Hereditary Red Cell Disorders Research Articles

The many faces of sickle cell disease in children: complications in the appendicular skeleton.

Sickle cell disease (SCD) is a hereditary red cell disorder with clinical manifestations secondary to sickling or crescent-shaped distortion of the red blood cells. Musculoskeletal complications of SCD are often the main causes for acute and chronic morbidities in children with manifestations including osteomyelitis, osteoporosis and osteonecrosis. This article aims to familiarise the paediatric radiologist with appendicular skeletal complications of SCD in the paediatric population and their imaging appearance.

Successes and pitfalls in orphan drug development for sickle cell disease

AbstractSickle cell disease (SCD) is a hereditary red cell disorder with a large disease burden at a global level. In the United States and Europe, medicines may qualify for orphan designation (OD), a regulatory status that provides incentives to boost development. We evaluated the development of new therapies for SCD using data for OD granted in the United States and Europe over the last 2 decades (2000-2021). We analyzed their characteristics, pathophysiological targets, trends, and OD sponsors. We then investigated the approval outcomes, including the phase success rate and reasons for discontinuation across different variables. We identified 57 ODs for SCD: 43 (75.4%) small molecules, 32 (56.1%) for oral administration, and 36 (63.1%) for chronic use to prevent SCD complications. At the end of the study (2021), development of 34 of 57 ODs was completed. Four ODs were approved with a success rate of 11.8%. Products targeting upstream causative events of SCD pathophysiology had a 1.8 higher success rate compared with products targeting disease consequences. Large companies showed a fourfold higher success rate compared with small-medium enterprises. Failures in clinical development were mainly seen in phase 3 for a lack of efficacy on vaso-occlusive crisis as the primary study end point, likely related to variable definitions and heterogeneity of pain scoring and treatment. Both advances in SCD knowledge and regulatory incentives paved the way for new therapies for SCD. Our finding of high failure rates in late-stage clinical development signals the need for better early-stage predictive models, also in the context of meaningful clinical end points.

P1483: EPELEUTON, A NOVEL SYNTHETIC SECOND GENERATION W-3 FATTY ACID, PROTECTS HUMANIZED SICKLE CELL MICE AGAINST HYPOXIA/REOXYGENATION ORGAN DAMAGE

Background: Sickle cell disease (SCD) is a hereditary red cell disorder with high mortality and morbidity. Although crizanlizumab, a P-selectin inhibitor, and voxelotor, an oral anti-sickling agent, have been recently approved for clinical management of SCD, therapeutic options to limit acute events and to reduce disease progression are still required. An attempt to target inflammatory vasculopathy and to modulate inflammatory response has been made based on evidence in other diseases such as in cardiovascular disease looking to administration of ω-3 fatty acids. In humanized SCD mice, we previously showed that polyunsaturated fatty acid supplementation protects against acute sickle cell-related lung and liver damages during hypoxia/reoxygenation (H/R) induced vaso-occlusive crisis (VOCs) (Kalish B et al. Haematologica 2016). This agrees with the observation that the resolution process actively controlled by specialized pro-resolving lipid mediators is defective in SCD (Matte A et al, Blood 2019). Epeleuton (15-HEPE, 15 hydroxy eicosapentaenoic acid) is a novel synthetic second generation w-3 fatty acid which (i) has a favorable clinical safety profile, (ii) modulates systemic inflammation and triglyceride synthesis in patients with cardiometabolic disease (Climax J et al J Am Heart As 2020) and (ii) beneficially affects red cell indices in long-term studies in rats. Aims: To evaluate the impact of epeleuton on acute organ damage in a humanized mouse model of SCD. Methods: 3-4 month old male and female mice healthy control (Hbatm1(HBA)Tow Hbbtm3(HBG1,HBB)Tow) and Tim Townes sickle mice (SCD, Hba tm1(HBA)Tow Hbb tm2(HBG1,HBB*)Tow) were used. Animals were treated for 6 weeks with epeleuton 1,000 mg/kg once daily or vehicle by gavage. Mice underwent 10 hours of hypoxia (8% oxygen), followed by 3 hours of reoxygenation (21% oxygen) to mimic acute VOCs (Matte A et al, Blood 2019). Hematologic parameters and molecular analysis of target organs for SCD such as lung were carried out. Results: In SCD mice exposed to H/R stress, we found that epeleuton (i) reduces H/R induced hemolysis; (ii) normalizes tyrosine-phosphorylation profile of red cell membrane proteins; and (iii) decreases neutrophil count. In lungs of SCD mice exposed to H/R stress, we observed that epeleuton prevents the H/R induced activation of inflammatory and redox related transcription factors NF-kB, p65 and Nrf2 local inflammatory response compared with vehicle-treated animals. Epeleuton treated SCD mice exposed to H/R stress showed down-regulation of VCAM-1 and E-selectin, markers of inflammatory vasculopathy as well as reduction of lung protein oxidation and expression of anti-oxidant systems such as heme-oxygenase-1 (HO-1) or peroxiredoxin-2. Similar changes were also observed in livers of epeleuton-treated SCD mice exposed to H/R stress compared with vehicle-treated SCD animals. Of note, epeleuton prevented the H/R induced up-regulation of both VCAM-1 and ICAM-1, suggesting a direct impact of treatment on vascular activation and inflammation. Summary/Conclusion: In humanized SCD mice exposed to H/R stress to mimic acute VOCs, epeleuton acts as a multimodal agent targeting red cells, hemolysis, inflammatory response, and vascular dysfunction. Our data provide the rationale for epeleuton as a potential novel therapeutic option for clinical management of patients with SCD.

