Hypoxia-inducible factor 1alpha may be a marker for vasculitic neuropathy

Neuromuscular biopsy is still an essential method for diagnosing vasculitic neuropathy, although its diagnostic sensitivity is at most 60%. Our objective was to examine the expression of hypoxia-inducible factor 1alpha (HIF-1alpha) in peripheral nerves and to evaluate its usefulness in diagnosing vasculitic neuropathy, especially for discrimination from other axonal neuropathies. Forty-one patients with vasculitic neuropathy consisting of 20 definite, 14 probable and seven possible diagnoses, 15 patients with metabolic neuropathy, five with motor neuron disease and six with chronic inflammatory demyelinating polyneuropathy were included. Nerve biopsy specimens were immunohistochemically examined for HIF-1alpha and various cell markers. Distinct immunoreactivity (IR) was observed in nuclei of endoneurial cells in 54% (22/41) of vasculitic patients, while specimens from metabolic neuropathies showed less nuclear IR and the difference of mean density of HIF-1alpha-positive nuclei was significant. Two patients with possible vasculitis who showed HIF-1alpha-positive nuclei in endoneurium, were later confirmed to have vasculitis by skin biopsies. Most of the cells expressing HIF were demonstrated to be Schwann cells. There was a trend in the vasculitic patients with early phase nerve damage to display higher endoneurial HIF-1alpha-IR. HIF-1alpha may be an immunohistochemical marker for vasculitic neuropathy, especially when the observed section contains no vasculitic lesions.