Protein biomarkers of epileptogenicity after traumatic brain injury

Posttraumatic epilepsy in chronic disorders of consciousness due to severe traumatic brain injury after traffic accidents

PURPOSE

To evaluate the clinical state of posttraumatic epilepsy (PTE) in patients with chronic disorders of consciousness (CDC) due to severe traumatic brain injury (STBI) after traffic accidents and clarify the risk factors for seizure occurrence in such patients.

METHODS

Two hundred ninety-three patients with CDC due to STBI (mean age at admission [±standard deviation]: 36.4 ± 17.9 years; men: 71.7 %; mean duration of injury to admission: 416 ± 732 days; mean hospitalization time: 899 ± 319 days) were enrolled in this study. We retrospectively investigated the relationship between seizure conditions (type and frequency) and clinical data, including age, sex, pathological types of brain injury, with/without surgical intervention, degree of CDC, and administration of antiseizure medications (ASMs).

RESULTS

Overall, 52.9 % (n = 155/293) and 64.2 % of the patients (n = 183/of 285 patients surviving at discharge) were administered ASMs at admission and discharge, respectively. One hundred thirty-two patients (45.1 %) experienced epileptic seizures during hospitalization, and the mean seizure frequency was 4.0 ± 0.4 times per year. In multivariate analysis, significant and independent risk factors of seizure occurrence were revealed to be male sex, high National Agency for Automotive Safety and Victims' Aid score, hypoxic encephalopathy, and history of the neurosurgical operations.

CONCLUSION

The high prevalence of PTE in patients with CDC due to STBI, and the significant and independent risk factors for seizure occurrence in the chronic clinical phase were revealed. We expect that this study will aid toward improving clinical assessment and management of epileptic seizures in the population.

Personalized antiseizure medication therapy in critically ill adult patients

Precision medicine has the potential to have a significant impact on both drug development and patient care. It is crucial to not only provide prompt effective antiseizure treatment for critically ill patients after seizures start but also have a proactive mindset and concentrate on epileptogenesis and the underlying cause of the seizures or seizure disorders. Critical illness presents different treatment issues compared with the ambulatory population, which makes it challenging to choose the best antiseizure medications and to administer them at the right time and at the right dose. Since there is a paucity of information available on antiseizure medication dosing in critically ill patients, therapeutic drug monitoring is a useful tool for defining each patient's personal therapeutic range and assisting clinicians in decision-making. Use of pharmacogenomic information relating to pharmacokinetics, hepatic metabolism, and seizure etiology may improve safety and efficacy by individualizing therapy. Studies evaluating the clinical implementation of pharmacogenomic information at the point-of-care and identification of biomarkers are also needed. These studies may make it possible to avoid adverse drug reactions, maximize drug efficacy, reduce drug-drug interactions, and optimize medications for each individual patient. This review will discuss the available literature and provide future insights on precision medicine use with antiseizure therapy in critically ill adult patients.

Early preclinical plasma protein biomarkers of brain trauma are influenced by early seizures and levetiracetam

OBJECTIVE

We used the lateral fluid percussion injury (LFPI) model of moderate-to-severe traumatic brain injury (TBI) to identify early plasma biomarkers predicting injury, early post-traumatic seizures or neuromotor functional recovery (neuroscores), considering the effect of levetiracetam, which is commonly given after severe TBI.

METHODS

Adult male Sprague-Dawley rats underwent left parietal LFPI, received levetiracetam (200 mg/kg bolus, 200 mg/kg/day subcutaneously for 7 days [7d]) or vehicle post-LFPI, and were continuously video-EEG recorded (n = 14/group). Sham (craniotomy only, n = 6), and naïve controls (n = 10) were also used. Neuroscores and plasma collection were done at 2d or 7d post-LFPI or equivalent timepoints in sham/naïve. Plasma protein biomarker levels were determined by reverse phase protein microarray and classified according to injury severity (LFPI vs. sham/control), levetiracetam treatment, early seizures, and 2d-to-7d neuroscore recovery, using machine learning.

