Toll-like receptor and nuclear factor kappa B signaling pathway (TLR/NF-κB)

The Toll-like receptor (TLR) and nuclear factor kappa B (NF-κB) signaling pathway is a central axis of the innate immune system responsible for detecting pathogen-associated molecular patterns (PAMPs) and damage-associated molecular patterns (DAMPs) [1.1.1, 1.1.3]. Upon ligand binding, TLRs undergo dimerization and recruit adaptor proteins like MyD88 or TRIF, which initiate a downstream kinase cascade involving IRAK4, IRAK1, and TRAF6 [1.1.2, 1.2.4]. This cascade culminates in the activation of the IκB kinase (IKK) complex, which phosphorylates IκB proteins, marking them for proteasomal degradation and allowing the transcription factor NF-κB to translocate into the nucleus [1.2.2, 1.2.4]. Once in the nucleus, NF-κB promotes the expression of pro-inflammatory cytokines and survival factors that orchestrate the immune response [1.2.1, 1.2.5]. Dysregulation of this pathway is implicated in a wide range of pathologies, including chronic inflammatory diseases, autoimmune disorders, and various cancers where constitutive NF-κB activation drives tumor growth and chemoresistance [1.1.1, 1.1.4]. Therapeutic strategies include TLR agonists used as vaccine adjuvants or cancer immunotherapies, and inhibitors of TLRs, IRAK4, or the IKK complex to treat inflammatory and autoimmune conditions [1.1.1, 1.1.4].

Other names

TLR signaling pathwayTLR-NF-κB axisInnate immune signaling pathwayToll-like receptors and NF-κB signaling components

Drugs targeting this pathway act by either stimulating Toll-like receptors (agonists) to enhance innate and adaptive immune responses against pathogens or tumors, or by inhibiting receptors, adaptors (e.g., MyD88), or downstream kinases (e.g., IRAK4, IKK) to suppress pathological inflammation and autoimmunity [1.1.1, 1.1.4].