Pharmacological cGAS-STING pathway inhibition on neuroinflammation in animal models of traumatic brain injury: A systematic review and meta-analysis protocol

Background: Traumatic brain injury (TBI) is a major cause of mortality and long-term neurological disability worldwide. Secondary injury mechanisms, particularly neuroinflammation, play a key role in determining neurological outcomes after the initial trauma. The cyclic GMP-AMP synthase stimulator of interferon genes (cGAS-STING) pathway has recently been identified as a mediator of innate immune activation following brain injury. Activation of this pathway promotes microglial activation and the release of pro-inflammatory cytokines, contributing to neuronal damage and impaired recovery. Pharmacological inhibition of the cGAS-STING signaling pathway has therefore emerged as a promising neuroprotective strategy in experimental TBI models. However, the available preclinical evidence has not yet been systematically synthesized. Methods: A systematic literature search was performed across MEDLINE, EMBASE and Web of Science without language or publication date restrictions. Titles and abstracts were screened independently by two reviewers, followed by independent full-text eligibility assessment. Data extraction was initiated subsequently and will be completed independently by two reviewers. Eligible studies will include in vivo animal models of TBI investigating direct or indirect pharmacological inhibition of the cGAS-STING pathway administered after injury, compared with vehicle-treated or untreated controls. The primary outcome will be quantitative measures of microglial activation within the first 72 hours post-injury, preferentially assessed using Iba1-positive cell density or percentage-stained area. Secondary outcomes will include astrocytic reactivity, cytokine expression (TNF-α, IL-1β, IL-6), lesion volume and neurological functional recovery. Risk of bias will be assessed using the SYRCLE tool. When appropriate, pooled effect sizes will be calculated using random-effects meta-analysis. Heterogeneity, publication bias and certainty of evidence will also be evaluated. Discussion: This systematic review and meta-analysis will help clarify the magnitude and consistency of therapeutic effects and inform the translational potential of this strategy while identifying methodological limitations that may guide future experimental and clinical research. Systematic review registration: PROSPERO CRD420261367166.