VE-Cadherin is involved in endothelial cell detachment during Thrombotic Thrombocytopenic Purpura.

BACKGROUND AND OBJECTIVES: Immune Thrombotic thrombocytopenic purpura (i-TTP) is a life-threatening thrombotic microangiopathie linked to ADAMTS13 deficiency. It has long been assumed that the activation of endothelial cells is the triggering factor for the TTP crisis. Circulating endothelial cells (CEC) have been shown to be a biomarker of vascular damage and are associated with the clinical severity of i-TTP. However, the mechanisms leading to endothelial cell detachment remain unclear. OBJECTIVES: We have investigated junctional destabilization and the mechanisms underlying cell detachment in TTP. METHODS AND RESULTS: In plasma from i-TTP patients, we show that CEC count is associated with severity and correlated to intracellular calcium influx (p<0.01). In vitro, serum from i-TTP patients induced stronger detachment of human umbilical vein endothelial cells (HUVECs) than serum from control patients (p<0.001). Plasma from i-TTP patients induced a higher calcium-dependent phosphorylation (p<0.05) and internalization (p<0.05) of VE-cadherin compared to plasma from control patients. This effect could be reproduced by IgG fraction isolated from patient plasma and in particular by the F(ab)'2 fragments of the corresponding IgG. In addition, subcutaneous injection of i-TTP plasma into mice resulted in higher vascular permeability than plasma from control patients. An inhibitor of endothelial calcium influx, ITF1697, normalized this increase in permeability. CONCLUSIONS: Our results suggest that plasma-induced endothelial activation also leads to an increase in vascular permeability. They contribute to the understanding of the mechanisms behind the presence of elevated CECs in patients' blood by linking endothelial activation to endothelial injury.

Tell-tale immune-related neurological syndromes: Should we look for and underlying low-grade B-cell lymphoma? A retrospective study on 12 cases.

INTRODUCTION: Immune-related neurological syndromes (affecting both the central and peripheral nervous system, as well as the neuromuscular junction) can associate with low-grade B-cell lymphomas. METHODS: We conducted a retrospective study on the records of patients with miscellaneous immune-related neuropathies followed by the "Referral Centre for Neuromuscular Diseases and ALS" in collaboration with the Services of Internal Medicine and Hematology (La Timone Hospital, and the Paoli Calmettes-Insitute, Marseille, France; Geneva University Hospitals, Geneva, Switzerland). Clinical, biological, immunological and histological work-up was carried out and data collected. RESULTS: We identified 12 patients with neurological syndromes and atypical presentation/course. In all these patients multiple autoantibodies were found. This prompted us to perform thorough hematologic investigations, that led to the diagnosis of different type of Low-Grade B-Cell lymphomas [i.e. marginal zone lymphomas with lymphoplasmacytic differentiation (n=3), splenic marginal area lymphoma with secondary lymph node invasion (n=1), unclassified marginal area lymphomas (n=8)]. Treatment of the underling lymphoma resulted in an improvement (n=8) or stabilization (n=4) of neurological disease. CONCLUSION: Atypical presentation of immune-related neurological syndromes, as well as the presence of antibodies with different antigenic targets should be regarded as "warning signs" and raise the suspicion of a paraneoplastic origin sustained by an underlying low-grade B-cell lymphoma that should be actively sought and treated. Close collaboration between internists, neurologists and hematologists allows for the appropriate management of each case.

Polymyalgia rheumatica and giant cell arteritis following COVID-19 vaccination: Results from a nationwide survey.