RESULTS

Low 2d plasma levels of Thr231 -phosphorylated tau protein (pTAU-Thr231 ) and S100B combined (ROC AUC = 0.7790) predicted prior craniotomy surgery (diagnostic biomarker). Levetiracetam-treated LFPI rats were differentiated from vehicle treated by the 2d-HMGB1, 2d-pTAU-Thr231 , and 2d-UCHL1 plasma levels combined (ROC AUC = 0.9394) (pharmacodynamic biomarker). Levetiracetam prevented the seizure effects on two biomarkers that predicted early seizures only among vehicle-treated LFPI rats: pTAU-Thr231 (ROC AUC = 1) and UCHL1 (ROC AUC = 0.8333) (prognostic biomarker of early seizures among vehicle-treated LFPI rats). Levetiracetam-resistant early seizures were predicted by high 2d-IFNγ plasma levels (ROC AUC = 0.8750) (response biomarker). 2d-to-7d neuroscore recovery was best predicted by higher 2d-S100B, lower 2d-HMGB1, and 2d-to-7d increase in HMGB1 or decrease in TNF (P < 0.05) (prognostic biomarkers).

SIGNIFICANCE

Antiseizure medications and early seizures need to be considered in the interpretation of early post-traumatic biomarkers.

The Impacts of Surgery and Intracerebral Electrodes in C57BL/6J Mouse Kainate Model of Epileptogenesis: Seizure Threshold, Proteomics, and Cytokine Profiles

Intracranial electroencephalography (EEG) is commonly used to study epileptogenesis and epilepsy in experimental models. Chronic gliosis and neurodegeneration at the injury site are known to be associated with surgically implanted electrodes in both humans and experimental models. Currently, however, there are no reports on the impact of intracerebral electrodes on proteins in the hippocampus and proinflammatory cytokines in the cerebral cortex and plasma in experimental models. We used an unbiased, label-free proteomics approach to identify the altered proteins in the hippocampus, and multiplex assay for cytokines in the cerebral cortex and plasma of C57BL/6J mice following bilateral surgical implantation of electrodes into the cerebral hemispheres. Seven days following surgery, a repeated low dose kainate (KA) regimen was followed to induce status epilepticus (SE). Surgical implantation of electrodes reduced the amount of KA necessary to induce SE by 50%, compared with mice without surgery. Tissues were harvested 7 days post-SE (i.e., 14 days post-surgery) and compared with vehicle-treated mice. Proteomic profiling showed more proteins (103, 6.8% of all proteins identified) with significantly changed expression (p < 0.01) driven by surgery than by KA treatment itself without surgery (27, 1.8% of all proteins identified). Further, electrode implantation approximately doubled the number of KA-induced changes in protein expression (55, 3.6% of all identified proteins). Further analysis revealed that intracerebral electrodes and KA altered the expression of proteins associated with epileptogenesis such as inflammation (C1q system), neurodegeneration (cystatin-C, galectin-1, cathepsin B, heat-shock protein 25), blood–brain barrier dysfunction (fibrinogen-α, serum albumin, α2 macroglobulin), and gliosis (vimentin, GFAP, filamin-A). The multiplex assay revealed a significant increase in key cytokines such as TNFα, IL-1β, IL-4, IL-5, IL-6, IL-10, IL12p70, IFN-γ, and KC/GRO in the cerebral cortex and some in the plasma in the surgery group. Overall, these findings demonstrate that surgical implantation of depth electrodes alters some of the molecules that may have a role in epileptogenesis in experimental models.

Nano dot blot: An alternative technique for protein identification and quantification in a high throughput format

BACKGROUND

Dot blot technique has been used in a similar way to western blotting, with the major difference being the lack of protein separation with electrophoresis. Protein samples are spotted over a membrane paper, the identification and quantification of a protein is achieved by immunodetection procedures such as colorimetry, fluorescence or chemiluminescence. This technique is widely accepted, but it uses large amounts of sample and antibodies to reveal the presence of the target protein. Significant milestones have been reached to achieve better results with the use of less sample and reagents; however, the ninety-six-well format is still in use.

