Endothelial activation and inflammation biomarkers in children and adolescents with sickle cell disease

Whole-blood transcriptome analysis reveals distinct gene expression signatures in paediatric patients with sickle cell anaemia before and after exercise

Sickle cell anaemia (SCA) patients display elevated levels of circulating pro-inflammatory cytokines and endothelial activation markers compared to healthy peers. The impact of exercise on the pro-inflammatory state in SCA remains unclear. This study aimed to characterize the whole-blood transcriptome profile in response to an acute bout of exercise in paediatric SCA patients. Twenty-three SCA participants (13 ± 3 years, 52% girls) and 17 healthy controls (14 ± 3 years, 29% girls) performed eight 2-min bouts of cycle ergometry interspersed with 1-min rest intervals. Whole-blood transcriptome profile (RNA-seq) was performed before and after exercise. At baseline, gene pathways associated with gas transport in erythrocytes were up-regulated in SCA patients compared to controls. Following exercise, gene pathways associated with innate immunity were altered in both groups. Interaction analyses revealed 160 annotated genes (101 up- and 59 down-regulated) that differentially altered by exercise in SCA patients. Moreover, genes that exhibited a blunted response to exercise in SCA patients were enriched in the IL-17 signalling pathway, suggesting an impaired innate immune response to exercise. This data will contribute to the development of evidence-based exercise prescription guidelines for this patient population.

Differential expression of adhesion molecules in sickle cell anemia and gut microbiome effect

Sickle cell anemia (SCA) causes a long-standing vascular inflammation state, leading to endothelial dysfunction and chronic overexpression of several adhesion molecules, which contributes to acute and constant vaso-occlusive (VOC) episodes. It has been demonstrated that hydroxyurea (HU) can reduce VOC events, organ damage, blood transfusions, and even the adhesion properties to endothelial cells of SCA subjects. Due to VOC episodes, these patients are also more susceptible to recurrent bacterial translocation and dysbiosis. Given this, our study aimed to uncover the interplay between adhesion molecules, gut microbiome, and hydroxyurea in a population of Angolan SCA children. Serum and fecal samples were obtained before and after HU treatment in 35 children. After HU, four of these adhesion molecules were significantly reduced: sE-selectin (p = 0.002), ADAMTS13 (p = 0.023), sICAM-1 (p = 0.003), and sVCAM-1 (p = 0.018). A positive correlation was observed between the number of neutrophils and sICAM-1, platelets, and sP-selectin, and also between leukocytes, sICAM-1, and sVCAM-1. Most taxa showing a significant correlation mainly belonged to the Clostridiales order. Specifically, from the Clostridium genera, the groups g19, g21, and g34 were all negatively correlated with HbF levels; g19, g21, and g24 positively correlated with leukocytes; g19 positively with neutrophils and sVCAM-1; and g34 positively with E- and P-selectin. Serratia, an opportunistic pathogen, was positively correlated with sE-selectin and sICAM-1 levels. Additionally, a negative correlation was observed between sP-selectin and Bifidobacterium. Research studies in this area could improve our understanding and contribute to finding new prognostic biomarkers to guarantee precise SCA patient stratification and predict severe complications.

VWF-ADAMTS13 axis dysfunction in children with sickle cell disease treated with hydroxycarbamide vs blood transfusion

Previous studies have reported elevated von Willebrand factor (VWF) levels in patients with sickle cell disease (SCD) and demonstrated a key role for the VWF-ADAMTS13 axis in the pathobiology of SCD vaso-occlusion. Although blood transfusion is the gold standard for stroke prevention in SCD, the biological mechanisms underpinning its improved efficacy compared with hydroxycarbamide are not fully understood. We hypothesized that the improved efficacy of blood transfusion might relate to differences in VWF-ADAMTS13 axis dysfunction. In total, 180 children with a confirmed diagnosis of SCD (hemoglobin SS) on hydroxycarbamide (n = 96) or blood transfusion (n = 84) were included. Despite disease-modifying treatment, plasma VWF and VWF propeptide were elevated in a significant proportion of children with SCD (33% and 47%, respectively). Crucially, all VWF parameters were significantly higher in the hydroxycarbamide compared with the blood transfusion cohort (P < .05). Additionally, increased levels of other Weibel-Palade body-stored proteins, including factor VIII (FVIII), angiopoietin-2, and osteoprotegerin were observed, indicated ongoing endothelial cell activation. Children treated with hydroxycarbamide also had higher FVIII activity and enhanced thrombin generation compared with those in the blood transfusion cohort (P < .001). Finally, hemolysis markers strongly correlated with VWF levels (P < .001) and were significantly reduced in the blood transfusion cohort (P < .001). Cumulatively, to our knowledge, our findings demonstrate for the first time that despite treatment, ongoing dysfunction of the VWF-ADAMTS13 axis is present in a significant subgroup of pediatric patients with SCD, especially those treated with hydroxycarbamide.

