Browsing by Author "Silva, Rita"
Now showing 1 - 10 of 15
Results Per Page
Sort Options
- Biomarkers and genetic modulators of cerebral vasculopathy in sub-Saharan ancestry children with sickle cell anemiaPublication . Silva, Marisa; Vargas, Sofia; Coelho, Andreia; Ferreira, Emanuel; Mendonça, Joana; Vieira, Luís; Maia, Raquel; Dias, Alexandra; Ferreira, Teresa; Morais, Anabela; Mota Soares, Isabel; Lavinha, João; Silva, Rita; Kjollerstrom, Paula; Faustino, PaulaWe investigated biomarkers and genetic modulators of the cerebral vasculopathy (CV) subphenotype in pediatric sickle cell anemia (SCA) patients of sub-Saharan African ancestry. We found that one VCAM1 promoter haplotype (haplotype 7) and VCAM1 single nucleotide variant rs1409419_T were associated with stroke events, stroke risk, as measured by time-averaged mean of maximum velocity in the middle cerebral artery, and with high serum levels of the hemolysis biomarker lactate dehydrogenase. Furthermore, VCAM-1 ligand coding gene ITGA4 variants rs113276800_A and rs3770138_T showed a positive association with stroke events. An additional positive relationship between a genetic variant and stroke risk was observed for ENPP1 rs1044498_A. Conversely, NOS3 variants were negatively associated with silent cerebral infarct events (VNTR 4b_allele and haplotype V) and CV globally (haplotype VII). The -alpha3.7kb–thal deletion did not show association with CV.However, it was associated with higher red blood cell and neutrophil counts, and lower mean corpuscular volume, mean corpuscular hemoglobin and red cell distribution width. Our results underline the importance of genetic modulators of the CV sub-phenotype and their potential as SCA therapeutic targets. We also propose that a biomarker panel comprising biochemical, hematological, imaging and genetic data would be instrumental for CV prediction, and prevention.
- Evening and morning alterations in Obstructive Sleep Apnea red blood cell proteomePublication . Feliciano, Amélia; Vaz, Fátima; Valentim-Coelho, Cristina; Torres, Vukosava M.; Silva, Rita; Prosinecki, Vesna; Alexandre, Bruno M.; Almeida, Andreia; Almeida-Marques, Catarina; Carvalho, Ana S.; Matthiesen, Rune; Malhotra, Atul; Pinto, Paula; Bárbara, Cristina; Penque, DeborahThis article presents proteomics data referenced in [1] Using proteomics-based evaluation of red blood cells (RBCs), we have identified differentially abundant proteins associated with Obstructive Sleep Apnea Syndrome (OSA). RBCs were collected from peripheral blood of patients with moderate/severe OSA or snoring at pre- (evening) and post-night (morning) polysomnography, so that proteome variations between these time points could be assessed. RBC cytoplasmic fraction depleted of hemoglobin, using Hemovoid(™) system, were analyzed by two-dimensional fluorescence difference gel electrophoresis (2D-DIGE), the 2D image software-based analyzed and relevant differentially abundant proteins identified by mass spectrometry (MS). MS identified 31 protein spots differentially abundant corresponding to 21 unique proteins possibly due to the existence of post-translational modification regulations. Functional analysis by bioinformatics tools indicated that most proteins are associated with catalytic, oxidoreductase, peroxidase, hydrolase, ATPase and anti-oxidant activity. At morning a larger numbers of differential proteins including response to chemical stimulus, oxidation reduction, regulation of catalytic activity and response to stress were observed in OSA. The data might support further research in OSA biomarker discovery and validation.
