LL-37: Benefits & Research

LL-37 is the only human cathelicidin antimicrobial peptide, active against a remarkably broad range of pathogens including gram-positive bacteria (S. aureus, including MRSA), gram-negative bacteria (E. coli, P. aeruginosa), fungi (Candida), and enveloped viruses. The antimicrobial mechanism involves direct membrane disruption — LL-37's amphipathic helical structure inserts into microbial membranes, forming pores that kill the pathogen.

This broad-spectrum activity has generated interest in LL-37 as a potential alternative or complement to conventional antibiotics, particularly for antibiotic-resistant infections.

A particularly valuable property of LL-37 is its ability to disrupt bacterial biofilms — the protective matrix communities that bacteria form on surfaces including medical devices, wounds, and mucosal surfaces. Biofilms are a major clinical challenge because they are 100–1,000× more resistant to antibiotics than planktonic (free-floating) bacteria. LL-37 can both prevent biofilm formation and break down established biofilms.

Beyond direct antimicrobial killing, LL-37 acts as a potent immune modulator:

• Chemotaxis — attracts immune cells (neutrophils, monocytes, T cells) to infection sites
• Promotes wound healing through angiogenesis and cell migration
• Modulates inflammatory cytokine production
• Enhances macrophage phagocytosis and bacterial killing
• Acts as an alarmin — bridging innate and adaptive immune responses

For other immune-modulating peptides, see KPV (anti-inflammatory) and thymosin beta-4 (tissue repair and immune regulation).

LL-37 promotes wound healing through multiple mechanisms: direct antimicrobial activity at the wound site (preventing infection), promotion of keratinocyte and fibroblast migration, stimulation of angiogenesis (new blood vessel formation), and modulation of the inflammatory response to favor tissue repair over chronic inflammation.