Tim3/galectin-9 alleviates the inflammation of TAO patients via suppressing Akt/NF-kB signaling pathway

Thyroid-associated ophthalmopathy (TAO) is an autoimmune disease. Studies showed that T helper 1 (Th1), Th2, and Th17 cells play important roles in the pathology of TAO. Tim-3 and its only known ligand Galectin-9 (Gal-9) is related to the suppression of Th1 and Th17 cytokine secretion. This study aims to investigate the role of Tim3/Gal-9 in the inflammatory response of TAO. In this study, the levels of Tim3, Gal-9, and cytokines of Th1 (TNF-α and IFN-γ), Th2 (IL-4), and Th17 (IL-17) cells were analyzed in the blood samples of TAO patients and healthy controls as well as in orbital fibroblasts. Tim3 overexpression and Gal-9 neutralizing antibody were used in TAO and LPS-stimulated control orbital fibroblasts to further investigate the role and mechanism of Tim3/Gal-9 on the inflammation of TAO. We found Tim3 and Gal-9 expression was significantly downregulated in TAO patients and further lower in active TAO than inactive TAO or controls. Th1, Th2, and Th17 cytokines were all increased in TAO patients. Th1 and Th17 cytokines were higher in active TAO patients than in inactive TAO patients, while Th2 cytokines were enhanced in inactive TAO. Tim3 overexpression decreased the levels of Th1 and Th17 cytokines, but not Th2 cytokine in TAO or LPS-stimulated control orbital fibroblasts. These effects were abrogated by Gal-9 neutralizing antibody. Moreover, Tim3 reduced the levels of p-Akt and p-p65 in TAO or LPS-induced control orbital fibroblasts that were reversed by Gal-9 blocking. In conclusion, Tim3/Gal-9 alleviates the inflammation of TAO patients via suppressing Akt/NF-κB signaling pathway.