Imbalance of Th17 and Tregs in thymoma may be a pathological mechanism
of myasthenia gravis
Abstract
An imbalance in Th17 cells and Tregs may be an important cause of the
pathogenesis of thymoma with myasthenia gravis (MG). In this study, 30
patients with simple thymoma and 30 patients with thymoma with MG were
analyzed. Flow cytometry analysis of Th17 and Tregs in peripheral blood
revealed that the percentages of Th17 in thymoma were lower than those
in thymoma with MG, while the percentages of Tregs were higher than
those in simple thymoma. Serum cytokine ELISA assays showed that IL-6
levels in simple thymoma were lower than those in MG patients. Further,
Th17 and Tregs levels were detected by immunohistochemical double
staining of thymoma tissue; the number of positive Th17 cells in thymoma
with MG was higher than that in simple thymoma, while positive Tregs
showed the opposite results. RORγt protein and mRNA expression in
thymoma with MG were both higher than those in simple thymoma. FOXP3
protein and mRNA expression in the thymoma with MG group were lower than
those in simple thymoma. The results of coculture of thymoma cells and
CD4+ T cells showed that thymoma cells could promote the differentiation
of Th17 cells and inhibit the Tregs. Overall, Th17 cells and related
transcription factors and cytokines in thymoma with MG patients were
higher than those in thymoma patients, whereas, Tregs showed the
opposite results, the mechanism may be that thymoma can secrete IL6 and
IL21. These findings indicated that imbalances in Th17/Tregs and
RORγt/FOXP3 may account for the pathogeny of thymoma with MG.