Evasion of NKG2D-mediated cytotoxic immunity by sarbecoviruses

SARS-CoV-2 and other sarbecoviruses continue to threaten humanity, highlighting the need to characterize common mechanisms of viral immune evasion for pandemic preparedness. Cytotoxic lymphocytes are vital for antiviral immunity and express NKG2D, an activating receptor conserved among mammals that recognizes infection-induced stress ligands (e.g., MIC-A/B). We found that SARS-CoV-2 evades NKG2D recognition by surface downregulation of MIC-A/B via shedding, observed in human lung tissue and COVID-19 patient serum. Systematic testing of SARS-CoV-2 proteins revealed that ORF6, an accessory protein uniquely conserved among sarbecoviruses, was responsible for MIC-A/B downregulation via shedding. Further investigation demonstrated that natural killer (NK) cells efficiently killed SARS-CoV-2-infected cells and limited viral spread. However, inhibition of MIC-A/B shedding with a monoclonal antibody, 7C6, further enhanced NK-cell activity toward SARS-CoV-2-infected cells. Our findings unveil a strategy employed by SARS-CoV-2 to evade cytotoxic immunity, identify the culprit immunevasin shared among sarbecoviruses, and suggest a potential novel antiviral immunotherapy.

Low ectonucleotidase activity and increased neutrophil-platelet aggregates in patients with antiphospholipid syndrome

ABSTRACT

Many patients with antiphospholipid syndrome had decreased ectonucleotidase activity on neutrophils and platelets, which enabled extracellular nucleotides to trigger neutrophil-platelet aggregates. This phenotype was replicated by treating healthy neutrophils and platelets with patient-derived antiphospholipid antibodies or ectonucleotidase inhibitors.

Extracellular vesicles are a late marker of inflammation, hypercoagulability and COVID-19 severity

Exacerbated inflammation and coagulation are a hallmark of COVID-19 severity. Extracellular vesicles (EVs) are intercellular transmitters involved in inflammatory conditions, which are capable of triggering prothrombotic mechanisms. Since the release of EVs is potentially associated with COVID-19-induced coagulopathy, the aim of this study was to evaluate changes in inflammation- and hypercoagulability-related EVs during the first month after symptom onset and to determine whether they are associated with disease severity. Blood samples of patients with mild or severe forms of the disease were collected on three occasions: in the second, third and fourth weeks after symptom onset for the quantification by flow cytometry of CD41A (platelet glycoprotein IIb/IIIa), CD162 (PSGL-1), CD31 (PECAM-1) and CD142 cells (tissue factor). Analysis of variance (ANOVA) with repeated measures, Kruskal-Wallis and correlation tests were used. Eighty-five patients were enrolled, 71% of whom had mild disease. Seventeen uninfected individuals served as controls. Compared to controls, both mild and severe COVID-19 were associated with higher EV-CD31+, EV-CD41+ and EV-CD142+ levels. All EV levels were higher in severe than in mild COVID-19 only after the third week from symptom onset, as opposed to C-reactive protein and D-dimer levels, which were higher in severe than in mild COVID-19 earlier during disease progression. EV levels were also associated with C-reactive protein and D-dimer levels only after the third week of symptoms. In conclusion, EVs expressing CD41A, CD31, TF, and CD162 appear as late markers of COVID-19 severity. This finding may contribute to the understanding of the pathogenesis of acute and possibly long COVID-19.

Immunothrombosis and its underlying biological mechanisms

The evolutionary conserved link between coagulation and innate immunity is a biological process characterized by the thrombosis formation stimulus of immune cells and specific thrombosis-related molecules. In physiological settings, the relationship between the immune system and thrombosis facilitates the recognition of pathogens and damaged cells and inhibits pathogen proliferation. However, when deregulated, the interplay between hemostasis and innate immunity becomes a pathological process named immunothrombosis, which is at the basis of several infectious and inflammation-related thrombotic disorders, including coronavirus disease 2019 (COVID-19). In advanced stages, alterations in both coagulation and immune cell function due to extreme inflammation lead to an increase in blood coagulability, with high rates of thrombosis and mortality. Therefore, understanding underlying mechanisms in immunothrombosis has become decisive for the development of more efficient therapies to treat and prevent thrombosis in COVID-19 and in other thrombotic disorders. In this review, we outline the existing knowledge on the molecular and cellular processes involved in immunothrombosis, focusing on the role of neutrophil extracellular traps (NETs), platelets and the coagulation pathway. We also describe how the deregulation of hemostasis is associated with pathological conditions and can significantly aggravate a patient's condition, using COVID-19 as a clinical model.

Acquired von willebrand syndrome secondary to monoclonal gammopathy of undetermined significance: long-term remission after treatment with bortezomib

Monoclonal gammopathy of undetermined significance (MGUS) is a plasma cell disorder that can precede the diagnosis of multiple myeloma. MGUS is characterized by the presence of a monoclonal paraprotein without evidence of multiple myeloma or other lymphoplasmacytic malignancies. Even though MGUS is an asymptomatic condition that does not require management strategies other than periodic follow-up to prevent complications, secondary nonmalignant diseases may arise, requiring control of the plasma cell clone. Acquired von Willebrand syndrome (AVWS) is a rare bleeding disorder that occurs in patients with no prior personal or family history of bleeding. It is associated with several other disorders, such as neoplasia, mainly hematological (including MGUS and other lymphoproliferative disorders), autoimmune, infectious and cardiac diseases. At diagnosis, patients usually present with cutaneous and mucosal bleeding, including gastrointestinal bleeding. Here, we report a case of a patient with MGUS who developed AVWS after one year of follow-up. The patient was refractory to glucocorticoids and cyclophosphamide and achieved remission only after monoclonal paraprotein was eradicated following treatment with bortezomib and dexamethasone. Our report sdemonstrates that, for refractory cases, eradication of the monoclonal paraprotein may be necessary to treat bleeding complications due to MGUS-associated AVWS.

