Glucocorticoids—All-Rounders Tackling the Versatile Players of the Immune System

Glucocorticoids regulate fundamental processes of the human body and control cellular functions such as cell metabolism, growth, differentiation, and apoptosis. Moreover, endogenous glucocorticoids link the endocrine and immune system and ensure the correct function of inflammatory events during tissue repair, regeneration, and pathogen elimination via genomic and rapid non-genomic pathways. Due to their strong immunosuppressive, anti-inflammatory and anti-allergic effects on immune cells, tissues and organs, glucocorticoids significantly improve the quality of life of many patients suffering from diseases caused by a dysregulated immune system. Despite the multitude and seriousness of glucocorticoid-related adverse events including diabetes mellitus, osteoporosis and infections, these agents remain indispensable, representing the most powerful, and cost-effective drugs in the treatment of a wide range of rheumatic diseases. These include rheumatoid arthritis, vasculitis, and connective tissue diseases, as well as many other pathological conditions of the immune system. Depending on the therapeutically affected cell type, glucocorticoid actions strongly vary among different diseases. While immune responses always represent complex reactions involving different cells and cellular processes, specific immune cell populations with key responsibilities driving the pathological mechanisms can be identified for certain autoimmune diseases. In this review, we will focus on the mechanisms of action of glucocorticoids on various leukocyte populations, exemplarily portraying different autoimmune diseases as heterogeneous targets of glucocorticoid actions: (i) Abnormalities in the innate immune response play a crucial role in the initiation and perpetuation of giant cell arteritis (GCA). (ii) Specific types of CD4+ T helper (Th) lymphocytes, namely Th1 and Th17 cells, represent important players in the establishment and course of rheumatoid arthritis (RA), whereas (iii) B cells have emerged as central players in systemic lupus erythematosus (SLE). (iv) Allergic reactions are mainly triggered by several different cytokines released by activated Th2 lymphocytes. Using these examples, we aim to illustrate the versatile modulating effects of glucocorticoids on the immune system. In contrast, in the treatment of lymphoproliferative disorders the pro-apoptotic action of glucocorticoids prevails, but their mechanisms differ depending on the type of cancer. Therefore, we will also give a brief insight into the current knowledge of the mode of glucocorticoid action in oncological treatment focusing on leukemia

ANCA-associated vasculitis.

The anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitides (AAVs) are a group of disorders involving severe, systemic, small-vessel vasculitis and are characterized by the development of autoantibodies to the neutrophil proteins leukocyte proteinase 3 (PR3-ANCA) or myeloperoxidase (MPO-ANCA). The three AAV subgroups, namely granulomatosis with polyangiitis (GPA), microscopic polyangiitis and eosinophilic GPA (EGPA), are defined according to clinical features. However, genetic and other clinical findings suggest that these clinical syndromes may be better classified as PR3-positive AAV (PR3-AAV), MPO-positive AAV (MPO-AAV) and, for EGPA, by the presence or absence of ANCA (ANCA+ or ANCA-, respectively). Although any tissue can be involved in AAV, the upper and lower respiratory tract and kidneys are most commonly and severely affected. AAVs have a complex and unique pathogenesis, with evidence for a loss of tolerance to neutrophil proteins, which leads to ANCA-mediated neutrophil activation, recruitment and injury, with effector T cells also involved. Without therapy, prognosis is poor but treatments, typically immunosuppressants, have improved survival, albeit with considerable morbidity from glucocorticoids and other immunosuppressive medications. Current challenges include improving the measures of disease activity and risk of relapse, uncertainty about optimal therapy duration and a need for targeted therapies with fewer adverse effects. Meeting these challenges requires a more detailed knowledge of the fundamental biology of AAV as well as cooperative international research and clinical trials with meaningful input from patients

Selectins impair regulatory T cell function and contribute to systemic lupus erythematosus pathogenesis

Le lupus érythémateux systémique (LES) est une maladie auto-immune systémique caractérisée par une perte de tolérance vis-à-vis des autoantigènes nucléaires, une production d’auto-anticorps, une signature interféron et une dysfonction du compartiment des lymphocytes T régulateur (Tregs). Dans ce travail, nous avons identifié que les plaquettes des patients LES actifs interagissaient de manière préférentielle avec les Tregs via l’axe P-sélectine/PSGL-1. L’interaction de la P-sélectine plaquettaire avec son ligand le PSGL-1 abolissait les fonction immunosuppressives des Tregs et des Tregs folliculaires par le biais d’une phosphorylation de Syk et d’un signal calcique intracellulaire. D’un point de vue mécanistique, l’interaction P-sélectine/PSGL-1 induisait une sous-expression de la voie TGF-béta, altérant le phénotype et les fonctions suppressives des Tregs. Chez les patients, nous avons montré une majoration significative des taux des P- et E-sélectine circulantes, sous forme soluble et microparticulaire, et ce de manière corrélé à l’activité du LES. Enfin, le blocage de la P-selectine dans un modèle murin de LES améliorait des symptômes cardinaux de la pathologies (atteinte rénale notamment). Au total, nos résultats identifient une nouvelle voie physiopathologique impliquant la P-sélectine dans le LES, et ouvre la voie pour des essais thérapeutique visant à bloquer la P-sélectine dans le LES.Systemic lupus erythematosus (SLE) is a systemic autoimmune disease characterized by a loss of tolerance toward self-nucleic acids, autoantibody production, an interferon signature, and a defect in the T regulatory cells (Tregs) compartment. In this work, we identified that platelets from active SLE patients preferentially interacted with Tregs via the P-selectin/PSGL-1 axis. Selectin interaction with PSGL-1 blocked the regulatory/suppressive properties of Tregs and follicular Tregs by triggering Syk phosphorylation and an increase in intracytosolic calcium. Mechanistically, P-selectin engagement on Tregs induced a downregulation of the TGF-beta axis, altering Tregs phenotype and limiting their immunosuppressive response. In patients, we found a significant upregulation of P- and E-selectin levels both expressed by microparticles and in their soluble forms that correlated with SLE disease activity. Finally, blocking P-selectin in a mouse model of SLE improved cardinal features of the disease. Overall, our results identify a selectin-dependent pathway active in SLE patients and validate it as a potential therapeutic avenue

