Ablation of cyclooxygenase-2 in forebrain neurons is neuroprotective and dampens brain inflammation after status epilepticus

Self-assembled amphiphilic quaternary ammonium chitosan nanocapsules for improving the therapeutic potential and bioavailability of Moringa oleifera polyphenols in safe cancer therapy

AIM

This study aimed to explore the capabilities of amphiphilic quaternary ammonium chitosan (AQAC) nanocapsules to improve the bioavailability, therapeutic efficacy, and delivery of Moringa oleifera polyphenols (MOPP). The encapsulated MOPP was evaluated as a safe chemotherapeutic for Ehrlich ascites carcinoma cells (EACs) in the peritoneal cavities of female mice without kidney damage.

MATERIALS AND METHODS

MOPP#AQAC was initially synthesized and characterized. Four equal groups of 60 female Swiss albino mice were used for animal studies: group I (negative control), group II (drug, MOPP#AQAC), group III (positive control, EACs-bearing), and group IV (therapeutic, (EACs + MOPP#AQAC).

RESULTS

In vivo, MOPP#AQAC showed antioxidant and anti-cancer properties against EACs. MOPP#AQAC-treated EACs-bearing mice show significantly increased reduced glutathione (GSH), catalase (CAT) and superoxide dismutase (SOD), and significantly decreased urea, creatinine, urinary protein, kidney injury molecule-1 (KIM-1), malondialdehyde (MDA), cyclooxygenase-2 (COX2), Neutrophil Gelatinase-Associated Lipocalin (NGAL), Bcl-2 associated X protein (Bax) and Noxa. Interestingly, the administration of AQAC significantly reduced both the proliferation and size of EAC, indicating its chemopreventive and chemotherapeutic potentials. Biochemical investigations revealed that treating with MOPP#AQAC ameliorated kidney tissue damage, as evidenced by improved histological architecture and reduced signs of pathological alterations. This could restore antioxidant qualities, which eliminate oxidative stress.

Alleviation of Neurological Disorders by Targeting Neurodegenerative-Associated Enzymes: Natural and Synthetic Molecules

Neurological disorders, encompassing neurodegenerative and neuroinflammatory conditions, present significant public health and clinical challenges. Recent research has elucidated the pivotal role of various enzymes in the onset and progression of these disorders. This review explores the therapeutic potential of targeting these enzymes with natural and synthetic molecules. Key enzymes, including acetylcholinesterase, monoamine oxidase, beta-secretase, tau kinases, caspases, and cyclooxygenase-2, are implicated in diseases such as Alzheimer's disease, Parkinson's disease, and multiple sclerosis. Modulating these enzymes can alleviate symptoms, slow disease progression, or reverse pathological changes. Natural molecules derived from plants, microbes, seaweeds, and animals have long been noted for their therapeutic potential. Their ability to interact with specific enzymes with high specificity and minimal side effects makes them promising candidates for treatment. These natural agents provide a foundation for developing targeted therapies with improved safety profiles. Simultaneously, the development of synthetic chemistry has resulted in molecules designed to inhibit neurodegenerative enzymes with precision. This review examines the progress in creating small molecules, peptides, and enzyme inhibitors through sophisticated drug design techniques. It evaluates the efficacy, safety, and mechanisms of these synthetic agents, highlighting their potential for clinical application. The review offers a comprehensive overview of recent advancements in enzyme-targeted therapies for neurological disorders, covering both natural and synthetic molecules investigated in preclinical and clinical settings. It discusses the mechanisms through which these molecules exert their effects, the challenges faced in their development, and future research directions. By synthesizing current knowledge, this paper aims to illuminate the potential of enzyme-targeted interventions in managing neurological disorders, showcasing both the promise and limitations of these approaches.

Therapeutic potential of COX-2 inhibitors in neuropsychiatric disorders

Neuropsychiatric disorders such as bipolar disorder, migraine, major depressive disorder, epilepsy, attention-deficit/hyperactivity disorder, autism spectrum disorder and schizophrenia, are a huge burden on global health, impacting millions of individuals worldwide and posing significant barriers to effective treatment. Despite advancements in medication and psychotherapy, many patients continue to suffer from severe symptoms and receive little alleviation. All of these conditions are quite frequent, yet they affect people in a way that is exceedingly detrimental. The increasing evidence suggests the connection between these disorders and inflammation. Therefore, the use of anti-inflammatory agents, namely cyclooxygenase-2 (COX-2) inhibitors, offers a new approach to prevent and treat neuropsychiatric disorders. This review discusses about the COX pathway and the role of COX-2 in the neuroinflammation. Furthermore, this review highlights the COX-2 inhibitors as a promising therapeutic agent in these neuropsychiatric disorders, however, further studies are required to assess appropriate illness stage-related indication.

Vagus nerve stimulation (VNS) preventing postoperative cognitive dysfunction (POCD): two potential mechanisms in cognitive function

Postoperative cognitive dysfunction (POCD) impacts a significant number of patients annually, frequently impairing their cognitive abilities and resulting in unfavorable clinical outcomes. Aimed at addressing cognitive impairment, vagus nerve stimulation (VNS) is a therapeutic approach, which was used in many mental disordered diseases, through the modulation of vagus nerve activity. In POCD model, the enhancement of cognition function provided by VNS was shown, demonstrating VNS effect on cognition in POCD. In the present study, we primarily concentrates on elucidating the role of the VNS improving the cognitive function in POCD, via two potential mechanisms: the inflammatory microenvironment and epigenetics. This study provided a theoretical support for the feasibility that VNS can be a potential method to enhance cognition function in POCD.

Ligand-receptor interactions: A key to understanding microglia and astrocyte roles in epilepsy

Epilepsy continues to pose significant social and economic challenges on a global scale. Existing therapeutic approaches predominantly revolve around neurocentric mechanisms, and fail to control seizures in approximately one-third of patients. This underscores the pressing need for novel and complementary treatment approaches to address this gap. An increasing body of literature points to a role for glial cells, including microglia and astrocytes, in the pathogenesis of epilepsy. Notably, microglial cells, which serve as pivotal inflammatory mediators within the epileptic brain, have received increasing attention over recent years. These immune cells react to epileptogenic insults, regulate neuronal processes, and play diverse roles during the process of epilepsy development. Additionally, astrocytes, another integral non-neuronal brain cells, have garnered increasing recognition for their dynamic contributions to the pathophysiology of epilepsy. Their complex interactions with neurons and other glial cells involve modulating synaptic activity and neuronal excitability, thereby influencing the aberrant networks formed during epileptogenesis. This review explores the alterations in microglial and astrocytic function and their mechanisms of communication following an epileptogenic insult, examining their contribution to epilepsy development. By comprehensively studying these mechanisms, potential avenues could emerge for refining therapeutic strategies and ameliorating the impact of this complex neurological disease.

Neuroinflammation and neurodegeneration in Huntington's disease: genetic hallmarks, role of metals and organophosphates

Huntington's disease (HDs) is a fatal, autosomal dominant, and hereditary neurodegenerative disorder characterized by progressive motor dysfunction, cognitive decline, and psychiatric disturbances. HD is well linked to mutation in the HTT gene, which leads to an abnormal expansion of trinucleotide CAG repeats, resulting in the production of the mHTT protein and responsible for abnormally long poly-Q tract. These abnormal proteins disrupt cellular processes, including neuroinflammation, endoplasmic reticulum (ER) stress, and mitochondrial dysfunction, ultimately leading to selective neuronal loss in the brain. Epidemiological studies reveal significant regional variability in HDs prevalence, with the highest rates observed in North America and the lowest in Africa. In addition to genetic factors, environmental influences such as exposure to metals, and chemicals, and lifestyle factors like alcohol and tobacco use may exacerbate disease progression. This review explores the molecular mechanisms underlying HDs and emphasize the role of neuroinflammatory mediators and environmental factors, in HD research. Understanding these complex interactions is crucial for developing targeted interventions that can slow or halt the progression of this devastating disease.

