Steady State Sickle Cell Anemia Is Associated with Increased Formation of Erythrocyte-Derived Microparticles and Acceleration of Thrombin Generation.

Blood ◽  
2009 ◽  
Vol 114 (22) ◽  
pp. 4001-4001 ◽  
Author(s):  
Mourad Chaari ◽  
Katia Stankovic ◽  
Vasso Galea ◽  
Francoise Robert ◽  
Amir Khaterchi ◽  
...  
Keyword(s):  
Steady State ◽  
Plasma Concentration ◽  
Sickle Cell ◽  
Sickle Cell Anemia ◽  
Plasma Levels ◽  
Thrombin Generation ◽  
Conflicts Of Interest ◽  
Inverse Correlation ◽  
Control Group ◽  
Generation Process

Abstract Abstract 4001 Poster Board III-937 Introduction Patients with Sickle Cell Anemia (SCA) are at risk of thrombosis, but this clinical manifestation is variable and it is probably not associated with the frequency of vaso-occlusive crisis. Increased plasma levels of platelet- and erythrocyte-derived microparticles and hypercoagulability markers have been reported in steady state SCA patients. However, the link between hypercoagulability and SCA is not completelty understood. Aim of the study We determined erythrocyte-derived (Ed-MP) and platelet-derived microparticles (Pd-MP) levels in patients with steady state SCA. We studied their relationship with hemolysis markers and their impact on thrombin generation process. Materials and methods Consecutive out-patients with steady state SCA (n=78) and 20 healthy age and sex-matched controls were included. They were free of any acute episode of SCA for at least one month prior inclusion. Microparticles were assessed with standardized whole blood flow cytometry assay. Ed-MP and Pd-MP were identified using respectively anti-CD235a and anti-CD41 monoclonal antibody and annexine V. Thrombin generation (TG) in citrated platelet poor plasma was assessed with Calibrated Automated Thrombogram® (Stago, France) using PPP-reagent 5pM® (Thrombinoscope BV, Nederlands). The following TG parameters were analyzed: lag-time (LT), time to peak of thrombin (ttpeak), peak of thrombin (peak), mean velocity rate index of the TG (MRI) and endogenous thrombin potential (ETP). Results Mean patient age was 25±8 (range 17-58 ys). In the patients group, Ed-MP and Pd-MP, expressing or not phosphatidyl-serine (PS), were significantly increased compared to the control group. Thrombogram parameters were not significantly different in both groups (Table 1). There was a slight though significant inverse correlation between Ed-MP and both LT and ttpeak (r=-0.235, r=-0.315 respectively; p<0.05). Ed-MP levels were correlated with MRI increase (r=0.241; p<0.05). Ed-MP values were inversely correlated with Hb levels and well correlated with reticulocytes count (r=-0.427, r=0.520 respectively; p<0.05). No relationship was found between Ed-MP and ETP values. The sub-population of Ed-MP/PS+ (expressing PS) showed also an inverse correlation with both ttPeak (r=-0.315, p<0.05) and ETP (r=-0.236; p<0.05), and a positive correlation with MRI (r=0.306 ; p<0.05). Pd-MP concentration was inversely correlated with Hb levels (r=-0.273 ; p<0.05). Only Pd-MP/PS+ plasma concentration was slightly by significantly correlated with ETP (r=0.225; p=0,049). Conclusion Patients with steady state SCA presented a significant increase of Ed-MP and Pd-MP plasma levels which seems to be linked to haemolysis degree. Each type of microparticles had different impact on TG process. Ed-MP induced acceleration of TG kinetics without increase of ETP whereas Pd-MP/PS+ affected mainly ETP. However the increase of Ed-MP and Pd-MP plasma concentration does not appear to be by itself a sufficient condition to induce a significant increase of TG. Disclosures: No relevant conflicts of interest to declare.

FXIIa Differentially Regulates Thrombin Generation during Steady State and Vaso-Occlusive Crisis in Sickle Cell Mice

Blood ◽  
2016 ◽  
Vol 128 (22) ◽  
pp. 162-162 ◽  
Author(s):  
Erica M Sparkenbaugh ◽  
Camille Faes ◽  
Denis Noubouossie ◽  
Daniel K. Kirchhofer ◽  
András Gruber ◽  
...  
Keyword(s):  
Steady State ◽  
Mouse Model ◽  
Vascular Permeability ◽  
Sickle Cell ◽  
Plasma Levels ◽  
Thrombin Generation ◽  
Conflicts Of Interest ◽  
Control Group ◽  
Liver And Kidney

