scholarly journals Two Stage Intravital Imaging Mouse Model to Assess Venous Thromboembolism in Sickle Cell Disease

Blood ◽  
2021 ◽  
Vol 138 (Supplement 1) ◽  
pp. 3225-3225
Author(s):  
Tomasz Brzoska ◽  
Tomasz W. Kaminski ◽  
Egemen Tutuncuoglu ◽  
Mark T. Gladwin ◽  
Prithu Sundd

Abstract Sickle cell disease (SCD) patients have an increased risk of venous thromboembolism (VTE). Population-based studies demonstrated that VTE has a cumulative incidence rate of approximately 25% in adult SCD patients and is associated with higher risk of mortality. VTE in SCD is most commonly manifested as deep vein thrombosis (DVT) with associated pulmonary embolism (PE). Although autopsy studies have regularly discovered pulmonary thromboembolic lesions in SCD patients, the pathophysiology of VTE in SCD remains largely unknown mostly due to the lack of relevant animal VTE model. Understanding the mechanisms that promote VTE in SCD is imperative to identify its prevention and treatment measures. To elucidate the cellular, molecular and biophysical mechanisms of VTE in SCD we developed an innovative two stage intravital imaging analysis experimental model in SCD mice. DVT in SCD mice was induced by surgical ligation of femoral vein. Venous thrombus formation was visualized using intravital multi-photon-excitation (MPE) microscopy. Venous thrombus took the form of a large mass of elliptical shape which extended in the long-axis direction of the femoral vein. It was composed of fibrin, erythrocytes and sparse platelets. Over time, thrombus was infiltrated by migrating neutrophils. To trigger acute PE, femoral vein ligation was removed and the venous thrombus was observed to spontaneously detach and travel to the SCD mouse lung. This method allowed real time visualization of acute PE in vivo using MPE microscopy of intact lung in live breathing mice. Acute PE involved embolization of the pulmonary arterioles and the arteriolar bottle-necks located at the junction of pulmonary arterioles and capillaries. The embolization of arteriolar circulation led to loss of blood flow in the arterioles and the down-stream capillaries. Herein we introduce an intravital microscopy approach to probe VTE in SCD live mouse. Our model has potential application in investigating the molecular determinants of VTE associated with SCD as well as evaluating efficacy of new antithrombotic drugs. Disclosures Sundd: Bayer: Research Funding; CSL Behring Inc: Research Funding; Novartis: Membership on an entity's Board of Directors or advisory committees, Research Funding.

Blood ◽  
2013 ◽  
Vol 122 (21) ◽  
pp. 2214-2214
Author(s):  
Rakhi P. Naik ◽  
Carlton Haywood ◽  
Michael B. Streiff ◽  
Sophie Lanzkron

