Deng
- Department of Chemistry and Institute for Biophysical Dynamics, The University of Chicago, Chicago, Illinois, United States of America
| | - Cai-Guang Yang
- Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China
| | - Yan Ye
- Department of Basic Sciences, University of North Dakota School of Medicine and Health Sciences, Grand Forks, North Dakota, United States of America
| | - Jing Zhao
- Institute of Chemistry and BioMedical Sciences, State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University, Nanjing, China
- * E-mail: (JZ); (MW); (LL)
| | - Min Wu
- Department of Basic Sciences, University of North Dakota School of Medicine and Health Sciences, Grand Forks, North Dakota, United States of America
- * E-mail: (JZ); (MW); (LL)
| | - Lefu Lan
- Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China
- * E-mail: (JZ); (MW); (LL)
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Involvement of stress-related genes polB and PA14_46880 in biofilm formation of Pseudomonas aeruginosa. Infect Immun 2014; 82:4746-57. [PMID: 25156741 DOI: 10.1128/iai.01915-14] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Chronic infections of Pseudomonas aeruginosa are generally established through production of biofilm. During biofilm formation, production of an extracellular matrix and establishment of a distinct bacterial phenotype make these infections difficult to eradicate. However, biofilm studies have been hampered by the fact that most assays utilize nonliving surfaces as biofilm attachment substrates. In an attempt to better understand the mechanisms behind P. aeruginosa biofilm formation, we performed a genetic screen to identify novel factors involved in biofilm formation on biotic and abiotic surfaces. We found that deletion of genes polB and PA14_46880 reduced biofilm formation significantly compared to that in the wild-type strain PA14 in an abiotic biofilm system. In a biotic biofilm model, wherein biofilms form on cultured airway cells, the ΔpolB and ΔPA14_46880 strains showed increased cytotoxic killing of the airway cells independent of the total number of bacteria bound. Notably, deletion mutant strains were more resistant to ciprofloxacin treatment. This phenotype was linked to decreased expression of algR, an alginate transcriptional regulatory gene, under ciprofloxacin pressure. Moreover, we found that pyocyanin production was increased in planktonic cells of mutant strains. These results indicate that inactivation of polB and PA14_46880 may inhibit transition of P. aeruginosa from a more acute infection lifestyle to the biofilm phenotype. Future investigation of these genes may lead to a better understanding of P. aeruginosa biofilm formation and chronic biofilm infections.
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Abstract
Glycosphingolipids are important structural constituents of cellular membranes. They are involved in the formation of nanodomains ("lipid rafts"), which serve as important signaling platforms. Invasive bacterial pathogens exploit these signaling domains to trigger actin polymerization for the bending of the plasma membrane and the engulfment of the bacterium--a key process in bacterial uptake. However, it is unknown whether glycosphingolipids directly take part in the membrane invagination process. Here, we demonstrate that a "lipid zipper," which is formed by the interaction between the bacterial surface lectin LecA and its cellular receptor, the glycosphingolipid Gb3, triggers plasma membrane bending during host cell invasion of the bacterium Pseudomonas aeruginosa. In vitro experiments with Gb3-containing giant unilamellar vesicles revealed that LecA/Gb3-mediated lipid zippering was sufficient to achieve complete membrane engulfment of the bacterium. In addition, theoretical modeling elucidated that the adhesion energy of the LecA-Gb3 interaction is adequate to drive the engulfment process. In cellulo experiments demonstrated that inhibition of the LecA/Gb3 lipid zipper by either lecA knockout, Gb3 depletion, or application of soluble sugars that interfere with LecA binding to Gb3 significantly lowered P. aeruginosa uptake by host cells. Of note, membrane engulfment of P. aeruginosa occurred independently of actin polymerization, thus corroborating that lipid zippering alone is sufficient for this crucial first step of bacterial host-cell entry. Our study sheds new light on the impact of glycosphingolipids in the cellular invasion of bacterial pathogens and provides a mechanistic explication of the initial uptake processes.
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Distinct susceptibilities of corneal Pseudomonas aeruginosa clinical isolates to neutrophil extracellular trap-mediated immunity. Infect Immun 2014; 82:4135-43. [PMID: 25047845 DOI: 10.1128/iai.02169-14] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Ocular bacterial keratitis, often associated with Pseudomonas aeruginosa bacterial infection, commonly occurs in contact lens wearers and may lead to vision impairment. In this study, we analyzed the contribution of neutrophil extracellular traps (NETs) to the mediation of protection during ocular keratitis. Both invasive and cytotoxic P. aeruginosa clinical isolates induced NET release by neutrophils. NETs carried the characteristic histone proteins, elastase, lysozyme, myeloperoxidase, and metabolic enzymes. While the invasive P. aeruginosa strains PAO1 (serogroup O5) and 6294 (serogroup O6) were trapped by NETs, the cytotoxic P. aeruginosa strains 6077, 6206 (serogroup O11), and PA14 (serogroup 010) were less sensitive to NET capture. The mechanism of escape by the cytotoxic strains from adhesion to NETs involved the shedding of outer membrane vesicles (OMVs) that outcompeted the cytotoxic P. aeruginosa strains for NET binding. When ocular infection was caused by an invasive strain in vivo, NETs were released at the ocular surface to capture bacteria, limiting their spread. Treatment with MNase I had a dose-dependent effect, with low doses of MNase speeding up bacterial clearance and high doses of MNase having toxic consequences. Cumulatively, our data suggest that NET-mediated immunity is a two-step process. Initially, pathogens attach to NET fragments; subsequently, upon nuclease activity, active serine proteases, which proteolytically degrade NET-associated proteins and promote DNase activity, are released. Therefore, a balance between NET production and NET degradation is needed to achieve maximal NET immunity.
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