Altered transforming growth factor beta/SMAD3 signalling in patients with hippocampal sclerosis

Alternations in morphometric similarity network in mesial temporal epilepsy correlate to neuroinflammatory pathway gene transcriptions

BACKGROUND

Mesial temporal lobe epilepsy (mTLE) is the most common form of focal epilepsy, often associated with hippocampal sclerosis. Increasing evidence suggests the pivotal role of neuroinflammation in mTLE onset and progression.

METHODS

We used morphometric similarity network (MSN) analysis and the Allen Human Brain Atlas (AHBA) database to investigate structural changes between mTLE and healthy controls, as well as correlation with inflammation-related gene expression.

RESULTS

We identified widespread alterations across the frontal and parietal lobes and cingulate cortex linked to neuroinflammatory genes such as PRR5, SMAD3, and IRF3. This correlation was even more pronounced in mTLE patients with hippocampal sclerosis compared to those without. Enrichment analysis highlighted pathways related to neurodevelopment and neurodegeneration, supporting a bidirectional link between mTLE and neurodegenerative diseases.

CONCLUSIONS

These findings suggest that brain-wide macroscopic morphometric alternations in mTLE are correlated to the neuroinflammation process. It provides circumstantial evidence from a new perspective to support the bidirectional link between mTLE and neurodegenerative diseases.

Altered expression of activating transcription factor 3 in the hippocampus of patients with mesial temporal lobe epilepsy-hippocampal sclerosis (MTLE-HS)

Aim of the study: Activating Transforming factor 3 (ATF3) is a stress induced gene and closely associated with neuro-inflammation while Transforming growth Factor Beta (TGFβ) signalling is also reported to be involved in neuro-inflammation and hyper-excitability associated with drug resistant epilepsy. Animal model studies indicate the involvement of ATF3 and TGFβ receptors to promote epileptogenesis. Human studies also show that TGFβ signalling is activated in MTLE-HS. However, lack of studies on ATF3 and TGFβRI expression in MTLE-HS patients exists. We hypothesize that ATF3 and TGFβRI might be expressed in hippocampi of patients with MTLE-HS and playing role in epileptogenesis. Materials & methods: Protein expression of ATF3 and TGFβRI was performed by western blotting. Localisation of ATF3 was performed by immunohistochemistry and immunoflorescence. Results: Protein expression of ATF3 and TGFβRI was significantly up-regulated in hippocampi of patients as compared to controls. Also ATF3 IR was significantly expressed in hippocampi of patients and ATF3 was expressed predominantly in cytoplasm as compared to nucleus. No correlation was found between ATF3 expression and epilepsy duration and seizure frequency. Conclusions: ATF3 and TGFβRI are both important players in neuro-inflammation and might potentiate epileptogenesis in these patients.

Downregulation of Ubiquitin-Specific Protease 15 (USP15) Does Not Provide Therapeutic Benefit in Experimental Mesial Temporal Lobe Epilepsy

Structural epilepsies display complex immune activation signatures. However, it is unclear which neuroinflammatory pathways drive pathobiology. Transcriptome studies of brain resections from mesial temporal lobe epilepsy (mTLE) patients revealed a dysregulation of transforming growth factor β, interferon α/β, and nuclear factor erythroid 2-related factor 2 pathways. Since these pathways are regulated by ubiquitin-specific proteases (USP), in particular USP15, we hypothesized that USP15 blockade may provide therapeutic relief in treatment-resistant epilepsies. For validation, transgenic mice which either constitutively or inducibly lack Usp15 gene expression underwent intrahippocampal kainate injections to induce mTLE. We show that the severity of status epilepticus is unaltered in mice constitutively lacking Usp15 compared to wild types. Cell death, reactive gliosis, and changes in the inflammatory transcriptome were pronounced at 4 days after kainate injection. However, these brain inflammation signatures did not differ between genotypes. Likewise, induced deletion of Usp15 in chronic epilepsy did not affect seizure generation, cell death, gliosis, or the transcriptome. Concordantly, siRNA-mediated knockdown of Usp15 in a microglial cell line did not impact inflammatory responses in the form of cytokine release. Our data show that a lack of USP15 is insufficient to modulate the expression of relevant neuroinflammatory pathways in an mTLE mouse model and do not support targeting USP15 as a therapeutic approach for pharmacoresistant epilepsy.

