Iris Angélica Feria-Romero

GABAergic Alterations in Neocortex of Patients with Pharmacoresistant Temporal Lobe Epilepsy Can Explain the Comorbidity of Anxiety and Depression: The Potential Impact of Clinical Factors

Temporal lobe epilepsy (TLE) is a chronic neurodegenerative disease with a high prevalence of psychiatric disorders. Temporal neocortex contributes to either seizure propagation or generation in TLE, a situation that has been associated with alterations of the γ-amino-butyric acid (GABA) system. On the other hand, an impaired neurotransmission mediated by GABA in temporal neocortex has also been involved with the pathophysiology of psychiatric disorders. In spite of these situations, the role of the necortical GABA system in the comorbidity of TLE and mood disorders has not been investigated. The present study was designed to identify alterations in the GABA system such as binding to GABAA and GABAB receptors and benzodiazepine site, the tissue content of GABA and the expression of the mRNA encoding the α1–6, β1–3, and γ GABAA subunits, in the temporal neocortex of surgically treated patients with TLE with and without anxiety, and/or depression. Neocortex of patients with TLE and comorbid anxiety and/or depression showed increased expression of the mRNA encoding the γ2-subunit, reduced GABAB-induced G-protein activation in spite of elevated GABAB binding, and lower tissue content of GABA when compared to autopsy controls. Some of these changes significantly correlated with seizure frequency and duration of epilepsy. The results obtained suggest a dysfunction of the GABAergic neurotransmission in temporal neocortex of patients with TLE and comorbid anxiety and/or depression that could be also influenced by clinical factors such as seizure frequency and duration of illness.

MDR-1 and MRP2 Gene Polymorphisms in Mexican Epileptic Pediatric Patients with Complex Partial Seizures.

Although the Pgp efflux transport protein is overexpressed in resected tissue of patients with epilepsy, the presence of polymorphisms in MDR1/ABCB1 and MRP2/ABCC2 in patients with antiepileptic-drugs resistant epilepsy (ADR) is controversial. The aim of this study was to perform an exploratory study to identify nucleotide changes and search new and reported mutations in patients with ADR and patients with good response (CTR) to antiepileptic drugs (AEDs) in a rigorously selected population. We analyzed 22 samples In Material and Methods, from drug-resistant patients with epilepsy and 7 samples from patients with good response to AEDs. Genomic DNA was obtained from leukocytes. Eleven exons in both genes were genotyped. The concentration of drugs in saliva and plasma was determined. The concentration of valproic acid in saliva was lower in ADR than in CRT. In ABCB1, five reported SNPs and five unreported nucleotide changes were identified; rs2229109 (GA) and rs2032582 (AT and AG) were found only in the ADR. Of six SNPs associated with the ABCC2 that were found in the study population, rs3740066 (TT) and 66744T > A (TG) were found only in the ADR. The strongest risk factor in the ABCB1 gene was identified as the TA genotype of rs2032582, whereas for the ABCC2 gene the strongest risk factor was the T allele of rs3740066. The screening of SNPs in ACBC1 and ABCC2 indicates that the Mexican patients with epilepsy in this study display frequently reported ABCC1 polymorphisms; however, in the study subjects with a higher risk factor for drug resistance, new nucleotide changes were found in the ABCC2 gene. Thus, the population of Mexican patients with AED-resistant epilepsy (ADR) used in this study exhibits genetic variability with respect to those reported in other study populations; however, it is necessary to explore this polymorphism in a larger population of patients with ADR.