Potential inflammatory targets in the integrative health care of patients with sickle cell disease

Inflammation plays an integral role in the complications of sickle cell disease (SCD), which can lead to vaso-occlusive crisis and extreme pain. SCD is accompanied by numerous complications, including cardiovascular disease, cognitive decline and endothelial dysfunction, contributing to mortality. As disease severity increases with age, the present study aimed to assess if age is also correlated with a definite pattern of progression of the two inflammatory markers, high-sensitivity C-reactive protein (hsCRP) and total homocysteine (tHCY). The findings of the present study could lead to an improved understanding of the threshold levels of these inflammatory markers and timely interventions to delay complications. In an observational study, levels of hsCRP and tHCY were analyzed in 70 patients (35 male and 35 female patients) with SCD aged between 5 and 16 years. hsCRP levels were in the high-risk range in 64.29% (n=45) of all male and female patients. A sex-wise distribution showed that, of the 35 male patients, 74.28% (n=26) were in the high-risk range, and of the 35 female patients, 54.28% (n=19) were in the high-risk range. An age-wise distribution showed that of the 41 patients in the 5-10-years age group, 70.73% (n=29), were in the high-risk range. In comparison, of the 29 patients in the 11-16-years age group, 55.17% (n=16) were in the high-risk range. tHCY levels were observed to be in the normal range in 98.57% (n=69) of all children, as compared with 1.43% (n=1) in the high-risk range. Furthermore, a sex-wise distribution showed that female patients in the high-risk group of hsCRP had higher concentrations of tHCY as compared with the male patients in that risk group. An age-wise distribution of hsCRP concentration also showed that the risk of CVD in patients in the 11-16-years age group was higher with increased concentrations of tHCY. A weak negative correlation was observed between age and hsCRP concentrations (r-value=-0.280; P=0.026) and a weak positive correlation was detected between tHCY and age (r-value=0.259; P=0.036). In conclusion, the results of the present study indicated that higher levels of hsCRP could be a useful marker in children with SCD, and levels of tHCY may be an adjunct marker as the disease progresses with age.

Longitudinal assessment of adhesion to vascular cell adhesion molecule-1 at steady state and during vaso-occlusive crises in sickle cell disease

Sickle cell disease (SCD) is characterized by frequent and unpredictable vaso‐occlusive crises (VOCs). Sickle erythrocytes (SSRBCs) contribute to VOCs by participating in a series of adhesive events with blood cells and the vascular endothelium. Adhesion assays have been used to evaluate the relationship between SSRBC adhesion and SCD severity. We developed a standardized, clinical flow adhesion assay of whole blood to vascular cell adhesion molecule (FA‐WB‐VCAM). The objective of this study was to assess the variability and clinical predictive value of FA‐WB‐VCAM in a six‐month longitudinal, observational study (ELIPSIS) in SCD subjects during at‐home, steady‐state and self‐reported VOCs, and following VOC resolution. We observed a strong relationship between FA‐WB‐VCAM and SCD severity. Adhesion indices were significantly lower in SCD subjects on hydroxycarbamide and increased during VOCs; at‐home VOCs had significantly higher FA‐WB‐VCAM than steady‐state and contact VOCs. SCD subjects with a high frequency of self‐reported VOCs had a pro‐adhesive phenotype at steady state and were stratified into a high‐adhesive phenotype cohort; two years prospectively we observed a higher frequency of VOCs in the high‐adhesion cohort. This study supports stratifying SCD subjects based on steady‐state FA‐WB‐VCAM and suggests that FA‐WB‐VCAM may be a plausible surrogate end‐point for SCD severity.

Acute Chest Syndrome in Sickle Cell Disease: Clinical Presentation and Outcomes. The Experience of a Single Thalassemia and Sickle Cell Unit in a University Hospital

Acute chest syndrome (ACS) is a common cause of death for sickle cell disease patients. This syndrome is defined as: respiratory symptoms, new X-ray findings developed and/or fever; ACS requires prompt treatment to avoid clinical deterioration and death in adults with sickle cell disease. Sixteen episodes of acute chest syndrome were studied in 16 adults with sickle cell disease. The clinical and radiological findings, treatment, response and outcome of the episode were evaluated respectively. The patient's past history and comorbidities were taken into account in the outcome and days of hospitalization. Fourteen patients recovered with no sequelae; one patient who required mechanical ventilation also recovered; one patient died due to pulmonary emboli. The mean hospitalization days were 7.43.

Hyperuricemia, Elevated Body Mass Index, Female Sex, and Albuminuria Increase the Probability of Elevated High-Sensitivity C-Reactive Protein: Results From the National Health and Nutrition Examination Survey 2015-2018

Importance: High uric acid (UA) is hypothesized to worsen kidney and cardiovascular disease morbidity via activation of systemic inflammation. Clinical trials of UA modification report reduction of the inflammatory marker high sensitivity C-reactive protein (hs-CRP) as an outcome measure, but studies have not demonstrated that hyperuricemia independently increases hs-CRP when adjusted for important confounders such as body mass index (BMI), sex, and age. Objective: To identify clinical risk factors for elevated hs-CRP, including but not limited to hyperuricemia, through a cross-sectional analysis of the National Health and Nutrition Examination Survey (NHANES) 2015-2018. Results: In the final multivariate logistic regression model, the exposure with the strongest effect on the odds of elevated hs-CRP was BMI in the fourth quartile, OR = 13.1 (95% CI 6.25-27.42), followed by female sex (OR = 4.9, 95% CI 2.92-8.34), hyperuricemia (OR = 2.2, 95% CI 1.36-3.45), urine albumin creatinine ratio (ACR; OR = 1.5, 95% CI 1.09-2.18), poor overall health (OR = 1.4, 95% CI 1.18-1.58), and interactions between hyperuricemia and sex (OR = 1.4, 95% CI 1.05-1.83), and between BMI and sex (OR = 1.2, 95% CI 1.03-1.47). Notably, chronic kidney disease (CKD) and CKD surrogates were not associated with hs-CRP despite urine ACR maintaining a significant independent effect. Conclusions: In this national population-based study, we demonstrated that hyperuricemia significantly increases the odds of elevated hs-CRP, independent from BMI, female sex, urine ACR, and overall health status. Further study is recommended to better understand the sex difference in this association and the role of albuminuria, but not CKD, in systemic inflammation.

