Sickle cell disease: a chronic inflammatory condition

Indicators for Osteomyelitis in Children With Sickle Cell Disease Admitted With Vaso-Occlusive Crises

INTRODUCTION

Sickle cell disease (SCD) is an autosomal recessive genetic disorder characterized by the presence of a mutated form of hemoglobin (Hb) known as sickle hemoglobin (HbS). Individuals with SCD are susceptible to a variety of osteoarticular complications. Osteomyelitis is a commonly seen infection affecting the tibia, diaphysis of the femur and humerus, and vertebras.

AIM

The aim of this study was to define the indicators suggesting the diagnosis of osteomyelitis in patients with SCD.

METHODS

This study is a descriptive, analytical, non-interventional, prospective study of pediatric patients with SCD admitted with vaso-occlusive crisis (VOC) and/or osteomyelitis, which were identified by laboratory and radiological features. Retrospective data was included for patients who met the inclusion criteria. The statistical analysis included a description of the primary and secondary outcomes in the cohort.

RESULTS

A total of 28 children were included in this study. Participants' ages ranged from 11 months to 13 years. Males represented the majority (64.3%) of the participants. The blood culture of most of the participants (89.3%) showed no growth; however, 7.1% had salmonella, and only 3.6% had Gram-positive cocci. Most cases (75%) had leukocytosis. Thrombocytosis was present mainly in patients with VOC (40%). CRP was 1-4.9 mg/dL, mainly in patients with osteomyelitis (50%). The ferritin level exceeded 5000 ng/mL in patients with osteomyelitis or both osteomyelitis and VOC (50%). Ultrasound examinations revealed no hip effusion in 24 of the 28 examined patients. A plain X-ray examination showed no abnormality in 24 out of the 28 examined cases; with MRI, three cases exhibited marrow edema with bone enhancement, two (66.7%) were complicated by osteomyelitis, and the last (33.3%) had osteomyelitis and VOC. Aspiration was performed only in seven of the 28 examined, of which six (85.7%) were complicated by osteomyelitis, while the last one (14.3%) had acute chest syndrome.

CONCLUSION

Based on the outcomes of this study, we recommend an individualized multidisciplinary examination (hematology, infectious disease, orthopedic surgery, and interventional radiology) for SCD patients with suspected osteomyelitis admitted with VOC, considering the entire clinical history and laboratory and MRI results.

Antioxidant supplementation for sickle cell disease

BACKGROUND

Sickle cell disease (SCD) refers to a group of genetic disorders characterized by the presence of an abnormal haemoglobin molecule called haemoglobin S (HbS). When subjected to oxidative stress from low oxygen concentrations, HbS molecules form rigid polymers, giving the red cell the typical sickle shape. Antioxidants have been shown to reduce oxidative stress and improve outcomes in other diseases associated with oxidative stress. Therefore, it is important to review and synthesize the available evidence on the effect of antioxidants on the clinical outcomes of people with SCD.

OBJECTIVES

To assess the effectiveness and safety of antioxidant supplementation for improving health outcomes in people with SCD.

SEARCH METHODS

We used standard, extensive Cochrane search methods. The latest search date was 15 August 2023.

SELECTION CRITERIA

We included randomized and quasi-randomized controlled trials comparing antioxidant supplementation to placebo, other antioxidants, or different doses of antioxidants, in people with SCD.

DATA COLLECTION AND ANALYSIS

Two authors independently extracted data, assessed the risk of bias and certainty of the evidence, and reported according to Cochrane methodological procedures.

MAIN RESULTS

The review included 1609 participants in 26 studies, with 17 comparisons. We rated 13 studies as having a high risk of bias overall, and 13 studies as having an unclear risk of bias overall due to study limitations. We used GRADE to rate the certainty of evidence. Only eight studies reported on our important outcomes at six months. Vitamin C (1400 mg) plus vitamin E (800 mg) versus placebo Based on evidence from one study in 83 participants, vitamin C (1400 mg) plus vitamin E (800 mg) may not be better than placebo at reducing the frequency of crisis (risk ratio (RR) 1.18, 95% confidence interval (CI) 0.64 to 2.18), the severity of pain (RR 1.33, 95% CI 0.40 to 4.37), or adverse effects (AE), of which the most common were headache, nausea, fatigue, diarrhoea, and epigastric pain (RR 0.56, 95% CI 0.31 to 1.00). Vitamin C plus vitamin E may increase the risk of SCD-related complications (acute chest syndrome: RR 2.66, 95% CI 0.77 to 9.13; 1 study, 83 participants), and increase haemoglobin level (median (interquartile range) 90 (81 to 96) g/L versus 93.5 (84 to 105) g/L) (1 study, 83 participants) compared to placebo. However, the evidence for all the above effects is very uncertain. The study did not report on quality of life (QoL) of participants and their caregivers, nor on frequency of hospitalization. Zinc versus placebo Zinc may not be better than placebo at reducing the frequency of crisis at six months (rate ratio 0.62, 95% CI 0.17 to 2.29; 1 study, 36 participants; low-certainty evidence). We are uncertain whether zinc is better than placebo at improving sickle cell-related complications (complete healing of leg ulcers at six months: RR 2.00, 95% CI 0.60 to 6.72; 1 study, 34 participants; very low-certainty evidence). Zinc may be better than placebo at increasing haemoglobin level (g/dL) (MD 1.26, 95% CI 0.44 to 1.26; 1 study, 36 participants; low-certainty evidence). The study did not report on severity of pain, QoL, AE, and frequency of hospitalization. N-acetylcysteine versus placebo N-acetylcysteine (NAC) 1200 mg may not be better than placebo at reducing the frequency of crisis in SCD, reported as pain days (rate ratio 0.99 days, 95% CI 0.53 to 1.84; 1 study, 96 participants; low-certainty evidence). Low-certainty evidence from one study (96 participants) suggests NAC (1200 mg) may not be better than placebo at reducing the severity of pain (MD 0.17, 95% CI -0.53 to 0.87). Compared to placebo, NAC (1200 mg) may not be better at improving physical QoL (MD -1.80, 95% CI -5.01 to 1.41) and mental QoL (MD 2.00, 95% CI -1.45 to 5.45; very low-certainty evidence), reducing the risk of adverse effects (gastrointestinal complaints, pruritus, or rash) (RR 0.92, 95% CI 0.75 to 1.14; low-certainty evidence), reducing the frequency of hospitalizations (rate ratio 0.98, 95% CI 0.41 to 2.38; low-certainty evidence), and sickle cell-related complications (RR 5.00, 95% CI 0.25 to 101.48; very low-certainty evidence), or increasing haemoglobin level (MD -0.18 g/dL, 95% CI -0.40 to 0.04; low-certainty evidence). L-arginine versus placebo L-arginine may not be better than placebo at reducing the frequency of crisis (monthly pain) (RR 0.71, 95% CI 0.26 to 1.95; 1 study, 50 participants; low-certainty evidence). However, L-arginine may be better than placebo at reducing the severity of pain (MD -1.41, 95% CI -1.65 to -1.18; 2 studies, 125 participants; low-certainty evidence). One participant allocated to L-arginine developed hives during infusion of L-arginine, another experienced acute clinical deterioration, and a participant in the placebo group had clinically relevant increases in liver function enzymes. The evidence is very uncertain whether L-arginine is better at reducing the mean number of days in hospital compared to placebo (MD -0.85 days, 95% CI -1.87 to 0.17; 2 studies, 125 participants; very low-certainty evidence). Also, L-arginine may not be better than placebo at increasing haemoglobin level (MD 0.4 g/dL, 95% CI -0.50 to 1.3; 2 studies, 106 participants; low-certainty evidence). No study in this comparison reported on QoL and sickle cell-related complications. Omega-3 versus placebo Very low-certainty evidence shows no evidence of a difference in the risk of adverse effects of omega-3 compared to placebo (RR 1.05, 95% CI 0.74 to 1.48; 1 study, 67 participants). Very low-certainty evidence suggests that omega-3 may not be better than placebo at increasing haemoglobin level (MD 0.36 g/L, 95% CI -0.21 to 0.93; 1 study, 67 participants). The study did not report on frequency of crisis, severity of pain, QoL, frequency of hospitalization, and sickle cell-related complications.

