Antimicrobial Peptides of the Cathelicidin Family: Focus on LL-37 and Its Modifications

Cathelicidins are a family of antimicrobial peptides (AMPs) with broad-spectrum activity and immunomodulatory functions. Among them, the only human cathelicidin LL-37 has garnered significant interest due to its potent antimicrobial, antiviral, antifungal, antiparasitic, and antitumor properties. However, the clinical application of LL-37 is hindered by several limitations, including low proteolytic stability, cytotoxicity, and high production costs. To overcome these challenges, a wide range of design strategies have been employed to modify LL-37 and improve its therapeutic potential. LL-37-based analogs represent promising candidates for the development of next-generation antimicrobial and immunomodulatory therapies. Despite significant progress, further research is required to optimize peptide design, ensure cost-effective production, and validate long-term safety and efficacy. Advances in computational modeling, high-throughput screening, and nanotechnology will play an important role in the translation of modified cathelicidins into clinical practice. This review summarizes key strategies of chemical and structural modifications of LL-37 aimed at enhancing its functional properties. Particular attention is given to truncated and retro-analogs, which preserve or improve biological activity while exhibiting reduced toxicity and increased proteolytic resistance. Furthermore, we highlight the use of nanoscale delivery systems, which facilitate targeted delivery, prolong peptide half-life, and mitigate cytotoxic effects.