melitten and Escherichia-coli-Infections

Bacteria-induced wound infections and multifunctional hydrogels have received widespread attention in wound repair. In this study, self-assembling peptides (SAPs) were grafted on O-carboxymethyl chitosan (O-CMCS), and compact spatial structure and good drug sustained-release effect on mel-d1, a new AMP designed based on melittin with the same antimicrobial activity but lower cytotoxicity and ciprofloxacin (CIP) were obtained. In vivo test showed that the O-CMCS/SAP hydrogel loaded with CIP and mel-d1 accelerated the wound closure speed caused by infection of Escherichia coli and skin tissue regeneration. Both of the enhanced interaction between O-CMCS/SAP and CIP/Mel-d1 because of the hydrophobic interaction and π-π stacking, and the potential tissue healing ability of SAP played important roles. This study provided a rational design method of O-CMCS by grafting SAPs to give a wider range of biological functions.

Topics: Animals; Anti-Bacterial Agents; Bandages; Cell Membrane; Chitosan; Ciprofloxacin; Delayed-Action Preparations; Drug Design; Escherichia coli; Escherichia coli Infections; Hydrogels; Hydrophobic and Hydrophilic Interactions; Male; Melitten; Mice; Mice, Inbred BALB C; NIH 3T3 Cells; Peptides; Rheology; Wound Healing

High throughput in vivo laboratory models is need for screening and identification of effective therapeutic agents to overcome microbial drug-resistance. This study was undertaken to evaluate in vivo antimicrobial efficacy of short-chain antimicrobial peptide- Cecropin A (1-7)-Melittin (CAMA) against three multi-drug resistant enteroaggregative Escherichia coli (MDR-EAEC) field isolates in a Galleria mellonella larval model. The minimum inhibitory concentration (MIC; 2.0 mg/L) and minimum bactericidal concentration (MBC; 4.0 mg/L) of CAMA were determined by microdilution assay. CAMA was found to be stable at high temperatures, physiological concentration of cationic salts and proteases; safe with sheep erythrocytes, secondary cell lines and commensal lactobacilli at lower MICs; and exhibited membrane permeabilization. In vitro time-kill assay revealed concentration- and time-dependent clearance of MDR-EAEC in CAMA-treated groups at 30 min. CAMA- treated G. mellonella larvae exhibited an increased survival rate, reduced MDR-EAEC counts, immunomodulatory effect and proved non-toxic which concurred with histopathological findings. CAMA exhibited either an equal or better efficacy than the tested antibiotic control, meropenem. This study highlights the possibility of G. mellonella larvae as an excellent in vivo model for investigating the host-pathogen interaction, including the efficacy of antimicrobials against MDR-EAEC strains.

Topics: Animals; Anti-Bacterial Agents; Antimicrobial Cationic Peptides; Antimicrobial Peptides; Disease Models, Animal; Drug Resistance, Multiple, Bacterial; Escherichia coli; Escherichia coli Infections; Larva; Melitten; Microbial Sensitivity Tests; Moths; Survival Rate

Antimicrobial peptides hold potential as a possible alternative, or complement, to conventional antibiotics but new, safe and efficient means are needed for formulation and administration of the peptides. In this study we have investigated the utility of a novel type of lipid particles, the polyethylene glycol-stabilized lipid disks, as carriers for the model peptide melittin. The structural integrity of the carrier particle when loaded with the peptide was investigated using cryo-transmission electron microscopy. Liposome leakage upon addition of the peptide-lipid disks was monitored as a means to verify the membrane lytic effect of the formulation. The susceptibility of melittin to tryptic digestion was studied and compared in the absence and presence of lipid disks. Finally, the antibacterial effect of the peptide-lipid disk formulation was compared to that of free melittin after both single and repeated exposure to Escherichia coli. The results show that melittin can redistribute from the disk into a new host membrane and that formulation in the disks does not compromise melittin's membrane permeabilizing ability. Further, the peptide was found to be fully protected against degradation when bound to the disks. Time-kill experiments revealed that all the antibacterial effect of melittin administered in free form was gone after a single exposure to E. coli. In contrast, the disk formulation showed significant cell-killing effect also upon a second exposure to bacteria, indicating an extended release of peptide from the lipid disks. These results suggest that the lipid disks constitute a new class of promising carriers for peptide antibiotics.

Topics: Amino Acid Sequence; Anti-Bacterial Agents; Drug Carriers; Escherichia coli; Escherichia coli Infections; Humans; Lipids; Melitten; Molecular Sequence Data; Polyethylene Glycols; Proteolysis