Echocardiographic markers of elevated pulmonary pressure and left ventricular diastolic dysfunction are associated with exercise intolerance in adults and adolescents with homozygous sickle cell anemia in the United States and United Kingdom

Rpl13a snoRNAs U34 and U35a: New Targets for Sickle Cell Disease Complications

BACKGROUND

In sickle cell disease (SCD), erythrocyte reactive oxygen species (ROS) production and oxidative stress play a critical role in vaso-occlusion, a hallmark of SCD. Small noncoding nucleolar RNAs (snoRNAs) of the Rpl13a locus have been described as regulators of ROS levels. However, whether Rpl13a snoRNAs are present in sickle red blood cells (RBCs) and regulate ROS levels and whether they contribute to SCD pathophysiology remain unknown.

METHODS

To determine whether sickle RBC ROS levels are associated with Rpl13a snoRNA levels and identify the mechanism by which they regulate ROS and snoRNAs' effects on SCD hemodynamics, we used human RBCs, Rpl13a snoRNA knockout sickle mice, K562 U32a, U33, U34, U35a, and the control U25 knockout mutants generated by CRISPR-Cas9-targeted genome editing, and genetic targeting with antisense oligonucleotides.

RESULTS

Excessive ROS production in sickle RBCs of patients with SCD is associated with high Rpl13a snoRNAs U32a, U33, U34, and U35a levels. U32a, U34, and U35a regulate ROS and hydrogen peroxide levels in sickle erythroid populations by modulating peroxidase activity. This was due to U32a- and U34-guided 2'-O-methylation on Prdx2 (peroxiredoxin 2) messenger RNA, a modification conveyed by fibrillarin during erythropoiesis, subsequently reducing Prdx2 expression and activity. The snoRNA U35a impaired Prdx2 expression/activity but independently of Prdx2 messenger RNA 2'-O-methylation. Excess sickle RBC ROS increased in turn Rpl13a snoRNAs levels. In vivo targeting combinations of U34+U35a and U32a+U34+U35a in sickle mice with antisense oligonucleotide blunted RBC ROS generation, improved erythropoiesis and anemia, alleviated leukocytosis and endothelial damage, diminished cell adhesion in inflamed vessels and vaso-occlusion, restored blood flow, and reduced animal mortality.

CONCLUSIONS

Rpl13a snoRNAs U34 and U35a specifically increase ROS levels, which, in turn, regulate snoRNA expression, in sickle erythroid cells, modulating Prdx2 expression/activity, subsequently impairing hemodynamics. Targeted U34+U35a with antisense oligonucleotide may represent a novel and safe therapy to ameliorate erythropoiesis and downstream events in SCD.

CureSCi Metadata Catalog-Finding and harmonizing studies for secondary analysis of hydroxyurea discontinuation in sickle cell disease

OBJECTIVES

Sickle cell disease (SCD) is a rare group of inherited red blood cell disorders that affect hemoglobin, resulting in serious multi-system complications. The limited number of patients available to participate in research studies can inhibit investigating sophisticated relationships. Secondary analysis is a research method that involves using existing data to answer new research questions. Data harmonization enables secondary analysis by combining data across studies, especially helpful for rare disease research where individual studies may be small. The National Heart, Lung, and Blood Institute Cure Sickle Cell Initiative (CureSCi) Metadata Catalog is a web-based tool to identify SCD study datasets for conducting data harmonization and secondary analysis. We present a proof-of-concept secondary analysis to explore factors associated with discontinuation of hydroxyurea, a safe and effective first line SCD therapy, to illustrate the utility of the CureSCi Metadata Catalog to expedite and enable more robust SCD research.

METHODS

We performed secondary analysis of SCD studies using a multi-step workflow: develop research questions, identify study datasets, identify variables of interest, harmonize variables, and establish an analysis method. A harmonized dataset consisting of eight predictor variables across five studies was created. Secondary analysis employed a generalized linear model to identify factors that significantly impact hydroxyurea discontinuation.

RESULTS

The CureSCi Metadata Catalog provided a platform to efficiently find relevant studies and design a harmonization strategy to prepare data for secondary analysis. Multivariate analysis of the harmonized data identified that patients who were female, had a history of blood transfusion therapy, experiencing pain, and had the SC sickle cell genotype are more likely to stop hydroxyurea treatment.

CONCLUSION

This secondary analysis provides a template for how the CureSCi Metadata Catalog expedites dataset discovery of sickle cell studies for identifying relationships between variables or validating existing findings.

Global prevalence of elevated estimated pulmonary artery systolic pressure in clinically stable children and adults with sickle cell disease: A systematic review and meta-analysis

BACKGROUND

The current study sought to determine the prevalence of elevated estimated pulmonary artery systolic pressure (ePASP) in clinically stable children and adults with sickle cell disease)SCD(worldwide.

METHODS

The studies included were identified through a search of databases such as PubMed, Scopus, Science Direct, Web of Science, and Embase, as well as Google Scholar engine, adhering to specific inclusion and exclusion criteria. Heterogeneity among the primary study results was assessed using the I-squared index, while publication bias was evaluated through funnel plots, Egger's test, and trim and fill analysis. All statistical analyses were conducted using R software, version 4.3.0.

RESULTS

79 primary studies were included, comprising 6,256 children (<18 years old) and 6,582 adults (≥18 years old) with SCD from 22 countries. The prevalence of elevated ePASP was found to be 21.8% (95% confidence interval [CI]: 18.46 to 25.07) in children and 30.6% (95% CI: 27.1 to 34.1) in adults. The prevalence of elevated ePASP among studies with severe SCD genotypes including HbSS and HbS/β0 was found to be 19.45% (95% CI: 14.95 to 23.95) in children and 29.55% (95% CI: 24.21 to 34.89) in adults. Furthermore, sex-specific prevalence among SCD patients with elevated ePASP indicated the highest prevalence in male children at 60.35% (95% CI: 54.82 to 65.88) and adult female patients at 54.41% (95% CI: 47.3 to 61.5). A comparative analysis of the mean values of clinical and laboratory results revealed significant differences in several characteristics, including age, oxygen saturation, hemoglobin levels, fetal hemoglobin, white blood cell counts, platelet counts, and reticulocyte counts between patients with elevated ePASP and those without, in both children and adult SCD populations.

CONCLUSION

Our findings regarding clinically stable SCD patients highlight a high prevalence of elevated ePASP.

Prognostic value of exercise longitudinal right ventricular free wall strain in patients with sickle cell disease

Longitudinal right ventricular free wall strain (RVFWS) has been identified as an independent prognostic marker in patients with pulmonary hypertension. Little is known however about the prognostic value of RVFWS in patients with sickle cell (SC) disease, particularly during exercise. We therefore examined the prognostic significance of RVFWS both at rest and with exercise in patients with SC disease and normal resting systolic pulmonary artery pressure (SPAP). Consecutive patients with SC disease referred for bicycle ergometer stress echocardiography (SE) were enrolled ftom July 2019 to January 2021. All patients had measurable tricuspid regurgitation velocity (TRV). Conventional echocardiography parameters, left ventricular global longitudinal strain (LVGLS), RVFWS, and ventriculoarterial coupling indices (TAPSE/SPAP and RVFWS/SPAP) were assessed at rest and peak exercise. Repeat SE was performed at a median follow-up of 2 years. The cohort consisted of 87 patients (mean age was 31 ± 11 years, 66% females). All patients had normal resting TRV < 2.8 m/s, RVFWS and LVGLS at baseline. There were 23 (26%) patients who had peak stress RVFWS < 20%. They had higher resting and peak stress TRV and SPAP, but lower resting and peak stress TAPSE/SPAP, RVFWS/SPAP, and LVGLS as well as lower peak stress cardiac output when compared to patients with peak stress RVFWS ≥ 20% (p < 0.05). Patients with baseline peak stress RVFWS < 20% had a significant decrease in exercise performance at follow-up (7.5 ± 2.7 min at baseline vs. 5.5 ± 2.8 min at follow-up, p < 0.001). In the multivariate analysis, baseline peak stress RVFWS was the only independent predictor of poorer exercise performance at follow-up [odds ratio 8.2 (1.2, 56.0), p = 0.033]. Among patients with SC disease who underwent bicycle ergometer SE, a decreased baseline value of RVFWS at peak stress predicted poorer exercise time at follow-up.

Prevalence of Pulmonary Hypertension among Sudanese Patients with Sickle Cell Disease

Background

Sickle Cell Disease (SCD) is a hereditary condition characterized by aberrant red blood cell morphology, leading to persistent hemolytic anemia. The consequential impact of SCD on the pulmonary vasculature can result in pulmonary hypertension (PHT), a severe complication that detrimentally affects the well-being and survival of individuals with SCD. The prevalence and risk determinants of PHT in SCD patients exhibit variations across diverse geographical regions and populations. This study aims to ascertain the prevalence of PHT among Sudanese SCD patients and identify associated factors.

Methods

A cohort of thirty-one adult sickle cell disease (SCD) patients, as confirmed by hemoglobin electrophoresis, were recruited for participation in this cross-sectional study. Comprehensive data encompassing demographic, clinical, and laboratory parameters were collected. Doppler echocardiography was employed to quantify pulmonary arterial systolic pressure (PASP) and evaluate right ventricular size and function.

