Integrative analysis of gene expression associated with epilepsy in human epilepsy and animal models

Acute rapamycin treatment reveals novel mechanisms of behavioral, physiological, and functional dysfunction in a maternal inflammation mouse model of autism and sensory over-responsivity

Maternal inflammatory response (MIR) during early gestation in mice induces a cascade of physiological and behavioral changes that have been associated with autism spectrum disorder (ASD). In a prior study and the current one, we find that mild MIR results in chronic systemic and neuro-inflammation, mTOR pathway activation, mild brain overgrowth followed by regionally specific volumetric changes, sensory processing dysregulation, and social and repetitive behavior abnormalities. Prior studies of rapamycin treatment in autism models have focused on chronic treatments that might be expected to alter or prevent physical brain changes. Here, we have focused on the acute effects of rapamycin to uncover novel mechanisms of dysfunction and related to mTOR pathway signaling. We find that within 2 hours, rapamycin treatment could rapidly rescue neuronal hyper-excitability, seizure susceptibility, functional network connectivity and brain community structure, and repetitive behaviors and sensory over-responsivity in adult offspring with persistent brain overgrowth. These CNS-mediated effects are also associated with alteration of the expression of several ASD-,ion channel-, and epilepsy-associated genes, in the same time frame. Our findings suggest that mTOR dysregulation in MIR offspring is a key contributor to various levels of brain dysfunction, including neuronal excitability, altered gene expression in multiple cell types, sensory functional network connectivity, and modulation of information flow. However, we demonstrate that the adult MIR brain is also amenable to rapid normalization of these functional changes which results in the rescue of both core and comorbid ASD behaviors in adult animals without requiring long-term physical alterations to the brain. Thus, restoring excitatory/inhibitory imbalance and sensory functional network modularity may be important targets for therapeutically addressing both primary sensory and social behavior phenotypes, and compensatory repetitive behavior phenotypes.

TGF-β as a Key Modulator of Astrocyte Reactivity: Disease Relevance and Therapeutic Implications

Astrocytes are essential for normal brain development and functioning. They respond to brain injury and disease through a process referred to as reactive astrogliosis, where the reactivity is highly heterogenous and context-dependent. Reactive astrocytes are active contributors to brain pathology and can exert beneficial, detrimental, or mixed effects following brain insults. Transforming growth factor-β (TGF-β) has been identified as one of the key factors regulating astrocyte reactivity. The genetic and pharmacological manipulation of the TGF-β signaling pathway in animal models of central nervous system (CNS) injury and disease alters pathological and functional outcomes. This review aims to provide recent understanding regarding astrocyte reactivity and TGF-β signaling in brain injury, aging, and neurodegeneration. Further, it explores how TGF-β signaling modulates astrocyte reactivity and function in the context of CNS disease and injury.

Relationship Between the Pyroptosis Pathway and Epilepsy: A Bioinformatic Analysis

Purpose

This study aimed to analyse the correlation between the pyroptosis pathway and epilepsy using bioinformatics analysis technology. We analyzed the expression of gasdermin D (GSDMD) and gasdermin E (GSDME), the key molecules of pyroptosis, in kainic acid-induced epileptic mice.

Methods

Weighted gene co-expression network analysis (WGCNA) was used to construct a signed co-expression network from expression data to screen gene sets closely related to epilepsy. The correlation between the module and epilepsy was verified through module conservative analysis, gene ontology (GO) annotation analysis, and correlation analysis with known epilepsy genes. We obtained currently recognized pyroptosis-related molecules through literature review, and correlation analysis was used to evaluate their correlation with epilepsy. Differentially expressed gene (DEG) analysis was used to analyse expression changes of pyroptosis-related molecules at the transcriptome level, compared to the sham group. We subsequently established a kainic acid-induced status epilepticus (SE) model in mice and validated the mRNA and protein expression of GSDMD and GSDME, the key molecules of pyroptosis, by quantitative reverse transcription PCR (qRT-PCR) and western blotting (WB).

