Intravascular Hemolysis In Patients Research Articles

Identification of potent siRNA targeting complement C5 and its robust activity in pre-clinical models of myasthenia gravis and collagen-induced arthritis

Complement component 5 (C5), an important molecule in the complement cascade, blockade by antibodies shows clinical efficacy in treating complement-mediated disorders. However, insufficient blockading induced by single-nucleotide polymorphisms in the C5 protein or frequent development of "breakthrough" intravascular hemolysis in patients with paroxysmal nocturnal hemoglobinuria treated with eculizumab have been reported. Herein, we developed a lipid nanoparticle (LNP)-formulated siRNA targeting C5 that was efficiently delivered to the liver and silenced C5 expression. We identified a potent C5-siRNA with an invitro IC50 of 420 pM and invivo ED50 of 0.017mg/kg following a single administration. Single or repeated administrations of the LNP-formulated C5-siRNA allowed robust and durable suppression of liver C5 expression in mice. Complement C5 silencing ameliorated C5b-dependent anti-acetylcholine receptor antibody-induced myasthenia gravis and C5a-dependent collagen-induced arthritis symptoms. Similarly, in nonhuman primates, a single administration of C5-siRNA/LNP-induced dose-dependent plasma C5 suppression and concomitantly inhibited serum complement activity; complement activity recovered to the pre-treatment levels at 65days post administration, thus indicating that the complement activity can be controlled for a specific period. Our findings provide the foundation for further developing C5-siRNA delivered via LNPs as a potential therapeutic for complement-mediated diseases.

Tissue plasminogen activator in left ventricular assist device-related intravascular hemolysis after failed augmented anticoagulation.

We sought to examine the efficacy and safety of adding fibrinogen-guided low-dose multi-day Alteplase™ tissue plasminogen activator (tPA) in the management of intravascular hemolysis (IVH) in patients with the HeartMate II (HM-II) continuous flow (CF) left ventricular assist device (LVAD) who failed to achieve IVH resolution with conventional augmented anticoagulation (AAC). IVH in patients with LVAD is often treated with AAC, failing which pump exchange is considered. We hypothesized that a trial of low-dose tPA after failed AAC therapy could resolve IVH and prevent pump exchange in some patients. We performed a retrospective study of 31 HM-II CF LVAD patients admitted to our center from January 2015 to January 2020 for IVH management who received tPA following failed AAC. Primary 6-month outcomes included successful IVH resolution, unsuccessful IVH resolution requiring pump exchange, gastrointestinal bleeding, ischemic and hemorrhagic cerebrovascular accident (CVA), and death. Thirty-one patients with IVH were treated with tPA following failed AAC. Successful resolution of IVH occurred in 22/31 (71%) patients. Pump exchange occurred in 9/31 (29%) patients. Gastrointestinal bleeding occurred in 7/31 (22.6%) patients. Ischemic CVA occurred in 6/31 (19.4%) patients. Management of IVH with administration of low-dose tPA after failed AAC is feasible and may prevent pump exchange in some patients.

Pozelimab, a Human Monoclonal Antibody Against Complement Factor C5, Provided Inhibition of Intravascular Hemolysis in Patients with Paroxysmal Nocturnal Hemoglobinuria

