Elevated interleukin-18 serum levels in chronic schizophrenia: Association with psychopathology

Elevated serum levels of TNF-α, IL-6 and IL-18 in chronic schizophrenic patients

“…Our results showed elevated levels of TNF-α, IL-6 in patients, providing further supporting evidence for the "macrophage Tlymphocyte" hypothesis. In addition, we found elevated serum levels of IL-18 in patients, which was agreed with previous studies in Japanese, Italian and Chinese schizophrenic patients (Reale et al, 2011;Palladino et al, 2012;Xiu et al, 2012). Since IL-18 is a member of the IL-1 family of proinflammatory cytokines and plays an important role in the activation of Th1 cells, our present result of increased IL-18 also support the activated macrophage theory.…”

“…Schizophrenia patients showed significant altered levels of blood interleukin-1 RA (IL-1RA), sIL-2R, IL-6 and tumor necrosis factoralpha (TNF-α) (Potvin et al, 2008;Song et al, 2013). Several recent studies have shown that IL-18 levels, a member of the IL-1 family of proinflammatory cytokines, are remarkably higher in schizophrenic patients than in controls and are correlated with the psychopathology of schizophrenia (Reale et al, 2011;Palladino et al, 2012;Xiu et al, 2012). Howerver,there were inconsistent of the findings about serum levels of cytokines.…”

“…In addition, duration of illness, antipsychotic dose and PANSS scores did not significantly correlate with serum levels of TNF-α, IL-6 and IL-18 in schizophrenic patients. It has been reported that a significant positive association between IL-18 and the PANSS general psychopathology subscore (Xiu et al, 2012). These inconsistencies may result from the heterogeneity of schizophrenia, the relative small number of subjects, and potential confounding factors.…”

Relationship of serum levels of TNF-α, IL-6 and IL-18 and schizophrenia-like symptoms in chronic ketamine abusers

“…Therefore, IL-18 appears to be a communication signal between the nervous and immune systems, mediating neuroinflammatory and neurodegenerative processes as well as influencing homeostasis and behavior (Alboni et al, 2010). Previous studies in Japanese, Italian and Chinese schizophrenic patients have shown that Il-18 level was remarkably higher in schizophrenia patients than in controls (Tanaka et al, 2000; Reale et al, 2011; Xiu et al, 2012; Palladino et al, 2012; Luo et al, 2014) indicating alterations of IL-18 may be involved in pathophysiology of schizophrenia. To date, there have been no reports to study the role of IL-18 in ketamine animal or human model of schizophrenia.…”

The immune system and schizophrenia: an update for clinicians

“…To reduce the role of this major confounding factor, it may be important to study changes in cytokine levels during the first psychotic episode in drugnaive patients. In one of the few studies to include drugnaive participants, Xiu et al (2012) found that levels of serum IL18, a proinflammatory cytokine, were significantly increased in patients on antipsychotic medication for chronic schizophrenia compared with drug naive patients with firstepisode psychosis and healthy controls, and also that IL18 levels were positively correlated with severity of symptoms.…”