A Narrative Review of the Published Pre-Clinical Evaluations: Multiple Effects of Arachidonic Acid, its Metabolic Enzymes and Metabolites in Epilepsy

Arachidonic acid (AA), an important polyunsaturated fatty acid in the brain, is hydrolyzed by a direct action of phospholipase A2 (PLA2) or through the combined action of phospholipase C and diacylglycerol lipase, and released into the cytoplasm. Various derivatives of AA can be synthesized mainly through the cyclooxygenase (COX), lipoxygenase (LOX) and cytochrome P450 (P450) enzyme pathways. AA and its metabolic enzymes and metabolites play important roles in a variety of neurophysiological activities. The abnormal metabolites and their catalytic enzymes in the AA cascade are related to the pathogenesis of various central nervous system (CNS) diseases, including epilepsy. Here, we systematically reviewed literatures in PubMed about the latest randomized controlled trials, animal studies and clinical studies concerning the known features of AA, its metabolic enzymes and metabolites, and their roles in epilepsy. The exclusion criteria include non-original studies and articles not in English.

Ameliorative effect of diclofenac in rotenone corneal kindling model of drug-resistant epilepsy: Edge of dual COX and KMO inhibition

Epilepsy affects millions of people worldwide, about one-third patients with epilepsy exhibits resistance to available antiseizures medications, known as drug-resistant epilepsy (DRE). Mitochondrial dysfunction has been implicated as a hallmark in drug-resistant epilepsy via activation of microglial kynurenine 3-monooxygenase (KMO) and cyclooxygenase (COX) enzymes, leading to neuroinflammation and oxidative stress. Diclofenac, an equipotent non selective cyclooxygenase inhibitor, has inhibitory action on KMO enzyme and has also shown anti-inflammatory and antioxidant properties in animal models of epilepsy. These properties make it a suitable candidate for amelioration of DRE. However, its potential in drug-resistant epilepsy remained unexplored till date. In this study, dose dependent effect of diclofenac (5 mg/kg, 10 mg/kg, 20 mg/kg) has been explored in rotenone corneal kindling model of mitochondrial DRE. The results of our study revealed the induction of drug resistance to antiseizure medications and induced kynurenine 3-monooxygenase activity in rotenone corneal kindled epileptic mice in comparison to naive mice. Treatment of rotenone corneal kindled epileptic mice with diclofenac resulted in a significant decrease in drug resistance to antiseizure medications as evident by a reduction in seizure score in the treatment groups as compared to control group, in post-treatment resistance validation. The kynurenine 3-monooxygenase inhibitory activity (as evidenced by decreased levels of neurotoxic quinolinic acid) and the antioxidant effect (as evident by significantly reduced oxidative stress) in the diclofenac treated groups, emerged as a major contributor for its ameliorative action. Findings of this study suggests, diclofenac can be used as an adjunct therapy in amelioration of drug-resistant epilepsy.

A phosphodiesterase 4 (PDE4) inhibitor, amlexanox, reduces neuroinflammation and neuronal death after pilocarpine-induced seizure

Epilepsy, a complex neurological disorder, is characterized by recurrent seizures caused by aberrant electrical activity in the brain. Central to this study is the role of lysosomal dysfunction in epilepsy, which can lead to the accumulation of toxic substrates and impaired autophagy in neurons. Our focus is on phosphodiesterase-4 (PDE4), an enzyme that plays a crucial role in regulating intracellular cyclic adenosine monophosphate (cAMP) levels by converting it into adenosine monophosphate (AMP). In pathological states, including epilepsy, increased PDE4 activity contributes to a decrease in cAMP levels, which may exacerbate neuroinflammatory responses. We hypothesized that amlexanox, an anti-inflammatory drug and non-selective PDE4 inhibitor, could offer neuroprotection by addressing lysosomal dysfunction and mitigating neuroinflammation, ultimately preventing neuronal death in epileptic conditions. Our research utilized a pilocarpine-induced epilepsy animal model to investigate amlexanox's potential benefits. Administered intraperitoneally at a dose of 100 ​mg/kg daily following the onset of a seizure, we monitored its effects on lysosomal function, inflammation, neuronal death, and cognitive performance in the brain. Tissue samples from various brain regions were collected at predetermined intervals for a comprehensive analysis. The study's results were significant. Amlexanox effectively improved lysosomal function, which we attribute to the modulation of zinc's influx into the lysosomes, subsequently enhancing autophagic processes and decreasing the release of inflammatory factors. Notably, this led to the attenuation of neuronal death in the hippocampal region. Additionally, cognitive function, assessed through the modified neurological severity score (mNSS) and the Barnes maze test, showed substantial improvements after treatment with amlexanox. These promising outcomes indicate that amlexanox has potential as a therapeutic agent in the treatment of epilepsy and related brain disorders. Its ability to combat lysosomal dysfunction and neuroinflammation positions it as a potential neuroprotective intervention. While these findings are encouraging, further research and clinical trials are essential to fully explore and validate the therapeutic efficacy of amlexanox in epilepsy management.

Inflammation and oxidative stress in epileptic children: from molecular mechanisms to clinical application of ketogenic diet

Childhood epilepsy affects up to 1 % of children. It has been shown that 30 % of patients are resistant to drug treatments, making further investigation of other potential treatment strategies necessary. One such approach is the ketogenic diet (KD) showing promising results and potential benefits beyond the use of current antiepileptic drugs. This study aims to investigate the effects of KD on inflammation and oxidative stress, as one of the main suggested mechanisms of neuroprotection, in children with epilepsy. This narrative review was conducted using the Medline and Google Scholar databases, and by searching epilepsy, drug-resistant epilepsy, child, children, ketogenic, ketogenic diet, diet, ketogenic, keto, ketone bodies (BHB), PUFA, gut microbiota, inflammation, inflammation mediators, neurogenic inflammation, neuroinflammation, inflammatory marker, adenosine modulation, mitochondrial function, MTOR pathway, Nrf2 pathway, mitochondrial dysfunction, PPARɣ, oxidative stress, ROS/RNS, and stress oxidative as keywords. Compelling evidence underscores inflammation and oxidative stress as pivotal factors in epilepsy, even in cases with genetic origins. The ketogenic diet effectively addresses these factors by reducing ROS and RNS, enhancing antioxidant defenses, improving mitochondrial function, and regulating inflammatory genes. Additionally, KD curbs pro-inflammatory cytokine and chemokine production by dampening NF-κB activation, inhibiting the NLRP3 inflammasome, increasing brain adenosine levels, mTOR pathway inhibition, upregulating PPARɣ expression, and promoting a healthy gut microbiota while emphasizing the consumption of healthy fats. KD could be considered a promising therapeutic intervention in patients with epilepsy particularly in drug-resistant epilepsy cases, due to its targeted approach addressing oxidative stress and inflammatory mechanisms.

Insights into epileptogenesis from post-traumatic epilepsy

Post-traumatic epilepsy (PTE) accounts for 5% of all epilepsies. The incidence of PTE after traumatic brain injury (TBI) depends on the severity of injury, approaching one in three in groups with the most severe injuries. The repeated seizures that characterize PTE impair neurological recovery and increase the risk of poor outcomes after TBI. Given this high risk of recurrent seizures and the relatively short latency period for their development after injury, PTE serves as a model disease to understand human epileptogenesis and trial novel anti-epileptogenic therapies. Epileptogenesis is the process whereby previously normal brain tissue becomes prone to recurrent abnormal electrical activity, ultimately resulting in seizures. In this Review, we describe the clinical course of PTE and highlight promising research into epileptogenesis and treatment using animal models of PTE. Clinical, imaging, EEG and fluid biomarkers are being developed to aid the identification of patients at high risk of PTE who might benefit from anti-epileptogenic therapies. Studies in preclinical models of PTE have identified tractable pathways and novel therapeutic strategies that can potentially prevent epilepsy, which remain to be validated in humans. In addition to improving outcomes after TBI, advances in PTE research are likely to provide therapeutic insights that are relevant to all epilepsies.

Exploring the chondroitin sulfate nanogel's potential in combating nephrotoxicity induced by cisplatin and doxorubicin-An in-vivo study on rats

In this study, we aim to unveil the potential of itaconyl chondroitin sulfate nanogel (ICSNG) in tackling chronic kidney diseases triggered by the administration of CDDP and doxorubicin (Adriamycin, ADR). To that end, the new drug delivery system (ICSNG) was initially prepared, characterized, and loaded with the target drugs. Thereafter, the in-vivo studies were performed using five equally divided groups of 100 male Sprague-Dawley (SD) rats. Biochemical evaluation and immunohistochemistry studies have revealed the renal toxicity and the ameliorative effects of ICSNG on renal function. When ICSNG-based treatments were contrasted with the CDDP and ADR infected groups, they significantly increased paraoxonase-1 (PON-1), superoxide dismutase (SOD), catalase (CAT) and albumin activity and significantly decreased nitric oxide (NO), tumor necrosis factor alpha (TNF-α), creatinine, urea, and cyclooxygenase-2 (COX-2) activity (p < 0.001). The findings of the current study imply that ICSNG may be able to lessen renal inflammation and damage in chronic kidney disorders brought on by the administration of CDDP and ADR. Interestingly, according to the estimated selectivity indices, the ICSNG-encapsulated drugs have demonstrated superior selectivity for cancer MCF-7 cells, over healthy HSF cells, in comparison to the bare drugs.