Results

Within our cohort, the prevalence of PHT was 29%. Active cigarette smoking demonstrated a significant association with PHT (P=0.042), while hydroxyurea therapy exhibited no noticeable impact on PHT (P=0.612).

Conclusion

Our investigation revealed a PHT prevalence of less than one-third in our SCD patient population, aligning with prior studies. Notably, independent of other factors, cigarette smoking emerged as a distinct risk factor for PHT in SCD patients. This highlights the potential utility of smoking cessation as an intervention to delay the onset of this condition. However, further research is imperative to elucidate the mechanisms through which smoking contributes to PHT development in individuals with SCD.

Left ventricular global longitudinal strain and acute myocardial injury in patients with sickle cell disease admitted to the intensive care unit for vaso-occlusive crisis

In patients with sickle cell disease (SCD), SCD-related cardiomyopathy may be partly due to repeated ischaemic events related to sickling during vaso-occlusive crises, but few clinical studies support this hypothesis. We evaluated the incidence of acute myocardial ischaemia during vaso-occlusive crises as assessed by the left ventricular global longitudinal strain (LVGLS) and high-sensitive cardiac troponin T (hs-cTnT). We included adult patients with SCD admitted to the intensive care unit (ICU) for vaso-occlusive crisis. We collected hs-cTnT and measured LVGLS with echocardiography at admission (day 1), day 2, day 3 and ICU discharge. Among 55 patients included, considering only the first hospitalization of patients admitted several times, 3 (5%) had elevated hs-cTnT at ≥1 time point of the ICU stay. It was ≤2 times the upper limit of normal in two of these patients. LVGLS was altered at ≥1 time point of the ICU stay in 13 (24%) patients. Both hs-cTnT and LVGLS were abnormal at ≥1 time point of the hospital stay in 2 (4%) patients. Acute myocardial injury as assessed by troponin elevation and LVGLS impairment was a rare event during vaso-occlusive crises.

Mortality in adults with sickle cell disease: Results from the sickle cell disease implementation consortium (SCDIC) registry

The cause of death in people affected by sickle cell disease (SCD) is often challenging to define as prior studies have used retrospective or administrative data for analysis. We used a prospective longitudinal registry to assess mortality and clinical co-morbidities among subjects enrolled in the Sickle Cell Disease Implementation Consortium (SCDIC) registry. At enrollment, we collected the following data: patient-reported demographics, SCD phenotype, baseline laboratory values, comorbidities, and current medications. Subjects were followed for a median of 4.7 years before the present analysis. The relationship of clinical co-morbidities (at time of enrollment) to mortality was determined using survival analysis, adjusting for SCD phenotype and gender. There was a total of 2439 people with SCD enrolled in the SCDIC registry. One hundred and twenty-eight participants (5%) died during the observation period (2017-2022). Six people died from trauma and were excluded from further analysis. Proximate cause of death was unwitnessed in 17% of the deaths, but commonest causes of death include cardiac (18%), acute chest or respiratory failure (11%), sudden unexplained death (8%). Enrollment characteristics of the individuals who died (n = 122) were compared to those of survivors (n = 2317). Several co-morbidities at enrollment increased the odds of death on univariate analysis. All co-morbidities were included in a multivariable model. After backward elimination, iron overload, pulmonary hypertension, and depression, remained statistically significant predictors of the risk of death. SCD reduces life expectancy. Improved comprehensive and supportive care to prevent end-organ damage and address comorbidities is needed for this population.

Altered ventricular longitudinal strain in children with sickle cell disease: Role of TGF-β and IL-18

BACKGROUND

Cardiovascular involvement in sickle cell disease (SCD) has a great impact on patients' morbidity and mortality. Recently, interleukin-18 (IL-18) and transforming growth factor beta (TGF-β) were suggested as potential biomarkers for sickle cell cardiomyopathy. Global longitudinal strain (GLS) is a reliable early parameter for estimation of deformed myocardium. This study evaluated the role of TGF-β and IL-18 as risk indicators of altered strain in patients with SCD.

METHODS

Forty children with SCD (age >5 years) and 40 healthy children as controls, matched in age and sex, were enrolled in the study. All participants were subjected to clinical examination, complete blood count, serum ferritin, TGF-β, IL-18, and assessment of cardiac function by echocardiography.

RESULTS

TGF-β, IL-18, and lactic acid dehydrogenase (LDH) were significantly higher among cases (mean age: 10.6 ± 3.5 years) when compared to controls (p < .001), at cutoff values 41.7 ng/mL, 128.9 pg/mL, and 340 unit, respectively. The LS of free wall of RV (FW-RV) was significantly lower among cases when compared to controls (-23.55% ± 5.55% vs. -28.73% ± 2.43%, p < .001). Free wall longitudinal strain of the right ventricle (FWLS-RV) was significantly correlated to IL-18 and LDH (p < .001), while GLS-RV was significantly correlated to TGF-β. The GLS-LV was correlated to frequency of vaso-occlusive crises (VOCs) per year (p < .001). Diastolic function, E/A of LV, and RV were negatively correlated to the hemoglobin and serum ferritin levels.

CONCLUSIONS

The TGF-β, IL-18, and LDH along with frequent VOCs are correlated to altered LS, especially the right ventricle, and could serve as risk indicators for subclinical cardiomyopathy in children with SCD.

Metabolic signatures of cardiorenal dysfunction in plasma from sickle cell patients as a function of therapeutic transfusion and hydroxyurea treatment

Metabolomics studies in sickle cell disease (SCD) have been so far limited to tens of samples, owing to technical and experimental limitations. To overcome these limitations, we performed plasma metabolomics analyses on 596 samples from patients with SCD enrolled in the WALK-PHaSST study (clinicaltrials gov. Identifier: NCT00492531). Clinical covariates informed the biological interpretation of metabolomics data, including genotypes (hemoglobin [Hb] SS, hemoglobin SC), history of recent transfusion (HbA%), response to hydroxyurea treatment (fetal Hb%). We investigated metabolic correlates to the degree of intravascular hemolysis, cardiorenal function, as determined by tricuspid regurgitation velocity (TRV), estimated glomerular filtration rate (eGFR), and overall hazard ratio (unadjusted or adjusted by age). Recent transfusion events or hydroxyurea treatment were associated with elevation in plasma-free fatty acids and decreases in acyl-carnitines, urate, kynurenine, indoles, carboxylic acids, and glycine- or taurine-conjugated bile acids. High levels of these metabolites, along with low levels of plasma S1P and L-arginine were identified as top markers of hemolysis, cardiorenal function (TRV, eGFR), and overall hazard ratio. We thus uploaded all omics and clinical data on a novel online portal that we used to identify a potential mechanism of dysregulated red cell S1P synthesis and export as a contributor to the more severe clinical manifestations in patients with the SS genotype compared to SC. In conclusion, plasma metabolic signatures - including low S1P, arginine and elevated kynurenine, acyl-carnitines and bile acids - are associated with clinical manifestation and therapeutic efficacy in SCD patients, suggesting new avenues for metabolic interventions in this patient population.

In vivo evaluation of the effect of sickle cell hemoglobin S, C and therapeutic transfusion on erythrocyte metabolism and cardiorenal dysfunction

Despite a wealth of exploratory plasma metabolomics studies in sickle cell disease (SCD), no study to date has evaluate a large and well phenotyped cohort to compare the primary erythrocyte metabolome of hemoglobin SS, SC and transfused AA red blood cells (RBCs) in vivo. The current study evaluates the RBC metabolome of 587 subjects with sickle cell sickle cell disease (SCD) from the WALK-PHaSST clinical cohort. The set includes hemoglobin SS, hemoglobin SC SCD patients, with variable levels of HbA related to RBC transfusion events. Here we explore the modulating effects of genotype, age, sex, severity of hemolysis, and transfusion therapy on sickle RBC metabolism. Results show that RBCs from patients with Hb SS genotypes-compared to AA RBCs from recent transfusion events or SC RBCs-are characterized by significant alterations of RBC acylcarnitines, pyruvate, sphingosine 1-phosphate, creatinine, kynurenine and urate metabolism. Surprisingly, the RBC metabolism of SC RBCs is dramatically different from SS, with all glycolytic intermediates significantly elevated in SS RBCs, with the exception of pyruvate. This result suggests a metabolic blockade at the ATP-generating phosphoenolpyruvate to pyruvate step of glycolysis, which is catalyzed by redox-sensitive pyruvate kinase. Metabolomics, clinical and hematological data were collated in a novel online portal. In conclusion, we identified metabolic signatures of HbS RBCs that correlate with the degree of steady state hemolytic anemia, cardiovascular and renal dysfunction and mortality.

