Role of Serum IL-6 in Neuropsychiatric Systemic lupus Erythematosus

Abstract

Objective: The present study was designed in order to elucidate the roles of serum interleukin 6 (IL-6) in the pathogenesis in neuropsychiatric systemic lupus erythematosus (NPSLE). Methods: Paired serum and cerebrospinal fluid (CSF) samples were obtained from 101 patients with SLE when they presented active neuropsychiatric manifestations (69 patients with diffuse psychiatric/neuropsychological syndromes [diffuse NPSLE] and 32 patients with neurologic syndromes or peripheral nervous system involvement [focal NPSLE]) and from 22 control patients without SLE with noninflammatory neurological diseases. The levels of albumin and IL-6 in CSF and sera were measured by enzyme-linked immunosorbent assay. Results: Serum IL-6 and CSF IL-6 were elevated in NPSLE compared with non-SLE controls. Among NPSLE, serum IL-6 and CSF IL-6 were significantly elevated in acute confusional state (ACS) compared with non-ACS diffuse NPSLE (anxiety disorder, cognitive dysfunction, mood disorder, and psychosis) or focal NPSLE. Q albumin (CSF/serum albumin quotient) was also significantly higher in ACS than in the other two groups of NPSLE. Of note, serum IL-6 (r = 0.2801, p = 0.0207), but not CSF IL-6 (r = 0.1602, p = 0.1918), was significantly correlated with Q albumin in patients with diffuse NPSLE, including ACS and non-ACS. Conclusion: These results indicate that serum IL-6 as well as CSF IL-6 is involved in the pathogenesis of NPSLE. Moreover, it is suggested that serum IL-6 might play a most important role in blood-brain barrier breakdown in NPSLE.