- Evening and morning peroxiredoxin-2 redox/oligomeric state changes in obstructive sleep apnea red blood cells: Correlation with polysomnographic and metabolic parametersPublication . Feliciano, Amélia; Vaz, Fátima; Torres, Vukosava M.; Valentim-Coelho, Cristina; Silva, Rita; Prosinecki, Vesna; Alexandre, Bruno M.; Carvalho, Ana S.; Matthiesen, Rune; Malhotra, Atul; Pinto, Paula; Bárbara, Cristina; Penque, DeborahWe have examined the effects of Obstructive Sleep Apnea (OSA) on red blood cell (RBC) proteome variation at evening/morning day time to uncover new insights into OSA-induced RBC dysfunction that may lead to OSA manifestations. Dysregulated proteins mainly fall in the group of catalytic enzymes, stress response and redox regulators such as peroxiredoxin 2 (PRDX2). Validation assays confirmed that at morning the monomeric/dimeric forms of PRDX2 were more overoxidized in OSA RBC compared to evening samples. Six month of positive airway pressure (PAP) treatment decreased this overoxidation and generated multimeric overoxidized forms associated with chaperone/transduction signaling activity of PRDX2. Morning levels of overoxidized PRDX2 correlated with polysomnographic (PSG)-arousal index and metabolic parameters whereas the evening level of disulfide-linked dimer (associated with peroxidase activity of PRDX2) correlated with PSG parameters. After treatment, morning overoxidized multimer of PRDX2 negatively correlated with fasting glucose and dopamine levels. Overall, these data point toward severe oxidative stress and altered antioxidant homeostasis in OSA RBC occurring mainly at morning time but with consequences till evening. The beneficial effect of PAP involves modulation of the redox/oligomeric state of PRDX2, whose mechanism and associated chaperone/transduction signaling functions deserves further investigation. RBC PRDX2 is a promising candidate biomarker for OSA severity and treatment monitoring, warranting further investigation and validation.
- Genetic Modulation of Cerebral Vasculopathy in Children with Sickle Cell AnemiaPublication . Silva, Marisa; Vargas, Sofia; Coelho, Andreia; Mendonça, Joana; Vieira, Luís; Kjollerstrom, Paula; Maia, Raquel; Silva, Rita; Dias, Alexandra; Ferreira, Teresa; Morais, Anabela; Mota Soares, Isabel; Lavinha, João; Faustino, PaulaSickle cell anemia (SCA) arises from homozygosity for the mutation c.20A>T in the HBB gene which originates hemoglobin S (HbS). In hypoxic conditions, HbS polymerizes inside erythrocytes deforming them and ultimately leading to hemolysis and vaso-occlusion. SCA shows a multifactorial-like behaviour with a high heterogeneity of clinical features, with stroke being the most severe of them. This heterogeneity may arise from underlying genetic modifiers, namely those affecting vascular hemostasis. These include genes like the ones encoding VCAM-1 and its ligand integrin α4 (expressed in activated human endothelium and leucocytes/stress reticulocytes, respectively), but also eNOS (expressed in human endothelium and regulating vascular tone). The aim of this study was to identify putative genetic modulators of stroke risk by analyzing 70 pediatric SCA patients, grouped according to their degree of cerebral vasculopathy. Molecular analysis was performed using Next-Generation Sequencing (NGS) and Sanger Sequencing. R software was used for statistical analyses and association studies. In silico studies were performed using PHASE, TFbind, PROMO and Human Splicing Finder software tools. We identified six different VCAM1 promoter variants and seven haplotypes. The VCAM1 promoter rs1409419_T allele was associated with stroke events, while one VCAM1 promoter haplotype was found to be protective of stroke. In the ITGA4 gene, forty variants were found, six of them novel. All patients presented with at least one variant in this gene. We observed co-inheritance of specific sets of ITGA4 variants indicating the presence of haplotypes not previously described. Three NOS3 variants were analysed and seven haplotypes were identified. The NOS3 promoter rs2070744_C allele was associated with stroke events, while the intron 4 VNTR 27bp_4a allele was found to be in association with risk of stroke. Our results reinforce the role of endothelial molecules and blood cell interaction in SCA severity. The association between specific variants in VCAM1 and ITGA4, as well as in NOS3, with certain cerebral vasculopathy predictors further enhances their putative modulating effect on pediatric stroke severity and prognosis. These findings provide additional clues on the SCA pathophysiology and uncover features of both genes that may prove to be crucial as potential therapeutic targets.
