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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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Florek LC, Lin X, Lin YC, Lin MH, Chakraborty A, Price-Whelan A, Tong L, Rahme L, Dietrich LE. The L-lactate dehydrogenases of Pseudomonas aeruginosa are conditionally regulated but both contribute to survival during macrophage infection. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.03.21.586142. [PMID: 38562866 PMCID: PMC10983889 DOI: 10.1101/2024.03.21.586142] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/04/2024]
Abstract
Pseudomonas aeruginosa is an opportunistic pathogen that thrives in environments associated with human activity, including soil and water altered by agriculture or pollution. Because L-lactate is a significant product of plant and animal metabolism, it is available to serve as a carbon source for P. aeruginosa in the diverse settings it inhabits. Here, we evaluate P. aeruginosa's production and use of its redundant L-lactate dehydrogenases, termed LldD and LldA. We confirm that the protein LldR represses lldD and identify a new transcription factor, called LldS, that activates lldA; these distinct regulators and the genomic contexts of lldD and lldA contribute to their differential expression. We demonstrate that the lldD and lldA genes are conditionally controlled in response to lactate isomers as well as to glycolate and - hydroxybutyrate, which, like lactate, are -hydroxycarboxylates. We also show that lldA is induced when iron availability is low. Our examination of lldD and lldA expression across depth in biofilms indicates a complex pattern that is consistent with the effects of glycolate production, iron availability, and cross-regulation on enzyme preference. Finally, macrophage infection assays revealed that both lldD and lldA contribute to persistence within host cells, underscoring the potential role of L-lactate as a carbon source during P. aeruginosa-eukaryote interactions. Together, these findings help us understand the metabolism of a key resource that may promote P. aeruginosa's success as a resident of contaminated environments and animal hosts.
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Affiliation(s)
- Lindsey C. Florek
- Department of Biological Sciences, Columbia University, New York, NY 10027
| | - Xi Lin
- Department of Biological Sciences, Columbia University, New York, NY 10027
| | - Yu-Cheng Lin
- Department of Dentistry, National Yang Ming Chiao Tung University, Taipei, Taiwan 112
| | - Min-Han Lin
- Department of Biological Sciences, Columbia University, New York, NY 10027
| | - Arijit Chakraborty
- Department of Surgery, Massachusetts General Hospital, and Harvard Medical School, Boston, Massachusetts, USA
- Shriners Hospitals for Children Boston, Boston, Massachusetts, USA
| | - Alexa Price-Whelan
- Department of Biological Sciences, Columbia University, New York, NY 10027
| | - Liang Tong
- Department of Biological Sciences, Columbia University, New York, NY 10027
| | - Laurence Rahme
- Department of Surgery, Massachusetts General Hospital, and Harvard Medical School, Boston, Massachusetts, USA
- Shriners Hospitals for Children Boston, Boston, Massachusetts, USA
- Department of Microbiology, Harvard Medical School, Boston, Massachusetts, USA
| | - Lars E.P. Dietrich
- Department of Biological Sciences, Columbia University, New York, NY 10027
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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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4
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Nakatsuka Y, Matsumoto M, Inohara N, Núñez G. Pseudomonas aeruginosa hijacks the murine nitric oxide metabolic pathway to evade killing by neutrophils in the lung. Cell Rep 2023; 42:112973. [PMID: 37561628 DOI: 10.1016/j.celrep.2023.112973] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2023] [Revised: 07/06/2023] [Accepted: 07/27/2023] [Indexed: 08/12/2023] Open
Abstract
Neutrophils play a critical role in the eradication of Pseudomonas aeruginosa, a major pathogen causing lung infection. However, the mechanisms used by the pathogen to evade neutrophil-mediated killing remain poorly understood. Using a high-density transposon screen, we find that P. aeruginosa colonization in the lung is promoted by pathogen nitrite reductase nirD. nirD is required for ammonia production from nitrite, a metabolite derived from nitrogen oxide (NO) generated by inducible NO synthetase (iNOS) in phagocytes. P. aeruginosa deficient in nirD exhibit reduced survival in wild-type neutrophils but not in iNOS-deficient neutrophils. Mechanistically, nirD enhances P. aeruginosa survival in neutrophils by inhibiting the localization of the pathogen in late phagosomes. P. aeruginosa deficient in nirD show impaired lung colonization after infection in wild-type mice but not in mice with selective iNos deficiency in neutrophils. Thus, P. aeruginosa uses neutrophil iNOS-mediated NO production to limit neutrophil pathogen killing and to promote its colonization in the lung.
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Affiliation(s)
- Yoshinari Nakatsuka
- Department of Pathology and Rogel Cancer Center, University of Michigan Medical School, Ann Arbor, MI 48019, USA.
| | - Masanori Matsumoto
- Department of Pathology and Rogel Cancer Center, University of Michigan Medical School, Ann Arbor, MI 48019, USA
| | - Naohiro Inohara
- Department of Pathology and Rogel Cancer Center, University of Michigan Medical School, Ann Arbor, MI 48019, USA
| | - Gabriel Núñez
- Department of Pathology and Rogel Cancer Center, University of Michigan Medical School, Ann Arbor, MI 48019, USA.
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Qerqez AN, Silva RP, Maynard JA. Outsmarting Pathogens with Antibody Engineering. Annu Rev Chem Biomol Eng 2023; 14:217-241. [PMID: 36917814 PMCID: PMC10330301 DOI: 10.1146/annurev-chembioeng-101121-084508] [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: 03/16/2023]
Abstract
There is growing interest in identifying antibodies that protect against infectious diseases, especially for high-risk individuals and pathogens for which no vaccine is yet available. However, pathogens that manifest as opportunistic or latent infections express complex arrays of virulence-associated proteins and are adept at avoiding immune responses. Some pathogens have developed strategies to selectively destroy antibodies, whereas others create decoy epitopes that trick the host immune system into generating antibodies that are at best nonprotective and at worst enhance pathogenesis. Antibody engineering strategies can thwart these efforts by accessing conserved neutralizing epitopes, generating Fc domains that resist capture or degradation and even accessing pathogens hidden inside cells. Design of pathogen-resistant antibodies can enhance protection and guide development of vaccine immunogens against these complex pathogens. Here, we discuss general strategies for design of antibodies resistant to specific pathogen defense mechanisms.
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Affiliation(s)
- Ahlam N Qerqez
- Department of Chemical Engineering, The University of Texas, Austin, Texas, USA;
| | - Rui P Silva
- Department of Molecular Biosciences, The University of Texas, Austin, Texas, USA
| | - Jennifer A Maynard
- Department of Chemical Engineering, The University of Texas, Austin, Texas, 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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Impact of fluoroquinolones and aminoglycosides on P. aeruginosa virulence factor production and cytotoxicity. Biochem J 2022; 479:2511-2527. [PMID: 36504127 DOI: 10.1042/bcj20220527] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2022] [Revised: 12/06/2022] [Accepted: 12/09/2022] [Indexed: 12/14/2022]
Abstract
The opportunistic pathogen Pseudomonas aeruginosa is one of leading causes of disability and mortality worldwide and the world health organisation has listed it with the highest priority for the need of new antimicrobial therapies. P. aeruginosa strains responsible for the poorest clinical outcomes express either ExoS or ExoU, which are injected into target host cells via the type III secretion system (T3SS). ExoS is a bifunctional cytotoxin that promotes intracellular survival of invasive P. aeruginosa by preventing targeting of the bacteria to acidified intracellular compartments. ExoU is a phospholipase which causes destruction of host cell plasma membranes, leading to acute tissue damage and bacterial dissemination. Fluoroquinolones are usually employed as a first line of therapy as they have been shown to be more active against P. aeruginosa in vitrothan other antimicrobial classes. Their overuse over the past decade, however, has resulted in the emergence of antibiotic resistance. In certain clinical situations, aminoglycosides have been shown to be more effective then fluoroquinolones, despite their reduced potency towards P. aeruginosa in vitro. In this study, we evaluated the effects of fluoroquinolones (moxifloxacin and ciprofloxacin) and aminoglycosides (tobramycin and gentamycin) on T3SS expression and toxicity, in corneal epithelial cell infection models. We discovered that tobramycin disrupted T3SS expression and reduced both ExoS and ExoU mediated cytotoxicity, protecting infected HCE-t cells at concentrations below the minimal inhibitory concentration (MIC). The fluoroquinolones moxifloxacin and ciprofloxacin, however, up-regulated the T3SS and did not inhibit and may have increased the cytotoxic effects of ExoS and ExoU.
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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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Jouault A, Saliba AM, Touqui L. Modulation of the immune response by the Pseudomonas aeruginosa type-III secretion system. Front Cell Infect Microbiol 2022; 12:1064010. [PMID: 36519135 PMCID: PMC9742435 DOI: 10.3389/fcimb.2022.1064010] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2022] [Accepted: 11/15/2022] [Indexed: 11/29/2022] Open
Abstract
Pseudomonas aeruginosa is an opportunistic pathogen that can cause critical cellular damage and subvert the immune response to promote its survival. Among the numerous virulence factors of P. aeruginosa, the type III secretion system (T3SS) is involved in host cell pathogenicity. Using a needle-like structure, T3SS detects eukaryotic cells and injects toxins directly into their cytosol, thus highlighting its ability to interfere with the host immune response. In this mini-review, we discuss how the T3SS and bacterial effectors secreted by this pathway not only activate the immune response but can also manipulate it to promote the establishment of P. aeruginosa infections.
