Microbiome-derived antimicrobial peptides offer therapeutic solutions for the treatment of Pseudomonas aeruginosa infections

Abstract

Microbiomes are rife for biotechnological exploitation, particularly the rumen microbiome, due to their complexicity and diversity. In this study, antimicrobial peptides (AMPs) from the rumen microbiome (Lynronne 1, 2, 3 and P15s) were assessed for their therapeutic potential against seven clinical strains of Pseudomonas aeruginosa. All AMPs exhibited antimicrobial activity against all strains, with minimum inhibitory concentrations (MICs) ranging from 4–512 µg/mL. Time-kill kinetics of all AMPs at 3× MIC values against strains PAO1 and LES431 showed complete kill within 10 min to 4 h, although P15s was not bactericidal against PAO1. All AMPs significantly inhibited biofilm formation by strains PAO1 and LES431, and induction of resistance assays showed no decrease in activity against these strains. AMP cytotoxicity against human lung cells was also minimal. In terms of mechanism of action, the AMPs showed affinity towards PAO1 and LES431 bacterial membrane lipids, efficiently permeabilising the P. aeruginosa membrane. Transcriptome and metabolome analysis revealed increased catalytic activity at the cell membrane and promotion of β-oxidation of fatty acids. Finally, tests performed with the Galleria mellonella infection model showed that Lynronne 1 and 2 were efficacious in vivo, with a 100% survival rate following treatment at 32 mg/kg and 128 mg/kg, respectively. This study illustrates the therapeutic potential of microbiome-derived AMPs against P. aeruginosa infections.

Evaluation of the Efficiency of Random and Diblock Methacrylate-Based Amphiphilic Cationic Polymers against Major Bacterial Pathogens Associated with Cystic Fibrosis

“…This suggests another mechanism of action for this copolymer on this strain that would be investigated in the future. Finally, similar to numerous AMPs [56,59,60], the tested copolymers were able to prevent biofilm formation implying a major impact of our molecule at the early stage of the infection. Unfortunately, selected copolymers were inactive on established biofilms, a limitation also observed with several AMPs [56,59,60], only few AMPs being shown to both inhibit biofilm formation and disrupt established ones [59].…”

“…Overall, this study shows that the Random and Diblock copolymers display the same strengths than AMPs in the treatment of CF-associated bacteria [60], notably their capacity to rapidly kill bacteria through a membranolytic activity, without causing resistance. However, unlike AMPs, Random and Diblock copolymers are insensitive to proteases, not immunogenic, and easy to produce in a large industrial scale.…”

“…Time-kill assay was performed as previously described [60,62]. Log-phase bacteria were incubated in wells of a 96 wells microplate at a final concentration of 10 6 cell/mL with either medium alone (growth control), or 150 µM cetyltrimethylammonium bromide (CTAB), or copolymer at 4× MIC.…”

“…The plate was incubated at 37 • C in a humidity chamber. At defined time intervals (5,15,30,60, 120 and 240 min), samples were taken from each well and serial dilutions were prepared and plated on agar plates. The number of CFU/mL was then evaluated after 5 days (for M. abscessus) or overnight (for P. aeruginosa and S. aureus) incubation at 37 • C. Experiments were conducted at least in triplicate (n ≥ 3).…”

Supporting the strategic pillars of translational research in biofilms

“…An alternative approach to identify novel antimicrobials is to search from them in microbiomes as they are a great resource for bioactive molecules which has been very much unexploited. In the study by Mulkern et al 10 the authors used antimicrobial peptides form rumen microbiome that show high effectiveness against Pseudomonas aeruginosa biofilms with low cytotoxicity and hence therapeutic potential. Finally, when designing new antimicrobials, it is important to understand their impact on different components of the biofilm such as the extracellular matrix, especially if the drug interacts with it like polymyxin B.…”