Proinflammatory cytokines in patients with bipolar disorder and borderline personality disorder

This study aims to compare levels of serum proinflammatory cytokines and receptors such as TNF-α, sTNFR-I, sTNFR-II, IL-2, sIL-2R, IL-6, sIL-6R, IL-1α, IL-1β, IFN-γ and IL-17 in patients with bipolar disorder (BD), borderline personality disorder (BPD) and healthy controls. By doing so we aimed to find out whether proinflammatory cytokines and /or receptors may be used as biomarkers in future to assess the etiopathogenesis of both psychopathologies, differentiate between similar and non-similar features and to evaluate new treatment options. Twenty-six female patients with BD type I in euthymic period and twenty-six female patients with BPD according to DSM-5 diagnostic criteria were included in the study. Also twenty-seven healthy female volunteers without any psychiatric disorders according to DSM-5 were used as control group. Serum samples were collected from all participants, cytokine and cytokine receptor levels were evaluated by ELISA method and compared. Levels of serum IL-1β were significantly lower in BD in comparison to the control group. In terms of other cytokine and cytokine receptors, there was no statistically significant difference between BD, BPD and the control group. Levels of sIL-6R, IFN-γ, TNF-α, sTNFR-II, IL-2 and IL-1β were found to be higher in patients with BPD who have a family history of psychiatric disorders. In addition, levels of sTNFR-I in BD were lower in patients who had been subject to lithium treatment and with longer duration of euthymia. The data obtained from our study suggests that BD and BPD may be similar psychopathologies. However, it is not possible to use cytokines as biomarkers in clinical practice to distinguish BD and BPD as of yet. We assert clinical features that might be related to cytokines should also be taken in to consideration. It is predicted that more comprehensive data can be obtained by providing larger participant pool with standardised treatment and by evaluating the same participants across different periods.