Elevated serum level of type-2 cytokine and low IL-17 in first episode psychosis and schizophrenia in relapse.

Schizophrenia is chronic and debilitating mental disorder. In broad spectrum of possible causes or contributing factors, immune system and cytokines were investigated in the onset and development of schizophrenia. The aim of our study was to analyze the serum concentrations of type-1 cytokines: TNF-α, IFN-γ, type-2 cytokines: IL-4, IL-10, type-17 cytokine: IL-17 and regulatory cytokines: TGF-β, IL-27, IL-6, in drug-naive patients with First Episode Psychosis - FEP (n = 88) and Schizophrenia in relapse - SC in relapse patients (n = 45), comparing to healthy controls (n = 36). Also, we attempted to determine potential correlation between cytokine levels and/or cytokine ratios with clinical parameters, such as severity of illness, positive, negative and general psychopathology. Our results showed decreased levels of IL-17 (p = 0.018), demonstrating that type-17 response is blunted in psychotic episode. Increased levels of IL-4 (p = 0.033) showed that type-2 response is overweight in psychotic episode. Also, levels of IL-4 in serum of SC in relapse patients were higher than controls (p < 0.0005) and patient with FEP (p = 0.003). This alteration was accompanied with increase in production of TGF-β in psychotic patients (p = 0.009) and also in FEP (p < 0.0005) and SC in relapse (p < 0.0005). Analysis showed that TGF-β can be a valuable marker for psychosis. The presence of enhanced anti-inflammatory/immunosuppressive activity in schizophrenia may be an attempt to counteract or limit ongoing pro-inflammatory processes and downregulating chronic inflammation. Finally we have documented decreased levels of IL-17 and IL-17/TGF-β ratio in these types of psychotic patients, suggesting the new aspects of schizophrenia pathophysiology.