Defensin beta 4B (DEFB4B)

Defensin beta 4B (DEFB4B), often referred to as beta-defensin 2 (BD-2 or hBD-2), is a cysteine-rich, cationic antimicrobial peptide that is part of the beta-defensin family. It is mainly produced by epithelial cells at barrier sites such as the skin, airways, and gastrointestinal tract in response to microbial products and proinflammatory cytokines. DEFB4B plays a dual role: it has direct antimicrobial activity against a broad spectrum of pathogens (Gram-negative and Gram-positive bacteria, Candida albicans), and it modulates immune responses by recruiting and activating immune cells via binding to the CCR6 receptor. It is quickly induced during infection and inflammation, and its expression level correlates with disease severity in certain inflammatory conditions like psoriasis. DEFB4B also contributes to maintenance of mucosal integrity and wound healing. Its antimicrobial activity is salt-sensitive and relies on disulfide-stabilized structure. Dysregulation or overexpression is linked to pathology in chronic inflammatory diseases and impaired barrier function.

Other names

Defensin beta 4ADEFB4ADEFB4DEFB102DEFB2BD-2hBD-2SAP1Beta-defensin 2Skin-antimicrobial peptide 1Defensin, beta 2Defensin, beta 4DEFB4PBeta-defensin 4BPseudogene

Antimicrobial activity (direct disruption of microbial membranes, especially via interaction with plasma membrane lipid phosphatidylinositol 4,5-bisphosphate in fungi); Immune cell recruitment (binds CCR6, induces chemotaxis of dendritic cells and T cells); Innate immune enhancement (induction/upregulation by bacterial products and cytokines during inflammation)