Pemphigus is a rare autoimmune disease involving skin and mucous membranes characterized by the production of pathogenic autoantibodies directed against desmosomal transmembrane glycoproteins belonging to the cadherin family,responsible for the disruption of desmosomes leading to the acantholysis phenomenon.Two main classical subtypes of pemphigus have been individualized:pemphigus vulgaris and foliaceus,in which pathogenic autoantibodies are directed against desmoglein 3 and 1 respectively.The knowledge about B-cell populations responsible for pemphigus activity increased a lot.In pemphigus patients,B-cell population was shown to comprise auto-reactive B lymphocytes producing antibodies targeting desmogleins,directly responsible for disease activity,and regulatory B lymphocytes.After rituximab treatment,clinical activity was proved to be associated with circulating auto-antibodies high titers and an increase of auto-reactive B-cells,whereas clinical remission was associated with a change in B-cell populations,as B cell repertoire changed from oligoclonal to polyclonal when reconstituting after treatment,with an increase of immatures and transitional B-cells producing IL-10.The mechanisms leading to autoreactive B-cells appearance,the precise role of B-reg in immune tolerance and the factors triggering the imbalance between pro autoimmune and regulatory immune B-cells leading to pemphigus activity remain to be discovered.Polymorphonuclear neutrophil granulocytes(PMN) are the first responders of the immune system to threats by invading microorganisms.Since 2004, PMN were shown to produce neutrophil extracellular traps(NET),structures consisting of decondensed chromatin embedded with histones,granular and cytoplasmic proteins that trap and kill microbes.In lupus recent works demonstrated evidences that NETs components are found in immune complexes responsible for tissue inflammation and that polyclonal activation of B-cell as well as memory B-cell activation could be obtain in presence of immune complexes derived from NET.Besides lupus,other works showed evidence of NETs implication in inflammatory and auto-immune states in rheumatoid arthritis and small vessel vasculitis.The hypotheses is that B-cell activation by NET might not be restricted to autoimmune diseases of which antibodies target NETs components.The aim is to assess the effects on B-cell activation and the phenotypic changes in B-cell population from pemphigus patients after stimulation by NET.
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Involvement of neutrophil extracellular traps (NETs) in the activation of B lymphocytes in Pemphigus
Timeframe: 9 months after inclusion