We conducted a national in-depth analysis including pharmacovigilance reports and clinical study to assess the reporting rate (RR) and to determine the clinical profile of polymyalgia rheumatica (PMR) and giant cell arteritis (GCA) in COVID-19-vaccinated individuals. First, based on the French pharmacovigilance database, we estimated the RR of PMR and GCA cases in individuals aged over 50 who developed their initial symptoms within one month of receiving the BNT162b2 mRNA, mRNA-1273, ChAdOx1 nCoV-19, and Ad26.COV2.S vaccines. We then conducted a nationwide survey to gather clinical profiles, therapeutic management, and follow-up data from individuals registered in the pharmacovigilance study. A total of 70 854 684 COVID-19 vaccine doses were administered to 25 260 485 adults, among which, 179 cases of PMR (RR 7. 1 cases/1 000 000 persons) and 54 cases of GCA (RR 2. 1 cases/1 000 000 persons) have been reported. The nationwide survey allowed the characterization of 60 PMR and 35 GCA cases. Median time to the onset of first symptoms was 10 (range 2-30) and 7 (range 2-25) days for PMR and GCA, respectively. Phenotype, GCA-related ischemic complications and -large vessel vasculitis as well as therapeutic management and follow-up seemed similar according to the number of vaccine shots received and when compared to the literature data of unvaccinated population. Although rare, the short time between immunization and the onset of first symptoms of PMR and GCA suggests a temporal association. Physician should be aware of this potential vaccine-related phenomenon.

Reduction of mortality, cardiac damage, and cerebral damage by IL-1 inhibition in a murine model of TTP.

ABSTRACT: Thrombotic thrombocytopenic purpura (TTP), a rare but fatal disease if untreated, is due to alteration in von Willebrand factor cleavage resulting in capillary microthrombus formation and ischemic organ damage. Interleukin-1 (IL-1) has been shown to drive sterile inflammation after ischemia and could play an essential contribution to postischemic organ damage in TTP. Our objectives were to evaluate IL-1 involvement during TTP and to test the efficacy of the recombinant IL-1 receptor antagonist, anakinra, in a murine TTP model. We retrospectively measured plasma IL-1 concentrations in patients with TTP and controls. Patients with TTP exhibited elevated plasma IL-1α and -1ß concentrations, which correlated with disease course and survival. In a mouse model of TTP, we administered anakinra (IL-1 inhibitor) or placebo for 5 days and evaluated the efficacy of this treatment. Anakinra significantly reduced mortality of mice (P < .001). Anakinra significantly decreased TTP-induced cardiac damage as assessed by blood troponin concentrations, evaluation of left ventricular function by echocardiography, [18F]fluorodeoxyglucose positron emission tomography of myocardial glucose metabolism, and cardiac histology. Anakinra also significantly reduced brain TTP-induced damage evaluated through blood PS100b concentrations, nuclear imaging, and histology. We finally showed that IL-1α and -1ß trigger endothelial degranulation in vitro, leading to the release of von Willebrand factor. In conclusion, anakinra significantly reduced TTP mortality in a preclinical model of the disease by inhibiting both endothelial degranulation and postischemic inflammation, supporting further evaluations in humans.

Diagnosis of thrombotic thrombocytopenic purpura: easy-to-use fiber optic surface plasmon resonance immunoassays for automated ADAMTS-13 antigen and conformation evaluation.

BACKGROUND: Laboratory diagnosis of immune-mediated thrombotic thrombocytopenic purpura (iTTP) remains challenging when ADAMTS-13 activity ranges between 10% and 20%. To prevent misdiagnosis, open ADAMTS-13 conformation gained clinical attention as a novel biomarker, especially to diagnose acute iTTP in patients with diagnostic undecisive ADAMTS-13 activity. Plasma ADAMTS-13 conformation analysis corrects for ADAMTS-13 antigen, with both parameters being characterized in enzyme-linked immunosorbent assay (ELISA)-based reference assays requiring expert technicians. OBJECTIVES: To design ADAMTS-13 antigen and conformation assays on automated, easy-to-use fiber optic surface plasmon resonance (FO-SPR) technology to promote assay accessibility and diagnose challenging iTTP patients. METHODS: ADAMTS-13 antigen and conformation assays were designed on FO-SPR technology. Plasma of 20 healthy donors and 20 acute iTTP patients were quantified, and data from FO-SPR and ELISA reference assays were compared. RESULTS: Following assay design, both antigen and conformation FO-SPR assays were optimized and characterized, presenting strong analytical sensitivity (detection limit of 0.001 µg/mL) and repeatability (interassay variation of 14.4%). Comparative analysis suggested positive correlation (Spearman r of 0.92) and good agreement between FO-SPR and ELISA assays. As expected, FO-SPR assays showed a closed or open ADAMTS-13 conformation in healthy donors and acute iTTP patients, respectively. CONCLUSION: Both ADAMTS-13 antigen and conformation assays were transferred onto automated, easy-to-use FO-SPR technology, displaying potent analytical sensitivity and reproducibility. ADAMTS-13 antigen and conformation were determined for healthy donors and acute iTTP patients showing strong correlation with ELISA reference. Introducing FO-SPR technology in clinical context could support routine diagnosis of acute iTTP patients, notably when ADAMTS-13 activity fluctuates between 10% and 20%.