AUTHORS' CONCLUSIONS

There was inconsistent evidence on all outcomes to draw conclusions on the beneficial and harmful effects of antioxidants. However, L-arginine may be better than placebo at reducing the severity of pain at six months, and zinc may be better than placebo at increasing haemoglobin level. We are uncertain whether other antioxidants are beneficial for SCD. Larger studies conducted on each comparison would reduce the current uncertainties.

Characterizing the Immature Immunophenotype of Sickle Cell Disease Monocytes

Sickle cell disease (SCD) is marked by episodic vaso-occlusive crisis (VOC). Recurrent VOC creates a pro-inflammatory state that induces phenotypic alterations in innate immune cells. Monocytes are of particular interest to VOC pathophysiology because they are especially malleable to inflammatory signaling. Indeed, inflammatory disease states such as chronic obstructive pulmonary disease (COPD), obesity and atherosclerosis are known to influence monocyte development and alter monocyte subpopulations. In this study, we describe SCD monocyte subsets by performing immunophenotypic flow cytometric, enzymatic, and morphologic analysis on peripheral blood. Herein, we add to the growing body of evidence suggesting aberrant monocyte populations underpin VOC pathophysiology. We found that SCD monocytes possess an immature phenotype as demonstrated by 1) decreased CD4 positivity (p < .01), 2) low α-naphthyl butyrate esterase (ANBE) expression, and 3) naïve morphologic features. We additionally found an increase in CD14+CD16-CD4- monocytes (p < .01), a subset associated with the impaired immune response of post-trauma patients. Interestingly, we also found a large proportion of CD14+CD4-HLA-DR- monocytes which, under normal circumstances, are exclusively found in neonates (p < .01). Finally, we report an increase in nonclassical monocytes (CD14dimCD16+), a subset recently shown to have a critical role in prevention and recovery from VOC.

Inflammatory status in pediatric sickle cell disease: Unravelling the role of immune cell subsets

Introduction: The mutation of the beta-globin gene that causes sickle cell disease (SCD) results in pleiotropic effects, such as hemolysis and vaso-occlusive crisis that can induce inflammatory mechanisms with deleterious consequences on the organism. Moreover, SCD patients display an increased susceptibility to infections. Few studies are currently available that evaluate a wide immunological profile in a pediatric population. This study proposes an evaluation of the immune profile in subjects with SCD in a pediatric population through a detailed analysis by flow cytometry. Methods and Materials: Peripheral blood samples from 53 pediatric patients with SCD (mean age 9.8 years, interquartile range 9 years) were obtained and then analyzed by flow cytometry, in order to evaluate changes in the immune populations compared to 40 healthy donors (mean age 7.3 years, interquartile range 9.5 years). Results: Our data showed an increase in neutrophils (with a reduction in the CD62L + subpopulation) and monocytes (with a decrease in HLA-DRlow monocytes) with normal values of lymphocytes in SCD patients. In the lymphocyte subpopulations analysis we observed lower values of CD4⁺ T cells (with higher number of memory and central memory T lymphocytes) with increased frequency of CD8⁺ T cells (with a predominant naive pattern). Moreover, we observed higher values of CD39⁺ Tregs and lower HLA-DR+ and CD39^- T cells with an increased Th17, Th1-17 and Th2 response. Conclusion: We observed immunological alterations typical of an inflammatory status (increase in activated neutrophils and monocytes) associated with a peculiar Treg pattern (probably linked to a body attempt to minimize inflammation intrinsic to SCD). Furthermore, we highlighted a T helper pathway associated with inflammation in line with other studies. Our data showed that immunological markers may have an important role in the understanding the pathophysiology of SCD and in optimizing targeted therapeutic strategies for each patient.

CCR5Δ32 in Brazil: Impacts of a European Genetic Variant on a Highly Admixed Population

The genetic background of Brazilians encompasses Amerindian, African, and European components as a result of the colonization of an already Amerindian inhabited region by Europeans, associated to a massive influx of Africans. Other migratory flows introduced into the Brazilian population genetic components from Asia and the Middle East. Currently, Brazil has a highly admixed population and, therefore, the study of genetic factors in the context of health or disease in Brazil is a challenging and remarkably interesting subject. This phenomenon is exemplified by the genetic variant CCR5Δ32, a 32 base-pair deletion in the CCR5 gene. CCR5Δ32 originated in Europe, but the time of origin as well as the selective pressures that allowed the maintenance of this variant and the establishment of its current frequencies in the different human populations is still a field of debates. Due to its origin, the CCR5Δ32 allele frequency is high in European-derived populations (~10%) and low in Asian and African native human populations. In Brazil, the CCR5Δ32 allele frequency is intermediate (4-6%) and varies on the Brazilian States, depending on the migratory history of each region. CCR5 is a protein that regulates the activity of several immune cells, also acting as the main HIV-1 co-receptor. The CCR5 expression is influenced by CCR5Δ32 genotypes. No CCR5 expression is observed in CCR5Δ32 homozygous individuals. Thus, the CCR5Δ32 has particular effects on different diseases. At the population level, the effect that CCR5Δ32 has on European populations may be different than that observed in highly admixed populations. Besides less evident due to its low frequency in admixed groups, the effect of the CCR5Δ32 variant may be affected by other genetic traits. Understanding the effects of CCR5Δ32 on Brazilians is essential to predict the potential use of pharmacological CCR5 modulators in Brazil. Therefore, this study reviews the impacts of the CCR5Δ32 on the Brazilian population, considering infectious diseases, inflammatory conditions, and cancer. Finally, this article provides a general discussion concerning the impacts of a European-derived variant, the CCR5Δ32, on a highly admixed population.

Beyond HIV infection: Neglected and varied impacts of CCR5 and CCR5Δ32 on viral diseases

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CCR5 regulates multiple cell types (e.g., T regulatory and Natural Killer cells) and immune responses.

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The effects of CCR5, CCR5Δ32 (variant associated with reduced CCR5 expression) and CCR5 antagonists vary between infections.

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CCR5 affects the pathogenesis of flaviviruses, especially in the brain.

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The genetic variant CCR5Δ32 increases the risk of symptomatic West Nile virus infection.

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The triad “CCR5, extracellular vesicles and infections” is an emerging topic.

The interactions between chemokine receptors and their ligands may affect susceptibility to infectious diseases as well as their clinical manifestations. These interactions mediate both the traffic of inflammatory cells and virus-associated immune responses. In the context of viral infections, the human C-C chemokine receptor type 5 (CCR5) receives great attention from the scientific community due to its role as an HIV-1 co-receptor. The genetic variant CCR5Δ32 (32 base-pair deletion in CCR5 gene) impairs CCR5 expression on the cell surface and is associated with protection against HIV infection in homozygous individuals. Also, the genetic variant CCR5Δ32 modifies the CCR5-mediated inflammatory responses in various conditions, such as inflammatory and infectious diseases. CCR5 antagonists mimic, at least in part, the natural effects of the CCR5Δ32 in humans, which explains the growing interest in the potential benefits of using CCR5 modulators for the treatment of different diseases. Nevertheless, beyond HIV infection, understanding the effects of the CCR5Δ32 variant in multiple viral infections is essential to shed light on the potential effects of the CCR5 modulators from a broader perspective. In this context, this review discusses the involvement of CCR5 and the effects of the CCR5Δ32 in human infections caused by the following pathogens: West Nile virus, Influenza virus, Human papillomavirus, Hepatitis B virus, Hepatitis C virus, Poliovirus, Dengue virus, Human cytomegalovirus, Crimean-Congo hemorrhagic fever virus, Enterovirus, Japanese encephalitis virus, and Hantavirus. Subsequently, this review addresses the impacts of CCR5 gene editing and CCR5 modulation on health and viral diseases. Also, this article connects recent findings regarding extracellular vesicles (e.g., exosomes), viruses, and CCR5. Neglected and emerging topics in “CCR5 research” are briefly described, with focus on Rocio virus, Zika virus, Epstein-Barr virus, and Rhinovirus. Finally, the potential influence of CCR5 on the immune responses to coronaviruses is discussed.

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

BACKGROUND

Sickle cell anemia (SCA) is associated with a chronic proinflammatory state characterized by elevated leukocyte count, mortality from severe recurrent infections, and subsequent vasoocclusive complications with leukocyte adhesion to the endothelium and increased plasma levels of inflammatory cytokines. The immune system has a close connection with morbidity in SCA, but further studies are needed to uncover the involvement of innate and adaptive immunities in modulating the SCA physiopathology. We performed measurements of the frequency of innate and adaptive immunity cells, cytokines, chemokines, and growth factors and immunophenotyping of Toll-like receptor and adhesion molecule expression in the blood of SCA patients and healthy donors to evaluate the different profiles of these biomarkers, the relationship among them, and their correlation to laboratory records and death risk. Material and Methods. Immunophenotyping of cells, Toll-like receptors, and adhesion molecules were performed from peripheral blood samples of SCA patients and healthy donors by flow cytometry and cytokine/chemokine/growth factor measurement by the Luminex technique performed from the serum of the same subjects.

