Abnormal Cytokine Production By Mast Cell Cultures from Sickle Cell Anemia Patients in Response to Inflammatory Stimuli and to Co-Culture with Eosinophils

Mast cell function (MC) in pathologic states can be studied through their ability to secrete mediators in vitro depending on MC phenotype and the nature of the stimuli. Reports on MC mediators in sickle cell anemia (SCA) patients are scarce, but clinical signs of MC activation syndrome, such as increased plasma histamine in vaso‐occlusive crisis (VOC), and normal or slightly elevated serum tryptase have been reported. However, assessing the biological relevance of MC as a cytokine source is more challenging because it is unclear under which circumstances they secrete those products in vivo, or if the cytokines measured systemically stem from a different cell type. We aimed to investigate the profile of mediators involved in the inflammatory process produced by MC in SCA. Methods:The supernatant of 5-week old MC cultures (17 SCA, 8 HV) obtained from peripheral blood CD34+ cells from 29 SCA patients and 13 healthy volunteers (HV) was analyzed using a multiplex platform and colorimetric assays for endothelin-1 (ET-1) and substance P (SP) (10 SCA, 6 HV). A correlation matrix (Pearson correlations, R software, v. 3.6.1) was generated using laboratory and clinical data chosen based on their value as inflammatory or prognosis markers (hydroxyurea [HU] treatment, fetal hemoglobin [HbF], hemoglobin [Hb], vaso-occlusive crisis [VOC], percentage of peripheral blood neutrophils, eosinophils (Eos), basophils, erythroblasts, and reticulocytes), MC surface expression of CD117, CD48 and CD63, and the supernatant content of 11 cytokines. To investigate MC cytokine release, we tested the supernatants from Eos-MC co-cultures (3:1 ratio), and after stimulation with ET-1 (20 nM), SP (10 µM) and imatinib (20 µg/ml)(n=3 per treatment). Results: Out of 26 cytokines, we found elevated levels of the following in the supernatants of SCA-MC cultures (data represented as mean in pg/ml±SE): TNFα: SCA=88.7±18.4, HV=32.6±3.8; IFNγ: SCA=55.3±11.2, HV=15.7±1.8; MCP1: SCA=555.0±147.2, HV=145.3±35.2; RANTES: SCA=24.7±3.9, HV=10.7±1.8 (p<0.05). However, SCA-MC from patients treated with HU (n = 11) showed higher values of IL-1b, IL-4, IL-5, IL-9, IL-15, and FGF than HV (n=8) and HU-free patients (n=6) (p<0.05). Supernatants from SCA-MC had higher ET-1 production compared to HV-MC (SCA=16.3±1.2, HV=11.93±1.3, pg/ml, p=0.02) but SP production was similar (SCA=27.9±1.3; HV=31.49±0.7 pg/ml). ET-1 stimulation of MC cultures caused 2-fold increase in IL-1AR production on HV-MC, but failed to produce any effect on SCA-MC. Similarly, imatinib reduced FGF only in HV-MC samples (HV: 15.1±3.5, HV-HU: 4.0±1.6, pg/ml). No effect on cytokine production was observed with SP. Conversely, Eos-MC cocultures showed a 10- and 4-fold increase of IL-5 and IL-9, respectively, regardless of the origin of Eos (HV or SCA). SCA-MC/SCA-Eos co-cultures had elevated proinflammatory (IL-1b, IL-12, TNF-α) and angiogenic (FGF, VEGF) cytokines, RANTES, IL-7, IL-4, and IL1-RA compared with SCA-MC/HV-Eos and HV-MC/HV-Eos (p<0.05). Preliminary multiparametric analysis on data from SCA patients showed a strong negative correlation between HU therapy and VGEF production, and between HbF levels and CD63 expression (MC activation marker).We also found a positive correlation between history of VOC and eotaxin-1 produced by SCA-MC. Conclusions: We found that MC responses depend both on the origin of the cultured cell and the stimuli utilized. Despite differences between in vitro and in vivo MC populations, our data show that cultured SCA-MC have a sustained activated state and produce a repertoire of mediators that could contribute to a perivascular microenvironment in favor of leukocyte and endothelium activation. In terms of cytokine production, cultured SCA-MC were more sensitive to stimulation by SCA-Eos than by HV-Eos, which may be relevant to the pathophysiology of airway inflammation in SCA patients with asthma. Differences in cytokine production between SCA-MC cultures from patients treated or not with HU may reflect the variability in adherence to treatment, individual response to each compound, or epigenetic modifications during the MC differentiation process that affect the phenotype of the mature MC. These results support that mediators produced by MC can contribute to the chronic inflammatory state and may be implicated in exacerbated responses to eosinophil activation in SCA. Disclosures Fertrin: Agios Pharmaceuticals, Inc.: Research Funding.

