Targeting Signaling Pathway Downstream of RIG-I/MAVS in the CNS Stimulates Production of Endogenous Type I IFN and Suppresses EAE.

Type I interferons (IFN), including IFNß, play a protective role in multiple sclerosis (MS) and its animal model, experimental autoimmune encephalomyelitis (EAE). Type I IFNs are induced by the stimulation of innate signaling, including via cytoplasmic RIG-I-like receptors. In the present study, we investigated the potential effect of a chimeric protein containing the key domain of RIG-I signaling in the production of CNS endogenous IFNß and asked whether this would exert a therapeutic effect against EAE. We intrathecally administered an adeno-associated virus vector (AAV) encoding a fusion protein comprising RIG-I 2CARD domains (C) and the first 200 amino acids of mitochondrial antiviral-signaling protein (MAVS) (M) (AAV-CM). In vivo imaging in IFNß/luciferase reporter mice revealed that a single intrathecal injection of AAV-CM resulted in dose-dependent and sustained IFNß expression within the CNS. IFNß expression was significantly increased for 7 days. Immunofluorescent staining in IFNß-YFP reporter mice revealed extraparenchymal CD45+ cells, choroid plexus, and astrocytes as sources of IFNß. Moreover, intrathecal administration of AAV-CM at the onset of EAE induced the suppression of EAE, which was IFN-I-dependent. These findings suggest that accessing the signaling pathway downstream of RIG-I represents a promising therapeutic strategy for inflammatory CNS diseases, such as MS.

Cholinergic basal forebrain nucleus of Meynert regulates chronic pain-like behavior via modulation of the prelimbic cortex.

The basal nucleus of Meynert (NBM) subserves critically important functions in attention, arousal and cognition via its profound modulation of neocortical activity and is emerging as a key target in Alzheimer's and Parkinson's dementias. Despite the crucial role of neocortical domains in pain perception, however, the NBM has not been studied in models of chronic pain. Here, using in vivo tetrode recordings in behaving mice, we report that beta and gamma oscillatory activity is evoked in the NBM by noxious stimuli and is facilitated at peak inflammatory pain-like behavior. Optogenetic and chemogenetic cell-specific, reversible manipulations of NBM cholinergic-GABAergic neurons reveal their role in endogenous control of nociceptive hypersensitivity, which are manifest via projections to the prelimbic cortex, resulting in layer 5-mediated antinociception. Our data unravel the importance of the NBM in top-down control of neocortical processing of pain-like behavior.