DEFB1 and cystic fibrosis: In fact, human beta defensin-1 (hBD-1) is unable to inhibit P. aeruginosa due to a 120 mM concentration of NaCl in the lungs of cystic fibrosis patients [94]; while β-defensin-3 (hBD-3) shows antibacterial activity also at high salt concentrations [54,55].