Results

Using WGCNA, module conservative analysis, and correlation analysis with known epilepsy genes, we screened out a module (a gene set of interest) closely related to epilepsy that was prominently enriched in immune and inflammatory-related biological processes. Correlation analysis results suggest that pyroptosis-related molecules are closely related to this module, but have no obvious correlation with others. DEG analysis of molecules associated with pyroptosis suggests that most of the pyroptosis-related molecules had significantly increased expression after SE, such as IL1b, Casp1, Casp4, Pycard, Gsdmd, Nlrp3, Aim2, Mefv, Tlr2, Tlr3, and Tlr4. qRT-PCR and WB analysis confirmed that the mRNA and protein levels of GSDMD in the mouse hippocampus were significantly upregulated after SE. The mRNA expression of GSDME was not different between the epilepsy group and sham group. However, the WB results showed that the expression of full-length GSDME was decreased and GSDME-N-terminus were significantly increased after SE.

Conclusions

Our study highlights that the pyroptosis pathway may be closely related to epilepsy. GSDMD and GSDME, the key executive molecules of pyroptosis, will help to understand the pathogenesis of epilepsy and aid in discovering new targets for anti-epileptic drug treatments.

Exosomes in Epilepsy of Tuberous Sclerosis Complex: Carriers of Pro-Inflammatory MicroRNAs

Exosomes are a class of small, secreted extracellular vesicles (EV) that have recently gained considerable attention for their role in normal cellular function, disease processes and potential as biomarkers. Exosomes serve as intercellular messengers and carry molecular cargo that can alter gene expression and the phenotype of recipient cells. Here, we investigated alterations of microRNA cargo in exosomes secreted by epileptogenic tissue in tuberous sclerosis complex (TSC), a multi-system genetic disorder that includes brain lesions known as tubers. Approximately 90% of TSC patients suffer from seizures that originate from tubers, and ~60% are resistant to antiseizure drugs. It is unknown why some tubers cause seizures while others do not, and the molecular basis of drug-resistant epilepsy is not well understood. It is believed that neuroinflammation is involved, and characterization of this mechanism may be key to disrupting the "vicious cycle" between seizures, neuroinflammation, and increased seizure susceptibility. We isolated exosomes from epileptogenic and non-epileptogenic TSC tubers, and we identified differences in their microRNA cargo using small RNA-seq. We identified 12 microRNAs (including miR-142-3p, miR-223-3p and miR-21-5p) that are significantly increased in epileptogenic tubers and contain nucleic acid motifs that activate toll-like receptors (TLR7/8), initiating a neuroinflammatory cascade. Exosomes from epileptogenic tissue caused induction of key pathways in cultured cells, including innate immune signaling (TLR), inflammatory response and key signaling nodes SQSTM1 (p62) and CDKN1A (p21). Genes induced in vitro were also significantly upregulated in epileptogenic tissue. These results provide new evidence on the role of exosomes and non-coding RNA cargo in the neuroinflammatory cascade of epilepsy and may help advance the development of novel biomarkers and therapeutic approaches for the treatment of drug-resistant epilepsy.

Bioinformatic analysis identifies key transcriptome signatures in temporal lobe epilepsy

Aims

To identify transcriptome signatures underlying epileptogenesis in temporal lobe epilepsy (TLE).

Methods

Robust rank aggregation analysis was used to integrate multiple microarrays in rodent models of TLE and determine differentially expressed genes (DEGs) in acute, latent, and chronic stages. Functional annotation and protein‐protein interaction analysis were performed to explore the potential functions of the DEGs and identify hub genes with the highest intramodular connectivity. The association between hub genes and hippocampal sclerosis/seizure frequency was analyzed using publicly available RNA‐sequencing datasets from TLE patients. We subsequently established a pilocarpine‐induced status epilepticus (SE) model in rats and validated mRNA expression of hub genes by quantitative reverse transcription PCR (qRT‐PCR).

