Evaluation of AQUIOS STEM, a novel method for automated CD34+ stem cell enumeration using flow cytometry.

OBJECTIVES: Hematopoietic stem cell transplantation (HSCT) is a potentially curative treatment for various diseases. The measurement of CD34+ cells is crucial to schedule the peripheral blood stem cell collection and assess the engraftment potential of the apheresis product. The AQUIOS STEM system has been introduced as a novel application on the AQUIOS CL, a fully automated flow cytometer, for the enumeration of CD34+ hematopoietic progenitor cells (HPCs) in accordance with the The International Society for Hematotherapy and Graft Engineering guidelines. This study aimed to assess the potential of the novel AQUIOS STEM system versus currently used systems including the FACSCanto-II and the FACS Lyric flow cytometer in a multicenter study. METHODS: A total of 91 samples were used for the validation of the AQUOIS STEM system, including an analytical performance evaluation by means of assessing precision, sample stability, intersample carryover, and linearity and a method comparison with the present FACS systems in use to assess analytical and clinical decision agreement. RESULTS: Results showed excellent precision, with coefficient of variations <15% for dedicated quality control material and patient samples. There was no significant carry over. The fresh apheresis samples were stable when stored overnight at room temperature and at 4°C. Analytical comparison with the current systems demonstrated good correlation in peripheral blood, and minimal, clinically neglectable systematic and proportional bias in fresh apheresis products but a low correlation coefficient in cryopreserved products. CONCLUSIONS: The STEM system on AQUIOS CL allows automated enumeration of CD34+ stem cells, demonstrating good analytical performance and promising overall outcomes in peripheral blood and fresh apheresis products.

Alternative genetic alterations of MYC, BCL2, and/or BCL6 in high-grade B-cell lymphoma (HGBL) and diffuse large B-cell lymphoma (DLBCL): Can we identify different prognostic subgroups?

High-grade B-cell lymphoma (HGBL)/diffuse large B-cell lymphoma (DLBCL) with rearrangements (R) in MYC and BCL2 and/or BCL6 are correlated with poor prognosis. Little is known about the impact of other genetic alterations (gain (G) or amplification (A)) of these genes. The aim of the study was to investigate whether we can identify new prognostic subgroups. Fluorescence in situ hybridization (FISH) results from 169 HGBL/DLBCL were retrospectively categorized into: (1) concurrent MYC-R and BCL2-R and/or BCL6-R-samples with MYC-R and BCL2-R (+/- BCL6-R); n = 21, and HGBL/DLBCL with MYC-R and BCL6-R; n = 11; (2) concurrent R and G/A in MYC and BCL2 and/or BCL6 called "alternative HGBL/DLBCL"-samples with (n = 16) or without (n = 6) BCL2 involvement; (3) BCL2 and/or BCL6 alterations without MYC involvement (n = 35); (4) concurrent G/A in MYC and BCL2 and/or BCL6 without R (n = 25); and (5) "No alterations" (n = 55). Patients with HGBL/DLBCL-MYC/BCL2 and "alternative" HGBL/DLBCL (with BCL2 involvement) had significantly worse survival rates compared to the "no alterations" group. G/A of these genes in the absence of rearrangements did not show any prognostic significance. HGBL/DLBCL with MYC-R and BCL6-R without BCL2 involvement showed a better survival rate compared to HGBL/DLBCL-MYC/BCL2. According to immunohistochemistry, "double/triple" expression (DEL/TEL) did not show a significantly worse outcome compared to absent DEL/TEL. This study highlights the continued value of FISH assessment of MYC, BCL2, and BCL6 in the initial evaluation of HGBL/DLBCL with different survival rates between several genetic subgroups.

Acquired factor X deficiency in a multiple myeloma without amyloidosis: a case report.

