LL-37 (Cathelicidin)
LL-37 is a 37-amino acid cationic host defense peptide derived from the C-terminus of the human cathelicidin precursor hCAP18, and the only cathelicidin expressed in humans. It is constitutively expressed in neutrophils and is induced in epithelial cells of the skin, gut, and lungs during infection or injury, functioning as a first-line innate immune defense by disrupting microbial membranes and modulating inflammatory signaling. Beyond direct antimicrobial activity, LL-37 promotes wound healing through keratinocyte migration, angiogenesis, and re-epithelialization, with topical formulations under investigation for chronic wounds and atopic dermatitis. Human clinical data are limited to small exploratory studies; injectable systemic use is experimental with no established dosing or safety data, and its pleiotropic immune effects create potential for pro-inflammatory effects in certain contexts.
Evidence last reviewed: 19 Apr 2026
Not a routine supplement — not recommended for self-directed use.
Information here is educational only, not a recommendation to use. See our Safety page.
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Evidence is from research or clinical settings — does not imply safety outside supervised contexts.
The evidence for LL-37 is limited to small studies and systematic reviews, indicating potential benefits in wound healing and immune modulation. However, the overall strength of the evidence is low, and more extensive research is needed to establish safety and efficacy.
Antimicrobial activityPatients with drug-resistant infections · Systematic reviewLow
Antimicrobial peptides, including LL-37, are implicated in managing periodontal and oral tissue conditions.
Immune modulationCritically ill patients with sepsis · RCTLow
Vitamin D promotes LL-37 synthesis, potentially aiding immune response in sepsis.
Wound healingPatients with chronic wounds · RCTLow
LL-37 showed potential in enhancing wound healing in chronic wound patients.