Gene expression profiling of orbital adipose tissue from patients with Graves' ophthalmopathy: a potential role for secreted frizzled-related protein-1 in orbital adipogenesis.
BACKGROUND
The signs and symptoms of Graves' ophthalmopathy (GO) result from inflammation and increased volume of the orbital adipose tissues and extraocular muscles.


OBJECTIVE
Our objective was to identify differentially regulated genes that may be involved in stimulating the orbital adipose tissue expansion seen in GO.


METHODS
Gene expression profiling was used to compare genes expressed in orbital adipose tissues from GO patients and normal individuals.


METHODS
The study took place at a private practice tertiary referral center.


METHODS
Orbital adipose tissues were collected at transantral orbital decompression surgery from 20 euthyroid patients undergoing this procedure for severe GO and at early autopsy from eight normal individuals having no evidence of thyroid or ocular disease.


RESULTS
Of the 12,686 genes analyzed, 25 known genes were increased in expression (>4-fold) in GO orbital tissues, whereas 11 genes were decreased (>4-fold). Up-regulated genes, confirmed by quantitative RT-PCR, included secreted frizzled-related protein-1 (sFRP-1; 18.5-fold) and several adipocyte-related genes, including peroxisome proliferator activated receptor-gamma (44.1-fold) and adiponectin (25-fold). Treatment in vitro of GO orbital preadipocytes with recombinant sFRP-1 (100 nm) significantly increased adiponectin (2.0-fold; P < 0.05), leptin (7-fold; P < 0.002), and TSH receptor mRNA (13-fold; P < 0.003) levels and enhanced Oil red-O staining in the cultures.


CONCLUSIONS
These results support the concept that orbital adipogenesis is enhanced in GO and suggest that elevated levels of sFRP-1 in the GO orbit may be involved in stimulating this pathogenic process.
Kumar
Seema
S
Division of Pediatric Endocrinology, Mayo Clinic, 200 First Street SW, Rochester, Minnesota 55905, USA.
Leontovich
Alexey
A
Coenen
Michael J
MJ
Bahn
Rebecca S
RS
D017667:Adipocytes / Q000166:cytology / Q000502:physiology; D000273:Adipose Tissue / Q000166:cytology / Q000502:physiology*; D002478:Cells, Cultured; D020869:Gene Expression Profiling; D006111:Graves Disease / Q000235:genetics* / Q000503:physiopathology*; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D009915:Orbit; D011506:Proteins / Q000235:genetics*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015854:Up-Regulation; D000099274:Frizzled-Related Proteins
D047908:Intracellular Signaling Peptides and Proteins; D011506:Proteins; D000099274:Frizzled-Related Proteins