Role of inflammatory cytokine in mediating the effect of plasma lipidome on epilepsy: a mediation Mendelian randomization study.

Background: Epilepsy is one of the most prevalent serious brain disorders globally, impacting over 70 million individuals. Observational studies have increasingly recognized the impact of plasma lipidome on epilepsy. However, establishing a direct causal link between plasma lipidome and epilepsy remains elusive due to inherent confounders and the complexities of reverse causality. This study aims to investigate the causal relationship between specific plasma lipidome and epilepsy, along with their intermediary mediators. Methods: We conducted a two-sample Mendelian randomization (MR) and mediation MR analysis to evaluate the causal effects of 179 plasma lipidomes and epilepsy, with a focus on the inflammatory cytokine as a potential mediator based on the genome-wide association study. The primary methodological approach utilized inverse variance weighting, complemented by a range of other estimators. A set of sensitivity analyses, including Cochran's Q test, I 2 statistics, MR-Egger intercept test, MR-PRESSO global test and leave-one-out sensitivity analyses was performed to assess the robustness, heterogeneity and horizontal pleiotropy of results. Results: Our findings revealed a positive correlation between Phosphatidylcholine (18:1_18:1) levels with epilepsy risk (OR = 1.105, 95% CI: 1.036-1.178, p = 0.002). Notably, our mediation MR results propose Tumor necrosis factor ligand superfamily member 12 levels (TNFSF12) as a mediator of the relationship between Phosphatidylcholine (18,1_18:1) levels and epilepsy risk, explaining a mediation proportion of 4.58% [mediation effect: (b = 0.00455, 95% CI: -0.00120-0.01030), Z = 1.552]. Conclusion: Our research confirms a genetic causal relationship between Phosphatidylcholine (18:1_18:1) levels and epilepsy, emphasizing the potential mediating role of TNFSF12 and provide valuable insights for future clinical investigations into epilepsy.

Sequencing of neurofilament genes identified NEFH Ser787Arg as a novel risk variant of sporadic amyotrophic lateral sclerosis in Chinese subjects.

BACKGROUND: Amyotrophic lateral sclerosis (ALS) is a devastating neurodegenerative disease with neuronal cell inclusions composed of neurofilaments and other abnormal aggregative proteins as pathological hallmarks. Approximately 90% of patients have sporadic cases (sALS), and at least 4 genes, i.e. C9orf72, SOD1, FUS and TARDBP, have been identified as the main causative genes, while many others have been proposed as potential risk genes. However, these mutations could explain only ~ 10% of sALS cases. The neurofilament polypeptides encoded by NEFH, NEFM, and NEFL are promising protein biomarkers for ALS and other degenerative diseases. However, whether the genetic variants of these genes were associated with ALS remain ambiguous. METHODS: Here, we used PCR-Sanger to sequence the exons of these three genes in a cohort of 371 sALS patients and 711 healthy controls (Phase I) and validated the risk variant in another 300 sALS patients and 1076 controls (Phase II). RESULTS: A total of 92 variants were identified, including 36 rare heterozygous variants in NEFH, 27 in NEFM, and 16 in NEFL, and only rs568759161 (p.Ser787Arg) in NEFH reached nominal statistical power (P = 0.02 at Phase I, P = 0.009 at Phase II) in the case-control comparison. Together, the Phase I and II studies showed the significantly higher frequency of the variant in cases (9/1342, 0.67%) than in controls (2/3574, 0.07%) (OR 12.06; 95% CI 2.60-55.88; P = 0.0003). No variants passed multiple testing in the discovery cohort, but rs568759161 was associated with ALS in a replication cohort. CONCLUSIONS: Our results confirmed that NEFH Ser787Arg is a novel sALS risk variant in Chinese subjects, but NEFM and NEFL were not associated with sALS. These data may have implications for genetic counselling and for understanding the pathogenesis of sALS.

Over-expression of 5-HT6 Receptor and Activated Jab-1/p-c-Jun Play Important Roles in Pilocarpine-Induced Seizures and Learning-Memory Impairment.

Cognitive impairment is a common comorbidity in patients with temporal lobe epilepsy (TLE) that severely affects patients' quality of life. Also, serotonin 5-hydroxytryptamine 6 (5-HT6) receptor plays an important role in cognition. This study aimed to investigate effects of 5-HT6 receptor on learning-memory capacities in epileptic rats. Total of 36 adult Sprague-Dawley (SD) rats were divided into vehicle (n = 6) and epileptic group (n = 30). Status epilepticus (SE) was induced via systemic injection of pilocarpine. Epileptic group was sub-divided into vehicle, 10, 20, and 30 µg SB-271046 groups, six mice per group. Learning-memory performance of rats was evaluated by using Y maze and Morris water maze test. 5-HT6 receptor expression was examined using immunostaining and Western blot. The other six rats were used to make epileptic model and Jab-1/p-c-Jun were detected. Results showed that frequency of spontaneous recurrent seizures (SRSs) was significantly decreased in pilocarpine-induced epileptic rats that treated with SB-271046. Alternation rate and new arm percentage were decreased in epileptic rats compared to control. The 5-day mean latency was prolonged in epileptic rats compared to control rats. During retention stage, mean latency, number of target crossings, and percentage of time spent in target zone were decreased in epileptic rats, but not in those treated with SB-271046. The number of apoptotic neurons was significantly increased in epileptic rats, which was decreased by SB-271046. 5-HT6 expression was significantly increased in hippocampus and cortex following recurrent seizures. Jab-1 level was decreased after SB-271046 administration. p-c-Jun level was elevated in epileptic rats and decreased in a dose-dependent manner after the SB-271046 administration. In conclusion, the over-expression of 5-HT6 receptor and activated Jab-1/p-c-Jun plays an important role in pilocarpine-induced seizures and learning-memory impairment.

