Anti-TNF-Alpha Therapy and Systemic Vasculitis

TNF-α is a pleiotropic cytokine, which plays a major role in the pathogenesis of numerous autoimmune and/or inflammatory systemic diseases. Systemic vasculitis constitutes a group of rare diseases, characterized by inflammation of the arterial or venous vessel wall, causing stenosis and thrombosis. Treatment of the different type of vasculitis mainly relies on steroids and immunosuppressive drugs. In case of refractory or relapsing diseases, however, a second line of treatment may be required. Anti-TNF-α drugs have been used in this setting during the last 15 years with inconsistent results. We reviewed herein the use of anti-TNF-α therapy in different kind of vasculitis and concluded that, except for Behcet's disease, this therapeutic option has not demonstrated significant improvement in the treatment of vasculitis

Pattern of DAP12 Expression in Leukocytes from Both Healthy and Systemic Lupus Erythematosus Patients

DAP12 is an ITAM-bearing transmembrane adaptor originally identified on the surface of Natural Killer cells. A broad expression among other immune cells was later found in myeloid and lymphoid cells. However, data on DAP12 expression pattern rely only on immunoblot and microarray analysis. Here, we describe the generation and the characterization of an anti-DAP12 monoclonal antibody. Using this novel reagent, we show that DAP12 expression is restricted to innate immune cells in basal condition. Since a decreased expression of DAP12 has been suggested in NK cells of systemic lupus erythematosus patients, we have further investigated the NK cell receptor repertoire and leukocyte expression of DAP12 in these patients and no major changes were detectable when compared to controls

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

ObjectiveIL-1β is a leaderless cytokine with poorly known secretory mechanisms that is barely detectable in serum of patients, including those with an IL-1β-mediated disease such as systemic juvenile idiopathic arthritis (sJIA). Leukocyte microvesicles (MVs) may be a mechanism of IL-1β secretion. The first objective of our study was to characterize IL-1β-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-1β-positive MVs in JIA patients.MethodsMVs 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-1β, 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-1β-positive MVs were studied ex vivo in 10 active JIA patients using flow cytometry.ResultsTHP-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-1β and bioactive TF. IL-1β-positive MVs expressed P2X7 receptor and released soluble IL-1β 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-1β-positive MVs were detectable in plasma from 10 active JIA patients.ConclusionMVs shed from activated macrophages contain IL-1β, NLRP3 inflammasome components, and TF, and constitute thrombo-inflammatory vectors that can be detected in the plasma from active JIA patients

Natural Killer Cells Exhibit a Peculiar Phenotypic Profile in Systemic Sclerosis and Are Potent Inducers of Endothelial Microparticles Release

The pathophysiology of systemic sclerosis (SSc) involves early endothelial and immune activation, both preceding the onset of fibrosis. We previously identified soluble fractalkine and circulating endothelial microparticles (EMPs) as biomarkers of endothelial inflammatory activation in SSc. Fractalkine plays a dual role as a membrane-bound adhesion molecule expressed in inflamed endothelial cells (ECs) and as a chemokine involved in the recruitment, transmigration, and cytotoxic activation of immune cells that express CX3CR1, the receptor of fractalkine, namely CD8 and γδ T cells and natural killer (NK) cells. We aimed to quantify circulating cytotoxic immune cells and their expression of CX3CR1. We further investigated the expression profile of NK cells chemokine receptors and activation markers and the potential of NK cells to induce EC activation in SSc. We performed a monocentric study (NCT 02636127) enrolling 15 SSc patients [15 females, median age of 55 years (39–63), 11 limited cutaneous form and 4 diffuse] and 15 healthy controls. Serum fractalkine levels were significantly increased in SSc patients. Circulating CD8 T cells numbers were decreased in SSc patients with no difference in their CX3CR1 expression. Circulating γδ T cells and NK cells numbers were preserved. CX3CR1 expression in CD8 and γδ T cells did not differ between SSc patients and controls. The percentage and level of CX3CR1 expression in NK cells were significantly lowered in SSc patients. Percentages of CXCR4, NKG2D, CD69-expressing NK cells, and their expression levels were decreased in NK cells. Conversely, CD16 level expression and percentages of CD16+ NK cells were preserved. The exposure of human microvascular dermic EC line (HMVEC-d) to peripheral blood mononuclear cells resulted in similar NK cells degranulation activity in SSc patients and controls. We further showed that NK cells purified from the blood of SSc patients induced enhanced release of EMPs than NK cells from controls. This study evidenced a peculiar NK cells phenotype in SSc characterized by decreased chemokine and activation receptors expression, that might reflect NK cells involvement in the pathogenic process. It also highlighted the role of NK cells as a potent mechanism inducing endothelial activation through enhanced EMPs release

