**2. Pathogenesis of peripheral neuropathy in ANCA vasculitis**

Peripheral neuropathy in AAV is caused by thrombosis and ischemic damage of the vasa nervorum. Different etiological agents may induce vascular

inflammation [4]. Vascular injury is associated with neoantigens (usually infectious) on the endothelium and neutrophils. Eosinophils contribute to vessel inflammation, as seen in GEPA [5]. Immune complexes with certain immunochemical characteristics activate a complement cascade that induces neutrophil-mediated damage to the vessel wall. The presence of granulocytes is associated with fibrinoid necrosis as they release toxic enzymes during inflammation. Antineutrophil cytoplasmic antibodies identify constituents of neutrophil cytoplasm including proteinase 3 (PR3), myeloperoxidase (MPO) and elastase. The release of these cytoplasmic components induces the release of inflammatory mediators such as TNFα [6]. Inflammation of vasa nervorum leads to ischemia with axonal degeneration that mainly presents as mononeuritis multiplex [7].
