Search

Objective/background: Sickle cell anemia (SCA) is associated with increased levels of extracellular heme, which is a key mediator of inflammation in this condition. Despite abundant evidence supporting this concept in cell and animal models, few studies addressed the association between heme levels and the development and severity of acute vasoocclusive crises (VOC) in humans., Methods: A cross-sectional study was conducted in patients with acute VOC. Total extracellular heme levels were measured in both plasma and serum at admission and after convalescence, and correlated with other clinical and laboratory markers of SCA severity., Results: A total of 28 episodes of VOC in 25 patients were included. Heme levels were similar between admission and convalescence, and correlated with the difference between pre and post hemoglobin, and SCA severity estimated by a composite score of clinical and laboratory markers. Heme levels were neither associated with VOC severity nor with markers of hemostasis activation, and were similar to those reported in an independent population of SCA patients at steady state., Discussion: Acute VOC are not characterized by significant increases in total extracellular heme levels. Studies measuring the fraction of free extracellular heme unbound to proteins are warranted to further refine our understanding of the role of heme in acute VOC.

Hemolytic diseases such as Sickle Cell Disease (SCD) are characterized by a natural propensity for both arterial and venous thrombosis. The ability of heme to induce tissue factor (TF) activation has been shown both in animal models of SCD, and in human endothelial cells and monocytes. Moreover, it was recently demonstrated that heme can induce coagulation activation in the whole blood of healthy volunteers in a TF-dependent fashion. Herein, we aim to further explore the cellular mechanisms by which heme induces TF-coagulation activation, using human mononuclear cells, which have been shown to be relevant to in vivo hemostasis. TF mRNA expression was evaluated by qPCR and TF procoagulant activity was evaluated using a 2-stage assay based on the generation of activated factor X (FXa). Heme was capable of inducing both TF expression and activation in a TLR4-dependent pathway. This activity was further amplified after TNF-α-priming. Our results provide additional details on the mechanisms by which heme is involved in the pathogenesis of hypercoagulability in hemolytic diseases.

Intravascular hemolysis (IH) contributes to the development of endothelial dysfunction (ED) in sickle cell anemia (SCA), and the effects of hydroxyurea (HU, the only approved drug that decreases the frequency and severity of vaso-oclussive crises) on IH and ED in SCA remain unclear. We evaluated and compared the markers of IH among steady-state adult Brazilians with SCA and HbAA individuals. Overall, this cross-sectional study enrolled 30 SCA patients not receiving HU therapy (HbSS), 25 SCA patients receiving HU therapy (HbSS_HU), and 32 HbAA volunteers (HbAA). The IH markers evaluated were serum Lactate Dehydrogenase (LDH), total heme, plasma hemoglobin (pHb), and soluble CD163 (sCD163). The ED markers analyzed were plasma von Willebrand factor (VWF:Ag), VWF ristocetin cofactor activity (VWF:RCo) levels, antigen of VWF-cleaving protease (ADAMTS13:Ag), thrombospondin-1, endothelin-1 levels, and ADAMTS13 Activity (ADAMTS13:Act). The levels of VWF:Ag, VWF:RCo, total heme, thrombospondin-1, and endothelin-1 were significantly higher in SCA patients (HbSS and HbSS_HU) compared to HbAA individuals. Also, pHb, LDH, and thrombospondin-1 levels were significantly higher in the HbSS group than in the HbSS_HU group. Contrarily, the levels of sCD163, ADAMTS13:Ag, and ADAMTS13:Act were significantly lower in both groups of SCA patients than HbAA controls, and ADAMTS13:Act levels were significantly lower in HbSS compared to HbSS_HU patients. The higher ADAMTS13 activity levels in those on HU therapy may be attributed to lower pHb and thrombospondin-1 levels as previously shown by in vitro studies that thrombospondin-1 and pHb are bound to VWF. Thus, VWF is restrained from ADAMTS13 activity and cleavage., (© 2021. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Sickle Cell Anemia (SCA) is the most common genetic disorder around the world. The mutation in the β-globin gene is responsible for a higher hemolysis rate, with further involvement of immunological molecules, especially cytokines, chemokines, growth factors, and anaphylatoxins. These molecules are responsible for inducing and attracting immune cells into circulation, thus contributing to increases in leukocytes and other pro-inflammatory mediators, and can culminate in a vaso-occlusive crisis (VOC). This study aimed to characterize the levels of these molecules in SCA patients in different clinical conditions in order to identify potential hallmarks of inflammation in these patients. An analytical prospective study was conducted using the serum of SCA patients in steady-state (StSt; n = 27) and VOC ( n = 22), along with 53 healthy donors (HD). Samples from the VOC group were obtained on admission and on discharge, in the convalescent phase (CV). Levels of chemokines (CXCL8, CXCL10, CL2, CLL3, CCL4, CL5, and CCL11), cytokines (IL-1β, IL-1ra, IL-2, IL-4, IL-5, IL-6, IL-7, IL-10, IL-12p70, IL-13, IL-17A, TNF-α, and IFN-γ) and growth factors (VEGF, FGFb, PDGF-BB, GM-CSF, and G-CSF) were measured using a Luminex assay, and anaphylatoxins (C3a, C4a, and C5a) were measured using Cytometric Bead Array. SCA patients in StSt showed a pro-inflammatory profile, and were indicated as being higher producers of CCL2, IL-1β, IL-12p70, IFN-γ, IL-17A, and GM-CSF, while VOC is highlighted by molecules IL-4 and IL-5, but also IL-2, IL-7, PDGF-BB, and G-CSF. PDGF-BB and IL-1ra seemed to be two important hallmarks for the acute-to-chronic stage, due to their significant decrease after crisis inflammation and statistical difference in VOC and CV groups. These molecules show higher levels and a strong correlation with other molecules in VOC. Furthermore, they remain at higher levels even after crisis recovery, which suggest their importance in the role of inflammation during crisis and participation in immune cell adhesion and activation. These results support a relevant role of cytokines, neutrophil and monocytes, since these may act as markers of VOC inflammation in SCA patients., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Silva-Junior, Garcia, Cardoso, Dias, Tarragô, Fraiji, Gomes, Amaral, Teixeira-Carvalho, Martins-Filho, De Paula, Costa and Malheiro.)