NEW METHOD

In this work, we propose an innovation to this technique, reducing the amount of sample and antibodies to identify a specific protein when compared to the regular dot blot method. Procedure consists of using a sample volume of approximately 200 nanoliters deposited with a multineedle device developed by our group.

RESULTS

Five samples of standard protein or antigen can be spotted in a Cartesian format to identify and quantify the protein involved in physiological or pathological conditions. In addition, at least five replicates of sample or antigen are used to enable better statistics to calculate the concentration of every standard and the protein present in a sample.

CONCLUSIONS

Hundreds of samples can be deposited in a few minutes and analyzed in a single experimental session. To validate this method, which we called nano dot blot, six proteins involved in the inflammation process were tested in acute and chronic rat models of seizures.

Post-Traumatic Seizures: A Deep-Dive Into Pathogenesis

Post-traumatic seizures (PTS) have become an emerging challenge for neurologists worldwide with the rise of brain injuries. Trauma can lead to various outcomes, ranging from naive spasms to debilitating post-traumatic epilepsy (PTE). In this article, we will explore the pathogenesis of convulsions following a concussion. We will look at multiple studies to explain the various structural, metabolic, and inflammatory changes leading to seizures. Additionally, we will explore the association between severity and location of injury and PTE. PTE's pathophysiology is not entirely implicit, and we are still in the dark as to which anti-epileptic drugs will be useful in circumventing these attacks. The purpose of this narrative review is to explain the post-traumatic brain changes in detail so that such attacks can be either thwarted or treated more resourcefully in the future.

Identification of clinically relevant biomarkers of epileptogenesis - a strategic roadmap

Onset of many forms of epilepsy occurs after an initial epileptogenic insult or as a result of an identified genetic defect. Given that the precipitating insult is known, these epilepsies are, in principle, amenable to secondary prevention. However, development of preventive treatments is difficult because only a subset of individuals will develop epilepsy and we cannot currently predict which individuals are at the highest risk. Biomarkers that enable identification of these individuals would facilitate clinical trials of potential anti-epileptogenic treatments, but no such prognostic biomarkers currently exist. Several putative molecular, imaging, electroencephalographic and behavioural biomarkers of epileptogenesis have been identified, but clinical translation has been hampered by fragmented and poorly coordinated efforts, issues with inter-model reproducibility, study design and statistical approaches, and difficulties with validation in patients. These challenges demand a strategic roadmap to facilitate the identification, characterization and clinical validation of biomarkers for epileptogenesis. In this Review, we summarize the state of the art with respect to biomarker research in epileptogenesis and propose a five-phase roadmap, adapted from those developed for cancer and Alzheimer disease, that provides a conceptual structure for biomarker research.

Insulin injections inhibits PTZ-induced mitochondrial dysfunction, oxidative stress and neurological deficits via the SIRT1/PGC-1α/SIRT3 pathway

With an associated 20% death risk, epilepsy mainly involves seizures of an unpredictable and recurrent nature. This study was designed to evaluate the neuroprotective effects and underlying mechanisms of insulin on mitochondrial disruption, oxidative stress, cell apoptosis and neurological deficits after epilepsy seizures. Mice were exposed to repetitive injections of pentylenetetrazol at a dose of 37 mg per kg. The influence of insulin was assessed by many biochemical assays, histopathological studies and neurobehavioral experiments. The administration of insulin was proven to increase the latency of seizures while also decreasing their intensity. It also caused a reversal of mitochondrial dysfunction and ameliorated oxidative stress. Additionally, insulin pretreatment upregulated Bcl-2, downregulated Bax, and then played a neuroprotective role against hippocampal neuron apoptosis. Furthermore, when insulin was administered, SIRT1/PGC-1α/SIRT3 signals were activated, possibly due to the fact that insulin's neuroprotective and anti-mitochondrial damage characteristics added to its observed antiepileptic functions. Finally, insulin treatment is thus extremely valuable for effecting improvements in neurological functions, as has been estimated in a series of functional tests. In conclude, the results of this study consequently demonstrate insulin to have significant potential for future application in epilepsy management.

