Immune Landscape of the Orbital Microenviroment in Thyroid-Associated Ophthalmopathy

Abstract

Purpose : This study focuses on inflammation in the local orbital microenvironment to gain insights into the immune landscape of orbital connective tissues in thyroid-associated ophthalmopathy (TAO).

Methods : Orbital tissues from TAO patients and control subjects were collected. Single-cell sequencing was performed to examine orbital lymphocytic infiltrates. Multi-color flow cytometry was used to explore phenotypes of different cell subsets and in vitro models for cell functional studies. Co-culture experiment and western blotting assay were conducted to unravel the underlying mechanism of the enhanced T cell immunity.

Results : TAO orbital microenvironment was composed of natural killer cells, dendritic cells, macrophages, T cells, and CD34⁺ orbital fibroblasts (OFs). Moreover, We found a T cell-dominated inflammatory micro-circumstance where Th17 and Th2 cells contributed to the immune reaction, and observed a Th1-like Th17 phenotype in TAO. Both interleukin (IL)-23R and IL-1R were up-regulated in Th17 cells from TAO orbits. Additionally, IL-17A, RORγt, IL-23R, and IL-1R correlated with TAO activity and visual acuity. Molecules involved in both Th17 and Th2 pathways were associated with TAO development, while TAO OFs expressed CD34, which enhanced IL-23R and IL-1R expression on T cells to promote the Th17 phenotype via the prostaglandin E₂-EP2/EP4-cAMP pathway.

Conclusions : Understanding the immune microenvironment in the orbital compartment will help in the development of more effective therapeutic strategies against causal factors in TAO.

This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.

 

Immune landscape of TAO orbital connective tissues by single-cell sequencing. A Visualization of four major classes of cells in TAO orbital connective tissues. Each dot is a single cell. B Detailed grouping of gene expression of cells in TAO orbital connective tissues. C and D Detailed grouping of gene expression of T cells in TAO orbital connective tissues.