Sickle Cell Disease and the Heart.. [DOI: 10.21203/rs.3.rs-3040535/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0]

Purpose The objective of this study was to explore the relationship between cardiac structure, cardiac index (CI), and diastolic function parameters, and laboratory values in patients with Sickle Cell Disease (SCD), and to characterize the distinct SCD cardiomyopathy phenotype Methods We conducted a retrospective review of 202 adult patients with SCD (mean age 41.02 ± 13.36) at our hospital who underwent outpatient echocardiographic screening from 2019–2022. Results Our study identified cardiac hypertrophy, chamber dilatation with preserved ejection fraction, elevated TRV, increased cardiac output, and diastolic dysfunction as defining echocardiographic features in SCD. There was a negative correlation between CI and lateral e’ (R = -0.182, P = 0.012), and a positive correlation between CI and E/e’ (R = 0.274, P = 0.0001). Conclusions Our study identified a unique cardiomyopathy in patients with SCD characterized by cardiac hypertrophy with preserved systolic function, abnormal mitral inflow patterns, and elevated cardiac output. These features are indicative of restrictive physiology, as evidenced by left atrial enlargement and diastolic dysfunction, superimposed on hyperdynamic physiology. Further research is needed to elucidate the pathophysiological mechanisms underlying these observations and determine their prognostic significance in vulnerable populations with an elevated burden of cardiovascular disease, including the risk of sudden cardiac death.

Metabolic signatures of cardiorenal dysfunction in plasma from sickle cell patients, as a function of therapeutic transfusion and hydroxyurea treatment

Metabolomics studies in sickle cell disease (SCD) have been so far limited to tens of samples, owing to technical and experimental limitations. To overcome these limitations, we performed plasma metabolomics analyses on 596 samples from patients with sickle cell sickle cell disease (SCD) enrolled in the WALK-PHaSST study. Clinical covariates informed the biological interpretation of metabolomics data, including genotypes (hemoglobin SS, hemoglobin SC), history of recent transfusion (HbA%), response to hydroxyurea treatment (HbF%). We investigated metabolic correlates to the degree of hemolysis, cardiorenal function, as determined by tricuspid regurgitation velocity (TRV), estimated glomerular filtration rate (eGFR), and overall hazard ratio (unadjusted or adjusted by age). Recent transfusion events or hydroxyurea treatment were associated with elevation in plasma free fatty acids and decreases in acyl-carnitines, urate, kynurenine, indoles, carboxylic acids, and glycine- or taurine-conjugated bile acids. High levels of these metabolites, along with low levels of plasma S1P and L-arginine were identified as top markers of hemolysis, cardiorenal function (TRV, eGFR), and overall hazard ratio. We thus uploaded all omics and clinical data on a novel online portal that we used to identify a potential mechanism of dysregulated red cell S1P synthesis and export as a contributor to the more severe clinical manifestations in patients with the SS genotype compared to SC. In conclusion, plasma metabolic signatures - including low S1P, arginine and elevated kynurenine, acyl-carnitines and bile acids - are associated with clinical manifestation and therapeutic efficacy in SCD patients, suggesting new avenues for metabolic interventions in this patient population.

Genome-wide association study of early ischaemic stroke risk in Brazilian individuals with sickle cell disease implicates ADAMTS2 and CDK18 and uncovers novel loci

Ischaemic stroke is a common complication of sickle cell disease (SCD) and without intervention can affect 11% of children with SCD before the age of 20. Within the Trans-Omics for Precision Medicine (TOPMed), a genome-wide association study (GWAS) of ischaemic stroke was performed on 1333 individuals with SCD from Brazil (178 cases, 1155 controls). Via a novel Cox proportional-hazards analysis, we searched for variants associated with ischaemic stroke occurring at younger ages. Variants at genome-wide significance (p < 5 × 10-8 ) include two near genes previously linked to non-SCD early-onset stroke (<65 years): ADAMTS2 (rs147625068, p = 3.70 × 10-9 ) and CDK18 (rs12144136, p = 2.38 × 10-9 ). Meta-analysis, which included the independent SCD cohorts Walk-PHaSST and PUSH, exhibited consistent association for variants rs1209987 near gene TBC1D32 (p = 3.36 × 10-10 ), rs188599171 near CUX1 (p = 5.89 × 10-11 ), rs77900855 near BTG1 (p = 4.66 × 10-8 ), and rs141674494 near VPS13C (1.68 × 10-9 ). Findings from this study support a multivariant model of early ischaemic stroke risk and possibly a shared genetic architecture between SCD individuals and non-SCD individuals younger than 65 years.

Metabolic correlates to critical speed in murine models of sickle cell disease

Introduction: Exercise intolerance is a common clinical manifestation in patients with sickle cell disease (SCD), though the mechanisms are incompletely understood. Methods: Here we leverage a murine mouse model of sickle cell disease, the Berkeley mouse, to characterize response to exercise via determination of critical speed (CS), a functional measurement of mouse running speed upon exerting to exhaustion. Results: Upon observing a wide distribution in critical speed phenotypes, we systematically determined metabolic aberrations in plasma and organs-including heart, kidney, liver, lung, and spleen-from mice ranked based on critical speed performances (top vs. bottom 25%). Results indicated clear signatures of systemic and organ-specific alterations in carboxylic acids, sphingosine 1-phosphate and acylcarnitine metabolism. Metabolites in these pathways showed significant correlations with critical speed across all matrices. Findings from murine models were thus further validated in 433 sickle cell disease patients (SS genotype). Metabolomics analyses of plasma from 281 subjects in this cohort (with HbA < 10% to decrease confounding effects of recent transfusion events) were used to identify metabolic correlates to sub-maximal exercise test performances, as measure by 6 min walking test in this clinical cohort. Results confirmed strong correlation between test performances and dysregulated levels of circulating carboxylic acids (especially succinate) and sphingosine 1-phosphate. Discussion: We identified novel circulating metabolic markers of exercise intolerance in mouse models of sickle cell disease and sickle cell patients.

Longitudinal effect of disease-modifying therapy on left ventricular diastolic function in children with sickle cell anemia

Cardiac abnormalities seen in sickle cell anemia (SCA) include diastolic dysfunction, which has been shown to be associated with high morbidity and early mortality. The effect of disease-modifying therapies (DMT) on diastolic dysfunction is poorly understood. We prospectively evaluated the effects of hydroxyurea and monthly erythrocyte transfusions on diastolic function parameters over 2 years. A total of 204 subjects with HbSS or HbSβ0-thalassemia (mean age 11 ± 3.7 years), unselected for disease severity, had diastolic function assessed with surveillance echocardiograms twice, 2 years apart. During this 2-year observation period, 112 participants received DMTs (hydroxyurea, n = 72, monthly erythrocyte transfusions, n = 40), 34 initiated hydroxyurea, and 58 did not receive any DMT. The entire cohort showed an increase in left atrial volume index (LAVi) of 3.40 ± 10.86 mL/m2, p = .001 over 2 years. This increase in LAVi was independently associated with anemia, high baseline E/e' or LV dilation. Individuals not exposed to DMT were younger (mean age 8.8 ± 2.9 years), but at baseline their prevalence of abnormal diastolic parameters was similar to that of the DMT-exposed participants who were older (mean age 12 ± 3.8 years). Participants on DMTs saw no improvement in diastolic function over the study period. In fact, participants on hydroxyurea saw a possible worsening in diastolic parameters (14% increase in LAVi and ~5% decrease in septal e') but also a ~9% decrease in fetal hemoglobin (HbF) levels. Further studies are needed to evaluate if exposure to DMT for a longer duration or achieving higher HbF might be beneficial in alleviating diastolic dysfunction.

The Role of Inflammation in The Cellular and Molecular Mechanisms of Cardiopulmonary Complications of Sickle Cell Disease

Cardiopulmonary complications remain the major cause of mortality despite newer therapies and improvements in the lifespan of patients with sickle cell disease (SCD). Inflammation has been identified as a major risk modifier in the pathogenesis of SCD-associated cardiopulmonary complications in recent mechanistic and observational studies. In this review, we discuss recent cellular and molecular mechanisms of cardiopulmonary complications in SCD and summarize the most recent evidence from clinical and laboratory studies. We emphasize the role of inflammation in the onset and progression of these complications to better understand the underlying pathobiological processes. We also discuss future basic and translational research in addressing questions about the complex role of inflammation in the development of SCD cardiopulmonary complications, which may lead to promising therapies and reduce morbidity and mortality in this vulnerable population.

In vivo evaluation of the effect of sickle cell hemoglobin S, C and therapeutic transfusion on erythrocyte metabolism and cardiorenal dysfunction

Despite a wealth of exploratory plasma metabolomics studies in sickle cell disease (SCD), no study to date has evaluate a large and well phenotyped cohort to compare the primary erythrocyte metabolome of hemoglobin SS, SC and transfused AA red blood cells (RBCs) in vivo . The current study evaluates the RBC metabolome of 587 subjects with sickle cell sickle cell disease (SCD) from the WALK-PHaSST clinical cohort. The set includes hemoglobin SS, hemoglobin SC SCD patients, with variable levels of HbA related to RBC transfusion events, and HbF related to hydroxyurea therapy. Here we explore the modulating effects of genotype, age, sex, severity of hemolysis, and hydroxyurea and transfusion therapy on sickle RBC metabolism. Data - collated in an online portal - show that the Hb SS genotype is associated with significant alterations of RBC acylcarnitines, pyruvate, sphingosine 1-phosphate, creatinine, kynurenine and urate metabolism. Surprisingly, the RBC metabolism of SC RBCs is dramatically different from SS, with all glycolytic intermediates significantly elevated in SS RBCs, with the exception of pyruvate. This result suggests a metabolic blockade at the ATP-generating phosphoenolpyruvate to pyruvate step of glycolysis, which is catalyzed by redox-sensitive pyruvate kinase. Increasing in vivo concentrations of HbA improved glycolytic flux and normalized the HbS erythrocyte metabolome. An unexpectedly limited metabolic effect of hydroxyurea and HbF was observed, possibly related to the modest induction of HbF in this cohort. The metabolic signature of HbS RBCs correlated with the degree of steady state hemolytic anemia, cardiovascular and renal dysfunction and mortality.