Les sélectines inhibent la fonction des lymphocytes T régulateurs et contribuent à la pathogénie du lupus érythémateux systémique

Systemic lupus erythematosus (SLE) is a systemic autoimmune disease characterized by a loss of tolerance toward self-nucleic acids, autoantibody production, an interferon signature, and a defect in the T regulatory cells (Tregs) compartment. In this work, we identified that platelets from active SLE patients preferentially interacted with Tregs via the P-selectin/PSGL-1 axis. Selectin interaction with PSGL-1 blocked the regulatory/suppressive properties of Tregs and follicular Tregs by triggering Syk phosphorylation and an increase in intracytosolic calcium. Mechanistically, P-selectin engagement on Tregs induced a downregulation of the TGF-beta axis, altering Tregs phenotype and limiting their immunosuppressive response. In patients, we found a significant upregulation of P- and E-selectin levels both expressed by microparticles and in their soluble forms that correlated with SLE disease activity. Finally, blocking P-selectin in a mouse model of SLE improved cardinal features of the disease. Overall, our results identify a selectin-dependent pathway active in SLE patients and validate it as a potential therapeutic avenue.Le lupus érythémateux systémique (LES) est une maladie auto-immune systémique caractérisée par une perte de tolérance vis-à-vis des autoantigènes nucléaires, une production d’auto-anticorps, une signature interféron et une dysfonction du compartiment des lymphocytes T régulateur (Tregs). Dans ce travail, nous avons identifié que les plaquettes des patients LES actifs interagissaient de manière préférentielle avec les Tregs via l’axe P-sélectine/PSGL-1. L’interaction de la P-sélectine plaquettaire avec son ligand le PSGL-1 abolissait les fonction immunosuppressives des Tregs et des Tregs folliculaires par le biais d’une phosphorylation de Syk et d’un signal calcique intracellulaire. D’un point de vue mécanistique, l’interaction P-sélectine/PSGL-1 induisait une sous-expression de la voie TGF-béta, altérant le phénotype et les fonctions suppressives des Tregs. Chez les patients, nous avons montré une majoration significative des taux des P- et E-sélectine circulantes, sous forme soluble et microparticulaire, et ce de manière corrélé à l’activité du LES. Enfin, le blocage de la P-selectine dans un modèle murin de LES améliorait des symptômes cardinaux de la pathologies (atteinte rénale notamment). Au total, nos résultats identifient une nouvelle voie physiopathologique impliquant la P-sélectine dans le LES, et ouvre la voie pour des essais thérapeutique visant à bloquer la P-sélectine dans le LES

WB-TFh paper.tiff

Figure 2C original western blots used for Bcl6 expression comparison between Camk4-sufficient & Camk4-deficient in vitro differentiation mouse Tfh cells.Manuscript Title: CaMK4 controls follicular helper T cell expansion and function during normal and autoimmune T-dependent B cell responsesJournal: Nature Communications </p

Acceptance rate and sociological factors involved in the switch from originator to biosimilar etanercept (SB4)

Objective : To study acceptance rate and factors influencing acceptance of the switch from originator etanercept (Enbrel©) to biosimilar etanercept (SB4, Bénépali©) in patients with rheumatic disease.Methods : Patients with a well-controlled rheumatic disease consulting in our rheumatology department were offered the switch for SB4. After oral and written information concerning biosimilar, free choice to accept the switch was left to the patients. The main outcome was primary switch acceptance rate defined by switch acceptance during the initial consult. Real switch adherence, socio-cultural factors and beliefs influencing switch acceptance rate were retrieved during a telephonic interview at distance from the consultation.Results : Fifty-two patients were eligible for the switch: 32 (62%) with spondyloarthritis and 20 (38%) with rheumatoid arthritis. The primary acceptance rate was 92% (48/52). Patients refusing the switch were more likely to report a bad opinion on generic drugs (100% vs 11%, p < 0.001). Other patient characteristics were roughly identical except for a statistical trend in the refusal group toward older age (61.4 vs 50.7 years, p = 0.08) and longer disease duration (26 vs 12.1 years, p = 0.05). Despite initial acceptance, two patients did not begin SB4 after receiving negative information by their regular pharmacist. Real SB4 switch rate was 85% (44/52) and 86% (38/44) of patients reported a good experience of the switch.Conclusions : Acceptance rate of the switch from originator to biosimilar etanercept is high. Patient information, physician and pharmacist knowledge on biosimilars should be taken into account in order to improve their diffusion