Elevated levels of serum IL-5 are associated with an increased likelihood of major depressive disorder.
BACKGROUND
Inflammatory mediators in both the peripheral circulation and central nervous system (CNS) are dysregulated in major depressive disorder (MDD). Nevertheless, relatively little is known about the role of the T-helper (Th)-2 effector cytokines interleukin (IL)-5 and IL-13 in MDD.


METHODS
We examined the serum levels of these cytokines and a Th-1 comparison cytokine, interferon (IFN)-γ, in 116 individuals (MDD, n = 58; controls, n = 58).


RESULTS
In our basic multivariate model controlling for the effects of potential confounders on the associations between MDD and the examined cytokines, each 1-unit increase in the serum IL-5 level increased the likelihood of belonging to the MDD group by 76% (OR 1.76, 95% CI 1.03-2.99, p = 0.04; model covariates: age, gender, marital status, daily smoking and alcohol use). The likelihood further increased in models additionally controlling for the effects of the use of antidepressants and NSAIDS, and a diagnosis of asthma. No such associations were detected with regard to IL-13 (OR 1.08, 95% CI 0.96-1.22, p = 0.22) or IFN-γ (OR 1.02, 95% CI 0.99-1.05, p = 0.23).


CONCLUSIONS
Elevated levels of IL-5, which uses the neural plasticity-related RAS GTPase-extracellular signal-regulated kinase (Ras-ERK) pathway to mediate its actions in the central nervous system (CNS), could be one of the factors underlying the depression-related changes in CNS plasticity.
Department of Psychiatry, Kuopio University Hospital and University of Eastern Finland, Kuopio, Finland. apelomaa@gmail.com
Antti-Pekka
AP
Elomaa
Leo
L
Niskanen
Karl-Heinz
KH
Herzig
Heimo
H
Viinamäki
Jukka
J
Hintikka
Heli
H
Koivumaa-Honkanen
Kirsi
K
Honkalampi
Minna
M
Valkonen-Korhonen
Ilkka T
IT
Harvima
Soili M
SM
Lehto
D015415:Biomarkers / Q000097:blood; D003865:Major Depressive Disorder / Q000097:blood* / Q000175:diagnosis; D005260:Female; D006801:Humans; D007371:Interferon-gamma / Q000097:blood; D015848:Interleukin-5 / Q000097:blood*; D008297:Male; D008875:Middle Aged; D008962:Models, Theoretical
D015415:Biomarkers; D015848:Interleukin-5; D007371:Interferon-gamma