LL-37 (5mg)

LL-37 (5 mg)

LL-37 is the only known human cathelicidin-derived antimicrobial peptide. It is generated from the C-terminal region of the precursor protein hCAP18 and consists of 37 amino acids beginning with two leucine residues (“LL”). LL-37 is a cationic, amphipathic host defense peptide with a broad portfolio of experimental actions:

• Direct antimicrobial activity (bacteria, fungi, some viruses)

• Immunomodulation and chemotaxis

• Promotion of wound healing and angiogenesis

• Regulation of apoptosis and cellular stress responses PubMed+2ScienceDirect+2

Because of its pleiotropic effects, LL-37 is widely used as a tool peptide in studies of innate immunity, epithelial biology, tissue repair, and inflammatory disease.

Specifications

• Synonyms: LL-37, hCAP18-derived peptide, human cathelicidin, CAMP peptide

• Length: 37 amino acids; net charge +6 at physiological pH MDPI

• Class: Cationic antimicrobial / host defense peptide (HDP)

• Biophysical properties:

  • Amphipathic α-helical structure in membrane-mimicking environments

  • Strong affinity for negatively charged microbial membranes and LPS/LTA ScienceDirect+1

Mechanism of Action and Antimicrobial Activity

LL-37 exerts direct antimicrobial effects primarily via:

• Electrostatic interaction with negatively charged bacterial surfaces (LPS, LTA)

• Insertion into lipid bilayers, forming discrete membrane lesions and pores

• Membrane permeabilization, leading to rapid disruption of microbial integrity and death ScienceDirect+2ASM Journals+2

It displays activity against Gram-positive and Gram-negative bacteria, some fungi, and enveloped viruses, making it a model peptide for innate immune defenses. PubMed+1

Immunomodulation and Innate Immune Signaling

Beyond direct killing, LL-37 is a potent immunomodulatory peptide:

• Acts as a chemotactic factor for neutrophils, monocytes, and T cells via receptors such as FPRL1 (FPR2) and P2X7 PMC+1

• Forms complexes with nucleic acids that can alter innate immune sensing (e.g., TLR pathways) and influence antiviral responses Cell+1

• Modulates cytokine production (both pro- and anti-inflammatory) in epithelial and immune cells, depending on context PMC+1

These properties are highly relevant to experimental models of autoimmunity, chronic inflammation, and host–pathogen interactions.

Wound Healing, Angiogenesis, and Tissue Repair

LL-37 has been repeatedly shown to support tissue repair processes:

• Angiogenesis: LL-37 stimulates endothelial cell proliferation, migration, and formation of capillary-like structures, driving angiogenesis in vitro and in vivo. Junior Chamber International+1

• Epithelial wound closure: It accelerates wound healing of airway and cutaneous epithelium by enhancing cell migration and proliferation. The Journals of Physiology+1

• Apoptosis modulation: LL-37 can protect certain host cells (e.g., keratinocytes) from apoptosis, while selectively permeabilizing and clearing apoptotic leukocytes in a manner analogous to its antimicrobial activity. JID Online+2ASM Journals+2

These data make LL-37 a valuable model peptide for studying the interface between host defense, angiogenesis, and tissue regeneration.

LL-37 in Inflammation, Autoimmunity, and Viral Research

Review articles highlight that LL-37 is involved in multiple inflammatory and immune settings:

• Dysregulated LL-37 responses have been linked to autoimmune and inflammatory diseases, including psoriasis and lupus, where LL-37–nucleic acid complexes may aberrantly activate innate receptors. PMC+1

• In viral research, LL-37 is explored as a host defense peptide with potential roles in respiratory viral infections, including SARS-CoV-2, due to its membrane-active and immunomodulatory characteristics. Frontiers+1

These effects are complex and context-dependent, reinforcing LL-37 as a research probe, not a therapeutic agent.

Other Experimental Applications

• Cancer biology: LL-37 has been studied for its dual roles in tumor promotion or suppression, depending on tissue and microenvironment. PubMed+1

• Biomaterials and coatings: Used to functionalize surfaces with antimicrobial and pro-healing properties.

• Systems immunology: Model peptide for studying host defense peptide networks and cationic peptide–membrane interactions.

Research Use Only – Important Notice

This LL-37 (5 mg) product is supplied strictly for laboratory research use:

• Not for human or veterinary use

• Not for diagnostic, therapeutic, or cosmetic applications

• Intended solely for in vitro assays and/or controlled experimental animal models by qualified personnel

• All descriptions provided summarize findings from experimental and preclinical research and must not be interpreted as medical advice or claims of clinical efficacy

References – LL-37

1. Vandamme D et al. A comprehensive summary of LL-37, the factotum human cathelicidin peptide. Peptides.
   https://pubmed.ncbi.nlm.nih.gov/23246832/ PubMed

2. Voronko OE et al. Antimicrobial peptides of the cathelicidin family: focus on structure–function. Int J Mol Sci.
   https://www.mdpi.com/1422-0067/26/16/8103 MDPI

3. Koczulla R et al. An angiogenic role for the human peptide antibiotic LL-37/cathelicidin. J Clin Invest.
   https://www.jci.org/articles/view/17545 Junior Chamber International

4. Shaykhiev R et al. Human endogenous antibiotic LL-37 stimulates airway epithelial wound closure. Am J Physiol Lung Cell Mol Physiol.
   https://journals.physiology.org/doi/full/10.1152/ajplung.00286.2004 The Journals of Physiology

5. Chamorro CI et al. The human antimicrobial peptide LL-37 suppresses apoptosis in keratinocytes. J Invest Dermatol.
   https://www.jidonline.org/article/S0022-202X%2815%2934292-5/fulltext JID Online

6. Pahar B et al. Immunomodulatory role of the antimicrobial LL-37 peptide in autoimmune and inflammatory diseases. Int J Mol Sci.
   https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7565865/ PMC

7. Aloul KM et al. Upregulating human cathelicidin LL-37 in the context of SARS-CoV-2 infection. Front Immunol.
   https://www.frontiersin.org/articles/10.3389/fimmu.2022.880961/full Frontiers

8. Xhindoli D et al. The human cathelicidin LL-37 – a pore-forming antibacterial peptide and host defense mediator. Biochim Biophys Acta.
   https://www.sciencedirect.com/science/article/pii/S0005273615003685 ScienceDirect

9. Seil M et al. Spotlight on human LL-37, an immunomodulatory peptide. (review of signaling and apoptosis effects).
   https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4034075/ PMC

10. Zielke C et al. Complexation of the human cathelicidin LL-37 with nucleic acids and innate immune stimulation. Biophys J.
    https://www.cell.com/biophysj/fulltext/S0006-3495%2823%2900671-9 Cell