This is a 5.1kDa 45 amino acid antimicrobial peptide called β-defensin-3 (hBD-3), a β sheet with three intramolecular disulfide bonds. It is expressed in keratinocytes and tonsil tissues, but low in the respiratory tract, gastrointestinal tract and genital urothelium. The factors that induce its expression include TNFα, IL-1beta, and bacteria such as Pseudomonas aeruginosa and Staphylococcus aureus. hBD-3 may also be induced after exposure to IFNγ. Compared with hBD-1, -2 and -4, hBD-3 shows insensitive anti-salt and anti-bacterial activity to several pathogenic microorganisms at physiological salt concentration. This makes hBD-3 unique and particularly relevant in other diseases where hBD is inactive. Compared with hBD-1(+4) and hBD-2(+6), hBD-3 can stimulate its antibacterial activity more effectively at lower concentrations due to its amphiphilic dimer structure and front surface Due to the increase in charge (+9). hBD-3 can induce human keratinocytes to produce cytokines and stimulate monocyte migration
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