Molecular B-cell clonality assay in minor salivary glands as a useful tool for the lymphoma risk assessment in Sjögren's syndrome.

OBJECTIVES: Non-Hodgkin's lymphoma (NHL) risk assessment is crucial in Sjögren's syndrome (SS). We studied the prevalence of clonal immunoglobulin gene rearrangements in minor salivary glands (MSG) and their correlations with lymphoma occurrence and with previously established NHL predictors. METHODS: Molecular B-cell expansion was studied in fresh-frozen MSG of 207 patients with either suspected SS or with suspected lymphoma during SS, using a standardised multiplex PCR assay combined with heteroduplex analysis by microcapillary electrophoresis. The assignation of clonal cases was based on EuroClonality consortium guidelines. RESULTS: Among 207 studied patients, 31 (15%) had MSG monoclonal B-cell infiltration. Monoclonality was significantly more frequent in patients with SS (28/123, 22.8%) compared with patients without SS (3/84, 3.6%, P<0.001). Monoclonal B-cell infiltration in MSG of SS patients correlated significantly with ongoing salivary gland NHL, salivary gland swelling, CD4+ T-cell lymphopenia, rheumatoid factor (RF) activity, low complement levels and type 2 mixed cryoglobulinemia. The accumulation of biological risk factors was associated with a higher rate of MSG B-cell monoclonality given that patients with only positive RF had no probability of MSG B-cell monoclonality, RF-positive patients with 1 or 2 other risk factors had a 25.0% and 85.7% probability of MSG B-cell monoclonality, respectively. CONCLUSION: The detection of MSG monoclonal B-cell expansion by this easy-to-perform molecular assay is useful, both at the time of diagnosis and during the course of SS. Monoclonal B-cell expansion is associated with a subset of SS patients presenting either ongoing lymphoma or other established lymphoma predictive factors.

Macrophage IL-1ß-positive microvesicles exhibit thrombo-inflammatory properties and are detectable in patients with active juvenile idiopathic arthritis.

Objective: IL-1ß is a leaderless cytokine with poorly known secretory mechanisms that is barely detectable in serum of patients, including those with an IL-1ß-mediated disease such as systemic juvenile idiopathic arthritis (sJIA). Leukocyte microvesicles (MVs) may be a mechanism of IL-1ß secretion. The first objective of our study was to characterize IL-1ß-positive MVs obtained from macrophage cell culture supernatants and to investigate their biological functions in vitro and in vivo. The second objective was to detect circulating IL-1ß-positive MVs in JIA patients. Methods: MVs were purified by serial centrifugations from PBMCs, or THP-1 differentiated into macrophages, then stimulated with LPS ± ATP. MV content was analyzed for the presence of IL-1ß, NLRP3 inflammasome, caspase-1, P2X7 receptor, and tissue factor (TF) using ELISA, Western blot, or flow cytometry. MV biological properties were studied in vitro by measuring VCAM-1, ICAM-1, and E-selectin expression after HUVEC co-culture and factor-Xa generation test was realized. In vivo, MVs' ability to recruit leukocytes in a murine model of peritonitis was evaluated. Plasmatic IL-1ß-positive MVs were studied ex vivo in 10 active JIA patients using flow cytometry. Results: THP-1-derived macrophages stimulated with LPS and ATP released MVs, which contained NLRP3, caspase-1, and the 33-kDa precursor and 17-kDa mature forms of IL-1ß and bioactive TF. IL-1ß-positive MVs expressed P2X7 receptor and released soluble IL-1ß in response to ATP stimulation in vitro. In mice, MVs induced a leukocyte peritoneal infiltrate, which was reduced by treatment with the IL-1 receptor antagonist. Finally, IL-1ß-positive MVs were detectable in plasma from 10 active JIA patients. Conclusion: MVs shed from activated macrophages contain IL-1ß, NLRP3 inflammasome components, and TF, and constitute thrombo-inflammatory vectors that can be detected in the plasma from active JIA patients.