Transfusional Approach in Multi-Ethnic Sickle Cell Patients: Real-World Practice Data From a Multicenter Survey in Italy.

Sickle cell disease (SCD) is a worldwide distributed hereditary red cell disorder characterized by recurrent acute vaso-occlusive crises (VOCs and anemia). Gold standard treatments are hydroxycarbamide (HC) and/or different red blood cell (RBC) transfusion regimens to limit disease progression. Here, we report a retrospective study on 1,579 SCD patients (median age 23 years; 802 males/777 females), referring to 34 comprehensive Italian centers for hemoglobinopathies. Although we observed a similar proportion of Caucasian (47.9%) and African (48.7%) patients, Italian SCD patients clustered into two distinct overall groups: children of African descent and adults of Caucasian descent. We found a subset of SCD patients requiring more intensive therapy with a combination of HC plus chronic transfusion regimen, due to partial failure of HC treatment alone in preventing or reducing sickle cell-related acute manifestations. Notably, we observed a higher use of acute transfusion approaches for SCD patients of African descent when compared to Caucasian subjects. This might be related to (i) age of starting HC treatment; (ii) patients' low social status; (iii) patients' limited access to family practitioners; or (iv) discrimination. In our cohort, alloimmunization was documented in 135 patients (8.5%) and was more common in Caucasians (10.3%) than in Africans (6.6%). Alloimmunization was similar in male and female and more frequent in adults than in children. Our study reinforces the importance of donor-recipient exact matching for ABO, Rhesus, and Kell antigen systems for RBC compatibility as a winning strategy to avoid or limit alloimmunization events that negatively impact the clinical management of SCD-related severe complications.Clinical Trial RegistrationClinicalTrials.gov, identifier: NCT03397017.

Arteriolar Neovasculogenesis and Sinusoidal Collapse Are Pathologic Features of the Hematopoietic Stem Cell Niche in Sickle Cell Disease (SCD) Mice