Intranasal Anti-rabies DNA Immunization Promotes a Th1-related Cytokine Stimulation Associated with Plasmid Survival Time

BACKGROUND AND AIMS DNA vaccination has a great potential to decrease infectious diseases worldwide, such as rabies. Here we showed the effects of a single anti-rabies DNA vaccination applied intranasally (IN) on plasmid survival time, neutralizing antibody (NA) titers, G-protein expression and Th1/Th2-related cytokines. METHODS Only one 50-μg dose of an anti-rabies DNA vaccine was IN administered to 160 Balb/c mice. Twenty mice were used for the neutralizing antibody study, 35 for the proliferation assay, 35 for Th1/Th2-related cytokines, 35 for glycoprotein expression by immunocytochemistry, and 35 for pGQH detection and G-protein mRNA expression. RESULTS Th1-type related cytokines from spleen cells (IFN-γ, TNF-α, and IL-2) were detected. Rabies NA titers were ≥0.6 IUs from day 30 onward in the IN DNA-vaccinated group. The plasmid was identified in brains and lungs from days 3-15. The mRNA transcript was amplified in brains and lungs from days 3-30, and G-protein expression was observed in spleens, brains and lungs on days 3, 8, and 15. In all cases, a gradual decrease was observed on days 30 and 45 and absent on day 60. CONCLUSIONS We found that Th1-type related cytokines (IL-2, IFN-γ, and TNF-α) were stimulated during the first month after DNA vaccination, correlating with the proliferation assays. Also, it was associated with the plasmid survival time remaining in lungs and brains prior to its degradation.

Frequency of the Serological Reactivity Against the Caprine Arthritis Encephalitis Lentivirus gp135 in Children Who Consume Goat Milk

BACKGROUND Caprine arthritis encephalitis virus (CAEV) is a retrovirus belonging to the lentivirus genus that also includes the human immunodeficiency virus (HIV). CAEV may be transmitted to humans by goat milk consumption. It has been suggested that CAEV may also be involved in the immunological protection process against HIV, but this has not been demonstrated. Here we identified serological reactivity against CAEV gp135 in children who consumed goat milk. METHODS Thirty sera samples from children (males between 6 and 16 years of age) who regularly consumed goat milk and a negative control of 30 serum samples from children (males between 6 and 12 years) with no previous contact with goats or goat dairy products were used. All sera were tested by Western blot against CAEV antigens. RESULTS There were 18/30 serum samples from goat milk consumers that were reactive to CAEV gp135, and one reacted against gp50 simultaneously; none of the 30 serum samples from nonconsumers of goat dairy products reacted to viral proteins. CONCLUSIONS These results showed that the positive response to gp135 may be the result of a repetitive stimulation without viral replication or the result of CAEV replication in humans. CAEV gp135 is codified by the env gene located on the viral particle surface as well as gp50. Moreover, there are similarities between CAEV gp135 and HIV-1 gp120, so there is a possibility that CAEV replicates in humans and may participate in immunological cross-phenomena, but this should be further studied.

Chronic administration of phenytoin induces efflux transporter overexpression in rats.

BACKGROUND Efflux transporters overexpression has been proposed as one of the responsible mechanism for refractory epilepsy by preventing access of the antiepileptic drug to the brain. In this work we investigated whether phenytoin (PHT), could induce efflux transporters overexpression, at different biological barriers and to evaluate the implication it could have on its pharmacokinetics and therapeutic/toxic response. METHODS Forty-two adult females Sprague Dawley divided in five groups were treated with oral doses of 25, 50 and 75mg/kg/6h of PHT for 3 days and two additionally groups were treated with intraperitoneal (ip) doses of 25mg/kg/6h or 100mg/kg/24h. At day 4 PHT plasma concentrations were measured and, obtained several organs, brain, parotid gland, liver and duodenum in which were analyzed for the Pgp expression. At day 4 PHT plasma concentrations were measured and several tissues: brain, parotid gland, liver and duodenum were obtained in order to analyze Pgp expression. In order to evaluate the oral bioavailability of PHT, two groups were administered with oral or intraperitoneal doses of 100mg/kg and plasma level were measured. RESULTS An induction of the expression of efflux transporter mediated by phenytoin in a concentration-and-time dependent manner was found when increasing oral and ip doses of phenytoin, One week after the interruption of ip treatment a basal expression of transporters was recovered. CONCLUSIONS Overexpression of efflux transporters can be mediated by inducer agents like PHT in a local-concentration dependent manner, and it is reversible once the substance is removed from the body. The recovery of basal Pgp expression could allow the design of dosing schedules that optimize anticonvulsant therapy.

