Browsing by Author "Ramalheira, João"
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- Apolipoprotein E isoforms and susceptibility to genetic generalized epilepsiesPublication . Chaves, João; Martins-Ferreira, Ricardo; Carvalho, Cláudia; Bettencourt, Andreia; Brás, Sandra; Chorão, Rui; Freitas, Joel; Samões, Raquel; Lopes, João; Ramalheira, João; Silva, Berta; Costa, Paulo; Martins Da Silva, António; Leal, BárbaraBackground: Apolipoprotein E (ApoE) is the main lipoprotein secreted in brain. It has a critical immunomodulatory function, influences neurotransmission and it is involved in repairing damaged neurons. ApoE e4 is an isoform of ApoE with altered function, and was previously associated with early onset epilepsy and refractoriness, both in animal models and in patients with focal epilepsies. There is a limited knowledge on ApoE’s role in Genetic Generalized Epilepsies (GGE). Aim: To determine if ApoE isoforms are risk factors for GGE development. Methods: A group of 337 GGE patients (193 F, 144 M, 33.6 ± 14.2 years) was compared with a group of 342 healthy individuals in a case-control genetic association study. ApoE genotyping was performed using PCR-RFLP. Results: The genotypic frequency of ApoE e3/e2 was lower in GGE patients relative to controls (6.5% in GGE vs. 11.7% in controls, p = 0.019, OR (95% CI) = 0.53 (0.305–0.905). No associations with other clinical data such as photosensitivity or age at disease onset were observed. Conclusion: Our results show that ApoE e3/e2 genotype may be a protective factor for GGE development. There is evidence that this genotype could be neuroprotective, preventing oxidative damage and promoting neuronal survival. Although replication studies are warranted, our data suggest that ApoE isoforms have a role in epileptogenic mechanisms regardless of the specific epileptic manifestations.
- Brain expression of inflammatory mediators in Mesial Temporal Lobe Epilepsy patientsPublication . Leal, Bárbara; Chaves, João; Carvalho, Cláudia; Rangel, Rui; Santos, Agostinho; Bettencourt, Andreia; Lopes, João; Ramalheira, João; Silva, Berta M.; da Silva, António Martins; Costa, Paulo P.Neuroinflammation may be central in epileptogenesis. In this study we analysed inflammatory reaction markers in brain tissue of Mesial Temporal Lobe Epilepsy with Hippocampal Sclerosis (MTLE-HS) patients. TLR4, IL-1β and IL-10 gene expression as well as the presence of activated HLA-DR+ microglia was evaluated in 23 patients and 10 cadaveric controls. Inflammation characterized by the presence of HLA-DR+microglia and TLR4, IL-1β overexpression was evident in hippocampus and anterior temporal cortex of MTLE-HS patients. Anti-inflammatory IL-10 was also overexpressed in MTLE-HS patients. Our results show that hippocampal neuroinflammation extends beyond lesional limits, as far as the anterior temporal cortex.
- Circulating miR-134 in mesial temporal lobe epilepsy: implications in hippocampal sclerosis development and drug resistancePublication . Guerra Leal, Bárbara; Carvalho, Cláudia; Santos, Cristina; Samões, Raquel; Martins-Ferreira, Ricardo; Teixeira, Catarina; Rodrigues, Diana; Freitas, Joel; Lemos, Carolina; Chorão, Rui; Ramalheira, João; Lopes, João; Martins da Silva, António; Pinho E Costa, Paulo; Chaves, JoãoAim: miR-134 has been widely reported as upregulated in experimental and human studies of Mesial Temporal Lobe Epilepsy the most common drug-resistant epilepsy (DRE). Studies have shown that the use of antagomirs, anti-miR-134, may be a promising therapeutic approach to these epilepsies. However, data on miR-134 in other epileptic syndromes is scarce. In this study, we aimed to quantify serum levels