HBDs play a pivotal role in the immune response of the gastrointestinal epithelium to Hp-infection, directly influencing and activating the adaptive immune system being modulators in infections, as Hp. Hp infection leads to a significant induction of HBD2, HBD3, and HBD4 while HBD-1, the constitutive expressed β-defensins, is much less pronounced. The gene discussed is HP; the disease is infection.