Comparison Of The Effects And Mechanisms Of AZT,Paeoniflorin And Indirub In On Psoriasis Mouse Model

ObjectivePsoriasis is an immunomodulatory and inflammatory skin disease whose pathogenesis is still not well defined.Zidovudine(AZT),a traditional antiretroviral drug,found improved the symptoms of psoriasis in HIV-infected patients.The mechanism remains unknown.On one hand,it is well known that AZT can damage mitochondria.However,it has not been reported that whether this damage is related to the efficacy of AZT.In our previous studies,we found that AZT can inhibit the glycosylation of ADAM17 thus inhibit its activation.It has been confirmed that the ADAM17/EGFR axis plays an important role in the pathogenesis and progression of psoriasis;this inhibition may also due to the efficacy of AZT.On the other hand,mitochondria is considered to be closely related to the Chinese medicine“Yang”syndrome because of its role in energy metabolism.In the theory of traditional Chinese medicine,"treatment from blood stage”is the basic rule for the treatment of psoriasis.Inflammation often manifests as a hot phase.Therefore,heat-clearing and cool ing blood medicines such as Qingdai and Chishao are commonly used for the treatment of“Yang”syndrome.Therefore,we select AZT,as well as indirubin and paeoniflor-he active const ituents of Qingdai and Chishao,respectively,in the TPA-induced mouse psoriasis model to compare the efficacy and mechanism of those three in psoriasis.To provide an experimental basis for understanding the mechanisms of different types of drugs for the treatment of psoriasis and anti-inflammatory mechanisms.MethodsThis study is divided into two parts.In the first part,24 C57BL/6J mice were randomly divided into four groups.Except the control group,the other groups were given TPA to induce psoriasis.For therapeutic intervention,the two treatment groups were given concentrations of 5%and 0.5%AZT ointment,respectively.Skin samples were taken for histopathological examination and some other further detection.Immunohistochemistry were used to analyze the in situ expression of ADAM17 and EGFR,the mRNA and protein expression of mitochondrial oxidative damage and keratinocyte differentiation in the skin were detected.Subsequently,cultured THP-1 cells were stimulated by TPA and different concentrations of AZT to detect mRNA and protein expression of related genes.In the second part,36 BALB/c mice were randomly divided into 6 groups.Except the control group,mice in the other groups were given TPA to induce psoriasis.For therapeutic intervention,the four treatment groups were given two concentrations of paeoniflorin ointment and indirubin ointment,respectively.The histopathological examination of mouse skin was carried out,and the expression of IL-6,TNF-? in plasma were detected by ELISA,and the mRNA expression of related genes in skin were detected by PCR.Cultured THP-1 cells were first stimulated with LPS,then stimulated by different concentrations of paeoniflorin and indirubin,the mRNA expression of related genes were detected.ResultsIn the first part,the normal thickness of the epidermal tissue was observed in control group;the model group showed significant thickening of the stratum corneum,telangiectasia and hyperemia,and increased inflammatory cell infiltration.5%and 0.5%concentrations of AZT treatment significantly improved the thickening of the epidermis.Experiments in vitro and in vivo of PCR results showed that AZT can significantly increase the expression of ADAM17 and EGFR,slight ly up-regulate TGM1 expression(P<0.05),changes of differentiation makers such as TGM3,Keratinl,Loricrin,involucrin,HMOX1,Nrf2,Nqol were not statistically significant(P>0.05).Western blotting results of in vitro and in vivo showed that AZT can significantly increase the expression of ADAM17 and EGFR(P<0.05);also significantly increase the expression of TGM1 and TGM3(P<0.05),and the effect of 0.5%concentration group is better than that of 5%concentration group.Immunohistochemistry results showed that the expression of ADAM17 was decreased in model group,the treatment of AZT up-regulated its expression,especially the 0.5%AZT group was more significant in up-regulating ADAM17.Although the change of EGFR was not as obvious as ADAM17,the trend is consistent with it.In the second part,the normal thickness of the epidermal tissue was observed in the control group.In the model group,there were obvious thickening of corneum,hyperkeratosis and parakeratosis,inflammatory cell infiltration.Neutrophil aggregation and acanthosis were observed in the corneum.Compared with the model group,the skin thickness in high and low dose paeoniflorin and indirubin was significantly decreased,hyperkeratosis,parakeratosis and augmentation of the acanthosis were significantly improved(P<0.05).Among them,efficacy in high dose group of paeoniflorin and indirubin were better than the low dose group.In skin tissue,gene expression of Nrf2 and involucrin in model group was significantly increased(P<0.05),while the performance of the treatment group was significantly decreased(P<0.05).In plasma of mice,the expression of IL-6 in model group was significantly increased(P<0.05),while the expression of treatment group was significantly decreased(P<0.05).THP-1 cells were stimulated by LPS and different concentrations of paeoniflorin and indirubin,it was found that both of them significantly inhibited LPS-induced IL-23 expression.ConclusionAZT,paeoniflorin and indirubin can alleviate TPA-induced psoriasis skin lesions in mice;however,the mechanisms are quite different.AZT can up-regulate the activity of ADAM17/EGFR/TGM1,which may play a role in maintaining the integrity of the epidermal barrier;HMOX-1 and Nrf2 also show an upward trend,and the changes of HMOX-1 and ADAM17 are consistent,suggesting that the protective system of oxidative damage may participated in this mechanism.Both paeoniflorin and indirubin inhibited Nrf2,IL-6 and IL-23,suggesting that it may directly inhibit TPA-induced oxidative damage and protect it from upstream.