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Affiliation(s)
- Albane Jouault
- Mucoviscidose: Phénotypique et Phénogénomique, Centre de Recherche Saint-Antoine, Sorbonne Universités, UPMC Univ Paris 06, INSERM, Paris, France,Département Santé Globale, Mucoviscidose et Bronchopathie Chroniques, Institut Pasteur, Paris, France,*Correspondence: Albane Jouault,
| | - Alessandra Mattos Saliba
- Department of Microbiology, Immunology and Parasitology, Faculty of Medical Sciences, Rio de Janeiro State University, Rio de Janeiro, Brazil
| | - Lhousseine Touqui
- Mucoviscidose: Phénotypique et Phénogénomique, Centre de Recherche Saint-Antoine, Sorbonne Universités, UPMC Univ Paris 06, INSERM, Paris, France,Département Santé Globale, Mucoviscidose et Bronchopathie Chroniques, Institut Pasteur, Paris, France
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10
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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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The Lectin LecB Induces Patches with Basolateral Characteristics at the Apical Membrane to Promote Pseudomonas aeruginosa Host Cell Invasion. mBio 2022; 13:e0081922. [PMID: 35491830 PMCID: PMC9239240 DOI: 10.1128/mbio.00819-22] [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
The opportunistic bacterium Pseudomonas aeruginosa can infect mucosal tissues of the human body. To persist at the mucosal barrier, this highly adaptable pathogen has evolved many strategies, including invasion of host cells. Here, we show that the P. aeruginosa lectin LecB binds and cross-links fucosylated receptors at the apical plasma membrane of epithelial cells. This triggers a signaling cascade via Src kinases and phosphoinositide 3-kinase (PI3K), leading to the formation of patches enriched with the basolateral marker phosphatidylinositol (3,4,5)-trisphosphate (PIP3) at the apical plasma membrane. This identifies LecB as a causative bacterial factor for activating this well-known host cell response that is elicited upon apical binding of P. aeruginosa. Downstream from PI3K, Rac1 is activated to cause actin rearrangement and the outgrowth of protrusions at the apical plasma membrane. LecB-triggered PI3K activation also results in aberrant recruitment of caveolin-1 to the apical domain. In addition, we reveal a positive feedback loop between PI3K activation and apical caveolin-1 recruitment, which provides a mechanistic explanation for the previously observed implication of caveolin-1 in P. aeruginosa host cell invasion. Interestingly, LecB treatment also reversibly removes primary cilia. To directly prove the role of LecB for bacterial uptake, we coated bacterium-sized beads with LecB, which drastically enhanced their endocytosis. Furthermore, LecB deletion and LecB inhibition with l-fucose diminished the invasion efficiency of P. aeruginosa bacteria. Taken together, the results of our study identify LecB as a missing link that can explain how PI3K signaling and caveolin-1 recruitment are triggered to facilitate invasion of epithelial cells from the apical side by P. aeruginosa.
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Kember M, Grandy S, Raudonis R, Cheng Z. Non-Canonical Host Intracellular Niche Links to New Antimicrobial Resistance Mechanism. Pathogens 2022; 11:pathogens11020220. [PMID: 35215166 PMCID: PMC8876822 DOI: 10.3390/pathogens11020220] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2021] [Revised: 02/03/2022] [Accepted: 02/05/2022] [Indexed: 12/04/2022] Open
Abstract
Globally, infectious diseases are one of the leading causes of death among people of all ages. The development of antimicrobials to treat infectious diseases has been one of the most significant advances in medical history. Alarmingly, antimicrobial resistance is a widespread phenomenon that will, without intervention, make currently treatable infections once again deadly. In an era of widespread antimicrobial resistance, there is a constant and pressing need to develop new antibacterial drugs. Unraveling the underlying resistance mechanisms is critical to fight this crisis. In this review, we summarize some emerging evidence of the non-canonical intracellular life cycle of two priority antimicrobial-resistant bacterial pathogens: Pseudomonas aeruginosa and Staphylococcus aureus. The bacterial factors that modulate this unique intracellular niche and its implications in contributing to resistance are discussed. We then briefly discuss some recent research that focused on the promises of boosting host immunity as a combination therapy with antimicrobials to eradicate these two particular pathogens. Finally, we summarize the importance of various strategies, including surveillance and vaccines, in mitigating the impacts of antimicrobial resistance in general.
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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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14
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Molecular Mechanisms Involved in Pseudomonas aeruginosa Bacteremia. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2022; 1386:325-345. [DOI: 10.1007/978-3-031-08491-1_12] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/12/2023]
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15
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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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16
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Rao L, De La Rosa I, Xu Y, Sha Y, Bhattacharya A, Holtzman MJ, Gilbert BE, Eissa NT. Pseudomonas aeruginosa survives in epithelia by ExoS-mediated inhibition of autophagy and mTOR. EMBO Rep 2021; 22:e50613. [PMID: 33345425 PMCID: PMC7857434 DOI: 10.15252/embr.202050613] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2020] [Revised: 10/29/2020] [Accepted: 11/12/2020] [Indexed: 12/12/2022] Open
Abstract
One major factor that contributes to the virulence of Pseudomonas aeruginosa is its ability to reside and replicate unchallenged inside airway epithelial cells. The mechanism by which P. aeruginosa escapes destruction by intracellular host defense mechanisms, such as autophagy, is not known. Here, we show that the type III secretion system effector protein ExoS facilitates P. aeruginosa survival in airway epithelial cells by inhibiting autophagy in host cells. Autophagy inhibition is independent of mTOR activity, as the latter is also inhibited by ExoS, albeit by a different mechanism. Deficiency of the critical autophagy gene Atg7 in airway epithelial cells, both in vitro and in mouse models, greatly enhances the survival of ExoS-deficient P. aeruginosa but does not affect the survival of ExoS-containing bacteria. The inhibitory effect of ExoS on autophagy and mTOR depends on the activity of its ADP-ribosyltransferase domain. Inhibition of mTOR is caused by ExoS-mediated ADP ribosylation of RAS, whereas autophagy inhibition is due to the suppression of autophagic Vps34 kinase activity.
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Affiliation(s)
- Lang Rao
- Department of MedicineBaylor College of MedicineHoustonTXUSA
- Veterans Administration Long Beach Health Care System and University of California at IrvineIrvineCAUSA
- Southern California Institute for Research and EducationLong BeachCAUSA
| | | | - Yi Xu
- Department of MedicineBaylor College of MedicineHoustonTXUSA
| | - Youbao Sha
- Department of MedicineBaylor College of MedicineHoustonTXUSA
| | | | - Michael J Holtzman
- Department of Internal MedicineWashington University School of MedicineSt. LouisMOUSA
| | - Brian E Gilbert
- Department of Molecular Virology and MicrobiologyBaylor College of MedicineHoustonTXUSA
| | - N Tony Eissa
- Department of MedicineBaylor College of MedicineHoustonTXUSA
- Veterans Administration Long Beach Health Care System and University of California at IrvineIrvineCAUSA
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17
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Moussouni M, Berry L, Sipka T, Nguyen-Chi M, Blanc-Potard AB. Pseudomonas aeruginosa OprF plays a role in resistance to macrophage clearance during acute infection. Sci Rep 2021; 11:359. [PMID: 33432030 PMCID: PMC7801371 DOI: 10.1038/s41598-020-79678-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2020] [Accepted: 12/11/2020] [Indexed: 12/14/2022] Open
Abstract
While considered an extracellular pathogen, Pseudomonas aeruginosa has been reported to be engulfed by macrophages in cellular and animal models. However, the role of macrophages in P. aeruginosa clearance in vivo remains poorly studied. The major outer membrane porin OprF has been recently shown to be involved in P. aeruginosa fate within cultured macrophages and analysis of an oprF mutant may thus provide insights to better understand the relevance of this intramacrophage stage during infection. In the present study, we investigated for the first time the virulence of a P. aeruginosa oprF mutant in a vertebrate model that harbors functional macrophages, the zebrafish (Danio rerio) embryo, which offers powerful tools to address macrophage–pathogen interactions. We established that P. aeruginosa oprF mutant is attenuated in zebrafish embryos in a macrophage-dependent manner. Visualization and quantification of P. aeruginosa bacteria phagocytosed by macrophages after injection into closed cavities suggested that the attenuated phenotype of oprF mutant is not linked to higher macrophage recruitment nor better phagocytosis than wild-type strain. Using cultured macrophages, we showed an intramacrophage survival defect of P. aeruginosa oprF mutant, which is correlated with elevated association of bacteria with acidic compartments. Notably, treatment of embryos with bafilomycin, an inhibitor of acidification, increased the sensibility of embryos towards both wild-type and oprF mutant, and partially suppressed the attenuation of oprF mutant. Taken together, this work supports zebrafish embryo as state-of-the-art model to address in vivo the relevance of P. aeruginosa intramacrophage stage. Our results highlight the contribution of macrophages in the clearance of P. aeruginosa during acute infection and suggest that OprF protects P. aeruginosa against macrophage clearance by avoiding bacterial elimination in acidified phagosomes.