Key points

In vivo dysregulation of RBC metabolism by HbS is evaluated by metabolic profiling of 587 patients with variable HbA, HbC and HbF levels;RBC acyl-carnitines, urate, pyruvate metabolism, S1P, kynurenine relate to hemolysis and cardiorenal dysfunction, respond to transfusion.

Echocardiographic Evaluation in Paediatric Sickle Cell Disease Patients: A Pilot Study

Cardiovascular involvement has a great impact on morbidity and mortality in sickle cell disease (SCD). Currently, few studies are available regarding the paediatric setting and, moreover, current guidelines for the echocardiogram screening program in the asymptomatic paediatric population are controversial. We performed a retrospective observational monocentric study on 64 SCD patients (37 male and 27 female, median age 10) at the Bambino Gesù Childrens' Hospital, who had undergone a routine transthoracic echocardiogram. In total, 46 (72%) patients had at least one cardiac abnormality. Left atrial dilatation (LAD) was present in 41 (65%) patients and left ventricular hypertrophy (LVH) was found in 29 (45%) patients. Patients with LAD showed lower median haemoglobin levels (p = 0.009), and a higher absolute reticulocyte count (p = 0.04). LVH was negatively correlated with the median haemoglobin value (p = 0.006) and positively with the reticulocyte count (p = 0.03). Moreover, we found that patients with cardiac anomalies had higher transfusion needs and a lower frequency of pain crises. In our setting, cardiac involvement has a high prevalence in the paediatric cohort and seems to be associated with specific laboratory findings, and with a specific clinical phenotype characterized by complications related to high haemodynamic load.

Longitudinal Changes in Cardiac Function Based on Serial Tissue Doppler and Doppler Imaging for Patients With Sickle Cell Anemia

Objective:

The aim was to evaluate the long-term changes in systolic and diastolic functions with tissue Doppler imaging in children with sickle cell anemia.

Materials and Methods:

In this study, myocardial performance index of ventricles and mitral and tricuspid valve E/A ratios were calculated. Wall motion velocities of the interventricular septum, right and left ventricles, and mitral and tricuspid annulus were assessed during the systole (Sm), the early diastole (Em), and the late diastole (Am) with pulsed Doppler echocardiography.

Results:

These diagnostic parameters were obtained from 38 patients (mean 12.5 ± 3.2 years old) who were reached after a mean 6.7 years in long-term follow-up. Left ventricular and septal end-systolic and end-diastolic diameters, and right and left ventricular myocardial performance index were higher in patients ( P < .05 and P = .001, respectively). The Em, Am, and Sm velocities of the right ventricle and septum were significantly lower in the patients at the baseline measures ( P < .05) and all these velocities decreased significantly in patients over time compared with their baseline values ( P < .05). In addition, it was observed that myocardial performance index values of the right and left ventricles increased significantly over time ( P < .05).

Conclusion:

This is the first study reflecting the age-related changes in global systolic and diastolic functions in sickle cell anemia by serial imaging.

Evaluation of left ventricular systolic function in children with sickle cell anemia: contribution of 2D strain

BACKGROUND

Children with sickle cell anemia (SCA) are at an increased risk of cardiovascular complications. The aim of this study was to assess the role of speckle tracking echocardiography in detecting subclinical myocardial damage in children with SCA.

METHODS

A cross-sectional case-control study was conducted at the echocardiography laboratory of the military hospital of Tunis between July and December 2018. Thirty patients with SCA were included. A control(C) group including 30 normally developing children was selected and matched to the SCA group by sex and age. We compared between the two groups: conventional echocardiographic parameters including cardiac output, left ventricular ejection fraction (LVEF), thickness and the global longitudinal strain (GLS). The echocardiographic measurements were indexed according to body surface area. The left ventricular (LV) GLS association with clinical characteristics and echocardiographic parameters were also evaluated.

RESULTS

Patients and controls were matched for age and sex: the mean age was (11± 2years) in SCA group versus (12± 1 years) in C group with a sex ratio of (1.31 versus 1.27, respectively). Body surface area was comparable. LV hypertrophy and dilation were revealed in the SCA group, whereas measurements were normal in the C group. No significant differences were observed for cardiac output (p=0.4). LVEF were preserved in both groups. However, two-dimensional (2D) LVGLS was impaired in 46% of SCA group (n=14) with mean value of (-21%±3.07 vs -25%±2.98; p<0.01).In SCA group, impaired LVGLS was significantly associated with LV mass (r = - 0.399, p<0.01), LV tele diastolic diameter(r= -0.419, p<0.01) and left atrial volume (r= - 0.399, p< 0.04). In multivariate analysis, LV mass was the only independent factor.

CONCLUSIONS

In the present study, LVGLS measurement revealed subclinical LV systolic impairment in patients with SCA. Therefore, 2D strain could be beneficial to detect the natural history of LV dysfunction in SCA.

Arginine Therapy and Cardiopulmonary Hemodynamics in Hospitalized Children with Sickle Cell Anemia: A Prospective, Double-blinded, Randomized Placebo-controlled Clinical Trial

Rationale: Acute changes in cardiopulmonary hemodynamics that include tricuspid regurgitant jet velocity (TRV) elevation measured by Doppler echocardiography are often encountered during sickle cell vasoocclusive pain and acute chest syndrome (ACS). Arginine and nitric oxide depletion develop in patients with these complications. Arginine administration may therefore improve nitric oxide bioavailability and potentiate pulmonary vasodilatation. Objectives: To evaluate effects of l-arginine supplementation on Doppler indices of cardiopulmonary hemodynamics in children with sickle cell anemia experiencing pain. Methods: This was a prospective, double-blinded, randomized placebo-controlled trial of oral arginine in children with sickle cell anemia age 5-17 years hospitalized with severe pain and/or ACS. Measurements and Main Results: Blood biomarkers and Doppler echocardiographic indices of cardiopulmonary hemodynamics were measured before and after supplementation. The mean change in TRV, pulmonary artery systolic pressure, mean pulmonary artery pressure, and other indices of cardiopulmonary hemodynamics were tested with paired Student's t test and correlated with markers of arginine bioavailability using Pearson correlation. Sixty-six children were randomized into arginine versus placebo groups. An elevated TRV ⩾ 2.5 m/s was seen in 40 (61%) patients. A Day 5 Doppler echocardiogram was performed in 47 patients who remained hospitalized. A greater reduction in median TRV occurred in the arginine group than placebo (22.2%, n = 22 vs. 3.8%, n = 25; p < 0.01). A larger percentage increase in global arginine bioavailability was associated with a lower TRV after 5 days of supplementation (r = -0.533; P = 0.001). Significant differences in multiple indices of cardiopulmonary hemodynamics and mean N-terminal pro B-type brain natriuretic peptide were also noted after arginine therapy. Conclusions: Oral arginine supplementation improves cardiopulmonary hemodynamics during sickle cell disease vasoocclusive pain and ACS.Clinical trial registered with Pan African Clinical Trial Registry https://pactr.samrc.ac.za/Search.aspx (PACTR201611001864290).

Testes Ergométricos em Pacientes com Anemia Falciforme: Segurança, Viabilidade e Possíveis Implicações no Prognóstico

Fundamento

Pacientes com anemia falciforme (AF) têm risco aumentado de complicações cardiovasculares. O teste ergométrico é usado como marcador de prognóstico em uma série de doenças cardiovasculares. Entretanto, há uma escassez de evidências sobre exercícios em pacientes com AF, especialmente em relação à sua segurança, viabilidade e possível função prognóstica.

Objetivos

Usamos o teste em esteira máximo para determinar a segurança e a viabilidade do teste ergométrico em pacientes com AF. Além disso, os fatores associados à duração do exercício, bem como o impacto das alterações causadas pelo exercício em resultados clínicos, também foram avaliados.

Métodos

113 pacientes com AF que passaram pelo teste ergométrico e por uma avaliação cardiovascular abrangente incluindo um ecocardiograma e os níveis do peptídeo natriurético do tipo B (BNP). O desfecho de longo prazo foi uma combinação de eventos incluindo morte, crises álgicas graves, síndrome torácica aguda ou internações hospitalares por outras complicações associadas â doença falciforme. A análise de regressão de Cox foi realizada para identificar as variáveis associadas ao resultado. Um p valor <0,05 foi considerado estatisticamente significativo.