Sickle cell disease is a worldwide distributed hereditary red cell disorder, caused by pathologic hemoglobin S (HbS). The main clinical manifestations of SCD are chronic hemolytic anemia and acute vaso-occlusion, leading to multiple end-organ complications. To what extent, vaso-occlusion may affect the bone marrow microenvironments that regulate hematopoiesis in SCD is poorly defined. Here, we first used quantitative 2-D and 3-D imaging analyses to study the bone marrow parenchyma. In 8-12 week-old SCD (SS) mice (humanized Townes model, SS), we observed a disorganized vasculature with both sinusoidal (laminin+ CD105+ Sca-1- alpha smooth muscle actin- ) and arteriolar (laminin+ CD105- Sca-1+ alpha smooth muscle actin+) structural abnormalities compared to healthy (AA) or HbS- carrier (SA) mice. The majority of sinusoids have either small or collapsed lumens, often filled with large Ter 119+ red blood cells (RBC) clumps, suggesting RBC sickling in localized areas. The RBC clumps involve significant numbers of Gr-1+/CD11b+ myeloid cells, which also are concentrated perisinusoidally consistent with a local inflammatory process. These features are amplified under hypoxia-reoxygenation conditions, used to mimick acute SCD vaso-occlusive crisis. Most strikingly, is the dramatic increase in small, tortuous artery/arteriole vessel formation, particularly in the central portions, i.e. non-endosteal regions, of the bone marrow cavity. Using laser scanning cytometry (LaSC) of whole femur sections, we determined a four fold increase in arterioles in the central bone marrow. In support of hypoxia induced pathways responsible for neovasculogenesis, we show that HIF-1alpha staining is dramatically increased in the bone marrow of SCD (SS) mice compared to healthy (AA) mice, and interestingly the distribution pattern also is concentrated to the central, non-endosteal portions of the marrow. Moreover the bone marrow supernatant, only in SS mice, exhibits high levels of vascular endothelial growth factor, VEGF in agreement with increased levels of HIF-1alpha. Because both the sinusoidal and arteriolar vascular structures are recognized components of the hematopoietic stem cell (HSC) niche, we explored the early stages of hematopoiesis by multiparameter flow cytometry. We found that the long term HSC population (Lin- Sca-1+ c-Kit+ CD48- CD150+) is reduced by 50% in SCD mice. Taken together, we propose a model for SCD bone marrow whereby vaso-occlusive events are accompanied by defects in both sinusoidal and arteriolar vessels and resultant severe tissue hypoxia. Finally, we speculate that the abnormal vascular niche structures in SS mice affect hematopoietic stem cell homeostasis, which requires further study. These findings may have significant implications for gene therapy protocols utilizing autologous hematopoietic stem cell transplantation. [Display omitted] DisclosuresNo relevant conflicts of interest to declare.

Tyrosine Phosphorylation Modulates Peroxiredoxin-2 Activity in Normal and Diseased Red Cells.

Peroxiredoxin-2 (Prx2) is the third most abundant cytoplasmic protein in red blood cells. Prx2 belongs to a well-known family of antioxidants, the peroxiredoxins (Prxs), that are widely expressed in mammalian cells. Prx2 is a typical, homodimeric, 2-Cys Prx that uses two cysteine residues to accomplish the task of detoxifying a vast range of organic peroxides, H2O2, and peroxynitrite. Although progress has been made on functional characterization of Prx2, much still remains to be investigated on Prx2 post-translational changes. Here, we first show that Prx2 is Tyrosine (Tyr) phosphorylated by Syk in red cells exposed to oxidation induced by diamide. We identified Tyr-193 in both recombinant Prx2 and native Prx2 from red cells as a specific target of Syk. Bioinformatic analysis suggests that phosphorylation of Tyr-193 allows Prx2 conformational change that is more favorable for its peroxidase activity. Indeed, Syk-induced Tyr phosphorylation of Prx2 enhances in vitro Prx2 activity, but also contributes to Prx2 translocation to the membrane of red cells exposed to diamide. The biologic importance of Tyr-193 phospho-Prx2 is further supported by data on red cells from a mouse model of humanized sickle cell disease (SCD). SCD is globally distributed, hereditary red cell disorder, characterized by severe red cell oxidation due to the pathologic sickle hemoglobin. SCD red cells show Tyr-phosphorylated Prx2 bound to the membrane and increased Prx2 activity when compared to healthy erythrocytes. Collectively, our data highlight the novel link between redox related signaling and Prx2 function in normal and diseased red cells.

Imatinib Protects Against Hypoxia/Reoxygenation Induced Lung and Kidney Injury in a Humanized Mouse Model for SCD

