Sequential Modulation of the cGAS-STING Pathway Promotes Spinal Cord Injury Repair

Background Spinal cord injury (SCI) is a devastating condition with limited treatment options, where dysregulated neuroinflammation critically impedes repair. The cGAS-STING pathway, a central cytosolic DNA-sensing axis of innate immunity, is implicated in neuroinflammatory disorders, yet its precise spatiotemporal role and therapeutic potential in SCI remain undefined. Given the complex, phase-specific nature of post-SCI immune responses, we hypothesized that a time-dependent modulation of this pathway, rather than continuous intervention, could optimally coordinate inflammation for repair. Methods Using a mouse model of thoracic compressive SCI, we assessed pathway activation via transcriptomics, western blot, and immunofluorescence. Motor recovery was evaluated longitudinally using the Basso Mouse Scale (BMS) and footprint analysis. Pharmacological agonists and antagonists of STING were administered either continuously or in a sequential regimen. Histological and ultrastructural analyses evaluated axonal regeneration, myelination, and glial scarring. RNA sequencing elucidated molecular mechanisms. Microglia-specific depletion using PLX5622 and in vitro neuron-microglia co-cultures were employed to determine cellular mechanisms. Results The cGAS-STING pathway was significantly activated post-SCI, primarily within microglia. Continuous pathway activation or inhibition failed to improve recovery. In contrast, sequential treatment (early agonist, late antagonist) significantly enhanced functional recovery, axonal regeneration, and remyelination while limiting glial scarring. Mechanistically, upregulated genes associated with microglial phagocytosis and chemotaxis, promoting debris clearance. Subsequent inhibition relieved inflammation, elevated anti-inflammatory cytokine and pro-regenerative programs. Microglial depletion completely abolished the therapeutic benefits of the sequential strategy, confirming their role as essential effector cells. Conclusion This study establishes the critical importance of timing in targeting the cGAS-STING pathway after SCI. We demonstrate that a phase-specific strategy that sequentially activates then inhibits this pathway optimally harnesses microglial functions for repair, offering a novel precision medicine approach for SCI.