LL-37

Overview

LL-37 is the only human cathelicidin antimicrobial peptide, produced by immune cells, epithelial cells, and skin. It plays a critical role in the innate immune defense against bacteria, viruses, and fungi, and is studied for chronic infections and wound healing.

Mechanism of Action

LL-37 directly disrupts microbial membranes through electrostatic interactions with negatively charged lipid bilayers. Beyond direct antimicrobial activity, it modulates immune responses by activating chemotaxis, promoting wound healing, modulating apoptosis, and stimulating angiogenesis. It signals through formyl peptide receptor-like 1 (FPRL1) and P2X7 receptors.

Research Summary

Clinical interest has grown for treatment of chronic infections, biofilm-associated infections, and wound healing. Studies show efficacy against antibiotic-resistant bacteria including MRSA. It is also studied in the context of CIRS (Chronic Inflammatory Response Syndrome) and mold-related illness. Research on synthetic delivery remains a challenge due to peptide stability.

Dosing Information

Reported Side Effects

• Injection site pain and redness
• Flu-like symptoms (cytokine response)
• Headache
• Fatigue

Research References

• LL-37, the only human member of the cathelicidin family of antimicrobial peptides (2003)
• The human antimicrobial peptide LL-37 — a multifunctional peptide involved in infection and inflammation (2014)
• LL-37 disrupts biofilms and enhances antimicrobial activity against Staphylococcus aureus (2014)