Resultados

A média de idade foi de 36 ± 12 anos (intervalo, 18-65 anos), e 62 pacientes eram do sexo feminino (52%). A presença de alterações isquêmicas ao esforço e resposta pressórica anormal ao exercício foram detectadas em 17% e 9 % da´população estudada respectivamente. Dois pacientes apresentaram crise álgica com necessidade de internação hospitalar no período de 48 horas da realização do exame. Fatores associados à duração do exercício foram idade, sexo, velocidade máxima de regurgitação tricúspide (RT), e relação E/e’, após a padronização quanto aos marcadores da gravidade da doença. Durante o período médio de acompanhamento de 10,1 meses (variando de 1,2 a 26), 27 pacientes (23%) apresentaram desfechos clínicos adversos. Preditores independentes de eventos adversos foram a concentração de hemoglobina, velocidade do fluxo transmitral tardio (onda A), e a resposta da PA ao exercício.

Conclusões

A realização de testes ergométricos em pacientes com AF, clinicamente estáveis, é viável. A duração do exercício estava associada à função diastólica e a pressão arterial pulmonar. A resposta anormal da PA foi um preditor independente de eventos adversos.

Influence of Haptoglobin Polymorphism on Stroke in Sickle Cell Disease Patients

This review outlines the current clinical research investigating how the haptoglobin (Hp) genetic polymorphism and stroke occurrence are implicated in sickle cell disease (SCD) pathophysiology. Hp is a blood serum glycoprotein responsible for binding and removing toxic free hemoglobin from the vasculature. The role of Hp in patients with SCD is critical in combating blood toxicity, inflammation, oxidative stress, and even stroke. Ischemic stroke occurs when a blocked vessel decreases oxygen delivery in the blood to cerebral tissue and is commonly associated with SCD. Due to the malformed red blood cells of sickle hemoglobin S, blockage of blood flow is much more prevalent in patients with SCD. This review is the first to evaluate the role of the Hp polymorphism in the incidence of stroke in patients with SCD. Overall, the data compiled in this review suggest that further studies should be conducted to reveal and evaluate potential clinical advancements for gene therapy and Hp infusions.

Associations of anemia with death and major bleeding in patients with atrial fibrillation: A report from the Chinese Atrial Fibrillation Registry Study

Background

Anemia is a common comorbidity in patients with atrial fibrillation (AF). Reports on the association of anemia and adverse events in patients with AF, especially from Asia, are limited.

Methods and Results

Based on data from the Chinese Atrial Fibrillation Registry Study (CAFR), a total of 18,106 AF patients enrolled between August 2011 and December 2018 had hemoglobin (Hb) values recorded at baseline. Patients were classified into three groups according to Hb levels: 15,606 patients (86.2%) into the no anemia group (male Hb≥130 g/L; female Hb≥120 g/L), 1800 (9.9%) with mild anemia (male 110≤Hb<129 g/L; female 110≤Hb<119 g/L), and 700 (3.9%) with moderate to severe anemia (Hb≤109 g/L). Multivariable Cox regression models were used to determine if anemia was independently associated with all‐cause death, cardiovascular death, or major bleeding, after adjusting for confounders.

Anemia was present in 13.8% of the population at baseline. During a median follow‐up of 4.01 years, the incidences of all‐cause death (1.8, 4.9, and 8.9 per 100 person‐years), cardiovascular death (1.0, 2.9, and 4.5 per 100 person‐years), and major bleeding (0.5, 0.6, and 0.7 per 100 person‐years) were gradually accentuated in patients with no anemia, mild anemia, and moderate to severe anemia, respectively. Compared with patients with no anemia, those with anemia had higher risks for all‐cause death (mild anemia; adjusted hazard ratio [HR]: 1.22, 95% confidence interval [CI]: 1.08–1.38; moderate to severe anemia; adjusted HR: 1.53, 95% CI: 1.31–1.77); and cardiovascular death (mild anemia; adjusted HR: 1.29, 95% CI: 1.10–1.52; moderate to severe anemia; adjusted HR: 1.27, 95% CI: 1.03–1.57), but not for major bleeding. The association between anemia and all‐cause death was similar among subgroups stratified by sex, kidney function, anticoagulant, or ablation therapy.

Conclusions

Anemia was associated with increased risks of all‐cause death, cardiovascular death, but no major bleeding in AF patients. The effect of anemia correction on the prognosis of patients with AF requires further study.

Exercise-induced changes of vital signs in adults with sickle cell disease

The six-minute walk test (6MWT) has been used in patients with sickle cell disease (SCD), in conjunction with tricuspid regurgitant velocity (TRV) and plasma N-terminal pro-brain natriuretic peptide (NT-pro BNP), to assess risk of having pulmonary hypertension. Exercise-induced vital sign changes (VSCs) are predictors of clinical outcomes in other diseases. In this study, we assess the predictors and prognostic value of 6MWT VSC in adult SCD patients. Data from a multinational study of SCD patients (Treatment of Pulmonary Hypertension with Sildenafil: walk-PHaSST) were used to calculate the 6MWT VSC. Predictors of VSC were identified by a multivariable analysis, and a survival analysis was conducted by the Cox proportional hazard method. An increase in heart rate was observed in 90% of the 630 SCD adults, 77% of patients had an increase in systolic blood pressure (SBP), and 50% of patients had a decrease in oxygen saturation. TRV (odds ratio [OR] = 1.82, p = .020), absolute reticulocyte count (OR = 1.03, p < .001), and hemoglobin (OR = 0.99, p = .035) predicted oxygen desaturation ≥ 3% during the 6MWT. In the adjusted analysis, SBP increase during the 6MWT was associated with improved survival (hazards ratio = 0.3, 95% confidence interval: 0.1-0.8). Increases in heart rate and blood pressure, as well as oxygen desaturation, are common in adults with SCD during the 6MWT. VSC is associated with markers of anemia and TRV and can be used for risk stratification. Any increase in SBP during the 6MWT was associated with improved survival and may be indicative of a patient's ability to increase stroke volume.

The burden of sleep disordered breathing in children with sickle cell disease

Children with sickle cell disease (SCD) have an increased risk of sleep disordered breathing (SDB) compared with the general pediatric population. There has been a growing research interest on this field in recent years, yet many questions regarding risk factors and clinical implications of SDB remain unclear. The aim of this review is to provide a concise narrative and systematic synthesis of the available evidence on the epidemiology, clinical presentation, complications, and management, of SDB in children with SCD. An electronic search was conducted on studies published from the 1st of January 2000 to the 31st of December 2020 in PubMed/Medline, Scopus, and Cochrane databases. All studies focusing on SDB in children with SCD aged from 0 to 20 years were included. Studies were eligible for inclusion if available in the English language. A quantitative synthesis of the included studies was performed. Only studies focusing on specific treatment outcomes were included in a meta-analytic process. A total of 190 papers were initially identified. After screening the title and abstract, 112 articles were evaluated for eligibility. At the end of the selection process, 62 studies were included in the analysis. Sleep disordered breathing is associated with worse neurological, neurocognitive, and cardiological outcomes, whereas the association with frequency or severity of vaso-occlusive pain events and acute chest syndrome was not clarified. Therapeutic interventions like adenotonsillectomy or oxygen supplementation may result in a significant increase in mean nocturnal oxygen saturation but effective clinical implications remain still unclear.

Murine models of sickle cell disease and beta-thalassemia demonstrate pulmonary hypertension with distinctive features

Sickle cell anemia and β-thalassemia intermedia are very different genetically determined hemoglobinopathies predisposing to pulmonary hypertension. The etiologies responsible for the associated development of pulmonary hypertension in both diseases are multi-factorial with extensive mechanistic contributors described. Both sickle cell anemia and β-thalassemia intermedia present with intra and extravascular hemolysis. And because sickle cell anemia and β-thalassemia intermedia share features of extravascular hemolysis, macrophage iron excess and anemia we sought to characterize the common features of the pulmonary hypertension phenotype, cardiac mechanics, and function as well as lung and right ventricular metabolism. Within the concept of iron, we have defined a unique pulmonary vascular iron accumulation in lungs of sickle cell anemia pulmonary hypertension patients at autopsy. This observation is unlike findings in idiopathic or other forms of pulmonary arterial hypertension. In this study, we hypothesized that a common pathophysiology would characterize the pulmonary hypertension phenotype in sickle cell anemia and β-thalassemia intermedia murine models. However, unlike sickle cell anemia, β-thalassemia is also a disease of dyserythropoiesis, with increased iron absorption and cellular iron extrusion. This process is mediated by high erythroferrone and low hepcidin levels as well as dysregulated iron transport due transferrin saturation, so there may be differences as well. Herein we describe common and divergent features of pulmonary hypertension in aged Berk-ss (sickle cell anemia) and Hbb^th/3+ (intermediate β-thalassemia) mice and suggest translational utility as proof-of-concept models to study pulmonary hypertension therapeutics specific to genetic anemias.

