Dietary ω-3 fatty acids protect against vasculopathy in a transgenic mouse model of sickle cell disease

17(R)-Resolvin D1 protects against sickle cell-related inflammatory cardiomyopathy in humanized mice

ABSTRACT

Cardiovascular disease has been recognized as the main cause of death in adults with sickle cell disease (SCD). Although the exact mechanism linking SCD to cardiomyopathy remains elusive, a possible role of subclinical acute transient myocardial ischemia during acute sickle cell-related vaso-occlusive crises (VOCs) has been suggested. We approached SCD cardiomyopathy by integrated omics using humanized SS mice exposed to hypoxia/reoxygenation (H/R; 10 hours hypoxia followed by 3 hours reoxygenation) stress, mimicking acute VOCs. In sickle cell (SS) mice exposed to H/R, a neutrophil-driven cardiac hypertrophic response is initiated by cardiac proinflammatory pathways, intersecting proteins and micro RNA involved in profibrotic signaling. This response may be facilitated by local unresolved inflammation. We then examined the effect of 17(R)-resolvin D1 (17R-RvD1), a member of the specialized proresolving lipid mediator superfamily, administration on H/R-activated profibrotic and proangiogenic pathways. In SS mice, we found that 17R-RvD1 (1) modulates miRNAome; (2) prevents the activation of NF-κB p65; (3) protects against the H/R-induced activation of both platelet derived growth factor receptor and transforming growth factor (TGF)-β1/Smad2-3 canonical pathways; (4) reduces the expression of hypoxia-inducible factor-dependent proangiogenic signaling; and (5) decreases the H/R-induced proapoptotic cell signature. The protective role of 17R-RvD1 against H/R-induced maladaptive heart remodeling was supported by the reduction of galectin-3, procollagen C-proteinase enhancer-1, and endothelin-1 expression and perivascular fibrosis in SS mice at 3 days after H/R stress compared with vehicle-treated SS animals. Collectively, our data support the novel role of unresolved inflammation in pathologic heart remodeling in SCD mice in response to H/R stress. Our study provides new evidence for protective effects of 17R-RvD1 against SCD-related cardiovascular disease.

Disrupted homeostasis in sickle cells: Expanding the comprehension of metabolism adaptation and related therapeutic strategies

Sickle cell disease (SCD) is a hereditary hemolytic anemia associated with the alteration of the membrane composition of the sickle erythrocytes, the loss of glycolysis, dysregulation of the pyruvate phosphatase pathway, and changes in nucleotide metabolism of the sickle red blood cell (RBC). This review provides a comprehensive overview of the impact of the presence of Hb S, which leads to the disruption of the normal RBC metabolism. The intricate interplay between the redox and energetic balance in erythrocytic cells, where the glycolysis, pentose phosphate pathway, and methemoglobin reductase pathways are all altered in sickle RBC, is a key focus. Moreover, this review summarizes the current knowledge about the disease-modifying agents and their action mechanisms based on the sickle RBC alterations previously mentioned (i.e., their association with beneficial effects on the sickle cells' membrane, to their RBCs' energy metabolism, and to their oxidative status). Therefore, providing a comprehensive understanding of how sickle cells cope with the disruption of metabolic homeostasis and the most promising therapeutic agents able to ameliorate the various consequences of abnormal sickle RBC alterations.

A review on disease modifying pharmacologic therapies for sickle cell disease

Sickle cell disease (SCD) is an inherited hematologic disease caused by sickle hemoglobin as the predominant RBC hemoglobin or by sickle hemoglobin in combination with other abnormal β-hemoglobin variants like HbC, HbD and others. Sickling of erythrocytes under deoxygenated conditions is the basis of inflammatory and thrombotic cascades which result in multiple serious complications, leading to early morbidity and mortality. While HLA-matched allogeneic bone marrow transplantation is potentially curative, it has considerable limitations due to potential severe toxicities. Despite slow progress towards novel therapeutic strategies for SCD and hydroxyurea being the sole medication that is shown to reduce vaso-occlusive events and mortality for almost 20 years, several pharmacological agents targeting different mechanisms have been examined in clinical trials and recently US- US-FDA-approved, including L-glutamine and crizanlizumab. Voxelotor was previously US-FDA-approved but has been voluntarily withdrawn from the market as the overall benefit did not outweigh the risks. Gene therapies based on CRISPR-Cas9 and lentiviral vectors have been very recently approved. However, excessive costs are a barrier to widespread use. Nonetheless, there is still a large area of unmet needs for patients with SCD, and further research towards better care is warranted.

Targeted therapeutic management based on phytoconstituents for sickle cell anemia focusing on molecular mechanisms: Current trends and future perspectives

The global epidemic of Sickle cell anemia (SCA) is causing thousands of children to die. SCA, a genetic disorder affecting the hemoglobin-globin chain, affects millions globally. The primary physiological issue in these patients is the polymerization of sickle hemoglobin within their red blood cells (RBCs) during their deoxygenating state. The RBC undergoes a sickle shape due to the polymerization of mutant hemoglobin within it and membrane deformation during anoxic conditions. To prevent complications, it is essential to effectively stop the sickling of RBCs of the patients. Various medications have been studied for treating SCA patients, focusing on antisickling, γ-globulin induction, and antiplatelet action. Natural and synthetic anti-sickling agents can potentially reduce patient clinical morbidity. Numerous clinical trials focused on using natural remedies for the symptomatic therapy of SCA. Medicinal plants and phytochemical agents have antisickling properties. Recent studies on plant extracts' natural compounds have primarily focused on in vitro RBCs sickling studies, with limited data on in vivo studies. This review discussed the potential role of phytoconstituents in the management of SCA.

Novel therapeutic approaches in thalassemias, sickle cell disease, and other red cell disorders

ABSTRACT

In this last decade, a deeper understanding of the pathophysiology of hereditary red cell disorders and the development of novel classes of pharmacologic agents have provided novel therapeutic approaches to thalassemias, sickle cell disease (SCD), and other red cell disorders. Here, we analyze and discuss the novel therapeutic options according to their targets, taking into consideration the complex process of erythroid differentiation, maturation, and survival of erythrocytes in the peripheral circulation. We focus on active clinical exploratory and confirmatory trials on thalassemias, SCD, and other red cell disorders. Beside β-thalassemia and SCD, we found that the development of new therapeutic strategies has allowed for the design of clinic studies for hereditary red cell disorders still lacking valuable therapeutic alternative such as α-thalassemias, congenital dyserythropoietic anemia, or Diamond-Blackfan anemia. In addition, reduction of heme synthesis, which can be achieved by the repurposed antipsychotic drug bitopertin, might affect not only hematological disorders but multiorgan diseases such as erythropoietic protoporphyria. Finally, our review highlights the current state of therapeutic scenarios, in which multiple indications targeting different red cell disorders are being considered for a single agent. This is a welcome change that will hopefully expand therapeutic option for patients affected by thalassemias, SCD, and other red cell disorders.

Epeleuton, a novel synthetic ω-3 fatty acid, reduces hypoxia/ reperfusion stress in a mouse model of sickle cell disease

Inflammatory vasculopathy is critical in sickle cell disease (SCD)-associated organ damage. An imbalance between pro-inflammatory and pro-resolving mechanisms in response to different triggers such as hypoxia/reoxygenation or infections has been proposed to contribute to the progression of SCD. Administration of specialized pro-resolving lipid mediators may provide an effective therapeutic strategy to target inflammatory vasculopathy and to modulate inflammatory response. Epeleuton (15 hydroxy eicosapentaenoic acid ethyl ester) is a novel, orally administered, second-generation ω-3 fatty acid with a favorable clinical safety profile. In this study we show that epeleuton re-programs the lipidomic pattern of target organs for SCD towards a pro-resolving pattern. This protects against systemic and local inflammatory responses and improves red cell features, resulting in reduced hemolysis and sickling compared with that in vehicle-treated SCD mice. In addition, epeleuton prevents hypoxia/reoxygenation-induced activation of nuclear factor-κB with downregulation of the NLRP3 inflammasome in lung, kidney, and liver. This was associated with downregulation of markers of vascular activation in epeleuton-treated SCD mice when compared to vehicle-treated animals. Collectively our data support the potential therapeutic utility of epeleuton and provide the rationale for the design of clinical trials to evaluate the efficacy of epeleuton in patients with SCD.

