Antiplatelet Antibodies Do Not Predict the Response to Intravenous Immunoglobulins during Immune Thrombocytopenia

Immune thrombocytopenia (ITP) is a rare autoimmune disease due to autoantibodies targeting platelet glycoproteins (GP). The mechanism of platelet destruction could differ depending on the specificity of antiplatelet antibodies: anti-GPIIb/IIIa antibodies lead to phagocytosis by splenic macrophages, in a Fcγ receptor (FcγR)-dependent manner while anti-GPIb/IX antibodies induce platelet desialylation leading to their destruction by hepatocytes after binding to the Ashwell–Morell receptor, in a FcγR-independent manner. Considering the FcγR-dependent mechanism of action of intravenous immunoglobulins (IVIg), we assumed that the response to IVIg could be less efficient in the presence of anti-GPIb/IX antibodies. We conducted a multicentric, retrospective study including all adult ITP patients treated with IVIg who had antiplatelet antibodies detected between January 2013 and October 2017. Among the 609 identified, 69 patients were included: 17 had anti-GPIb/IX antibodies and 33 had anti-GPIIb/IIIa antibodies. The response to IVIg was not different between the patients with or without anti-GPIb/IX (88.2% vs. 73.1%). The response to IVIg was better in the case of newly diagnosed ITP (odds ratio (OR) = 5.4 (1.2–24.7)) and in presence of anti-GPIIb/IIIa (OR = 4.82 (1.08–21.5)), while secondary ITP had a poor response (OR = 0.1 (0.02–0.64)). In clinical practice, the determination of antiplatelet antibodies is therefore of little value to predict the response to IVIg

The Oxygen Sensor PHD2 Controls Dendritic Spines and Synapses via Modification of Filamin A

International audienceNeuronal function is highly sensitive to changes in oxygen levels, but how hypoxia affects dendritic spine formation and synaptogenesis is unknown. Here we report that hypoxia, chemical inhibition of the oxygen-sensing prolyl hydroxylase domain proteins (PHDs), and silencing of Phd2 induce immature filopodium-like dendritic protrusions, promote spine regression, reduce synaptic density, and decrease the frequency of spontaneous action potentials independently of HIF signaling. We identified the actin cross-linker filamin A (FLNA) as a target of PHD2 mediating these effects. In normoxia, PHD2 hydroxylates the proline residues P2309 and P2316 in FLNA, leading to von Hippel-Lindau (VHL)-mediated ubiquitination and proteasomal degradation. In hypoxia, PHD2 inactivation rapidly upregulates FLNA protein levels because of blockage of its proteasomal degradation. FLNA upregulation induces more immature spines, whereas Flna silencing rescues the immature spine phenotype induced by PHD2 inhibition

Neointimal myofibroblasts contribute to maintaining Th1/Tc1 and Th17/Tc17 inflammation in giant cell arteritis

International audienceVascular smooth muscle cells (VSMCs) have been shown to play a role in the pathogenesis of giant cell arteritis (GCA) through their capacity to produce chemokines recruiting T cells and monocytes in the arterial wall and their ability to migrate and proliferate in the neointima where they acquire a myofibroblast (MF) phenotype, leading to vascular stenosis. This study aimed to investigate if MFs could also impact T-cell polarization. Confocal microscopy was used to analyze fresh fragments of temporal artery biopsies (TABs). Healthy TAB sections were cultured to obtain MFs, which were then treated or not with interferon-gamma (IFN-γ) and tumor necrosis factor-alpha (TNF-α) and analyzed by immunofluorescence and RT-PCR. After peripheral blood mononuclear cells and MFs were co-cultured for seven days, T-cell polarization was analyzed by flow cytometry. In the neointima of GCA arteries, we observed a phenotypic heterogeneity among VSMCs that was consistent with a MF phenotype (α-SMA + CD90 + desmin + MYH11 +) with a high level of STAT1 phosphorylation. Co-culture experiments showed that MFs sustain Th1/Tc1 and Th17/Tc17 polarizations. The increased Th1 and Tc1 polarization was further enhanced following the stimulation of MFs with IFN-γ and TNF-α, which induced STAT1 phosphorylation in MFs. These findings correlated with increases in the production of IL-1β, IL-6, IL-12 and IL-23 by MFs. Our study showed that MFs play an additional role in the pathogenesis of GCA through their ability to maintain Th17/Tc17 and Th1/Tc1 polarizations, the latter being further enhanced in case of stimulation of MF with IFN-γ and TNF-α

