Plasma immune mediators as laboratorial biomarkers for Sickle Cell Disease patients according to the hydroxyurea therapy and disease severity.

In the present work, the impact of Sickle Cell Disease (SCD) degrees of severity, as well hydroxyurea treatment on the systemic immunological signatures of patients was evaluated. Based on a high-throughput chemokine, cytokine and growth factor multiplex analysis, it was possible to obtain the systemic immunological profile of patients with SCD (n = 40), treated or not with hydroxyurea, as compared to healthy controls (n = 40). Overall, SCD patients with severe disease displayed increased levels of almost all biomarkers analyzed. Our data demonstrated that CXCL8, CCL3 and CXCL10 were pointed out as universal biomarkers of SCD. The results also indicated that HU-untreated patients with indication of HU-therapy display a more prominent increase on plasma immune mediators in a similar way as those with severe SCD disease. Together, these findings provided a comprehensive landscape of evidence that may have implications for further therapeutic strategies and SCD clinical management.

Endothelial dysfunction biomarkers in sickle cell disease: is there a role for ADMA and PAI-1?

Within the spectrum of sickle cell disease (SCD) are sickle cell anemia (SCA), presence of hemoglobin SS (HbSS), hemoglobin SC disease (HbSC), and sickle cell ß-thalassemia (Sß-thal). Asymmetric dimethylarginine (ADMA) competitively inhibits the binding of arginine to NOS, reducing NO production. In patients with HbSS, increased levels of ADMA have been reported, as well as changes in many hemostatic biomarkers, including the plasminogen activator inhibitor type 1 (PAI-1). We hypothesized that high levels of ADMA and PAI-1 may be associated with more severe SCD. Thus, ADMA and PAI-1 levels were determined in 78 individuals including 38 adult patients with SCD and 40 control subjects. Higher levels of ADMA were shown in HbSS and Sß-thal patients compared to controls. Concerning PAI-1, all patients showed high levels of PAI-1 compared to controls. As a role of NO in the pathogenesis of SCD has already been established, we concluded that high levels of ADMA should compromise, at least in part, NO synthesis, resulting in endothelial dysfunction. Elevated plasma levels of PAI-1 in all patients may indicate not only endothelial dysfunction but also a hypofibrinolytic state favoring thrombotic complications. Finally, high levels of ADMA and PAI-1 may be associated with more severe SCD.

ADAMTS-13-VWF axis in sickle cell disease patients.

Sickle cell disease (SCD) comprises a group of genetic disorders characterized by the presence of the hemoglobin (Hb) S in homozygosis or in heterozygosis with some other Hb variant or in interaction with thalassemia. SCD is characterized by a very complex pathophysiology, which determines a wide variability of clinical manifestations, including a chronic state of hypercoagulability responsible for the increased risk of thromboembolic events. ADAMTS13 and von Willebrand factor (VWF) play an important role in arterial and venous thrombosis. Thus, the aim of this study was to understand how the ADAMTS13-VWF axis behaves in sickle cell disease, as well as whether there is an association of these markers with the use of hydroxyurea (HU). This is a cross-sectional study conducted with 40 patients diagnosed with SCD and 40 healthy individuals. The analysis of the ADAMTS13-VWF axis was comparatively performed between groups of patients and controls and, afterwards, between patients with SCD who were users and non-users of HU. ADAMTS13 activity, ADAMTS13 activity/VWF:Ag, and ADAMTS13:Ag/VWF:Ag ratios were significantly lower and VWF:Ag levels significantly higher in SCD patients when compared to the controls. There was no statistically significant difference in ADAMTS13:Ag and VWF collagen binding (VWF:CB) levels between the groups evaluated. Among the categories of HU use, there was no statistically significant difference in any of the evaluated markers. As a conclusion, we could observe that the ADAMTS13-VWF axis is altered in SCD when compared to healthy individuals and that there is no association between these markers and the use of HU.

Thrombin generation in vivo and ex vivo in sickle cell disease patients.

