Granulocyte- Macrophage Colony-Stimulating Factor Reverses Immunosuppression Acutely Following a Traumatic Brain Injury and Hemorrhage Polytrauma in a Juvenile Male Rat Model.

Traumatic brain injury (TBI) is a common cause of morbidity and mortality in children. We have previously shown that TBI with a concurrent extracranial injury reliably leads to post-injury suppression of the innate and adaptive immune systems. In patients with post-injury immune suppression, if immune function could be preserved, this might represent a therapeutic opportunity. As such, we examined, in an animal injury model, whether systemic administration of granulocyte macrophage colony-stimulating factor (GM-CSF) could reverse post-injury immune suppression and whether treatment was associated with neuroinflammation or functional deficit. Prepubescent male rats were injured using a controlled cortical impact model and then subjected to removal of 25% blood volume (TBI/H). Sham animals underwent surgery without injury induction, and the treatment groups were sham and injured animals treated with either saline vehicle or 50 µg/kg GM-CSF. GM-CSF was administered following injury and then daily until sacrifice at post-injury day (PID) 7. Immune function was measured by assessing tumor necrosis factor-α (TNF-α) levels in whole blood and spleen following ex vivo stimulation with pokeweed mitogen (PWM). Brain samples were assessed by multiplex enzyme-linked immunosorbent assay (ELISA) for cytokine levels and by immunohistochemistry for microglia and astrocyte proliferation. Neuronal cell count was examined using cresyl violet staining. Motor coordination was evaluated using the Rotarod performance test. Treatment with GM-CSF was associated with a significantly increased response to PWM in both whole blood and spleen. GM-CSF in injured animals did not lead to increases in levels of pro-inflammatory cytokines in brain samples but was associated with significant increases in counted astrocytes. Finally, while injured animals treated with saline showed a significant impairment on behavioral testing, injured animals treated with GM-CSF performed similarly to uninjured animals. GM-CSF treatment in animals with combined injury led to increased systemic immune cell response in whole blood and spleen in the acute phase following injury. Improved immune response was not associated with elevated pro-inflammatory cytokine levels in the brain or functional impairment.

Association of initial assessment variables and mortality in severe pediatric traumatic brain injury.

Background: Predictive scales have been used to prognosticate long-term outcomes of traumatic brain injury (TBI), but gaps remain in predicting mortality using initial trauma resuscitation data. We sought to evaluate the association of clinical variables collected during the initial resuscitation of intubated pediatric severe patients with TBI with in-hospital mortality. Methods: Intubated pediatric trauma patients <18 years with severe TBI (Glasgow coma scale (GCS) score ≤8) from January 2011 to December 2020 were included. Associations between initial trauma resuscitation variables (temperature, pulse, mean arterial blood pressure, GCS score, hemoglobin, international normalized ratio (INR), platelet count, oxygen saturation, end tidal carbon dioxide, blood glucose and pupillary response) and mortality were evaluated with multivariable logistic regression. Results: Among 314 patients, median age was 5.5 years (interquartile range (IQR): 2.2-12.8), GCS score was 3 (IQR: 3-6), Head Abbreviated Injury Score (hAIS) was 4 (IQR: 3-5), and most had a severe (25-49) Injury Severity Score (ISS) (48.7%, 153/314). Overall mortality was 26.8%. GCS score, hAIS, ISS, INR, platelet count, and blood glucose were associated with in-hospital mortality (all p<0.05). As age and GCS score increased, the odds of mortality decreased. Each 1-point increase in GCS score was associated with a 35% decrease in odds of mortality. As hAIS, INR, and blood glucose increased, the odds of mortality increased. With each 1.0 unit increase in INR, the odds of mortality increased by 1427%. Conclusions: Pediatric patients with severe TBI are at substantial risk for in-hospital mortality. Studies are needed to examine whether earlier interventions targeting specific parameters of INR and blood glucose impact mortality.

Recommendations for reproducibility of cerebrospinal fluid extracellular vesicle studies.

Cerebrospinal fluid (CSF) is a clear, transparent fluid derived from blood plasma that protects the brain and spinal cord against mechanical shock, provides buoyancy, clears metabolic waste and transports extracellular components to remote sites in the brain. Given its contact with the brain and the spinal cord, CSF is the most informative biofluid for studies of the central nervous system (CNS). In addition to other components, CSF contains extracellular vesicles (EVs) that carry bioactive cargoes (e.g., lipids, nucleic acids, proteins), and that can have biological functions within and beyond the CNS. Thus, CSF EVs likely serve as both mediators of and contributors to communication in the CNS. Accordingly, their potential as biomarkers for CNS diseases has stimulated much excitement for and attention to CSF EV research. However, studies on CSF EVs present unique challenges relative to EV studies in other biofluids, including the invasive nature of CSF collection, limited CSF volumes and the low numbers of EVs in CSF as compared to plasma. Here, the objectives of the International Society for Extracellular Vesicles CSF Task Force are to promote the reproducibility of CSF EV studies by providing current reporting and best practices, and recommendations and reporting guidelines, for CSF EV studies. To accomplish this, we created and distributed a world-wide survey to ISEV members to assess methods considered 'best practices' for CSF EVs, then performed a detailed literature review for CSF EV publications that was used to curate methods and resources. Based on responses to the survey and curated information from publications, the CSF Task Force herein provides recommendations and reporting guidelines to promote the reproducibility of CSF EV studies in seven domains: (i) CSF Collection, Processing, and Storage; (ii) CSF EV Separation/Concentration; (iii) CSF EV Size and Number Measurements; (iv) CSF EV Protein Studies; (v) CSF EV RNA Studies; (vi) CSF EV Omics Studies and (vii) CSF EV Functional Studies.