Associations between genetic variation in one-carbon metabolism and leukocyte DNA methylation in valproate-treated patients with epilepsy.

BACKGROUND: Valproate (VPA) as a first-line antiepileptic drug is useful for the most types of epileptic seizure treatment. Previous studies observed that VPA influenced one-carbon metabolism (OCM), consequently, DNA methylation. However, other individual genetic variations, as well as VPA, modify DNA methylation. OBJECTIVE: In this study, we investigated associations between genetic variations in OCM and leukocyte DNA methylation in VPA-treated patients with epilepsy. METHODS: This was a cross-sectional study of 101 epileptic patients who underwent VPA monotherapy and 68 healthy controls. All subjects were measured OCM-related nutrients (folate, homocysteine and vitamin B12), and DNA methylation of specific regions were analyzed. Furthermore, we examined the associations between genetic variations in OCM and DNA methylation levels in epileptic patients. RESULTS: VPA-treated patients with epilepsy exhibited both higher serum homocysteine and vitaminB12 levels and lower folate levels relative to controls (P = 0.018, P = 0.003, P < 0.001 respectively), the methylation level of the MTHFR amplicon was significantly lower in the VPA group compared with those in the controls (P = 0.043). VPA-treated epileptic patients carrying the T-allele of methylenetetrahydrofolate reductase (MTHFR) c.677C>T showed higher serum Hcy levels than those observed in the 677CC group (P < 0.01). Epileptic patients who carried G-allele of methionine synthase (MTR) c.2756A>G showed significantly lower MTHFR amplicon methylation levels compared to carriers of the wild-type MTR 2756AA genotype (P = 0.028). CONCLUSION: Our study provided evidence that the MTR c.2756A>G polymorphism is associated with MTHFR amplicon hypomethylation in VPA-treated patients with epilepsy.

HLA-A*24:02 as a common risk factor for antiepileptic drug-induced cutaneous adverse reactions.

OBJECTIVE: To investigate the involvement of human leukocyte antigen (HLA) loci in aromatic antiepileptic drug-induced cutaneous adverse reactions. METHODS: A case-control study was performed to detect HLA loci involved in aromatic antiepileptic drug-induced Stevens-Johnson syndrome in a southern Han Chinese population. Between January 1, 2006, and December 31, 2015, 91 cases of Stevens-Johnson syndrome induced by aromatic antiepileptic drugs and 322 matched drug-tolerant controls were enrolled from 8 centers. Important genotypes were replicated in cases with maculopapular eruption and in the meta-analyses of data from other populations. Sequence-based typing determined the HLA-A, HLA-B, HLA-C, and HLA-DRB1 genotypes. RESULTS: HLA-B*15:02 was confirmed as strongly associated with carbamazepine-induced Stevens-Johnson syndrome (p = 5.63 × 10-15). In addition, HLA-A*24:02 was associated significantly with Stevens-Johnson syndrome induced by the aromatic antiepileptic drugs as a group (p = 1.02 × 10-5) and by individual drugs (carbamazepine p = 0.015, lamotrigine p = 0.005, phenytoin p = 0.027). Logistic regression analysis revealed a multiplicative interaction between HLA-B*15:02 and HLA-A*24:02. Positivity for HLA-A*24:02 and/or HLA-B*15:02 showed a sensitivity of 72.5% and a specificity of 69.0%. The presence of HLA-A*24:02 in cases with maculopapular exanthema was also significantly higher than in controls (p = 0.023). Meta-analysis of data from Japan, Korea, Malaysia, Mexico, Norway, and China revealed a similar association. CONCLUSIONS: HLA-A*24:02 is a common genetic risk factor for cutaneous adverse reactions induced by aromatic antiepileptic drugs in the southern Han Chinese and possibly other ethnic populations. Pretreatment screening is recommended for people in southern China.

Association between mossy fiber sprouting and expression of semaphorin-3f protein in dentate gyrus of hippocampus in lithium-pilocarpine-induced status epilepticus mouse model.

