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Updated: Jul 1, 2025
Quantifying the Cytotoxicity of Staphylococcus aureus Against Human Polymorphonuclear Leukocytes
Published on: January 3, 2020
Effect of Polyphenols on Inflammation Induced by Membrane Vesicles from Staphylococcus aureus
Yukino Oura1, Yuko Shimamura1, Toshiyuki Kan2
1School of Food and Nutritional Sciences, University of Shizuoka, 52-1 Yada, Suruga-ku, Shizuoka 422-8526, Japan.
Abstract:
Staphylococcus aureus, a bacterium found on human skin, produces toxins and various virulence factors that can lead to skin infections such as atopic dermatitis. These toxins and virulence factors are carried in membrane vesicles (MVs), composed of the bacterium's own cell membranes, and are expected to reach host target cells in a concentrated form, inducing inflammation. This study investigated the effects of two polyphenols, (-)-epigallocatechin gallate (EGCG) and nobiletin (NOL), on the expression of S. aureus virulence factors and the inflammation induced by MVs. The study found that EGCG alone decreased the production of Staphylococcal Enterotoxin A (SEA), while both EGCG and NOL reduced biofilm formation and the expression of virulence factor-related genes. When S. aureus was cultured in a broth supplemented with these polyphenols, the resulting MVs showed a reduction in SEA content and several cargo proteins. These MVs also exhibited decreased levels of inflammation-related gene expression in immortalized human keratinocytes. These results suggest that EGCG and NOL are expected to inhibit inflammation in the skin by altering the properties of MVs derived from S. aureus.
Insights
Polyphenols like EGCG and NOL reduce Staphylococcus aureus virulence factors and inflammation. These compounds alter bacterial membrane vesicles, decreasing their inflammatory potential in skin cells.
Area of Science:
- Microbiology
- Dermatology
- Pharmacology
Background:
- Staphylococcus aureus causes skin infections like atopic dermatitis through toxins and virulence factors.
- Bacterial membrane vesicles (MVs) deliver these factors to host cells, inducing inflammation.
Purpose of the Study:
- Investigate the effects of (-)-epigallocatechin gallate (EGCG) and nobiletin (NOL) on S. aureus virulence and MV-induced inflammation.
- Determine if EGCG and NOL can mitigate skin inflammation caused by S. aureus.
Main Methods:
- Cultured S. aureus with EGCG and NOL.
- Analyzed MVs for toxin and protein content.
- Assessed inflammation-related gene expression in human keratinocytes exposed to MVs.
Main Results:
- EGCG reduced Staphylococcal Enterotoxin A (SEA) production; both EGCG and NOL decreased biofilm formation and virulence gene expression.
- MVs from polyphenol-treated bacteria had lower SEA and cargo protein levels.
- These MVs induced reduced inflammation-related gene expression in keratinocytes.
Conclusions:
- EGCG and NOL alter S. aureus membrane vesicle properties.
- These polyphenols show potential for inhibiting skin inflammation by modulating bacterial virulence factor delivery.
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