Abstract Background An increased risk of venous thromboembolism (VTE) among individuals with sickle cell disease (SCD) has only recently been recognized. Unlike arterial thrombosis such as stroke which primarily occurs in children with SCD, VTE risk in SCD appears to increase in young adulthood. To date, no studies have described the incidence of VTE in adolescents and adults with SCD. We performed a secondary analysis of the largest prospective cohort of SCD patients, the Cooperative Study of Sickle Cell Disease (CSSCD), to estimate the incidence rate and age-specific cumulative incidence of first VTE among SS/Sβ0 patients aged 15 or older. Methods We used available data from Phase 1 of the CSSCD,1 a multi-institution longitudinal prospective study conducted from 1978-1988, to identify cases of first VTE in patients aged 15 or older at enrollment with SS/Sβ0 genotype. Individuals with a history of prior VTE were excluded. VTE was defined as any pulmonary embolism (PE) or deep venous thrombosis (DVT) identified by ICD-9 code except in the case of pregnancy where VTE events were explicitly collected. Because the definition of acute chest syndrome (ACS) in the CSSCD also included PE and because the ICD-9 code for PE was also used for pulmonary infarct in cases of potential ACS, PE cases that were identified during an admission for ACS were included only if a negative chest X-ray was recorded. The date of VTE was recorded as being the date of the annual visit for any interim VTE or as the date of discharge for any VTE that occurred during a hospitalization. 95% Confidence intervals (CI) for incidence rates were calculated using a Poisson distribution assumption. Kaplan-Meier failure curves were generated to estimate age-specific cumulative incidence. Results A total of 1,133 individuals with SS/Sβ0 aged ≥ 15 years with 6,608 years of follow-up were included for analysis. During this study period, 43 incident VTE events were identified. The median age at VTE was 26.3 years (range 17-47 years) and 25 (58%) were female. The overall incidence rate for VTE was 6.5 events/1000 person-years (CI 4.7, 8.8). The Kaplan-Meier failure curve for VTE is shown below. The cumulative incidence of first VTE was estimated as 9.0% (CI 6.4-12.7) by age 30 and 14.1% (CI 10.2-19.2) by age 40. Conclusions The incidence rate of first VTE among SS/Sβ0 patients aged ≥ 15 years appears to be high, with an estimated cumulative incidence by age 40 that far exceeds that for Factor V Leiden carriers (estimated 6.2% by age 65).2 This study underscores the thrombophilic state of SCD and emphasizes the need for further research into the risk factors for VTE in the SCD population. 1. Gaston M, Rosse WF. The cooperative study of sickle cell disease: review of study design and objectives. Am J Pediatr Hematol Oncol 1982; 4: 197-201. 2. Heit JA, Sobell JL, Li H, Sommer S. The incidence of venous thromboembolism among Factor V Leiden carriers: a community-based cohort study. J Throm Haemost 2004; 3: 305-11. This Abstract was prepared using CSSCD Research Materials obtained from the NHLBI via BioLINCC (https://biolincc.nhlbi.nih.gov/). Disclosures: Naik: NHLBI: Research Funding. Haywood:NHLBI: Research Funding. Lanzkron:GlycoMimetics, Inc.: Research Funding.


Author(s):  
Vishal K. Gupta ◽  
Rachel Strykowski ◽  
Brittany Scarpato ◽  
Romy Lawrence ◽  
Sarah L. Khan ◽  
...  

Blood ◽  
2020 ◽  
Vol 136 (Supplement 1) ◽  
pp. 16-17
Author(s):  
Wally R Smith ◽  
Benjamin Jaworowski ◽  
Shirley Johnson ◽  
Thokozeni Lipato ◽  
Daniel M Sop