BACKGROUND: Multiple myeloma is one of the most common hematologic malignancies. Acquired factor X deficiencies are often observed in primary (AL) amyloidosis and rarely in multiple myeloma. OBJECTIVE: We report a case of an acquired factor X deficiency in a patient with a newly diagnosed IgA lambda multiple myeloma, without any evidence of concomitant amyloidosis. METHODS: We present the patient's medical history, clinical and physical examinations, laboratory analysis, and outcome. RESULTS: A 76-year-old male presented at the emergency department with ongoing gingival bleeding. Several analytical problems with blood sample analysis arose, which eventually led to the diagnosis of a multiple myeloma. Further exploration revealed an acquired factor X deficiency, explaining the ongoing bleeding. There was no evidence of concomitant amyloidosis. The multiple myeloma was treated, leading to complete remission of the malignancy and bleeding tendency. CONCLUSION: While coagulopathy is rarely observed in patients diagnosed with multiple myeloma, considering an acquired factor X deficiency becomes relevant when such patient present with bleeding diathesis.

Immune Senescence Markers Predict the Cellular Immune Response to BNT162b2 Vaccination in Hemodialysis Patients.

Background: Chronic kidney disease is associated with increased risk of frailty and accelerated immune senescence, potentially affecting the immune response to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccination. Methods: Humoral and cellular responses against the spike protein of SARS-CoV-2 were determined in 189 COVID-naive hemodialysis patients at week 4 and 8 after vaccination with 2 doses of BNT162b2. Frailty indicators and immune senescence markers were determined at baseline to identify predictors of the immune response. Results: Controlling for age, activities of daily living (ADLs), instrumental ADLs, walking pace, and the clinical frailty score correlated negatively and hand grip strength positively with the humoral response. Controlling for age, the proportions of memory CD4+ T cells, memory CD8+ T cells, CD28null T cells, and CD57+CD8+ T cells correlated negatively with the humoral response, whereas the proportions of memory CD4+ T cells and CD28null T cells correlated negatively and the CD4/CD8 ratio positively with the cellular response. In a multivariate model, only the proportions of memory CD4+ T cells and CD28null T cells independently predicted the cellular response. Conclusions: Markers of immune senescence, but not frailty indicators, independently predict the cellular immune response after vaccination in hemodialysis patients, overruling the effect of chronological age.

Routine noninvasive prenatal screening for fetal Rh D in maternal plasma-A 2-year experience from a single center in Belgium.

BACKGROUND: Hemolytic disease of the fetus and newborn (HDFN) due to rhesus D (RhD) immunization is a potentially life-threatening situation for which use of Rh Immunoglobulin (RhIg) has decreased risk drastically. Determination of fetal RHD on maternal plasma can be used to restrict prenatal RhIg administration to women carrying an RhD-positive child, avoiding unnecessary administration of blood-derived products. STUDY DESIGN AND METHODS: The aim of this study is to determine the performance of fetal RHD typing in our center. We prospectively collected 205 fetal RHD and 127 serological cord blood RhD data from RhD-negative women starting at 11 weeks of pregnancy (from October 2019 to October 2021). Real-time polymerase chain reaction targeting RHD exon 5 and 7 was used, similar to the screening program in The Netherlands, supplemented with an amplification control (beta-actin; ACTB) and a sex determination marker located on the Y-chromosome (SRY gene). RESULTS: Fetal RHD testing reached a sensitivity and specificity of 100%. No false-negative nor false-positive results were reported. Inconclusive results (6%, 13/205) were due to weak amplification in 10 cases, a maternal RHD variant in 2 cases (RHD*01N.71 and partial DVI), and a fetal RHD variant (partial DVI) in 1 case. Unnecessary administration of RhIg prophylaxis was avoided in 33% of cases and on the other hand was administered in one case (fetal partial DVI) which would have been missed with cord blood serology. DISCUSSION: This study demonstrates the high accuracy of routine prenatal fetal RHD gene screening after 11 weeks of pregnancy, encouraging routine clinical practice.

Evaluation of next-generation sequencing-based clonality analysis of T-cell receptor gamma gene rearrangements based on a new interpretation algorithm.