Revolutionizing Cardiovascular Health with Nano Encapsulated Omega-3 Fatty Acids: A Nano-Solution Approach

Omega-3 polyunsaturated fatty acids (ω-3 PUFAs) offer diverse health benefits, such as supporting cardiovascular health, improving cognitive function, promoting joint and musculoskeletal health, and contributing to healthy aging. Despite their advantages, challenges like oxidation susceptibility, low bioavailability, and potential adverse effects at high doses persist. Nanoparticle encapsulation emerges as a promising avenue to address these limitations while preserving stability, enhanced bioavailability, and controlled release. This comprehensive review explores the therapeutic roles of omega-3 fatty acids, critically appraising their shortcomings and delving into modern encapsulation strategies. Furthermore, it explores the potential advantages of metal-organic framework nanoparticles (MOF NPs) compared to other commonly utilized nanoparticles in improving the therapeutic effectiveness of omega-3 fatty acids within drug delivery systems (DDSs). Additionally, it outlines future research directions to fully exploit the therapeutic benefits of these encapsulated omega-3 formulations for cardiovascular disease treatment.

Management of the Sickle Cell Trait: An Opinion by Expert Panel Members

The number of individuals with the sickle cell trait exceeds 300 million worldwide, making sickle cell disease one of the most common monogenetic diseases globally. Because of the high frequency of sickle cell disease, reproductive counseling is of crucial importance. In addition, unlike other carrier states, Sickle Cell Trait (SCT) seems to be a risk factor for several clinical complications, such as extreme exertional injury, chronic kidney disease, and complications during pregnancy and surgery. This expert panel believes that increasing knowledge about these clinical manifestations and their prevention and management can be a useful tool for all healthcare providers involved in this issue.

Erythrocyte pyruvate kinase activation in red cell disorders

PURPOSE OF REVIEW

In red cells, pyruvate kinase is a key enzyme in the final step of glycolytic degradative process, which generates a constant energy supply via ATP production. This commentary discusses recent findings on pyruvate kinase activators as new therapeutic option in hereditary red cell disorders such as thalassemic syndromes or sickle cell disease (SCD).

RECENT FINDINGS

Mitapivat and etavopivat are two oral pyruvate kinase activators. Studies in a mouse model for β thalassemia have shown beneficial effects of mitapivat on both red cell survival and ineffective erythropoiesis, with an amelioration of iron homeostasis. This was confirmed in a proof-of-concept study in patients with nontransfusion-dependent thalassemias. Both mitapivat and etavopivat have been evaluated in mouse models for SCD, showing an increased 2-3DPG/ATP ratio and a reduction in haemolysis as well as in sickling. These data were confirmed in proof-of-concept clinical studies with both molecules carried in patients with SCD.

SUMMARY

Preclinical and clinical evidence indicate that pyruvate kinase activators represent new therapeutic option in hemoglobinopathies or SCD. Other red cell disorders such as hereditary spherocytosis or hereditary anaemias characterized by defective erythropoiesis might represent additional areas to investigate the therapeutic impact of pyruvate kinase activators.

Pathophysiological characterization of the Townes mouse model for sickle cell disease

A deeper pathophysiologic understanding of available mouse models of sickle cell disease (SCD), such as the Townes model, will help improve preclinical studies. We evaluated groups of Townes mice expressing either normal adult human hemoglobin (HbA), sickle cell trait (HbAS), or SCD (HbS), comparing younger versus older adults, and females versus males. We obtained hematologic parameters in steady-state and hypoxic conditions and evaluated metabolic markers and cytokines from serum. Kidney function was evaluated by measuring the urine protein/creatinine ratio and urine osmolality. In vivo studies included von Frey assay, non-invasive plethysmography, and echocardiography. Histopathological evaluations were performed in lung, liver, spleen, and kidney tissues. HbS mice displayed elevated hemolysis markers and white blood cell counts, with some increases more pronounced in older adults. After extended in vivo hypoxia, hemoglobin, platelet counts, and white blood cell counts decreased significantly in HbS mice, whereas they remained stable in HbA mice. Cytokine analyses showed increased TNF-alpha in HbS mice. Kidney function assays revealed worsened kidney function in HbS mice. The von Frey assay showed a lower threshold to response in the HbS mice than controls, with more noticeable differences in males. Echocardiography in HbS mice suggested left ventricular hypertrophy and dilatation. Plethysmography suggested obstructive lung disease and inflammatory changes in HbS mice. Histopathological studies showed vascular congestion, increased iron deposition, and disruption of normal tissue architecture in HbS mice. These data correlate with clinical manifestations in SCD patients and highlight analyses and groups to be included in preclinical therapeutic studies.

Hidden Comorbidities in Asthma: A Perspective for a Personalized Approach

Bronchial asthma is the most frequent inflammatory non-communicable condition affecting the airways worldwide. It is commonly associated with concomitant conditions, which substantially contribute to its burden, whether they involve the lung or other districts. The present review aims at providing an overview of the recent acquisitions in terms of asthma concomitant systemic conditions, besides the commonly known respiratory comorbidities. The most recent research has highlighted a number of pathobiological interactions between asthma and other organs in the view of a shared immunological background underling different diseases. A bi-univocal relationship between asthma and common conditions, including cardiovascular, metabolic or neurodegenerative diseases, as well as rare disorders such as sickle cell disease, α1-Antitrypsin deficiency and immunologic conditions with hyper-eosinophilia, should be considered and explored, in terms of diagnostic work-up and long-term assessment of asthma patients. The relevance of that acquisition is of utmost importance in the management of asthma patients and paves the way to a new approach in the light of a personalized medicine perspective, besides targeted therapies.

In Humanized Sickle Cell Mice, Imatinib Protects Against Sickle Cell-Related Injury

Drug repurposing is a valuable strategy for rare diseases. Sickle cell disease (SCD) is a rare hereditary hemolytic anemia accompanied by acute and chronic painful episodes, most often in the context of vaso-occlusive crisis (VOC). Although progress in the knowledge of pathophysiology of SCD have allowed the development of new therapeutic options, a large fraction of patients still exhibits unmet therapeutic needs, with persistence of VOCs and chronic disease progression. Here, we show that imatinib, an oral tyrosine kinase inhibitor developed for the treatment of chronic myelogenous leukemia, acts as multimodal therapy targeting signal transduction pathways involved in the pathogenesis of both anemia and inflammatory vasculopathy of humanized murine model for SCD. In addition, imatinib inhibits the platelet-derived growth factor-B-dependent pathway, interfering with the profibrotic response to hypoxia/reperfusion injury, used to mimic acute VOCs. Our data indicate that imatinib might be considered as possible new therapeutic tool for chronic treatment of SCD.

Plasma levels of E-selectin are associated with retinopathy in sickle cell disease

BACKGROUND

The vascular endothelium is markedly disrupted in sickle cell disease (SCD) and is the converging cascade of the complex pathophysiologic processes linked to sickle cell vasculopathy. Circulating endothelial activation and/or apoptotic markers may reflect this endothelial activation/damage that contributes to the pathophysiology of the SCD vascular complications.

METHODS

Plasmatic levels of circulating endothelial cells (CECs), E-selectin, progenitor's endothelial cells (EPCs), and circulating extracellular vesicles (EVs) were evaluated in 50 SCD patients, 16 with vasculopathy. The association between these markers and the occurrence of disease-related microvascular injuries of the eye (retinopathy), kidney (nephropathy), and skin (chronic active ulcers) was explored.

RESULTS

Among the endothelial activation markers studied, only higher plasma levels of E-selectin were found in SCD patients with vasculopathy (p = .015). Increased E-selectin levels were associated with retinopathy (p < .001) but not with nephropathy or leg ulcers. All patients, at steady state, with or without vasculopathy, did not display a high count of CEC and EPC, markers of endothelial injury and repair. We did not show any significant differences in EVs levels between vasculopathy and not vasculopathy SCD patients.

CONCLUSIONS

Further studies will be required to determine whether the E-selectin could be used as an early biomarker of retinopathy sickle cell development.