Background Even before the US upswing of the current COVID pandemic, the number of sickle cell disease (SCD) patients coming to hospitals and EDs appeared to fall drastically. This happened despite SCD patients having often been heavy utilizers of the ED and hospital for their iconic vaso-occlusive crises (VOC). Though ambulatory SCD clinics quick converted largely to telehealth in order to comply with stay-at-home orders designed to suppress person-to-person transmission, some SCD patients appeared to avoid care, delay care, or refuse doctors' invitations for care. Presumably patients did so out of COVID fears, but this has not been confirmed in the literature. Further, whether these patients had COVID symptoms but stayed at home has not been studied. As part of quality improvement (QI) to conduct COVID surveillance in an adult sickle cell program, we sought to explain and predict SCD health care utilization patterns we were observing, as well as to determine urgent physical and mental health needs of patients who appeared to be avoiding care. Methods Fifteen staff in the Adult Sickle Cell Medical Home at Virginia Commonwealth University, a large urban academic medical center, conducted a telephone survey ("wellness check"was used when we talked to patients) of all known adults with SCD over 19 days in 2020. A staff member confirmed the patient had SCD, asked permission to proceed, then asked about symptoms consistent with COVID-19. At the end of the telephone survey, respondents wer invited to complete an email survey of sickle cell and COVID-19 utilization attitudes (19-33 items, depending on the response pattern, either drawn from the National Health Interview Survey, from the Adult Sickle Cell Quality of Life Measurement quality of care survey, or drafted by the authors), the Sickle Cell Stress Survey-Adult (SCSS-A, a 10-item previously validated survey), and anxiety and depression (PHQ9 of the PRIME-MD). Results Of 622 adults approached by phone call, 353 responded to the following yes/no screening questions regarding the prior 14 days: fever over 100 F 0/353 (0.00%); cough 3/353(0.01%); difficulty breathing 0/353(0.00%); unexplained shortness of breath 2/353(0.01%); sore throat 2/353 (0.01%); unexplained muscle soreness 2/353(0.01%);contact with anyone who tested positive for COVID-19 2/353(0.01%); testing for COVID 19 6/353(0.02%). For QI purposes, we set a threshold of three or more COVID-associated symptoms or the presence of fever as criteria requiring intense telephone or in-person staff monitoring for the following week. Only three patients met criteria. A total of 219/353 had email surveys sent. Of 63 patients (28.8%) who returned email surveys by June 10, 2020, 35.9% had already managed a "pain attack" at home 4 or more times in the prior 12 months, and 45.5% of these said their bad ER experiences were very or somewhat important in that decision. In the prior 14 days, although 30/64 reported a crisis for at least one day, only 4/64 had visited the Emergency Department for pain. On a 0-10 scale, 21/61 patients endorsed "0" for worry that they would be COVID-infected by going for medical care (weighted mean 3.9), but 18/59 endorsed "10" for worry they were more at risk of COVID because of SCD (weighted mean 6.31), and 22/60 endorsed "10" for worry they would fare worse than others if COVID infected (weighted mean 6.97). Many patients forwent "needed" care (16/62) or delayed "needed" care by at least a day (36/61). Eleven patients met criteria for moderately severe to severe depression on the PHQ-9, and 28/63 somewhat or strongly agreed with the statement "death is always on the back of my mind" on the SCSS-A. Conclusions In adolescents and adults with SCD, many were already reticent to come to the ED for pain, but a significant portion reported delays or avoidance of needed care during the early stages of the US COVID pandemic, and few reported using the ED despite over half reporting at least one crisis day in 14. Patients nonetheless reported very few COVID-associated symptoms. Fears of COVID infection/susceptibility may limit visits for needed sickle cell care among adults. Acknowledgements: Mica Ferlis RN, FNP, Caitlin McManus, RN, FNP, Emily Sushko, RN, FNP, Justin West, RN, Kate Osborne, RN, Stefani Vaughan-Sams, Marla Brannon, BS, Nakeiya Williams, BS Disclosures Smith: GlycoMimetics, Inc.: Consultancy; Emmaeus Pharmaceuticals, Inc.: Consultancy; Novartis, Inc.: Consultancy, Other: Investigator, Research Funding; Global Blood Therapeutics, Inc.: Consultancy, Research Funding; Shire, Inc.: Other: Investigator, Research Funding; NHLBI: Research Funding; Patient-Centered Outcomes Research Institute: Other: Investigator, Research Funding; Health Resources and Services Administration: Other: Investigator, Research Funding; Incyte: Other: Investigator; Pfizer: Consultancy; Ironwood: Consultancy; Novo Nordisk: Consultancy; Imara: Research Funding; Shire: Research Funding.


Blood ◽  
2021 ◽  
Vol 138 (Supplement 1) ◽  
pp. 3091-3091
Author(s):  
Michael Rabaza ◽  
Maria Armila Ruiz ◽  
Liana Posch ◽  
Faiz Ahmed Hussain ◽  
Franklin Njoku ◽  
...  