INTRODUCTIONParoxysmal Nocturnal hemoglobuinuria (PNH) is a rare, acquired, life-threatening disorder characterised by intravascular hemolysis and increased risk of thrombosis. Current available treatments represent a significant burden to patients and include anti-complement factor 5 (C5) therapies, eculizumab and ravulizumab, both intravenous infusions, or more recently, twice weekly C3 inhibitor, Pegcetacoplan, a subcutaneous (SC) infusion treatment.Pozelimab (REGN3918), a fully human monoclonal immunoglobulin G4 antibody directed against C5, has been shown to bind with high affinity to wild-type and variant (R885H/C) human C5 and block its activity.In a healthy volunteer study (NCT03115996), SC administration of pozelimab was found to be generally well tolerated while providing complete inhibition of ex vivo-assessed hemolytic activity [Weyne J et al. Blood. 2018;S1:1039]. The data suggested that pozelimab may provide control of intravascular hemolysis in patients with active PNH, and thus could provide an important new alternative for patients supporting progression to a first-in-patient study of pozelimab in patients with active PNH.OBJECTIVETo demonstrate a clinically significant reduction in intravascular hemolysis by once-weekly SC administration of pozelimab over 26 weeks of treatment in patients with active PNH.METHODSThis is a phase 2, open-label, single-arm, 26-week treatment study in 24 patients with active symptomatic PNH who are naïve to complement inhibitor therapy, or who have received prior treatment with a complement inhibitor but not within 6 months prior to the start of the study (NCT03946748).The treatment regimen consists of pozelimab as a single IV loading dose of 30 mg/kg followed thereafter by weekly SC 800 mg administrations.The effect of pozelimab on intravascular hemolysis (monitored via LDH levels) and transfusion avoidance, as well as safety, is to be assessed from baseline to week 26 (study day 183; only partial data were available for some patients at the time of abstract submission). Pozelimab pharmacodynamics was assessed utilizing a sheep red blood cell (RBC) complement activity assay (CH50) and rabbit RBC complement activity assay (AH50).RESULTSAll 24 patients completed the 26-week treatment period with no study drug discontinuation and have been enrolled into an ongoing open-label extension study (NCT04162470). An interim analysis on the first 17 patients was previously reported. All 17 patients had at least 71 days of treatment, with 10 patients receiving treatment for up to 183 days. All enrolled patients had baseline LDH levels ≥2 x upper limit of normal (ULN). Participants were enrolled in two cohorts: Cohort A for dose confirmation and Cohort B for further evaluation of efficacy and safety.Interim Efficacy AnalysisAs previously reported, treatment with pozelimab led to a rapid and sustained reduction in LDH through study week 26. All 17 patients achieved LDH reduction to below the clinically significant threshold of LDH ≤1.5 x ULN.All but one patient achieved control of intravascular hemolysis (LDH ≤1.5 x ULN) at week 2, and all but one patient achieved normalization of LDH (LDH ≤1.0 x ULN) at week 4.Importantly, one patient who is a carrier of a C5 variant known to be resistant to blockade by eculizumab/ravulizumab demonstrated rapid and sustained normalization of LDH.Interim SafetyAs previously reported, no serious adverse events or adverse events leading to treatment discontinuation were reported. Common treatment-emergent adverse events included headache (4 patients; 23.5%) and nausea (2 patients; 11.8%).No breakthrough hemolysis events were observed.CONCLUSIONSPozelimab administered SC once weekly led to the inhibition of intravascular hemolysis in patients with active PNH and was generally well-tolerated. An update to the previously reported interim analysis will be provided.Upon successful completion of the 26-week treatment period, patients are enrolled into an open-label extension study. DisclosuresWeyne: Regeneron Pharmaceuticals, Inc.: Current Employment, Current holder of stock options in a privately-held company. Chaudhari: Regeneron Pharmaceuticals, Inc.: Current Employment, Current holder of stock options in a privately-held company. Harari: Regeneron Pharmaceuticals, Inc.: Current Employment, Current holder of stock options in a privately-held company. Miller: Regeneron Pharmaceuticals, Inc.: Current Employment, Current holder of stock options in a privately-held company. Dain: Regeneron Pharmaceuticals, Inc.: Other: Contractor. Meagher: Regeneron Pharmaceuticals, Inc.: Current Employment, Current holder of stock options in a privately-held company. Rodgers: Regeneron Pharmaceuticals, Inc.: Current Employment, Current holder of stock options in a privately-held company. Perlee: Regeneron Pharmaceuticals, Inc.: Current Employment, Current holder of stock options in a privately-held company. Morton: Regeneron Pharmaceuticals, Inc.: Current Employment, Current holder of stock options in a privately-held company. Weinreich: Regeneron Pharmaceuticals, Inc.: Current Employment, Current holder of stock options in a privately-held company. Yancopoulos: Regeneron Pharmaceuticals, Inc.: Current Employment, Current holder of stock options in a privately-held company. Griffin: Alexion, AstraZeneca Rare Disease: Honoraria, Membership on an entity's Board of Directors or advisory committees; BioCryst Pharmaceuticals: Consultancy, Membership on an entity's Board of Directors or advisory committees; Sobi Pharmaceuticals: Honoraria, Membership on an entity's Board of Directors or advisory committees; Apellis: Other: Educational grant support.

