LL-37

LL-37 is the only human cathelicidin-derived antimicrobial peptide, cleaved from the precursor protein hCAP18 by serine proteases at sites of infection and inflammation. This 37-amino acid cationic peptide adopts an alpha-helical structure and plays a crucial role in innate immune defense.

The antimicrobial activity of LL-37 stems from its ability to disrupt microbial membranes through electrostatic interaction with negatively charged phospholipids. It demonstrates broad-spectrum activity against gram-positive and gram-negative bacteria, fungi, viruses, and even some parasites. Importantly, LL-37 can also disrupt and prevent biofilm formation.

Beyond direct antimicrobial effects, LL-37 functions as an immunomodulatory molecule, influencing cytokine production, recruiting immune cells through chemotactic activity, and modulating inflammatory responses. It promotes wound healing through stimulation of angiogenesis, keratinocyte migration, and extracellular matrix production.

Research into LL-37 has revealed its involvement in numerous physiological and pathological processes, including skin barrier function, respiratory defense, inflammatory bowel disease, and cancer. Its dual antimicrobial and wound-healing properties make it particularly valuable for research into chronic wounds and infected tissue repair.