Galleria mellonella native and analogue peptides Gm1 and ΔGm1. II) Anti-bacterial and anti-endotoxic effects

• Published in: Biochimica et biophysica acta 2014-10, Vol.1838 (10), p.2739-2744
• Main Authors: Correa, Wilmar, Manrique-Moreno, Marcela, Behrends, Jochen, Patiño, Edwin, Marella, Chakravarthy, Peláez-Jaramillo, Carlos, Garidel, Patrick, Gutsmann, Thomas, Brandenburg, Klaus, Heinbockel, Lena
• Format: Article
• Language: English
• Subjects: Animals; Anti-Bacterial Agents - chemistry; Anti-Bacterial Agents - pharmacology; Antibacterial/antimicrobial peptide; Antimicrobial Cationic Peptides - chemistry; Antimicrobial Cationic Peptides - pharmacology; Atomic force microscopy; Cells, Cultured; Endotoxemia - chemically induced; Endotoxemia - drug therapy; Endotoxemia - metabolism; Endotoxemia - pathology; Female; Galleria mellonella; Humans; Insect Proteins - chemistry; Insect Proteins - pharmacology; Leukocytes, Mononuclear - metabolism; Leukocytes, Mononuclear - pathology; Lipopolysaccharide; Lipopolysaccharides - toxicity; Male; Moths - chemistry; Peptide-lipid interaction; Tumor Necrosis Factor-alpha - metabolism
• ISSN: 0005-2736; 0006-3002; 1879-2642
• DOI: 10.1016/j.bbamem.2014.07.005

Antimicrobial peptides (AMPs) are important components of the innate immune system of animals, plants, fungi and bacteria and are recently under discussion as promising alternatives to conventional antibiotics. We have investigated two cecropin-like synthetic peptides, Gm1, which corresponds to the natural overall uncharged Galleria mellonella native peptide and ΔGm1, a modified overall positively charged Gm1 variant. We have analysed these peptides for their potential to inhibit the endotoxin-induced secretion of tumour necrosis factor-α (TNF-α) from human mononuclear cells. Furthermore, in a conventional microbiological assay, the ability of these peptides to inhibit the growth of the rough mutant bacteria Salmonella enterica Minnesota R60 and the polymyxin B-resistant Proteus mirabilis R45 was investigated and atomic force microscopy (AFM) measurements were performed to characterize the morphology of the bacteria treated by the two peptides. We have also studied their cytotoxic properties in a haemolysis assay to clarify potential toxic effects. Our data revealed for both peptides minor anti-inflammatory (anti-endotoxin) activity, but demonstrated antimicrobial activity with differences depending on the endotoxin composition of the respective bacteria. In accordance with the antimicrobial assay, AFM data revealed a stronger morphology change of the R45 bacteria than for the R60. Furthermore, Gm1 had a stronger effect on the bacteria than ΔGm1, leading to a different morphology regarding indentations and coalescing of bacterial structures. The findings verify the biophysical measurements with the peptides on model systems. Both peptides lack any haemolytic activity up to an amount of 100μg/ml, making them suitable as new anti-infective agents. [Display omitted] •The result suggests that Gm1 and ΔGm1 can block the action of free endotoxin.•The peptide Gm1 shows a high level of antibacterial activity.•Gm1 caused fusion of membranes which led to a blurring of the borders.•ΔGm1 cause irregular deep grooves on the surface and the cells lost their shape.•Gm1 and ΔGm1 do not have citotoxic effects in human blood cells.