LL-37
LL-37 is a naturally occurring antimicrobial peptide derived from the protein hCAP18 (the CAMP gene product). Beyond killing microbes, it modulates inflammation, chemotaxis, angiogenesis and wound healing, and its expression is induced by vitamin D. It has a dual nature: it is also implicated in inflammatory skin diseases and some cancers. Synthetic LL-37 has been explored in early clinical research (for example in wound healing), but it is not an approved therapeutic.
Mechanism
In plain terms, LL-37 is part of the body's first line of defence: it disrupts the membranes of bacteria and other microbes and also sends signals that help coordinate the immune response and tissue repair. Technically, it is an amphipathic, cationic alpha-helical peptide cleaved from the C-terminus of hCAP18; it permeabilises negatively charged microbial membranes and also acts as an immunomodulator, reported to bind receptors such as formyl-peptide-receptor-like-1 (FPRL1/FPR2), recruit immune cells, neutralise bacterial lipopolysaccharide, and promote angiogenesis and re-epithelialisation. Its expression is up-regulated by vitamin D (1,25-dihydroxyvitamin D).
Regulatory Status by Region
- United States (FDA)Not FDA-approved; an endogenous human peptide studied in early-stage research and not an approved drug.
- Australia (TGA)Not on the ARTG; no approved LL-37 product.
- European Union (EMA)No EMA marketing authorisation; investigated only in early clinical studies (for example, wound healing).
- WADANot listed by name on the Prohibited List; as an endogenous host-defence peptide it is not a named prohibited substance, but synthetic administration is unapproved and athletes should verify current status.
Key Studies
- LL-37, the only human member of the cathelicidin family of antimicrobial peptides (Durr et al.) (opens in a new tab) (Biochim Biophys Acta 2006;1758(9):1408-1425; DOI 10.1016/j.bbamem.2006.03.030; PMID 16716248)
Related Clinical Trials
- Evaluation of 25(OH)D3 and LL-37 Levels in Periimplant Sulcus FluidN/A · Not Yet Recruiting
- Cathelicidin LL-37 Relation to Potentially Malignant LesionsN/A · Completed
- Crosstalk Between Mucosal-Associated Invariant T (MAIT) Cells and the Gut Microbiota and Mucosa in the Development of Type 1 Diabetes in ChildrenN/A · Recruiting
- Chlorhexidine and Essential Oil Mouthwashes on Human Beta-Defensin 2 (hbD2) and Kathelicidin (LL-37) Saliva LevelsN/A · Unknown
- The Role of Anti-inflammatory Cytokines and Antimicrobial Peptide LL-37 Biomarkers in the Treatment of Periodontal Disease.N/A · Completed
- Peri-implant Vitamin D and Cathelicidin (LL-37) LevelsN/A · Completed
- Cathelicidin LL-37 Levels in the GCF and the Saliva of Smokers and Non-smokers With Stage III,IV PeriodontitisN/A · Completed
- Efficacy of LL-37 Cream on Bacteria Colonization, Inflammation Response and Healing Rate of Diabetic Foot UlcersPhase 2 · Unknown
Related News & Research
- This Week in Peptide Research: Orforglipron Dosing Data, GLP-1 Safety Signals, and a Teriparatide-Osteosarcoma Reporting Signal
- This Week in Peptide Research: GLP-1 Mechanism Studies, LL-37 Engineering Advances, and Kisspeptin's Reach Beyond Reproduction
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Latest research
- LL-37-MRGPRX2-Mast Cell Signaling in Rosacea: Current Evidence and Directions for Human Studies. (opens in a new tab)
Clinical, cosmetic and investigational dermatology · Oct 7, 2026
- Full-length brain-derived α-synuclein fibril models reveal fuzzy-coat control of peptide recognition. (opens in a new tab)
Protein science : a publication of the Protein Society · Oct 1, 2026
Common Questions
- What is LL-37?
- LL-37 is the only human cathelicidin, a 37-amino-acid host-defence (antimicrobial) peptide that the body produces as part of innate immunity. It is an endogenous molecule under active research for antimicrobial, wound-healing and immune-modulating roles; it is not an approved drug, and therapeutic (exogenous) use remains early-stage.
- Is LL-37 approved for medical use?
- LL-37 is investigational: it is being studied in clinical research and is not an approved medicine. United States (FDA): Not FDA-approved; an endogenous human peptide studied in early-stage research and not an approved drug. European Union (EMA): No EMA marketing authorisation; investigated only in early clinical studies (for example, wound healing). Australia (TGA): Not on the ARTG; no approved LL-37 product.
- How does LL-37 work?
- In plain terms, LL-37 is part of the body's first line of defence: it disrupts the membranes of bacteria and other microbes and also sends signals that help coordinate the immune response and tissue repair. Technically, it is an amphipathic, cationic alpha-helical peptide cleaved from the C-terminus of hCAP18; it permeabilises negatively charged microbial membranes and also acts as an immunomodulator, reported to bind receptors such as formyl-peptide-receptor-like-1 (FPRL1/FPR2), recruit immune cells, neutralise bacterial lipopolysaccharide, and promote angiogenesis and re-epithelialisation.
- Is LL-37 legal in Australia?
- LL-37 in Australia (TGA): Not on the ARTG; no approved LL-37 product.
- Is LL-37 banned in sport?
- LL-37 under the World Anti-Doping Agency (WADA) code: Not listed by name on the Prohibited List; as an endogenous host-defence peptide it is not a named prohibited substance, but synthetic administration is unapproved and athletes should verify current status.