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Counter inhibition between leukotoxins attenuates Staphylococcus aureus virulence.

Yoong P, Torres VJ - Nat Commun (2015)

Bottom Line: Despite extensive sequence conservation, each leukotoxin has unique properties, including disparate cellular receptors and species specificities.Using in vivo murine models of infection, we show that LukSF-PV negatively influences S. aureus virulence and colonization by inhibiting LukED.Thus, while S. aureus leukotoxins can certainly injure immune cells, the discovery of leukotoxin antagonism suggests that they may also play a role in reducing S. aureus virulence and maintaining infection without killing the host.

View Article: PubMed Central - PubMed

Affiliation: Department of Microbiology, New York University School of Medicine, New York, New York 10016, USA.

ABSTRACT
Staphylococcus aureus subverts host defences by producing a collection of virulence factors including bi-component pore-forming leukotoxins. Despite extensive sequence conservation, each leukotoxin has unique properties, including disparate cellular receptors and species specificities. How these toxins collectively influence S. aureus pathogenesis is unknown. Here we demonstrate that the leukotoxins LukSF-PV and LukED antagonize each other's cytolytic activities on leukocytes and erythrocytes by forming inactive hybrid complexes. Remarkably, LukSF-PV inhibition of LukED haemolytic activity on both human and murine erythrocytes prevents the release of nutrients required for in vitro bacterial growth. Using in vivo murine models of infection, we show that LukSF-PV negatively influences S. aureus virulence and colonization by inhibiting LukED. Thus, while S. aureus leukotoxins can certainly injure immune cells, the discovery of leukotoxin antagonism suggests that they may also play a role in reducing S. aureus virulence and maintaining infection without killing the host.

No MeSH data available.


Related in: MedlinePlus

LukSF-PV inhibition of LukED attenuates S. aureus in vivo.(a) ‘Survival' of mice infected with the isogenic Newman strains carrying the integrated empty plasmid (Newman::pJC1111; n=20) or the lukSF-PV containing plasmid (Newman::plukSF-PV; n=20). (b) ‘Survival' of mice infected with the isogenic USA400-MW2 strains (n=10). (a,b) Each mouse was infected intravenously with 5 × 107 colony-forming units (c.f.u.) S. aureus. ‘Survival' curves were compared using the log-rank (Mantel–Cox) test. (c) Pulmonary infections were established in mice by instilling 2 × 108 c.f.u. of each isogenic USA300-LAC strains intranasally. Lungs were harvested 4 days post infection and plated for S. aureus counts. The data are represented as percentage of infected mice that harboured bacterial c.f.u. in the lungs 4 days post infection (P=0.0451). Statistical significance was determined using Fisher's exact test.
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f4: LukSF-PV inhibition of LukED attenuates S. aureus in vivo.(a) ‘Survival' of mice infected with the isogenic Newman strains carrying the integrated empty plasmid (Newman::pJC1111; n=20) or the lukSF-PV containing plasmid (Newman::plukSF-PV; n=20). (b) ‘Survival' of mice infected with the isogenic USA400-MW2 strains (n=10). (a,b) Each mouse was infected intravenously with 5 × 107 colony-forming units (c.f.u.) S. aureus. ‘Survival' curves were compared using the log-rank (Mantel–Cox) test. (c) Pulmonary infections were established in mice by instilling 2 × 108 c.f.u. of each isogenic USA300-LAC strains intranasally. Lungs were harvested 4 days post infection and plated for S. aureus counts. The data are represented as percentage of infected mice that harboured bacterial c.f.u. in the lungs 4 days post infection (P=0.0451). Statistical significance was determined using Fisher's exact test.

Mentions: Based on the observation that LukSF-PV blocks both LukED leukotoxic (Fig. 2a) and haemolytic activities (Fig. 2c) impacting S. aureus growth (Fig. 3a,b), we next explored if LukSF-PV also blocked LukED in vivo in a lethal LukED-mediated bloodstream infection model91024. Of note, experiments evaluating the contribution of LukED to S. aureus pathogenesis have only been performed on strains that naturally lack lukSF-PV91024. One such strain is Newman, a highly virulent MSSA strain commonly used in murine models of infection91024363738394041424344. Thus, we engineered a Newman strain to express lukSF-PV from its endogenous promoter from a single copy in the chromosome at the SaPI1 attachment site45. Evaluation of the toxin profile by immunoblotting revealed that heterologous production of LukSF-PV did not affect the production of the other toxins in strain Newman (Supplementary Fig. 3A,C). Mice were then challenged with isogenic strains containing either an integrated empty vector or the vector containing the lukSF-PV locus and the development of acute disease monitored. While 100% of the mice infected with WT Newman succumbed to infection in the 2-week study, only 60% of the mice infected with the LukSF-PV producing strain succumbed to infection (Fig. 4a).