Thrombosis Occurrence in COVID-19 Compared With Other Infectious Causes of ARDS: A Contemporary Cohort

Thrombosis occurrence in coronavirus disease 2019 (COVID-19) has been mostly compared to historical cohorts of patients with other respiratory infections. We retrospectively evaluated the thrombotic events that occurred in a contemporary cohort of patients hospitalized between March and July 2020 for acute respiratory distress syndrome (ARDS) according to the Berlin Definition and compared those with positive and negative real-time polymerase chain reaction results for wild-type severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) using descriptive analysis. The association between COVID-19 and thrombotic risk was evaluated using logistic regression. 264 COVID-19-positive (56.8% male, 59.0 years [IQR 48.6-69.7], Padua score on admission 3.0 [2.0-3.0]) and 88 COVID-19-negative patients (58.0% male, 63.7 years [51.2-73.5], Padua score 3.0 [2.0-5.0]) were included. 10.2% of non-COVID-19 and 8.7% of COVID-19 patients presented≥1 clinically relevant thrombotic event confirmed by imaging exam. After adjustment for sex, Padua score, intensive care unit stay, thromboprophylaxis, and hospitalization length, the odds ratio for thrombosis in COVID-19 was 0.69 (95% CI, 0.30-1.64). We, therefore, conclude that infection-induced ARDS carries an inherent thrombotic risk, which was comparable between patients with COVID-19 and other respiratory infections in our contemporary cohort.

Venous thromboembolism in critically ill patients with pneumonia in the pre-COVID-19 era: Data from a large public database

Background

The magnitude of venous thromboembolism (VTE) risk in severe COVID‐19 is a matter of debate because of study heterogeneity, changes in VTE management, and scarce evidence of VTE risk in critically ill patients with pneumonia in the pre‐COVID‐19 era.

Objectives

To evaluate VTE risk in the pre‐COVID‐19 era in a large intensive care unit (ICU) database.

Patients/Methods

Data from consecutive pneumonia patients admitted to the ICU were retrieved from the Medical Information Mart for Intensive Care III. VTE risk was described in the entire cohort and in subgroups.

Results

Among 6842 pneumonia patients admitted to the ICU, 486 patients were diagnosed with VTE after a median of 3 (IQR 1–11) days in the ICU. The 30‐day cumulative incidence of VTE was 7% and remained at this level across different age groups, sex, and type of ICU. After adjusting for death, the overall cumulative incidence of VTE was 5%. A total of 1788 patients received thromboprophylaxis (of 2958 for whom that data were available). VTE occurred in 10.7% (95% CI 9.0–12.6) of patients without thromboprophylaxis and in 6.4% (95% CI 5.4–7.6) of those with thromboprophylaxis. Mortality was 20.6% among patients with VTE and 19.2% among those without VTE.

Conclusions

In the pre‐COVID‐19 era, VTE risk in ICU patients with pneumonia was high and decreased with thromboprophylaxis. These findings can serve as comparators for future studies aiming at evaluating the impact of COVID‐19 or other emerging infections on VTE risk.

EXTRACELLULAR VESICLES AS MARKERS OF INFLAMMATION AND HYPERCOAGULABILITY DURING THE FIRST MONTH OF SARS-COV-2 INFECTION IN OUTPATIENTS AND HOSPITALIZED PATIENTS

Introduction

During SARS-CoV-2 infection, a severe hypercoagulability state is observed due to the stimulus of multiple mechanisms of hemostasis, such as coagulation, activation of platelets, endothelial cells, monocytes and neutrophils and impaired fibrinolysis. As a consequence, thrombotic complications are common in the course of COVID-19. Microvesicles (MVs) are intracellular transmitters that participate in pathological conditions, such as inflammatory and infectious processes, and are capable of triggering prothrombotic mechanisms. Since MVs release is potentially associated with COVID-19-induced coagulopathy, our aim was to identify during the course of the disease when the stimulus for MVs release occurs and whether this was associated with adverse outcomes.

Objective

We evaluated changes in the levels of MVs markers during the first month of SARS-CoV-2 infection in patients (pts) with severe disease (hospitalized in an Intensive Care Unit ‒ ICU) as compared to outpatients. We also evaluated the association between MVs markers with: inflammatory biomarkers (C-reactive protein, CRP), hypercoagulability (D-dimer) and death.

Methods

Blood samples were collected on three occasions: before the 10^th day of symptoms, in the 3^rd week of symptoms and in the 4^th week of symptoms for the quantification of the following MVs markers by flow cytometry: CD41A (platelet activation), CD162 (PSGL-1; leukocyte-platelet interaction), CD31 (endothelium-platelet interaction) and CD142 (tissue factor). Statistical tests of ANOVA with repeated measures, Mann-Whitney and regression methods were used.