Free extracellular heme has been shown to activate several compartments of innate immunity, acting as a danger-associated molecular pattern (DAMP) in hemolytic diseases. Although localized endothelial barrier (EB) disruption is an important part of inflammation that allows circulating leukocytes to reach inflamed tissues, non-localized/deregulated disruption of the EB can lead to widespread microvascular hyperpermeability and secondary tissue damage. In mouse models of sickle cell disease (SCD), EB disruption has been associated with the development of a form of acute lung injury that closely resembles acute chest syndrome (ACS), and that can be elicited by acute heme infusion. Here we explored the effect of heme on EB integrity using human endothelial cell monolayers, in experimental conditions that include elements that more closely resemble in vivo conditions. EB integrity was assessed by electric cell-substrate impedance sensing in the presence of varying concentrations of heme and sera from SCD patients or healthy volunteers. Heme caused a dose-dependent decrease of the electrical resistance of cell monolayers, consistent with EB disruption, which was confirmed by staining of junction protein VE-cadherin. In addition, sera from SCD patients, but not from healthy volunteers, were also capable to induce EB disruption. Interestingly, these effects were not associated with total heme levels in serum. However, when heme was added to sera from SCD patients, but not from healthy volunteers, EB disruption could be elicited, and this effect was associated with hemopexin serum levels. Together our in vitro studies provide additional support to the concept of heme as a DAMP in hemolytic conditions., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2020 Santaterra, Fiusa, Hounkpe, Chenou, Tonasse, da Costa, Garcia-Weber, Domingos, Lima, Borba-Junior, Araújo, Lucena-Araújo, Bezerra, dos Santos, Costa, Millán and De Paula.)

Sickle cell disease (SCD) is an inherited hemoglobinopathy that is caused by the presence of abnormal hemoglobin S (HbS) in red blood cells, leading to alterations in red cell properties and shape, as the result of HbS dexoygenation and subsequent polymerization. SCD pathophysiology is characterized by chronic inflammatory processes, triggered by hemolytic and vaso-occlusive events, which lead to the varied complications, organ damage and elevated mortality seen in individuals with the disease. In association with activation of the endothelium and leukocytes, hemostatic alterations and thrombotic events are well-documented in SCD. Here we discuss the role for inflammatory pathways in modulating coagulation and inducing platelet activation in SCD, due to tissue factor activation, adhesion molecule expression, inflammatory mediator production and the induction of innate immune responses, amongst other mechanisms. Thromboinflammatory pathways may play a significant role in some of the major complications of SCD, such as stroke, venous thromboembolism and possibly acute chest syndrome, besides exacerbating the chronic inflammation and cellular interactions that trigger vaso-occlusion, ischemia-reperfusion processes, and eventually organ damage.

