Pregnancy Complications In Sickle Cell Disease Are More Prevalent In Women with Vaso-Occlusion Related Organ Damage Than Hemolysis Related Organ Damage

Blood ◽  
2010 ◽  
Vol 116 (21) ◽  
pp. 2661-2661
Author(s):  
Charlotte F.J. van Tuijn ◽  
Roosmarijn G. van der Stap ◽  
Joris A.M. van der Post ◽  
Marjolein Peters ◽  
Bart J. Biemond
Keyword(s):  
Birth Weight ◽  
Sickle Cell Disease ◽  
Sickle Cell ◽  
Pregnancy Complications ◽  
Organ Damage ◽  
Pregnancy Complication ◽  
Cell Disease ◽  
Genotype Group ◽  
Lower Birth Weight ◽  
Platelet Counts

Abstract Abstract 2661 Background: Patients with sickle cell disease (SCD) develop accumulating organ damage throughout their lives as result of chronic hemolytic anemia and ongoing microvascular vaso-occlusion. Chronic organ damage has been related to significant morbidity and increased mortality. Previous studies have shown significant increased foetal and maternal complications in patients with SCD. It is unclear whether the presence of chronic organ damage is related to pregnancy complications in these patients. Therefore, we determined the relation between chronic organ damage and pregnancy complications in women with SCD. Methods: We performed a retrospective analysis of pregnancy complications in all women known with SCD (defined as HbSS, HbS-β°, HbSC and HbSβ+) in a teaching hospital in the Netherlands. Pregnancy complications consisted of: hypertension, (pre)eclampsia, still birth, preterm birth, dysmaturity, urinary tract infection, perinatal mortality, maternal mortality, painful crisis and acute chest syndrome (ACS). In all patients vaso-occlusion related organ damage (pain rate >1 crises/year, ACS, avascular osteonecrosis and retinopathy) as well as hemolysis related organ damage (microalbuminuria, renal failure, pulmonary hypertension, chronic leg ulcers, stroke and cholelithiasis) was assessed. The patients were divided in a severe (HbSS/HbSβ°) and a mild genotype group (HbSC/HbSβ+). Chronic organ damage and the history of previous sickle cell-related complications were related to pregnancy complications, birth weight and laboratory tests. We adjusted for multiple pregnancies with the generalized estimated equations (GEE) model. Results: All 97 female patients known with SCD in our hospital were systematically evaluated for organ damage and sickle cell related complications. Thirty-six patients had not been pregnant at time of evaluation, medical information about their pregnancy was missing for 7 women and 6 women were only known with an elective abortion. Fifty-five pregnancies in 48 women with SCD (18 HbSS, 4 HbSβ0, 21 HbSC and 5 HbSβ+) were evaluated for pregnancy complications. Hemolysis related organ damage was present in 17/22 (77%) of the patients with a severe genotype and 7/32 (22%) patients with a mild genotype (p<0.001). Patients with vaso-occlusion related organ damage had more pregnancy related complications 26/32 (81%) compared to patients without vaso-occlusive related organ damage 10/19, (53%) (p=0.033). No relation between hemolysis related organ damage and pregnancy complications was found. In the severe genotype group more pregnancy complications were observed and children of patients with the severe genotype had a lower birth weight (2603±721) as compared to the milder group (2866±811) but these differences did not reach significance. Lower birth weight correlated with lower hemoglobin concentration (Hb) (r=0,326; p=0.08), leukocyte count (r=−0.438; p=0.005) and platelet counts (r=-0.368; p<0.001). With respect to laboratory test, patients with pregnancy complications had lower hemoglobin levels (p=0.031), higher leukocyte counts (p=0.006) and a lower LDH (p=0.049) in comparison to patients without any pregnancy complication. Conclusions: The majority of patients with SCD had at least one pregnancy complication. Pregnancy related complications were more frequently observed in patients with organ complications related to vaso-occlusion than patients with mainly hemolysis related complications. Furthermore, pregnancy related complications were more frequently observed in the severe genotype group with a trend to a lower birth weight and appeared to be related with lower Hb concentration, higher leukocyte and higher platelet counts. Disclosures: No relevant conflicts of interest to declare.