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Affiliation(s)
- Malika Moussouni
- Laboratory of Pathogen-Host Interactions (LPHI), CNRS-UMR5235, Université de Montpellier, Montpellier, France
| | - Laurence Berry
- Laboratory of Pathogen-Host Interactions (LPHI), CNRS-UMR5235, Université de Montpellier, Montpellier, France
| | - Tamara Sipka
- Laboratory of Pathogen-Host Interactions (LPHI), CNRS-UMR5235, Université de Montpellier, Montpellier, France
| | - Mai Nguyen-Chi
- Laboratory of Pathogen-Host Interactions (LPHI), CNRS-UMR5235, Université de Montpellier, Montpellier, France
| | - Anne-Béatrice Blanc-Potard
- Laboratory of Pathogen-Host Interactions (LPHI), CNRS-UMR5235, Université de Montpellier, Montpellier, France.
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18
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Armentrout EI, Kundracik EC, Rietsch A. Cell-type-specific hypertranslocation of effectors by the Pseudomonas aeruginosa type III secretion system. Mol Microbiol 2020; 115:305-319. [PMID: 33012037 DOI: 10.1111/mmi.14617] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2020] [Revised: 09/22/2020] [Indexed: 12/23/2022]
Abstract
Many Gram-negative pathogens use a type III secretion system (T3SS) to promote disease by injecting effector proteins into host cells. Common to many T3SSs is that injection of effector proteins is feedback inhibited. The mechanism of feedback inhibition and its role in pathogenesis are unclear. In the case of P. aeruginosa, the effector protein ExoS is central to limiting effector injection. ExoS is bifunctional, with an amino-terminal RhoGAP and a carboxy-terminal ADP-ribosyltransferase domain. We demonstrate that both domains are required to fully feedback inhibit effector injection. The RhoGAP-, but not the ADP-ribosyltransferase domain of the related effector protein ExoT also participates. Feedback inhibition does not involve translocator insertion nor pore-formation. Instead, feedback inhibition is due, in part, to a loss of the activating trigger for effector injection, and likely also decreased translocon stability. Surprisingly, feedback inhibition is abrogated in phagocytic cells. The lack of feedback inhibition in these cells requires phagocytic uptake of the bacteria, but cannot be explained through acidification of the phagosome or calcium limitation. Given that phagocytes are crucial for controlling P. aeruginosa infections, our data suggest that feedback inhibition allows P. aeruginosa to direct its effector arsenal against the cell types most damaging to its survival.
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Affiliation(s)
- Erin I Armentrout
- Department of Molecular Biology and Microbiology, Case Western Reserve University, Cleveland, OH, USA
| | - Emma C Kundracik
- Department of Molecular Biology and Microbiology, Case Western Reserve University, Cleveland, OH, USA
| | - Arne Rietsch
- Department of Molecular Biology and Microbiology, Case Western Reserve University, Cleveland, OH, USA
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19
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Josephson H, Ntzouni M, Skoglund C, Linder S, Turkina MV, Vikström E. Pseudomonas aeruginosa N-3-Oxo-Dodecanoyl-Homoserine Lactone Impacts Mitochondrial Networks Morphology, Energetics, and Proteome in Host Cells. Front Microbiol 2020; 11:1069. [PMID: 32523583 PMCID: PMC7261938 DOI: 10.3389/fmicb.2020.01069] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2020] [Accepted: 04/29/2020] [Indexed: 01/10/2023] Open
Abstract
Mitochondria play crucial roles in cellular metabolism, signaling, longevity, and immune defense. Recent evidences have revealed that the host microbiota, including bacterial pathogens, impact mitochondrial behaviors and activities in the host. The pathogenicity of Pseudomonas aeruginosa requires quorum sensing (QS) cell-cell communication allowing the bacteria to sense population density and collectively control biofilm development, virulence traits, adaptation and interactions with the host. QS molecules, like N-3-oxo-dodecanoyl-L-homoserine lactone (3O-C12-HSL), can also modulate the behavior of host cells, e.g., epithelial barrier properties and innate immune responses. Here, in two types of cells, fibroblasts and intestinal epithelial cells, we investigated whether and how P. aeruginosa 3O-C12-HSL impacts the morphology of mitochondrial networks and their energetic characteristics, using high-resolution transmission electron microscopy, fluorescence live-cell imaging, assay for mitochondrial bioenergetics, and quantitative mass spectrometry for mitoproteomics and bioinformatics. We found that 3O-C12-HSL induced fragmentation of mitochondria, disruption of cristae and inner membrane ultrastructure, altered major characteristics of respiration and energetics, and decreased mitochondrial membrane potential, and that there are distinct cell-type specific details of these effects. Moreover, this was mechanistically accompanied by differential expression of both common and cell-type specific arrays of components in the mitochondrial proteome involved in their structural organization, electron transport chain complexes and response to stress. We suggest that this effect of 3O-C12-HSL on mitochondria may represent one of the events in the interaction between P. aeruginosa and host mitochondria and may have an impact on the pathogens strategy to hijack host cell activities to support their own survival and spreading.
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Affiliation(s)
- Henrik Josephson
- Department of Biomedical and Clinical Sciences, Faculty of Medicine and Health Sciences, Linköping University, Linköping, Sweden
| | - Maria Ntzouni
- Core Facility, Faculty of Medicine and Health Sciences, Linköping University, Linköping, Sweden
| | - Camilla Skoglund
- Department of Biomedical and Clinical Sciences, Faculty of Medicine and Health Sciences, Linköping University, Linköping, Sweden
| | - Stig Linder
- Department of Biomedical and Clinical Sciences, Faculty of Medicine and Health Sciences, Linköping University, Linköping, Sweden
| | - Maria V Turkina
- Department of Biomedical and Clinical Sciences, Faculty of Medicine and Health Sciences, Linköping University, Linköping, Sweden
| | - Elena Vikström
- Department of Biomedical and Clinical Sciences, Faculty of Medicine and Health Sciences, Linköping University, Linköping, Sweden
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20
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Mukherjee K, Khatua B, Mandal C. Sialic Acid-Siglec-E Interactions During Pseudomonas aeruginosa Infection of Macrophages Interferes With Phagosome Maturation by Altering Intracellular Calcium Concentrations. Front Immunol 2020; 11:332. [PMID: 32184783 PMCID: PMC7059019 DOI: 10.3389/fimmu.2020.00332] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2019] [Accepted: 02/10/2020] [Indexed: 11/24/2022] Open
Abstract
Pseudomonas aeruginosa (PA) is commonly associated with nosocomial and chronic infections of lungs. We have earlier demonstrated that an acidic sugar, sialic acid, is present in PA which is recognized and bound by sialic acid binding immunoglobulin type lectins (siglecs) expressed on neutrophils. Here, we have tried to gain a detailed insight into the immunosuppressive role of sialic acid-siglec interactions in macrophage-mediated clearance of sialylated PA (PA+Sia). We have demonstrated that PA+Sia shows enhanced binding (~1.5-fold) to macrophages due to additional interactions between sialic acids and siglec-E and exhibited more phagocytosis. However, internalization of PA+Sia is associated with a reduction in respiratory burst and increase in anti-inflammatory cytokines secretion which is reversed upon desialylation of the bacteria. Phagocytosis of PA+Sia is also associated with reduced intracellular calcium ion concentrations and altered calcium-dependent signaling which negatively affects phagosome maturation. Consequently, although more PA+Sia was localized in early phagosomes (Rab5 compartment), only fewer bacteria reach into the late phagosomal compartment (Rab7). Possibly, this leads to reduced phagosome lysosome fusion where reduced numbers of PA+Sia are trafficked into lysosomes, compared to PA−Sia. Thus, internalized PA+Sia remain viable and replicates intracellularly in macrophages. We have also demonstrated that such siglec-E-sialic acid interaction recruited SHP-1/SHP-2 phosphatases which modulate MAPK and NF-κB signaling pathways. Disrupting sialic acid-siglec-E interaction by silencing siglec-E in macrophages results in improved bactericidal response against PA+Sia characterized by robust respiratory burst, enhanced intracellular calcium levels and nuclear translocation of p65 component of NF-κB complex leading to increased pro-inflammatory cytokine secretion. Taken together, we have identified that sialic acid-siglec-E interactions is another pathway utilized by PA in order to suppress macrophage antimicrobial responses and inhibit phagosome maturation, thereby persisting as an intracellular pathogen in macrophages.
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Affiliation(s)
- Kaustuv Mukherjee
- Cancer Biology and Inflammatory Disorder Division, CSIR-Indian Institute of Chemical Biology, Kolkata, India
| | - Biswajit Khatua
- Cancer Biology and Inflammatory Disorder Division, CSIR-Indian Institute of Chemical Biology, Kolkata, India
| | - Chitra Mandal
- Cancer Biology and Inflammatory Disorder Division, CSIR-Indian Institute of Chemical Biology, Kolkata, India
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21
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Casadevall A, Fang FC. The intracellular pathogen concept. Mol Microbiol 2019; 113:541-545. [PMID: 31762116 DOI: 10.1111/mmi.14421] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/06/2019] [Indexed: 12/21/2022]
Abstract
The intracellular pathogen concept classifies pathogenic microbes on the basis of their site of replication and dependence on host cells. This concept played a fundamental role in establishing the field of cellular microbiology, founded in part by Dr. Pascale Cossart, whose seminal contributions are honored in this issue of Molecular Microbiology. The recognition that microbes can access and replicate in privileged compartments within host cells has led to many new and fruitful lines of investigation into the biology of the cell and mechanisms of cell-mediated immunity. However, like any scientific concept, the intracellular pathogen concept can become a dogma that constrains thinking and oversimplifies complex and dynamic host-pathogen interactions. Growing evidence has blurred the distinction between "intracellular" and "extracellular" pathogens and demonstrated that many pathogens can exist both within and outside of cells. Although the intracellular pathogen concept remains useful, it should not be viewed as a rigid classification of pathogenic microbes, which exhibit remarkable variation and complexity in their behavior in the host.
