A mini-review on cathelicidin in fish: Gene expression, immune function, and evolutionary insights.

Abstract

Cathelicidins are a family of cationic antimicrobial peptides that play a critical role in innate immune defense. Similar to other antibacterial peptides, cathelicidins can kill pathogens while significantly reducing the risk of inducing antimicrobial resistance, a growing concern in the aquaculture industry. Although cathelicidins are widely distributed across vertebrates, from basal vertebrate species such as hagfish and lampreys to mammals, the number of identified cathelicidin sequences in fish remains relatively limited. This review aims to comprehensively summarize current knowledge on teleost cathelicidins, including their expression patterns, antimicrobial properties, and immunomodulatory functions, while also highlighting prospects for future research. Additionally, we conducted a genomic analysis to examine the species distribution and evolutionary history of cathelicidin in fish. Our findings reveal conserved synteny of cathelicidin loci in both cartilaginous and bony fishes, along with lineage-specific expansions and chromosomal rearrangements that may have contributed to gene loss. Overall, this study offers a valuable reference for advancing our understanding of cathelicidins in teleosts, and serves as a foundation for future research into their evolutionary history, biological functions, and potential applications in fish health management and aquaculture.