Pathophysiology of traumatic brain injury

AI-Based Decision Support System for Traumatic Brain Injury: A Survey

Traumatic brain injury (TBI) is one of the major causes of disability and mortality worldwide. Rapid and precise clinical assessment and decision-making are essential to improve the outcome and the resulting complications. Due to the size and complexity of the data analyzed in TBI cases, computer-aided data processing, analysis, and decision support systems could play an important role. However, developing such systems is challenging due to the heterogeneity of symptoms, varying data quality caused by different spatio-temporal resolutions, and the inherent noise associated with image and signal acquisition. The purpose of this article is to review current advances in developing artificial intelligence-based decision support systems for the diagnosis, severity assessment, and long-term prognosis of TBI complications.

Perfusion Imaging of Traumatic Brain Injury

The mechanisms for regulating cerebral blood flow (CBF) are highly sensitive to traumatic brain injury (TBI). The perfusion imaging technique may be used to assess CBF and identify perfusion abnormalities following a TBI. Studies have identified CBF disturbances across the injury severity spectrum and correlations with both acute and long-term indices of clinical outcome. Although not yet widely used in the clinical context, this is an important area of ongoing research.

Associations between psychological resilience and metrics of white matter microstructure in pediatric concussion

This study investigated associations between psychological resilience and characteristics of white matter microstructure in pediatric concussion. This is a case control study and a planned substudy of a larger randomized controlled trial. Children with an acute concussion or orthopedic injury were recruited from the emergency department. Participants completed both the Connor-Davidson Resilience Scale 10 and an MRI at 72 h and 4-weeks post-injury. The association between resiliency and fractional anisotropy (FA), mean diffusivity (MD), axial diffusivity (AD), and radial diffusivity (RD) at both timepoints were examined. We examined whether these associations were moderated by group. The association between resiliency captured at 72 h and diffusion tensor imaging metrics at 4 weeks was also investigated. Clusters were extracted using a significance threshold of threshold-free cluster enhancement corrected p < .05. A total of 66 children with concussion (median (IQR) age = 12.88 (IQR: 11.80-14.36); 47% female) and 29 children with orthopedic-injury (median (IQR) age = 12.49 (IQR: 11.18-14.01); 41% female) were included. A negative correlation was identified in the concussion group between 72 h resilience and 72 h FA. Meanwhile, positive correlations were identified in the concussion group with concussion between 72 h resilience and both 72 h MD and 72 h RD. These findings suggest that 72 h resilience is associated with white matter microstructure of the forceps minor, superior longitudinal fasciculus, and anterior thalamic radiation at 72 h post-concussion. Resilience seems to be associated with neural integrity only in the acute phase of concussion and thus may be considered when researching concussion recovery.

Inflammation and immunomodulation in central nervous system injury - B cells as a novel therapeutic opportunity

Acute injury to the central nervous system (CNS) remains a complex and challenging clinical need. CNS injury initiates a dynamic neuroinflammatory response, mediated by both resident and infiltrating immune cells. Following the primary injury, dysregulated inflammatory cascades have been implicated in sustaining a pro-inflammatory microenvironment, driving secondary neurodegeneration and the development of lasting neurological dysfunction. Due to the multifaceted nature of CNS injury, clinically effective therapies for conditions such as traumatic brain injury (TBI), spinal cord injury (SCI), and stroke have proven challenging to develop. No therapeutics that adequately address the chronic inflammatory component of secondary CNS injury are currently available. Recently, B lymphocytes have gained increasing appreciation for their role in maintaining immune homeostasis and regulating inflammatory responses in the context of tissue injury. Here we review the neuroinflammatory response to CNS injury with particular focus on the underexplored role of B cells and summarize recent results on the use of purified B lymphocytes as a novel immunomodulatory therapeutic for tissue injury, particularly in the CNS.

VCE-005.1, an hypoxia mimetic betulinic acid derivative, induces angiogenesis and shows efficacy in a murine model of traumatic brain injury

One of the main global causes of mortality and morbidity is traumatic brain injury (TBI). Neuroinflammation and brain-blood barrier (BBB) disruption play a pivotal role in the pathogenesis of acute and chronic TBI onset. The activation of the hypoxia pathway is a promising approach for CNS neurodegenerative diseases, including TBI. Herein, we have studied the efficacy of VCE-005.1, a betulinic acid hydroxamate, against acute neuroinflammation in vitro and on a TBI mouse model. The effect of VCE-005.1 on the HIF pathway in endothelial vascular cells was assessed by western blot, gene expression, in vitro angiogenesis, confocal analysis and MTT assays. In vivo angiogenesis was evaluated through a Matrigel plug model and a mouse model of TBI induced by a controlled cortical impact (CCI) was used to assess VCE-005.1 efficacy. VCE-005.1 stabilized HIF-1α through a mechanism that involved AMPK and stimulated the expression of HIF-dependent genes. VCE-005.1 protected vascular endothelial cells under prooxidant and pro-inflammatory conditions by enhancing TJ protein expression and induced angiogenesis both in vitro and in vivo. Furthermore, in CCI model, VCE-005.1 greatly improved locomotor coordination, increased neovascularization and preserved BBB integrity that paralleled with a large reduction of peripheral immune cells infiltration, recovering AMPK expression and reducing apoptosis in neuronal cells. Taken together, our results demonstrate that VCE-005.1 is a multitarget compound that shows anti-inflammatory and neuroprotective effects mainly by preventing BBB disruption and has the potential to be further developed pharmacologically in TBI and maybe other neurological conditions that concur with neuroinflammation and BBB disruption.

Increased Risk of Aging-Related Neurodegenerative Disease after Traumatic Brain Injury

Traumatic brain injury (TBI) survivors frequently suffer from chronically progressive complications, including significantly increased risk of developing aging-related neurodegenerative disease. As advances in neurocritical care increase the number of TBI survivors, the impact and awareness of this problem are growing. The mechanisms by which TBI increases the risk of developing aging-related neurodegenerative disease, however, are not completely understood. As a result, there are no protective treatments for patients. Here, we review the current literature surrounding the epidemiology and potential mechanistic relationships between brain injury and aging-related neurodegenerative disease. In addition to increasing the risk for developing all forms of dementia, the most prominent aging-related neurodegenerative conditions that are accelerated by TBI are amyotrophic lateral sclerosis (ALS), frontotemporal dementia (FTD), Parkinson's disease (PD), and Alzheimer's disease (AD), with ALS and FTD being the least well-established. Mechanistic links between TBI and all forms of dementia that are reviewed include oxidative stress, dysregulated proteostasis, and neuroinflammation. Disease-specific mechanistic links with TBI that are reviewed include TAR DNA binding protein 43 and motor cortex lesions in ALS and FTD; alpha-synuclein, dopaminergic cell death, and synergistic toxin exposure in PD; and brain insulin resistance, amyloid beta pathology, and tau pathology in AD. While compelling mechanistic links have been identified, significantly expanded investigation in the field is needed to develop therapies to protect TBI survivors from the increased risk of aging-related neurodegenerative disease.

Drosophila melanogaster as a model to study age and sex differences in brain injury and neurodegeneration after mild head trauma

Repetitive physical insults to the head, including those that elicit mild traumatic brain injury (mTBI), are a known risk factor for a variety of neurodegenerative conditions including Alzheimer's disease (AD), Parkinson's disease (PD), and chronic traumatic encephalopathy (CTE). Although most individuals who sustain mTBI typically achieve a seemingly full recovery within a few weeks, a subset experience delayed-onset symptoms later in life. As most mTBI research has focused on the acute phase of injury, there is an incomplete understanding of mechanisms related to the late-life emergence of neurodegeneration after early exposure to mild head trauma. The recent adoption of Drosophila-based brain injury models provides several unique advantages over existing preclinical animal models, including a tractable framework amenable to high-throughput assays and short relative lifespan conducive to lifelong mechanistic investigation. The use of flies also provides an opportunity to investigate important risk factors associated with neurodegenerative conditions, specifically age and sex. In this review, we survey current literature that examines age and sex as contributing factors to head trauma-mediated neurodegeneration in humans and preclinical models, including mammalian and Drosophila models. We discuss similarities and disparities between human and fly in aging, sex differences, and pathophysiology. Finally, we highlight Drosophila as an effective tool for investigating mechanisms underlying head trauma-induced neurodegeneration and for identifying therapeutic targets for treatment and recovery.

[A pilot study on the effects of early use of valproate sodium on neuroinflammation after traumatic brain injury]

OBJECTIVES

To study the effect of early use of sodium valproate on neuroinflammation after traumatic brain injury (TBI).