Cardiovascular phenotypes predict clinical outcomes in sickle cell disease: An echocardiography-based cluster analysis

This study sought to link cardiac phenotypes in homozygous Sickle Cell Disease (SCD) patients with clinical profiles and outcomes using cluster analysis. We analyzed data of 379 patients included in the French Etendard Cohort. A cluster analyses was performed based on echocardiographic variables, and the association between clusters, clinical profiles and outcomes was assessed. Three clusters were identified. Cluster 1 (n = 123) patients had the lowest cardiac output, mild left cardiac cavities remodeling, mild diastolic dysfunction, and higher tricuspid regurgitation velocity (TRV). They were predominantly female and displayed the most altered functional limitation. Cluster 2 (n = 102) patients had the highest cardiac output and the most remodeled cardiac cavities. Diastolic function and TRV were similar to cluster 1. These patients had a higher blood pressure and a severe hemolytic anemia. Cluster 3 (n = 154) patients had mild left cardiac cavities remodeling, normal diastolic function and lowest TRV values. They were younger with the highest hemoglobin value. Right heart catheterization was performed in 94 patients. Cluster 1 (n = 33) included the majority of pre-capillary PH whilst cluster 2 (n = 34) included post-capillary PH. No PH was found in cluster 3 (n = 27). After a follow-up of 11.4 ± 2 years, death occurred in 41 patients (11%). Cluster 2 patients had the worst prognosis with a 19% mortality rate versus 12% in cluster 1 and 5% in cluster 3 (p log-rank = 0.003). Cluster analysis of echocardiography variables identified three hemodynamic and clinical phenotypes among SCD patients, each predicting a different prognosis.

The different facets of sickle cell disease-related pulmonary hypertension

PURPOSE OF REVIEW

Sickle cell disease (SCD), one of the most common genetic diseases in the world, is characterized by repeated episodes of hemolysis and vaso-occlusion. Hemolytic anemia is a risk factor for the development of pulmonary hypertension, and currently SCD-related pulmonary hypertension is classified as World Health Organization group 5 pulmonary hypertension. Patients with SCD-related pulmonary hypertension have unique hemodynamics, multiple comorbidities, and distinct phenotypes that may contribute to the development of pulmonary hypertension.

RECENT FINDINGS

SCD-related pulmonary hypertension is defined as a mean pulmonary artery pressure >20 mmHg, a pulmonary artery occlusion pressure ≤15 mmHg and relatively low pulmonary vascular resistance (>2 Wood units) rather than the traditional definition of ≥3 Wood units, an important distinction due to a baseline high-cardiac output state in the setting of chronic anemia and low vascular resistance. Diastolic dysfunction is frequently identified in this patient population and right heart catheterization is essential to determine if combined pre- and postcapillary pulmonary hypertension is present. Thromboembolism is common among patients with SCD, and screening for chronic thromboembolic pulmonary hypertension is essential. Data regarding advanced therapies are limited. Primary treatment options include targeting correction of their primary hemoglobinopathy as well as aggressive management of underlying comorbid conditions.

SUMMARY

SCD-related pulmonary hypertension is common among patients with SCD and is associated with increased mortality. A high index of suspicion is warranted during evaluation to identify all potential factors that may be contributing to disease.

Multiple-ancestry genome-wide association study identifies 27 loci associated with measures of hemolysis following blood storage

BackgroundThe evolutionary pressure of endemic malaria and other erythrocytic pathogens has shaped variation in genes encoding erythrocyte structural and functional proteins, influencing responses to hemolytic stress during transfusion and disease.MethodsWe sought to identify such genetic variants in blood donors by conducting a genome-wide association study (GWAS) of 12,353 volunteer donors, including 1,406 African Americans, 1,306 Asians, and 945 Hispanics, whose stored erythrocytes were characterized by quantitative assays of in vitro osmotic, oxidative, and cold-storage hemolysis.ResultsGWAS revealed 27 significant loci (P < 5 × 10-8), many in candidate genes known to modulate erythrocyte structure, metabolism, and ion channels, including SPTA1, ALDH2, ANK1, HK1, MAPKAPK5, AQP1, PIEZO1, and SLC4A1/band 3. GWAS of oxidative hemolysis identified variants in genes encoding antioxidant enzymes, including GLRX, GPX4, G6PD, and SEC14L4 (Golgi-transport protein). Genome-wide significant loci were also tested for association with the severity of steady-state (baseline) in vivo hemolytic anemia in patients with sickle cell disease, with confirmation of identified SNPs in HBA2, G6PD, PIEZO1, AQP1, and SEC14L4.ConclusionsMany of the identified variants, such as those in G6PD, have previously been shown to impair erythrocyte recovery after transfusion, associate with anemia, or cause rare Mendelian human hemolytic diseases. Candidate SNPs in these genes, especially in polygenic combinations, may affect RBC recovery after transfusion and modulate disease severity in hemolytic diseases, such as sickle cell disease and malaria.

Manifestations of HbSE sickle cell disease: a systematic review

BACKGROUND

Sickle cell disease (SCD) is commonly encountered in Africa and Middle Eastern countries. The causative mutation in the gene encoding the hemoglobin subunit β (HBB) leads to various genotypic variants of the disease. This results in varied phenotypes, with a spectrum of complications, from benign to fatal. Hemoglobin SS (HBSS) genotype is associated with most of these complications; hence, it is a severe form of SCD. On the other hand, rare genotypes such as hemoglobin SE (HBSE) are considered benign. There is limited literature about the clinical manifestations and characteristics of patients with HBSE. We pooled all available data describing the phenotypic manifestations of HBSE heterozygote worldwide to perform a systematic review.

METHODS

We performed a systematic review according to PRISMA guidelines using PubMed, SCOPUS, and Google Scholar databases. Two independent reviewers (FA and IK) evaluated studies for eligibility and extracted data. We synthesized data on demographics, manifestations, and management of HBSE disease. PROSPERO Registration Number: CRD42021229877.

RESULTS

We found 68 HBSE patients reported in the literature. 24 cases were extracted from case reports whereas 44 cases from case series and retrospective studies. Turkey reported the highest number of patients (n = 22). 32 (47%) of the patients were males. The mean age was 20.9 ± 18.26 years. The mean HBS and HBE percentages were 61.1% ± 7.25% and 32.3% ± 5.06%, respectively, whereas the mean hemoglobin was 11.64 ± 1.73 g/dl. Reported manifestations of HBSE disease included acute vaso-occlusive pain crisis (n = 22, 32.3%), splenomegaly (n = 11, 16.1%), hemolytic anemia (n = 10, 14.7%), infections (n = 8. 11.7%), bone infarction (n = 4, 5.8%), gallstones (n = 3, 4.4%), venous thromboembolism (VTE) (n = 2, 2.9%) and stroke (n = 2, 2.9%), and hematuria (n = 2, 2.9%). Death due to HBSE complications was reported in three patients.

CONCLUSION

HBSE is a rare genotypic variant of SCD. It has been considered a benign form; however, there are multiple reports of severe complications. Severe complications observed in HBSE disease include vaso-occlusive crisis, acute chest syndrome, stroke, bone marrow embolism, and death.

Chronic organ injuries in children with sickle cell disease

Median life expectancy of patients with sickle cell disease has increased to up to 55 years but there are still frequent cases of premature death, mostly in patients with pre-existing organ failure such as pulmonary hypertension, kidney injury, and cerebral vasculopathy. Most organ injuries remain asymptomatic for a long time and can only be detected through early systematic screening. Protocols combining assessment of velocities on transcranial Doppler and regular transfusions in patients with abnormal velocities have been demonstrated to dramatically reduce the risk of stroke. In contrast, no consensus has been reached on systematic screening or therapy for silent cerebral infarcts. The prognostic significance of increased tricuspid regurgitant jet velocity on echocardiography has not yet been identified in children, whereas increased albuminuria is a good predictor of kidney injury. Finally, screening for hip and eye disorder is recommended; however, different countries adopt different screening strategies. Hydroxyurea is probably of potential benefit in preventing chronic organ damage but this requires further study in order to be fully demonstrated. Efficacy and safety of the other new drugs available are also under investigation.

Is Skeletal Muscle Dysfunction a Limiting Factor of Exercise Functional Capacity in Patients with Sickle Cell Disease?

Patients with sickle cell disease (SCD) have reduced functional capacity due to anemia and cardio-respiratory abnormalities. Recent studies also suggest the presence of muscle dysfunction. However, the interaction between exercise capacity and muscle function is currently unknown in SCD. The aim of this study was to explore how muscle dysfunction may explain the reduced functional capacity. Nineteen African healthy subjects (AA), and 24 sickle cell anemia (SS) and 18 sickle cell hemoglobin C (SC) patients were recruited. Maximal isometric torque (Tmax) was measured before and after a self-paced 6-min walk test (6-MWT). Electromyographic activity of the Vastus Lateralis was recorded. The 6-MWT distance was reduced in SS (p < 0.05) and SC (p < 0.01) patients compared to AA subjects. However, Tmax and root mean square value were not modified by the 6-MWT, showing no skeletal muscle fatigue in all groups. In a multiple linear regression model, genotype, step frequency and hematocrit were independent predictors of the 6-MWT distance in SCD patients. Our results suggest that the 6-MWT performance might be primarily explained by anemia and the self-paced step frequency in SCD patients attempting to limit metabolic cost and fatigue, which could explain the absence of muscle fatigue.