Predictors for Improvement in Patient-Reported Outcomes: Post-Hoc Analysis of a Phase 3 Randomized, Open-Label Study of Eculizumab and Ravulizumab in Complement Inhibitor-Naïve Patients with Paroxysmal Nocturnal Hemoglobinuria (PNH)

Predictors for Improvement in Patient-Reported Outcomes: Post-Hoc Analysis of a Phase 3 Randomized, Open-Label Study of Eculizumab and Ravulizumab in Complement Inhibitor-Naïve Patients with Paroxysmal Nocturnal Hemoglobinuria (PNH)

Activation of Pyruvate Kinase-R with Etavopivat (FT-4202) Is Well Tolerated, Improves Anemia, and Decreases Intravascular Hemolysis in Patients with Sickle Cell Disease Treated for up to 12 Weeks

Activation of Pyruvate Kinase-R with Etavopivat (FT-4202) Is Well Tolerated, Improves Anemia, and Decreases Intravascular Hemolysis in Patients with Sickle Cell Disease Treated for up to 12 Weeks

Extravascular Hemolysis Due to C3-Loading in Patients with PNH Treated with Eculizumab: Defining the Clinical Syndrome

IntroductionComplement-mediated intravascular hemolysis in patients with paroxysmal nocturnal hemoglobinuria (PNH) is effectively prevented by the terminal-complement inhibitor eculizumab, reducing symptoms and protecting against the clinical consequences of the disease, such as thrombosis and renal failure. Due to the continued activation of the proximal complement cascade upstream of C5, PNH red cells become opsonized with fragments of C3, leading to extravascular hemolysis and a continued transfusion requirement in a proportion of patients. Lactate dehydrogenase (LDH) is utilised as the main indicator of hemolysis in PNH but is particularly a measure of intravascular rather than extravascular hemolysis and therefore is not necessarily elevated in proportion to transfusion requirement due to C3-loading. We therefore conducted data analysis to determine whether other parameters were more indicative of extravascular hemolysis.MethodsData from patients with PNH treated in the Leeds centre of the UK PNH National Service was reviewed retrospectively. Criteria for inclusion in the analysis were treatment with eculizumab for ≥13 months, a mean platelet count >50 x 109/L and mean absolute neutrophil count >0.5 x 109/L (to exclude patients with significant bone marrow failure). Mean values for hemoglobin, absolute reticulocyte count, LDH (adjusted for upper limit of normal), total bilirubin and the proportion of PNH red cells loaded with C3 were collated covering a 48-month period. C3 loading of red cells was assessed by flow cytometry (Sutherland et al., Curr Protoc Cytom. 2015). Red cell transfusion requirements for the latest 12 months and latest eculizumab dosage were also collected.ResultsOne hundred and forty-one patients were identified for inclusion by the above criteria; 70 males and 71 females. The median hemoglobin level for all patients was 109g/l. Seventy-two percent had a mean hemoglobin below 120g/l despite treatment with eculizumab and all patients had variable amounts of C3 on their red cells demonstrating that some degree of extravascular hemolysis is always seen. During the latest 12 months, 51 (36%) patients received at least one transfusion, with 23 (16%) requiring 3 or more transfusions. Thirty (21%) patients were receiving a higher dose of eculizumab (1200mg or more every 2 weeks) due to either sub-therapeutic eculizumab levels and/or measureable terminal complement levels, assessed by the CH50, at the standard dose of 900mg every two weeks.Patients were stratified by both reticulocyte count and LDH and the means for each parameter calculated as shown in Table 1. Bilirubin, C3 loading, transfusion requirement and requirement for an increased dose of eculizumab all correlated better when stratifying by reticulocytes rather than by LDH.When patients were scored on the severity of C3 loading, bilirubin values and reticulocyte count, those with the worst (highest) joint scores were 3 times more likely to be transfused. 72/141 (51%) patients had all three of the following: reticulocyte count <230 x 109/l, bilirubin <30umol/l and less than 30% of their PNH red cells staining for C3. 55 of these 72 (76%) were not transfused in the last 12 months. In contrast 9 patients had reticulocytes >230, bilirubin ≥30 and C3-loading ≥30% and 7 of these 9 continued to require transfusions.ConclusionReticulocyte count appears to be a better indicator of extravascular hemolysis than LDH, correlating more strongly with raised bilirubin, increased C3 loading of PNH red cells and increased transfusion requirement. Using these parameters patients who are more likely to continue to require transfusion support on eculizumab can be identified. Such an approach may be used to identify patients who are more likely to benefit from inhibition of the complement cascade that could reduce the level of C3-associated extravascular hemolysis. [Display omitted] DisclosuresRichards:Alexion Pharmaceuticals, Inc.: Honoraria. Munir:Alexion Pharmaceuticals, Inc.: Honoraria; Gilled: Honoraria; AbbVie: Honoraria; Janssen: Honoraria; Roche: Honoraria. Griffin:Alexion Pharmaceuticals, Inc.: Honoraria. Arnold:Alexion Pharmaceuticals, Inc.: Honoraria. Hill:Alexion Pharmaceuticals, Inc.: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees. Hillmen:Roche: Consultancy, Honoraria, Research Funding; Celgene: Research Funding; Alexion Pharmaceuticals, Inc.: Consultancy, Honoraria; Pharmacyclics LLC, an AbbVie Company: Honoraria, Research Funding; Novartis: Honoraria, Research Funding; Gilead: Consultancy, Honoraria, Research Funding; AbbVie: Consultancy, Honoraria, Research Funding; GSK: Consultancy, Honoraria, Research Funding; Janssen: Consultancy, Honoraria, Research Funding.