of miR-134 in a cohort of patients with Mesial Temporal Lobe Epilepsy-Hippocampal Sclerosis (MTLE-HS) and with Genetic Generalized Epilepsies (GGE). Additionally, we explored the correlation between miR-134 serum levels and clinical parameters, such as age at onset or febrile seizures antecedents, to evaluate its potential as a biomarker and therapeutic target in epilepsy. Methods: miR-134 levels were evaluated in cell-free serum of 131 patients with epilepsy (75 women, 56 men; age 41.10 ± 13.12 years; 72 with DRE) and 42 healthy individuals (25 women, 17 men; age 42.40 ± 9.80 years). The epilepsy cohort included 77 MTLE-HS patients and 54 GGE patients. Results: Patients with elevated miR-134 circulating levels were at higher risk of drug-resistant epilepsy (OR [95% CI] = 2.246 [1.111–4.539], p = 0.021). Other risk factors included an older age (OR [95% CI] = 1.032 [1.004–1.061], p = 0.025), history of febrile seizures (OR [95% CI] = 2.994 [1.385–6.471], p = 0.005) and higher disease duration (OR [95% CI] = 1.038 [1.011–1.066], p = 0.006). The strongest predictor of DRE was hippocampal sclerosis (OR [95% CI] = 10.338 [4.566–23.404], p < 0.001). Circulating miR-134 levels were significantly higher in MTLE-HS patients compared to controls (p < 0.05) and GGE patients (p < 0.05). However, the clinical utility of miR-134 in discriminating MTLE-HS patients from controls was only moderated (AUC = 0.651 ± 0.051 95% CI 0.551–0.751, p = 0.007). Conclusion: We show that miR-134 circulating levels are associated with DRE, especially in MTLE-HS, a syndrome characterized by severe hippocampal damage, consistent with activity-regulated miR-134 expression. This overexpression likely contributes to disease progression and our results support the potential of targeting miR-134 as a novel therapeutic approach for refractory epilepsy.
- Expression of Inflammation-Associated MicroRNAs in EpilepsyPublication . Leal, Bárbara; Carvalho, Cláudia; Chaves, João; Bettencourt, Andreia; Freitas, Joel; Lopes, João; Ramalheira, João; Silva, António M.; Costa, Paulo P.; Silva, Berta M.Background: Neuroinflammation appears as an important epileptogenic mechanism. MicroRNAs (miRNA) are small non-coding RNA molecules that function as post-transcriptional regulators of gene expression, controlling different biological process including immune system homeostasis and function. Evidences, both in patients and animal studies, have demonstrated an abnormal brain expression of miR-146a and miR-155 in Mesial Temporal Lobe Epilepsy (MTLE), the most refractory epilepsy type. Knowing that miR expression is very stable in biological fluids such as plasma or serum our aim was to characterize miR-146a and miR-155 expression in serum of MTLE and GGE patients. Methods: Expression levels of miR146a and RNU48 (reference gene) were quantified by Real-Time PCR in serum of 16 MTLE patients all with Hippocampal Sclerosis (6F, 8M, mean age= 44.1±11.7 years, age of onset= 13.5±10.6 years, 7 with Febrile Seizures antecedents). A group of 24 healthy individuals was used as control. Relative expression values were calculated using the 2-ΔΔCt method. Results: MTLE patients had a higher expression of miR-146a (6 fold) and miR-155 (2 fold) when compared to controls. Conclusion: Our results, although preliminary, show that miR-146a and miR-155 may be suitable biomarkers for epileptogenesis. It is thought that these miRNAs have role in fine-tuning the response to pro-inflammatory cytokines during epileptogenesis. Nevertheless its importance in epilepsy development it is yet not fully understood. The comprehension of this role may be relevant for the development of new therapeutic strategies.