The Sickle Cell Pro-Inflammatory Response to Interval Testing Study (SPRINTS) in children and young adults with sickle cell anemia - Study design and methodological strategies

The impact of sickle cell anemia (SCA) and its complications on physical functioning and cardiopulmonary/aerobic fitness in affected individuals is significant. Although limited data support the safety of maximal cardiopulmonary exercise testing (CPET) for children and adults with SCA, the safety of submaximal moderate and high intensity, and longer duration, exercise in this population is not clear. The Sickle Cell Pro-Inflammatory Response to Interval Testing Study (SPRINTS) is a multicenter, randomized, prospective trial. SPRINTS leverages unique collaborations between investigators in pediatric hematology and exercise science to evaluate the impact of exercise intensity on the acute phase inflammatory response to exercise and changes in airway dynamics in children and young adults with SCA. Here we describe the study design and methodological strategies employed in SPRINTS, including an exercise challenge that mimics real-life patterns of childhood physical activity, characterized by multiple moderate and high intensity brief bouts of exercise interspersed with rest periods. Primary outcomes comprise pre- and post-exercise biomarkers of inflammation and endothelial dysfunction and spirometry. Secondary outcomes include assessment of physical activity and functioning, genomic studies and near-infrared spectroscopy measurements to assess tissue oxygenation status during exercise. SPRINTS aims to enroll 70 subjects with SCA and 70 matched, healthy controls. We anticipate that data from SPRINTS will address gaps in our understanding of exercise responses and safety in SCA and support the future development of evidence-based, exercise prescription guidelines in this population.

Characteristics and outcomes of osteomyelitis in children with sickle cell disease: A 10-year single-center experience

BACKGROUND

Patients with sickle cell disease (SCD) are at increased risk for osteomyelitis (OM). Diagnosis of OM in SCD is challenging as the clinical presentation is similar to a vasoocclusive crisis (VOC) with no diagnostic gold standard. We report characteristics and outcomes of OM in SCD patients treated at our center over 10-year period.

DESIGN/METHOD

We conducted a retrospective analysis of patients with SCD who were treated for OM at our center over a 10-year period (2006-2016). Cases were identified utilizing radiology data mining software. Radiology reports and medical charts of potential OM cases were reviewed.

RESULTS

Twenty-eight children with SCD were treated for OM at our institution. Patients treated for OM were largely similar to patients treated for a VOC. However, patients treated for OM had significantly higher C-reactive protein (10 mg/dL vs 5.58 mg/dL, P = 0.03) and erythrocyte sedimentation rate (60 mm/h vs 47 mm/h, P = 0.02). Magnetic resonance imaging (MRI) findings were consistent with OM in 18 (64%) patients and indeterminate in the remaining. Based on clinical, laboratory, and radiological findings, the diagnosis of OM was considered confirmed in 3 patients, probable in 6 patients, and presumed in 19 patients. Nontyphoidal Salmonella was isolated from cultures in 9 (32%) patients, while no organism was identified in 19 (67%) patients. All patients were treated with antibiotics. Six patients (21%) required surgical interventions.

CONCLUSIONS

OM continues to pose diagnostic challenges. Most patients are treated for OM without definitive confirmation. Nontyphoidal Salmonella was the only organism identified in our cohort.

Sickle Cell Anemia Patients Display an Intricate Cellular and Serum Biomarker Network Highlighted by TCD4+CD69+ Lymphocytes, IL-17/MIP-1β, IL-12/VEGF, and IL-10/IP-10 Axis

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-1α, MIP-1β, 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-1α, MIP-1β, 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-1β 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.

Role of some members of chemokine/cytokine network in the pathogenesis of thalassemia and sickle cell hemoglobinopathies: a mini review

The word of hemoglobinopathy is described for an array of disorders that affecting hemoglobin (Hb) functions. Hb is a molecule with 68 kDa molecular weight, serving as oxygen carrying metalloprotein. Hemoglobinopathy includes a wide range of Hb structural deficits varying from thalassemia to sickle cell disease. Cyto-chemokine network members are pivotally involved in the pathogenesis of hemoglobinopathies, however, the exact role of these mediators in the development of these disorders yet to be well addressed. Cytokines and chemokines are generated by inflamed endothelial cells that promote the expression of their respected receptors and further activate NF-κβ, recruit red blood cells (RBCs) and white blood cells (WBCs) toward the inflamed endothelium. Therefore, due to critical roles played by the cyto-chemokine network in several aspects of hemoglobinopathies pathophysiology including apoptosis of endothelial cells, RBC, WBC and etc.…, in the present review, we focused on the critical parts played by this network in the pathogenesis of hemoglobinopathies.

