LL-37
A naturally occurring antimicrobial cathelicidin peptide with dual antimicrobial and immune signaling activity.
Mechanism of Action
Bioregulator compound with targeted biochemical activity.
Evidence Chain
LL-37
COMPOUND
1 Research Goal
• Immune & Antimicrobial
Evidence Strength
2 articles sourced
Knowledge Graph
(3 connections)Research Evidence
(2)LL-37 (Cathelicidin): Antimicrobial Peptide Biology and Clinical Research Landscape
LL-37 is the only human cathelicidin antimicrobial peptide, with dual roles in direct microbial killing and immunomodulation. This review synthesizes peer-reviewed evidence on its clinical relevance in wound healing, infectious disease, and inflammatory skin disorders.
Peptide Synergy: Immune System Modulation
Evidence-based review of immune peptide synergy, examining thymic function, antimicrobial defense, and cytokine modulation.
Overview
LL-37 is the only known human cathelicidin, a naturally occurring antimicrobial peptide that serves as a key component of the innate immune system. Produced by epithelial cells, neutrophils, and other immune cells, LL-37 provides broad-spectrum antimicrobial defense against bacteria, viruses, and fungi. Beyond its direct antimicrobial activity, LL-37 has emerged as a significant immunomodulatory peptide with roles in wound healing, inflammation regulation, and autoimmune disease.
Mechanism of Action
LL-37 exerts antimicrobial effects through multiple mechanisms. Its cationic (positively charged) amphipathic structure enables it to bind to and disrupt microbial membranes, producing direct killing of bacteria, fungi, and enveloped viruses. Beyond direct antimicrobial activity, LL-37 functions as an immunomodulator: it binds to and neutralizes lipopolysaccharide (LPS), reducing endotoxin-induced inflammation. LL-37 also acts as a chemoattractant for immune cells, activates specific receptors including FPR2 and P2X7, and modulates cytokine production. These immunomodulatory functions connect innate and adaptive immune responses.
Research Highlights
Studies have demonstrated LL-37's broad-spectrum antimicrobial activity against bacteria (including antibiotic-resistant strains), viruses (including respiratory viruses), and fungi. Research has shown wound healing properties, with LL-37 promoting angiogenesis, keratinocyte migration, and epithelial regeneration. Studies have explored its role in autoimmune diseases, where dysregulated LL-37 expression has been implicated in psoriasis, lupus, and rheumatoid arthritis. Research has investigated therapeutic applications in infectious disease, wound healing, and as an immune adjuvant. The dual antimicrobial and immunomodulatory functions make LL-37 a versatile research target.
Dosage & Administration
In research, LL-37 has been administered via topical, subcutaneous, and intravenous routes in animal and in vitro models. No standardized human dosing protocols exist. For research use only (RUO).
Safety Profile
As a naturally occurring human peptide, LL-37 has inherent biocompatibility. However, dysregulated or excessive LL-37 activity has been associated with autoimmune conditions, suggesting that therapeutic applications require careful dosing. Preclinical studies have reported favorable safety profiles at therapeutic doses. Long-term safety data in humans is absent. Not approved by the FDA for any indication.
References
Durr UHN, et al. LL-37: a human antimicrobial peptide. Biochim Biophys Acta. 2006. Vandamme D, et al. LL-37 structure and function. Biochem Soc Trans. 2012. Kuroda K, et al. LL-37 in skin disease. J Invest Dermatol. 2014. All content is for educational and research purposes only.
FDA 2026 Regulatory Update
As of April–June 2026, this compound was among the 14 peptides formally removed from the FDA's Category 2 restricted compounding list following review by the Pharmacy Compounding Advisory Committee (PCAC). This regulatory shift permits licensed compounding pharmacies to produce and dispense this compound under appropriate oversight, subject to final 503A Bulks List adjudication expected following the July 23–24, 2026 PCAC meeting. This does not constitute FDA approval for therapeutic use. All information on this page is for research purposes only.
Related Compounds
Synergy & Compatibility
(3)Computational assessment of bio-regulatory compatibility with compounds sharing research goals. Scores reflect half-life alignment, receptor target overlap, and bioavailability data.
Computational assessment based on available pharmacology data. Does not account for individual variability, dose-dependent effects, or unstudied interactions. For research use only.
Community Observations
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For research use only. Not medical advice.