AZU1 (azurocidin 1) is a neutrophil granule-derived glycoprotein with diverse roles in innate immunity and disease pathogenesis. As an antimicrobial protein, AZU1 demonstrates selective activity against Gram-negative bacteria, particularly Pseudomonas aeruginosa, through its basic N-terminal domain's affinity for lipopolysaccharides 1. Beyond its canonical antibacterial function, AZU1 serves as a chemotactic mediator recruiting monocytes and fibroblasts during inflammatory responses and mediates cell migration through heparin binding. Recent studies reveal AZU1's broader pathophysiological significance. In acute mountain sickness, elevated AZU1 expression correlates with disease severity through neutrophil extracellular trap formation 2. In high-altitude pulmonary edema, DNA methylation-driven AZU1 upregulation promotes oxidative stress via p38/MAPK signaling in endothelial cells 3. Conversely, AZU1 exhibits tumor-suppressive effects in triple-negative breast cancer, inducing pyroptosis through the NF-κB/NLRP3/caspase-1 pathway 4. AZU1 expression appears dysregulated in inflammatory bowel disease, showing increased levels in Crohn's disease ileal tissue 5, and mediates depression-related phenotypes through plasma protein and metabolite pathways when exposed to bisphenol S 6. DPP-1 inhibition substantially reduces circulating AZU1 levels, identifying it as a sensitive biomarker of neutrophil protease modulation 7. These findings establish AZU1 as a multifunctional protein with context-dependent protective or pathogenic roles across infectious, inflammatory, and malignant diseases.