- Genetic modulation of stroke in children with sickle cell anaemiaPublication . Silva, Marisa; Vargas, Sofia; Coelho, Andreia; Mendonça, Joana; Vieira, Luís; Kjollerstrom, Paula; Maia, Raquel; Silva, Rita; Dias, Alexandra; Ferreira, Teresa; Morais, Anabela; Mota Soares, Isabel; Lavinha, João; Faustino, PaulaSickle cell anaemia (SCA) is an autosomal recessive genetic disease that leads to the synthesis of haemoglobin S (HbS). The pathophysiology of the disease is centred on HbS polymerization inside the red blood cells, which become sickle-shaped (SSRBCs), rigid, viscous and adherent-prone to the vascular endothelium, favouring the occurrence of chronic haemolysis and vaso-occlusion. The main vascular problems of SCA arise from several pathways including endothelial dysfunction and nitric oxide (NO) metabolism. Children with SCA have a much higher risk (11% by age 20 years) of developing stroke or silent cerebral infarcts (up to 37%) than the general paediatric population. Abnormal interactions between SSRBCs and the cerebral arterial endothelium lead to endothelial injury, vaso-occlusion and tissue ischemia and result in cerebral vasculopathy (CVA) through a yet unknown pathophysiological mechanism. Current risk screening strategies rely mainly on imaging techniques (transcranial Doppler ultrasonography and magnetic resonance imaging) and children with altered results undergo regular blood transfusion and/or hydroxyurea therapy to reduce stroke risk/recurrence. However, we need more specific/sensitive biomarkers for stroke prediction/prognosis. Genetic modulators may be paramount in SCA pathophysiology and in CVA severity. They include variants in VCAM1 (endothelial dysfunction), ITGA4 (cell-cell adhesion), and NOS3 (nitric oxide metabolism. The main goals of this work are: a) improve the knowledge on the genetic architecture of paediatric cerebral vasculopathy in SCA; b) assessing the consequences of those genetic variants on gene expression/protein function; c) identify genotypic/phenotypic markers of SCA sub-phenotypes; and d) analyse their potential as genetic modulators of disease severity. This would be crucial in assessing potential pharmacological targets specifically aimed to the vascular system and instrumental for the design of novel preventive, prophylactic or therapeutic strategies.
- Genetic modulators of fetal hemoglobin expression and ischemic stroke occurrence in African descendant children with sickle cell anemiaPublication . Nicolau, Marta; Vargas, Sofia; Silva, Marisa; Coelho, Andreia; Ferreira, Emanuel; Mendonça, Joana; Vieira, Luís; Kjollerstrom, Paula; Maia, Raquel; Silva, Rita; Dias, Alexandra; Ferreira, Teresa; Morais, Anabela; Mota Soares, Isabel; Lavinha, João; Faustino, PaulaSickle cell anemia (SCA) is an autosomal recessive monogenic disease with significant clinical variability. Cerebrovascular disease, particularly ischemic stroke, is one of the most severe complications of SCA in children. This study aimed to investigate the influence of genetic variants on the levels of fetal hemoglobin (Hb F) and biochemical parameters related with chronic hemolysis, as well as on ischemic stroke risk, in ninety-one unrelated SCA patients, children of sub-Saharan progenitors. Our results show that a higher Hb F level has an inverse relationship with the occurrence of stroke, since the group of patients who suffered stroke presents a significantly lower mean Hb F level (5.34 ± 4.57% versus 9.36 ± 6.48%; p = 0.024). Furthermore, the co-inheritance of alpha-thalassemia improves the chronic hemolytic pattern, evidenced by a decreased reticulocyte count (8.61 ± 3.58% versus 12.85 ± 4.71%; p < 0.001). In addition, our findings have confirmed the importance of HBG2 and BCL11A loci in the regulation of Hb F expression in sub-Saharan African SCA patients, as rs7482144_A, rs11886868_C, and rs4671393_A alleles are significantly associated with a considerable increase in Hb F levels (p = 0.019, p = 0.026, and p = 0.028, respectively). Concerning KLF1, twelve different variants were identified, two of them novel. Seventy-three patients (80.2%) presented at least one variant in this gene. However, no correlation was observed between the presence of these variants and Hb F level, severity of hemolysis, or stroke occurrence, which is consistent with their in silico-predicted minor functional consequences. Thus, we conclude that the prevalence of functional KLF1 variants in a sub-Saharan African background does not seem to be relevant to SCA clinical modulation.