PKC-Mediated Endothelin-1 Expression in Endothelial Cell Promotes Macrophage Activation in Atherogenesis

BACKGROUND

Atherosclerosis is a chronic inflammatory disease triggered by endothelial dysfunction and exaggerated by macrophage infiltration. Although endothelin-1 (ET-1) plays an important role in vascular inflammation and reactive oxygen species production, the individual effect of ET-1 in atherogenesis remains unclear.

METHODS AND RESULTS

ET-1 expression was increased in mouse atherosclerotic plaques and human umbilical vein endothelial cells (HUVECs) administrated by oxidized low-density lipoprotein stimulation. Moreover, the immunofluorescence co-staining showed upregulated ET-1 expression in endothelial cells. Real-time polymerase chain reaction demonstrated that ET-1 overexpression promoted adhesion molecules and chemokines secretion in HUVECs. Following this intervention, the migration of macrophages and the pro-inflammatory cytokines were increased. More importantly, the endothelial dysfunction regulated by ET-1 and subsequently the effect on macrophage activation were mediated by ETA receptor and largely reversed by protein kinase C (PKC) inhibitor. Eight-week-old male ApoE-/- mice and eET-1/ApoE-/- mice were fed with high-fat diet for 12 weeks. eET-1/ApoE-/- significantly increased atherosclerotic lesions in the whole aorta and aortic sinus, which accompanied by the induction of inflammatory cytokines and macrophages infiltration.

CONCLUSIONS

ET-1 accelerates atherogenesis by promoting adhesion molecules and chemokines, as well as subsequent macrophage activation. Collected, these evidence suggest that ET-1 might be a potential target for the treatment of atherogenesis.

Selecting red blood cell units to perform RBCX in patients with sickle cell disease

Red blood cell exchange (RBCX) is a standard option for treating or preventing complications in patients with sickle cell disease (SCD). According to the patient's blood volume, the amounts of red blood cells (RBC) to be exchanged and the practices of the apheresis and clinical teams, such treatment requires numerous red blood cell units (RBCUs) (3-15 RBCUs per procedure). To perform RBCXs safely and prevent the risk of alloimmunization, appropriate RBCUs must be selected and transfused to replace the sickled RBCs. Understanding of alloimmunization in patients with SCD strengthened the development of recommendations for preventing the risk of alloimmunization. This review describes the alloimmunization risk, the methods used to decrease the risk, and our own experience.

Clinical relevance of pulmonary vasculature involvement in sickle cell disease

Pulmonary complications are frequent in patients with sickle cell disease (SCD), but few studies have described lung pathology in SCD. We studied the lung tissue of 30 deceased SCD patients (1994-2012). Demographics, genotype, clinical characteristics, cause of death and associated conditions are presented. We quantified the presence of pulmonary arterial changes, thrombosis and venous thickening. Alveolar capillary abnormalities were demonstrated using CD34 expression and confocal microscopy. Autopsy and echocardiography reports were reviewed to classify heart abnormalities. Tissue expression of markers of endothelial activation (vascular cell adhesion molecule 1, intercellular adhesion molecule 1 and vascular endothelial growth factor) was quantified in pulmonary vessels. Median age was 33 years; genotype was SS in 19, SC in 7 and Sβ in 4, and there were 18 males. Hypertensive arterial changes were present in 76% of the patients, recent thrombosis in 80% and old thrombosis in 43%. Venous thickening was present in 23% and pulmonary capillary haemangiomatosis foci in 87%. Ten percent of the patients presented right ventricular hypertrophy. There was no increased expression of endothelial activation markers when compared to controls. SCD affects the whole pulmonary vascular tree and reflects the multiple burden on lung vasculature imposed by the disease upon time.

Early initiation of inhaled corticosteroids does not decrease acute chest syndrome morbidity in pediatric patients with sickle cell disease

Acute chest syndrome (ACS) is a leading cause of mortality in patients with sickle cell disease (SCD). Systemic corticosteroids decrease ACS severity, but the risk of readmission for vaso-occlusive crises (VOC) has limited their use. The efficacy of inhaled corticosteroids (ICS) as a safer alternative is currently unknown. An observational, historic cohort study compared patients with SCD with ACS who received ICS at admission (ICS) to those who did not (non-ICS). Outcome measures included rates of transfusion, oxygen requirement, BiPAP initiation, PICU transfer, intubation, readmission, hospital cost, and length of stay. One hundred twenty patients with SCD (55 non-ICS, 65 ICS) were included. A significantly higher proportion of the non-ICS group had bilateral infiltrates, but fewer had asthma. More children in the ICS group had BiPAP initiated, however transfer to the PICU, intubation, transfusion rates, oxygen requirement, hospital cost, length of stay, and readmission rates did not differ between groups. Regression analysis did not reveal any differences in outcomes, nor were outcomes changed when patients were separated based on the presence or absence of asthma. In this observational cohort study, ICS did not demonstrate a significant reduction in ACS morbidity, though ICS use should be studied in a prospective manner.