- Immunogenetic predisposing factors for mesial temporal lobe epilepsy with hippocampal sclerosisPublication . Leal, Bárbara; Chaves, João; Carvalho, Cláudia; Bettencourt, Andreia; Brito, Cláudia; Boleixa, Daniela; Freitas, Joel; Brás, Sandra; Lopes, João; Ramalheira, João; Costa, Paulo; Silva, Berta; Martins Da Silva, AntónioPurpose: Neuroinflammation appears as an important epileptogenic mechanism. Experimental and clinical studies have demonstrated an upregulation of pro-inflammatory cytokines such as IL-1β and TNF-α, in mesial temporal lobe epilepsy with hippocampal sclerosis (MTLE-HS). Expression of these cytokines can be modulated by polymorphisms such as rs16944 and rs1800629, respectively, both of which have been associated with febrile seizures (FS) and MTLE-HS development. The human leukocyte antigen (HLA) system has also been implicated in diverse epileptic entities, suggesting a variable role of this system in epilepsy. Our aim was to analyse the association between immunogenetic factors and MTLE-HS development. For that rs16944 (-511 T>C, IL-1β), rs1800629 (-308 G>A, TNF-α) polymorphisms and HLA-DRB1 locus were genotyped in a Portuguese Population. Methods: We studied 196 MTLE-HS patients (108 females, 88 males, 44.7 ± 12.0 years, age of onset = 13.6 ± 10.3 years, 104 with FS antecedents) and 282 healthy controls in a case–control study. Results: The frequency of rs16944 TT genotype was higher in MTLE-HS patients compared to controls (14.9% in MTLE-HS vs. 7.7% in controls, p = 0.021, OR [95% CI] = 2.20 [1.13–4.30]). This association was independent of FS antecedents. No association was observed between rs1800629 genotypes or HLA-DRB1 alleles and MTLE-HS susceptibility. Also, no correlation was observed between the studied polymorphisms and disease age of onset. Conclusion: The rs16944 TT genotype is associated with MTLE-HS development what may be explained by the higher IL-1β levels produced by this genotype. High IL-1β levels may have neurotoxic effects or imbalance neurotransmission leading to seizures.
- Immunogenetic protective factors in Genetic Generalized EpilepsyPublication . Chaves, João; Martins-Ferreira, Ricardo; Ferreira, Ana Marta; Brás, Sandra; Carvalho, Cláudia; Bettencourt, Andreia; Samões, Raquel; Monteiro, Fábio; Freitas, Joel; Chorão, Rui; Lopes, João; Ramalheira, João; Silva, Berta; Costa, Paulo; Martins Da Silva, António; Leal, BárbaraBackground: Genetic Generalized Epilepsies (GGEs) are a heterogeneous group of syndromes characterized by generalized seizure activity that affects both hemispheres, with mainly genetic causes. Neuroinflammation has been established as an important mechanism in epileptogenesis. The ability to develop an appropriated immune response is strongly determined by immunogenetic factors. In this setting, our aim was to evaluate potential associations between GGEs and immunogenetic factors. Methods: The rs16944 (IL-1β -511 T > C) polymorphism and the HLA-DRB1 locus were genotyped in a Portuguese GGE population. Association with two clinicopathological features, photosensitivity and refractoriness, was investigated. This case-control study included 323 GGE patients (187 F, 136 M, 34.0 ± 13.9 years of age), 145 of which with JME diagnosis (88 F, 57 M, 34.1 ± 14.0 years), and 282 healthy controls (174 F, 108 M, 37.7 ± 11.6 years). Results: Decreased frequencies of the HLA-DRB1*09 and DRB1*13 alleles were observed in the GGE population. HLA-DRB1*07 frequency was increased in JME. Rs16944 allelic frequencies were similar between patients and controls. Conclusions: These results, not entirely consistent with previous reports, suggest that HLA molecules may have a complex role in epileptogenesis.
- Late‐onset Levodopa Responsive Parkinsonism Due to Polymerase γ 1 MutationsPublication . Calejo, Margarida; Vilarinho, Laura; Neiva, Raquel; Botelho, Luís; Ramalheira, João; Taipa, Ricardo; Melo‐Pires, Manuel; Lima, António Bastos; Damásio, JoanaIntroduction: Polymerase γI (POLG) gene mutations may induce mitochondrial DNA (mtDNA) instability leading to its depletion or multiple deletions1 and causing a wide spectrum of multisystemic disorders. Commonly described phenotypes include AlpersHuttenlocher syndrome, childhood myocerebrohepatopathy, myoclonic epilepsy myopathy and sensory ataxia, mitochondrial recessive ataxia syndrome, sensory ataxia neuropathy with dysarthria, and ophthalmoplegia and progressive external ophthalmoplegia (PEO).1 Levodopa-responsive parkinsonism has been described as a late feature in patients with PEO.