Impaired Fibrinolysis in Sickle Cell Disease

1970 ◽  
Vol 24 (01/02) ◽  
pp. 010-016 ◽  
Author(s):  
D Green ◽  
H. C Kwaan ◽  
G Ruiz
Keyword(s):  
Sickle Cell Disease ◽  
Factor Viii ◽  
Plasminogen Activator ◽  
Sickle Cell ◽  
Fibrinolytic Activity ◽  
Endothelial Damage ◽  
Cell Disease ◽  
Clotting Factors ◽  
Platelet Counts

SummaryCoagulation studies were performed in 52 patients with sickle cell disease during asymptomatic periods and during episodes of crisis and infection. Platelet counts averaged 473,000, 469,000, and 461,000 per mm3 in these 3 groups, and factor VIII concentrations were elevated in all. Fibrinogen was increased to the same extent in both sickle cell and non-sickle cell patients with infection. Fibrinolytic activity, as measured by euglobulin lysis times and zones of lysis on fibrin plates, was markedly reduced during periods of infection in sickle cell patients but not in non-sickle patients. Impairment of fibrinolysis in most patients was not on the basis of overutilization or consumption, since no decrease in the levels of clotting factors or plasminogen was observed. It was suggested that generalized intravascular sickling in these patients may have caused widespread endothelial damage, resulting in decreased production of plasminogen activator.In addition, several sickle cell patients with infection were found to possess elevated levels of an inhibitor directed against urokinase.

scholarly journals Sickle Cell Disease: Role of Oxidative Stress and Antioxidant Therapy

Antioxidants ◽  
2021 ◽  
Vol 10 (2) ◽  
pp. 296
Author(s):  
Rosa Vona ◽  
Nadia Maria Sposi ◽  
Lorenza Mattia ◽  
Lucrezia Gambardella ◽  
Elisabetta Straface ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Sickle Cell Disease ◽  
Sickle Cell ◽  
Globin Gene ◽  
Organ Damage ◽  
Cell Disease ◽  
Vessel Occlusion ◽  
Antioxidant Agents ◽  
Oxidant Status

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.

scholarly journals Targeting pain at its source in sickle cell disease

2018 ◽  
Vol 315 (1) ◽  
pp. R104-R112 ◽  
Author(s):  
Kanika Gupta ◽  
Om Jahagirdar ◽  
Kalpna Gupta
Keyword(s):  
Sickle Cell Disease ◽  
Sickle Cell ◽  
Cell Activation ◽  
Molecular Mechanisms ◽  
Genetic Disorder ◽  
Somatosensory System ◽  
Organ Damage ◽  
Mast Cell Activation ◽  
Cell Disease ◽  
Central Nervous Systems

Sickle cell disease (SCD) is a genetic disorder associated with hemolytic anemia, end-organ damage, reduced survival, and pain. One of the unique features of SCD is recurrent and unpredictable episodes of acute pain due to vasoocclusive crisis requiring hospitalization. Additionally, patients with SCD often develop chronic persistent pain. Currently, sickle cell pain is treated with opioids, an approach limited by adverse effects. Because pain can start at infancy and continue throughout life, preventing the genesis of pain may be relatively better than treating the pain once it has been evoked. Therefore, we provide insights into the cellular and molecular mechanisms of sickle cell pain that contribute to the activation of the somatosensory system in the peripheral and central nervous systems. These mechanisms include mast cell activation and neurogenic inflammation, peripheral nociceptor sensitization, maladaptation of spinal signals, central sensitization, and modulation of neural circuits in the brain. In this review, we describe potential preventive/therapeutic targets and their targeting with novel pharmacologic and/or integrative approaches to ameliorate sickle cell pain.

scholarly journals The gut microbiome in sickle cell disease: Characterization and potential implications

PLoS ONE ◽  
2021 ◽  
Vol 16 (8) ◽  
pp. e0255956
Author(s):  
Hassan Brim ◽  
James Taylor ◽  
Muneer Abbas ◽  
Kimberly Vilmenay ◽  
Mohammad Daremipouran ◽  
...  
Keyword(s):  
Sickle Cell Disease ◽  
Sickle Cell ◽  
Gut Microbiome ◽  
Tissue Injury ◽  
Organ Damage ◽  
Composition Analysis ◽  
Cell Disease ◽  
Blood Disorder ◽  
Major Player ◽  
Next Generation Sequencing Ngs