Abstract Introduction Sickle cell disease (SCD) affects 1 in 365 African Americans and approximately 25 million people world-wide. A common skeletal system complication is avascular necrosis (AVN), which can cause substantial pain and a reduced quality of life. While early management of AVN is focused on increasing range of motion with physical therapy and pain relief, there are no clear predictors for who is more likely to develop AVN and earlier institution of these preventive measure could help decrease disease progression. Vascular endothelial growth factor (VEGF) is a biomarker of endothelial injury and may indicate reduced vascular supply to the femoral or humeral head. Here we describe potential risk factors and biologic pathways for AVN in SCD, as understanding these may lead to improvements in future monitoring, early detection, and early intervention practices. Methods We investigated clinical and laboratory risk factors associated with AVN in a cohort of 435 SCD patients from our center. Blood samples, clinical, and laboratory data were collected at the time of enrollment during a clinic visit. Genotyping for alpha thalassemia was performed by PCR and the serum concentration of VEGF was measured by ELISA. AVN status was confirmed by review of the medical record and available imaging. We conducted a cross-sectional analysis comparing categorical and linear variables by AVN status using the chi-square and Kruskal-Wallis test, respectively. The independent association of the clinical and laboratory variables with AVN status was determined by logistic regression analysis. The initial model included variables with a P-value < 0.1 on univariate analysis and the final model was ascertained by stepwise forward and backward selection. Median values and interquartile range (IQR) are provided. Results The median age of the cohort was 32 (IQR, 24 - 43) years, 57% (250/435) were female, and 46% (198/435) were on hydroxyurea. AVN was observed in 34% (149/435) of SCD patients. SCD patients with AVN were older, had more frequent vaso-occlusive crises requiring medical attention, and had a higher body mass index (Table I) (P ≤ 0.002). We measured VEGF in 241 of the SCD patients with serum samples available at the time of enrolment. Serum VEGF concentrations trended higher in SCD patients with versus without AVN (420 vs. 359 pg/mL, respectively; P = 0.078). In the multivariate analysis model, AVN was independently associated with increased number of vaso-occlusive crises (OR 1.1, 95% CI: 1.0 - 1.14; P = 0.02), AST concentration (natural log OR 0.5, 95% CI: 0.2 - 0.9; P = 0.03), VEGF concentration (natural log OR 1.4, 95% CI: 1.0 - 1.9; P = 0.047), and tobacco use (OR 1.9, 95% CI: 0.9 - 3.7; P = 0.078). Discussion In conclusion, we demonstrate a high prevalence of AVN in an adult cohort of SCD patients. The presence of AVN was independently associated with a greater frequency of vaso-occlusive pain episodes, which may demonstrate a shared pathophysiology between AVN and vaso-occlusion that merits further investigation. We demonstrate that serum VEGF concentrations are higher in SCD patients with AVN and may be a clinical tool to identify those at high-risk and for earlier intervention for this complication. Figure 1 Figure 1. Disclosures Gordeuk: Modus Therapeutics: Consultancy; Novartis: Research Funding; Incyte: Research Funding; Emmaus: Consultancy, Research Funding; Global Blood Therapeutics: Consultancy, Research Funding; CSL Behring: Consultancy. Saraf: Pfizer: Research Funding; Global Blood Therapeutics: Membership on an entity's Board of Directors or advisory committees, Research Funding; Novartis: Membership on an entity's Board of Directors or advisory committees, Research Funding.


Blood ◽  
2020 ◽  
Vol 136 (Supplement 1) ◽  
pp. 20-20
Author(s):  
Victoria Brooks ◽  
Oluwalonimi Adebowale ◽  
Victor R. Gordeuk ◽  
Sergei Nekhai ◽  
James G. Taylor