Increased serum levels of fractalkine and mobilisation of CD34+CD45− endothelial progenitor cells in systemic sclerosis

International audienceBackground: The disruption of endothelial homeostasis is a major determinant in the pathogenesis of systemic sclerosis (SSc) and is reflected by soluble and cellular markers of activation, injury and repair. We aimed to provide a combined assessment of endothelial markers to delineate specific profiles associated with SSc disease and its severity

Syndrome de Tolosa-Hunt et vascularite à p-ANCA (première observation)

AIX-MARSEILLE2-BU Méd/Odontol. (130552103) / SudocPARIS-BIUM (751062103) / SudocSudocFranceF

Rôle de l'activation calcique dans la microvascularisation enothéliale au cours du Purpura Thrombotique Thrombocytopénique auto-immun de l'adulte

Le purpura thrombotique thrombocytopénique auto-immun (PTT-AI) appartient au groupe des mircroangiopathies thrombotiques qui se caractérisent par l'association d'une anémie hémolytique mécanique et d'une thrombopénie périphérique. Cette maladie est liée à la présence d'auto-anticorps inhibiteurs dirigés contre ADAMTS13, protéase clivant le facteur von Willebrand de haut poids moléculaire (FvW-HM). Cependant l'absence d'enzyme ne suffit pas à induire la maladie, il est nécessaire qu'il y ait une phase d'activation endothéliale. En effet, les plasmas des patients atteintes de PTT induisent in vitro, en réponse à un flux calcique intra-cellulaire, la dégranulation des corps de Weibel et Palade et la production de grandes quantités de FvW-HM. Ainsi, au cours de ce travail nous avons voulu étudier le rôle de la blessure calcique dans la génération de microparticules endothéliales in vitro. Nos résultats montrent que les plasmas des patient PTT induisent la production de grandes quantités de microparticules pro-coagulantes portant du FVW à leur surface, secondairement un flux calcique intra-cellulaire. DE plus, nous avons montré que ces phénomènes sont partiellement dépendants d'une activation du système du complément mais surtout dépendants de la présence d'IgG dans le plasma des patients PTT, ce qui laisse supposer que l'activation endothéliale pourrait être secondaire à la présence dans leur plasma d'auto-anticorps anti-cellules endothéliales. Ces résultats suggèrent que l'épuration des IgG des plasmas de patients, l'inhibition des flux calciques intra-endothéliaux et/ou du complément sont des stratégies possibles dans le traitement du PTT humainAIX-MARSEILLE2-BU Méd/Odontol. (130552103) / SudocSudocFranceF

La maladie de Horton (diagnostic et prise en charge)

AIX-MARSEILLE2-BU Méd/Odontol. (130552103) / SudocPARIS-BIUM (751062103) / SudocSudocFranceF

Rôle de l'interleukine-18 dans la physiopathologie du syndrome d'activation macrophagique de l'adulte

AIX-MARSEILLE2-BU Méd/Odontol. (130552103) / SudocPARIS-BIUM (751062103) / SudocSudocFranceF

Pathogenesis of ANCA-associated vasculitis: An update

International audienceAntineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) constitutes a group of rare diseases characterized by necrotizing inflammation of small blood vessels and the presence of ANCA. Although these autoantibodies were initially used to classify pauci-immune vasculitis, increasing clinical and experimental evidence now supports their pathogenic role, mainly through ANCA-induced activation of primed neutrophils and monocytes leading to destructive vascular necrosis. The mechanisms of ANCA generation remain however unclear. Neutrophils play a central role in the pathophysiological process of AAV since they are both effector cells responsible for endothelial damage and targets of autoimmunity. Another role of neutrophils is due to their ability to generate neutrophil extracellular traps, which support the presentation of ANCA autoantigens, could break immune tolerance and induce autoantibody generation. Alternatively, the ANCA autoimmune response is facilitated by insufficient T-cell and B-cell regulation, and the role of complement alternative pathway has recently been emphasized. This review summarizes the main pathogenesis concepts of AAV as well as the putative mechanisms for the origin of ANCA autoimmune response