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Sickle Cell Anemia and Babesia Infection

Pathogens ◽

10.3390/pathogens10111435 ◽

2021 ◽

Vol 10 (11) ◽

pp. 1435

Author(s):

Divya Beri ◽

Manpreet Singh ◽

Marilis Rodriguez ◽

Karina Yazdanbakhsh ◽

Cheryl Ann Lobo

Keyword(s):

Sickle Cell ◽

Sickle Cell Anemia ◽

Current Knowledge ◽

Globin Gene ◽

Environmental Niche ◽

Parasite Resistance ◽

The Usa ◽

Human Infections

Babesia is an intraerythrocytic, obligate Apicomplexan parasite that has, in the last century, been implicated in human infections via zoonosis and is now widespread, especially in parts of the USA and Europe. It is naturally transmitted by the bite of a tick, but transfused blood from infected donors has also proven to be a major source of transmission. When infected, most humans are clinically asymptomatic, but the parasite can prove to be lethal when it infects immunocompromised individuals. Hemolysis and anemia are two common symptoms that accompany many infectious diseases, and this is particularly true of parasitic diseases that target red cells. Clinically, this becomes an acute problem for subjects who are prone to hemolysis and depend on frequent transfusions, like patients with sickle cell anemia or thalassemia. Little is known about Babesia’s pathogenesis in these hemoglobinopathies, and most parallels are drawn from its evolutionarily related Plasmodium parasite which shares the same environmental niche, the RBCs, in the human host. In vitro as well as in vivo Babesia-infected mouse sickle cell disease (SCD) models support the inhibition of intra-erythrocytic parasite proliferation, but mechanisms driving the protection of such hemoglobinopathies against infection are not fully studied. This review provides an overview of our current knowledge of Babesia infection and hemoglobinopathies, focusing on possible mechanisms behind this parasite resistance and the clinical repercussions faced by Babesia-infected human hosts harboring mutations in their globin gene.

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Abstract 15142: Endogenous Cardiac Stem Cells’ Activation in Response to Injury Potentiates Their Regenerative Ability

Circulation ◽

10.1161/circ.132.suppl_3.15142 ◽

2015 ◽

Vol 132 (suppl_3) ◽

Author(s):

Andrew J Smith ◽

Iolanda Aquila ◽

Beverley J Henning ◽

Mariangela Scalise ◽

Bernardo Nadal-Ginard ◽

...

Keyword(s):

Stem Cells ◽

Cardiac Injury ◽

Fold Increase ◽

Cardiac Stem Cells ◽

Post Injury ◽

Activated State ◽

Potential Benefits ◽

Therapeutic Avenue

The identification of resident, endogenous cardiac stem cells (eCSCs) has re-shaped our understanding of cardiac cellular physiology, while offering a significant potential therapeutic avenue. The biology of these cells must be better understood to harness their potential benefits. We used an acute dose (s.c.; 5mgkg-1) of isoproterenol (ISO) to induce diffuse cardiac injury, with associated eCSC activation, in rats. As peak eCSC activation was at 24 hours post ISO-injury, c-kitpos eCSCs were isolated, characterised and their potential for growth and regenerative potential was assessed in vitro and in vivo, respectively. Activated eCSCs showed increased cell cycling activity (51+1% in S- or G2/M phases vs. 9+2% of quiescent), Ki67 expression (56+7% vs. 10+1%) and TERT expression (14-fold increase vs. quiescent). When directly harvested in culture, activated eCSCs showed augmented proliferation, clonogenicity and cardiosphere formation compared to quiescent eCSCs. Activated eCSCs showed increases in expression of numerous growth factors, particularly HGF, IGF-1, TGF-β, periostin, PDGF-AA and VEGF-A. Furthermore, significant alterations were found in the miRnome, notably increased miR-146b and -221, and decreased miR-192 and -351. ISO+5FU was administrated to mice to induce a model of chronic dilated cardiomyopathy, which is characterized by the ablation of eCSCs and the absence of cardiomyocyte replenishment. In these mice with chronic heart failure, freshly isolated quiescent eCSCs or activated eCSCs (2d post-ISO) were injected through the tail vein. 28 days after injection, activated but not quiescent eCSCs re-populated the resident CSC pool, promoted robust new cardiomyocyte formation and improved cardiac function when compared to saline-treated mice. Dual-labelling with BrdU and EdU at selected stages after ISO injury determined that activated eCSCs returned to a quiescent level by 10 weeks post-injury. In conclusion, CSCs rapidly switch from a quiescent to an activated state to match the myocardial needs for myocyte replacement after injury and then spontaneously go back to quiescence. Harnessing the molecules regulating this process may open up future novel approaches for effective myocardial regeneration.

