Development of a novel short 12-meric papiliocin-derived peptide that is effective against Gram-negative sepsis

Myeong Seon Jeong,Yeongjoon Lee,Mihee Jang,Sujin Lee,Binu Jacob,Chulhee Kwak,Yangmee Kim,Seung-Hae Kwon,In Duk Jung,Jieun Kim,Kkabi Son

doi:10.1038/s41598-019-40577-8

Abstract

The development of novel peptide antibiotics with potent activity against multidrug-resistant Gram-negative bacteria and anti-septic activity is urgently needed. In this study, we designed short, 12-meric antimicrobial peptides by substituting amino acids from the N-terminal 12 residues of the papiliocin (Pap12-1) peptide to alter cationicity and amphipathicity and improve antibacterial activity and bacterial membrane interactions. Pap12-6, with an amphipathic α-helical structure and Trp12 at the C-terminus, showed broad-spectrum antibacterial activity, especially against multidrug-resistant Gram-negative bacteria. Dye leakage, membrane depolarization, and electron microscopy data proved that Pap12-6 kills bacteria by permeabilizing the bacterial membrane. Additionally, Pap12-6 significantly reduced the secretion of NO, TNF-α, and IL-6 and secreted alkaline phosphatase reporter gene activity confirmed that Pap12-6 shows anti-inflammatory activity via a TLR4-mediated NF-κB signaling pathway. In a mouse sepsis model, Pap12-6 significantly improved survival, reduced bacterial growth in organs, and reduced LPS and inflammatory cytokine levels in the serum and organs. Pap12-6 showed minimal cytotoxicity towards mammalian cells and controlled liver and kidney damage, proving its high bacterial selectivity. Our results suggest that Pap12-6 is a promising peptide antibiotic for the therapeutic treatment of Gram-negative sepsis via dual bactericidal and immunomodulatory effects on the host.

Highlights

The development of novel peptide antibiotics with potent activity against multidrug-resistant Gramnegative bacteria and anti-septic activity is urgently needed
Pap[] significantly reduced the secretion of NO, TNF-α, and IL-6 and secreted alkaline phosphatase reporter gene activity confirmed that Pap[] shows anti-inflammatory activity via a toll-like receptor 4 (TLR4)-mediated nuclear factor-κB (NF-κB) signaling pathway
Previous studies have reported 12-meric peptides with potent antibacterial activities derived from long α-helical Antimicrobial peptides (AMPs), such as MSI-78 and LL-3726,27

Summary

Introduction

The development of novel peptide antibiotics with potent activity against multidrug-resistant Gramnegative bacteria and anti-septic activity is urgently needed. Our results suggest that Pap[] is a promising peptide antibiotic for the therapeutic treatment of Gram-negative sepsis via dual bactericidal and immunomodulatory effects on the host. Gram-negative bacterial infection leads to the release of LPS, which are recognised by toll-like receptor 4 (TLR4) on macrophages, subsequently triggering the overexpression of cytokines and an uncontrolled inflammatory response, leading to sepsis[6,7,8]. Gram-negative sepsis results from a harmful host response to infection, in which bacteria and LPS released from bacteria activate immune cells, such as monocytes and macrophages[9]. Many AMPs are active against multidrug-resistant (MDR) pathogenic bacteria and mainly target the bacterial cell membrane, making them a promising new class of therapeutic agents[15,16,17].

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Conclusion