Measuring ADAMTS-13 activity to diagnose thrombotic thrombocytopenic purpura: a novel, fast fiber-optic surface plasmon resonance immunoassay.

Background: Thrombotic thrombocytopenic purpura (TTP) is characterized by severe ADAMTS-13 activity deficiency (<10%). Diagnostic testing is challenging because of unavailability, high cost, and expert technician requirement of ADAMTS-13 enzyme assays. Cost-effective, automated fiber-optic surface plasmon resonance (FO-SPR) platforms show potential for developing diagnostic tests. Yet, FO-SPR has never been explored to measure enzymatic activities. Objectives: To develop an easy-to-use ADAMTS-13 activity assay utilizing optical fibers to rapidly diagnose TTP. Methods: The ADAMTS-13 activity assay was designed and optimized using FO-SPR technology based on a previously described enzyme-linked immunosorbent assay setup. A calibration curve was generated to quantify ADAMTS-13 activity in plasma of healthy donors and patients with acute immune-mediated TTP (iTTP), hemolytic uremic syndrome, or sepsis. ADAMTS-13 activity data from FO-SPR and fluorescence resonance energy transfer-based strategies (FRETS)-VWF73 reference assays were compared. Results: After initial assay development, optimization improved read-out magnitude and signal-to-noise ratio and reduced variation. Further characterization demonstrated a detection limit (6.8%) and inter-assay variation (Coefficient of variation, 7.2%) that showed good analytical sensitivity and repeatability. From diverse plasma samples, only plasma from patients with acute iTTP showed ADAMTS-13 activities below 10%. Strong Pearson correlation (r = 0.854) between FO-SPR and reference FRETS-VWF73 assays were observed for all measured samples. Conclusions: A fast ADAMTS-13 activity assay was designed onto automated FO-SPR technology. Optimization resulted in sensitive ADAMTS-13 activity measurements with a detection limit enabling clinical diagnosis of TTP within 3 hours. The FO-SPR assay proved strong correlation with the reference FRETS-VWF73 assay. For the first time, this assay demonstrated the capacity of FO-SPR technology to measure enzymatic activity in pre-clinical context.

Anti-Jo-1 autoantibodies: biomarkers of severity and evolution of the disease in antisynthetase syndrome.

BACKGROUND: Anti-Jo-1 autoantibodies represent essential markers in the diagnosis of antisynthetase syndrome (ASS). In this retrospective study, we aimed to investigate whether their concentrations and fluctuations could both respectively reflect the severity and evolution of ASS. METHODS: Between 2015 and 2020, clinical and biological features of ASS patients with at least one positive measure of anti-Jo-1 autoantibody were collected. At each serum sampling, we assessed myositis activity by using the Myositis Intention to Treat Activities Index (MITAX) and compared anti-Jo-1 concentrations with ASS severity, anti-Jo-1 concentrations between patients with and without active disease, and changes in anti-Jo-1 concentrations with disease activity. RESULTS: Forty-eight patients with ASS had at least one positive determination of anti-Jo-1 concentration. Among them, twenty-nine patients had at least two determinations of anti-Jo-1 autoantibody in their follow-up. We showed that these autoantibody concentrations were significantly correlated with MITAX (r = 0.4, p = 0.03) and creatine kinase concentration (r = 0.34, p = 0.002) and that they were significantly higher in patients with active disease than in those with inactive disease (91.7 IU/L vs 44.4 IU/L, p = 0.016). During follow-up, we found a significant correlation between fluctuations of anti-Jo-1 autoantibody concentrations and MITAX score (r = 0.7, p < 0.0001). CONCLUSION: Our results suggest that anti-Jo-1 autoantibody concentration could be a predictive marker of the severity and evolution of ASS and show that their quantification could represent a precious tool for disease monitoring and for improving the therapeutic management of ASS patients.

