Proinflammatory cytokines and the hypermetabolism of children with sickle cell disease

Sickle Cell Disease Update: New Treatments and Challenging Nutritional Interventions

Sickle cell disease (SCD), a distinctive and often overlooked illness in the 21st century, is a congenital blood disorder characterized by considerable phenotypic diversity. It comprises a group of disorders, with sickle cell anemia (SCA) being the most prevalent and serious genotype. Although there have been some systematic reviews of global data, worldwide statistics regarding SCD prevalence, morbidity, and mortality remain scarce. In developed countries with a lower number of sickle cell patients, cutting-edge technologies have led to the development of new treatments. However, in developing settings where sickle cell disease (SCD) is more prevalent, medical management, rather than a cure, still relies on the use of hydroxyurea, blood transfusions, and analgesics. This is a disease that affects red blood cells, consequently affecting most organs in diverse manners. We discuss its etiology and the advent of new technologies, but the aim of this study is to understand the various types of nutrition-related studies involving individuals suffering from SCD, particularly in Africa. The interplay of the environment, food, gut microbiota, along with their respective genomes collectively known as the gut microbiome, and host metabolism is responsible for mediating host metabolic phenotypes and modulating gut microbiota. In addition, it serves the purpose of providing essential nutrients. Moreover, it engages in direct interactions with host homeostasis and the immune system, as well as indirect interactions via metabolites. Nutrition interventions and nutritional care are mechanisms for addressing increased nutrient expenditures and are important aspects of supportive management for patients with SCD. Underprivileged areas in Sub-Saharan Africa should be accompanied by efforts to define and promote of the nutritional aspects of SCD. Their importance is key to maintaining well-being and quality of life, especially because new technologies and products remain limited, while the use of native medicinal plant resources is acknowledged.

Effect of Hydroxyurea Therapy on Growth Parameters in Older Children (6-15 Year-Old) with Sickle Cell Disease: Low Dose Versus High Dose

Growth impairment is a known complication of sickle cell disease (SCD). Few studies explored the potential effects of hydroxyurea (HU) on growth in children with SCD in relation to HU dose and response. This is a prospective study conducted at Sultan Qaboos University Hospital, Oman, and included 91 SCD patients with age below 16 years when started on HU, aiming to explore the potential effect/s of HU on growth parameters of older children with SCD in relation to their clinical improvement and the dose required for this improvement. Weight, height, and body mass index (BMI) were collected at baseline, 6 and 18 months after initiation. Anthropometric data were compared to WHO standards. Initial height and BMI Z scores (HAZ and WAZ) were lower compared to WHO norms. HAZ and WAZ did not change significantly after 6 and 18 months on HU therapy. However, BMI Z-scores improved significantly after 6 and 18 months of follow-up (p value 0.044 and 0.028 respectively). No significant changes were observed in WAZ or HAZ among patients on low dose versus those on high dose. BMI Z score improved significantly after 18 months of low dose group (p = 0.014) but did not change in those on high dose HU. In conclusion, HU therapy did not adversely affect weight and height growth in older children with SCD. BMI Z scores improved at 18 months in patients on low dose but not in those on high dose (p = 0.014).

Evaluating Associations between Average Pain Intensity and Genetic Variation in People with Sickle Cell Disease: An Exploratory Study

BACKGROUND

Pain is one of the most common and deleterious symptoms experienced by individuals with sickle cell disease (SCD). There is a paucity of studies identifying potential genetic mechanisms of pain in this population.

AIM

Examine associations between 11 functional single nucleotide polymorphisms in 9 candidate genes with reports of average pain intensity in individuals with sickle cell disease.

METHOD

Cross-sectional analyses were performed on data and blood samples collected through the Duke SCD Implementation Consortium Registry. Participants were asked to rate their pain "on the average" using an 11-point numeric rating scale (0 = no pain; 10 = pain as bad as you can imagine). We genotyped 11 single nucleotide polymorphisms in 9 pain-related genes using TaqMan® Genotyping Assays. Associations between each polymorphism and reports of average pain were evaluated.

RESULTS

The 86 participants (mean age: 28.7 years; 64% female) included in this study reported moderate pain on average (Mean = 4, Standard Deviation = 2.4). ICAM1 rs1799969 was the only genetic polymorphism that was significantly associated with pain (p = .01). Individuals with one or more minor alleles had lower average pain (Mean = 1.25, Standard Deviation = 1.50) than individuals without a minor allele (Mean = 4.13, Standard Deviation = 2.25). The effect size for ICAM1 rs1799969 was 1.30, which is considered large. The effect sizes for all other single nucleotide polymorphisms ranged from small to medium (range: 0-0.3).

CONCLUSIONS

Our findings provide preliminary evidence that the minor allele in ICAM1 rs1799969 had protective effects against experiencing more severe pain in sickle cell disease.

Omega 3 fatty acids - Potential modulators for oxidative stress and inflammation in the management of sickle cell disease

OBJECTIVE

Sickle cell disease is characterized by clinical complications resulting in vaso-occlusive crisis with prominent attributes of oxidative stress, inflammation, and pain. Inflammation is an integral part of this disease which further exacerbates the pain during a crisis. Omega-3 fatty acids are known to possess anti-inflammatory and anti-aggregatory properties and assist in diminishing the slow physiological inactivation.

METHODS

A pilot nutritional interventional study was conducted wherein forty-three children with sickle cell disease aged 5-16 years were supplemented with omega-3 fatty acids for a period of six months. Analysis of oxidative stress, as well as inflammatory parameters, was done pre and post-supplementation.

RESULTS

Increased free oxygen radical transference values depicting free radical generation is enhanced in these patients along with a reduced antioxidant defense, as seen by decreased free oxygen radical defense values. Supplementation with omega-3 fatty acids for a period of six months significantly reduced the inflammatory marker homocysteine in all patients, whereas high sensitive C reactive protein was significantly reduced only in females of the age group 11-16years. Simultaneously a significant reduction in oxidative stress parameters with a concomitant increase of antioxidant defense was observed in all patients.

CONCLUSION

The authors' findings suggest the regulatory effects of omega-3 fatty acids as cellular activators in alleviating the complications due to sickle cell disease. Omega-3 fatty acids hold promise as future therapeutic candidates in patients with sickle cell disease.

Adiponectin and Disease Severity in Sickle Cell Anemia Patients Attending a Tertiary Health Institution in Nnewi, Southeast Nigeria

Background: Hemoglobin polymerization in sickle cell anemia (SCA) leads to abnormally rigid and adhesive erythrocytes that obstruct blood vessels, leading to poor tissue perfusion, hence provoking inflammation and damage of surrounding tissues. Adiponectin, a protein hormone, presumptively has anti-inflammatory characteristics, hence may be an important therapeutic target in SCA.

Aim: The aim of the study was to evaluate the status of adiponectin and its correlation with disease severity in SCA.

Patients and Methods: A total of 84 subjects were recruited for the study comprising 34 homozygous sickle cell (HbSS) subjects (25 in the steady state and nine in the resolving crisis state) and 50 controls (25 heterozygous sickle cell [HbAS] and 25 hemoglobin phenotype AA subjects). The hemoglobin phenotype, adiponectin levels, and full blood counts were evaluated. Anthropometric measurements were also conducted.