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In Vitro and In Vivo Antioxidant Effect of Fermented Papaya Preparation (FPP) on Blood Cells of Beta-Thalassaemia Patients.

Blood ◽

10.1182/blood.v108.11.1766.1766 ◽

2006 ◽

Vol 108 (11) ◽

pp. 1766-1766

Author(s):

Eitan Fibach ◽

Johnny Amer ◽

Ada Goldfarb ◽

Eliezer Rachmilewitz

Keyword(s):

Oxidative Stress ◽

Lipid Peroxidation ◽

Sickle Cell ◽

Sickle Cell Anemia ◽

Peripheral Blood ◽

Thalassemia Major ◽

Oxidative Status ◽

Beta Thalassemia ◽

Thalassemia Intermedia

Abstract In sickle cell anemia (SCD) and thalassemia, although the basic lesions are mutations in the globin genes, the pathophysiology involves oxidative stress-mediated cell damage in the bone marrow (ineffective erythropoiesis due to apoptosis of early erythroid precursors) and in the peripheral blood (chronic hemolysis of mature RBC). In addition, some patients develop thromboembolic complications and recurrent bacterial infections, the etiology of which is related at least in part, to documented oxidative stress in platelets and neutrophils (PMN), respectively. To study the presence and the role of oxidative stress in thalassemia and SCD, we adapted flow cytometry techniques for measuring the generation of Reactive Oxygen Species (ROS), the content of reduced glutathione (GSH), membrane lipid peroxidation and externalization of phosphatidylserine (PS) moieties in RBC, platelets and PMN. Cells derived from the peripheral blood of patients with beta-thalassemia major, intermedia or SCD showed increased oxidative status (increased ROS, lipid peroxidation and PS externalization, and decreased GSH) compared with their normal counterparts. Incubating fresh blood samples from patients with thalassemia major and thalassemia intermedia with 10 mg/ml FPP for 16 hours at 37oC reduced the oxidative status of RBC as well as platelets and PMN. Experiments carried out in normal and thalassemic mice (Th3/+, a mouse model of human beta-thalassemia intermedia demonstrated that mice treated for one week with 10 mg/ml FPP (dissolved in the drinking water) had reduced oxidative stress compared to control mice. The in-vivo effect of FPP was tested on 9 patients with beta-thalassemia (6 - major and 3 - intermedia) treated with 3 gr FPP per os three times a day for 12–15 weeks. Following the treatment, the ROS in RBC, platelets and PMN decreased and the GSH increased in all patients (see table). Six of these patients responded by a modest increase in RBC, reticulocytes and hemoglobin levels. These results suggest that FPP may have an important clinical efficacy as an antioxidant in thalassemia and sickle cell anemia. The in vivo effect of FPP treatment of beta-thalassemia patients Baseline After treatment n Mean ± SE Mean ± SE P-value* * Paired samples t-test RBC 9 324.07 ± 29.19 209.55 ± 23.65 0.001 ROS Platelets 9 223.73 ± 26.49 109.11 ± 8.71 0.001 PMN 9 222.72 ± 46.42 117.61 ± 8.98 0.045 RBC 9 55.37 ± 5.37 94.88 ± 3.71 0.001 GSH Platelets 9 59.41 ± 4.98 97.55 ± 5.26 <0.0001 PMN 9 58.29 ± 5.35 90.06 ± 5.87 0.005

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Altered Functional Properties of Eosinophils In Sickle Cell Anemia and Effects of Hydroxyurea Therapy

Blood ◽

10.1182/blood.v116.21.2656.2656 ◽

2010 ◽

Vol 116 (21) ◽

pp. 2656-2656

Author(s):

Flavia Rubia Pallis ◽

Nicola Conran ◽

Kleber Yotsumoto Fertrin ◽

Sara T. Olalla-Saad ◽

Fernando Ferreira Costa ◽

...