Results

The population studied was 85 pts, being 25 from ICU. Mostly were men (51%), with a median age of 41 years. The concentration of MVs expressing CD31+, CD41+, CD162+ and CD142+ were persistently elevated in pts who required ICU compared to outpatients at the 3 moments studied, except for the levels of MVs-CD31+ and MVs-CD142+ that were similar between ICU and outpatients in the 4^th week of symptoms. However, despite the differences between the groups, there were no significant changes in the levels of MVs during the course of the disease within the groups. In subgroup analysis, we observed that increases in the levels of MVs-CD162+ and MVs-CD142+ in the 3^rd week of symptoms were associated with the risk of death (p=0.02 and p=0.06, respectively). We also observed that during the course of the disease an association between MVs, coagulability and inflammation was evident. In the 3rd week of symptoms, D-dimer levels were correlated with MV-CD31+ (r=0.52, p<0.0001), MV-CD162+ (r=0.35, p=0.001), MV-CD41A+ (r=0.44, p<0.0001) and MV-CD142+ (r=0.47, p<0.0001) and CRP values were correlated with MV-CD31+ (r=0.56, p=<0.0001), MV-CD162+ (r=0.48, p<0.0001), MV-CD41A+ (r= 0.41, p=0.0001), and MV-CD142+ (r=0.56, p<0.0001). By the 4^th week of symptoms, both D-dimers and CRP correlations with the above MVs remained unchanged.

Conclusion

To conclude, MVs that express antigens related to platelet activation, leukocyte-platelet interaction and endothelium-platelet interaction, as well as those related to tissue factor are released during the course of COVID-19 in pts with severe disease. After the 4^th week of symptoms, the release of these MVs was associated with signs of inflammation and hypercoagulability. Additionally, MVs that express tissue factor and leukocyte-platelet interaction antigens were particularly high among non-survivors, suggesting that these MVs may serve as markers of the risk of death. Finally, these findings suggest the participation of innate immunity and tissue factor pathways in the prognosis of COVID-19, and point towards a possible role of MVs as biomarkers of disease prognosis.

AVALIAÇÃO DA INTEGRIDADE DA BARREIRA ENDOTELIAL E SUA RELAÇÃO COM AS MANIFESTAÇÕES CLÍNICAS E LABORATORIAIS NA COVID-19

Objetivos

Os mecanismos fisiopatológicos que determinam a gravidade da Covid-19 estão associados a ativação da hemostasia e da imunidade inata, em um processo coletivamente referido como imunotrombose, e que envolve ativação plaquetária, geração de NETs (do inglês, Nucleo extracelular traps), expressão de fator tecidual, ativação do complemento e ativação endotelial. Um elemento importante da ativação endotelial é a quebra da barreira endotelial (BE), que ocorre para facilitar o acesso de leucócitos aos tecidos, onde contribuem para erradicação dos patógenos. No entanto, a avaliação da integridade da BE é desafiadora, exigindo o uso de modelos celulares. O objetivo desse estudo foi avaliar o efeito do soro de pacientes com Covid-19 sobre a integridade da BE em monocamadas de células endoteliais, e sua correlação com características clínicas da doença.

Materiais e métodos

A população do estudo consistiu em 30 pacientes com Covid-19 que apresentavam comprometimento pulmonar confirmado por tomografia de tórax, e necessidade de internação hospitalar por hipoxemia e 30 controles saudáveis pareados por sexo e idade. Os pacientes recrutados fizeram parte de um estudo clínico (REBEC: U1111-1250-1843), e as amostras utilizadas nesta avaliação foram obtidas no momento da internação, antes de qualquer intervenção. Monocamadas de células endoteliais de duas fontes (HUVECs: células de cordão umbilical; HULECs: células endoteliais pulmonares) foram estimuladas com soro de pacientes e indivíduos saudáveis (diluição 15% em meio de cultura) e a integridade da BE foi avaliada por um sensor de impedância celular (ECIS; Eletric Cell-substrate Impedance Sensing System) continuamente por 36 horas. Biomarcadores de gravidade e relacionados à ativação da hemostasia foram avaliados por kits comerciais. Dados clínicos foram obtidos a partir dos prontuários digitais.

Resultados

O soro de pacientes com Covid-19 induziu quebra de BE significativamente mais acentuada que o de indivíduos saudáveis em HUVECs nos tempos 15 min (p < 0,01); 30 min (p ≤ 0,001); 1h (p ≤ 0,0001); 2h (p ≤ 0,0001); 3h (p ≤ 0,0001); 4h (p ≤ 0,01) e 5h (p ≤ 0,05). Estes resultados foram confirmados no modelo de células endoteliais pulmonares (HULECs). A magnitude da quebra apresentou correlação significativa com desfechos clínicos relevantes como tempo de internação total (R_S até 0.57) e tempo de UTI (R_S = 0,47). Em relação a biomarcadores de interesse na Covid-19, a quebra da BE apresentou correlação significativa com neutrofilia, relação neutrófilo/linfócito, fator de Von Willebrand, fatores IX e XI, fibrinogênio, D-dímero e uPAR (Receptor de Uroquinase).

Discussão

Através de um método considerado padrão-ouro para avaliação in vitro da integridade da BE nós demonstramos que componentes presentes no soro de pacientes com Covid-19 são capazes de promover a quebra da BE, e que a magnitude deste processo está relacionada à gravidade desta doença. A correlação com outros marcadores inflamatórios corrobora a conexão entre os mecanismos envolvidos na imunotrombose em pacientes com Covid-19.

Conclusão

nossos resultados apontam a quebra da BE como um alvo terapêutico atrativo nestes pacientes.

