Correlations of Red Cell-Derived Micropareticles (RMP) with Other MP Species in Hematological and Thrombotic Disorders

Abstract Background: We have recently observed that increased levels of circulating RMP are associated with several hematological disorders and thrombophilic states, and that levels were significantly higher when thrombosis was present. However, other species of MP, such as from platelets (PMP), endothelia (EMP), leukocytes (LMP) and annixin V-binding (AnV) have also been shown to be associated with thrombophilic states. The purpose of this study was to determine if correlations exist between RMP and other MP. Methods: This is a retrospective analysis of 702 laboratory samples over an 8 year period, limited to elevated values: >2SD above normal controls (>2,000/uL).. About 87% were individuals, the remaining 13% were tested 2-3 times and all tests >3 per patient were excluded. The disorders were hemolytic anemia (HA, n=38), hypercoagulable state (HCS, n=64), immune thrombocytopenia (ITP, n=86), thrombocytopenia of all causes (TP, n=69), myeloprolifereative disorder (MPD, n=29), thrombotic thrombocytopenic purpura (TTP, n=29), antiphospholipid syndrome (APS, n=34), pulmonary embolism (PE, n=21), and all-cause thrombosis (TBS, n=251). Some were classified in more than one way. MP species assayed were RMP by glycophorinA, PMP by CD41 (PMP41), PMP by CD42 (PMP42), EMP by CD31+/42- (EMP31), EMP by CD62E (EMP62E), LMP by CD45, annexin V binding (AnV), and counts by lectin, FITC-Ulex, which efficiently detects total MP including very small. Results: In HCS, the RMP >2,000/uL correlated well with PMP41 (R=0.407, p <0.001) and with PMP42 (R=0.285, p =0.02). In ITP, the RMP correlated solely with PMP42,31 (R=0.331, p =0.003). In HA, the RMP correlated with LMP (R=0.408, p =0.009) and with PMP42 (R=0.340, p =0.03). In all-cause TBS, RMP correlated with PMP41 (R=0.164, p =0.0120 and with LMP (R=0.231, p <0.001). In MPD, the RMP correlated solely with ulex (R=0.343, p <0.01). There was no significant correlation between RMP >2,000/uL and any of the MP markers in APS, TP, or TTP. The MP species markers, EMP31, EMP62E, and AnV, failed to show correlation with RMP in any of the disorders analyzed. In addition, we tested for correlations between elevated RMP and other MP for the entire data set (all disorders combined) and found that only LMP was significant (p <0.05). However, when the data was sorted by increasing LMP, it was found that the highest quintile showed improved correlation with RMP (p <0.01) while the lowest quintile of LMP values yielded no correlation at al (p > 0.05). Discussion: These correlation analyses shows that RMP correlated most frequently with PMP, as seen in HA, ITP, HCS, and TBS, followed by LMP, as seen in HA and TBS. These observations suggest that platelet or/and leukocyte activation may be involved in RMP generation. Of added interest is the finding that the overall data correlated well with LMP only at the higher LMP levels, not at all in the lower quintile of LMP. This suggests that RMP elevations are associated with immunolgic, inflammatory processes. In summary, correlation analysis reveals likely interaction between red cells and platelets or leukocytes during immunologic, inflammatory or in thrombophilic states, resulting in elevated RMP. Disclosures No relevant conflicts of interest to declare.

Download Full-text

Elevated Complement (C) and IgG Bound Microparticles (MP) in Immune Thrombocytopenic Purpura (ITP) and Hemolytic Anemia (HA).

Blood ◽

10.1182/blood.v114.22.1313.1313 ◽

2009 ◽

Vol 114 (22) ◽

pp. 1313-1313

Author(s):

Wenche Jy ◽

Lawrence L Horstman ◽

Andrew Lin ◽

Carlos Bidot ◽

Yeon-Soong Ahn

Keyword(s):

