Interleukin-6 is associated with tryptophan metabolism and signs of depression in individuals with carbohydrate malabsorption

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Dietmar Enko
Sieglinde Zelzer
Julian Wenninger
Sandra Holasek
Wolfgang J. Schnedl
Andreas Baranyi
Markus Herrmann
Andreas Meinitzer

Abstract

The aim of the present study was to investigate possible associations between interleukin-6 (IL-6), interferon-gamma (INF-γ), tumor necrosis factor-alpha (TNF-α), lactoferrin and lipopolysaccharide binding protein (LBP) with TRP metabolism and signs of depression in a large cohort of outpatients referred for carbohydrate malabsorption testing. Serum concentrations of IL-6, INF-γ, TNF-α, lactoferrin, LBP, tryptophan (TRP), kynurenine (KYN) and kynuric acid were determined in 250 adults referred for lactose and fructose malabsorption testing. All participants filled out the Beck Depression Inventory (BDI). Serum IL-6 levels were positively correlated with the BDI score (p = 0.001, ρ = 0.205) and indicators of TRP metabolism (KYN/TRP ratio, KYN) (P-values < 0.05, ρ = 0.176 and 0.136). Ninety-five individuals with a BDI score > 13 showed significantly higher IL-6 serum levels (1.7 [1.0 – 2.8] vs. 1.1 [0.8 – 1.7] pg/mL, p < 0.001) compared to 115 individuals with a BDI score ≤ 13. LBP showed a positive correlation with the KYN/TRP ratio (p = 0.005, ρ = 0.177). IL-6 and LBP were associated with indicators of TRP metabolism. IL-6 was found to be linked to signs of depression. Individuals with the presence of depressive symptoms showed higher serum IL-6 levels compared to individuals without depressive symptoms.

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How to Cite
Enko, D., Zelzer, S., Wenninger, J., Holasek, S., Schnedl, W. J., Baranyi, A., Herrmann, M., & Meinitzer, A. (2020). Interleukin-6 is associated with tryptophan metabolism and signs of depression in individuals with carbohydrate malabsorption. EXCLI Journal, 19, 1414-1422. https://doi.org/10.17179/excli2020-2940
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Original articles

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