Membrane-Interactive Compounds fromPistacia lentiscusL. ThwartPseudomonas aeruginosaVirulence

Abstract

30Pseudomonas aeruginosa is capable to deploy a collection of virulence factors that are not 31 only essential for host infection and persistence, but also to escape from the host immune 32 system and to become more resistant to drug therapies. Thus, developing anti-virulence agents 33 that may directly counteract with specific virulence factors or disturb higher regulatory 34 pathways controlling the production of virulence armories are urgently needed. In this regard, 35 this study reports that Pistacia lentiscus L. fruit cyclohexane extract (PLFE1) thwarts P. 36 aeruginosa virulence by targeting mainly the pyocyanin pigment production by interfering with 37 4-hydroxy-2-alkylquinolines molecules production. Importantly, the anti-virulence activity of 38 PLFE1 appears to be associated with membrane homeostasis alteration through the 39 modulation of SigX, an extracytoplasmic function sigma factor involved in cell wall stress 40 response. A thorough chemical analysis of PLFE1 allowed us to identify the ginkgolic acid 41 (C17:1) and hydroginkgolic acid (C15:0) as the main bioactive membrane-interactive 42 compounds responsible for the observed increased membrane stiffness and anti-virulence 43 activity against P. aeruginosa. This study delivers a promising perspective for the potential 44 future use of PLFE1 or ginkgolic acid molecules as an adjuvant therapy to fight against P. 45 aeruginosa infections. 46 47 48 Bacterial infections still constitute a serious public health threat even though their prevention 49 and treatment have been improved over the last decades. The effects of common antibiotics 50 are no longer effective against microbial threats including Enterococcus faecium, 51Staphylococcus aureus, Acinetobacter baumannii, Pseudomonas aeruginosa, and 52Enterobacter species, also known as the "ESKAPE" pathogens group. 1 In a recent report 53 published by the World Health Organization (WHO), P. aeruginosa was categorized as one of 54 the "critical priority pathogens" for which there is an urgent need for the discovery of alternative 55 and innovative new therapies. 2 56 57 P. aeruginosa is predominantly responsible for different life-threatening infections in humans, 58 including the respiratory system, burn and wound, urinary tract as well as medical implant 59 devices. 3 This notorious multidrug resistant opportunistic Gram-negative bacterium deploys a 60 wide variety of virulence factors and host-degrading enzymes as well as multiple secondary 61 metabolites. 4 Pyocyanin is an important virulence factor produced and secreted abundantly by 62 nearly 95% of P. aeruginosa isolates. 5 This phenazine-derived pigment, blue-green in color, 63 confers a greenish hue to the sputum of cystic fibrosis (CF) individuals suffering P. aeruginosa 64 chronic lung infection. 6 Moreover, pyocyanin is a highly diffusible redox-active secondary 65 metabolite which plays an important role in several physiological processes 6,7 making it a good 66 target. Therefore, pyocyanin production hindrance may have consequences regardin...