METHODS

A total of 45 children who visited in Xuzhou Children's Hospital Affiliated to Xuzhou Medical University from August 2021 to August 2022 were enrolled in this prospective study, among whom 15 healthy children served as the healthy control group, and 30 children with TBI were divided into a sodium valproate treatment group and a conventional treatment group using a random number table (n=15 each). The children in the sodium valproate treatment group were given sodium valproate in addition to conventional treatment, and those in the conventional group were given an equal volume of 5% glucose solution in addition to conventional treatment. The serum concentrations of nucleotide-binding oligomerization domain-like receptor protein 3(NLRP3), high-mobility group box 1 (HMGB1), tumor necrosis factor-α (TNF-α), and interleukin-1β (IL-1β) were measured in the healthy control group on the day of physical examination and in the children with TBI on days 1, 3, and 5 after admission. Glasgow Outcome Scale-Extended (GOS-E) score was evaluated for the children with TBI 2 months after discharge.

RESULTS

Compared with the healthy control group, the children with TBI had significantly higher serum concentrations of NLRP3, HMGB1, TNF-α, and IL-1β on day 1 after admission (P<0.017). The concentration of NLRP3 on day 5 after admission was significantly higher than that on days 1 and 3 after admission in the children with TBI (P<0.017). On days 3 and 5 after admission, the sodium valproate treatment group had a significantly lower concentration of NLRP3 than the conventional treatment group (P<0.05). For the conventional treatment group, there was no significant difference in the concentration of HMGB1 on days 1, 3, and 5 after admission (P>0.017), while for the sodium valproate treatment group, the concentration of HMGB1 on day 5 after admission was significantly lower than that on days 1 and 3 after admission (P<0.017). On day 5 after admission, the sodium valproate treatment group had a significantly lower concentration of HMGB1 than the conventional treatment group (P<0.05). For the children with TBI, the concentration of TNF-α on day 1 after admission was significantly lower than that on days 3 and 5 after admission (P<0.017). On days 3 and 5 after admission, the sodium valproate treatment group had a significantly lower concentration of TNF-α than the conventional treatment group (P<0.05). The concentration of IL-1β on day 3 after admission was significantly lower than that on days 1 and 5 after admission (P<0.017) in the children with TBI. On days 3 and 5 after admission, the sodium valproate treatment group had a significantly lower concentration of IL-1β than the conventional treatment group (P<0.05). The GOS-E score was significantly higher in the sodium valproate treatment group than that in the conventional treatment group 2 months after discharge (P<0.05).

CONCLUSIONS

Early use of sodium valproate can reduce the release of neuroinflammatory factors and improve the prognosis of children with TBI.

Neutrophil to Lymphocyte Ratio as a Predictor of Postoperative Outcomes in Traumatic Brain Injury: A Systematic Review and Meta-Analysis

(1) Introduction: Traumatic brain injury (TBI) is a leading cause of injury and mortality worldwide, carrying an estimated cost of $38 billion in the United States alone. Neutrophil to lymphocyte ratio (NLR) has been investigated as a standardized biomarker that can be used to predict outcomes of TBI. The aim of this review was to determine the prognostic utility of NLR among patients admitted for TBI. (2) Methods: A literature search was conducted in PubMed, Scopus, and Web of Science in November 2022 to retrieve articles regarding the use of neutrophil to lymphocyte ratio (NLR) as a prognostic measure in traumatic brain injury (TBI) patients. Inclusion criteria included studies reporting outcomes of TBI patients with associated NLR values. Exclusion criteria were studies reporting only non-primary data, those insufficiently disaggregated to extract NLR data, and non-English or cadaveric studies. The Newcastle-Ottawa Scale was utilized to assess for the presence of bias in included studies. (3) Results: Following the final study selection 19 articles were included for quantitative and qualitative analysis. The average age was 46.25 years. Of the 7750 patients, 73% were male. Average GCS at presentation was 10.51. There was no significant difference in the NLR between surgical vs. non-surgical cohorts (SMD 2.41 95% CI −1.82 to 6.63, p = 0.264). There was no significant difference in the NLR between bleeding vs. non-bleeding cohorts (SMD 4.84 95% CI −0.26 to 9.93, p = 0.0627). There was a significant increase in the NLR between favorable vs. non-favorable cohorts (SMD 1.31 95% CI 0.33 to 2.29, p = 0.0090). (4) Conclusions: Our study found that NLR was only significantly predictive for adverse outcomes in TBI patients and not surgical treatment or intracranial hemorrhage, making it nonetheless an affordable alternative for physicians to assess patient prognosis.

Neuroprotective mechanisms of OXCT1 via the SIRT3-SOD2 pathway after traumatic brain injury

BACKGROUND

Ketones are not only utilized to produce energy but also play a neuroprotective role in many neurodegenerative diseases. However, whether this process has an impact on secondary brain damage after traumatic brain injury (TBI) remains unknown. OXCT1 (3-Oxoacid CoA-Transferase 1) is the rate-limiting enzyme in the intra-neuronal utilization of ketones. In this study, we investigated whether reduced expression of OXCT1 after TBI could impact neuroprotective mechanisms and exacerbate neurological dysfunction.

MATERIALS AND METHODS

Experimental TBI was induced by a modified version of the weight drop model, it is a model of severe head trauma. Expression of OXCT1 in the injured hippocampus of mice was measured at different time points using immunoblotting assays. The release of abnormal mitochondrial cytochrome c from neurons of the mouse injured lateral hippocampus was measured 1 week after TBI using immunoblotting assays. Neuronal death was assessed by Nissl staining and the level of reactive oxygen species (ROS) within the neurons of the injured lateral hippocampus was assessed by Dihydroethidium staining. Results OXCT1 was overexpressed in hippocampal neurons by injection of adeno-associated virus into the lateral ventricle. OXCT1 expression levels decreased significantly 1 week post-TBI. After comparing the data obtained from different groups of mice, OXCT1 was found to significantly increase the expression of SIRT3 and reduce the proportion of acetylated SOD2, thus decreasing the production of ROS in the injured hippocampal neurons, reducing neuronal death, and improving cognitive function. Conclusions OXCT1 has a critical previously unappreciated protective role in neurological impairment following TBI via the SIR3-SOD2 pathway. These findings highlight the potential of OXCT1 as a simple treatment for patients with TBI.

A Systematic Review of ASL Perfusion MRI in Mild TBI

Mild traumatic brain injury (mTBI) is a major public health concern. Cerebrovascular alterations play a significant role in the evolution of injury sequelae and in the process of post-traumatic brain repair. Arterial spin labeling (ASL) is an advanced perfusion magnetic resonance imaging technique that permits noninvasive quantification of cerebral blood flow (CBF). This is the first systematic review of ASL research findings in patients with mTBI. Our approach followed the American Academy of Neurology (AAN) and PRISMA guidelines. We searched Ovid/MEDLINE, Web of Science, Scopus, and the Cochrane Index for relevant articles published as of February 20, 2020. Full-text results were combined into Rayyan software for further evaluation. Data extraction, including risk of bias ratings, was performed using American Academy of Neurology's four-tiered classification scheme. Twenty-three articles met inclusion criteria comprising data on up to 566 mTBI patients and 654 control subjects. Of the 23 studies, 18 reported some type of regional CBF abnormality in mTBI patients at rest or during a cognitive task, with more findings of decreased than increased CBF. The evidence supports the conclusion that mTBI likely causes ASL-derived CBF anomalies. However, synthesis of findings was challenging due to substantial methodological variations across studies and few studies with low risk of bias. Thus, larger-scale prospective cohort studies are needed to more definitively chart the course of CBF changes in humans after mTBI and to understand how individual difference factors contribute to post-injury CBF changes.

Head Injury and Long-term Mortality Risk in Community-Dwelling Adults

Importance

Head injury is associated with significant short-term morbidity and mortality. Research regarding the implications of head injury for long-term survival in community-dwelling adults remains limited.

Objective

To evaluate the association of head injury with long-term all-cause mortality risk among community-dwelling adults, with consideration of head injury frequency and severity.

Design, Setting, and Participants

This cohort study included participants with and without head injury in the Atherosclerosis Risk in Communities (ARIC) study, an ongoing prospective cohort study with follow-up from 1987 through 2019 in 4 US communities in Minnesota, Maryland, North Carolina, and Mississippi. Of 15 792 ARIC participants initially enrolled, 1957 were ineligible due to self-reported head injury at baseline; 103 participants not of Black or White race and Black participants at the Minnesota and Maryland field centers were excluded due to race-site aliasing; and an additional 695 participants with missing head injury date or covariate data were excluded, resulting in 13 037 eligible participants.

Exposures

Head injury frequency and severity, as defined via self-report in response to interview questions and via hospital-based International Classification of Diseases diagnostic codes (with head injury severity defined in the subset of head injury cases identified using these codes). Head injury was analyzed as a time-varying exposure.

Main Outcomes and Measures

All-cause mortality was ascertained via linkage to the National Death Index. Data were analyzed between August 5, 2021, and October 23, 2022.