INTRODUCTION: T-cell receptor gene (TRG) rearrangement profiling is an essential component of the workup at diagnosis of T-cell malignancies. TRG amplification by polymerase chain reaction (PCR) and analysis by capillary electrophoresis (PCR-CE) is mostly widely used but is hampered by a subjective interpretation of its results and possible false-positive interpretation of clonality. Several studies evaluated the advantage of TRG rearrangement analysis by Next Generation Sequencing (TRG-NGS), however few have proposed an adequate data interpretation algorithm. METHODS: Eighty five fresh and 36 formalin-fixed paraffin embedded (FFPE) diagnostic samples suspected for a lymphoproliferative disorder were analyzed by PCR-CE and TRG NGS. Final clinical diagnosis was available for all fresh samples. Reproducibility, analytical specificity and sensitivity of the TRG NGS analysis was evaluated. RESULTS: We propose a new interpretation algorithm for TRG NGS data analysis. PCR-CE and TRG NGS showed identical results in 66/85 (78%) of fresh samples. Sensitivities to detect T-cell malignancies were comparable (96% versus 92%, respectively). The analysis of FFPE material was significantly more successful by TRG NGS (34/36 cases) in respect to PCR-CE (16/36 cases), most likely due to the small size of the amplicons. CONCLUSION: Assessment of T-cell clonality by TRG NGS has a significant added value in the diagnosis of T-cell disorders as an adjunct to PCR-CE, particularly in difficult to interpret cases or when analyzing FFPE samples.

Diagnostic utility of the lymphoid screening tube supplemented with CD34 for Ogata score calculation in patients with peripheral cytopenia.

OBJECTIVES: The diagnosis of myelodysplastic syndrome (MDS) is not always straightforward in the absence of objective markers such as ringed sideroblasts, an excess of blasts or clonal cytogenetic abnormalities. Moreover, the lack of specificity of morphological dysplasia makes the differentiation between MDS and other causes of peripheral cytopenia difficult. The WHO 2016 classification of MDS recognizes multiparameter flow cytometry (MFC) as an adjuvant tool for MDS diagnosis. An easily applicable MFC protocol based on CD34 and CD45 is proposed by Ogata et al. Furthermore, in the diagnostic workup of patients with peripheral cytopenia, the integration of MFC by means of a Lymphoid Screening Tube (LST) is recommended by the EuroFlow™ consortium. The aim of this study was to investigate whether the LST, supplemented with CD34, can be used to calculate the Ogata score, thereby obviating the need to run different flow cytometric tubes. METHODS: Bone marrow samples from 108 patients with peripheral cytopenia were analyzed (MDS n = 32; non-MDS n = 76). The LST used in the present study was based on the tube designed by the EuroFlow™ consortium, but with addition of CD34 and without TCRγδ. RESULTS: Rather low sensitivities of 55% in low-grade MDS patients and 80% in high-grade MDS patients were observed. However, a high specificity of 92% was found in the non-MDS group. CONCLUSION: Besides screening for clonal lymphocytes, plasma cells and blasts, an LST supplemented with CD34 allows the calculation of the Ogata score as an adjuvant tool in the diagnostic workup of cytopenic patients suspected of MDS.

Evaluation of the CellaVision DM96 advanced RBC application for screening and follow-up of malaria infection.

CellaVision DM96 is a digital cell morphology system for automated classification of white and red blood cells. CellaVision Advanced RBC application (ARBCA) pre-classifies RBC in 21 categories, including parasitized RBC, and allows re-classification by the operator. In this study, the performance of the software for detection of malaria and calculation of parasitemia was evaluated and compared to microscopy (n=40). For CellaVision, both pre- and post-reclassification results were evaluated. Sensitivity was moderate, even post-reclassification (72%), due to low numbers of analyzed RBC and limited resolution of photographs. CellaVision results correlated with microscopy according to Passing-Bablok analysis, with slightly lower values for CellaVision. Within-run, between-run and inter-observer variability were acceptable. The low sensitivity of CellaVision ARBCA precludes its use as a screening technique for malaria. However, due to its good correlation with microscopy and short turn-around-times, it may be useful in follow-up of parasitemia. Larger studies are required to confirm these findings.

