Effect of Chuanshanlong Granule on TLR4/MyD88/NF-κB Signaling Pathway in Rats with Autoimmune Thyroiditis / 中国实验方剂学杂志

ABSTRACT

ObjectiveTo investigate the effect of Chuanshanlong granule on Toll-like receptor 4 （TLR4）/myeloid differentiation protein 88 （MyD88）/nuclear transcription factor -κB （NF-κB） signaling pathway， and to explore the mechanism of its treatment of autoimmune thyroiditis （AIT） in rats. MethodForty AIT models were established following excess iodine and injection of porcine thyroglobulin and Freund's adjuvant into Lewis rats for six weeks. Then the rats were randomly divided into the model group， Chuanshanlong granule low-， medium- and high-dose group （0.52， 1.03， 2.06 g·kg-1·d-1）， with ten in each group. Rats in the Chuanshanlong granule low-， medium- and high-dose groups were separately given 0.01 mL·g-1·d-1 Chuanshanlong granule， and those in the normal group and the model group were given the same volume of deionized water for eight weeks. Serum of rats was taken to measure thyroglobulin antibody （TgAb） and thyroid peroxidase antibody （TPOAb） by enzyme-linked immunosorbent assay （ELISA）， and the concentrations of free triiodothyronine （FT3）， free thyroxine （FT4） and thyroid stimulating hormone （TSH） were detected. The rat thyroid lobes were stained with hematoxylin and eosin （HE）， and the pathological changes were observed under light microscope. In addition， the relative expression of TLR4， MyD88， NF-κB protein and mRNA was determined by immunohistochemistry and real-time polymerase chain reaction （Real-time PCR）. ResultCompared with the conditions in the normal group， the serum concentrations of TPOAb and TgAb （P<0.01） and FT3 and FT4 （P<0.01） increased and TSH decreased （P<0.01） in the model group. Compared with the conditions in the model group， the concentrations of TPOAb and TgAb in the Chuanshanlong granule treatment groups reduced （P<0.01）， and the concentrations of FT3 and FT4 were lowered （P<0.01） while TSH increased （P<0.01） in the Chuanshanlong granule high-dose group. HE staining showed that there was lymphocyte infiltration in the thyroid follicular space， a large number of destroyed or diminished follicular cavities， decreased colloid content， and thinned or destroyed follicular wall in the model group， while the thyroid lymphocyte infiltration in the Chuanshanlong granule treatment groups was significantly less and the structure of thyroid follicles was more complete than those in the model group. Compared with the normal group， the model group had up-regulated relative expression of TLR4， MyD88 and NF-κB protein （P<0.01） and mRNA （P<0.01）. Compared with the model group， the Chuanshanlong granule high-dose group had down-regulated relative expression of TLR4 protein and mRNA （P<0.05）， MyD88 protein （P<0.01） and mRNA （P<0.05）， and NF-κB protein and mRNA （P<0.01）. ConclusionChuanshanlong granule may play a therapeutic role in AIT by inhibiting the activation of TLR4/MyD88/NF-κB signaling pathway.