Background: Blood transfusion is a common therapy for sickle cell disease (SCD). Although, highly effective, a major limitation is development of alloantibodies to minor blood group antigens on donor red cells. Alloimmunization has a prevalence of 2-5% for transfusions in the general population, but it is significantly higher in SCD. Risk factors for alloimmunization have been poorly characterized, although number of lifetime transfusions is an important risk factor. Alloimmunization has been clinically observed in children with a prevalence of about 7%. With development of each antibody, blood donor matching becomes increasingly difficult and expensive with an increased risk for transfusion reactions and diminished availability of compatible red cell units for treatment of SCD. The ability to identify risk factors for developing alloantibodies would be beneficial for clinicians. To identify markers for alloimmunization in SCD, we have analyzed children and adults who developed this complication. Methods: We analyzed The Pulmonary Hypertension and Hypoxic Response in Sickle Cell Disease (PUSH) study, which enrolled n=468 pediatric and n=59 adult SCD subjects. In both children and adults, alloimmunization cases were defined as a history of at least 1 alloantibody. Controls in both cohorts were defined as subjects with no history of alloantibodies and receipt of more than 10 lifetime red cell transfusions. All others within the study who did not meet these criteria were assigned to a third comparison group. To identify differences between cases, controls and all others, we performed univariate analyses (using ANOVA or Kruskal Wallace where appropriate) for clinical parameters and laboratories. Case control comparisons were also performed for selected variables and plasma levels for 11 cytokines. Results were further analyzed using regression modeling. Results: The overall prevalence of alloimmunization was 7.3% among children (34/468 subjects; median age 12, range 3-20 years) compared to 28.8% in adults (17/59 subjects; median age 37, range 18-73 years). When only considering those with >10 lifetime transfusions, the prevalence was considerably higher at 29.3% and 54.8% in children and adults, respectively. At the same time, 8 pediatric (23.5%) and 5 adult (29.4%) alloimmunization cases had received fewer than 10 transfusions. In a 3-way pediatric cohort comparison (cases, controls and all others), risk factors associated with alloimmunization included SS genotype, older age and markers of more severe disease (higher ferritin, WBCs, platelets and total bilirubin). Comparison of cases to controls showed alkaline phosphatase (P=0.05) was significantly lower in cases, whereas AST (P=0.02) was significantly higher even with adjustment for age. Levels of plasma cytokines MCP-1 (P=0.01) and IFNgamma (P=0.08) were lower in cases from a subset of the pediatric cohort. In adults, only 4/59 (6.8%) subjects had never received a lifetime transfusion (all non-SS). In the adult 3-way comparisons, only SS genotype and higher ferritin were associated with alloimmunization. The adult case control analysis showed higher absolute monocyte count (P=0.02), absolute eosinophil count (P=0.04) and absolute basophil count (P=0.008) in association with alloimmunization cases. In addition, alkaline phosphatase was again significantly lower among cases (P=0.02) as seen in the pediatric cohort. There were no significant differences in cytokine levels among adults. Conclusions: When considering only transfused SCD patients, the prevalence of alloimmunization is higher than 30%. As seen in prior studies, higher lifetime red cell transfusions are an important risk factor especially among adults where most patients have received transfusions. Children who develop alloantibodies appear to have laboratory markers of more severe disease, but this is not observed in adults. A novel association observed across both pediatric and adult subjects is a significantly lower serum alkaline phosphatase in those with alloantibodies. The results of this study suggest a need for improved tracking of red cell transfusion therapy in the US for SCD patients due to a high prevalence of alloimmunization. Further study is also needed to elucidate the significance of the alkaline phosphatase association. Disclosures Gordeuk: CSL Behring: Consultancy, Research Funding; Global Blood Therapeutics: Consultancy, Research Funding; Novartis: Consultancy; Ironwood: Research Funding; Imara: Research Funding.


Blood ◽  
2019 ◽  
Vol 134 (Supplement_1) ◽  
pp. 2286-2286
Author(s):  
Kiranveer Kaur ◽  
Ying Huang ◽  
Subha Raman ◽  
Eric H. Kraut ◽  
Payal Desai

