Le tocilizumab corrige le déséquilibre de la balance Th17/Treg chez les patients atteints de polyarthrite rhumatoïde

Brief Report: Inhibition of interleukin-6 function corrects Th17/Treg cell imbalance in patients with rheumatoid arthritis

OBJECTIVE: From an immunologic standpoint, the mechanisms by which treatment with tocilizumab (TCZ), a humanized anti-interleukin-6 (anti-IL-6) receptor antibody, results in improvement in rheumatoid arthritis (RA) patients are still not fully understood. In vitro studies and studies in mouse models have demonstrated the critical role of IL-6 in Th17 cell differentiation. Th17 lymphocytes have been shown to be strongly involved in RA pathogenesis, and the purpose of this study was to investigate the effect of IL-6 blockade on the balance between Th17 cells and Treg cells in patients with active RA. METHODS: Patients with active RA for whom TCZ had been prescribed by a rheumatologist were en…

Modification de la réponse immunitaire au cours de la maladie de Rendu-Osler

Introduction La maladie de Rendu-Osler (MRO) est une maladie genetique vasculaire rare caracterisee par une neo-angiogenese deregulee aboutissant a des epistaxis anemiantes parfois associees a malformations arterio-veineuses (MAV) pulmonaires, hepatiques ou cerebrales. La MRO est egalement associee a une lymphopenie T predominant sur les CD4+ dont les causes et les consequences sont mal connues. L’objectif de ce travail est de decrire les polarisations lymphocytaires Th1, Th2, Th17, Th1-17 et Treg au cours de la MRO. Patients et methodes Les patients atteints de MRO confirmee genetiquement ont ete prospectivement inclus lors de leur suivi habituel. Le score de severite des epistaxis (ESS), …

Colony-stimulating factor-1-induced oscillations in phosphatidylinositol-3 kinase/AKT are required for caspase activation in monocytes undergoing differentiation into macrophages.

Abstract The differentiation of human peripheral blood monocytes into resident macrophages is driven by colony-stimulating factor-1 (CSF-1), which upon interaction with CSF-1 receptor (CSF-1R) induces within minutes the phosphorylation of its cytoplasmic tyrosine residues and the activation of multiple signaling complexes. Caspase-8 and -3 are activated at day 2 to 3 and contribute to macrophage differentiation, for example, through cleavage of nucleophosmin. Here, we show that the phosphatidylinositol-3 kinase and the downstream serine/threonine kinase AKT connect CSF-1R activation to caspase-8 cleavage. Most importantly, we demonstrate that successive waves of AKT activation with increasi…

TET2 gene mutation is a frequent and adverse event in chronic myelomonocytic leukemia

Background Acquired somatic deletions and loss-of-function mutations in one or several codons of the TET2 ( Ten-Eleven Translocation-2 ) gene were recently identified in hematopoietic cells from patients with myeloid malignancies, including myeloproliferative disorders and myelodys-plastic syndromes. The present study was designed to determine the prevalence of TET2 gene alterations in chronic myelomonocytic leukemias. Design and Methods Blood and bone marrow cells were collected from 88 patients with chronic phase chronic myelomonocytic leukemia and from 14 with acute transformation of a previously identified disease. Polymerase chain reaction analysis and direct sequencing were used to se…

Alpha-defensins secreted by dysplastic granulocytes inhibit the differentiation of monocytes in chronic myelomonocytic leukemia.

Abstract Chronic myelomonocytic leukemia (CMML) is a clonal hematopoietic disorder that occurs in elderly patients. One of the main diagnostic criteria is the accumulation of heterogeneous monocytes in the peripheral blood. We further explored this cellular heterogeneity and observed that part of the leukemic clone in the peripheral blood was made of immature dysplastic granulocytes with a CD14−/CD24+ phenotype. The proteome profile of these cells is dramatically distinct from that of CD14+/CD24− monocytes from CMML patients or healthy donors. More specifically, CD14−/CD24+ CMML cells synthesize and secrete large amounts of alpha-defensin 1-3 (HNP1-3). Recombinant HNPs inhibit macrophage co…

Th1 and Th17 lymphocytes expressing CD161 are implicated in giant cell arteritis and polymyalgia rheumatica pathogenesis.

