Associations between serum levels of alpha-calcitonin gene-related peptide and clinical features of neuromyelitis optica spectrum disorders

Neuromyelitis optica spectrum disorders (NMOSD) are characterized by severe inflammation-mediated astrocytopathy in the central nervous system. Neuropathic pain (NP) is highly prevalent among patients with NMOSD, and significantly impairs their quality of life. Alpha-calcitonin gene-related peptide (α-CGRP) is a neuropeptide related to pain and neuroinflammation in the central and peripheral nerves; however, the involvement of α-CGRP in NMOSD pathophysiology remains unexplored. Here, we measured serum levels of α-CGRP in 33 patients with NMOSD and 36 healthy controls by enzyme-linked immunosorbent assay to clarify associations between serum α-CGRP levels and clinical NMOSD features, including NP. The NMOSD patients showed significantly higher serum α-CGRP levels than healthy controls [median (interquartile range), ng/mL; 1.89 (1.66–2.39) vs 1.54 (1.34–1.87), p = 0.008]. NMOSD patients with sensory or bowel and bladder dysfunction had elevated serum α-CGRP levels compared with those without [2.02 (1.76–2.80) vs 1.76 (1.44–1.95), p = 0.049; 2.19 (1.96–2.86) vs 1.71 (1.40–1.90), p < 0.001, respectively]. Serum α-CGRP levels were higher in NMOSD patients with neuropathic pain than in those without [2.00 (1.71–2.76) vs 1.78 (1.51–1.97), p = 0.120]. NMOSD patients with spinal cord lesions on magnetic resonance imaging showed significantly higher serum α-CGRP levels compared with those without [2.02 (1.73–2.83) vs 1.73 (1.36–1.87), p = 0.044]. These findings indicate an association between α-CGRP and NMOSD pathophysiological status, especially sensory and bowel and bladder dysfunction derived from spinal cord lesions.