AVALIAÇÃO DOS NÍVEIS CIRCULANTES DE MEDIADORES DA INTEGRIDADE DA BARREIRA ENDOTELIAL NA COVID-19 E SUA RELAÇÃO COM A ATIVAÇÃO DA HEMOSTASIA

Objetivos

a imunotrombose consiste no processo que envolve a ativação concomitante da imunidade inata, hemostasia e endotélio como parte da resposta a patógenos, e vem sendo colocada no centro da fisiopatologia da Covid-19. Um elemento menos explorado da imunotrombose é a ruptura da barreira endotelial (BE), que permite o acesso dos leucócitos aos tecidos inflamados. Entre os reguladores da integridade da BE destacam-se as vias que envolvem a angiopoietina (Ang) 1 e 2 e seu receptor Tie2, e a via do VEGF-A/VE-caderina (VEC). Além deste papel, foi recentemente demonstrado que a ativação da via Ang/Tie2 inibe a ativação endotelial e a expressão de fator tecidual, estabilizando o endotélio no estado quiescente. Neste estudo determinamos os níveis circulantes de mediadores da integridade da BE na Covid-19, e exploramos sua associação com a gravidade da doença, assim como com a ativação da hemostasia através de um painel abrangente de biomarcadores.

Materiais e métodos

as amostras foram obtidas de 30 pacientes internados por Covid-19 devido à hipoxemia e achados tomográficos típicos, e recrutados para um estudo clínico (REBEC: U1111-1250-1843). As amostras foram coletadas em até 24h do diagnóstico, antes de qualquer intervenção terapêutica. Os níveis de reguladores da BE foram medidos por métodos imunológicos (Elisa ou multiplex), e o de biomarcadores da hemostasia por kits comerciais específicos. Um grupo de 30 indivíduos saudáveis pareados por idade e sexo foram utilizados como controle. Dados clínicos e laboratoriais foram obtidos dos prontuários digitais.

Resultados

o tempo médio de internação foi de 12,9 ± 9,8 dias, e 12 pacientes (40%) necessitaram de UTI. O dímero D médio foi de 3.609 ± 14.440 ng/mL. Os níveis circulantes de todos reguladores da integridade da BE encontraram-se aumentados em pacientes, quando comparado com controles (Ang1: 463.2 ± 194.6 vs 237.4 ± 104.9 pg/mL, p < 0.0001; Ang2: 1.926 (1.275-3.134) vs 1.215 (9-1.444) pg/mL, p < 0.0001; Tie2: 10.753 ± 2.377 vs 8.603 ± 1.851 pg/mL, p < 0.0001 e VEGF-A: 94.7 (73.4-116.0) vs 45.9 (39.7-57.0), p < 0.0001. Além disso, os níveis de alguns destes reguladores se associaram significativamente a desfechos de relevância clínica, a saber: (i) extensão da lesão pulmonar na tomografia: Ang2 e VEGF-A; (ii) tempo de internação em UTI: VEGF-A. Interessantemente, observamos correlações consistentes e significativas entre os níveis de reguladores da BE a proteínas envolvidas na ativação da hemostasia (fibrinogênio, VWF: Ag, uPAR, PAI-1 e P-selectina).

Discussão

o interesse no estudo de reguladores da integridade da BE na Covid-19 já se justifica pelo fato de a doença envolver tanto o comprometimento da barreira alvéolo-capilar quanto a ativação da angiogênese, como demonstrado por outros autores. Nossos resultados reforçam a relevância destas vias através da associação observada com desfechos clínicos. Além disso, os resultados mostram pela primeira vez uma associação entre mediadores da integridade da BE e um painel amplo de biomarcadores da ativação da hemostasia, sugerindo um crosstalk entre estas vias na Covid-19, como demonstrado recentemente no contexto da sepse.

Conclusões

nossos resultados apontam que a via Ang/Tie2 deve ser considerada um alvo terapêutico atrativo na Covid-19, por representar um elemento central da imunotrombose nestes pacientes.

TIME COURSE OF THE DEVELOPMENT OF IMMUNOTHROMBOSIS DURING COVID-19 HOSPITALIZATION

Introduction

Hypercoagulability in COVID-19 has been attributed to immunothrombosis, a process that involves the formation of neutrophils extracellular traps (NETs). The moment of the COVID-19 evolution in which immunothrombosis mechanisms are triggered is not established. Aim: To describe the kinetics of NETs release during COVID-19 hospitalization associating with thrombosis and death.

Methods

We quantified citrullinated H3 and inflammatory cytokines (TNF-α, IL-6), markers of NETs release, on 4 time points during COVID-19 hospitalization (admission, day 4, day 8 and last day) between May and July 2020. The association between changes in these markers levels and clinical outcomes was determined.