Background Sickle Cell Disease (SCD) is an inherited blood disorder that leads to hemolytic anemia, pain, organ damage and early mortality. It is characterized by polymerized deoxygenated hemoglobin, rigid sickle red blood cells and vaso-occlusive crises (VOC). Recurrent hypoxia-reperfusion injury in the gut of SCD patients could increase tissue injury, permeability, and bacterial translocation. In this context, the gut microbiome, a major player in health and disease, might have significant impact. This study sought to characterize the gut microbiome in SCD. Methods Stool and saliva samples were collected from healthy controls (n = 14) and SCD subjects (n = 14). Stool samples were also collected from humanized SCD murine models including Berk, Townes and corresponding control mice. Amplified 16S rDNA was used for bacterial composition analysis using Next Generation Sequencing (NGS). Pairwise group analyses established differential bacterial groups at many taxonomy levels. Bacterial group abundance and differentials were established using DeSeq software. Results A major dysbiosis was observed in SCD patients. The Firmicutes/Bacteroidetes ratio was lower in these patients. The following bacterial families were more abundant in SCD patients: Acetobacteraceae, Acidaminococcaceae, Candidatus Saccharibacteria, Peptostreptococcaceae, Bifidobacteriaceae, Veillonellaceae, Actinomycetaceae, Clostridiales, Bacteroidacbactereae and Fusobacteriaceae. This dysbiosis translated into 420 different operational taxonomic units (OTUs). Townes SCD mice also displayed gut microbiome dysbiosis as seen in human SCD. Conclusion A major dysbiosis was observed in SCD patients for bacteria that are known strong pro-inflammatory triggers. The Townes mouse showed dysbiosis as well and might serve as a good model to study gut microbiome modulation and its impact on SCD pathophysiology.

scholarly journals Sickle Cell Disease Model Mice Lacking 2,3-Dpg Show Reduced RBC Sickling and Improvements in Markers of Hemolytic Anemia

Blood ◽  
2020 ◽  
Vol 136 (Supplement 1) ◽  
pp. 27-28
Author(s):  
Kelly M. Knee ◽  
Amey Barakat ◽  
Lindsay Tomlinson ◽  
Lila Ramaiah ◽  
Zane Wenzel ◽  
...  
Keyword(s):  
Sickle Cell Disease ◽  
Blood Cell ◽  
Hemolytic Anemia ◽  
Sickle Cell ◽  
Red Blood Cell ◽  
Organ Damage ◽  
Complete Elimination ◽  
Cell Disease ◽  
The Impact ◽  
2,3 Dpg

Sickle cell disease (SCD) is a severe genetic disorder caused by a mutation in hemoglobin (b6Glu-Val), which allows the mutant hemoglobin to assemble into long polymers when deoxygenated. Over time, these polymers build up and deform red blood cells, leading to hemolytic anemia, vaso-occlusion, and end organ damage. A number of recent therapies for SCD have focused on modulating the mutant hemoglobin directly, however, reduction or elimination of 2,3-DPG to reduce Hb S polymerization and RBC sickling has recently been proposed as a therapeutic strategy for SCD. Current clinical studies focus on activation of pyruvate kinase to reduce 2,3-DPG, however, direct targeting of the enzyme which produces 2,3-DPG; Bisphosphoglycerate Mutase (BPGM) may also be possible. In this study we evaluate the impact of elimination of 2,3-DPG on SCD pathology by complete knockout of BPGM in Townes model mice. Animals with complete knockout of BPGM (BPGM -/-) have no detectable 2,3-DPG, while animals that are heterozygous for BPGM (BPGM -/+) have 2,3-DPG levels comparable to Townes mice. Western Blot analysis confirms that BPGM -/- animals completely lack BPGM, while BPGM -/+ animals have BPGM levels that are nearly equivalent to Townes mice. As expected from the lack of 2,3-DPG, BPGM -/- animals have increased oxygen affinity, observed as a 39% decrease in p50 relative to Townes mice. Complete elimination of 2,3-DPG has significant effects on markers of hemolytic anemia in BPGM -/- mice. Mice lacking 2,3-DPG have a 60% increase in hemoglobin (3.7 g/dL), a 53% increase in red blood cell count, and a 29% increase in hematocrit relative to Townes mice. The BPGM -/- mice also have a 57% decrease in reticulocytes, and a 61% decrease in spleen weight relative to Townes animals, consistent with decreased extramedullary hematopoiesis. Consistent with the reduction in hemolysis, BPGM -/- animals had a 59% reduction in red blood cell sickling under robust hypoxic conditions. BPGM -/+ animals had hemoglobin, RBC, and hematocrit levels that were similar to Townes animals, and a similar degree of RBC sickling to Townes mice. Liver phenotype was similar across all variants, with areas of random necrosis observed in BPGM -/-, BPGM -/+ and Townes mice. Higher percentages of microcytic and/or hyperchromic RBCs were observed in BPGM -/- animals relative to BPGM -/+ or Townes animals. These results suggest that modulation of 2,3-DPG has a positive effect on RBC sickling and hemolytic anemia, which may have therapeutic benefits for SCD patients. However, the lack of improvement in organ damage suggests that modulation of 2,3-DPG alone may not be sufficient for complete elimination of SCD phenotypes, and further investigation of this therapeutic avenue may be necessary. Disclosures No relevant conflicts of interest to declare.