Results

More than one-half of participants were female (57.7%; 42.3% men), 27.9% were Black (72.1% White), and the median age at baseline was 54 years (IQR, 49-59 years). Median follow-up time was 27.0 years (IQR, 17.6-30.5 years). Head injuries occurred among 2402 participants (18.4%), most of which were classified as mild. The hazard ratio (HR) for all-cause mortality among individuals with head injury was 1.99 (95% CI, 1.88-2.11) compared with those with no head injury, with evidence of a dose-dependent association with head injury frequency (1 head injury: HR, 1.66 [95% CI, 1.56-1.77]; 2 or more head injuries: HR, 2.11 [95% CI, 1.89-2.37]) and severity (mild: HR, 2.16 [95% CI, 2.01-2.31]; moderate, severe, or penetrating: HR, 2.87 [95% CI, 2.55-3.22]). Estimates were similar by sex and race, with attenuated associations among individuals aged 54 years or older at baseline.

Conclusions and Relevance

In this community-based cohort with more than 3 decades of longitudinal follow-up, head injury was associated with decreased long-term survival time in a dose-dependent manner, underscoring the importance of measures aimed at prevention and clinical interventions to reduce morbidity and mortality due to head injury.

Patient-Centered Approaches to Cognitive Assessment in Acute TBI

PURPOSE OF THE REVIEW

The purpose of this article is to help clinicians understand how underlying pathophysiologies and medical comorbidities associated with acute traumatic brain injury (TBI) can impact assessment of cognition during the initial stages of recovery. Clinicians can use information from this article to develop assessment plans rooted in patient-centered care.

RECENT FINDINGS

The authors conducted a review of the literature related to the assessment of cognition in acute TBI, focusing on pathophysiology, medical comorbidities, and assessment approaches. Results indicated that TBI pathophysiologies associated with white and gray matter changes make many patients vulnerable to cognitive deficits. Acute comorbidities such as psychological and pain status influence cognitive abilities as well. The current approaches to cognitive assessment can be limited in many ways, though by using the patient's neuropathological profile, noted comorbidities, and other patient specific factors, clinicians can potentially improve the effectiveness of assessment.

Partial Ablation of Astrocytes Exacerbates Cerebral Infiltration of Monocytes and Neuronal Loss After Brain Stab Injury in Mice

In traumatic brain injury (TBI), mechanical injury results in instantaneous tissue damages accompanied by subsequent pro-inflammatory cascades composed of microgliosis and astrogliosis. However, the interactive roles between microglia and astrocytes during the pathogenesis of TBI remain unclear and sometimes debatable. In this study, we used a forebrain stab injury mouse model to investigate the pathological role of reactive astrocytes in cellular and molecular changes of inflammatory response following TBI. In the ipsilateral hemisphere of stab-injured brain, monocyte infiltration and neuronal loss, as well as increased elevated astrogliosis, microglia activation and inflammatory cytokines were observed. To verify the role of reactive astrocytes in TBI, local and partial ablation of astrocytes was achieved by stereotactic injection of diphtheria toxin in the forebrain of Aldh1l1-CreER^T2::Ai9::iDTR transgenic mice which expressed diphtheria toxin receptor (DTR) in astrocytes after tamoxifen induction. This strategy achieved about 20% of astrocytes reduction at the stab site as validated by immunofluorescence co-staining of GFAP with tdTomato-positive astrocytes. Interestingly, reduction of astrocytes showed increased microglia activation and monocyte infiltration, accompanied with increased severity in stab injury-induced neuronal loss when compared with DTR^-/- mice, together with elevation of inflammatory chemokines such as CCL2, CCL5 and CXCL10 in astrogliosis-reduced mice. Collectively, our data verified the interactive role of astrocytes as an immune modulator in suppressing inflammatory responses in the injured brain. Schematic diagram shows monocyte infiltration and neuronal loss, as well as increased elevated astrogliosis, microglia activation and chemokines were observed in the injured site after stab injury. Local and partial ablation of astrocytes led to increased microglia activation and monocyte infiltration, accompanied with increased severity in neuronal loss together with elevation of inflammatory chemokines as compared with control mice subjected stab injury.

Racial/Ethnic Differences in Traumatic Brain Injury: Pathophysiology, Outcomes, and Future Directions

Traumatic brain injury (TBI) is a major cause of death and disability in the United States, exacting a debilitating physical, social, and financial strain. Therefore, it is crucial to examine the impact of TBI on medically underserved communities in the U.S. The purpose of the current study was to review the literature on TBI for evidence of racial/ethnic differences in the U.S. Results of the review showed significant racial/ethnic disparities in TBI outcome and several notable differences in other TBI variables. American Indian/Alaska Natives have the highest rate and number of TBI-related deaths compared with all other racial/ethnic groups; Blacks/African Americans are significantly more likely to incur a TBI from violence when compared with Non-Hispanic Whites; and minorities are significantly more likely to have worse functional outcome compared with Non-Hispanic Whites, particularly among measures of community integration. We were unable to identify any studies that looked directly at underlying racial/ethnic biological variations associated with different TBI outcomes. In the absence of studies on racial/ethnic differences in TBI pathobiology, taking an indirect approach, we looked for studies examining racial/ethnic differences in oxidative stress and inflammation outside the scope of TBI as they are known to heavily influence TBI pathobiology. The literature indicates that Blacks/African Americans have greater inflammation and oxidative stress compared with Non-Hispanic Whites. We propose that future studies investigate the possibility of racial/ethnic differences in inflammation and oxidative stress within the context of TBI to determine whether there is any relationship or impact on TBI outcome.

Cdk5 mediates rotational force-induced brain injury

Millions of traumatic brain injuries (TBIs) occur annually. TBIs commonly result from falls, traffic accidents, and sports-related injuries, all of which involve rotational acceleration/deceleration of the brain. During these injuries, the brain endures a multitude of primary insults including compression of brain tissue, damaged vasculature, and diffuse axonal injury. All of these deleterious effects can contribute to secondary brain ischemia, cellular death, and neuroinflammation that progress for weeks, months, and lifetime after injury. While the linear effects of head trauma have been extensively modeled, less is known about how rotational injuries mediate neuronal damage following injury. Here, we developed a new model of repetitive rotational head trauma in rodents and demonstrated acute and prolonged pathological, behavioral, and electrophysiological effects of rotational TBI (rTBI). We identify aberrant Cyclin-dependent kinase 5 (Cdk5) activity as a principal mediator of rTBI. We utilized Cdk5-enriched phosphoproteomics to uncover potential downstream mediators of rTBI and show pharmacological inhibition of Cdk5 reduces the cognitive and pathological consequences of injury. These studies contribute meaningfully to our understanding of the mechanisms of rTBI and how they may be effectively treated.

Neurometabolite alterations in traumatic brain injury and associations with chronic pain

Traumatic brain injury (TBI) can lead to a variety of comorbidities, including chronic pain. Although brain tissue metabolite alterations have been extensively examined in several chronic pain populations, it has received less attention in people with TBI. Thus, the primary aim of this study was to compare brain tissue metabolite levels in people with TBI and chronic pain (n = 16), TBI without chronic pain (n = 17), and pain-free healthy controls (n = 31). The metabolite data were obtained from participants using whole-brain proton magnetic resonance spectroscopic imaging (1H-MRSI) at 3 Tesla. The metabolite data included N-acetylaspartate, myo-inositol, total choline, glutamate plus glutamine, and total creatine. Associations between N-acetylaspartate levels and pain severity, neuropathic pain symptom severity, and psychological variables, including anxiety, depression, post-traumatic stress disorder (PTSD), and post-concussive symptoms, were also explored. Our results demonstrate N-acetylaspartate, myo-inositol, total choline, and total creatine alterations in pain-related brain regions such as the frontal region, cingulum, postcentral gyrus, and thalamus in individuals with TBI with and without chronic pain. Additionally, NAA levels in the left and right frontal lobe regions were positively correlated with post-concussive symptoms; and NAA levels within the left frontal region were also positively correlated with neuropathic pain symptom severity, depression, and PTSD symptoms in the TBI with chronic pain group. These results suggest that neuronal integrity or density in the prefrontal cortex, a critical region for nociception and pain modulation, is associated with the severity of neuropathic pain symptoms and psychological comorbidities following TBI. Our data suggest that a combination of neuronal loss or dysfunction and maladaptive neuroplasticity may contribute to the development of persistent pain following TBI, although no causal relationship can be determined based on these data.

