Correlation between tumor necrosis factor alpha mRNA and microRNA-155 expression in rat models and patients with temporal lobe epilepsy

Posttraumatic epilepsy: Integrating clinical, inflammatory, and genetic profiles in traumatic brain injury patients

OBJECTIVE

This study aims to assess the clinical, inflammatory, and genetic profiles of traumatic brain injury (TBI) patients over a 2-year follow-up period, focusing on the development of posttraumatic epilepsy (PTE).

METHODS

Fifty-nine patients with acute TBI were recruited in the emergency unit of a hospital in Brazil. Clinical data and blood samples were collected after 10 days of hospitalization for posterior genetic profile (Apolipoprotein E- ApoE and Glutamic Acid Descarboxylase-GAD sequencing) analyses. A subset of 19 patients were assessed for cytokine markers (mRNA expression). The development of PTE was investigated for two years following TBI. Statistical analyses including univariate analysis, multiple correspondence analysis, and Mann-Whitney test were performed.

RESULTS

Analysis revealed an association between severe TBI and requirement for neurosurgery and polytrauma (p<0.05), as well as the development of PTE over a two-year follow-up period (p<0.05). Multiple correspondence analysis identified two distinct profiles associated with PTE and Non-PTE outcomes. The PTE profile showed a higher prevalence of the ApoE genotype E3/E3 and GAD1 SNP (rs769391) genotype AA in our study, while the Non-PTE profile showed a higher presence of E3/E4. mRNA expression analysis demonstrated acute elevated levels of TNF-α in the PTE group as compared to Non-PTE patients (6.70±1.53 vs 5.31 ±0.33, p<0.01).

SIGNIFICANCE

Our findings underscore the multifactorial nature of aspects potentially contributing to PTE. It is unlikely that any single factor might in isolation have a strong causative influence over the development of epilepsy after TBI. Our results provide a suggestion of potential clustering that might be relevant as prognostic factors for PTE.

Roles of the miR-155 in Neuroinflammation and Neurological Disorders: A Potent Biological and Therapeutic Target

Neuroinflammation plays a crucial role in the development and progression of neurological disorders. MicroRNA-155 (miR-155), a miR is known to play in inflammatory responses, is associated with susceptibility to inflammatory neurological disorders and neurodegeneration, including Alzheimer's disease, Parkinson's disease, multiple sclerosis, and amyotrophic lateral sclerosis as well as epilepsy, stroke, and brain malignancies. MiR-155 damages the central nervous system (CNS) by enhancing the expression of pro-inflammatory cytokines, like IL-1β, IL-6, TNF-α, and IRF3. It also disturbs the blood-brain barrier by decreasing junctional complex molecules such as claudin-1, annexin-2, syntenin-1, and dedicator of cytokinesis 1 (DOCK-1), a hallmark of many neurological disorders. This review discusses the molecular pathways which involve miR-155 as a critical component in the progression of neurological disorders, representing miR-155 as a viable therapeutic target.

Influence of methadone on the anticonvulsant efficacy of valproate sodium gabapentin against maximal electroshock seizure in mice by regulation of brain MDA TNF-α

Methadone is the most frequently used opioid therapy worldwide, with controversial effects on oxidative stress homeostasis. This study investigated the effects of intraperitoneal (i.p.) co-administration of methadone (0.1, 0.3, 1, and 3 mg/kg) and valproate sodium (300 mg/kg) or gabapentin (50 mg/kg) in the mice maximal electroshock (MES)-induced seizure model. The adverse effect of drugs was assessed using the chimney test. The levels of tumor necrosis factor-alpha (TNF-α) and malondialdehyde (MDA) contents were measured in mice brains after a single seizure. Administration of methadone alone resulted in a significant reduction in the duration of hind limb extension (HLE) than that in the control group. Methadone pretreatment at doses of 0.1 and 0.3 mg/kg i.p. decreased, and at doses of 1 and 3 mg/kg i.p. had an increasing effect on anticonvulsant efficacy of gabapentin. Pretreatment with all doses of methadone significantly decreased the valproate anticonvulsive efficacy. At doses of 1 and 3 mg/kg i.p. methadone per se increased brain MDA levels after MES-induced seizure. Administration of methadone (0.3 mg/kg i.p.) enhanced and at 3 mg/kg decreased gabapentin effect on brain MDA level, but their co-treatment did not lead to further increase in MDA. Methadone at 0.3–3 mg/kg enhanced the effect of sodium valproate on MDA levels in the brain, but at all doses significantly potentiated its effect on brain TNF-α levels. The drugs did not produce any side effects on motor coordination in experimental animals. In conclusion, methadone showed different effects on anticonvulsant actions of gabapentin and valproate through regulation of brain levels of MDA and TNF-α.