OBJECTIVES: Mossy fiber sprouting is involved in the pathogenesis of mesial temporal lobe epilepsy. But the exact mechanism of formation of mossy fiber sprouting is still unclear. Semaphorin-3f protein could inhibit the growth of neuron axons. The aim of this research is to evaluate the association between semaphorin-3f expression and mossy fiber sprouting. METHODS: We established pilocarpine-induced status epilepticus (PISE) models firstly. Then, mossy fiber sprouting in the hippocampus of PISE models was examined by Timm staining. Expression of semaphorin-3f was evaluated by western blot analysis and immunohistochemical examination. Expression of semaphorin-3f protein in different subregions of hippocampus and its relationship with mossy fiber sprouting were studied. RESULTS: We found that in PISE group, mossy fiber sprouting appeared in dentate gyrus (DG) region. It started to develop in the latent phase of PISE group and increased significantly in the chronic phase. Expression of semaphorin-3f protein in DG region started to decrease in the latent phase, and stayed at low level in the chronic phase. No such change was found in the other groups. CONCLUSIONS: These results indicate that the decrease in semaphorin-3f expression in DG region was in parallel to the change of mossy fiber sprouting in PISE models, suggesting that mossy fiber sprouting is closely associated with reduced expression of semaphorin-3f in this model.

Pluronic P85-coated poly(butylcyanoacrylate) nanoparticles overcome phenytoin resistance in P-glycoprotein overexpressing rats with lithium-pilocarpine-induced chronic temporal lobe epilepsy.

P-glycoprotein (Pgp) overexpression in the blood brain barrier (BBB) is hypothesized to lower brain drug concentrations and thus inhibit anticonvulsant effects in drug-resistant epilepsy. Recently, the poly(butylcyanoacrylate) (PBCA) nanoparticle system was shown to overcome the obstacle of the BBB to deliver drugs into the brain. To determine whether pluronic P85-coated phenytoin poly(butylcyanoacrylate) nanoparticles (P85-PHT-PBCA-NPs) target PHT to the brain, PHT-resistant rats overexpressing Pgp in the BBB were screened by response to PHT treatment after chronic temporal lobe epilepsy induced by lithium-pilocarpine, followed by direct verification of PHT transport via measurement of brain PHT concentrations using microdialysis. Thereafter, the PHT-resistant rats were divided into three groups, which were treated with PHT, PHT + tariquidar (TQD), or P85-PHT-PBCA-NPs. PHT + TQD and P85-PHT-PBCA-NPs showed anticonvulsant activity in the PHT-resistant rats and increased the ratio of the area under the curve of the PHT concentrations in the brain/plasma in comparison with that observed in animals subjected to PHT treatment. However, the ratios of the PHT concentrations in the liver/plasma and kidney/plasma following P85-PHT-PBCA-NPs treatment were much lower than those measured following PHT + TQD treatment. Thus, Pgp overexpression decreases therapeutic drug concentrations in the brains of subjects with drug-resistant epilepsy and P85-PHT-PBCA-NPs could increase these drug concentrations.

Effects of antiepileptic drug monotherapy on one-carbon metabolism and DNA methylation in patients with epilepsy.

PURPOSE: The aim of this study was to compare the serum levels of one-carbon metabolism (OCM) nutrients (e.g., folate, homocysteine and vitamin B12) and peripheral blood DNA methylation in epileptic patients under treatment with antiepileptic drugs (AEDs) and in healthy controls. METHODS: In this cross-sectional study, 60 patients with epilepsy who were receiving valproate (VPA) (n = 30) or lamotrigine (LTG) (n = 30) monotherapy were enrolled. Thirty age and sex matched healthy subjects served as the controls. Serum concentrations of OCM nutrients and peripheral blood DNA methylation status were measured. RESULTS: Compared to the control group, the VPA group had higher serum levels of homocysteine (p<0.05). No difference in homocysteine concentration was observed in the LTG group. Patients receiving VPA or LTG had significantly lower serum folate levels in comparison with controls (p<0.001). The level of methylation of long interspersed nucleotide element-1 (LINE-1) in peripheral blood was not significantly different between the AED monotherapy group and healthy controls. A difference in the methylation levels of methylenetetrahydrofolate reductase (MTHFR) amplicon was observed between AED-treated patients with epilepsy and controls (p<0.01). A positive correlation between serum folate levels and peripheral blood MTHFR amplicon methylation status was also observed (r = 0.25, p = 0.023). CONCLUSION: Our findings suggest that the effects of AED monotherapy on OCM may induce specific regions of DNA hypomethylation.

