Detection of thyroid peroxidase mRNA and protein in orbital tissue.
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.
Lai
Oi Fah
OF
Department of Clinical Research, Singapore General Hospital, Singapore.
Zaiden
Norazean
N
Goh
Sui Sin
SS
Mohamed
Nur-Ezan
NE
Seah
Lay Leng
LL
Fong
Kee Siew
KS
Estienne
Valerie
V
Carayon
Pierre
P
Ho
Su Chin
SC
Khoo
Daphne H C
DH
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
D012333:RNA, Messenger; D007453:Iodide Peroxidase