RESULTS

Cells of adaptive immunity such as IL-12, IL-17, and IL-10 cytokines; IL-8, IP-10, MIP-1α, MIP-1β, and RANTES chemokines; and VEGF, FGF-basic, and GM-CSF growth factors were higher in SCA patients than healthy donors regardless of any laboratorial and clinical condition. However, high death risk appears to have relevant biomarkers.

CONCLUSION

In the SCA pathophysiology at steady state, there is a broad immunological biomarker crosstalk highlighted by TCD4+CD69+ lymphocytes, IL-12 and IL-17 inflammatory and IL-10 regulatory cytokines, MIP-1α, MIP-1β, and IP-10 chemokines, and VEGF growth factor. High expression of TLR2 in monocytes and VLA-4 in TCD8+ lymphocytes and high levels of MIP-1β and RANTES appear to be relevant in high death risk conditions. The high reticulocytosis and high death risk conditions present common correlations, and there seems to be a balance by the Th2 profile.

The increased neopterin content in turkish pediatric patients with sickle cell anemia

In the present study, the possible activation of cellular immunity in SCD patients was investigated. As immune activation parameters, neopterin concentrations and kynurenine/tryptophan ratio for tryptophan degradation in 35 pediatric patients with sickle cell disease (31 HbSS and 4 HbSß) were determined. Our results have shown that neopterin levels (both urinary and serum) are increased in pediatric patients with sickle cell disease. The increase in neopterin concentration was accompanied by significantly increased biopterin, kynurenine concentration and kynurenine/tryptophan ratio. The mechanism of immune activation and the effects of inflammatory mediators in sickle cell disease are poorly understood, especially in terms of cell-mediated immunity. Further in-vivo and in-vitro studies are required to illuminate the association between neopterin levels and neutrophil activation in sickle cell disease.

A common molecular signature of patients with sickle cell disease revealed by microarray meta-analysis and a genome-wide association study

A chronic inflammatory state to a large extent explains sickle cell disease (SCD) pathophysiology. Nonetheless, the principal dysregulated factors affecting this major pathway and their mechanisms of action still have to be fully identified and elucidated. Integrating gene expression and genome-wide association study (GWAS) data analysis represents a novel approach to refining the identification of key mediators and functions in complex diseases. Here, we performed gene expression meta-analysis of five independent publicly available microarray datasets related to homozygous SS patients with SCD to identify a consensus SCD transcriptomic profile. The meta-analysis conducted using the MetaDE R package based on combining p values (maxP approach) identified 335 differentially expressed genes (DEGs; 224 upregulated and 111 downregulated). Functional gene set enrichment revealed the importance of several metabolic pathways, of innate immune responses, erythrocyte development, and hemostasis pathways. Advanced analyses of GWAS data generated within the framework of this study by means of the atSNP R package and SIFT tool identified 60 regulatory single-nucleotide polymorphisms (rSNPs) occurring in the promoter of 20 DEGs and a deleterious SNP, affecting CAMKK2 protein function. This novel database of candidate genes, transcription factors, and rSNPs associated with SCD provides new markers that may help to identify new therapeutic targets.

[Epidemiological, clinical and hematological profiles of homozygous sickle cell disease during the intercritical period among children in Ziguinchor, Senegal]

La drépanocytose pose un problème de santé publique au Sénégal. Elle concerne principalement les enfants et les adolescents. L'objectif de notre travail était de déterminer les profils épidémiologiques, cliniques et hématologiques de la drépanocytose homozygote SS dans une cohorte d'enfants suivis à l'hôpital de la paix de Ziguinchor. Il s'agit d'une étude rétrospective portant sur des dossiers d'enfants drépanocytaires. Etaient inclus, les drépanocytaires SS âgés entre 2mois et 21ans, reçus en phase inter critique durant la période d'étude allant du 1^er Janvier 2015 au 31 Août 2017. N'étaient pas inclus dans l'étude les hétérozygotes composites (SC, S béta thalassémie). Nous avons colligé 46 dossiers de drépanocytaires SS (20 filles et 26 garçons). L'âge moyen des enfants était de 8,0ans [11mois-21ans]. Environ 1/3 des enfants (39,1%) avaient un âge inférieur ou égal à 5 ans. Il y avait une diversité ethnique avec une prédominance de diola (30,2%) suivi de mandingue (27,9%) et de poular (25,6%). L'âge moyen des enfants à la 1ére crise était de 35,5mois [7-192 mois]. Plus de 1/3 des enfants (41,3%) avaient fait une 1ére crise avant le deuxième anniversaire. Le type de la 1ére crise, qu'avait présenté l'enfant, était dominé par la crise vaso-occlusive (32,6%) suivi du syndrome pied-main (30,4%). Les signes cliniques en phase inter critique étaient la pâleur 95,6%); l'ictère (36,9%) et la splénomégalie (21,7%). A l'hémogramme, le nombre de globules blancs moyen était de 12465 leucocytes/mm³ [5340-26900]. L'hyperleucocytose, supérieure à 10 000 leucocytes/mm³ était retrouvée chez 34 malades (73,9%). La totalité des malades présentait une anémie avec une moyenne 08,6 g/dl [05,7-11,8]. Le taux d'hémoglobine S variait entre 54,6 et 98,4%. Le diagnostic et la prise en charge médicale de la drépanocytose SS sont tardifs à Ziguinchor. Le dépistage néonatal pourrait favoriser une prise en charge précoce dans la région.

Induced Pluripotent Stem Cell for the Study and Treatment of Sickle Cell Anemia

Sickle cell anemia (SCA) is a monogenic disease of high mortality, affecting millions of people worldwide. There is no broad, effective, and safe definitive treatment for SCA, so the palliative treatments are the most used. The establishment of an in vitro model allows better understanding of how the disease occurs, besides allowing the development of more effective tests and treatments. In this context, iPSC technology is a powerful tool for basic research and disease modeling, and a promise for finding and screening more effective and safe drugs, besides the possibility of use in regenerative medicine. This work obtained a model for study and treatment of SCA using iPSC. Then, episomal vectors were used for reprogramming peripheral blood mononuclear cells to obtain integration-free iPSC. Cells were collected from patients treated with hydroxyurea and without treatment. The iPSCP Bscd lines were characterized for pluripotent and differentiation potential. The iPSC lines were differentiated into HSC, so that we obtained a dynamic and efficient protocol of CD34+CD45+ cells production. We offer a valuable tool for a better understanding of how SCA occurs, in addition to making possible the development of more effective drugs and treatments and providing better understanding of widely used treatments, such as hydroxyurea.

[Epidemiological profile of hemoglobinopathies: a cross-sectional and descriptive index case study]

Hemoglobinopathies are congenital disorders resultimg from hemoglobin abnormalities. Major forms are often severe, their management is difficult and associated with a great psychosocial impact on patients and their families. They are classified as rare diseases and are still insufficiently known by health professionals. This lack of knowledge is at the origin of diagnostic errors, delay in their management and therefore high morbidity and mortality rate for these patients. In 2008, the World Health Organization (WHO) has published data on hemoglobinopathies epidemiology: more than 330.000 cases of hemoglobinopathy occur each year (83% of cases of sickle cell anemia, 17 % of cases of thalassemia). Hemoglobin disorders are responsible for approximately 3.4% of deaths among people under the age of 5. At the global level, approximately 7% of pregnant women would be carriers of a form of thalassemia and 1% of couples are at risk. However, they are relatively frequent in some regions of the globe where consanguineous marriages are common. We conducted a descriptive cross-sectional study based on two surveys, the first in May 2015 and the second in June of the same year. It was performed in the immunization days to deliver pneumococcal vaccine to the index cases and it was aimed to describe the epidemiological features of families at risk of hemoglobinopathies (index case study), whose index cases were treated in the Department of Pediatrics at the Provincial Hospital El Idrisi, Kenitra, Morocco. After having collected the epidemiological data from patients, laboratory tests were performed including: blood count with red blood cells morphological assessment using the MGG assay and automatic numbering of reticulocytes; hemoglobin electrophoresis at alkaline pH (8.8) and then at acid pH (5.4) on agarose gel and densitometric integration. 275 patients had laboratory profiles compatible with hemoglobinopathy. The majority of these patients were born to consanguineous marriages (83.1%) and came from the north regions of Morocco. This family survey allowed to identify families at risk with a high frequency of sickle cell anemia. Our results confirm the existence of hemoglobinopathies variants among Moroccan population.

