LL-37

LL-37 Peptide – 5mg
LL-37 is a synthetic peptide corresponding to the only known human cathelicidin antimicrobial peptide. It consists of 37 amino acids beginning with two leucine residues, hence the designation “LL-37.” Naturally, LL-37 is produced from the precursor protein hCAP-18 through proteolytic cleavage and is found in epithelial tissues and circulating immune cells. Research interest in LL-37 centers on its potential antimicrobial, immunomodulatory, and tissue-regenerative properties in experimental models.

Overview
LL-37 has been studied for its broad antimicrobial spectrum, with reported activity against Gram-positive and Gram-negative bacteria, fungi, and certain enveloped viruses in preclinical research. Beyond direct antimicrobial effects, LL-37 appears to influence host cell biology by modulating inflammation, promoting chemotaxis, and regulating immune responses.

Experimental data suggest that LL-37 may act on multiple cellular targets, including toll-like receptors, chemokine receptors, and formyl peptide receptors. This signaling activity has been associated with effects on wound closure, angiogenesis, and epithelial barrier function. The peptide also appears to interact with lipopolysaccharides, potentially reducing pro-inflammatory signaling from bacterial endotoxins.

Due to its pleiotropic roles, LL-37 is being studied in contexts such as infection control, tissue repair, and immune regulation.

Chemical Makeup

• Molecular Formula: C189H322N52O49
• Molecular Weight: 4493.3 g/mol
• Sequence: LLGDFFRKSKEKIGKEFKRIVQRIKDFLRNLVPRTES
• Other Known Titles: Human cathelicidin antimicrobial peptide, hCAP-18-derived LL-37

Research and Clinical Studies

Antimicrobial Properties
LL-37 has demonstrated antimicrobial activity in vitro against bacteria including Escherichia coli, Staphylococcus aureus, and Pseudomonas aeruginosa. Studies suggest the peptide disrupts microbial membranes through pore formation and membrane destabilization.

Immunomodulation
In experimental models, LL-37 has been shown to regulate cytokine production, suppress excessive pro-inflammatory responses, and recruit immune cells such as neutrophils, monocytes, and T lymphocytes. This dual antimicrobial–immunomodulatory role has led to interest in LL-37 as a host-defense peptide.

Wound Healing and Angiogenesis
Preclinical wound models have indicated that LL-37 may enhance keratinocyte migration and angiogenesis, potentially accelerating tissue repair. Its influence on vascular endothelial growth factor (VEGF) expression has also been proposed as a mechanism for its angiogenic effects.

Respiratory and Epithelial Studies
LL-37 expression is upregulated in airway epithelia during infection, where it may serve as part of the innate immune defense. Laboratory studies suggest it can reduce bacterial load while supporting epithelial barrier function.

Bone and Connective Tissue
LL-37 has been evaluated in osteogenic models, with some studies reporting stimulation of mesenchymal stem cell differentiation and bone regeneration, suggesting possible roles beyond antimicrobial defense.

LL-37 peptide is available for research and laboratory purposes only. Not for human consumption.

References

1. Dürr UH, Sudheendra US, Ramamoorthy A. LL-37, the only human cathelicidin: structure, function, and applications. Biochim Biophys Acta. 2006;1758(9):1408–1425. https://pubmed.ncbi.nlm.nih.gov/16716248/
2. Vandamme D, et al. A comprehensive summary of LL-37 and its derived peptides. Cell Mol Life Sci. 2012;69(20): 3885–3908. https://pubmed.ncbi.nlm.nih.gov/22585085/
3. Nijnik A, Hancock RE. The roles of cathelicidin LL-37 in immune defences and novel clinical applications. Curr Opin Hematol. 2009;16(1):41–47. https://pubmed.ncbi.nlm.nih.gov/19057201/
4. Overhage J, et al. Human host defense peptide LL-37 prevents bacterial biofilm formation. Infect Immun. 2008;76(9):4176–4182. https://pubmed.ncbi.nlm.nih.gov/18591225/
5. Heilborn JD, et al. The cathelicidin peptide LL-37 is involved in re-epithelialization of human skin wounds and is lacking in chronic ulcers. J Invest Dermatol. 2003;120(3):379–389. https://pubmed.ncbi.nlm.nih.gov/12603845/
6. Barlow PG, et al. Antiviral activity and increased host defense response of LL-37 in influenza virus infection. J Immunol. 2011;186(10): 6166–6174. https://pubmed.ncbi.nlm.nih.gov/21460223/
7. Kahlenberg JM, Kaplan MJ. Little peptide, big effects: the role of LL-37 in inflammation and autoimmune disease. J Immunol. 2013;191(10):4895–4901. https://pubmed.ncbi.nlm.nih.gov/24163488/
8. Mookherjee N, et al. Modulation of the TLR-mediated inflammatory response by LL-37. J Immunol. 2006;176(4):2455–2464. https://pubmed.ncbi.nlm.nih.gov/16456005/
9. Krasnodembskaya A, et al. Human cathelicidin peptide LL-37 promotes mesenchymal stem cell–mediated immunomodulation and tissue repair. Proc Natl Acad Sci U S A. 2010;107(32):14292–14297. https://pubmed.ncbi.nlm.nih.gov/20660729/
10. Ramos R, et al. Wound healing activity of LL-37 peptide. Peptides. 2011;32(9):1849–1858. https://pubmed.ncbi.nlm.nih.gov/21763365/