Toll-like receptor 2, 3, 4, 7, and 9 (TLR2/3/4/7/9)

TLR2/3/4/7/9 refers to a specific subset of the Toll-like receptor (TLR) family, which are essential pattern recognition receptors (PRRs) that mediate the innate immune response. This group encompasses both cell-surface receptors, such as TLR2 and TLR4, and endosomal receptors, including TLR3, TLR7, and TLR9, which collectively detect a broad spectrum of pathogen-associated molecular patterns (PAMPs) like lipoproteins, lipopolysaccharides, and microbial nucleic acids [1, 3, 5]. Upon activation, these receptors initiate intracellular signaling cascades primarily through the MyD88 and TRIF adapter proteins, leading to the activation of NF-κB and IRF transcription factors and the subsequent production of pro-inflammatory cytokines and type I interferons [1, 17]. In clinical contexts, these receptors are targeted for their roles in diverse pathologies; for instance, their overactivation is linked to autoimmune diseases like systemic lupus erythematosus and chronic inflammatory conditions like osteoarthritis, while their controlled stimulation is utilized in cancer immunotherapy and as vaccine adjuvants [2, 14, 15]. Therapeutic agents include agonists like imiquimod (TLR7) and CpG ODNs (TLR9) to enhance immune surveillance, as well as antagonists like hydroxychloroquine (TLR7/9) and TAK-242 (TLR4) to mitigate excessive inflammation [4, 5, 8]. Because this entry represents a collection of distinct proteins rather than a single molecular entity, it is classified as an incorrect canonical target form for structured databases.

Other names

TLR2TLR3TLR4TLR7TLR9Toll-like receptorsTLR family subset

Agonism of individual or multiple TLRs to stimulate innate and adaptive immune responses; Antagonism to inhibit pathological pro-inflammatory signaling.