The Addition of a Synthetic LPS-Targeting Domain Improves Serum Stability While Maintaining Antimicrobial, Antibiofilm, and Cell Stimulating Properties of an Antimicrobial Peptide.

Anna Maystrenko,Yulong Feng,Nadeem Akhtar,Julang Li

doi:10.3390/biom10071014

Abstract

Multi-drug resistant (MDR) bacteria and their biofilms are a concern in veterinary and human medicine. Protegrin-1 (PG-1), a potent antimicrobial peptide (AMP) with antimicrobial and immunomodulatory properties, is considered a potential alternative for conventional antibiotics. AMPs are less stable and lose activity in the presence of physiological fluids, such as serum. To improve stability of PG-1, a hybrid peptide, SynPG-1, was designed. The antimicrobial and antibiofilm properties of PG-1 and the PG-1 hybrid against MDR pathogens was analyzed, and activity after incubation with physiological fluids was compared. The effects of these peptides on the IPEC-J2 cell line was also investigated. While PG-1 maintained some activity in 25% serum for 2 h, SynPG-1 was able to retain activity in the same condition for up to 24 h, representing a 12-fold increase in stability. Both peptides had some antibiofilm activity against Escherichia coli and Salmonella typhimurium. While both peptides prevented biofilm formation of methicillin-resistant Staphylococcus aureus (MRSA), neither could destroy MRSA’s pre-formed biofilms. Both peptides maintained activity after incubation with trypsin and porcine gastric fluid, but not intestinal fluid, and stimulated IPEC-J2 cell migration. These findings suggest that SynPG-1 has much better serum stability while maintaining the same antimicrobial potency as PG-1.

Highlights

Biofilms are multilayer communities of immobile bacteria that grow adhered to a surface, encased within a self-produced extracellular polymeric substance (EPS) matrix, and differ from their planktonic counterparts growing in nutrient-rich media [1]
A 3D model of SynPG-1 was predicted through I-TASSER and visualized using ChimeraX
In an unpublished study evaluating the stability of various hybrid peptides in serum, we found that the novel Syn-possessing peptide had the highest stability, indicating some potential protective effects through the addition of the Syn domain

Summary

Introduction

Biofilms are multilayer communities of immobile bacteria that grow adhered to a surface, encased within a self-produced extracellular polymeric substance (EPS) matrix, and differ from their planktonic counterparts growing in nutrient-rich media [1]. These bacterial communities can be found growing on both organic and inorganic surfaces. Biofilms growing on organic surfaces are associated with chronic infections of epithelial and mucosal surfaces, such as Pseudomonas-associated cystic fibrosis [4], urinary tract infections, and foot ulcers [5] In animals, these infections manifest as mastitis, wound lesions, enteritis, and pneumonia [6]. Treatment for biofilm infections is scarce as many biofilms have an inherent resistance to conventional antibiotics due to the protective EPS matrix and can persist even after treatment with concentrations a thousand times their minimal inhibitory concentration [7]

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