Novel insights into the effect of paroxetine administration in pilocarpine­induced chronic epileptic rats.

The aim of the present study was to investigate the role of paroxetine intervention in epilepsy, and its association with the expression of serotonin transporter (SERT) and hippocampal apoptosis. Thirty adult male Sprague Dawley rats were divided into control vehicle (n=6) and epileptic (n=24) groups. Status epilepticus (SE) was induced via systemic injection of pilocarpine, and seizure activity was monitored via video electroencephalogram. The epileptic group was then randomly divided into two groups; Four weeks following SE induction, paroxetine (5 mg/kg/day; SE + paroxetine group) or normal saline (SE group) was intraperitoneally injected for 4 weeks. Brain tissue was collected to evaluate apoptosis via terminal deoxynucleotidyl transferase dUTP nick­end labeling. SERT, B­cell lymphoma­2 (Bcl­2) and brain derived neurotropic factor (BDNF) expression levels were evaluated by western blotting, and miR­16 expression was evaluated by reverse transcription­quantitative polymerase chain reaction. Paroxetine did not affect the mortality of the pilocarpine­induced chronic epileptic rats. Spontaneous recurrent seizures (SSRs) were observed 7­28 days following SE induction. The frequency and stage of the SSRs were reduced by paroxetine administration. Apoptotic cells were observed in the epileptic hippocampus. Following paroxetine intervention, the staining intensity and number of apoptotic cells were significantly decreased. Expression levels of BDNF and Bcl­2 were lower in the SE group compared with the vehicle group. The former was not altered by paroxetine injection; however, the latter was increased. In the SE group, SERT expression was not altered in the raphe nucleus but was decreased in the hippocampus. Following paroxetine administration, SERT expression was decreased in the raphe nucleus and increased in the hippocampus. In the SE group, miR­16 expression was decreased in the raphe nucleus and increased in the hippocampus. Following paroxetine administration, miR­16 expression was not altered in the raphe nucleus but was reduced in the hippocampus. In conclusion, the seizures and hippocampal apoptosis observed in chronic epileptic rats were alleviated by paroxetine treatment. This effect may be associated with the reduced Bcl­2 and BDNF expression and the modulation of SERT expression. The alterations in miR­16 expression may provide a potential explanation for the modulation of apoptosis; however, further research is required to determine the complete underlying molecular mechanism.

The Role of 5-HTR6 in Mossy Fiber Sprouting: Activating Fyn and p-ERK1/2 in Pilocarpine-Induced Chronic Epileptic Rats.

OBJECTIVE: Our primary objective is to verify whether 5-HTR6 is involved in the development of mossy fiber sprouting (MFS), and to determine how the progression of MFS is affected by 5-HTR6. METHODS: A total of 90 male adult Sprague-Dawley rats were allocated into either the control group (n=36) or the epileptic group (n=54). Status epilepticus (SE) of rats was induced by the intraperitoneal (i.p.) injection of LiCl-pilocarpine. We conducted our experiments in two stages. The first stage involves equally dividing 36 epileptic rats into three groups with treatments of none, 5-HTR6 antagonist SB-27104 (SB) and vehicle DMSO. Then behavior and electroencephalogram (EEG) of rats were monitored by video-EEG. The second stage involves dividing 126 epileptic rats into seven groups with treatments of none, 10% DMSO, SB (100 µg/kg), Fyn antagonist PP2 (50 µg/kg), p-ERK1/2 antagonist PD-98059 (30 µg/kg), SB (100 µg/ kg) + PP2 (50 µg/kg); SB (100 µg/kg) + PD-98059 (30 µg/kg). We also treated 18 rats in the control group of the first stage with 100 µg/kg 5-HTR6 agonist WAY-181187 (WAY). MFS of rats was detected through the approach of Timm's staining. Finally, expressions of 5-HTR6, Fyn, p-ERK1/2 and GAP-3 were qualified and semi-quantified via western blotting or RT-PCR. RESULTS: Induction of SE could stimulate formation of MFS and increased GAP-43 expressions. Expressions of 5-HTR6, Fyn and p-ERK1/2 were also up-regulated with increasing time after establishment of SE models. The development of MFS was remarkably inhibited by SB, PP2 and PD. Compared to the single antagonist, such an inhibitory effect was enhanced by SB+PD or SB+PP. Moreover, treatment of healthy rats with WAY would contribute to up-regulated Fyn and p-ERK1/2 expressions, as well as development of MFS (P < 0.05). Suppression of Fyn triggered a down-regulating trend of p-ERK1/2 (P < 0.05), however, suppressed p-ERK1/2 did not have such a significant effect on Fyn expression. CONCLUSION: HTR6 may affect the progression of MFS by activating both p-ERK1/2 and Fyn, which further modulate the expression of GAP-43.