Alterations of the serum N-glycan profile in female patients with Major Depressive Disorder

Abstract

BackgroundGlycans are short chains of saccharides linked to glycoproteins that are known to be involved in a wide range of inflammatory processes. As depression has been consistently associated with chronic low-grade inflammation, we asked whether patients with Major Depressive Disorder show alterations in the N-glycosylation pattern of serum proteins that might be linked to associated changes in inflammatory processes.MethodsIn a study cohort of 21 female patients with an acute depressive episode and 21 non-depressed female control subjects aged between 50 and 69 years, we analyzed the serum N-glycan profile by DNA Sequencer Adapted-Fluorophore Assisted Carbohydrate Electrophoresis (DSA-FACE) and assessed the serum levels of interleukin (IL)− 6, tumor necrosis factor (TNF)-α and C-reactive protein (CRP) by chemiluminescence immunoassays and nephelometry.ResultsCompared to controls, MDD patients showed significant differences in the serum levels of several N-glycan structures. Alterations in the serum N-glycan profile were associated with depressive symptom severity and exploratory analyses revealed that they were most pronounced in MDD patients with a history of childhood sexual abuse. Furthermore, MDD patients showed higher levels of IL-6 and a trend for higher CRP levels, which were also associated with similar alterations in the serum N-glycan profile as those characteristic for MDD patients.LimitationsThe relatively small sample size and the presence of potential confounders (e.g., BMI, smoking, medication).ConclusionThe results offer the first evidence that specific differences in the N-glycosylation pattern of serum proteins constitute a so far unrecognized level of biological alterations that might be involved in the immune changes associated with MDD.