Abstract Sickle cell disease (SCD) is associated with chronic activation of coagulation. Previously, we demonstrated that inhibition of tissue factor (TF) attenuates thrombin generation (measured by plasma levels of thrombin-antithrombin complexes [TAT]) in a mouse model of SCD during steady state. Furthermore, we showed that neither inhibition of FXIIa-dependent activation of FXI (using 14E11 antibody) nor FXI deficiency reduces thrombin generation (TG) in sickle mice. In contrast, genetic deficiency of FXII or kininogen (HK) reduced plasma TAT levels. These data suggest that during steady state, FXIIa contributes to TG in sickle mice via activation of the kallikrein/HK pathway, but not FXI. In the present study, we further investigated the mechanisms of HK-induced TG at steady state, and increased TG observed during vaso-occlusive crisis (VOC). All experiments were performed using 4-5 month old Townes SS (sickle) and AA (control) mice. Kallikrein cleaves HK into HK fragments (HKFs) and bradykinin (BK). First, we investigated whether a BK-mediated increase in vascular permeability contributes to TG by exposing perivascular TF. This hypothesis was disproved by data demonstrating no difference in vascular permeability (measured by the extravasation of Evans blue in the heart, lung, liver and kidney) between AA (n=8) and SS (n=10) mice. HKFs were shown to induce leukocyte TF expression in vitro via binding to CD11b/CD18 (Mac-1). Therefore, we investigated whether Mac-1 inhibition affects TG in SS mice. AA and SS mice were treated with an inhibitory anti Mac-1 (M1/70) or IgG control antibody on days 0, 3 and 6 (i.p. 1 mg/kg) and TG was analyzed 1 day after the last injection. In the control group, SS mice demonstrated higher plasma TAT levels compared to AA mice (8.1±1.6 vs 4.2±0.6 ng/mL, n=10-11, p<0.05), but inhibition of Mac-1 significantly reduced plasma TAT levels in SS mice (4.6±0.7 ng/mL, n=11, p<0.05). These data suggest that HK might contribute to TG during steady state via Mac-1-dependent induction of monocyte TF. The steady state of SCD is interspersed with acute periods of VOC. Clinical data demonstrate that compared to the steady state, plasma levels of cell free DNA (cfDNA), activation of the contact system, and TG are further enhanced during VOC. To determine the mechanism of increased TG during VOC, we used the previously characterized mouse model of TNFα -induced VOC. Townes AA and SS mice were injected with recombinant TNFα (2 µg/g body weight) or the same volume of PBS, and plasma was collected 5 hours later. TNFα not only dramatically increased plasma levels of cfDNA in SS mice (14.78 ± 1.64 vs 679 ± 300 ng/mL; p<0.01), but also further increased plasma TAT levels compared to those observed in PBS-treated SS mice (2.9 fold, p<0.001, n=8). Importantly, there was a significant positive correlation between cfDNA and TAT in SS mice (r2 =0.65, p<0.001). Since cfDNA can activate FXII, we determined whether FXIIa-dependent activation of FXI contributes to TG during VOC. AA and SS mice received 14E11 or IgG control (4 mg/kg) 30 minutes before TNFα (2 μg/g) or PBS injection, and plasma TAT was assessed 5 hours later. Strikingly, 14E11 attenuated the increased TAT level in TNFα-treated SS mice, to the level observed in SS mice injected with PBS and IgG (IgG/SS/PBS: 9 ng/mL ± 1.8 vs. IgG/SS/TNF: 18.9 ± 3.6, p<0.001; 14E11/SS/TNF: 9.86 ± 0.72, p<0.05 vs. IgG/SS/TNF). We also determined if TF activity is required for the increased TG observed during VOC. Interestingly, inhibition of TF with an inhibitory 1H1 antibody (25 or 75 mg/kg injected i.p. 1 or 18 hours prior to TNFα, respectively) had no effect on the increased TG observed in TNFα treated SS mice. In aggregate, our data suggest that during the steady state of SCD, FXII-dependent TG is not FXI-dependent, but instead is mediated by a pathway involving HK, Mac-1 integrin and leukocyte TF. Furthermore, we propose that during VOC the massive release of cfDNA results in FXIIa-dependent FXI activation and enhances TG independently of TF. This study provides mechanistic insight into the initiators of TG in SCD. Moreover, it implicates FXIIa as a potential therapeutic target to reduce the prothrombotic state in SCD, during both steady state and VOC. Disclosures No relevant conflicts of interest to declare.