Treatment with recombinant ADAMTS13, alleviates hypoxia/reoxygenation-induced pathologies in a mouse model of human sickle cell disease

BACKGROUND

Sickle cell disease (SCD) is an inherited red blood cell disorder with a causative substitution in the beta-globin gene that encodes beta-globin in hemoglobin. Furthermore, the ensuing vasculopathy in the microvasculature involves heightened endothelial cell adhesion, inflammation, and coagulopathy, all of which contribute to vaso-occlusive crisis (VOC) and the sequelae of SCD. In particular, dysregulation of the von Willebrand factor (VWF) and a disintegrin and metalloproteinase with thrombospondin type 1 motif, member 13 (ADAMTS13) axis has been implicated in human SCD pathology.

OBJECTIVES

To investigate the beneficial potential of treatment with recombinant ADAMTS13 (rADAMTS13) to alleviate VOC.

METHODS

Pharmacologic treatment with rADAMTS13 in vitro or in vivo was performed in a humanized mouse model of SCD that was exposed to hypoxia/reoxygenation stress as a model of VOC. Then, pharmacokinetic, pharmacodynamic, and behavioral analyses were performed.

RESULTS

Administration of rADAMTS13 to SCD mice dose-dependently increased plasma ADAMTS13 activity, reduced VWF activity/antigen ratios, and reduced baseline hemolysis (free hemoglobin and total bilirubin) within 24 hours. rADAMTS13 was administered in SCD mice, followed by hypoxia/reoxygenation stress, and reduced VWF activity/antigen ratios in parallel to significantly (p < .01) improved recovery during the reoxygenation phase. Consistent with the results in SCD mice, we demonstrate in a human in vitro system that treatment with rADAMTS13 counteracts the inhibitory activity of hemoglobin on the VWF/ADAMTS13-axis.

CONCLUSION

Collectively, our data provide evidence that relative ADAMTS13 insufficiency in SCD mice is corrected by pharmacologic treatment with rADAMTS13 and provides an effective disease-modifying approach in a human SCD mouse model.

Real-World Evidence on Disease Burden and Economic Impact of Sickle Cell Disease in Italy

A real-world analysis was conducted in Italy among sickle cell disease (SCD) patients to evaluate the epidemiology of SCD, describe patients' characteristics and the therapeutic and economic burden. A retrospective analysis of administrative databases of various Italian entities was carried out. All patients with ≥1 hospitalization with SCD diagnosis were included from 01/2010-12/2017 (up to 12/2018 for epidemiologic analysis). The index date corresponded to the first SCD diagnosis. In 2018, SCD incidence rate was 0.93/100,000, the prevalence was estimated at 13.1/100,000. Overall, 1816 patients were included. During the 1st year of follow-up, 50.7% of patients had one all-cause hospitalization, 27.8% had 2, 10.4% had 3, and 11.1% had ≥4. Over follow-up, 6.1-7.2% of patients were treated with SCD-specific, 58.4-69.4% with SCD-related, 60.7-71.3% with SCD-complications-related drugs. Mean annual number per patient of overall treatments was 14.9 ± 13.9, hospitalizations 1.1 ± 1.1, and out-patient services 5.3 ± 7.6. The total mean direct cost per patient was EUR 7918/year (EUR 2201 drugs, EUR 3320 hospitalizations, and EUR 2397 out-patient services). The results from this real-world analysis showed a high disease burden for SCD patients with multiple hospitalizations during the follow-up. High healthcare resource utilization and costs were associated with patient' management and were most likely underestimated since indirect costs and Emergency Room admissions were not included.

Magnesium homeostasis in deoxygenated sickle erythrocytes is modulated by endothelin-1 via Na+ /Mg2+ exchange

Painful crises in sickle cell disease (SCD) are associated with increased plasma cytokines levels, including endothelin-1 (ET-1). Reduced red cell magnesium content, mediated in part by increased Na⁺ /Mg²⁺ exchanger (NME) activity, contributes to erythrocyte K⁺ loss, dehydration and sickling in SCD. However, the relationship between ET-1 and the NME in SCD has remained unexamined. We observed increased NME activity in sickle red cells incubated in the presence of 500 nM ET-1. Deoxygenation of sickle red cells, in contrast, led to decreased red cell NME activity and cellular dehydration that was reversed by the NME inhibitor, imipramine. Increased NME activity in sickle red cells was significantly blocked by pre-incubation with 100 nM BQ788, a selective blocker of ET-1 type B receptors. These results suggest an important role for ET-1 and for cellular magnesium homeostasis in SCD. Consistent with these results, we observed increased NME activity in sickle red cells of three mouse models of sickle cell disease greater than that in red cells of C57BL/J6 mice. In vivo treatment of BERK sickle transgenic mice with ET-1 receptor antagonists reduced red cell NME activity. Our results suggest that ET-1 receptor blockade may be a promising therapeutic approach to control erythrocyte volume and magnesium homeostasis in SCD and may thus attenuate or retard the associated chronic inflammatory and vascular complications of SCD.

Functional foods: promising therapeutics for Nigerian Children with sickle cell diseases

Sickle cell disease (SCD), also known as sickle cell anemia (SCA) is one of the structural hemoglobinopathies that occurs due to a single nucleotide mutation from GAG to GTG, which changes the amino acid of a β-globin chain of hemoglobin (Hb) from glutamate to valine. This singular mutation results to disorderliness in red blood cells (RBCs) with advent of changes in RBC morphology and other pathological conditions. In the 1980s, intermittent red blood cell transfusions, opioids, and penicillin prophylaxis were the only available therapy for SCA and were commonly reserved for acute, life threatening complications. So far, the US Food and Drug Administration (FDA) has granted a total of four drugs approval for the prophylaxis and treatment of the clinical complications of SCD. Due to limitations (adherence, safety, adverse effects) of existing therapies in the prophylaxis and treatment of SCD complications in Nigerian children and their inaccessibility to approved drugs, the present study discusses the therapeutic effects of readily available functional food as one of the therapies or an adjunct therapy to tackle the sickle cell crisis in Nigerian Children.

Dietary alpha-linolenic acid reduces platelet activation and collagen-mediated cell adhesion in sickle cell disease mice

BACKGROUND

Sickle cell disease (SCD) is a genetic hemoglobinopathy associated with high morbidity and mortality. The primary cause of hospitalization in SCD is vaso-occlusive crisis (VOC), mediated by alteration of red blood cells, platelets, immune cells and a pro-adhesive endothelium.

OBJECTIVES

We investigated the potential therapeutic use of the plant-derived omega-3 alpha-linolenic acid (ALA) in SCD.

METHODS

Berkeley mice were fed a low- or high-ALA diet for 4 weeks, followed by analysis of liver fibrosis, endothelial activation, platelet activation and formation of platelet-neutrophils aggregates. Aggregation of platelets over collagen under flow after high-ALA was compared to a blocking P-selectin Fab.

RESULTS

Dietary high-ALA was able to reduce the number of sickle cells in blood smear, liver fibrosis, and the expression of adhesion molecules on the endothelium of aorta, lungs, liver and kidneys (VCAM-1, ICAM-1 and vWF). Specific parameters of platelet activation were blunted after high-ALA feeding, notably P-selectin exposure and the formation of neutrophil-platelet aggregates, along with a correspondingly reduced expression of PSGL-1 on neutrophils. By comparison, in vivo treatment of SCD mice with the anti-P-selectin Fab was able to similarly reduce the formation of neutrophil-platelet aggregates, but did not reduce GpIbα shedding nor the activation of the αIIb β3 integrin in response to thrombin. Both ALA feeding and P-selectin blocking significantly reduced collagen-mediated cell adhesion under flow.

CONCLUSIONS

Dietary ALA is able to reduce the pro-inflammatory and pro-thrombotic state occurring in the SCD mouse model and may represent a novel, inexpensive and readily available therapeutic strategy for SCD.

