Human Beta-Defensin 2
Inducible epithelial antimicrobial peptide with potent activity against gram-negative bacteria and chemotactic properties for immune cells.
Chemical Identity
| Property | Value |
|---|---|
| Gene | DEFB4A |
| Molecular Weight | ~4.3 kDa |
| Amino Acids | 41 (mature peptide) |
| Peptide Class | Beta-Defensin |
| Disulfide Bonds | 3 |
Structure
Human beta-defensin 2 (hBD-2) is a 41-amino acid cationic peptide with six cysteine residues forming three intramolecular disulfide bonds characteristic of beta-defensins. Unlike constitutively expressed hBD-1, hBD-2 is strongly induced by microbial products, inflammatory cytokines, and Toll-like receptor activation.
Mechanism of Action
hBD-2 disrupts microbial membranes through electrostatic interaction with anionic phospholipids, forming pores that cause cell lysis. It also binds CCR6 on dendritic cells and memory T cells, serving as a chemoattractant to bridge innate and adaptive immunity. Activity is enhanced at low salt concentrations.
Clinical Applications
- Mucosal defense: Strongly induced at sites of infection and inflammation
- Skin defense: Upregulated in psoriasis and wound healing
- Respiratory defense: Expressed in airway epithelium
- Gut defense: Induced by commensal and pathogenic bacteria
- Therapeutic potential: Recombinant hBD-2 for resistant infections
Pharmacology
- Spectrum: Broad, especially potent against gram-negative bacteria
- Induction: TLR2, TLR4, IL-1beta, TNF-alpha
- Salt sensitivity: Activity reduced in high-salt environments
- Candida activity: Active against C. albicans
References
- Harder, J., et al. (1997). hBD-2: a novel antimicrobial peptide from skin. Nature, 387, 861.
- O’Neil, D.A., et al. (1999). Expression and function of hBD-2 in intestinal epithelium. Journal of Immunology, 162, 6502-6510.
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