LL-37 (5mg)

LL‑37 is a 37‑amino‑acid human cathelicidin antimicrobial peptide produced naturally in the body as part of the innate immune system. Its name comes from the two leucine residues at its N‑terminus (“LL”) and its length (“37”). It is the only naturally produced human cathelicidin, derived from the precursor protein hCAP18 (human cationic antimicrobial protein 18 kDa) Jay Campbell+1.

How It’s Made

• Precursor: hCAP18 is stored in granules of immune cells like neutrophils, macrophages, and mast cells, and in epithelial cells of skin, lungs, gut, and urogenital tract www.peptidesinstitute.org.
• Activation: Enzymes such as proteinase 3, neutrophil elastase, and serine proteases cleave hCAP18 to release active LL‑37 peptidedosages.com+1.
• Regulation: Expression is influenced by proinflammatory cytokines, growth factors, and vitamin D, which binds to vitamin D receptors in the LL‑37 gene promoter peptidesexplorer.com.

How It Works

LL‑37 has dual roles:

1. Antimicrobial action:
   • Its positively charged residues bind to negatively charged microbial membranes (e.g., lipopolysaccharides in Gram‑negative bacteria, lipoteichoic acids in Gram‑positive bacteria) peptidesexplorer.com+1.
   • It inserts into lipid bilayers, forming pores or disrupting membrane integrity, killing bacteria, fungi, and some viruses peptidesexplorer.com+1.
   • Effective against drug‑resistant strains like MRSA and VRE www.peptidesinstitute.org.
   • Can disrupt bacterial biofilms at sub‑antimicrobial concentrations peptidesexplorer.com.
2. Immune and tissue modulation:
   • Recruits immune cells (neutrophils, macrophages, dendritic cells) to infection sites www.peptidesinstitute.org.
   • Enhances phagocytosis and adaptive immune priming.
   • Promotes angiogenesis, wound healing, and tissue repair peptidesexplorer.com+1.
   • Neutralizes bacterial endotoxins like LPS, helping to control excessive inflammation peptidedosages.com+1.

Biological Context

LL‑37 is released at sites of infection, inflammation, or tissue damage. It is a first‑line defense in mucosal and epithelial barriers, and its production is linked to vitamin D status — low vitamin D correlates with reduced LL‑37 and higher infection risk peptidesexplorer.com.

Research & Applications

• Topical wound healing: Clinical evidence supports LL‑37 in wound care, where it accelerates closure and modulates inflammation peptidedosages.com.
• Infection control: Studied for bacterial, fungal, and viral infections, and for biofilm disruption peptidesexplorer.com+1.
• Immune support: Explored in chronic inflammatory and autoimmune conditions due to its immune‑modulating effects peptidedosages.com+1.

In summary: LL‑37 is a versatile human peptide that both directly kills microbes and orchestrates immune and repair processes, making it a key player in innate immunity and a promising therapeutic candidate for infections, wounds, and inflammatory disorders peptidedosages.com+2.