Innate immune RNA sensors (RNA Sensors)

Innate immune RNA sensors are a diverse group of pattern recognition receptors (PRRs) that detect foreign or damage-associated RNA, serving as a vital link between innate detection and the activation of the adaptive immune system. This group includes endosomal receptors such as Toll-like receptors 3, 7, and 8 (TLR3, TLR7, TLR8), which recognize double-stranded and single-stranded RNA, as well as cytosolic sensors like Retinoic acid-inducible gene I (RIG-I) and Melanoma differentiation-associated protein 5 (MDA5) [1][2]. Activation of these sensors triggers signaling cascades that culminate in the production of Type I interferons and pro-inflammatory cytokines, which are essential for the maturation of professional antigen-presenting cells (APCs) like dendritic cells [3]. These matured APCs then upregulate MHC molecules and co-stimulatory signals to effectively present antigens to T cells, thereby initiating a targeted adaptive response [4]. In clinical practice, agonists of these sensors are utilized as potent vaccine adjuvants and in cancer immunotherapy to stimulate anti-tumor T-cell activity, though their over-activation can lead to severe systemic inflammation or autoimmune pathologies [2][5].

Other names

Pattern recognition receptors (PRRs)Nucleic acid sensorsEndosomal RNA sensorsCytosolic RNA sensorsRNA-sensing pathway

Agonism of endosomal (TLR3, TLR7, TLR8) or cytosolic (RIG-I, MDA5) sensors to trigger downstream signaling (TRIF, MyD88, MAVS), leading to the expression of Type I interferons and pro-inflammatory cytokines that facilitate antigen processing and presentation by dendritic cells to T cells.