Flow Cytometry ◽

Cell Activation ◽

Conflicts Of Interest ◽

Linear Regression Analysis ◽

Red Cell ◽

Major Mechanism ◽

Cell Destruction ◽

The Mean ◽

Underlying Mechanisms ◽

Normal Controls

Abstract Abstract 1313 Poster Board I-337 Background Cell derived microparticles (MP) are shed during cell activation and apotosis and MP profiles reflect the status of cell disturbances in various forms of pancytopenias. It was demonstrated that when antibodies fix complement (C) on the membrane, red cells evade C mediated lysis by shedding MP with bound C. We analyzed C and IgG bound to MP to gain insight on the underlying mechanisms of cell destruction. We measured C1q fragment and IgG on cell-derived (MP) in plasmas of patients with ITP, hemolytic anemias (HA) and thrombosis (TBS). Methods (1) Patient population. Consenting patients consisted of 18 TBS, 14 ITP and 6 HA (5 AIHA and 1 TTP), as well as 20 normal controls (NC). (2) Flow cytometry. MP were centrifuged from 1 mL fresh (not frozen) platelet-poor plasma (PPP), washed twice with saline, resuspended in 100 μL, then incubated with fluorescent mAb to C1q and IgG, then analyzed by flow cytometry. In addition, MP in the PPP were analyzed for MP from RBC (RMP) using marker glycophorin A, and MP from platelets (PMP) by CD42b. Values were considered elevated if >2SD above the mean of NC. Control values were (mean ±SD per μL): C1q+ MP = 536 ±151; IgG+ MP = 5,542 ±2,081; RMP = 823 ±246; PMP = 7,520 ±2,084. Results We observed significant elevation of C1q+ and IgG+ MP in patients with ITP (2-3 fold) and hemolytic anemias (6-10 fold) but not in those with thrombosis. These findings indicate that complement mediated cell destruction or disturbance in these disorders is frequent. (1). The ITP group consisted of 2 subgroups, one of which had elevated C1q+ and IgG+ MP, the other not, and these subgroups also differed in RMP. Specifically, six ITP with high C1q+ MP also had high RMP (1,899 ±682 /μL) and PMP (16,602 ±4,216 /μL) while those with normal C1q+ MP had normal RMP (504 ±186 /μL) and PMP (3,472 ±1196 /μL). This suggests that platelet destruction in ITP can proceed via C in some but not all cases, probably depending on the autoantibodies. We have previously reported high RMP in ITP. These findings suggest subclinical C mediated hemolysis in a subset of ITP. (2) In HA patients, all 6 had elevated C1q+ MP (3,934 ±1,419 /μL, p<0.001) as compared to normal controls (536 ±151 /μL). The mean in HA was nearly 6-fold greater than NC. The HA group also had higher IgG+ MP, with mean counts about 10-fold higher than NC (61,531 ±20,733 vs. 5,542 ±2,081 /μL, p<0.001). Furthermore, the HA patients also had elevated RMP (2,191 ±635 /μL, p<0.01). This suggests that C-mediated destruction of RBC is a major mechanism in HA. (3) Linear regression analysis showed that C1q+ MP is well correlated with IgG+ MP (R = 0.84, p<0.0001) and RMP (R = 0.79, p<0.001). (4) The TBS group did not show higher levels of any of the measures assayed. It is widely believed that phagocytosis is the mechanism of cell destruction in ITP and AIHA. Our findings support the concept that complement (C) -mediated platelet or red cell destruction play an important role and is common in these disorders. Assay of C and IgG on MP can provide new insight to underlying mechanisms of immune mediated platelet and red cell destruction. Disclosures No relevant conflicts of interest to declare.

Download Full-text

Comparison of Pharmacokinetics and Hemostatic Efficacy of Red Cell Microparticles (RMP) in Rabbits Using Different Infusion Regimens

Blood ◽

10.1182/blood.v124.21.2811.2811 ◽

2014 ◽

Vol 124 (21) ◽

pp. 2811-2811 ◽

Cited By ~ 1

Author(s):

Wenche Jy ◽

Carlos Bidot ◽

Max E Johansen ◽

Lawrence L Horstman ◽

Rifat Pamukcu ◽

...