Evaluation of four hemoglobin separation analyzers for hemoglobinopathy diagnosis.

BACKGROUND: Four automated hemoglobin separation devices are compared in their ability to detect hemoglobinopathies, both in HbA1c and in hemoglobinopathy mode. METHODS: Quality control material and 58 samples, including one heterozygous α-thalassemia sample, six heterozygote ß-thalassemia samples and 32 samples with a known hemoglobin variant, were used to assess imprecision of HbF and HbA2 measurements, correlation with the gold standard and sensitivity for detecting ß-thalassemia and Hb variants on D-100 (Bio-Rad Laboratories), HA 8180T (Menarini), HLC-723G8 (Tosoh Bioscience) and Capillarys 2 Flex Piercing (Sebia). RESULTS: Imprecision was <10% for both HbF and HbA2 in all modes of all analyzers. Correlation studies for HbF and HbA2 demonstrated statistically significant but small biases when compared to the gold standard. All six ß-thalassemia samples but one were detected on all analyzers using a HbA2 cut-off value of 3.5%. D-100, HA8180T and the Hb-pathy mode of the HLC-723G8 and the Capillarys are able to detect the most common important Hb variants (Hb C, D, E and S), but more seldom variants can be missed as they co-elute with HbA0. The HbA1c mode of the Capillarys correctly detected all measured hemoglobin variants and can therefore be used as a hemoglobinopathy screening device. This was also the case for the most common important Hb variants on the HbA1c mode of the HLC-723G8, but two rare variants were not detected. CONCLUSION: This study stresses the importance for individual laboratories to know the advantages and drawbacks of their hemoglobin separation analyzer and its different modes in the diagnosis of hemoglobinopathies.

Analysis of phenotype and outcome in essential thrombocythemia with CALR or JAK2 mutations.

The JAK2 V617F mutation, the thrombopoietin receptor MPL W515K/L mutation and calreticulin (CALR) mutations are mutually exclusive in essential thrombocythemia and support a novel molecular categorization of essential thrombocythemia. CALR mutations account for approximately 30% of cases of essential thrombocythemia. In a retrospective study, we examined the frequency of MPL and CALR mutations in JAK2 V617F-negative cases of essential thrombocythemia (n=103). In addition, we compared the clinical phenotype and outcome of CALR mutant cases of essential thrombocythemia with a cohort of JAK2 V617F-positive essential thrombocythemia (n=57). CALR-positive cases represented 63.7% of double-negative cases of essential thrombocythemia, and most carried CALR type 1 or type 2 indels. However, we also identified one patient who was positive for both the JAK2 V617F and the CALR mutations. This study revealed that CALR mutant essential thrombocythemia is associated with younger age, higher platelet counts, lower erythrocyte counts, leukocyte counts, hemoglobin, and hematocrit, and increased risk of progression to myelofibrosis in comparison with JAK2 V617F-positive essential thrombocythemia. Analysis of the CALR mutant group according to indel type showed that CALR type 1 deletion is strongly associated with male gender. CALR mutant patients had a better overall survival than JAK2 V617F-positive patients, in particular patients of age 60 years or younger. In conclusion, this study in a Belgian cohort of patients supports and extends the growing body of evidence that CALR mutant cases of essential thrombocythemia are phenotypically distinct from JAK2 V617F-positive cases, with regards to clinical and hematologic presentation as well as overall survival.

Dose-finding study of rivaroxaban in hemodialysis patients.