Sickle cell disease (SCD) is a worldwide distributed hereditary red cell disorder characterized by chronic hemolytic anemia in association with acute and chronic life-threatening complications mainly related to acute vaso-occlusive events (VOCs) due to amplified inflammatory response and defective pro-resolving events.Imatinib is an oral Tyrosine (Tyr)-kinase inhibitor, developed for the treatment of chronic myeloid leukemia (CML). Few case reports on SCD patients with CML undergoing imatinib treatment highlight the beneficial impact of imatinib on severity and recurrence of acute VOCs in SCD. In red blood cells (RBCs), Imatinib has been shown to interfere with Tyr-phosphorylation state of the integral membrane protein band 3, affecting RBC microparticle formation. Here, we study the actions of Imatinib on a model of acute VOCs using humanized SCD mice (Hbatm1(HBA)TowHbbtm2(HBG1,HBB*)Tow). We treated SCD and control healthy mice (AA, Hbatm1(HBA)Tow Hbbtm3(HBG1,HBB)Tow) (n=6-7 animals in each group) with Imatinib 50 mg/Kg/d for 2 weeks before hypoxia/Reoxygenation (H/R) stress used to mimic acute VOCs. Under normoxia, we found that in SCD mice Imatinib significantly reduced (i) Tyr-phosphorylation state of sickle red cell membrane proteins; (ii) the amount of phosphatidyl-serine (PS)+ sickle RBCs; and (iii) the release of erythroid microparticles, which was associated with accumulation of hemichromes and a more efficient erythrophagocytosis compared to vehicle treated animals. In SCD mice exposed to H/R stress, imatinib significantly decreased the H/R-induced (i) increase in peripheral neutrophil count; (ii) lung inflammatory cell infiltrate; (iii) kidney inflammatory cell infiltrate. In the lung of H/R SCD mice, Imatinib inhibited the H/R induced NF-kB activation and prevented the up-regulation of (i) pro-inflammatory cytokines such as ET-1; (ii) vascular endothelial activation markers (VCAM-1, ICAM-1); (iii) pro-fibrotic markers such as PDGF-B and (iv) the activation of UPR system. In the kidney of H/R SCD mice, Imatinib significantly reduced H/R induced expression of ET-1, VCAM-1 and E-selectin, which were again associated with inhibition of NF-kB. In addition, Imatinib significantly upregulated the expression of the microRNAs miR200a/b, which has been described to reduce renal fibrosis. Finally, in isolated aorta from Imatinib treated SCD exposed to H/R stress, a significant reduction in vascular activation markers was observed compared to vehicle treated animals. Collectively, our data indicate that Imatinib acts on multiple targets, modulating signal transduction and reducing inflammatory vasculopathy and extracellular matrix remodeling process related to VOC in SCD. Thus, Imatinib might represent a new therapeutic tool in clinical management of SCD patients. DisclosuresEl Nemer:Imara: Research Funding.

Reliability of the current newborn screening action value for beta thalassaemia disease detection in England: A prospective study.

Beta thalassaemias are a group of hereditary red cell disorders resulting in a reduced or absent production of the main adult haemoglobin, adult haemoglobin. In England, the NHS Sickle Cell & Thalassaemia Screening Programme recommends reporting newborn beta thalassaemia disease as an incidental finding when detected whilst screening for sickle cell disease. The current action value to initiate further investigations is 1.5% adult haemoglobin, using high-performance liquid chromatography or capillary electrophoresis. We examined the reliability of this action value. A 44-month country-wide prospective study using data from 13 newborn screening laboratories in England. There were 81 cases reported with an adult haemoglobin of 1.5% or less at first-line screen, of which nine were lost to follow-up. The six false-positive results were all of 32 weeks' gestation or less. Of the 66 true-positives, 36 had confirmatory molecular results (11 of these cases also have results from tandem mass spectrometry), 19 had clinical confirmation and 11 had the results of both parents available which were consistent with the screening result. There was one false-negative, a confirmed beta thalassaemia major case with an adult haemoglobin of 1.7%, above the action value at first-line screen but known to be at risk from parental results and therefore referred into clinical care by the laboratory. This study demonstrates a positive predictive value of 91.7%, with a specificity of 99.9% and a sensitivity of 98.5%. These results confirm the reliability of the current action value.

Imaging of musculoskeletal manifestations in sickle cell disease patients.

Sickle cell disease (SCD) is a hereditary red cell disorder with clinical manifestations secondary to sickling or crescent-shaped distortion of the red blood cells. Major clinical manifestations of SCD include haemolytic anaemia and vaso-occlusive phenomena resulting in ischaemic tissue injury and organ damage. Chronic sequelae of the anaemia and vaso-occlusive processes involving the musculoskeletal system include complications related to extramedullary haematopoiesis, osteonecrosis, myonecrosis and osteomyelitis. Sickle cell bone disease is one of the commonest clinical presentations. Awareness and knowledge of the imaging features related to these complications are essential for early diagnosis and prompt management. In this article, the pathophysiology and key imaging findings related to these complications are reviewed.