Hemolysis in patients with Extracorporeal Membrane Oxygenation therapy for severe Acute Respiratory Distress Syndrome - a systematic review of the literature.

The Acute Respiratory Distress Syndrome (ARDS) is common in patients on the Intensive Care Unit and associated with significant mortality rates. In situations of severe respiratory insufficiency and failure of all possible conservative therapeutic approaches, veno-venous extracorporeal membrane oxygenation (VV ECMO) is used as a final option for temporary replacement of pulmonary function. ARDS as well as sepsis and VV ECMO treatment are all associated with intravascular hemolysis. The extent and relevance of intravascular hemolysis in the context of ARDS therapy is unclear. This systematic review aims to summarize the current evidence on the incidence and associated complications of intravascular hemolysis in adult patients with ARDS and treatment with VV ECMO. The databases MEDLINE, EMBASE and Web of Science were systematically searched and 19 publications fulfilled inclusion criteria. The incidence of hemolysis in patients with ARDS and treatment with VV ECMO ranged from 0 to 41% with survivors showing lower incidences and less severe hemolysis. A pump head thrombosis and high blood flows (≥3 l/min) as well as use of dual-lumen cannulas but not different pump models were associated with increased hemolysis. In conclusion, intravascular hemolysis in patients with ARDS and treatment with VV ECMO is a common and relevant complication that appears associated with increased mortality. Apart from ECMO hardware-settings, no additional possible causes for increased red cell breakdown such as disease severity, duration of ECMO therapy, or number and quality of red blood cell transfusions were investigated. Further research is needed to determine the origin and relevance of intravascular hemolysis in patients with ARDS and treatment with VV ECMO.

Preclinical Characterization of BCX9930, a Potent Oral Complement Factor D Inhibitor, Targeting Alternative Pathway-Mediated Diseases Including Paroxysmal Nocturnal Hemoglobinuria (PNH)