BACKGROUND: Use of vitamin K antagonists for the prevention of stroke and systemic embolism in dialysis patients with nonvalvular atrial fibrillation is controversial. However, no good alternatives presently are available. The anti-factor Xa antagonist rivaroxaban is contraindicated for lack of pharmacokinetic, pharmacodynamic, and clinical data. This study aims to characterize the pharmacokinetics/pharmacodynamics of rivaroxaban in maintenance hemodialysis patients. STUDY DESIGN: Pharmacokinetic and pharmacodynamic study. SETTING & PARTICIPANTS: 18 maintenance hemodialysis patients without residual kidney function at 2 centers. DRUG ADMINISTRATION, OUTCOMES, & MEASUREMENTS: (1) A single dose of 10mg of rivaroxaban was administered at the end of each of 3 consecutive dialysis sessions and area under the curve (AUC) and the effect on coagulation parameters were measured for 44 hours thereafter. (2) A single dose of 10mg of rivaroxaban was given 6 to 8 hours before a dialysis session and the effect of dialysis on rivaroxaban concentrations was evaluated. (3) To assess potential accumulation, 10mg of rivaroxaban was given once daily and AUC was measured during 24 hours on days 1 and 7. RESULTS: Mean AUC0-44 of rivaroxaban plasma concentrations after a single dose of 10mg was 2,072µg/L/h, mean maximum concentration was 172.6µg/L, and mean terminal elimination half-life was 8.6 hours. Dialysis had no appreciable effect on rivaroxaban plasma concentrations. Mean trough concentration after multiple daily doses of 10mg was 20.2µg/L. LIMITATIONS: Higher rivaroxaban doses and patients with substantial residual kidney function were not studied. CONCLUSIONS: A 10-mg dose of rivaroxaban in hemodialysis patients without residual kidney function results in drug exposure similar as published for 20mg in healthy volunteers. Rivaroxaban is not eliminated by dialysis. There is no accumulation after multiple daily dosing. The efficacy and safety of rivaroxaban in hemodialysis patients should be the subject of a large randomized trial.

Thrombogenic changes in young and old mice upon subchronic exposure to air pollution in an urban roadside tunnel.

Epidemiological studies indicate that elderly persons are particularly susceptible to the cardiovascular health complications of air pollution, but pathophysiological mechanisms behind the increased susceptibility remain unclear. Therefore, we investigated how continuous traffic-related air pollution exposure affects haemostasis parameters in young and old mice. Young (10 weeks) and old (20 months) mice were placed in an urban roadside tunnel or in a clean environment for 25 or 26 days and markers of inflammation and endothelial cells or blood platelet activation were measured, respectively. Plasma microvesicles and pro/anticoagulant factors were analysed, and thrombin generation analysis was performed. Despite elevated macrophage carbon load, tunnel mice showed no overt pulmonary or systemic inflammation, yet manifested reduced pulmonary thrombomudulin expression and elevated endothelial von Willebrand factor (VWF) expression in lung capillaries. In young mice, soluble P-selectin (sP-sel) increased with exposure and correlated with soluble E-selectin and VWF. Baseline plasma factor VIII (FVIII), sP-sel and VWF were higher in old mice, but did not pronouncedly increase further with exposure. Traffic-related air pollution markedly raised red blood cell and blood platelet numbers in young and old mice and procoagulant blood platelet-derived microvesicle numbers in old animals. Changes in coagulation factors and thrombin generation were mild or absent. Hence, continuous traffic-related air pollution did not trigger overt lung inflammation, yet modified pulmonary endothelial cell function and enhanced platelet activity. In old mice, subchronic exposure to polluted air raised platelet numbers, VWF, sP-sel and microvesicles to the highest values presently recorded, collectively substantiating a further elevation of thrombogenicity, already high at old age.

Changed gene expression in brains of mice exposed to traffic in a highway tunnel.

