Disability and Depressiveness are Related to IL-18 Serum Levels in the Remission of Multiple Sclerosis

Depression and fatigue are common comorbidities in multiple sclerosis patients, and multiple sclerosis, depression, and fatigue are all associated with dysregulated cytokine production. The serum levels of interleukin-18, C-reactive protein, and uric acid were measured in 48 multiple sclerosis patients in the relapse before and 2 months after corticosteroid treatment, 50 multiple sclerosis remitting patients, and 33 healthy subjects. The severity of depressive symptomatology, fatigue, and disability was assessed using the Beck’s Depression Inventory, the Fatigue Severity Scale, and the Expanded Disability Status Scale, respectively. We also investigated the possible correlation of these biomarkers with clinical symptomatology scores. Multiple sclerosis patients had significantly higher levels of Interleukin-18 compared to healthy control subjects (468.96 ± 840.77 vs. 405.20 ± 146.16 pg/ml, p = 0.017), while there were no differences between groups of patients. We found a moderate positive correlation between levels of Interleukin-18 and C-reactive protein in the relapse phase (p = 0.012, r = 0.305) and a strong negative correlation between levels of Interleukin-18 and uric acid in the remission phase (p = 0.014, r = −0.551). We found a strong positive correlation between concentrations of Interleukin-18 and Beck's Depression Inventory score (p = 0.018, r = 0.535) and a moderate positive correlation with Expanded Disability Status Scale score (p = 0.047, r = 0.462) in the stabilization of multiple sclerosis. Our results may suggest that Interleukin-18 is involved in inflammation in the acute phase and regresses in the stabilization phase, but also in the psychopathology that often occurs after multiple sclerosis.