Adaptative Up-Regulation of PRX2 and PRX5 Expression Characterizes Brain from a Mouse Model of Chorea-Acanthocytosis

The peroxiredoxins (PRXs) constitute a ubiquitous antioxidant. Growing evidence in neurodegenerative disorders such as Parkinson’s disease (PD) or Alzheimer’s disease (AD) has highlighted a crucial role for PRXs against neuro-oxidation. Chorea-acanthocytosis/Vps13A disease (ChAc) is a devastating, life-shortening disorder characterized by acanthocytosis, neurodegeneration and abnormal proteostasis. We recently developed a Vps13a^−/− ChAc-mouse model, showing acanthocytosis, neurodegeneration and neuroinflammation which could be restored by LYN inactivation. Here, we show in our Vps13a^−/− mice protein oxidation, NRF2 activation and upregulation of downstream cytoprotective systems NQO1, SRXN1 and TRXR in basal ganglia. This was associated with upregulation of PRX2/5 expression compared to wild-type mice. PRX2 expression was age-dependent in both mouse strains, whereas only Vps13a^−/− PRX5 expression was increased independent of age. LYN deficiency or nilotinib-mediated LYN inhibition improved autophagy in Vps13a^−/− mice. In Vps13a^−/−; Lyn^−/− basal ganglia, absence of LYN resulted in reduced NRF2 activation and down-regulated expression of PRX2/5, SRXN1 and TRXR. Nilotinib treatment of Vps13a^−/− mice reduced basal ganglia oxidation, and plasma PRX5 levels, suggesting plasma PRX5 as a possible ChAc biomarker. Our data support initiation of therapeutic Lyn inhibition as promptly as possible after ChAc diagnosis to minimize development of irreversible neuronal damage during otherwise inevitable ChAc progression.

Dietary ω-3 Fatty Acid Supplementation Improves Murine Sickle Cell Bone Disease and Reprograms Adipogenesis

Sickle cell disease (SCD) is a genetic disorder of hemoglobin, leading to chronic hemolytic anemia and multiple organ damage. Among chronic organ complications, sickle cell bone disease (SBD) has a very high prevalence, resulting in long-term disability, chronic pain and fractures. Here, we evaluated the effects of ω-3 (fish oil-based, FD)-enriched diet vs. ω-6 (soybean oil-based, SD)- supplementation on murine SBD. We exposed SCD mice to recurrent hypoxia/reoxygenation (rec H/R), a consolidated model for SBD. In rec H/R SS mice, FD improves osteoblastogenesis/osteogenic activity by downregulating osteoclast activity via miR205 down-modulation and reduces both systemic and local inflammation. We also evaluated adipogenesis in both AA and SS mice fed with either SD or FD and exposed to rec H/R. FD reduced and reprogramed adipogenesis from white to brown adipocyte tissue (BAT) in bone compartments. This was supported by increased expression of uncoupling protein 1(UCP1), a BAT marker, and up-regulation of miR455, which promotes browning of white adipose tissue. Our findings provide new insights on the mechanism of action of ω-3 fatty acid supplementation on the pathogenesis of SBD and strengthen the rationale for ω-3 fatty acid dietary supplementation in SCD as a complementary therapeutic intervention.

Therapeutic targeting of Lyn kinase to treat chorea-acanthocytosis

Chorea-Acanthocytosis (ChAc) is a devastating, little understood, and currently untreatable neurodegenerative disease caused by VPS13A mutations. Based on our recent demonstration that accumulation of activated Lyn tyrosine kinase is a key pathophysiological event in human ChAc cells, we took advantage of Vps13a^−/− mice, which phenocopied human ChAc. Using proteomic approach, we found accumulation of active Lyn, γ-synuclein and phospho-tau proteins in Vps13a^−/− basal ganglia secondary to impaired autophagy leading to neuroinflammation. Mice double knockout Vps13a^−/− Lyn^−/− showed normalization of red cell morphology and improvement of autophagy in basal ganglia. We then in vivo tested pharmacologic inhibitors of Lyn: dasatinib and nilotinib. Dasatinib failed to cross the mouse brain blood barrier (BBB), but the more specific Lyn kinase inhibitor nilotinib, crosses the BBB. Nilotinib ameliorates both Vps13a^−/− hematological and neurological phenotypes, improving autophagy and preventing neuroinflammation. Our data support the proposal to repurpose nilotinib as new therapeutic option for ChAc patients.

Sickle Cell Disease: Role of Oxidative Stress and Antioxidant Therapy

Sickle cell disease (SCD) is the most common hereditary disorder of hemoglobin (Hb), which affects approximately a million people worldwide. It is characterized by a single nucleotide substitution in the β-globin gene, leading to the production of abnormal sickle hemoglobin (HbS) with multi-system consequences. HbS polymerization is the primary event in SCD. Repeated polymerization and depolymerization of Hb causes oxidative stress that plays a key role in the pathophysiology of hemolysis, vessel occlusion and the following organ damage in sickle cell patients. For this reason, reactive oxidizing species and the (end)-products of their oxidative reactions have been proposed as markers of both tissue pro-oxidant status and disease severity. Although more studies are needed to clarify their role, antioxidant agents have been shown to be effective in reducing pathological consequences of the disease by preventing oxidative damage in SCD, i.e., by decreasing the oxidant formation or repairing the induced damage. An improved understanding of oxidative stress will lead to targeted antioxidant therapies that should prevent or delay the development of organ complications in this patient population.

Genetic Analysis of Patients With Sickle Cell Anemia and Stroke Before 4 Years of Age Suggest an Important Role for Apoliprotein E

BACKGROUND

Ischemic stroke is a devastating complication affecting children with sickle cell anemia. Genetic factors are likely to be important in determining the risk of stroke but are poorly defined.

METHODS

We have studied a cohort of 19 children who had an overt ischemic stroke before 4 years of age. We predicted genetic determinants of stroke would be more prominent in this group. We performed whole exome sequencing on this cohort and applied 2 hypotheses to our variant filtering. First, we looked for strong, potentially mono- or oligogenic variants for ischemic stroke, and second, we considered that more common polygenic variants will be enriched in our cohort. Candidate variants emerging from both strategies were validated in a cohort of 283 patients with sickle cell anemia and known pediatric cerebrovascular outcomes. We used principal component analysis in this cohort to control for relatedness and population substructure.

RESULTS

Our primary finding was that the Apoliprotein E genotypes ε2/ε4 and ε4/ ε4, defined by the interplay of rs7412 and rs429358, were associated with increased stroke risk, with an odds ratio of 4.35 ([95% CI, 1.85-10.0] P=0.0011) for ischemic stroke in the validation cohort. We also found that rs2297518 in NOS (NO synthase) 2 (odds ratio, 2.25 [95% CI, 1.21-4.19]; P=0.014) and rs2230123 in signal transducer and activator of transcription (odds ratio, 2.60 [95% CI, 1.30-5.20]; P=0.009) both had increased odds ratios for ischemic stroke, although these two variants were below the threshold for statistical significance after correction for multiple testing.

CONCLUSIONS

These data identify new loci for future functional investigations into cerebrovascular disease in sickle cell anemia. Based on African population reference allele frequencies, the Apoliprotein E genotypes would be present in about 10% of children with sickle cell anemia and represent a genetic risk factor that is potentially modifiable by both dietary and pharmaceutical manipulation of its dyslipidemic effects.

Biochemical and therapeutic effects of Omega-3 fatty acids in sickle cell disease

Sickle cell disease (SCD) is a hematologic disorder with complex pathophysiology that includes chronic hemolysis, vaso-occlusion and inflammation. Increased leukocyte-erythrocyte-endothelial interactions, due to upregulated expression of adhesion molecules and activated endothelium, are thought to play a primary role in initiation and progression of SCD vaso-occlusive crisis and end-organ damage. Several new pathophysiology-based therapeutic options for SCD are being developed, chiefly targeting the inflammatory pathways. Omega-3 fatty acids are polyunsaturated fatty acids that are known to have effects on diverse physiological processes. Eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) are the principal biologically active omega-3 fatty acids. The therapeutic effects of DHA and EPA on chronic inflammatory disorders and cardiovascular diseases are well recognized. The therapeutic effects of omega-3 fatty acids are attributed to their anti-inflammatory and anti-thrombotic eicosanoids, and the novel class of EPA and DHA derived lipid mediators: resolvins, protectins and maresins. Blood cell membranes of patients with SCD have abnormal fatty acids composition characterized by high ratio of pro-inflammatory arachidonic acid (AA) to anti-inflammatory DHA and EPA (high omega-6/omega-3 ratio). In addition, experimental and clinical studies provide evidence that treatment with DHA does confer improvement in rheological properties of sickle RBC, inflammation and hemolysis. The clinical studies have shown improvements in VOC rate, markers of inflammation, adhesion, and hemolysis. In toto, the results of studies on the therapeutic effects of omega-3 fatty acids in SCD provide good body of evidence that omega-3 fatty acids could be a safe and effective treatment for SCD.

