Temporin-GHb-Derived\nPeptides Exhibit Potent Antibacterial\nand Antibiofilm Activities against <i>Staphylococcus aureus</i> In Vitro and Protect Mice from Acute Infectious Pneumonia

Abstract

With the continuous development of drug resistance in\nbacteria\nto traditional antibiotics, the demand for novel antibacterial agents\nis urgent. Antimicrobial peptides (AMPs) are promising candidates\nbecause of their unique mechanism of action and low tendency to induce\ndrug resistance. Previously, we cloned temporin-GHb (hereafter referred\nto simply as “GHb”) from <i>Hylarana guentheri</i>. In this study, a series of derived peptides were designed, namely,\nGHbR, GHbK, GHb3K, GHb11K, and GHbK4R. The five derived peptides had\nstronger antibacterial activities against <i>Staphylococcus aureus</i> than the parent peptide GHb and could effectively inhibit the formation\nof biofilms and eradicate mature biofilms in vitro. GHbR, GHbK, GHb3K,\nand GHbK4R exerted bactericidal effects by disrupting membrane integrity.\nHowever, GHb11K exhibited bacteriostatic efficacy with toroidal pore\nformation on the cell membrane. In comparison to GHbK4R, GHb3K showed\nmuch lower cytotoxicity against A549 alveolar epithelial cells, with\nan IC₅₀ > 200 μM, which was much higher than its\nminimal inhibitory concentration (MIC = 3.1 μM) against <i>S. aureus</i>. The anti-infection potential of GHbK4R and GHb3K\nwas investigated in vivo. Compared with vancomycin, the two peptides\ndisplayed significant efficacy in a mouse model of acute pneumonia\ninfected with <i>S. aureus</i>. Both GHbK4R and GHb3K also\nhad no obvious toxicity to normal mice after intraperitoneal administration\n(15 mg/kg) for 8 days. Our results indicate that GHb3K and GHbK4R\nmight be promising candidates for the treatment of bacterial pneumonia\ninfected with <i>S. aureus</i>.