Mechanisms of tissue injury in vasculitic neuropathies

We studied the expression of candidate molecules for tissue injury in vasculitic neuropathies immunohistochemically, using samples obtained by nerve biopsy from seven patients with necrotizing angitis. In the involved vessels of all samples, numerous infiltrating cells were positive for perforin, nitric oxide synthase (m-NOS), cyclooxygenase-2 (COX-2), or matrix metalloproteinase-1 (MMP-1). Cell-mediated cytotoxicity may be involved in the pathogenesis of small vessel injury in vasculitic neuropathies. In the endoneurium following axonal degeneration, scattered and phagocytosing macrophages showed immunostaining for m-NOS and MMP-1, but COX-2 was all but restricted to phagocytosing macrophages. This suggests a role for prostaglandins in nerve damage.