Browsing by Author "Castro, Elisabeth"
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- Band 3 profile as a marker of erythrocyte changes in chronic kidney disease patientsPublication . Costa, Elísio; Rocha, Susana; Rocha-Pereira, Petronila; Castro, Elisabeth; Miranda, Vasco; Faria, Maria do Sameiro; Loureio, Alfredo; Quintanilha, Alexandre; Belo, Luís; Santos-Silva, AliceOur aim was to study changes in red blood cell (RBC) membrane band 3 profile, as a cumulative marker of RBC changes, in chronic kidney disease (CKD) patients under haemodialysis and recombinant human erythropoietin (rhEPO) therapy and its linkage with resistance to this therapy. We studied 63 CKD patients, 32 responders and 31 non-responders to rhEPO therapy, and 26 healthy individuals. We evaluated the band 3 profile [% of band 3 monomer, high molecular weight aggregates (HMWAg), and proteolytic fragments (Pfrag)], membrane-bound haemoglobin (MBH), haematological data, total serum bilirubin, glutathione peroxidase (GPx) and superoxide dismutase activities, total antioxidant status (TAS) and plasma lipid peroxidation (TBA). Compared to controls, band 3 profile presented by CKD patients showed statistically significant lower HMWAg and Pfrag values and a significant higher value in band 3 monomer. GPx, TBA and TAS activities, and TBA/TAS ratio were also significantly higher in CKD patients. Comparing responders to non-responders CKD patients, significantly lower value in Pfrag and a trend for a higher value in MBH were found in non-responders. Our data suggest that CKD patients present younger RBC population, which could be related to the rhEPO therapy. The adverse plasma environment associated to CKD patients under hemodialysis imposes changes in band 3 profile, particularly in non-responders, suggesting that resistance to rhEPO therapy in CKD patients seems to be associated to an increase in RBC damage.
- Changes in red blood cells membrane protein composition during hemodialysis procedurePublication . Costa, Elísio; Rocha, Susana; Rocha-Pereira, Petronila; Castro, Elisabeth; Miranda, Vasco; Faria, Maria do Sameiro; Loureio, Alfredo; Quintanilha, Alexandre; Belo, Luís; Santos-Silva, AliceOur aim was to evaluate the influence of the hemodialysis (HD) procedure in red blood cells (RBC) membrane protein composition. We evaluated hematological data (RBC count, hemoglobin concentration, and hematimetric indices) and RBC membrane protein composition (linear and exponential gradient polyacrylamide gel electrophoresis in the presence of sodium dodecylsulfate [SDS-PAGE] followed by densitometry analysis of RBC membrane proteins) before and immediately after the HD procedure in 20 patients (10 responders and 10 non-responders to recombinant human erythropoietin therapy [rhEPO]) and 26 healthy controls. Before HD, patients presented anaemia and significant changes in membrane protein composition, namely, a statistically significant reduction in spectrin associated with a significant increase in bands 6, as well as an altered membrane protein interaction (protein 4.1/spectrin, protein 4.1/band 3, protein 4.2/band 3 and spectrin/band 3). After HD, we found that patients showed a statistically significant increase in RBC count and hemoglobin, a further and statistically significant decrease in spectrin, an increase in band 3, and an altered spectrin/band 3 ratio. When comparing responders and non-responders patients after HD, we found that the non-responders presented a trend to a higher reduction in spectrin. Our data suggest that HD procedure seems to contribute to a reduction in spectrin, which is normally associated with a reduction in RBC deformability, being that reduction in spectrin is higher in non-responder patients.
