title: Synovial deposition of wild-type transthyretin-derived amyloid in knee joint osteoarthritis patients.
abstract: OBJECTIVE
  To investigate histological features of deposited amyloid in the synovial tissue and its clinical significance in knee joint osteoarthritis (OA) patients.
  
  
  METHODS
  We prospectively enrolled 232 consecutive patients who underwent arthroplasty or total replacement of the knee joint for treatment of OA. Congo red staining and immunohistochemistry were performed in the synovial tissue obtained at surgery. When transthyretin (TTR)-derived amyloid was positive, we analyzed all 4 exons of the TTR gene using the direct DNA sequencing method in order to detect mutations.
  
  
  RESULTS
  We analyzed 322 specimens in this study. Twenty-six specimens (8.1%) obtained from 21 patients (5 men and 16 women; mean, 79.0 ± 4.6 years) showed deposition of amyloid, which was positively stained with the anti-TTR antibody. Eighteen patients showed inhomogeneous accumulations of amyloid in the loose connective tissue under the synovial epithelia sometimes with nodule formation, while in the remaining three, small vessels in the adipose tissue were involved. Medical records of these patients revealed nothing remarkable in the clinical course, laboratory data or macroscopic intraarticular findings at surgery. No mutations were detectable in the TTR gene analysis.
  
  
  CONCLUSIONS
  Wild-type TTR-derived amyloid may affect the synovial tissue as a result of long-term mechanical stress or as a part of senile systemic amyloidosis in approximately 8% of knee joint OA patients. No obvious clinical significance was found in synovial deposition of amyloid.
authors.affiliation: Department of Rheumatology, Marunouchi Hospital, Matsumoto, Japan.
authors.forename: Tetsuo
authors.initials: T
authors.lastname: Takanashi
authors.forename: Masayuki
authors.initials: M
authors.lastname: Matsuda
authors.forename: Masahide
authors.initials: M
authors.lastname: Yazaki
authors.forename: Hideshi
authors.initials: H
authors.lastname: Yamazaki
authors.forename: Masashi
authors.initials: M
authors.lastname: Nawata
authors.forename: Yoshiki
authors.initials: Y
authors.lastname: Katagiri
authors.forename: Shu-Ichi
authors.initials: S
authors.lastname: Ikeda
mesh_terms: D000273:Adipose Tissue / Q000098:blood supply / Q000737:chemistry / Q000378:metabolism; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D000682:Amyloid / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D000686:Amyloidosis / Q000235:genetics / Q000473:pathology* / Q000601:surgery; D019645:Arthroplasty, Replacement, Knee; D005091:Exons; D005260:Female; D015870:Gene Expression; D006801:Humans; D017746:Joint Capsule / Q000737:chemistry* / Q000378:metabolism / Q000601:surgery; D007719:Knee Joint / Q000737:chemistry* / Q000378:metabolism / Q000601:surgery; D008297:Male; D009154:Mutation; D009389:Neovascularization, Pathologic; D010003:Osteoarthritis / Q000235:genetics / Q000473:pathology* / Q000601:surgery; D010641:Phenotype; D058225:Plaque, Amyloid / Q000737:chemistry* / Q000235:genetics / Q000601:surgery; D011228:Prealbumin / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D011446:Prospective Studies
chemical_list: D000682:Amyloid; D011228:Prealbumin; C076571:transthyretin-related amyloid fibril protein, human