The Effects of Hydroxyurea on the Thrombin Generation and Microparticles in Sickle Cell Anemia Patients

Blood ◽  
2011 ◽  
Vol 118 (21) ◽  
pp. 2292-2292
Author(s):  
Patrick Van Dreden ◽  
Grigoris T Gerotziafas ◽  
Barry J Woodhams ◽  
Mourad Chaari ◽  
Robert Girot ◽  
...  
Keyword(s):  
Steady State ◽  
Sickle Cell ◽  
Thrombin Generation ◽  
Enzyme Linked Immunosorbent Assay ◽  
Control Group ◽  
No Production ◽  
Generation Process ◽  
Coagulation Activation ◽  
Significant Difference ◽  
Hydroxyurea Therapy

Abstract Abstract 2292 Introduction: The clinical course of sickle cell disease (SCD) is punctuated by episodic vascular occlusive events. The possibility that activation of the clotting system plays a contributory role in these complications is supported by abundant clinical data during both steady-state disease and pain crisis. Hydroxyurea therapy induces fetal haemoglobin, improves laboratory parameters and reduces acute clinical complications of SCD, but despite an abundance of evidence for coagulation and platelet activation, it remains incompletely defined whether these changes contribute to the reduced thrombin generation. This study is designed to evaluate coagulation profiles of patients with SCA in steady state and to determine whether hypercoagulable state is modified or not in patients on hydroxyurea therapy. Patients and Methods: We studied erythrocyte derived microparticles (Ed-MP) and platelet derived microparticles (Pd-MP) expressing or not expressing phosphatidylserine (PS) in patients with steady state SCD and we evaluated their specific procoagulant activity and their impact on thrombin generation process. A total of 92 steady state SCD patients were included in the study, of which 19 were under treatment with hydroyurea. The control group consisted of 30 healthy age and sex matched controls. Microparticles in whole blood were assessed using flow cytometry. Ed-MP and Pd-MP were identified using an anti-CD235 and CD41 monoclonal antibodies and annexin V. Thrombin generation in platelet poor plasma (PPL) was measured by CAT assay using PPP-reagent 5pM (Thrombinoscope, The Netherlands). Procoagulant phospholipid dependent activity in plasma was assessed by the Procoag-PPL assay (Diagnostica Stago, France). Thrombomodulin (TM) levels were measured by enzyme-linked immunosorbent assay (Elisa) Asserachrom thrombomodulin (Diagnostica Stago, Asnieres, France). Results: Hydroxyurea treated patients had lower counts of leukocytes, reticulocytes and platelets and an increased mean hemoglobin concentration as compared to non treated patients. Leukocyte and reticulocytes counts of treated patients were higher than those of controls. Platelets counts did not differ between treated and untreated patients. Patients on treatment with hydroxyurea had significantly lower levels of Ed-MP/PS+ and Ed-MP compared to untreated patients. The concentration of Pd-MP/PS+ and Pd-MP were not significantly different between hydroxyurea treated and non treated patients. The Ed-MP/PS+ showed a significant inverse correlation with Hb F (p<0.05). Thrombogram parameters, lag-time, ttPeak, Peak and MRI were significantly different between hydroxyurea treated patients and non treated patients. In hydroxyurea treated patients in contrast to the untreated ones no correlation was found between Ed-MP/PS+ and Ed-MP and parameters of thrombin generation. Among hydroxyurea treated patients 68% showed MRI levels higher than the UNL. Stratification groups of treated patients according to the levels of microparticles with Ed-MP/PS+ or Pd-MP/PS+ concentration higher than the UNL showed non significant difference compared to entirely group of patients. The PPL concentration was significantly lower in the SCD-treated patient compared to untreated patients (p<0.05). In contrast to platelet-derived-microparticles, the numbers of erythrocyte-derived-microparticles differed between patients with and without hydroxyurea during steady state. In patients treated with hydoxyurea, platelets were correlated with Ed-MP, Pd-MP with and without PS+ (p<0.05), but any of the others parameters showed one association. Procoagulant phospholipids and thrombomodulin were increased in SCD with and without hydroxyurea compared with controls group (p<0.05). Conclusion: Treatment with hydroxyurea result in decreases in plasma markers of thrombin generation, and may decrease coagulation activation by reducing PS expression on the surface of both RBCs and platelets in addition to being a NO donor hydro may also decrese haemostatic activation by its effect in decreasing the white blood cell count and particularly monocytes that express TF, furthermore the beneficial effects of hydroxyurea may be due to vasodilatationand decressed platelet and coagulation activation following NO production. Disclosures: Van Dreden: Diagnostica Stago: Employment. Gerotziafas:APHP: Employment. Woodhams:Diagnostica Stago: Employment. Chaari:APHP: Employment. Girot:APHP: Employment. Kartechi:APHP: Employment. Galea:APHP: Employment. Lionnet:APHP: Employment. Elalamy:APHP: Employment.

scholarly journals Is there a role for selective vasodilation in the management of sickle cell disease?

