A preliminary report of increased plasma levels of IL-33 in bipolar disorder: further evidence of pro-inflammatory status.

BACKGROUND

Recent findings suggest an important role for inflammation in the neurobiology of bipolar disorder (BD). Interleukin 33 (IL-33) is a cytokine with multiple functions and may act as a nuclear factor regulating transcription and as an "alarmin". IL-33 exerts part of its function through the receptor ST2 that also exists in a soluble form (sST2). This study was performed to evaluate IL-33 and sST2 plasma levels in BD patients.

METHODS

We evaluated IL33 and sST2 plasma levels of 46 BD patients (23 in euthymia and 23 in mania) and 23 healthy controls using enzyme-linked immunosorbent assay (ELISA). BD patients were age and gender matched healthy controls.

RESULTS

IL-33 levels were higher in BD patients (p=0.02) but there was no difference in sST2 (p=0.55). IL33 and sST2 plasma levels were not correlated with age, neither was influenced by clinical comorbidities nor medications in use.

CONCLUSION

These findings corroborate the view of BD as a multisystem condition with a proinflammatory profile.