Pro-angiogenic changes of T-helper lymphocytes in hereditary hemorrhagic telangiectasia.

Hereditary hemorrhagic telangiectasia (HHT) is a rare inherited disease due to heterozygous loss-of-function mutations on the BMP9/10 pathway ( or mainly). HHT endothelial cells are prone to lose their quiescence, leading to progressive appearance of numerous telangiectases on skin and mucosa (complicated by epistaxis and anemia), and to larger arteriovenous malformations in lungs, liver and brain. HHT is also associated with T lymphocyte abnormalities, which are currently poorly understood.

Regulatory T-cell dysfunctions are associated with increase in tumor necrosis factor α in autoimmune hemolytic anemia and participate in Th17 polarization.

Warm autoimmune hemolytic anemia (wAIHA) is a rare acquired autoimmune disease mediated by antibodies targeting red blood cells. The involvement of CD4 T-helper cells has been scarcely explored, with most findings extrapolated from animal models. Here, we performed quantification of both effector T lymphocytes (Teff) and regulatory T cells (Treg), associated with functional and transcriptomic analyses of Treg in human wAIHA.

T-cell immune response predicts the risk of critical SARS-Cov2 infection in hospitalized COVID-19 patients.

Introduction: This study aimed to identify markers of disease worsening in patients hospitalized for SARS-Cov2 infection.

Patients And Methods: Patients hospitalized for severe recent-onset (<1 week) SARS-Cov2 infection were prospectively included. The percentage of T-cell subsets and plasma IL-6 at admission (before any steroid therapy) were compared between patients who progressed to a critical infection and those who did not.

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

Objectives: 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 ( = 20) or glucocorticoids ( = 23). Treg percentage and phenotype were assessed by flow cytometry.

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.

Mucosal-associated invariant T cells in Giant Cell Arteritis.

This 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 CD3CD4TCRγδTCRVα7.

Efficiency of human monocyte-derived suppressor cell-based treatment in graft-versus-host disease prevention while preserving graft-versus-leukemia effect.

Background: Immunosuppressive cell-based therapy is a recent strategy for controlling Graft--Host Disease (GvHD). Such cells ought to maintain their suppressive function in inflammatory conditions and in the presence of immunosuppressive agents currently used in allogeneic hematopoietic cell transplantation (allo-HCT). Moreover, these therapies should not diminish the benefits of allo-HCT, the Graft--Leukemia (GvL) effect.

B cell depleting therapy regulates splenic and circulating T follicular helper cells in immune thrombocytopenia.

B cells are involved in immune thrombocytopenia (ITP) pathophysiology by producing antiplatelet auto-antibodies. However more than a half of ITP patients do not respond to B cell depletion induced by rituximab (RTX). The persistence of splenic T follicular helper cells (TFH) that we demonstrated to be expanded during ITP and to support B cell differentiation and antiplatelet antibody-production may participate to RTX inefficiency.

Involvement and prognosis value of CD8(+) T cells in giant cell arteritis.

CD8(+) T cells participate in the pathogenesis of some vasculitides. However, little is known about their role in Giant Cell Arteritis (GCA). This study was conducted to investigate CD8(+) T cell involvement in the pathogenesis of GCA.

T Lymphocyte Inhibition by Tumor-Infiltrating Dendritic Cells Involves Ectonucleotidase CD39 but Not Arginase-1.

T lymphocytes activated by dendritic cells (DC) which present tumor antigens play a key role in the antitumor immune response. However, in patients suffering from active cancer, DC are not efficient at initiating and supporting immune responses as they participate to T lymphocyte inhibition. DC in the tumor environment are functionally defective and exhibit a characteristic of immature phenotype, different to that of DC present in nonpathological conditions.

Human monocyte-derived suppressor cells control graft-versus-host disease by inducing regulatory forkhead box protein 3-positive CD8+ T lymphocytes.

Background: Adoptive transfer of immunosuppressive cells has emerged as a promising strategy for the treatment of immune-mediated disorders. However, only a limited number of such cells can be isolated from in vivo specimens. Therefore efficient ex vivo differentiation and expansion procedures are critically needed to produce a clinically relevant amount of these suppressive cells.

Splenic TFH expansion participates in B-cell differentiation and antiplatelet-antibody production during immune thrombocytopenia.

Antiplatelet-antibody-producing B cells play a key role in immune thrombocytopenia (ITP) pathogenesis; however, little is known about T-cell dysregulations that support B-cell differentiation. During the past decade, T follicular helper cells (TFHs) have been characterized as the main T-cell subset within secondary lymphoid organs that promotes B-cell differentiation leading to antibody class-switch recombination and secretion. Herein, we characterized TFHs within the spleen of 8 controls and 13 ITP patients.

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.

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

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.

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.

Immunologic effects of rituximab on the human spleen in immune thrombocytopenia.

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.

Cytotoxic dendritic cells generated from cancer patients.

Known for years as professional APCs, dendritic cells (DCs) are also endowed with tumoricidal activity. This dual role of DC as killers and messengers may have important implications for tumor immunotherapy. However, the tumoricidal activity of DCs has mainly been investigated in animal models.

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

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.

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.

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

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.