International audience; OBJECTIVE: Giant cell arteritis (GCA) is the most frequently occurring vasculitis in elderly individuals, and its pathogenesis is not fully understood. The objective of this study was to decipher the role of the major CD4+ T cell subsets in GCA and its rheumatologic form, polymyalgia rheumatica (PMR). METHODS: A prospective study of the phenotype and the function of major CD4+ T cell subsets (Th1, Th17, and Treg cells) was performed in 34 untreated patients with GCA or PMR, in comparison with 31 healthy control subjects and with the 27 treated patients who remained after the 7 others withdrew. RESULTS: Compared with control subjects, patients with GCA and patients wi…

Immunologic effects of rituximab on the human spleen in immune thrombocytopenia

Abstract Immune thrombocytopenia (ITP) is an autoimmune disease with a complex pathogenesis. As in many B cell–related autoimmune diseases, rituximab (RTX) has been shown to increase platelet counts in some ITP patients. From an immunologic standpoint, the mode of action of RTX and the reasons underlying its limited efficacy have yet to be elucidated. Because splenectomy is a cornerstone treatment of ITP, the immune effect of RTX on this major secondary lymphoid organ was investigated in 18 spleens removed from ITP patients who were treated or not with RTX. Spleens from ITP individuals had follicular hyperplasia consistent with secondary follicles. RTX therapy resulted in complete B-cell de…

Immune Thrombocytopenia: Recent Advances in Pathogenesis and Treatments

Immune thrombocytopenia (ITP) is a rare autoimmune disease due to both a peripheral destruction of platelets and an inappropriate bone marrow production. Although the primary triggering factors of ITP remain unknown, a loss of immune tolerance—mostly represented by a regulatory T-cell defect—allows T follicular helper cells to stimulate autoreactive splenic B cells that differentiate into antiplatelet antibody-producing plasma cells. Glycoprotein IIb/IIIa is the main target of antiplatelet antibodies leading to platelet phagocytosis by splenic macrophages, through interactions with Fc gamma receptors (FcγRs) and complement receptors. This allows macrophages to activate autoreactive T cells …

Preferential splenic CD8+ T-cell activation in rituximab-nonresponder patients with immune thrombocytopenia

The pathogenic role of B cells in immune thrombocytopenia (ITP) has justified the therapeutic use of anti-CD20 antibodies such as rituximab (RTX). However, 60% of ITP patients do not respond to RTX. To decipher the mechanisms implicated in the failure of RTX, and because the spleen plays a well-recognized role in ITP pathogenesis, 12 spleens from ITP patients who had been nonresponders to RTX therapy were compared with 11 spleens from RTX-untreated ITP patients and 9 controls. We here demonstrate that in RTX-nonresponder ITP patients, preferential Th1 and Tc1 T lymphocyte polarizations occur, associated with an increase in splenic effector memory CD8(+) T-cell frequency. Moreover, in the RT…

ÉTUDE DES CELLULES LYMPHOÏDES INNÉES SPLÉNIQUES HUMAINES ET DE LEURS IMPLICATIONS AU COURS DE LA THROMBOPÉNIE IMMUNOLOGIQUE

ÉTUDE DES CELLULES LYMPHOÏDES INNÉES SPLÉNIQUES HUMAINES ET DE LEURS IMPLICATIONS AU COURS DE LA THROMBOPÉNIE IMMUNOLOGIQUEDe découverte récente, les ILC ont été caractérisées comme cellules effectrices de l’immunité innéecapables de moduler les réponses lymphocytaires T et B dans les muqueuses. Cependant, leur rôle ausein des organes lymphoïdes chez l’Homme au cours des maladies auto-immunes n’a pas été étudié.La thrombopénie immunologique est une maladie auto-immune responsable d’une destructionpériphérique des plaquettes associée à une production médullaire inadaptée. La rate joue un rôlecentral dans la physiopathologie en étant le site principal de la destruction des plaquettes et du ma…