Neuroinflammation in epileptogenesis: from pathophysiology to therapeutic strategies

Epilepsy is a group of enduring neurological disorder characterized by spontaneous and recurrent seizures with heterogeneous etiology, clinical expression, severity, and prognosis. Growing body of research investigates that epileptic seizures are originated from neuronal synchronized and excessive electrical activity. However, the underlying molecular mechanisms of epileptogenesis have not yet been fully elucidated and 30% of epileptic patients still are resistant to the currently available pharmacological treatments with recurrent seizures throughout life. Over the past two decades years accumulated evidences provide strong support to the hypothesis that neuroinflammation, including microglia and astrocytes activation, a cascade of inflammatory mediator releasing, and peripheral immune cells infiltration from blood into brain, is associated with epileptogenesis. Meanwhile, an increasing body of preclinical researches reveal that the anti-inflammatory therapeutics targeting crucial inflammatory components are effective and promising in the treatment of epilepsy. The aim of the present study is to highlight the current understanding of the potential neuroinflammatory mechanisms in epileptogenesis and the potential therapeutic targets against epileptic seizures.

Neuroinflammation: The central enabler of postoperative cognitive dysfunction

The proportion of advanced age patients undergoing surgical procedures is on the rise owing to advancements in surgical and anesthesia technologies as well as an overall aging population. As a complication of anesthesia and surgery, older patients frequently suffer from postoperative cognitive dysfunction (POCD), which may persist for weeks, months or even longer. POCD is a complex pathological process involving multiple pathogenic factors, and its mechanism is yet unclear. Potential theories include inflammation, deposition of pathogenic proteins, imbalance of neurotransmitters, and chronic stress. The identification, prevention, and treatment of POCD are still in the exploratory stages owing to the absence of standardized diagnostic criteria. Undoubtedly, comprehending the development of POCD remains crucial in overcoming the illness. Neuroinflammation is the leading hypothesis and a crucial component of the pathological network of POCD and may have complex interactions with other mechanisms. In this review, we discuss the possible ways in which surgery and anesthesia cause neuroinflammation and investigate the connection between neuroinflammation and the development of POCD. Understanding these mechanisms may likely ensure that future treatment options of POCD are more effective.

Neuroimmunology of status epilepticus

Status epilepticus (SE) is a very heterogeneous clinical condition often refractory to available treatment options. Evidence in animal models shows that neuroinflammation arises in the brain during SE due to the activation of innate immune mechanisms in brain parenchyma cells. Intervention studies in animal models support the involvement of neuroinflammation in SE onset, duration, and severity, refractoriness to treatments, and long-term neurological consequences. Clinical evidence shows that neuroinflammation occurs in patients with SE of diverse etiologies likely representing a common phenomenon, thus broadening the involvement of the immune system beyond the infective and autoimmune etiologies. There is urgent need for novel therapies for refractory SE that rely upon a better understanding of the basic mechanisms underlying this clinical condition. Preclinical and clinical evidence encourage consideration of specific anti-inflammatory treatments for controlling SE and its consequences in patients.

Preclinical development of an EP2 antagonist for post-seizure cognitive deficits

Cognitive comorbidities can substantially reduce quality of life in people with epilepsy. Inflammation is a component of all chronic diseases including epilepsy, as well as acute events like status epilepticus (SE). Neuroinflammation is the consequence of several broad signaling cascades including cyclooxygenase-2 (COX-2)-associated pathways. Activation of the EP2 receptor for prostaglandin E2 appears responsible for blood-brain barrier leakage and much of the inflammatory reaction, neuronal injury and cognitive deficit that follows seizure-provoked COX-2 induction in brain. Here we show that brief exposure of mice to TG11-77, a potent, selective, orally available and brain permeant EP2 antagonist, eliminates the profound cognitive deficit in Y-maze performance after SE and reduces delayed mortality and microgliosis, with a minimum effective i.p. dose (as free base) of 8.8 mg/kg. All in vitro studies required to submit an investigational new drug (IND) application for TG11-77 have been completed, and non-GLP dose range-finding toxicology in the rat identified no overt, organ or histopathology signs of toxicity after 7 days of oral administration at 1000 mg/kg/day. Plasma exposure in the rat was dose-linear between 15 and 1000 mg/kg dosing. TG11-77 thus appears poised to continue development towards the initial clinical test of the hypothesis that EP2 receptor modulation after SE can provide the first preventive treatment for one of the chief comorbidities of epilepsy.

The Neuroprotective Effect Associated with Echinops spinosus in an Acute Seizure Model Induced by Pentylenetetrazole

Echinops spinosus (ES) is a medicinal plant with a wide range of pharmacological and biological effects. It is a medicinal herb having a variety of therapeutic characteristics, including antioxidant, anti-inflammatory, and antibacterial capabilities. The primary goal of this research is to investigate the neuroprotective and anticonvulsant characteristics of E. spinosa extract (ESE) against pentylenetetrazole (PTZ)-induced acute seizures. Negative control rats, ESE treatment rats, PTZ acute seizure model rats, ESE + PTZ rats, and Diazepam + PTZ rats were used in the study. The rats were given a 7-day treatment. ESE pretreatment elevated the latency to seizure onset and lowered seizure duration after PTZ injection. By reducing Bax levels and enhancing antiapoptotic Bcl-2 production, ESE prevented the release of interleukin-1β, tumor necrosis factor-α, and cyclooxygenase-2, as well as preventing hippocampal cell death after PTZ injection. ESE corrected the PTZ-induced imbalance in gamma-aminobutyric acid levels and increased the enzyme activity of Na⁺/K⁺-ATPase. Echinops spinosus is a potent neuromodulatory, antioxidant, antiinflammatory, and antiapoptotic plant that could be employed as a natural anticonvulsant in the future.

Caloric restriction: Anti-inflammatory and antioxidant mechanisms against epileptic seizures

Caloric restriction (CR) possesses different cellular mechanisms. Though there are still gaps in the literature regarding its plausible beneficial effects, the suggestion that this alternative therapy can improve the inflammatory and antioxidant response to control epileptic seizures is explored throughout this study. Epilepsy is the second most prevalent neurodegenerative disease in the world. However, the appropriate mechanisms for it to be fully controlled are still unknown. Neuroinflammation and oxidative stress promote epileptic seizures' appearance and might even aggravate them. There is growing evidence that caloric restriction has extensive anti-inflammatory and antioxidant properties. For instance, nuclear factor erythroid 2-related factor 2 (Nrf2) and all-trans retinoic acid (ATRA) have been proposed to induce antioxidant processes and ulteriorly improve the disease progression. Caloric restriction can be an option for those patients with refractory epilepsy since it allows for anti-inflammatory and antioxidant properties to evolve within the brain areas involved.

Distinct Cell-specific Roles of NOX2 and MyD88 in Epileptogenesis

It is well established that temporal lobe epilepsy (TLE) is often related to oxidative stress and neuroinflammation. Both processes subserve alterations observed in epileptogenesis and ultimately involve distinct classes of cells, including astrocytes, microglia, and specific neural subtypes. For this reason, molecules associated with oxidative stress response and neuroinflammation have been proposed as potential targets for therapeutic strategies. However, these molecules can participate in distinct intracellular pathways depending on the cell type. To illustrate this, we reviewed the potential role of nicotinamide adenine dinucleotide phosphate (NADPH) oxidase 2 (NOX2) and myeloid differentiation primary response 88 (MyD88) in astrocytes, microglia, and neurons in epileptogenesis. Furthermore, we presented approaches to study genes in different cells, employing single-cell RNA-sequencing (scRNAseq) transcriptomic analyses, transgenic technologies and viral serotypes carrying vectors with specific promoters. We discussed the importance of identifying particular roles of molecules depending on the cell type, endowing more effective therapeutic strategies to treat TLE.

