Increased Concentrations of Interleukin-33 in the Serum and Cerebrospinal Fluid of Patients with Multiple Sclerosis

Interleukin (IL)-33 is a cytokine with both pro- and anti-inflammatory effects involved in the pathogenesis of some inflammatory diseases. The purpose of this investigation was to evaluate the serum and cerebrospinal fluid (CSF) IL-33 concentrations in patients with multiple sclerosis (MS).

Blood specimens were obtained from 140 patients with MS (46 males and 94 females) with various disease patterns and treatment plans and 140 healthy subjects (47 males and 93 females), who acted as a control group. CSF samples were collected from 20 MS group and 20 sex- and age-matched patients with other neurological diseases of nonautoimmune etiology. The serum and CSF concentrations of IL-33 were measured by the enzyme-linked immunosorbent assay.

The serum and CSF IL-33 levels were significantly higher in the MS group compared to the control group (p<0.001 and p<0.050, respectively). The serum IL-33 concentrations were also significantly higher in newly diagnosed (untreated) patients and patients treated with methylprednisolone or with interferon-β and methylprednisolone compared to the healthy patient group (p<0.007, p<0.002, and p<0.010, respectively). Moreover, the serum IL-33 concentrations in patients with relapsing-remitting (RRMS), primary progressive (PPMS), and secondary progressive (SPMS) forms of the disease were significantly higher than in the healthy control group (p<0.006, p<0.001, and p<0.020, respectively).

Our results showed increased concentrations of IL-33 in patients with MS including both untreated and treated MS patients and patients with the RRMS, SPMS, and PPMS forms. This suggests that IL-33 may be involved in the pathogenesis of all MS forms and treatment with methylprednisolone or both interferon-β plus methylprednisolone has no influence on IL-33 concentrations.