scholarly journals Potential role of LSD1 inhibitors in the treatment of sickle cell disease: a review of preclinical animal model data

2018 ◽  
Vol 315 (4) ◽  
pp. R840-R847 ◽  
Author(s):  
Angela Rivers ◽  
Ramasamy Jagadeeswaran ◽  
Donald Lavelle
Keyword(s):  
Reactive Oxygen Species ◽  
Sickle Cell Disease ◽  
Sickle Cell ◽  
Globin Gene ◽  
Reactive Oxygen ◽  
Organ Damage ◽  
The United States ◽  
Oxygen Species ◽  
Cell Disease ◽  
Hematopoietic Stem

Sickle cell disease (SCD) is caused by a mutation of the β-globin gene (Ingram VM. Nature 180: 326–328, 1957), which triggers the polymerization of deoxygenated sickle hemoglobin (HbS). Approximately 100,000 SCD patients in the United States and millions worldwide (Piel FB, et al. PLoS Med 10: e1001484, 2013) suffer from chronic hemolytic anemia, painful crises, multisystem organ damage, and reduced life expectancy (Rees DC, et al. Lancet 376: 2018–2031, 2010; Serjeant GR. Cold Spring Harb Perspect Med 3: a011783, 2013). Hematopoietic stem cell transplantation can be curative, but the majority of patients do not have a suitable donor (Talano JA, Cairo MS. Eur J Haematol 94: 391–399, 2015). Advanced gene-editing technologies also offer the possibility of a cure (Goodman MA, Malik P. Ther Adv Hematol 7: 302–315, 2016; Lettre G, Bauer DE. Lancet 387: 2554–2564, 2016), but the likelihood that these strategies can be mobilized to treat the large numbers of patients residing in developing countries is remote. A pharmacological treatment to increase fetal hemoglobin (HbF) as a therapy for SCD has been a long-sought goal, because increased levels of HbF (α2γ2) inhibit the polymerization of HbS (Poillin WN, et al. Proc Natl Acad Sci USA 90: 5039–5043, 1993; Sunshine HR, et al. J Mol Biol 133: 435–467, 1979) and are associated with reduced symptoms and increased lifespan of SCD patients (Platt OS, et al. N Engl J Med 330: 1639–1644, 1994; Platt OS, et al. N Engl J Med 325: 11–16, 1991). Only two drugs, hydroxyurea and l-glutamine, are approved by the US Food and Drug Administration for treatment of SCD. Hydroxyurea is ineffective at HbF induction in ~50% of patients (Charache S, et al. N Engl J Med 332: 1317–1322, 1995). While polymerization of HbS has been traditionally considered the driving force in the hemolysis of SCD, the excessive reactive oxygen species generated from red blood cells, with further amplification by intravascular hemolysis, also are a major contributor to SCD pathology. This review highlights a new class of drugs, lysine-specific demethylase (LSD1) inhibitors, that induce HbF and reduce reactive oxygen species.