- Moduladores genéticos de vasculopatia cerebral em crianças com drepanocitosePublication . Silva, Marisa; Vargas, Sofia; Maia, Raquel; Dias, Alexandra; Ferreira, Teresa; Morais, Anabela; Soares, Isabel Mota; Lavinha, João; Silva, Rita; Kjöllerström, Paula; Faustino, PaulaA drepanocitose é uma doença genética causada pela mutação c.20A>T, em homozigotia, no gene da beta-globina, que leva à síntese de uma hemoglobina anómala – hemoglobina S. Para além da anemia hemolítica crónica, as manifestações clínicas são diversas e, em crianças, a mais grave é a vasculopatia cerebral que inclui os acidentes vasculares cerebrais (AVC) e os enfartes cerebrais silenciosos. Apesar de monogénica, variantes noutros genes poderão atuar como modificadores do seu curso e gravidade clínica. Neste trabalho, estudámos 70 doentes pediátricos, de origem subsaariana, com drepanocitose e bem caracterizados em termos de vasculopatia cerebral. Procedemos à genotipagem de variantes nos genes VCAM1 e NOS3 envolvidos na ativação do endotélio dos vasos sanguíneos e no tónus vascular. A análise estatística revelou uma associação positiva entre a presença da variante rs1409419_T, bem como do haplotipo 7 de VCAM1, e a ocorrência de AVC. Por outro lado, para o gene NOS3, observámos uma associação negativa entre o VNTR_alelo 4b e o haplotipo V, e a ocorrência de enfarte cerebral silencioso, bem como entre o haplotipo VII e a ocorrência de vasculopatia cerebral. Os resultados obtidos sublinham a importância de VCAM1 e NOS3 como moduladores genéticos, bem como o seu potencial como biomarcadores para a prevenção e prognóstico da vasculopatia cerebral em crianças com drepanocitose.
- Ocorrência de Níquel em alimentos consumidos em Portugal: Resultados preliminares do projeto TDS (piloto)Publication . Ventura, Marta; Gueifão, Sandra; Silva, Rita; Delgado, Inês; Coelho, Inês; Castanheira, IsabelO níquel é um elemento natural da superfície terrestre. A alimentação é uma das principais fontes de exposição deste metal na população não fumadora. Devido à sua acumulação no organismo pode causar efeitos nocivos para a saúde como a carcinogénese e a dermatite endógena. O principal objetivo deste trabalho foi a determinação de níquel em alimentos analisados como consumidos e representativos da dieta portuguesa. A metodologia escolhida para a quantificação deste contaminante foi a espectrometria de massa acoplada a plasma indutivo (ICP-MS) precedida por digestão ácida em vaso fechado no micro-ondas. Foram recolhidas 1560 amostras, que foram analisadas em 130 pools, contendo cada 12 alimentos idênticos. O teor de níquel variou entre 21,2 µg/kg (sumos) e 1050 µg/kg (bivalves). O limite de quantificação do método foi o parâmetro analítico considerado indicador para a avaliação da exposição. A análise comparativa entre os valores analíticos superiores ao limite de quantificação do método e os valores não quantificáveis, demonstrou que todos os compósitos apresentaram valores acima do limite de quantificação e 60% dos resultados encontrados nos lacticínios estavam abaixo do limite de quantificação. Atendendo aos procedimentos aplicados os resultados obtidos podem ser utilizados como fonte de informação científica para simulações da avaliação de risco de exposição ao níquel, com consequentes ganhos em saúde.
