What is LL-37?
LL-37 is a human antimicrobial peptide (AMP) belonging to the cathelicidin family. It is the only cathelicidin found in humans and plays crucial roles in innate immunity, wound healing, and immune modulation. Named for its 37-amino acid length beginning with two leucines, LL-37 is produced by neutrophils, epithelial cells, and other immune cells.
Beyond its antimicrobial properties, LL-37 has attracted research interest for its immunomodulatory effects, wound healing properties, and potential applications in various inflammatory and infectious conditions.
Natural Function
Antimicrobial Activity
LL-37 has broad-spectrum antimicrobial effects:
Active Against:
- Gram-positive bacteria
- Gram-negative bacteria
- Fungi
- Some viruses
- Biofilms
Mechanism:
- Disrupts microbial membranes
- Creates pores in cell walls
- Neutralizes endotoxins (LPS)
Immunomodulation
Beyond direct killing:
- Chemotactic for immune cells
- Modulates cytokine production
- Regulates inflammation
- Promotes wound healing
Molecular Profile
Sequence
LLGDFFRKSKEKIGKEFKRIVQRIKDFLRNLVPRTES
Molecular Data
| Property | Value |
|---|---|
| Molecular Weight | ~4493 Da |
| Amino Acids | 37 |
| Charge | +6 at neutral pH |
| Structure | α-helical in membranes |
Research Applications
Wound Healing
LL-37 promotes healing through:
- Keratinocyte migration
- Angiogenesis stimulation
- Anti-biofilm activity
- Inflammation modulation
Infectious Disease
Research explores:
- Antibiotic-resistant infections
- Biofilm-related infections
- Sepsis models
- Respiratory infections
Inflammatory Conditions
Studies in:
- Psoriasis (elevated LL-37)
- Rosacea (elevated LL-37)
- Various inflammatory states
Summary
LL-37 represents an important component of human innate immunity with diverse functions beyond simple antimicrobial activity, making it a significant research target.
Key Points:
- Classification: Human cathelicidin antimicrobial peptide
- Functions: Antimicrobial, immunomodulatory, wound healing
- Research: Infectious disease, wound healing, inflammation