LL-37: The Swiss Army Knife Peptide of Your Immune System

This review establishes LL-37 as far more than an antimicrobial peptide. As the sole human cathelicidin, LL-37 serves as a broad-spectrum natural antibiotic, but also has potent chemotactic properties (attracting immune cells to sites of infection) and immunomodulatory effects. The authors analyzed LL-37’s therapeutic potential across four major systems: immune, respiratory, gastrointestinal, and skin — identifying specific molecular pathways and disease connections in each.

Comprehensive literature review analyzing published research on LL-37’s molecular mechanisms, biological activities, and therapeutic potential across immune, respiratory, gastrointestinal, and skin systems. No original experimental data were generated.

LL-37 is unique in human biology as the only cathelicidin we produce, yet it wears many hats — antimicrobial, immune signaling, wound healing, and inflammation modulation. This review maps those diverse functions to specific diseases and molecular pathways, making a comprehensive case for developing LL-37-based therapeutics that could address conditions ranging from infections to inflammatory bowel disease to skin disorders.

Antimicrobial peptides are increasingly seen as the next generation of antibiotics as drug resistance grows. LL-37 stands out because it’s already part of human innate immunity — we know it’s tolerated and functional. Understanding its full range of activities, from killing bacteria to modulating immune responses in the gut and lungs, positions it as one of the most therapeutically interesting natural peptides in the human body.

This is a narrative review without new experimental data. The therapeutic potential discussed remains largely preclinical, and the gap between LL-37’s known biology and its clinical development as a drug is not fully addressed. The review does not systematically assess evidence quality.