Exploring Fish Antimicrobial Peptides (Amps): Classification, Biological Activities, and Mechanisms of Action

Despite the growing productivity of aquaculture, economic losses due to infectious diseases, environmental pollution, and human safety concerns related to antibiotic resistance are limiting its growth. Therefore, research is intensively focused on alternative strategies for controlling infectious diseases.

Antimicrobial peptides (AMPs) are short, usually cationic, amphipathic, germline-encoded endogenous peptides possessing molecular weight less than 13 kDa, which show an extended variety of different families of highly conserved peptides found widely throughout Nature, which play a crucial role in molecular and cellular host defense towards pathogens (bacteria, viruses, parasites, and fungi), tissue damage, and infection.

They emerge as a promising antibiotic alternative due to their unique and multidimensional properties, including their low potential for developing antimicrobial resistance, minimal cytotoxicity to mammalian cells, high selective cytotoxicity against bacteria, low residual flesh, and ability to modulate host immune responses. Also, their ability to act even in extremely high salt concentrations, makes them suitable potential targets for development as therapeutic antimicrobials. AMPs are induced by various elements, including dietary ingredients and specific molecules also known as pathogen-associated molecular patterns (PAMPs), which may activate downstream signals to initiate transcription of AMP genes. Fish are an excellent origin of the peptides, as they express all major AMP families, including defensins, cathelicidins, hepcidins, histone-derived peptides, and a fish-specific class, called piscidins. Given their increasing attention in research, this review investigates various fish AMPs, their biological activities, and mechanisms of action.

The findings suggest that fish can serve as sources of unique peptides with a broad range of biological activities, thereby offering a novel class of antibiotics.