CD34⁻ Orbital Fibroblasts From Patients With Thyroid-Associated Ophthalmopathy Modulate TNF-α Expression in CD34⁺ Fibroblasts and Fibrocytes

Abstract

PurposeOrbital fibroblasts from patients with Graves' disease (GD-OF) express many different cytokines when treated with bovine thyrotropin (bTSH). The present study aimed to determine why TNF-α cannot be induced by bTSH in GD-OF.MethodsFibrocytes and GD-OFs were cultivated from donors who were patients in a busy academic medical center practice. Real-time PCR, Western blot analysis, reporter gene assays, cell transfections, mRNA stability assays, ELISA, and flow cytometry were performed.ResultsWe found that bTSH induces TNF-α dramatically in fibrocytes but is undetectable in GD-OF. The induction in fibrocytes is a consequence of increased TNF-α gene promoter activity and is independent of ongoing protein synthesis. It could be attenuated by dexamethasone and the IGF-1 receptor inhibiting antibody, teprotumumab. When separated into pure CD34+ OF and CD34− OF subsets, TNF-α mRNA became highly inducible by bTSH in CD34+ OF but remained undetectable in CD34− OF. Conditioned medium from CD34− OF inhibited induction of TNF-α in fibrocytes.ConclusionsOur data indicate that CD34− OF appear to release a soluble(s) factor that downregulates expression and induction by bTSH of TNF-α in fibrocytes and their derivative CD34+ OF. We proffer that CD34− OF produce an unidentified modulatory factor that attenuates TNF-α expression in GD-OF and may do so in the TAO orbit.

New insights into the pathogenesis and nonsurgical management of Graves orbitopathy

“…Apart from orbital fibroblasts, fibrocytes, which are CD34 + bone marrow-derived progenitor cells, migrate from the circulation into sites of inflammation and injury ( Figure 2). They have been identified in the orbit, particularly those of patients with Graves' orbitopathy, 92,93 and reported to express two of the major thyroid autoantigens, the TSHR and thyroglobulin 94 Graves' orbitopathy and non-Graves' orbitopathy orbital fibroblasts 97 . Mast cells also produce prostaglandins which are able to enhance adipogenesis 98 .…”

Teprotumumab as a Novel Therapy for Thyroid-Associated Ophthalmopathy

“…This receptor was subsequently found to be functional and could mediate effects of both TSH and thyroid-stimulating autoantibodies (7,14). Activation of several genes, including those encoding cytokines implicated in the pathogenesis of TAO, has been reported (19,(33)(34)(35). Fibrocytes are trafficked to sites of tissue injury through several chemokine networks, most notably the CXCL-12/CXCR4 pathway (36) which is under the control of TSHR signaling.…”

Progress in the pathogenesis of thyroid-associated ophthalmopathy and new drug development

“…Some studies have pointed out that this regulatory effect may be controlled by Slit2 and AIRE. [ 72 73 74 75 ] Our study found that fibrocytes can recruit Th17 cells through the MIP-3/CCR-6 pathway. [ 76 ] In addition, TSH and CD40L can induce the secretion of IL-12 of fibrocytes,[ 77 ] which might be involved in the induction of Th1 cell immunity or transformation of Th17 cell to Th1 phenotype.…”