Results

101 patients were included, the median days in-hospital were 15, 62% were men, 27% were obese, 43% were diabetic, 54% were hypertensive, 59% were critically ill, 11% had a thrombotic event and 21% died. IL-6 levels were high on admission in survivors (median 25.32, IQR 24.19-28.15) and non-survivors (median 24.19, IQR 12.51-27.19), but gradually decreased on day 4 (median 12.07, IQR 6.32-17.81), day 8 (median 9.34, IQR 5.18-17.59) and last day (median 8.64, IQR 4.81-14.89) in survivors. TNF-α levels remained 2 times higher in non-survivors: admission (median 1.60, IQR 0.64-2.26), day 4 (median 1.78, IQR 1.02-2.60), day 8 (median 1.65, IQR 0.93-2.5), last day (median 2.41, IQR 1.31-4.06); than in survivors: admission (median 0.81, IQR 0.52-1.26), day 4 (median 0.84, IQR 0.44-1.16), day 8 (median 0.72, IQR 0.44-1.24), last day (median 0.69, IQR 0.4-1.14). CitH3 levels were similar between non-survivors at the beginning of hospitalization: admission (median 1.03, IQR 0.43-4.34), day 4 (median 1.1, IQR 0.65-3.45); as for survivors: admission (median 1.20, IQR 0.45-2.60), day 4 (median 1.27, IQR 0.64-3.29). On day 8, citH3 increased by 3-fold (median 3.80, IQR 1.98-10.15) in non-survivors and 2-fold (median 2.60, IQR 1.22-5.01) in survivors. While IL-6 and TNF-α levels were similar between patients with and without thrombosis, citH3 levels increased shortly on day 4, before the occurrence of a thrombotic event: admission (median 1.64, IQR 0.44-4.14), day 4 (median 3.21, IQR 2.57-9.31); but it didn't change on non-thrombotic event patients: admission (median 1.05, IQR 0.44-2.50), day 4 (median 1.06, IQR 0.58-2.95).

Conclusion

Markers of inflammation and immunothrombosis were associated with poor outcomes in COVID-19; however, these disorders were detected in different moments during COVID-19 course. While an increased inflammatory response was observed since the beginning of hospitalization, markers of immunothrombosis arose latter during the course of the disease. Acknowledgment of the time-course of immunothrombosis development in COVID-19 is important for planning therapeutic strategies against this pathological process.

A retrospective analysis of 122 immune thrombocytopenia patients treated with dapsone: Efficacy, safety and factors associated with treatment response

BACKGROUND

The optimum second-line treatment or best sequence of treatments for immune thrombocytopenia (ITP) are yet to be determined. Our institution has accumulated extensive experience regarding the use of dapsone as second-line therapy for ITP.

OBJECTIVES

We aimed to assess the efficacy rate and safety of dapsone treatment in ITP patients.

PATIENTS/METHODS

Here we report our experience in a retrospective study, including 122 patients, with a median treatment duration with dapsone of 6 months and a median follow-up period of 3.4 years.

RESULTS

The overall response rate in this cohort was 66%, including 24% of complete responses. Among responders, in 24% a relapse occurred while on treatment. Therefore, a sustained response was observed in 51% of patients. Interestingly, 81% of the responders maintained the response after the interruption of treatment, for a median time of 26 months. Side effects were reported in 16% of the patients in this cohort and treatment was interrupted due to side effects in 11% of patients. The main cause in these cases was hemolytic anemia and methemoglobinemia. Reductions in hemoglobin levels during the use of dapsone were seen in 94% of the patients. Responders presented significantly greater reductions in their hemoglobin levels than nonresponders did: median hemoglobin drop of 1.9 g/dl vs. 1.2 g/dl (p = .004).

CONCLUSIONS

Our findings suggest that dapsone has adequate efficacy and is well tolerated. Although the mechanism of action is still unclear, our observation that the degree in the drop of hemoglobin is greater in responders suggest a possible role of the blockage of the reticuloendothelial system in the therapeutic effect of the drug.

Neutrophil activation and circulating neutrophil extracellular traps are increased in venous thromboembolism patients for at least one year after the clinical event

Neutrophil activation and neutrophil extracellular traps (NETs) have been associated with the pathogenesis of venous thromboembolism (VTE). Considering VTE-associated chronic sequelae, which suggest that some pathological mechanisms remain after the acute episode, we investigated whether neutrophil activation is increased in patients with a prior VTE at least one year before this investigation. Thirty-seven patients with prior VTE and 37 individuals with no history of VTE were included. Neutrophil activity was evaluated by the expression of the adhesive molecule activation-specific epitopes LFA-1 (CD11a) and MAC-1 (CD11b), chemotaxis, reactive oxygen species (ROS) and by MPO-DNA complexes as markers of NETs. The adhesive molecules sICAM-1 and sVCAM-1, involved in the cross talk between neutrophil and endothelial cells, were also evaluated. Patient neutrophils presented increased CD11a expression before and after TNF-α stimulus, whereas increased CD11b expression was observed only after TNF-α stimulus, as compared to controls. Neutrophil chemotaxis on both, basal state and after IL-8 stimulus, on circulating levels of sICAM-1 and sVCAM-1, and on MPO-DNA complexes were also increased in VTE patients. ROS release was similar between patients and controls. This is, to our knowledge, the first study to investigate neutrophil inflammatory activity in VTE patients a long period after an acute event (approximately 2 years). The results showed altered neutrophil activation patterns in these patients. While activated neutrophils can cause endothelial activation and injury, the activated endothelium can induce the release of NETs with consequent endothelial cytotoxicity, creating a vicious cycle of activation between neutrophils and endothelium that can lead to thrombosis.