Secondary Degeneration of Oligodendrocyte Precursor Cells Occurs as Early as 24 h after Optic Nerve Injury in Rats

Optic nerve injury causes secondary degeneration, a sequela that spreads damage from the primary injury to adjacent tissue, through mechanisms such as oxidative stress, apoptosis, and blood-brain barrier (BBB) dysfunction. Oligodendrocyte precursor cells (OPCs), a key component of the BBB and oligodendrogenesis, are vulnerable to oxidative deoxyribonucleic acid (DNA) damage by 3 days post-injury. However, it is unclear whether oxidative damage in OPCs occurs earlier at 1 day post-injury, or whether a critical 'window-of-opportunity' exists for therapeutic intervention. Here, a partial optic nerve transection rat model of secondary degeneration was used with immunohistochemistry to assess BBB dysfunction, oxidative stress, and proliferation in OPCs vulnerable to secondary degeneration. At 1 day post-injury, BBB breach and oxidative DNA damage were observed, alongside increased density of DNA-damaged proliferating cells. DNA-damaged cells underwent apoptosis (cleaved caspase3+), and apoptosis was associated with BBB breach. OPCs experienced DNA damage and apoptosis and were the major proliferating cell type with DNA damage. However, the majority of caspase3+ cells were not OPCs. These results provide novel insights into acute secondary degeneration mechanisms in the optic nerve, highlighting the need to consider early oxidative damage to OPCs in therapeutic efforts to limit degeneration following optic nerve injury.

In-vivo time course of organ uptake and blood-brain-barrier permeation of poly(L-lactide) and poly(perfluorodecyl acrylate) nanoparticles with different surface properties in unharmed and brain-traumatized rats

Background

Traumatic brain injury (TBI) has a dramatic impact on mortality and quality of life and the development of effective treatment strategies is of great socio-economic relevance. A growing interest exists in using polymeric nanoparticles (NPs) as carriers across the blood-brain barrier (BBB) for potentially effective drugs in TBI. However, the effect of NP material and type of surfactant on their distribution within organs, the amount of the administrated dose that reaches the brain parenchyma in areas with intact and opened BBB after trauma, and a possible elicited inflammatory response are still to be clarified.

Methods

The organ distribution, BBB permeation and eventual inflammatory activation of polysorbate-80 (Tw80) and sodiumdodecylsulfate (SDS) stabilized poly(L-lactide) (PLLA) and poly(perfluorodecyl acrylate) (PFDL) nanoparticles were evaluated in rats after intravenous administration. The NP uptake into the brain was assessed under intact conditions and after controlled cortical impact (CCI).

Results

A significantly higher NP uptake at 4 and 24 h after injection was observed in the liver and spleen, followed by the brain and kidney, with minimal concentrations in the lungs and heart for all NPs. A significant increase of NP uptake at 4 and 24 h after CCI was observed within the traumatized hemisphere, especially in the perilesional area, but NPs were still found in areas away from the injury site and the contralateral hemisphere. NPs were internalized in brain capillary endothelial cells, neurons, astrocytes, and microglia. Immunohistochemical staining against GFAP, Iba1, TNFα, and IL1β demonstrated no glial activation or neuroinflammatory changes.

Conclusions

Tw80 and SDS coated biodegradable PLLA and non-biodegradable PFDL NPs reach the brain parenchyma with and without compromised BBB by TBI, even though a high amount of NPs are retained in the liver and spleen. No inflammatory reaction is elicited by these NPs within 24 h after injection. Thus, these NPs could be considered as potentially effective carriers or markers of newly developed drugs with low or even no BBB permeation.

Are GABAergic drugs beneficial in providing neuroprotection after traumatic brain injuries? A comprehensive literature review of preclinical studies

Traumatic brain injuries (TBI) caused by physical impact to the brain can adversely impact the welfare and well-being of the affected individuals. One of the leading causes of mortality and dysfunction in the world, TBI is a major public health problem facing the human community. Drugs that target GABAergic neurotransmission are commonly used for sedation in clinical TBI yet their potential to cause neuroprotection is unclear. In this paper, I have performed a rigorous literature review of the neuroprotective effects of drugs that increase GABAergic currents based on the results reported in preclinical literature. The drugs covered in this review include the following: propofol, benzodiazepines, barbiturates, isoflurane, and other drugs that are agonists of GABAA receptors. A careful review of numerous preclinical studies reveals that these drugs fail to produce any neuroprotection after a primary impact to the brain. In numerous circumstances, they could be detrimental to neuroprotection by increasing the size of the contusional brain tissue and by severely interfering with behavioral and functional recovery. Therefore, anesthetic agents that work by enhancing the effect of neurotransmitter GABA should be administered with caution of TBI patients until a clear and concrete picture of their neuroprotective efficacy emerges in the clinical literature.

Influence of traumatic brain injury on ipsilateral and contralateral cortical perfusion in mice

Traumatic brain injury (TBI) is one of the most important causes of death in young adults. After brain injury cortical perfusion is impaired by cortical spreading depression, cerebral microvasospasm or microvascular thrombosis and contributes to secondary expansion of lesion into surrounding healthy brain tissue. The present study was designed to determine the regional cortical perfusion pattern after experimental TBI induced by controlled cortical impact (CCI) in male C57/BL6N mice. We performed a longitudinal time series analysis by Laser speckle contrast imaging (LSCI). Measurements were carried out before, immediately and 24 h after trauma. Immediately after CCI cortical perfusion in the lesion core dropped to 10 % of before injury (baseline; %BL) and to 21-24 %BL in the cortical area surrounding the core. Interestingly, cortical perfusion was also significantly reduced in the contralateral non-injured hemisphere (41-58 %BL) matching the corresponding brain region of the injured hemisphere. 24 h after CCI perfusion of the contralateral hemisphere returned to baseline level in the area corresponding to the lesion core, whereas the lateral area of the parietal cortex was hyperperfused (125 %BL). The lesion core region itself remained severely hypoperfused (18 to 26 %BL) during the observation period. TBI causes a maldistribution of both ipsi- and contralateral cerebral perfusion immediately after trauma, which persist for at least 24 h. Higher perfusion levels in the lesion core 24 h after trauma were associated with increased tissue damage, which supports the role of reperfusion injury for secondary brain damage after TBI.

Systemic immune inflammation index and peripheral blood carbon dioxide concentration at admission predict poor prognosis in patients with severe traumatic brain injury

Background

Recent studies have shown that systemic inflammation responses and hyperventilation are associated with poor outcomes in patients with severe traumatic brain injury (TBI). The aim of this retrospective study was to investigate the relationships between the systemic immune inflammation index (SII = platelet × neutrophil/lymphocyte) and peripheral blood CO₂ concentration at admission with the Glasgow Outcome Score (GOS) at 6 months after discharge in patients with severe TBI.

Methods

We retrospectively analyzed the clinical data for 1266 patients with severe TBI at three large medical centers from January 2016 to December 2021, and recorded the GOS 6 months after discharge. The receiver operating characteristic (ROC) curve was used to determine the best cutoff values for SII, CO₂, neutrophil to lymphocyte ratio (NLR), platelet to lymphocyte ratio (PLR), and lymphocyte to monocyte ratio (LMR), and chi-square tests were used to evaluate the relationships among SII, CO₂ and the basic clinical characteristics of patients with TBI. Multivariate logistic regression analysis was used to determine the independent prognostic factors for GOS in patients with severe TBI. Finally, ROC curve, nomogram, calibration curve and decision curve analyses were used to evaluate the value of SII and coSII-CO2 in predicting the prognosis of patients with severe TBI. And we used the multifactor regression analysis method to build the CRASH model and the IMPACT model. The CRASH model included age, GCS score (GCS, Glasgow Coma Scale) and Pupillary reflex to light: one, both, none. The IMPACT model includes age, motor score and Pupillary reflex to light: one, both, none.

Results

The ROC curves indicated that the best cutoff values of SII, CO₂, PLR, NLR and LMR were 2651.43×10⁹, 22.15mmol/L, 190.98×10⁹, 9.66×10⁹ and 1.5×10⁹, respectively. The GOS at 6 months after discharge of patients with high SII and low CO₂ were significantly poorer than those with low SII and high CO₂. Multivariate logistic regression analysis revealed that age, systolic blood pressure (SBP), pupil size, subarachnoid hemorrhage (SAH), SII, PLR, serum potassium concentration [K⁺], serum calcium concentration [Ca²⁺], international normalized ratio (INR), C-reactive protein (CRP) and co-systemic immune inflammation index combined with carbon dioxide (coSII-CO₂) (P < 0.001) were independent prognostic factors for GOS in patients with severe TBI. In the training group, the C-index was 0.837 with SII and 0.860 with coSII-CO₂. In the external validation group, the C-index was 0.907 with SII and 0.916 with coSII-CO₂. Decision curve analysis confirmed a superior net clinical benefit with coSII-CO₂ rather than SII in most cases. Furthermore, the calibration curve for the probability of GOS 6 months after discharge showed better agreement with the observed results when based on the coSII-CO₂ rather than the SII nomogram. According to machine learning, coSII-CO₂ ranked first in importance and was followed by pupil size, then SII.

Conclusions

SII and CO₂ have better predictive performance than NLR, PLR and LMR. SII and CO₂ can be used as new, accurate and objective clinical predictors, and coSII-CO₂, based on combining SII with CO₂, can be used to improve the accuracy of GOS prediction in patients with TBI 6 months after discharge.

