ORCID Profile
0000-0002-5365-875X
Current Organisation
University of Queensland
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Publisher: American Chemical Society (ACS)
Date: 05-2018
Publisher: American Society of Tropical Medicine and Hygiene
Date: 04-11-2020
Publisher: Springer Science and Business Media LLC
Date: 31-12-2022
DOI: 10.1007/S00018-021-04041-Z
Abstract: Bacteria that occupy an intracellular niche can evade extracellular host immune responses and antimicrobial molecules. In addition to classic intracellular pathogens, other bacteria including uropathogenic Escherichia coli (UPEC) can adopt both extracellular and intracellular lifestyles. UPEC intracellular survival and replication complicates treatment, as many therapeutic molecules do not effectively reach all components of the infection cycle. In this study, we explored cell-penetrating antimicrobial peptides from distinct structural classes as alternative molecules for targeting bacteria. We identified two β-hairpin peptides from the horseshoe crab, tachyplesin I and polyphemusin I, with broad antimicrobial activity toward a panel of pathogenic and non-pathogenic bacteria in planktonic form. Peptide analogs [I11A]tachyplesin I and [I11S]tachyplesin I maintained activity toward bacteria, but were less toxic to mammalian cells than native tachyplesin I. This important increase in therapeutic window allowed treatment with higher concentrations of [I11A]tachyplesin I and [I11S]tachyplesin I, to significantly reduce intramacrophage survival of UPEC in an in vitro infection model. Mechanistic studies using bacterial cells, model membranes and cell membrane extracts, suggest that tachyplesin I and polyphemusin I peptides kill UPEC by selectively binding and disrupting bacterial cell membranes. Moreover, treatment of UPEC with sublethal peptide concentrations increased zinc toxicity and enhanced innate macrophage antimicrobial pathways. In summary, our combined data show that cell-penetrating peptides are attractive alternatives to traditional small molecule antibiotics for treating UPEC infection, and that optimization of native peptide sequences can deliver effective antimicrobials for targeting bacteria in extracellular and intracellular environments.
Publisher: Elsevier BV
Date: 08-2020
Publisher: Cold Spring Harbor Laboratory
Date: 27-01-2020
DOI: 10.1101/2020.01.21.914846
Abstract: Melioidosis is a neglected tropical disease caused by the Gram-negative soil bacterium Burkholderia pseudomallei. Current treatment regimens are prolonged and costly, and acquired antimicrobial resistance has been reported for all currently used antibiotics. Efforts to develop new treatments for melioidosis are h ered by the risks associated with handling pathogenic B. pseudomallei , which restricts research to facilities with Biosafety Level (BSL) 3 containment. Closely related Burkholderia species that are less pathogenic can be investigated under less stringent BSL 2 containment. We hypothesized that near-neighbour Burkholderia species could be used as model organisms for developing therapies that would also be effective against B. pseudomallei . We used microbroth dilution assays to compare the susceptibility of three Australian B. pseudomallei isolates and five near-neighbour Burkholderia species – B. humptydooensis, B. thailandensis, B. oklahomensis, B territorii and B. stagnalis – to antibiotics currently used to treat melioidosis, and general-use antibacterial agents. We also established the susceptibility profiles of B. humptydooensis and B. territorii to 400 compounds from the Medicines for Malaria Venture Pathogen Box. From these comparisons, we observed a high degree of similarity in the susceptibility profiles of B. pseudomallei and near-neighbour species B. humptydooensis, B. thailandensis, B. oklahomensis and B. territorii. Less pathogenic Australian Burkholderia species B. humptydooensis, B. thailandensis, B. oklahomensis and B. territorii are excellent model organisms for developing potential new therapies for melioidosis.
Publisher: Wiley
Date: 10-0009
DOI: 10.1002/PEP2.24246
Abstract: We need new treatment options to control bacterial infections. Bacteria use several strategies to resist drug treatment, including modification of the drug target, and adaptation to a different lifestyle, such as intracellular niches within host cells. Drugs that act on erse targets are less likely to induce resistance in bacteria, than current antibiotics acting on a single molecular target. Antimicrobial peptides have been explored as a new class of antibiotics because they selectively kill bacteria via a mechanism that involves recognition of the negatively charged microbial surface. Furthermore, antimicrobial peptides with cell‐penetrating properties can cross host cell membranes and target bacteria in the cytosol or sequestered in vesicles. Therefore, bacteria in intracellular niches are less capable of evading treatment and the likelihood of establishing drug resistance is further reduced. This review highlights the potential of antimicrobial peptides as alternative therapeutics to target bacterial pathogens in both extracellular and intracellular environments, and to avoid acquired drug‐resistance.
Publisher: Cold Spring Harbor Laboratory
Date: 28-06-2021
DOI: 10.1101/2021.06.27.450110
Abstract: Bacteria that occupy an intracellular niche can evade extracellular host immune responses and antimicrobial molecules. In addition to classic intracellular pathogens, other bacteria including uropathogenic Escherichia coli (UPEC) can adopt both extracellular and intracellular lifestyles. UPEC intracellular survival and replication complicates treatment, as many therapeutic molecules do not effectively reach all components of the infection cycle. In this study, we explored cell penetrating antimicrobial peptides from distinct structural classes as alternative molecules for targeting bacteria. We identified two β-hairpin peptides from the horseshoe crab, tachyplesin I and polyphemusin I, with broad antimicrobial activity toward a panel of pathogenic and non-pathogenic bacteria in planktonic form. Peptide analogues [I11A]tachyplesin I and [I11S]tachyplesin I maintained activity toward bacteria, but were less toxic to mammalian cells than native tachyplesin I. This important increase in therapeutic window allowed treatment with higher concentrations of [I11A]tachyplesin I and [I11S]tachyplesin I, to significantly reduce intramacrophage survival of UPEC in an in vitro infection model. Mechanistic studies using bacterial cells, model membranes and cell membrane extracts, suggest that tachyplesin I and polyphemusin I peptides kill UPEC by selectively binding and disrupting bacterial cell membranes. Moreover, treatment of UPEC with sublethal peptide concentrations increased zinc toxicity and enhanced innate macrophage antimicrobial pathways. In summary, our combined data show that cell penetrating peptides are attractive alternatives to traditional small molecule antibiotics for treating UPEC infection, and that optimization of native peptide sequences can deliver effective antimicrobials for targeting bacteria in extracellular and intracellular environments.
No related grants have been discovered for Anna Amiss.