Keyword(s):

Steady State ◽

Continuous Infusion ◽

Conflicts Of Interest ◽

Isotonic Saline ◽

Annexin V ◽

Procoagulant Activity ◽

Rapid Decline ◽

Red Cell ◽

Excessive Bleeding ◽

Hemostatic Efficacy

Abstract INTRODUCTION: Excessive bleeding is a life-threatening challenge in many areas of medical practice, especially in surgical procedures and trauma care. Few treatment options are available to meet the challenge of preventing or treating excessive bleeding, and none of them is satisfactory. The efficacy of red cell microparticles (RMP) in reducing blood loss has been documented in rat and rabbit bleeding models, as summarized in a recent publication by Jy et al. [Thromb. & Haemost., 2013;110:751-60]. No adverse effects were noticed in short-term observation of either model with the effective dose used. The rate of clearance of RMP in vivo has not been analyzed systemically. The purpose of this study is to characterize the pharmacokinetics / rate of clearance of RMP in rabbit model by different infusion regimens and to establish the relationship between blood concentration and hemostatic efficacy of RMP. METHODS: (i) RMP were produced by high pressure extrusion method [Thromb. & Haemost., 2013; 110:751-60]. The resulting product was washed twice with isotonic saline, lyophilized, and stored at -80°C. (ii) Pharmacokinetics of RMP were measured using either bolus infusion of RMP (3x109 counts/kg) during 1 min., or a combination of bolus (1/3 of total RMP) followed by continuous infusion (2/3 of total RMP) for 30 min to the sedated non-bleeding rabbits. Blood samples (1 mL each) were collected at intervals: 5 min pre-injection, and at 1, 3, 5, 7.5, 10, 15, 20, 25, 30, 45, and 60 min post-injection. A sample size of 5 animals was used for each infusion regimen. Levels of RMP were assayed by flow cytometry with dual labeling: anti-CD235a-PE and Annexin V-FITC. The former is specific for human RMP and will not label rabbit RMP. The latter is not species sensitive and labels both human and rabbit MP. (iii)The procoagulant activity of RMP in rabbit blood was assayed by thromboelastogram (TEG). RESULTS:(1) BolusInfusion of RMP (3 x109 counts/kg) resulted in a rapid rise of RMP levels peaking at 1 min post-infusion followed by rapid decline to baseline by 10 – 15 min. The half-life (T1/2) in circulation was estimated to be ≈ 4 – 7 min. The peak RMP concentration reached 2.5 – 3.4 x107 counts/mL. (2) The 2 markers used yielded small but significantly different rates of clearance after reaching peak concentrations: the T1/2 by anti-CD235a was 6.2 ±1.0 min, and by annexin V was 4.4 ±0.7 min (p = 0.01). These results indicate that these two phenotypes of RMP were cleared by different mechanisms. RMP expressing phosphatidylserine (annexin V positive) seem to be cleared faster than those expressing CD235a. (3) Bolus followed by continuous infusion resulted in a smaller initial spike (0.7 – 1.0 x107 counts/mL) followed by a rapid decline to ≈25-30%, then steady rise over the course of 30 min. infusion, finally reaching a steady-state level of 0.4 -0.6 x107 counts/mL. RMP levels returned to baseline within 15 min after cessation of infusion. (4) The ex vivo TEG data revealed good correlation between rise and fall of circulating RMP and procoagulant activity. However, T1/2 for procoagulant activity was longer (7.4 ±1.2 min.) compared to T1/2of circulating RMP, whether measured by anti-CD235a or annexin V. On the other hand, bolus followed by continuous infusion resulted in steady elevation of procoagulant activity, with little fluctuation during the course of infusion. CONCLUSIONS: These data demonstrate that bolus followed by continuous infusion of RMP is capable of maintaining almost steady-state levels for extended periods, with concomitantly increased procoagulant activity. Accordingly, this regimen is expected to be the optimum clinical treatment for excessive bleeding. This work also demonstrates the existence of different rate of clearance for different phenotypes of RMP, suggesting that multiple mechanisms are involved in the clearance of RMP. Disclosures No relevant conflicts of interest to declare.

Download Full-text

Elevated Red Cell Microparticles (RMP) in Hematologic and Thrombotic Disorders

Blood ◽

10.1182/blood.v126.23.3553.3553 ◽

2015 ◽

Vol 126 (23) ◽

pp. 3553-3553

Author(s):

Wenche Jy ◽

Gabriel Tinoco ◽

Mohamed EL Dinali ◽

Carlos Bidot ◽

Lawrence L Horstman ◽

...