The impaired bioavailability of endogenous nitric oxide (NO) in sickle cell anemia (SCA) may be influenced by polymorphisms in the endothelial nitric oxide synthase gene (eNOS). We compared allelic/genotypic frequencies of the eNOS polymorphisms T-786C, VNTR4a/b and G894T between 89 adult SCA patients and 100 healthy controls, and investigated the relationship between these SNPs and markers of hemolysis [lactate dehydrogenase (LDH), indirect bilirubin (IB) and reticulocyte counts], inflammation [interleukins IL-1β, IL-6, IL-8, Tumor Necrosis Factor (TNF-α) and C-reactive protein (CRP)] and endothelial dysfunction (ED) [soluble vascular cell adhesion molecule-1 (sVCAM-1), soluble intercellular adhesion molecule-1 (sICAM-1), soluble L-selectin (sL-selectin), von Willebrand Factor (vWF) antigen and D-dimers] in the patients. The frequencies of the mutant -786C allele and -786C/C genotype were significantly higher in patients (p = 0.02 and p = 0.04, respectively) but not significantly correlated with the markers. For VNTR4a/b and G894T, the allelic/genotypic frequencies did not statistically differ between patient and control groups. Patients carrying the 4a allele and those with the 894G/G genotype showed a significant decrease in IB (p = 0.02 and p = 0.04, respectively), and only patients with the 4a allele exhibited reduced IL-1β (p = 0.01). The correlation profiles between markers of inflammation and ED significantly differed between patients carrying the mutant alleles and those with wild-type genotypes. This appears to be the first report on the relationship between eNOS gene polymorphisms and markers of hemolysis, inflammation and ED in Brazilian SCA patients. Our results indicate that the SNPs analyzed may influence the phenotypic variability of these patients.

Background: Sickle cell anemia (SCA) is associated with a chronic proinflammatory state characterized by elevated leukocyte count, mortality from severe recurrent infections, and subsequent vasoocclusive complications with leukocyte adhesion to the endothelium and increased plasma levels of inflammatory cytokines. The immune system has a close connection with morbidity in SCA, but further studies are needed to uncover the involvement of innate and adaptive immunities in modulating the SCA physiopathology. We performed measurements of the frequency of innate and adaptive immunity cells, cytokines, chemokines, and growth factors and immunophenotyping of Toll-like receptor and adhesion molecule expression in the blood of SCA patients and healthy donors to evaluate the different profiles of these biomarkers, the relationship among them, and their correlation to laboratory records and death risk. Material and Methods . Immunophenotyping of cells, Toll-like receptors, and adhesion molecules were performed from peripheral blood samples of SCA patients and healthy donors by flow cytometry and cytokine/chemokine/growth factor measurement by the Luminex technique performed from the serum of the same subjects., Results: Cells of adaptive immunity such as IL-12, IL-17, and IL-10 cytokines; IL-8, IP-10, MIP-1 α , MIP-1 β , and RANTES chemokines; and VEGF, FGF-basic, and GM-CSF growth factors were higher in SCA patients than healthy donors regardless of any laboratorial and clinical condition. However, high death risk appears to have relevant biomarkers., Conclusion: In the SCA pathophysiology at steady state, there is a broad immunological biomarker crosstalk highlighted by TCD4+CD69+ lymphocytes, IL-12 and IL-17 inflammatory and IL-10 regulatory cytokines, MIP-1 α , MIP-1 β , and IP-10 chemokines, and VEGF growth factor. High expression of TLR2 in monocytes and VLA-4 in TCD8+ lymphocytes and high levels of MIP-1 β and RANTES appear to be relevant in high death risk conditions. The high reticulocytosis and high death risk conditions present common correlations, and there seems to be a balance by the Th2 profile., Competing Interests: The authors declare that there is no conflict of interests regarding the publication of this paper., (Copyright © 2020 Nadja Pinto Garcia et al.)

Objective/background: Sickle cell disease (SCD) is a chronic inflammatory condition caused by a point mutation in the HBB gene. Here we characterized the clinical presentation of SCD in a population from Amazonas State in northern Brazil, in order to evaluate whether the higher Amerindian ancestry observed in this relatively isolated geographic region would influence the clinical presentation of SCD., Methods: This was a cross-sectional study characterizing the clinical presentation of SCD patients registered at HEMOAM, Amazon, Brazil. Data were obtained using a structured questionnaire, and by a review of the medical records., Results: Of the 236 SCD patients listed in the historical records, 122 were included in this study. The median age was 15 years, with a male to female ratio of 52:70. The population was characterized by a high level of socioeconomic vulnerability, with only 2.1% presenting a family income above five minimum wages. Homozygous HbS (SS) was the most prevalent form of SCD (89.7%), and the diagnosis of SCD was performed in the context of complications in 92.3% of patients. The median frequency of vaso-occlusive crisis in the past 12 months was 2 (0-10). Using a validated clinical severity score based on clinical and laboratory data, no significant difference could be observed when compared to other populations., Conclusion: Our results represent the first comprehensive characterization of epidemiological, laboratorial, and clinical data of SCD in the region of the Brazilian Amazon. Despite the higher contribution of Amerindian ancestry previously demonstrated in this region, the main clinical characteristics of SCD seem similar to those reported in other populations., (Copyright © 2019 King Faisal Specialist Hospital & Research Centre. Published by Elsevier Ltd. All rights reserved.)

