Therapeutic Potential of Novel Antimicrobial Peptide Pap12-6-10: Mechanisms of Antibacterial and Anti-inflammatory Action Against Gram-Negative Sepsis.

To develop novel antibiotics, we engineered 12-mer peptides derived from the N-terminus of papiliocin. Pap12-6-10 emerged as a potent antibacterial agent against multidrug-resistant Gram-negative bacteria, demonstrating a low propensity for resistance development. Pap12-6-10 exerts its antibacterial activity by permeabilizing bacterial membranes through binding to lipopolysaccharide (LPS), inducing oxidative stress that leads to cell death. Pap12-6-10 modulates LPS-induced inflammatory responses by selectively targeting the TLR4 signaling pathways. Structural analysis using NMR, surface plasmon resonance, docking, and molecular dynamics simulations suggested that Pap12-6-10 binds to the hydrophobic pocket of MD-2, thereby preventing the LPS-induced dimerization of the TLR4/MD-2 complex, which is essential for inflammatory signaling during sepsis. In the Escherichia coli K1 and carbapenem-resistant Acinetobacter baumannii-induced sepsis mouse model Pap12-6-10 protected organ damage from septic shock and displayed significant therapeutic effects while maintaining low cytotoxicity. This study highlights its potential as a valuable candidate for treating Gram-negative infections.