LL-37
unknown riskAlso: Cathelicidin · CAMP peptide · hCAP-18 fragment
LL-37 is the only human cathelicidin antimicrobial peptide. It is part of the innate immune system's first line of defense against pathogens, with broad-spectrum antimicrobial activity and significant immunomodulatory properties.
Reported Benefits
Antimicrobial
Broad-spectrum activity against bacteria, fungi, viruses, and parasites demonstrated in vitro.
Wound Healing
Promotes keratinocyte migration, angiogenesis, and reduces biofilm formation.
Immune Modulation
Modulates TLR signaling, recruits immune cells, and regulates inflammation.
Mechanism of Action
LL-37 exerts antimicrobial effects by disrupting bacterial and fungal membranes through amphipathic alpha-helical structure — it inserts into lipid bilayers and creates pores or carpet-mechanism disruption. Immunomodulatory effects are mediated through FPR2, EGFR, and P2Y11 receptor interactions.
Key Clinical Studies
Krauson AJ et al. (2015)
laboratory · In vitro
Mechanism of membrane disruption and selectivity for bacterial membranes
Vandamme D et al. (2012)
review · Review
Comprehensive antimicrobial and immunomodulatory profile
Overview
LL-37 holds a unique position as the only human cathelicidin — a class of antimicrobial peptides that form a critical part of innate immunity. Unlike exogenous antimicrobials, LL-37 represents a component of the body’s own defense system, with activity that extends beyond simple pathogen killing.
Antimicrobial Breadth
The antimicrobial spectrum of LL-37 is remarkably broad: gram-positive bacteria, gram-negative bacteria, fungi, enveloped viruses, and even some parasites. Critically, it is active against multi-drug resistant organisms and disrupts biofilms — a major limitation of conventional antibiotics.
Dual Role: Defense and Damage Control
LL-37 simultaneously kills pathogens and modulates the host immune response. It recruits neutrophils and macrophages, activates dendritic cells, and regulates TLR4 signaling to prevent excessive inflammation. This dual role makes it conceptually attractive as a wound healing and infection control agent.
Deficiency in Disease
Low LL-37 expression is associated with atopic dermatitis (explaining the increased skin infection risk), and deficiency of cathelicidins is linked to increased susceptibility to various bacterial infections. Conversely, excess LL-37 is observed in psoriasis and lupus, suggesting a complex regulatory role.
Regulatory Status
Research OnlyNot FDA-approved; research-only status
Safety Profile
Side Effects
- •Potential cytotoxicity at high concentrations
- •Pro-inflammatory effects at high doses
Contraindications
- •Active cancer (immunostimulatory effects)
Drug Interactions
- •Antibiotics (synergistic in some combinations)
Primary Uses
Related Peptides
Weekly Briefing
Regulatory updates + new study breakdowns.
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