Mucosal-associated invariant T cells in giant cell arteritis

International audienceThis study aimed to assess the implication of mucosal-associated invariant T (MAIT) cells in GCA. Blood samples were obtained from 34 GCA patients (before and after 3 months of treatment with glucocorticoids (GC) alone) and compared with 20 controls aged >50 years. MAIT cells, defined by a CD3(+)CD4(-)TCRγδ(-)TCRVα7.2(+)CD161(+) phenotype, were analyzed by flow cytometry. After sorting, we assessed the ability of MAIT cells to proliferate and produce cytokines after stimulation with anti CD3/CD28 microbeads or IL-12 and IL-18. MAIT were stained in temporal artery biopsies (TAB) by confocal microscopy. MAIT cells were found in the arterial wall of positive TABs but was absent in negative TAB. MAIT frequency among total αβ-T cells was similar in the blood of patients and controls (0.52 vs. 0.57%; P = 0.43) and not modified after GC treatment (P = 0.82). Expression of IFN-γ was increased in MAIT cells from GCA patients compared to controls (44.49 vs. 32.9%; P = 0.029), and not modified after 3 months of GC therapy (P = 0.82). When they were stimulated with IL-12 and IL-18, MAIT from GCA patients produced very high levels of IFN-γ and displayed a stronger proliferation compared with MAIT from controls (proliferation index 3.39 vs. 1.4; P = 0.032). In GCA, the functional characteristics of MAIT cells are modified toward a pro-inflammatory phenotype and a stronger proliferation capability in response to IL-12 and IL-18, suggesting that MAIT might play a role in GCA pathogenesis. Our results support the use of treatments targeting IL-12/IL-18 to inhibit the IFN-γ pathway in GCA

Improvement of Treg immune response after treatment with tocilizumab in giant cell arteritis

International audienceOBJECTIVES: To study the percentage, suppressive function and plasticity of Treg in giant cell arteritis (GCA), and the effects of glucocorticoids and tocilizumab. METHODS: Blood samples were obtained from 40 controls and 43 GCA patients at baseline and after treatment with glucocorticoids + IV tocilizumab (n = 20) or glucocorticoids (n = 23). Treg percentage and phenotype were assessed by flow cytometry. Suppressive function of Treg was assessed by measuring their ability to inhibit effector T-cell (Teff) proliferation and polarisation into Th1 and Th17 cells. RESULTS: Treg (CD4(+)CD25(high)FoxP3(+)) frequency in total CD4(+) T cells was decreased in active GCA patients when compared to controls (2.5% vs. 4.7%, P < 0.001) and increased after treatment with tocilizumab but worsened after treatment with glucocorticoids alone. Treg lacking exon 2 of FoxP3 were increased in GCA patients when compared to controls (23% vs. 10% of total Treg, P = 0.0096) and normalised after treatment with tocilizumab + glucocorticoids but not glucocorticoids alone. In GCA patients, Treg were unable to control Teff proliferation and induced ˜50% increase in the amount of IL-17(+) Teff, which was improved after in vitro blockade of the IL-6 pathway by tocilizumab. CONCLUSION: This study reports quantitative and functional disruptions in the regulatory immune response of GCA patients and demonstrates that, unlike glucocorticoids, tocilizumab improves Treg immune response

De l’âge du Bronze à l’âge du Fer en France et en Europe occidentale (Xe-VIIe siècle av. J.-C.)

Les actes du XXXe colloque de l’Association Française pour l’Étude de l’Âge du Fer (A.F.E.A.F.) - Saint-Romain-en-Gal, 2006 - rassemblent en un seul volume les 16 communications du thème régional et les 28 du thème spécialisé, co-organisé avec l’Association pour la Promotion des Recherches sur l’âge du Bronze (A.P.R.A.B.). La question du territoire est la trame de fond de la partie régionale, suscitée par le dynamisme et les résultats de l’archéologie à Lyon et dans la région (du Mâconnais à la Loire et aux Alpes). Cette question est abordée par l’examen des sources écrites, d’utiles synthèses et la présentation de sites remarquables, en contexte d’habitat ou funéraire. L’enjeu du thème spécialisé était s’éclaircir la difficile question du passage de l’âge du Bronze à l’âge du Fer. Comment cerner les signes du changement, l’expliquer, en saisir le moment ? La plupart des auteurs ont choisi une fourchette chronologique large et se sont placés dans l’optique d’une évolution d’ordre endogène. Le critère du métal n’apparaît pas comme le plus pertinent. La fragmentation des faciès céramiques, la rupture de l’unité culturelle prévalant entre le XIIe et le VIIe siècles, des comportements nouveaux constatés dans les habitats et les pratiques funéraires : la situation est contrastée dans une Europe étudiée ici avec des exemples allant de l’Espagne à l’Italie, de la Grande-Bretagne à la Bohême.So dynamic was archaeology in Lyon and its surrounding region (Macon, the Loire Country and the Alps), that focus was kept on regional topics and that the question of «territory» was kept as the main line of research. The question has been tackled from many angles: written sources, enlightening summaries and synthetized works, presentation of quite remarkable sites, whether settlement sites or burial sites. The whole point was to shed light on the transitional phase between the Bronze Age and the Iron Age. What are the signs of a change, how to explain them, how to pinpoint them? Most scientists have led their research on a fairly large time span, always in the perspective of an endogenous evolution. The metal criterion do not come up as the most relevant factor anymore. Differenciation in pottery groups and disruption in the cultural cohesion prevail between the XIIthand the VIIth centuries. New practices arise in settlement patterns as well as funeral rites: the situation in Europe here under study, is richly contrasted and documented with case studies coming from a zone spreading from Spain to Italy, from Great Britain to Bohemia. The records of the 30th «A.F.E.A.F., Association Française pour l’Étude de l’Âge du Fer» ’symposium - Saint-Romain en Gal, 2006 - gather in one single volume the 16 papers on regional issues, as well as 28 papers on more specific issues, organized in collaboration with the Association pour la Promotion des Recherches sur l’âge du Bronze (A.P.R.A.B.)