Tocilizumab versus anakinra in COVID-19: results from propensity score matching.

Background: Tocilizumab and anakinra are anti-interleukin drugs to treat severe coronavirus disease 2019 (COVID-19) refractory to corticosteroids. However, no studies compared the efficacy of tocilizumab versus anakinra to guide the choice of the therapy in clinical practice. We aimed to compare the outcomes of COVID-19 patients treated with tocilizumab or anakinra. Methods: Our retrospective study was conducted in three French university hospitals between February 2021 and February 2022 and included all the consecutive hospitalized patients with a laboratory-confirmed severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection assessed by RT-PCR who were treated with tocilizumab or anakinra. A propensity score matching was performed to minimize confounding effects due to the non-random allocation. Results: Among 235 patients (mean age, 72 years; 60.9% of male patients), the 28-day mortality (29.4% vs. 31.2%, p = 0.76), the in-hospital mortality (31.7% vs. 33.0%, p = 0.83), the high-flow oxygen requirement (17.5% vs. 18.3%, p = 0.86), the intensive care unit admission rate (30.8% vs. 22.2%, p = 0.30), and the mechanical ventilation rate (15.4% vs. 11.1%, p = 0.50) were similar in patients receiving tocilizumab and those receiving anakinra. After propensity score matching, the 28-day mortality (29.1% vs. 30.4%, p = 1) and the rate of high-flow oxygen requirement (10.1% vs. 21.5%, p = 0.081) did not differ between patients receiving tocilizumab or anakinra. Secondary infection rates were similar between the tocilizumab and anakinra groups (6.3% vs. 9.2%, p = 0.44). Conclusion: Our study showed comparable efficacy and safety profiles of tocilizumab and anakinra to treat severe COVID-19.

NLRP3 inflammasome and interleukin-1 contributions to COVID-19-associated coagulopathy and immunothrombosis.

Immunothrombosis-immune-mediated activation of coagulation-is protective against pathogens, but excessive immunothrombosis can result in pathological thrombosis and multiorgan damage, as in severe coronavirus disease 2019 (COVID-19). The NACHT-, LRR-, and pyrin domain-containing protein 3 (NLRP3) inflammasome produces major proinflammatory cytokines of the interleukin (IL)-1 family, IL-1ß and IL-18, and induces pyroptotic cell death. Activation of the NLRP3 inflammasome pathway also promotes immunothrombotic programs including release of neutrophil extracellular traps and tissue factor by leukocytes, and prothrombotic responses by platelets and the vascular endothelium. NLRP3 inflammasome activation occurs in patients with COVID-19 pneumonia. In preclinical models, NLRP3 inflammasome pathway blockade restrains COVID-19-like hyperinflammation and pathology. Anakinra, recombinant human IL-1 receptor antagonist, showed safety and efficacy and is approved for the treatment of hypoxaemic COVID-19 patients with early signs of hyperinflammation. The non-selective NLRP3 inhibitor colchicine reduced hospitalization and death in a subgroup of COVID-19 outpatients but is not approved for the treatment of COVID-19. Additional COVID-19 trials testing NLRP3 inflammasome pathway blockers are inconclusive or ongoing. We herein outline the contribution of immunothrombosis to COVID-19-associated coagulopathy, and review preclinical and clinical evidence suggesting an engagement of the NLRP3 inflammasome pathway in the immunothrombotic pathogenesis of COVID-19. We also summarize current efforts to target the NLRP3 inflammasome pathway in COVID-19, and discuss challenges, unmet gaps, and the therapeutic potential that inflammasome-targeted strategies may provide for inflammation-driven thrombotic disorders including COVID-19.