Selenium Nanoparticles with Prodigiosin Rescue Hippocampal Damage Associated with Epileptic Seizures Induced by Pentylenetetrazole in Rats

BACKGROUND

Prodigiosin (PDG) is a red pigment synthesized by bacterial species with important pharmaceutical and biological activities. Here, we investigated the neuroprotective and anticonvulsant activities of green biosynthesized selenium formulations with PDG (SeNPs-PDG) versus pentylenetetrazole (PTZ)-induced epileptic seizures.

METHODS

Rats were assigned into six experimental groups: control; PTZ (60 mg/kg, epileptic model); sodium valproate (200 mg/kg) + PTZ; PDG (300 mg/kg) + PTZ; sodium selenite (0.5 mg/kg) + PTZ; and SeNPs-PDG (0.5 mg/kg) + PTZ. The treatment duration is extended to 28 days.

RESULTS

SeNPs-PDG pre-treatment delayed seizures onset and reduced duration upon PTZ injection. Additionally, SeNPs-PDG enhanced the antioxidant capacity of hippocampal tissue by activating the expression of nuclear factor erythroid 2-related factor 2 and innate antioxidants (glutathione and glutathione derivatives, in addition to superoxide dismutase and catalase) and decreasing the levels of pro-oxidants (lipoperoxidation products and nitric oxide). SeNPs-PDG administration inhibited inflammatory reactions associated with epileptic seizure development by suppressing the production and activity of glial fibrillary acidic protein and pro-inflammatory mediators, including interleukin-1 beta, tumor necrosis factor-alpha, cyclooxygenase-2, inducible nitric oxide synthase, and nuclear factor kappa B. Moreover, SeNPs-PDG protected against hippocampal cell loss following PTZ injection by decreasing the levels of cytosolic cytochrome c, Bax, and caspase-3 and enhancing the expression of anti-apoptotic Bcl-2. Interestingly, SeNPs-PDG restored the PTZ-induced imbalance between excitatory and inhibitory amino acids and improved monoaminergic and cholinergic transmission.

CONCLUSIONS

These promising antioxidative, anti-inflammatory, anti-apoptotic, and neuromodulatory activities indicate that SeNPs-PDG might serve as a naturally derived anticonvulsant agent.

Myeloid EP2 Receptors in Status Epilepticus-Peripheral But Not Negligible

Peripheral Myeloid Cell EP2 Activation Contributes to the Deleterious Consequences of Status Epilepticus

Varvel NH, Espinosa-Garcia C, Hunter-Chang S, Chen Di, Biegel A, Hsieh A, Blackmer-Raynolds L, Ganesh T, Dingledine R. J Neurosci. 2021;41(5):1105-1117. doi: 10.1523/JNEUROSCI.2040-20.2020

A multidimensional inflammatory response ensues after status epilepticus (SE), driven partly by cyclooxygenase-2-mediated activation of prostaglandin EP2 receptors. The inflammatory response is typified by astrocytosis, microgliosis, erosion of the blood–brain barrier (BBB), formation of inflammatory cytokines, and brain infiltration of blood-borne monocytes. Our previous studies have shown that inhibition of monocyte brain invasion or systemic administration of an EP2 receptor antagonist relieves multiple deleterious consequences of SE. Here, we identify those effects of EP2 antagonism that are reproduced by conditional ablation of EP2 receptors in immune myeloid cells and show that systemic EP2 antagonism blocks monocyte brain entry in male mice. The induction of hippocampal interleukin-6 after pilocarpine SE was nearly abolished in EP2 conditional knockout (KO) mice. Serum albumin levels in the cortex, a measure of BBB breakdown, were significantly higher after SE in EP2-sufficient mice but not in EP2 conditional KOs. The EP2 deficiency in innate immune cells accelerated the recovery from sickness behaviors following SE. Surprisingly, neurodegeneration was not alleviated in myeloid conditional KOs. Systemic EP2 antagonism prevented monocyte brain infiltration and provided broader rescue of SE-induced effects than myeloid EP2 ablation, including neuroprotection and broader suppression of inflammatory mediators. Reporter expression indicated that the cellular target of CD11b-driven Cre was circulating myeloid cells but, unexpectedly, not microglia. These findings indicate that activation of EP2 receptors on immune myeloid cells drives substantial deficits in behavior and disrupts the BBB after SE. The benefits of systemic EP2 antagonism can be attributed, in part, to blocking brain recruitment of blood-borne monocytes. SIGNIFICANCE STATEMENT Unabated seizures reduce quality of life, promote the development of epilepsy, and can be fatal. We previously identified activation of prostaglandin EP2 receptors as a driver of undesirable consequences of seizures. However, the relevant EP2-expressing cell types remain unclear. Here we identify peripheral innate immune cells as a driver of the EP2-related negative consequences of seizures. Removal of EP2 from peripheral immune cells was beneficial, abolishing production of a key inflammatory cytokine, accelerating weight regain, and limiting behavioral deficits. These findings provide evidence that EP2 engagement on peripheral immune and brain endothelia contributes to the deleterious effects of SE, and will assist in the development of beneficial therapies to enhance quality of life in individuals who suffer prolonged seizures.

Sleep Disruption Worsens Seizures: Neuroinflammation as a Potential Mechanistic Link

Sleep disturbances, such as insomnia, obstructive sleep apnea, and daytime sleepiness, are common in people diagnosed with epilepsy. These disturbances can be attributed to nocturnal seizures, psychosocial factors, and/or the use of anti-epileptic drugs with sleep-modifying side effects. Epilepsy patients with poor sleep quality have intensified seizure frequency and disease progression compared to their well-rested counterparts. A better understanding of the complex relationship between sleep and epilepsy is needed, since approximately 20% of seizures and more than 90% of sudden unexpected deaths in epilepsy occur during sleep. Emerging studies suggest that neuroinflammation, (e.g., the CNS immune response characterized by the change in expression of inflammatory mediators and glial activation) may be a potential link between sleep deprivation and seizures. Here, we review the mechanisms by which sleep deprivation induces neuroinflammation and propose that neuroinflammation synergizes with seizure activity to worsen neurodegeneration in the epileptic brain. Additionally, we highlight the relevance of sleep interventions, often overlooked by physicians, to manage seizures, prevent epilepsy-related mortality, and improve quality of life.

Impact of drug treatment and drug interactions in post-stroke epilepsy

Stroke is a huge burden on our society and this is expected to grow in the future due to the aging population and the associated co-morbidities. The improvement of acute stroke care has increased the survival rate of stroke patients, and many patients are left with permanent disability, which makes stroke the main cause of adult disability. Unfortunately, many patients face other severe complications such as post-stroke seizures and epilepsy. Acute seizures (ASS) occur within 1 week after the stroke while later occurring unprovoked seizures are diagnosed as post-stroke epilepsy (PSE). Both are associated with a poor prognosis of a functional recovery. The underlying neurobiological mechanisms are complex and poorly understood. There are no universal guidelines on the management of PSE. There is increasing evidence for several risk factors for ASS/PSE, however, the impacts of recanalization, drugs used for secondary prevention of stroke, treatment of stroke co-morbidities and antiseizure medication are currently poorly understood. This review focuses on the common medications that stroke patients are prescribed and potential drug interactions possibly complicating the management of ASS/PSE.

EP2 Antagonists (2011-2021): A Decade's Journey from Discovery to Therapeutics

In the wake of health disasters associated with the chronic use of cyclooxygenase-2 (COX-2) inhibitor drugs, it has been widely proposed that modulation of downstream prostanoid synthases or receptors might provide more specificity than simply shutting down the entire COX cascade for anti-inflammatory benefits. The pathogenic actions of COX-2 have long been thought attributable to the prostaglandin E2 (PGE2) signaling through its Gαs-coupled EP2 receptor subtype; however, the truly selective EP2 antagonists did not emerge until 2011. These small molecules provide game-changing tools to better understand the EP2 receptor in inflammation-associated conditions. Their applications in preclinical models also reshape our knowledge of PGE2/EP2 signaling as a node of inflammation in health and disease. As we celebrate the 10-year anniversary of this breakthrough, the exploration of their potential as drug candidates for next-generation anti-inflammatory therapies has just begun. The first decade of EP2 antagonists passes, while their future looks brighter than ever.