Increased homocysteine levels in valproate-treated patients with epilepsy: a meta-analysis.

OBJECTIVE: To determine whether valproate (VPA) monotherapy influences homocysteine metabolism in patients with epilepsy. DESIGN: Systematic review and meta-analysis. DATA SOURCES: We searched all articles in English through PubMed, Web of Science and EMBASE published up to August 2013 concerning the homocysteine levels in VPA monotherapeutic patients with epilepsy. PARTICIPANTS: VPA-treated patients with epilepsy (n=266) and matched healthy controls (n=489). OUTCOME MEASURES: Heterogeneity between studies was assessed using I(2) statistics. Pooled standardised mean difference (SMD) and 95% CIs were calculated using a random effect model. RESULTS: A total of eight eligible studies were enrolled in our meta-analysis. We compared the plasma levels of homocysteine in VPA-treated patients with epilepsy and healthy controls. There was significant heterogeneity in the estimates according to the I(2) test (I(2)=65.6%, p=0.005). Plasma homocysteine levels in VPA-treated patients with epilepsy were significantly higher than in healthy controls under a random effect model. (SMD, 0.62; 95% CI 0.32 to 0.92). Further subgroup analyses suggested that no significant differences were present when grouped by ethnicity and age, but the risk of heterogeneity in the West Asian group (I(2)=47.4%, p=0.107) was diminished when compared with that of the overall group (I(2)=65.6%, p=0.005). CONCLUSIONS: Our meta-analysis indicates that VPA monotherapy is associated with the increase in plasma homocysteine levels in patients with epilepsy. Whether this association is influenced by ethnicity needs further research.

[Effects of carbamazepine on plasma concentrations of valproic acid and its toxic metabolite in epileptic patients].

To investigate the effects of carbamazepine (CBZ) on the plasma concentrations of valproic acid (VPA) and its toxic metabolite 2-propyl-4-pentenoic acid (4-ene VPA) in epileptic patients, the plasma concentrations of VPA and 4-ene VPA were determined, and the effect of CBZ on pharmacokinetics of VPA was evaluated. All patients had been divided into two groups (VPA group, n = 87; and VPA+CBZ group, n = 19). As compared to VPA group, the combination of CBZ significantly (P < 0.01) decreased the trough concentration of VPA [VPA group, (69.5 +/- 28.8) microg x mL(-1); VPA+CBZ group, (46.3 +/- 25.6) microg x mL(-1)] and does-adjusted VPA trough concentration [VPA group, (4.89 +/- 2.21) microg x mL(-1) x mg(-1) x kg(-1); VPA+CBZ group, (3.14 +/- 1.74) microg x mL(-1) x mg(-1) x kg(-1)]. However, the addition of CBZ did not influence the concentration of 4-ene VPA. The present study revealed that coadministration of CBZ can reduce VPA plasma concentration and may impact VPA clinical effect, therefore therapeutic drug mornitoring of VPA should be used when combined use of CBZ and VPA.

STE20/SPS1-related proline/alanine-rich kinase is involved in plasticity of GABA signaling function in a mouse model of acquired epilepsy.

The intracellular concentration of chloride ([Cl(-)]i) determines the strength and polarity of GABA neurotransmission. STE20/SPS1-related proline/alanine-rich kinase (SPAK) is known as an indirect regulator of [Cl(-)]i for its activation of Na-K-2 Cl(-)co-transporters (NKCC) and inhibition of K-Cl(-)co-transporters (KCC) in many organs. NKCC1 or KCC2 expression changes have been demonstrated previously in the hippocampal neurons of mice with pilocarpine-induced status epilepticus (PISE). However, it remains unclear whether SPAK modulates [Cl(-)]i via NKCC1 or KCC2 in the brain. Also, there are no data clearly characterizing SPAK expression in cortical or hippocampal neurons or confirming an association between SPAK and epilepsy. In the present study, we examined SPAK expression and co-expression with NKCC1 and KCC2 in the hippocampal neurons of mice with PISE, and we investigated alterations in SPAK expression in the hippocampus of such mice. Significant increases in SPAK mRNA and protein levels were detected during various stages of PISE in the PISE mice in comparison to levels in age-matched sham (control) and blank treatment (control) mice. SPAK and NKCC1 expression increased in vitro, while KCC2 was down-regulated in hippocampal neurons following hypoxic conditioning. However, SPAK overexpression did not influence the expression levels of NKCC1 or KCC2. Using co-immunoprecipitation, we determined that the intensity of interaction between SPAK and NKCC1 and between SPAK and KCC2 increased markedly after oxygen-deprivation, whereas SPAK overexpression strengthened the relationships. The [Cl(-)]i of hippocampal neurons changed in a corresponding manner under the different conditions. Our data suggests that SPAK is involved in the plasticity of GABA signaling function in acquired epilepsy via adjustment of [Cl(-)]i in hippocampal neurons.

