DEFB103B (defensin beta 103B) encodes an antimicrobial peptide belonging to the beta-defensin family. Functionally, DEFB103B contributes to innate immunity through antimicrobial and immunomodulatory mechanisms. The gene is upregulated in response to various bacterial challenges and microbial stimuli. In periodontal immunity, Akkermansia muciniphila enhances DEFB103B expression in gingival epithelial cells through the TLR-MYD88-NF-κB pathway, strengthening mucosal defense against Porphyromonas gingivalis 1. DEFB103B also plays a critical role in intracellular host-pathogen interactions; CRISPR knockout studies revealed that DEFB103B loss diminishes Brucella intracellular survival by altering host cell autophagy 2. In wound healing, microbial extracts induce DEFB103B expression in keratinocytes, contributing to antimicrobial protection and skin repair 3. Genetically, DEFB103B has been identified in genome-wide association studies for bone ultrasound parameters, with associations to broadband ultrasound attenuation in male-specific analysis 4. Additionally, DEFB103B ligand interactions have been identified in pituitary neuroendocrine tumors, where stromal expression participates in stroma-to-stroma signaling via chemokine receptors 5. Collectively, DEFB103B functions as a multifaceted antimicrobial peptide with roles in mucosal immunity, autophagy regulation, wound healing, and tumor microenvironment interactions.