Ameliorating effect of ketogenic diet on acute status epilepticus: Insights into biochemical and histological changes in rat hippocampus

This study aimed to evaluate the potential neuroprotective effects of ketogenic diet (KD) against the neuronal disruptions induced by SE in lithium-pilocarpine rat model of status epilepticus (SE). Four groups of female rats include; groups I and III received standard diet and groups II and IV received KD for 3 weeks. Groups I and II were left untreated, while groups III and IV were injected with LiCl (127 mg/kg, i.p.) followed by pilocarpine HCl (10 mg/kg, i.p.) 18-24 h later, repeatedly, till induction of SE. 72 h post-SE, KD effectively ameliorated the balance between excitatory (glutamate) and inhibitory (GABA) neurotransmitters and the oxidative stress indices, increased adenine nucleotides and decreased immunoreactivity of iNOS, TNFα, glial fibrillary acidic protein, and synaptophysin. Thiswas in association with improvement in inflammatory response and neuronal tissue characteristics in hippocampus of SE rats. Histological changes showed preservation of neuronal integrity. These findings highlight the protective effects of KD in the acute phase post-SE via ameliorating biochemical and histological changes involved. PRACTICAL APPLICATIONS: Epilepsy is the fourth most common neurological disorder that requires lifelong treatment. It stigmatizes patients and their families. The use of the ketogenic diet (KD) as a therapy for epilepsy developed from observations that fasting could reduce seizures. From 1920s, the KD was a common epilepsy treatment until it was gradually superseded by anticonvulsant drugs so that by the 1980s it was rarely used. However, there has been a resurgence of interest and usage of the KD for epilepsy since the turn of the century. Despite its long history, the mechanisms by which KD exhibits its anti-seizure action are not fully understood. Our study aims to identify the mechanism of KD which may help further studies to achieve the same benefits with a drug or supplement to overcome its unpalatability and gastrointestinal side effects.

Modafinil exerts anticonvulsive effects against lithium-pilocarpine-induced status epilepticus in rats: A role for tumor necrosis factor-α and nitric oxide signaling

BACKGROUND

Status epilepticus (SE) is a continuous episode of seizures which leads to hippocampal neurodegeneration, severe systemic inflammation, and extreme damage to the brain. Modafinil, a psychostimulant and wake-promoting agent, has exerted neuroprotective and anti-inflammatory effects in previous preclinical studies. The aim of this study was to assess effects of modafinil on the lithium-pilocarpine-induced SE rat model and to explore possible involvement of tumor necrosis factor-α (TNF-α) and nitric oxide (NO) pathways in this regard.

METHODS

Status epilepticus was provoked by injection of lithium chloride (127 mg/kg, intraperitoneally [i.p]) and pilocarpine (60 mg/kg, i.p.) in rats. Animals received different modafinil doses (50, 75, 100, and 150 mg/kg, i.p.) and SE scores were documented over 3 hours of duration. Moreover, the role of the nitrergic pathway in the effects of modafinil was evaluated by injection of the non-selective NO synthase (NOS) inhibitor L-N^G-Nitro arginine methyl ester (L-NAME, 10 mg/kg, i.p.), the selective neuronal NOS inhibitor 7-nitroindazole (30 mg/kg, i.p.), and the selective inducible NOS inhibitor aminoguanidine (100 mg/kg, i.p.) 15 min before saline/vehicle or modafinil. The ELISA method was used to quantify TNF-α and NO metabolite levels in the isolated hippocampus.

RESULTS

Modafinil at 100 mg/kg significantly decreased SE scores (P < 0.01). Pre-treatment with L-NAME, 7-nitroindazole, and aminoguanidine significantly reversed the anticonvulsive effects of modafinil. Status epilepticus-induced animals showed significantly higher NO metabolite and TNF-α levels in their hippocampal tissues, an effect that was reversed by modafinil (100 mg/kg, i.p.) treatment. Administration of NOS inhibitors resulted in excessive NO level reduction but an escalation of TNF-α level in modafinil-treated SE-animals.

CONCLUSION

Our study revealed anticonvulsive effects of modafinil in the lithium-pilocarpine-induced SE rat model via possible involvement of TNF-α and nitrergic pathways.