Anomalous expression of chloride transporters in the sclerosed hippocampus of mesial temporal lobe epilepsy patients.

The Na(+)-K(+)-Cl(-) cotransporter 1 and K(+)-Cl(-) cotransporter 2 regulate the levels of intracellular chloride in hippocampal cells. Impaired chloride transport by these proteins is thought to be involved in the pathophysiological mechanisms of mesial temporal lobe epilepsy. Imbalance in the relative expression of these two proteins can lead to a collapse of Cl(-) homeostasis, resulting in a loss of gamma-aminobutyric acid-ergic inhibition and even epileptiform discharges. In this study, we investigated the expression of Na(+)-K(+)-Cl(-) cotransporter 1 and K(+)-Cl(-) cotransporter 2 in the sclerosed hippocampus of patients with mesial temporal lobe epilepsy, using western blot analysis and immunohistochemistry. Compared with the histologically normal hippocampus, the sclerosed hippocampus showed increased Na(+)-K(+)-Cl(-) cotransporter 1 expression and decreased K(+)-Cl(-) cotransporter 2 expression, especially in CA2 and the dentate gyrus. The change was more prominent for the Na(+)-K(+)-Cl(-) cotransporter 1 than for the K(+)-Cl(-) cotransporter 2. These experimental findings indicate that the balance between intracellular and extracellular chloride may be disturbed in hippocampal sclerosis, contributing to the hyperexcitability underlying epileptic seizures. Changes in Na(+)-K(+)-Cl(-) cotransporter 1 expression seems to be the main contributor. Our study may shed new light on possible therapies for patients with mesial temporal lobe epilepsy with hippocampal sclerosis.

Polycystic ovary syndrome in patients with epilepsy: a study in 102 Chinese women.

PURPOSE: The incidence of polycystic ovary syndrome (PCOS) increases in women with epilepsy (WWE), which appears to vary with ethnicity. This study was conducted to determine the incidence and risk factors of PCOS in Chinese WWE. METHODS: The study was carried out in 102 of 139 Chinese WWE at reproductive ages, with 32 receiving valproic acid (VPA), 40 receiving other antiepileptic drugs (AEDs), and 30 without AEDs therapy. PCOS was defined as having 2 or more of the following components: polycystic ovaries, hyperandrogenism, and amenorrhoea or oligomenorrhoea (a/oligomenorrhoea). RESULTS: One or more isolated components of PCOS were found in 56 (54.9%) patients, with 29 (28.4%) having polycystic ovaries, 20 (19.6%) with a/oligomenorrhea, 7 (6.9%) with hyperandrogenism, and 13 (12.7%) with defined PCOS. Their average age at the start of seizure was 13.8±6.5 years, younger than that of patients without these disorders (16.9±8.6 years, p<0.05). VPA therapy increased the incidence of PCOS (11/32, 34.4%), in addition to increased blood levels of testosterone and luteinizing hormone (LH) as well as LH to FSH (follicle-stimulating hormone) ratio. No significant relationship was found between the incidence of PCOS and the type, duration, or frequency of seizures in these WWE. CONCLUSION: There is an increased incidence of PCOS in Chinese WWE at reproductive ages, by more than 2 times of that in the general population. Risk factors include seizures starting at a young age and VPA therapy.

Association between HLA and Stevens-Johnson syndrome induced by carbamazepine in Southern Han Chinese: genetic markers besides B*1502?