Keyword(s):

Risk Factors ◽

Conflicts Of Interest ◽

Myeloproliferative Disorder ◽

Red Cell ◽

Coagulation Disorders ◽

Leukocyte Activation ◽

Antithrombotic Treatment ◽

Platelet Destruction ◽

Thrombotic Risk ◽

High Burden

Abstract Introduction. Circulating cell-derived microparticlesa (MP) from platelets (PMP), leukocytes (LMP), and endothelia (EMP) have been well-documented for their roles in hemostasis, thrombosis and inflammation but the clinical significance of RMP is less well understood. The purpose of this study is to study the relation of elevated RMP to selected hematologic and thrombotic disorders. Methods. This is a retrospective study on RMP profiles for patients referred to University of Miami Hospital and Clinics for hematologic consultation over the last 8 years. The patient population includes 51 hemolytic anemia (HA), 459 thrombocytopenia (TP), 26 myeloproliferative disorder (MPD), 413 hypercoagulable state (HCS), and 446 thrombotic disorders (TBS). Some patients were analyzed in more than one of the above disorders. Levels of RMP were measured by flow cytometry with PE-conjugated anti-CD235a labeling as previously described [Thromb. & Haemost., 2013;110:751-60]. Levels of RMP above mean +2SD of controls (> 2,000 counts/mL) are designated as "elevated RMP". Results. (I) Prevalence of elevated RMP in patient populartion: Elevated RMP were found in 31 of 51 HA (60.8%), 138 of 459 TP (30.1%), 20 of 26 MPD (78.1%), 175 of 413 HCS (42.4%), and 251 of 446 TBS (56.3%). (II) Association of elevated RMP with thrombosis: Of 31 HA patients with elevated RMP, 11 were positive for TBS, and the remaining 20 were negative. Levels of RMP (mean ±SD) for TBS(+) and TBS(-) were 5,824 ±3713 and 3,265 ±1,048, counts /mL, respectively (p<0.01). Of 138 TP patients with elevated RMP, 31 were TBS(+) and 107 were TBS(-). Levels of RMP for TBS(+) and TBS(-) were 4,698 ±3,208 and 3,012 ±1,503, counts/mL, respectively (p <0.001). (III) RMP in HCS: Of 175 HCS with elevated RMP, 116 were TBS(+) and 59 were TBS(-). The levels of RMP for TBS(+) and TBS(-) were 4,062 ±3,285 and 2,987 ±1,454, counts/mL, respectively (p <0.02). Among these 116 TBS(+) patients, 22 did not receive antithrombotic treatment at the time of assay (HCS-1), 84 received treatment at time of assay (HCS-2), and 10 developed recurrent TBS despite therapy (HCS-3). Levels of RMP for HCS-1, HCS-2, and HCS-3 were 5,091 ±3,804, 3,973 ±3,044, and 6,191 ±3,763, respectively. Of these, HCS-2 differed significantly from HCS-3, p < 0.05. (IV) TBS with vs. without risk factors: Of 251 TBS with elevated RMP, 226 had known hematological or coagulation disorders, or risk factors for TBS (such as HA, TP, MPD, thrombocytosis, cancers, atrial fibrillation, APS, lupus, or markers for HCS). The remaining 25 without risk factors nevertheless had TBS and elevated RMP, suggesting RMP may be a useful biomarker for thrombotic risk. Discussion. (i) The cause of RMP elevation in HA is reasonably attributed to red cell destruction. The cause in TP/ITP is likely due to products of platelet destruction or leukocyte activation. The cause in MPD could result from clearance of the high burden of red cells and platelets. (ii) Patients who were TBS(+) had higher RMP than TBS(-), seen in HCS, HA, TP, raising the question of whether high RMP is a cause or consequence of TBS. To answer this will require further study. (iii) The finding of exceptionally high RMP levels in recurrent TBS vs. non-recurrent TBS (HCS-3 vs. HC-2) indicates that RMP levels reflect severity of TBS. (iv) Finally, these data indicate that RMP may be a useful biomarker of thrombotic risk, particularly because some TBS patients had elevated RMP, yet tested negative by all conventional markers of HCS workups. Disclosures No relevant conflicts of interest to declare.

