DEFB124 (defensin beta 124) is an antimicrobial peptide with critical roles in innate immunity. Primary Function: DEFB124 exhibits antibacterial activity and functions as an immune signaling molecule in epithelial tissues 1. Mechanism: DEFB124 expression is induced through NF-κB signaling pathway activation in response to bacterial pathogen-associated molecular patterns, particularly peptidoglycan 1. Upon upregulation, DEFB124 enhances production of pro-inflammatory cytokines (IL-6, IL-12) and chemokines (CCL5, CCL22, CXCL8), promoting immune cell recruitment and activation 1. DEFB124 expression is negatively regulated by NLRX1, a pattern recognition receptor that suppresses NF-κB signaling during bacterial infection 2. Disease Relevance: DEFB124 expression increases significantly during enterohemorrhagic E. coli infection, contributing to anti-microbial host defense 2. Environmental exposure to polychlorinated biphenyls (PCBs) during pregnancy is associated with altered DEFB124 gene expression in newborns, suggesting environmental factors may dysregulate immune defense mechanisms 3. Clinical Significance: DEFB124-mediated innate immune responses may be critical for protection against bacterial infections, while dysregulation could compromise epithelial immune defense.