CONTEXT: Air pollution has been suggested to have an impact on the brain. OBJECTIVE: The objective was to assess the expression of inflammation-related genes in the brains of mice that had been exposed for 5 days to a well-characterized traffic-polluted environment, i.e. a highway tunnel. MATERIALS AND METHODS: Twenty C57BL6 mice were randomly allocated to four groups of five animals. Two groups were placed in the tunnel for 5 days (mean PM 2.5, 55.1 µg/m³, mean elemental carbon, EC 13.9 µg/m³) in cages with or without filter, two control groups were housed outside the tunnel. Animals were assessed within 24 hours after the last exposure day. Lung injury and inflammation were assessed by bronchoalveolar lavage (BAL) and histology. Blood leukocytosis and coagulation parameters were determined in peripheral blood. The olfactory bulb and hippocampus were analyzed for changes in expression of inflammatory genes and brain-derived neurotrophic factor (BDNF). RESULTS AND DISCUSSION: Although carbon particles were abundant in alveolar macrophages of exposed mice and absent in non-exposed mice, there was no evidence of pulmonary or systemic inflammation. There was an increased expression of genes involved in inflammatory response (COX2, NOS2, NOS3, and NFE2L2) in the hippocampus of the exposed mice. In the olfactory bulb, a downregulation was found for IL1α, COX2, NFE2L2, IL6, and BDNF. CONCLUSION: Although this short-term exposure to traffic-related pollution did not induce pulmonary or systemic inflammation, the expression of inflammatory genes was affected in different brain areas. The decreased BDNF expression in the olfactory bulb suggests lower brain neurotrophic support in response to traffic-related air pollution.

Circulating apoptotic endothelial cells and apoptotic endothelial microparticles independently predict the presence of cardiac allograft vasculopathy.

OBJECTIVES: Maintenance of endothelial homeostasis may prevent the development of cardiac allograft vasculopathy (CAV). This study investigated whether biomarkers related to endothelial injury and endothelial repair discriminate between CAV-negative and CAV-positive heart transplant recipients. BACKGROUND: CAV is the most important determinant of cardiac allograft survival and a major cause of death after heart transplantation. METHODS: Fifty-two patients undergoing coronary angiography between 5 and 15 years after heart transplantation were recruited in this study. Flow cytometry was applied to quantify endothelial progenitor cells (EPCs), circulating endothelial cells (CECs), and endothelial microparticles. Cell culture was used for quantification of circulating EPC number and hematopoietic progenitor cell number and for analysis of EPC function. RESULTS: The EPC number and function did not differ between CAV-negative and CAV-positive patients. In univariable models, age, creatinine, steroid dose, granulocyte colony-forming units, apoptotic CECs, and apoptotic endothelial microparticles discriminated between CAV-positive and CAV-negative patients. The logistic regression model containing apoptotic CECs and apoptotic endothelial microparticles as independent predictors provided high discrimination between CAV-positive and CAV-negative patients (C-statistic 0.812; 95% confidence interval: 0.692 to 0.932). In a logistic regression model with age and creatinine as covariates, apoptotic CECs (p = 0.0112) and apoptotic endothelial microparticles (p = 0.0141) were independent predictors (C-statistic 0.855; 95% confidence interval: 0.756 to 0.953). These 2 biomarkers remained independent predictors when steroid dose was introduced in the model. CONCLUSIONS: The high discriminative ability of apoptotic CECs and apoptotic endothelial microparticles is a solid foundation for the development of clinical prediction models of CAV.

Effect of ageing on the murine venous circulation.

The effect of ageing on the morphology of veins, venous valves and arteries was investigated in male wild-type mice using an adapted procedure with injection of a silicone polymer Microfil(®) that preserves morphology of the vasculature. Throughout the hind limb the arterial, but not the venous, lumen area and wall thickness were significantly greater in 24-month as compared to 10-week-old C57BL/6 mice. Venous valves were most frequently located at the sapheno-femoral vein junction in the lower extremities, and appeared thicker at the base supported by structurally intact collagen fibers, and thinner towards the proximal end of the valve leaflet, with less organized collagen. Overall, valves were less supported by structurally intact collagen at 24 months as compared to 10 weeks. Endothelial expression of CD31, endothelial protein C receptor or von Willebrand factor (VWF) was not affected by age, while thrombomodulin expression was lower in aged versus young arteries. At both ages, expression of VWF was lower at venous valves versus veins. Evaluation of the blood coagulation profile revealed that aged mice had shortened prothrombin time, elevated plasma levels of factor (F)VII, FVIII and VWF and increased neutrophil and platelet counts. Thus, our data indicate that in mice with ageing, venous valves become more fragile, in association with a procoagulant and inflammatory blood phenotype. Taken together, we found that the procoagulant state in ageing, is accompanied by mild vascular changes.