Simvastatin reduces vaso-occlusive pain in sickle cell anaemia: a pilot efficacy trial

Sickle cell anaemia (SCA) is a progressive vascular disease characterized by episodic vaso-occlusive pain. Despite the broad impact of inflammation on acute and chronic clinical manifestations of SCA, no directed anti-inflammatory therapies currently exist. Statins are cholesterol-lowering agents shown to confer protection from vascular injury by suppressing inflammation. We previously documented a reduction in soluble biomarkers of inflammation in patients with sickle cell disease treated with simvastatin. To determine the potential clinical efficacy of simvastatin, we treated 19 SCA patients with single daily dose simvastatin for 3 months and assessed changes from baseline in the frequency and intensity of diary-reported pain and levels of circulating nitric oxide metabolites (NOx), high sensitivity C-reactive protein (hs-CRP), vascular cell adhesion molecule 1 (VCAM-1), intercellular adhesion molecule 1 (ICAM-1), ICAM-3, E-selectin, and vascular endothelial growth factor (VEGF). Treatment with simvastatin resulted in a significant reduction in the frequency of pain (P = 0·0003), oral analgesic use (P = 0·003) and circulating hs-CRP (P = 0·003), soluble (s)E-selectin (P = 0·01), sICAM-1 (P = 0·02), sICAM-3 (P = 0·02) and sVEGF (P = 0·01). Simvastatin had no effect on pain intensity or levels of NOx, sP-selectin and sVCAM-1. The observed reductions in pain rate and markers of inflammation were greatest in subjects receiving hydroxycarbamide (HC), suggesting a synergistic effect of simvastatin. These results provide preliminary clinical data to support a larger trial of simvastatin in SCA.

Endothelin-1 contributes to the progression of renal injury in sickle cell disease via reactive oxygen species

BACKGROUND AND PURPOSE

Endothelin-1 (ET-1) is increased in patients with sickle cell disease and may contribute to the development of sickle cell nephropathy. The current study was designed to determine whether ET-1 acting via the ETA receptor contributes to renal injury in a mouse model of sickle cell disease.

EXPERIMENTAL APPROACH

Adult, humanized HbSS (homozygous for sickle Hb) mice had increased ET-1 mRNA expression in both the cortex and the glomeruli compared with mice heterozygous for sickle and Hb A (HbAS controls). In the renal cortex, ETA receptor mRNA expression was also elevated in HbSS (sickle) mice although ETB receptor mRNA expression was unchanged. Ligand binding assays confirmed that sickle mice had increased ETA receptors in the renal vascular tissue when compared with control mice.

KEY RESULTS

In response to PKC stimulation, reactive oxygen species production by isolated glomeruli from HbSS sickle mice was increased compared with that from HbSA controls, an effect that was prevented by 1 week in vivo treatment with the selective ETA antagonist, ABT-627. Protein and nephrin excretion were both elevated in sickle mice, effects that were also significantly attenuated by ABT-627. Finally, ETA receptor antagonism caused a significant reduction in mRNA expression of NADPH oxidase subunits, which may contribute to nephropathy in sickle cell disease.

CONCLUSIONS AND IMPLICATIONS

These data support a novel role for ET-1 in the progression of sickle nephropathy, specifically via the ETA receptor, and suggest a potential role for ETA receptor antagonism in a treatment strategy.

Alteration of lymphocyte phenotype and function in sickle cell anemia: Implications for vaccine responses

Individuals with sickle cell anemia (SCA) have increased susceptibility to infections, secondary to impairment of immune function. Besides the described dysfunction in innate immunity, including impaired opsonization and phagocytosis of bacteria, evidence of dysfunction of T and B lymphocytes in SCA has also been reported. This includes reduction in the proportion of circulating CD4+ and CD8+ T cells, reduction of CD4+ helper: CD8+ suppressor T cell ratio, aberrant activation and dysfunction of regulatory T cells (Treg ), skewing of CD4+ T cells towards Th2 response and loss of IgM-secreting CD27 + IgM(high) IgD(low) memory B cells. These changes occur on the background of immune activation characterized by predominance of memory CD4+ T cell phenotypes, increased Th17 signaling and elevated levels of C-reactive protein and pro-inflammatory cytokines IL-6 and TNF-α, which may affect the immunogenicity and protective efficacy of vaccines available to prevent infections in SCA. Thus, in order to optimize the use of vaccines in SCA, a thorough understanding of T and B lymphocyte functions and vaccine reactivity among individuals with SCA is needed. Studies should be encouraged of different SCA populations, including sub-Saharan Africa where the burden of SCA is highest. This article summarizes our current understanding of lymphocyte biology in SCA, and highlights areas that warrant future research. Am. J. Hematol. 91:938-946, 2016. © 2016 Wiley Periodicals, Inc.