Influence of genetic variants of CYP2D6, CYP2C9, CYP2C19 and CYP3A4 on antiepileptic drug metabolism in pediatric patients with refractory epilepsy

BACKGROUND Identified the polymorphisms of CYP2D6, CYP2C9, CYP2C19 and CYP3A4, within a rigorously selected population of pediatric patients with drug-resistant epilepsy. METHOD The genomic DNA of 23 drug-resistant epilepsy patients and 7 patients with good responses were analyzed. Ten exons in these four genes were genotyped, and the drug concentrations in saliva and plasma were determined. RESULTS The relevant SNPs with pharmacogenomics relations were CYP2D6*2 (rs16947) decreased your activity and CYP2D6*4 (rs1065852), CYP2C19*2 (rs4244285) and CYP3A4*1B (rs2740574) by association with poor metabolizer. The strongest risk factors were found in the AA genotype and allele of SNP rs3892097 from the CYP2D6 gene, followed by the alleles A and T of SNPs rs2740574 and rs2687116, respectively from CYP3A4. The most important concomitance was between homozygous genotype AA of rs3892097 and genotype AA of rs2740574 with 78.3% in drug-resistant epilepsy patients as compared to 14.3% in control patients. CONCLUSION The results demonstrated the important role of the CYP 3A4*1B allelic variant as risk factor for developing drug resistance and CYP2D6, CYP2C19 SNPs and haplotypes may affect the response to antiepileptic drugs.BACKGROUND Identified the polymorphisms of CYP2D6, CYP2C9, CYP2C19 and CYP3A4, within a rigorously selected population of pediatric patients with drug-resistant epilepsy. METHOD The genomic DNA of 23 drug-resistant epilepsy patients and 7 patients with good responses were analyzed. Ten exons in these four genes were genotyped, and the drug concentrations in saliva and plasma were determined. RESULTS The relevant SNPs with pharmacogenomics relations were CYP2D6*2 (rs16947) decreased your activity and CYP2D6*4 (rs1065852), CYP2C19*2 (rs4244285) and CYP3A4*1B (rs2740574) by association with poor metabolizer. The strongest risk factors were found in the AA genotype and allele of SNP rs3892097 from the CYP2D6 gene, followed by the alleles A and T of SNPs rs2740574 and rs2687116, respectively from CYP3A4. The most important concomitance was between homozygous genotype AA of rs3892097 and genotype AA of rs2740574 with 78.3% in drug-resistant epilepsy patients as compared to 14.3% in control patients. CONCLUSION The results demonstrated the important role of the CYP 3A4*1B allelic variant as risk factor for developing drug resistance and CYP2D6, CYP2C19 SNPs and haplotypes may affect the response to antiepileptic drugs.

Mecanismos de neurodegeneración en la epilepsia del lóbulo temporal

La epilepsia es una enfermedad que afecta entre el 1 al 2% de la poblacion mundial, siendo la epilepsia del lobulo temporal (ELT) la que abarca el 40% de todos los casos de epilepsia. La controversia en definir a la epilepsia como una enfermedad neurodegenerativa, se debe a que no hay pruebas suficientes que demuestren como las convulsiones y el estado de mal epileptico (SE) provocan un dano neuronal irreversible. El insulto epileptogenico presente al inicio de la enfermedad genera la muerte neuronal aguda y tardia, para dar lugar a la gliosis; pero tambien se desencadenan procesos compensatorios como la angiogenesis, la proliferacion celular y una reorganizacion tanto de la matriz extracelular como de los receptores, canales y proteinas transportadoras de farmacos. En el caso de la neurogenesis y recrecimiento axonal, la edad de inicio es determinante para la formacion de neuronas anormales y circuitos aberrantes como consecuencia de las convulsiones, donde aproximadamente un 30% comienzan en el lobulo temporal. Estas alteraciones se continuan en paralelo o de forma secuencia! durante la evolucion de la epilepsia, lo que implica un gran desafio en la busqueda de nuevos tratamientos.