Association of Anemia and Blood Pressure With Novel Markers of Diastolic Function in Pediatric Sickle Cell Disease

Diastolic dysfunction is a known cause of mortality in adults with sickle cell disease (SCD). Left atrial function (LAf) and strain (LAS) are novel echocardiographic parameters to assess early diastolic dysfunction, which have not been assessed in pediatric SCD. Through a retrospective single-center study, we describe echocardiographic parameters of diastology in children with SCD and evaluate their relationship with clinical variables including anemia and blood pressure. Baseline clinical data, 24-hour ambulatory blood pressure monitoring data and echocardiography results were collected. LAf and LAS were measured using volumetric data and speckle-tracking echocardiography, respectively. Sixty-seven children with SCD (13.5±7 y, 47% male, 7% hypertensive) with a mean hemoglobin of 8.8±1.3 g/dL, LAf of 61±8% (n=53) and LAS of 46.3±7.4% (n=28) were included. LAS was significantly associated with hemoglobin (ρ=0.43, P=0.022) but not with maximal left atrial (LA) volume (ρ=-0.05, P=0.79) or any blood pressure parameters. On multivariate analysis, LAS decreased by 3.2% (1.3, 5.1) and LA volume increased by 1.6 mL/m2 (3.1, 0.08) for every 1 g/dL decrease in hemoglobin. Thus, severity of baseline anemia in pediatric SCD correlates with diastolic function as measured by LAS, independent of LA dilation.

The CYB5R3c .350C>G and G6PD A alleles modify severity of anemia in malaria and sickle cell disease

Genetic modifiers of anemia in Plasmodium falciparum infection and sickle cell disease (SCD) are not fully known. Both conditions are associated with oxidative stress, hemolysis and anemia. The CYB5R3 gene encodes cytochrome b5 reductase 3, which converts methemoglobin to hemoglobin through oxidation of NADH. CYB5R3c.350C > G encoding CYB5R3T117S , the most frequent recognized African-specific polymorphism, does not have known functional significance, but its high allele frequency (23% in African Americans) suggests a selection advantage. Glucose-6-phosphate dehydrogenase (G6PD) is essential for protection from oxidants; its African-polymorphic X-linked A+ and A- alleles, and other variants with reduced activity, coincide with endemic malaria distribution, suggesting protection from lethal infection. We examined the association of CYB5R3c.350C > G with severe anemia (hemoglobin <5 g/dL) in the context of G6PD A+ and A- status among 165 Zambian children with malaria. CYB5R3c.350C > G offered protection against severe malarial anemia in children without G6PD deficiency (G6PD wild type or A+/A- heterozygotes) (odds ratio 0.29, P = .022) but not in G6PD A+ or A- hemizygotes/homozygotes. We also examined the relationship of CYB5R3c.350C > G with hemoglobin concentration among 267 children and 321 adults and adolescents with SCD in the US and UK and found higher hemoglobin in SCD patients without G6PD deficiency (β = 0.29, P = .022 children; β = 0.33, P = .004 adults). Functional studies in SCD erythrocytes revealed mildly lower activity of native CYB5R3T117S compared to wildtype CYB5R3 and higher NADH/NAD+ ratios. In conclusion, CYB5R3c.350C > G appears to ameliorate anemia severity in malaria and SCD patients without G6PD deficiency, possibly accounting for CYB5R3c.350C > G selection and its high prevalence.

Prognostic value of left ventricular longitudinal strain by speckle-tracking echocardiography in patients with sickle cell disease

Cardiovascular complications have been increasingly detected in patients with sickle cell disease (SCD). Two-dimensional speckle-tracking echocardiography (STE) detects early myocardial changes in a number of pathophysiological processes, which may be useful in SCD. This study was designed to examine the value of STE in predicting clinical outcome in adult patients with SCD. A total of 219 patients, mean age 33 ± 12 years were prospectively enrolled. Several clinical, laboratory and echocardiographic variables including left ventricular global longitudinal strain (LVGLS) by STE were assessed. The endpoint was a composite of the following events: (1) all-cause mortality, (2) three or more acute painful episodes that require hospitalization in one year, (3) acute chest syndrome and (4) hospitalization due to disease complication. The majority of the patients had enlargement of LV and left atrial (LA) with preserved ejection fraction. During the mean follow-up of 30 months, 69 patients (32%) had reached the endpoint, including eight deaths (3.7%). No difference was observed in the parameters of diastolic function comparing the patients with and without events. LVGLS ranged from - 12.25 to - 25.44 (mean - 20.26 ± 2.5), with higher values in the patients who had events compared with those who did not. In the multivariable analysis, higher LVGLS values were associated with adverse events (adjusted OR 1.25; 95% CI 1.04-1.51; p = 0.021), independently of the TR maximal velocity and LV ejection fraction. In patients with SCD, higher LV global longitudinal strain was a predictor of adverse outcome, independently of age, TR velocity and LV function.

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.

End points for sickle cell disease clinical trials: renal and cardiopulmonary, cure, and low-resource settings

To address the global burden of sickle cell disease and the need for novel therapies, the American Society of Hematology partnered with the US Food and Drug Administration to engage the work of 7 panels of clinicians, investigators, and patients to develop consensus recommendations for clinical trial end points. The panels conducted their work through literature reviews, assessment of available evidence, and expert judgment focusing on end points related to patient-reported outcome, pain (non-patient-reported outcomes), the brain, end-organ considerations, biomarkers, measurement of cure, and low-resource settings. This article presents the findings and recommendations of the end-organ considerations, measurement of cure, and low-resource settings panels as well as relevant findings and recommendations from the biomarkers panel.

Low hemoglobin increases risk for cerebrovascular disease, kidney disease, pulmonary vasculopathy, and mortality in sickle cell disease: A systematic literature review and meta-analysis

Sickle cell disease (SCD) is characterized by deoxygenation-induced polymerization of hemoglobin in red blood cells, leading to hemolytic anemia, vaso-occlusion, and the development of multiple clinical complications. To characterize the clinical burden associated with differences in hemoglobin concentration and hemolysis measures, a systematic literature review of MEDLINE, EMBASE, and related meta-analyses was undertaken. For quantitative analyses related to hemoglobin concentration, pooled results were analyzed using random effects models to control for within-and between-study variability. To derive risk ratios associated with hemoglobin concentration change, we combined ratios of means from select studies, which reported hazard and odds ratios in meta-analyses for hemoglobin concentration-related outcomes and changes between groups. Forty-one studies were identified for inclusion based on relating hemoglobin concentration to clinical outcomes. Meta-analyses demonstrated that mean hemoglobin concentration was significantly lower in patients with cerebrovascular disease (0.4 g/dL), increased transcranial Doppler velocity in cerebral arteries (0.6 g/dL), albuminuria (0.6 g/dL), elevated estimated pulmonary artery systolic pressure (0.9 g/dL), and in patients that subsequently died (0.6 g/dL). In a risk reduction meta-analysis, modeled increased hemoglobin concentrations of 1 g/dL or greater resulted in decreased risk of negative clinical outcomes of 41% to 64%. In conclusion, chronic anemia is associated with worse clinical outcomes in individuals with SCD and even modest increases in hemoglobin concentration may be beneficial in this patient population. This systematic review has been registered on Prospero (Registration number CRD42018096860; https://www.crd.york.ac.uk/prospero/).

Cardiovascular complications of sickle cell disease

Sickle cell disease (SCD) is the most common inherited blood disorder in the United States, and a global health problem. Pathological features of the abnormal hemoglobin (HbS) result in 2 hallmarks of the disease - recurrent episodes of acute microvascular occlusion and chronic hemolytic anemia - that inflict continuous and insidious damage to multiple organs. With improved childhood survival, SCD in adults has evolved into a chronic degenerative disease with underlying damage to multiple organs including the heart and lungs. Cardiopulmonary complications, including cardiomyopathy, diastolic dysfunction, pulmonary hypertension (PH), and sudden cardiac death are the most common causes of morbidity and mortality. Awareness of the sickle-related cardiovascular phenotypes is important for screening, early diagnosis, and intervention of cardiac complications in this disorder.

Left atrial dysfunction in sickle cell anemia is associated with diffuse myocardial fibrosis, increased right ventricular pressure and reduced exercise capacity

Increased extracellular volume (ECV) by CMR is a marker of interstitial myocardial fibrosis and is associated with diastolic dysfunction in sickle cell anemia (SCA). Left atrial (LA) dysfunction and stiffness contribute to the development of diastolic heart failure in other settings. We aimed to evaluate LA function and stiffness associations with ECV, tricuspid regurgitation jet velocity (TRV) and exercise abnormalities in SCA. In a prospective study, individuals with SCA underwent CMR, echocardiography and exercise test. ECV was measured using MOLLI sequence. Atrial strain was studied in the 4- and 2-chamber views. LA stiffness was calculated as the ratio of echocardiographic E/e’-to-LA reservoir strain. Twenty-four participants with SCA were included (median age 20 years). ECV was increased in participant with SCA compared to our lab normal values (mean 0.44 ± 0.08 vs 0.26 ± 0.02, P < 0.0001). Six (25%) had LA LGE. ECV positively correlated with LA stiffness (r = 0.45, p = 0.04). There was a negative correlation between LA stiffness and %predicted VO2 (r = −0.50, p = 0.04). LA stiffness was moderately associated with increased TRV (r = 0.55, p < 0.005). LA stiffness is associated with ECV, exercise impairment and increased TRV. This study sheds insights on the interaction between LA function, RV hypertension, and myocardial fibrosis in SCA.

