Helicobacter pylorivirulence factors: subversion of host immune system and development of various clinical outcomes

Abstract

AbstractHelicobacter pylori(H. pylori) is a worldwide spread bacterium, co-evolving with humans for at least 100 000 years. Despite the uncertainty about the mode ofH. pyloritransmission, the development of intra-gastric and extra-gastric diseases is attributed to this bacterium. The morphological transformation and production of heterogenic virulence factors enableH. pylorito overcome the harsh stomach environment. Using numerous potent disease-associated virulence factors makesH. pyloria prominent pathogenic bacterium. These bacterial determinants are adhesins (e.g., blood group antigen-binding adhesin (BabA)/sialic acid-binding adhesin (SabA)), enzymes (e.g., urease), toxins (e.g., vacuolating cytotoxin A (VacA)), and effector proteins (e.g., cytotoxin-associated gene A (CagA)) involved in colonisation, immune evasion, and disease induction.H. pylorinot only cleverly evades the immune system but also robustly induces immune responses. This insidious bacterium employs various strategies to evade human innate and adaptive immune responses, leading to a life-long infection. Owing to the alteration of surface molecules, innate immune receptors couldn't recognise this bacterium; moreover, modulation of effector T cells subverts adaptive immune response. Most of the infected humans are asymptomatic and only a few of them present severe clinical outcomes. Therefore, the identification of virulence factors will pave the way for the prediction of infection severity and the development of an effective vaccine.H. pylorivirulence factors are hereby comprehensively reviewed and the bacterium evasion from the immune response is properly discussed.