Previous studies have demonstrated a strong association between carbamazepine-induced Stevens-Johnson syndrome and toxic epidermal necrolysis (CBZ-induced SJS/TEN) and HLA-B*1502 in Chinese, and HLA-A*3101 but not HLA-B*1502 in Caucasians and Japanese. Cases with CBZ-induced SJS/TEN negative for HLA-B*1502 were reported recently in Southeast Asia. Negative correlations between CBZ-induced SJS/TEN and B*0702 or B*4001 have also been reported, suggesting a possible protective role. Here, we genotyped HLA-B and HLA-A in 18 cases with CBZ-induced SJS/TEN, in comparison with CBZ-tolerant and normal controls in Southern Han Chinese. A strong association between HLA-B*1502 and CBZ-induced SJS/TEN was found, with 72.2% sensitivity and 87.1% specificity. However, we also found five patients with SJS (5/18, 27.78%) who were negative for HLA-B*1502. HLA-A*2402 was present in nine of 16 cases with SJS (56.25%, including three of five cases negative for HLA-B*1502), which was significantly more frequent than that of CBZ-tolerant controls or the general southern population. Only one case with SJS carried HLA-A*3101. No statistical difference in the mean age, sex ratio and CBZ usage was found between the CBZ-induced SJS/TEN group and the CBZ-tolerant group. In search for possible protective genetic markers in HLA-B*1502-positive but CBZ-tolerant patients, we failed to find any significant factors in the HLA alleles observed. Given the association between HLA-B*1502 and CBZ-induced SJS/TEN, genetic testing before initiating CBZ therapy is suggested in Han Chinese population. However, physicians should also be vigilant about SJS/TEN in those negative for HLA-B*1502. Other factors for the development of CBZ-induced SJS/TEN in HLA-B*1502-negative patients and protective factors in CBZ-tolerant patients should be investigated further.

Simultaneous determination of valproic acid and 2-propyl-4-pentenoic acid for the prediction of clinical adverse effects in Chinese patients with epilepsy.

Valproic acid (VPA) is a well-established anticonvulsant drug that has been increasingly used in the treatment of many forms of generalized epilepsy. Although there are many reports of adverse effects of VPA, studies focusing on the concentration-response relationships of VPA and its metabolites in patients with epilepsy are extremely limited. In this study, a rapid and specific high performance liquid chromatography-ultraviolet (HPLC-UV) method to simultaneously detect the concentrations of VPA and its major hepatotoxic metabolite 2-propyl-4-pentenoic acid (4-ene VPA) in human plasma has been established, using 2,4'-dibromoacetophenone and octanoic acid as the derivatization reagent and internal standard, respectively. This method was used to analyze plasma samples (n=64) of Chinese patients with epilepsy. The results revealed that 4-ene VPA concentrations in Chinese patients were much higher than those in patients in other countries such as United States and Iran. Significant correlations between aspartate aminotransferase (AST), alanine aminotransferase (ALT) and 4-ene VPA concentration suggest that the simultaneous determination of VPA and 4-ene VPA is an effective tool for the prediction of clinical hepatotoxicity in epileptic patients. Furthermore, the present study describes a less costly and complex technique for the clinical monitoring of VPA plasma levels and the risk of hepatotoxicity which may be of particular interest in developing countries like China.

Association between HLA-B*1502 allele and carbamazepine-induced severe cutaneous adverse reactions in Han people of southern China mainland.

Previous studies have found a strong association between HLA-B*1502 and carbamazepine-induced Stevens-Johnson syndrome in Asian areas including Taiwan, Hongkong and Thailand. This study explores the association between HLA-B*1502 allele and carbamazepine-induced cutaneous adverse reactions in Han Chinese of southern China mainland, and find the genetic marker that can predict carbamazepine-induced cutaneous adverse reactions. HLA-B*1502 allele genotyping was performed by a polymerase chain reaction-sequence specific primers (PCR-SSP) method in 48 Han Chinese subjects who had carbamazepine-induced cutaneous adverse reactions, including 9 severe cutaneous adverse reaction patients with Stevens-Johnson syndrome (SJS) or toxic epidermal necrolysis (TEN) and 39 cutaneous adverse reaction patients with maculopapular eruption (MPE). Meanwhile 80 carbamazepine-tolerant controls and 62 healthy individuals were also tested. The frequency of HLA-B*1502 allele among SJS/TEN patients (100%) is significantly higher than carbamazepine-tolerant controls (13.75%, P<0.001) and healthy individuals (17.74%, P<0.001). But the frequency between MPE patients and carbamazepine-tolerant controls (25.64% vs.13.75%, P=0.110) did not have any significant difference. The data showed that HLA-B*1502 allele is strongly associated with carbamazepine-induced SJS/TEN but not MPE in Han Chinese of southern China mainland.