Development of Algorithm for Clinical Management of Sickle Cell Bone Disease: Evidence for a Role of Vertebral Fractures in Patient Follow-up

Sickle-cell disease (SCD) is a worldwide distributed hemoglobinopathy, characterized by hemolytic anemia associated with vaso-occlusive events. These result in acute and chronic multiorgan damage. Bone is early involved, leading to long-term disability, chronic pain and fractures. Here, we carried out a retrospective study to evaluate sickle bone disease (SBD) in a cohort of adults with SCD. We assessed bone density, metabolism and turnover. We also evaluated the presence of fractures and the correlation between SCD severity and skeletal manifestations. A total of 71 patients with SCD were analyzed. The mean age of population was 39 ± 10 years, 56% of which were females. We found osteoporosis in a range between 7% and 18% with a high incidence of vertebral fractures. LDH and AST were predictive for the severity of vertebral fractures, while bone density was not. Noteworthy, we identified -1.4 Standard Deviations T-score as the cutoff for detecting the presence of fractures in patients with SCD. Collectively our data allowed us to develop an algorithm for the management of SBD, which may be useful in daily clinical practice to early intersect and treat SBD.

Effect of High-dose Vitamin A Supplementation in Children With Sickle Cell Disease: A Randomized, Double-blind, Dose-finding Pilot Study

Suboptimal vitamin A status (serum retinol <30 µg/dL) is associated with poor clinical outcomes in children with the hemoglobin-SS disease (HbSS), and supplementation with the recommended daily allowance of retinol is ineffective in improving vitamin A status. In a single-center randomized blinded dose-finding pilot study, we compared vitamin A and nutritional status in children with HbSS to healthy children and explored the impact of high-dose supplementation on the primary outcome serum vitamin A status. Exploratory outcomes included hematologic, nutritional, immunologic, and muscle function status in children with HbSS. A mixed-effects linear regression model evaluated associations between vitamin A dose, serum retinol, and exploratory outcomes. Twenty healthy children participated, and 22 subjects with HbSS were randomized to oral 3000 or 6000 IU/d retinol for 8 weeks; 21 subjects completed all evaluations. Serum retinol, growth, and nutritional status were all suboptimal in HbSS subjects at baseline, and supplementation did not change vitamin A status. Fetal hemoglobin (Δ=2.5, 95% confidence interval [CI], 0.5-4.3), mean corpuscular volume (Δ=2.7, 95% CI, 0.7-4.7), mean corpuscular hemoglobin (Δ=1.4, 95% CI, 0.5-2.3), and mean corpuscular hemoglobin concentration (Δ=0.5, 95% CI, 0.1-0.9) all improved with supplementation. Mild improvements in erythrocyte indices, growth status, and muscle function occurred independent of hydroxyurea use.

Emerging drugs in randomized controlled trials for sickle cell disease: are we on the brink of a new era in research and treatment?

Introduction: Sickle cell disease (SCD) is caused by a mutation in the HBB gene which is key for making a component of hemoglobin. The mutation leads to the formation of an abnormal hemoglobin molecule called sickle hemoglobin (HbS). SCD is a chronic, complex disease with a multiplicity of pathophysiological targets; it has high morbidity and mortality.Hydroxyurea has for many years been the only approved drug for SCD; hence, the development of new therapeutics is critical.Areas covered: This article offers an overview of the key studies of new therapeutic options for SCD. We searched the PubMed database and Cochrane Database of Systemic Reviews for agents in early phase clinic trials and preclinical development.Expert opinion: Although knowledge of SCD has progressed, patient survival and quality of life must be improved. Phase II and phase III clinical trials investigating pathophysiology-based novel agents show promising results in the clinical management of SCD acute events. The design of long-term clinical studies is necessary to fully understand the clinical impact of these new therapeutics on the natural history of the disease. Furthermore, the building of global collaborations will enhance the clinical management of SCD and the design of primary outcomes of future clinical trials.

Bitopertin, a selective oral GLYT1 inhibitor, improves anemia in a mouse model of β-thalassemia

Anemia of β-thalassemia is caused by ineffective erythropoiesis and reduced red cell survival. Several lines of evidence indicate that iron/heme restriction is a potential therapeutic strategy for the disease. Glycine is a key initial substrate for heme and globin synthesis. We provide evidence that bitopertin, a glycine transport inhibitor administered orally, improves anemia, reduces hemolysis, diminishes ineffective erythropoiesis, and increases red cell survival in a mouse model of β-thalassemia (Hbbth3/+ mice). Bitopertin ameliorates erythroid oxidant damage, as indicated by a reduction in membrane-associated free α-globin chain aggregates, in reactive oxygen species cellular content, in membrane-bound hemichromes, and in heme-regulated inhibitor activation and eIF2α phosphorylation. The improvement of β-thalassemic ineffective erythropoiesis is associated with diminished mTOR activation and Rab5, Lamp1, and p62 accumulation, indicating an improved autophagy. Bitopertin also upregulates liver hepcidin and diminishes liver iron overload. The hematologic improvements achieved by bitopertin are blunted by the concomitant administration of the iron chelator deferiprone, suggesting that an excessive restriction of iron availability might negate the beneficial effects of bitopertin. These data provide important and clinically relevant insights into glycine restriction and reduced heme synthesis strategies for the treatment of β-thalassemia.

Emerging disease-modifying therapies for sickle cell disease

Sickle cell disease afflicts millions of people worldwide and approximately 100,000 Americans. Complications are myriad and arise as a result of complex pathological pathways ‘downstream’ to a point mutation in DNA, and include red blood cell membrane damage, inflammation, chronic hemolytic anemia with episodic vaso-occlusion, ischemia and pain, and ultimately risk of cumulative organ damage with reduced lifespan of affected individuals. The National Heart, Lung, and Blood Institute’s 2014 evidence-based guideline for sickle cell disease management states that additional research is needed before investigational curative therapies will be widely available to most patients with sickle cell disease. To date, sickle cell disease has been cured by hematopoietic stem cell transplantation in approximately 1,000 people, most of whom were children, and significantly ameliorated by gene therapy in a handful of subjects who have only limited follow-up thus far. During a timespan in which over 20 agents were approved for the treatment of cystic fibrosis by the Food and Drug Administration, similar approval was granted for only two drugs for sickle cell disease (hydroxyurea and L-glutamine) despite the higher prevalence of sickle cell disease. This trajectory appears to be changing, as the lack of multimodal agent therapy in sickle cell disease has spurred engagement among many in academia and industry who, in the last decade, have developed new drugs poised to prevent complications and alleviate suffering. Identified therapeutic strategies include fetal hemoglobin induction, inhibition of intracellular HbS polymerization, inhibition of oxidant stress and inflammation, and perturbation of the activation of the endothelium and other blood components (e.g. platelets, white blood cells, coagulation proteins) involved in the pathophysiology of sickle cell disease. In this article, we present a crash-course review of disease-modifying approaches (minus hematopoietic stem cell transplant and gene therapy) for patients with sickle cell disease currently, or recently, tested in clinical trials in the era following approval of hydroxyurea.

New and emerging treatments for vaso-occlusive pain in sickle cell disease

Introduction: Acute pain from episodic vaso-occlusion (VOC) spans the lifespan of almost everyone with sickle cell disease (SCD), while additional chronic pain develops in susceptible individuals in early adolescences. Frequent acute pain with chronic pain causes significant physical and psychological morbidity, and frequent health-care utilization. Available pharmacologic therapies reduce acute pain frequency but few evidence-based therapies are available for chronic pain. Areas covered: An extensive PubMed literature search was performed with appropriate search criteria. The pathophysiology of acute pain from VOC in SCD is very complex with many events subsequent to sickle polymer formation. Sensitization of pain pathways and alterations of brain networks contributes to the experience of chronic pain. Numerous therapies targeting putative VOC mechanisms are in clinical trials, and show considerable promise. Alternative analgesic treatments for acute and chronic pain have been examined in small patient cohorts, but formal clinical trials are lacking. Expert opinion: Childhood is likely a critical window for prevention of acute and later chronic pain. New multimodal analgesic therapies are needed, particularly for chronic pain, and should be examined in clinical trials. Given the multifactorial nature of both pain and VOC, simultaneously targeting multiple mechanisms may be the optimal approach for effective preventive therapies.