Activation of coagulation is an important hallmark of sickle cell disease (SCD) and it is believed that hypercoagulability plays a role to the disease pathophysiology. Studies have sought to identify how hemostatic biomarkers are expressed in SCD, however, the results are inconclusive. In this context, our objective was to evaluate the thrombin generation in vivo and ex vivo in SCD patients and the association between these biomarkers and the use of HU. This cross-sectional study was carried out with patients diagnosed with SCD, users or not of Hydroxyurea (HU), and healthy individuals as controls. D dimer (D-Di) was evaluated by ELISA and (TGT) thrombin generation test by CAT method. D-Di plasma levels were significantly higher in SCD patients when compared to the controls. TGT parameters such as peak, ETP and normalized ETP at low TF concentration and time-to-peak, peak, ETP and normalized ETP values at high TF concentration were lower in SCD patients than in controls. In contrast, the normalized activated protein C sensitivity ratio (nAPCsr) was higher in patients compared to controls, indicating resistance to the action of this natural anticoagulant. Regarding the use of HU, comparing users and non-users of this drug, no difference was observed in D-Di levels and in most TGT parameters. Our data analyzed together allow us to conclude that patients with SCD present a state of hypercoagulability in vivo due to the higher levels of D-Di and resistance to APC assessed ex vivo which is consistent with the coagulation imbalance described in SCD patients.

Prevalência de traço falciforme em doadores de sangue da região Centro-Oeste do Estado de Minas Gerais / Prevalence of sickle cell trait in blood donors in the Midwest region of the State of Minas Gerais

Introdução: Apesar do traço falciforme ser considerado uma condição benigna, existem estudos mostrando que apresenta manifestações clínicas relevantes, o que torna importante a realização de estudos para conhecer sua prevalência. Objetivo: Estimar a prevalência de traço falciforme em doadores de sangue da região Centro-Oeste do estado de Minas Gerais (MG). Metodologia: As informações sobre a presença de HbS no sangue, etnia, gênero, escolaridade, idade, níveis de hemoglobina e procedência dos doadores de sangue foram consultadas no sistema Hemote Plus da Fundação Hemominas (FH). Resultados: A média de idade dos doadores de sangue da região Centro-Oeste de MG foi de 34,4±11,3 anos, 51,4% eram do sexo masculino, 52,8% se autodeclararam brancos, 53,3% possuíam até 2º grau completo e a média dos níveis de hemoglobina foi de 15,1±1,3 g/dL. A prevalência de traço falciforme foi de 2,2% nessa população. Entre os doadores portadores do traço falciforme houve maior frequência de autodeclarados pardos, seguidos de autodeclarados brancos (30,7%) e autodeclarados negros (26,5%), as faixas etárias de 21 a 30 anos (31,9%) e de 31 a 40 anos (30,7%) e o sexo feminino (53,9%) foram mais prevalentes e a média dos níveis de hemoglobina foi de 14,8±1,3 g/dL. Conclusão: A prevalência de traço falciforme encontrada em nosso estudo foi de 2,2%, o que se assemelha à encontrada na população brasileira e é discretamente menor que a do Estado de MG. Esses achados contribuem com os demais estudos de prevalência no Brasil.

Introduction: Although sickle cell trait is considered a benign condition, there are studies showing that it presents relevant clinical manifestations, which makes it important to carry out studies to know its prevalence. Objective: To estimate the prevalence of sickle cell trait in blood donors in the Midwest region of the state of Minas Gerais (MG). Methods: Information on the presence of HbS in the blood, ethnicity, gender, education, age, hemoglobin levels and origin of blood donors were consulted in the Hemote Plus system of the Hemominas Foundation (FH). Results: The mean age of blood donors in the Midwest region of MG was 34.4±11.3 years, 51.4% were male, 52.8% self-declared white, 53.3% had up to high school and the mean hemoglobin levels were 15.1±1.3g/dL. The prevalence of sickle cell trait was 2.2% in this population. Among the donors with sickle cell trait, there was a higher frequency of self-declared brown, followed by self-declared white (30.7%) and self-declared black (26.5%), aged 21 to 30 years (31.9%) and 31 to 40 years (30.7%) and females (53.9%) were more prevalent and the mean hemoglobin levels were 14.8±1.3 g/dL. Conclusion: The prevalence of sickle cell trait found in our study was 2.2%, which is similar to that found in the Brazilian population and is slightly lower than in the state of MG. These findings contribute to other prevalence studies in Brazil.