title: Comparison of pro-inflammatory cytokines among patients with bipolar disorder and unipolar depression and normal controls.
abstract: OBJECTIVE
  Research evidence has shown that bipolar disorder (BD) and unipolar depression (UD) are both related to inflammatory dysregulation, but few studies have compared the levels of cytokines between these two disorders.
  
  
  METHODS
  Study subjects were age- and gender-matched outpatients with BD or UD and normal controls (NC). Severities of depression and mania symptoms were assessed with the Montgomery-Åsberg Depression Rating Scale (MADRS) and the Young Mania Rating Scale (YMRS). Pro-inflammatory cytokines, including soluble interleukin-6 receptor (sIL-6R), soluble interleukin-2 receptor (sIL-2R), C-reactive protein (CRP), soluble tumor necrosis factor receptor type 1 (sTNF-R1), soluble p-selectin receptor (sP-selectin), and monocyte chemotactic protein-1 (MCP-1), were assessed in all subjects by enzyme-linked immunosorbent assays.
  
  
  RESULTS
  In all, 130 patients with BD, 149 patients with UD, and 130 NC were enrolled in the study; 67.6% were female and the average age was mean ± standard deviation (SD) 43.5 ± 11.8 years. The BD group had a significantly higher smoking rate, more medical comorbidity, higher body mass index (BMI), and higher levels of sIL-2R, sIL-6R, CRP, sTNF-R1, and MCP-1 (all p < 0.01) than the UD and NC groups. When the remitted patients with BD (YMRS scores ≤ 12) were compared with the patients with UD, controlling for age, MADRS score, smoking, medical comorbidity, and BMI in the regression model, the results showed that the BD group had significantly higher levels of sIL-6R (p < 0.001), CRP (p = 0.045), sTNF-R1 (p = 0.036), and MCP-1 (p = 0.001) than the UD group.
  
  
  CONCLUSIONS
  Higher levels of sIL-6R, CRP, sTNF-R1, and MCP-1 were noted in BD than in UD. These results may suggest a more severe inflammatory dysregulation in BD. Further studies are required to investigate whether these cytokines could be biomarkers for affective disorders.
authors.affiliation: Department of Psychiatry, Taipei Veterans General Hospital; Department of Psychiatry, College of Medicine, National Yang-Ming University.
authors.forename: Ya-Mei
authors.initials: YM
authors.lastname: Bai
authors.forename: Tung-Ping
authors.initials: TP
authors.lastname: Su
authors.forename: Cheng-Ta
authors.initials: CT
authors.lastname: Li
authors.forename: Shih-Jen
authors.initials: SJ
authors.lastname: Tsai
authors.forename: Mu-Hong
authors.initials: MH
authors.lastname: Chen
authors.forename: Pei-Chi
authors.initials: PC
authors.lastname: Tu
authors.forename: Wen-Fei
authors.initials: WF
authors.lastname: Chiou
mesh_terms: D000328:Adult; D015415:Biomarkers; D001714:Bipolar Disorder / Q000276:immunology*; D015992:Body Mass Index; D002097:C-Reactive Protein / Q000276:immunology; D016022:Case-Control Studies; D018932:Chemokine CCL2 / Q000276:immunology; D016207:Cytokines / Q000276:immunology*; D003866:Depressive Disorder / Q000276:immunology; D003865:Major Depressive Disorder / Q000276:immunology*; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D019007:P-Selectin / Q000276:immunology; D011569:Psychiatric Status Rating Scales; D015375:Receptors, Interleukin-2 / Q000276:immunology; D019947:Receptors, Interleukin-6 / Q000276:immunology; D047888:Receptors, Tumor Necrosis Factor, Type I / Q000276:immunology
chemical_list: D015415:Biomarkers; C111835:CCL2 protein, human; D018932:Chemokine CCL2; D016207:Cytokines; D019007:P-Selectin; D015375:Receptors, Interleukin-2; D019947:Receptors, Interleukin-6; D047888:Receptors, Tumor Necrosis Factor, Type I; C546937:SELP protein, human; C506235:TNFRSF1A protein, human; D002097:C-Reactive Protein
keywords: bipolar disorder; pro-inflammatory cytokines; unipolar depression