- Ocorrência de níquel em alimentos consumidos em Portugal: resultados preliminares do projeto-piloto Total Diet StudyPublication . Ventura, Marta; Gueifão, Sandra; Silva, Rita; Delgado, Inês; Coelho, Inês; Castanheira, IsabelO níquel é um elemento natural da superfície terrestre. A alimentação é uma das principais fontes de exposição a este metal. Devido à sua acumulação no organismo pode causar efeitos nocivos para a saúde como a carcinogénese e a dermatite induzida. O principal objetivo deste trabalho foi a determinação de níquel em alimentos analisados como consumidos e representativos da dieta portuguesa. A metodologia escolhida para a quantificação deste contaminante foi a espectrometria de massa acoplada a plasma indutivo (ICP-MS) precedida por digestão ácida em vaso fechado no micro-ondas. Foram recolhidas 1560 amostras, que foram analisadas em 130 pools, contendo cada 12 alimentos idênticos. O teor de níquel variou entre 21,2 μg/kg (sumos) e 1050 μg/kg (bivalves). O limite de quantificação do método foi o parâmetro analítico considerado indicador para a avaliação da exposição. A análise comparativa entre os valores analíticos superiores ao limite de quantificação do método e os valores não quantificáveis, demonstrou que todos os pratos compostos apresentaram valores superiores ao limite de quantificação e 60% dos resultados encontrados nos laticínios eram inferiores ao limite de quantificação do método. Atendendo aos procedimentos aplicados, os resultados obtidos podem ser utilizados como fonte de informação científica para simulações da avaliação do risco de exposição ao níquel, com consequentes ganhos em saúde.
- Paediatric cerebral vasculopathy in sickle cell anaemia: contribution of genetic modifiersPublication . Silva, Marisa; Vargas, Sofia; Coelho, Andreia; Mendonça, Joana; Vieira, Luís; Kjollerstrom, Paula; Maia, Raquel; Silva, Rita; Dias, Alexandra; Ferreira, Teresa; Morais, Anabela; Mota Soares, Isabel; Lavinha, João; Faustino, PaulaSickle cell anaemia (SCA) arises from homozygosity for the mutation c.20A>T in the HBB gene. However, it shows a multifactorial-like behaviour with high heterogeneity of clinical features. Cerebral vasculopathy (CVA), namely paediatric ischemic stroke, is one of its most devastating consequences. The risk of CVA development, specifically stroke or silent cerebral infarction, may be modulated by underlying genetic modifiers, for example those affecting vascular homeostasis. In this study, we aimed to investigate the impact of variants in genes related with endothelial adhesion (VCAM1 and ITGA4) and nitric oxide metabolism (NOS3) on CVA in a group of 70 SCA children well characterized according to their CVA degree. In addition, the effect of the same genetic variants on biochemical/haematological biomarkers of chronic haemolysis was also analysed. Moreover, we also evaluated the putative additional modulating role of variants previously identified as stroke risk factors by genome-wide associated studies: GOLGB1 Y1212C, ENPP1 K173Q and PON1 Q192R. Molecular analysis was performed using PCR, PCR-RFLP, next-generation sequencing and Sanger sequencing. SPSS software was used for statistical analyses and association studies. One of the seven VCAM1 promoter haplotypes found and the VCAM1 promoter rs1409419_T showed association with moderate to high time-averaged mean of maximum velocity in the middle cerebral artery. The same association was observed for the variant ENPP1 K173Q. On the other hand, we observed that ITGA4 variants rs113276800_A and rs3770138_T were associated with stroke events. As for NOS3, one of the six haplotypes and the intron 4 VNTR_4b allele (5 repeats) were associated with lower risk of silent cerebral infarction. Chronic haemolysis biomarker levels also seemed to be influenced by genetic variants. LDH levels was higher in the presence of VCAM1 promoter rs1409419_T and one VCAM1 haplotype but lower in patients with one of the two ITGA4 haplotypes found. Genetic modulation also occurred in total bilirubin levels, which were higher in association with VCAM1 rs3783613_C allele. Our results, namely the association between specific variants with certain cerebral vasculopathy predictors further enhances their putative modulating effect on SCA paediatric stroke risk, severity and prognosis. These findings provide additional clues on the SCA pathophysiology and uncover features in these genes that may prove to be crucial as potential therapeutic targets.