Antimicrobial and host defense peptides for therapeutic use against multidrug-resistant pathogens: new hope on the horizon.

The concept of using antimicrobial peptides (AMPs) and host defense peptides (HDPs) as therapeutics was first introduced in the late 1990s. However, an AMP drug has yet to reach the market. AMPs and HDPs have intriguing potential as therapeutics: the peptides are evolutionary conserved, and are critical components of the innate immune system of all eukaryotes; their evolution pre-dates the appearance of the adaptive immune system; and they do not readily engender bacterial resistance. Nevertheless, there are significant obstacles to the use of AMPs and HDPs in humans, including the need to conduct clinical trials to demonstrate efficacy, and the capacity to manufacture AMPs and HDPs in a cost-effective manner. Progress in both of these areas would support the exciting possibility that AMPs and HDPs could be developed as therapeutics that kill pathogens and facilitate the immune response.