cGAS-STING as a Neuroimmune Traffic Molecule: Unraveling Pathogenic Mechanisms and Therapeutic Potential in Neurological Disorders.

The cyclic GMP-AMP synthase-stimulator of interferon genes (cGAS-STING) pathway is an essential cytosolic DNA-sensing system that plays an important role in the regulation of innate immune and inflammatory responses in the central nervous system (CNS). It was first discovered as a promising antiviral defense cascade and has since been shown to execute broader functions in neuroinflammation and neurodegeneration. The pathway can become hyperactive with the release of endogenous DNA from damaged nuclei, mitochondria, or genomic instability, leading to chronic production of type I interferon (TI-IFN), various pro-inflammatory cytokines, and eventually contributing to chronic neuroinflammatory diseases. Recent studies have found that dysregulated cGAS-STING signaling is associated with several neurological disorders, such as Alzheimer's disease (AD), Parkinson's disease (PD), Huntington's disease (HD), amyotrophic lateral sclerosis (ALS), traumatic brain injury (TBI), stroke, and age-related neurodegeneration. In the CNS, chronic activation of this pathway leads to activation of microglia, oxidative stress, breakdown of the blood-brain barrier (BBB), impaired function of the synapses, and neuronal death. Mitochondrial dysfunction and cytosolic release of mitochondrial DNA (mtDNA) further promote inflammatory signaling, thus perpetuating neurodegeneration. This review highlights the molecular and pathological mechanisms of cGAS-STING signaling in a broader aspect of neurological disorders and appraises the novel therapeutics already under development to inhibit this pathway to regulate neuroinflammation and enhance neurological outcomes.