BIOMARKERS: CAN THEY REALLY GUIDE OUR DAILY PRACTICE?

ABSTRACT: Optimal management of septic patients requires accurate assessment of both current severity status and prognosis. Since the 1990s, substantial advances have been made in the use of circulating biomarkers for such assessments. This summary of the session on "Biomarkers: can they really use guide our daily practice?" presented at the 2021 WEB-CONFERENCE OF THE EUROPEAN SHOCK SOCIETY, 6 November 2021. These biomarkers include ultrasensitive detection of bacteremia, circulating soluble urokina-type plasminogen activator receptor (suPAR), C-reactive protein (CRP) and ferritin and procalcitonin. In addition, the potential application of novel multiwavelength optical biosensor technology allows noninvasive monitoring of multiple metabolites that can be used to assess severity and prognosis in septic patients. The application these biomarkers and improved technologies provide the potential for improved personalized management of septic patients.

Is Endothelial Activation a Critical Event in Thrombotic Thrombocytopenic Purpura?

Thrombotic thrombocytopenic purpura (TTP) is a severe thrombotic microangiopathy. The current pathophysiologic paradigm suggests that the ADAMTS13 deficiency leads to Ultra Large-Von Willebrand Factor multimers accumulation with generation of disseminated microthrombi. Nevertheless, the role of endothelial cells in this pathology remains an issue. In this review, we discuss the various clinical, in vitro and in vivo experimental data that support the important role of the endothelium in this pathology, suggesting that ADAMTS13 deficiency may be a necessary but not sufficient condition to induce TTP. The "second hit" model suggests that in TTP, in addition to ADAMTS13 deficiency, endogenous or exogenous factors induce endothelial activation affecting mainly microvascular cells. This leads to Weibel-Palade bodies degranulation, resulting in UL-VWF accumulation in microcirculation. This endothelial activation seems to be worsened by various amplification loops, such as the complement system, nucleosomes and free heme.

Characteristics of ANCA-associated vasculitis with aneurysms: Case series and review of the literature.

INTRODUCTION: ANCA-associated vasculitis (AAV) is an exceptional cause of small and large vascular aneurysms. Here, we present the phenotypic characteristics of patients with AAV associated with the presence of aneurysms. METHODS: We conducted a retrospective multicenter study and a systematic review of the literature. Only AAV patients with positive ANCA results and > 1 aneurysm(s) were enrolled. Patients were recruited through a call of observations among the French Vasculitis Study Group (FVSG) and the French Internal Medicine Network. Patients with aneurysm rupture were compared to those without. RESULTS: We enrolled 51 patients in the cohort, including 31 (67%) with granulomatosis with polyangiitis. The median Birmingham Vasculitis Activity Score was 18 [6-41]. A total of 92 aneurysms were noted, 74% of which involved medium-sized arteries, particularly the renal artery. During a follow-up of 24 [6-56] months, 22 (43%) patients experienced aneurysmal rupture, 91% of which involved medium-sized vessels. Patients with aneurysmal rupture showed significantly more pulmonary infiltrates and higher creatinine levels at baseline than patients without rupture. Initial treatments did not differ between the two groups. Ten (20%) patients died during the follow-up, including three from an aneurysmal rupture. CONCLUSION: Aneurysms were more frequently observed in GPA patients and predominantly affected medium-sized vessels, especially the renal arteries. The risk of rupture was high and occurred in >40% of patients. Because of their increased mortality, further studies are required to better manage this subset of patients.

Predictors of Relapses or Recurrences in Patients With Giant Cell Arteritis: A Medical Records Review Study.

