Inhibition of α-hemolysin activity of Staphylococcus aureus by theaflavin 3,3'-digallate

Area of Science:

• Microbiology
• Pharmacology
• Dermatology

Background:

• Antibiotic resistance limits treatment options for bacterial infections.
• Methicillin-resistant Staphylococcus aureus (MRSA) poses a significant public health threat.
• Novel therapeutic strategies are needed to combat resistant bacterial strains.

Purpose of the Study:

• To investigate the anti-hemolytic mechanisms of theaflavin 3,3′-digallate (TF3).
• To evaluate TF3's efficacy against Staphylococcus aureus and its alpha-hemolysin (Hla).
• To assess TF3's protective effects on human keratinocytes and its impact on inflammatory responses.

Main Methods:

• Bacteriostatic and bactericidal assays were performed on Staphylococcus aureus.
• Surface Plasmon Resonance (SPR) assay was used to determine TF3-Hla binding kinetics.
• In vitro and in vivo studies assessed TF3's effects on Hla-induced cell death, cytokine production (IL1β, IL6, TNFα), NFκB activity, and epithelial barrier integrity (E-cadherin, ZO-1).

Main Results:

• TF3 exhibited weak bacteriostatic and bactericidal effects on Staphylococcus aureus.
• TF3 strongly inhibited Hla hemolytic activity, production, and secretion, with a binding affinity (KD) of 4.57×10-5 M.
• TF3 protected human keratinocytes from Hla-induced cell death without toxicity, reduced Hla-induced inflammation by inhibiting NFκB signaling, and attenuated S. aureus-induced barrier disruption.

Conclusions:

• TF3 effectively neutralizes the hemolytic activity of Staphylococcus aureus alpha-hemolysin.
• TF3 demonstrates therapeutic potential by protecting epithelial barriers and reducing inflammation associated with S. aureus infections.
• TF3 represents a promising candidate for developing new treatments against antibiotic-resistant bacterial infections.