The association between serum levels of TNF-α and IL-6 in schizophrenic patients and their metabolic status - A case control study.

According to immunological theory of schizophrenia, dysfunctions of the immune system are linked with the pathology of schizophrenia. Among cytokines, tumor necrosis factor alpha (TNF-α) and interleukin 6 (IL-6) seem to be correlated with psychopathology of schizophrenia. Both IL-6 and TNF-α are produced in the fat tissue by adipocytes. Thus, cytokine levels in obese patients are increased compared with healthy subjects. These metabolic underlying mechanisms may be an important confounding factor in the studies on cytokines levels in schizophrenia. The aim of this study was to evaluate how metabolic alterations affect peripheral IL-6 and TNF-α levels in schizophrenia patients. This was a case-control study, 30 schizophrenia patients were recruited in the study group and 30 healthy subjects were matched by sex and age. Serum levels of TNF-α and Il-6 were measured using ELISA test, together with detailed anthropometric, laboratory and body composition parameters (determined using bioelectric impedance analysis). Serum TNF-α concentration in the schizophrenia group was 6.05 ± 1.61 ng/mL and 5.94 ± 1.26 ng/mL in the control group. The difference between these two groups was not significant (p = .79). Serum IL-6 concentration in the schizophrenia group was 1.54 ± 1.46 ng/mL and in the control group 1.39 ± 1.39 ng/mL. Again, the difference was not significant (p = .51). We have analysed the relationship between anthropometric and metabolic variables and serum IL-6 and TNF-α concentrations. In conclusion, TNF-α was more sensitive to metabolic alterations compared with IL-6. This observation may be beneficial for further research on immune system in schizophrenia, indicating that studies of IL-6 and TNF-α should be controlled at least for major metabolic parameters (BMI, WHR).

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