Blood ◽  
1988 ◽  
Vol 71 (3) ◽  
pp. 597-602 ◽  
Author(s):  
GP Rodgers ◽  
MS Roy ◽  
CT Noguchi ◽  
AN Schechter
Keyword(s):  
Blood Flow ◽  
Steady State ◽  
Sickle Cell Disease ◽  
Sickle Cell ◽  
Sickle Cell Anemia ◽  
Microvascular Obstruction ◽  
Controlled Study ◽  
Control Group ◽  
Cell Disease ◽  
Retinal Arteriolar

Abstract To test the hypothesis that microvascular obstruction to blood flow at the level of the arteriole may be significant in individuals with sickle cell anemia, the ophthalmologic effects of orally administered nifedipine were monitored in 11 steady-state patients. Three patients with evidence of acute peripheral retinal arteriolar occlusion displayed a prompt reperfusion of the involved segment. Two other patients showed fading of retroequatorial red retinal lesions. Color vision performance was improved in six of the nine patients tested. The majority of patients also demonstrated a significant decrease in the amount of blanching of the conjunctiva which reflects improved blood flow to this frequently involved area. Such improvements were not observable in a control group of untreated stable sickle cell subjects. These findings support the hypothesis that inappropriate vasoconstriction or frank vasospasm may be a significant factor in the pathogenesis of the microvascular lesions of sickle cell disease and, further, that selective microvascular entrapment inhibition may offer an additional strategy to the management of this disorder. We believe a larger, placebo-controlled study with nifedipine and similar agents is warranted.

Hemoglobinuria Is a Risk Factor For Kidney Disease Progression In Sickle Cell Anemia

Blood ◽  
2013 ◽  
Vol 122 (21) ◽  
pp. 996-996
Author(s):  
Santosh L. Saraf ◽  
Xu Zhang ◽  
Tamir Kanias ◽  
James P. Lash ◽  
Robert E. Molokie ◽  
...  
Keyword(s):  
Steady State ◽  
Kidney Disease ◽  
Kidney Function ◽  
Sickle Cell ◽  
Sickle Cell Anemia ◽  
Conflicts Of Interest ◽  
Red Blood Cell Transfusion ◽  
Free Hemoglobin ◽  
Arterial Blood

Abstract Chronic kidney disease (CKD) is a frequent complication of sickle cell anemia (SCA) and is a predictor of early mortality. To determine the predictors of deteriorating kidney function in SCA, we followed 164 patients treated at the University of Illinois at Chicago for a median of 32 months (range 3-88 months). Steady-state estimated glomerular filtration (eGFR), albuminuria, and hemoglobinuria assessments were obtained at baseline and during the follow-up period. Steady-state was defined as greater than four weeks from a vaso-occlusive pain episode or a red blood cell transfusion. Hemoglobinuria was defined as positive for blood on dipstick and < 2 red blood cells on microscopy. Fifty-six (34%) of the patients had hemoglobinuria at baseline. We confirmed in a subset of 43 patients that dipstick positive hemoglobinuria (n=17) was associated with higher urine cell-free hemoglobin concentrations determined by ELISA than dipstick negative urine (n=26) (23.1 vs. 11.5 ng/mL, p<0.0001) (Figure 1). Age and mean arterial blood pressures were similar in patients with hemoglobinuria at baseline compared to those without but markers of hemolysis were higher (LDH, indirect bilirubin, AST, and reticulocyte percentage; p<0.0001). Sixty-one percent (95%CI: 48-73%) of patients with hemoglobinuria at baseline had hemoglobinuria at most recent follow up compared to 9% (95%CI: 5-18%) of patients without hemoglobinuria at baseline (p<0.0001). The proportion of patients with CKD progression defined by a 50% reduction in eGFR calculated by the CKD-EPI formula or requirement for hemodialysis or kidney transplant was higher in patients with baseline hemoglobinuria (13%, 7/56) versus without hemoglobinuria (1%, 1/108) (HR 14, 95%CI: 2-113; logrank p=0.001) (Figure 2). Progression of albuminuria category from normoalbuminuria (albuminuria < 30mg/g creatinine) to either microalbuminuria (albuminuria = 30-300 mg/g creatinine) or macroalbuminuria (albuminuria > 300mg/g creatinine) or microalbuminuria to macroalbuminuria was also higher in patients with baseline hemoglobinuria (42%, 11/26) versus without hemoglobinuria (13%, 9/67) (HR 3.1, 95%CI: 1.3-7.7; logrank p=0.004) (Figure 3). In conclusion, hemoglobinuria determined by urinalysis at steady-state is a valid assessment of increased urine cell-free hemoglobin concentration and is fairly consistent on repeat testing at steady-state visits. The presence of hemoglobinuria is significantly associated with a greater risk for progression of CKD and albuminuria. Our findings are consistent with the possibility that cell-free hemoglobin contributes to the progression of kidney disease in SCA. Further research including measures to decrease cell-free hemoglobin exposure to preserve kidney function are warranted.Figure 1Figure 1. Figure 2Figure 2. Figure 3Figure 3. Disclosures: No relevant conflicts of interest to declare.