Download Full-text

Procoagulant Profile of Platelets from Immune Thrombocytopenia Patients

Blood ◽

10.1182/blood.v128.22.1370.1370 ◽

2016 ◽

Vol 128 (22) ◽

pp. 1370-1370

Author(s):

María Teresa Álvarez Román ◽

Raul Justo Sanz ◽

Elena Monzon Manzano ◽

Monica Martín Salces ◽

Ihosvany Fernandez Bello ◽

...

Keyword(s):

Flow Cytometry ◽

Platelet Count ◽

Immune Thrombocytopenia ◽

Conflicts Of Interest ◽

Annexin V ◽

Compensatory Mechanism ◽

Healthy Controls ◽

Hepes Buffer ◽

Prothrombinase Complex ◽

Fibrinogen Receptor

Abstract Introduction: Immune thrombocytopenia (ITP) is an autoimmune disorder in which both increased platelet destruction and insufficient platelet production are involved. Patients can have a range of bleeding manifestations from none to severe at a similar platelet count. In some cases, patients have fewer bleeding symptoms than expected considering the low platelet count that they might have. Objective: The aim of this study was to determine the procoagulant profile of platelets from ITP patients in order to determine whether any of their features may explain this observation. Methods: Twenty-five patients with chronic ITP [(68±100)x109 platelets/L, mean age: 59.6 ± 16.1 years old, 56% female)] and thirty-five healthy controls [(256±36)x109 platelets/L, mean age: 41.6 ± 13.5 years old, 51% female) were included. Platelet counts were determined with a Coulter Ac. T Diff cell counter (Beckman Coulter, Madrid, Spain). Citrated blood was centrifuged at 152 g 10 min at 23°C for obtaining platelet rich plasma (PRP). To obtain washed platelets, the top two-thirds volumes of PRP were collected and centrifuged (650 g for 10 min at 23°C) after the addition of acid-citrate-dextrose (ACD, 1:10) and the pellet was resuspended in an equal volume of HEPES buffer. Platelet activation was determined by flow cytometry through binding of FITC-PAC1 (a mAb that recognizes activated conformation of fibrinogen receptor) to quiescent and 100 micromol/L thrombin receptor-activating peptide 6 (TRAP, Bachem, Switzerland) or 20 micromol/L ADP. Apoptosis was determined by flow cytometry analysis through FITC-annexin V binding to phosphatidylserine (PS) exposed on platelet membrane under basal conditions. To characterize platelet ability to bind coagulation factors, washed platelets (1x108/mL) were activated with 100 micromol/L TRAP and then incubated with FVa and/or FXa (5nM each, 10 min, ambient temperature). After fixation with 2% paraformaldehyde to cross-link the platelet-bound factors Va and Xa, platelets were washed two times with Hepes Buffer. Non-specific binding sites were blocked with 8% bovine serum albumin (30 min, room temperature). Following centrifugation, platelets were first incubated with anti-CD41-PE, anti-FVa and/or anti-FXa and then with a secondary FITC-goat anti-mouse IgG and stored at 4°C until flow cytometry analyses. Results: Platelets from ITP patients showed a basal expression of activated fibrinogen receptor similar to controls and a reduced ability for being activated by agonists (% of positive platelets for TRAP-induced PAC1 binding: 60±20 % in controls and 35±23 % in ITP, p<0.01; ADP-induced PAC1 binding: 63±14 % in controls and 50±23 % in ITP, p<0.05). Diminished responses to activation were not due to a reduction in surface expression of fibrinogen receptor in platelets from ITP patients. Platelets from ITP patients expressed more PS than controls under basal conditions [mean fluorescence (MF) for FITC-annexin V binding was: 336±128 in controls, 588±25 in ITP, p<0.05]. Since the PS is the anchor site of the prothrombinase complex, we studied the binding of FVa and FXa at baseline and after activating platelets with TRAP. The binding of these factors in both conditions was higher in the group of patients with ITP (MF for basal FVa binding: 41.4±14.4 in controls, 58.1±24 in ITP, p <0.02; MF for TRAP-induced FVa binding: 44.1±11.4 in controls, 81.4±38 in ITP, p<0.001; MF for basal FXa binding: 45.7±18.4 in controls, 58.1±24 in ITP, p <0.005; MF for TRAP-induced FXa binding: 46.1±16.4 in controls, 72.0±24 in ITP, p<0.05). The lower the platelet count the higher increase in PS exposure (Spearman r =-0,518, p <0.001) and the union of FVa (Spearman r = -0.8571, p <0.001) and FXa (Spearman r = -0.7455, p<0.05). Conclusions: Platelets from ITP patients, despite having less capacity of activation by agonist stimulation, have an increased procoagulant surface with greater ability to bind prothrombinase complex (FXaVa) than those from healthy controls. This feature might be a procoagulant compensatory mechanism that could reduce the risk of bleeding in patients with ITP. This work was supported by a grants from the FIS-FEDER, PI12/01831 and PI15/01457 Disclosures No relevant conflicts of interest to declare.