scholarly journals Current and novel therapies for the prevention of vaso-occlusive crisis in sickle cell disease

2020 ◽  
Vol 11 ◽  
pp. 204062072095500
Author(s):  
Ifeyinwa Osunkwo ◽  
Deepa Manwani ◽  
Julie Kanter
Keyword(s):  
Sickle Cell Disease ◽  
Sickle Cell ◽  
Severe Pain ◽  
Management Strategies ◽  
Organ Damage ◽  
Care Utilization ◽  
Cell Disease ◽  
High Resource ◽  
Emerging Treatments

Individuals with sickle cell disease (SCD) are living further into adulthood in high-resource countries. However, despite increased quantity of life, recurrent, acute painful episodes cause significant morbidity for affected individuals. These SCD-related painful episodes, also referred to as vaso-occlusive crises (VOCs), have multifactorial causes, and they often occur as a result of multicellular aggregation and vascular adherence of red blood cells, neutrophils, and platelets, leading to recurrent and unpredictable occlusion of the microcirculation. In addition to severe pain, long-term complications of vaso-occlusion may include damage to muscle and/or bone, in addition to vital organs such as the liver, spleen, kidneys, and brain. Severe pain associated with VOCs also has a substantial detrimental impact on quality of life for individuals with SCD, and is associated with increased health care utilization, financial hardship, and impairments in education and vocation attainment. Previous treatments have targeted primarily SCD symptom management, or were broad nontargeted therapies, and include oral or parenteral hydration, analgesics (including opioids), nonsteroidal anti-inflammatory agents, and various other types of nonpharmacologic pain management strategies to treat the pain associated with VOC. With increased understanding of the pathophysiology of VOCs, there are several new potential therapies that specifically target the pathologic process of vaso-occlusion. These new therapies may reduce cell adhesion and inflammation, leading to decreased incidence of VOCs and prevention of end-organ damage. In this review, we consider the benefits and limitations of current treatments to reduce the occurrence of VOCs in individuals with SCD and the potential impact of emerging treatments on future disease management.

Reduced Oxidative Stress and Enhanced Nitric Oxide (NO) Bioavailability in Transgenic-Knockout Sickle Mice Expressing Fetal Hemoglobin (HbF) Is Mediated by Decreased Sickling and Hemolysis.

Blood ◽  
2007 ◽  
Vol 110 (11) ◽  
pp. 842-842
Author(s):  
Trisha Dasgupta ◽  
Mary E. Fabry ◽  
Dhananjay K. Kaul
Keyword(s):  
Oxidative Stress ◽  
Sickle Cell Disease ◽  
Sickle Cell ◽  
Genetic Manipulation ◽  
Fetal Hemoglobin ◽  
Organ Damage ◽  
Multiple Organ ◽  
Protective Effects ◽  
Cell Disease ◽  
No Bioavailability

Abstract The primary event in the vaso-occlusive pathophysiology of sickle cell disease (SCD) is polymerization of hemoglobin S under deoxygenated conditions. In SCD, sub-clinical transient vaso-occlusive events caused by red cell sickling are likely to be more frequent resulting in “reperfusion injury” that generates reactive oxygen species and results in chronic oxidative stress that will contribute to multiple organ damage. In fact, previous studies have suggested that sickling is etiologic to repefusion injury and oxidative stress (Kaul and Hebbel, JCI, 2000), although the effect of antisickling therapy on oxidative stress has not been evaluated. Increasing the levels of antisickling fetal hemoglobin (HbF) by hydroxyurea therapy markedly reduces polymer formation. HbF exerts an ameliorating effect in sickle cell disease patients both on red cells and in the prevention of multiple organ damage. Here, we hypothesize that induction of HbF by genetic manipulation (in the absence of pharmacological manipulation) will reduce organ oxidative stress by reducing sickling and hemolysis, and thereby increase NO bioavailability. To test our hypothesis, we measured activity of selected antioxidants and lipid peroxidation (LPO) in BERK mice expressing exclusively human α- and βS-globins and varying levels of HbF, i.e., BERK (<1% HbF), BERKγM (20% HbF) and BERKγH (40% HbF). Percent sickled cells in venous samples (drawn in 2.5% glutaraldehyde solution in 0.1M cacodylate buffer) showed a distinct decrease with increased %HbF (P<0.05, multiple comparisons). Consistent with maximal sickling, BERK mice showed 5.4–6.9-fold increase in LPO in various tissues (muscle, kidney and liver) compared with C57BL controls (P<0.001). In contrast, BERKγM and BERKγH mice showed a marked decrease (73% and 80%, respectively) in LPO compared with BERK mice (P<0.001). Also, activity/levels of antioxidants (superoxide dismutase [SOD], catalase, glutathione peroxidase [GPx] and reduced glutathione [GSH]) showed significant decreases in BERK mice (P<0.001–0.00001). On the other hand, BERKγM and BERKγH mice showed significant increases in antioxidant activity (P<0.05–0.0001). Induction of HbF was associated with increased levels of NO metabolites (NOx) and reduced hemolysis; the latter is in agreement with our previous observations in BERKγM mice (Kaul et al. JCI, 2004). These results strongly suggest that reduced sickling and hemolysis in the presence of HbF cause increased NO bioavailability. NO is well known to exert antioxidative effects. Thus, we show for the first time that the induction of antisickling HbF leads to an increase in NO bioavailability and a decrease in oxidative stress, and that these protective effects are mediated primarily by reduced intravascular sickling.

