Research supports immune dysfunction in bipolar disorder
MedWire News: Patients with bipolar disorder display altered plasma chemokine profiles compared with mentally healthy individuals, indicating that the mood disorder is associated with immune dysfunction.
Antônio Lúcio Teixeira (Universidade Federal de Minas Gerais, Belo Horizonte, Brazil) and colleagues explain that "recent evidence has suggested that inflammatory and immune mechanisms may play a role in the pathophysiology of bipolar disorder."
But they add that few studies have investigated levels of chemokines ‑ small proteins defined by their ability to direct the movement of circulating leukocytes to sites of inflammation or injury ‑ in patients with the mood disorder.
To investigate further, the team studied blood samples collected from 70 patients with bipolar I disorder, and 50 age-, gender-, and education level-matched mentally healthy individuals (controls).
Of the bipolar disorder patients, 35 were euthymic and 35 were experiencing an episode of mania at the time of the study. The mean length of illness was 23.4 years and 64.3% were women.
Enzyme-linked immunosorbent assays were used to measure and compare plasma levels of the chemokines CCL2, CCL3, CCL11, CCL24, CXCL8, and CXCL10 between the groups.
The team found that plasma levels of CCL11, CCL24, and CXCL10 were significantly higher in bipolar disorder patients compared with controls, at means of 980.63 versus 579.25 pg/mL, 1203.04 versus 856.63 pg/mL, and 197.85 versus 136.85 pg/mL, respectively.
Conversely, plasma levels of CXCL8 were significantly lower in bipolar disorder patients compared with controls, at 49.19 versus 425.92 pg/mL.
The findings remained largely unchanged after categorizing bipolar disorder patients according to mood state, except that CCL24 levels were found to be higher in euthymic patients compared with controls, but similar in manic patients and controls.
Chemokines levels were not associated with psychiatric comorbidities, substance dependence, or medication use in the bipolar disorder patients, the researchers note.
"Our data reinforce the view that there is an immunological imbalance associated with bipolar disorder trait," Teixeira et al conclude in the European Archives of Psychiatry and Clinical Neuroscience.
By Mark Cowen