Antimicrobial peptides loaded collagen nanosheets with enhanced antibacterial activity, corneal wound healing and M1 macrophage polarization in bacterial keratitis

Bacterial keratitis is one of the leading causes of blindness in the world. Frequent administration of antibiotic eye drops is the first-line treatment, which has difficulties in achieving favorable outcomes in some cases due to the emerging antibiotic resistance and low bioavailability. Antimicrobial peptides have been shown to overcome antibiotic resistance through diverse bactericidal mechanisms including antibiofilm effects, enabling them to be a promising strategy to combat resistance. Here, we report a novel antibacterial strategy with collagen nanosheets (CN) loaded with the cationic antimicrobial short peptide Tet213 (Tet213-CN). In this study, we demonstrated that Tet213-CN possessed excellent properties with good adherence, high oxygen permeability, transparency, biocompatibility, and showed no ocular irritation. In vitro and in vivo assays demonstrated that Tet213-CN had enhanced antibacterial and corneal epithelial healing effects. Furthermore, we observed that Tet213-CN treatment facilitated innate immune defense by promoting M1 macrophage polarization, increasing intracellular ROS generation and proinflammatory cytokine secretion, and enhancing phagocytosis of bacteria via the TLR2/ MyD88/NF-kappa B signaling pathway. Most impressively, Tet213-CN achieved considerable outcomes in Pseudomonas aeruginosa keratitis models with a one-time application. Overall, Tet213-CN may serve as an ideal strategy in the management of bacterial keratitis, and shed new light onto the treatment against antibioticresistant bacteria. In addition, these results provide a conceptual framework for a novel macrophage-based strategy in the treatment of corneal infection diseases.