Keyword(s):

Functional Properties ◽

Sickle Cell ◽

Sickle Cell Anemia ◽

Peripheral Blood ◽

Plasma Levels ◽

Transgenic Animal ◽

Healthy Controls ◽

Eosinophil Peroxidase

Abstract Abstract 2656 The pathophysiology of sickle cell anemia (SCA) is now recognized to include a chronic inflammatory condition that contributes to the recurrent episodes of vaso-occlusion that characterize this disease. The vaso-occlusive process is a multi-step process that involves different cell types, such as red blood cells, reticulocytes, activated endothelial cells, platelets and leukocytes. In vivo transgenic animal studies indicated that the neutrophil appears to be the most important leukocyte in vaso-occlusion in previous transgenic animal in vivo studies; however, eosinophils (EOs) may also participate in this phenomenon in humans. EOs are found in significantly elevated numbers in sickle cell disease individuals and, in static adhesion assays, demonstrate augmented adhesive properties suggesting an activated state of these cells. However, the role of EOs in the pathophysiology of SCD and the effect of hydroxyurea (HU) therapy on the functional properties of these cells are not well understood. The aim of this study was to evaluate EO adhesion, migration and degranulation in SCA patients and the effect of HU therapy on these cells. EOs were purified from the peripheral blood of healthy controls (CON) (n≥10), steady-state SCA patients (n≥12) and SCA patients on HU therapy (n≥15), using Percoll gradient separation, followed by immunomagnetic sorting. EO adhesion was determined by static adhesion assays and degranulation was evaluated by measurement of eosinophil peroxidase activity. Migration of EOs was determined in 96-multiwell chemotaxis chamber assays. Plasma levels of Eotaxin-1, 2 and RANTES, important eosinophil attracting chemokines, were determined by ELISA. The absolute number of EOs in the peripheral blood of SCD patients not treated with HU was significantly higher compared to control individuals (0.504±0.09 vs 0.188±0.04; P=0.01, respectively). SCA patients taking HU presented significantly lower numbers of EOs (0.200±0.05, P = 0.01). Basal adhesion of EOs from SCA patients was significantly higher than in healthy controls (22.8±2.6 vs 13.7±1.7%, respectively, P = 0.004). Furthermore, the EOs from SCA patients on HU therapy demonstrated a significantly lower adhesion to fibronectin (12.5±2.0%, P=0.002). Spontaneous EO chemotaxis was significantly increased in SCA patients, compared to healthy controls (12.9±1.56 vs 6.97±0.8 × 105/ml, respectively, P=0.009). Interestingly, the chemotatic response of EOs isolated from SCA patients taking HU was also higher than that of control EOs (12.1± 1.9 × 105/ml). EO chemotaxis in response to RANTES, Eotaxin and IL5 was significantly augmented in all groups compared to spontaneous chemotaxis (RANTES: CON: 15.3± 2.3; SCA: 19.9±3.0; SCAHU: 25.0±4.7; Eotaxin: CON: 18.7±3.0; SCA: 24.5±4.2; SCAHU: 24.0±5.2; IL5: CON: 13.4±2.4; SCA: 18.8±3.0, SCAHU: 16.6±4.5, P<0.05). Baseline eosinophil peroxidase release was higher in SCA EOs, compared to CON EOs (0.4±0.04 vs 0.2±0.02, respectively, P=0.001), but patients on HU presented a lower EOs degranulation than SCA not on HU (0.19±0.03, P=0.003). Plasma levels of Eotaxin-1 and RANTES were significantly higher in SCA individuals, compared to CON individuals (124±7; 1057±125 vs 78±7; 540±50.2 pg/ml, P=0.0002; P=0.0009, respectively). HU therapy was not associated with any change in Eotaxin-1 and RANTES plasma levels (117.9±9.7; 1175±126.2 pg/ml, respectively). Eotaxin-2 plasma levels did not vary among groups (485±80.8, 450±34, 398±47.8 pg/ml for CON, SCA and SCAHU, respectively). EOs of patients with SCA demonstrate a higher capacity for spontaneous migration, stimulated migration and degranulation. Therapy with HU is associated with reduced adhesion and degranulation of EOs in these patients, but had no effect on the chemotactic ability of these cells or chemokine levels. The presence of relative eosinophilia along with altered functional properties in SCA patients warrants further investigation of the role of EOs in the vaso-occlusive process. In particular, complications associated with allergic reactions, such as acute thoracic syndrome and asthma in SCA children, in which EO adhesion and degranulation may be more important, should be studied. The characteristics of the effect of HU on EO also suggest that SCA events in which EO chemotaxis plays a role are likely to respond poorly to HU therapy, and should lead to the development of alternative therapeutic strategies. Disclosures: No relevant conflicts of interest to declare.