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Affiliation(s)
- Arturo Casadevall
- Department of Molecular Microbiology and Immunology, Johns Hopkins School of Public Health, Baltimore, MD, USA
| | - Ferric C Fang
- Departments of Laboratory Medicine and Microbiology, University of Washington School of Medicine, Seattle, WA, USA
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22
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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: 51] [Impact Index Per Article: 10.2] [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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23
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Pseudomonas aeruginosa ExsA Regulates a Metalloprotease, ImpA, That Inhibits Phagocytosis of Macrophages. Infect Immun 2019; 87:IAI.00695-19. [PMID: 31527124 DOI: 10.1128/iai.00695-19] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2019] [Accepted: 09/09/2019] [Indexed: 02/08/2023] Open
Abstract
Pseudomonas aeruginosa is an opportunistic pathogenic bacterium whose type III secretion system (T3SS) plays a critical role in acute infections. Translocation of the T3SS effectors into host cells induces cytotoxicity. In addition, the T3SS promotes the intracellular growth of P. aeruginosa during host infections. The T3SS regulon genes are regulated by an AraC-type regulator, ExsA. In this study, we found that an extracellular metalloprotease encoded by impA (PA0572) is under the regulation of ExsA. An ExsA consensus binding sequence was identified upstream of the impA gene, and direct binding of the site by ExsA was demonstrated via an electrophoretic mobility shift assay. We further demonstrate that secreted ImpA cleaves the macrophage surface protein CD44, which inhibits the phagocytosis of the bacterial cells by macrophages. Combined, our results reveal a novel ExsA-regulated virulence factor that cooperatively inhibits the functions of macrophages with the T3SS.
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24
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Hritonenko V, Metruccio M, Evans D, Fleiszig S. Epithelial cell lysates induce ExoS expression and secretion by Pseudomonas aeruginosa. FEMS Microbiol Lett 2019. [PMID: 29518189 DOI: 10.1093/femsle/fny053] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
The type three secretion system (T3SS) is important for the intracellular survival of Pseudomonas aeruginosa. Known T3SS inducers include low Ca2+, serum or host cell contact. Here, we used corneal epithelial cell lysates to test if host cytosolic factors could also induce the T3SS. Invasive P. aeruginosa strain PAO1 was exposed to cell lysates for 16 h, and expression of T3SS effectors determined by q-PCR and Western immunoblot. Lysate exposure reduced PAO1 growth (∼5-fold) versus trypticase soy broth (TSB), but also resulted in appearance of a protein in culture supernatants, but not bacterial cell pellets, which reacted with antibody raised against ExoS. T3SS-inducing media (TSBi) caused the expression and secretion of ExoS and ExoT. Heat-treated lysates induced the protein; 1:3 diluted lysates did not. The protein that bound anti-ExoS antibody was found in supernatants of lysate-exposed exoT mutants, but not exoS or pscC mutants, suggesting a secreted form of ExoS, albeit slightly larger than that induced by TSBi. Lysate-exposed strain PAK expressed the same protein. Lysates caused PAO1 exoS and exoT gene expression, but only ∼20% and ∼6% of TSBi, respectively. T3SS induction by epithelial cell lysates could help explain T3SS expression by internalized P. aeruginosa.
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Affiliation(s)
| | - Matteo Metruccio
- School of Optometry, University of California, Berkeley, CA 94720-2020, USA
| | - David Evans
- School of Optometry, University of California, Berkeley, CA 94720-2020, USA.,College of Pharmacy, Touro University California, Vallejo, CA 94592-2020, USA
| | - Suzanne Fleiszig
- School of Optometry, University of California, Berkeley, CA 94720-2020, USA.,Graduate Groups in Vision Science, Microbiology, and Infectious Diseases & Immunity, University of California, Berkeley, CA 94720-2020, USA
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25
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Nieto V, Kroken AR, Grosser MR, Smith BE, Metruccio MME, Hagan P, Hallsten ME, Evans DJ, Fleiszig SMJ. Type IV Pili Can Mediate Bacterial Motility within Epithelial Cells. mBio 2019; 10:e02880-18. [PMID: 31431558 PMCID: PMC6703432 DOI: 10.1128/mbio.02880-18] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2018] [Accepted: 07/31/2019] [Indexed: 02/07/2023] Open
Abstract
Pseudomonas aeruginosa is among bacterial pathogens capable of twitching motility, a form of surface-associated movement dependent on type IV pili (T4P). Previously, we showed that T4P and twitching were required for P. aeruginosa to cause disease in a murine model of corneal infection, to traverse human corneal epithelial multilayers, and to efficiently exit invaded epithelial cells. Here, we used live wide-field fluorescent imaging combined with quantitative image analysis to explore how twitching contributes to epithelial cell egress. Results using time-lapse imaging of cells infected with wild-type PAO1 showed that cytoplasmic bacteria slowly disseminated throughout the cytosol at a median speed of >0.05 μm s-1 while dividing intracellularly. Similar results were obtained with flagellin (fliC) and flagellum assembly (flhA) mutants, thereby excluding swimming, swarming, and sliding as mechanisms. In contrast, pilA mutants (lacking T4P) and pilT mutants (twitching motility defective) appeared stationary and accumulated in expanding aggregates during intracellular division. Transmission electron microscopy confirmed that these mutants were not trapped within membrane-bound cytosolic compartments. For the wild type, dissemination in the cytosol was not prevented by the depolymerization of actin filaments using latrunculin A and/or the disruption of microtubules using nocodazole. Together, these findings illustrate a novel form of intracellular bacterial motility differing from previously described mechanisms in being directly driven by bacterial motility appendages (T4P) and not depending on polymerized host actin or microtubules.IMPORTANCE Host cell invasion can contribute to disease pathogenesis by the opportunistic pathogen Pseudomonas aeruginosa Previously, we showed that the type III secretion system (T3SS) of invasive P. aeruginosa strains modulates cell entry and subsequent escape from vacuolar trafficking to host lysosomes. However, we also showed that mutants lacking either type IV pili (T4P) or T4P-dependent twitching motility (i) were defective in traversing cell multilayers, (ii) caused less pathology in vivo, and (iii) had a reduced capacity to exit invaded cells. Here, we report that after vacuolar escape, intracellular P. aeruginosa can use T4P-dependent twitching motility to disseminate throughout the host cell cytoplasm. We further show that this strategy for intracellular dissemination does not depend on flagellin and resists both host actin and host microtubule disruption. This differs from mechanisms used by previously studied pathogens that utilize either host actin or microtubules for intracellular dissemination independently of microbe motility appendages.
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Affiliation(s)
- Vincent Nieto
- School of Optometry, University of California, Berkeley, California, USA
| | - Abby R Kroken
- School of Optometry, University of California, Berkeley, California, USA
| | - Melinda R Grosser
- School of Optometry, University of California, Berkeley, California, USA
| | - Benjamin E Smith
- Vision Science Program, University of California, Berkeley, California, USA
| | | | - Patrick Hagan
- Undergraduate Research Apprentice Program, University of California, Berkeley, California, USA
| | - Mary E Hallsten
- Undergraduate Research Apprentice Program, University of California, Berkeley, California, USA
| | - David J Evans
- School of Optometry, University of California, Berkeley, California, USA
- College of Pharmacy, Touro University California, Vallejo, California, USA
| | - Suzanne M J Fleiszig
- School of Optometry, University of California, Berkeley, California, USA
- Vision Science Program, University of California, Berkeley, California, USA
- Graduate Group in Microbiology, University of California, Berkeley, California, USA
- Graduate Group in Infectious Diseases and Immunity, University of California, Berkeley, California, USA
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26
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Feng C, Huang Y, He W, Cheng X, Liu H, Huang Y, Ma B, Zhang W, Liao C, Wu W, Shao Y, Xu D, Su Z, Lu W. Tanshinones: First-in-Class Inhibitors of the Biogenesis of the Type 3 Secretion System Needle of Pseudomonas aeruginosa for Antibiotic Therapy. ACS CENTRAL SCIENCE 2019; 5:1278-1288. [PMID: 31403076 PMCID: PMC6662154 DOI: 10.1021/acscentsci.9b00452] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/07/2019] [Indexed: 05/17/2023]
Abstract
The type 3 secretion system (T3SS) found as cell-surface appendages of many pathogenic Gram-negative bacteria, although nonessential for bacterial survival, is an important therapeutic target for drug discovery and development aimed at inhibiting bacterial virulence without inducing antibiotic resistance. We designed a fluorescence-polarization-based assay for high-throughput screening as a mechanistically well-defined general strategy for antibiotic discovery targeting the T3SS and made a serendipitous discovery of a subset of tanshinones-natural herbal compounds in traditional Chinese medicine widely used for the treatment of cardiovascular and cerebrovascular diseases-as effective inhibitors of the biogenesis of the T3SS needle of multi-drug-resistant Pseudomonas aeruginosa. By inhibiting the T3SS needle assembly and, thus, cytotoxicity and pathogenicity, selected tanshinones reduced the secretion of bacterial virulence factors toxic to macrophages in vitro, and rescued experimental animals challenged with lethal doses of Pseudomonas aeruginosa in a murine model of acute pneumonia. As first-in-class inhibitors with a demonstrable safety profile in humans, tanshinones may be used directly to alleviate Pseudomonas-aeruginosa-associated pulmonary infections without inducing antibiotic resistance. Since the T3SS is highly conserved among Gram-negative bacteria, this antivirulence strategy may be applicable to the discovery and development of novel classes of antibiotics refractory to existing resistance mechanisms for the treatment of many bacterial infections.
