Antiphospholipid antibodies in convalescent plasma of donors recovered from mild COVID-19 infection.

BACKGROUND AND OBJECTIVES: Passive immunization by the infusion of convalescent plasma (CP) obtained from patients who have recently recovered from COVID-19, thus having antibodies to severe acute respiratory syndrome coronavirus 2, is a potential strategy to reduce the severity of illness. A high prevalence of antiphospholipid antibodies (APLA) in patients with COVID-19 has been reported during the pandemic, raising a concern whether the use of CP could increase the risk of thrombosis in transfused patients. We aimed to evaluate the prevalence of APLA in COVID-19 CP (CCP) in order to assess the potential prothrombotic influence of transfused CCP to COVID-19 patients. MATERIALS AND METHODS: We studied the prevalence of APLA in 122 CCP samples collected from healthy donors who recovered from mild-COVID-19 at two time periods: September 2020-January 2021 (defined as 'early period' samples) and April-May 2021 (defined as 'late period' samples). Thirty-four healthy subjects unexposed to COVID-19 were used as controls. RESULTS: APLA were present in 7 of 122 (6%) CCP samples. One donor had anti-ß2-glycoprotein 1(anti-ß2GP1) IgG, one had anti-ß2GP1 IgM and five had lupus anticoagulant (LAC) using silica clotting time (SCT), all in 'late period' donors. In the control group, one subject had anti-ß2GP1 IgG, two had LAC using dilute Russell viper venom time (dRVVT) and four had LAC SCT (both LAC SCT and LAC dRVVT in one subject). CONCLUSION: The low prevalence of APLA in CCP donors reassures the safety of CCP administration to patients with severe COVID-19.

International Normalized Ratio as a Screening Test for Assessment of Anticoagulant Activity for Patients Treated With Rivaroxaban or Apixaban: A Pilot Study.

Introduction: In patients treated with direct oral anti activated factor X (anti-FXa) anticoagulants such as apixaban and rivaroxaban, there are several emergency and non-emergency conditions in which anticoagulation activity should be measured. The validity of the common global clotting tests, prothrombin time and international normalized ratio (PT/INR) for determination of blood levels of these drugs, has been widely investigated. As the anticoagulation activity evaluation "calibrated anti-FXa" of these drugs is relatively more expensive and less available, we aimed to build a prediction model for anticoagulation activity assessment based on INR values. Methods and Findings: One hundred sixty samples from 80 hospitalized patients treated with apixaban or rivaroxaban were tested using PT/INR and Anti-FXa chromogenic assay. Two blood samples, trough and peak, were collected from each subject. Participants were randomly divided into two equal groups. One group (n = 40) was used to build the model, which was validated by the second group (n = 40). There was a strong correlation between anti-FXa concentrations and INR in rivaroxaban treated patients (r = 0.899, p < 0.001). Therefore, we were able to build a formula for rivaroxaban patient group which reliably represent the relationship between these two parameters. The correlation in apixaban treated patients was less predictive (r = 0.798, p < 0.001) and the formula suggested could not be validated. Conclusions: In our study, we developed a formula that estimates the anticoagulant activity of rivaroxaban by obtaining INR values. Where anti-FXa assay is unavailable, our proposed formula may be considered as a screening test for rivaroxaban.

Prevalence of Paroxysmal Nocturnal Hemoglobinuria Clones in Myeloproliferative Neoplasm Patients: A Cross-Sectional Study.

INTRODUCTION: The myeloproliferative neoplasms (MPN) are clonal diseases that confer an increased risk of thrombohemorrhagic complications. Paroxysmal nocturnal hemoglobinuria (PNH) is a rare clonal disease associated with an increased thrombotic risk. Small PNH clones are prevalent in aplastic anemia and myelodysplastic syndrome patients, but their prevalence in MPN patients is unknown. PATIENTS AND METHODS: Consecutive patients with MPN followed up at a single center were recruited. PNH clones were analyzed in erythrocytes and white blood cells by flow cytometry. RESULTS: PNH clones were detected in 2% of patients and were more common in JAK2 V617F positive patients. We could not detect any differences in clinical manifestations or complications in patients either with or without PNH clones because of the small patient numbers. CONCLUSION: The prevalence of PNH clones in MPN is similar to that described in myelodysplastic syndromes. Whether PNH clones influence MPN phenotype and complications should be studied prospectively in larger patient cohorts and over long-term follow-up.

Differential regulation of astrocyte prostaglandin response by kinins: possible role for mitogen activated protein kinases.

