Immune dysfunction in bipolar disorder and suicide risk: is there an association between peripheral corticotropin-releasing hormone and interleukin-1ß?

OBJECTIVE: The aim of the present study was to investigate the relationship between peripheral levels of corticotropin-releasing hormone (CRH) and interleukin-1ß (IL-1ß) in individuals with bipolar disorder (BD) with and without suicide risk (SR), and controls. METHODS: A total of 120 young adults (40 controls, 40 subjects with BD without SR, and 40 subjects with BD with SR) were enrolled from a population-based study carried out in the city of Pelotas, Brazil. BD and SR were assessed through the Mini International Neuropsychiatric Interview (MINI 5.0), and peripheral markers were evaluated by enzyme-linked immunosorbent assay (ELISA). RESULTS: Levels of CRH were significantly lower both in subjects with BD without SR (p = 0.04) and subjects with BD with SR (p = 0.02) when compared to controls. However, levels of IL-1ß were increased in subjects with BD with SR (p = 0.05) when compared to controls. Sociodemographic and clinical variables, current mood episode, and use of psychiatric medications were not associated with changes in these markers. No correlation was found between peripheral levels of CRH and IL-1ß (p = 0.60) in the population or in the BD with SR group (p = 0.88). CONCLUSIONS: These results suggest that peripheral mechanisms linking stress hormones and the immune system might be critical patterns involved in suicidal behavior associated with BD.

Interleukin-1ß is associated with depressive episode in major depression but not in bipolar disorder.

Our work was sought to investigate possible changes in peripheral levels of interleukin-1ß (IL-1ß) according to the diagnosis of major depression (MD) and bipolar disorder (BD) and in different mood episodes. This is a cross-sectional nested in a population-based study comparing 240 young adults (80 controls, 80 MD and 80 BD), balanced for age and gender. Serum levels of IL-1ß were significantly higher in MD when compared to control or BD subjects. In addition, when divided by current mood episode, MD subjects in current depression presented higher IL-1ß levels than controls. No differences in IL-1ß levels were found between different episodes of BD (euthymic, depressed, mania or mixed). Moreover, the use of psychiatric medication was very low in our sample and not associated with changes in IL-1ß levels. In conclusion, increased peripheral IL-1ß might be a useful marker associated with a depressive episode in the context of MD.