Transfusional Iron Overload In An Adult Sickle Cell Disease Population: Epidemiology, Prevalence, and Management

Blood ◽  
2013 ◽  
Vol 122 (21) ◽  
pp. 1005-1005 ◽  
Author(s):  
James Son ◽  
Hongyan Xu ◽  
Nadine J Barrett ◽  
Leigh G Wells ◽  
Latanya Bowman ◽  
...  
Keyword(s):  
Sickle Cell Disease ◽  
Iron Overload ◽  
Sickle Cell ◽  
Serum Ferritin ◽  
Chelation Therapy ◽  
Organ Damage ◽  
Morbidity And Mortality ◽  
Genotype Distribution ◽  
Cell Disease ◽  
The Mean

Abstract Transfusional iron (Fe) overload remains a significant problem among patients with chronic, transfusion dependent anemias, especially in transfusion dependent ß-thalassemia (Thal) syndromes. If not treated vigorously with chelation, Fe overload in Thal is associated with significant organ damage, especially with chronic liver disease and cardiac abnormalities which can contribute to morbidity and mortality. In recent decades, the significance of Fe overload in sickle cell disease (SCD) has also been recognized especially among pediatric patients on chronic transfusion regimens predominantly for primary and secondary prevention of stroke. The prevalence and significance of this problem among adult SCD patients is less clear, although it is widely believed that episodic, mostly unnecessary transfusion practices play a more prominent role in this patient population. There have been reports of an association between iron overload and increased morbidity and mortality among adult SCD patients; it has also been speculated that the chronic inflammatory state that exists in SCD affords some degree of protection against severe organ damage through upregulation of hepcidin and sequestration of Fe in these patients. We performed a retrospective review of 635 adult SCD patients followed at our Center to define and ascertain the epidemiology, prevalence, etiology, and clinical correlates of transfusional Fe overload. Fe overload was defined as two consecutive serum ferritin values of > 1000 ng/ml. 80 patients (12.6%) met this criterion. Of these, 38 were male and 42 were female. Genotype distribution was: 73 SS, 3 S-β+ thal, 2 S-β0 thal and 2 SC. The mean age was 35.9 (range 18-69). Out of the 80 patients with transfusional Fe overload, 24 (30%) were/had been on a chronic transfusion regimen (23 for secondary or primary stroke prevention and one for childhood cardiomyopathy). Seventy percent of the patients (n=56) developed Fe overload from episodic transfusions predominantly performed at outlying community hospitals. The mean highest ferritin value was 4991 ng/ml (range 1,052-16,500). There was no correlation between ferritin levels and the number of hospitalizations or painful episodes (p=0.9). Thirty seven patients (46.2%) had a history of chelation therapy (with desferoxamine, deferasirox, or both). In 25 patients who have been on deferasirox for a period of 6 months or more, serum ferritin levels decreased from 4452.3 to 3876.6 ng/ml (p=0.3239). Our retrospective study shows that transfusional Fe overload is not rare among adults with SCD and develops predominantly as a result of episodic blood transfusions. This underscores the importance of the development and dissemination of evidence based guidelines, especially for episodic transfusions in SCD. A careful study of the extent and degree of organ damage associated with transfusional Fe overload in SCD and why less than half (46.2%) of patients are exposed to chelation therapy needs to be done. These studies should include liver iron concentration (LIC), cardiac iron and liver histology, when indicated, in parallel with serum hepcidin levels. The fact that the reduction in serum ferritin levels with deferasirox did not reach statistical significance in this cohort can be explained by the relatively small number of patients as well as by the short period (6 months) of exposure to chelation therapy. Disclosures: No relevant conflicts of interest to declare.