Results: A significant difference was observed in the mean body mass index between the different hemoglobin phenotype groups and also between the SCA in crisis resolution patients and the control group (p < 0.05). There was no significant difference in the median serum levels of adiponectin in the different hemoglobin phenotype groups and between SCA patients in the steady state compared with those in the crisis resolution state. Also, there was no correlation between disease severity and adiponectin in SCA patients in the steady state (p = 0.87).

Conclusion: Our study seems to suggest that in our data set of sickle cell anemia patients in the steady state, adiponectin does not constitute part of the endocrinopathy that affects these patients.

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.

Severe Persistent Pain and Inflammatory Biomarkers in Sickle Cell Disease: An Exploratory Study

BACKGROUND

Severe pain is among the most common and deleterious symptoms experienced by individuals with sickle cell disease (SCD), of whom more than 50% report chronic pain. Despite this, the understanding of the biological contributors to persistent severe SCD pain is limited. This exploratory study sought to describe pain phenotypes based on frequency of severe pain experienced over 6 months and identify inflammatory biomarkers associated with pain phenotypes among individuals with SCD.

METHODS

This study used self-report and electronic health record data collected from 74 individuals enrolled in the Duke Sickle Cell Disease Implementation Consortium Registry. Plasma from previously collected blood specimens was used to generate inflammatory biomarker data using the Inflammation 20-plex ProcartaPlexTM panel. Descriptive statistics were used to describe the occurrence of severe pain over the past 6 months, and bi-variate analyses were used to evaluate the relationship between inflammatory biomarkers and pain phenotypes.

RESULTS

Among the 74 participants included in this study, 33.8% reported severe pain occurring never or rarely, 40.5% reported severe pain occurring sometimes, and 25.7% reported severe pain occurring often or always. Soluble E-selectin (sE-selectin) was the only inflammatory biomarker significantly associated with the pain phenotype groups (p = 0.049). Post hoc comparisons identified that participants in the often/always severe pain group had significantly higher plasma concentrations of sE-selectin compared to those in the sometimes severe pain group (p = 0.040).

CONCLUSIONS

Our findings provide preliminary evidence of the frequent occurrence of severe pain and that sE-selectin may be an objective biomarker for the frequent occurrence of severe pain in this population.

Interleukin 6 as a marker of severe bacterial infection in children with sickle cell disease and fever: a case-control study

Background

Etiological diagnosis of fever in children with sickle cell disease (SCD) is often challenging. The aim of this study was to analyze the pattern of inflammatory biomarkers in SCD febrile children and controls, in order to determine predictors of severe bacterial infection (SBI).

Methods

A prospective, case–control study was carried out during 3 years, including patients younger than 18 years with SCD and fever (cases) and asymptomatic steady-state SCD children (controls). Clinical characteristics and laboratory parameters, including 10 serum proinflammatory cytokines (IL-1β, IL-2, IL-4, IL-6, IL-8, IL-10, IL-12p70, IL-17a, IFN-γ and TNF-α) and comparisons among study subgroups were analyzed.

Results

A total of 137 patients (79 cases and 58 controls) were included in the study; 78.5% males, median age 4.1 (1.7–7.5) years. Four cases were diagnosed with SBI, 41 viral infection (VI), 33 no proven infection (NPI) and 1 bacterial-viral coinfection (the latter excluded from the subanalyses). IL-6 was significantly higher in patients with SBI than in patients with VI or NPI (163 vs 0.7 vs 0.7 pg/ml, p < 0.001), and undetectable in all controls. The rest of the cytokines analyzed did not show any significant difference. The optimal cut-off value of IL-6 for the diagnosis of SBI was 125 pg/mL, with high PPV and NPV (PPV of 100% for a prevalence rate of 5, 10 and 15% and NPV of 98.7%, 97.3% and 95.8% for those prevalences rates, respectively).

Conclusion

We found that IL-6 (with a cut-off value of 125 pg/ml) was an optimal marker for SBI in this cohort of febrile SCD children, with high PPV and NPV. Therefore, given its rapid elevation, IL-6 may be useful to early discriminate SCD children at risk of SBI, in order to guide their management.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12879-021-06470-4.

Obesity and diabetes mellitus in patients with sickle cell disease

Obesity and diabetes mellitus are prevalent among the African-American/Black population. They result in multiple chronic conditions that impact the quality and lifespan of the patients. Their occurrence in patients with sickle cell disease (SCD) will increase the risks for multimorbidity in these patients. We have carried out a chart survey of a cohort of 449 patients with SCD to determine the prevalence rates of obesity and diabetes mellitus in these patients. SCD patients were less likely to develop obesity and diabetes mellitus, compared to their peers of the same race/ethnicity. The lower prevalence rates were observed in those over the age of 6 years, irrespective of the gender of the patients. Their life-time probabilities for obesity and diabetes mellitus were also low. Within this group of SCD patients, obesity was associated with significantly higher prevalence of diabetes mellitus. The underlying reasons for our observed results of low prevalence rate of obesity in SCD remain speculative but may be related to reduced calorie intake, increased calorie use due to hypermetabolism, reduced intestinal absorption, or intestinal dysbiosis.

Nutritional perspectives on sickle cell disease in Africa: a systematic review

BACKGROUND

Sickle cell disease (SCD) is an inherited blood disorder that predominantly affects individuals in sub-Saharan Africa. However, research that elucidates links between SCD pathophysiology and nutritional status in African patients is lacking. This systematic review aimed to assess the landscape of studies in sub-Saharan Africa that focused on nutritional aspects of SCD, and highlights gaps in knowledge that could inform priority-setting for future research.

METHODS

The study was conducted using the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines. Inclusion criteria comprised original, peer-reviewed research published between January 1995 and November 2020 involving individuals in Africa with any phenotypic variant of SCD and at least one nutritional status outcome. Nutritional status outcomes were defined as those that assessed dietary intakes, growth/anthropometry, or nutritional biomarkers. Databases used were Ovid Embase, Medline, Biosis and Web of Science.

RESULTS

The search returned 526 articles, of which 76 were included in the final analyses. Most investigations (67%) were conducted in Nigeria. Studies were categorized into one of three main categories: descriptive studies of anthropometric characteristics (49%), descriptive studies of macro- or micronutrient status (41%), and interventional studies (11%). Findings consistently included growth impairment, especially among children and adolescents from sub-Saharan Africa. Studies assessing macro- and micronutrients generally had small sample sizes and were exploratory in nature. Only four randomized trials were identified, which measured the impact of lime juice, long-chain fatty acids supplementation, ready-to-use supplementary food (RUSF), and oral arginine on health outcomes.

CONCLUSIONS

The findings reveal a moderate number of descriptive studies, most with small sample sizes, that focused on various aspects of nutrition and SCD in African patients. There was a stark dearth of interventional studies that could be used to inform evidence-based changes in clinical practice. Findings from the investigations were generally consistent with data from other regional settings, describing a significant risk of growth faltering and malnutrition among individuals with SCD. There is an unmet need for clinical research to better understand the potential benefits of nutrition-related interventions for patients with SCD in sub-Saharan Africa to promote optimal growth and improve health outcomes.