[Evaluation of hemogram in patients with homozygous sickle cell disease: about 87 cases]

Homozygous sickle cell disease is one of the most frequent haemoglobinopathies in Morocco. Sickle cell disease is characterized by a large clinical and biological expression variability which depends on modulating genetic and environmental factors. Clinical manifestation includes regenerative anemia whose severity may vary among individuals. In the absence of treatment, it results in premature death. Sickle cell disease is characterized by a large clinical and biological expression variability which depends on genetic and environmental factors. A severe clinical picture marked by high early transfusion frequency, severe infectious complications and early mortality. A constant inflammatory condition characterized by elevated inflammatory proteins and compromised nutritional status. The objective of this study is to determine the hematological parameters profile in moroccan patients with homozygous sickle cell (SS) disease during stationary phases. We conducted a cross-sectional descriptive study of 87 patients with sickle cell (SS) disease. We performed a biological study based on: Hemogram with morphological assessment of red blood cells stained with MGG and automated reticulocyte counting; Hemoglobin electrophoresis test performed on alkaline agarose gel (pH 8.8) and densitometric integration. The average age is 13.22 years ± 16.36, ranging betrween 0.6 and 36 years, with a sex ratio (M/F) of 1.175. Biological effects of anemia were intense in 88.5% of patients; 67.8% of patients had normocytic anemia compared with 29.9% with microcytosis, and 2.3% with macrocytosis. The degree of anisocytosis was related to the degree of anemia, very evocative in patients with homozygous S/S (95.4%). Reticulocytosis was observed in 81.6% of patients; 52.9% of patients had thrombocytosis. Leukocytosis was observed in 64.4% of patients; 80.5% of patients had neutropenia. The parameters of the hemogram will serve as a basis for comparison during crises and will make it possible to evaluate the effectiveness of patient management. High white blood cell count, platelets and MCHC seem to be determinant of sickle cell anemia severity in Morocco. The haematological profile of moroccan patients with sickle cell disease exhibits data similar to those reported in literature relating to patients with leucocytosis from Central Africa. The results of our study suggest that sickle cell anemia is the most common health problem in Morocco and they are similar to those for major sickle cell syndrome.

Red blood cell alloimmunization in patients with sickle cell disease: correlation with HLA and cytokine gene polymorphisms

BACKGROUND

The reason for the difference in susceptibility to red blood cell (RBC) alloimmunization among patients with sickle cell disease (SCD) is not clearly understood and is probably the result of multiple factors. Our hypothesis is that genetic polymorphisms are associated with RBC alloimmunization.

STUDY DESIGN AND METHODS

We investigated the possible association of susceptibility to RBC alloimmunization with polymorphisms of HLA and cytokines genes in 161 SCD patients prior exposed to RBC transfusion. Cytokine gene polymorphisms were analyzed by polymerase chain reaction (PCR) and TaqMan assays. HLA Class I genotyping was performed using PCR-specific sequence of oligonucleotides. Polymorphism frequencies were compared using the Fisher's exact test.

RESULTS

Our results revealed increased percentage of the A allele and the GA genotype of the TNFA -308G/A cytokine among alloimmunized patients when compared to nonalloimmunized patients (A allele, 16.4% vs. 6.8%, p = 0.004; GA genotype, 32.8% vs. 11.7%, p = 0.0021). In addition, the IL1B -511T allele and the IL1B -511TT and CT genotype frequencies were overrepresented among alloimmunized patients (T allele, 53.0% vs. 37.5%, p = 0.0085; CT + TT genotypes, 81.82% vs. 60.87%, p = 0.0071). In relation to HLA Class I, we found a higher frequency of HLA-DRB1*15 among patients alloimmunized to Rh antigens when compared to nonalloimmunized patients (15.63% vs. 6.98%, p = 0.044).

CONCLUSION

Brazilian SCD patients with the TNFA, IL1B, and HLA-DRB1 gene polymorphisms were at increased risk of becoming alloimmunized by RBC transfusions. These findings may contribute to the development of future therapeutic strategies for patients with SCD with higher susceptibility of alloimmunization.

Vitamin D Deficiency in Adult Sickle Cell Patients

INTRODUCTION

Vitamin D levels in adult black Americans with sickle cell disease (SCD) are comparatively lower than those found in the general population of black Americans. The objectives of this study were to examine the prevalence of Vitamin D deficiency (VDD) in adults with various subtypes of sickle cell disease and identify risk factors for vitamin D deficiency.

METHODS

In a retrospective study serum Vitamin D25(OH)D and/or VitaminD1,25(OH)2D levels were obtained in 120 subjects with sickle cell disease. Baseline studies also included LFTs, total protein, albumin, total bilirubin, and creatinine levels. In a portion of subjects that were treated with oral ergocalciferol vitamin D levels and chemistries were obtained within 6 months of treatment. Data was statistically analyzed with Welch two sample t-tests and individual simple linear regressions (including logarithmic values) for each variable.

RESULTS

Vitamin D25(OH)D levels were found to be significantly lower in a group of subjects with Hgb SS disease, than in a group with other subtypes of sickle cell disease. In both groups combined, significant (p = 0.05) and clinically suggestive negative correlations with Vitamin D25(OH)D were seen for total bilirubin and total protein, respectively. When total bilirubin and total protein levels were compared between the Hgb SS and HgbS/other groups, t-test revealed these levels were significantly higher in the Hgb SS group levels at p < 0.001 and p = 0.005, respectively.

IMPLICATIONS

Low total Vitamin D25(OH)D levels in adults with sickle cell disease may be a reflection of chronic inflammation and overall disease severity.

Hemopexin therapy reverts heme-induced proinflammatory phenotypic switching of macrophages in a mouse model of sickle cell disease

Hemolytic diseases, such as sickle cell anemia and thalassemia, are characterized by enhanced release of hemoglobin and heme into the circulation, heme-iron loading of reticulo-endothelial system macrophages, and chronic inflammation. Here we show that in addition to activating the vascular endothelium, hemoglobin and heme excess alters the macrophage phenotype in sickle cell disease. We demonstrate that exposure of cultured macrophages to hemolytic aged red blood cells, heme, or iron causes their functional phenotypic change toward a proinflammatory state. In addition, hemolysis and macrophage heme/iron accumulation in a mouse model of sickle disease trigger similar proinflammatory phenotypic alterations in hepatic macrophages. On the mechanistic level, this critically depends on reactive oxygen species production and activation of the Toll-like receptor 4 signaling pathway. We further demonstrate that the heme scavenger hemopexin protects reticulo-endothelial macrophages from heme overload in heme-loaded Hx-null mice and reduces production of cytokines and reactive oxygen species. Importantly, in sickle mice, the administration of human exogenous hemopexin attenuates the inflammatory phenotype of macrophages. Taken together, our data suggest that therapeutic administration of hemopexin is beneficial to counteract heme-driven macrophage-mediated inflammation and its pathophysiologic consequences in sickle cell disease.

[Hematological and nutritional profile of homozygous sickle cell SS aged 6 to 59 months in Lubumbashi, Democratic Republic of Congo]

Introduction

La drépanocytose est une maladie génétique très polymorphe et la moitié des drépanocytaires homozygotes SS en Afrique meurt avant l’âge de 5 ans. Le but de cette étude est de déterminer les paramètres nutritionnels et hématologiques des jeunes drépanocytaires homozygotes (SS) congolais au cours de la phase stationnaire.

Méthodes

Nous avons fait à une étude descriptive comparative de deux groupes de patients dont l'un avec 41 sujets drépanocytaires (SS) d’âge moyen de 39,1mois et l'autre, groupe contrôle, avec 82 patients avec hémoglobine AA et d’âge moyen de 35,0 mois. Nous avons eu recours à un automate ABX Micros 60 pour l’évaluation hématologique. Pour l’évaluation nutritionnel nous avons étudiés le poids, la taille, l’âge ainsi que le sexe.