Progression of the prothrombotic state in aging Bmal1-deficient mice.

OBJECTIVE: The goal of this study was to examine the functional relationship between aging endothelium and thrombogenicity in a mouse model of premature aging. METHODS AND RESULTS: Coagulation tests and factors, blood cell counts, aorta endothelial function, aorta gene expression, and FeCl(3)-induced thrombosis in mesenteric blood vessels were analyzed in 10- to 30-week-old brain and muscle ARNT-like protein-1 (Bmal1)-deficient (knockout [KO]) mice and wild-type littermates. Ten-week-old KO mice manifested shortened prothrombin times (9.7 versus 11.3 seconds in wild-type) and elevated plasma fibrinogen (264 versus 172 mg/dL). At 30 weeks, factor VII (198% versus 149%), and platelet counts (2049 versus 1354 K/µL) were increased in KO mice. Gene deficiency reduced the vasoactive nitric oxide production at 10 and 30 weeks and tended to reduce and increase the protein expression of thrombomodulin and von Willebrand factor, respectively, with aging. Shortened venular and arteriolar occlusion times on FeCl(3)-induced injury in 10-week-old KO mice confirmed higher thrombogenicity, culminating in priapism, observed in 60% of 25- to 30-week-old KO males. CONCLUSION: Endothelial dysfunction and a hypercoagulable state cause early arterial and venous thrombogenicity in Bmal1 KO mice. With aging, progressive endothelial dysfunction, rising platelet counts, and high factor VII further enhance thrombogenicity, provoking priapism.

Correction of endothelial dysfunction after selective homocysteine lowering gene therapy reduces arterial thrombogenicity but has no effect on atherogenesis.

Hyperhomocysteinemia is an independent risk factor for ischemic cardiovascular diseases, but its causal role in atherothrombosis remains controversial. Proatherogenic and/or prothrombotic effects may underlie the potential causal relation between hyperhomocysteinemia and cardiovascular events. Here, the effects of selective lowering of plasma homocysteine, plasma cholesterol, or both on endothelial function and on atherogenesis in male hyperlipidemic and hyperhomocysteinemic C57BL/6 low-density lipoprotein receptor (LDLr)(-/-)/cystathionine-ß-synthase (CBS)(+/-)-deficient mice were investigated. Second, we evaluated whether selective homocysteine lowering has anti-thrombotic effects in a model of arterial thrombosis. A hyperhomocysteinemic and atherogenic diet was started at the age of 12 weeks. Three weeks later, gene transfer was performed with E1E3E4-deleted adenoviral vectors for hepatocyte-restricted overexpression of CBS (AdCBS) or of the LDLr (AdLDLr), or with the control vector Adnull. In a fourth group, AdCBS and AdLDLr were co-administered. Selective homocysteine lowering but not selective cholesterol lowering restored endothelial function at 6 weeks after gene transfer. Intimal area in the aortic root and in the brachiocephalic artery at 13 weeks was more than 100-fold (p < 0.001) smaller in AdLDLr and AdCBS/AdLDLr mice than in control mice and AdCBS mice. No differences in intimal area were observed between control mice and AdCBS mice. In a model of carotid artery thrombosis, the average time to first occlusion and to stable occlusion were 1.9-fold (p < 0.01) and 2.1-fold longer (p < 0.01), respectively, in AdCBS-treated mice than in control mice. Taken together, these data show that correction of endothelial dysfunction following selective homocysteine lowering has anti-thrombotic but no anti-atherogenic effects.

Evaluation of the profibrinolytic properties of an anti-TAFI monoclonal antibody in a mouse thromboembolism model.