The emerging role of noncoding RNAs in neuroinflammation: Implications in pathogenesis and therapeutic approaches

Noncoding RNAs (ncRNAs) are important regulators of gene expression in different cell processes. Due to their ability in monitoring neural development genes, these transcripts confer neurons with the potential to exert broad control over the expression of genes for performing neurobiological functions. Although the change of ncRNA expression in different neurodegenerative diseases has been reviewed elsewhere, only recent evidence drove our attention to unravel the involvement of these molecules in neuroinflammation within these devastating disorders. Remarkably, the interactions between ncRNAs and inflammatory pathways are not fully recognized. Therefore, this review has focused on the interplay between diverse inflammatory pathways and the related ncRNAs, including microRNAs, long noncoding RNAs, and competing endogenous RNAs in Alzheimer's disease, Parkinson's diseases, amyotrophic lateral sclerosis, epilepsy, multiple sclerosis, Huntington's disease, and prion diseases. Providing novel insights in the field of combining biomarkers is a critical step for using them as diagnostic tools and therapeutic targets in clinical settings.

Neuroprotective Effect of Fisetin Through Suppression of IL-1R/TLR Axis and Apoptosis in Pentylenetetrazole-Induced Kindling in Mice

Epilepsy is a complex neurological disorder, characterized by frequent electrical activity in brain regions. Inflammation and apoptosis cascade activation are serious neurological sequelae during seizures. Fisetin (3, 3',4',7-tetrahydroxyflavone), a flavonoid molecule, is considered for its effective anti-inflammatory and anti-apoptotic properties. This study investigated the neuroprotective effect of fisetin on experimental epilepsy. For acute studies, increasing current electroshock (ICES) and pentylenetetrazole (PTZ)-induced seizure tests were performed to evaluate the antiseizure activity of fisetin. For the chronic study, the kindling model was established by the administration of PTZ in subconvulsive dose (25 mg/kg, i.p.). Mice were treated with fisetin (5, 10, and 20 mg/kg, p.o.) to study its probable antiseizure mechanism. The kindled mice were evaluated for seizure scores. Their hippocampus and cortex were assessed for neuronal damage, inflammation, and apoptosis. Histological alterations were observed in the hippocampus of the experimental mice. Levels of high mobility group box 1 (HMGB1), Toll-like receptor-4 (TLR-4), interleukin-1 receptor 1 (IL-1R1), interleukin-1β (IL-1β), interleukin-6 (IL-6), and tumor necrosis factor-α (TNF-α) were assessed in the hippocampus and cortex by ELISA. The immunoreactivity and mRNA expressions of nuclear factor-κB (NF-κB), cyclooxygenase-2 (COX-2), cytochrome C, and caspase-3 were quantified by immunohistochemical analysis and real-time PCR. Phosphorylation ELISA was performed to evaluate AkT/mTOR (mammalian target of rapamycin) activation in the hippocampus and cortex of the kindled mice. The results showed that fisetin administration increased the seizure threshold current (STC) in the ICES test. In PTZ-induced seizures, fisetin administration increased the latency for myoclonic jerks (MJs) and generalized seizures (GSs). In the PTZ-induced kindling model, fisetin administration dose-dependently suppressed the development of kindling and the associated neuronal damage in the experimental mice. Further, fisetin administration ameliorated kindling-induced neuroinflammation as evident from decreased levels of HMGB1, TLR-4, IL-1R1, IL-1β, IL-6, and TNF-α in the hippocampus and cortex of the kindled mice. Also, the immunoreactivity and mRNA expressions of inflammatory molecules, NF-κB, and COX-2 were decreased with fisetin administration in the kindled animals. Decreased phosphorylation of the AkT/mTOR pathway was reported with fisetin administration in the hippocampus and cortex of the kindled mice. The immunoreactivity and mRNA expressions of apoptotic molecules, cytochrome C, and caspase-3 were attenuated upon fisetin administration. The findings suggest that fisetin shows a neuroprotective effect by suppressing the release of inflammatory and apoptosis molecules and attenuating histological alterations during experimental epilepsy.

Relationship between Tumor Necrosis Factor-Alpha and Neuropeptide Y Expression and Neurological Function Score in Epileptic Children

Background

To observe the relationship between Tumor Necrosis Factor-alpha (TNF-α) and Neuropeptide Y (NPY) expression and neurological function score in epileptic children.

Methods

Fifty-four epileptic children diagnosed and treated in Xuzhou Children's Hospital, China from Feb 2017 to Mar 2018 were collected and included in a research group (RG), while 30 healthy children who underwent physical examination at the same time were included in the control group (CG). ELISA was used to detect the expression of TNF-α and NPY in the serum of children in the two groups, and those before treatment were compared. The National Institute of Health stroke scale (NIHSS) and Hamilton Anxiety (HAMA) scores before and after treatment were observed, and Pearson correlation was used to analyze the relationship between the expression levels of TNF-α and NPY in the serum as well as NIHSS and HAMA scores.