Using bioinformatics technology to mine the expression of serum exosomal miRNA in patients with traumatic brain injury

Introduction

Traumatic brain injury (TBI) is considered the most common traumatic neurological disease, is associated with high mortality and long-term complications, and is a global public health issue. However, there has been little progress in serum markers for TBI research. Therefore, there is an urgent need for biomarkers that can sufficiently function in TBI diagnosis and evaluation.

Methods

Exosomal microRNA (ExomiR), a stable circulating marker in the serum, has aroused widespread interest among researchers. To explore the level of serum ExomiR after TBI, we quantified ExomiR expression levels in serum exosomes extracted from patients with TBI using next-generation sequencing (NGS) and explored potential biomarkers using bioinformatics screening.

Results

Compared with the control group, there were 245 ExomiR (136 up-regulated and 109 down-regulated) in the serum of the TBI group that changed significantly. We observed serum ExomiRs expression profiles associated with neurovascular remodeling, the integrity of the blood-brain barrier, neuroinflammation, and a cascade of secondary injury, including eight up-regulated ExomiRs (ExomiR-124-3p, ExomiR-137-3p, ExomiR-9-3p, ExomiR-133a-5p, ExomiR-204-3p, ExomiR-519a-5p, ExomiR-4732-5p, and ExomiR-206) and 2 down-regulated ExomiR (ExomiR-21-3p and ExomiR-199a-5).

Discussion

The results revealed that serum ExomiRs might become a new research direction and breakthrough for the diagnosis and pathophysiological treatment of patients with TBI.

Modifiable risk factors of dementia linked to excitation-inhibition imbalance

Recent evidence identifies 12 potentially modifiable risk factors for dementia to which 40% of dementia cases are attributed. While the recognition of these risk factors has paved the way for the development of new prevention measures, the link between these risk factors and the underlying pathophysiology of dementia is yet not well understood. A growing number of recent clinical and preclinical studies support a role of Excitation-Inhibition (E-I) imbalance in the pathophysiology of dementia. In this review, we aim to propose a conceptual model on the links between the modifiable risk factors and the E-I imbalance in dementia. This model, which aims to address the current gap in the literature, is based on 12 mediating common mechanisms: the hypothalamic-pituitary-adrenal (HPA) axis dysfunction, neuroinflammation, oxidative stress, mitochondrial dysfunction, cerebral hypo-perfusion, blood-brain barrier (BBB) dysfunction, beta-amyloid deposition, elevated homocysteine level, impaired neurogenesis, tau tangles, GABAergic dysfunction, and glutamatergic dysfunction. We believe this model serves as a framework for future studies in this field and facilitates future research on dementia prevention, discovery of new biomarkers, and developing new interventions.

The role of the microbiota-gut-brain axis in long-term neurodegenerative processes following traumatic brain injury

Traumatic brain injury (TBI) can be a devastating and debilitating disease to endure. Due to improvements in clinical practice, declining mortality rates have led to research into the long-term consequences of TBI. For example, the incidence and severity of TBI have been associated with an increased susceptibility of developing neurodegenerative disorders, such as Parkinson's or Alzheimer's disease. However, the mechanisms linking this alarming association are yet to be fully understood. Recently, there has been a groundswell of evidence implicating the microbiota-gut-brain axis in the pathogenesis of these diseases. Interestingly, survivors of TBI often report gastrointestinal complaints and animal studies have demonstrated gastrointestinal dysfunction and dysbiosis following injury. Autonomic dysregulation and chronic inflammation appear to be the main driver of these pathologies. Consequently, this review will explore the potential role of the microbiota-gut-brain axis in the development of neurodegenerative diseases following TBI.

A Systematic Review on Traumatic Brain Injury Pathophysiology and Role of Herbal Medicines in its Management

BACKGROUND

Traumatic brain injury (TBI) is a worldwide problem. Almost about sixtynine million people sustain TBI each year all over the world. Repetitive TBI linked with increased risk of neurodegenerative disorder such as Parkinson, Alzheimer, traumatic encephalopathy. TBI is characterized by primary and secondary injury and exerts a severe impact on cognitive, behavioral, psychological and other health problem. There were various proposed mechanism to understand complex pathophysiology of TBI but still there is a need to explore more about TBI pathophysiology. There are drugs present for the treatment of TBI in the market but there is still need of more drugs to develop for better and effective treatment of TBI, because no single drug is available which reduces the further progression of this injury.

OBJECTIVE

The main aim and objective of structuring this manuscript is to design, develop and gather detailed data regarding about the pathophysiology of TBI and role of medicinal plants in its treatment.

METHOD

This study is a systematic review conducted between January 1995 to June 2021 in which a consultation of scientific articles from indexed periodicals was carried out in Science Direct, United States National Library of Medicine (Pubmed), Google Scholar, Elsvier, Springer and Bentham.

RESULTS

A total of 54 studies were analyzed, on the basis of literature survey in the research area of TBI.

CONCLUSION

Recent studies have shown the potential of medicinal plants and their chemical constituents against TBI therefore, this review targets the detailed information about the pathophysiology of TBI and role of medicinal plants in its treatment.

Sex-stratified RNA-seq analysis reveals traumatic brain injury-induced transcriptional changes in the female hippocampus conducive to dementia

Introduction

Traumatic brain injury (TBI), resulting from a violent force that causes functional changes in the brain, is the foremost environmental risk factor for developing dementia. While previous studies have identified specific candidate genes that may instigate worse outcomes following TBI when mutated, TBI-induced changes in gene expression conducive to dementia are critically understudied. Additionally, biological sex seemingly influences TBI outcomes, but the discrepancies in post-TBI gene expression leading to progressive neurodegeneration between the sexes have yet to be investigated.

Methods

We conducted a whole-genome RNA sequencing analysis of post-mortem brain tissue from the parietal neocortex, temporal neocortex, frontal white matter, and hippocampus of 107 donors characterized by the Aging, Dementia, and Traumatic Brain Injury Project. Our analysis was sex-stratified and compared gene expression patterns between TBI donors and controls, a subset of which presented with dementia.

Results

We report three candidate gene modules from the female hippocampus whose expression correlated with dementia in female TBI donors. Enrichment analyses revealed that the candidate modules were notably enriched in cardiac processes and the immune-inflammatory response, among other biological processes. In addition, multiple candidate module genes showed a significant positive correlation with hippocampal concentrations of monocyte chemoattractant protein-1 in females with post-TBI dementia, which has been previously described as a potential biomarker for TBI and susceptibility to post-injury dementia. We concurrently examined the expression profiles of these candidate modules in the hippocampus of males with TBI and found no apparent indicator that the identified candidate modules contribute to post-TBI dementia in males.

Discussion

Herein, we present the first sex-stratified RNA sequencing analysis of TBI-induced changes within the transcriptome that may be conducive to dementia. This work contributes to our current understanding of the pathophysiological link between TBI and dementia and emphasizes the growing interest in sex as a biological variable affecting TBI outcomes.

Overview of the meningeal lymphatic vessels in aging and central nervous system disorders

In the aging process and central nervous system (CNS) diseases, the functions of the meningeal lymphatic vessels (MLVs) are impaired. Alterations in MLVs have been observed in aging-related neurodegenerative diseases, brain tumors, and even cerebrovascular disease. These findings reveal a new perspective on aging and CNS disorders and provide a promising therapeutic target. Additionally, recent neuropathological studies have shown that MLVs exchange soluble components between the cerebrospinal fluid (CSF) and interstitial fluid (ISF) and drain metabolites, cellular debris, misfolded proteins, and immune cells from the CSF into the deep cervical lymph nodes (dCLNs), directly connecting the brain with the peripheral circulation. Impairment and dysfunction of meningeal lymphatics can lead to the accumulation of toxic proteins in the brain, exacerbating the progression of neurological disorders. However, for many CNS diseases, the causal relationship between MLVs and neuropathological changes is not fully clear. Here, after a brief historical retrospection, we review recent discoveries about the hallmarks of MLVs and their roles in the aging and CNS diseases, as well as potential therapeutic targets for the treatment of neurologic diseases.

Design and optimization of metformin-loaded solid lipid nanoparticles for neuroprotective effects in a rat model of diffuse traumatic brain injury: A biochemical, behavioral, and histological study

BACKGROUND AND PURPOSE

Following traumatic brain injury, inflammation, mitochondrial dysfunction, oxidative stress, ischemia, and energy crisis can cause mortality or long-term morbidity. As an activator of AMP-activated protein kinase, metformin reduces the secondary injuries of traumatic brain injury by compensating for the lack of energy in damaged cells. But the blood-brain barrier prevents a hydrophilic drug such as metformin from penetrating the brain tissue. Solid lipid nanoparticles with their lipid nature can cross the blood-brain barrier and solve this challenge. so This study aimed to investigate the effect of metformin-loaded lipid nanoparticles (NanoMet) for drug delivery to the brain and reduce complications from traumatic brain injury.