Background: Interleukins IL1ß/IL18 and Inflammasome NLRP1/NLRP3 polymorphisms can change the course of multiple human diseases, both inflammatory as infectious. SNPs these proteins were associated with the constructive activation of the Inflammasome and excessive production of IL-1β induce a serious autoinflammatory disease, as sickle cell anemia (SCA). The present study aims to association of interleukins IL1ß/IL18 and inflammasome NLRP1/NLRP3 polymorphisms in SCA patients in Amazon region and their association with severity score., Methods: The study was developed at Fundação Hospitalar de Hematologia e Hemoterapia do Amazonas (HEMOAM) with 21 patients diagnosed SCA (HbSS) and 50 Healthy Donor´s. Genetic polymorphisms (SNPs) in interleukins IL1ß/IL18 and inflammasome NLRP1/NLRP3 were genotyped by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) and real time PCR. Simple and multiple logistic regression were performed to investigate association between the polymorphisms and the SCA and severe score., Results: The genotypes C/C (IL18 -137G/C) and C/A (NLRP3, rs35829419) appear to be risk factors for SCA disease (IL18: G/G vs C/C OR=103.500 [95% CI: 8.32-1287.79, p<0.00001]; IL18: G/G vs G/C OR=7.360 [95% CI: 0.85-63.48, p=0.040]; IL18: G/G vs CC+CG OR=14.481 [95% CI: 1.79-117.32, p=0.002; NLRP3: C/C vs C/A: OR=10.967 [95% CI: 2.41-49.89, p=0.0004]). In addition, only allelic C (IL18 -137G/C) and A (NLRP3) appear to be risk factors for SCA disease (IL18: G vs C OR=6.366 [95% CI: 2.73-14.86, p<0.00001]; NLRP3: C vs A OR=8.383 [95% CI: 2.03-34.62, p=0.005]. No associations were observed between genotypes and alleles with the severity score., Conclusion: Evidence of association between the IL18 (rs16944) and NLRP3 (rs35829419) polymorphisms with sickle cell anemia were described. Our results suggest that individuals with genotypes evaluated are associated SCA disease even though it does not influence the severe score., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.net.)

Despite the detailed characterization of the inflammatory and endothelial changes observed in Sickle Cell Disease (SCD), the hierarchical relationship between elements involved in the pathogenesis of this complex disease is yet to be described. Meta-analyses of gene expression studies from public repositories represent a novel strategy, capable to identify key mediators in complex diseases. We performed several meta-analyses of gene expression studies involving SCD, including studies with patient samples, as well as in-vitro models of the disease. Meta-analyses were performed with the Inmex bioinformatics tool, based on the RankProd package, using raw gene expression data. Functional gene set analysis was performed using more than 60 gene-set libraries. Our results demonstrate that the well-characterized association between innate immunity, hemostasis, angiogenesis and heme metabolism with SCD is also consistently observed at the transcriptomic level, across independent studies. The enrichment of genes and pathways associated with innate immunity and damage repair-associated pathways supports the model of erythroid danger-associated molecular patterns (DAMPs) as key mediators of the pathogenesis of SCD. Our study also generated a novel database of candidate genes, pathways and transcription factors not previously associated with the pathogenesis of SCD that warrant further investigation in models and patients of SCD.

Objective: To evaluate the effects of prophylactic transfusion by means of erythrocytapheresis at the beginning of the third trimester of pregnancy in women with sickle cell disease (SCD)., Methods: A cohort of 14 pregnant women with SCD who received prophylactic erythrocytapheresis transfusions at the beginning of the third trimester was retrospectively compared with a cohort of 17 pregnant women who received simple prophylactic transfusions for no indication other than SCD severity., Results: Prophylactic erythrocytapheresis transfusions were associated with a lower risk of intrauterine growth restriction (OR, 0.11; 95% confidence interval, 0.01-1.00) and oligohydramnios (OR, 0.65; 95% confidence interval, 0.45-0.92) in pregnant women with SCD., Conclusion: These results suggest that erythrocytapheresis transfusions are beneficial in women with SCD who are in the third trimester of pregnancy. Given the decrease in transfusion risks, this therapy deserves further evaluation in future trials.