INTRODUCTION: Complement factor D is a serine protease that specifically catalyzes the cleavage of factor B [bound to C3(H2O) or C3b], its only natural substrate, to Ba and Bb. Factor D has the lowest concentration in plasma among all the complement proteins and is the rate-limiting enzyme of the alternative pathway (AP) of complement. Factor D plays a key role in both AP-initiated C3 convertase formation and the amplification loop of the complement cascade. Therefore, targeting factor D is a promising therapeutic strategy to inhibit AP activation for treatment of AP-mediated diseases such as PNH, atypical hemolytic uremic syndrome, and C3 glomerulopathy. Inhibition of terminal complement C5 by eculizumab or ravulizumab results in sustained inhibition of intravascular hemolysis in patients with PNH by blocking formation of the membrane attack complex (C5b-9). However, many PNH patients treated with eculizumab continue to have symptomatic anemia, with up to half of the patients requiring blood transfusions due to extravascular hemolysis as a result of ongoing AP activation and C3 opsonization on erythrocytes. BioCryst Pharmaceuticals has developed a small-molecule, orally bioavailable human factor D inhibitor that is currently under evaluation as oral monotherapy for the treatment of patients with PNH in a Phase 1 study (BCX9930-101; NCT04330534). Here we demonstrate that BCX9930 is a potent and highly selective factor D inhibitor, and completely blocked AP activation on PNH erythrocytes in vitro. METHODS: Factor D enzymatic activity was analyzed in vitro in an esterolytic assay with a synthetic substrate and in a proteolytic assay using its natural substrate factor B bound to C3b. The selectivity was assessed in substrate-specific assays using other human serine proteases. The inhibition of AP-mediated hemolysis was assessed in vitro with rabbit erythrocytes incubated with 10% normal human serum (NHS). The Ham test was used to evaluate the inhibition by BCX9930 of AP-mediated hemolysis of erythrocytes from PNH patients with 20% acidified NHS. Inhibition of AP-mediated C3 fragment deposition was evaluated by flow cytometry using PNH erythrocytes incubated with acidified C5-depleted NHS. Activity of the classical pathway (CP) of complement l was evaluated by measuring 50% Hemolytic Complement (CH50) activity of serum and by assay of CP-mediated hemolysis of antibody-sensitized sheep erythrocytes. Pharmacodynamic effects in rhesus monkeys dosed orally with BCX9930 (100 and 200 mg twice-a-day) were assessed ex vivo with the AP Wieslab assay for the determination of C5b-9 generation after AP activation. RESULTS: BCX9930 potently inhibited esterolytic activity of purified human factor D with a mean 50% inhibitory concentration (IC50) of 14.3 nM. BCX9930 also inhibited its proteolytic activity against factor B bound to C3b with a mean IC50 of 28.1 nM. BCX9930 inhibited AP-mediated hemolysis of rabbit erythrocytes with a mean IC50 of 29.5 nM. Using the Ham test with erythrocytes from three PNH patients, BCX9930 completely suppressed AP-mediated hemolysis with a mean IC50 of 35.4 nM. Furthermore, BCX9930 suppressed C3 fragment deposition on PNH erythrocytes with a mean IC50 value of 39.3nM. BCX9930 did not inhibit enzyme activity of the human serine proteases thrombin, activated protein C, tissue plasminogen activator and trypsin up to 28 μM, and activated factor X and activated factor XII up to 50 μM. The mean IC50 values of BCX9930 inhibition of C1s and plasmin were 936 and 2850 nM, respectively. BCX9930 at a concentration up to 3 μM had no effect on CP activity in in vitro assays. Oral dosing of BCX9930 in monkeys completely suppressed AP activity of serum measured by AP-dependent generation of C5b-9. CONCLUSIONS: BCX9930 inhibitory activity on Factor D in vitro was potent and highly specific. BCX9930 completely blocked hemolysis of PNH cells in vitro and suppressed the accumulation of C3 fragments on PNH erythrocytes, indicating that BCX9930 has the potential to inhibit both intravascular and extravascular hemolysis. After oral dosing of BCX9930 in rhesus monkeys, AP activity was completely suppressed in ex vivo assays. These data demonstrate that BCX9930, an orally administered investigational drug, is a potent and selective factor D inhibitor, and that targeting factor D with BCX9930 has potential for the treatment of patients with PNH and other alternative pathway mediated diseases. Disclosures Chen: BioCryst Pharmaceuticals, Inc.: Current Employment. Cheng:BioCryst Pharmaceuticals, Inc.: Current Employment. Liu:BioCryst Pharmaceuticals, Inc.: Current Employment. Muppa:BioCryst Pharmaceuticals, Inc.: Current Employment. Parker:BioCryst Pharmaceuticals, Inc.: Current Employment. Zhu:BioCryst Pharmaceuticals, Inc.: Current Employment. Raman:BioCryst Pharmaceuticals, Inc.: Current Employment. Kotian:BioCryst Pharmaceuticals, Inc.: Current Employment. Babu:BioCryst Pharmaceuticals, Inc.: Current Employment.

Research progress on nitric oxide depletion and its replacement therapy in intravascular hemolytic diseases

In the case of intravascular hemolysis in patients with hemolytic diseases such as paroxysmal nocturnal hemoglobinuria (PNH) and sickle cell disease (SCD), patients′ body can produce a large amount of free hemoglobin (FHb) and release intracellular arginase. FHb can rapidly scavenge nitric oxide (NO) and arginase can degrade L-arginine, which is substrate for NO synthesis. All together with the increased amount of reactive oxygen species (ROS) after hemolysis, NO appears to be depleted in the circulation, which results damages to endothelial and dysfunction of microcirculation, as well as eventually lead to acute and chronic impair to multiple organs. In recent years, with the in-depth study of the mechanisms beneath NO depletion in intravascular hemolytic disorders, the common pathological mechanisms of such diseases have been elucidated, and NO replacement therapy seems to be an all new approach. In view of this, this article reviews the research progress in the field of NO depletion and its replacement therapy in intravascular hemolytic diseases. Key words: Hemolytic disease; Nitric oxide; Depletion; Replacement therapy; Intravascular hemolysis

A suspected case of Clostridium perfringens sepsis with intravascular hemolysis after transhepatic arterial chemoembolization: a case report

