A recent review article published in the Journal of Clinical Investigation discusses the expanding roles of the cyclic GMP-AMP synthase (cGAS)–stimulator of interferon genes (STING) pathway in neuroinflammation.
Key Details
- The cGAS-STING pathway is a component of innate immunity that detects double-stranded DNA (dsDNA) and activates a type I interferon (IFN-I) response.
- Neuroinflammation is a feature of neurological diseases including Parkinson's disease, Alzheimer's disease, and Huntington's disease.
- The pathway regulates anti-tumor immunity, tumorigenesis, and neuroinflammation; its dysregulation is linked to brain aging and neurodegenerative diseases.
Mechanisms
- cGAS binds to dsDNA and synthesizes cGAMP, which activates STING and leads to IRF3-mediated IFN-I induction, as well as NF-κB activation and pro-inflammatory cytokine expression.
- The pathway also intersects with lysosomal pathways and autophagy.
- Nuclear cGAS interacts with histones and PARP1, influencing DNA damage repair and replication.
Effectors in the Central Nervous System
- Sustained cGAS-STING activation promotes astrocyte and microglia activation.
- STING is expressed in immune cells and neurons; neuronal STING may regulate axonal regeneration and excitability.
- cGAS-STING activation in brain endothelial cells can disrupt the blood-brain barrier, though effects may be context-dependent.
Therapeutic Potential
- Many neurodegenerative conditions generate cytosolic dsDNA (e.g., mitochondrial DNA) that can activate cGAS.
- Pharmacological inhibition of VDAC1 or mPTP reduces neurodegeneration in TDP-43 models.
- In models of AD, PD, and frontotemporal dementia, inhibiting cGAS-STING reduces inflammatory mediators.
- cGAS ablation in AD models enhances amyloid-β clearance via increased microglial recruitment.
Concluding Remarks
Sustained cGAS-STING activation in the CNS is associated with aging, neurodegeneration, and cognitive decline.
- Inhibition of cGAS or STING in preclinical models shows promise, but chronic inhibition may impair immune function.
- Partial, context-dependent, or CNS-selective modulation may be needed, with biomarkers for patient selection.