title: Detection of thyroid peroxidase mRNA and protein in orbital tissue.
abstract: OBJECTIVE
  We have previously reported that the absence of thyroid peroxidase antibodies (TPOAb) in Graves' disease (GD) was associated with an increased risk of Graves' ophthalmopathy (GO). This observation raised the possibility that TPOAb could act as a protective factor. However, the presence of thyroid peroxidase (TPO) in the orbit has not been previously reported. The aim of this study was to confirm or exclude the presence of orbital TPO.
  
  
  METHODS
  Relative TPO mRNA expression from GO (n=6) and normal (n=5) orbital fat tissue was determined using real-time PCR technique. Orbital fat in the normal group from blepharoplasty represents extraconal (anterior) fat. mRNA expression in fibroblasts grown from these tissues before and after adipocyte differentiation was also documented. Finally, Western blotting was carried out to verify translation of TPO mRNA transcripts.
  
  
  CONCLUSIONS
  TPO transcripts were detected in the orbital fat tissue obtained from normal and GO subjects using the real-time PCR technique. TPO expression was increased in GO compared to normal (N) tissues. However, TPO expression in cultured fibroblasts was similar in both groups and adipogenesis did not appear to alter TPO expression. Protein was detected by Western blot analysis using the TPO MAB 47 (mAb 47). The predicted 110-kDa band was detected in orbital fat as well as in orbital fibroblasts. Our results suggest the presence of TPO in GO and N orbital tissues. We hypothesise that immune responses directed against orbital TPO might play a role in modulating the clinical expression of GO.
authors.affiliation: Department of Clinical Research, Singapore General Hospital, Singapore.
authors.forename: Oi Fah
authors.initials: OF
authors.lastname: Lai
authors.forename: Norazean
authors.initials: N
authors.lastname: Zaiden
authors.forename: Sui Sin
authors.initials: SS
authors.lastname: Goh
authors.forename: Nur-Ezan
authors.initials: NE
authors.lastname: Mohamed
authors.forename: Lay Leng
authors.initials: LL
authors.lastname: Seah
authors.forename: Kee Siew
authors.initials: KS
authors.lastname: Fong
authors.forename: Valerie
authors.initials: V
authors.lastname: Estienne
authors.forename: Pierre
authors.initials: P
authors.lastname: Carayon
authors.forename: Su Chin
authors.initials: SC
authors.lastname: Ho
authors.forename: Daphne H C
authors.initials: DH
authors.lastname: Khoo
mesh_terms: D017667:Adipocytes / Q000166:cytology / Q000201:enzymology; D000273:Adipose Tissue / Q000166:cytology / Q000201:enzymology*; D015153:Blotting, Western; D002478:Cells, Cultured; D005347:Fibroblasts / Q000166:cytology / Q000201:enzymology; D015971:Gene Expression Regulation, Enzymologic; D049970:Graves Ophthalmopathy / Q000378:metabolism* / Q000503:physiopathology; D006801:Humans; D007453:Iodide Peroxidase / Q000235:genetics* / Q000378:metabolism*; D009915:Orbit; D012333:RNA, Messenger / Q000032:analysis; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: D012333:RNA, Messenger; D007453:Iodide Peroxidase