- Mesial Temporal Lobe Epilepsy (MTLE) Drug-Refractoriness Is Associated With P2X7 Receptors Overexpression in the Human Hippocampus and Temporal Neocortex and May Be Predicted by Low Circulating Levels of miR-22Publication . Guerra Leal, Bárbara; Barros-Barbosa, Aurora; Ferreirinha, Fátima; Chaves, João; Rangel, Rui; Santos, Agostinho; Carvalho, Cláudia; Martins-Ferreira, Ricardo; Samões, Raquel; Freitas, Joel; Lopes, João; Ramalheira, João; Lobo, Maria Graça; Martins da Silva, António; Costa, Paulo P.; Correia-de-Sá, PauloObjective: ATP-gated ionotropic P2X7 receptors (P2X7R) actively participate in epilepsy and other neurological disorders. Neocortical nerve terminals of patients with Mesial Temporal Lobe Epilepsy with Hippocampal Sclerosis (MTLE-HS) express higher P2X7R amounts. Overexpression of P2X7R bolsters ATP signals during seizures resulting in glial cell activation, cytokines production, and GABAergic rundown with unrestrained glutamatergic excitation. In a mouse model of status epilepticus, increased expression of P2X7R has been associated with the down-modulation of the non-coding micro RNA, miR-22. MiR levels are stable in biological fluids and normally reflect remote tissue production making them ideal disease biomarkers. Here, we compared P2X7R and miR-22 expression in epileptic brains and in the serum of patients with MTLE-HS, respectively. Methods: Quantitative RT-PCR was used to evaluate the expression of P2X7R in the hippocampus and anterior temporal lobe of 23 patients with MTLE-HS and 10 cadaveric controls. Confocal microscopy and Western blot analysis were performed to assess P2X7R protein amounts. MiR-22 expression was evaluated in cell-free sera of 40 MTLE-HS patients and 48 healthy controls. Results: Nerve terminals of the hippocampus and neocortical temporal lobe of MTLE-HS patients overexpress (p < 0.05) an 85 kDa P2X7R protein whereas the normally occurring 67 kDa receptor protein dominates in the brain of the cadaveric controls. Contrariwise, miR-22 serum levels are diminished (p < 0.001) in MTLE-HS patients compared to age-matched control blood donors, a situation that is more evident in patients requiring multiple (>3) anti-epileptic drug (AED) regimens. Conclusion: Data show that there is an inverse relationship between miR-22 serum levels and P2X7R expression in the hippocampus and neocortex of MTLE-HS patients, which implies that measuring serum miR-22 may be a clinical surrogate of P2X7R brain expression in the MTLE-HS. Moreover, the high area under the ROC curve (0.777; 95% CI 0.629-0.925; p = 0.001) suggests that low miR-22 serum levels may be a sensitive predictor of poor response to AEDs among MTLE-HS patients. Results also anticipate that targeting the miR-22/P2X7R axis may be a good strategy to develop newer AEDs.
- Obstructive sleep apnoea syndrome and HLA in the North of PortugalPublication . Silva, Luís; Lopes, João; Ramalheira, João; Cunha, Daniela; Carvalho, Cláudia; Bettencourt, Andreia; Bras, Sandra; Costa, Paulo; Silva, M. Berta; Martins-da-Silva, António[ENG] Introduction. The obstructive sleep apnoea syndrome (OSAS) is a common, complex and polygenic disease with diverse aetiologies interacting to produce a single phenotype. OSAS occurs throughout the entire lifespan and familial aggregation has been suggested. Several predisposing factors, as age, gender and obesity have been described. Associations between HLA polymorphisms and sleep disorders are confirmed, in European and Non-European descendent populations. However the associations found between HLA alleles and OSAS have not been consistent and have no informative value for sleep disorder classification. Aims. To explore the genetic association of HLA with OSAS in a northern Portuguese population and to evaluate the role of obesity in the context of HLA in OSAS. Patients and methods. A cohort of 131 patients with OSAS was studied. Patients followed up in an Outpatient Sleep Clinic were assessed by clinical history, night sleep polygraphic recording, multiple sleep latency test (when necessary for differential diagnosis), laboratorial and demographic studies. A control population (CP) of 223 healthy individuals was used for comparison. HLA-DRB1 genotyping was performed using a polymerase chain reaction with sequence specific primers methodology. Results. In this cohort, the HLA-DRB1*03 allele was identified as a susceptibility factor for OSAS (24% OSAS vs. 15% CP; p = 0.025; odds ratio = 1.861; 95% CI = 1.081-3.205). No significant differences were found for other HLA-DBR1* alleles. Conclusion. HLA-DRB1*03 is a susceptibility factor for OSAS in Portuguese population. Key words. Gender. HLA-DRB1*03. Obesity. Obstructive sleep apnoea syndrome (OSAS). Risk factors. Sleep disorders.