Increased Platelet-Derived CD40L May Modulate Endothelial Cell ICAM-1 Expression and Interact With Leukocytes In Sickle Cell Anemia

Blood ◽  
2013 ◽  
Vol 122 (21) ◽  
pp. 974-974
Author(s):  
Vanessa Tonin Garrido ◽  
Renata Proença-Ferreira ◽  
Venina M. Dominical ◽  
Marcos André Cavalcanti Bezerra ◽  
Aderson S. Araujo ◽  
...  
Keyword(s):  
Flow Cytometry ◽  
Endothelial Cells ◽  
Steady State ◽  
Sickle Cell ◽  
Sickle Cell Anemia ◽  
Repeated Measures ◽  
Conflicts Of Interest ◽  
Endothelial Activation ◽  
Surface Expression ◽  
Platelet Surface

Abstract Background Vaso-occlusive events are a major cause of morbidity in sickle cell anemia (SCA) and attributable to the abnormal adhesion of red cells and leukocytes to the endothelium. Platelets may contribute to the chronic inflammation and endothelial activation that initiates the vaso-occlusive process. We hypothesized that platelet-associated CD40 ligand (CD40L) may contribute to platelet-mediated inflammatory responses in SCA. Aims This study evaluated the platelet (PLT) release of CD40L, the expression of its receptor (CD40) on platelets, neutrophils, lymphocytes and monocytes of control individuals (CON) and SCA patients, and also the ability of platelet-derived CD40L to activate endothelial cells. Methods IL-8, soluble ICAM-1, VCAM-1 and CD40L were determined in PLT-free plasma or the supernatant of stimulated (ADP or Collagen) and unstimulated PLTs (2•10⁸/mL in Kreb’s buffer), from CON individuals and steady-state SCA patients, by ELISA. Flow cytometry was used to analyze CD40 expression on platelets, neutrophils, lymphocytes and monocytes from the peripheral blood of the study’s subjects. Human umbilical vein endothelial cells (HUVECs) were cultured (1x106cells/well; 37°C, 5% CO2) together with PLTs (3x108PLTs/well) from CON individuals or steady-state SCA patients for 24h, 37°C, 5%CO2, in the presence, or not, of blocking antibodies against CD40L. After incubation, PLTs were removed and HUVECs analyzed by flow cytometry for CD54 (ICAM-1) surface expression. Results SCA individuals presented elevated levels of plasma CD40L (724.4± 55.7 pg/ml; n=90) compared to CON (241.5±34.6 pg/ml; n=41; P<0.0001) and these levels correlated with PLT counts (rs=0.255; P=0.015). No correlation was found between plasma CD40L and plasma IL-8, ICAM-1 or VCAM-1. PLT release of CD40L (90 min, 37°C, 5%CO2) was evaluated; PLTs of SCA patients released higher quantities of CD40L (8347±1464 pg/108 PLTs; n=10) than PLTs of CON individuals (3652±568 pg/108 PLTs; n=5; P=0.019). CD40L release from SCA PLTs was augmented by incubation with collagen (P<0.001), but not ADP. Expression of the CD40 receptor on the platelet surface was elevated in the SCA group (52.4±2.7% positive cells; n=23), compared to the CON group (36.8±3.7% positive cells; n=9; P=0.005). The surface expression of CD40 was also elevated on neutrophils (SCA, 10.4±1.5% positive cells, n=14; CON, 5.5±1.1% positive cells, n=13; P=0.03), lymphocytes (SCA, 8.3±0.8% positive cells, n=16; CON, 3.6±0.4% positive cells, n=14; P<0.001) and monocytes (SCA 69.6±5.9% positive cells, n=16; CON, 49.9±5.8% positive cells, n=14; P=0.03) of SCA patients, compared to controls. ICAM-1 expression on the surface of HUVECs (Basal expression 32.8±1.8%, n=11) was significantly increased following incubation with SCA PLTs (54.0±4.8%, n=11, p<0.0001) and slightly augmented after incubation with CON PLTs (40.8±3.1%, n=11, p<0.05; Repeated measures ANOVA). Interestingly, when HUVECs and SCA PLTs were incubated with a blocking antibody against CD40L, the increase in ICAM-1 expression was significantly reversed on HUVECs (HUVECs, 28.1±0.2%, n=6; HUVECs+SCA PLTs, 42.0±3.3%, n=6; HUVECs+SCA PLTs+anti-CD40L 28.9±1.5%, n=6; P<0.01). Conclusions Plasma levels and platelet release of CD40L were found to be significantly elevated in SCA, in association with increased expressions of the CD40 receptor on SCA PLTs, neutrophils, lymphocytes and monocytes, possibly indicating a CD40L-mediated crosstalk between platelets and leukocytes in SCA. Platelets from SCA patients can induce adhesion molecule expression on the surface of endothelial cells in vitro, and this up-regulation may be modulated by platelet-derived CD40L. Results suggest that the CD40/CD40L pathway may be altered in SCA and that platelets may participate in this up-regulation. Given the potent inflammatory effect of this cytokine, a role for platelets and this cytokine in endothelial activation, inflammation and consequent vaso-occlusion, is likely. Disclosures: No relevant conflicts of interest to declare.