Efficacy of a hypolipid diet in patients with primary antiphospholipid syndrome with dyslipidemia: a prospective study

Although dyslipidemia is associated with poorer prognosis in antiphospholipid syndrome (APS), the management of lipid disorders can be challenging. While statins may increase the bleeding risk associated with anticoagulation, the effectiveness of hypolipid diet (HD) has not yet been established in patients with autoimmune disorders. In this study, we evaluated whether HD is associated with decreases in cholesterol levels in patients with thrombotic primary APS (t-PAPS) and dyslipidemia. Nutritional and lipid profiles were assessed before HD was initiated (baseline) and after 3 and 6 months with HD. A 24-h dietary recall was applied to assess the adherence to the diet. Forty-four patients were included, mean age was 43 years (± 12.93) and 65% were female. After HD was started, the intake of carbohydrates, lipids, saturated fats and cholesterol decreased, whereas dietary fiber intake increased. Levels of total cholesterol (TC) and non-high density lipoprotein cholesterol (non-HDL-C) decreased after 3 and 6 months of HD, as compared to baseline (P = 0.007 and P = 0.008). Low-density lipoprotein cholesterol (LDL-C), triglycerides (TG), and high-density lipoprotein cholesterol (HDL-C) values did not change during the study period. The mean body mass index (BMI) decreased from 28.4 to 27.8 kg/m² after six months of HD (p < 0.0001). In subgroup analysis, the effects of HD were more pronounced in patients with high TC, LDL-C or non-HDL-C levels at baseline and in those without obesity or hypertension. Nutritional intervention is feasible among t-PAPS and could be an alternative therapy to modulate lipid metabolism in this population.

Inflammatory markers in thrombosis associated with primary antiphospholipid syndrome

The role of inflammation in thrombotic complications of primary antiphospholipid syndrome (PAPS) is controversial. The aim of this study was to evaluate levels of inflammation and coagulation markers in patients with thrombotic PAPS (t-PAPS). Patients with t-PAPS and individuals with no history of thrombosis were enrolled. The association of t-PAPS with levels of tumor necrosis factor (TNF)-α, C-reactive protein (hs-CRP), interferon (IFN)-α, interleukins (IL)-6, -8, factor VIII (FVIII), von Willebrand factor (VWF) and tissue factor (TF) was evaluated by regression models. The levels of these markers were also compared between controls and subgroups of t-PAPS patients with triple positivity, recently diagnosed thrombosis, recurrent thrombosis and venous thrombosis. Patients with t-PAPS (n = 101) had a 8.6-fold increased levels of TNF-α, 90% increased levels of hs-CRP, 80% increased levels of IL-6, 30% increased levels of FVIIIAg, 50% increased levels of VWF and 66% increased levels of TF as compared to controls (n = 131), and the differences did not change after adjustments for sex, age and cardiovascular risk factors. Inflammatory markers were elevated in t-PAPS regardless of the aPL profile, number of previous thrombosis or time elapsed since diagnosis. TNF-α and IL-8 levels were higher in t-PAPS patients with venous thrombosis, in comparison with those with arterial thrombosis and controls. Patients with t-PAPS presented with increased levels of inflammatory and coagulation markers, which suggests that t-PAPS is associated not only with hypercoagulability but also with a persistent inflammatory state.

Glucocorticoid use and risk of first and recurrent venous thromboembolism: self-controlled case-series and cohort study

Glucocorticoid treatment increases venous thromboembolism (VTE) risk. Whether this is due to the medication or the underlying disease, or affects the risk of VTE recurrence, has been difficult to determine. The aim of our present study was to quantify the risk for first and recurrent VTE associated with oral glucocorticoids use, considering the underlying disease. A total of 2547 patients with VTE from the Multiple Environmental and Genetic Assessment of Risk Factors for Venous Thrombosis (MEGA) study were linked to the Dutch Pharmaceutical Statistics register. The risk of first VTE during periods of exposure with oral glucocorticoids was estimated by the self‐controlled case series method and that of recurrent VTE was examined in a cohort design. The incidence rate ratio (IRR) of first VTE in the period of glucocorticoid treatment was 3·51 [95% confidence interval (CI) 2·55–4·80]. This IRR was 2·53 (95% CI 1·10–5·72) in the week before treatment started, 5·28 (95% CI 2·89–9·53) in the first 7 days of treatment, remained elevated afterwards and decreased to 1·55 (95% CI 0·85–3·12) after 6 months, as compared to unexposed periods. The hazard ratio for recurrence was 2·72 (95% CI 1·64–4·78) in treatment periods as compared with no treatment. The increased risk of VTE associated with oral glucocorticoid treatment is due to a combined effect of the treatment and the underlying disease, remaining high during the first months of prescription.

Association of apolipoproteins C-I, C-II, C-III and E with coagulation markers and venous thromboembolism risk

Purpose

Apolipoproteins C-I, C-II, C-III and E have been associated with risk of arterial thrombotic diseases. We investigated whether these apolipoproteins have prothrombotic properties and are associated with risk of venous thromboembolism (VTE).

Patients and methods

A total of 127 VTE patients and 299 controls were randomly selected from the Multiple Environmental and Genetic Assessment of Risk Factors for Venous Thrombosis study (1999–2004), in the Netherlands. The apolipoproteins were quantified using mass spectrometry (LC/MS/MS), and their levels were analyzed as continuous variable (per SD increase).

Results

In controls, increases in levels of apolipoproteins were associated with increases in levels of vitamin K-dependent factors, factor XI, antithrombin and clot lysis time. Additionally, increasing apolipoproteins C-III and E levels were associated with higher factor VIII and von Willebrand factor levels. Levels of C-reactive protein were not associated with any apolipoprotein. The age- and sex-adjusted odds ratios of apolipoproteins E, C-III, CII and CI to the risk of venous thrombosis were 1.21 (95% CI, 0.98–1.49), 1.19 (95% CI, 0.99–1.44), 1.24 (95% CI, 0.95–1.61) and 1.06 (95% CI, 0.87–1.30) per SD increase, respectively. These odds ratios did not attenuate after adjustments for statin use, estrogen use, BMI, alcohol use, and self-reported diabetes.

