Corneal Virulence of<i>Pseudomonas aeruginosa</i>Elastase B and Alkaline Protease Produced by<i>Pseudomonas putida</i>

Thibodeaux, Brett A.; Caballero, Armando R.; Marquart, Mary E.; Tommassen, Jan; O’Callaghan, Richard J.

doi:10.1080/02713680701244181

Cited by 33 publications

(38 citation statements)

References 50 publications

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“…5). Protease expression by P. aeruginosa is an important virulence mechanism (8,13,24,45). Previous studies have examined the roles of elastase (LasB) and alkaline protease on corneal pathology using purified proteases and/or bacterial mutants deficient in one or multiple proteases to establish those contributing to P. aeruginosa's virulence in vivo (32,35,46).…”

Section: Discussionmentioning

confidence: 99%

Role of the Corneal Epithelial Basement Membrane in Ocular Defense against Pseudomonas aeruginosa

Alarcon

Kwan

et al. 2009

Infect Immun

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Pseudomonas aeruginosa can invade corneal epithelial cells and translocates multilayered corneal epithelia in vitro, but it does not penetrate the intact corneal epithelium in vivo. In healthy corneas, the epithelium is separated from the underlying stroma by a basement membrane containing extracellular matrix proteins and pores smaller than bacteria. Here we used in vivo and in vitro models to investigate the potential of the basement membrane to defend against P. aeruginosa. Transmission electron microscopy of infected mouse corneas in vivo showed penetration of the stroma by P. aeruginosa only where the basement membrane was visibly disrupted by scratch injury, suggesting that the intact basement membrane prevented penetration. This hypothesis was explored using an in vitro Matrigel Transwell model to mimic the corneal basement membrane. P. aeruginosa translocation of multilayered corneal epithelia grown on Matrigel was ϳ100-fold lower than that of cells grown without Matrigel (P < 0.005, t test). Matrigel did not increase transepithelial resistance. Matrigel-grown cells blocked translocation by a P. aeruginosa protease mutant. Without cells, Matrigel also reduced traversal of P. aeruginosa and the protease mutant. Fluorescence microscopy revealed a relative accumulation of bacteria at the superficial epithelium of cells grown on Matrigel at 3 h compared to cells grown on uncoated filters. By 5 h, bacteria accumulated beneath the cells, suggesting direct trapping by the Matrigel. These findings suggest that the basement membrane helps defend the cornea against infection via physical barrier effects and influences on the epithelium and that these roles could be compromised by P. aeruginosa proteases.Pseudomonas aeruginosa is an important opportunistic pathogen, commonly affecting burn victims, individuals with cystic fibrosis, patients in hospital intensive care units, and contact lens wearers (9-11). In the absence of contact lens wear, the cornea is remarkably resistant to infection, with P. aeruginosa effectively colonizing this tissue only if it is injured or otherwise compromised (41). To initiate clinically significant corneal pathology, P. aeruginosa (and almost all other microbes) must first access the corneal stroma, which is normally protected by a multilayered epithelium and associated basement membrane (1).The corneal epithelial basement membrane is secreted by the overlying epithelia and is comprised of sheets of extracellular matrix constituents, including type IV collagen, heparan sulfate proteoglycan, and various glycoproteins (laminin, entactin, nidogen, and fibronectin) and growth factors that mediate cellular function (1). Quantitative imaging of the corneal epithelial basal membrane in the rhesus macaque has shown a complex cross-linking of fibers and proteins intermingled with pores ranging from 30 to 400 nm in size (2). As shown for other basement membranes in the body (17,19,33), the corneal basement membrane anchors epithelial cells and provides positional information for healing, tissu...

