Increased level of serum cytokines, chemokines and adipokines in patients with schizophrenia is associated with disease and metabolic syndrome.

At present there are strong indications of a shared vulnerability factor for schizophrenia (SZ), diabetes and the metabolic syndrome (metS). In this study we focus on an aberrantly activated monocyte/macrophage system as the shared factor. We measured in SZ patients (n=144), the serum levels of monocyte/macrophage cytokines/chemokines/adipokines CCL2, CCL4, IL-1β, TNF-α, IL-6, PTX3, leptin, adiponectin, PAI-1, OPG and ICAM-1 and compared these levels to healthy controls (HC) (n=138). Using multivariate analysis, we studied the effect of the presence of the disease SZ, the components of the metS including BMI, the levels of lipids (HDL cholesterol and triglycerides (TG)), diabetes (hyperglycemia) and the use of antipsychotic medication, on the serum levels of these immune compounds. We found all measured immune compounds with the exception of PAI-1 and OPG to be elevated in the SZ patient population. Multivariate analysis showed that elevations were linked to gender (ICAM-1, leptin, TNF-α and adiponectin), an increased BMI (leptin, adiponectin), hyperglycemia/diabetes (CCL4, and OPG), reduced HDL-cholesterol or increased levels of TG (adiponectin and PTX3) or the metS (CCL2, leptin and adiponectin). IL-1β and IL-6 were the only immune compounds raised in the serum of patients not affected by any of the included factors. Although many of the immune compounds were found linked to (components of) the metS, the most dominant linkage was found with the disease schizophrenia, confirming earlier reports on increased monocyte/macrophage activation as a key component for understanding the pathogenesis of schizophrenia.