Immunological Hallmarks of Inflammatory Status in Vaso-Occlusive Crisis of Sickle Cell Anemia Patients

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

In Vitro Lymphocyte Functions in Undernourished Children With Sickle Cell Anemia

Background: Children with sickle cell disease (SCD) often suffer from growth deficits and impaired immunity. However, the association between mild to moderate malnutrition and in vitro lymphocyte function has not been well studied. The goal of this study was to investigate the effects of undernutrition on lymphocyte functions in children with SCD. Methods: Weight; height; plasma concentrations of albumin (Alb), prealbumin (PA), transferrin (Tf), retinol-binding protein (RBP), α₁-acid glycoprotein (AGP), C-reactive protein (CRP), and ceruloplasmin (Cp); and lymphocyte proliferation and interleukin (IL)-2 in phytohemagglutinin-treated blood lymphocytes were measured in 90 children with SCD (59 SS, 4 Sβ°, 27 SC hemoglobin genotypes). Results: The mean age of the children included in the analysis was 7.65 years. Four of the 90 children had weight and height below the fifth percentile. A higher percentage of children with HbSS/HbSβ° (61.4%) than of those with HbSC (44%) had ≥2 plasma protein concentrations below normal (Alb <35 g/L, PA <160 mg/L, Tf <2.0 g/L, and RBP ≤20 mg/L). Mean anthropometric measurements, hemoglobin, and hematocrit were lower in children with HbSS/HbSβ° than in those with HbSC (P<0.05). Lymphocyte proliferation was reduced by 20% to 27% in children with HbSS/HbSβ° with undernutrition plus inflammation (AGP >1 g/L, CRP >5 mg/L, Cp >600 mg/L) compared to children with neither. Regardless of inflammatory status, lymphocyte proliferation was reduced by 29% to 49% in children with HbSS/HbSβ° and undernutrition defined by PA or Alb plus RBP (P<0.05) compared to those with RBP within normal range. Neither undernutrition nor inflammation reduced lymphocyte proliferation in children with HbSC. Mean IL-2 activity was reduced by undernutrition, defined as PA <160 mg/L, in both groups. PA, RBP, and hemoglobin concentrations positively correlated with in vitro lymphocyte functions (P<0.05). Conclusion: Undernutrition altered in vitro lymphocyte function in children with the HbSS/HbSβ° genotypes. Dietary supplements may improve the altered functions in these children.

High levels of proinflammatory cytokines IL-6 and IL-8 are associated with a poor clinical outcome in sickle cell anemia

Sickle cell anemia (SCA) pathophysiology is characterized by the activation of sickle red blood cells, reticulocytes, leukocytes, platelets, and endothelial cells, and with the expression of several inflammatory molecules. Therefore, it is conceivable that variations in levels of proinflammatory cytokines may act as a signaling of differential clinical course in SCA. Here, we evaluated the clinical impact of proinflammatory cytokines interleukin 1-β (IL-1β), interleukin 6 (IL-6), and interleukin 8 (IL-8) in 79 patients with SCA, followed in a single reference center from northeastern Brazil. The main clinical/laboratory data were obtained from patient interview and medical records. The proinflammatory markers IL-1β, IL-6, and IL-8 were evaluated by using commercially available enzyme-linked immunosorbent assay kits. According to levels of the proinflammatory markers, we observed that patients who had a higher frequency of VOC per year (P = 0.0236), acute chest syndrome (P = 0.01), leg ulcers (P = 0.0001), osteonecrosis (P = 0.0006), stroke (P = 0.0486), and priapism (P = 0.0347) had higher IL-6 levels compared with patients without these clinical complications. Furthermore, increased levels of IL-8 were found in patients who presented leg ulcers (P = 0.0184). No significant difference was found for IL-1β levels (P > 0.05). In summary, the present study emphasizes the role of inflammation in SCA pathophysiology, reveals an association of IL-8 levels and leg ulcer occurrence, and indicates that IL-6 levels can be used as a useful predictor for poor outcomes in SCA.

Identification of genetic biomarkers for alloimmunization in sickle cell disease

Most sickle cell disease (SCD) patients rely on blood transfusion as their main treatment strategy. However, frequent blood transfusion poses the risk of alloimmunization. On average, 30% of SCD patients will alloimmunize while other patient groups form antibodies less frequently. Identification of genetic markers may help to predict which patients are at risk to form alloantibodies. The aim of this study was to evaluate whether genetic variations in the Toll-like receptor pathway or in genes previously associated with antibody-mediated conditions are associated with red blood cell (RBC) alloimmunization in a cohort of SCD patients. In this case-control study, cases had a documented history of alloimmunization while controls had received ≥20 RBC units without alloantibody formation. We used a customized single nucleotide polymorphism (SNP) panel to genotype 690 SNPs in 275 (130 controls, 145 cases) patients. Frequencies were compared using multiple logistic regression analysis. In our primary analysis, no SNPs were found to be significantly associated with alloimmunization after correction for multiple testing. However, in a secondary analysis with a less stringent threshold for significance we found 19 moderately associated SNPs. Among others, SNPs in TLR1/TANK and MALT1 were associated with a higher alloimmunization risk, while SNPs in STAM/IFNAR1 and STAT4 conferred a lower alloimmunization risk.

Asthma in children with sickle cell disease

PURPOSE OF REVIEW

Asthma is common in children with sickle cell disease (SCD) and appears to be associated with increased morbidity. Providers caring for children with SCD have struggled with the question of whether asthma exists as a true comorbidity or whether certain aspects of the chronic inflammatory disease gives children with SCD an asthma-like phenotype.

RECENT FINDINGS

Clinical signs and symptoms seen in children with asthma in the general population, such as wheezing, airway hyperresponsiveness, atopy, elevated leukotrienes, and abnormal lung function are seen in children with SCD both with and without a diagnosis of asthma.

SUMMARY

Current evidence highlights that the presence of lung disease in children with SCD has significant implications irrespective of the underlying cause, including asthma. Further research should focus on well tolerated and effective interventions to prevent disease-related complications for children with pulmonary complications of SCD.

Sickle cell disease: Hemostatic and inflammatory changes, and their interrelation

Sickle cell disease, the most common genetic blood disorder in the world, has high clinical variability, negatively impacts quality of life and contributes to early mortality. Sickled erythrocytes cause blood flow obstruction, hemolysis, and several hemostatic changes that promote coagulation. These events, in turn, induce chronic inflammation, characterized by elevated plasma levels of pro-inflammatory markers, which aggravates the already unfavorable state of the circulatory system. Empirical evidence indicates that the hemostatic and inflammatory systems continuously interact with each other and thereby further propagate the hypercoagulability and inflammatory conditions. In this review article, we discuss the pathophysiological aspects of sickle cell disease and the hemostatic and inflammatory changes that underlie its pathogenesis.

Higher prevalence of spontaneous cerebral vasculopathy and cerebral infarcts in a mouse model of sickle cell disease

Stroke is a dramatic complication of sickle cell disease (SCD), which is associated with cerebral vasculopathies including moya moya, intravascular thrombi, cerebral hyperemia, and increased vessel tortuosity. The spontaneous occurrence of these pathologies in the sickle cell mouse model has not been described. Here, we studied Townes humanized sickle cell and age-matched control mice that were 13 months old. We used in vivo two-photon microscopy to assess blood flow dynamics, vascular topology, and evidence of cerebral vasculopathy. Results showed that compared to controls, sickle cell mice had significantly higher red blood cell (RBC) velocity (0.73 mm/s vs. 0.55 mm/s, p = 0.013), capillary vessel diameter (4.84 µM vs. 4.50 µM, p = 0.014), and RBC volume flux (0.015 nL/s vs. 0.010 nL/s, p = 0.021). Also, sickle cell mice had significantly more tortuous capillary vessels ( p < 0.0001) and significantly shorter capillary vessel branches ( p = 0.0065) compared to controls. Sickle cell mice also had significantly higher number of capillary occlusive events (3.4% vs. 1.9%, p < 0.0001) and RBC stalls (3.8% vs. 2.1%, p < 0.0001) in the cerebral capillary bed. In post-mortem immunohistochemical analyses, sickle cell mice had a 2.5-fold higher frequency of cortical microinfarcts compared to control mice. Our results suggest that aged Townes sickle cell mice spontaneously develop SCD-associated cerebral vasculopathy.