Results

The expression levels of TNF-α and NPY in the serum of children in the RG were significantly higher than those in the CG (P<0.001). The expression level of TNF-α was positively correlated with the NIHSS and HAMA scores (r=0.748, P<0.001) (r=0.772, P<0.001). The expression level of NPY was positively correlated with the NIHSS and HAMA scores (r=0.768, P<0.001) (r=0.643, P<0.001).

Conclusion

TNF-α and NPY are highly expressed in epileptic children and are positively correlated with neurological function score.

MicroRNAs in temporal lobe epilepsy: a systematic review

OBJECTIVE

About 30% of patients with epilepsy have drug-resistant seizures. The aim of the current endeavor was to systematically review the existing evidence on the potential applications of microRNAs as biomarkers in people with difficult to treat temporal lobe epilepsy (TLE).

METHODS

MEDLINE (accessed from PubMed) and Scopus from inception to March 18, 2020 were systematically searched for related published articles. In both electronic databases, the following search strategy was implemented, and these keywords (in the title/abstract) were used: "microRNA" AND "temporal lobe epilepsy." Articles written in English that were human studies in people with epilepsy were all included in this search.

RESULTS

We could identify 16 articles about different aspects of microRNAs in the serum of patients with TLE. However, only three studies robustly investigated microRNAs as potential biomarkers in the diagnosis of drug-resistant TLE (microRNA-155 (upregulated), microRNA-129-2-3p (upregulated), microRNA-153 (downregulated)). One small study provided class II, and two small studies provided class III evidence.

CONCLUSION

While this systematic review identified three studies that provided some evidence on the potential applications of circulating serum microRNAs as biomarkers in people with drug-resistant TLE, the evidence is not robust yet. While these findings provide a new horizon, substantial challenges remain before the roles of microRNAs as biomarkers in the diagnosis of drug-resistant TLE can be translated into clinical practice.

Prospects and Limitations Related to the Use of MicroRNA as a Biomarker of Epilepsy in Children: A Systematic Review

Epilepsy is one of the most common neurological diseases in children. There is an unmet need for new objective methods that would facilitate and accelerate the diagnostic process, thus improving the prognosis. In many studies, the participation of microRNA in epileptogenesis has been confirmed. Therefore, it seems to be a promising candidate for this role. Scientists show the possibility of using microRNAs as diagnostic and predictive biomarkers as well as novel therapeutic targets. Children with epilepsy would benefit particularly from the use of this innovative method. However, the number of studies related to this age group is very limited. This review is based on 10 studies in children and summarizes the information collected from studies on animal models and the adult population. A total of 136 manuscripts were included in the analysis. The aim of the review was to facilitate the design of studies in children and to draw attention to the challenges and traps related to the analysis of the results. Our review suggests a high potential for the use of microRNAs and the need for further research.

Expression of VEGF- and tight junction-related proteins in the neocortical microvasculature of patients with drug-resistant temporal lobe epilepsy

The blood-brain barrier (BBB) maintains the optimal microenvironment for brain function. Tight junctions (TJs) allow endothelial cells to adhere to each other, leading to the formation of a barrier that prevents the penetration of most molecules via transcellular routes. Evidence has indicated that seizure-induced vascular endothelial growth factor (VEGF) type 2 receptor (VEGFR-2) pathway activation weakens TJs, inducing vasodilatation and increasing vascular permeability and subsequent brain injury. The present study focused on investigating the expression levels of VEGF-related (VEGF-A and VEGFR-2) and TJ-related proteins (claudin-5, occludin and ZO-1) in the neocortical microvasculature of patients with drug-resistant temporal lobe epilepsy (TLE). The results obtained from hippocampal sclerosis TLE (HS-TLE) patients were compared with those obtained from patients with TLE secondary to lesions (lesion-TLE) and autopsy samples. The Western blotting and immunofluorescence results showed that VEGF-A and VEGFR-2 protein expression levels were increased in HS-TLE and lesion-TLE patients compared to autopsy group. On the other hand, claudin-5 expression was higher in HS-TLE patients and lesion-TLE patients than autopsies. The expression level of occludin and ZO-1 was decreased in HS-TLE patients. Our study described modifications to the integrity of the BBB that may contribute to the pathogenesis of TLE, in which the VEGF system may play an important role. We demonstrated that the same modifications were present in both HS-TLE and lesion-TLE patients, which suggests that seizures modify these systems and that they are not associated with the establishment of epilepsy.

