Sickle cell disease (SCD) is characterized by sickle hemoglobin (HbS) which polymerizes under deoxygenated conditions to form a stiff, sickled erythrocyte. The dehydration of sickle erythrocytes increases intracellular HbS concentration and the propensity of erythrocyte sickling. Prevention of this mechanism may provide a target for potential SCD therapy investigation. Ionophores such as monensin can increase erythrocyte sodium permeability by facilitating its transmembrane transport, leading to osmotic swelling of the erythrocyte and decreased hemoglobin concentration. In this study, we treated thirteen blood samples from patients with SCD with 10 nM of monensin ex vivo. We measured changes in cell volume and hemoglobin concentration in response to monensin treatment, and we perfused treated blood samples through a microfluidic device that permits quantification of blood flow under controlled hypoxia. Monensin treatment led to increases in cell volume and reductions in hemoglobin concentration in most blood samples, though the degree of response varied across samples. Monensin treated samples also demonstrated reduced blood flow impairment under hypoxic conditions relative to untreated controls. Moreover, here was a significant correlation between the improvement in blood flow and the decrease in hemoglobin concentration. Thus, our results demonstrate that a reduction in intracellular HbS concentration by osmotic swelling improves blood flow under hypoxic conditions. Although the toxicity of monensin prevents it from being a viable clinical treatment, these results suggest that osmotic swelling should be investigated further as a potential mechanism for SCD therapy.

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Human parvovirus B19 causes life-threatening anemia due to transient red cell aplasia (TRCA) in individuals with sickle cell disease (SCD). Children with SCD experiencing profound anemia during TRCA often require red blood cell transfusions and hospitalization. The prevalence of vitamin deficiencies in SCD is high and deficiencies are associated with respiratory and pain symptoms, but the effects of vitamins on acute infection with parvovirus B19 remain unclear. We performed a clinical study in which 20 SCD patients hospitalized with parvovirus B19 infections (Day 0) were monitored over a 120-day time course to query relationships between vitamins A and D and clinical outcomes. There were significant negative correlations between Day 0 vitamin levels and disease consequences (e.g., red blood cell transfusion requirements, inflammatory cytokines). There were significant positive correlations (i) between Day 0 vitamins and peak virus-specific antibodies in nasal wash, and (ii) between Day 0 virus-specific serum plus nasal wash antibodies and absolute reticulocyte counts. There was a significant negative correlation between Day 0 virus-specific serum antibodies and virus loads. To explain the results, we propose circular and complex mechanisms. Low baseline vitamin levels may weaken virus-specific immune responses to permit virus amplification and reticulocyte loss; consequent damage may further reduce vitamin levels and virus-specific immunity. While the complex benefits of vitamins are not fully understood, we propose that maintenance of replete vitamin A and D levels in children with SCD will serve as prophylaxis against parvovirus B19-induced TRCA complications.