Risk factors of metabolic syndrome among adult Sudanese sickle cell anemia patients

BACKGROUND

Sickle cell disease is a hereditary disorder characterized by haematological anaemia. Several studies assumed that adult sickle patients might develop metabolic syndrome features as hyperglycaemia, hypertension and dyslipidaemia. The aim of this study was to evaluate the metabolic syndrome risk factors among adult Sudanese with sickle cell anemia in the steady state.

METHODS

A prospective cross sectional study design was conducted among thirty adult patients with sickle cell anemia Hb SS (mean age 23 ± 6.1 years) and thirty healthy individuals matched for age and gender. Waist and hip circumferences were measured by simple tape. Venous blood sample were analysed to detect blood glucose level, uric acid, total cholesterol, triglycerides, low and high-density lipoprotein after 8 h overnight fasting by spectrophotometer. Blood pressure was measured by sphygmomanometer. National Cholesterol Education Program-Adult Treatment Panel III was utilised to define metabolic syndrome. Statistical analysis was performed SPSS software version 23. Continuous data were expressed using mean ± SD. P-value of < 0.05 (two-tailed) was used to establish statistical significance. Unpaired independent T- test was used.

RESULTS

No significant difference in mean systolic blood pressure in patients group compared to control (P value = 0.3). Mean value of diastolic blood pressure was significantly low in patients group compared to control (65.4 ± 10. 4 VS72.33 ± 8.27 mmHg, P value< 0.001). Fasting triglycerides level was comparable between patients group and control (P value = 0.56). While high-density lipoprotein was significantly lower in sicklers compared to control (30.2 ± 8.2 mg/dL vs 44.71 ± 1.85 mg/dL, P value< 0.001). Fasting blood glucose was significantly low in sickle compared to control (92.6 ± 13 mg/dL vs 106.83 ± 25.11 mg/dL P value< 0.001). Uric acid level was not statistically differed in patients group compared to control (p value = 0.5).

CONCLUSION

There was significant decrease in fasting High-density lipoprotein, diastolic blood pressure, mean arterial pressure and fasting blood glucose among SCA patients compared to control. There was no significant difference in waist circumference, systolic blood pressure, fasting triglycerides and uric acid levels between patients and control groups.

The Epidemiology and Management of Lung Diseases in Sickle Cell Disease: Lessons Learned from Acute and Chronic Lung Disease in Cystic Fibrosis

Although sickle cell disease and cystic fibrosis are two of the most common monogenic diseases presenting in childhood worldwide, cystic fibrosis and sickle cell disease enjoy vastly different funding and collaborative research efforts. Pulmonary complications in cystic fibrosis have well established guidelines and multidisciplinary involvement focusing on comorbidities, routine monitoring, infectious complications, nutrition, and treatment recommendations. These guidelines can provide a framework on which to build knowledge of lung disease in sickle cell disease.

Loss of NRF2 function exacerbates the pathophysiology of sickle cell disease in a transgenic mouse model

The basic leucine zipper transcription factor nuclear factor (erythroid-derived 2)-like 2 (NRF2) plays a critical role in the cellular antioxidant response under oxidative stress conditions. In this study, we investigated the role of NRF2 in fetal hemoglobin expression and the pathophysiology of sickle cell disease (SCD) in a NRF2 knockout (SCD/NRF2^-/-) transgenic mouse model. NRF2 loss impaired survival of SCD pups during gestation and in the first 2 months of life. Furthermore, fetal hemoglobin expression was inhibited during erythropoiesis in embryonic day 13.5 and embryonic day 18.5 fetal liver and adult spleen and bone marrow cells, respectively. Examination of peripheral red blood cells revealed an increase of reactive oxygen species (ROS) and sickling under hypoxic conditions. Loss of NRF2 function in SCD/NRF2^-/- mice produced greater splenomegaly with red pulp expansion and obscured architecture. In addition, NRF2 knockout reduced the expression of its target antioxidant proteins, leading to increased levels of ROS, proinflammatory cytokines, and adhesion molecules in SCD mice. Genetic knockout of NRF2 demonstrates its role in developmentally regulated γ-globin gene expression and the ability to control oxidative stress and the phenotypic severity of SCD.

Body Mass Index and the Association With Vaso-occlusive Crises in Pediatric Sickle Cell Disease

BACKGROUND

Children with sickle cell disease (SCD) historically have been underweight and have poor overall growth. Recent studies have demonstrated a trend toward obesity in pediatric SCD populations.

MATERIALS AND METHODS

Through retrospective chart review of patients with SCD followed at our center, we collected patient's data, including body mass index (BMI), weight percentiles, sickle cell genotype, baseline hemoglobin, medical and psychiatric comorbidities, 25-hydroxy vitamin D level, treatment with hydroxyurea, and chronic transfusions. We identified hospitalizations to St. Christopher's Hospital for vaso-occlusive crisis (VOC) and duration of hospitalization and intravenous opioid use were recorded. Student t test, Mann-Whitney U test, and analysis of variance were used to examine associations between variables and frequency and duration of hospitalizations for VOC.

RESULTS

Among 328 patients with SCD, overweight and obese children constituted 19% of hospitalized and nonhospitalized patients. BMI status did not influence frequency (P=0.90) or duration of hospitalization (P=0.65) for VOC. Obesity was more associated with HbSC than HbSS (P=0.025) genotype.

CONCLUSIONS

Our study did not demonstrate an association between extremes of BMI of patients and hospitalization for VOC. Considering current trend toward obesity, further prospective and interventional research are required to define the effects of extremes of BMI on pain crises in SCD.

Relationship between serum 25-hydroxyvitamin D and inflammatory cytokines in paediatric sickle cell disease

BACKGROUND

Alteration in the concentration of inflammatory cytokines may contribute to pathogenesis in sickle cell anaemia (SCA). Vitamin D may suppress pro-inflammatory cytokines and enhance anti-inflammatory cytokines.

OBJECTIVE

To compare steady state levels of pro-and anti-inflammatory cytokines of Nigerian SCA children with age- and sex-matched healthy controls, and determine the relationship with 25-hydroxyvitamin-D (25-OHD). Effects of three months of vitamin D supplementation on cytokines of SCA children with suboptimal 25-OHD were also evaluated.

METHODS

Serum 25-OHD, IL-1β, 2, 6, 8, 11, 12, 13, 17, 18 of 95 SCA children and 75 matched controls were determined using HPLC. The 12 SCA children with suboptimal 25-OHD received 2000IU of vitamin D daily for 3months, and their post supplementation cytokines and 25-OHD levels were compared with the baseline values.