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Affiliation(s)
- Chao Feng
- Center
for Translational Medicine, Frontier Institute of Science
and Technology, Shaanxi Institute of Pediatric Diseases, Affiliated Children’s
Hospital, and Key Laboratory of Biomedical Information Engineering of the Ministry
of Education, School of Life Science and Technology, Xi’an Jiaotong University, Xi’an 710054, China
| | - Yinong Huang
- Center
for Translational Medicine, Frontier Institute of Science
and Technology, Shaanxi Institute of Pediatric Diseases, Affiliated Children’s
Hospital, and Key Laboratory of Biomedical Information Engineering of the Ministry
of Education, School of Life Science and Technology, Xi’an Jiaotong University, Xi’an 710054, China
| | - Wangxiao He
- Center
for Translational Medicine, Frontier Institute of Science
and Technology, Shaanxi Institute of Pediatric Diseases, Affiliated Children’s
Hospital, and Key Laboratory of Biomedical Information Engineering of the Ministry
of Education, School of Life Science and Technology, Xi’an Jiaotong University, Xi’an 710054, China
| | - Xiyao Cheng
- Department
of Biological and Food Engineering, Hubei
University of Technology, Wuhan 430068, China
| | - Huili Liu
- State
Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Chinese
Academy of Sciences, Wuhan 430071, China
| | - Yongqi Huang
- Department
of Biological and Food Engineering, Hubei
University of Technology, Wuhan 430068, China
| | - Bohan Ma
- Center
for Translational Medicine, Frontier Institute of Science
and Technology, Shaanxi Institute of Pediatric Diseases, Affiliated Children’s
Hospital, and Key Laboratory of Biomedical Information Engineering of the Ministry
of Education, School of Life Science and Technology, Xi’an Jiaotong University, Xi’an 710054, China
| | - Wei Zhang
- Center
for Translational Medicine, Frontier Institute of Science
and Technology, Shaanxi Institute of Pediatric Diseases, Affiliated Children’s
Hospital, and Key Laboratory of Biomedical Information Engineering of the Ministry
of Education, School of Life Science and Technology, Xi’an Jiaotong University, Xi’an 710054, China
| | - Chongbing Liao
- Center
for Translational Medicine, Frontier Institute of Science
and Technology, Shaanxi Institute of Pediatric Diseases, Affiliated Children’s
Hospital, and Key Laboratory of Biomedical Information Engineering of the Ministry
of Education, School of Life Science and Technology, Xi’an Jiaotong University, Xi’an 710054, China
| | - Weihui Wu
- State Key
Laboratory of Medicinal Chemical Biology, Key Laboratory of Molecular
Microbiology and Technology of the Ministry of Education, Department
of Microbiology, College of Life Sciences, Nankai University, Tianjin 300071, China
| | - Yongping Shao
- Center
for Translational Medicine, Frontier Institute of Science
and Technology, Shaanxi Institute of Pediatric Diseases, Affiliated Children’s
Hospital, and Key Laboratory of Biomedical Information Engineering of the Ministry
of Education, School of Life Science and Technology, Xi’an Jiaotong University, Xi’an 710054, China
| | - Dan Xu
- Center
for Translational Medicine, Frontier Institute of Science
and Technology, Shaanxi Institute of Pediatric Diseases, Affiliated Children’s
Hospital, and Key Laboratory of Biomedical Information Engineering of the Ministry
of Education, School of Life Science and Technology, Xi’an Jiaotong University, Xi’an 710054, China
| | - Zhengding Su
- Department
of Biological and Food Engineering, Hubei
University of Technology, Wuhan 430068, China
| | - Wuyuan Lu
- Institute
of Human Virology and Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, Maryland 21201, United States
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Garai P, Berry L, Moussouni M, Bleves S, Blanc-Potard AB. Killing from the inside: Intracellular role of T3SS in the fate of Pseudomonas aeruginosa within macrophages revealed by mgtC and oprF mutants. PLoS Pathog 2019; 15:e1007812. [PMID: 31220187 PMCID: PMC6586356 DOI: 10.1371/journal.ppat.1007812] [Citation(s) in RCA: 48] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2019] [Accepted: 05/02/2019] [Indexed: 12/19/2022] Open
Abstract
While considered solely an extracellular pathogen, increasing evidence indicates that Pseudomonas aeruginosa encounters intracellular environment in diverse mammalian cell types, including macrophages. In the present study, we have deciphered the intramacrophage fate of wild-type P. aeruginosa PAO1 strain by live and electron microscopy. P. aeruginosa first resided in phagosomal vacuoles and subsequently could be detected in the cytoplasm, indicating phagosomal escape of the pathogen, a finding also supported by vacuolar rupture assay. The intracellular bacteria could eventually induce cell lysis, both in a macrophage cell line and primary human macrophages. Two bacterial factors, MgtC and OprF, recently identified to be important for survival of P. aeruginosa in macrophages, were found to be involved in bacterial escape from the phagosome as well as in cell lysis caused by intracellular bacteria. Strikingly, type III secretion system (T3SS) genes of P. aeruginosa were down-regulated within macrophages in both mgtC and oprF mutants. Concordantly, cyclic di-GMP (c-di-GMP) level was increased in both mutants, providing a clue for negative regulation of T3SS inside macrophages. Consistent with the phenotypes and gene expression pattern of mgtC and oprF mutants, a T3SS mutant (ΔpscN) exhibited defect in phagosomal escape and macrophage lysis driven by internalized bacteria. Importantly, these effects appeared to be largely dependent on the ExoS effector, in contrast with the known T3SS-dependent, but ExoS independent, cytotoxicity caused by extracellular P. aeruginosa towards macrophages. Moreover, this macrophage damage caused by intracellular P. aeruginosa was found to be dependent on GTPase Activating Protein (GAP) domain of ExoS. Hence, our work highlights T3SS and ExoS, whose expression is modulated by MgtC and OprF, as key players in the intramacrophage life of P. aeruginosa which allow internalized bacteria to lyse macrophages. The ability of professional phagocytes to ingest and kill microorganisms is central to host defense and Pseudomonas aeruginosa has developed mechanisms to avoid being killed by phagocytes. While considered an extracellular pathogen, P. aeruginosa has been reported to be engulfed by macrophages in animal models. Here, we visualized the fate of P. aeruginosa within cultured macrophages, revealing macrophage lysis driven by intracellular P. aeruginosa. Two bacterial factors, MgtC and OprF, recently discovered to be involved in the intramacrophage survival of P. aeruginosa, appeared to play a role in this cytotoxicity caused by intracellular bacteria. We provided evidence that type III secretion system (T3SS) gene expression is lowered intracellularly in mgtC and oprF mutants. We further showed that intramacrophage P. aeruginosa uses its T3SS, specifically the ExoS effector, to promote phagosomal escape and cell lysis. We thus describe a transient intramacrophage stage of P. aeruginosa that could contribute to bacterial dissemination.