Relationship of Omega-3 fatty acids DHA and EPA with the inflammatory biomarker hs-CRP in children with sickle cell anemia

BACKGROUND

Inflammation and vaso-occlusion play key roles in Sickle Cell Disease (SCD) pathophysiology. Lipoxygenase products of the omega-3 fatty acids (O3FAs), docosahexaenoic (DHA) and eicosapentaenoic (EPA) acids, are potent anti-inflammatory mediators modulating pain. O3FAs decrease episodes of vaso-occlusion in SCD.

METHODS

We assessed erythrocyte fatty acid composition in two major cell membrane phospholipids, phosphatidylcholine and phosphatidylethanolamine, in children with SCD HbSS-disease (n = 38) and age/race-matched HbAA-controls (n = 18). Ratio of pro-inflammatory arachidonic acid (AA) to anti-inflammatory DHA and EPA (FA-Ratio), and its relationship to hs-CRP were evaluated.

RESULTS

FA-Ratios were increased in both phosphatidylcholine and phosphatidylethanolamine in HbSS compared to controls. Correlations were noted in HbSS subjects between hs-CRP and FA-Ratios (p = 0.011). FA-Ratios increased with age (p = 0.0007) due to an increase in pro-inflammatory AA with a concomitant decrease in anti-inflammatory DHA.

CONCLUSIONS

Findings demonstrate relative deficiencies in HbSS of the anti-inflammatory precursor fatty acids DHA and EPA, which correlates positively with hs-CRP.

Current challenges in the management of patients with sickle cell disease - A report of the Italian experience

Sickle cell disease (SCD) is an inherited red blood cell disorder caused by a structural abnormality of hemoglobin called sickle hemoglobin (HbS). Clinical manifestations of SCD are mainly characterized by chronic hemolysis and acute vaso-occlusive crisis, which are responsible for severe acute and chronic organ damage. SCD is widespread in sub-Saharan Africa, in the Middle East, Indian subcontinent, and some Mediterranean regions. With voluntary population migrations, people harboring the HbS gene have spread globally. In 2006, the World Health Organization recognized hemoglobinopathies, including SCD, as a global public health problem and urged national health systems worldwide to design and establish programs for the prevention and management of SCD. Herein we describe the historical experience of the network of hemoglobinopathy centers and their approach to SCD in Italy, a country where hemoglobinopathies have a high prevalence and where SCD, associated with different genotypes including ß-thalassemia, is present in the native population.

Double-blind, randomized, multicenter phase 2 study of SC411 in children with sickle cell disease (SCOT trial)

Blood cell membranes in sickle cell disease (SCD) have low docosahexaenoic acid (DHA). DHA treatment reduces sickle cell crisis (SCC) rate and ameliorates the inflammation, oxidative stress, and hypercoagulable state of SCD. SC411 is a novel DHA ethyl ester formulation with a proprietary delivery platform (Advanced Lipid Technology) that enhances DHA bioavailability. The SCOT trial investigated the effect of 3 different doses of SC411 on clinical and biochemical endpoints in 67 children with SCD (5-17 years old). Seventy-six percent of subjects were also receiving hydroxyurea. After 4 weeks of treatment with SC411 at 20, 36, and 60 mg DHA/kg per day or placebo a statistically significant (P < .001) mean percentage increase of blood cell membrane DHA and eicosapentaenoic acid was seen vs baseline: 109.0% (confidence interval [CI], 46.7-171.3), 163.8% (CI, 108.3-219.2), 170.8% (CI, 90.2-251.4), and 28.6% (CI, 250.1 to 107.3), respectively. After 8 weeks of treatment, statistically significant changes vs placebo were also observed in D-dimer (P = .025) and soluble E-selectin (P = .0219) in subjects exposed to 36 mg/kg. A significant increase in hemoglobin was observed against placebo in subjects receiving 20 mg DHA/kg per day (P = .039). SC411 significantly reduced electronic diary recorded SCC, analgesic use at home, and days absent from school because of sickle cell pain. The lower rate of clinical SCC observed in the pooled active groups vs placebo did not reach statistical significance (rate ratio, 0.47; 95% CI, 0.20-1.11; P = .07). All tested doses were safe and well tolerated. This trial was registered at www.clinicaltrials.gov as #NCT02973360.

Fish oil-based injectable lipid emulsions containing medium-chain triglycerides or added α-tocopherol offer anti-inflammatory benefits in a murine model of parenteral nutrition-induced liver injury

BACKGROUND

Fish oil (FO) intravenous lipid emulsions (ILEs) are used as a monotherapy to treat parenteral nutrition (PN)-associated liver disease and provide essential fatty acids (EFAs) needed to sustain growth and prevent EFA deficiency (EFAD). Studies have suggested that medium-chain triglycerides (MCTs) and α-tocopherol have anti-inflammatory properties.

OBJECTIVE

The purpose of this study was to test whether FO-ILEs containing MCTs and/or additional α-tocopherol decrease the inflammatory response to an endotoxin challenge compared with FO-ILE alone and preserve the ability to prevent PN-induced liver injury in mice.

METHODS

A murine model of PN-induced hepatosteatosis was used to compare the effects of ILEs formulated in the laboratory containing varying ratios of FO and MCTs, and subsequently FO- and 50:50 FO:MCT-ILE plus 500 mg/L α-tocopherol (FO + AT and 50:50 + AT, respectively). C57BL/6 mice receiving unpurified diet (UPD), PN-equivalent diet (PN) + saline, and PN + soybean oil (SO)-ILE served as controls. After 19 d, mice received an intraperitoneal saline or endotoxin challenge 4 h before being killed. Serum and livers were harvested for histologic analysis, fatty acid profiling, and measurement of systemic inflammatory markers (tumor necrosis factor-α, interleukin-6).

RESULTS

All ILEs were well tolerated and prevented biochemical EFAD. Livers of mice that received saline and SO developed steatosis. Mice that received 30:70 FO:MCT developed mild hepatosteatosis. All other FO-containing ILEs preserved normal hepatic architecture. Mice that received FO- or SO-ILE had significantly elevated systemic inflammatory markers after endotoxin challenge compared with UPD-fed controls, whereas 50:50 FO:MCT, 30:70 FO:MCT, FO + AT, and 50:50 + AT groups had significantly lower inflammatory markers similar to those seen in UPD-fed controls.

CONCLUSIONS

Mixed FO/MCT and the addition of α-tocopherol to FO improved the inflammatory response to endotoxin challenge compared with FO-ILE alone while still preventing PN-induced liver injury and EFAD in mice. There was no synergistic relation between α-tocopherol and MCTs.

Therapeutic strategies for sickle cell disease: towards a multi-agent approach

For over 100 years, clinicians and scientists have been unravelling the consequences of the A to T substitution in the β-globin gene that produces haemoglobin S, which leads to the systemic manifestations of sickle cell disease (SCD), including vaso-occlusion, anaemia, haemolysis, organ injury and pain. However, despite growing understanding of the mechanisms of haemoglobin S polymerization and its effects on red blood cells, only two therapies for SCD - hydroxyurea and L-glutamine - are approved by the US Food and Drug Administration. Moreover, these treatment options do not fully address the manifestations of SCD, which arise from a complex network of interdependent pathophysiological processes. In this article, we review efforts to develop new drugs targeting these processes, including agents that reactivate fetal haemoglobin, anti-sickling agents, anti-adhesion agents, modulators of ischaemia-reperfusion and oxidative stress, agents that counteract free haemoglobin and haem, anti-inflammatory agents, anti-thrombotic agents and anti-platelet agents. We also discuss gene therapy, which holds promise of a cure, although its widespread application is currently limited by technical challenges and the expense of treatment. We thus propose that developing systems-oriented multi-agent strategies on the basis of SCD pathophysiology is needed to improve the quality of life and survival of people with SCD.

Fyn kinase is a novel modulator of erythropoietin signaling and stress erythropoiesis

The signaling cascade induced by the interaction of erythropoietin (EPO) with its receptor (EPO-R) is a key event of erythropoiesis. We present here data indicating that Fyn, a Src-family-kinase, participates in the EPO signaling-pathway, since Fyn^-/- mice exhibit reduced Tyr-phosphorylation of EPO-R and decreased STAT5-activity. The importance of Fyn in erythropoiesis is also supported by the blunted responsiveness of Fyn^-/- mice to stress erythropoiesis. Fyn^-/- mouse erythroblasts adapt to reactive oxygen species (ROS) by activating the redox-related-transcription-factor Nrf2. However, since Fyn is a physiologic repressor of Nrf2, absence of Fyn resulted in persistent-activation of Nrf2 and accumulation of nonfunctional proteins. ROS-induced over-activation of Jak2-Akt-mTOR-pathway and repression of autophagy with perturbation of lysosomal-clearance were also noted. Treatment with Rapamycin, a mTOR-inhibitor and autophagy activator, ameliorates Fyn^-/- mouse baseline erythropoiesis and erythropoietic response to oxidative-stress. These findings identify a novel multimodal action of Fyn in the regulation of normal and stress erythropoiesis.

