Lepidopteran Antimicrobial Peptides (AMPs): Overview, Regulation, Modes of Action, and Therapeutic Potentials of Insect-Derived AMPs

Abstract

Due to overuse of antibiotics or drugs, antibiotic resistance and multidrug resistance in pathogenic bacteria have been rising during the last two decades. Therefore, there is an urgent need for development of natural antibiotics in the form of antimicrobial peptides (AMPs). These are produced by nearly all organisms, from bacteria to plants and animals, and can protect against a broad array of pathogenic bacteria, fungi, parasites, viruses, and protozoa and thus may serve as alternatives to synthetic (conventional) antibiotics. Apart from microbicidal properties of AMPs, they have been shown to act as immunomodulators with chemoattractants, to exhibit signaling activities, and also to help in the management of beneficial endosymbionts. As a result, clinical programs on host defense AMPs have been established in the areas of cancer biology, infection, inflammation, and dermatology. This chapter provides a detailed account of the anti-infective properties of AMPs derived from lepidopterans for clinical research in the biotechnology industry. It focuses on the expression of AMPs in insects belonging to the order Lepidoptera upon lipopolysaccharide (LPS) challenge and discusses their various functions and relative mechanisms of action with bacterial membranes. Insect AMPs show greater evolutionary dynamism than conserved components such as signaling molecules, and this may explain insects’ ability to mount a high immune response and/or colonize new niches. Thus, understanding the modes of action of these AMPs will give insights into host-parasite coevolution as well as enable design of next-generation antibiotics.