- DMT1 (NRAMP2/DCT1) genetic variability and resistance to recombinant human erythropoietin therapy in chronic kidney disease patients under haemodialysisPublication . Costa, Elísio; Rocha, Susana; Rocha-Pereira, Petronila; Reis, Flávio; Castro, Elisabeth; Teixeira, Frederico; Miranda, Vasco; Faria, Maria do Sameiro; Loureio, Alfredo; Quintanilha, Alexandre; Belo, Luís; Santos-Silva, Alice
- Neutrophil activation and resistance to recombinant human erythropoietin therapy in Hemodialysis PatientsPublication . Costa, Elísio; Rocha, Susana; Rocha-Pereira, Petronila; Nascimento, Henrique; Castro, Elisabeth; Miranda, Vasco; Faria, Maria do Sameiro; Loureiro, Alfredo; Belo, Luís; Santos-Silva, AliceThe aim of this work was to evaluate the neutrophil activation state in chronic kidney disease (CKD) patients under hemodialysis, and its linkage with resistance to recombinant human erythropoietin (rhEPO) therapy. Methods: We studied 63 CKD patients under hemodialysis and rhEPO treatment (32 responders and 31 non-responders to rhEPO therapy). In 20 of the CKD patients (10 responders and 10 non-responders to rhEPO therapy), blood samples were also collected immediately after dialysis. Twenty-six healthy volunteers were included in a control group. Hemoglobin levels, total and differential leukocyte counts, and circulating levels of C-reactive protein (CRP), elastase and lactoferrin were measured in all patients and controls. Results: Compared with controls, CKD patients presented with significantly higher CRP, neutrophil and elastase levels. When we compared the 2 groups of patients, we found that non-responders presented statistically significantly higher elastase plasma levels. A positive significant correlation was found between elastase levels and weekly rhEPO dose and CRP serum levels. After the hemodialysis procedure, a statistically significant rise in elastase, lactoferrin and, elastase/neutrophil and lactoferrin/neutrophil ratios were found. Conclusions: Our data show that CKD patients under hemodialysis present higher elastase levels (particularly in non-responding patients), which could be related to the rise in neutrophils, and to be part of the enhanced inflammatory process found in these patients
- Resistance to recombinant human erythropoietin therapy in haemodialysis patientsPublication . Costa, Elísio; Lima, Margarida; Rocha, Susana; Pereira, Petronila Rocha; Reis, Flávio; Castro, Elisabeth; Teixeira, Frederico; Miranda, Vasco; Faria, Maria do Sarmento; Loureiro, Alfredo; Quintanilha, Alexandre; Belo, Luís; Santos-Silva, AliceTo better clarify the mechanism of resistance to recombinan thuman erythropoietin (rhEPO) therapy in haemodialysis patients, we studied systemic changes associated with resistance to rhEPO therapy in haemodialysis patients under rhEPO therapies, with particular interest on inflammation, leukocyte activation, iron status, oxidative stress and erythrocyte damage. We studied 63 chronic kidney disease (CKD) patients under haemodialysis and rhEPO therapies (32 responders and 31 non-responders to rhEPO therapy) and 26 healthy volunteers. In 20 of the CKD patients (10 responders and 10 non-responders to rhEPO therapy), blood samples were also collected immediately after dialysis to study the effect of the haemodialysis procedure. When compared to controls, haemodialysis patients presented lymphopenia, which results, at least in part, from a decrease in total circulating CD3+ T-lymphocytes and affect both the CD4+ and the CD8+ T-cell subsets. These lymphocytes presented markers of enhanced continuous activation state and enhanced ability to produce Th1 related cytokines. Furthermore, haemodialysis patients presented raised markers of an inflammatory process, and of an enhanced neutrophil activation, as showed by the high serum levels of elastase. Concerning to iron status, patients showed increased ferritin and prohepcidin serum levels, and a decrease in transferrin. Furthermore, some changes were observed in erythrocyte membrane protein composition and in band 3 profile, being the decrease in spectrin the most significant change. Higher plasma levels of total antioxidant status (TAS), lipidic peroxidation (TBA) and TBA/TAS ratio were also found. When comparing the two groups of patients, we found that non-responders presented a significant decrease in total lymphocyte and CD4+ T-cell counts, a more accentuated inflammatory process and indicators of enhanced neutrophil activation. No significant differences were found in serum iron status markers between the two groups of patients, except for the soluble transferrin receptor, which was higher among nonresponders. Prohepcidin serum levels were significantly lower in non-responders, but were higher than those in the control group. An accentuated decrease in erythrocyte membrane spectrin, alterations in band 3 profile [decrease in band 3 proteolytic fragments (Pfrag) and in Pfrag/band 3 monomer ratio], and a trend to higher values of membrane bound haemoglobin were also found in non-responders patients. In conclusion, although the etiology of resistance to rhEPO therapy is still unknown, our work confirms that inflammationseems to have an important role in its pathophysiology. We also showed that resistance to rhEPO therapy is associated with “functional” iron deficiency, lymphopenia and CD4+ lymphopenia, higher elastase plasma levels, increased interleukin-7 serum levels, and alterations in erythrocyte membrane protein structure and in band 3 profile. Further studies are needed to understand the rise in inflammation with the associated need in higher doses of rhEPO and the reduced iron availability.