Deciphering the mechanisms of regulation of an excitatory synapse via cyclooxygenase-2. A review

Cyclooxygenase (COX) is a heme-containing enzyme that produces prostaglandins (PGs) via a pathway known as the arachidonic acid (AA) cascade. Two isoforms of COX enzyme (COX-1 and COX-2) and splice variant (COX-3) have been described so far. COX-2 is a neuronal enzyme that is intensively produced during activation of the synapse and glutamate (Glu) release. The end product of COX-2 action, prostaglandin E2 (PGE2), regulates Glu level in a retrograde manner. At the same time, the level of Glu, the primary excitatory neurotransmitter, is regulated in the excitatory synapse via Glu receptors, both ionotropic and metabotropic ones. Glu receptors are known modulators of behavior, engaged in cognition and mood. So far, the interaction between ionotropic N-methyl-D-aspartate (NMDA) receptors or metabotropic glutamate (mGluRs) receptors and COX-2 was found. Here, based on literature data and own research, a new mechanism of action of COX-2 in an excitatory synapse will be presented.

A Novel Second-Generation EP2 Receptor Antagonist Reduces Neuroinflammation and Gliosis After Status Epilepticus in Rats

Prostaglandin-E2 (PGE2), an important mediator of inflammation, achieves its functions via four different G protein-coupled receptors (EP1, EP2, EP3, and EP4). We previously demonstrated that the EP2 receptor plays a proinflammatory and neurodegenerative role after status epilepticus (SE). We recently developed TG8-260 as a second-generation highly potent and selective EP2 antagonist. Here, we investigate whether TG8-260 is anti-inflammatory and combats neuropathology caused by pilocarpine-induced SE in rats. Adult male Sprague-Dawley rats were injected subcutaneously with pilocarpine (380-400 mg/kg) to induce SE. Following 60 min of SE, the rats were administered three doses of TG8-260 or vehicle and were allowed to recover. Neurodegeneration, neuroinflammation, gliosis, and blood-brain barrier (BBB) integrity were examined 4 days after SE. The results confirmed that pilocarpine-induced SE results in hippocampal neurodegeneration and a robust inflammatory response that persists days after SE. Furthermore, inhibition of the EP2 receptor by TG8-260 administered beginning 2 h after SE significantly reduced hippocampal neuroinflammation and gliosis but, in distinction to the earlier generation EP2 antagonist, did not mitigate neuronal injury or BBB breakdown. Thus, attenuation of neuroinflammation and gliosis is a common feature of EP2 inhibition following SE.

Regulation of post-ischemic inflammatory response: A novel function of the neuronal tyrosine phosphatase STEP

The neuron-specific tyrosine phosphatase STEP is emerging as a key neuroprotectant against acute ischemic stroke. However, it remains unclear how STEP impacts the outcome of stroke. We find that the exacerbation of ischemic brain injury in STEP deficient mice involves an early onset and sustained activation of neuronal p38 mitogen activated protein kinase, a substrate of STEP. This leads to rapid increase in the expression of neuronal cyclooxygenase-2 and synthesis of prostaglandin E₂, causing change in microglial morphology to an amoeboid activated state, activation of matrix metalloproteinase-9, cleavage of tight junction proteins and extravasation of IgG into the ischemic brain. Restoration of STEP signaling with intravenous administration of a STEP-derived peptide mimetic reduces the post-ischemic inflammatory response and attenuates brain injury. The findings identify a unique role of STEP in regulating post-ischemic neuroinflammation and further emphasizes the therapeutic potential of the STEP-mimetic in neurological disorders where inflammation contributes to brain damage.

Cannabidiol and Neurodevelopmental Disorders in Children

Neurodevelopmental and neuropsychiatric disorders (such as autism spectrum disorder) have broad health implications for children, with no definitive cure for the vast majority of them. However, recently medicinal cannabis has been successfully trialled as a treatment to manage many of the patients' symptoms and improve quality of life. The cannabinoid cannabidiol, in particular, has been reported to be safe and well-tolerated with a plethora of anticonvulsant, anxiolytic and anti-inflammatory properties. Lately, the current consensus is that the endocannabinoid system is a crucial factor in neural development and health; research has found evidence that there are a multitude of signalling pathways involving neurotransmitters and the endocannabinoid system by which cannabinoids could potentially exert their therapeutic effects. A better understanding of the cannabinoids' mechanisms of action should lead to improved treatments for neurodevelopmental disorders.

Peripheral Myeloid Cell EP2 Activation Contributes to the Deleterious Consequences of Status Epilepticus

A multidimensional inflammatory response ensues after status epilepticus (SE), driven partly by cyclooxygenase-2-mediated activation of prostaglandin EP2 receptors. The inflammatory response is typified by astrocytosis, microgliosis, erosion of the blood-brain barrier (BBB), formation of inflammatory cytokines, and brain infiltration of blood-borne monocytes. Our previous studies have shown that inhibition of monocyte brain invasion or systemic administration of an EP2 receptor antagonist relieves multiple deleterious consequences of SE. Here we identify those effects of EP2 antagonism that are reproduced by conditional ablation of EP2 receptors in immune myeloid cells and show that systemic EP2 antagonism blocks monocyte brain entry in male mice. The induction of hippocampal IL-6 after pilocarpine SE was nearly abolished in EP2 conditional KO mice. Serum albumin levels in the cortex, a measure of BBB breakdown, were significantly higher after SE in EP2-sufficient mice but not in EP2 conditional KOs. EP2 deficiency in innate immune cells accelerated the recovery from sickness behaviors following SE. Surprisingly, neurodegeneration was not alleviated in myeloid conditional KOs. Systemic EP2 antagonism prevented monocyte brain infiltration and provided broader rescue of SE-induced effects than myeloid EP2 ablation, including neuroprotection and broader suppression of inflammatory mediators. Reporter expression indicated that the cellular target of CD11b-driven Cre was circulating myeloid cells but, unexpectedly, not microglia. These findings indicate that activation of EP2 receptors on immune myeloid cells drives substantial deficits in behavior and disrupts the BBB after SE. The benefits of systemic EP2 antagonism can be attributed, in part, to blocking brain recruitment of blood-borne monocytes.SIGNIFICANCE STATEMENT Unabated seizures reduce quality of life, promote the development of epilepsy, and can be fatal. We previously identified activation of prostaglandin EP2 receptors as a driver of undesirable consequences of seizures. However, the relevant EP2-expressing cell types remain unclear. Here we identify peripheral innate immune cells as a driver of the EP2-related negative consequences of seizures. Removal of EP2 from peripheral immune cells was beneficial, abolishing production of a key inflammatory cytokine, accelerating weight regain, and limiting behavioral deficits. These findings provide evidence that EP2 engagement on peripheral immune and brain endothelia contributes to the deleterious effects of SE, and will assist in the development of beneficial therapies to enhance quality of life in individuals who suffer prolonged seizures.

The role of inflammation in epileptogenesis

Epilepsy is a chronic neurological disorder that has an extensive impact on a patient’s life. Accumulating evidence has suggested that inflammation participates in the progression of spontaneous and recurrent seizures. Pro-convulsant incidences can stimulate immune cells, augment the release of pro-inflammatory cytokines, elicit neuronal excitation as well as blood-brain barrier (BBB) dysfunction, and finally trigger the generation or recurrence of seizures. Understanding the pathogenic roles of inflammatory mediators, including inflammatory cytokines, cells, and BBB, in epileptogenesis will be beneficial for the treatment of epilepsy. In this systematic review, we performed a literature search on the PubMed database using the following keywords: “epilepsy” or “seizures” or “epileptogenesis”, and “immunity” or “inflammation” or “neuroinflammation” or “damage-associated molecular patterns” or “cytokines” or “chemokines” or “adhesion molecules” or “microglia” or “astrocyte” or “blood-brain barrier”. We summarized the classic inflammatory mediators and their pathogenic effects in the pathogenesis of epilepsy, based on the most recent findings from both human and animal model studies.

5xFAD Mice Display Sex-Dependent Inflammatory Gene Induction During the Prodromal Stage of Alzheimer's Disease

Alzheimer's disease (AD) pathology consists of extracellular deposits of amyloid-β peptides (Aβ) and intracellular neurofibrillary tangles. These pathological alterations are accompanied by a neuroinflammatory response consisting of increased expression of inflammatory mediators. An anti-inflammatory strategy designed to prevent or delay the development of AD would benefit from knowing when neuroinflammation appears in the transgenic models during prodromal disease stages relative to Aβ pathology. We investigated the expression patterns of inflammatory mediators in the brain of 5xFAD mice in comparison to development of Aβ deposition. Expression changes in inflammatory mediators and glial markers are more robust in female mice starting at three months of age, in contrast to males in which there is no clear trend through five months. Female and male 5xFAD mice also displayed an age-dependent increase in cortical Aβ deposition congruent with neuroinflammation. Thus, in the 5xFAD mouse model of AD, administration of an anti-inflammatory agent would be most efficacious when administered before three months of age.

