Increased serum matrix metalloproteinase-9 (MMP-9) levels in young patients during bipolar depression

Background: Matrix metalloproteinase-9 (MMP-9) is an enzyme implicated in a number of pathological conditions such as cardiovascular disease, cancer, and neuropsychiatric disorders. Increased blood levels of MMP-9 were found in cancer, heart disease and migraine. Molecular-genetic studies demonstrated an association of functional polymorphism of MMP-9 gene with predisposition to schizophrenia and bipolar illness. In this first study of serum MMP-9 in psychiatric illness, we estimated it in patients with bipolar mood disorder both during depression or mania as well as during immediate remission after these episodes. Methods: The study was performed on 54 in-patients with bipolar mood disorder (19 males, 35 females), aged 42 +/- 14 years. Thirty were studied during acute episode and immediate remission after depression, and 24 during acute episode and immediate remission after mania. The control group consisted of 29 subjects (15 males, 14 females) aged 40 +/- 11 years. Serum MMP-9 was estimated by ELISA. Results: In patients with bipolar illness, a significant correlation of MMP-9 levels was obtained with age. Younger patients with depression (below or equal 45 years of age), both during acute episode and in remission after depression had significantly higher MMP-9 levels compared to those with acute episode and remission after mania and control subjects. Limitations: Relatively small number of patients, who were receiving different antidepressant, antipsychotic and mood stabilizing drugs that might have influenced MMP-9 levels. Conclusions: Increased levels of serum MMP-9 during depression in young patients may indicate this phenomenon as a possible biochemical marker for staging of bipolar disorder. (c) 2012 Elsevier B.V. All rights reserved.