Dual fluorescence images, transport pathway, and blood-brain barrier penetration of B-Met-W/O/W SE

Borneol is an aromatic traditional Chinese medicine that can improve the permeability of the blood-brain barrier (BBB), enter the brain, and promote the brain tissue distribution of many other drugs. In our previous study, borneol-metformin hydrochloride water/oil/water composite submicron emulsion (B-Met-W/O/W SE) was prepared using borneol and SE to promote BBB penetration, which significantly increased the brain distribution of Met. However, the dynamic images, transport pathway (uptake and efflux), promotion of BBB permeability, and mechanisms of B-Met-W/O/W SE before and after entering cells have not been clarified. In this study, rhodamine B and coumarin-6 were selected as water-soluble and oil-soluble fluorescent probes to prepare B-Met-W/O/W dual-fluorescent SE (B-Met-W/O/W DFSE) with concentric circle imaging. B-Met-W/O/W SE can be well taken up by brain microvascular endothelial cells (BMECs). The addition of three inhibitors (chlorpromazine hydrochloride, methyl-β-cyclodextrin, and amiloride hydrochloride) indicated that its main pathway may be clathrin-mediated and fossa protein-mediated endocytosis. Meanwhile, B-Met-W/O/W SE was obviously shown to inhibit the efflux of BMECs. Next, BMECs were cultured in the Transwell chamber to establish a BBB model, and Western blot was employed to detect the protein expressions of Occludin, Zona Occludens 1 (ZO-1), and p-glycoprotein (P-gp) after B-Met-W/O/W SE treatment. The results showed that B-Met-W/O/W SE significantly down-regulated the expression of Occludin, ZO-1, and P-gp, which increased the permeability of BBB, promoted drug entry into the brain through BBB, and inhibited BBB efflux. Furthermore, 11 differentially expressed genes (DEGs) and 7 related signaling pathways in BMECs treated with B-W/O/W SE were detected by transcriptome sequencing and verified by quantitative real-time polymerase chain reaction (qRT-PCR). These results provide a scientific experimental basis for the dynamic monitoring, transmembrane transport mode, and permeation-promoting mechanism of B-Met-W/O/W SE as a new brain-targeting drug delivery system.

Association Between Angiotensin Receptor Blocker Therapy and Incidence of Epilepsy in Patients With Hypertension

Importance

Arterial hypertension is associated with an increased incidence of epilepsy. Results from animal studies suggest that angiotensin receptor blocker (ARB) therapy could inhibit epileptic seizures. However, there is a lack of clinical data to support the use of ARB therapy in humans.

Objective

To assess whether ARB therapy is associated with a decreased incidence of epilepsy in patients with hypertension.

Design, Setting, and Participants

This cohort study obtained data from the Disease Analyzer database (IQVIA) on patients aged 18 years or older who had hypertension and at least 1 antihypertensive drug prescription. Patients were treated at 1274 general practices between January 2010 and December 2020 in Germany. Data were available for 1 553 875 patients who had been prescribed at least 1 antihypertensive drug. Patients diagnosed with epilepsy before or up to 3 months after the index date were excluded. A total of 168 612 patients were included in propensity score matching. Patients treated with 1 of 4 antihypertensive drug classes (β-blockers, ARBs, angiotensin-converting enzyme inhibitors, and calcium channel blockers [CCBs]) were matched to each other using propensity scores.

Main Outcomes and Measures

The main outcome of the study was the incidence of epilepsy associated with ARB therapy compared with other antihypertensive drug classes. Cox regression models were used to study the association between the incidence of epilepsy and ARBs compared with all other antihypertensive drug classes as a group.

Results

The study included a total of 168 612 patients, with 42 153 in each antihypertensive drug class. The mean [SD] age of patients was 62.3 [13.5] years, and 21 667 (51.4%) were women. The incidence of epilepsy within 5 years was lowest among patients treated with ARBs (0.27% at 1 year, 0.63% at 3 years, 0.99% at 5 years) and highest among patients receiving β-blockers and CCBs (0.38% for both β-blockers and CCBs at 1 year; 0.91% for β-blockers and 0.93% for CCBs at 3 years; β-blockers, 1.47%; and CCBs, 1.48% at 5 years). Angiotensin receptor blocker therapy was associated with a significantly decreased incidence of epilepsy (hazard ratio, 0.77; 95% CI, 0.65-0.90) compared with the other drug classes as a group.

Conclusions and Relevance

In this cohort study of patients with hypertension, ARB therapy was associated with a significantly decreased incidence of epilepsy. The findings suggest antihypertensive drugs could be used as a novel approach for preventing epilepsy in patients with arterial hypertension.