Neuroinflammation in Post-Traumatic Epilepsy: Pathophysiology and Tractable Therapeutic Targets

Epilepsy is a common chronic consequence of traumatic brain injury (TBI), contributing to increased morbidity and mortality for survivors. As post-traumatic epilepsy (PTE) is drug-resistant in at least one-third of patients, there is a clear need for novel therapeutic strategies to prevent epilepsy from developing after TBI, or to mitigate its severity. It has long been recognized that seizure activity is associated with a local immune response, characterized by the activation of microglia and astrocytes and the release of a plethora of pro-inflammatory cytokines and chemokines. More recently, increasing evidence also supports a causal role for neuroinflammation in seizure induction and propagation, acting both directly and indirectly on neurons to promote regional hyperexcitability. In this narrative review, we focus on key aspects of the neuroinflammatory response that have been implicated in epilepsy, with a particular focus on PTE. The contributions of glial cells, blood-derived leukocytes, and the blood–brain barrier will be explored, as well as pro- and anti-inflammatory mediators. While the neuroinflammatory response to TBI appears to be largely pro-epileptogenic, further research is needed to clearly demonstrate causal relationships. This research has the potential to unveil new drug targets for PTE, and identify immune-based biomarkers for improved epilepsy prediction.

Imaging biomarkers of posttraumatic epileptogenesis

Traumatic brain injury (TBI) affects 2.5 million people annually within the United States alone, with over 300 000 severe injuries resulting in emergency room visits and hospital admissions. Severe TBI can result in long-term disability. Posttraumatic epilepsy (PTE) is one of the most debilitating consequences of TBI, with an estimated incidence that ranges from 2% to 50% based on severity of injury. Conducting studies of PTE poses many challenges, because many subjects with TBI never develop epilepsy, and it can be more than 10 years after TBI before seizures begin. One of the unmet needs in the study of PTE is an accurate biomarker of epileptogenesis, or a panel of biomarkers, which could provide early insights into which TBI patients are most susceptible to PTE, providing an opportunity for prophylactic anticonvulsant therapy and enabling more efficient large-scale PTE studies. Several recent reviews have provided a comprehensive overview of this subject (Neurobiol Dis, 123, 2019, 3; Neurotherapeutics, 11, 2014, 231). In this review, we describe acute and chronic imaging methods that detect biomarkers for PTE and potential mechanisms of epileptogenesis. We also describe shortcomings in current acquisition methods, analysis, and interpretation that limit ongoing investigations that may be mitigated with advancements in imaging techniques and analysis.

Post-Traumatic Epilepsy and Seizure Susceptibility in Rat Models of Penetrating and Closed-Head Brain Injury

Traumatic brain injury (TBI) carries a risk of developing post-traumatic epilepsy (PTE). Currently, animal models that replicate clinical PTE (delayed spontaneous and recurrent seizures) are limited, which hinders pre-clinical research. In this study, we used two rat models of penetrating ballistic-like brain injury (PBBI) and closed-head injury (CHI) to induce spontaneous seizures and also measure changes in seizure susceptibility. In the PBBI model, two trajectories (frontal and lateral) and two injury severities for each trajectory, were evaluated. In the CHI model, a single projectile impact to the dorsal/lateral region of the head was tested. Continuous video-electroencephalographic (EEG) recordings were collected for 10 days at 1 or 6 month(s) post-injury. After EEG recording, all rats were given a sub-convulsant dose of pentylenetetrazole (PTZ) to challenge the seizure susceptibility. The video-EEG recording did not detect PTE following the PBBI. Only one CHI rat demonstrated persistent and recurrent non-convulsive seizures detected at 6 months post-injury. However, after PTZ challenge, 50-100% of the animals across different TBI groups experienced seizures. Seizure susceptibility increased over time from 1 to 6 months post-injury across the majority of TBI groups. Injury severity effects were not apparent within the PBBI model, but were evident between PBBI and CHI models. These results demonstrated the difficulties in detecting delayed spontaneous post-traumatic seizures even in a high-risk model of penetrating brain injury. The PTZ-induced increase in seizure susceptibility indicated the existence of vulnerable risk of epileptogenesis following TBI, which may be considered as an alternative research tool for pre-clinical studies of PTE.