Matrix metalloproteinases in the cerebrospinal fluid of suicide attempters

Abstract

It is increasingly recognized that depression and suicidal behavior are associated with inflammation. Matrix metalloproteinase (MMP) is a family of enzymes involved in the regulation of inflammatory responses. Although elevated MMP-9 production by macrophages have been observed in the ovarian cancer patients suffering from depressive symptoms and chronic stress, it is not known if the expression of different MMPs is altered in depressed or suicidal patients. The aim of the present study was to assess the levels of MMP-1, MMP-3 and MMP-9 in the cerebrospinal fluid (CSF) of suicide attempters.

CSF was collected from 111 suicide attempters and 44 healthy controls. Suicidal ideation and depressive symptoms were evaluated using the Suicide Assessment Scale and the Montgomery – Åsberg Depression Rating Scale (MADRS). Patients were classified according to diagnosis and violent or non-violent suicide attempt. MMP levels in CSF were measured using Mesoscale Discovery multiplex MMP immunoassay. Student´s T-test, Spearman rank correlation coefficient (rho) test and linear regression were used for statistical analysis.

No differences in MMP-1, MMP-3 and MMP-9 levels were observed when all suicide attempters were compared to healthy controls. However, adjustment disorder and substance abuse were significant independent predictors of MMP-1 levels in the CSF of suicide attempters, in models correcting for comorbid psychiatric diagnoses (beta = 0.202, p = 0.031 and beta = 0.226, p = 0.012, respectively).

These results indicate a possible association of MMP-1 with the specific aspects of suicidal behavior and thus could have important implications for the discovery of suicide-associated biomarkers.