IntroductionSepsis due to Clostridium perfringens, one of several clostridial species, is an important cause of massive intravascular hemolysis in patients with underlying malignancies. Chronic liver diseases, immunosuppression, and presence of malignancies were risk factors for Clostridium perfringens sepsis. Therefore, Clostridium perfringens sepsis should always be considered in patients presenting with liver damage after chemo-embolic therapy for hepatocellular carcinoma. This case report focuses on findings characteristic of an intravascular hemolysis due to Clostridium perfringens after transhepatic arterial chemoembolization.Case presentationAn 83-year-old Japanese man presented to our hospital because of a third recurrence of hepatocellular carcinoma. He had nonalcoholic steatohepatitis-related cirrhosis, and underwent radiofrequency ablation and transhepatic arterial chemoembolization therapy for hepatocellular carcinoma of S4/S8 and S2. He had a medical history of pancreatic carcinoma and underwent pylorus-preserving pancreaticoduodenectomy approximately 5 years ago. Because follow-up computed tomography showed a recurrence of the hepatocellular carcinoma, he underwent transhepatic arterial chemoembolization with a hepatic arterial infusion of 20 mg epirubicin, followed by 4 mL Lipiodol (ethiodized oil). On the sixth day after the procedure, he complained of fever and hematuria with jaundice. Laboratory findings indicated hemolysis and increased inflammatory response. Although we initiated antibiotic therapy combined with surgical debridement for infection after transhepatic arterial chemoembolization, he died within 6 hours. The autopsy showed a 4-cm local necrotic hepatic tumor. The cut surface revealed a tumor with an internal spongiform appearance, which was a pseudocystic and partially necrotic lesion. In addition, a diffuse spread of Gram-positive rods in multiple organs including the heart was histologically confirmed. The culture obtained by fluid aspiration from the hepatic abscess revealed Clostridium perfringens. Although the role of Clostridium perfringens was never established during the life of this patient, based on the clinical course and the culture from the hepatic abscess at postmortem, intravascular hemolysis secondary to Clostridium perfringens sepsis was suspected.ConclusionIntravascular hemolysis secondary to Clostridium perfringens should always be considered in patients presenting with liver damage after chemo-embolic therapy for hepatocellular carcinoma. Biliary reconstruction is an especially important risk factor for infection.

Intravascular hemolysis in patients with mitral regurgitation: Evaluation by erythrocyte creatine

BackgroundIntravascular hemolysis has been reported in patients with cardiac valve prostheses, but intravascular hemolysis in patients with mitral regurgitation with native valve has not been evaluated in detail. We designed a study to elucidate the impact of regurgitation flow on intravascular hemolysis in patients with primary mitral regurgitation by measuring erythrocyte creatine. MethodsErythrocyte creatine was enzymatically assayed in 29 patients with moderate to severe primary mitral regurgitation and 12 age-matched healthy volunteers. The size and characteristics of mitral regurgitation were determined by color Doppler echocardiography. ResultsErythrocyte creatine was significantly higher in patients with eccentric jet (n=17, 2.64±0.77μmol/g Hb) than that of central jet (n=12, 1.68±0.13μmol/g Hb) and control subjects (1.39±0.25μmol/g Hb). Patients with eccentric jet had a significantly lower erythrocyte count and hemoglobin (385±58 x104/μL and 116±19g/l) compared to those with central jet (450±47×104/μL and 137±14g/l) and control subjects (433±31×104/μL and 134±19g/l). There were no significant differences in age, estimated glomerular filtration rate, pulmonary artery systolic pressure, left atrial size and left ventricular end-diastolic dimension between patients with eccentric jet and central jet. ConclusionsIntravascular hemolysis associated with subclincal anemia in patients with eccentric jet was due to the destruction of erythrocyte by collision of the eccentric jet to the atrial wall.

Terminal Complement Blockade after Hematopoietic Stem Cell Transplantation Is Safe without Meningococcal Vaccination

Eculizumab inhibits terminal complement-mediated intravascular hemolysis in patients with paroxysmal nocturnal hemoglobinuria and complement-mediated thrombotic microangiopathy (TMA) in patients with atypical hemolytic uremic syndrome and is now used as a first-line therapy in these diseases. Eculizumab is available only through a restricted program under a Risk Evaluation and Mitigation Strategy (REMS) because of an increased risk of meningococcal infections in persons without adequate functional complement. Administration of meningococcal vaccine is required at least 2 weeks before administering the first dose of eculizumab, and this advice is included in the product label. Eculizumab use for treatment of TMA in hematopoietic stem cell transplantation (HSCT) recipients brings a significant dilemma regarding REMS required meningococcal vaccination. TMA after HSCT usually occurs within the first 100 days after transplantation when patients are severely immunocompromised and are not able to mount a response to vaccines. We evaluated 30 HSCT recipients treated with eculizumab for high-risk TMA without meningococcal vaccine. All patients received antimicrobial prophylaxis adequate for Neisseria meningitides during eculizumab therapy and for 8 weeks after discontinuation of the drug. Median time to TMA diagnosis was 28 days after transplant (range, 13.8 to 48.5). Study subjects received a median of 14 eculizumab doses (range, 2 to 38 doses) for HSCT-associated TMA therapy. There were no incidences of meningococcal infections. The incidences of bacterial and fungal bloodstream infections were similar in patients treated with eculizumab (n = 30) as compared with those with HSCT-associated TMA who did not receive any complement blocking therapy (n = 39). Our data indicate that terminal complement blockade in the early post-transplant period can be performed without meningococcal vaccination while using appropriate antimicrobial prophylaxis until complement function is restored after therapy completion.