METHOD

Different formulations of NanoMet were designed by Box-Behnken, and after formulation, particle size, zeta potential, and entrapment efficiency were investigated. For in vivo study, Male rats were divided into eight groups, and except for the intact and sham groups, the other groups underwent brain trauma by the Marmarou method. After the intervention, the Veterinary Coma Scale, Vestibular Motor function, blood-brain barrier integrity, cerebral edema, level of inflammatory cytokines, and histopathology of brain tissue were assessed.

RESULTS

The optimal formula had a size of 282.2 ± 9.05 nm, a zeta potential of -1.65 ± 0.33 mV, and entrapment efficiency of 60.61 ± 6.09% which released the drug in 1400 min. Concentrations of 5 and 10 mg/kg of this formula improved the consequences of trauma.

CONCLUSION

This study showed that nanoparticles could help target drug delivery to the brain and apply the desired result.

Traumatic Brain Injury and Secondary Neurodegenerative Disease

Traumatic brain injury (TBI) is a devastating event with severe long-term complications. TBI and its sequelae are one of the leading causes of death and disability in those under 50 years old. The full extent of secondary brain injury is still being intensely investigated; however, it is now clear that neurotrauma can incite chronic neurodegenerative processes. Chronic traumatic encephalopathy, Parkinson's disease, and many other neurodegenerative syndromes have all been associated with a history of traumatic brain injury. The complex nature of these pathologies can make clinical assessment, diagnosis, and treatment challenging. The goal of this review is to provide a concise appraisal of the literature with focus on emerging strategies to improve clinical outcomes. First, we review the pathways involved in the pathogenesis of neurotrauma-related neurodegeneration and discuss the clinical implications of this rapidly evolving field. Next, because clinical evaluation and neuroimaging are essential to the diagnosis and management of neurodegenerative diseases, we analyze the clinical investigations that are transforming these areas of research. Finally, we briefly review some of the preclinical therapies that have shown the most promise in improving outcomes after neurotrauma.

Early posttraumatic CSF1R inhibition via PLX3397 leads to time- and sex-dependent effects on inflammation and neuronal maintenance after traumatic brain injury in mice

BACKGROUND

There is a need for early therapeutic interventions after traumatic brain injury (TBI) to prevent neurodegeneration. Microglia/macrophage (M/M) depletion and repopulation after treatment with colony stimulating factor 1 receptor (CSF1R) inhibitors reduces neurodegeneration. The present study investigates short- and long-term consequences after CSF1R inhibition during the early phase after TBI.

METHODS

Sex-matched mice were subjected to TBI and CSF1R inhibition by PLX3397 for 5 days and sacrificed at 5 or 30 days post injury (dpi). Neurological deficits were monitored and brain tissues were examined for histo- and molecular pathological markers. RNAseq was performed with 30 dpi TBI samples.

RESULTS

At 5 dpi, CSF1R inhibition attenuated the TBI-induced perilesional M/M increase and associated gene expressions by up to 50%. M/M attenuation did not affect structural brain damage at this time-point, impaired hematoma clearance, and had no effect on IL-1β expression. At 30 dpi, following drug discontinuation at 5 dpi and M/M repopulation, CSF1R inhibition attenuated brain tissue loss regardless of sex, as well as hippocampal atrophy and thalamic neuronal loss in male mice. Selected gene markers of brain inflammation and apoptosis were reduced in males but increased in females after early CSF1R inhibition as compared to corresponding TBI vehicle groups. Neurological outcome in behaving mice was almost not affected. RNAseq and gene set enrichment analysis (GSEA) of injured brains at 30 dpi revealed more genes associated with dendritic spines and synapse function after early CSF1R inhibition as compared to vehicle, suggesting improved neuronal maintenance and recovery. In TBI vehicle mice, GSEA showed high oxidative phosphorylation, oxidoreductase activity and ribosomal biogenesis suggesting oxidative stress and increased abundance of metabolically highly active cells. More genes associated with immune processes and phagocytosis in PLX3397 treated females vs males, suggesting sex-specific differences in response to early CSF1R inhibition after TBI.

CONCLUSIONS

M/M attenuation after CSF1R inhibition via PLX3397 during the early phase of TBI reduces long-term brain tissue loss, improves neuronal maintenance and fosters synapse recovery. Overall effects were not sex-specific but there is evidence that male mice benefit more than female mice.

Oxidative Stress in Traumatic Brain Injury

Traumatic Brain Injury (TBI) remains a major cause of disability worldwide. It involves a complex neurometabolic cascade, including oxidative stress. The products of this manuscript is examining the underlying pathophysiological mechanism, including reactive oxygen species (ROS) and reactive nitrogen species (RNS). This process in turn leads to secondary injury cascade, which includes lipid peroxidation products. These reactions ultimately play a key role in chronic inflammation and synaptic dysfunction in a synergistic fashion. Although there are no FDA approved antioxidant therapy for TBI, there is a number of antioxidant therapies that have been tested and include free radical scavengers, activators of antioxidant systems, inhibitors of free radical generating enzymes, and antioxidant enzymes. Antioxidant therapies have led to cognitive and functional recovery post TBI, and they offer a promising treatment option for patients recovering from TBI. Current major challenges in treatment of TBI symptoms include heterogenous nature of injury, as well as access to timely treatment post injury. The inherent benefits of antioxidant therapies include minimally reported side effects, and relative ease of use in the clinical setting. The current review also provides a highlight of the more studied anti-oxidant regimen with applicability for TBI treatment with potential use in the real clinical setting.

Evaluating Thera-101 as a Low-Volume Resuscitation Fluid in a Model of Polytrauma

Traumatic brain injury (TBI) and hemorrhage remain challenging to treat in austere conditions. Developing a therapeutic to mitigate the associated pathophysiology is critical to meet this treatment gap, especially as these injuries and associated high mortality are possibly preventable. Here, Thera-101 (T-101) was evaluated as low-volume resuscitative fluid in a rat model of TBI and hemorrhage. The therapeutic, T-101, is uniquely situated as a TBI and hemorrhage intervention. It contains a cocktail of proteins and microvesicles from the secretome of adipose-derived mesenchymal stromal cells that can act on repair and regenerative mechanisms associated with poly-trauma. T-101 efficacy was determined at 4, 24, 48, and 72 h post-injury by evaluating blood chemistry, inflammatory chemo/cytokines, histology, and diffusion tensor imaging. Blood chemistry indicated that T-101 reduced the markers of liver damage to Sham levels while the levels remained elevated with the control (saline) resuscitative fluid. Histology supports the potential protective effects of T-101 on the kidneys. Diffusion tensor imaging showed that the injury caused the most damage to the corpus callosum and the fimbria. Immunohistochemistry suggests that T-101 may mitigate astrocyte activation at 72 h. Together, these data suggest that T-101 may serve as a potential field deployable low-volume resuscitation therapeutic.

Role of TREM2 in the Development of Neurodegenerative Diseases After Traumatic Brain Injury

Traumatic brain injury (TBI) has been found as the primary cause of morbidity and disability worldwide, which has posed a significant social and economic burden. The first stage of TBI produces brain edema, axonal damage, and hypoxia, thus having an effect on the blood-brain barrier function, promoting inflammatory responses, and increasing oxidative stress. Patients with TBI are more likely to develop post-traumatic epilepsy, behavioral issues, as well as mental illnesses. The long-term effects arising from TBI have aroused rising attention over the past few years. Microglia in the brain can express the triggering receptor expressed on myeloid cells 2 (TREM2), which is a single transmembrane receptor pertaining to the immunoglobulin superfamily. The receptor has been correlated with a number of neurodegenerative disorders, including Alzheimer's disease, Parkinson's disease, and other relevant diseases. In this review, it is demonstrated that TREM2 is promising to serve as a neuroprotective factor for neurodegenerative disorders following TBI by modulating the function of microglial cells. Accordingly, it has potential avenues for TREM2-related therapies to improve long-term recovery after TBI.

The utility of therapeutic hypothermia on cerebral autoregulation

Cerebral autoregulation (CA) dysfunction is a strong predictor of clinical outcome in patients with acute brain injury (ABI). CA dysfunction is a potential pathologic defect that may lead to secondary injury and worse functional outcomes. Early therapeutic hypothermia (TH) in patients with ABI is controversial. Many factors, including patient selection, timing, treatment depth, duration, and rewarming strategy, impact its clinical efficacy. Therefore, optimizing the benefit of TH is an important issue. This paper reviews the state of current research on the impact of TH on CA function, which may provide the basis and direction for CA-oriented target temperature management.