Seizures elevate gliovascular unit Ca2+ and cause sustained vasoconstriction

Seizures can result in a severe hypoperfusion/hypoxic attack that causes postictal memory and behavioral impairments. However, neither postictal changes to microvasculature nor Ca²⁺ changes in key cell types controlling blood perfusion have been visualized in vivo, leaving essential components of the underlying cellular mechanisms unclear. Here, we use 2-photon microvascular and Ca²⁺ imaging in awake mice to show that seizures result in a robust vasoconstriction of cortical penetrating arterioles, which temporally mirrors the prolonged postictal hypoxia. The vascular effect was dependent on cyclooxygenase 2, as pretreatment with ibuprofen prevented postictal vasoconstriction. Moreover, seizures caused a rapid elevation in astrocyte endfoot Ca²⁺ that was confined to the seizure period, and vascular smooth muscle cells displayed a significant increase in Ca²⁺ both during and following seizures, lasting up to 75 minutes. Our data show enduring postictal vasoconstriction and temporal activities of 2 cell types within the neurovascular unit that are associated with seizure-induced hypoperfusion/hypoxia. These findings support prevention of this event may be a novel and tractable treatment strategy in patients with epilepsy who experience extended postseizure impairments.

Seizures cause enduring microvascular constriction via long lasting calcium elevations in vascular smooth muscle cells.

Inhibition of the prostaglandin EP2 receptor prevents long-term cognitive impairment in a model of systemic inflammation

Long-term cognitive and affective impairments are common problems in the survivors of sepsis, which weakens their vocational and daily life ability. Neuroinflammation has been reported to exert a key role in the development of cognitive deficit in different disorders including epilepsy, Alzheimer's disease (AD) and stroke. Mice treated with lipopolysaccharide (LPS), an endotoxin produced by gram-negative bacteria, show a robust but short-lived neuroinflammation and develop long-term memory and affective problems. In this study, we test the hypothesis that pharmacological blockade of the EP2 receptor for prostaglandin E2 reduces neuroinflammation and prevents long-term affective and memory deficits in a mouse model of LPS-induced, sepsis-associated encephalopathy (SAE). Our results show that an EP2 antagonist, TG6-10-1, promotes the recovery of body weight, mitigates neuroinflammation as judged by inflammatory cytokines and microgliosis, prevents the loss of synaptic proteins, and ameliorates depression-like behavior in the sucrose preference test as well as memory loss in the novel object recognition test. Our results point to a new avenue to ameliorate neuroinflammation and long-term affective and cognition problems of sepsis survivors.

Ibuprofen Exerts Antiepileptic and Neuroprotective Effects in the Rat Model of Pentylenetetrazol-Induced Epilepsy via the COX-2/NLRP3/IL-18 Pathway

Epilepsy is one of the most common diseases of the central nervous system. Recent studies have shown that a variety of inflammatory mediators play a key role in the pathogenesis of the disease. Ibuprofen (IBP) is a well-known anti-inflammatory agent that reduces the neuroinflammatory response and neuronal damage. In this study, we examined the effect of IBP in a rat model of pentylenetetrazol (PTZ)-induced chronic epilepsy. PTZ injection was given a total of 15 times on alternate days (over a period of 29 days) to induce epilepsy. The effects of IBP were evaluated by behavioral observation, EEG recording, Nissl staining, immunohistochemistry, Western blot analysis, and electrophysiological recording. The results showed that IBP alone affected the expression of cyclooxygenase-2 (COX-2) and neuronal excitability but did not cause epilepsy. IBP reduced seizure scores in the PTZ-treated rats, and it minimized the loss of hippocampal neurons. In addition, IBP decreased the secretion of COX-2, inhibited the activation of the NOD-like receptor 3 inflammasome, and reduced the secretion of the inflammatory cytokine interleukin-18. Furthermore, the results of whole-cell patch-clamp revealed that IBP affected action potential properties, including frequency, latency and duration in epileptic rats, suggesting that it may impact neuronal excitability. These effects of IBP may underlie its antiepileptic and neuroprotective actions.

Modulating neuroinflammation and oxidative stress to prevent epilepsy and improve outcomes after traumatic brain injury

Traumatic brain injury (TBI) is a leading cause of death and disability in young adults worldwide. TBI survival is associated with persistent neuropsychiatric and neurological impairments, including posttraumatic epilepsy (PTE). To date, no pharmaceutical treatment has been found to prevent PTE or ameliorate neurological/neuropsychiatric deficits after TBI. Brain trauma results in immediate mechanical damage to brain cells and blood vessels that may never be fully restored given the limited regenerative capacity of brain tissue. This primary insult unleashes cascades of events, prominently including neuroinflammation and massive oxidative stress that evolve over time, expanding the brain injury, but also clearing cellular debris and establishing homeostasis in the region of damage. Accumulating evidence suggests that oxidative stress and neuroinflammatory sequelae of TBI contribute to posttraumatic epileptogenesis. This review will focus on possible roles of reactive oxygen species (ROS), their interactions with neuroinflammation in posttraumatic epileptogenesis, and emerging therapeutic strategies after TBI. We propose that inhibitors of the professional ROS-generating enzymes, the NADPH oxygenases and myeloperoxidase alone, or combined with selective inhibition of cyclooxygenase mediated signaling may have promise for the treatment or prevention of PTE and other sequelae of TBI. This article is part of the special issue entitled 'New Epilepsy Therapies for the 21st Century - From Antiseizure Drugs to Prevention, Modification and Cure of Epilepsy'.

Beneficial Effects of Ibuprofen on Pentylenetetrazol-induced Convulsion

Ibuprofen is a non-steroidal anti-inflammatory drug (NSAID) that is commonly used as an anti-inflammatory, anti-pyretic, and analgesic. Although some studies have focused on the anti-inflammatory and anti-pyretic properties of ibuprofen during febrile convulsions, only one has investigated its antiepileptic effects. In the present study, we aimed to investigate the effects of ibuprofen in rats exposed to pentylenetetrazol (PTZ)-induced seizures. In total, 48 rats were randomly divided in two groups: Group A for electroencephalography (EEG) recordings and Group B for behavioral assessment. All EEG recordings and behavioral assessment protocols were performed. In addition, groups were compared in terms of prostaglandin F2 alfa (PGF2α) levels in the brain. We demonstrated the beneficial effects of the administration of ibuprofen in PTZ-induced seizures in rats via the following findings: spike percentages and Racine convulsion scale values were significantly lower and first myoclonic jerk (FMJ) onset times were significantly higher in the ibuprofen-administered groups. Moreover, PGF2α levels in the brain were significantly higher in the saline and PTZ 70 mg/kg group than in the control and PTZ 70 mg/kg and 400 mg/kg ibuprofen groups. Our study is the first to demonstrate the beneficial effects of ibuprofen on seizures through behavioral, EEG, and PGF2α brain assessments. Ibuprofen can be used for epilepsy and febrile seizures safely and without inducing seizures. However, further experimental and clinical studies are needed to confirm our results.

COX-2-PGE2 signaling pathway contributes to hippocampal neuronal injury and cognitive impairment in PTZ-kindled epilepsy mice

Epilepsy is one of the most common neurological diseases. It adversely affects cognitive function. Neuroinflammation has been widely recognized as an important factor involved in the pathophysiology of epilepsy. Cyclooxygenase (COX) is a type of oxidoreductase enzyme that acts in the metabolic pathway converting arachidonic acid to prostaglandins, which mediate inflammatory reactions. The activation of inducible cyclooxygenase-2 (COX-2) is considered to be a precipitating factor of neuroinflammation in the brain. Neuroinflammatory processes in the brain are known to contribute to the cascade of events leading to neuronal injury, which may consequently cause cognitive decline. Here in this study, we showed that pentylenetetrazole (PTZ)-kindled mice exhibited an increased level of COX-2 and its main product prostaglandin E2 (PGE₂) along with neuroinflammation and neuronal injury in the hippocampus. Pharmacological inhibition of COX-2 by celecoxib, however, significantly reduced hippocampal neuroinflammation and neuronal injury. Furthermore, inhibition of COX-2 by celecoxib attenuated cognitive impairment in the PTZ-kindled mice, suggesting that COX-2-PGE₂ signaling pathway mediated neuroinflammation and neuronal injury contributes to cognitive dysfunction in the PTZ-kindled epilepsy mice. Targeting COX-2-PGE₂ signaling pathway in the epileptic brain appears to be a viable strategy for attenuating neuronal injury and preventing cognitive deficits in epilepsy patients.