New Therapeutic Options: Alternates to Gene Therapy for Treating Hemoglobinopathies

Hemoglobinopathies are chronic, invalidating globally distributed hereditary red cell disorders, which impact patient survival and quality of life. Sickle cell disease (SCD) and β-thalassemias are the more frequent hemoglobinopathies worldwide. In both SCD and β-thalassemias, novel therapeutic strategies might be divided into (1) pathophysiology related therapies and (2) innovative curative therapeuties such as hematopoietic stem cell transplantation and gene therapy, the latter discussed in another presentation in this session. In the last two decades, studies have highlighted the biocomplexity of SCD and β-thalassemias and the need for the development of new therapeutic options targeting one or more of the mechanisms involved in their pathogenesis. In SCD, the pathophysiology related novel therapies might be divided into: (i)Molecules targeting sickling and red cell dehydration; (ii) Molecules targeting SCD vasculopathy and sickle cell-endothelial adhesive events; (iii) Molecules modulating SCD related oxidative stress. Since inflammatory vasculopathy is a key factor in SCD related organ damage, major efforts have been made to develop agents that interfere with SCD vasculopathy and adhesion events, involving sickle red cells, neutrophils and endothelial interplay. β-thalassemic syndromes are characterized by ineffective erythropoiesis, which plays a crucial role in anemia and in the development of extramedullar erythropoiesis. In β-thalassemic syndromes, pathophysiology related novel therapies might be divided into: (i) Agents reducing the ineffective erythropoiesis such the TRAP ligands, targeting the GDF11 pathway (sotatercept or luspatercept); (ii) Agents affecting Jak2 activation to reduce splenomegaly in β-thalassemia and (iii) Agents modulating hepcidin - erythropoiesis axis such as minihepcidins. The main goal of these molecules is to ameliorate the ineffective erythropoiesis resulting in increased hemoglobin levels with reduction of transfusion requirement, iron overload, and facilitating iron chelation therapy. This review highlights new therapeutic strategies in SCD and β-thalassemia and discusses future development, research implications, and possible directions toward future clinical trials. Disclosures De Franceschi: F. Hoffmann-La Roche Ltd, Basel, Switzerland: Research Funding.

Hypoxia-reperfusion affects osteogenic lineage and promotes sickle cell bone disease

AbstractSickle cell disease (SCD) is a worldwide distributed hereditary red cell disorder, characterized by severe organ complication. Sickle bone disease (SBD) affects a large part of the SCD patient population, and its pathogenesis has been only partially investigated. Here, we studied bone homeostasis in a humanized mouse model for SCD. Under normoxia, SCD mice display bone loss and bone impairment, with increased osteoclast and reduced osteoblast activity. Hypoxia/reperfusion (H/R) stress, mimicking acute vaso-occlusive crises (VOCs), increased bone turnover, osteoclast activity (RankL), and osteoclast recruitment (Rank) with upregulation of IL-6 as proresorptive cytokine. This was associated with further suppression of osteogenic lineage (Runx2, Sparc). To interfere with the development of SBD, zoledronic acid (Zol), a potent inhibitor of osteoclast activity/osteoclastogenesis and promoter of osteogenic lineage, was used in H/R-exposed mice. Zol markedly inhibited osteoclast activity and recruitment, promoting osteogenic lineage. The recurrent H/R stress further worsened bone structure, increased bone turnover, depressed osteoblastogenesis (Runx2, Sparc), and increased both osteoclast activity (RankL, Cathepsin k) and osteoclast recruitment (Rank) in SCD mice compared with either normoxic or single-H/R-episode SCD mice. Zol used before recurrent VOCs prevented bone impairment and promoted osteogenic lineage. Our findings support the view that SBD is related to osteoblast impairment, and increased osteoclast activity resulted from local hypoxia, oxidative stress, and the release of proresorptive cytokine such as IL-6. Zol might act on both the osteoclast and osteoblast compartments as multimodal therapy to prevent SBD.

Fentanyl Buccal Tablet: A New Breakthrough Pain Medication in Early Management of Severe Vaso-Occlusive Crisis in Sickle Cell Disease.

