Author response: Heterogeneous absorption of antimicrobial peptide LL37 in Escherichia coli cells enhances population survivability

Snoussi, Mehdi; Talledo, John Paul; Rosario, Nathan-Alexander Del; Mohammadi, Salimeh; Ha, Bae‐Yeun; Košmrlj, Andrej; Taheri-Araghi, Sattar

doi:10.7554/elife.38174.023

Cited by 4 publications

(4 citation statements)

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“…Some AMPs kill bacteria by interacting with DNA or RNA, and therefore interfere with their synthesis, replication, and translational processes ( 10 , 85 ). It is debatable whether AMPs can target specific portions of DNA/RNA, as positively charged AMPs might bind unspecifically to negatively charged nucleic acids via strong electrostatic attractions ( 86 ). In addition, binding to nucleic acids can be unrelated to the cell death mechanism, as it can occur as a result of AMPs entering bacteria after disrupting their membranes.…”

Section: Detection Of Amp and Nucleic Acid Interactions Using Electrophoretic Mobility Shift Assaysmentioning

confidence: 99%

Mode-of-Action of Antimicrobial Peptides: Membrane Disruption vs. Intracellular Mechanisms

Benfield

Henriques

2020

Front. Med. Technol.

198

139

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Antimicrobial peptides are an attractive alternative to traditional antibiotics, due to their physicochemical properties, activity toward a broad spectrum of bacteria, and mode-of-actions distinct from those used by current antibiotics. In general, antimicrobial peptides kill bacteria by either disrupting their membrane, or by entering inside bacterial cells to interact with intracellular components. Characterization of their mode-of-action is essential to improve their activity, avoid resistance in bacterial pathogens, and accelerate their use as therapeutics. Here we review experimental biophysical tools that can be employed with model membranes and bacterial cells to characterize the mode-of-action of antimicrobial peptides.

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Section: Detection Of Amp and Nucleic Acid Interactions Using Electrophoretic Mobility Shift Assaysmentioning

confidence: 99%

Mode-of-Action of Antimicrobial Peptides: Membrane Disruption vs. Intracellular Mechanisms

Benfield

Henriques

2020

Front. Med. Technol.

198

139

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“…Therefore, binding to cellular components other than the bacterial membranes is likely. In studies by Jepson [2016], Snoussi [2018] and Wu [2019] it was shown that lysed cells are capable of sequestering a large number of peptide molecules. We have recently measured the association of an AMP to lysed cells, which proved to bind the peptide 10 times stronger than live bacteria [Savini 2020].…”

Section: Wherementioning

confidence: 99%

“…Finally, microscopy experiments [Zhu 2019] provided a mechanistic explanation for these observations: once the membranes are permeabilized, bacteria can enter the cell and molecules (e.g., DNA) in the intracellular compartment become accessible for binding. These effects could contribute to the IE by reducing the free peptide concentration available for bacterial killing [Jepson 2016, Snoussi 2018and Wu 2019, and thus lead to an overestimation of the value.…”

Section: Wherementioning

confidence: 99%

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Inoculum effect of antimicrobial peptides

Loffredo

Savini

Bobone

et al. 2020

Preprint

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The activity of many antibiotics depends on the initial density of cells used in bacteria growth inhibition assays. This phenomenon, termed the inoculum effect, can have important consequences for the therapeutic efficacy of the drugs, since bacterial loads vary by several orders of magnitude in clinically relevant infections. Antimicrobial peptides are a promising class of molecules to fight drug-resistant bacteria, since they act mainly by perturbing the cell membranes rather than by inhibiting intracellular targets. Here we report the first systematic characterization of the inoculum effect for this class of antibacterial compounds. Thirteen peptides (including all-D enantiomers) and peptidomimetics were analyzed by measuring minimum inhibitory concentration values, covering more than 7 orders of magnitude in inoculated cell density. In all cases, we observed a significant inoculum effect for cell densities above 5 x 104 cells/mL, while the active concentrations remained constant (within the micromolar range) for lower densities. In the case of membrane-active peptides, these data can be rationalized by considering a simple model, taking into account peptide-cell association and hypothesizing that a threshold number of cell-bound peptide molecules is required in order to cause a killing effect. The observed effects question the clinical utility of activity and selectivity determinations performed at a fixed, standardized cell density. A routine evaluation of the inoculum dependence of the activity of antimicrobial peptides and peptidomimetics should be considered.

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Antimicrobial Susceptibility Testing of Antimicrobial Peptides to Better Predict Efficacy

Mercer

Torres

Duay

et al. 2020

Front. Cell. Infect. Microbiol.

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During the development of antimicrobial peptides (AMP) as potential therapeutics, antimicrobial susceptibility testing (AST) stands as an essential part of the process in identification and optimisation of candidate AMP. Standard methods for AST, developed almost 60 years ago for testing conventional antibiotics, are not necessarily fit for purpose when it comes to determining the susceptibility of microorganisms to AMP. Without careful consideration of the parameters comprising AST there is a risk of failing to identify novel antimicrobials at a time when antimicrobial resistance (AMR) is leading the planet toward a post-antibiotic era. More physiologically/clinically relevant AST will allow better determination of the preclinical activity of drug candidates and allow the identification of lead compounds. An important consideration is the efficacy of AMP in biological matrices replicating sites of infection, e.g., blood/plasma/serum, lung bronchiolar lavage fluid/sputum, urine, biofilms, etc., as this will likely be more predictive of clinical efficacy. Additionally, specific AST for different target microorganisms may help to better predict efficacy of AMP in specific infections. In this manuscript, we describe what we believe are the key considerations for AST of AMP and hope that this information can better guide the preclinical development of AMP toward becoming a new generation of urgently needed antimicrobials.

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Author response: Heterogeneous absorption of antimicrobial peptide LL37 in Escherichia coli cells enhances population survivability

Cited by 4 publications

References 0 publications

Mode-of-Action of Antimicrobial Peptides: Membrane Disruption vs. Intracellular Mechanisms

Mode-of-Action of Antimicrobial Peptides: Membrane Disruption vs. Intracellular Mechanisms

Inoculum effect of antimicrobial peptides

Antimicrobial Susceptibility Testing of Antimicrobial Peptides to Better Predict Efficacy

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