DINP Aggravate Autoimmune Thyroid Disease Through Promoting Oxidative Stress To Activate Akt/mTOR Pathway In Wistar Rats

As the most commonly used plasticizer,phthalic acid esters(PAEs)are wildly used in many products like food packaging,building materials,children's toys,personal care products,and medical equipment.Epidemiological investigations and toxicological studies have found that some traditional phthalates can induce reproductive and developmental toxicity.So the production and using of environmental friendly phthalates,such as Di-isononyl phthalate(DINP),are increasing.Autoimmune thyroid disease(AITD)is the most common autoimmune disease and environmental factors are the main cause that induces the incident rate of AITD increased.In recent years,studies have shown that phthalates can affect normal function of the thyroid.However,the effect of DINP on AITD and the potential mechanisms are still not clear.In this study,female Wistar rats were used to build an autoimmune thyroid disease model by using heterologous thyroglobulin.During modeling,rats in the DINP exposure groups received the different dose of DINP via oral exposure.Further,Vitamin E(VE)or rapamycin(RAPA)were used as the inhibitor of oxidative stress or the mammalian target of rapamycin(mTOR)respectively to explore the potential mechanisms.In our experiment,we detected the pathological damage in the thyroid gland,the content of thyroglobulin autoantibody(TG-Ab),the express status of Thl cytokine interferon-y(IFN-y)and Th2 cytokine interleukin-4(IL-4),the express status of apoptosis related protein caspase-3 in the thyroid,the content of autophagy-related protein LC3B and SQSTM1 in the thyroid tissue,the exist status of autophagosome or autolysosome,the levels of oxidative stress and inflammation factor interleukin-1?(IL-1?),the activation status of protein kinase(Akt)and mTOR,the phosphorylation level of signal transducers and activators of transcription 3(STAT3)and the level of interleukin-17(IL-17).The results showed that(1)oral exposure to a certain concentration DINP can aggravate autoimmune thyroid disease and exacerbate apoptosis in the thyroid,(2)DINP can aggravated the suppression of normal autophagy in the thyroid of AITD model rats,(3)after being exposed to DINP,the content of reactive oxygen species(ROS)in the thyroid increased and the level of glutathione(GSH)decreased,the level of inflammation factor IL-1? increased,the phosphorylation level of Akt and mTOR increased,the phosphorylation level of STAT3 increased and the level of IL-17 increased,(4)oxidative stress and the phosphorylation levels of Akt and mTOR were decreased significantly after being treated with VE,in the RAPA treated groups the phosphorylation levels of mTOR and STAT3 decreased and IL-17 level also decreased.In conclusion,oral exposure to a certain dose of DINP(1.5mg/kg or 15mg/kg)can lead to an exacerbation of AITD and the potential mechanism is DINP induces an increase of oxidative stress then activates the Akt/mTOR signaling pathway that results in the suppression of normal autophagy in the thyroid.Meanwhile,the activation of Akt/mTOR pathway activates STAT3 lead to the increase of IL-17 and aggravated AITD eventually.