Emerging role of STING signalling in CNS injury: inflammation, autophagy, necroptosis, ferroptosis and pyroptosis

Stimulator of interferons genes (STING), which is crucial for the secretion of type I interferons and proinflammatory cytokines in response to cytosolic nucleic acids, plays a key role in the innate immune system. Studies have revealed the participation of the STING pathway in unregulated inflammatory processes, traumatic brain injury (TBI), spinal cord injury (SCI), subarachnoid haemorrhage (SAH) and hypoxic–ischaemic encephalopathy (HIE). STING signalling is markedly increased in CNS injury, and STING agonists might facilitate the pathogenesis of CNS injury. However, the effects of STING-regulated signalling activation in CNS injury are not well understood. Aberrant activation of STING increases inflammatory events, type I interferon responses, and cell death. cGAS is the primary pathway that induces STING activation. Herein, we provide a comprehensive review of the latest findings related to STING signalling and the cGAS–STING pathway and highlight the control mechanisms and their functions in CNS injury. Furthermore, we summarize and explore the most recent advances toward obtaining an understanding of the involvement of STING signalling in programmed cell death (autophagy, necroptosis, ferroptosis and pyroptosis) during CNS injury. We also review potential therapeutic agents that are capable of regulating the cGAS–STING signalling pathway, which facilitates our understanding of cGAS–STING signalling functions in CNS injury and the potential value of this signalling pathway as a treatment target.

Neutrophil-lymphocyte ratio as a predictor of outcome following traumatic brain injury: Systematic review and meta-analysis

Objectives

The neutrophil-to-lymphocyte ratio (NLR) is a simple and routinely performed hematological parameter; however, studies on NLR as a prognostic tool in traumatic brain injury (TBI) have yielded contradictory results.

Materials and Methods

This systematic review and meta-analysis was conducted according to the Preferred Reporting Items in the Systematic Review and Meta-Analysis guidelines 2020. Electronic databases of PubMed, Cochrane Library, Web of Science, and Scopus were searched. The population consisted of TBI patients in the absence of moderate and severe extracranial injury. Day 1 NLR was taken for the analysis. The outcomes evaluated were mortality and the Glasgow Outcome Scale (GOS). No restrictions were placed on the language, year and country of publication, and duration of follow-up. Animal studies were excluded from the study. Studies, where inadequate data were reported for the outcomes, were included in the qualitative synthesis but excluded from the quantitative synthesis. Study quality was evaluated using the Newcastle-Ottawa scale (NOS). The risk of bias was estimated using the Cochrane RoBANS risk of bias tool.

Results

We retrieved 7213 citations using the search strategy and 2097 citations were excluded based on the screening of the title and abstract. Full text was retrieved for 40 articles and subjected to the eligibility criteria, of which 28 were excluded from the study. Twelve studies were eligible for the synthesis of the systematic review while seven studies qualified for the meta-analysis. The median score of the articles was 8/9 as per NOS. The risk of selection bias was low in all the studies while the risk of detection bias was high in all except one study. Ten studies were conducted on adult patients, while two studies reported pediatric TBI. A meta-analysis for GOS showed that high NLR predicted unfavorable outcomes at ≥6 months with a mean difference of -5.18 (95% confidence interval: -10.04, -0.32); P = 0.04; heterogeneity (I2), being 98%. The effect estimates for NLR and mortality were a mean difference of -3.22 (95% confidence interval: -7.12, 0.68), P = 0.11, and an I2 of 85%. Meta-analysis for Area under the curve (AUC) receiver operating characteristic of the included studies showed good predictive power of NLR in predicting outcomes following TBI with AUC 0.706 (95% CI: 0.582-0.829).

Conclusion

A higher admission NLR predicts an increased mortality risk and unfavorable outcomes following TBI. However, future research will likely address the existing gaps.

Chronic Cognitive and Cerebrovascular Function after Mild Traumatic Brain Injury in Rats

Severe traumatic brain injury (TBI) results in cognitive dysfunction in part due to vascular perturbations. In contrast, the long-term vasculo-cognitive pathophysiology of mild TBI (mTBI) remains unknown. We evaluated mTBI effects on chronic cognitive and cerebrovascular function and assessed their interrelationships. Sprague-Dawley rats received midline fluid percussion injury (n = 20) or sham (n = 21). Cognitive function was assessed (3- and 6-month novel object recognition [NOR], novel object location [NOL], and temporal order object recognition [TOR]). Six-month cerebral blood flow (CBF) and cerebral blood volume (CBV) using contrast magnetic resonance imaging (MRI) and ex vivo circle of Willis artery endothelial and smooth muscle-dependent function were measured. mTBI rats showed significantly impaired NOR, with similar trends (non-significant) in NOL/TOR. Regional CBF and CBV were similar in sham and mTBI. NOR correlated with CBF in lateral hippocampus, medial hippocampus, and primary somatosensory barrel cortex, whereas it inversely correlated with arterial smooth muscle-dependent dilation. Six-month baseline endothelial and smooth muscle-dependent arterial function were similar among mTBI and sham, but post-angiotensin 2 stimulation, mTBI showed no change in smooth muscle-dependent dilation from baseline response, unlike the reduction in sham. mTBI led to chronic cognitive dysfunction and altered angiotensin 2-stimulated smooth muscle-dependent vasoreactivity. The findings of persistent pathophysiological consequences of mTBI in this animal model add to the broader understanding of chronic pathophysiological sequelae in human mild TBI.

Saffron Extract Attenuates Anxiogenic Effect and Improves Cognitive Behavior in an Adult Zebrafish Model of Traumatic Brain Injury

Traumatic brain injury (TBI) has the highest mortality rates worldwide, yet effective treatment remains unavailable. TBI causes inflammatory responses, endoplasmic reticulum stress, disruption of the blood-brain barrier and neurodegeneration that lead to loss of cognition, memory and motor skills. Saffron (Crocus sativus L.) is known for its anti-inflammatory and neuroprotective effects, which makes it a potential candidate for TBI treatment. Zebrafish (Danio rerio) shares a high degree of genetic homology and cell signaling pathways with mammals. Its active neuro-regenerative function makes it an excellent model organism for TBI therapeutic drug identification. The objective of this study was to assess the effect of saffron administration to a TBI zebrafish model by investigating behavioral outcomes such as anxiety, fear and memory skills using a series of behavioral tests. Saffron exhibited anxiolytic effect on anxiety-like behaviors, and showed prevention of fear inhibition observed after TBI. It improved learning and enhanced memory performance. These results suggest that saffron could be a novel therapeutic enhancer for neural repair and regeneration of networks post-TBI.

Hypoxia-pretreated mesenchymal stem cell-derived exosomes-loaded low-temperature extrusion 3D-printed implants for neural regeneration after traumatic brain injury in canines

Regenerating brain defects after traumatic brain injury (TBI) still remains a significant difficulty, which has motivated interest in 3D printing to design superior replacements for brain implantation. Collagen has been applied to deliver cells or certain neurotrophic factors for neuroregeneration. However, its fast degradation rate and poor mechanical strength prevent it from being an excellent implant material after TBI. In the present study, we prepared 3D-printed collagen/silk fibroin/hypoxia-pretreated human umbilical cord mesenchymal stem cells (HUCMSCs)-derived exosomes scaffolds (3D-CS-HMExos), which possessed favorable physical properties suitable biocompatibility and biodegradability and were attractive candidates for TBI treatment. Furthermore, inspired by exosomal alterations resulting from cells in different external microenvironments, exosomes were engineered through hypoxia stimulation of mesenchymal stem cells and were proposed as an alternative therapy for promoting neuroregeneration after TBI. We designed hypoxia-preconditioned (Hypo) exosomes derived from HUCMSCs (Hypo-MExos) and proposed them as a selective therapy to promote neuroregeneration after TBI. For the current study, 3D-CS-HMExos were prepared for implantation into the injured brains of beagle dogs. The addition of hypoxia-induced exosomes further exhibited better biocompatibility and neuroregeneration ability. Our results revealed that 3D-CS-HMExos could significantly promote neuroregeneration and angiogenesis due to the doping of hypoxia-induced exosomes. In addition, the 3D-CS-HMExos further inhibited nerve cell apoptosis and proinflammatory factor (TNF-α and IL-6) expression and promoted the expression of an anti-inflammatory factor (IL-10), ultimately enhancing the motor functional recovery of TBI. We proposed that the 3D-CS-loaded encapsulated hypoxia-induced exosomes allowed an adaptable environment for neuroregeneration, inhibition of inflammatory factors and promotion of motor function recovery in TBI beagle dogs. These beneficial effects implied that 3D-CS-HMExos implants could serve as a favorable strategy for defect cavity repair after TBI.