- Resistência à terapêutica com eritropoietina humana recombinante em doentes hemodializadosPublication . Costa, Elísio; Lima, Margarida; Rocha, Susana; Rocha-Pereira, Petronila; Reis, Flávio; Castro, Elisabeth; Teixeira, Frederico; Miranda, Vasco; Faria, Maria do Sameiro; Loureiro, Alfredo; Quintanilha, Alexandre; Belo, Luís; Santos-Silva, AliceCom o objectivo de clarificar o mecanismo de resistência à terapêutica com eritropoietina humana recombinante (EPOhr) em doentes hemodializados, estudamos alterações a ela associada, com particular interesse na inflamação, activação leucocitária, ciclo do ferro, stress oxidativo e lesão eritrocitária. Foram estudados 63 doentes renais crónicos (DRC) em hemodiálise e terapêutica com EPOhr (32 respondedores e 31 não respondedores à terapêutica com EPOhr) e 26 indivíduos controlo. Em 20 dos DRC (10 respondedores e 10 não respondedores à terapêutica com EPOhr), foram também colhidas amostras de sangue imediatamente após a hemodiálise para estudar os efeitos deste procedimento. Quando comparados com os controlos, os DRC em hemodiálise apresentaram linfocitopenia, resultante de uma diminuição da contagem dos linfócitos CD3+ e em que ambos os subtipos de linfócitos T CD4+ e CD8+ se encontravam diminuídos. Estes linfócitos apresentavam marcadores celulares de estimulação continuada aumentados e capacidade aumentada de produzir citoquinas associadas com a resposta imune do tipo Th1. Adicionalmente, estes doentes apresentavam marcadores inflamatórios, e aumento na activação dos neutrófilos. No que se refere ao estudo do ciclo do ferro, os DRC apresentavam aumento dos níveis séricos de ferritina e prohepcidina, e uma diminuição na transferrina. Adicionalmente, foram também encontradas alterações na composição proteica da membrana dos eritrócitos e no perfil da banda 3, sendo a diminuição da espectrina a alteração mais significativa. Aumento na capacidade antioxidante total (TAS), na peroxidação lipídica (TBA) e da razão TBA/TAS foram também demonstrados. Quando comparamos os dois grupos de DRC, verificamos que os não respondedores à terapêutica com EPOhr apresentavam diminuição no número total de linfócitos e nos linfócitos T CD4+, e aumento nos marcadores inflamatórios e na activação dos neutrófilos. Não encontramos diferenças significativas nos parâmetros relacionados com o ciclo do ferro, com excepção do receptor solúvel da transferrina, que se encontrava aumentado nos não respondedores. Os níveis séricos de prohepcidina encontravam-se diminuídos nos não respondedores; no entanto, encontravam-se mais elevados que no grupo controlo. Diminuição acentuada no conteúdo em espectrina, alterações no perfil de banda 3 [diminuição fragmentos proteolíticos da banda 3 (Pfrag) e na razão Pfrag/monómero de banda 3], e uma tendência para valores aumentados de hemoglobina ligada à membrana foram também encontrados nos DRC não respondedores à terapêutica com EPOhr. Em conclusão, apesar da etiologia à resistência à terapêutica com EPOhr não estar ainda completamente esclarecidaos nossos resultados confirmam que a inflamação parece ter um papel muito importante. Encontramos também relação entre resistência è terapêutica com EPOhr com défice funcional em ferro, linfocitopenia e linfocitopenia T CD4+, níveis plasmáticos aumentados de elastase, níveis séricos aumentados de interleucina-7, e alterações na estrutura das proteínas de membrana do eritrócito e no perfil de banda 3. Mais estudos serão necessários para se entender a associação entre a inflamação, e resistência à terapêutica com EPOhr e diminuição na disponibilidade em ferro.