Absolute Reticulocyte Count Is Negatively Correlated with Fetal Hemoglobin during Infancy and Early Childhood in Patients with Sickle Cell Anemia

Blood ◽  
2014 ◽  
Vol 124 (21) ◽  
pp. 4081-4081
Author(s):  
Emily R. Meier ◽  
Colleen Byrnes ◽  
Y. Terry Lee ◽  
Maxine Weissman ◽  
Jeffery L. Miller
Keyword(s):  
Steady State ◽  
Sickle Cell ◽  
Sickle Cell Anemia ◽  
Conflicts Of Interest ◽  
Fetal Hemoglobin ◽  
Convenience Sample ◽  
Risk Of Death ◽  
Increased Risk ◽  
F Cells ◽  
Analytical Approaches

Abstract Hemoglobin switching is largely complete in healthy infants by 6 months of age. In infants with sickle cell anemia (HbSS, SCA), reticulocytosis begins early in life as fetal hemoglobin (HbF) is replaced by sickle hemoglobin (HbS). Previous studies demonstrated that patients with an ARC greater than 200 K/uL during early infancy (60-196 days of age) were at the highest risk for SCA-associated events. 1,2 The objective of this study was to determine if ARC is related to HbF levels in a cohort of pediatric SCA patients. A convenience sample of 106 children with SCA between the ages of 1 month and 20 years who were not receiving hydroxyurea or monthly blood transfusions were enrolled in this observational study [42 (39.6%) less than 1 year of age (28-362 days old), 46 (43.4%) between the ages of 1 and 10 years, and 18 (17.0%) between 10 and 20 years old]. After consent and assent were provided, discarded peripheral blood was obtained during routine clinic visits at steady state and analyzed within 48 hours of collection and storage at 40C. Steady state was defined as a sample drawn at least 30 days following an acute event and at least 60 days following a blood transfusion. Hematologic data, including ARC and HbF levels, were measured using CLIA approved methods. F-cells were enumerated by flow cytometry following intracellular staining with a fluorescent antibody directed against HbF. Correlations were calculated to determine the relationships of ARC with HbF, F-cells, and other hematologic data, while two-tailed t tests were used to compare means. Initial studies compared groups based upon ARC greater than or equal to 200 K/uL (ARC≥200) during infancy because of the previously reported utility of this threshold as a predictive marker for SCA severity.1 Over one third of the infants less than 1 year of age (n=16) had an ARC≥200. Mean HbF and F-cell levels were significantly lower in the ARC≥200 group when compared to the ARC<200 group (HbF: 29.9±10.9% vs. 53.5±17.6%, respectively, p=2.2E-05; F-cells: 83.5±13.2% vs. 96.6±5.7%, p=6.2E-05). Mean hemoglobin levels were also lower in the ARC≥200 group [8.1±1.4 g/dL vs. 9.5±1.6 g/dL (ARC<200), p=0.005]. Of the 22 (52.4%) infants who had a HbF level greater than 40%, only 2 (9.1%) had an ARC greater than 200K/uL. Enrolled patients were also grouped according to age and comparisons were made between ARC and HbF or F-cell levels. HbF and F-cell levels were negatively correlated to ARC in the infant subgroup (r=-0.696, p=3.1E-07 and r=-0.795, p=0.000, respectively). HbF and F-cell levels from children between the ages of 1 and 10 years were inversely related to the ARC, but the correlation was less significant (r=-0.626, p=3.3E-06 and r=-0.538, p=1.2E-04, respectively). The inverse relationship was no longer present in the oldest group of patients (HbF vs. ARC r=-0.203, p=0.420 and F-cells vs. ARC, r=-0.258, p=0.302). According to both analytical approaches described here, increased ARC is associated with decreased HbF and F-cell levels in infants with SCA. Less robust negative correlations are maintained through age 10 years, but no significant correlation was identified in adolescence and young adulthood. Overall, the data suggest that increased ARC levels may identify SCA infants who manifest a more rapid or greater loss of fetal hemoglobin during the later stages of the HbF-to-HbS switching phenomenon. Meier ER, Byrnes C, Lee YT, et al. Increased reticulocytosis during infancy is associated with increased hospitalizations in sickle cell anemia patients during the first three years of life. PLoS One 2013; 8(8):e70794. doi: 10.1371/journal.pone.0070794.Meier ER, Wright EC, Miller JL. Reticulocytosis and anemia are associated with an increased risk of death and stroke in the newborn cohort of the Cooperative Study of Sickle Cell Disease. Am J Hematol 2014 May 31; doi: 10.1002/ajh.23777. [Epub ahead of print] Disclosures No relevant conflicts of interest to declare.