OBJECTIVE: Giant cell arteritis (GCA) is the most common systemic vasculitis in individuals aged ≥50 years. Its course is marked by a high relapse rate requiring long-term glucocorticoid use with its inherent adverse effects. We aimed to identify factors associated with relapses or recurrences in GCA at diagnosis. METHODS: We reviewed the medical records of consecutive patients with GCA diagnosed between 2009 and 2019 and followed for at least 12 months. We recorded their characteristics at onset and during follow-up. Factors associated with relapses or recurrences were identified using multivariable analysis. RESULTS: We included 153 patients, among whom 68% were female with a median age of 73 (47-98) years and a median follow-up of 32 (12-142) months. Seventy-four patients (48.4%) had at least 1 relapse or recurrence. Headache and polymyalgia rheumatica were the most frequent manifestations of relapses. The first relapse occurred at a median time of 13 months after the diagnosis, with a median dose of 5.5 (0-25) mg/d of glucocorticoids.In multivariable analysis, patients with relapses or recurrences had a higher frequency of cough and scalp tenderness at diagnosis (20.3% vs 5.1%; odds ratio [OR], 4.73; 95% confidence interval [CI], 1.25-17.94; p = 0.022; and 41.9% vs 29.1%; OR, 2.4; 95% CI, 1.07-5.39; p = 0.034, respectively). Patients with diabetes mellitus at diagnosis had fewer relapses or recurrences during follow-up (5.4% vs 19%; OR, 0.24; 95% CI, 0.07-0.83; p = 0.024). CONCLUSIONS: Cough and scalp tenderness at diagnosis were associated with relapses or recurrences, whereas patients with diabetes experienced fewer relapses or recurrences.

Immune-mediated thrombotic thrombocytopenic purpura plasma induces calcium- and IgG-dependent endothelial activation: correlations with disease severity.

Immune-mediated thrombotic thrombocytopenic purpura (iTTP) is characterized by a severe ADAMTS13 deficiency due to the presence of anti-ADAMTS13 auto-antibodies, with subsequent accumulation of circulating ultra-large von Willebrand factor (VWF) multimers. The role of endothelial cell activation as a trigger of the disease has been suggested in animal models but remains to be demonstrated in humans. We prospectively obtained plasma from the first plasma exchange of 25 patients during iTTP acute phase. iTTP but not control plasma, induced a rapid VWF release and P-selectin exposure on the surface of dermal human micro-vascular endothelial cell (HMVEC-d), associated with angiopoietin-2 and endothelin-1 secretion, consistent with Weibel-Palade bodies exocytosis. Calcium (Ca2+) blockade significantly decreased VWF release, whereas iTTP plasma induced a rapid and sustained Ca2+ flux in HMVEC-d which correlated in retrospect, with disease severity and survival in 62 iTTP patients. F(ab)'2 fragments purified from the immunoglobulin G fraction of iTTP plasma mainly induced endothelial cell activation with additional minor roles for circulating free heme and nucleosomes, but not for complement. Furthermore, two anti-ADAMTS13 monoclonal antibodies purified from iTTP patients' B cells, but not serum from hereditary TTP, induced endothelial Ca2+ flux associated with Weibel-Palade bodies exocytosis in vitro, whereas inhibition of endothelial ADAMTS13 expression using small intering RNA, significantly decreased the stimulating effects of iTTP immunoglobulin G. In conclusion, Ca2+-mediated endothelial cell activation constitutes a "second hit" of iTTP, is correlated with the severity of the disease and may constitute a possible therapeutic target.

Eosinopenia as Predictor of Poor Outcome in Hospitalized COVID-19 Adult Patients from Waves 1 and 2 of 2020 Pandemic.

During SARS-CoV-2 infection, eosinopenia may reflect a hyperactive immune response. In this study of hospitalized COVID-19 patients, we aimed to better understand the prognostic value of severe eosinopenia (absolute eosinophil count = 0 G/L) and decipher its underlying mechanisms. We retrospectively analyzed the records of COVID-19 patients hospitalized from March to June 2020 in three university hospitals in Marseille, France. We assessed the association between severe eosinopenia and a composite poor outcome in these patients, including the need for oxygen supplementation at >6 L/min, ICU admission, and in-hospital death. Among the 551 COVID-19 patients included in this study, severe eosinopenia was found in 228 (51%) of them on admission to hospital and was associated with a composite poor outcome using multivariate analysis (OR = 2.58; CI95 [1.77−3.75]; p < 0.0001). We found a significant association between the presence of severe eosinopenia on admission and the elevation in C-reactive protein, ferritin, IP-10, and suPAR. The histological findings in a series of 37 autopsies from patients who died from severe COVID-19 and presented with severe eosinopenia showed no pulmonary eosinophil trapping. Severe eosinopenia can be a reliable biomarker associated with a composite poor outcome in hospitalized COVID-19 adult patients. It may reflect the magnitude of immune hyperactivation during severe-to-critical COVID-19.