RESULTS

IL-2, 6, 8, 12, 17 and 18 were higher in SCA children than the controls (p≤0.001), but no significant variation in IL-11 and 13 (p=0.131 and 0.057 respectively). Patients with suboptimal serum 25-OHD had higher IL-6, 8 and 18 (p=0.003, 0.010 and 0.002 respectively) and lower levels of IL-11 (p=0.005). Significant positive treatment effects were observed: post-supplementation, serum 25-OHD increased by 23.3ng/mL, p<0.001; proinflammatory cytokines IL-2, 6, 8, 17 and 18 (p<0.001) were reduced and anti-inflammatory cytokine IL-11 was increased, p<0.001.

CONCLUSIONS

Suboptimal 25OHD is associated with enhanced levels of pro-inflammatory markers in children with SCA. Three months of daily vitamin D supplementation reversed the trend. Hence; Vitamin D supplementation may reduce the inflammatory milieu and serve as an anti-inflammatory agent in the management of SCA.

African Ancestry Gradient Is Associated with Lower Systemic F2-Isoprostane Levels

Context. Low levels of systemic F₂-isoprostanes (F₂-IsoP) increase the risk of diabetes and weight gain and were found in African Americans. Low F₂-IsoPs could reflect an unfavorable metabolic characteristic, namely, slow mitochondrial metabolism in individuals with African ancestry. Objective. To examine differences in plasma F₂-IsoPs in three groups with a priori different proportion of African ancestry: non-Hispanic Whites (NHWs), US-born African Americans (AAs), and West African immigrants (WAI). Design. Cross-sectional study. Setting. Georgia residents recruited from church communities. Participants. 218 males and females 25–74 years of age, who are self-identified as NHW (n = 83), AA (n = 56), or WAI (n = 79). Main Outcome Measure(s). Plasma F₂-IsoPs quantified by gas chromatography-mass spectrometry. Results. After adjustment for age, gender, obesity, and other comorbidities, WAI had lower levels of plasma F₂-IsoP than AA (beta-coefficient = −9.8, p < 0.001) and AA had lower levels than NHW (beta-coefficient = −30.3, p < 0.001). Similarly, among healthy nonobese participants, F₂-IsoP levels were lowest among WAI, followed by AA, and the highest levels were among NHW. Conclusion. Plasma F₂-IsoPs are inversely associated with African ancestry gradient. Additional studies are required to test whether optimization of systemic F₂-IsoP levels can serve as means to improve race-specific lifestyle and pharmacological intervention targeted to obesity prevention and treatment.

Quantitative sensory testing and pain-evoked cytokine reactivity: comparison of patients with sickle cell disease to healthy matched controls

Sickle cell disease (SCD) is an inherited blood disorder associated with significant morbidity, which includes severe episodic pain, and, often, chronic pain. Compared to healthy individuals, patients with SCD report enhanced sensitivity to thermal detection and pain thresholds and have altered inflammatory profiles, yet no studies to date have examined biomarker reactivity after laboratory-induced pain. We sought to examine this relationship in patients with SCD compared to healthy control participants. We completed quantitative sensory testing in 83 patients with SCD and sequential blood sampling in 27 of them, whom we matched (sex, age, race, body mass index, and education) to 27 healthy controls. Surprisingly, few quantitative sensory testing differences emerged between groups. Heat pain tolerance, pressure pain threshold at the trapezius, thumb, and quadriceps, and thermal temporal summation at 45°C differed between groups in the expected direction, whereas conditioned pain modulation and pain ratings to hot water hand immersion were counterintuitive, possibly because of tailoring the water temperature to a perceptual level; patients with SCD received milder temperatures. In the matched subsample, group differences and group-by-time interactions were observed in biomarkers including tumor necrosis factor alpha, interleukin-1ß, interleukin-4, and neuropeptide Y. These findings highlight the utility of laboratory pain testing methods for understanding individual differences in inflammatory cytokines. Our findings suggest amplified pain-evoked proinflammatory cytokine reactivity among patients with SCD relative to carefully matched controls. Future research is warranted to evaluate the impact of enhanced pain-related cytokine response and whether it is predictive of clinical characteristics and the frequency/severity of pain crises in patients with SCD.

Systemic F2-Isoprostane Levels in Predisposition to Obesity and Type 2 Diabetes: Emphasis on Racial Differences

This review focuses on racial differences in systemic levels of lipid peroxidation markers F₂-isoprostanes as metabolic characteristics predisposing to obesity and type 2 diabetes. Elevated levels F₂-isoprostanes were found in obesity, type 2 diabetes and their comorbidities. It was hypothesized that increased F₂-isoprostane levels reflect the obesity-induced oxidative stress that promotes the development of type 2 diabetes. However, African Americans have lower levels of systemic F₂-isoprostane levels despite their predisposition to obesity and type 2 diabetes. The review summarizes new findings from epidemiological studies and a novel interpretation of metabolic determinants of systemic F₂-isoprostane levels as a favorable phenotype. Multiple observations indicate that systemic F₂-isoprostane levels reflect intensity of oxidative metabolism, a major endogenous source of reactive oxygen species, and specifically, the intensity of fat utilization. Evidence from multiple human studies proposes that targeting fat metabolism can be a productive race-specific strategy to address the existing racial health disparities. Urinary F₂-isoprostanes may provide the basis for targeted interventions to prevent obesity and type 2 diabetes among populations of African descent.

Developing new pharmacotherapeutic approaches to treating sickle-cell disease

Survival for patients with SCD has been prolonged by improvements in supportive care, including vaccinations, antibiotic prophylaxis, and overall medical management, including tra nsfusion. However, there remains only one approved, partially effective drug for sickle cell disease-hydroxyurea (hydroxycarbamide). The world desperately needs better ways of both treating and preventing the recurrent painful vaso-occlusive episodes pathognomonic of sickle cell disease as well as the end-organ damage that still leads inexorably to severely shortened life expectancies throughout the world. Based on accumulating knowledge about how the abnormal red blood cells of sickle cell disease cause the double scourge of acute painful episodes and progressive end-organ damage, both pharmaceutical enterprises and individual investigators are now pursuing multiple new avenues for treating sickle cell disease. As a result, many compounds are in active development, both in preclinical models as well as in phase I, II, and III clinical trials. These agents target many pathophysiologic processes thought to be critical in sickle cell disease, including the chemical and physical behavior of haemoglobin S, cell adhesion, coagulation pathways, platelet activation, inflammatory pathways, and upregulation of haemoglobin F expression. In addition, recent explorations of the genetic variations that predispose to certain types of sickle cell disease-related tissue injury, such as stroke or nephropathy, are expected to lead to identification of drugs targeting the pathways uncovered by such work. Thus, the next five to ten years holds a promise of new treatments for sickle cell disease.

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.

Effects of nutritional intake on disease severity in children with sickle cell disease

Background

Children with Sickle Cell Disease (SCD) may show growth failure in comparison to healthy peers. Many factors as hematological status, endocrine and/or metabolic dysfunction, and nutritional status, may play an important role in growth failure. The aim of this study was to assess whether impaired growth and nutritional intake can affect SCD severity during childhood.

