[Pathophysiology of systemic sclerosis].

Systemic sclerosis (SSc) is an orphan disease affecting the connective tissue. The cause of SSc remains unknown but is likely to involve environmental factors in a genetically primed individual with SSc belonging to the multigenic disorders. Pathogenesis is dominated by early microvascular changes targeting endothelial cells and with the release of several mediators promoting an inflammatory response and vascular remodelling. Several lines of evidence position autoimmunity as a key perpetuating event with activation of both innate and adaptive immunity and with the production of distinct autoantibodies. The cascade ultimates with the fibrosis defined by accumulation of extra-cellular matrix through an imbalance between synthesis and degradation of several components and mesenchymal cell activation and differentiation controlled by a large number of autocrine and paracrine factors.