Abstracts of the 8th Meeting of the Italian Peripheral Nerve Study Group: 87

Abstract

Inflammatory vasculopathy is observed in 20 to 66% of nerve biopsies in diabetic neuropathy, especially in patients with proximal diabetic neuropathy (diabetic amyotrophy) or with other patterns of multifocal neuropathy. Moreover there is growing evidence that diabetic patients have an increased predisposition to Chronic Inflammatory Demyelinating Polyneuropathy (CIDP). Many authors suggest that there is a more pervasive contribution of inflammatory and immuno‐mediated damage to the pathogenesis of diabetic neuropathy than had previously been imagined. In these patients, immunosuppressive therapy is indicated. However differentiating CIDP in diabetic patients from diabetic neuropathy (DNP) may be difficult. We tried to differentiate immuno‐mediated and inflammatory neuropathies in diabetic patients with polyneuropathy revealing the presence of matrix metalloproteinases (MMPs) in the endoneurium. MMPs are calcium‐dependent zinc endopeptidases which are able to degrade the basement membrane and thus contribute to tissue destruction and cell invasion. Sural nerve biopsies were taken from 10 diabetic patients with CIDP and 5 patients with DNP. Immunohistochemistry was performed for T‐cells, macrophages, von Willebrand factor and MMP‐9. Endoneurial and epineurial immunoreactivity was evaluated and quantified separately. Small epineurial T‐cells infiltrates were present in 5 out of 10 CIDP patients and in none of DNP patients. In CIDP patients 53% of endoneurial vessels were immunoreactive for MMP‐9 against only 12% in DNP patients and this difference reached a statistical significance. In conclusion we demonstrated that immunoreactivity of MMP‐9 is strongly enhanced in diabetic patients with CIDP but not in patients with DNP. The pattern of immunoreactivity may help to select patients for a trial with immunosuppressant drugs.