Antithrombin activity levels for predicting long-term outcomes in the early phase of isolated traumatic brain injury

Coagulopathy management is an important strategy for preventing secondary brain damage in patients with traumatic brain injury (TBI). Antithrombin (AT) is a natural anticoagulant that controls coagulation and inflammation pathways. However, the significance of AT activity levels for outcomes in patients with trauma remains unclear. This study aimed to investigate the relationship between AT activity levels and long-term outcomes in patients with TBI; this was a sub-analysis of a prior study that collected blood samples of trauma patients prospectively in a tertiary care center in Kawaguchi City, Japan. We included patients with isolated TBI (iTBI) aged ≥16 years admitted directly to our hospital within 1 h after injury between April 2018 and March 2021. General coagulofibrinolytic and specific molecular biomarkers, including AT, were measured at 1, 3, 6, 12, and 24 h after injury. We analyzed changes in the AT activity levels during the study period and the impact of the AT activity levels on long-term outcomes, the Glasgow Outcome Scale-Extended (GOSE), 6 months after injury. 49 patients were included in this study; 24 had good neurological outcomes (GOSE 6-8), and 25 had poor neurological outcomes (GOSE 1-5). Low AT activity levels were shown within 1 h after injury in patients in the poor GOSE group; this was associated with poor outcomes. Furthermore, AT activity levels 1 h after injury had a strong predictive value for long-term outcomes (area under the receiver operating characteristic curve of 0.871; 95% CI: 0.747-0.994). Multivariate logistic regression analysis with various biomarkers showed that AT was an independent factor of long-term outcome (adjusted odds ratio: 0.873; 95% CI: 0.765-0.996; p=0.043). Another multivariate analysis with severity scores showed that low AT activity levels were associated with poor outcomes (adjusted odds ratio: 0.909; 95% CI: 0.822-1.010; p=0.063). We demonstrated that the AT activity level soon after injury could be a predictor of long-term neurological prognosis in patients with iTBI.

Porous Silicon Nanoparticles Targeted to the Extracellular Matrix for Therapeutic Protein Delivery in Traumatic Brain Injury

Traumatic brain injury (TBI) is a major cause of disability and death among children and young adults in the United States, yet there are currently no treatments that improve the long-term brain health of patients. One promising therapeutic for TBI is brain-derived neurotrophic factor (BDNF), a protein that promotes neurogenesis and neuron survival. However, outstanding challenges to the systemic delivery of BDNF are its instability in blood, poor transport into the brain, and short half-life in circulation and brain tissue. Here, BDNF is encapsulated into an engineered, biodegradable porous silicon nanoparticle (pSiNP) in order to deliver bioactive BDNF to injured brain tissue after TBI. The pSiNP carrier is modified with the targeting ligand CAQK, a peptide that binds to extracellular matrix components upregulated after TBI. The protein cargo retains bioactivity after release from the pSiNP carrier, and systemic administration of the CAQK-modified pSiNPs results in effective delivery of the protein cargo to injured brain regions in a mouse model of TBI. When administered after injury, the CAQK-targeted pSiNP delivery system for BDNF reduces lesion volumes compared to free BDNF, supporting the hypothesis that pSiNPs mediate therapeutic protein delivery after systemic administration to improve outcomes in TBI.

Paradigm Shift in Materials for Skull Reconstruction Facilitated by Science and Technological Integration

The surgical repair of a bone deficiency in the skull caused by a prior procedure or accident is known as cranioplasty. There are various types of cranioplasties, but the majority entail raising the scalp and reshaping the skull using either the original piece of bone from the skull or a specially molded graft created from Titanium (plate or mesh), artificial bone in place of, a stable biomaterial (prefabricated customized implant to match the exact contour and shape of the skull). Cranioplasty, one of the oldest surgical treatments for cranial abnormalities, has undergone several changes throughout the years to discover the best material to improve patient outcomes. Various materials have been utilized in cranioplasty throughout history. As biomedical technology progresses, surgeons will have access to new materials. There is still no agreement on the optimum material, and research into biologic and nonbiologic alternatives is ongoing in the hopes of finding the finest reconstruction material. The materials and techniques used in cranioplasty are covered in this article.

Carotid Arterial Compliance and Aerobic Exercise Training in Chronic Traumatic Brain Injury: A Pilot Study

OBJECTIVE

Decreased carotid arterial compliance (CAC) is associated with cerebral microvascular damage, cerebral blood flow (CBF) dysregulation, and increased risk for stroke and dementia, which are reported to be prevalent after traumatic brain injury (TBI). However, the effect of TBI on CAC has not been reported. The purposes of this pilot study were to (1) compare CAC between participants with chronic traumatic brain injury (cTBI) and age-matched healthy control (HC) subjects and (2) to examine whether CAC changed after 3 months of exercise training in those with cTBI.

SETTING

Community based.

PARTICIPANTS

Nineteen participants with cTBI (6-72 months postinjury) and 19 HC matched for age and sex were tested at baseline. The same cTBI cohort was enrolled in a proof-of-concept randomized controlled exercise training program to investigate the effects of 3 months of aerobic exercise training (AET) or nonaerobic stretching and toning (SAT) on cerebrovascular parameters.

DESIGN

Cross-sectional study and randomized controlled trial.

MAIN MEASURES

CAC was measured by tonometry and ultrasonography at the common carotid artery; CBF was measured by ultrasonography at the bilateral internal carotid and vertebral arteries, and pulsatile CBF was measured by transcranial Doppler ultrasonography at the middle cerebral arteries. Cerebrovascular resistance (CVR) was calculated as mean arterial pressure divided by total CBF.

RESULTS

Relative to HC, the participants with cTBI had lower CAC (0.10 ± 0.03 vs 0.12 ± 0.03 mm 2 /mm Hg, P = .046) and higher CVR (0.17 ± 0.03 vs 0.15 ± 0.03 mm Hg/mL/min, P = .028). CAC tended to increase after AET compared with SAT ( P = .080). Increases in CAC were associated with decreased pulsatile CBF ( r = -0.689, P = .003).

CONCLUSION

These findings suggest that the individuals with cTBI have decreased CAC, which may potentially be improved by AET.

Tenascin-C fibronectin D domain is involved in the fine-tuning of glial response to CNS injury in vitro

Understanding processes that occur after injuries to the central nervous system is essential in order to gain insight into how the restoration of function can be improved. Extracellular glycoprotein tenascin-C (TnC) has numerous functions in wound healing process depending on the expression time, location, isoform and binding partners which makes it interesting to study in this context. We used an in vitro injury model, the mixed culture of cortical astrocytes and microglia, and observed that without TnC microglial cells tend to populate gap area in greater numbers and proliferate more, whereas astrocytes build up in the border region to promote faster gap closure. Alternatively spliced domain of TnC, fibronectin type III-like repeat D (FnD) strongly affected physiological properties and morphology of both astrocytes and microglia in this injury model. The rate of microglial proliferation in the injury region decreased significantly with the addition of FnD. Additionally, density of microglia also decreased, in part due to reduced proliferation, and possibly due to reduced migration and increased contact inhibition between enlarged FnD-treated cells. Overall morphology of FnD-treated microglia resembled the activated pro-inflammatory cells, and elevated expression of iNOS was in accordance with this phenotype. The effect of FnD on astrocytes was different, as it did not affect their proliferation, but stimulated migration of reactivated astrocytes into the scratched area 48 h after the lesion. Elevated expression and secretion of TNF-α and IL-1β upon FnD treatment indicated the onset of inflammation. Furthermore, on Western blots we observed increased intensity of precursor bands of β1 integrin and appearance of monomeric bands of P2Y12R after FnD treatment which substantiates and clarifies its role in cellular shape and motility changes. Our results show versatile functions of TnC and in particular FnD after injury, mostly contributing to ongoing inflammation in the injury region. Based on our findings, FnD might be instrumental in limiting immune cell infiltration, and promoting astrocyte migration within the injury region, thus influencing spaciotemporal organization of the wound and surrounding area.

Perspectives on the Molecular Mediators of Oxidative Stress and Antioxidant Strategies in the Context of Neuroprotection and Neurolongevity: An Extensive Review

Molecules with at least one unpaired electron in their outermost shell are known as free radicals. Free radical molecules are produced either within our bodies or by external sources such as ozone, cigarette smoking, X-rays, industrial chemicals, and air pollution. Disruption of normal cellular homeostasis by redox signaling may result in cardiovascular, neurodegenerative diseases and cancer. Although ROS (reactive oxygen species) are formed in the GI tract, little is known about how they contribute to pathophysiology and disease etiology. When reactive oxygen species and antioxidants are in imbalance in our bodies, they can cause cell structure damage, neurodegenerative diseases, diabetes, hypercholesterolemia, atherosclerosis, cancer, cardiovascular diseases, metabolic disorders, and other obesity-related disorders, as well as protein misfolding, mitochondrial dysfunction, glial cell activation, and subsequent cellular apoptosis. Neuron cells are gradually destroyed in neurodegenerative diseases. The production of inappropriately aggregated proteins is strongly linked to oxidative stress. This review's goal is to provide as much information as possible about the numerous neurodegenerative illnesses linked to oxidative stress. The possibilities of multimodal and neuroprotective therapy in human illness, using already accessible medications and demonstrating neuroprotective promise in animal models, are highlighted. Neuroprotection and neurolongevity may improve from the use of bioactive substances from medicinal herbs like Allium stadium, Celastrus paniculatus, and Centella asiatica. Many neuroprotective drugs' possible role has been addressed. Preventing neuroinflammation has been demonstrated in several animal models.