Conclusions

Levels of apolipoproteins C-I, C-II, C-III and E are associated with those of several coagulation factors. However, whether these apolipoproteins are also associated with an increased risk of VTE remains to be established.

Statin Therapy to Revert Hypercoagulability and Prevent Venous Thromboembolism: A Narrative Review

Venous thromboembolism (VTE) causes a major disease burden worldwide, so that effective preventive measures are warranted. Although oral anticoagulation is effective in preventing VTE episodes, bleeding complications are a major concern that may lead to treatment avoidance. Statin therapy, which is widely used for prevention of arterial cardiovascular disease, is a promising alternative treatment for VTE prophylaxis, as the drug may affect hemostasis without increasing the risk of bleeding. In the past years, clinical studies have suggested that statins can interfere with blood coagulation and, in turn, reduce the risk of VTE. These effects, however, are still regarded with skepticism, as the underlying mechanisms by which statins may affect hemostasis in humans are not clear and data showing that statin therapy reduces VTE risk mostly came from observational studies, while only one randomized trial was conducted to evaluate this issue. In this review, the authors summarize the currently available evidence regarding the effect of statin therapy on coagulation and on VTE prevention. Recent randomized data showed that statin therapy, in particular rosuvastatin, leads to decreased levels of coagulation factors in patients with prior VTE. This evidence provides a reasonable basis for interventional studies necessary to establish the efficacy of statins on reducing the risk of incident and recurrent VTE.

Rosuvastatin use reduces thrombin generation potential in patients with venous thromboembolism: a randomized controlled trial

Essentials The role of statins in hemostasis and venous thromboembolism (VTE) prophylaxis is not clear. This trial assessed whether rosuvastatin use affects thrombin generation in patients with VTE. Endogenous thrombin potential and peak were decreased by 10% and 5% with rosuvastatin therapy. These results provide basis for trials on the efficacy of statins in reducing recurrent VTE risk. SUMMARY: Background Statin therapy could form an alternative prophylactic treatment for venous thromboembolism (VTE) if statins are proven to downregulate hemostasis and prevent recurrent VTE, without increasing bleeding risk. Objectives The STAtins Reduce Thrombophilia (START) trial investigated whether statin affects coagulation in patients with prior VTE. Patients/methods After anticoagulation withdrawal, patients were randomized to rosuvastatin 20 mg day-1 for 4 weeks or no intervention. Plasma samples taken at baseline and at the end of the study were analyzed employing thrombin generation assay. Results and conclusions The study comprised 126 rosuvastatin users and 119 non-users. Mean age was 58 years, 61% were men, 49% had unprovoked VTE and 75% had cardiovascular (CV) risk factors. Endogenous thrombin potential (ETP) increased from baseline to end of study in non-statin users (mean 97.22 nm*min; 95% CI, 40.92-153.53) and decreased in rosuvastatin users (mean -24.94 nm*min; 95% CI, -71.81 to 21.93). The mean difference in ETP change between treatments was -120.24 nm*min (95% CI, -192.97 to -47.51), yielding a 10.4% ETP reduction by rosuvastatin. The thrombin peak increased in both non-statin (mean 20.69 nm; 95% CI, 9.80-31.58) and rosuvastatin users (mean 8.41 nm; 95% CI -0.86 to 17.69). The mean difference in peak change between treatments was -11.88 nm (95% CI, -26.11 to 2.35), yielding a 5% peak reduction by rosuvastatin. Other thrombin generation parameters did not change substantially. The reduction in ETP and peak by rosuvastatin was more pronounced in the subgroups of participants with CV risk factors and with unprovoked VTE. We conclude that rosuvastatin reduces thrombin generation potential in patients who had VTE.

Evaluation of the immature platelet fraction contribute to the differential diagnosis of hereditary, immune and other acquired thrombocytopenias

The differential diagnosis of immune (ITP) and hereditary macrothrombocytopenia (HM) is key to patient management. The immature platelet fraction (IPF) represents the subset of circulating platelets with higher RNA content, and has been shown to distinguish hypo- from hyperproliferative thrombocytopenias. Here we evaluated the diagnostic accuracy of IPF in the differential diagnosis between HM and other thrombocytopenias in a population of patients with post-chemotherapy thrombocytopenia (n = 56), bone marrow failure (n = 22), ITP (n = 105) and HM (n = 27). TPO levels were also measured in HM and ITP matched for platelet counts. Platelet counts were similar in all patient groups. Higher IPF values were observed in both ITP (12.3%; 2.4–65.6%) and HM (29.8%; 4.6–65.9%) compared to hypoproliferative thrombocytopenias. IPF values were also higher in HM compared to ITP, yielding a diagnostic accuracy of 0.80 (95%CI 0.70–0.90; P < 0.0001) to distinguish these two conditions. Intra- and inter-assays reproducibility of IPF in HM patients revealed that this is a stable parameter. In conclusion, IPF is increased in HM compared to both ITP and other thrombocytopenias and contributes to the differentiation between ITP and HM. Further studies are warranted to understand the biological rationale of these findings and to its incorporation in diagnostic algorithms of HM.

