Expression of GRα mRNA and NF-kB in orbital fat and extraocular muscle in Thyroid Eye Disease

Abstract

Purpose: In this study we compared GRα mRNA and NF-kB in Thyroid Eye Disease’s (TED) orbital fat (OF) and extraocular muscle (EOM) with normal OF and EOM.

Methods: A prospective study was performed at the Ophthalmology Unit of Santa Casa of Sao Paulo, Brazil. We evaluated 34 TED patients and 42 healthy controls. OF was harvested from 34 TED and 25 controls. EOM biopsy was obtained from 33 TED and 20 controls. Samples were examined by real time PCR. Methods of statistical analysis were choosen depending on the type of the data, with the level of statistical significance as p value <0.05.

Results: A higher level of GRα mRNA was observed in TED muscle with median (p25-p75)=213.39 (96.91-376.78) compared to controls muscle with median (p25-p75)=60.99 (32.28-131.00), (p<0.001). The same behavior was seen when NF-kB was analysed in TED muscle with median (p25-p75)=223.49 (30.57-520.23) compared to controls muscle with median (p25-p75)=8.39 (6.40-30.04), (p<0.001). However, in OF samples, GRα mRNA and NF-kB were similar among groups. GRα/NF-kB ratio in TED EOM was 0.73 (0.34-5.18) and in controls EOM was 5.19 (3.73-8.05), (p=0.005).

Conclusions: GRα mRNA and NF-kB levels differed among tissues involved in the pathophysiology of Graves Orbitopathy. In TED OF samples there was no difference in gene expression compared to controls. In the other hand, in TED muscles samples, the levels of GRα mRNA and NF-kB were higher than controls.

Keywords: 631 orbit • 533 gene/expression • 739 transcription factors