Researchers explore the role of astrocytes in mediating damage sustained during blast injuries.
While there are ongoing efforts to reduce exposure to and increase reporting of blast events across the Services, military blast exposure remains a prevalent concern for Service members in the training and operational environments, as these exposures can have a long-lasting impact on the Service member by increasing risk for neurobehavioral sequelae, cognitive deficits, and chronic traumatic encephalopathy (CTE). In a recent publication1, researchers investigated astrogliosis, or defense-mediated changes to the brain cell's structure and function in response to injury, in blast and impact neurotrauma, focusing on repetitive head injury (RHI) and CTE.
Researchers compared the brain tissue from several groups including (1) former military veterans with a history of blast exposure, with and without CTE; (2) former American football players with a history of RHI with and without a neuropathological diagnosis of CTE; and (3) controls with no history of blast, RHI exposure, or CTE diagnosis. The human brain tissue was sourced from donor samples acquired from the Veteran Affairs Boston Healthcare System, the National Posttraumatic Stress Disorder brain bank, and the "Understanding Neurologic Injury and Traumatic Encephalopathy (UNITE)" study at the Veteran's Affairs-Boston University-Concussion Legacy Foundation brain bank. The cohorts were determined by the type of neurotrauma exposure and the presence or absence of CTE (through neuropathological diagnosis). The researchers leveraged quantitative immunofluorescence to identify areas of the brain that indicate astrocytic activity from neurotrauma and compared the three groups. The results showed higher levels of glial fibrillary acidic protein (GFAP) located in at the cortical grey-white matter junction of those who experienced impact and blast neurotrauma. Generally, if there is an increase in GFAP, this indicates some astrocytic activation that could indicate neural damage within the central nervous system.
Based on the study findings, researchers suggest that astrogliosis at the grey-white matter interface (i.e., dorsolateral frontal cortex) may result from the localization of shearing forces during blast neurotrauma, caused by the rapid acceleration and deceleration of the head. Neurotrauma alone might cause astrocytes to alter their GFAP expression in a region-dependent manner. Further study on the impact of blast neurotrauma in this part of the brain would be beneficial to determine whether the region is more susceptible to injury and responsible for long-term health effects in Service members. The researchers also suggested that future research might explore the clinical utility of astrocyte-focused biomarkers.
1 Babcock, K.J., Abdolmohammadi, B., Kiernan, P.T., Mahar, I., Cherry, J.D., Alvarez, V.E., Goldstein, L.E., Stein, T.D., McKee, A.C., & Huber, B.R. (2022). Interface Astrogliosis in Contact Sport Head Impacts and Military Blast Exposure. Acta Neuropathologica Communications. doi: 10.1186/s40478-022-01358-z
This work was funded by the following grants: National Institute of Neurological Disorders and Stroke (U54NS115266), National Institute of Aging (U19AG068753), National Institute of Aging Boston University AD Research Center (P30AG013846), Department of Veterans Affairs, Veterans Health Administration, Clinical Sciences Research and Development Merit Award (I01-CX001038), Department of Veterans Affairs, Veterans Health Administration, Biomedical Laboratory Research and Development Merit Award (hai).
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