Immune-mediated thrombotic thrombocytopenic purpura prognosis is affected by blood pressure.

Background: The prevalence, prognostic role, and diagnostic value of blood pressure in immune-mediated thrombotic thrombocytopenic purpura (iTTP) and other thrombotic microangiopathies (TMAs) remain unclear. Methods: Using a national cohort of iTTP (n = 368), Shigatoxin-induced hemolytic uremic syndrome (n = 86), atypical hemolytic uremic syndrome (n = 84), and hypertension-related thrombotic microangiopathy (n = 25), we sought to compare the cohort's blood pressure profile to assess its impact on prognosis and diagnostic performances. Results: Patients with iTTP had lower blood pressure than patients with other TMAs, systolic (130 [interquartile range (IQR) 118-143] vs 161 [IQR 142-180] mmHg) and diastolic (76 [IQR 69-83] vs 92 [IQR 79-105] mmHg, both p < 0.001). The best threshold for iTTP diagnosis corresponded to a systolic blood pressure <150 mmHg. iTTP patients presenting with hypertension had a significantly poorer survival (hazard ratio 1.80, 95% confidence interval 1.07-3.04), and this effect remained significant after multivariable adjustment (hazard ratio = 1.14, 95% confidence interval 1.00-1.30). Addition of a blood pressure criterion modestly improved the French clinical score to predict a severe A disintegrin and metalloprotease with thrombospondin type 1 deficiency in patients with an intermediate score (i.e., either platelet count <30 × 109/L or serum creatinine <200 µM). Conclusions: Elevated blood pressure at admission affects the prognosis of iTTP patients and may help discriminate them from other TMA patients. Particular attention should be paid to blood pressure and its management in these patients.

Pericardial effusion in giant cell arteritis is associated with increased inflammatory markers: a retrospective cohort study.

OBJECTIVE: Giant cell arteritis (GCA) is the most frequent vasculitis affecting adults aged > 50 years. Cardiac involvement in GCA is considered rare, and only a few cases of pericarditis have been reported. The aim of this study was to determine the characteristics and prognosis of GCA patients suffering from pericardial involvement at diagnosis. METHODS: We conducted a single-centre, retrospective chart review of patients with GCA in internal medicine departments (from 2000 to 2020). Patients were identified through a centralized hospital database. We retrospectively collected demographic, clinicobiological, histological, imaging, treatment and outcome data. Patients with pericardial effusion, defined as an effusion visible on the CT-scan performed at GCA diagnosis were compared to those without pericardial involvement. RESULTS: Among the 250 patients with GCA, 23 patients (9.2%) had pericardial effusion on CT-scan. The comparison between the groups revealed similar distribution of age, gender, cranial symptoms and ocular ischaemic complications. Patients with pericardial effusion had a higher frequency of weight loss. They also had lower haemoglobin levels and higher platelet levels (p = 0.006 and p = 0.002, respectively), and they more frequently had positive temporal artery biopsy. There were no differences concerning the treatment, relapses, follow-up duration or deaths. CONCLUSIONS: This case series sheds light on GCA as a cause of unexplained pericardial effusion or symptomatic pericarditis among adults aged > 50 years and elevated inflammatory biological markers. Fortunately, pericardial involvement is a benign GCA manifestation. In that context, the search for constitutional symptoms, cranial symptoms and associated signs of polymyalgia rheumatica is crucial for rapidly guiding GCA diagnosis.