Abstract 2149 Cell-specific differential gene expression analysis by snRNA-seq after repetitive weaponry-type blast-induced traumatic brain injury

Military personnel who specialize in the use of heavy weaponry such as artillery, 0.50-caliber rounds, and breaching devices have returned from training and active service with neurological symptoms including cognitive impairment, memory loss, attention deficits, mood changes, irritability, and sleep disturbances due to repeated exposure to low-level blast waves. Service members who sustain repetitive weaponry-type blast-induced TBI (rwbTBI) do not display overt pathological symptoms immediately but rather develop these mild symptoms over time after incurring repeated damage. We are interested in understanding the impact of rwbTBI on neuronal health and identifying underlying injury mechanisms and therapeutic targets to improve cognitive outcomes for Veterans and others. We hypothesize that the cumulative neurotrauma in individuals with rwbTBI results in the upregulation of neuroinflammatory and other detrimental genes and insufficient expression of neuroprotective genes. Furthermore, we investigated whether modulation of neuroprotective and antioxidant transcription factors can help combat neuroinflammatory responses and neuronal loss following rwbTBI by influencing gene expression profiles of cell populations within the hippocampus, a critical region involved in memory and cognition. Here, male C57BL/6J mice received five 70 kPa blast exposures at 1-min intervals in a well-established shock tube system to model occupational use of heavy weaponry followed by treatment with tert-butylhydroquinone (tBHQ), a Nrf2 activator, and pioglitazone, a PPARγ agonist, at 30 minutes post-injury. Single nucleus RNA sequencing (snRNA-seq) was performed using nuclei isolated from mouse hippocampal tissue at 24 hours post-injury to assess gene expression changes by cell type in response to injury and/or treatment. Preliminary analysis identified differential expression of genes of interest including upregulation of Nfe2l2, the gene that encodes Nrf2, in dentate granule cells and upregulation of Pparg in astrocytes due to injury. We also conducted gene ontology and pathway analysis to identify functional profiles in various cell types after injury and/or treatment. This study provides insight into potential mechanisms that underlie cell-specific neuropathological changes following repetitive weaponry-type blast exposure and provides a foundation for the identification of therapeutic targets that could be modulated to improve the health of Veterans and others with histories of occupational blast exposures. Supported by the Department of Veterans Affairs (Veterans Health Administration, Office of Research and Development, BLR&D I01BX005015 (BAC), I01BX004561 (KDB), I01RX001520 (BAC), IK2RX003253 (VD)), and the Veterans Bio-Medical Research Institute. Dr. Citron is the recipient of a Research Career Scientist award (IK6BX006188) from the Department of Veterans Affairs.