Role of extracellular vesicles in autoimmune diseases

Extracellular vesicles (EVs) consist of exosomes released upon fusion of multivesicular bodies with the cell plasma membrane and microparticles shed directly from the cell membrane of many cell types. EVs can mediate cell-cell communication and are involved in many processes including inflammation, immune signaling, angiogenesis, stress response, senescence, proliferation, and cell differentiation. Accumulating evidence reveals that EVs act in the establishment, maintenance and modulation of autoimmune processes among several others involved in cancer and cardiovascular complications. EVs could also present biomedical applications, as disease biomarkers and therapeutic targets or agents for drug delivery

Clinical and Sociodemographic Characteristics Associated With Thick Melanomas: A Population-Based, Case-Case Study in France.

International audienceOBJECTIVE To identify clinical and sociodemographic factors associated with very thick melanoma (VTM) (Breslow thickness, ≥3 mm) in France. DESIGN Retrospective, population-based, case-case study using a survey of cancer registries and questionnaires to practitioners. SETTING Five regions covering 19.2% of the French territory and 8.2 million inhabitants. CASES Cases included all incident melanomas with a Breslow thickness of 3 mm or greater (ie, VTM), diagnosed between January 1 and December 31, 2008, in residents of the study area (Alsace, Bourgogne, Champagne-Ardenne, Franche-Comté, and Lorraine, France), and a randomly selected sample of melanomas thinner than 3 mm. MAIN OUTCOME MEASURES Circumstances of diagnosis, clinical and pathological characteristics of melanomas, and sociodemographic characteristics of patients (age, sex, residence, home and family life conditions, educational level, and smoking habits). RESULTS Among 898 melanomas, 149 (16.6%) were VTMs. Very thick melanomas were more often diagnosed in a general-practice setting than thinner melanomas. The rate of immediate clinical recognition by dermatologists was lower for VTMs than for thinner melanomas. In a multivariate logistic regression analysis, factors associated with VTM were the nodular and acrolentiginous types; the head and neck and lower limb locations; older age; male sex; and being single, separated, divorced, or widowed. When only factors related to patients were taken into account, older age, male sex, and living alone were independent risk factors for VTM. The most significant risk was observed for patients living alone. CONCLUSIONS Intrinsic factors related to the tumor and sociodemographic characteristics of patients contribute to the occurrence of VTM. These factors should be better targeted in future secondary prevention programs

Variations in management of stage I to stage III cutaneous melanoma: a population-based study of clinical practices in France.

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Brain endothelial TAK1 and NEMO safeguard the neurovascular unit

Inactivating mutations of the NF-kappa B essential modulator (NEMO), a key component of NF-kappa B signaling, cause the genetic disease incontinentia pigmenti (IP). This leads to severe neurological symptoms, but the mechanisms underlying brain involvement were unclear. Here, we show that selectively deleting Nemo or the upstream kinase Tak1 in brain endothelial cells resulted in death of endothelial cells, a rarefaction of brain microvessels, cerebral hypoperfusion, a disrupted blood-brain barrier (BBB), and epileptic seizures. TAK1 and NEMO protected the BBB by activating the transcription factor NF-kappa B and stabilizing the tight junction protein occludin. They also prevented brain endothelial cell death in a NF-kappa B-independent manner by reducing oxidative damage. Our data identify crucial functions of inflammatory TAK1-NEMO signaling in protecting the brain endothelium and maintaining normal brain function, thus explaining the neurological symptoms associated with IP

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

Systemic lupus erythematosus (SLE) is a systemic autoimmune disease characterized by a loss of tolerance toward self-nucleic acids, autoantibody production, interferon expression and signaling, and a defect in the regulatory T (T(reg)) cell compartment. In this work, we identified that platelets from patients with active SLE preferentially interacted with T(reg) cells via the P-selectin/P-selectin glycoprotein ligand-1 (PSGL-1) axis. Selectin interaction with PSGL-1 blocked the regulatory and suppressive properties of T(reg) cells and particularly follicular T(reg) cells by triggering Syk phosphorylation and an increase in intracytosolic calcium. Mechanistically, P-selectin engagement on T(reg) cells induced a down-regulation of the transforming growth factor-β axis, altering the phenotype of T(reg) cells and limiting their immunosuppressive responses. In patients with SLE, we found an up-regulation of P- and E-selectin both on microparticles and in their soluble forms that correlated with disease activity. Last, blocking P-selectin in a mouse model of SLE improved cardinal features of the disease, such as anti-dsDNA antibody concentrations and kidney pathology. Overall, our results identify a P-selectin-dependent pathway that is active in patients with SLE and validate it as a potential therapeutic avenue

The role of the acquired immune response in systemic sclerosis

Profound alterations characterize the adaptive immune response in systemic sclerosis, and several layers of evidence support a prominent role exerted by immune cellular effectors and humoral mediators in the pathogenesis of this disease. These include (i) the presence of oligoclonal T cells in tissues undergoing fibrosis consistent with (auto)antigen-specific recruitment, (ii) the preferential expansion of polarized CD4+ and CD8+ T cells producing pro-fibrotic cytokines such as IL-4 and IL-13, (iii) the presence of increased number of cells producing mediators belonging to the IL-17 family, including IL-22, which may drive and participate in inflammatory pathways involving epithelial cells as well as fibroblasts, (iv) the deficient or redirected function of T regulatory cells favoring fibrosis, and (v) the enhanced expression of CD19 and CD21 on naïve B cells, and the upregulation of co-stimulatory molecules in mature B cells, which together with the increased levels of B cell activating factor (BAFF) underlie the propensity to an exaggerated humoral response possibly favoring fibrogenesis. Despite all the progress made in understanding the features of the aberrant immune response in scleroderma, it remains unclear whether the activation of immune effector pathways ultimately drives the disease pathogenesis or rather represents a defective attempt to limit or even reverse excessive extracellular matrix deposition and progressive vasculopathy, the main hallmarks of this disease