Download Full-text

Pierwotna małopłytkowość immunologiczna u dzieci

Nowa Pediatria ◽

10.25121/np.2018.22.4.122 ◽

2018 ◽

Vol 22 (4) ◽

Author(s):

Anna Dusza ◽

Michał Matysiak

Keyword(s):

Immune Thrombocytopenia ◽

Clinical Symptoms ◽

Pediatric Population ◽

Current Data ◽

Current Investigation ◽

Surgical Interventions ◽

Hematological Disorders ◽

Primary Immune Thrombocytopenia

In this article we present current investigation on primary immune thrombocytopenia in children. There are described pathomorphology, clinical symptoms, diagnosis and treatment. We also present current data from literature about genetic tests and latest data on treating options in children. Primary immune thrombocytopenia (ITP) is one of the most frequent hematological disorders in pediatric population. Although the majority of children have a self-limited and short duration of the disease. However, approximately 20-30% of those patients can develop chronic ITP, which can cause significant complications and higher mortality and reduced quality of life. Especially regarding to long-term immunosupression or surgical interventions, such like splenectomy and restrictions on daily activities to avoid trauma. Over the past decades a lot of informations has been reported about pathogenic features of ITP. Nowdays, we know that it is not only caused by increased platet destruction and decreased platet production, but also complex, multifactorial immune dysregulation, like loss of immune tolerance and generation of platelet autoantibodies. In this article we present current investigation on ITP including clinical symptoms, diagnosis, pathomorphology and latests options on treatment in children. We also present current data about genetic biomarker, such as Vanin-1 (VNN-1) which has been suggested as one of predictors of chronic disease and potentially can offer early prognosis estimation.

Download Full-text

PS01.103: THE UNUSUAL CAUSES OF ODYNOPHAGIA

Diseases of the Esophagus ◽

10.1093/dote/doy089.ps01.103 ◽

2018 ◽

Vol 31 (Supplement_1) ◽

pp. 78-78 ◽

Cited By ~ 1

Author(s):

Kheng Tian Lim

Keyword(s):

Complete Resolution ◽

Conflicts Of Interest ◽

Fish Bone ◽

Esophageal Injury ◽

Mediastinal Infection ◽

Inflammatory Processes ◽

History Of ◽

Fish Ingestion ◽

The Right ◽

Esophageal Ulcers

Abstract Background Odynophagia can be caused by infective and non-infective inflammatory processes, benign and malignant esophageal disorders such as achalasia, gastro-esophageal reflux disease and carcinoma. Methods We described two unusual cases of odynophagia and their individual management. Results Case 1 is a 21 year-old Indian man presented with 2 days history of odynophagia after taking doxycycline capsules indicated for acne. An esophagogastroduodenoscopy (OGD) was performed and showed multiple mid esophageal ulcers. Esophageal biopsy taken showed inflammatory ulcer slough with no fungal infection, dysplasia or malignancy. Doxycycline was stopped and patient recovered with complete resolution of odynophagia. Case 2 is a 55 year-old Chinese man presented with 1 day history of odynophagia and severe chest pain after eating a bowl of hot fish soup. A CT Thorax was performed which showed a localised perforation of the right wall of the esophagus with extraluminal gas posterior to the trachea. An urgent OGD was performed and an L-shaped fish bone was removed successfully and an endoclip was applied to close the puncture hole of esophagus. Patient made a full recovery without any mediastinal infection. Conclusion Odynophagia from mid esophageal ulcers secondary to doxycycline intake should be recognized and can be easily managed by stopping the antibiotics with complete resolution of the symptom. Fish ingestion leading to sharp bone induced penetrating esophageal injury can be safely managed by endoscopic removal and endoclip application. Disclosure All authors have declared no conflicts of interest.

