Epilepsy research in 2022: clinical advances

Identification of a new retigabine derivative with improved photostability for selective activation of neuronal Kv7 channels and antiseizure activity

OBJECTIVE

Pharmacological activation of neuronal Kv7 channels by the antiepileptic drug retigabine (RTG; ezogabine) has been proven effective in treating partial epilepsy. However, RTG was withdrawn from the market due to the toxicity caused by its phenazinium dimer metabolites, leading to peripheral skin discoloration and retinal abnormalities. To address the undesirable metabolic properties of RTG and prevent the formation of phenazinium dimers, we made chemical modifications to RTG, resulting in a new RTG derivative, 1025c, N,N'-{4-[(4-fluorobenzyl) (prop-2-yn-1-yl)amino]-1,2-phenylene}bis(3,3-dimethylbutanamide).

METHODS

Whole-cell recordings were used to evaluate Kv7 channel openers. Site-directed mutagenesis and molecular docking were adopted to investigate the molecular mechanism underlying 1025c and Kv7.2 interactions. Mouse seizure models of maximal electroshock (MES), subcutaneous pentylenetetrazol (scPTZ), and PTZ-induced kindling were utilized to test compound antiepileptic activity.

RESULTS

The novel compound 1025c selectively activates whole-cell Kv7.2/7.3 currents in a concentration-dependent manner, with half-maximal effective concentration of .91 ± .17 μmol·L-1. The 1025c compound also causes a leftward shift in Kv7.2/7.3 current activation toward a more hyperpolarized membrane potential, with a shift of the half voltage of maximal activation (ΔV1/2) of -18.6 ± 3.0 mV. Intraperitoneal administration of 1025c demonstrates dose-dependent antiseizure activities in assays of MES, scPTZ, and PTZ-induced kindling models. Moreover, through site-directed mutagenesis combined with molecular docking, a key residue Trp236 has been identified as critical for 1025c-mediated activation of Kv7.2 channels. Photostability experiments further reveal that 1025c is more photostable than RTG and is unable to dimerize.

SIGNIFICANCE

Our findings demonstrate that 1025c exhibits potent and selective activation of neuronal Kv7 channels without being metabolized to phenazinium dimers, suggesting its developmental potential as an antiseizure agent for therapy.

Composition and influencing factors of hospitalization expenses for epilepsy patients based on path analysis

OBJECTIVE

This study aimed to understand the composition and influencing factors of epilepsy patients' hospitalization expenses, thus providing a reference for reducing the disease burden of epilepsy patients in low- and middle-income developing countries.

METHODS

A total of 4206 hospitalized cases of epilepsy from 2018 to 2020 were collected. Descriptive statistics were used to understand the patient cost composition, path analysis was used to understand the direct and indirect factors of hospitalization expenses.

RESULTS

From 2018 to 2020, the average hospitalization expenses for epilepsy patients was 4,299.93 RMB yuan, and the average length of stay was 2.47 days. The highest proportion of hospitalization expenses was diagnosis costs (> 50%), followed by comprehensive medical service costs and drug costs. In terms of the total effect coefficient, the major factors affecting the hospitalization expenses were length of stay (0.880), emergency admission(0.463), and the comorbidities and complications(> 0.250). Hospital length of stay, discharge mode(death) and number of hospitalizations(2 times) affect hospitalization expenses through direct effect. Long-term hospitalization (> 30 days), admission routes(emergency), the comorbidities and complications, presence of drug allergy, and age also affect hospitalization expenses through indirect effects.

CONCLUSION

Diagnosis costs and length of stay are important factors affecting the medical expenses of epilepsy inpatients. In general, the quality control of the hospital is good, but it still needs to standardize the diagnosis and treatment behavior of medical staff through the clinical path.

Cannabidiol Anticonvulsant Effects Against Lithium-Pilocarpine-Induced Status Epilepticus in Male Rats Are Mediated by Neuroinflammation Modulation and Cannabinoids 1 (CB1), But Not CB2 and GABAA Receptors