Introduction: Myocardial ischemic injury remains an under recognized problem in patients with sickle cell disease (SCD), for which the exact prevalence remains undefined. SCD patients are known to have microvascular disease, impaired myocardial perfusion reserve and lack of typical epicardial vessel involvement based on prior data. Previous study at our institution has demonstrated that 3/22(13%) patients with clinically stable sickle cell disease had impaired myocardial perfusion reserve but no epicardial coronary artery disease. In this study, we will aim to learn prevalence of cardiac injury and microvascular ischemic disease. We will also evaluate for impact of these findings on overall survival (OS) of SCD patients. Methods: We conducted a retrospective chart review of patients with SCD seen at OSU Wexner Medical Center from July 2005 to July 2015 to identify patients who had elevated troponin-I level or cardiac MRI performed for chest pain. Clinical and laboratory data around the time of cardiac MRI and troponin elevation was collected. Abnormal MRI was defined in three ways: 1) Microvascular disease was defined by presence of subendocardial or myocardial perfusion defects and myocardial scarring. 2) Myocardial disease otherwise includes other findings suggestive but not specific for myocardial ischemia including left ventricular dysfunction, midmyocardial fibrosis, inflammation and regional wall motion abnormalities. 3) Abnormal MRI includes patients described in either 1) or 2). Kaplan-Meier (KM) method was used to evaluate the impact of microvascular disease defined in all 3 ways on OS. Proportional hazards model was fit to estimate the association between troponin elevation and OS, where troponin elevation was treated as a time-dependent variable and OS was measured from time of birth. Results: Sixty-nine (51% male; genotype Hb SS 75%, SC 16%, and Sβ-thal 9%) of 373 SCD patients had either abnormal troponin and/or had cardiac MRI done. Median age was 34 years (range 19-67 years). Of 238 patients who had troponin-I measured over this period, 18 % (n=42) had elevated troponin. 24 of 47 patients with cardiac MRI showed abnormalities described above specific for microvascular disease (n=14, 30%) and myocardial disease otherwise (n=10, 21%). We identified 22 patients with troponin measurement within 30 days before cardiac MRI. Elevated troponin levels predicted MRI abnormalities with sensitivity of 71% (95% confidence interval (CI) 42-92%) and specificity of 63% (95% CI 24-91%). The degree of troponin elevation did not correlate with the MRI abnormality. Hazard ratio of death in patients with elevated troponin was 5.1 (95% CI 2.7-9.6; p<0.0001). While the KM survival curves show lower OS in patients in abnormal MRI (p=0.74) and microvascular disease (p=0.42; Figure 1) group compared with normal MRI, the comparisons were not statistically significant. There was no difference in OS for patients with nonspecific myocardial disease findings (p=0.59). Conclusion: Over a 10-year period, the prevalence of cardiac injury as measured by elevated troponin was 18% (42/238) in patients with atypical chest pain. Among 47 patients who had cardiac MRI performed, 51% were abnormal with 30% having findings specific for microvascular cardiac disease. Troponin elevation appears to significantly increase the risk of all-cause mortality. Patient with microvascular and myocardial ischemic disease tend to have lower OS, but it did not reach statistical significance. This could be one of the potential contributing factors to high early mortality and sudden deaths in SCD patients. Further studies will be needed to elaborate on disease modifying interventions that impact survival in these patients. Disclosures Desai: Novartis: Research Funding; Pfizer: Membership on an entity's Board of Directors or advisory committees, Research Funding; Potomac: Speakers Bureau; Global Blood Therapeutics: Membership on an entity's Board of Directors or advisory committees, Research Funding; University of Pittsburgh: Research Funding; Ironwood: Other: Adjudication Board.


Blood ◽  
2007 ◽  
Vol 110 (3) ◽  
pp. 908-912 ◽  
Author(s):  
Harland Austin ◽  
Nigel S. Key ◽  
Jane M. Benson ◽  
Cathy Lally ◽  
Nicole F. Dowling ◽  
...  

Abstract People with sickle cell disease have a chronically activated coagulation system and display hemostatic perturbations, but it is unknown whether they experience an increased risk of venous thromboembolism. We conducted a case–control study of venous thromboembolism that included 515 hospitalized black patients and 555 black controls obtained from medical clinics. All subjects were assayed for hemoglobin S and hemoglobin C genotypes. The prevalence of the S allele was 0.070 and 0.032 for case patients and controls, respectively (P < .001). The odds that a patient had sickle cell trait were approximately twice that of a control, indicating that the risk of venous thromboembolism is increased approximately 2-fold among blacks with sickle cell trait compared with those with the wild-type genotype (odds ratio = 1.8 with 95% confidence interval, 1.2-2.9). The odds ratio for pulmonary embolism and sickle cell trait was higher, 3.9 (2.2-6.9). The prevalence of sickle cell disease was also increased among case patients compared with controls. We conclude that sickle cell trait is a risk factor for venous thromboembolism and that the proportion of venous thromboembolism among blacks attributable to the mutation is approximately 7%.