Methods

We conducted an observational study on children with SCD referring to our clinic for routine follow-up visits in a 6-month period. We collected information on weight, height and body mass index (BMI) and calculated their respective standardized scores (z). The nutritional intake was assessed through the last 24-h recall intake of total calories, macro- (proteins, lipids, carbohydrates) and micronutrients (calcium, iron, phosphorus, vitamins B1, PP, A, C, B2). Disease severity was assessed through total hemoglobin (Hb) and fetal hemoglobin (HbF), and lactic dehydrogenase (LDH) levels, and through the total number and days of hospitalizations, as well as the lifetime episodes of acute chest syndrome (ACS).

Results

Twenty nine children (14 males, 15 females) with SCD were enrolled; their mean age was 9.95 years (SD 3.50, min 3.72, max 17.18). Z-weight and z-BMI were significantly directly related to total Hb. Food intake resulted significantly unbalanced in terms of total calorie intake, macro- and micronutrients, especially calcium, iron, vitamin B1 and C. Low intake of calcium and vitamin B1 were significantly inversely correlated with number and days of hospitalizations per year. Protein, lipid, phosphorus, and vitamin PP intakes resulted adequate but were inversely correlated with number and days of hospitalizations. Carbohydrate, lipid, iron, phosphorus, vitamins B1 and B2 intakes were significantly inversely correlated to HbF levels.

Conclusions

This study showed that, in our population, inadequate nutritional intake, weight and BMI have a significant impact on SCD severity indices.

Red cell storage age policy for patients with sickle cell disease: A survey of transfusion service directors in the United States

In patients with sickle cell disease (SCD), the effects of the red cell storage lesion are not well defined. The objective of this study was to determine the prevalence of transfusion services that limit red cell units by storage age for patients with SCD. We developed a 22 question survey of transfusion service director opinions and their corresponding blood bank policies. Target subjects were systematically identified on the AABB website. Responses were recorded in SurveyMonkey and summarized using standard statistical techniques. Ninety transfusion service directors responded to the survey. Response rate was 22%. Only 23% of respondents had storage age policies in place for patients with SCD, even though 36% of respondents consider older units to be potentially harmful in this patient population. Of those with a policy, a less-than 15 day storage age requirement was most often used (75%), but practices varied, and most respondents (65%) agreed that evidence-based guidelines regarding storage age are needed for patients with SCD. Policies, practices and opinions about the risks of older units for patients with SCD vary. As patients with SCD may have unique susceptibilities to features of the red cell storage lesion, prospective studies in this population are needed to determine best practice.

Biomarkers and recent advances in the management and therapy of sickle cell disease

Although production of hemoglobin S, the genetic defect that causes sickle cell disease (SCD), directly affects only red blood cells, the manifestations of SCD are pervasive, and almost every cell type and organ system in the body can be involved. Today, the vast majority of patients with SCD who receive modern health care reach adulthood thanks to vaccine prophylaxis and improvements in supportive care, including transfusion. However, once patients reach adulthood, they commonly experience recurrent painful vaso-occlusive crises and frequently have widespread end-organ damage and severely shortened life expectancies. Over the last several decades, research has elucidated many of the mechanisms whereby abnormal red blood cells produce such ubiquitous organ damage. With these discoveries have come new ways to measure disease activity. In addition, new pharmaceutical interventions are now being developed to address what has been learned about disease mechanisms.

Alloimmunization is associated with older age of transfused red blood cells in sickle cell disease

Red blood cell (RBC) alloimmunization is a significant clinical complication of sickle cell disease (SCD). It can lead to difficulty with cross-matching for future transfusions and may sometimes trigger life-threatening delayed hemolytic transfusion reactions. We conducted a retrospective study to explore the association of clinical complications and age of RBC with alloimmunization in patients with SCD followed at a single institution from 2005 to 2012. One hundred and sixty six patients with a total of 488 RBC transfusions were evaluated. Nineteen patients (11%) developed new alloantibodies following blood transfusions during the period of review. The median age of RBC units was 20 days (interquartile range: 14-27 days). RBC antibody formation was significantly associated with the age of RBC units (P = 0.002), with a hazard ratio of 3.5 (95% CI: 1.71-7.11) for a RBC unit that was 7 days old and 9.8 (95% CI: 2.66-35.97) for a unit that was 35 days old, 28 days after the blood transfusion. No association was observed between RBC alloimmunization and acute vaso-occlusive complications. Although increased echocardiography-derived tricuspid regurgitant jet velocity (TRV) was associated with the presence of RBC alloantibodies (P = 0.02), TRV was not significantly associated with alloimmunization when adjusted for patient age and number of transfused RBC units. Our study suggests that RBC antibody formation is significantly associated with older age of RBCs at the time of transfusion. Prospective studies in patients with SCD are required to confirm this finding.

Haptoglobin gene polymorphisms and interleukin-6 and -8 levels in patients with sickle cell anemia

Background

Haptoglobin genotypes, and interleukin-6 and -8 participate in the pathophysiology of sickle cell anemia. The expression of cytokines is regulated by genetic mechanisms however the effect of haptoglobin polymorphisms on these cytokines is not fully understood. This study aimed to compare the frequency of haptoglobin genotypes and the interleukin-6 and -8 concentrations in sickle cell anemia patients and controls to investigate the association between haptoglobin genotypes and cytokine levels.

Methods

Sixty sickle cell anemia patients and 74 healthy individuals were analyzed. Haptoglobin genotypes were determined by multiplex polymerase chain reaction, and the interleukin-6 and -8 levels by enzyme linked immunosorbent assay. The association between haptoglobin genotypes and cytokines was investigated by statistical tests.

Results

Hp2-1 was the most common genotype in both the cases and controls while Hp1-1 was less frequent among sickle cell anemia patients. Interleukin-6 and -8 levels were higher in patients than controls (p-value <0.0001). There was no significant difference in interleukin-6 and -8 concentrations between the genotypes (p-value >0.05). A similar trend was observed among the controls.

Conclusion

Although, levels of interleukin-6 and -8 were higher in the sickle cell anemia patients, they appeared not to be related to the haptoglobin genotypes. Further investigations are necessary to identify factors responsible for increased secretion of the interleukin-6 and -8 pro-inflammatory cytokines in patients with sickle cell anemia.

Body composition and grip strength are improved in transgenic sickle mice fed a high-protein diet

Key pathophysiology of sickle cell anaemia includes compensatory erythropoiesis, vascular injury and chronic inflammation, which divert amino acids from tissue deposition for growth/weight gain and muscle formation. We hypothesised that sickle mice maintained on an isoenergetic diet with a high percentage of energy derived from protein (35 %), as opposed to a standard diet with 20 % of energy derived from protein, would improve body composition, bone mass and grip strength. Male Berkeley transgenic sickle mice (S; n 8-12) were fed either 20 % (S20) or 35 % (S35) diets for 3 months. Grip strength (BIOSEB meter) and body composition (dual-energy X-ray absorptiometry scan) were measured. After 3 months, control mice had the highest bone mineral density (BMD) and bone mineral content (BMC) (P < 0·005). S35 mice had the largest increase in grip strength. A two-way ANOVA of change in grip strength (P = 0·043) attributed this difference to genotype (P = 0·025) and a trend in type of diet (P = 0·067). l-Arginine (l-Arg) supplementation of the 20 % diet was explored, as a possible mechanism for improvement obtained with the 35 % diet. Townes transgenic sickle mice (TS; n 6-9) received 0·8, 1·6, 3·2 or 6·4 % l-Arg based on the same protocol and outcome measures used for the S mice. TS mice fed 1·6 % l-Arg for 3 months (TS1.6) had the highest weight gain, BMD, BMC and lean body mass compared with other groups. TS3.2 mice showed significantly more improvement in grip strength than TS0·8 and TS1.6 mice (P < 0·05). In conclusion, the high-protein diet improved body composition and grip strength. Outcomes observed with TS1.6 and TS3.2 mice, respectively, confirm the hypothesis and reveal l-Arg as part of the mechanism.

