Low levels of vitamin D and the relationship between vitamin D and Th2 axis-related cytokines in neuromyelitis optica spectrum disorders

Objective: The impact of vitamin D have been studied in neuroinflammation disorders, and as the newly discovered Th2-related cytokines, IL-25, IL-31 and IL-33 may also play important roles in the lesions of neuromyelitis optica spectrum disorders (NMOSD). This study sought to investigate the clinical profiles of vitamin D and Th2 axis-related cytokines and their relationships in patients with NMOSD.

Methods: Eighty-four NMOSD patients and 84 healthy controls (HC) were evaluated for serum levels of the total vitamin D [25(OH)D], 25-hydroxyvitamin D2 [25(OH)D2] and 25-hydroxyvitamin D3 [25(OH)D3] by means of high performance liquid chromatographytandem mass spectrometry (HPLC-MS/MS). Meanwhile, serum AQP4-IgG (n = 84) were detected by an AQP4-transfected cell-based assay (CBA) and IL-25, IL-31, IL-33 (n = 32) were performed using enzyme-linked immunoassay (ELISA) method.

Results: The serum levels of 25(OH)D, 25(OH)D2 and 25(OH)D3 were significantly lower in NMOSD group as compared to HC group. There were also significant differences in serum vitamin D levels between the acute phase group and remission group except the 25(OH)D2 levels (p = 0.070). No correlations were detected between vitamin D and disease activity or vitamin D and disease disability. Furthermore, serum 25(OH)D, 25(OH)D2, and 25(OH)D3 levels were not correlated with serum IL-25, IL-31, and IL-33 levels, the location of lesions and the number of lesion locations.

Conclusion: Our result showed hypovitaminosis D in NMOSD patients. The activity of 25(OH)D3 seemed to be closer to 25(OH)D than 25(OH)D2. Low levels of 25(OH)D/25(OH)D3 might represent a risk factor for the disease activity in patients with NMOSD.