title: High Kynurenine (a Tryptophan Metabolite) Predicts Remission in Patients with Major Depression to Add-on Treatment with Celecoxib.
abstract: BACKGROUND
  Signs of an inflammatory process have been described in major depression.
  
  
  METHODS
  In a double-blind, randomized study of celecoxib or placebo add-on to reboxetine in 40 depressed patients, celecoxib treatment has beneficial effects. In order to evaluate the tryptophan/kynurenine metabolism and to identify predictors for remission, tryptophan (TRP), kynurenine (KYN), kynurenic acid (KYNA), and quinolinic acid (QUIN) were estimated in the serum of 32 patients before and after treatment and in a group of 20 healthy controls.
  
  
  RESULTS
  KYN levels were significantly lower in patients (p= 0.008), and the QUIN/KYN ratios were significantly higher (p= 0.028). At baseline, the higher KYN/TRP ratio was predictive for remission during celecoxib add-on treatment (p= 0.04) as well as for remission in the overall patient group (p= 0.01). In the placebo group, remitters showed a higher KYNA/QUIN ratio (p= 0.032). In the overall group, remitters showed lower KYNA/KYN (p= 0.035) and QUIN/KYN (p= 0.011) ratios. The lower the formation of downstream metabolites, especially QUIN, the better the treatment outcome.
  
  
  CONCLUSIONS
  The high KYN/TRP ratio predicted remission after treatment with celecoxib in this small sample of depressed patients. Eventually, the KYN/TRP ratio might be a marker for those patients, which benefit from an additional anti-inflammatory treatment.
authors.affiliation: Department of Psychiatry and Psychotherapy, Ludwig Maximilian University , Munich , Germany.
authors.forename: Daniela
authors.initials: D
authors.lastname: Krause
authors.affiliation: Department of Psychiatry and Psychotherapy, Ludwig Maximilian University , Munich , Germany.
authors.forename: Aye-Mu
authors.initials: AM
authors.lastname: Myint
authors.affiliation: Institute for Transfusion Medicine, Ernst Moritz Arndt University , Greifswald , Germany.
authors.forename: Christine
authors.initials: C
authors.lastname: Schuett
authors.affiliation: Department of Psychiatry and Psychotherapy, Ludwig Maximilian University , Munich , Germany.
authors.forename: Richard
authors.initials: R
authors.lastname: Musil
authors.affiliation: Department of Psychiatry and Psychotherapy, Ludwig Maximilian University , Munich , Germany.
authors.forename: Sandra
authors.initials: S
authors.lastname: Dehning
authors.affiliation: Department of Psychiatry and Psychotherapy, Ludwig Maximilian University , Munich , Germany.
authors.forename: Anja
authors.initials: A
authors.lastname: Cerovecki
authors.affiliation: Department of Psychiatry and Psychotherapy, Ludwig Maximilian University , Munich , Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Riedel
authors.affiliation: Department of Psychiatry and Psychotherapy, Wilhelm University , Muenster , Germany.
authors.forename: Volker
authors.initials: V
authors.lastname: Arolt
authors.affiliation: Institute of Laboratory Medicine, Ludwig Maximilian University , Munich , Germany.
authors.forename: Markus J
authors.initials: MJ
authors.lastname: Schwarz
authors.affiliation: Department of Psychiatry and Psychotherapy, Ludwig Maximilian University , Munich , Germany.
authors.forename: Norbert
authors.initials: N
authors.lastname: Müller
keywords: celecoxib; cyclooxygenase-2; depression; kynurenines; remission