Role of TLRs and other innate receptors in adaptive immunity
TLRs in collaboration with other innate receptors such as RLRs and NLRs play an important role in innate responses as well as shaping adaptive immunity. RLRs and NLRs are cytoplasmic PRRs that sense various ligands in the Ganetespib and induce appropriate immune responses. Upon RNA virus infection, viral ss- or dsRNAs are generated in the cytoplasm and are recognized by RLRs including RIG-I and MDA5 (melanoma-differentiation associated gene 5) [2], [17], [18] and [27]. The RLRs activate IRFs via IFNβ promoter stimulator-1 (IPS-1), resulting in the production of type I interferons. NLRs recognize a wide range of ligands including bacteria, fungi, DNA or RNA viruses and endogenous ligands, and induce the IL-1 family of cytokines [28] and [29].
Future perspectives
TLRs are the most extensively studied innate receptors and their roles in innate and adaptive immunity are well documented. However, some questions still need to be addressed, including how our immune system responds to various bacterial, viral, fungal and protozoal infections in association with other known and unknown innate receptors. Furthermore, it is unknown whether TLRs and other innate receptors such as RLRs and NLRs are sufficient to defend against various infections. Future studies or identification of new families of innate receptors and their signaling pathways will help us to more clearly understand the host–pathogen interactions.