2018 ◽  
Vol 16 (1) ◽  
Author(s):  
Jean Jacques Noubiap ◽  
Mazou N. Temgoua ◽  
Ronni Tankeu ◽  
Joel Noutakdie Tochie ◽  
Ambroise Wonkam ◽  
...  

2019 ◽  
Vol 12 (3) ◽  
pp. 173-182 ◽  
Author(s):  
Foluso Joy Ogunsile ◽  
Rakhi Naik ◽  
Sophie Lanzkron

Blood ◽  
2009 ◽  
Vol 114 (22) ◽  
pp. 1534-1534
Author(s):  
Kevin Cheng ◽  
Mehdi Nouraie ◽  
Xiaomei Niu ◽  
Evadne Moore-King ◽  
Margaret F. Fadojutimi-Akinsi ◽  
...  

Abstract Abstract 1534 Poster Board I-557 Background Low bone mass density affects more than 65% of adult sickle cell disease patients and correlates with lower hemoglobin and higher ferritin concentrations (1). Increased iron supply promotes osteoclast differentiation and bone resorption (2). Proinflammatory cytokines also promote bone resorption (3). Tartrate resistant acid phosphatase isoform 5b (TRACP-5b) is produced only by activated osteoclasts and therefore serves as a marker of bone resorption (4). Sickle cell disease is a condition of chronic inflammation and patients often suffer from transfusional iron overload as well. In this study we aimed to determine the predictors of bone resorption in patients with sickle cell disease by measuring circulating levels of TRACP-5b. Methods Fifty-nine adult sickle cell disease patients and 22 apparently healthy controls were recruited at Howard University Hospital. Patients were at steady state with no crisis, hospitalization or blood transfusion in the last 3 weeks. Clinical and laboratory information was collected at the time of recruitment and TRACP-5b was measured in non-fasting serum samples using an enzyme immuno assay kit (Quidel, San Diego, CA). Serum concentrations of inflammatory cytokines and growth factors were measured by Multiplex assay (Bio-Rad, Hercules, CA).. Results Sickle cell disease patients had elevated concentrations of TRACP-5b compared to controls (median values of 4.4 vs. 2.4 U/l, P < 0.0001). Among the patients, TRACP-5b concentrations correlated positively with number of blood transfusions (r = 0.19) and serum concentrations of alkaline phosphatase (r=0.46), endothelin-1 (r=0.39), interleukin-8 (r= 0.38), and interleukin-6 (r=0.25). TRACP-5b correlated negatively with RANTES (r = -0.42) and PDGF (r = -0.31). It did not correlate significantly with serum ferritin (r = -0.03), LDH (r = 0.13) or hemoglobin concentration (r = 0.11). Interestingly, TRACP-5b correlated positively with tricuspid regurgitation velocity, which reflects systolic pulmonary artery pressure (r = 0.30). Conclusion Sickle cell patients have elevated steady-state osteoclast activity as reflected in serum TRACP-5b concentrations. Multiple blood transfusions and inflammation are associated findings. Among patients, higher TRACP-5b concentrations are associated with lower concentrations of RANTES and PDGF-BB, factors that influence function of osteoblasts. Further studies are needed to investigate whether common pathways may be involved in osteoclast activation and pulmonary changes in sickle cell disease. Supported by grants number 2 R25 HL003679-08 and 1 R01 HL079912-02 and 1U54HL090508-01 from NHLBI, by Howard University GCRC grant no 2MOI RR10284-10 from NCRR, NIH, Bethesda, MD, and by the intramural research program of the National Institutes of Health. Disclosures Gordeuk: Biomarin: Research Funding; TRF Pharma: Research Funding; Merck: Research Funding; Novartis: Speakers Bureau.


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