Résultats

Nous n'avons pas observé de différence significative entre les deux groupes par rapport à l’état nutritionnel (p > 0,05). L'hémogramme des homozygotes SS révèle une anémie chronique avec un taux moyen d'Hémoglobine à 8,33 ± 1,35g/dL. Cette anémie est normocytaire (VGM = 83,86 µm3), et régénérative (réticulocytes = 4,23±4,26%).

Conclusion

Nos résultats rencontrent ce qui est souvent décrit dans le syndrome drépanocytaire majeur sur les homozygotes SS avec haplotype bantu.

Label-free and depth resolved optical sectioning of iron-complex deposits in sickle cell disease splenic tissue by multiphoton microscopy

Multiphoton microscopy (MPM) imaging of intrinsic two-photon excited fluorescence (TPEF) is performed on humanized sickle cell disease (SCD) mouse model splenic tissue. Distinct morphological and spectral features associated with SCD are identified and discussed in terms of diagnostic relevance. Specifically, spectrally unique splenic iron-complex deposits are identified by MPM; this finding is supported by TPEF spectroscopy and object size to standard histopathological methods. Further, iron deposits are found at higher concentrations in diseased tissue than in healthy tissue by all imaging methods employed here including MPM, and therefore, may provide a useful biomarker related to the disease state. These newly characterized biomarkers allow for further investigations of SCD in live animals as a means to gain insight into the mechanisms impacting immune dysregulation and organ malfunction, which are currently not well understood.

The CCR5Δ32 polymorphism in Brazilian patients with sickle cell disease

BACKGROUND

Previous studies on the role of inflammation in the pathophysiology of sickle cell disease (SCD) suggested that the CCR5Δ32 allele, which is responsible for the production of truncated C-C chemokine receptor type 5 (CCR5), could confer a selective advantage on patients with SCD because it leads to a less efficient Th1 response. We determined the frequency of the CCR5Δ32 polymorphism in 795 Afro-Brazilian SCD patients followed up at the Pernambuco Hematology and Hemotherapy Center, in Northeastern Brazil, divided into a pediatric group (3 months-17 years, n = 483) and an adult group (18-70 years, n = 312). The adult patients were also compared to a healthy control group (blood donors, 18-61 years, n = 247).

METHODS

The CCR5/CCR5Δ32 polymorphism was determined by allele-specific PCR.

RESULTS

No homozygous patient for the CCR5Δ32 allele was detected. The frequency of heterozygotes in the study population (patients and controls) was 5.8%, in the total SCD patients 5.1%, in the children 5.4%, in the adults with SCD 4.8%, and in the adult controls 8.1%. These differences did not reach statistical significance.

CONCLUSIONS

Our findings failed to demonstrate an important role of the CCR5Δ32 allele in the population sample studied here.

Heme on innate immunity and inflammation

Heme is an essential molecule expressed ubiquitously all through our tissues. Heme plays major functions in cellular physiology and metabolism as the prosthetic group of diverse proteins. Once released from cells and from hemeproteins free heme causes oxidative damage and inflammation, thus acting as a prototypic damage-associated molecular pattern. In this context, free heme is a critical component of the pathological process of sterile and infectious hemolytic conditions including malaria, hemolytic anemias, ischemia-reperfusion, and hemorrhage. The plasma scavenger proteins hemopexin and albumin reduce heme toxicity and are responsible for transporting free heme to intracellular compartments where it is catabolized by heme-oxygenase enzymes. Upon hemolysis or severe cellular damage the serum capacity to scavenge heme may saturate and increase free heme to sufficient amounts to cause tissue damage in various organs. The mechanism by which heme causes reactive oxygen generation, activation of cells of the innate immune system and cell death are not fully understood. Although heme can directly promote lipid peroxidation by its iron atom, heme can also induce reactive oxygen species generation and production of inflammatory mediators through the activation of selective signaling pathways. Heme activates innate immune cells such as macrophages and neutrophils through activation of innate immune receptors. The importance of these events has been demonstrated in infectious and non-infectious diseases models. In this review, we will discuss the mechanisms behind heme-induced cytotoxicity and inflammation and the consequences of these events on different tissues and diseases.

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.

CCR5delta32 in systemic lupus erythematosus: implications for disease susceptibility and outcome in a Brazilian population

The aim of this study was to analyze the allelic and genotypic frequencies of the CCR5delta32 polymorphism in systemic lupus erythematosus (SLE) patients and to investigate a possible association of this allele with SLE susceptibility and clinical outcome. A total of 367 SLE patients and 435 healthy controls were genotyped for the CCR5delta32 polymorphism. We observed that, in European-derived individuals, the frequency of the CCR5delta32 allele was smaller in patients than in controls (2.7% vs. 7.5%, OR 0.34, 95% CI 0.17-0.65, p Bonf=0.002), suggesting that this allele could be considered a protective factor for the disease. Regarding clinical manifestations, we observed that CCR5delta32 female African-derived carrier patients presented a higher predisposition to class IV nephritis when compared with absent nephritis/other class group (13.8% vs. 3.8%, OR 37.1, 95% CI 2.8-1854.7, p Bonf=0.030). A multivariate analysis including all female patients and controlling for the presence or absence of anti-dsDNA antibodies, ethnicity and age at diagnosis showed an increased relative risk of 3.9 times for patients carrying the CCR5delta32 allele to develop class IV nephritis as compared with noncarriers. Our data suggest that the CCR5delta32 allele is a protective factor for the disease in European-derived patients and a susceptibility factor to class IV nephritis in African-derived female patients.

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.

Heme oxygenase-1 gene promoter polymorphism is associated with reduced incidence of acute chest syndrome among children with sickle cell disease

Sickle cell disease is a common hemolytic disorder with a broad range of complications, including vaso-occlusive episodes, acute chest syndrome (ACS), pain, and stroke. Heme oxygenase-1 (gene HMOX1; protein HO-1) is the inducible, rate-limiting enzyme in the catabolism of heme and might attenuate the severity of outcomes from vaso-occlusive and hemolytic crises. A (GT)(n) dinucleotide repeat located in the promoter region of the HMOX1 gene is highly polymorphic, with long repeat lengths linked to decreased activity and inducibility. We examined this polymorphism to test the hypothesis that short alleles are associated with a decreased risk of adverse outcomes (hospitalization for pain or ACS) among a cohort of 942 children with sickle cell disease. Allele lengths varied from 13 to 45 repeats and showed a trimodal distribution. Compared with children with longer allele lengths, children with 2 shorter alleles (4%; ≤ 25 repeats) had lower rates of hospitalization for ACS (incidence rate ratio 0.28, 95% confidence interval, 0.10-0.81), after adjusting for sex, age, asthma, percentage of fetal hemoglobin, and α-globin gene deletion. No relationship was identified between allele lengths and pain rate. We provide evidence that genetic variation in HMOX1 is associated with decreased rates of hospitalization for ACS, but not pain. This study is registered at www.clinicaltrials.gov as #NCT00072761.

HO-1 polymorphism as a genetic determinant behind the malaria resistance afforded by haemolytic disorders

Malaria affects thousands of people around the world representing a critical issue regarding health policies in tropical countries. Similarly, also haemolytic diseases such as sickle cell disease and thalassemias are a concern in different parts of the globe. It is well established that haemolytic diseases, such as sickle cell disease (SCD) and thalassemias, represent a resistance factor to malaria, which explains the high frequencies of such genetic variants in malaria endemic areas. In this context, it has been shown that the rate limiting enzyme heme oxygenase I (HO-1), responsible for the catabolism of the free heme in the body, is an important resistance factor in malaria and is also important in the physiopathology of haemolytic diseases. Here, we suggest that allelic variants of HO-1, which display significant differences in terms of protein expression, have been selected in endemic malaria areas since the HO-1 enzyme can enhance the protection against malaria conferred by haemolytic diseases This protection apply mainly in what concerns protection against severe malaria forms. Therefore, HO-1 genotyping would be fundamental to determine resistance of a given individual to lethal forms of malaria as well as to common clinical complications typical to haemolytic diseases and would be helpful in the establishment of public health politics.