Increased levels of α4-containing GABAA receptors in focal cortical dysplasia: A possible cause of benzodiazepine resistance

Benzodiazepines are the first choice of anti-epileptic drugs used to treat seizures. However, it has been seen that their efficacy decreases with time leading to drug insensitivity, plausibly caused by an alteration in the expression of the benzodiazepine biding site on GABA_A receptors. This study was designed to investigate if the differential expression of GABA_A receptor subunits α1/α4/γ2/δ across the postsynaptic sites could contribute to benzodiazepine resistance in patients with focal cortical dysplasia (FCD), the most common cause of drug resistant epilepsy in pediatric population. Differential gene and cellular expression of GABA_A receptor subunits α1, α4, γ2 and δ were evaluated and validated using qPCR and immunohistochemistry. Whole cell patch clamp studies were performed on pyramidal neurons of resected cortical FCD samples to measure the spontaneous GABA_A receptor activity. Upregulation of α4-and γ2-subunits containing GABA_A receptors were observed at both mRNA and protein level. α1-and δ-subunits containing GABA_A receptors did not show any significant changes. Flumazenil treatment did not affect the kinetics of GABAergic events in FCD; however, it significantly reduced the frequency and amplitude of spontaneous GABAergic activity in non-seizure control samples. Our results demonstrate the enhanced expression of α4-containing GABA_A receptors and GABAergic activity in pyramidal neurons which in turn may contribute to benzodiazepine resistance in FCD patients.

Possible interplay between the theories of pharmacoresistant epilepsy

Epilepsy is one of the oldest known neurological disorders and is characterized by recurrent seizure activity. It has a high incidence rate, affecting a broad demographic in both developed and developing countries. Comorbid conditions are frequent in patients with epilepsy and have detrimental effects on their quality of life. Current management options for epilepsy include the use of anti-epileptic drugs, surgery, or a ketogenic diet. However, more than 30% of patients diagnosed with epilepsy exhibit drug resistance to anti-epileptic drugs. Further, surgery and ketogenic diets do little to alleviate the symptoms of patients with pharmacoresistant epilepsy. Thus, there is an urgent need to understand the underlying mechanisms of pharmacoresistant epilepsy to design newer and more effective anti-epileptic drugs. Several theories of pharmacoresistant epilepsy have been suggested over the years, the most common being the gene variant hypothesis, network hypothesis, multidrug transporter hypothesis, and target hypothesis. In our review, we discuss the main theories of pharmacoresistant epilepsy and highlight a possible interconnection between their mechanisms that could lead to the development of novel therapies for pharmacoresistant epilepsy.

Exposure to carbon black nanoparticles increases seizure susceptibility in male mice

Carbon black nanoparticles (CBNPs) can enter the central nervous system through blood circulation and olfactory nerves, affecting brain development or increasing neurological disease susceptibility. However, whether CBNPs exposure affects seizure is unclear. Herein, mice were exposed to two different doses of CBNPs (21 and 103 μg/animal) based on previous studies and the maximum exposure limitation (4 mg/m³) in occupational workplaces set by the Chinese government. In the pentylenetetrazol (PTZ) and kainic acid (KA) seizure models, high-dose CBNPs exposure increased seizure susceptibility in both models and increased spontaneous recurrent seizure (SRS) frequency in the KA model. In vivo local field potential (LFP) recording in KA model mice revealed that both low-dose and high-dose CBNPs exposure increased seizure-like event (SLE) frequency in the SRS interval but shortened SLE duration. Intriguingly, H&E staining and Nissl staining on brain tissue revealed that CBNPs exposure did not cause significant brain tissue morphology or neuronal damage. Detection of inflammatory factors, such as TNF-α, TGF-β1, IL-1β, and IL-6, in brain tissue showed that only high dose of CBNPs exposure increased the expression of cortical TGF-β1. By using the primary cultured neurons, we observed that CBNPs exposure not only significantly decreased the expression of the neuronal marker MAP2 but also enhanced the levels of action potential frequency in the neurons. In general, CBNPs exposure can affect abnormal epileptic discharges during the seizure interval and enhance susceptibility to frequent seizures. Our findings suggest that minimizing CBNPs exposure may be a potential way to prevent or ease seizure.

The Demonstration of an Aqp4/Tgf-beta 1 Pathway in Murine Astrocytes Holds Implications for Both Neuromyelitis Optica and Progressive Multiple Sclerosis

The role exerted by Aquaporin 4 (AQP4) as a regulator of astrocyte immune functions has been poorly explored. A recent report demonstrates that under neuroinflammatory conditions, the expression of Aqp4 on murine astrocytes is mandatory for the effective control of acute inflammation in the central nervous system. Such an immunomodulatory function appears to be mediated by a promotion of the transforming growth factor beta 1 (Tgfb1) pathway. Here, these results are discussed in the context of neuromyelitis optica (NMO) and multiple sclerosis (MS) progressive forms. It is proposed that NMO and progressive MS might rely on opposite molecular mechanisms involving, in NMO, an acutely-defective AQP4/TGFB1 pathway and, in progressive MS, a chronically-stimulated AQP4/TGFB1 pathway. Data supporting the involvement of angiotensin II as a molecular link between AQP4 and TGFB1 are also reviewed.