Results

The DEGs in the acute, latent, and chronic phases of TLE in animal models were prominently enriched in inflammatory response. Hub genes identified in the acute phase mainly participated in biological processes including inflammation, blood‐brain barrier damage, and cell adhesion. The hub genes in the latent phase were related to microglia/macrophage activation (Emr1 and Aif1) and phagocytosis (Cd68, Tyrobp, and Lyz). In the chronic phase, the hub genes were associated with activation of complements and microglia/macrophages. We further found that some hub genes identified in human TLE, such as Tlr2, Lgals3, and Stat3, were positively correlated with seizure frequency. Other hub genes, including Lgals3 and Serpine1, were associated with hippocampus sclerosis. qRT‐PCR analysis confirmed that the mRNA levels of hub genes in rat hippocampus were significantly up‐regulated after SE induction.

Conclusions

Our integrated analysis identified hub genes in different stages of epilepsy. The functional annotations suggest that the activation and phagocytic activities of microglia/macrophages may play critical roles in epileptogenesis of TLE.

Aberrant expression of PAR bZIP transcription factors is associated with epileptogenesis, focus on hepatic leukemia factor

Epilepsy is a widespread neurological disease characterized by abnormal neuronal activity resulting in recurrent seizures. There is mounting evidence that a circadian system disruption, involving clock genes and their downstream transcriptional regulators, is associated with epilepsy. In this study, we characterized the hippocampal expression of clock genes and PAR bZIP transcription factors (TFs) in a mouse model of temporal lobe epilepsy induced by intrahippocampal injection of kainic acid (KA). The expression of PAR bZIP TFs was significantly altered following KA injection as well as in other rodent models of acquired epilepsy. Although the PAR bZIP TFs are regulated by proinflammatory cytokines in peripheral tissues, we discovered that the regulation of their expression is inflammation-independent in hippocampal tissue and rather mediated by clock genes and hyperexcitability. Furthermore, we report that hepatic leukemia factor (Hlf), a member of PAR bZIP TFs family, is invariably downregulated in animal models of acquired epilepsy, regulates neuronal activity in vitro and its overexpression in dentate gyrus neurons in vivo leads to altered expression of genes associated with seizures and epilepsy. Overall, our study provides further evidence of PAR bZIP TFs involvement in epileptogenesis and points to Hlf as the key player.

Effects of carbamazepine combined with vitamin B12 on levels of plasma homocysteine, hs-CRP and TNF-α in patients with epilepsy

The efficacy of carbamazepine combined with vitamin B12 in epilepsy treatment by comparing levels of plasma homocysteine (Hcy), serum TNF-α and hs-CRP in patients with epilepsy before and after treatment was investigated. Fifty-eight patients with epilepsy who were admitted and received treatment in The First People's Hospital of Xuzhou were recruited as subjects, and fifty-eight healthy volunteers were recruited as the control group. Patients were treated with carbamazepine combined with vitamin B12 for a period of three months. The mRNA and protein levels of TNF-α and hs-CRP in serum were measured before and after treatment using semi-quantitative RT-PCR and western blotting, respectively. The plasma Hcy levels were measured as well. Within one year after the 3-month treatment, the frequency and duration of seizure were tracked. After treatment with carbamazepine combined with vitamin B12 for patients with epilepsy, the Hcy level was significantly higher than that before treatment and that in the control group (P<0.01). The mRNA and protein levels of TNF-α and hs-CRP in serum were significantly higher in patients than that in healthy people (P<0.01). After treatment these levels were reduced (P<0.01), but still higher than those in healthy people (P<0.05, P<0.01). After treatment, the frequency and duration of seizures were all reduced (P<0.05, P<0.01). The results suggested that carbamazepine combined with vitamin B12 was effective in treatment of epilepsy by reducing levels of TNF-α and hs-CRP in the serum, but had a risk of increasing the Hcy level.