Contribution of the Antiepileptic Drug Administration Regime in the Development and/or Establishment of Pharmacoresistant Epilepsy

Overexpression of membrane transporters is one of the main pharmacokinetic reasons that lead to the lack of response of antiepileptics in drug refractory treatments. The present chapter deals with the difficulty anticonvulsant agents have in reaching the brain receptor sites.

Abnormalities of GABA System and Human Pharmacoresistant Epilepsy

Despite the availability of various newly developed antiepileptic drugs (AEDs), pharmacoresistance remains a major challenge in epilepsy management. Unraveling the mechanisms underlying AED resistance has been the focus of intense efforts, in order to develop new rationally designed therapies for as yet refractory epilepsies. Based on experimental and clinical studies, one of the major neurobiological theories that has been put forward is the target hypothesis, which suggests that AEDs are not effective because of target alterations in the epileptogenic brain. Several studies have shown that seizure activity results in altered expression of gamma-aminobutyric acid (GABA) components such as GABA transporters (GATs) and GABA receptors. Indeed, changes in the composition of subunits expression appear to affect the functioning of GABAergic neurotransmission. Here, we review the current literature on epilepsy-associated changes in the GABA system conducted in experimental models and observations made in patients with treatment-resistant epilepsy, as well as genetic abnormalities in the GABA system in refractory human epilepsy.

Immunomodulatory effect of Celecoxib on HMGB1/TLR4 pathway in a recurrent seizures model in immature rats

ABSTRACT Epileptic seizures constitute an important problem in pediatric neurology during the developmental period. The frequency and nosological significance of seizures, as well as their association with epileptogenesis, may be related to underlying mechanisms such as neuroinflammation. Those mechanisms of response activate inflammatory molecules induced in the neurons, activated glial cells and endothelial cells via the key HMGB1/TLR4 pathway. In this study, the drug celecoxib (CCX) was used as a blocker of the cyclooxygenase 2 (COX‐2) and HMGB1/TLR‐4 pathways. The experimental model was implemented in 10‐day‐old neonatal Sprague Dawley rats to induce recurrent seizures with kainic acid (KA, 1.4 mg/kg). Data were evaluated at early (14 PND) and late (30 PND) time points. The results showed that the CCX and CCX + pentobarbital (PB) groups exhibited a protective effect by significantly increasing the time latency of seizures compared to the KA group at both early (p < 0.01) and late (p < 0.001) times. When the CCX group was compared to the KA group, there was also a significant decrease in the number of HMGB1 and TLR‐4 transcripts (p < 0.05) and in COX‐2 protein expression (p < 0.05) in the most important areas for seizure generation (the hippocampus and cortex) at both the early and late time points. These results demonstrated that CCX treatment after epileptic seizures has a neuroprotective effect due to the inhibition of proinflammatory proteins and associated signaling pathways and reduces seizure susceptibility. Additionally, the timely intervention of inflammatory pathways will reduce the risk of developing epilepsy in adulthood. Graphical abstract The post‐treatment effect of CCX administration in a KA‐induced seizures immature rats model was assessed in 14 PND and 30 PND animals, through clinical manifestations and expression of the pro‐inflammatory molecules TLR4, HMGB1 and COX‐2 in susceptible brain areas of seizures generation, and at risk of generating epileptogenesis in adulthood. Figure. No caption available. HighlightsKA induces a reproducible convulsive activity in 10 PND Sprague Dawley rats.CCX pos‐treatment has a neuroprotective effect on seizure activityCCX pos‐treatment decreases pro‐inflammatory molecules expression.CCX and PB post‐treatment has a combined effect on proinflammatory molecules.