Elevated serum free IL-18 in neuropsychiatric systemic lupus erythematosus patients with seizure disorders

Abstract

Background Since dysregulation of total Interleukin (IL)-18 and IL-18 binding protein (IL-18BP) may participate in systemic lupus erythematosus (SLE) and contribute to the occurrence of non-autoimmune epilepsy, the aim of the current work is to investigate whether the interaction between IL-18 and IL-18BP plays any role in neuropsychiatric systemic lupus erythematosus related seizures. Methods Data from 137 SLE patients and 30 healthy controls (HC) were consecutively collected from 2020 to 2021. Serum levels of total IL-18 and IL-18BP for all patients and HC were measured by ELISA test. Free IL-18 was calculated based on the law of mass action. Results Among the 137 SLE patients, 103 had active disease and were classified into NPSLE ( n = 50) and Non-NPSLE ( n = 53) groups. Among the NPSLE patients, 16 had seizure disorders. Serum free IL-18 levels were increased in NPSLE (277.6 [150.9–428.8]pg/mL) and were correlated with disease activity (r = 0.268, p = 0.002). Moreover, serum free IL-18 levels in NPSLE patients with seizure disorders (350.9 [237.9–455.9]pg/mL) were significantly higher than the levels in those with other neuropsychiatric symptoms (237.7 [124.6–428.8] pg/mL). Conclusions The expression of free IL-18 was increased in neuropsychiatric systemic lupus erythematosus(NPSLE), especially in NPSLE related seizures. Also, serum levels of free IL-18 were significantly increased in active SLE patients. In this regard, free IL-18 may be involved in the pathogenesis of NPSLE related seizures and associated with disease activity.