Reduced cerebrovascular reserve is regionally associated with cortical thickness reductions in children with sickle cell disease

Sickle cell disease (SCD) is a genetic disorder which adversely affects cerebrovascular health. Previous studies have demonstrated regional cortical thinning in SCD. However, the reason behind regional reductions in cortical thickness remains unclear. Therefore, we aimed to explore the possible link between the state of cerebrovascular health and cortical thickness. In this study, we obtained magnetic resonance (MR) based measures of cerebrovascular reactivity (CVR), a measure of vascular health, and cortical thickness in SCD patients (N=60) and controls of similar age and similar gender ratio (N=27). The group comparison analysis revealed significant regionally specific reductions in CVR and cortical thickness in the SCD group compared to the controls. In addition, a regional association analysis was performed between CVR and cortical thickness in the SCD group which revealed a significant regional association in several brain regions with the highest strength of association observed in the left cuneus, right post central gyrus and the right temporal pole. The regional association analysis revealed that significant associations were found in brain regions with high metabolic activity (anterior cingulate, posterior cingulate, occipital gyrus, precuneus) thus demonstrating that these regions could be most vulnerable to structural damage under hypoxic conditions.

Therapeutic potential of endothelin receptor antagonism in kidney disease

Our growing understanding of the role of the endothelin (ET) system in renal physiology and pathophysiology is from emerging studies of renal disease in animal models and humans. ET receptor antagonists reduce blood pressure and proteinuria in chronic kidney disease and cause regression of renal injury in animals. However, the therapeutic potential of ET receptor antagonism has not been fully explored and clinical studies have been largely limited to patients with diabetic nephropathy. There remains a need for more work in nondiabetic chronic kidney disease, end-stage renal disease (patients requiring maintenance dialysis and those with a functioning kidney transplant), ischemia reperfusion injury, and sickle cell disease. The current review summarizes the most recent advances in both preclinical and clinical studies of ET receptor antagonists in the field of kidney disease.

Coronary artery ectasia in atherosclerotic coronary artery disease, inflammatory disorders, and sickle cell disease

Coronary artery ectasia (CAE) or aneurysm is usually defined as dilation ≥1.5-fold the normal vessel diameter. It has an incidence of 1.4-5.3% and is associated with a wide variety of etiologies-mainly congenital, atherosclerotic, and inflammatory ones. CAE is very common in sickle cell disease, and possibly sickle cell trait, with an incidence of 17.7%. It is likely related to the inflammatory process associated with hemoglobin S. Prognosis depends mainly on the underlying etiology. Atherosclerotic CAE does not carry additional risks compared to atherosclerotic coronary artery disease (ACAD) without ectasia. However, isolated CAE in the absence of ACAD carries an increased risk of myocardial infarction (MI) due to vasospasm, slower coronary blood flow, and thrombosis, typically within the dilated segments. Due to lack of studies and guidelines, management recommendations are based on personal experiences. Therapy should be tailored to each individual case after assessment of severity, history of complications, underlying etiology, and comorbidities. Treatment of underlying condition and avoidance of exacerbating factors are essential. Medical therapy in general may include antiplatelets, β-blockers, angiotensin-converting enzyme inhibitors statins, and dihydropyridine calcium channel blockers. In severe CAE or history of MI, the addition of anticoagulation therapy after assessing bleeding risk may be warranted. In acute MI, the large thrombus burden in the dilated segment makes the percutaneous approach very challenging. Aspiration attempts can result in distal thromboembolization. Survival is better in bypass grafting than with medical therapy. Nonetheless, bypass grafting does not improve survival in atherosclerotic CAE. Depending on the physical characteristics of aneurysm, different surgical approaches can be sought; however, the ideal one is unclear.

The five key things you need to know to manage adult patients with sickle cell disease

The lack of a strong evidence base to guide the management of adults with sickle cell disease (SCD) makes it difficult for patients to receive high quality care outside of specialty centers. As there is a dearth of providers with sickle cell expertise, the purpose of this article is to identify some of the key things every provider who manages the care of adults with SCD should know. Managing adults with SCD requires excellent clinical skills, as it can affect every organ and cause life-threatening complications but it also requires a willingness to manage patients who often have psychosocial issues that are complex and impact care and care delivery in very significant ways. We have chosen topics for which there is a limited evidence base but which have significant clinical consequences if left unrecognized or poorly managed. The topics that will be addressed include chronic pain, neurocognitive dysfunction, renal disease, venous thromboembolism, and avoiding the inappropriate use of red cell transfusions.

The acute phase inflammatory response to maximal exercise testing in children and young adults with sickle cell anaemia

Although individuals with sickle cell anaemia (SCA) have elevated baseline inflammation and endothelial activation, the acute phase response to maximal exercise has not been evaluated among children with SCA. We measured the acute phase response to maximal exercise testing for soluble vascular cell adhesion molecule (sVCAM) as well as interleukin 6 (IL6), total white blood cell (WBC) count, C-reactive protein (CRP) and D-dimer in a cohort of children with SCA and matched controls at baseline, immediately after, and 30, 60 and 120 min following exercise. Despite higher baseline levels of all biomarkers except CRP, the acute phase response from baseline to immediately after exercise was significantly greater in subjects versus controls for CRP (2·1 vs. 0·2 mg/l, P = 0·02) and D-dimer (160 vs. 10 μg/l, P < 0·01) only. Similar between-group trends were observed over time for all biomarkers, including sVCAM, IL6, total WBC, CRP and D-dimer. Lower fitness, defined by peak oxygen consumption (VO2 ), was independently associated with greater acute phase responses to exercise for sVCAM. Our results suggest maximal exercise may not be associated with any greater escalation of endothelial activation or inflammation in SCA and provide preliminary biomarker evidence for the safety of brief, high-intensity physical exertion in children with SCA.