Silencing of microRNA-146a alleviates the neural damage in temporal lobe epilepsy by down-regulating Notch-1

This study aimed to evaluate the specific regulatory roles of microRNA-146a (miRNA-146a) in temporal lobe epilepsy (TLE) and explore the related regulatory mechanisms. A rat model of TLE was established by intraperitoneal injection of lithium chloride-pilocarpine. These model rats were injected intracerebroventricularly with an miRNA-146a inhibitor and Notch-1 siRNA. Then, neuronal damage and cell apoptosis in the cornu ammonis (CA) 1 and 3 regions of the hippocampus were assessed. SOD and MDA levels in the hippocampus were detected by chromatometry, and IL-1β, IL-6, and IL-18 levels were detected by ELISA. Then, we evaluated the expression levels of caspase-9, GFAP, Notch-1, and Hes-1 in the hippocampus. The interaction between Notch-1 and miRNA-146a was assessed by a dual luciferase reporter gene assay. A rat model of TLE was successfully established, which exhibited significantly increased miRNA-146a expression in the hippocampus. Silencing of miRNA-146a significantly alleviated the neuronal damage and cell apoptosis in the CA1 and CA3 regions of the hippocampus in TLE rats and decreased MDA, IL-1β, IL-6, and IL-18 levels and increased SOD levels in the hippocampus of TLE rats. In addition, silencing of miRNA-146a significantly decreased the expression levels of caspase-9, GFAP, Notch-1, and Hes-1 in the hippocampus of TLE rats. Notch-1 was identified as a target of miRNA-146a and silencing of Notch-1 aggravated the neuronal damage in the CA1 and CA3 regions. Silencing of miRNA-146a alleviated the neuronal damage in the hippocampus of TLE rats by down-regulating Notch-1.

microRNA-139-5p confers sensitivity to antiepileptic drugs in refractory epilepsy by inhibition of MRP1

Aim

Drug resistance is an intractable issue urgently needed to be overcome for improving efficiency of antiepileptic drugs in treating refractory epilepsy. microRNAs (miRNAs) have been proved as key regulators and therapeutic targets in epilepsy. Accordingly, the aim of the present study was to identify a novel differentially expressed miRNA which could improve the efficiency of antiepileptic drugs during the treatment of refractory epilepsy.

Methods and Results

Serum samples were collected from children with refractory epilepsy. An in vivo refractory epilepsy model was developed in SD rats by electrical amygdala kindling. We identified that miR‐139‐5p was decreased and multidrug resistance‐associated protein 1 (MRP1) was remarkably upregulated in the serum samples from children with refractory epilepsy and the brain tissues from rat models of refractory epilepsy. After phenobarbitone injection in rat models of refractory epilepsy, the after discharging threshold in kindled amygdala was detected to screen out drug‐resistant rats. Dual‐luciferase reporter gene assay demonstrated that MRP1 was a target of miR‐139‐5p. In order to evaluate the effect of miR‐139‐5p/MRP1 axis on drug resistance of refractory epilepsy, we transfected plasmids into the hippocampus of drug‐resistant rats to alter the expression of miR‐139‐5p and MRP1. TUNEL staining and Nissl staining showed that miR‐139‐5p overexpression or MRP1 downregulation could reduce the apoptosis and promote survival of neurons, accompanied by alleviated neuronal damage.

Conclusion

Collectively, these results suggest an important role of miR‐139‐5p/MRP1 axis in reducing the resistance of refractory epilepsy to antiepileptic drugs.

Perspective: Therapeutic Potential of Flavonoids as Alternative Medicines in Epilepsy

Epilepsy is a chronic neurological disorder that affects many people worldwide. Temporal lobe epilepsy is the most common and most studied type of epilepsy, but the pathological mechanisms underlying this condition are poorly understood. More than 20 antiepileptic drugs (AEDs) have been developed and used for the treatment of epilepsy; however, 30% of patients still experience uncontrolled epilepsy and associated comorbidities, which impair their quality of life. In addition, various side effects have been reported for AEDs, such as drowsiness, unsteadiness, dizziness, blurred or double vision, tremor (shakiness), greater risk of infections, bruising, and bleeding. Thus, critical medical needs remain unmet for patients with uncontrolled epilepsy. Flavonoids belong to a subclass of polyphenols that are widely present in fruits, vegetables, and certain beverages. Recently, many studies have reported that some flavonoids elicit various beneficial effects in patients with epilepsy without causing the side effects associated with conventional medical therapies. Moreover, flavonoids may have a property of regulating microRNA expression associated with inflammation and cell survival. These findings suggest that flavonoids, which are more effective but impose fewer adverse effects than conventional AEDs, could be used in the treatment of epilepsy.