Infections in thalassemia and hemoglobinopathies: focus on therapy-related complications

The clinical approach to thalassemia and hemoglobinopathies, specifically Sickle Cell Disease (SCD), based on transfusions, iron chelation and bone marrow transplantation has ameliorated their prognosis. Nevertheless, infections still may cause serious complications in these patients. The susceptibility to infections in thalassemia and SCD arises both from a large spectrum of immunological abnormalities and from exposure to specific infectious agents. Four fundamental issues will be focused upon as central causes of immune dysfunction: the diseases themselves; iron overload, transfusion therapy and the role of the spleen. Thalassemia and SCD differ in their pathogenesis and clinical course. It will be outlined how these differences affect immune dysfunction, the risk of infections and the types of most frequent infections in each disease. Moreover, since transfusions are a fundamental tool for treating these patients, their safety is paramount in reducing the risks of infections. In recent years, careful surveillance worldwide and improvements in laboratory tests reduced greatly transfusion transmitted infections, but the problem is not completely resolved. Finally, selected topics will be discussed regarding Parvovirus B19 and transfusion transmitted infections as well as the prevention of infectious risk postsplenectomy or in presence of functional asplenia.

HLA-G polymorphism influences the susceptibility to HCV infection in sickle cell disease patients

Despite its well known monogenic etiopathogenesis, sickle cell disease (SCD) is characterized by a striking variability of clinical presentation. There is growing evidence that genetic factors may be involved in this variability. Human leukocyte antigen (HLA)-G is a non-classical HLA molecule which was shown to be expressed at sites of inflammation and in inflammatory diseases. Besides its large and highly polymorphic promoter region, the 3' UTR region seems also to play an important role on regulating HLA-G expression. We investigated the influence of the 14 pb (rs1704) and the +3142 (rs1063320) HLA-G polymorphisms in 93 SCD patients in order to evaluate its potential role on clinical parameters. Twenty-one patients presented an HCV infection. Among all SCD patients 16 (22.2%) were homozygous for the +3142C genotype, none of them hepatitis C (HCV) positive. Controlling for blood transfusions in the last year, the C allele represented a dose dependent protection effect for HCV infection (PR = 0.41; 95% CI: 0.24-0.71). The +3142C allele was also underrepresented among patients with history of respiratory-tract infections. Our results support a role of the +3142 polymorphism in the susceptibility to infections, in particular to HCV infection, and suggest a possible interference of the HLA-G molecule in the response to infections, among SCD patients.

The role of inflammation in alloimmunization to antigens on transfused red blood cells

PURPOSE OF REVIEW

To discuss how inflammation affects humoral alloimmunization to antigens on transfused red blood cells (RBCs).

RECENT FINDINGS

Recently, three unique murine models of humoral alloimmunization to transfused RBCs have been described. As in humans, RBC alloimmunization rates in recipient mice are variable, with segregation into responder and nonresponder groups. Because the recipient mice are genetically identical, environmental factors may play a role in regulating alloimmunization. These models have further been used to demonstrate that recipient inflammation has a complex regulatory effect upon alloimmunization. Isolated case reports in humans raise the possibility of a similar role of inflammation in regulating alloimmunization to RBCs.

SUMMARY

It is currently unknown why some human transfusion recipients mount strong alloantibody responses, whereas others do not. Human leukocyte antigen immunogenetics likely play a substantial role. However, within groups with the genetic capacity to respond to a given RBC antigen, recipients still segregate into responders and nonresponders. The data reviewed herein indicate that recipient inflammation in mice has the capacity to regulate alloimmunization. Future studies will be required to further understand these effects and to investigate if similar biology regulates alloimmunization to transfused RBCs in humans.

Histopathology of experimentally induced asthma in a murine model of sickle cell disease

Asthma is a comorbid condition associated with increased rates of pain, acute chest syndrome, and premature death in human sickle cell disease (SCD). We developed an experimental asthma model in SCD and control mice expressing either normal human or murine hemoglobin to determine its effect on mortality and lung pathology. To induce lung inflammation, experimental mice were sensitized to ovalbumin (OVA) by subcutaneous OVA implantation (Sen), allowed 2 weeks to recover, and then divided into 2 groups, each receiving over a subsequent 10-day period the same dosage of aerosolized OVA but 2 different levels of exposure: 15 minutes (LoSen) and 30 minutes (HiSen). During recovery, 10% of SCD mice died compared with no deaths in control mice. An additional 30% of HiSen SCD mice died during aerosolization compared with 10% in LoSen SCD. Histologic indices of lung inflammation (eg, eosinophil recruitment, airway and vessel wall thickening, and immunoreactive TGFbeta and fsp-1) and bronchial alveolar lavage fluid eosinophil peroxidase activity differentially increased in sensitized mice compared with unsensitized mice. Our findings indicate SCD mice with experimentally induced asthma are more susceptible to death and pulmonary inflammation compared with control mice, suggesting that asthma contributes significantly to morbidity and mortality in SCD.

Cytokine concentrations in bone marrow of stable sickle cell anemia patients

Inflammation plays a significant role in the clinical manifestations of sickle cell anemia. In studies of anemic patients with other clinical syndromes, measurement of the concentrations of cytokine mediators of inflammation in bone marrow aspirates has provided unique correlations with clinical and laboratory parameters. We determined concentrations of interleukin (IL)-1, IL-6, tumor necrosis factor (TNF), and placental growth factor (PlGF) in bone marrow aspirates from six homozygous sickle cell (SS) patients who were not acutely ill and who were not receiving hydroxyurea, erythropoietin, or chronic transfusion and compared them with specimens from seven healthy controls. We also measured concentrations of soluble transferrin receptor (sTfR) and of marrow erythroid colony-forming units (CFU-E) as markers of erythropoietic activity. sTfR concentration was significantly higher in SS patients (p = .024). CFU-E concentration was not significantly different between the two groups. Bone marrow concentrations of IL-6 and IL-1 did not differ between the study groups. TNF was undetectable in all specimens, plasma or marrow. Bone marrow PlGF concentrations were significantly higher in SS patients (p = .004). Since PlGF is a product of erythroid cells, the ratio of marrow PlGF to marrow sTfR was determined and found to be significantly greater in SS patients. This suggests that the observed difference in marrow PlGF concentrations does not reflect increased erythropoiesis but rather represents increased PlGF production per erythroid unit.

Inhibition of caspase-dependent spontaneous apoptosis via a cAMP-protein kinase A dependent pathway in neutrophils from sickle cell disease patients

Sickle cell disease (SCD) is a chronic inflammatory condition characterized by high leucocyte counts, altered cytokine levels and endothelial cell injury. As the removal of inflammatory cells by apoptosis is fundamental for the resolution of inflammation, we aimed to determine whether the leucocyte apoptotic process is altered in SCD. Neutrophils from SCD individuals showed an inhibition of spontaneous apoptosis when cultured in vitro, in the presence of autologous serum for 20 h. Intracellular cyclic adenosine monophosphate (cAMP) levels were approximately twofold increased in SCD neutrophils; possible cAMP-upregulating factors present in SCD serum include interleukin-8, granulocyte-macrophage colony-stimulating factor and prostaglandin. Accordingly, co-incubation of SCD neutrophils with KT5720, a cAMP-dependent protein kinase (PKA) inhibitor, abrogated increased SCD neutrophil survival. Caspase-3 activity was also significantly diminished in SCD neutrophils cultured for 16 h and this activity was restored when cells were co-incubated with KT5720. BIRC2 (encoding cellular inhibitor of apoptosis protein 1, cIAP(1)), MCL1 and BAX expression were unaltered in SCD neutrophils; however, BIRC3 (encoding the caspase inhibitor, cIAP(2)), was expressed at significantly higher levels. Thus, we report an inhibition of spontaneous SCD neutrophil apoptosis that appears to be mediated by upregulated cAMP-PKA signalling and decreased caspase activity. Increased neutrophil survival may have significant consequences in SCD; contributing to leucocytosis, tissue damage and exacerbation of the chronic inflammatory state.