Sickle cell disease (SCD) is a worldwide distributed hereditary red cell disorder. The principal clinical manifestations of SCD are the chronic hemolytic anemia and the acute vaso-occlusive crisis (VOCs), which are mainly characterized by ischemic/reperfusion tissue injury. Pain is the main symptom of VOCs, and its management is still a challenge for hematologists, requiring a multidisciplinary approach. We carried out a crossover study on adult SCD patients, who received two different types of multimodal analgesia during two separate severe VOCs with time interval between VOCs of at least 6months. The first VOC episode was treated with ketorolac (0.86mg/kg/day) and tramadol (7.2mg/kg/day) (TK treatment). In the second VOC episode, fentanyl buccal tablet (FBT; 100μg) was introduced in a single dose after three hours from the beginning of TK analgesia (TKF treatment). We focused on the first 24hours of acute pain management. The primary efficacy measure was the time-weighted-sum of pain intensity differences (SPID24). The secondary efficacy measures included the pain intensity difference (PID), the total pain relief (TOTPAR), and the time-wighted sum of anxiety (SAID24). SPID24 was significantly higher in TKF than in TK treatment. All the secondary measures were significantly ameliorated in TKF compared to TK treatment, without major opioid side effects. Patients satisfaction was higher with TKF treatment than with TK one. We propose that VOCs might require breakthrough pain drug strategy as vaso-occlusive phenomena and enhanced vasoconstriction promoting acute ischemic pain component exacerbate the continuous pain of VOCs. FBT might be a powerful and feasible tool in early management of acute pain during VOCs in emergency departments.

Zoledronic Acid Reverses Acute Bone Impairment in a Mouse Model for Sickle Cell Disease

Sickle cell disease (SCD) is a worldwide distributed hereditary red cell disorder, characterized by the synthesis of pathological hemoglobin S (HbS). Up to now, limited studies in SCD patients have proposed a bone loss related to recurrent acute vaso-occlusive events (VOCs). Here, we designed a study in a humanized mouse model for SCD to evaluate (i) bone structure turnover and micro-architecture by histomorphometric approach; (ii) osteoblastic differentiation by RT-PCR analysis of bone runx2, sparc and alp gene expression. We used humanized healthy control (Hbatm1(HBA)TowHbbtm3(HBG1,HBB)Tow) and SCD (Hbatm1(HBA)TowHbbtm2(HBG1,HBB*)Tow) mice. Mice were divided into different groups as detailed in the enclosed flow-chart. In steady state, we first evaluated bone-marrow erythropoiesis by FACS analysis based on CD44-TER119 strategy. No signs of ineffective erythropoiesis were detectable in SCD mice compared to controls. Bone analysis was performed by histomorphometric approach after double labelling with demeclocycline followed by calcein to evaluate the dynamic parameters of bone turnover and analyzed by a specific software (bone3.1, Explora Nova, Larochelle, France). The histomorphometric bone analysis revealed (i) reduced bone volume with associated decreased trabecular number and increased trabecular separation; (ii) increased bone-turnover measured as bone formation rate (BFR) and activation frequency (AcF); (iii) decreased number of nodes (NdN) and node termini ratio; (iv) increased marrow star volume (MSV) and fractal dimension (D) compared to healthy mice. The bone molecular analysis revealed a significant down-regulation of runx2, sparc and alp gene expression in SCD mice compared to healthy ones. These data indicate a severe osteoporosis with bone fragility associated with alteration of osteogenic differentiation in SCD mice. Zoledronic acid (Zol) is the most powerful available bisphosphonate used to reduce bone turnover and bone fragility. Since VOCs are life-threatening complication of SCD and mainly involved skeletal system, requiring multidiscliplinary approach, we exposed SCD and control mice to hypoxia/reoxygenation (H/R) stress to mimic acute VOCs (see flow-chart). Mice were exposed to hypoxia (8% oxygen, 10 hours) followed by reoxygenation (21% oxygen) for either 18 hours to carry out molecular analysis or 10 days to carry out histomorphometric analysis. In H/R exposed vehicle treated SCD mice, we found (i) a significant increase in AcF (bone turnover), without differences in bone structure and microarchitecture compared to SCD mice under normoxia; (ii) a further reduction in osteogenic differentiation molecular markers. Zol (100 μg/ Kg in a single ip injection) was administrated either 7 days before (Zol-pre) or immediately after (Zol-post) H/R stress. In SCD mice, both Zol-pre and Zol-post significantly prevented the H/R induced increased bone turnover, while no differences were detectable in bone structure and microarchitecture compared to vehicle treated H/R SCD mice. The molecular analysis showed that Zol increased the osteogenic related gene expression, indicating a positive induction of osteogenic differentiation. Our data suggest that murine SCD is characterized by a significant bone impairment related to the unbalance between osteoblastic/osteoclastic activity in favor of osteoclastic one in presence of a down-regulation of osteogenic differentiation. In SCD, Zol plays a pivotal role decreasing osteoclastic activity and promoting osteogenic differentiation, representing a powerful new therapeutic strategy to limit bone disease in SCD. [Display omitted] DisclosuresNo relevant conflicts of interest to declare.

