Functional Analyses Of Nimodipine In Allogeneic Islets Transplantation In Mice

Objective:With the development of economy and the change of living habits,diabetes mellitus,as a high-incidence chronic disease,has a greater impact on human health.At present,the incidence of diabetes in China is already ranked second in the world.The prevalence of diabetes not only creates a greater economic and psychological burden on patients,but also becomes a social problem.With the presentation of the Edmonton programme,islet transplantation as one of the final treatment options for diabetes has been getting more and more attention,However,the shortage of transplanted donor and postoperative immune rejection still seriously hinder the clinical development of islet transplantation.In addition,the current islet transplant immunosuppressants programme is expensive and has some renal toxicity and islet toxicity,which not only exacerbates the financial burden on patients,but also has a negative impact on the quality of life of patients.As a clinical first-line drug to control hypertension,Nimodipine has a clear mechanism of toxicological action in the human body.Its protective effect on the pancreatic islet of diabetic patients and its effect on relieving immune inflammation in autoimmune diseases were reported.The purpose of this study was to study the immunomodulatory effect of nimodipine in allogeneic islet transplantation.The role and mechanism of nimodipine in islet transplantation were studied with the model of Allogeneic islet transplantation in mice,in order to obtain an immunosuppressant with better immunosuppressive effect,less toxic side effects and lower cost for clinical islet transplantation.METHODS:We first studied the effects of nimodipine on the structure,function and activity of islet in vitro.The specific method is to place the islet single cell after the pancreatic enzyme digestion in the medium of 5.6uM and 16.7uM glucose respectively,and then detect the apoptosis of islet cells and the secretion of insulin under the action of different concentrations of nimodipine solution(Oug/ml,4.0ug/ml,8ug/mg,12ug/ml,16ug/ml),and find out their correlation.In vivo experiments,we transplanted the islets of 400 Balb/c mice into the renal membranes of C57BL/6 mice,and randomly divided the transplanted receptor mice into 4 drug groups:The control group,the Nimodipine single group,the Rapamycin single group,and the combined application group of Nimodipine and Rapamycin.And the survival period of each group is observed.Pathological,immune factor and cytology were detected in grafts and receptor mice on the tenth day after transplantation.In vitro,we studied the inhibitory effect of nimodipine on the activation and proliferation of T cells,and explored the immunosuppressive mechanism of Nimodipine through a series of experiments,such as T-cell incompetence experiment,apoptosis experiment and immune imprinting experiment,and the possible related pathways of nimodipine and rapamycin to induce tolerance.RESULTS:In vitro experimental studies showed that nimodipine could protect the activity of islet in hypoxic state.In vivo trials of islet transplantation models,the median survival(MST)of the receptor mouse grafts in the control group was 14 days,the Nimodipine group was 25 days,the Rapamycin group was 33 days,and the Nimodipine group and Rapamycin combined group were 40 days,of which two mice were not ostracized after 100 days of transplantation.The experimental results showed that nimodipine could reduce the immune response of Thl and Th2,protect islet grafts,and the combination of Nimodipine and rapamycin was synergistic in inhibiting allogeneic immune response.The protein immunoimprinting test showed that the NF-?B signaling pathway and the p38-MAPK signaling pathway played an important role in inhibiting the activation and proliferation of T cells in Nimodipine,and the p38-MAPK signaling pathway was likely to be related to the synergistic effects of nimodipine and rapamycin.Conclusion:Through this study,we have confirmed for the first time that Nimodipine has protective effects on islets in allogeneic islet transplantation models.Nimodipine may have reduced the level of immune rejection mediated by donor reactive T cells by inducing regulatory T-cell production and T cell cloning incompetence.Moreover,the combined application of nimodipine and rapamycin can create synergy,promote the long-term survival of islet grafts and achieve transplant tolerance,in addition,because of the low toxicity of nimodipine to the human body and the protective effect on islet cells,it is hoped to occupy an important position in the clinical Islet Transplantation immunosuppressive program.