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Hydroxyurea Induces Hepcidin Expression In Monocytes In Sickle Cell Anemia Patients

Blood ◽

10.1182/blood.v116.21.2653.2653 ◽

2010 ◽

Vol 116 (21) ◽

pp. 2653-2653

Author(s):

Kleber Yotsumoto Fertrin ◽

Carolina Lanaro ◽

Carla Fernanda Franco-Penteado ◽

Dulcinéia Martins Albuquerque ◽

Mariana R. B. Mello ◽

...

Keyword(s):

Gene Expression ◽

Sickle Cell ◽

Iron Metabolism ◽

Sickle Cell Anemia ◽

Peripheral Blood ◽

Serum Iron ◽

Iron Status ◽

Blood Transfusions ◽

Hepcidin Expression

Abstract Abstract 2653 The antimicrobial peptide hormone hepcidin is a key regulator of iron metabolism. Although mainly produced in the liver, hepcidin is also known to be synthesized by monocytic-macrophagic cells. We have previously shown that hepcidin is overexpressed in mononuclear cells in patients with sickle cell anemia (SCA), but whether monocyte-derived hepcidin production is related to iron metabolism remains unknown. To gather further insight into the role of hepcidin in monocytes, we collected peripheral blood samples from adult SCA patients (n=54) and normal age- and race-matched controls (CTRL, n=13) for assessment of hematological parameters, biochemical markers of iron status (serum iron and transferrin saturation - TfSat), hemolysis (lactate dehydrogenase-LDH) and inflammation (C reactive protein - CRP), and separation of peripheral blood monocytes by Ficoll-Hypaque and Percoll gradients for gene expression analyses of genes involved in iron metabolism signaling (HAMP encoding hepcidin, and three genes belonging to different pathways known to influence hepcidin expression, STAT3, SMAD4 and TLR4). Plasma GDF-15 levels were also measured, as this protein has been shown to be a potent downregulator of hepcidin. SCA patients were further stratified according to the number of previous blood transfusions and to treatment with hydroxyurea (HU). All patients were in steady-state, had no history of iron chelation treatment and were not enrolled in a regular transfusion program. 18 patients were receiving HU and 15 from the non-HU group had received over 20 blood transfusions during their lifetime. As expected, SCA patients had elevated LDH levels, but no differences were found between control and SCA groups regarding serum iron, TfSat or CRP levels. Except for a higher red cell mean corpuscular volume, patients on HU did not differ significantly from patients not using HU. Plasma GDF-15 levels were higher in SCA patients (2146±506.4pg/mL) than in control individuals (228.5±21.0pg/mL, p<0.0001). Among the genes studied, HAMP expression was significantly increased in the SCA group as a whole compared to the CTRL group, but SCA patients on HU had higher levels of monocytic hepcidin expression when compared to the remaining individuals (CTRL 0.043±0.030, SCA on HU 1.240±0.426, remaining SCA 0.332±0.093, p=0.0196). There were no significant correlations between monocytic hepcidin expression and hemoglobin levels, hematocrit, leucocyte or reticulocyte counts, serum iron, LDH or CRP levels, TfSat or transfusion history. STAT3, SMAD4 and TLR4 gene expressions did not differ significantly, suggesting that a possible alternative cause for hepcidin upregulation unrelated to known mechanisms by IL-6, BMP6, LPS or GDF-15 could be an unexpected effect of hydroxyurea. To further investigate if HU was able to modulate hepcidin expression, we performed experiments with THP-1, a human monocytic lineage, since in vitro analysis would allow us to exclude the influence of circulating cytokines elevated in SCA patients. THP-1 cells were cultured in RPMI medium enriched with 10% fetal bovine serum at 37°C and 5% CO2 atmosphere, and were submitted to treatment with water as control, or HU dissolved in water in increasing concentrations (100μM, 400μM and 1600μM) for 6 hours (n≥4). Cell viability was not affected by treatment (>90% viable cells at all experiments), and HAMP gene expression was increased up to four times in the cell cultures exposed to HU (p=0.03), while STAT3 and SMAD4 expressions remained unchanged. We have shown that hepcidin expression is upregulated in monocytes in SCA patients, particularly in those receiving HU, and that HU is capable of inducing this expression in an in vitro model, independently from inflammatory cytokine-mediated stimulation. Our data suggest that, although liver-derived hepcidin has been shown to have a major role in iron metabolism, its monocyte-derived counterpart does not seem to be directly influenced by iron status and may have other functions. Some studies have demonstrated that hepcidin in other species has anti-inflammatory effects in vitro, and that patients with SCA on HU shift to a lower inflammatory status. Thus, monocytic hepcidin overexpression might be a response against the chronic inflammatory state in SCA, and HU treatment may enhance this response. This is the first description of monocyte-derived hepcidin in SCA and the influence of HU on its expression. Disclosures: No relevant conflicts of interest to declare.

