Antimicrobial peptide-chitosan nanoparticles combat ETEC-induced bacterial infection in mice

Antimicrobial peptides (AMPs) are promising alternatives to antibiotics. However, the disadvantage of AMPs in combating bacterial infections in vivo restricts their practical application. In this study, 3W-2-chitosan-nanoparticles (3W-2-CS-NPs) were successfully constructed by encapsulating the porcine-derived AMPs 3W-2 (WRLRWKTRWRLK-NH₂), previously developed by our team, with chitosan (CS). This novel formulation aims to enhance the antibacterial activity and stability of AMPs in vivo, with the specific goal of mitigating the systemic organ impairments induced by Enterotoxigenic Escherichia coli (ETEC) infection. In vitro studies demonstrated that 3W-2-CS-NPs exhibited sustained-release properties and stronger antibacterial activity in comparison to chitosan-nanoparticles (CS-NPs). Additionally, 3W-2-CS-NPs maintained better antibacterial activity in gastric and intestinal fluid environments compared to 3W-2. In vivo studies showed that the gavage of 3W-2-CS-NPs alleviated weight loss, liver damage, systemic inflammation, and intestinal mucosal injury induced by ETEC infection in mice. Furthermore, 3W-2-CS-NPs were demonstrated to promote intestinal microecological balance, as evidenced by 16S rRNA sequencing analysis. Conclusively, this study suggests that the construction of AMPs-CS-NPs has the potential to enhance the in vivo therapeutic efficacy of AMPs and lays the theoretical foundation for the application of AMPs as additives in food and animal husbandry.