Background: Status epilepticus (SE) is a series of seizures that can lead to serious neurological damages. Cannabidiol (CBD) is extracted from the cannabis plant, which has been approved as an antiseizure medication. This study aimed to determine the efficacy of various doses of CBD on lithium-pilocarpine-induced SE in rats and possible involvement of multiple pharmacological pathways. We hypothesized that cannabinoid receptors type 1 (CB1) and CB2, as well as GABAA receptors, might have important roles in the anticonvulsant effects of CBD against SE by its anti-inflammatory effects. Methods: SE was induced by intraperitoneal (i.p.) injection of lithium (127 mg/kg, i.p.) and pilocarpine (60 mg/kg, i.p., 20 h after lithium). Forty-two male rats were divided into seven groups (including control and sham groups), and the treated groups received different doses of CBD (1, 3, 5, 10, and 25 mg/kg, i.p.). SE score was recorded over the next 2 h following pilocarpine injection. Then, we measured the levels of pro-inflammatory cytokines, including interleukin (IL)-lβ and tumor necrosis factor (TNF)-α, using ELISA kits. Also we analyzed the expression of CB1, CB2, and GABAA receptors using the Western blot technique. Results: CBD at 5 mg/kg significantly reduced Racine's scale and duration of seizures, and increased the onset time of seizure. Moreover, CBD 5 mg/kg caused significant reductions in the elevated levels of IL-lβ and TNF-α, as well as a significant increase in the decreased level of CB1 receptor expression compared to the control group. In other word, CBD reverted the effects of SE in terms of neuroinflammation and CB1 receptor. Based on the obtained results, CBD was not able to restore the declined levels of CB2 or GABAA receptors. Conclusion: Our study found anticonvulsant effects of CBD on the SE rat model induced by lithium-pilocarpine with probable involvement of CB1 receptors and anti-inflammatory effects by reducing IL-1β and TNF-α markers independent of CB2 and GABAA receptors.

The burden of epilepsy in the People's Republic of China from 1990 to 2019: epidemiological trends and comparison with the global burden of epilepsy

Background

Epilepsy is associated with a significant global burden of disease, affecting over 50 million people worldwide. The specific aim of this study is to compare the burden of epilepsy in the People's Republic of China (PRC) with the global burden, and to analyze the epidemiological trends of epilepsy, the relationship between the burden of epilepsy and social demographic index (SDI), and the relative contributions of epidemiological factors.

Methods

This is a retrospective population-based study, data were obtained from the Global Burden of Disease (GBD) study in 2019. We employed Joinpoint software and the age-period-cohort (APC) model to analyze epilepsy's epidemiological trends. Health inequality analysis was conducted to investigate the impact of SDI on epilepsy burden. Decomposition analysis was performed to examine the relative contributions of age, population, and epidemiological changes to epilepsy.

Results

Between 1990 and 2019, the incidence rate in the PRC increased by 45%, significantly surpassing the global incidence of epilepsy. However, Disability-Adjusted Life Years (DALY) decreased notably, and the proportion of Years of Life Lost (YLL) decreased from 62.73 to 39.03%. Concerning incidence, the period Rate Ratio (RR) in the PRC initially increased and then decreased, while the cohort RR in the PRC and globally exhibited a consistent upward trend. In terms of mortality, period RR and cohort RR in the PRC displayed a gradual decrease, with mortality starting higher but eventually falling below the global mortality. The net drifts of incidence were greater than 0, whereas the net drifts of mortality were less than 0, both were lower in the PRC than at the global level. Decomposition analysis indicated that the changes of incidence and mortality in the PRC were mainly attributed to epidemiological changes. Additionally, global disparities in epilepsy decreased, with the burden concentrating in low SDI countries.

Conclusion

The incidence of epilepsy in the PRC rose during the 30-year study period, while epilepsy mortality decreased. The improved survival rate in the PRC is predominantly attributable to epidemiological changes. The burden of epilepsy in the PRC predominantly affects males, children, and the elderly, Chinese government should focus on specific populations.

Epilepsy: Mitochondrial connections to the 'Sacred' disease

Over 65 million people suffer from recurrent, unprovoked seizures. The lack of validated biomarkers specific for myriad forms of epilepsy makes diagnosis challenging. Diagnosis and monitoring of childhood epilepsy add to the need for non-invasive biomarkers, especially when evaluating antiseizure medications. Although underlying mechanisms of epileptogenesis are not fully understood, evidence for mitochondrial involvement is substantial. Seizures affect 35%-60% of patients diagnosed with mitochondrial diseases. Mitochondrial dysfunction is pathophysiological in various epilepsies, including those of non-mitochondrial origin. Decreased ATP production caused by malfunctioning brain cell mitochondria leads to altered neuronal bioenergetics, metabolism and neurological complications, including seizures. Iron-dependent lipid peroxidation initiates ferroptosis, a cell death pathway that aligns with altered mitochondrial bioenergetics, metabolism and morphology found in neurodegenerative diseases (NDDs). Studies in mouse genetic models with seizure phenotypes where the function of an essential selenoprotein (GPX4) is targeted suggest roles for ferroptosis in epilepsy. GPX4 is pivotal in NDDs, where selenium protects interneurons from ferroptosis. Selenium is an essential central nervous system micronutrient and trace element. Low serum concentrations of selenium and other trace elements and minerals, including iron, are noted in diagnosing childhood epilepsy. Selenium supplements alleviate intractable seizures in children with reduced GPX activity. Copper and cuproptosis, like iron and ferroptosis, link to mitochondria and NDDs. Connecting these mechanistic pathways to selenoproteins provides new insights into treating seizures, pointing to using medicines including prodrugs of lipoic acid to treat epilepsy and to potential alternative therapeutic approaches including transcranial magnetic stimulation (transcranial), photobiomodulation and vagus nerve stimulation.