Download Full-text

Bile Acids Induce Platelet Activation Leading to Degranulation and a Prothrombotic Phenotype

Blood ◽

10.1182/blood-2019-126095 ◽

2019 ◽

Vol 134 (Supplement_1) ◽

pp. 4887-4887

Author(s):

Joachim Zobel ◽

Tanja Strini ◽

Martin Tischitz ◽

Sina Pohl ◽

Theresa Greimel ◽

...

Keyword(s):

Liver Fibrosis ◽

Bile Acids ◽

Conflicts Of Interest ◽

Annexin V ◽

Farnesoid X Receptor ◽

Fibrinogen Binding ◽

Model Study ◽

Serine Protease Activity ◽

Adult Volunteers ◽

Dose Dependent

Background: Previous articles have identified the farnesoid X receptor (FXR) as an integral part in the formation of coated platelets. Coated platelets are preactivated platelets featuring degranulation, increased fibrinogen binding, and increased serine protease activity leading to fibrin generation. Furthermore, phosphatidylserine exposure is increased and integrin α2bβIII is inhibited - leading to a prothrombotic phenotype despite decreased platelet aggregation. We hypothesize that bile acids, as natural ligands of FXR, lead to a change of platelet phenotype and therefore play a pivotal role in the formation of coated platelets, especially in presence of cholestasis. Methods: Based on previous findings, we incubated human washed platelets of healthy adult volunteers with the synthetic FXR ligand GW4064 in various concentrations (0, 10, 20, 50, 100µM) and used flow cytometry to detect a shift in p-selectin expression, PAC-1 binding and annexin-V-binding. Moreover, we used different concentrations (0, 100, 200, 400, 600µM) of three bile acids (ursodeoxycholic acid, UDCA; chenodeoxycholic acid, CDCA; glycochenodeoxycholic acid, GCDCA) to see if natural FXR ligands induce an effect on the platelet phenotype. Results: We observed a dose dependent shift in annexin-V-binding when treating washed platelets with GW4064 as well as CDCA and GCDCA. Similarly, GW4064 led to increased p-selectin expression while increased PAC-1-binding was only detected at the highest concentration. In contrast, CDCA and GCDCA showed merely slight changes in p-selectin expression whereas PAC-1-binding seemed to be unaffected. However, none of these effects were seen when using UDCA. Conclusion: We conclude that pretreatment of washed platelets with CDCA and GCDCA initiate a dose-dependent shift towards a prothrombotic platelet phenotype. Therefore, we assume that increased levels of certain bile acids drive thrombosis in patients with cholestatic liver injury. Furthermore, a recent mouse model study suggested that platelet derived growth factor β (PDGFβ), a component of α-granula, drives liver fibrosis. Hence, in addition to their prothrombotic effects, coated platelets might exacerbate liver fibrosis. Disclosures No relevant conflicts of interest to declare.

Download Full-text

Cross-Reactivity of Drug-Dependent Antibodies in Patients with Immune Thrombocytopenia Induced By Beta-Lactam Antibiotics

Blood ◽

10.1182/blood-2019-131375 ◽

2019 ◽

Vol 134 (Supplement_1) ◽

pp. 2350-2350

Author(s):

Matthew John Slaught ◽

Daniel W. Bougie ◽

Richard H. Aster

Keyword(s):

