Elsevier

Biological Psychiatry

Volume 78, Issue 1, 1 July 2015, Pages 28-37
Biological Psychiatry

Archival Report
Meta-Analysis of Cytokines and Chemokines in Suicidality: Distinguishing Suicidal Versus Nonsuicidal Patients

https://doi.org/10.1016/j.biopsych.2014.10.014Get rights and content

Abstract

Background

Major psychiatric disorders are associated with inflammation. Aberrant cytokine and chemokine levels have been associated with psychiatric disorders and suicidal behavior. We performed a meta-analysis of cytokine and chemokine levels in patients with versus without suicidality and patients with suicidality versus healthy controls.

Methods

We identified articles by searching MEDLINE, PsycINFO, and Thomson Reuters Web of Knowledge databases and the reference lists of identified studies.

Results

Study inclusion criteria were met by 18 studies comprising 583 patients with suicidality, 315 patients without suicidality, and 845 healthy control subjects. Levels of interleukin (IL)-1β and IL-6 were significantly increased in blood and postmortem brain samples of patients with suicidality compared with both patients without suicidality and healthy control subjects (p < .05 for each). In vitro IL-2 production by peripheral blood mononuclear cells was significantly decreased in patients with suicidality compared with both patients without suicidality and healthy controls (p < .01 for each). Cerebrospinal fluid levels of IL-8 were significantly decreased in patients with suicidality versus control subjects (p < .05).

Conclusions

We found evidence for aberrant cytokine levels in blood, cerebrospinal fluid, and postmortem brain samples of patients with suicidality. Levels of IL-1β and IL-6 were most robustly associated with suicidality, and these cytokines may help distinguish suicidal from nonsuicidal patients. Rigorously designed longitudinal studies are needed to evaluate these associations further.

Section snippets

Study Selection

Studies investigating cytokines and chemokines in suicide were systematically searched in MEDLINE (PubMed, National Center for Biotechnology Information, U.S. National Library of Medicine, Bethesda, Maryland), PsycINFO (via Ovid, American Psychological Association, Washington, DC), and Thomson Reuters (formerly ISI) Web of Knowledge (Science Citation Index and Social Sciences Citation Index, Thomson Reuters, Charlottesville, Virginia) in September 2014. The primary search strategy was

Results

As described in Figure 1, search procedures yielded 18 independent studies comprising 583 psychiatric patients with suicidality, 315 psychiatric patients without suicidality, and 845 healthy control subjects for inclusion in the meta-analysis. For cytokine levels in patients with psychiatric disorders with versus without suicidality, 10 studies measuring blood levels of the cytokines IL-1β, IL-2, IL-4, IL-6, IL-10, TNF-α, transforming growth factor (TGF)-β, interferon (IFN)-γ, and C-reactive

Discussion

Our findings suggest that cytokine levels are abnormal in patients with suicidality, most robustly IL-1β and IL-6. Significant increases in in vivo blood levels of these two cytokines distinguished psychiatric patients with suicidality both from psychiatric patients without suicidality and from healthy control subjects. Additionally, both IL-1β and IL-6 were increased in postmortem brain samples of patients with completed suicide. In vitro IL-2 production by peripheral blood mononuclear cells

Acknowledgments and Disclosures

This work was supported by Medical Scholars Program, Medical College of Georgia, Georgia Regents University (CB).

We thank Billy P. Houke for assistance with articles; Dr. Cecilie Bay-Richter, Dr. Lena Brundin, Dr. Shorena Janelidze, Dr. Jussi Jokinen, Dr. Manuella Kaster, Dr. Daniel Lindqvist, Dr. Ghanshyam Pandey, and Dr. Leonardo Tonelli for sharing summary data or clarifying information; and especially Dr. Peter Buckley for his input and insight.

In the past 3 years, BJM has received grant

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