Flagellin: A crucial virulence factor coordinating bacterial pathogenesis and host immune responses

Flagella serve as the motility organs of bacteria, possessing not only the capability to facilitate movement through mechanisms such as rotation and swinging but also playing a crucial role in the establishment of bacterial infections. Flagellin, the primary functional subunit of flagellar filaments, is recognized as a classic virulence factor. It plays a critical role in various life processes of pathogenic bacteria, including adhesion, invasion, and biofilm formation. Additionally, flagellin regulates the secretion of pro-inflammatory factors and contributes to immune evasion by pathogens, acting as a significant molecular bridge in the interaction between pathogens and hosts. Elucidating its pivotal function within the infection-immune regulatory network is vital for comprehending both pathogenicity and immune mechanisms associated with bacteria. This paper reviews the roles and effects of flagella at the interface between hosts and bacteria, aiming to provide a comprehensive understanding of their contributions to bacterial virulence and their significance in immunology.