The acceleration of the propagation phase of thrombin generation in patients with steady-state sickle cell disease is associated with circulating erythrocyte-derived microparticles

2012 ◽  
Vol 107 (06) ◽  
pp. 1044-1052 ◽  
Author(s):  
Grigoris Gerotziafas ◽  
Patrick Van Dreden ◽  
Mourad Chaari ◽  
Vassiliki Galea ◽  
Amir Khaterchi ◽  
...  
Keyword(s):  
Steady State ◽  
Sickle Cell Disease ◽  
Sickle Cell ◽  
Thrombin Generation ◽  
Generation Process ◽  
Cell Disease ◽  
Significant Acceleration ◽  
High Concentrations ◽  
The Impact ◽  
Functional Alteration

SummarySickle cell disease (SCD) is linked to hypercoagulability and is characterised by high concentrations of erythrocyte-derived microparticles (Ed-MPs). However, the impact of procoagulant cell-derived microparticles on the thrombin generation process remains unclear. We analysed the alterations of each phase of thrombin generation (TG) in relation to the concentration of erythrocyte- or platelet-derived microparticles (Ed-MPs and Pd-MPs) in a cohort of patients with steady-state SCD. We studied 92 steady-state SCD patients, 19 of which were under treatment with hydroxyurea, and 30 healthy age- and sex-matched individuals. TG was assessed by calibrated automated thrombogram. Ed-MP and Pd-MP expressing or not phosphatidylserine (PS) were determined by means of flow cytometry. Procoagulant phospholipid-dependent activity in the plasma was evaluated by the Procoag-PPL assay. Levels of thrombomodulin and haemoglobin in the plasma as well as red blood cell and reticulocyte counts were measured. SCD patients, independently of the administration of hydroxyurea, were marked by a significant acceleration in the propagation phase of TG which correlated with the Ed-MP/PS+ concentration. TG was significantly attenuated in hydroxyurea-treated patients. In conclusion, the acceleration of the propagation phase of TG, driven by Ed-MP/PS+, is a major functional alteration in blood coagulation in patients with steady-state SCD. Treatment with hydroxyurea, in addition to the regulation of haemolysis, lowers Ed-MPs and attenuates thrombin generation. The thrombogram could be a useful tool for the diagnosis of hypercoagulability and optimisation of the treatment in patients with SCD.

Interleukin 8 Level, Reticulocyte Counting and aPTT Ratio in Brazilian Sickle Cell Anemia Patients with Leg Ulcers

Blood ◽  
2011 ◽  
Vol 118 (21) ◽  
pp. 4835-4835
Author(s):  
Magnun N N Santos ◽  
Eliel Wagner Faber ◽  
Dulcinéia Martins Albuquerque ◽  
Romulo Tadeu Dias Oliveira ◽  
Marcos André Cavalcanti Bezerra ◽  
...  
Keyword(s):  
Gene Expression ◽  
Sickle Cell ◽  
Sickle Cell Anemia ◽  
Plasma Levels ◽  
Conflicts Of Interest ◽  
Organ Damage ◽  
Northeastern Brazil ◽  
Leg Ulcers ◽  
Increased Risk ◽  
History Of

Abstract Abstract 4835 Background: Sickle cell anemia (SCA) is characterized by a chronic inflammatory state in which oxidative stress, particularly in the endothelium, exerts a strong influence on the pathogenesis of vaso-occlusion and may be implicated in patients' clinical heterogeneity and survival. It has been suggested that the cytokine production profile of cells involved in the immune response may vary among patients with SCA. Leg ulcers (LU) represent a severe complication in these patients, and this condition has been associated with specific end-organ damage and an increase in morbidity and mortality. Recent studies have shown that venous obstruction, endothelial dysfunction, coagulopathy and infections are implicated in the complex pathogenesis of LU. Aims: To determine IL-1β, IL-6 and IL-8 plasma levels and gene expression rates as well as hematological and coagulation parameters and correlate these with the history of LU in adult SCA patients followed up at HEMOPE, in the state of Pernambuco, northeastern Brazil. Methods: Peripheral blood samples from 92 patients (median age 27 years; 42 female; 52 male; all Afro-descendants) in the steady state who had been diagnosed with SCA (HbSS), had not received a transfusion and were not using hydroxyurea were analyzed. Plasma levels of cytokines were determined by ELISA, and the gene expression rates by qRT-PCR. The patients' clinical and laboratorial characteristics were obtained from their medical charts. Statistical analysis was performed using the SAS System for Windows version 9.2. Results: Median age was higher in patients with a history of LU than in those without a history (33.1 vs. 28.4; p = 0.04). Although no statistically significant (p = 0.5) differences in IL-8 gene expression rates were observed, IL-8 plasma levels were significantly higher in patients with a history of LU than in patients without a history (23.8 vs. 7.7; p = 0.01) (Figure 1). Thus, patients with high levels of IL-8 had an increased risk for the occurrence of leg ulcers (OR = 1.01; 95% CI = 1.00–1.02). The ROC curve showed that IL-8 levels higher than 8.55 pg/mL could indicate the presence of LU (accuracy = 71.6%; sensitivity = 73.7%; specificity = 68.5%). The laboratory tests revealed reticulocyte counts and activated partial thromboplastin time (aPTT) ratios (R) that were significantly higher in patients with a history of LU than in those without a history (11.8 vs. 8.4, p = 0.01; 1.1 vs. 0.9, p = 0.04, respectively). Both the higher reticulocyte counts and R values were associated with increased risk for the occurrence of leg ulcers in these patients (OR = 1.12, 95% CI = 1.02 – 1.20; OR = 24.28, 95% CI = 1.20 – 486.09, respectively). Conclusion: In this study, patients who had had LU at some time in their lives showed significantly higher IL-8 levels, reticulocyte counts and R values than patients who had never had LU. Our results therefore suggest a relationship between the parameters described above and LU in patients with SCA. These parameters could perhaps be used, in association with different genetic modulators that may contribute to different clinical phenotypes observed in this disease, as markers of this clinical manifestation of SCA or of a propensity to develop it. Financial Support: CAPES (Brazil)/FAPESP/CNPq/INCTS Disclosures: No relevant conflicts of interest to declare.

