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A large-scale genome-wide gene expression analysis in peripheral blood identifies very few differentially expressed genes related to antidepressant treatment and response in patients with major depressive disorder.

ABSTRACT: A better understanding of the biological factors underlying antidepressant treatment in patients with major depressive disorder (MDD) is needed. We perform gene expression analyses and explore sources of variability in peripheral blood related to antidepressant treatment and treatment response in patients suffering from recurrent MDD at baseline and after 8 weeks of treatment. The study includes 281 patients, which were randomized to 8 weeks of treatment with vortioxetine (N = 184) or placebo (N = 97). To our knowledge, this is the largest dataset including both gene expression in blood and placebo-controlled treatment response measured by a clinical scale in a randomized clinical trial. We identified three novel genes whose RNA expression levels at baseline and week 8 are significantly (FDR < 0.05) associated with treatment response after 8 weeks of treatment. Among these genes were SOCS3 (FDR = 0.0039) and PROK2 (FDR = 0.0028), which have previously both been linked to depression. Downregulation of these genes was associated with poorer treatment response. We did not identify any genes that were differentially expressed between placebo and vortioxetine groups at week 8 or between baseline and week 8 of treatment. Nor did we replicate any genes identified in previous peripheral blood gene expression studies examining treatment response. Analysis of genome-wide expression variability showed that type of treatment and treatment response explains very little of the variance, a median of <0.0001% and 0.05% in gene expression across all genes, respectively. Given the relatively large size of the study, the limited findings suggest that peripheral blood gene expression might not be the best approach to explore the biological factors underlying antidepressant treatment.

SUBMITTER: Nohr AK

PROVIDER: S-EPMC8134553 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:In Major Depressive Disorder (MDD), treatment outcomes with currently available strategies are often disappointing. Therefore, it is sensible to develop new strategies to increase remission rates in acutely depressed patients. Many studies reported that true drug response can be observed within 14 days (early improvement) of antidepressant treatment. The identical time course of symptom amelioration after early improvement in patients treated with antidepressants of all classes or with placebo strongly suggests a common biological mechanism, which is not specific for a particular antidepressant medication. However, the biology underlying early improvement and final treatment response is not understood and there is no established biological marker as yet, which can predict treatment response for the individual patient before initiation or during the course of antidepressant treatment. Peripheral blood markers and executive functions are particularly promising candidates as markers for the onset of action and thus the prediction of final treatment outcome in MDD.The present paper presents the rationales, objectives and methods of a multi-centre study applying close-meshed repetitive measurements of peripheral blood and neuropsychological parameters in patients with MDD and healthy controls during a study period of eight weeks for the identification of biomarkers for the onset of antidepressants' action in patients with MDD. Peripheral blood parameters and depression severity are assessed in weekly intervals from baseline to week 8, executive performance in bi-weekly intervals. Patients are participating in a randomized controlled multi-level clinical trial, healthy controls are matched according to mean age, sex and general intelligence.This investigation will help to identify a biomarker or a set of biomarkers with decision-making quality in the treatment of MDD in order to increase the currently disappointing remission rates of antidepressant treatment.

Project description:Major depressive disorder (MDD) is one of the most prevalent major psychiatric disorders with a lifetime prevalence of 17%. Recent evidence suggests MDD is not only a brain dysfunction, but a systemic disease affecting the whole body. Central and peripheral inflammatory changes seem to be a centerpiece of MDD pathology: a subset of patients show elevated blood cytokine and chemokine levels that partially normalize with symptom improvement over the course of anti-depressant treatment. As this inflammatory process in MDD is poorly understood, we hypothesized that the peripheral tissues of MDD patients will respond differently to inflammatory stimuli, resulting in an aberrant transcriptional response to elevated pro-inflammatory cytokines. To test this, we used MDD patient- and control-derived dermal fibroblast cultures to investigate their response to an acute treatment with IL6, IL1?, TNF?, or vehicle. Following RNA isolation and subsequent cDNA synthesis, quantitative PCR was used to determine the relative expression level of several families of inflammation-responsive genes. Our results showed comparable expression of the tested genes between MDD patients and controls at baseline. In contrast, MDD patient fibroblasts had a diminished transcriptional response to IL6 in all the gene sets tested (oxidative stress response, mitochondrial function, and lipid metabolism). We also found a significant increase in baseline and IL6 stimulated transcript levels of the IL6 receptor gene. This IL6 receptor transcript increase in MDD fibroblasts was accompanied by an IL6 stimulated increase in induction of SOCS3, which dampens IL6 receptor signaling. Altogether our results demonstrate that there is an altered transcriptional response to IL6 in MDD, which may represent one of the molecular mechanisms contributing to disease pathophysiology. Ultimately we hope that these studies will lead to validation of novel MDD drug targets focused on normalizing the altered IL6 response in patients.

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A large-scale genome-wide gene expression analysis in peripheral blood identifies very few differentially expressed genes related to antidepressant treatment and response in patients with major depressive disorder.

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