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.