scholarly journals Is there a role for selective vasodilation in the management of sickle cell disease?

Blood ◽  
1988 ◽  
Vol 71 (3) ◽  
pp. 597-602
Author(s):  
GP Rodgers ◽  
MS Roy ◽  
CT Noguchi ◽  
AN Schechter
Keyword(s):  
Blood Flow ◽  
Steady State ◽  
Sickle Cell Disease ◽  
Sickle Cell ◽  
Sickle Cell Anemia ◽  
Microvascular Obstruction ◽  
Controlled Study ◽  
Control Group ◽  
Cell Disease ◽  
Retinal Arteriolar

To test the hypothesis that microvascular obstruction to blood flow at the level of the arteriole may be significant in individuals with sickle cell anemia, the ophthalmologic effects of orally administered nifedipine were monitored in 11 steady-state patients. Three patients with evidence of acute peripheral retinal arteriolar occlusion displayed a prompt reperfusion of the involved segment. Two other patients showed fading of retroequatorial red retinal lesions. Color vision performance was improved in six of the nine patients tested. The majority of patients also demonstrated a significant decrease in the amount of blanching of the conjunctiva which reflects improved blood flow to this frequently involved area. Such improvements were not observable in a control group of untreated stable sickle cell subjects. These findings support the hypothesis that inappropriate vasoconstriction or frank vasospasm may be a significant factor in the pathogenesis of the microvascular lesions of sickle cell disease and, further, that selective microvascular entrapment inhibition may offer an additional strategy to the management of this disorder. We believe a larger, placebo-controlled study with nifedipine and similar agents is warranted.

scholarly journals Doppler velocimetry of the orbital arteries in patients with sickle cell anemia: relationship with biomarkers of hemolysis

2017 ◽  
Vol 50 (2) ◽  
pp. 103-108 ◽  
Author(s):  
Thiago de Oliveira Ferrão ◽  
Paulo Ricardo Martins-Filho ◽  
Cleverton Aragão ◽  
Marlyson Santana ◽  
Allan Nascimento ◽  
...  
Keyword(s):  
Steady State ◽  
Vascular Resistance ◽  
Sickle Cell ◽  
Sickle Cell Anemia ◽  
Ophthalmic Artery ◽  
Central Retinal Artery ◽  
Control Group ◽  
Doppler Velocimetry ◽  
Retinal Artery ◽  
Flow Velocities

Abstract Objective: To investigate orbital vascular resistance by Doppler velocimetry in patients with steady-state sickle cell anemia, as well as to characterize its relationship with biomarkers of hemolysis. Materials and Methods: This was a cross-sectional study of two groups: 71 outpatients with sickle cell anemia; and 32 age- and gender- matched, healthy subjects (control group). All participants underwent Doppler velocimetry of the orbital arteries and laboratory tests. Results: All biochemical laboratory markers were abnormal in the sickle cell anemia patients (p < 0.0001 vs. controls). In the patient group, Doppler velocimetry revealed increased flow velocities in the ophthalmic artery and reduced flow velocities in the central retinal artery, as well as high values for the resistance index (RI) and pulsatility index (PI) in both arteries (p < 0.0001 vs. controls). Biomarkers of hemolysis were found to correlate significantly with the RI and PI indices. In the ophthalmic artery, the reticulocyte count showed a moderate direct correlation with RI and with PI. In the central retinal artery, hemoglobin showed a strong inverse correlation with RI and with PI. Conclusion: Orbital vascular resistance, as evaluated by Doppler velocimetry, is elevated in patients with steady-state sickle cell anemia and shows a significant correlation with biomarkers of hemolysis.

Sign in / Sign up

Export Citation Format

Share Document