The Therapeutic Effect Of TGI1002on Models Of Mice Delayed Type Hypersensitiity And Its Mechanisms

In the present study, we found that small molecular compound which named TGI1002have an obvious therapeutic effect on delayed allergic reaction animal models, contact dermatitis mice model. The possible mechanisms of immunosuppressive effect of TGI1002were discussed, and this compound might become a new powerful immunosuppressive drug.In Chapter1, the pharmacological effect of TGI1002was overall evaluation through picryl chloride-induced contact dermatitis mice model. TGI1002administered to animals by gastric perfusion through induced phase and effector phase. Results showed that ear tumefaction of mice were inhibited dose dependently, and pathologic changes were also significantly improved.IFN-y, IL-2and TNF-a are the main inflammatory cytokines in contact dermatitis mice model, and IL-17A which is the characteristic cytokine of Thl7cell have also been found to participate in this inflammatory reaction. We detected the expression level of these inflammatory cytokines in mice lymph node. Results showed that TGI1002could down-regulate the expression level of IFN-y, IL-2and TNF-a while IL-17A wasn’t been affected, which suggested that TGI1002have little effect on Thl7cell. We then detected the effect of TGI1002on ofp-xylene induced mice ear tumefaction model, but observe no significant inhibit effect. These results suggested that the therapeutic effect of TGI1002on mice ear tumefaction model did not related to inhibit cytokines, such as histamine, kinin and fibrinolysis release.In Chapter2, we further investigate the possible immunosuppressive mechanism of TGI1002. It has been report that contact dermatitis is T-cell dependent reaction. Through Chapter1we have known that therapeutic effect of TGI1002did not related to inhibit cytokines. In this part, we proved T cell is the main target of TGI1002through passive transfer experiment. We also found that TGI1002inhibited proliferation of T cell activated sensitized lymph node cells, which suggested that TGI1002exhibited its effect through inhibit cell activation and proliferation.TGI1002also significantly inhibited the activation and proliferation of Con A or antiCD3/CD28induced T cell. TGI1002could effectively reduce expression of CD25and CD69, the surface activation markers of T cells, and inhibit the activation of T cells. TGI1002could stop the cell cycle of T cells at G0/G1period, and promote its apoptosis. This might be the main mechanism of TGI1002to exhibiting its immunosuppressive effect.The cytokines’level was an important indicator to judge activation of T cells. Results of experiments in vitro were consistent with in vivo:secrete of T cell cytokines which include IL-2, IFN-y and TNF-a were inhibited, which IL-17A was little affected.Further study of mechanism on inhibit expression of these cytokines by TGI1002should be taken. It is known that IFN-y-STAT1-T-bet form a positive regulate circulation, which plays a key role in stable Thl cell phenotype. TGI1002could inhibit the expression of T-bet in activated T cell, it also could inhibited phosphorylation of STAT1in a dose dependent manner. How TGI1002to inhibit phosphorylation of STAT1? We incidental found that TGI1002could up-regulate the phosphorylation level of SHP2dose dependently. TGI1002might competitively inhibit the phosphorylation of STAT1through up-regulate the level of phosphorylated SHP2, and inhibit the IFN y/STAT1pathway.In conclusion, TGI1002have significantly therapeutic effect on contact dermatitis mice model. Mechanism of this effect may be related with affect proliferation and function of T cell. TGI1002can competitively inhibit the phosphorylation of STAT1through up-regulate the level of phosphorylated SHP2. Accordingly, inflammation is prevented since activation and proliferation of T cell is T cell is inhibited by TGI1002as cell cycle stop at G0/G1period.