Counter inhibition between leukotoxins attenuates Staphylococcus aureus virulence.

Yoong P, Torres VJ - Nat Commun (2015)

LukSF-PV inhibition of LukED attenuates S. aureus in vivo.(a) ‘Survival' of mice infected with the isogenic Newman strains carrying the integrated empty plasmid (Newman::pJC1111; n=20) or the lukSF-PV containing plasmid (Newman::plukSF-PV; n=20). (b) ‘Survival' of mice infected with the isogenic USA400-MW2 strains (n=10). (a,b) Each mouse was infected intravenously with 5 × 107 colony-forming units (c.f.u.) S. aureus. ‘Survival' curves were compared using the log-rank (Mantel–Cox) test. (c) Pulmonary infections were established in mice by instilling 2 × 108 c.f.u. of each isogenic USA300-LAC strains intranasally. Lungs were harvested 4 days post infection and plated for S. aureus counts. The data are represented as percentage of infected mice that harboured bacterial c.f.u. in the lungs 4 days post infection (P=0.0451). Statistical significance was determined using Fisher's exact test.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4562310&req=5

f4: LukSF-PV inhibition of LukED attenuates S. aureus in vivo.(a) ‘Survival' of mice infected with the isogenic Newman strains carrying the integrated empty plasmid (Newman::pJC1111; n=20) or the lukSF-PV containing plasmid (Newman::plukSF-PV; n=20). (b) ‘Survival' of mice infected with the isogenic USA400-MW2 strains (n=10). (a,b) Each mouse was infected intravenously with 5 × 107 colony-forming units (c.f.u.) S. aureus. ‘Survival' curves were compared using the log-rank (Mantel–Cox) test. (c) Pulmonary infections were established in mice by instilling 2 × 108 c.f.u. of each isogenic USA300-LAC strains intranasally. Lungs were harvested 4 days post infection and plated for S. aureus counts. The data are represented as percentage of infected mice that harboured bacterial c.f.u. in the lungs 4 days post infection (P=0.0451). Statistical significance was determined using Fisher's exact test.
Mentions: Based on the observation that LukSF-PV blocks both LukED leukotoxic (Fig. 2a) and haemolytic activities (Fig. 2c) impacting S. aureus growth (Fig. 3a,b), we next explored if LukSF-PV also blocked LukED in vivo in a lethal LukED-mediated bloodstream infection model91024. Of note, experiments evaluating the contribution of LukED to S. aureus pathogenesis have only been performed on strains that naturally lack lukSF-PV91024. One such strain is Newman, a highly virulent MSSA strain commonly used in murine models of infection91024363738394041424344. Thus, we engineered a Newman strain to express lukSF-PV from its endogenous promoter from a single copy in the chromosome at the SaPI1 attachment site45. Evaluation of the toxin profile by immunoblotting revealed that heterologous production of LukSF-PV did not affect the production of the other toxins in strain Newman (Supplementary Fig. 3A,C). Mice were then challenged with isogenic strains containing either an integrated empty vector or the vector containing the lukSF-PV locus and the development of acute disease monitored. While 100% of the mice infected with WT Newman succumbed to infection in the 2-week study, only 60% of the mice infected with the LukSF-PV producing strain succumbed to infection (Fig. 4a).

Bottom Line: Despite extensive sequence conservation, each leukotoxin has unique properties, including disparate cellular receptors and species specificities.Using in vivo murine models of infection, we show that LukSF-PV negatively influences S. aureus virulence and colonization by inhibiting LukED.Thus, while S. aureus leukotoxins can certainly injure immune cells, the discovery of leukotoxin antagonism suggests that they may also play a role in reducing S. aureus virulence and maintaining infection without killing the host.

View Article: PubMed Central - PubMed

Affiliation: Department of Microbiology, New York University School of Medicine, New York, New York 10016, USA.

ABSTRACT
Staphylococcus aureus subverts host defences by producing a collection of virulence factors including bi-component pore-forming leukotoxins. Despite extensive sequence conservation, each leukotoxin has unique properties, including disparate cellular receptors and species specificities. How these toxins collectively influence S. aureus pathogenesis is unknown. Here we demonstrate that the leukotoxins LukSF-PV and LukED antagonize each other's cytolytic activities on leukocytes and erythrocytes by forming inactive hybrid complexes. Remarkably, LukSF-PV inhibition of LukED haemolytic activity on both human and murine erythrocytes prevents the release of nutrients required for in vitro bacterial growth. Using in vivo murine models of infection, we show that LukSF-PV negatively influences S. aureus virulence and colonization by inhibiting LukED. Thus, while S. aureus leukotoxins can certainly injure immune cells, the discovery of leukotoxin antagonism suggests that they may also play a role in reducing S. aureus virulence and maintaining infection without killing the host.

No MeSH data available.


Related in: MedlinePlus