What Is LL-37? Benefits, Research & Safety

Cathelicidins were first discovered in the early 1990s as a family of antimicrobial peptides found in various mammalian species. In 1995, human cathelicidin (hCAP18) was identified in neutrophils. Researchers discovered that hCAP18 requires proteolytic processing to release the active antimicrobial peptide. The active portion, LL-37, was characterised and found to have broad-spectrum antimicrobial activity. Subsequent research revealed that LL-37's functions extended beyond direct antimicrobial killing. Studies demonstrated immunomodulatory effects, influence on wound healing, and roles in inflammatory responses. This multifunctionality has made LL-37 an intensively studied peptide. Research has also identified associations between LL-37 levels and various diseases. Deficiency is associated with increased susceptibility to infections, while overexpression or dysregulation may contribute to autoimmune conditions like psoriasis. The peptide's complexity—beneficial antimicrobial effects but potential for inflammatory damage in some contexts—has made therapeutic development challenging but continues to be an active area of research.