Abstract
Objectives & Methods: CXC Th1-chemokines and CCL Th2-chemokines play an important role in the initial phases of autoimmune disorders. Serum CXC Th1-chemokine CXCL10 is high in patients with active Graves ophthalmopathy (GO). Human thyrocytes, orbital fibroblasts, and preadipocytes in primary culture from GO patients produce large amounts of CXCL10 when stimulated by IFN-gamma and TNF-alpha; furthermore, PPAR-gamma agonists (TZD) rosiglitazone and pioglitazone dose-dependently suppressed IFN-gamma+TNF-alpha-induced CXCL10 release. The effects of IFN-gamma and TNF-alpha stimulation and of increasing concentrations of TZD (pioglitazone or rosiglitazone; 0.1 mcM-10 mcM) on Th1-chemokines CXCL9 and CXCL11 and Th2-chemokine CCL2 secretion in primary cultures of thyrocytes, fibroblasts from perimisium, and preadipocytes from GO patients were tested.
Results: In primary thyrocytes, fibroblasts and preadipocytes cultures, from patients with GO, CXCL9, CXCL11 and CCL2 were undetectable in the supernatant. IFN-gamma dose-dependently induced CXCL9, CXCL11 and CCL2 release, whereas TNF-alpha alone had no effect on CXCL9 and CXCL11 but stimulated CCL2 release. However, the combination of TNF-alpha and IFN-gamma had a significant synergistic effect on CXCL9, CXCL11 and CCL2 secretion. Treatment of thyrocytes, fibroblasts or preadipocytes cultures with rosiglitazone or pioglitazone, added at the time of IFN-gamma and TNF-alpha stimulation, dose-dependently inhibited CXCL9 and CXCL11 release, but not CCL2. TZD alone had no effect and did not affect cell viability or total protein content in thyrocytes, retrobulbar fibroblasts and preadipocytes. TZD did not cause significant adipogenic changes (as judged by Oil Red O staining) in either cell type after a 24-h period of incubation.
Conclusions: This study demonstrates that in GO: 1) thyrocytes and retrobulbar cell types participate in the self-perpetuation of inflammation by releasing CXCL9, CXCL11 and CCL2 chemokines under the influence of cytokines; 2) PPAR-gamma activation plays an inhibitory role in this process on CXCL9 and CXCL11