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Influence of hydroxyurea on fetal hemoglobin production in vitro

Blood ◽

10.1182/blood.v70.6.1824.1824 ◽

1987 ◽

Vol 70 (6) ◽

pp. 1824-1829 ◽

Cited By ~ 14

Author(s):

BA Miller ◽

O Platt ◽

S Hope ◽

G Dover ◽

DG Nathan

Keyword(s):

Sickle Cell ◽

Peripheral Blood ◽

Fetal Hemoglobin ◽

Erythroid Cells ◽

Hemoglobin Content ◽

Hemoglobin F ◽

Hydroxyurea Treatment ◽

Hemoglobin Production

Abstract Cytotoxic drugs increase circulating fetal hemoglobin levels. We examined the mechanism by measuring the fetal hemoglobin produced per BFU-E-derived erythroblast following hydroxyurea treatment in vivo and in vitro. Treatment of four sickle cell patients increased the percentage of circulating F reticulocytes. The frequencies of bone marrow or peripheral blood BFU-E or CFU-E-derived colonies and their fetal hemoglobin content were unaffected. In all cases, the number of erythroid cells/progenitor-derived colony increased. To explore further the effect of hydroxyurea on fetal hemoglobin production, we added 50 mumol/L hydroxyurea to cultures of peripheral blood BFU-E-derived erythroblasts on 1 of 9 days (day 5 through 13) to nine samples. These BFU-E were derived from the peripheral blood of normal donors, sickle trait donors, and sickle cell anemia patients and from the bone marrows of monkeys. This concentration of hydroxyurea was selected so that the frequency of BFU-E and their size was moderately decreased. Addition of hydroxyurea to these progenitor-derived erythroid cells had no effect on fetal hemoglobin content per cell. Neither did transient exposure of progenitors to hydroxyurea prior to culture in nontoxic concentrations (0 to 500 mumol/L) result in a significant increase in fetal hemoglobin content in progenitor-derived erythroblasts. These data suggest that hydroxyurea does not directly alter the HbF program expressed by progenitor-derived erythroid cells. Instead, it enhances hemoglobin F content secondarily, possibly by inducing alterations in erythropoiesis.

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Sickling Cells, Cyclic Nucleotides, and Protein Kinases: The Pathophysiology of Urogenital Disorders in Sickle Cell Anemia

Anemia ◽

10.1155/2012/723520 ◽

2012 ◽

Vol 2012 ◽

pp. 1-13 ◽

Cited By ~ 4

Author(s):

Mário Angelo Claudino ◽

Kleber Yotsumoto Fertrin

Keyword(s):

Protein Kinases ◽

Sickle Cell ◽

Sickle Cell Anemia ◽

Cyclic Nucleotides ◽

Single Point ◽

Clinical Manifestations ◽

Single Point Mutation ◽

Tract Infections

Sickle cell anemia is one of the best studied inherited diseases, and despite being caused by a single point mutation in theHBBgene, multiple pleiotropic effects of the abnormal hemoglobin S production range from vaso-occlusive crisis, stroke, and pulmonary hypertension to osteonecrosis and leg ulcers. Urogenital function is not spared, and although priapism is most frequently remembered, other related clinical manifestations have been described, such as nocturia, enuresis, increased frequence of lower urinary tract infections, urinary incontinence, hypogonadism, and testicular infarction. Studies on sickle cell vaso-occlusion and priapism using bothin vitroandin vivomodels have shed light on the pathogenesis of some of these events. The authors review what is known about the deleterious effects of sickling on the genitourinary tract and how the role of cyclic nucleotides signaling and protein kinases may help understand the pathophysiology underlying these manifestations and develop novel therapies in the setting of urogenital disorders in sickle cell disease.

