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Galectin-3 Is a Target for Proteases Involved in the Virulence of Staphylococcus aureus
Jonas Elmwall1, Jakub Kwiecinski1,2, Manli Na1
1Department of Rheumatology and Inflammation Research, Sahlgrenska Academy at the University of Gothenburg, Gothenburg, Sweden.
Infection and Immunity
|April 26, 2017
Summary
Staphylococcus aureus proteases, particularly SspB, degrade human galectin-3. This inactivation of galectin-3 impairs neutrophil defense and exacerbates skin infection severity.
Area of Science:
- Microbiology
- Immunology
- Biochemistry
Background:
- Staphylococcus aureus is a significant pathogen causing skin and soft tissue infections.
- Staphylococcal proteases are increasingly recognized as key virulence factors.
- Human galectin-3 plays a role in immune regulation and antimicrobial defense.
Purpose of the Study:
- To investigate if staphylococcal proteases target human galectin-3.
- To determine if galectin-3 proteolysis is an immune evasion mechanism.
- To elucidate the role of galectin-3 and staphylococcal proteases in S. aureus virulence.
Main Methods:
- Degradation assays using S. aureus supernatants and purified galectin-3.
- Assessment of neutrophil NADPH oxidase activation.
- Murine skin infection model using galectin-3 deficient and wild-type mice.
Main Results:
- Staphylococcus aureus and Staphylococcus epidermidis supernatants degraded galectin-3, while Staphylococcus saprophyticus did not.
- Bacterial proteolysis of galectin-3 abrogated its ability to activate neutrophil NADPH oxidase, with SspB identified as the primary protease.
- In a murine model, SspB-expressing S. aureus caused more severe skin lesions and higher bacterial loads in galectin-3 sufficient mice compared to protease-deficient strains.
Conclusions:
- The staphylococcal protease SspB inactivates human galectin-3.
- This inactivation hinders neutrophil oxygen radical production, a key antimicrobial mechanism.
- Galectin-3 proteolysis by SspB contributes to increased tissue damage and bacterial virulence in S. aureus skin infections.
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