Study of inflammation inbipolar disorder: Assessment of inflammatory cytokines

Introduction. The inflammatory process leads to the release of several lipids and protein mediators, including cytokines. Recent studies have associated cytokines and their actions to the physiopathology of Bipolar Disorder (BD). This disorderis characterized bymood changes between pathological(depression or mania) and physiologic (euthymia) states. Objective. To review the literature concerning the measurement of circulating (serum or plasma) levels of cytokines in BD. Method. Articles were searched from01/1980 to01/2013, in English and Portuguese, in the databases MEDLINE and SciELO with the keywords Inflammation, Cytokines and Bipolar Disorder. Articles that evaluated in vitro production of cytokines, or did not perform stratification of patients according to the phase of bipolar disorder (mania depression or euthymia)were excluded. Results. 25 works that evaluated the cytokine levels (serum or plasma) in patients with BD were identified. The cytokines evaluated were:IL-8, INF-γ, IL-1β, TGF-β, IL-12, IL-6, IL-4, IL-10, IL-2, IL-17, IL-5, and TNF-α, and its soluble receptors TNFR1 and sTNFR2, as well as sIL-6R andIL- 1Ra. Although the studies have shown conflicting results regarding the levels of proand anti-inflammatory serum or plasma of patients with TB, there is a tendency towards apro-inflammatory profilein patientsin phase of depressionand mania. Conclusion. This study suggests that immunological parameters, represented by changes in plasma and/or serum cytokines may be related to the pathophysiology of BD.