Diisononyl Phthalate Aggravates Allergic Dermatitis By Activation Of NF-?B And Enhancement Of TRPA1

There are many types of plasticizers,phthalates(PAEs)is one of the most common types.It is widely used in PVC,children's toys,food packaging bags,medical materials,and personal care products.It can be said that people can come into contact with these plastic products to varying degrees every day.Epidemiological investigations have found that some early plasticizer products are potentially harmful to human health,and there may be a close relationship between the incidence of atopic dermatitis and phthalate ester exposure.According to this,some new low-toxicity plasticizer products are favored by the market instead of the traditional plasticizer products.Di-iso-nonyl phthalate(DINP)is the representative of the new plasticizers,which is widely used in industrial production.DINP,which is less toxic than some early toxic plasticizers(such as DBP,DDP,DEHP),enters the body through long-term oral exposure and the immunotoxicity deserves our attention.For the current scholars' research,there is no clear answer to the mechanism of the effect of DINP exposure on allergic skin inflammation.In this study,we used 0.5%fluorescein isothiocyanate(FITC)as a sensitizer and selected male Balb/c mice to establish an allergic skin inflammation model.To investigate the effects of long-term oral exposure of DINP on atopic dermatitis,pyrrolidine dithiocarbamate(PDTC)was used as an antagonist of NF-?B and HC030031 as an antagonist of TRPA1 ion channel respectively,and to explore upper and lower relations of molecular events.In this study,the ear edema and ear weight in mice were measured.The levels of serum immunoglobulin E(IgE)and immunoglobulin G1(IgG1)in serum were measured.The levels of Thl cytokine interferon-?(IFN-?),Th2 cytokines interleukin-4(IL-4),interleukin-5(IL-5),interleukin-13(IL-13)and Th2 cofactor interleukin-6(IL-6)and the levels of oxidative damage in right ear tissue were measured,the expression of TRPA1,the degranulation of mast cells,the activation levels of thymus stromal lymphopoietin(TSLP),nuclear transcription factor ?B(NF-?B)and signal transducer and activator of transcriptions(STATs)were measured in the right ear tissue.The results showed that:(1)200 mg/kg/d DINP exposure alone did not cause allergic dermatitis in mice;(2)DINP increased the symptoms of allergic dermatitis with Th2 immune response;(3)Oxidative stress activated NF-?B and triggered downstream molecular events.The contents of reactive oxygen species(ROS)and malondialdehyde(MDA)in ears of mice increased significantly and the contents of reduced glutathione(GSH)decreased significantly.The level of oxidative stress decreased after using PDTC.The phosphorylation of NF-?B had significant changes(p<0.05).The levels of TSLP activation were significantly increased after PDTC treatment with NF-?B antagonist PDTC.The levels of phosphorylation of STAT5 and STAT6 were significantly increased.(4)The increased expression of TRPA1 ion channel aggravated the symptoms of atopic dermatitis,which was regulated by NF-?B.TRPA1 gene expression was significantly increased,which was decreased by the use of HC030031.But the use of HC030031 can not decrease the phosphorylation level of NF-?B and the activated level of TSLP.It is worth noting that the activation level of TRPA1 gene was significantly decreased after using NF-?B antagonist PDTC.This research shows that continuous exposure to high concentration of DINP can lead to deterioration of symptoms in mice with atopic dermatitis.This process is triggered by increased oxidative stress,activation of NF-?B signaling pathway and increased production of TSLP.The enhanced expression of the TRPA1 ion channel promotes the secretion of IL-6 and Th2 cytokines,resulting in an imbalance in Thl/Th2 immunity.When we add PDTC,a NF-?B antagonist,and TRPA1 ion channel antagonist HC030031,this mechanism of action can be clearly identified.