Rare hereditary red blood cell enzymopathies associated with hemolytic anemia - pathophysiology, clinical aspects, and laboratory diagnosis.

Hereditary red blood cell enzymopathies are genetic disorders affecting genes encoding red blood cell enzymes. They cause a specific type of anemia designated hereditary nonspherocytic hemolytic anemia (HNSHA). Enzymopathies affect cellular metabolism, which, in the red cell, mainly consists of anaerobic glycolysis, the hexose monophosphate shunt, glutathione metabolism, and nucleotide metabolism. Enzymopathies are commonly associated with normocytic normochromic hemolytic anemia. In contrast to other hereditary red cell disorders such as membrane disorders or hemoglobinopathies, the morphology of the red blood cell shows no specific abnormalities. Diagnosis is based on detection of reduced specific enzyme activity and molecular characterization of the defect on the DNA level. The most common enzyme disorders are deficiencies of glucose-6-phosphate dehydrogenase (G6PD) and pyruvate kinase (PK). However, there are a number of other enzyme disorders, often much less known, causing HNSHA. These disorders are rare and often underdiagnosed, and the purpose of this review. In this brief review, we provide an overview of clinically relevant enzymes, their function in red cell metabolism, and key aspects of laboratory diagnosis.

Pharmacological Inhibition of Calpain-1 Prevents Red Cell Dehydration and Reduces Gardos Channel Activity in a Mouse Model of Sickle Cell Disease. Identification of Druggable Protease Target

Abstract 852Sickle cell disease (SCD) is a hereditary red cell disorder characterized by the presence of pathological HbS, which polymerizes upon deoxygenation promoting red blood cell (RBC) dehydration and sickling. In SCD, the dense RBCs play a crucial role in the pathogenesis of sickle cell related organ damage and clinical manifestations. Although progress has been made in pathogenesis of SCD, the treatment options for SCD have limited pharmacological tools for clinical practice. Calpains are ubiquitous calcium-activated cysteine proteases, causing controlled proteolysis of protein substrates with regulatory functions. RBCs express only calpain-1, whose physiological function remains poorly understood. Gene inactivation of mouse calpain-1 revealed differential regulation of RBC calcium pump and enhanced RBC hydration. To investigate the relevance of these findings in SCD, we used BDA-410, a novel orally active inhibitor of calpain-1. Using the sickle (SAD) mouse, a model for human sickle cell disease, BDA-410 was administrated at the dosage of 30 mg/K/d by gavage to wild-type (WT) and sickle cell (SAD) mice. Animals were divided into 4 groups of 6 mice each: two groups from each strain were treated with BDA-410 for 14 days along with vehicle controls. Mice at baseline, day 7, and day 14 of BDA-410 treatment were evaluated for hematological parameters including the RBC density profile with phthalate density curves, RBC cation content, and Ca2+ activated K+ channel (Gardos channel) activity. BDA-410 induced a significant increase in Hct in both WT and SAD mice with no significant changes in Hb levels and an associated increased in MCV. The red cell K+ content increased significantly in SAD RBCs at day 7 and 14 of inhibitor treatment as compared to untreated SAD mice; whereas no major changes were observed in the WT RBCs. The mean corpuscular Hb concentration (CHCM) decreased in both WT and SAD mice treated with BDA-410. A left-shift in the RBC density curves was observed in SAD mice; whereas this left-shift was limited to a sub-fraction of denser red cells in the WT mice. The activity of the Gardos channel was significantly reduced in BDA-410 treated SAD mice compared to the untreated SAD group, while no significant differences were observed in the WT mice. Since the membrane-association of Peroxiredoxin-2 (Prx2) is increased in SCD RBCs, and has been correlated with Gardos channel activity, we evaluated Prx2-membrane association. BDA-410 treatment induced a significant reduction in the amount of Prx2 translocated to the membrane in both WT and SAD mice. Moreover, when we exposed WT and SAD mice to hypoxia (8% oxygen) for 48 hours, followed by 2 hours of re-oxygenation to mimic sickle cell related vaso-occlusive events, BDA-410 treatment prevented the hypoxia induced K+ loss and RBC dehydration in SAD mice. Identification of RBC membrane substrates in the calpain-1 null mice suggests that proteolytic modification of clapain targets as calcium pump, Prx2, and the Gardos channel protein may underpin some of the protective effects of BDA-410 in SAD mice. These results suggest that the inhibition of calpain-1 may offer a new therapeutic strategy to ameliorate hematological phenotype of SCD. Disclosures:No relevant conflicts of interest to declare.