Interleukin-1β and interleukin-6 gene polymorphisms are associated with manifestations of sickle cell anemia

Sickle cell anemia (SCA), a disorder characterized by both acute and chronic inflammation, exhibits substantial phenotypic variability. Interleukin-1 beta (IL-1β) and IL-6 are important in acute and chronic diseases, and their single nucleotide polymorphisms (SNPs) have been considered as predictors of prognosis in several inflammatory conditions. This study aims at exploring possible association of IL-1β and IL-6 SNPs as potential genetic modifiers and or predictors of SCA clinical and laboratory phenotypes. This cross-sectional study involved 107 SCA patients and 110 age, sex and ethnicity-matched healthy individuals. The SNPs were identified by PCR-RFLP for IL-1β (-511C>T and +3954C>T) and IL-6 (-597G>A and -174G>C) genes. Associations between these SNPs and the clinical and laboratory profiles of patients with SCA were then determined. Allelic and genotypic frequencies of IL-1β and IL-6 SNPs between patients with SCA and controls were similar and followed HWE. IL-1β +3954C>T SNP was associated with increased risk of osteonecrosis, elevated pulmonary arterial pressure and lower absolute reticulocyte count, while IL-6 -597G>A was associated with higher likelihood of retinopathy and leg ulcer. These data indicate that IL-1β and IL-6 gene SNPs are associated with SCA complications among Brazilian patients and may act as genetic predictors of SCA clinical heterogeneity.

Genetics of transfusion recipient alloimmunization: can clues from susceptibility to autoimmunity pave the way?

The search for genetic determinants of alloimmunization in sickle cell disease transfusion recipients was based on two premises: i) that polymorphisms responsible for stronger immune and/or inflammatory responses and hemoglobin β(S) mutation were co-selected by malaria; and ii) that stronger responder status contributes to development of lupus. We found a marker of alloimmunization in the gene encoding for Ro52 protein, also known as Sjögren syndrome antigen 1 (SSA1) and TRIM21. Surprisingly, the nature of the association was opposite of that with lupus; the same variant of a polymorphism (rs660) that was associated with lupus incidence was also associated with induction of tolerance to red blood cell antigens during early childhood. The dual function of Ro52 can explain this apparent contradiction. We propose that other lupus/autoimmunity susceptibility loci may reveal roles of additional molecules in various aspects of alloimmunization induced by transfusion as well as during pregnancy.

High protein diet attenuates histopathologic organ damage and vascular leakage in transgenic murine model of sickle cell anemia

Previous reports have shown that a high protein diet improves weight gain and decreases expression of inflammatory markers in weanling Berkeley transgenic sickle cell mice. The effect of this diet on the underlying histopathology, however, has not been studied. Age-matched, male C57BL/6 controls (n = 24), Berkley sickle mice (n = 31) and Townes sickle mice (n = 14) were randomized in a terminal experiment at weaning to isoenergetic diets, with either normal (20%) or high (35%) amount of energy from protein, by replacing dextrin. Tissue sampling for blinded histologic study and scoring of changes at baseline and after 3 months of feedings showed progressive siderosis and infarcts in spleen, kidney, and liver in all sickle groups, and no significant changes in age- and sex-matched normal controls. High-protein (35%) fed Berkeley sickle mice had significantly fewer (p < 0.01) infarcts in spleen (35.7% less), liver (12.5% less), and kidney (28.6% less) and lower histopathologic scores (p < 0.01) for chronic tissue injury in liver and spleen than matched normal-protein (20%) fed Berkeley sickle mice. In addition, high-protein fed Townes sickle mice had less vascular leakage (∼36%) in the heart, lungs, and brain and a better survival rate (21%) than matched normal-protein Townes sickle mice. This is the first report of histopathologic evidence that a high protein:calorie diet attenuates sickle cell related chronic organ injury in transgenic sickle cell mouse models.

Hypoxia and inflammation in children with sickle cell disease: implications for hippocampal functioning and episodic memory

Children with sickle cell disease (SCD) suffer from systemic processes (e.g., chronic anemia, recurrent hypoxic-ischemic events, chronic inflammation) that have been associated with neurocognitive impairment in a range of clinical populations, but which have been largely understudied in relation to specific domains of cognitive functioning in children with SCD. This review focuses on episodic memory, as the hippocampus may be especially vulnerable to the systemic processes associated with SCD. The first part of the paper outlines the pathophysiology of SCD and briefly reviews the extant literature on academic and cognitive functioning in children with SCD, emphasizing the dearth of research on episodic memory. Next, the complex systemic processes of hypoxia and inflammation associated with SCD are reviewed, along with research that has associated these processes with hippocampal damage and memory impairment. The paper concludes with suggestions for future research that are informed, in part, by the literature on developmental amnesia.

High multi-cytokine levels are not a predictive marker of alloimmunization in transfused sickle cell disease patients

Patients with sickle cell disease (SCD) receive multiple red blood cell (RBC) transfusions for both prevention of and therapy for disease-related complications. In some patients, transfusion results in development of both allo- and auto-antibodies to RBC antigens. What precipitates the antibody formation is currently unclear. It has been hypothesized that a pro-inflammatory state preceding the therapeutic transfusion may be a predisposing factor. Plasma levels of ten cytokines were evaluated upon recruitment to the study of 83 children with SCD undergoing therapeutic RBC transfusions. The levels of cytokines were correlated with development of anti-RBC antibodies prior, or during seven years post recruitment. Twelve subjects displayed significantly higher levels of all cytokines examined, with pro-, as well as anti-inflammatory properties. Surprisingly, the elevated levels of cytokines were preferentially found in patients without anti-RBC allo- and/or auto-antibodies. Further, presence of high cytokine levels was not predictive of anti-RBC antibody development during the subsequent seven year follow up. These data suggest that the increased concentration of multiple cytokines is not a biomarker of either the presence of or susceptibility to the development of RBC alloimmunization.

TNF-α, IFN-γ, IL-10, and IL-4 levels were elevated in a murine model of human sickle cell anemia maintained on a high protein/calorie diet

Increased frequency and risk of infection is one of the well described complications of sickle cell anemia (SCA). Dietary supplementation in children with SCA and growth retardation improved growth and decreased incidence of infection. We investigated the impact of a high protein diet on weight gain, hematological profile, and immune cytokine levels in the Berkeley model of SCA, 16 of which were randomized to either regular mouse diet with 20% of calories from protein (n = 8) or a test feed with 35% of calories from protein (n = 8). Control mice (C57BL/6, n = 16) were correspondingly randomized, and were all feed ad libitum for three months with actual intake estimated by subtracting the weight of gnaw waste from that of the feed given. Blood was collected at sacrifice by cardiac puncture and plasma levels of T helper cell 1 (TH1) and TH2 associated cytokines were measured using a multiplex antibody immobilized bead assay. SCA mice receiving the 35% protein diet had modest improvements in weight, red blood cell count, and hemoglobin level, with a slight decrease in reticulocyte count compared with SCA mice on the regular mouse diet. Furthermore, they also had significantly higher plasma levels of cytokines tumor necrosis factor (TNF)-α (P = 0.02), interferon (IFN)-γ (P = 0.01), interleukin 10 (IL-10; P = 0.02), and IL-4 (P = 0.02) compared with those that received the 20% protein diet. We conclude that providing additional protein calories to transgenic SCA mice increased the plasma levels of acute inflammatory cytokines associated with immune response to infection, which might partly explain decreased episodes of infection observed among supplemented children with SCA.

