Differential Gene Expression Profiling of Orbital Adipose Tissue in Thyroid Orbitopathy

Abstract

PURPOSE. We aimed to determine differentially expressed genes relevant to orbital inflammation and orbital fat expansion in thyroid orbitopathy (TO) using microarray gene profiling in a case-control study.METHODS. Human orbital adipose samples were obtained from individuals with active TO (n ¼ 12), inactive TO (n ¼ 21), and normal controls (n ¼ 21). Gene expression profiles were examined using microarray analysis and were compared between active and inactive TO, and between active TO and normal controls. Top ranked differentially expressed genes were validated by real-time RT-PCR in an additional eight active TO, 13 inactive TO, and 11 normal controls and correlated with gene set enrichment analysis (GSEA) and molecular pathways analysis.RESULTS. Seven hundred twenty-one probes (683 genes) and 806 probes (735 genes) were significantly differentially expressed in comparing active to inactive TO and in comparing active TO to healthy controls, respectively. All selected genes were confirmed to be differentially expressed by real-time RT-PCR. Multiple top ranked genes in active versus inactive TO comparison are overrepresented by immune and inflammatory response genes. They include defensins (DEFA1, DEFA1B, DEFA3), which were overexpressed by 3.05-to 4.14-fold and TIMD4 by 4.20-fold. Markers for adipogenesis were overexpressed including SCD, FADS1, and SCDP1. Gene set enrichment analysis revealed dysregulation of epigenetic signatures, T-cell activation, Th1 differentiation, defensin pathway, cell adhesion, cytoskeleton organization, apoptosis, cell cycling, and lipid metabolism in active TO.CONCLUSIONS. Active TO is characterized by upregulation of genes involved in cell-mediated immune, innate immune, and inflammatory response and enhanced orbital adipogenesis. TIMD4, DEFA1, DEFA1B, and DEFA3 genes may be involved in the innate immune-mediated orbital inflammation in TO. Epigenetic mechanisms may play a role in the pathogenesis of TO.

Pathophysiology of Graves’ Ophthalmopathy: A Literature Review

“…Regarding IL-23, two polymorphisms were detected (rs10889677 and rs2201841), which occur at a rate 1.8 higher than in those unaffected by GO [3]. It also seems to be a gene upregulation relationship involved in the innate, cell-mediated, and inflammatory immune responses in the GO orbital adipogenesis (TIMD4, DEFA1B, DEFA1,and DEFA3) [7].…”

The 2017 Doyne Lecture: the orbit as a window to systemic disease

“…The study of the genetics of Graves' orbitopathy offers an opportunity to identify patients at risk 59 and to better understand the pathophysiology of the disease. 60 This is but one example of the future direction of research in orbital disease.…”

RNA-Sequencing Gene Expression Profiling of Orbital Adipose-Derived Stem Cell Population Implicate HOX Genes and WNT Signaling Dysregulation in the Pathogenesis of Thyroid-Associated Orbitopathy

“… 15 , 16 Although the inflammatory response is well outlined, the pathophysiology of TAO has not been completely elucidated and the variability in disease course and presentation still remains elusive. 17 , 18 …”

“…To better understand which factors may be implicated in disease onset and severity, several gene expression profiling studies using microarray have been performed for TAO. 17 , 37 , 38 Many signaling pathways, such as IGF-1 and WNT signaling, have been associated with the development of TAO. 37 Interestingly, previous studies have only focused on the whole orbital adipose tissue rather than isolating the stem cell population in these tissues.…”