Practical Diagnosis of Red Cell Disorders in Southern Spain

Background: Hereditary red cell disorders are associated with a protective effect against malaria, which results in an increased prevalence in malaria-endemic areas. Migratory flows from these areas are resulting in a marked increase in such abnormalities in Southern Spain. Methods: All hemoglobin disorders diagnosed between 1997 and 2010 have been recorded. Since 2008, we have performed systematic screening for hemoglobinopathies on African patients. A high-pressure liquid chromatography system was used as screening method for structural hemoglobinopathies and for separation of hemoglobin (Hb) F and A₂. Results: We detected 666 cases in patients of foreign origin and 308 in native Spanish patients. Thalassemias (thal) are the most frequent disorders amongst the local population: β-thal minor, 57.1% (176/308); α-thal, 18.2% (56/308), and δβ-thal, 7.8% (24/308). In ethnic minorities, there is a huge variety of hemoglobinopathies: heterozygous Hb S, 45% (300/666); heterozygous Hb C, 15% (100/666); β-thal minor, 13.7% (91/666); α-thal, 10.2% (68/666); Hb SS in 14 patients, and Hb CC in 9 patients. Of the native patients, 14 were found to have Hb AS and 9 Hb AC. Conclusion: Given the modern migratory flows, greater knowledge of these disorders is needed by all medical staff, and new practical and cost/time-effective diagnostic approaches have to be devised.

Deoxygenation affects tyrosine phosphoproteome of red cell membrane from patients with sickle cell disease

Sickle cell disease (SCD) is a worldwide distributed hereditary red cell disorder related to the production of a defective form of hemoglobin, hemoglobin S (HbS). One of the hallmarks of SCD is the presence of dense, dehydrate highly adhesive sickle red blood cells (RBCs) that result from persistent membrane damage associated with HbS polymerization, abnormal activation of membrane cation transports and generation of distorted and rigid red cells with membrane perturbation and cytoskeleton dysfunction. Although modulation of phosphorylation state of the proteins from membrane and cytoskeleton networks has been proposed to participate in red cell homeostasis, much still remains to be investigated in normal and diseased red cells. Here, we report that tyrosine (Tyr-) phosphoproteome of sickle red cells was different from normal controls and was affected by deoxygenation. We found proteins, p55 and band 4.1, from the junctional complex, differently Tyr-phosphorylated in SCD RBCs compared to normal RBCs under normoxia and modulated by deoxygenation, while band 4.2 was similarly Tyr-phosphorylated in both conditions. In SCD RBCs we identified the phosphopeptides for protein 4.1R located in the protein FERM domain (Tyr-13) and for α-spectrin located near or in a linker region (Tyr-422 and Tyr-1498) involving protein areas crucial for their functions in the context of red cell membrane properties, suggesting that Tyr-phosphorylation may be part of the events involved in maintaining membrane mechanical stability in SCD red cells.

Hereditary red cell disorders and malaria resistance

Human malaria is attributed to five species of the Plasmodium parasite (this includes the discovery that P. knowlesi infects humans[1][1]). The most virulent form of the disease is caused by P. falciparum , which continues to have a major impact on human populations: a third of the world’s

Laboratory tests to evaluate hereditary red cell disorders

PreviewPrimary care physicians need to be familiar with the distinctive clinical and laboratory characteristics of hereditary red cell disorders. Drs Monzon and Taylor profile the hemolytic anemias and describe the laboratory tests routinely used to diagnose them. They encourage open communication between clinician and pathologist.

Hereditary Red Cell Disorders in Southeast Asian Refugees and the Effect on the Prevalence of Thalassemia Disorders in the United States

This investigation established the frequency and prevalence of hemoglobin E, alpha and beta thalassemia, and glucose-6-phosphate dehydrogenase deficiency in a group of Southeast Asian individuals and determined the impact upon the prevalence of thalassemia disorders in the United States. The resettlement program of Southeast Asian refugees has significantly increased the total number of serious thalassemic disorders in the United States. For several generations Southeast Asian children will be the principal thalassemic group.