Development of a Mouse Model to Investigate the Role of ZBP1 in Neuroinflammation

About This Grant

ABSTRACT. Traumatic brain injury (TBI) is a major cause of mortality and long-term disability, characterized by complex neurobiological changes. Neuroinflammation, primarily mediated by microglia, is a central component of TBI pathology. While acute microglial activation supports tissue repair, chronic activation significantly contributes to secondary neuronal injury through sustained release of cytokines and reactive oxygen species. In moderate to severe TBI, damage-associated molecular patterns (DAMPs) molecules released from injured tissue initiate early microglial activation by binding to the surface receptors. However, the mechanisms that sustain microglial activation during the post-acute phase—when DAMPs generation decline—remain unclear. Similarly, in mild TBI, neuroinflammation occurs despite limited cell death or significant DAMPs release during both acute and post-acute phases, suggesting alternative microglia activation pathways. Our published and preliminary data support a novel mechanism for microglial activation involving neuronal mitochondrial DNA (mtDNA). We found that mild TBI induces neuronal mtDNA damage and its release via extracellular vesicles (EVs). These neuron-derived EVs activate microglia through mtDNA binding to the cytosolic DNA/RNA sensor Z-DNA binding protein 1 (ZBP1), triggering inflammatory and oxidative responses. Activated microglia, in turn, exacerbate neuronal mtDNA damage, promoting further release. We propose that this establishes a positive feedback loop that sustains microglial activation through the neuronal mtDNA–ZBP1 axis explaining microglial activation in moderate to severe chronic TBI phase and persistent inflammation in acute and chronic mild TBI phases. To directly test this mechanism, we will generate an inducible mouse model in which expression of a ZBP1 variant lacking its nucleic acid (NA) binding domains (Zα1 and Zα2) is controlled by tamoxifen, using a Cre-loxP system with tamoxifen-inducible Cre (CreER) activity in microglia. This model will allow precise, temporal dissection of the role of ZBP1’s NA-binding domains in microglial activation during both acute and chronic phases of TBI. Furthermore, this model will serve as a valuable tool for investigating the role of ZBP1’s NA-binding domains in neuroinflammation beyond TBI, including in neurodegenerative diseases (e.g., Alzheimer’s, Parkinson’s) and infectious conditions (e.g., Zika virus). Our long-term goal is to establish ZBP1 as a therapeutic target for mitigating neuroinflammation, making the development of this mouse model a critical step toward that aim.