Plasma exosomes from patients with active thyroid-associated orbitopathy induce inflammation and fibrosis in orbital fibroblasts

The pathogenesis of thyroid-associated orbitopathy (TAO) remains incompletely understand. The interaction between immunocytes and orbital fibroblasts (OFs) play a critical role in orbital inflammatory and fibrosis. Accumulating reports indicate that a significant portion of plasma exosomes (Pla-Exos) are derived from immune cells; however, their impact upon OFs function is unclear.

OFs were primary cultured from inactive TAO patients. Exosomes isolated from plasma samples of patients with active TAO and healthy controls (HCs) were utilized for functional and RNA cargo analysis. Functional analysis in thymocyte differentiation antigen-1⁺ (Thy-1⁺) OFs measured expression of inflammatory and fibrotic markers (mRNAs and proteins) and cell activity in response to Pla-Exos. RNA cargo analysis was performed by RNA sequencing and RT-qPCR. Thy-1⁺ OFs were transfected with miR-144-3p mimics/inhibitors to evaluate its regulation of inflammation, fibrosis, and proliferation.

Pla-Exos derived from active TAO patients (Pla-Exos^TAO−A) induced stronger production of inflammatory cytokines and hyaluronic acid (HA) in Thy-1⁺ OFs while inhibiting their proliferation. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis and single sample gene set enrichment analysis (ssGSEA) suggested that the difference in mRNA expression levels between Pla-Exos^TAO−A and Pla-Exos^HC was closely related to immune cells. Differential expression analysis revealed that 62 upregulated and 45 downregulated miRNAs in Pla-Exos^TAO−A, with the elevation of miR-144-3p in both Pla-Exos and PBMCs in active TAO group. KEGG analysis revealed that the target genes of differentially expressed miRNA and miR-144-3p enriched in immune-related signaling pathways. Overexpression of the miR-144-3p mimic significantly upregulated the secretion of inflammatory cytokines and HA in Thy-1⁺ OFs while inhibiting their proliferation.

Pla-Exos derived from patients with active TAO were immune-active, which may be a long-term stimulus casual for inflammatory and fibrotic progression of TAO. Our finding suggests that Pla-Exos could be used as biomarkers or treatment targets in TAO patients.