New Therapeutic Options for the Treatment of Sickle Cell Disease

Sickle cell disease (SCD; ORPHA232; OMIM # 603903) is a chronic and invalidating disorder distributed worldwide, with high morbidity and mortality. Given the disease complexity and the multiplicity of pathophysiological targets, development of new therapeutic options is critical, despite the positive effects of hydroxyurea (HU), for many years the only approved drug for SCD. New therapeutic strategies might be divided into (1) pathophysiology-related novel therapies and (2) innovations in curative therapeutic options such as hematopoietic stem cell transplantation and gene therapy. The pathophysiology related novel therapies are: a) Agents which reduce sickling or prevent sickle red cell dehydration; b) Agents targeting SCD vasculopathy and sickle cell-endothelial adhesive events; c) Anti-oxidant agents. This review highlights new therapeutic strategies in SCD and discusses future developments, research implications, and possible innovative clinical trials.

Advances in the Treatment of Sickle Cell Disease

Sickle cell disease (SCD) is a monogenic disorder that afflicts approximately 100,000 Americans and millions of people worldwide. It is characterized by hemolytic anemia, vaso-occlusive crises, relentless end-organ injury, and premature death. Currently, red blood cell transfusion and hydroxyurea are the major disease-modifying therapies available for SCD. Hematopoetic stem cell transplant is curative, but barriers to treatment are substantial and include a lack of suitable donors, immunologic transplant rejection, long-term adverse effects, prognostic uncertainty, and poor end-organ function, which is especially problematic for older patients. Gene therapy to correct the β^s point mutation is under investigation as another curative modality. Deeper insights into the pathophysiology of SCD have led to the development of novel agents that target cellular adhesion, inflammation, oxidant injury, platelets and/or coagulation, vascular tone, and hemoglobin polymerization. These agents are in preclinical and clinical trials. One such agent, L-glutamine, decreases red blood cell oxidant injury and is recently US Food and Drug Administration approved to prevent acute pain episodes of SCD in patients 5 years of age or older. The purpose of this review is to describe the currently established therapies, barriers to curative therapies, and novel therapeutic agents that can target sickle cell hemoglobin polymerization and/or its downstream sequelae. A PubMed search was conducted for articles published up to May 15, 2018, using the search terms sickle cell disease, novel treatments, hematopoietic stem cell transplantation, and gene therapy. Studies cited include case series, retrospective studies, prospective clinical trials, meta-analyses, online abstracts, and original reviews.

New insights into the pathophysiology and development of novel therapies for sickle cell disease

Although the seminal event in sickle cell disease is the polymerization of abnormal hemoglobin, the downstream pathophysiology of vasoocclusion results from heterotypic interactions between the altered, adhesive sickle cell red blood cells, neutrophils, endothelium, and platelets. Ischemia reperfusion injury, hemolysis, and oxidant damage all contribute to heightened inflammation and activation of the hemostatic system. These various pathways are the focus of emerging treatments with potential to ameliorate disease manifestations. This review summarizes the considerable progress in development of these agents despite challenges in selection of study end points and complex pathophysiology.

Resolution of sickle cell disease-associated inflammation and tissue damage with 17R-resolvin D1

Resolvins (Rvs), endogenous lipid mediators, play a key role in the resolution of inflammation. Sickle cell disease (SCD), a genetic disorder of hemoglobin, is characterized by inflammatory and vaso-occlusive pathologies. We document altered proresolving events following hypoxia/reperfusion in humanized SCD mice. We demonstrate novel protective actions of 17R-resolvin D1 (17R-RvD1; 7S, 8R, 17R-trihydroxy-4Z, 9E, 11E, 13Z, 15E, 19Z-docosahexaenoic acid) in reducing ex vivo human SCD blood leukocyte recruitment by microvascular endothelial cells and in vivo neutrophil adhesion and transmigration. In SCD mice exposed to hypoxia/reoxygenation, oral administration of 17R -RvD1 reduces systemic/local inflammation and vascular dysfunction in lung and kidney. The mechanism of action of 17R-RvD1 involves (1) enhancement of SCD erythrocytes and polymorphonuclear leukocyte efferocytosis, (2) blunting of NF-κB activation, and (3) a reduction in inflammatory cytokines, vascular activation markers, and E-selectin expression. Thus, 17R-RvD1 might represent a new therapeutic strategy for the inflammatory vasculopathy of SCD.

A Scientific Renaissance: Novel Drugs in Sickle Cell Disease

We have entered an era of exploding interest in therapeutics for sickle cell disease. The expansion in our understanding of sickle cell disease pathophysiology has enhanced the range of potential therapeutic targets. From induction of fetal hemoglobin to antiadhesion molecules, we are potentially on the cusp of making life-altering modifications for individuals with sickle cell disease. This disease population cannot afford to let the current momentum wane. Studies exploring combinations of therapies affecting multiple steps in the pathophysiology and exploring novel and clinically relevant outcomes are incumbent.

Novel Sickle Cell Disease Therapies: Targeting Pathways Downstream of Sickling

Sickle cell disease is an inherited hemoglobinopathy characterized by hemolytic anemia, frequent painful episodes, poor quality of life, end organ damage and a shortened lifespan. Although the seminal event is the polymerization of the abnormal hemoglobin, the downstream pathophysiology of vaso-occlusion results from heterotypic interactions between the altered, adhesive sickle cell RBCs, neutrophils, endothelium, and platelets. Ischemia reperfusion injury, hemolysis and oxidant damage all contribute to heightened inflammation and activation of the hemostatic system. These downstream targets are the focus of emerging treatments with considerable potential to ameliorate disease manifestations. This review summarizes the progress on development of these agents.

Sickle cell dehydration: Pathophysiology and therapeutic applications

Cell dehydration is a distinguishing characteristic of sickle cell disease and an important contributor to disease pathophysiology. Due to the unique dependence of Hb S polymerization on cellular Hb S concentration, cell dehydration promotes polymerization and sickling. In double heterozygosis for Hb S and C (SC disease) dehydration is the determining factor in disease pathophysiology. Three major ion transport pathways are involved in sickle cell dehydration: the K-Cl cotransport (KCC), the Gardos channel (KCNN4) and Psickle, the polymerization induced membrane permeability, most likely mediated by the mechano-sensitive ion channel PIEZO1. Each of these pathways exhibit unique characteristics in regulation by oxygen tension, intracellular and extracellular environment, and functional expression in reticulocytes and mature red cells. The unique dependence of K-Cl cotransport on intracellular Mg and the abnormal reduction of erythrocyte Mg content in SS and SC cells had led to clinical studies assessing the effect of oral Mg supplementation. Inhibition of Gardos channel by clotrimazole and senicapoc has led to Phase 1,2,3 trials in patients with sickle cell disease. While none of these studies has resulted in the approval of a novel therapy for SS disease, they have highlighted the key role played by these pathways in disease pathophysiology.

Peroxiredoxin-2: A Novel Regulator of Iron Homeostasis in Ineffective Erythropoiesis

AIMS

Iron overload (IO) is a life-threatening complication of chronic hemolytic disorders such as β-thalassemia. IO results in severe cellular oxidative damage, leading to organ failure. Peroxiredoxin-2 (Prx2), a typical 2-cysteine-(Cys)-peroxiredoxin, is an important component of the cytoprotective system, but its response to IO is still to be fully defined.