Bacterial Infections ◽

Immune Thrombocytopenia ◽

Conflicts Of Interest ◽

Cross Reactivity ◽

Beta Lactam ◽

Cross Reactions ◽

Beta Lactam Antibiotics ◽

Wide Range ◽

Group 2 ◽

Group 1

More than 50 beta lactam (BL) antibiotics are now in active use for treatment of a wide range of bacterial infections. BL antibiotics are among the most common drugs capable of inducing antibodies (DDAbs) that cause drug-induced immune thrombocytopenia (DITP). Most DDAbs are highly specific for the sensitizing drug but beta lactams all have a common core structure and many similarities among side groups that are added to augment potency and modify specificity, raising the possibility that a DDAb specific for one BL may cross-react with another. We studied DDAbs from 33 patients with DITP induced by 9 commonly used BL drugs to determine whether patterns of cross-reactivity exist that might influence the choice of an alternative antibiotic in a patient with BL-induced DITP. DDAbs were demonstrated in a flow cytometric assay considered to be "positive" when immunoglobulins in patient serum but not normal serum react with normal platelets in the presence, but not in the absence of drug (Blood 2018;131:1486). DDAbs detected in the 33 patients were specific for 9 different BL drugs that were divided into two groups, "penicillins" (Group 1) and cephalosporins (Group 2) on the basis of structural similarities (Figure 1). In Group 1 were 19 DDAbs specific for amoxicillin (2), nafcillin (4) and piperacillin (13). Structurally similar ampicillin and penicillin were also tested with these abs. In Group 2 were 14 DDAbs specific for cefadroxil (1), cefepime (2), ceftazidime (2), ceftizoxime (1), ceftriaxone (7) and cephalexin 1). Cross-reactions identified within these groups of DDAbs are shown in Tables 1 and 2. Cross-reactions, many quite strong (S) were observed among DDAbs specific for drugs in both structural groups (Tables 1 and 2). Particularly noteworthy were cross-reactions of the 19 Group 1 DDAbs with ampicillin (6) and penicillin (6) (Table 1) and of the 14 Group 2 DDAbs with cefepime (6), ceftizoxazole (6) and ceftriaxone (3) (Table 2). The findings show that platelet-specific DDAbs induced by beta lactam antibiotics, in contrast with those induced by medications like quinine, sulfamethoxazole and vancomycin, commonly cross-react with other antibiotics of this class. In patients with immune thrombocytopenia induced by a beta lactam antibiotic, it may be prudent to avoid switching to another beta lactam or, if this is necessary, to monitor platelet counts carefully. Disclosures No relevant conflicts of interest to declare.

Download Full-text

Leukocyte activation receptor CD69 and ligands: Immunoregulatory role in inflammatory processes

Toxicology Letters ◽

10.1016/j.toxlet.2016.07.087 ◽

2016 ◽

Vol 259 ◽

pp. S19 ◽

Cited By ~ 1

Author(s):

H. De la Fuente ◽

V. Cibrian ◽

F. Sanchez-Madrid

Keyword(s):

Leukocyte Activation ◽

Inflammatory Processes

Download Full-text

Regulating Conflicts of Interest in Medicine Through Public Disclosure: Evidence from a Physician Payments Sunshine Law

Management Science ◽

10.1287/mnsc.2020.3940 ◽

2021 ◽

Author(s):

Matthew Chao ◽

Ian Larkin

Keyword(s):

Conflicts Of Interest ◽

Healthcare Management ◽

Public Disclosure ◽

Brand Name ◽

Data Set ◽

Pharmaceutical Firms ◽

Drug Classes ◽

Healthcare Administrators ◽

The Many ◽

Brand Name Drugs

Hospital and healthcare administrators name high prescription drug costs as one of their largest problems. A significant body of research demonstrates that meals and honoraria from pharmaceutical firms to physicians leads to higher prescribing of expensive, brand name drugs, despite little difference in efficacy. Some administrators and scholars have advocated for mandatory disclosure of these payments in order to reduce this conflict of interest, but many practitioners believe disclosure has little effect on prescribing, and the empirical evidence is mixed. This paper uses a quasi-experiment of a 2009 payment disclosure policy in Massachusetts to estimate the causal impact of public disclosure on prescribing. The comprehensive data set includes all retail prescriptions for 262 drugs in nine drug classes written by 5,730 physicians in five states over 48 months. We show a significant postdisclosure reduction in brand name drug prescriptions by Massachusetts physicians, relative to control physicians in other states. These effects are driven by heavy prescribers of brand name drugs in the prepolicy period, particularly for drugs with large prepolicy sales forces. Effects are also detected before the first data were released, implying that the effects are not because patients or administrators responded to the disclosed payments. Instead, some physicians may have changed their payments and prescriptions behavior to avoid appearing biased. Taken in tandem with the many studies showing that pharmaceutical industry payments influence prescribing, this study suggests a strong role for mandatory public disclosure in reducing conflicts of interest in medicine and costly prescribing of brand name drugs. This paper was accepted by Stefan Scholtes, healthcare management.

Download Full-text