Beta-Defensin-2 (hBD-2)

Human beta-defensin-2 (hBD-2) is an inducible antimicrobial peptide produced by epithelial cells throughout the body, particularly in skin, respiratory tract, and gastrointestinal epithelium. Unlike constitutively expressed hBD-1, hBD-2 is strongly upregulated in response to infection, inflammation, and epithelial injury.

The 41-amino acid peptide contains six cysteine residues forming three disulfide bonds in the characteristic beta-defensin pattern, distinct from the alpha-defensin connectivity. This fold creates a cationic, amphipathic structure capable of membrane disruption against gram-positive and gram-negative bacteria, fungi, and some viruses.

Beyond direct antimicrobial activity, hBD-2 functions as a chemokine, attracting immature dendritic cells and memory T cells through CCR6 receptor activation. This links the innate epithelial defense to adaptive immunity, making hBD-2 a key mediator at the interface between immediate antimicrobial protection and organized immune responses.

Research has revealed hBD-2's involvement in inflammatory skin conditions including psoriasis, where dramatically elevated expression contributes to both antimicrobial resistance and chronic inflammation. Understanding hBD-2 regulation and function has implications for treating skin infections, inflammatory diseases, and potentially developing novel antimicrobial or immunomodulatory therapeutics.