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Affiliation(s)
- Preeti Garai
- Laboratoire de Dynamique des Interactions Membranaires Normales et Pathologiques, Université de Montpellier, CNRS-UMR5235, Montpellier, France
| | - Laurence Berry
- Laboratoire de Dynamique des Interactions Membranaires Normales et Pathologiques, Université de Montpellier, CNRS-UMR5235, Montpellier, France
| | - Malika Moussouni
- Laboratoire de Dynamique des Interactions Membranaires Normales et Pathologiques, Université de Montpellier, CNRS-UMR5235, Montpellier, France
| | - Sophie Bleves
- LISM, Institut de Microbiologie de la Méditerranée, CNRS & Aix-Marseille Univ, Marseille, France
| | - Anne-Béatrice Blanc-Potard
- Laboratoire de Dynamique des Interactions Membranaires Normales et Pathologiques, Université de Montpellier, CNRS-UMR5235, Montpellier, France
- * E-mail:
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Brothers KM, Callaghan JD, Stella NA, Bachinsky JM, AlHigaylan M, Lehner KL, Franks JM, Lathrop KL, Collins E, Schmitt DM, Horzempa J, Shanks RMQ. Blowing epithelial cell bubbles with GumB: ShlA-family pore-forming toxins induce blebbing and rapid cellular death in corneal epithelial cells. PLoS Pathog 2019; 15:e1007825. [PMID: 31220184 PMCID: PMC6586354 DOI: 10.1371/journal.ppat.1007825] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2018] [Accepted: 05/07/2019] [Indexed: 12/18/2022] Open
Abstract
Medical devices, such as contact lenses, bring bacteria in direct contact with human cells. Consequences of these host-pathogen interactions include the alteration of mammalian cell surface architecture and induction of cellular death that renders tissues more susceptible to infection. Gram-negative bacteria known to induce cellular blebbing by mammalian cells, Pseudomonas and Vibrio species, do so through a type III secretion system-dependent mechanism. This study demonstrates that a subset of bacteria from the Enterobacteriaceae bacterial family induce cellular death and membrane blebs in a variety of cell types via a type V secretion-system dependent mechanism. Here, we report that ShlA-family cytolysins from Proteus mirabilis and Serratia marcescens were required to induce membrane blebbling and cell death. Blebbing and cellular death were blocked by an antioxidant and RIP-1 and MLKL inhibitors, implicating necroptosis in the observed phenotypes. Additional genetic studies determined that an IgaA family stress-response protein, GumB, was necessary to induce blebs. Data supported a model where GumB and shlBA are in a regulatory circuit through the Rcs stress response phosphorelay system required for bleb formation and pathogenesis in an invertebrate model of infection and proliferation in a phagocytic cell line. This study introduces GumB as a regulator of S. marcescens host-pathogen interactions and demonstrates a common type V secretion system-dependent mechanism by which bacteria elicit surface morphological changes on mammalian cells. This type V secretion-system mechanism likely contributes bacterial damage to the corneal epithelial layer, and enables access to deeper parts of the tissue that are more susceptible to infection.
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Affiliation(s)
- Kimberly M. Brothers
- Department of Ophthalmology, University of Pittsburgh, Pittsburgh, PA United States of America
- Charles T. Campbell Laboratory of Ophthalmic Microbiology
| | - Jake D. Callaghan
- Department of Ophthalmology, University of Pittsburgh, Pittsburgh, PA United States of America
- Charles T. Campbell Laboratory of Ophthalmic Microbiology
| | - Nicholas A. Stella
- Department of Ophthalmology, University of Pittsburgh, Pittsburgh, PA United States of America
- Charles T. Campbell Laboratory of Ophthalmic Microbiology
| | - Julianna M. Bachinsky
- Department of Ophthalmology, University of Pittsburgh, Pittsburgh, PA United States of America
- Charles T. Campbell Laboratory of Ophthalmic Microbiology
| | - Mohammed AlHigaylan
- Department of Ophthalmology, University of Pittsburgh, Pittsburgh, PA United States of America
- Charles T. Campbell Laboratory of Ophthalmic Microbiology
| | - Kara L. Lehner
- Department of Ophthalmology, University of Pittsburgh, Pittsburgh, PA United States of America
- Charles T. Campbell Laboratory of Ophthalmic Microbiology
| | - Jonathan M. Franks
- Center for Biological Imaging, University of Pittsburgh, Pittsburgh, PA United States of America
| | - Kira L. Lathrop
- Department of Ophthalmology, University of Pittsburgh, Pittsburgh, PA United States of America
| | - Elliot Collins
- Department of Natural Sciences and Mathematics, West Liberty University, West Liberty, WV United States of America
| | - Deanna M. Schmitt
- Department of Natural Sciences and Mathematics, West Liberty University, West Liberty, WV United States of America
| | - Joseph Horzempa
- Department of Natural Sciences and Mathematics, West Liberty University, West Liberty, WV United States of America
| | - Robert M. Q. Shanks
- Department of Ophthalmology, University of Pittsburgh, Pittsburgh, PA United States of America
- Charles T. Campbell Laboratory of Ophthalmic Microbiology
- * E-mail:
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29
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Bogiel T, Deptuła A, Kwiecińska-Piróg J, Prażyńska M, Mikucka A, Gospodarek-Komkowska E. The Prevalence of Exoenzyme S Gene in Multidrug-Sensitive and Multidrug-Resistant Pseudomonas aeruginosa Clinical Strains. Pol J Microbiol 2019; 66:427-431. [PMID: 29313517 DOI: 10.5604/01.3001.0010.6500] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Pseudomonas aeruginosa rods are one of the most commonly isolated microorganisms from clinical specimens, usually responsible for nosocomial infections. Antibiotic-resistant P. aeruginosa strains may present reduced expression of virulence factors. This fact may be caused by appropriate genome management to adapt to changing conditions of the hospital environment. Virulence factors genes may be replaced by those crucial to survive, like antimicrobial resistance genes. The aim of this study was to evaluate, using PCR, the occurrence of exoenzyme S-coding gene (exoS) in two distinct groups of P. aeruginosa strains: 83 multidrug-sensitive (MDS) and 65 multidrug-resistant (MDR) isolates. ExoS gene was noted in 72 (48.7%) of the examined strains: 44 (53.0%) MDS and 28 (43.1%) MDR. The observed differences were not statistically significant (p = 0.1505). P. aeruginosa strains virulence is rather determined by the expression regulation of the possessed genes than the difference in genes frequency amongst strains with different antimicrobial susceptibility patterns.
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Affiliation(s)
- Tomasz Bogiel
- Department of Microbiology, Ludwik Rydygier Collegium Medicum in Bydgoszcz, Nicolaus Copernicus University in Toruń, Poland
| | - Aleksander Deptuła
- Department of Microbiology, Ludwik Rydygier Collegium Medicum in Bydgoszcz, Nicolaus Copernicus University in Toruń, Poland
| | - Joanna Kwiecińska-Piróg
- Department of Microbiology, Ludwik Rydygier Collegium Medicum in Bydgoszcz, Nicolaus Copernicus University in Toruń, Poland
| | - Małgorzata Prażyńska
- Department of Microbiology, Ludwik Rydygier Collegium Medicum in Bydgoszcz, Nicolaus Copernicus University in Toruń, Poland
| | - Agnieszka Mikucka
- Department of Microbiology, Ludwik Rydygier Collegium Medicum in Bydgoszcz, Nicolaus Copernicus University in Toruń, Poland
| | - Eugenia Gospodarek-Komkowska
- Department of Microbiology, Ludwik Rydygier Collegium Medicum in Bydgoszcz, Nicolaus Copernicus University in Toruń, Poland
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30
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Mohankumar V, Ramalingam S, Chidambaranathan GP, Prajna L. Autophagy induced by type III secretion system toxins enhances clearance of Pseudomonas aeruginosa from human corneal epithelial cells. Biochem Biophys Res Commun 2018; 503:1510-1515. [DOI: 10.1016/j.bbrc.2018.07.071] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2018] [Accepted: 07/13/2018] [Indexed: 10/28/2022]
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31
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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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32
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Ruch TR, Engel JN. Targeting the Mucosal Barrier: How Pathogens Modulate the Cellular Polarity Network. Cold Spring Harb Perspect Biol 2017; 9:cshperspect.a027953. [PMID: 28193722 DOI: 10.1101/cshperspect.a027953] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The mucosal barrier is composed of polarized epithelial cells with distinct apical and basolateral surfaces separated by tight junctions and serves as both a physical and immunological barrier to incoming pathogens. Specialized polarity proteins are critical for establishment and maintenance of polarity. Many human pathogens have evolved virulence mechanisms that target the polarity network to enhance binding, create replication niches, move through the barrier by transcytosis, or bypass the barrier by disrupting cell-cell junctions. This review summarizes recent advances and compares and contrasts how three important human pathogens that colonize mucosal surfaces, Pseudomonas aeruginosa, Helicobacter pylori, and Neisseria meningitidis, subvert the host cell polarization machinery during infection.
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Affiliation(s)
- Travis R Ruch
- Department of Medicine, University of California, San Francisco, San Francisco, California 94143
| | - Joanne N Engel
- Department of Medicine, University of California, San Francisco, San Francisco, California 94143.,Department of Microbiology and Immunology, University of California, San Francisco, San Francisco, California 94143
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33
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Song OR, Deboosere N, Delorme V, Queval CJ, Deloison G, Werkmeister E, Lafont F, Baulard A, Iantomasi R, Brodin P. Phenotypic assays for Mycobacterium tuberculosis infection. Cytometry A 2017; 91:983-994. [PMID: 28544095 DOI: 10.1002/cyto.a.23129] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2016] [Revised: 03/23/2017] [Accepted: 04/13/2017] [Indexed: 12/13/2022]
Abstract
Tuberculosis (TB) is still a major global threat, killing more than one million persons each year. With the constant increase of Mycobacterium tuberculosis strains resistant to first- and second-line drugs, there is an urgent need for the development of new drugs to control the propagation of TB. Although screenings of small molecules on axenic M. tuberculosis cultures were successful for the identification of novel putative anti-TB drugs, new drugs in the development pipeline remains scarce. Host-directed therapy may represent an alternative for drug development against TB. Indeed, M. tuberculosis has multiple specific interactions within host phagocytes, which may be targeted by small molecules. In order to enable drug discovery strategies against microbes residing within host macrophages, we developed multiple fluorescence-based HT/CS phenotypic assays monitoring the intracellular replication of M. tuberculosis as well as its intracellular trafficking. What we propose here is a population-based, multi-parametric analysis pipeline that can be used to monitor the intracellular fate of M. tuberculosis and the dynamics of cellular events such as phagosomal maturation (acidification and permeabilization), zinc poisoning system or lipid body accumulation. Such analysis allows the quantification of biological events considering the host-pathogen interplay and may thus be derived to other intracellular pathogens. © 2017 International Society for Advancement of Cytometry.