RESULTS

We studied the effects of IO on Prx2-knockout mice (Prx2^-/-). The absence of Prx2 enhanced toxicity due to IO on erythropoiesis. We found that IO failed to induce the typical hepcidin (Hamp) upregulation in Prx2^-/- mice due to its failure to activate the signal transducer and activator of transcription-3 (STAT3) with intact Jak2 signaling. In Prx2^-/- mice, the loss of Hamp response was also observed after administration of a single dose of oral iron. When lipopolysaccharide (LPS) was used to explore IL6-STAT3 activation in Prx2^-/- mice, STAT3 activation and Hamp upregulation were once again defective. Treatment with PEP-fusion-recombinant-Prx2 (PEP Prx2) significantly increased STAT3 activation with upregulation of Hamp expression in both IO- and LPS-exposed Prx2^-/- mice. We also confirmed the beneficial effects of PEP Prx2 on Hamp expression through STAT3 activation in β-thalassemic mice.

INNOVATION

We propose that Prx2 plays a key role in responding to cytotoxicity of IO, directly targeting STAT3-transcriptional factor in a Jak2-independent fashion and regulating Hamp in response to canonical stimuli.

CONCLUSION

Collectively, our data highlight a novel role of Prx2 in iron homeostasis. Prx2 is a key cytoprotector against IO that is induced either by iron supplementation or due to chronic hemolysis as in β-thalassemia. Prx2 is required to support STAT3 transcriptional activity and regulation of Hamp expression. Antioxid. Redox Signal. 28, 1-14.

Coagulation profile of Sudanese children with homozygous sickle cell disease and the effect of treatment with omega-3 fatty acid on the coagulation parameters

Background

It has been reported that patients with SCD do have an abnormal coagulation profile. Coagulopathy is thought to be one of the key factors that contribute to the vaso-occlusive crisis that characterises sickle cell disease (SCD). In this study, we investigated whether Sudanese sickle cell patients have an abnormal coagulation profile. In addition, the effect of treatment with either omega-3 fatty acids or hydroxyurea on coagulation profile was assessed.

Methods

Homozygous SCD patients untreated (n = 52), omega-3 treated (n = 44), hydroxyurea (HU) treated (n = 8) and healthy (HbAA) controls (n = 52) matched for age (4–20 years), gender and socioeconomic status were enrolled. Patients on omega-3 fatty acids, according to age, received one to four capsules containing 277.8 mg DHA and 39.0 mg eicosapentnoic. Patients on Hydroxyurea were in on dosage more than 20 mg/kg/day. The steady state levels of the coagulation parameters and the effect of the treatments with either HU or omega-3 fatty acids on markers of coagulation were investigated.

Results

Compared to the healthy controls, treated and untreated HbSS patients had lower hemoglobin, plasma Protein C, proteins S and higher white blood cell count (WBC), platelets count (PLTs) and plasma D-dimer levels,(p < 0.05). In comparison to untreated HbSS, treatment with neither omega-3 nor HU had effect on the WBC, plasma proteins C and S, (p > 0.05). HU treated group had a lower PLTs count compared to HbSS untreated group (p < 0.5). The prothrombin and activated partial thromboplastin times and international normalized ratio (INR) of untreated patients are significantly higher than n-3 treated, HU-treated patients and health controls, (p < 0.05). Patients treated with omega-3 had lowered D-dimer levels in comparison to HU-treated and untreated HbSS patients, (p < 0.001).

Conclusion

This study provides evidence that Sudanes patients have abnormal coagulation profile and treatment with either HU or omega-3 fatty acids might partially ameliorate SCD-associated chronic coagulopathic state.

Peroxiredoxin-2 plays a pivotal role as multimodal cytoprotector in the early phase of pulmonary hypertension

Pulmonary-artery-hypertension (PAH) is a life-threatening and highly invalidating chronic disorder. Chronic oxidation contributes to lung damage and disease progression. Peroxiredoxin-2 (Prx2) is a typical 2-cysteine (Cys) peroxiredoxin but its role on lung homeostasis is yet to be fully defined. Here, we showed that Prx2^-/- mice displayed chronic lung inflammatory disease associated with (i) abnormal pulmonary vascular dysfunction; and (ii) increased markers of extracellular-matrix remodeling. Hypoxia was used to induce PAH. We focused on the early phase PAH to dissect the role of Prx2 in generation of PAH. Hypoxic Prx2^-/-mice showed (i) amplified inflammatory response combined with cytokine storm; (ii) vascular activation and dysfunction; (iii) increased PDGF-B lung levels, as marker of extracellular-matrix deposition and remodeling; and (iv) ER stress with activation of UPR system and autophagy. Rescue experiments with in vivo the administration of fused-recombinant-PEP-Prx2 show a reduction in pulmonary inflammatory vasculopathy and in ER stress with down-regulation of autophagy. Thus, we propose Prx2 plays a pivotal role in the early stage of PAH as multimodal cytoprotector, targeting oxidation, inflammatory vasculopathy and ER stress with inhibition of autophagy. Collectively, our data indicate that Prx2 is able to interrupt the hypoxia induced vicious cycle involving oxidation-inflammation-autophagy in the pathogenesis of PAH.

Data demonstrating the role of peroxiredoxin 2 as important anti-oxidant system in lung homeostasis

The data presented in this article are related to the research paper entitled “peroxiredoxin-2 plays a pivotal role as multimodal cytoprotector in the early phase of pulmonary hypertension” (Federti et al., 2017) [1]. Data show that the absence of peroxiredoxin-2 (Prx2) is associated with increased lung oxidation and pulmonary vascular endothelial dysfunction. Prx2^−/− mice displayed activation of the redox-sensitive transcriptional factors, NF-kB and Nrf2, and increased expression of cytoprotective system such as heme-oxygenase-1 (HO-1). We also noted increased expression of both markers of vascular activation and extracellular matrix remodeling. The administration of the recombinant fusion protein PEP Prx2 reduced the activation of NF-kB and Nrf2 and was paralleled by a decrease in HO-1 and in vascular endothelial abnormal activation. Prolonged hypoxia was used to trigger pulmonary artery hypertension (PAH). Prx2^−/− precociously developed PAH compared to wildtype animals.

An Evolving Story of Translational Research: A Decade after the Jacobson Promising Investigator Award

THE THIRD JOAN L AND JULIUS H JACOBSON PROMISING INVESTIGATOR AWARDEE, MARK PUDER, MD, PHD, FACS: In 2005, the Surgical Research Committee (SRC) of the American College of Surgeons was tasked with selecting the recipient of a newly established award, "The Joan L and Julius H Jacobson Promising Investigator Award." According to the Jacobsons, the award, funded by Dr Jacobson, should be given at least once every 2 years to a surgeon investigator at "the tipping point," who can demonstrate that his or her research shows the promise of leading to a significant contribution to the practice of surgery and patient safety. Every year, the SRC receives many excellent nominations and has the difficult task of selecting 1 awardee. The first awardee was Michael Longaker, MD, FACS, who, 10 years later, reflected on the award and the impact it had on his career.¹ This year, Mark Puder, MD, PhD FACS, the third Jacobson awardee, reflects on his 10-year journey after receiving the award. Dr Puder is now a national and international figure in the field of intestinal failure-associated liver disease and has studied the effect of intravenous lipid emulsions on the etiology and treatment of a once fatal disease in children. Kamal MF Itani, MD, FACS and Brian S Zuckerbraun, MD, FACS, on behalf of the Research Committee of the American College of Surgeons.

Pathways to pulmonary hypertension in sickle cell disease: the search for prevention and early intervention

INTRODUCTION

Pulmonary hypertension (PH) develops in a significant number of patients with sickle cell disease (SCD), resulting in increased morbidity and mortality. This review focuses on PH pathophysiology, risk stratification, and new recommendations for screening and treatment for patients with SCD. Areas covered: An extensive PubMed literature search was performed. While the pathophysiology of PH in SCD is yet to be fully deciphered, it is known that the etiology is multifactorial; hemolysis, hypercoagulability, hypoxemia, ischemic-reperfusion injury, oxidative stress, and genetic susceptibility all contribute in varying degrees to endothelial dysfunction. Hemolysis, in particular, seems to play a key role by inciting an imbalance in the regulatory axis of nitric oxide and arginine metabolism. Systematic risk stratification starting in childhood based on clinical features and biomarkers that enable early detection is necessary. Multi-faceted, targeted interventions, before irreversible vasculopathy develops, will allow for improved patient outcomes and life expectancy. Expert commentary: Despite progress in our understanding of PH in SCD, clinically proven therapies remain elusive and additional controlled clinical trials are needed. Prevention of disease starts in childhood, a critical window for intervention. Given the complex and multifactorial nature of SCD, patients will ultimately benefit from combination therapies that simultaneously targets multiple mechanisms.