Energy expenditure, inflammation, and oxidative stress in steady-state adolescents with sickle cell anemia

Sickle cell anemia (HbSS) is characterized by hypermetabolism, chronic inflammation, and increased oxidative stress, but the relationship between these factors is undefined. In this study, we examined indicators of inflammatory process and markers of oxidative damage and their impact on resting energy expenditure (REE) in stable HbSS adolescents (n = 35) and healthy controls carrying normal hemoglobin genotype (HbAA) (n = 39). C-reactive protein (CRP), white blood cell (WBC) count, and proinflammatory cytokines were measured as markers of inflammation and 2,3-dinor-5,6-dihydro-15-F2t-isoprostane (F2-IsoPM) as a marker of oxidative stress. REE was measured by indirect calorimetry. WBC counts (11.90 +/- 5.3 x10/muL versus 5.6 +/- 1.9 x10/muL; p < 0.001), serum CRP (9.1 +/- 11.0 mug/mL versus 0.4 +/- 0.7 mug/mL; p < 0.001) and serum IL-8 (7.5 +/- 4.4 pg/mL versus 5.5 +/- 4.8 pg/mL; p = 0.011) were higher in HbSS than HbAA, suggesting an anti-inflammatory response in HbSS. Higher urinary F2-IsoPM in HbSS (1.2 +/- 0.4 versus 0.7 +/- 0.3 ng/mg creatinine; p < 0.001) indicates increased oxidative stress. Fat free mass (FFM), hemoglobin (Hgb), interleukin (IL)-8, and F2-IsoPM were independent predictors of REE in HbSS (overall r = 0.778; p < 0.001). Low-grade inflammation and increased oxidative stress are present in adolescents with HbSS in the absence of acute crisis, and their markers are correlated with elevated REE.

Recipient inflammation affects the frequency and magnitude of immunization to transfused red blood cells

BACKGROUND

Most alloantigens on transfused red blood cells (RBCs) are weakly immunogenic, with only a 2 to 6 percent overall immunization rate even in patients receiving multiple transfusions. Although recipient genetics may contribute to responder and/or nonresponder status, in most cases HLA type does not predict humoral response to RBC antigens. In contrast, rates of alloimmunization do correspond to the underlying disease status of transfusion recipients, suggesting that acquired host factors may play an important role. In this context, it was hypothesized that the inflammatory status of a transfusion recipient would influence immunization to transfused RBCs.

STUDY DESIGN AND METHODS

A novel murine model for alloimmunization to RBC antigens was developed with the mHEL mouse, which expresses hen egg lysozyme (HEL) as a model blood group antigen. Leukoreduced mHEL RBCs were transfused into wild-type recipient mice, and anti-HEL responses were monitored. To test the stated hypothesis, some recipient animals were injected with polyinosinic polycytidylic acid (poly(I:C)), a synthetic double-stranded RNA molecule that induces viral-like inflammation.

RESULTS

Similar to the immunogenicity of most RBC antigens in humans, transfusion of mHEL RBCs into uninflamed mice was only a weak immunogen. In contrast, poly(I:C)-treated mice had a significant increase in both the frequency and the magnitude of alloimmunization to the mHEL antigen.

CONCLUSIONS

These findings demonstrate that recipient inflammation with poly(I:C) significantly enhances humoral immunization to transfused alloantigens in a murine model. Moreover, these data suggest that the inflammatory status of human transfusion recipients may regulate the immunogenicity of transfused RBCs.

High levels of neopterin and interleukin-3 in sickle cell disease patients

Sickle cell disease (SCD) is recognized as a chronic inflammatory condition. Cytokines are released in response to stress or pathological situations, and influence hematopoiesis. The aim of this study was to evaluate interleukin-3 (IL-3), interferon-gamma (IFN-gamma), and neopterin (NP) levels in steady-state patients with sickle cell anemia (SS) (n = 35) and SC hemoglobinopathy (n = 15) in order to verify the possible action of those cytokines and NP on iron metabolism and hematopoiesis. Serum IL-3 concentration was higher in SS and SC groups than in controls, whereas IFN-gamma levels did not differ among groups. SS patients presenting hemoglobin fetal (HbF) >or=8.5% had significantly higher IL-3 levels than those with HbF <8.5% (P = 0.0338). No correlation was observed among inflammatory and iron metabolism parameters. Significant correlations were observed between IL-3 and Hb levels (r = 0.4633, P = 0.0457), and IL-3 and HbF levels (r = 0.6011, P = 0.0065). A negative correlation was observed between IL-3 and reticulocyte counting (r = -0.4632, P = 0.0457) only in the SS group. NP levels were significantly higher in the SS and SC groups than in controls, but did not differ between SS and SC. No correlation was observed between NP and iron metabolism parameters. These data suggest that IL-3 stimulates hematopoiesis, and that SS patients, even in steady state, have macrophage/monocyte activation (represented by high levels of NP) that probably contributes to their chronic inflammatory condition.

Biologically active CD40 ligand is elevated in sickle cell anemia: potential role for platelet-mediated inflammation

OBJECTIVE

After activation, platelets expose CD40 ligand (CD40L) on their surface, then subsequently release the inflammatory mediator as a soluble fragment (sCD40L). Because sickle cell anemia (SCA) is noted for both platelet activation and chronic inflammation, we asked whether platelet-released CD40L potentially plays a role in SCA.

METHODS AND RESULTS

ELISAs demonstrate that SCA patient plasma contains 30-fold more sCD40L than control plasma. Correspondingly, platelets from these patients contain less than half the CD40L found in control platelets. Platelets from patients in painful crises are further depleted of CD40L, with even higher plasma levels, suggesting a correlation to the patient's clinical state. In addition, elevated sCD40L correlates with increased tissue factor in SCA plasma. Blockage of the CD40L receptor CD40 reduces SCA plasma-induced production of tissue factor and endothelial intercellular adhesion molecule-1 (ICAM-1). Finally, sCD40L activity in SCA plasma is confirmed by its induction of B-cell proliferation.

CONCLUSIONS

Platelet-derived sCD40L is elevated in SCA, further elevated in crises, and biologically active. The participation of sCD40L in SCA plasma-induced production of B cells, tissue factor, and ICAM-1 suggests that CD40L may contribute to the chronic inflammation and increased thrombotic activity known to occur in SCA.

Histamine increases sickle erythrocyte adherence to endothelium

Complications of sickle cell anaemia include vascular occlusion triggered by the adherence of sickle erythrocytes to endothelium in the postcapillary venules. Adherence can be promoted by inflammatory mediators that induce endothelial cell adhesion molecule expression and arrest flowing erythrocytes. The present study characterised the effect of histamine stimulation on the kinetics of sickle cell adherence to large vessel and microvascular endothelium under physiological flow. Increased sickle cell adherence was observed within minutes of endothelial activation by histamine and reached a maximum value within 30 min. At steady state, sickle cell adherence to histamine-stimulated endothelium was 47 +/- 4 adherent cells/mm(2), 2.6-fold higher than sickle cell adherence to unstimulated endothelial cells. Histamine-induced sickle cell adherence occurred rapidly and transiently. Studies using histamine receptor agonists and antagonists suggest that histamine-induced sickle cell adhesion depends on simultaneous stimulation of the H(2) and H(4) histamine receptors and endothelial P-selectin expression. These data show that histamine release may promote sickle cell adherence and vaso-occlusion. In vivo histamine release should be studied to determine its role in sickle complications and whether blocking of specific histamine receptors may prevent clinical complications or adverse effects from histamine release stimulated by opiate analgesic treatment.

Insights into elevated distortion product otoacoustic emissions in sickle cell disease: Comparisons of hydroxyurea-treated and non-treated young children

Distortion product otoacoustic emissions (DPOAEs) were examined in 15 normal-hearing African-American children between the ages of 6 and 14 years with homozygous sickle cell disease (SCD), who were on a regimen of hydroxyurea (HDU), a drug that reduces inflammatory processes and symptoms of SCD; a matched group of 15 African-American children with homozygous SCD not on HDU; and 15 African-American children with normal hemoglobin. DPOAEs were evoked by 13 primary tone pairs with f2 frequencies ranging from 1000 to 4500 Hz. Increased DPOAE amplitudes, believed to be a precursor of eventual hearing loss, were evident in children with SCD who were not receiving HDU. Those taking HDU had DPOAE amplitudes similar to normal controls. These findings suggest that HDU, in addition to reducing symptoms of SCD, may play a role in inhibiting or preventing cochlear pathology and hearing loss in individuals with SCD.

Polymorphisms of chemokine receptors and eNOS in Brazilian patients with sickle cell disease

Sickle cell disease (SCD) is an inherited disorder that presents extremely variable clinical manifestations. For the past few decades, it has been approached as an inflammatory disorder, and several researchers have tried to determine the factors involved in such characteristic. In order to contribute to the identification of the genetic differences underlying this phenotypic diversity in SCD, we proposed to study the distribution of polymorphic variants of the genes encoding the chemokine receptors CCR2 and CCR5, as well as three polymorphisms in the NOS3 gene, in Brazilian SCD patients. These genes are involved in the development of inflammatory immune reactions, a feature believed to be of extreme importance in SCD pathology. Our results indicate that the polymorphisms studied here are not directly associated with severe clinical manifestations in SCD patients. Nevertheless, we observed a tendency for the development of a severe clinical course in carriers of the variant alleles CCR2-64I and CCR5delta32 and in homozygotes for the -786C variant of the NOS3 gene. Further studies should be carried out in order to assess the role of such variants in the clinical picture of SCD.