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ELKS1 controls mast cell degranulation by regulating the transcription of Stxbp2 and Syntaxin 4 via Kdm2b stabilization

Science Advances ◽

10.1126/sciadv.abb2497 ◽

2020 ◽

Vol 6 (31) ◽

pp. eabb2497

Author(s):

Hiu Yan Lam ◽

Surendar Arumugam ◽

Han Gyu Bae ◽

Cheng Chun Wang ◽

Sangyong Jung ◽

...

Keyword(s):

Mast Cell ◽

Cytokine Production ◽

Nuclear Factor Κb ◽

Mast Cell Degranulation ◽

Nuclear Factor ◽

Regulated Exocytosis ◽

Lysine Specific Demethylase ◽

Syntaxin 4

ELKS1 is a protein with proposed roles in regulated exocytosis in neurons and nuclear factor κB (NF-κB) signaling in cancer cells. However, how these two potential roles come together under physiological settings remain unknown. Since both regulated exocytosis and NF-κB signaling are determinants of mast cell (MC) functions, we generated mice lacking ELKS1 in connective tissue MCs (Elks1f/f Mcpt5-Cre) and found that while ELKS1 is dispensable for NF-κB–mediated cytokine production, it is essential for MC degranulation both in vivo and in vitro. Impaired degranulation was caused by reduced transcription of Syntaxin 4 (STX4) and Syntaxin binding protein 2 (Stxpb2), resulting from a lack of ELKS1-mediated stabilization of lysine-specific demethylase 2B (Kdm2b), which is an essential regulator of STX4 and Stxbp2 transcription. These results suggest a transcriptional role for active-zone proteins like ELKS1 and suggest that they may regulate exocytosis through a novel mechanism involving transcription of key exocytosis proteins.

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Influence of hydroxyurea on fetal hemoglobin production in vitro

Blood ◽

10.1182/blood.v70.6.1824.bloodjournal7061824 ◽

1987 ◽

Vol 70 (6) ◽

pp. 1824-1829 ◽

Cited By ~ 1

Author(s):

BA Miller ◽

O Platt ◽

S Hope ◽

G Dover ◽

DG Nathan

Keyword(s):

Sickle Cell ◽

Peripheral Blood ◽

Fetal Hemoglobin ◽

Erythroid Cells ◽

Hemoglobin Content ◽

Hemoglobin F ◽

Hydroxyurea Treatment ◽

Hemoglobin Production

Cytotoxic drugs increase circulating fetal hemoglobin levels. We examined the mechanism by measuring the fetal hemoglobin produced per BFU-E-derived erythroblast following hydroxyurea treatment in vivo and in vitro. Treatment of four sickle cell patients increased the percentage of circulating F reticulocytes. The frequencies of bone marrow or peripheral blood BFU-E or CFU-E-derived colonies and their fetal hemoglobin content were unaffected. In all cases, the number of erythroid cells/progenitor-derived colony increased. To explore further the effect of hydroxyurea on fetal hemoglobin production, we added 50 mumol/L hydroxyurea to cultures of peripheral blood BFU-E-derived erythroblasts on 1 of 9 days (day 5 through 13) to nine samples. These BFU-E were derived from the peripheral blood of normal donors, sickle trait donors, and sickle cell anemia patients and from the bone marrows of monkeys. This concentration of hydroxyurea was selected so that the frequency of BFU-E and their size was moderately decreased. Addition of hydroxyurea to these progenitor-derived erythroid cells had no effect on fetal hemoglobin content per cell. Neither did transient exposure of progenitors to hydroxyurea prior to culture in nontoxic concentrations (0 to 500 mumol/L) result in a significant increase in fetal hemoglobin content in progenitor-derived erythroblasts. These data suggest that hydroxyurea does not directly alter the HbF program expressed by progenitor-derived erythroid cells. Instead, it enhances hemoglobin F content secondarily, possibly by inducing alterations in erythropoiesis.

