Quick summary
Cathelicidins are endogenous antimicrobial peptides, with LL-37 being the sole human member. LL-37 has broad-spectrum antimicrobial activity, accelerates wound healing by activating keratinocyte migration and angiogenesis, and is notably absent in chronic non-healing ulcers.
Overview
Cathelicidins are a family of endogenous antimicrobial peptides characterized by a conserved N-terminal cathelin domain and a variable C-terminal antimicrobial peptide. LL-37 is the sole human cathelicidin — a 37-amino acid cationic peptide with broad-spectrum antimicrobial, wound-healing, and immunomodulatory activity. Research interest spans topical antimicrobials, chronic wound care, and cancer biology.
Mechanism of action
LL-37 disrupts bacterial membranes via amphipathic alpha-helix insertion, causing membrane depolarization and lysis. It also binds lipopolysaccharide (LPS), neutralizing endotoxin. Beyond direct killing, LL-37 activates keratinocyte migration through formyl peptide receptor 2 (FPR2), triggering MAPK and PI3K/Akt signaling. It promotes angiogenesis by activating VEGFR2, and recruits neutrophils, monocytes, and T cells via FPR1. In wounds, LL-37 accelerates re-epithelialization and vascularization and is notably absent in chronic non-healing ulcers.
Dosing protocols
| Purpose | Route | Dosage | Frequency | Notes |
|---|---|---|---|---|
| wound healing research | topical | 50–200 mcg/mL | once to twice daily | Concentrations used in preclinical and early-phase wound healing studies; clinical dosing not established |
Dosing information is for educational purposes only. Consult a qualified healthcare professional before using any peptide.
Research summary
LL-37 is found in neutrophil granules, keratinocytes, lung epithelium, and intestinal Paneth cells. Studies demonstrate that topical LL-37 accelerates healing of chronic wounds in diabetic and venous ulcer models. It shows activity against MRSA, Pseudomonas aeruginosa, and biofilms. In vitro and early-phase clinical data support its role in wound management. Paradoxically, overexpression is linked to inflammatory skin diseases (rosacea, psoriasis) and certain cancers, where LL-37 acts as a growth factor. No LL-37 drug is currently FDA-approved; clinical trials are ongoing.[1][2][3][4]
Evidence grading
Each claimed benefit is graded by the strength of available evidence. Grades reflect study quality, not effect size.
Strong = multiple RCTs · Moderate = limited trials or observational · Preliminary = animal or in vitro only · Insufficient = anecdotal or no published data
Side effects
Side effects vary by individual. This is not an exhaustive list. Report unusual symptoms to a healthcare professional.
Common stacks
Peptides commonly paired with Cathelicidins for synergistic effects.
Legal status
LL-37 and related cathelicidin peptides are research-only compounds. Synthetic LL-37 is available from peptide suppliers for research use. Not approved as a human therapeutic as of 2026.
Sourcing & access
Research compound
Cathelicidins is classified as a research compound. Regulatory status varies by jurisdiction. Always verify current legal status and source from vendors providing third-party certificates of analysis (COA).
Frequently asked questions
Cathelicidins are a family of antimicrobial peptides with a conserved cathelin domain. LL-37 is the sole human cathelicidin, a 37-amino acid cationic peptide with broad-spectrum antimicrobial, wound-healing, and immunomodulatory activity found in neutrophils, keratinocytes, and lung epithelium.
LL-37 disrupts bacterial membranes via amphipathic alpha-helix insertion, neutralizes endotoxin (LPS), activates keratinocyte migration through FPR2 receptors, promotes angiogenesis via VEGFR2, and recruits immune cells. In wounds, it accelerates re-epithelialization and vascularization.
Side effects include local irritation at application sites and pro-inflammatory effects at high concentrations. It may exacerbate rosacea in susceptible individuals. Paradoxically, LL-37 overexpression is linked to inflammatory skin diseases (rosacea, psoriasis) and certain cancers.
Topical LL-37 accelerates healing of chronic wounds in diabetic and venous ulcer models and shows activity against MRSA, Pseudomonas, and biofilms. Its absence in chronic non-healing ulcers suggests therapeutic potential, though no LL-37 drug is currently FDA-approved.