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Affiliation(s)
- Ok-Ryul Song
- University of Lille, CNRS, Inserm, CHU Lille, Institut Pasteur de Lille, U1019 - UMR 8204 - CIIL - Centre d'Infection et d'Immunité de Lille, F-59000, France
| | - Nathalie Deboosere
- University of Lille, CNRS, Inserm, CHU Lille, Institut Pasteur de Lille, U1019 - UMR 8204 - CIIL - Centre d'Infection et d'Immunité de Lille, F-59000, France
| | - Vincent Delorme
- University of Lille, CNRS, Inserm, CHU Lille, Institut Pasteur de Lille, U1019 - UMR 8204 - CIIL - Centre d'Infection et d'Immunité de Lille, F-59000, France.,Tuberculosis Research Laboratory, Institut Pasteur Korea, Bundang-gu, Seongnam-si, Gyeonggi-do, 13488, Korea
| | - Christophe J Queval
- University of Lille, CNRS, Inserm, CHU Lille, Institut Pasteur de Lille, U1019 - UMR 8204 - CIIL - Centre d'Infection et d'Immunité de Lille, F-59000, France
| | - Gaspard Deloison
- University of Lille, CNRS, Inserm, CHU Lille, Institut Pasteur de Lille, U1019 - UMR 8204 - CIIL - Centre d'Infection et d'Immunité de Lille, F-59000, France
| | - Elisabeth Werkmeister
- University of Lille, CNRS, Inserm, CHU Lille, Institut Pasteur de Lille, U1019 - UMR 8204 - CIIL - Centre d'Infection et d'Immunité de Lille, F-59000, France
| | - Frank Lafont
- University of Lille, CNRS, Inserm, CHU Lille, Institut Pasteur de Lille, U1019 - UMR 8204 - CIIL - Centre d'Infection et d'Immunité de Lille, F-59000, France
| | - Alain Baulard
- University of Lille, CNRS, Inserm, CHU Lille, Institut Pasteur de Lille, U1019 - UMR 8204 - CIIL - Centre d'Infection et d'Immunité de Lille, F-59000, France
| | - Raffaella Iantomasi
- University of Lille, CNRS, Inserm, CHU Lille, Institut Pasteur de Lille, U1019 - UMR 8204 - CIIL - Centre d'Infection et d'Immunité de Lille, F-59000, France
| | - Priscille Brodin
- University of Lille, CNRS, Inserm, CHU Lille, Institut Pasteur de Lille, U1019 - UMR 8204 - CIIL - Centre d'Infection et d'Immunité de Lille, F-59000, France
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34
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Thanabalasuriar A, Surewaard BG, Willson ME, Neupane AS, Stover CK, Warrener P, Wilson G, Keller AE, Sellman BR, DiGiandomenico A, Kubes P. Bispecific antibody targets multiple Pseudomonas aeruginosa evasion mechanisms in the lung vasculature. J Clin Invest 2017; 127:2249-2261. [PMID: 28463232 DOI: 10.1172/jci89652] [Citation(s) in RCA: 62] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2016] [Accepted: 03/02/2017] [Indexed: 12/19/2022] Open
Abstract
Pseudomonas aeruginosa is a major cause of severe infections that lead to bacteremia and high patient mortality. P. aeruginosa has evolved numerous evasion and subversion mechanisms that work in concert to overcome immune recognition and effector functions in hospitalized and immunosuppressed individuals. Here, we have used multilaser spinning-disk intravital microscopy to monitor the blood-borne stage in a murine bacteremic model of P. aeruginosa infection. P. aeruginosa adhered avidly to lung vasculature, where patrolling neutrophils and other immune cells were virtually blind to the pathogen's presence. This cloaking phenomenon was attributed to expression of Psl exopolysaccharide. Although an anti-Psl mAb activated complement and enhanced neutrophil recognition of P. aeruginosa, neutrophil-mediated clearance of the pathogen was suboptimal owing to a second subversion mechanism, namely the type 3 secretion (T3S) injectisome. Indeed, T3S prevented phagosome acidification and resisted killing inside these compartments. Antibody-mediated inhibition of the T3S protein PcrV did not enhance bacterial phagocytosis but did enhance killing of the few bacteria ingested by neutrophils. A bispecific mAb targeting both Psl and PcrV enhanced neutrophil uptake of P. aeruginosa and also greatly increased inhibition of T3S function, allowing for phagosome acidification and bacterial killing. These data highlight the need to block multiple evasion and subversion mechanisms in tandem to kill P. aeruginosa.
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Affiliation(s)
- Ajitha Thanabalasuriar
- Department of Physiology and Pharmacology, Snyder Institute for Chronic Diseases, University of Calgary, Calgary, Alberta, Canada
| | - Bas Gj Surewaard
- Department of Physiology and Pharmacology, Snyder Institute for Chronic Diseases, University of Calgary, Calgary, Alberta, Canada
| | - Michelle E Willson
- Department of Physiology and Pharmacology, Snyder Institute for Chronic Diseases, University of Calgary, Calgary, Alberta, Canada
| | - Arpan S Neupane
- Department of Physiology and Pharmacology, Snyder Institute for Chronic Diseases, University of Calgary, Calgary, Alberta, Canada
| | | | | | | | | | | | | | - Paul Kubes
- Department of Physiology and Pharmacology, Snyder Institute for Chronic Diseases, University of Calgary, Calgary, Alberta, Canada
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Capasso D, Pepe MV, Rossello J, Lepanto P, Arias P, Salzman V, Kierbel A. Elimination of Pseudomonas aeruginosa through Efferocytosis upon Binding to Apoptotic Cells. PLoS Pathog 2016; 12:e1006068. [PMID: 27977793 PMCID: PMC5158079 DOI: 10.1371/journal.ppat.1006068] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2016] [Accepted: 11/15/2016] [Indexed: 02/03/2023] Open
Abstract
For opportunistic pathogens such as Pseudomonas aeruginosa, the mucosal barrier represents a formidable challenge. Infections develop only in patients with altered epithelial barriers. Here, we showed that P. aeruginosa interacts with a polarized epithelium, adhering almost exclusively at sites of multi-cellular junctions. In these sites, numerous bacteria attach to an extruded apoptotic cell or apoptotic body. This dead cell tropism is independent of the type of cell death, as P. aeruginosa also binds to necrotic cells. We further showed that P. aeruginosa is internalized through efferocytosis, a process in which surrounding epithelial cells engulf and dispose of extruded apoptotic cells. Intracellularly, along with apoptotic cell debris, P. aeruginosa inhabits an efferocytic phagosome that acquires lysosomal features, and is finally killed. We propose that elimination of P. aeruginosa through efferocytosis is part of a host defense mechanism. Our findings could be relevant for the study of cystic fibrosis, which is characterized by an exacerbated number of apoptotic cells and ineffective efferocytosis. Pseudomonas aeruginosa is an opportunistic pathogen that infects vulnerable patients, such as those with cystic fibrosis or hospitalized in intensive care units. An advance towards understanding infections caused by P. aeruginosa would be to fully elucidate the mechanisms that operate in the bacteria-epithelial barrier interplay. Here, we showed that P. aeruginosa exhibits a remarkable tropism towards dead cells. As bacteria interact with a polarized epithelium, they attach and aggregate almost exclusively on apoptotic cells extruded from the epithelium, while the rest of the surface seems reluctant to bacterial adhesion. We further showed that P. aeruginosa is internalized by epithelial cells surrounding the infected apoptotic cell through efferocytosis, a process in which apoptotic cells are engulfed and disposed of by other cells. Bacteria are eliminated intracellularly. Our findings may help to understand why contexts such as cystic fibrosis, where apoptotic cells are unusually produced and efferocytosis fails, favor P. aeruginosa colonization.
