Antimicrobial Peptides

In basic research, antimicrobial peptides (AMPs) have been proposed as an alternative to antibiotic therapy. As part of the innate immune system, AMPs are widely found in both plants and animals. AMPs are known to clear infection in the host mostly through direct killing mechanism [i]. Generally, AMPs showing antibiotic activity are cationic (positively charged) and amphiphilic (hydrophilic and hydrophobic) molecules. They could be both of natural origin or designed in order to improve efficacy or lower toxicity. This field could represent an alternative approach to overcome antibiotic resistance, thanks to the AMP modes of action. For instance, they have the capacity to alter membrane permeability or bind nutrients or other microbial macromolecules, depending on their size [ii].

Major drawbacks of these compounds are related to their non-specific action, which can lead to side effects, and the existence of bacterial defense mechanisms. Proteases or trapping proteins, for example, can deactivate AMPs; alternatively, modifications of cell wall surface charge and other defense strategies can decrease bacterial susceptibility to this class of molecules [ii]. While 3.6% of reviews focus on this strategy, with our search criteria we did not retrieve examples of clinical trials using AMPs, although some clinical studies can be found searching directly for specific peptides such as magainins in the “other terms” search field [iii].