2016 Volume 62 Issue 2 Pages 112-119
Antimicrobial peptides (AMPs) are produced by multicellular organisms and play an important role in innate immunity. AMPs are considered to be promising candidates for novel antibiotics because the emergence of drug-resistant bacteria has become a serious global health problem. There are many advantages of AMPs over conventional antibiotics, including a broad antibacterial spectrum and unique antibacterial mechanisms. Importantly, microbial resistance to membrane-disruptive AMPs is very unlikely to occur rapidly because changes in the target cell membrane cannot occur within a short period. However, antigenicity, cytotoxicity, stability, and production cost are the main difficulties with the application of AMPs for therapeutic purposes. Therefore, modifications of the original AMPs have been performed to overcome these difficulties.
Here we describe our work on the potential therapeutic applications of AMPs as well as the development of beetle defensin-derived AMPs and their multiple functions and applications. The defensin-derived AMPs disrupt negatively charged phospholipids on the cell membrane, showing direct cytotoxic activity against bacteria, fungi, protozoa, and cancer cell lines as well as induce apoptosis by disrupting the mitochondrial membrane; however, it does not demonstrate cytotoxic activity against normal mammalian cells. AMPs also show telomerase inhibition activity. They showed therapeutic effects in MRSA and Escherichia coli (E. coli)-infected mice, with very weak antigenicity. The AMP-immobilized fibers exhibited potent antibacterial activity against Staphylococcus aureus (S. aureus), including MRSA, and the activity was maintained even after repetitive washing and sterilization by autoclaving. These results suggest that the AMP-immobilized fibers are promising for use as novel antimicrobial materials.