Glaucocalyxin A Promotes Spinal Cord Repair By Nrf2/HO-1 Pathway Activation to Suppress AIM2 Inflammasome Formation

Spinal cord injury (SCI) is a debilitating neurological disorder that frequently results in severe motor, sensory, and autonomic dysfunction, often leading to permanent disability. However, due to the complexity of its pathophysiologic mechanisms, therapeutic options for SCI remain limited. In this study, we focus on Glaucocalyxin A (GLA), a bioactive diterpenoid compound derived from Lamiaceae plants, which exhibits remarkable anti-inflammatory and antioxidant properties and shows promising potential as a therapeutic candidate for SCI. This study aims to elucidate the mechanism by which GLA exerts its neuroprotective effects, namely by activating the Nrf2/HO-1 pathway to alleviate oxidative stress, thereby inhibiting absent in melanoma 2 (AIM2) inflammasome-mediated neuronal pyroptosis. This study employed network pharmacology and molecular docking to predict the therapeutic potential and mechanism of GLA in SCI. To validate these predictions, we established a rat SCI model to evaluate GLA's therapeutic effects. In vitro experiments were also conducted using lipopolysaccharide-stimulated PC12 cells to investigate GLA's neuroprotective effects against oxidative stress parameters, inflammasome activation, and pyroptosis markers. GLA demonstrated significant neuroprotective effects in SCI, as evidenced by improved locomotor recovery, attenuated tissue damage, and enhanced axonal regeneration in SCI model rats. Mechanistic studies revealed that GLA treatment potently activated the Nrf2/HO-1 signaling axis, leading to enhanced cellular antioxidant defenses and reduced reactive oxygen species accumulation in both in vivo and in vitro models. Concurrently, GLA effectively suppressed neuroinflammatory responses by inhibiting AIM2 inflammasome assembly, consequently reducing caspase-1 activation, gasdermin D-dependent pyroptosis, and interleukin-1β maturation in injured neurons. This study demonstrates that GLA exerts neuroprotective effects by activating the Nrf2/HO-1 antioxidant pathway and inhibiting AIM2 inflammasome-mediated pyroptosis. These findings suggest that GLA is a candidate drug with multi-target therapeutic potential, likely possessing clinical value for the treatment of SCI.