Neuroinflammation impact in epileptogenesis and new treatment strategy

Epilepsy is considered a major serious chronic neurological disorder, characterized by recurrent seizures. It is usually associated with a history of a lesion in the nervous system. Irregular activation of inflammatory molecules in the injured tissue is an important factor in the development of epilepsy. It is unclear how the imbalanced regulation of inflammatory mediators contributes to epilepsy. A recent research goal is to identify interconnected inflammation pathways which may be involved in the development of epilepsy. The clinical use of available antiepileptic drugs is often restricted by their limitations, incidence of several side effects, and drug interactions. So development of new drugs, which modulate epilepsy through novel mechanisms, is necessary. Alternative therapies and diet have recently reported positive treatment outcomes in epilepsy. Vitamin D (Vit D) has shown prophylactic and therapeutic potential in different neurological disorders. So, the aim of current study was to review the associations between different brain inflammatory mediators and epileptogenesis, to strengthen the idea that targeting inflammatory pathway may be an effective therapeutic strategy to prevent or treat epilepsy. In addition, neuroprotective effects and mechanisms of Vit D in clinical and preclinical studies of epilepsy were reviewed.

Targeting prostaglandin receptor EP2 for adjunctive treatment of status epilepticus

Status epilepticus (SE) is an emergency condition that can cause permanent brain damage or even death when generalized convulsive seizures last longer than 30 min. Controlling the escalation and propagation of seizures quickly and properly is crucial to the prevention of irreversible neuronal death and the associated morbidity. However, SE often becomes refractory to current anticonvulsant medications, which primarily act on ion channels and commonly impose undesired effects. Identifying new molecular targets for SE might lead to adjunctive treatments that can be delivered even when SE is well established. Recent preclinical studies suggest that prostaglandin E2 (PGE₂) is an essential inflammatory mediator for the brain injury and morbidity following prolonged seizures via activating four G protein-coupled receptors, namely, EP1-EP4. Given that EP2 receptor activation has been identified as a common culprit in several inflammation-associated neurological conditions, such as strokes and neurodegenerative diseases, selective small-molecule antagonists targeting EP2 have been recently developed and utilized to suppress PGE₂-mediated neuroinflammation. Transient inhibition of the EP2 receptor by these bioavailable and brain-permeable antagonists consistently showed marked anti-inflammatory and neuroprotective effects in several rodent models of SE yet had no noticeable effect on seizures per se. This review provides overviews and perspectives of the EP2 receptor as an emerging target for adjunctive treatment, together with the current first-line anti-seizure drugs, to prevent acute brain inflammation and damage following SE.

Potent, Selective, Water Soluble, Brain-Permeable EP2 Receptor Antagonist for Use in Central Nervous System Disease Models

Activation of prostanoid EP2 receptor exacerbates neuroinflammatory and neurodegenerative pathology in central nervous system diseases such as epilepsy, Alzheimer's disease, and cerebral aneurysms. A selective and brain-permeable EP2 antagonist will be useful to attenuate the inflammatory consequences of EP2 activation and to reduce the severity of these chronic diseases. We recently developed a brain-permeable EP2 antagonist 1 (TG6-10-1), which displayed anti-inflammatory and neuroprotective actions in rodent models of status epilepticus. However, this compound exhibited moderate selectivity to EP2, a short plasma half-life in rodents (1.7 h) and low aqueous solubility (27 μM), limiting its use in animal models of chronic disease. With lead-optimization studies, we have developed several novel EP2 antagonists with improved water solubility, brain penetration, high EP2 potency, and selectivity. These novel inhibitors suppress inflammatory gene expression induced by EP2 receptor activation in a microglial cell line, reinforcing the use of EP2 antagonists as anti-inflammatory agents.

The Role of NLRP3 and IL-1β in Refractory Epilepsy Brain Injury

Objective: The objective of this study was to investigate the roles and mechanisms of inflammatory mediators NLRP3 and IL-1β in refractory temporal epilepsy brain injury.

Method: First, the brain tissue and the peripheral blood of children undergoing intractable temporal lobe epilepsy surgery were analyzed as research objects. The expression levels of NLRP3 in brain tissue and IL-1β in blood were measured. A model of temporal lobe epilepsy was established using wild-type and NLRP3 knockout 129 mice. Pilocarpine was injected intraperitoneally into the experimental group, and isovolumetric saline was injected intraperitoneally into the control group (n = 8 in each group). The expression of IL-1β in the peripheral blood, cerebral cortex, and hippocampus of mice was measured by ELISA at 3 h, 24 h, 3 days, and 7 days after modeling. Fluoro-Jade B (FJB) and TUNEL methods were used to determine necrosis and apoptosis in hippocampal neurons, respectively, and the expression of NLRP3 in the cortex was measured by immunofluorescence methods.

Result: (1) The IL-1β levels in the peripheral blood of children with intractable temporal lobe epilepsy were higher than those in the control group (t = 2.813, P = 0.01). There was also a positive correlation between IL-1β expression levels and the onset time of a single convulsion in patients with refractory epilepsy (r = 0.9735, P < 0.05). The expression level of NLRP3 in the cerebral cortex of patients with refractory temporal lobe epilepsy was higher than that in the control group. (2) The expression level of NLRP3 in the hippocampus of wild-type mice increased 3 days after modeling and decreased slightly at 7 days but remained higher than that of the control group. IL-1β levels in peripheral blood were significantly higher than those in the control group at 3 days (t = 8.259, P < 0.0001). The IL-1β levels in the peripheral blood of NLRP3 knockout mice were lower than those in the wild-type group at 3 days (t = 3.481, P = 0.004). At day 7, the neuronal necrosis and apoptosis levels in the CA3 region of the hippocampus decreased.

Conclusion: NLRP3 may be involved in the development of refractory temporal lobe epilepsy. Inhibiting NLRP3 may alleviate local brain injury by downregulating the IL-1β expression. The IL-1β levels in the peripheral blood of patients with refractory temporal lobe epilepsy may reflect the severity of convulsions.

A rat model of organophosphate-induced status epilepticus and the beneficial effects of EP2 receptor inhibition

This review describes an adult rat model of status epilepticus (SE) induced by diisopropyl fluorophosphate (DFP), and the beneficial outcomes of transient inhibition of the prostaglandin-E2 receptor EP2 with a small molecule antagonist, delayed by 2-4 h after SE onset. Administration of six doses of the selective EP2 antagonist TG6-10-1 over a 2-3 day period accelerates functional recovery, attenuates hippocampal neurodegeneration, neuroinflammation, gliosis and blood-brain barrier leakage, and prevents long-term cognitive deficits without blocking SE itself or altering acute seizure characteristics. This work has provided important information regarding organophosphate-induced seizure related pathologies in adults and revealed the effectiveness of delayed EP2 inhibition to combat these pathologies.

The Interplay between the Endocannabinoid System, Epilepsy and Cannabinoids

Epilepsy is a neurological disorder that affects approximately 50 million people worldwide. There is currently no definitive epilepsy cure. However, in recent years, medicinal cannabis has been successfully trialed as an effective treatment for managing epileptic symptoms, but whose mechanisms of action are largely unknown. Lately, there has been a focus on neuroinflammation as an important factor in the pathology of many epileptic disorders. In this literature review, we consider the links that have been identified between epilepsy, neuroinflammation, the endocannabinoid system (ECS), and how cannabinoids may be potent alternatives to more conventional pharmacological therapies. We review the research that demonstrates how the ECS can contribute to neuroinflammation, and could therefore be modulated by cannabinoids to potentially reduce the incidence and severity of seizures. In particular, the cannabinoid cannabidiol has been reported to have anti-convulsant and anti-inflammatory properties, and it shows promise for epilepsy treatment. There are a multitude of signaling pathways that involve endocannabinoids, eicosanoids, and associated receptors by which cannabinoids could potentially exert their therapeutic effects. Further research is needed to better characterize these pathways, and consequently improve the application and regulation of medicinal cannabis.