Analyzing clinical and electrophysiological characteristics of Paroxysmal Dyskinesia.

The classification, clinical and electrophysiological characteristics, treatment outcome and pathogenesis of paroxysmal dyskinesia were summarized and analyzed. Paroxysmal dyskinesia was classified into three types. Different types had different incentives in clinical practice. Patients were mostly male adolescents, and the attacks, which were in various forms, manifested as dysmyotonia of choreoathetosis, body torsion and facemaking; no disturbance of consciousness during attacks. Electroencephalogram and other examinations showed no specific abnormalities during both the attacks and interictal period. Paroxysmal dyskinesia was an independent disease and different from epilepsy.

Long-term increasing co-localization of SCN8A and ankyrin-G in rat hippocampal cornu ammonis 1 after pilocarpine induced status epilepticus.

Voltage-gated sodium channels (VGSC) are important determinants of neuronal excitability which are implicated in the pathogenesis of epilepsy. Ankyrin-G contributes to the distribution and regulation of VGSC. Here we investigated the alterations of the two alpha-subunits SCN8A and SCN1A and their adapter ankyrin-G in the hippocampal cornu ammonis 1 (CA1) of rats after pilocarpine induced status epilepticus (PISE), compared to the sham-control group (C1) and blank-control group (C2). Significant increase of SCN8A mRNA (41.08% increase compared to C1, P<0.001; 30.88% increase compared to C2, P=0.011) was detected 60 days after PISE. At D1 SCN8A mRNA reduced but no significant changes were detected when compared to controls (one-way ANOVA, F=1.232, P=0.276). After measuring the optical density of Western blot, we detected significant differences between the levels of SCN8A protein in different groups but no difference between the protein levels of SCN1A at D1 and D60 after pilocarpine treatment compared to the control. At D60 the relative copies of ankyrin-G mRNA on internal control beta-actin in PISE group increased significantly compared to C1 and C2 (one-way ANOVA, F=16.537, P<0.001). Significantly increase of ankyrin-G immunoreactivity in Western blot from the PISE group 1 day and 60 days after PISE was observed, compared to the controls (one-way ANOVA, F=24.255 at D1, P<0.001; F=29.280 at D60, P<0.001). After analyzing the double-stained cells counting, we detected significant differences between the numbers of SCN8A+/ankyrin-G+ immunoreactive cells in different groups in acute and chronic period following PISE (two way-ANOVA, F(group)=37.905, P<0.001; F(day)=45.310, P<0.001). The data revealed that both SCN8A and ankyrin-G increased significantly in the CA1 subfield of the rat hippocampus 60 days following pilocarpine induced status epilepticus and co-localized with each other.

Long-term expressional changes of Na+ -K+ -Cl- co-transporter 1 (NKCC1) and K+ -Cl- co-transporter 2 (KCC2) in CA1 region of hippocampus following lithium-pilocarpine induced status epilepticus (PISE).

NKCC1 and KCC2 are encoded by slc12 gene family and involved in the maintenance of intracellular chloride concentration which may be associated with epileptogenesis. In this study, we aimed to investigate the long-term expression profiles of NKCC1 and KCC2 in CA1 region in the mice model of lithium-pilocarpine induced status epilepticus (PISE) and their relationship with epileptogenesis. We found NKCC1 mRNA and proteins were up-regulated at 1 d, 14 d and 45 d after pilocarpine injection, while KCC2 was down-regulated. According to obtained results, there were some expressional changes of NKCC1 and KCC2. Deregulation of their expression may break the balance of intracellular and extracellular chloride concentration which contributes to the mechanism of hyperexcitability leading to seizures. Also it may provide new drug targets for development of new antiepileptic medicine.