Nucleic acid sensing in the central nervous system: Implications for neural circuit development, function, and degeneration.

Nucleic acids are a critical trigger for the innate immune response to infection, wherein pathogen-derived RNA and DNA are sensed by nucleic acid sensing receptors. This subsequently drives the production of type I interferon and other inflammatory cytokines to combat infection. While the system is designed such that these receptors should specifically recognize pathogen-derived nucleic acids, it is now clear that self-derived RNA and DNA can also stimulate these receptors to cause aberrant inflammation and autoimmune disease. Intriguingly, similar pathways are now emerging in the central nervous system in neurons and glial cells. As in the periphery, these signaling pathways are active in neurons and glia to present the spread of pathogens in the CNS. They further appear to be active even under steady conditions to regulate neuronal development and function, and they can become activated aberrantly during disease to propagate neuroinflammation and neurodegeneration. Here, we review the emerging new roles for nucleic acid sensing mechanisms in the CNS and raise open questions that we are poised to explore in the future.