Novel Microglia Cell Line Expressing the Human EP2 Receptor

Recently, EP2 signaling pathways were shown to regulate the classical activation and death of microglia in rat primary microglial culture. The study of microglial cells has been challenging because they are time-consuming to isolate in culture, they are demanding in their growth requirements, and they have a limited lifespan. To circumvent these difficulties, we created a murine BV2 microglial cell line stably expressing human EP2 receptors (BV2-hEP2) and further explored EP2 modulation of microglial functions. The BV2-hEP2 cells displayed cAMP elevation when exposed to the selective EP2 receptor agonists (ONO-AE1-259-1 and CP544326), and this response was competitively inhibited by TG4-155, a selective EP2 antagonist (Schild K_B = 2.6 nM). By contrast, untransfected BV2 cells were unresponsive to selective EP2 agonists. Similar to the case of rat primary microglia, BV2-hEP2 microglia treated with lipopolysaccharide (LPS) (100 ng/mL) displayed rapid and robust induction of the inflammatory mediators COX-2, IL-1β, TNFα, and IL-6. EP2 activation depressed TNFα induction but exacerbated that of the other inflammatory mediators. Like primary microglia, classically activated BV2 microglia phagocytose fluorescent-labeled latex microspheres. The presence of EP2, but not its activation by agonists, in BV2-hEP2 microglia reduced phagocytosis and proliferation by 65% and 32%, respectively, compared to BV2 microglia. Thus, BV2-hEP2 is the first microglial cell line that retains the EP2 modulation of immune regulation and phagocytic ability of native microglia. Suppression of phagocytosis by the EP2 protein appears unrelated to classical EP2 signaling pathways, which has implications for therapeutic development of EP2 antagonists.

G protein-coupled receptors in acquired epilepsy: Druggability and translatability

As the largest family of membrane proteins in the human genome, G protein-coupled receptors (GPCRs) constitute the targets of more than one-third of all modern medicinal drugs. In the central nervous system (CNS), widely distributed GPCRs in neuronal and nonneuronal cells mediate numerous essential physiological functions via regulating neurotransmission at the synapses. Whereas their abnormalities in expression and activity are involved in various neuropathological processes. CNS conditions thus remain highly represented among the indications of GPCR-targeted agents. Mounting evidence from a large number of animal studies suggests that GPCRs play important roles in the regulation of neuronal excitability associated with epilepsy, a common CNS disease afflicting approximately 1-2% of the population. Surprisingly, none of the US Food and Drug Administration (FDA)-approved (>30) antiepileptic drugs (AEDs) suppresses seizures through acting on GPCRs. This disparity raises concerns about the translatability of these preclinical findings and the druggability of GPCRs for seizure disorders. The currently available AEDs intervene seizures predominantly through targeting ion channels and have considerable limitations, as they often cause unbearable adverse effects, fail to control seizures in over 30% of patients, and merely provide symptomatic relief. Thus, identifying novel molecular targets for epilepsy is highly desired. Herein, we focus on recent progresses in understanding the comprehensive roles of several GPCR families in seizure generation and development of acquired epilepsy. We also dissect current hurdles hindering translational efforts in developing GPCRs as antiepileptic and/or antiepileptogenic targets and discuss the counteracting strategies that might lead to a potential cure for this debilitating CNS condition.

The Neuroprotective Effect of Astaxanthin on Pilocarpine-Induced Status Epilepticus in Rats

Cognitive dysfunction is one of the serious complications induced by status epilepticus (SE), which has a significant negative impact on patients’ quality of life. Previous studies demonstrated that the pathophysiological changes after SE such as oxidative stress, inflammatory reaction contribute to neuronal damage. A recent study indicated that preventive astaxanthin (AST) alleviated epilepsy-induced oxidative stress and neuronal apoptosis in the brain. In the present study, rats were treated with vehicle or AST 1 h after SE onset and were injected once every other day for 2 weeks (total of seven times). The results showed that the cognitive function in SE rats was significantly impaired, and AST treatment improved cognitive function in the Morris water maze (MWM). Magnetic resonance imaging (MRI), hematoxylin-eosin (HE) staining and TdT-mediated dUTP Nick-End Labeling (TUNEL) staining showed obvious damage in the hippocampus of SE rats, and AST alleviated the damage. Subsequently, we evaluated the effect of AST on relative pathophysiology to elucidate the possible mechanisms. To evaluate the oxidative stress, the expression of malondialdehyde (MDA) and superoxide dismutase (SOD) in plasma were detected using commercially available kits. NADPH oxidase-4 (Nox-4), p22phox, NF-E2-related factor 2 (Nrf-2), heme oxygenase 1 (Ho-1) and sod1 in the parahippocampal cortex and hippocampus were detected using western blot and real-time polymerase chain reaction (RT-PCR). The levels of MDA in plasma and Nox-4 and p22phox in the brain increased in SE rats, and the levels of SOD in plasma and Nrf-2, Ho-1 and sod1 in the brain decreased. Treatment with AST alleviated these changes. We also detected the levels of inflammatory mediators like cyclooxygenase-2 (cox-2), interleukin-1β (IL-1β), tumor necrosis factor-α (TNF-α) and NF-κB phosphorylation p65 (p-p65)/p65 in the brain. The inflammatory reaction was significantly activated in the brain of SE rats, and AST alleviated neuroinflammation. We detected the levels of p-Akt, Akt, B-cell lymphoma-2 (Bcl-2), Bax, cleaved caspase-3, and caspase-3 in the parahippocampal cortex and hippocampus using western blot. The levels of p-Akt/Akt and Bcl-2 decreased in SE rats, Bax and cleaved caspase-3/caspase-3 increased, while AST alleviated these changes. The present study indicated that AST exerted an reobvious neuroprotective effect in pilocarpine-induced SE rats.

Resolving the Micro-Macro Disconnect to Address Core Features of Seizure Networks

Current drug treatments for epilepsy attempt to broadly restrict excitability to mask a symptom, seizures, with little regard for the heterogeneous mechanisms that underlie disease manifestation across individuals. Here, we discuss the need for a more complete view of epilepsy, outlining how key features at the cellular and microcircuit level can significantly impact disease mechanisms that are not captured by the most common methodology to study epilepsy, electroencephalography (EEG). We highlight how major advances in neuroscience tool development now enable multi-scale investigation of fundamental questions to resolve the currently controversial understanding of seizure networks. These findings will provide essential insight into what has emerged as a disconnect between the different levels of investigation and identify new targets and treatment options.

In search of antiepileptogenic treatments for post-traumatic epilepsy

Post-traumatic epilepsy (PTE) is diagnosed in 20% of individuals with acquired epilepsy, and can impact significantly the quality of life due to the seizures and other functional or cognitive and behavioral outcomes of the traumatic brain injury (TBI) and PTE. There is no available antiepileptogenic or disease modifying treatment for PTE. Animal models of TBI and PTE have been developed, offering useful insights on the value of inflammatory, neurodegenerative pathways, hemorrhages and iron accumulation, calcium channels and other target pathways that could be used for treatment development. Most of the existing preclinical studies test efficacy towards pathologies of functional recovery after TBI, while a few studies are emerging testing the effects towards induced or spontaneous seizures. Here we review the existing preclinical trials testing new candidate treatments for TBI sequelae and PTE, and discuss future directions for efforts aiming at developing antiepileptogenic and disease-modifying treatments.

Suppressing pro-inflammatory prostaglandin signaling attenuates excitotoxicity-associated neuronal inflammation and injury

Glutamate receptor-mediated excitotoxicity is a common pathogenic process in many neurological conditions including epilepsy. Prolonged seizures induce elevations in extracellular glutamate that contribute to excitotoxic damage, which in turn can trigger chronic neuroinflammatory reactions, leading to secondary damage to the brain. Blocking key inflammatory pathways could prevent such secondary brain injury following the initial excitotoxic insults. Prostaglandin E2 (PGE₂) has emerged as an important mediator of neuroinflammation-associated injury, in large part via activating its EP2 receptor subtype. Herein, we investigated the effects of EP2 receptor inhibition on excitotoxicity-associated neuronal inflammation and injury in vivo. Utilizing a bioavailable and brain-permeant compound, TG6-10-1, we found that pharmacological inhibition of EP2 receptor after a one-hour episode of kainate-induced status epilepticus (SE) in mice reduced seizure-promoted functional deficits, cytokine induction, reactive gliosis, blood-brain barrier impairment, and hippocampal damage. Our preclinical findings endorse the feasibility of blocking PGE₂/EP2 signaling as an adjunctive strategy to treat prolonged seizures. The promising benefits from EP2 receptor inhibition should also be relevant to other neurological conditions in which excitotoxicity-associated secondary damage to the brain represents a pathogenic event.