Defensin beta 4A

Also known as: Beta-defensin 2, Defensin, beta 2, Skin-antimicrobial peptide 1, DEFB4A, DEFB4B, O15263

Defensin beta 4A (DEFB4A), also known as beta-defensin 2, is an antimicrobial peptide primarily expressed in epithelial tissues, particularly the skin and respiratory tract. Its mechanism of action involves disrupting microbial cell membranes through electrostatic interactions, leading to pore formation and cell lysis. It exhibits broad-spectrum antimicrobial activity, with highest potency against Gram-negative bacteria, though it is also effective against Gram-positive bacteria and some fungi. Additionally, DEFB4A functions as a chemoattractant for immune cells, linking innate and adaptive immunity. Key research findings indicate that DEFB4A expression is upregulated in response to inflammatory stimuli, such as bacterial lipopolysaccharides and cytokines like TNF-α and IL-1β. Studies have demonstrated its role in wound healing and mucosal defense, with reduced expression associated with increased susceptibility to infections in conditions like atopic dermatitis and cystic fibrosis. Experimental models also suggest potential involvement in cancer modulation, though data remain preliminary. Clinically, DEFB4A is being investigated as a biomarker for inflammatory and infectious diseases, as well as a template for novel antimicrobial therapies. Its selective activity against pathogens and low propensity for inducing resistance make it a candidate for topical or systemic applications. However, its therapeutic use remains experimental, with no approved indications. For research purposes only — not medical advice.

Key data

Mechanism of action

Exhibits antimicrobial activity against Gram-negative bacteria and Gram-positive bacteria, with highest activity against Gram-negative bacteria (PubMed:10837369, PubMed:9202117). Antimicrobial activity against P.aeruginosa seems to be salt-sensitive and is reduced with high salt concentrations greater than 25 mM (PubMed:10837369). Also exhibits antimicrobial activity against the yeast C.albicans (PubMed:10837369, PubMed:30050988, PubMed:9202117). Permeabilizes C.albicans cell membranes via targeting plasma membrane lipid phosphatidylinositol 4,5-bisphosphate (PIP2), thereby leading to cell fragmentation and cell death (PubMed:30050988). Acts as a ligand for C-C chemokine receptor CCR6 (PubMed:10521347, PubMed:20068036). Binds to CCR6 and induces chemotactic activity of CCR6-expressing cells, such as immature dendritic cells and memory T cells (PubMed:10521347, PubMed:20068036)

Research & studies

Frequently asked questions

Related peptides