Nucleic acid-sensing Toll-like receptors (TLR3, TLR7, TLR8, TLR9) (NA-TLRs)

Nucleic acid-sensing Toll-like receptors (TLRs), specifically TLR3, TLR7, TLR8, and TLR9, are endosomal receptors that play a pivotal role in the innate immune system by detecting foreign genetic material. TLR3 recognizes double-stranded RNA, TLR7 and TLR8 detect single-stranded RNA, and TLR9 identifies unmethylated CpG DNA motifs [Source: UniProt]. Upon activation, these receptors initiate signaling pathways that result in the production of type I interferons and other pro-inflammatory cytokines, which are essential for antiviral and antibacterial defense. However, the inappropriate recognition of self-nucleic acids by these receptors is strongly linked to the pathogenesis of autoimmune disorders like systemic lupus erythematosus and psoriasis [Source: PubMed, PMID: 30108117]. Therapeutic interventions often focus on blocking these pathways, either through direct receptor antagonism or via ligand sequestration. Ligand sequestration involves specialized molecules, such as cationic polymers or antibodies, that bind to and neutralize the nucleic acid ligands before they can trigger the receptors [Source: PNAS, doi:10.1073/pnas.1109096108]. This approach aims to reduce the inflammatory burden in chronic conditions without completely compromising the immune system's ability to respond to other threats. Drugs like hydroxychloroquine have long been used to modulate these pathways, while newer, more specific inhibitors are currently in clinical development.

Other names

Endosomal Toll-like receptorsNucleic acid-sensing TLRsTLR3/7/8/9

Inhibition of receptor activation through ligand sequestration (binding and neutralizing DNA/RNA) or direct competitive antagonism of the endosomal receptor binding sites [Source: Nature Reviews Immunology, doi:10.1038/nri.2017.115].