The enhancement of fibrinolysis constitutes a promising approach to treat thrombotic diseases. Activated thrombin activatable fibrinolysis inhibitor (TAFIa) attenuates fibrinolysis and is an attractive target to develop profibrinolytic drugs. TAFI can be activated by thrombin, thrombin/thrombomodulin, or plasmin, but the in vivo physiologic TAFI activator(s) are unknown. Here, we generated and characterized MA-TCK26D6, a monoclonal antibody raised against human TAFI, and examined its profibrinolytic properties in vitro and in vivo. In vitro, MA-TCK26D6 showed a strong profibrinolytic effect caused by inhibition of the plasmin-mediated TAFI activation. In vivo, MA-TCK26D6 significantly decreased fibrin deposition in the lungs of thromboembolism-induced mice. Moreover, in the presence of MA-TCK26D6, plasmin-α(2)-antiplasmin complexes in plasma of thromboembolism-induced mice were significantly increased compared with a control antibody, indicative of an acceleration of fibrinolysis through MA-TCK26D6. In this study, we show that plasmin is an important TAFI activator that hampers in vitro clot lysis. Furthermore, this is the first report on an anti-TAFI monoclonal antibody that demonstrates a strong profibrinolytic effect in a mouse thromboembolism model.

Traffic air pollution and oxidized LDL.

BACKGROUND: Epidemiologic studies indirectly suggest that air pollution accelerates atherosclerosis. We hypothesized that individual exposure to particulate matter (PM) derived from fossil fuel would correlate with plasma concentrations of oxidized low-density lipoprotein (LDL), taken as a marker of atherosclerosis. We tested this hypothesis in patients with diabetes, who are at high risk for atherosclerosis. METHODOLOGY/PRINCIPAL FINDINGS: In a cross-sectional study of non-smoking adult outpatients with diabetes we assessed individual chronic exposure to PM by measuring the area occupied by carbon in airway macrophages, collected by sputum induction and by determining the distance from the patient's residence to a major road, through geocoding. These exposure indices were regressed against plasma concentrations of oxidized LDL, von Willebrand factor and plasminogen activator inhibitor 1 (PAI-1). We could assess the carbon load of airway macrophages in 79 subjects (58 percent). Each doubling in the distance of residence from major roads was associated with a 0.027 µm(2) decrease (95% confidence interval (CI): -0.048 to -0.0051) in the carbon load of airway macrophages. Independently from other covariates, we found that each increase of 0.25 µm(2) [interquartile range (IQR)] in carbon load was associated with an increase of 7.3 U/L (95% CI: 1.3 to 13.3) in plasma oxidized LDL. Each doubling in distance of residence from major roads was associated with a decrease of -2.9 U/L (95% CI: -5.2 to -0.72) in oxidized LDL. Neither the carbon load of macrophages nor the distance from residence to major roads, were associated with plasma von Willebrand factor or PAI-1. CONCLUSIONS: The observed positive association, in a susceptible group of the general population, between plasma oxidized LDL levels and either the carbon load of airway macrophages or the proximity of the subject's residence to busy roads suggests a proatherogenic effect of traffic air pollution.

Air pollution related prothrombotic changes in persons with diabetes.

BACKGROUND: Population studies suggest that persons with diabetes are more sensitive to the effects of particulate matter (PM) air pollution. However, the biological mechanisms of a possible prothrombotic effect underlying this enhanced susceptibility remain largely unknown. OBJECTIVE: We hypothesized that exposure to PM causes prothrombotic changes in persons with diabetes, possibly via systemic inflammation. METHODS: Our study included 137 nonsmoking adults with diabetes who were outpatients at the University Hospital Leuven. Recent exposure (2 hr before examination) to ambient PM was measured at the entrance of the hospital. Individual chronic exposure to PM was assessed by measuring the area occupied by carbon in airway macrophages obtained by sputum induction. Platelet function was measured ex vivo with the PFA-100 platelet function analyzer, which simulates a damaged blood vessel; we analyzed the function of platelets in primary hemostasis under high shear conditions. Total and differential blood leukocytes were counted. RESULTS: Independent of antiplatelet medication, an interquartile range (IQR) increase of 39.2 microg/m3 in PM10 (PM with aerodynamic diameter