Increased adhesive properties of neutrophils and inflammatory markers in venous thromboembolism patients with residual vein occlusion and high D-dimer levels

BACKGROUND

Venous thromboembolism (VTE) develops via a multicellular process on the endothelial surface. Although widely recognized, the relationship between inflammation and thrombosis, this relationship has been mostly explored in clinical studies by measuring circulating levels of inflammatory cytokines. However, the role of inflammatory cells, such as neutrophils, in the pathogenesis of VTE is not clear in humans.

AIMS

To evaluate the adhesive properties of neutrophils, erythrocytes and platelets in VTE patients and to correlate findings with inflammatory and hypercoagulability marker levels.

METHODS

Study group consisted of twenty-nine VTE patients and controls matched according to age, gender and ethnic background. Adhesive properties of neutrophils, erythrocytes and platelets were determined using a static adhesion assay. Neutrophil adhesion molecules expressions were evaluated by flow cytometry. Inflammatory and hypercoagulability marker levels were evaluated by standard methods. Residual vein occlusion (RVO) was evaluated by Doppler ultrasound.

RESULTS

No significant difference could be observed in platelet and erythrocyte adhesion between VTE patients and controls. Interestingly, VTE patients with high levels of D-dimer and RVO, demonstrated a significant increase in neutrophil adhesion, compared to controls and remaining patients. Inflammatory markers (IL-6, IL-8, TNF-α) were also significantly elevated in this subgroup, compared to other VTE patients. Adhesive properties of neutrophils correlated with IL-6 and D-dimer levels. Neutrophils adhesion molecules (CD11a, CD11b and CD18) were not altered in any of the groups.

CONCLUSION

These findings not only support the hypothesis of an association between inflammation and hypercoagulability, but more importantly, highlight the role of neutrophils in this process.

Reduced thrombin formation and excessive fibrinolysis are associated with bleeding complications in patients with dengue fever: a case-control study comparing dengue fever patients with and without bleeding manifestations

Background

Dengue cases have been classified according to disease severity into dengue fever (DF) and dengue hemorrhagic fever (DHF). Although DF is considered a non-severe manifestation of dengue, it has been recently demonstrated that DF represents a heterogeneous group of patients with varied clinical complications and grades of severity. Particularly, bleeding complications, commonly associated to DHF, can be detected in half of the patients with DF. Although a frequent complication, the causes of bleedings in DF have not been fully addressed. Thus, the aim of this study was to perform a comprehensive evaluation of possible pathophysiological mechanisms that could contribute to the bleeding tendency observed in patients with DF.

Methods

This is a case–control study that enrolled adults with DF without bleeding and adults with DF and bleeding complications during the defervescence period. Healthy controls were also included. Peripheral blood counts, inflammatory, fibrinolysis and endothelial cell activation markers, and thrombin generation were evaluated in patients and controls.

Results

We included 33 adults with DF without complications, 26 adults with DF and bleeding and 67 healthy controls. Bleeding episodes were mild in 15 (57.6%) and moderate in 11 (42.4%) patients, 8 (30.7%) patients had bleedings in multiple sites. Patients with DF and bleedings had lower platelet counts than DF without bleeding (median = 19,500 vs. 203,500/mm3, P < 0,0001). Levels of TNF-α, thrombomodulin and VWF were significantly increased in the two dengue groups than in healthy controls, but similar between patients with and without bleedings. Plasma levels of tPA and D-dimer were significantly increased in patients with bleedings (median tPA levels were 4.5, 5.2, 11.7 ng/ml, P < 0.0001 and median D-dimer levels were 515.5, 1028 and 1927 ng/ml, P < 0.0001). The thrombin generation test showed that patients with bleeding complications had reduced thrombin formation (total thrombin generated were 3753.4 in controls, 3367.5 in non-bleeding and 2274.5nM in bleeding patients, P < 0.002).

Conclusions

DF can manifest with spontaneous bleedings, which are associated with specific coagulation and fibrinolysis profiles that are not significantly present in DF without this complication. Particularly, thrombocytopenia, excessive fibrinolysis and reduced thrombin formation may contribute to the bleeding manifestations in DF.

VKORC1 V66M mutation in African Brazilian patients resistant to oral anticoagulant therapy

Warfarin-based anticoagulant therapy is associated with large variability in dose response. Genetic variability in the VKORC1 and CYP2C9 genes is associated with increased warfarin sensitivity. In addition, rare coding region mutations in VKORC1 have been associated with resistance to warfarin. VKORC1 and CYP2C9 variability associated with altered warfarin response is less well characterized in African and mixed-raced populations such as Brazilians. To determine genetic variability associated with altered warfarin response among Brazilian patients, sixty-two adult patients with extreme resistance or sensitivity to warfarin were genotyped for variants in CYP2C9 and VKORC1. Of the 51 patients on low doses of warfarin, the VKORC1--1639 (3673) G>A polymorphism associated with warfarin sensitivity was present in 48 (94.1%), including 97% of Caucasians, 82% of African-descent patients, and all 7 (100%) patients of Indian descent. Additionally, 52.9% of warfarin sensitive patients had at least one CYP2C9*2 or CYP2C9*3 decreased metabolism allele, 63.6% of Caucasians and 54% of African-descent patients. Of the 11 patients on high doses of warfarin, sequencing of VKORC1 revealed a nonsynonymous V66M mutation in two warfarin resistant patients, both of African-descent. Brazilian patients requiring low doses of warfarin have a high frequency of VKORC1 and CYP2C9 variants associated with warfarin sensitivity. The presence of the rare VKORC1 V66M in two warfarin high dose outlier patients implies that this variant may be more frequent among African Brazilians and has implications for future warfarin studies in other populations of African descent.