Salmonella Typhimurium flagellin (FliC)

Salmonella Typhimurium flagellin is the primary structural protein of the bacterial flagellum, existing in two phase-variable forms known as FliC and FljB (UniProt P06179). It serves as a potent pathogen-associated molecular pattern (PAMP) that is specifically recognized by the host's Toll-like receptor 5 (TLR5), a key component of the innate immune system (Hayashi et al., 2001, Nature). Upon binding to TLR5, flagellin triggers the MyD88-dependent activation of the NF-κB signaling pathway, which induces the expression of pro-inflammatory cytokines and provides cytoprotective signals. In drug development, flagellin derivatives such as Entolimod (CBLB502) are being investigated for their ability to protect healthy tissues from ionizing radiation and to stimulate anti-tumor immune responses in oncology (Cleveland BioLabs). Additionally, flagellin is widely utilized as a vaccine adjuvant to enhance the immunogenicity of recombinant antigens by promoting dendritic cell maturation and T-cell activation. However, its clinical application is carefully managed due to the risk of inducing excessive systemic inflammation or neutralizing immune responses against the protein itself.

Other names

FliCFljBH antigenBacterial flagellinTLR5 ligand

Agonism of Toll-like receptor 5 (TLR5) leading to NF-κB activation and induction of pro-inflammatory and anti-apoptotic pathways.