Microglial NOX2 as a therapeutic target in traumatic brain injury: Mechanisms, consequences, and potential for neuroprotection

Abstract

Traumatic brain injury (TBI) is a leading cause of long-term disability worldwide, with secondary injury mechanisms, including neuroinflammation and oxidative stress, driving much of its chronic pathology. While NADPH oxidase 2 (NOX2)-mediated reactive oxygen species (ROS) production is a recognized factor in TBI, the specific role of microglial NOX2 in perpetuating oxidative and inflammatory damage remains underexplored. Addressing this gap is critical, as current therapeutic approaches primarily target acute symptoms and fail to interrupt the persistent neuroinflammation that contributes to progressive neurodegeneration. Besides NOX, other ROS-generating enzymes, such as CYP1B1, COX2, and XO, also play crucial roles in triggering oxidative stress and neuroinflammatory conditions in TBI. However, this review highlights the pathophysiological role of microglial NOX2 in TBI, focusing on its activation following injury and its impact on ROS generation, neuroinflammatory signaling, and neuronal loss. These insights reveal NOX2 as a critical driver of secondary injury, linked to worsened outcomes, particularly in aged individuals where NOX2 activation is more pronounced. In addition, this review evaluates emerging therapeutic approaches targeting NOX2, such as GSK2795039 and other selective NOX2 inhibitors, which show potential in reducing ROS levels, limiting neuroinflammation, and preserving neurological functions. By highlighting the specific role of NOX2 in microglial ROS production and secondary neurodegeneration, this study advocates for NOX2 inhibition as a promising strategy to improve TBI outcomes by addressing the unmet need for therapies targeting long-term inflammation and neuroprotection. Our review highlights the potential of NOX2-targeted interventions to disrupt the cycle of oxidative stress and inflammation, ultimately offering a pathway to mitigate the chronic impact of TBI.