In Vivo Modeling Of Genetic Mechanisms Associated With Sickle Cell Disease Nephropathy

Blood ◽  
2013 ◽  
Vol 122 (21) ◽  
pp. 2224-2224
Author(s):  
Blair R Anderson ◽  
Erica E Davis ◽  
Marilyn J. Telen ◽  
Allison E Ashley-Koch
Keyword(s):  
At Risk ◽  
Sickle Cell Disease ◽  
Glomerular Filtration ◽  
Sickle Cell ◽  
Organ Damage ◽  
Strong Linkage Disequilibrium ◽  
Wild Type ◽  
Cell Disease ◽  
Gene Suppression ◽  
End Organ Damage

Abstract End-organ damage in patients with sickle cell disease (SCD) has become an emergent clinical priority over recent decades due to the increased lifespan of affected individuals. Renal failure (ESRD), which occurs in 4-12% of SCD patients and is strongly associated with early mortality, has become a particular concern. The detection of SCD nephropathy (SCDN) relies on relatively late markers of the disease process, namely proteinuria and reduced glomerular filtration rate (GFR). Therefore, at-risk SCD patients cannot be identified prior to end-organ damage. A genomic region on human chromosome 22 containing two genes, MYH9 and APOL1, has been associated with non-SCD nephropathy, although the primary gene responsible has remained elusive due to strong linkage disequilibrium in this region. Our group demonstrated that both MYH9 and APOL1 are strong, independent genetic predictors of risk for proteinuria in SCD and interact to affect GFR (Ashley-Koch et al., 2011). We have now used zebrafish as a model to study the contribution of each gene (myh9 and apol1) to kidney function and filtration. To test independent effects of the knockdown of myh9 or apol1, we injected morpholino (MO) antisense oligonucleotides in wild-type zebrafish embryos; this resulted in generalized edema (64% [myh9-MO] and 58% [apol1-MO], both significantly different compared to 3% of control embryos) and reduced glomerular filtration (as measured by quantitative dextran clearance; myh9-MO p=0.047 and apol1-MO p=0.042 when compared to control embryos) for both gene suppression models. Each morphant phenotype was rescued significantly by co-injection of each respective wild type human MYH9 (p=0.001) and APOL1 (p=0.043) mRNA. Importantly, co-injection of human mRNA corresponding to other APOL gene family members did not significantly rescue the observed apol1-MO phenotype, suggesting that apol1 is indeed the functional ortholog to the human gene. Next, we investigated the possibility of a genetic interaction between MYH9 and APOL1 by co-suppression of each of the zebrafish orthologous genes. We observed no additive or synergistic effects due to the co-suppression. Instead, the double morphants were indistinguishable from the myh9 morpholino alone, and neither single morpholino could be rescued by the human mRNA of the other gene. These data suggest that MYH9 and APOL1 may function independently but converge on the same biological process to affect risk of SCDN. In addition to evaluating the effects of candidate gene suppression in wild-type models, we have begun to utilize anemic zebrafish models described previously (Shah et al., 2012). Our preliminary work suggests that the myh9 knockdown phenotype is exacerbated under anemic stress. Ongoing efforts are aimed at identifying novel genetic contributions to SCDN through genome-wide association analysis and exome sequencing of extreme phenotypes in SCD patients, with functional evaluation of putative genetic candidates in our zebrafish model. By offering new insights into the contribution of genes that regulate renal function, these results further our understanding of the pathogenesis of SCDN and may provide genetic markers for the identification of at-risk SCD patients prior to the onset of kidney dysfunction. Disclosures: No relevant conflicts of interest to declare.

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