Ferric chloride induces ferroptosis in Pseudomonas aeruginosa and heals wound infection in a mouse model

Pseudomonas aeruginosa is one of the most common pathogens that lead to fatal human infection. This Gram-negative pathogen has evolved complex drug resistance, which poses significant challenges to the current antibiotic-dependent healthcare system. New therapeutic approaches are urgently required to treat infections caused by P. aeruginosa. Inspired by ferroptosis, the antibacterial effects of iron compounds on P. aeruginosa via direct exposure were investigated. In addition, thermal-responsive hydrogels to carry FeCl3 were developed as a wound dressing to treat P. aeruginosa-induced wound infection in a mouse model. The results showed that 200 µM FeCl3 killed more than 99.9% of P. aeruginosa cells. FeCl3-mediated cell death in P. aeruginosa was associated with hallmarks of ferroptosis in mammalian cells, including reactive oxygen species (ROS) burst, lipid peroxidation, and DNA damage. Catalase or Fe2+ chelator alleviated FeCl3-mediated cell death, indicating that H2O2 and labile Fe2+ induced the Fenton reaction leading to cell death. Further proteomics analysis showed that proteins related to glutathione (GSH) synthesis and the glutathione peroxidase (GPX) family were significantly downregulated after FeCl3 treatment, which is equivalent to GPX4 inactivation in mammalian cells. The therapeutic effect of FeCl3 on P. aeruginosa was further evaluated in a mouse wound infection model using polyvinyl alcohol-boric acid (PB) hydrogels as a carrier of FeCl3. FeCl3-PB hydrogels completely cleared pus on wounds and promoted wound healing. These results indicated that FeCl3 induces microbial ferroptosis in P. aeruginosa and has high therapeutic potential for the treatment of P. aeruginosa wound infection.