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Metabolomic Characterization of Red Blood Cell Differentiation

Blood ◽

10.1182/blood-2020-137175 ◽

2020 ◽

Vol 136 (Supplement 1) ◽

pp. 35-35

Author(s):

Kelsey Temprine ◽

Amanda Sankar ◽

Costas Lyssiotis ◽

Yatrik Shah

Keyword(s):

Amino Acid ◽

Sickle Cell ◽

Sickle Cell Anemia ◽

Sodium Butyrate ◽

Global Changes ◽

Ineffective Erythropoiesis ◽

Irreversible Loss ◽

In Vivo Models

Background: Erythropoiesis is the highly coordinated multi-step process by which multipotent hematopoietic stem cells differentiate into mature enucleated red blood cells (RBCs). As erythroid cells become more terminally differentiated, they undergo changes in morphology and gene expression, start synthesizing hemoglobin, commit to an irreversible loss of proliferation, and eventually expulse their nuclei and other cytoplasmic organelles. Thus, RBCs must rely on their proteome and metabolome for proper function. The RBC proteome is estimated to contain 2,800 proteins, including a variety of receptors and transporters that allow RBCs to uptake xenobiotics or endogenous metabolites as they circulate for ∼120 days. Furthermore, they are metabolically active with glycolysis, nucleotide catabolism, and glutathione metabolism as the major pathways supporting cell survival and function. However, it is unclear how the metabolome is altered during erythropoiesis, what role metabolites play in normal erythropoiesis, and if dysregulation of metabolites contributes to diseases of ineffective erythropoiesis, such as sickle cell anemia and thalassemia. Methods: Four models of erythropoiesis were used in this study. 1) Mice were treated with phenylhydrazine (Phz) to induce acute hemolysis followed by erythropoietic recovery, leading to an increase in circulating reticulocytes. 2) Mice were lethally irradiated and transplanted with wild-type or sickle cell bone marrow, leading to anemic profiles in sickle cell chimeras. 3) The mouse erythroleukemic (MEL) cell line was treated with DMSO to induce differentiation. 4) The human erythroleukemic (K562) cell line was treated with sodium butyrate to induce differentiation. For the in vivo mouse models, blood was collected from control and treated animals, and complete blood count (CBC) analysis was performed. For the in vitro cell culture models, the mRNA levels of β-globin were measured by Q-RT-PCR in control and differentiated cells, and the degree of hemoglobinization was determined visually and via staining for heme. In addition, metabolites were extracted from the collected RBCs and erythroleukemic cell lines, and a Snapshot LC/MS metabolomic platform was used to identify commonly altered metabolites. Results: We first validated our four models of erythropoiesis. Treatment with Phz decreased the number of total RBCs while increasing the RBC distribution width, indicating an increased number of reticulocytes (more immature RBCs) in circulation. Similar results were seen in the sickle cell chimeras. Treatment of MEL and K562 cells with DMSO and sodium butyrate, respectively, resulted in increased expression of β-globin, increased levels of heme, and increased red color. Then, using our Snapshot metabolomic platform, we identified global changes in RBC metabolism during erythropoiesis. Analyses of the commonly altered metabolites in the in vitro and in vivo models revealed an increase in amino acid, mitochondrial, and urea cycle metabolism during erythropoiesis. L-aspartate levels were particularly upregulated, especially in DMSO-treated MEL cells. We are now investigating the role of aspartate in the regulation of erythropoiesis. Conclusions: We defined how the metabolome was altered in multiple in vitro and in vivo models of erythropoiesis and identified global changes in RBC metabolism between the different models. Specifically, we found that L-aspartate was upregulated during RBC differentiation in all four models. Aspartate is an amino acid that plays a role in many processes in cells, including nucleotide biosynthesis, redox homeostasis, and amino acid biosynthesis. We hypothesize that aspartate metabolism is critical for RBC differentiation and that its dysregulation exacerbates disease of ineffective erythropoiesis, such as sickle cell anemia and β-thalassemia. We are currently testing its role in inducing hemoglobinization and in regulating the commitment of erythroid progenitor cells to an irreversible loss of proliferation. Overall, we believe that understanding the precise mechanisms by which cellular metabolism plays a role in proper RBC differentiation may lead to better therapies for diseases of ineffective erythropoiesis, such as sickle cell anemia and thalassemia. Disclosures No relevant conflicts of interest to declare.

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