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Section: Discussionmentioning

confidence: 99%

Role of the Corneal Epithelial Basement Membrane in Ocular Defense against Pseudomonas aeruginosa

Alarcon

Kwan

et al. 2009

Infect Immun

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“…A number of exotoxins including heat-stable haemolysin, phospholipases, exotoxins play a role in invasion of bacteria into the cornea with eventual stromal necrosis [133]. Once bacterial invasion into the cornea has ensued, the infection progresses rapidly towards melting of cornea facilitated by bacterial proteases, activation of metalloproteases and stimulation of immune response resulting in further damage via release of reactive oxygen intermediates and host proteases [114,192]. Proteases contribute to the pathogenesis of keratitis by degrading basement membrane, laminin, proteoglycans, collagen, and extracellular matrix [66,201].…”

Section: Bacterial Invasion and Cytotoxic Effectsmentioning

confidence: 99%

Pathogenesis of microbial keratitis

Lakhundi

Siddiqui

Khan

2017

Microbial Pathogenesis

181

121

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Microbial keratitis is a sight-threatening ocular infection caused by bacteria, fungi, and protist pathogens. Epithelial defects and injuries are key predisposing factors making the eye susceptible to corneal pathogens. Among bacterial pathogens, the most common agents responsible for keratitis include Staphylococcus aureus, Pseudomonas aeruginosa, Streptococcus pneumonia and Serratia species. Fungal agents of corneal infections include both filamentous as well as yeast, including Fusarium, Aspergillus, Phaeohyphomycetes, Curvularia, Paecilomyces, Scedosporium and Candida species, while in protists, Acanthamoeba spp. are responsible for causing ocular disease. Clinical features include redness, pain, tearing, blur vision and inflammation but symptoms vary depending on the causative agent. The underlying molecular mechanisms associated with microbial pathogenesis include virulence factors as well as the host factors that aid in the progression of keratitis, resulting in damage to the ocular tissue. The treatment therefore should focus not only on the elimination of the culprit but also on the neutralization of virulence factors to minimize the damage, in addition to repairing the damaged tissue. A complete understanding of the pathogenesis of microbial keratitis will lead to the rational development of therapeutic interventions. This is a timely review of our current understanding of the advances made in this field in a comprehensible manner. Coupled with the recently available genome sequence information and high throughput genomics technology, and the availability of innovative approaches, this will stimulate interest in this field.

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“…1). P. putida has rarely been reported to cause human infections, likely owing to its lack of an innate virulence potential (41,42). Of note, P. aeruginosa expresses a single polar flagellum, while P. putida displays multiple polar flagella (43,44).…”

Section: Flagella Are Major Elicitors Of Host Reactionsmentioning

confidence: 99%

The LasB Elastase of Pseudomonas aeruginosa Acts in Concert with Alkaline Protease AprA To Prevent Flagellin-Mediated Immune Recognition

et al. 2016

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eThe opportunistic pathogen Pseudomonas aeruginosa is capable of establishing severe and persistent infections in various eukaryotic hosts. It encodes a wide array of virulence factors and employs several strategies to evade immune detection. In the present study, we screened the Harvard Medical School transposon mutant library of P. aeruginosa PA14 for bacterial factors that modulate interleukin-8 responses in A549 human airway epithelial cells. We found that in addition to the previously identified alkaline protease AprA, the elastase LasB is capable of degrading exogenous flagellin under calcium-replete conditions and prevents flagellin-mediated immune recognition. Our results indicate that the production of two proteases with anti-flagellin activity provides a failsafe mechanism for P. aeruginosa to ensure the maintenance of protease-dependent immune-modulating functions.

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Corneal Virulence ofPseudomonas aeruginosaElastase B and Alkaline Protease Produced byPseudomonas putida

Cited by 33 publications

References 50 publications

Role of the Corneal Epithelial Basement Membrane in Ocular Defense against Pseudomonas aeruginosa

Role of the Corneal Epithelial Basement Membrane in Ocular Defense against Pseudomonas aeruginosa

Pathogenesis of microbial keratitis

The LasB Elastase of Pseudomonas aeruginosa Acts in Concert with Alkaline Protease AprA To Prevent Flagellin-Mediated Immune Recognition

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