Correlation between the Lactate Dehydrogenase Levels with Laboratory Variables in the Clinical Severity of Sickle Cell Anemia in Congolese Patients

Background

Sickle cell anemia is an inflammatory disease and is characterized by chronic hemolysis. We sought to evaluate the association of lactate dehydrogenase levels with specific clinical phenotypes and laboratory variables in patients with sickle cell anemia.

Methods

The present cross-sectional study was conducted in Sickle Cell Centre of Yolo in Kinshasa, the Democratic Republic of Congo. Two hundred and eleven patients with Sickle Cell Anemia in steady state were recruited. Seventy-four participants with normal Hb (Hb-AA) were selected as a control group.

Results

The average rates of hemoglobin, hematocrit, and red blood cells tended to be significantly lower in subjects with Hb-SS (p<0.001). The average rates of white blood cells, platelets, reticulocytes and serum LDH were significantly higher in subjects with Hb-SS (p<0.001). The average rates of Hb, HbF, hematocrit and red blood cells of Hb-SS patients with asymptomatic clinical phenotype were significantly higher than those of the two other phenotypes. However, the average rates of white blood cells, platelets, reticulocytes, and LDH of Hb-SS patients with the severe clinical phenotype are higher than those of two other clinical phenotypes. Significant correlations were observed between Hb and white blood cell in severe clinical phenotype (r3 = -0.37 *) between Hb and red blood cells in the three phenotypes (r1 = 0.69 * r2 * = 0.69, r3 = 0.83 *), and finally between Hb and reticulocytes in the asymptomatic clinical phenotype and severe clinical phenotype (r1 = -0.50 * r3 = 0.45 *). A significant increase in LDH was observed in patients with leg ulcer, cholelithiasis and aseptic necrosis of the femoral head.

Conclusion

The increase in serum LDH is accompanied by changes in hematological parameters. In our midst, serum LDH may be considered as an indicator of the severity of the disease.

Dietary ω-3 fatty acids protect against vasculopathy in a transgenic mouse model of sickle cell disease

The anemia of sickle cell disease is associated with a severe inflammatory vasculopathy and endothelial dysfunction, which leads to painful and life-threatening clinical complications. Growing evidence supports the anti-inflammatory properties of ω-3 fatty acids in clinical models of endothelial dysfunction. Promising but limited studies show potential therapeutic effects of ω-3 fatty acid supplementation in sickle cell disease. Here, we treated humanized healthy and sickle cell mice for 6 weeks with ω-3 fatty acid diet (fish-oil diet). We found that a ω-3 fatty acid diet: (i) normalizes red cell membrane ω-6/ω-3 ratio; (ii) reduces neutrophil count; (iii) decreases endothelial activation by targeting endothelin-1 and (iv) improves left ventricular outflow tract dimensions. In a hypoxia-reoxygenation model of acute vaso-occlusive crisis, a ω-3 fatty acid diet reduced systemic and local inflammation and protected against sickle cell-related end-organ injury. Using isolated aortas from sickle cell mice exposed to hypoxia-reoxygenation, we demonstrated a direct impact of a ω-3 fatty acid diet on vascular activation, inflammation, and anti-oxidant systems. Our data provide the rationale for ω-3 dietary supplementation as a therapeutic intervention to reduce vascular dysfunction in sickle cell disease.

Cerebral lesions on 7 tesla MRI in patients with sickle cell anemia

BACKGROUND

Patients with sickle cell anemia (SCA) are at a high risk to develop cerebral damage. Most common are silent cerebral infarctions (SCIs), visible as white matter hyperintensities (WMHs) on MRI in a patient without neurological deficits. The etiology of SCIs remains largely unclear. In addition, patients are at an increased risk for overt stroke, which is associated with large vessel disease. This classification based on the presence or absence of neurological deficits may not be the most fitting for research purposes, as it does not match the different underlying pathology. A classification based on imaging findings may therefore be a more straightforward approach for research purposes. We explored the feasibility to identify imaging features of SCIs in young, asymptomatic patients with SCA using ultra high-field 7 Tesla (7T) MRI. 7T MRI has a high resolution, which offers a unique chance to investigate small subclinical brain lesions in detail. To explore the superiority of 7T in identifying imaging abnormalities, we compared our results with 3T MRI.

METHODS

Ten young, neurologically asymptomatic patients with SCA underwent 7T and 3T MRI; 10 healthy, age-matched controls underwent 7T MRI. We used existing neuroimaging standards to classify the brain lesions. We scored 7T and 3T scans separately, blinded for all other results.

RESULTS

Using 7T MRI, we identified more patients with intracerebral lesions (9/10 vs. 5/10), a higher total count of WMHs (203 vs. 190, p = 0.016) and more lacunes (5 vs. 4) compared to 3T MRI. Abnormalities seen on 7T, which could not be identified on 3T, were cortical hyperintensities (in 3/10) and a different aspect of irregular WMHs, closely associated with cortical hyperintensities in a patient with large vessel stenosis. In 7 controls, a total of 13 WMHs were present.

