title: Inflammatory cytokines are overexpressed in the subacromial bursa of frozen shoulder.
abstract: BACKGROUND
  Frozen shoulder is a debilitating condition characterized by gradual loss of glenohumeral motion with chronic inflammation and capsular fibrosis. Yet its pathogenesis remains largely unknown. We hypothesized that the subacromial bursa may be responsible for the pathogenesis of frozen shoulder by producing inflammatory cytokines.
  
  
  METHODS
  We obtained joint capsules and subacromial bursae from 14 patients with idiopathic frozen shoulder and from 7 control subjects to determine the expression levels of interleukin (IL) 1α, IL-1β, IL-6, tumor necrosis factor α (TNF-α), cyclooxygenase (COX) 1, and COX-2 by real-time reverse transcriptase-polymerase chain reaction, immunohistochemistry, and enzyme-linked immunosorbent assay.
  
  
  RESULTS
  IL-1α, IL-1β, TNF-α, COX-1, and COX-2 were expressed at significantly high levels in the joint capsules of the frozen shoulder group compared with those of the control group. Intriguingly, IL-1α, TNF-α, and COX-2 were also expressed at significantly high levels in the subacromial bursae of the frozen shoulder group compared with those of the control group. Immunohistochemical analysis showed increased expression of COX-2 in both the joint capsules and subacromial bursae of the frozen shoulder group.
  
  
  CONCLUSIONS
  These findings imply that elevated levels of inflammatory cytokines in the subacromial bursa may be associated with the pathogenesis of inflammation evolving into fibrosis.
authors.affiliation: Pain Research Center, Department of Biochemistry, School of Medicine, Keimyung University, Daegu, South Korea.
authors.forename: Yun-Mee
authors.initials: YM
authors.lastname: Lho
authors.forename: Eunyoung
authors.initials: E
authors.lastname: Ha
authors.forename: Chul-Hyun
authors.initials: CH
authors.lastname: Cho
authors.forename: Kwang-Soon
authors.initials: KS
authors.lastname: Song
authors.forename: Byung-Woo
authors.initials: BW
authors.lastname: Min
authors.forename: Ki-Cheor
authors.initials: KC
authors.lastname: Bae
authors.forename: Kyung-Jae
authors.initials: KJ
authors.lastname: Lee
authors.forename: Ilseon
authors.initials: I
authors.lastname: Hwang
authors.forename: Hyung-Bin
authors.initials: HB
authors.lastname: Park
mesh_terms: D001182:Arthroscopy; D002061:Bursa, Synovial / Q000378:metabolism*; D002062:Bursitis / Q000378:metabolism* / Q000601:surgery; D051545:Cyclooxygenase 1 / Q000096:biosynthesis; D016207:Cytokines / Q000096:biosynthesis*; D006801:Humans; D007249:Inflammation / Q000378:metabolism; D015850:Interleukin-6 / Q000096:biosynthesis; D017746:Joint Capsule / Q000378:metabolism*; D014409:Tumor Necrosis Factor-alpha / Q000096:biosynthesis
chemical_list: D016207:Cytokines; C508600:IL6 protein, human; D015850:Interleukin-6; D014409:Tumor Necrosis Factor-alpha; D051545:Cyclooxygenase 1; C496511:PTGS1 protein, human