Inhibition mechanism of lung cancer cell metastasis through targeted regulation of Smad3 by miR-15a

Effect of targeted regulation of mothers against decapentaplegic homolog 3 (Smad3) by microRNA-15a (miR-15a) on the proliferation, invasion and metastasis of non-small cell lung cancer (NSCLC) cells and its related mechanisms were investigated. Fifty pairs of NSCLC and para-cancerous tissues were collected to identify the expression level of miR-15a in NSCLC, para-cancerous tissue, and cell lines A549, H1299, H1975 and BEAS-2B by real-time fluorescence quantitative PCR (RT-PCR); A549 cells were transfected with miR-15a mimic; the MTT assay was performed to detect the role of miR-15a transfection in proliferation of A549 cells, the wound healing assay was carried out to identify the role of miR-15a in migration of A549 cells; Transwell invasion assay was conducted to analyze the role of miR-15a in invasion of A549 cells; western blotting was carried out to find the effect of miR-15a on Smad3 expression, and Spearman's rank correlation was used to analyze the correlation between miR-15a and Smad3 expression. NSCLC tissues and cells showed significantly lower miR-15a expression, compared with para-cancerous tissues and normal cell lines (P=0.023). miR-15a was significantly more expressed in A549 cells transfected with miR-15a mimic (P=0.043). Overexpression of miR-15a can significantly inhibit A549 cell proliferation (P=0.038), migration (P=0.033) and invasion (P=0.025), and significantly reduced the expression level of Smad3 (P=0.031) in A549 cells. Spearman's rank correlation showed negative correlation of miR-15a expression with Smad3, which may indicate negative regulation (r=−0.34, P<0.0001). Inhibition of proliferation, migration and invasion of NSCLC cells can be achieved with targeted regulation of Smad3 by miR-15a.

A somatic mutation in MEN1 gene detected in periventricular nodular heterotopia tissue obtained from depth electrodes

Periventricular nodular heterotopia (PNH) is a common structural malformation of cortical development. Mutations in the filamin A gene are frequent in familial cases with X‐linked PNH. However, many cases with sporadic PNH remain genetically unexplained. Although medically refractory epilepsy often brings attention to the underlying PNH, patients are often not candidates for surgical resection. This limits access to neuronal tissue harboring causal mutations. We evaluated a patient with PNH and medically refractory focal epilepsy who underwent a presurgical evaluation with stereotactically placed electroencephalographic (SEEG) depth electrodes. Following SEEG explantation, we collected trace tissue adherent to the electrodes and extracted the DNA. Whole‐exome sequencing performed in a Clinical Laboratory Improvement Amendments–approved genetic diagnostic laboratory uncovered a de novo heterozygous pathogenic variant in novel candidate PNH gene MEN1 (multiple endocrine neoplasia type 1; c.1546dupC, p.R516PfsX15). The variant was absent in an earlier exome profiling of the venous blood–derived DNA. The MEN1 gene encodes the ubiquitously expressed, nuclear scaffold protein menin, a known tumor suppressor gene with an established role in the regulation of transcription, proliferation, differentiation, and genomic integrity. Our study contributes a novel candidate gene in PNH generation and a novel practical approach that integrates electrophysiological and genetic explorations of epilepsy.

Smad Anchor for Receptor Activation and Phospho-Smad3 Were Upregulated in Patients with Temporal Lobe Epilepsy

Smad anchor for receptor activation (SARA) is an important regulator of transforming growth factor β (TGF-β) signaling by recruiting Smad2/3 to TGF-β receptors. We recently demonstrated that the expressions of SARA and level of downstream phospho-Smad3 (p-Smad3) were upregulated in the brain in the epileptic rat model, but were never examined in patients with temporal lobe epilepsy (TLE). In this study, we examined the expressions of SARA and level of p-Smad3 in brain tissues of TLE patients using immunohistochemistry and western blot to demonstrate that SARA activation in neurons is sufficient to facilitate TGF- β pathway in patients to regulate epilepsy. We found that the expressions of SARA and level of p-Smad3 were significantly upregulated in neurons of the temporal cortex of TLE patients compared to controls. Moreover, SARA and p-Smad3 were strongly stained in the cytoplasm in the temporal cortex of TLE patients. Our results indicate that upregulation of SARA and p-Smad3 in cortex neurons might be involved in the development of intractable temporal lobe epilepsy.