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Introduction Emerging literature suggests body mass index (BMI) may be increasing in individuals with sickle cell disease (SCD), a condition historically associated with underweight status. However, the current prevalence of overweight and obese adults with SCD remains unclear in a country where high BMI is prevalent in the general population. We present an epidemiological analysis of the prevalence of overweight and obese individuals in a large representative sample of adult SCD patients, identifying associations between BMI, sociodemographic and clinical characteristics. Methods Using the Sickle Cell Disease Consortium (SCDIC) registry, we compiled a detailed clinical and demographical from a non-random sample of adults, aged 20-45 years. The SCDIC collects data from eight academic centers providing comprehensive care throughout the U.S. Adult participants were excluded from the analysis if they were under 20 years of age, pregnant at the time of enrollment, or were without medical records or patient enrollment surveys. Sociodemographic information and patient-reported outcomes, including pain frequency and severity, SCD complications, and hydroxyurea use, were collected at the time of enrollment. Non-SCD medical conditions and anthropometric measurements were abstracted from medical records. We stratified BMI, measured in kilograms per meters squared (kg/m2) following CDC criteria: underweight (<18.5 kg/m2), normal weight (18.5-24.9 kg/m2), overweight (25.0-29.9 kg/m2), and obese (>30 kg/m2). An epidemiological analysis was performed of BMI in those with SCD. Bivariate analyses were conducted using Chi-square test, t-test, and ANOVA; non-parametric tests were used when appropriate. Data were analyzed using SAS 9.4 (SAS Institute; Cary, NC). Results In total, 1,664 adults met the inclusion criteria for this cross-sectional analysis of SCDIC registry data. The median BMI for the entire sample was 23.9 kg/m² (IQR: 21.1-28). The majority of participants were African American (99.1%), female (56.6%), and had an HbSS genotype (69.6%). The prevalence of an obese BMI (17.5%) was greater than underweight BMI (6.4%) among the entire cohort (Table 1). When compared to under/normal weight participants, those who were overweight/obese were older (median age 31.2 versus 29.3 years; p<0.0001) and had a higher prevalence of hypertension (45.1% versus 28.3%; p<0.0001). Most participants in the overweight/obese BMI categories had genotype HbSS (59.0%), however, genotype HbSS accounted for 77% of the under/normal weight category. Most participants with an overweight/obese BMI also had some college or vocational training (39.9%) and had Medicare, Medicaid, or military insurance (71.9%). Median BMI did not differ on reported use or non-use of hydroxyurea (23.9 [IQR: 21.1-27.6] vs 23.9 [IQR: 21.0-28.4] p=0.1), mean number of patient-reported SCD complications (2.6 versus 2.6; p=0.6), nor mean pain frequency (49.6 versus 50.6; p=0.06). However, overweight/obese participants reported significantly higher mean pain intensity than their under/normal weight counterparts (51.8 versus 50.8; p=0.03). Conclusion To date, this is the largest analysis of adult BMI among individuals with SCD in the U.S. Among the eight SCDIC sites spanning from the Northeast to Southwest U.S., the prevalence of underweight BMI was less than that of overweight or obese BMI status, challenging previous understandings of weight status and further aligning with the growing rates of overweight and obesity in the general U.S. population. Significant associations between high BMI and hypertension, age, and pain intensity highlight an opportunity for further research to understand the impact of increasing BMI on SCD outcomes and non-SCD comorbidities. Figure 1 Figure 1. Disclosures Ibemere: bluebird bio Insights Council: Consultancy, Honoraria; Ugali Youth: Consultancy, Membership on an entity's Board of Directors or advisory committees. King: Health Resources and Services Administration: Research Funding; National Cancer Institute: Research Funding; Global Blood Therapeutics: Research Funding; National Heart, Lung, and Blood Institute: Research Funding. Hankins: Global Blood Therapeutics: Consultancy; UpToDate: Consultancy; Bluebird Bio: Consultancy; Vindico Medical Education: Consultancy. Tanabe: CSL Behring: Consultancy. Shah: Emmaus: Consultancy; GLG: Consultancy; Alexion: Speakers Bureau; Guidepoint Global: Consultancy; Bluebird Bio: Consultancy; CSL Behring: Consultancy; Novartis: Research Funding, Speakers Bureau; GBT: Consultancy, Research Funding, Speakers Bureau.

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Summary Individuals with sickle cell disease (SCD) have historically been considered underweight. Despite increasing body mass index (BMI) in the general population, the prevalence of overweight and obese status remains unclear in the adult SCD population. Our primary aim was to determine the prevalence of overweight and obese status and to identify associations between BMI, demographic, and clinical characteristics. We conducted an analysis of abstracted electronic health record data and patient‐reported outcomes from the Sickle Cell Disease Implementation Consortium registry; individuals aged 20–45 years were included. The median (interquartile range) BMI for the 1664 adults in this analysis was 23.9 (21.1–28) kg/m2. In this cohort, 42.9% had a BMI of >25 kg/m2 (Centers for Disease Control and Prevention definition of overweight/obese). In multivariable analysis, higher odds of being overweight or obese were associated with female gender, older age, college education, private insurance, and hypertension diagnosis. Higher odds of a BMI of >25 kg/m2 were observed in individuals with HbSC or HbSβ+ thalassaemia regardless of hydroxycarbamide (hydroxyurea) exposure (odds ratio [OR] 3.4, p < 0.0001) and HbSS or HbSβ0 thalassaemia exposed to hydroxycarbamide (OR 1.6, p = 0.0003) compared to those with HbSS or HbSβ0 thalassaemia with no hydroxycarbamide exposure. These data highlight the importance of early identification, prevention, and intervention for increasing BMI to reduce obesity‐related complications that may impact SCD‐related complications.