NR4A3 affects fibrotic activation of orbital fibroblasts and thyroid-associated ophthalmopathy through regulating NF-κB signaling

Orbital fibroblast proliferation and activation contribute to the development of thyroid-associated ophthalmopathy (TAO). In this study, nuclear receptor subfamily 4 group A member 3 (NR4A3) was predicted to play a role in TAO based on bioinformatics analysis. Validation of NR4A3 expression in human TAO orbital samples confirmed its elevated levels compared to normal controls. In vitro studies demonstrated that transforming growth factor beta 1 (TGF-β1)-induced NR4A3 expression in human TAO orbital fibroblasts (OFs) enhanced cell viability, DNA synthesis, and fibrotic marker expression. Conversely, NR4A3 knockdown inhibited these fibrotic responses, suggesting a pro-fibrotic role for NR4A3 in TAO. In vivo experiments further validated these findings, with NR4A3 knockdown in a TAO mouse model leading to reduced pathological injury and fibrosis in orbital tissues. Additionally, NR4A3 knockdown decreased the expression of fibrotic markers in the orbital tissues of TAO mice, corroborating the in vitro results. Finally, NR4A3 was shown to modulate the nuclear factor kappa B (NF-κB) pathway, which is activated in TAO. NR4A3 overexpression enhanced, while its knockdown suppressed, NF-κB activation in both human TAO OFs and orbital tissues from TAO mice. These findings suggest that NR4A3 promotes TAO progression through its pro-fibrotic effects and activation of NF-κB signaling, highlighting its potential as a therapeutic target for TAO. Collectively, NR4A3 plays a pivotal regulatory role in both fibroblast proliferation and the fibrotic response in TAO, acting through mechanisms involving the NF-κB signaling pathway. Its ability to enhance TGF-β1-induced changes and activate NF-κB underscores its potential as a key therapeutic target for addressing the complex pathophysiology of TAO.