Evaluation of Intravascular Hemolysis With Erythrocyte Creatine in Patients With Aortic Stenosis

Chronic intravascular hemolysis has been identified in patients with cardiac valve prostheses, but only a few case reports have evaluated intravascular hemolysis in patients with native valvular heart disease. To detect intravascular hemolysis in patients with aortic stenosis, erythrocyte creatine was evaluated with hemodynamic indices obtained by echocardiography.Erythrocyte creatine, a marker of erythrocyte age, was assayed in 30 patients with aortic stenosis and 10 aged matched healthy volunteers. Peak flow velocity of the aortic valve was determined by continuous-wave Doppler echocardiography. Twenty of 30 patients with aortic stenosis had high erythrocyte creatine levels (> 1.8 µmol/g Hb) and erythrocyte creatine was significantly higher as compared with control subjects (1.98 ± 0.49 versus 1.52 ± 0.19 µmol/g Hb, P = 0.007). Peak transvalvular pressure gradient ranged from 46 to 142 mmHg and peak flow velocity ranged from 3.40 to 5.95 m/second. Patients with aortic stenosis had a significantly lower erythrocyte count (387 ± 40 versus 436 ± 42 × 10(4) µL, P = 0.002) and hemoglobin (119 ± 11 versus 135 ± 11 g/L, P < 0.001) as compared with control subjects. Erythrocyte creatine had a fair correlation with peak flow velocity (r = 0.55, P = 0.002).In conclusion, intravascular hemolysis due to destruction of erythrocytes was detected in patients with moderate to severe aortic stenosis and the severity of intravascular hemolysis was related to valvular flow velocity of the aortic valve.

INTRAVASCULAR HEMOLYSIS IN PATIENTS WITH AORTIC STENOSIS: EVALUATION BY ERYTHROCYTE CREATINE

Intravascular hemolysis has been identified in patients with prosthetic heart valves, but there are only few case reports evaluating intravascular hemolysis in patients with native valvular heart disease. To detect intravascular hemolysis in patients with aortic stenosis, erythrocyte creatine was

Cell-type–specific transcriptional regulation of PIGM underpins the divergent hematologic phenotype in inherited GPl deficiency

AbstractA rare point mutation in the core promoter −270GC-rich box of PIGM, a housekeeping gene, disrupts binding of the generic transcription factor (TF) Sp1 and causes inherited glycosylphosphatidylinositol (GPI) deficiency (IGD). We show that whereas PIGM messenger RNA levels and surface GPI expression in IGD B cells are low, GPI expression is near normal in IGD erythroid cells. This divergent phenotype results from differential promoter chromatin accessibility and binding of Sp1. Specifically, whereas PIGM transcription in B cells is dependent on Sp1 binding to the −270GC-rich box and is associated with lower promoter accessibility, in erythroid cells, Sp1 activates PIGM transcription by binding upstream of (but not to) the −270GC-rich box. These findings explain intact PIGM transcription in IGD erythroid cells and the lack of clinically significant intravascular hemolysis in patients with IGD. Furthermore, they provide novel insights into tissue-specific transcriptional control of a housekeeping gene by a generic TF.

The Role of Medical Management for Acute Intravascular Hemolysis in Patients Supported on Axial Flow LVAD

Continuous flow left ventricular assist devices (LVADs) are used with good outcome. However, acute intravascular hemolysis due to thrombus in the pump remains a clinical challenge. We screened for LVAD-related intravascular hemolysis among 115 consecutive patients surviving HeartMateII implantation and investigated the role of medical therapy in resolving the hemolysis. Hemolytic events were identified in 7% of patients, 2-26 months after implant, manifested by peak lactate dehydrogenase (LDH) levels >6 times normal. With the institution of heparin and enhanced antiplatelet therapy, LDH levels receded rapidly reaching a stable trough level near baseline within 2 weeks with the resolution of clinical symptoms except in one patient who required additional therapy with tissue plasminogen activator (tPA). Complications included transient renal failure, one splenic infarct, and a cerebrovascular attack after tPA. The acute event of hemolysis resolved with medical therapy, and all were successfully discharged. However, recurrent hemolysis was common (6/8 patients over the next 1-7 months). At the end of follow-up, three patients were transplanted, one patient died refusing LVAD exchange for recurrent hemolysis, and 4 remained alive on LVAD support. Medical treatment with intensification of anticoagulation can be effective in resolving the acute hemolytic event. However, a definitive long-term strategy should be planned because the recurrence rate is high.