Frequent red cell transfusions reduced vascular endothelial activation and thrombogenicity in children with sickle cell anemia and high stroke risk

Stroke is one of the most disabling complications of sickle cell anemia (SCA). The molecular mechanisms leading to stroke in SCA or by which packed red blood cell (PRBC) transfusion prevents strokes are not understood. We investigated the effects of PRBC transfusion on serum biomarkers in children with SCA who were at high-risk for stroke. Serum samples from 80 subjects were analyzed, including baseline, study exit time point and 1 year after study exit. Forty of the 80 samples were from subjects randomized to standard care and 40 from transfusion arm. Samples were assayed for levels of BDNF, sVCAM-1, sICAM-1, MPO, Cathepsin-D, PDGF-AA, PDGF-AB/BB, RANTES (CCL5), tPAI-1, and NCAM-1 using antibody immobilized bead assay. Significantly lower mean serum levels of sVCAM-1 (2.2 × 10(6) ± 0.8 × 10(6) pg/mL vs. 3.1 × 10(6) ± 0.9 × 10(6) pg/mL, P < 0.0001), Cathepsin-D (0.5 × 10(6) ± 0.1 × 10(6) pg/mL vs. 0.7 × 10(6) ± 0.2 × 10(6) pg/mL, P < 0.0001), PDGF-AA (10556 ± 4033 pg/mL vs. 14173 ± 4631 pg/mL, P = 0.0008), RANTES (0.1 × 10(6) ± 0.07 × 10(6) pg/mL vs. 0.2 × 10(6) ± 0.06 × 10(6) pg/mL, P < 0.006), and NCAM-1 (0.7 × 10(6) ± 0.2 × 10(6) pg/mL vs. 0.8 × 10(6) ± 0.1 × 10(6) pg/mL, P < 0.0006) were observed among participants who received PRBC transfusion, compared to those who received standard care. Twenty or more PRBC transfusion over 4 years was associated with lower serum levels of sVCAM-1 (P < 0.001), PDGF-AA (P = 0.025), and RANTES (P = 0.048). Low baseline level of BDNF (P = 0.025), sVCAM-1 (P = 0.025), PDGF-AA (P = 0.01), t-PAI-1 (P = 0.025) and sICAM-1 (P = 0.022) was associated with higher probability of stroke free survival. Beyond improving hemoglobin levels, our results suggest that the protective effects of PRBC transfusion on reducing stroke in SCD may result from reduced thrombogenesis and vascular remodeling.

The association of CD81 polymorphisms with alloimmunization in sickle cell disease

The goal of the present work was to identify the candidate genetic markers predictive of alloimmunization in sickle cell disease (SCD). Red blood cell (RBC) transfusion is indicated for acute treatment, prevention, and abrogation of some complications of SCD. A well-known consequence of multiple RBC transfusions is alloimmunization. Given that a subset of SCD patients develop multiple RBC allo-/autoantibodies, while others do not in a similar multiple transfusional setting, we investigated a possible genetic basis for alloimmunization. Biomarker(s) which predicts (predict) susceptibility to alloimmunization could identify patients at risk before the onset of a transfusion program and thus may have important implications for clinical management. In addition, such markers could shed light on the mechanism(s) underlying alloimmunization. We genotyped 27 single nucleotide polymorphisms (SNPs) in the CD81, CHRNA10, and ARHG genes in two groups of SCD patients. One group (35) of patients developed alloantibodies, and another (40) had no alloantibodies despite having received multiple transfusions. Two SNPs in the CD81 gene, that encodes molecule involved in the signal modulation of B lymphocytes, show a strong association with alloimmunization. If confirmed in prospective studies with larger cohorts, the two SNPs identified in this retrospective study could serve as predictive biomarkers for alloimmunization.

Malnutrition in Sickle Cell Anemia: Implications for Infection, Growth, and Maturation

Sickle cell anemia (SCA) is a genetic disease that affects mostly individuals of African and/or Hispanic descent, with the majority of cases in sub-Saharan Africa. Individuals with this disease show slowed growth, delayed sexual maturity, and poor immunologic function. These complications could partly be explained by the state of undernutrition associated with the disease. Proposed mechanism of undernutrition include protein hypermetabolism, decreased dietary intake possibly from interleukin-6-related appetite suppression, increased cardiac energy demand/expenditure, and increased red cell turnover. All the above mechanisms manifest as increased resting energy expenditure. Nutritional intervention utilizing single or multiple nutrient supplementation has led to improved clinical outcome, growth, and sexual maturation. Studies are currently underway to determine the best possible approach to applying nutritional intervention in the management of SCA. Management of SCA will, of necessity, involve a nutritional component, given the sociodemographic distribution of those most affected by the disease, the ease of a nutritional approach, and the wider reach that such an approach will embody.

Plasma BDNF and PDGF-AA levels are associated with high TCD velocity and stroke in children with sickle cell anemia

Sickle cell anemia (SCA) associated cerebrovascular disease includes vascular remodeling, abnormal cerebral blood flow (CBF) and infarction. We studied the relationships between plasma brain derived neurotropic factor (BDNF), platelet derived growth factors (PDGF-AA and -AB/BB) and high trans-cranial Doppler (TCD) velocity, an indication of CBF velocity. Baseline plasma samples from 39 children (19 SCA with abnormal/high TCD [SATCD], 13 SCA with normal TCD [SNTCD] and 7 healthy non-SCA), were assayed for BDNF, PDGF-AA and -AB/BB plus 11 other cytokines. The sensitivity, specificity and usefulness of these biomarkers for stroke prediction was investigated. All subject groups were of similar age and gender distribution. Mean BDNF was significantly higher among SATCD than SNTCD (p=0.004) as was mean PDGF-AA (p=0.001). Similarly, mean PDGF-AA was higher among SCA subjects who developed stroke than those who did not (p=0.012). Elevated BDNF and PDGF-AA were good predictors of the presence of abnormally high CBF velocity and were both associated with severity of anemia. Elevated PDGF-AA predicted risk for stroke development. Stroke incidence and high TCD velocity were associated with elevated BDNF and PDGF-AA. These findings suggest a role for BDNF and PDGF-AA in the patho-physiological mechanism of cerebrovascular disease in SCA.

Red blood cell alloimmunization in sickle cell disease: pathophysiology, risk factors, and transfusion management

Red blood cell transfusions have reduced morbidity and mortality for patients with sickle cell disease. Transfusions can lead to erythrocyte alloimmunization, however, with serious complications for the patient including life-threatening delayed hemolytic transfusion reactions and difficulty in finding compatible units, which can cause transfusion delays. In this review, we discuss the risk factors associated with alloimmunization with emphasis on possible mechanisms that can trigger delayed hemolytic transfusion reactions in sickle cell disease, and we describe the challenges in transfusion management of these patients, including opportunities and emerging approaches for minimizing this life-threatening complication.