Investigating the In Vivo Antimicrobial Activity of a Self-Assembling Peptide Hydrogel Using a Galleria mellonella Infection Model

Abstract

Technological advances in protein biochemistry now enable researchers to modify the structure of peptides to enable them to possess self-assembling properties, forming hydrogels at low concentrations. Peptides can be altered further to provide multifunctional characteristics, for example, to demonstrate antimicrobial properties. The aim of this article is to investigate the in vivo toxicity and antimicrobial properties of a low molecular weight (naphthalene-2-ly)acetyl-diphenylalanine-dilysine-OH (NapFFKK-OH) peptide hydrogel using an innovative waxworm (Galleria mellonella) model, as an alternative to mammalian/vertebrate testing. NapFFKK-OH hydrogels did not demonstrate any observable in vivo toxicity or death in G. mellonella larvae over 5 days at concentrations studied (≤2% w/v). A dose-dependent log 10 reduction in viable (CFU/mL) Gram-positive (Staphylococcus aureus, Staphylococcus epidermidis) and Gram-negative (Escherichia coli, Pseudomonas aeruginosa) bacteria implicated in nosocomial infections was observed over 72 h. NapFFKK-OH was especially effective against in vivo infection models of S. aureus with a significant 4.4 log 10 CFU/mL reduction in viable bacteria at 2% w/v after 72 h. Our results show G. mellonella to be a useful model for preliminary determination of in vivo toxicity and antimicrobial efficacy profiles of novel nanomaterials, including peptide-based hydrogels. This contributes to the 3R principles of animal testing, reduction, refinement, and replacement. The results also show NapFFKK-OH to be a promising alternative to standardly employed antimicrobials with the potential to be utilized as a novel therapeutic in the treatment and prevention of hospital infections.

The Antioxidant Peptide Salamandrin-I: First Bioactive Peptide Identified from Skin Secretion of Salamandra Genus (Salamandra salamandra)

“…These results do not differ statistically (log-rank Mantel-Cox) from controls treated with PBS or 6% (v/v) DMSO. Peptides that have no toxicity in this model have been demonstrated by several studies [66][67][68]. Another way to study the toxic effects in the G. mellonella model is through histological analysis [69].…”

Antimicrobial Hydrogels: Promising Soft Biomaterials

“…[37][38][39] During the past few years, these photoactive materials have also been used in the preparation of the antimicrobial hydro- Figure 5. Low molecular weight hydrogel-forming peptide NapFFKK-OH reported by McCloskey et al [26] Figure 6. Small molecule-based hydrogel reported by Cheng et al [31] gel.…”

“…It was found that NapFFKK-OH exhibited antimicrobial activity and can be used for the prevention of hospital infections as well as in therapeutic treatment. [26]…”

Ornithine Lipids in Burkholderia spp. Pathogenicity

“…Hemolymph clotting, equivalent to mammalian blood clotting, is followed by melanization. The cellular response results in the encapsulation of the infecting pathogen and phagocytosis (McCloskey et al, 2019). When control larvae were infiltrated with saline solution, with E. coli or simply picketed, they were asymptomatic and neither death FIGURE 6 | Melanization in Galleria mellonella larvae infected with strains of B. cenocepacia occurs in the presence of the pathogen and does not depend on the presence of OLs.…”