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Affiliation(s)
- Darío Capasso
- Instituto de Investigaciones Biotecnológicas Dr. Rodolfo A. Ugalde (IIB-INTECH), Universidad Nacional de San Martín, Consejo Nacional de Investigaciones Científicas y Técnicas (UNSAM-CONICET), San Martín, Buenos Aires, Argentina
| | - María Victoria Pepe
- Instituto de Investigaciones Biotecnológicas Dr. Rodolfo A. Ugalde (IIB-INTECH), Universidad Nacional de San Martín, Consejo Nacional de Investigaciones Científicas y Técnicas (UNSAM-CONICET), San Martín, Buenos Aires, Argentina
| | | | | | - Paula Arias
- Instituto de Investigaciones Biotecnológicas Dr. Rodolfo A. Ugalde (IIB-INTECH), Universidad Nacional de San Martín, Consejo Nacional de Investigaciones Científicas y Técnicas (UNSAM-CONICET), San Martín, Buenos Aires, Argentina
| | - Valentina Salzman
- Instituto de Investigaciones Biotecnológicas Dr. Rodolfo A. Ugalde (IIB-INTECH), Universidad Nacional de San Martín, Consejo Nacional de Investigaciones Científicas y Técnicas (UNSAM-CONICET), San Martín, Buenos Aires, Argentina
| | - Arlinet Kierbel
- Instituto de Investigaciones Biotecnológicas Dr. Rodolfo A. Ugalde (IIB-INTECH), Universidad Nacional de San Martín, Consejo Nacional de Investigaciones Científicas y Técnicas (UNSAM-CONICET), San Martín, Buenos Aires, Argentina
- * E-mail:
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Anantharajah A, Mingeot-Leclercq MP, Van Bambeke F. Targeting the Type Three Secretion System in Pseudomonas aeruginosa. Trends Pharmacol Sci 2016; 37:734-749. [PMID: 27344210 DOI: 10.1016/j.tips.2016.05.011] [Citation(s) in RCA: 74] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2016] [Revised: 05/15/2016] [Accepted: 05/17/2016] [Indexed: 12/11/2022]
Abstract
The injectisome type three secretion system (T3SS) is a major virulence factor in Pseudomonas aeruginosa. This bacterium is responsible for severe infections in immunosuppressed or cystic fibrosis patients and has become resistant to many antibiotics. Inhibitors of T3SS may therefore constitute an innovative therapeutic target. After a brief description of the T3SS and its regulation, this review presents strategies to inhibit T3SS-mediated toxicity and describes the main families of existing inhibitors. Over the past few years, 12 classes of small-molecule inhibitors and two types of antibody have been discovered and evaluated in vitro for their capacity to inhibit T3SS expression or function, and to protect host cells from T3SS-mediated cytotoxicity. While only one small molecule has been tested in vivo, a bifunctional antibody targeting both the translocation apparatus of the T3SS and a surface polysaccharide is currently in Phase II clinical trials.
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Affiliation(s)
- Ahalieyah Anantharajah
- Pharmacologie Cellulaire et Moléculaire, Louvain Drug Research Institute, Université Catholique de Louvain, Brussels, Belgium
| | - Marie-Paule Mingeot-Leclercq
- Pharmacologie Cellulaire et Moléculaire, Louvain Drug Research Institute, Université Catholique de Louvain, Brussels, Belgium
| | - Françoise Van Bambeke
- Pharmacologie Cellulaire et Moléculaire, Louvain Drug Research Institute, Université Catholique de Louvain, Brussels, Belgium.
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Khajah MA, Luqmani YA. Involvement of Membrane Blebbing in Immunological Disorders and Cancer. Med Princ Pract 2016; 25 Suppl 2:18-27. [PMID: 26488882 PMCID: PMC5588526 DOI: 10.1159/000441848] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/31/2015] [Accepted: 10/20/2015] [Indexed: 12/17/2022] Open
Abstract
Cellular blebbing is a unique form of dynamic protrusion emanating from the plasma membrane which can be either apoptotic or nonapoptotic in nature. Blebs have been observed in a wide variety of cell types and in response to multiple mechanical and chemical stimuli. They have been linked to various physiological and pathological processes including tumor motility and invasion, as well as to various immunological disorders. They can form and retract extremely rapidly in seconds or minutes, or slowly over hours or days. This review focuses on recent evidence regarding the role of blebbing in cell locomotion with particular emphasis on its role in tumor metastasis, indicating the role of specific causative molecules. The phenomenon of blebbing has been observed in endocrine-resistant breast cancer cells in response to brief exposure to extracellular alkaline pH, which leads to enhanced invasive capacity. Genetic or pharmacological targeting of cellular blebs could serve as a potential therapeutic option to control tumor metastasis.
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Affiliation(s)
| | - Yunus A. Luqmani
- Department of Pharmaceutical Chemistry, Faculty of Pharmacy, Kuwait University, Safat, Kuwait
- *Yunus A. Luqmani, Department of Pharmaceutical Chemistry, Faculty of Pharmacy, Kuwait University, PO Box 24923, Safat 13110 (Kuwait), E-Mail
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Pseudomonas aeruginosa-induced bleb-niche formation in epithelial cells is independent of actinomyosin contraction and enhanced by loss of cystic fibrosis transmembrane-conductance regulator osmoregulatory function. mBio 2015; 6:e02533. [PMID: 25714715 PMCID: PMC4358002 DOI: 10.1128/mbio.02533-14] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
The opportunistic pathogen Pseudomonas aeruginosa can infect almost any site in the body but most often targets epithelial cell-lined tissues such as the airways, skin, and the cornea of the eye. A common predisposing factor is cystic fibrosis (CF), caused by defects in the cystic fibrosis transmembrane-conductance regulator (CFTR). Previously, we showed that when P. aeruginosa enters epithelial cells it replicates intracellularly and occupies plasma membrane blebs. This phenotype is dependent on the type 3 secretion system (T3SS) effector ExoS, shown by others to induce host cell apoptosis. Here, we examined mechanisms for P. aeruginosa-induced bleb formation, focusing on its relationship to apoptosis and the CFTR. The data showed that P. aeruginosa-induced blebbing in epithelial cells is independent of actin contraction and is inhibited by hyperosmotic media (400 to 600 mOsM), distinguishing bacterially induced blebs from apoptotic blebs. Cells with defective CFTR displayed enhanced bleb formation upon infection, as demonstrated using bronchial epithelial cells from a patient with cystic fibrosis and a CFTR inhibitor, CFTR(Inh)-172. The defect was found to be correctable either by incubation in hyperosmotic media or by complementation with CFTR (pGFP-CFTR), suggesting that the osmoregulatory function of CFTR counters P. aeruginosa-induced bleb-niche formation. Accordingly, and despite their reduced capacity for bacterial internalization, CFTR-deficient cells showed greater bacterial occupation of blebs and enhanced intracellular replication. Together, these data suggest that P. aeruginosa bleb niches are distinct from apoptotic blebs, are driven by osmotic forces countered by CFTR, and could provide a novel mechanism for bacterial persistence in the host. Pseudomonas aeruginosa is an opportunistic pathogen problematic in hospitalized patients and those with cystic fibrosis (CF). Previously, we showed that P. aeruginosa can enter epithelial cells and replicate within them and traffics to the membrane blebs that it induces. This “bleb-niche” formation requires ExoS, previously shown to cause apoptosis. Here, we show that the driving force for bleb-niche formation is osmotic pressure, differentiating P. aeruginosa-induced blebs from apoptotic blebs. Either CFTR inhibition or CFTR mutation (as seen in people with CF) causes P. aeruginosa to make more bleb niches and provides an osmotic driving force for blebbing. CFTR inhibition also enhances bacterial occupation of blebs and intracellular replication. Since CFTR is targeted for removal from the plasma membrane when P. aeruginosa invades a healthy cell, these findings could relate to pathogenesis in both CF and healthy patient populations.
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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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McGuigan L, Callaghan M. The evolving dynamics of the microbial community in the cystic fibrosis lung. Environ Microbiol 2014; 17:16-28. [DOI: 10.1111/1462-2920.12504] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2014] [Revised: 04/28/2014] [Accepted: 05/01/2014] [Indexed: 12/29/2022]
Affiliation(s)
- Luke McGuigan
- Department of Science; Centre of Microbial Host Interactions (CMHI); ITT-Dublin; Dublin Ireland
| | - Máire Callaghan
- Department of Science; Centre of Microbial Host Interactions (CMHI); ITT-Dublin; Dublin Ireland
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Junkins RD, McCormick C, Lin TJ. The emerging potential of autophagy-based therapies in the treatment of cystic fibrosis lung infections. Autophagy 2014; 10:538-47. [PMID: 24434788 PMCID: PMC4077897 DOI: 10.4161/auto.27750] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Cystic fibrosis (CF) is caused by mutations in the CF transmembrane conductance regulator (CFTR), a channel that normally transports anions across epithelial cell membranes. The most common manifestation of CF is buildup of mucus in the airways and bacterial colonization of the lower respiratory tract, accompanied by chronic inflammation. Antibiotics are used to control CF-associated opportunistic infections, but lengthy antibiotic treatment risks the emergence of multiple-drug resistant (MDR) strains. New antimicrobial strategies are needed to prevent and treat infections in these high-risk individuals. Autophagy contributes to the control of a variety of microbial infections. For this reason, the recent discovery of functional impairment of autophagy in CF provides a new basis for understanding susceptibility to severe infections. Here, we review the role of autophagy in host defense against CF-associated bacterial and fungal pathogens, and survey pharmacologic approaches to restore normal autophagy function in these individuals. Autophagy restoration therapy may improve pathogen clearance and mitigate lung inflammation in CF airways.
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Affiliation(s)
- Robert D Junkins
- Department of Microbiology and Immunology; Dalhousie University; Halifax, NS CA; Department of Pediatrics; IWK Health Centre; Halifax, NS CA; Beatrice Hunter Cancer Research Institute; Halifax, NS CA
| | - Craig McCormick
- Department of Microbiology and Immunology; Dalhousie University; Halifax, NS CA; Beatrice Hunter Cancer Research Institute; Halifax, NS CA
| | - Tong-Jun Lin
- Department of Microbiology and Immunology; Dalhousie University; Halifax, NS CA; Department of Pediatrics; IWK Health Centre; Halifax, NS CA; Beatrice Hunter Cancer Research Institute; Halifax, NS CA
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