A Brominated Furanone Inhibits Pseudomonas aeruginosa Quorum Sensing and Type III Secretion, Attenuating Its Virulence in a Murine Cutaneous Abscess Model

Quorum sensing (QS) and type III secretion systems (T3SSs) are among the most attractive anti-virulence targets for combating multidrug-resistant pathogenic bacteria. Some halogenated furanones reduce QS-associated virulence, but their role in T3SS inhibition remains unclear. This study aimed to assess the inhibition of these two systems on Pseudomonas aeruginosa virulence. The halogenated furanones (Z)-4-bromo-5-(bromomethylene)-2(5H) (C-30) and 5-(dibromomethylene)-2(5H) (named hereafter GBr) were synthesized, and their ability to inhibit the secretion of type III exoenzymes and QS-controlled virulence factors was analyzed in P. aeruginosa PA14 and two clinical isolates. Furthermore, their ability to prevent bacterial establishment was determined in a murine cutaneous abscess model. The GBr furanone reduced pyocyanin production, biofilm formation, and swarming motility in the same manner or more effectively than C-30. Moreover, both furanones inhibited the secretion of ExoS, ExoT, or ExoU effectors in all tested strains. The administration of GBr (25 and 50 mu M) to CD1 mice infected with the PA14 strain significantly decreased necrosis formation in the inoculation zone and the systemic spread of bacteria more efficiently than C-30 (50 mu M). Molecular docking analysis suggested that the gem position of bromine in GBr increases its affinity for the active site of the QS LasR regulator. Overall, our findings showed that the GBr furanone displayed efficient multi-target properties that may favor the development of more effective anti-virulence therapies.

Automated summary

This study assessed the inhibition of quorum sensing (QS) and type III secretion systems (T3SSs) on Pseudomonas aeruginosa virulence. The synthesized halogenated furanones, named GBr, effectively reduced pyocyanin production, biofilm formation, and swarming motility, and inhibited the secretion of ExoS, ExoT, or ExoU effectors in tested strains. In a mouse model, GBr significantly decreased necrosis formation and bacterial spread more efficiently than C-30. Molecular docking analysis suggested that GBr had increased affinity for the active site of the QS LasR regulator. These findings highlight the potential of GBr as a multi-target anti-virulence therapy.