title: Elevated serum levels of IL-6 and IL-17 may associate with the development of ankylosing spondylitis.
abstract: OBJECTIVE
  A meta-analysis was undertaken to examine the correlation between ankylosing spondylitis (AS) progression and serum levels of pro-inflammatory cytokines, Interleukin-6 (IL-6) and Interleukin-17 (IL-17) in AS patients.
  
  
  METHODS
  PubMed, EBSCO, Cochrane Library database, Ovid, Springer link, WANFANG, China national knowledge infrastructure (CNKI) and VIP databases(last updated search in October, 2014) were exhaustively searched for published case-control studies using keywords related to IL-6, IL-17 and AS. The search results were screened using stringent inclusion and exclusion criteria, and the data from selected high-quality studies was analyzed with Comprehensive Meta-analysis 2.0 software.
  
  
  RESULTS
  Thirteen case-control studies were selected for this meta-analysis and contained a pooled total of 514 AS patients and 358 healthy controls. Our main result revealed strikingly higher serum levels of IL-6 and IL-17 in AS patients, compared to healthy controls (IL-6: SMD = 2.51, 95% CI = 1.33~3.70, P = 0.01; IL-17: SMD = 3.05, 95% CI = 2.09~4.02, P < 0.001). Ethnicity-based subgroup analysis showed a statistically correlation of high IL-6 and IL-17 serum levels with AS both in Asian (IL-6: SMD = 3.15, 95% CI = 0.75~5.55, P < 0.001; IL-17: SMD = 3.30, 95% CI = 1.93~4.66, P < 0.001) and Caucasian populations (IL-6: SMD = 1.34, 95% CI = 0.33~2.35, P = 0.009; IL-17: SMD = 2.52, 95% CI = 1.06~3.98, P = 0.001).
  
  
  CONCLUSIONS
  Meta-analysis of pooled data from thirteen high-quality studies revealed a strong correlation between elevated IL-6 and IL-17 serum levels and the development of AS. Therefore, IL-6 and IL-17 could be used as markers for diagnosis and assessment of treatment outcomes in AS patients.
authors.affiliation: Department of Rheumatology and Immunology, The First Teaching Hospital of Tianjin University of Traditional Chinese Medicine Tianjin 300193, China.
authors.forename: Wei
authors.initials: W
authors.lastname: Liu
authors.affiliation: Department of Rheumatology and Immunology, The First Teaching Hospital of Tianjin University of Traditional Chinese MedicineTianjin 300193, China; Institute of Basic Research in Clinical Medicine, China Academy of Chinese Medical SciencesBeijing 100700, China.
authors.forename: Yuan-Hao
authors.initials: YH
authors.lastname: Wu
authors.affiliation: Department of Rheumatology and Immunology, The First Teaching Hospital of Tianjin University of Traditional Chinese Medicine Tianjin 300193, China.
authors.forename: Lei
authors.initials: L
authors.lastname: Zhang
authors.affiliation: Department of Rheumatology and Immunology, The First Teaching Hospital of Tianjin University of Traditional Chinese Medicine Tianjin 300193, China.
authors.forename: Xiao-Ya
authors.initials: XY
authors.lastname: Liu
authors.affiliation: Department of Rheumatology and Immunology, The First Teaching Hospital of Tianjin University of Traditional Chinese Medicine Tianjin 300193, China.
authors.forename: Bin
authors.initials: B
authors.lastname: Xue
authors.affiliation: Department of Rheumatology and Immunology, The First Teaching Hospital of Tianjin University of Traditional Chinese Medicine Tianjin 300193, China.
authors.forename: Yi
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Department of Rheumatology and Immunology, The First Teaching Hospital of Tianjin University of Traditional Chinese Medicine Tianjin 300193, China.
authors.forename: Bin
authors.initials: B
authors.lastname: Liu
authors.affiliation: Department of Rheumatology and Immunology, The First Teaching Hospital of Tianjin University of Traditional Chinese Medicine Tianjin 300193, China.
authors.forename: Qiao
authors.initials: Q
authors.lastname: Jiang
authors.affiliation: Department of Rheumatology and Immunology, The First Teaching Hospital of Tianjin University of Traditional Chinese Medicine Tianjin 300193, China.
authors.forename: Hou-Wen
authors.initials: HW
authors.lastname: Kwang
authors.affiliation: Department of Rheumatology and Immunology, The First Teaching Hospital of Tianjin University of Traditional Chinese Medicine Tianjin 300193, China.
authors.forename: Dong-Jing
authors.initials: DJ
authors.lastname: Wu
keywords: Ankylosing spondylitis; interleukin-17; interleukin-6; meta-analysis; rheumatism; spondyloarthropathies