LasR-deficient Pseudomonas aeruginosa variants increase airway epithelial mICAM-1 expression and enhance neutrophilic lung inflammation

Hennemann, Lisa C.; LaFayette, Shantelle L.; Malet, Julien Karim; Bortolotti, Perrine; Yang, Tianxiao; McKay, Geoffrey A.; Houle, Daniel; Radzioch, Danuta; Rousseau, Stéphane; Nguyen, Dao M.

doi:10.1371/journal.ppat.1009375

Cited by 19 publications

(13 citation statements)

References 95 publications

(175 reference statements)

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“…According to our results, it is likely that AprA and LasB contribute to the virulence of P. aeruginosa once the infection is already established, but not in the early steps when the innate immune system is faster than the synthesis of both proteases by the microorganism. Thus, both exoproteases might facilitate the dissemination of the microorganism, disrupting the endothelial barrier from the initial focus of the infection ( Golovkine et al., 2014 ), as in pneumonias, or participate in the modulation of the inflammatory response in the chronic respiratory infections ( LaFayette et al., 2015 ; Hennemann et al., 2021 ).…”

Section: Discussionmentioning

confidence: 99%

Molecular Analysis of the Contribution of Alkaline Protease A and Elastase B to the Virulence of Pseudomonas aeruginosa Bloodstream Infections

Mateu-Borrás

Zamorano

González-Alsina

et al. 2022

Front. Cell. Infect. Microbiol.

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Pseudomonas aeruginosa is a major cause of nosocomial bloodstream infections. This microorganism secretes two major proteases, alkaline protease A (AprA) and elastase B (LasB). Despite several in vitro studies having demonstrated that both purified proteases cleave a number of components of the immune system, their contribution to P. aeruginosa bloodstream infections in vivo remains poorly investigated. In this study, we used a set of isogenic mutants deficient in AprA, LasB or both to demonstrate that these exoproteases are sufficient to cleave the complement component C3, either soluble or deposited on the bacteria. Nonetheless, exoprotease-deficient mutants were as virulent as the wild-type strain in a murine model of systemic infection, in Caenorhabditis elegans and in Galleria mellonella. Consistently, the effect of the exoproteases on the opsonization of P. aeruginosa by C3 became evident four hours after the initial interaction of the complement with the microorganism and was not crucial to survival in blood. These results indicate that exoproteases AprA and LasB, although conferring the capacity to cleave C3, are not essential for the virulence of P. aeruginosa bloodstream infections.

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Section: Discussionmentioning

confidence: 99%

Molecular Analysis of the Contribution of Alkaline Protease A and Elastase B to the Virulence of Pseudomonas aeruginosa Bloodstream Infections

Mateu-Borrás

Zamorano

González-Alsina

et al. 2022

Front. Cell. Infect. Microbiol.

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“…It has been shown that LasR-deficient isolates from CF patients induce exaggerated host inflammatory responses and promote neutrophil recruitment due to the loss of the LasB cytokine-proteolytic activity [ 33 ]. More recently, Hennemann et al demonstrated that LasR-deficient strains enhanced neutrophil adhesion due to the loss of ICAM-1 degradation by LasR-regulated proteases [ 34 ]. Our findings complement these previous studies on the potential detrimental effects of the LasR mutations.…”

Section: Discussionmentioning

confidence: 99%

“…Our findings complement these previous studies on the potential detrimental effects of the LasR mutations. Thus, it is likely that the loss of the AprA/LasB-dependent proteolysis of C5a exhibited by the lasR -mutant isolates may contribute to the intense neutrophilia observed in the lung fluids of the CF patients [ 9 , 28 ] and in the previous studies with mice challenged with LasR-deficient mutants [ 33 , 34 ]. It is noteworthy that, in addition to the neutrophil chemotactic activity, C5a also induces the expression of the neutrophil integrin that mediates the attachment to ICAM-I, facilitating their migration to the lung.…”

Section: Discussionmentioning

confidence: 99%

Pseudomonas aeruginosa adaptation in cystic fibrosis patients increases C5a levels and promotes neutrophil recruitment

Mateu-Borrás¹,

González-Alsina²,

Doménech-Sánchez³

et al. 2022

Virulence

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Cystic fibrosis (CF) disease is characterized by an intense airway inflammatory response mediated by neutrophils and chronic respiratory infections caused by P. aeruginosa . High levels of the complement component C5a, the strongest neutrophil chemoattractant molecule, are commonly found in the CF lung and have been associated with a worsening of the disease. In this study, we investigated how the isolates from CF patients modulate the levels of C5a and identified the bacterial factors involved. We demonstrated that most isolates from airway chronic infections induce the production and accumulation of C5a, an effect attributable to the loss of C5a cleavage by the exoproteases alkaline protease (AprA) and elastase B (LasB). Furthermore, we found that lack of the bacterial protease-dependent C5a degradation is due to mutations in the master regulator LasR. Thus, complementation of a non-C5a-cleaving CF isolate with a functional wild-type LasR restored its ability to express both proteases, cleave C5a and reduce neutrophil recruitment in vitro. These findings suggest that the non-cleaving C5a phenotype acquired by the LasR variants frequently isolated in CF patients may account for the strong neutrophilia and general neutrophil dysfunction predisposing toward increased inflammation and reduced bacterial clearance described in CF patients.

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“…For our study, we selected BEAS-2B cells, an AEC line widely used to study host cell signaling and inflammatory responses to P.a. and its secreted or surface molecules [66][67][68][69]. Previous studies using live cell video microscopy by the Fleiszig group have observed that P.a.…”

Section: Discussionmentioning

confidence: 99%

A Model of Intracellular Persistence of Pseudomonas aeruginosa in Airway Epithelial Cells

Malet

Hennemann

Hua

et al. 2022

Cellular Microbiology

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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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LasR-deficient Pseudomonas aeruginosa variants increase airway epithelial mICAM-1 expression and enhance neutrophilic lung inflammation

Cited by 19 publications

References 95 publications

Molecular Analysis of the Contribution of Alkaline Protease A and Elastase B to the Virulence of Pseudomonas aeruginosa Bloodstream Infections

Molecular Analysis of the Contribution of Alkaline Protease A and Elastase B to the Virulence of Pseudomonas aeruginosa Bloodstream Infections

Pseudomonas aeruginosa adaptation in cystic fibrosis patients increases C5a levels and promotes neutrophil recruitment

A Model of Intracellular Persistence of Pseudomonas aeruginosa in Airway Epithelial Cells

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