Abstract
Purpose :
Orbital fibroblasts are targets of the immune response in thyroid eye disease (TED). In vitro work has shown that in response to immune activation, orbital fibroblasts produce cytokines and undergo adipogenesis. In this study, we use single nuclear RNA sequencing (snRNA-Seq) to characterize and compare gene expression and cell types present in orbital fat isolated from control patients and those with TED.
Methods :
We performed nRNA-Seq on retrobulbar fat from three control patients undergoing resection of prolapsed orbital fat and three patients with TED undergoing orbital decompression. TED patients had clinical activity scores ranging from 0-3.
Results :
We identified multiple cell types in control patients and those with TED using snRNA-Seq, including fibroblasts and adipocytes (Figure 1a). TED patients have a higher proportion of adipocytes than controls (Figure1b), and TED-specific adipocytes expressed higher levels of adipocyte-enriched/specific genes, FKBP5 and PLIN5 (Figure 1c). TED patients show a reduced proportion of fibroblasts (Figure 1a) and reduced expression in fibroblast-enriched genes (Figure 2a). In addition, we identified fibroblast subtypes that express markers that we have described previously during adipogenic differentiation in vitro, such as PPARG and PDE3B (Figure 2b). In addition, gene expression changes in orbital fibroblasts undergoing adipogenesis match closely to our previous observations in vitro.
Conclusions :
We demonstrate evidence of hyperplasia within orbital adipocytes and fibroblasts in TED patients. We identify in vivo changes in gene expression in TED orbital fibroblasts that are consistent with our current in vitro model of orbital adipogenesis.
This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.