The role of kinins, well known as peripheral inflammatory mediators, in the modulation of brain inflammation is not completely understood. The present data show that bradykinin, a B2 receptor agonist, enhanced both basal and lipopolysaccharide (LPS)-induced cyclooxygenase-2 mRNA and protein levels and prostaglandin E2 synthesis in primary rat astrocytes. By contrast, Lys-des-Arg(9)-bradykinin, which is a bradykinin breakdown product and a selective kinin B1 receptor agonist, attenuated both basal and LPS-induced astrocyte cyclooxygenase-2 mRNA levels and prostaglandin E2 production. Pre-treating the cells with p42/p44 MAPK but not with JNK or p38 inhibitors completely abrogated PGE2 synthesis in cells stimulated with LPS in the presence of bradykinin or bradykinin B1 receptor agonist. Bradykinin, but not the bradykinin B1 receptor agonist, augmented p42/p44 MAPK phosphorylation. The phosphorylation of JNK and p38 was not altered upon exposure to Bradykinin or the bradykinin B1 receptor agonist. These results suggest that the dual delayed effect of kinins on PGE2 synthesis may be due to differential regulation of COX-2 and signaling molecules such as p42/p44 MAPKs. Thus, kinins may exert opposing actions on brain inflammation and neurodegenerative diseases.

Distinct modulation of microglial amyloid ß phagocytosis and migration by neuropeptides (i).

Microglial activation plays an integral role in the development and course of neurodegeneration. Although neuropeptides such as bradykinin (BK), somatostatin (SST), and endothelin (ET) are known to be important mediators of inflammation in the periphery, evidence of a similar function in brain is scarce. Using immunocytochemistry, we demonstrate the expression of receptors for BK (B1, B2 subtypes), ET (ETA, ETB subtypes) and SST (SST 2, 3, 4 subtypes) in primary microglia and microglial cell lines. Exposure of BV2 and N9, as well as primary microglial cells to BK or SST increased Aß uptake in a concentration-dependent manner, whereas endothelin decreased Aß uptake. This was caused by increased phagocytosis of Aß since the rate of intracellular Aß degradation remained unaffected. All neuropeptides increased chemotactic activity of microglia. In addition, BK reduced Aß-induced expression of proinflammatory genes including iNOS and COX-2. ET decreased the Aß-induced expression of monocyte chemoattractant protein 1 and interleukin-6. These results suggest that neuropeptides play an important role in chemotaxis and Aß clearance and modulate the brain's response to neuroinflammatory processes.

Glial response to lipopolysaccharide: possible role of endothelins.

Glial inflammation plays a major role in the development of neurodegenerative diseases. Although endothelins (ETs) are known as modulators of inflammation in the periphery, little is known about their possible role in brain inflammation. Previously, we demonstrated that all three endothelins (ET-1, ET-2 and ET-3) enhanced unstimulated synthesis of the glial pro-inflammatory mediators, prostaglandin E2 (PGE2) and nitric oxide (NO). In the present study, glial cells were stimulated in an in vitro model of inflammation by incubation with the bacterial endotoxin lipopolysaccharide (LPS). Indeed, the present study shows that ETs regulate basal and LPS-induced glial inflammation in an opposite fashion. Here we demonstrate that ETs significantly inhibited the LPS-induced glial synthesis of PGE2 and NO, and each of the selective antagonists for ETA and ETB receptors (BQ123 and BQ788 respectively), significantly inhibited the ETs effects in LPS-treated cells. Similar results were observed when expression of key enzymes namely, cyclooxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS) in PG and NO synthesis respectively, was measured. ET-1 significantly enhanced the expression of both COX-2 and iNOS. Whereas, it inhibited the LPS-induced expression of both enzymes. These observations suggest a novel neuro-immune feedback pathway through which inflammatory mediators' synthesis is initially enhanced by ETs and are eventually blocked by the same neuropeptide when excessive production of inflammatory mediators occurs following an inflammatory insult.

Protein synthesis dependent effects of kinins on astrocyte prostaglandin synthesis.

It has been shown that kinins and their receptors are over expressed in the brain under pathophysiological conditions such as inflammation. However, little is known about the possible role of kinins, and especially bradykinin in brain inflammation. Although kinins are thought to have immediate effects, peptides may also exert longer and protein synthesis dependent actions. To evaluate this possibility, we assessed the regulation of prostaglandin E(2) synthesis after 15h bradykinin or Lys-des-Arg(9)-bradykinin (B(1) receptor agonist) treatment in rat neonatal astrocytes. Bradykinin, dose dependently stimulated basal and lipopolysaccharide-induced prostaglandin E(2) production, whereas exposure of astrocytes to the B(1) receptor agonist decreased both basal and lipopolysaccharide-induced prostaglandin E(2) release in a dose-dependent manner. These kinin effects on PGE(2) synthesis were completely abrogated by actinomycin-D and cycloheximide, suggesting de novo synthesis of proteins. Bradykinin also increased cyclooxygenase-2 protein levels about 2-fold, while the B(1) receptor agonist decreased cyclooxygenase-2 protein expression. There was no change in cyclooxygenase-1 protein levels after treatment with either of the kinins. Our data suggest a delayed feedback regulatory mechanism of kinins on astrocyte inflammation, whereby astrocyte prostaglandin synthesis is initially enhanced by bradykinin (B(2)) and eventually blocked by kinin breakdown product, acting on B(1) receptors. At least part of this presumed feedback loop could be mediated by de novo protein synthesis of cyclooxygenase-2.