Overview of vasculitis: classification and pathogenesis

Abstract

The aetiology of the primary systemic vasculitides remains obscure. Recent years have seen significant advances in our understanding of relevant mechanisms of inflammation and in particular the role of, and interactions between, the vascular endothelium, inflammatory mediators and immune effector cells. This has helped to elucidate further those specific processes relevant to vasculitis which result in endothelial cell damage. In Wegener's granulomatosis and microscopic polyarteritis the evidence favours an autoimmune inflammatory response, characterized by specific mediators in which the endothelium is both target and active participant. The focal nature of the lesions seen in systemic vasculitis as evident in the kidney is unlike that of other immune-mediated renal diseases and has yet to be explained. Similarly, in the absence of immune complex deposition, the mechanism of endothelial injury and the contribution to the injury by humoral and cell-mediated mechanisms need to be studied further. Other potential mechanisms of injury need to be explored. Increased understanding of the pathogenesis of systemic vasculitis is likely to provide the basis for the use of more selective immunomodulatory therapies in the future.