SJMHE1 protects against excessive iodine-induced pyroptosis in human thyroid follicular epithelial cells through a toll-like receptor 2-dependent pathway.

To elucidate the effect of Schistosoma japonicum peptide (SJMHE1) on pyroptosis in thyroid follicular epithelial cells (TFCs) induced by excessive iodine and the potential mechanism, the effects of SJMHE1 were investigated in NaI-treated Nthy-ori 3-1 cells; and the involvement of the ROS/MAPK/NF-κB signaling pathways in these effects was evaluated by employing CCK-8 assays, flow cytometry, ELISA, and Western blotting experiments. We found that SJMHE1 significantly reduced NLRP3, N-terminus of gasdermin D (GSDMD-N) and cleaved caspase-1 (C-caspase-1) expression, and decreased IL-1β secretion in TFCs. SJMHE1 also markedly reduced reactive oxygen species (ROS) production, and decreased the phosphorylation levels of MAPK and NF-κB pathway members. Moreover, blocking of the Toll-like receptor 2 significantly impaired SJMHE1-mediated protection from excessive iodine-induced pyroptosis in TFCs. Therefore, our results suggested a protective role of SJMHE1 in excessive iodine-induced pyroptosis in TFCs, which might be attributed to its suppression for ROS/MAPK/NF-κB signaling pathway by binding of SJMHE1 with TLR2.