CONCLUSION

Using 7T MRI, we identified more intracerebral lesions compared to 3T, and found several abnormalities not visible on 3T. 7T MRI in SCA seems of particular interest to study the cortical involvement and the relation between WMHs and the cortex. We found some imaging features that are thought to be representative for small vessel disease, including WMHs, lacunes and prominent perivascular spaces; to understand whether small vessel disease plays a role in SCA requires further research.

Morphine for the treatment of pain in sickle cell disease

Pain is a hallmark of sickle cell disease (SCD) and its treatment remains challenging. Opioids are the major family of analgesics that are commonly used for treating severe pain. However, these are not always effective and are associated with the liabilities of their own. The pharmacology and multiorgan side effects of opioids are rapidly emerging areas of investigation, but there remains a scarcity of clinical studies. Due to opioid-induced endothelial-, mast cell-, renal mesangial-, and epithelial-cell-specific effects and proinflammatory as well as growth influencing signaling, it is likely that when used for analgesia, opioids may have organ specific pathological effects. Experimental and clinical studies, even though extremely few, suggest that opioids may exacerbate existent organ damage and also stimulate pathologies of their own. Because of the recurrent and/or chronic use of large doses of opioids in SCD, it is critical to evaluate the role and contribution of opioids in many complications of SCD. The aim of this review is to initiate inquiry to develop strategies that may prevent the inadvertent effect of opioids on organ function in SCD, should it occur, without compromising analgesia.

Elevated soluble platelet glycoprotein VI is a useful marker for DVT in postoperative patients treated with edoxaban

Prevention of deep vein thrombosis (DVT) is important in patients undergoing major orthopedic surgery. Although the detection of an elevated D-dimer level is useful for predicting DVT, it is not efficacious in postoperative patients being treated with anti-Xa agents. The soluble platelet glycoprotein VI (sGPVI) level is a marker of activated platelets, but not bleeding. Therefore, sGPVI levels are usually examined as a predictor of DVT in such patients. In the present study, 83 orthopedic patients were treated with 30 mg of edoxaban for prophylaxis of DVT. Fourteen patients developed DVT and 17 patients discontinued the prophylaxis due to decreased hemoglobin levels. Plasma levels of sGPVI in the patients were significantly higher after surgery than before surgery. On day 1, the sGPVI levels increased, while the platelet counts decreased. There were no significant differences in D-dimer, soluble fibrin, or FDP levels in orthopedic patients with and without DVT before surgery and on days 1, 4, and 8. Plasma sGPVI levels were significantly higher in the patients with DVT than in those without DVT on days 1 and 4. Plasma levels of D-dimer were significantly higher in patients with withdrawal than in those without. However, there were no significant differences in sGPVI levels between those with and without withdrawal. As D-dimer levels are known to increase in patients with withdrawal, this parameter is not useful for evaluating the risk of DVT in these patients. In contrast, the sGPVI level is not increased in those with withdrawal and may therefore be useful for evaluating the risk of DVT in postoperative patients treated with an anticoagulant.

Heme-bound iron activates placenta growth factor in erythroid cells via erythroid Krüppel-like factor

In adults with sickle cell disease (SCD), markers of iron burden are associated with excessive production of the angiogenic protein placenta growth factor (PlGF) and high estimated pulmonary artery pressure. Enforced PlGF expression in mice stimulates production of the potent vasoconstrictor endothelin-1, producing pulmonary hypertension. We now demonstrate heme-bound iron (hemin) induces PlGF mRNA >200-fold in a dose- and time-dependent fashion. In murine and human erythroid cells, expression of erythroid Krüppel-like factor (EKLF) precedes PlGF, and its enforced expression in human erythroid progenitor cells induces PlGF mRNA. Hemin-induced expression of PlGF is abolished in EKLF-deficient murine erythroid cells but rescued by conditional expression of EKLF. Chromatin immunoprecipitation reveals that EKLF binds to the PlGF promoter region. SCD patients show higher level expression of both EKLF and PlGF mRNA in circulating blood cells, and markers of iron overload are associated with high PlGF and early mortality. Finally, PlGF association with iron burden generalizes to other human diseases of iron overload. Our results demonstrate a specific mechanistic pathway induced by excess iron that is linked in humans with SCD and in mice to markers of vasculopathy and pulmonary hypertension. These trials were registered at www.clinicaltrials.gov as #NCT00007150, #NCT00023296, #NCT00081523, and #NCT00352430.

Hydroxyurea therapy for priapism prevention and erectile function recovery in sickle cell disease: a case report and review of the literature

Prolonged ischemic priapism in patients with sickling hemoglobinopathies is a urologic emergency requiring immediate intervention to avoid irreversible anoxic penile injury, corporal fibrosis, and erectile dysfunction. Therapeutic options, however, are limited and often ineffective. Here, we report recovery of erectile function with hydroxyurea therapy in an adolescent with hemoglobin SS following a prolonged episode of priapism and subsequent severe erectile dysfunction. This case suggests a potential role of hydroxyurea in reversing end organ damage in patients with hemoglobin SS and also supports basic science work indicating involvement of the NO-dependent pathway in the pathogenesis of sickle cell disease-associated priapism.