Differential effects of hydroxyurea and zileuton on interleukin-13 secretion by activated murine spleen cells: implication on the expression of vascular cell adhesion molecule-1 and vasoocclusion in sickle cell anemia

BACKGROUND

Interleukin-13 (IL-13), a TH2 cytokine, upregulates the expression of vascular cell adhesion molecule-1 on endothelial cells, a factor involved in vasoocclusion in sickle cell disease (SCD). Hydroxyurea improves clinical status of SCD patients in part by induction of fetal hemoglobin. Its effect on IL-13 secretion has not been investigated.

OBJECTIVE

To determine whether hydroxyurea and zileuton, a hydroxyurea derivative with antiinflammatory properties, affect IL-13 secretion.

METHODS

We measured IL-13 in the supernatant of murine spleen cells incubated without and with hydroxyurea, zileuton (10 microg/ml), concanavalin A (2.5 microg/ml), and anti-CD3 (50 ng/ml) (n=8).

RESULTS

Hydroxyurea and zileuton do not affect baseline IL-13 secretion. Unexpectedly, hydroxyurea increases IL-13 levels above baseline (120%, 216.5%, [p<0.05] after 24 h and 48 h, respectively) in lymphocytes activated by anti-CD3, while zileuton reduces them by 59%-78% (p<0.005). In lymphocytes activated by concanavalin A, hydroxyurea and zileuton reduce IL-13 secretion by 24-36% and 50-87%, respectively (p<0.05). Hydroxyurea, but not zileuton, significantly inhibits spleen cell proliferative responses to mitogens (p<0.005).

CONCLUSION

Data suggest that hydroxyurea up-regulates IL-13 secretion in anti-CD3-activated lymphocytes through gene activation but not by altered cell proliferation. Increased IL-13 secretion may contribute to unresponsiveness of certain SCD patients to hydroxyurea. The potential benefit of zileuton in the management of vasoocclusion is discussed.

Induction of fetal haemoglobin expression in erythroid cells – A model based on iron availability signalling

The K562 cell line has erythroid origin and is used for the study of fetal haemoglobin (HbF) production after treatment with several drugs, such as hydroxyurea, cisplatin and cytosine arabinoside (Ara C). It represents an important tool for the study of cancer differentiation therapy and treatment of thalassaemia and sickle cell disease. Although subject to intense research, the mechanisms involved in the induction of HbF are not fully established, and the regulation of several genes and signalling pathways has been proposed. Using the methodology of differential display, we investigated the changes in gene expression in K562 cells treated with doxorubicin and aclarubicin, which induce HbF expression and cell cycle arrest. Several genes were shown to present differential expression patterns, many of them related to the iron signalling pathway. Particular attention was given to Ndrg1, expressed as early as 24 h after treatment, which can be regulated by iron and is involved with blocking of the cell cycle. A review of the literature shows that, similar to doxorubicin and aclarubicin, most of the drugs used to induce HbF present some kind of effect on the iron signalling pathway, activating in the cells the machinery necessary for the incorporation of extracellular iron. Considering these results, as well as the fact that in erythroid cells the synthesis of haemoglobin is of vital importance, we propose that the production of fetal haemoglobin in erythroid cells is highly dependent on the iron signalling pathway.

Immunosuppressive therapy for kidney transplant prevents vaso-occlusive crisis in a haemoglobin SC disease patient

Although the molecular basis of sickle cell disease (SCD) is well established, the wide variability in clinical manifestations still puzzles haematologists and clinicians. Recently, SCD started to be considered by different groups as a chronic inflammatory condition, where the inflammatory tendency of each individual could drive more or less severe clinical features. Here we describe a haemoglobin SC disease patient (heterozygous to both HbS and HbC variants) that experienced several vaso-occlusive crises before underwent a successful kidney transplantation. Since then (16 years ago), she is on uninterruped immunosuppressive therapy, and do not experienced any severe vaso-occlusive crisis. Considering SCD associated morbidity as a result of exacerbated immune responses, we suggest that the immunosuppressive therapy directed to the kidney graft maintenance is actually also helping in the control of the chronic inflammatory responses associated to SCD.

Endothelial cell P-selectin mediates a proinflammatory and prothrombogenic phenotype in cerebral venules of sickle cell transgenic mice

Whereas the adhesion of leukocytes and erythrocytes to vascular endothelium has been implicated in the vasooclusive events associated with sickle cell disease, the role of platelet-vessel wall interactions in this process remains undefined. The objectives of this study were to: 1) determine whether the adhesion of platelets and leukocytes in cerebral venules differs between sickle cell transgenic (betaS) mice and their wild-type (WT) counterparts (C57Bl/6) under both resting and posthypoxic conditions, and 2) define the contributions of P-selectin to these adhesion processes. Animals were anesthetized, and platelet and leukocyte interactions with endothelial cells of cerebral postcapillary venules were monitored and quantified using intravital fluorescence microscopy in WT, betaS, and chimeric mice produced by transplanting bone marrow from WT or betaS mice into WT or P-selectin-deficient (P-sel(-/-)) mice. Platelet and leukocyte adhesion to endothelial cells in both unstimulated and posthypoxic betaS mice were significantly elevated over WT levels. Chimeric mice involving bone marrow transfer from betaS mice to P-sel(-/-) mice exhibited a profound attenuation of both platelet and leukocyte adhesion compared with betaS bone marrow transfer to WT mice. These findings indicate that betaS mice assume both an inflammatory and prothrombogenic phenotype, with endothelial cell P-selectin playing a major role in mediating these microvascular responses.

Enhanced pulmonary and systemic response to endotoxin in transgenic sickle mice

Some suggest that sickle cell disease (SCD) is associated with a "proinflammatory state" that predisposes patients to acute chest syndrome in the setting of triggering factors. Conflicting data emerged when inflammation markers in SCD were compared with healthy individuals. Therefore, we examined transgenic sickle and control mice at baseline and with endotoxin (LPS) intraperitoneal injection to determine whether a proinflammatory state truly exists. At baseline, sickle mice had elevated levels of circulating leukocytes and soluble vascular cell adhesion molecule 1 (sVCAM-1). No other differences were observed at baseline or in response to saline. However, LPS challenge was associated with significant increases in mortality (p<0.05), airway tone (p<0.03), serum and bronchoalveolar lavage levels of cytokines tumor necrosis factor-alpha (p<0.03), interleukin-1beta (p<0.02), and sVCAM-1 (p<0.01) in sickle mice compared with control subjects. Furthermore, 4 hours after LPS, microarray analysis identified 413 genes differentially expressed in the sickle mice (n=5) compared with only 7 in the control subjects (n=5). No difference in lung parenchyma was observed by light microscopy. This enhanced response to LPS suggests that the sickle red blood cell confers a subclinical "proinflammatory state." This enhanced response to inflammatory insult, particularly by adhesion molecules such as sVCAM-1, could play a role in the increased susceptibility to pulmonary dysfunction that has been observed clinically in SCD.

High frequency of the CCR5delta32 variant among individuals from an admixed Brazilian population with sickle cell anemia

Homozygous sickle cell disease (SCD) has a wide spectrum of clinical manifestations. In Brazil, the main cause of death of individuals with SCD is recurrent infection. The CCR5delta32 allele, which confers relative resistance to macrophage-tropic HIV virus infection, probably has reached its frequency and world distribution due to other pathogens that target macrophage in European populations. In the present investigation a relatively higher prevalence (5.1%) of the CCR5delta32 allele was identified, by PCR amplification using specific primers, in 79 SCD patients when compared to healthy controls (1.3%) with the same ethnic background (Afro-Brazilians). Based on a hypothesis that considers SCD as a chronic inflammatory condition, and since the CCR5 chemokine receptor is involved in directing a Th1-type immune response, we suggest that a Th1/Th2 balance can influence the morbidity of SCD. If the presence of the null CCR5delta32 allele results in a reduction of the chronic inflammation state present in SCD patients, this could lead to differential survival of SCD individuals who are carriers of the CCR5delta32 allele. This differential survival could be due to the development of less severe infections and consequently reduced or less severe vaso-occlusive crises.