Physiological Evaluation for Endurance Exercise Prescription in Sickle Cell Disease

PURPOSE

Although strenuous exercise may expose sickle cell disease (SCD) patients to risks of vaso-occlusive crisis, evidence suggests that regular endurance exercise may be beneficial. This study aimed to test (i) the safety and usefulness of a submaximal incremental exercise in evaluating physical ability of SCD patients and identify a marker for the management of endurance exercise and (ii) the feasibility of endurance exercise sessions in SCD patients.

METHODS

Twenty adults with SCD (12 men and 8 women) performed a submaximal incremental exercise used to determine the first lactate threshold (LT1) and stopped as soon as blood lactate concentration ([lactate]b) reached ≥4 mmol·L. Fifteen of those patients (8 men and 7 women) also performed three 30-min endurance exercise sessions at ~2.5 mmol·L of [lactate]b on separate occasions.

RESULTS

LT1 occurred at 47 ± 3 and 33 ± 3 W for men and women, respectively, demonstrating the extreme deconditioning and, thus, low physical ability of adult SCD patients. During endurance exercise, peripheral oxygen saturation and [lactate]b most often remained stable and within acceptable ranges.

CONCLUSIONS

The proposed strategy of submaximal incremental exercise allowed safe determination of LT1, an important parameter of patients' physical ability. The study also demonstrated the feasibility and safety of individually tailored endurance exercises at ~2.5 mmol·L of [lactate]b. These latter results suggest that endurance training programs may be considered for adult SCD patients and that the method proposed here may be helpful in that regard.

Life-Threatening Infectious Complications in Sickle Cell Disease: A Concise Narrative Review

Sickle cell disease (SCD) results in chronic hemolytic anemia, recurrent vascular occlusion, insidious vital organ deterioration, early mortality, and diminished quality of life. Life-threatening acute physiologic crises may occur on a background of progressive diminishing vital organ function. Sickle hemoglobin polymerizes in the deoxygenated state, resulting in erythrocyte membrane deformation, vascular occlusion, and hemolysis. Vascular occlusion and increased blood viscosity results in functional asplenia and immune deficiency in early childhood, resulting in life-long increased susceptibility to serious bacterial infections. Infection remains a main cause of overall mortality in patients with SCD in low- and middle-income countries due to increased exposure to pathogens, increased co-morbidities such as malnutrition, lower vaccination rates, and diminished access to definitive care, including antibiotics and blood. Thus, the greatest gains in preventing infection-associated mortality can be achieved by addressing these factors for SCD patients in austere environments. In contrast, in high-income countries, perinatal diagnosis of SCD, antimicrobial prophylaxis, vaccination, aggressive use of antibiotics for febrile episodes, and the availability of contemporary critical care resources have resulted in a significant reduction in deaths from infection; however, chronic organ injury is problematic. All clinicians, regardless of their discipline, who assume the care of SCD patients must understand the importance of infectious disease as a contributor to death and disability. In this concise narrative review, we summarize the data that describes the importance of infectious diseases as a contributor to death and disability in SCD and discuss pathophysiology, prevalent organisms, prevention, management of acute episodes of critical illness, and ongoing care.

Smooth muscle cytochrome b5 reductase 3 deficiency accelerates pulmonary hypertension development in sickle cell mice

Pulmonary and systemic vasculopathies are significant risk factors for early morbidity and death in patients with sickle cell disease (SCD). An underlying mechanism of SCD vasculopathy is vascular smooth muscle (VSM) nitric oxide (NO) resistance, which is mediated by NO scavenging reactions with plasma hemoglobin (Hb) and reactive oxygen species that can oxidize soluble guanylyl cyclase (sGC), the NO receptor. Prior studies show that cytochrome b5 reductase 3 (CYB5R3), known as methemoglobin reductase in erythrocytes, functions in VSM as an sGC heme iron reductase critical for reducing and sensitizing sGC to NO and generating cyclic guanosine monophosphate for vasodilation. Therefore, we hypothesized that VSM CYB5R3 deficiency accelerates development of pulmonary hypertension (PH) in SCD. Bone marrow transplant was used to create SCD chimeric mice with background smooth muscle cell (SMC)-specific tamoxifen-inducible Cyb5r3 knockout (SMC R3 KO) and wild-type (WT) control. Three weeks after completing tamoxifen treatment, we observed 60% knockdown of pulmonary arterial SMC CYB5R3, 5 to 6 mm Hg elevated right-ventricular (RV) maximum systolic pressure (RVmaxSP) and biventricular hypertrophy in SS chimeras with SMC R3 KO (SS/R3KD) relative to WT (SS/R3WT). RV contractility, heart rate, hematological parameters, and cell-free Hb were similar between groups. When identically generated SS/R3 chimeras were studied 12 weeks after completing tamoxifen treatment, RVmaxSP in SS/R3KD had not increased further, but RV hypertrophy relative to SS/R3WT persisted. These are the first studies to establish involvement of SMC CYB5R3 in SCD-associated development of PH, which can exist in mice by 5 weeks of SMC CYB5R3 protein deficiency.

Sickle cell disease: at the crossroads of pulmonary hypertension and diastolic heart failure

Sickle cell disease (SCD) is caused by a single point mutation in the gene that codes for beta globin synthesis, causing haemoglobin polymerisation, red blood cell stiffening and haemolysis under low oxygen and pH conditions. Downstream effects include widespread vasculopathy due to recurring vaso-occlusive events and haemolytic anaemia, affecting all organ systems. Cardiopulmonary complications are the leading cause of death in patients with SCD, primarily resulting from diastolic heart failure (HF) and/or pulmonary hypertension (PH). HF in SCD often features biventricular cardiac hypertrophy and left ventricular (LV) diastolic dysfunction. Among HF cases in the general population, approximately half occur with preserved ejection fraction (HFpEF). The insidious evolution of HFpEF differs from the relatively acute evolution of HF with reduced ejection fraction. The PH of SCD has diverse origins, which can be pulmonary arterial (precapillary), pulmonary venous (postcapillary) or pulmonary thromboembolic. It is also appreciated that patients with SCD can develop both precapillary and postcapillary PH, with elevations in LV diastolic pressures, as well as elevations in transpulmonary pressure gradient and pulmonary vascular resistance. Regardless of the cause of PH in SCD, its presence significantly reduces functional capacity and increases mortality. PH that occurs in the presence of HFpEF is usually of postcapillary origin. This review aims to assemble what has been learnt from clinical and animal studies about the manifestation of PH-HFpEF in SCD, specifically the contributions of LV diastolic dysfunction and myocardial fibrosis, in an attempt to gain an understanding of its evolution.

Elevated tricuspid regurgitation velocity in congenital hemolytic anemias: Prevalence and laboratory correlates

Elevated tricuspid valve regurgitation jet velocity (TRV ≥ 2.5 m/s) is associated with mortality among adults with sickle cell disease (SCD), but correlative biomarkers are not studied according to treatment exposure or genotypes. To investigate the associations between biomarkers and TRV elevation, we examined the relationship between TRV and hemolytic, inflammatory, and cardiac biomarkers, stratified by disease-modifying treatments and SCD genotype. In total, 294 participants with SCD (mean age, 11.0 ± 3.7 years) and 49 hereditary spherocytosis (HS; mean age, 22.9 ± 19.75 years) were included for comparison and enrolled. TRV was elevated in 30.7% of children with SCD overall: 18.8% in HbSC/HbSβ⁺ -thalassemia, 28.9% in untreated HbSS/HbSβ⁰ -thalassemia, 34.2% in HbSS/HbSβ⁰ -thalassemia hydroxyurea-treated, and 57% in HbSS/HbSβ⁰ -thalassemia chronic transfusion treated. TRV was elevated in 10.7% and 27.8% in HS children and adults, respectively. In children with SCD, elevated TRV was correlated with hemoglobin (odds ratio [OR] = 0.78, P = 0.004), lactate dehydrogenase (LDH; OR = 2.52, P = 0.005), and N-terminal pro-brain natriuretic peptide (NT-pro BNP; OR = 1.003, P = 0.004). In multivariable logistic regression, adjusting for genotype, sex, hemolytic index, and treatment, hemoglobin concentration remained the only significant variable associated with elevated TRV in untreated HbSS/HbSβ⁰ -thalassemia participants. TRV was not associated with inflammatory markers, other markers of hemolysis, or NT-pro BNP in untreated HbSS/HbSβ⁰ -thalassemia. Neither hemoglobin nor LDH was associated with TRV in HbSC/HbSβ⁺ -thalassemia. These results suggest that elevated TRV is influenced by the degree of anemia, possibly reflecting sickling as part of the disease pathophysiology. Prospective studies should monitor hemoglobin concentration as children with SCD age into adulthood, prompting initiation of TRV screening and monitoring.