title: Inflammatory monocyte gene expression: trait or state marker in bipolar disorder?
abstract: BACKGROUND
  This study aimed to examine whether inflammatory gene expression was a trait or a state marker in patients with bipolar disorder (BD).
  
  
  METHODS
  69 healthy controls (HC), 82 euthymic BD patients and 8 BD patients with a mood episode (7 depressed, 1 manic) were included from the MOODINFLAME study. Six of the eight patients who had a mood episode were also investigated when they were euthymic (6 of the 82 euthymic patients). Of these participants the expression of 35 inflammatory genes was determined in monocytes using quantitative-polymerase chain reaction, of which a total gene expression score was calculated as well as a gene expression score per sub-cluster.
  
  
  RESULTS
  There were no significant differences in inflammatory monocyte gene expression between healthy controls and euthymic patients. Patients experiencing a mood episode, however, had a significantly higher total gene expression score (10.63 ± 2.58) compared to healthy controls (p = .004) and euthymic patients (p = .009), as well as when compared to their own scores when they were euthymic (p = .02). This applied in particular for the sub-cluster 1 gene expression score, but not for the sub-cluster 2 gene expression score.
  
  
  CONCLUSIONS
  Our study indicates that in BD inflammatory monocyte, gene expression is especially elevated while in a mood episode compared to being euthymic.
authors.affiliation: ICPE/UCP/Triade (CC.72), Interdisciplinary Center Psychopathology and Emotion Regulation (ICPE), University Medical Center Groningen, University of Groningen, PO Box 30001, 9700 RB, Groningen, The Netherlands. k.becking@umcg.nl.|Department of Psychiatry, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands. k.becking@umcg.nl.
authors.forename: K
authors.initials: K
authors.lastname: Becking
authors.affiliation: Department of Psychiatry, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands. b.c.m.haarman@umcg.nl.|Radiology Morphological Solutions, Berkel en Rodenrijs, The Netherlands. b.c.m.haarman@umcg.nl.
authors.forename: B C M
authors.initials: BC
authors.lastname: Haarman
authors.affiliation: ICPE/UCP/Triade (CC.72), Interdisciplinary Center Psychopathology and Emotion Regulation (ICPE), University Medical Center Groningen, University of Groningen, PO Box 30001, 9700 RB, Groningen, The Netherlands. r.f.riemersma@umcg.nl.|Department of Psychiatry, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands. r.f.riemersma@umcg.nl.
authors.forename: R F Riemersma
authors.initials: RF
authors.lastname: van der Lek
authors.affiliation: Department of Psychiatry, University of Münster, Münster, Germany. laura.sumaski@ukmuenster.de.
authors.forename: L
authors.initials: L
authors.lastname: Grosse
authors.affiliation: Department of Psychiatry, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands. w.a.nolen@umcg.nl.
authors.forename: W A
authors.initials: WA
authors.lastname: Nolen
authors.affiliation: Department of Psychiatry, University of Leuven (KU Leuven), Louvain, Belgium. stephan.claes@uzleuven.be.
authors.forename: S
authors.initials: S
authors.lastname: Claes
authors.affiliation: Department of Immunology, Erasmus MC, Rotterdam, The Netherlands. h.drexhage@erasmusmc.nl.
authors.forename: H A
authors.initials: HA
authors.lastname: Drexhage
authors.affiliation: ICPE/UCP/Triade (CC.72), Interdisciplinary Center Psychopathology and Emotion Regulation (ICPE), University Medical Center Groningen, University of Groningen, PO Box 30001, 9700 RB, Groningen, The Netherlands. r.a.schoevers@umcg.nl.|Department of Psychiatry, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands. r.a.schoevers@umcg.nl.
authors.forename: R A
authors.initials: RA
authors.lastname: Schoevers
keywords: Bipolar disorder; Gene expression; Mood episode; State; Trait