Editorial Commentary: Single-Dose Primaquine as Gametocytocidal Treatment in Patients With Uncomplicated Falciparum Malaria

Editorial Commentary: Single-Dose Primaquine as Gametocytocidal Treatment in Patients With Uncomplicated Falciparum Malaria

The relationship between the severity of hemolysis, clinical manifestations and risk of death in 415 patients with sickle cell anemia in the US and Europe

The intensity of hemolytic anemia has been proposed as an independent risk factor for the development of certain clinical complications of sickle cell disease, such as pulmonary hypertension, hypoxemia and cutaneous leg ulceration. A composite variable derived from several individual markers of hemolysis could facilitate studies of the underlying mechanisms of hemolysis. In this study, we assessed the association of hemolysis with outcomes in sickle cell anemia. A hemolytic component was calculated by principal component analysis from reticulocyte count, serum lactate dehydrogenase, aspartate aminotransferase and total bilirubin concentrations in 415 hemoglobin SS patients. Association of this component with direct markers of hemolysis and clinical outcomes was assessed. As primary validation, both plasma red blood cell microparticles and cell-free hemoglobin concentration were higher in the highest hemolytic component quartile compared to the lowest quartile (P≤0.0001 for both analyses). The hemolytic component was lower with hydroxyurea therapy, higher hemoglobin F, and alpha-thalassemia (P≤0.0005); it was higher with higher systemic pulse pressure, lower oxygen saturation, and greater values for tricuspid regurgitation velocity, left ventricular diastolic dimension and left ventricular mass (all P<0.0001). Two-year follow-up analysis showed that a high hemolytic component was associated with an increased risk of death (hazard ratio, HR 3.44; 95% confidence interval, CI: 1.2-9.5; P=0.02). The hemolytic component reflects direct markers of intravascular hemolysis in patients with sickle cell disease and allows for adjusted analysis of associations between hemolytic severity and clinical outcomes. These results confirm associations between hemolytic rate and pulse pressure, oxygen saturation, increases in Doppler-estimated pulmonary systolic pressures and mortality (Clinicaltrials.gov identifier: NCT00492531).

Eculizumab: A Guide to its Use in Paroxysmal Nocturnal Hemoglobinuria

The targeted terminal complement inhibitor eculizumab (Soliris) reduces intravascular hemolysis in patients with paroxysmal nocturnal hemoglobinuria (PNH), as well as stabilizing hemoglobin levels, improving fatigue and health-related quality of life, and reducing the requirement for packed red cell transfusions. Eculizumab is generally well tolerated in patients with PNH, although the risk of Neisseria meningitidis infection is increased with eculizumab, meaning that patients must be vaccinated.

Insidious, Largely Undetected, Fatal Clostridium perfringens Sepsis Resulting in Unbridled Vascular Hemolysis: Concepts Regarding Pathogenesis

© 2012 Elsevier 0196-4399/00 (see frontmatter) 47 Introduction Clostridium perfringens is a grampositive, encapsulated, nonmotile, anaerobic, spore-forming bacillus that is widely distributed in nature and the alimentary tracts of animals and humans (1). When cultured on 5% sheep blood agar, it produces a distinct zone of beta hemolysis surrounded by a secondary, less-intense hemolytic zone. The hemolytic zones on blood agar are attributable to several hemolysins, including the very potent alpha-lecithinase (phospholipase C) toxin. Under ideal growth conditions, C. perfringens has a doubling time of 7 min (2) and, therefore, in a short time span can produce and secrete large amounts of toxins, which can account for most of the clinical manifestations of infections caused by the bacterium. C. perfringens is well known as a virulent pathogen in gas gangrene infections and in food poisoning, as exemplified by enteritis necroticans (pigbel), a necrotizing infection of the jejunum and ileum accompanied by bloody diarrhea (3,4). Other devastating manifestations of C. perfringens invasion include postabortal and postpartum infections, leading to intravascular hemolysis in patients who have undergone abortion (5) or who have sustained trauma. In addition, spontaneous, nontraumatic gas gangrene can occur in Corresponding Author: Steve Xie, M.D., Ph.D., Department of Pathology, Westchester Medical Center, New York Medical College, 100 Woods Rd., Valhalla, NY 10595. Tel.: 914-493-7433. Fax: 914493-1145. E-mail: xies@wcmc.com Case Report