| Background:lung transplantation is the unique effective treatment for terminal pulmonary diseases, since the first allo-graft lung transplatation was accomplished successfully in 1983, it was used more and more in clinic and developed sufficiently. Currently, more than 2000 cases are completed in the world every year. By 2010, 32652 cases are accomplished in 158 centers worldwide, and the median survival time is 5.3y, the survival rate of 5 and 10 year are 52% and 29%. The survival rate is raised with the development of lung protective technique, anti-rejection technique, and combination of vary departments[1].The peroperative death is still a significant factor causing the failure of lung transplantation, according to statistics, the main cause of death is primary graft dysfunction(PGD) induced by ischemia reperfusion(I/R) injury[2]. Although the skills of operation, techniques of lung protection and intensive care therapy are improving, PGD is still the main cause of death in the early stage of lung transplantation[3]. Nonspecific alveolus injury, pulmonary edema, and hypoxemia within 72hrs post-transplantation are the major manifest of ischemia reperfusion injury[4]. In the previous two decades, the mechanisms of IR injury were interpreted more and more perspicuously, the use of new lung protective fluid and technology reduced the rate of PGD from 30% in 1990s to 12% presently. However, the lung has its specific physiological nature via other parenchymatous organs[5], and is more sensitive to ischemia and other ectogenesis enviromental stimulus, the acquisition and protection of lung are more strict than others. According to statistics, about 75% patient with terminal pulmonary diseases died during the waiting for suitable donors[6]. With the purpose of the release of IR injury and enlargement of donor sources, it is important to exploit new medicines for the storage of lung which can protect even revive lung functions.T lymphocyte surface differentiated antigen CD26/DPPIV is a multifunctional typeâ…¡transmembrane glycoprotein with relative molecular mass of 110kDa, which possess dipeptidase enzyme activity and express on the surfaces of varied cells such as epithelial cells, T lymphocytes, and endotheliocytes. Its over-expression is also found in lung tissues[7]. Our research showed that I/R injury in rat lung transplantation can be released obviously by inhibiting the activity of DDPâ…£enzyme in the donor lung, and pulmonary fuction can be improved in short-term(2h) [8-9]. However, the effects of inhibiting the activity of DDPâ…£enzyme for long-term lung function after transplantation and the concrete mechanism for relieving IRI of transplanted lung are not clear yet. It is suspected to be related to the regulation of inflammation by DDPIV enzyme and the protection of lung function by its substrate[10]. By this experiment, we intend to investigate the effects of donor's DPPIV enzyme activity inhibition on long-term lung function post-operation, and investigate the expression of differential proteins in lung tissue after inhibiting donor's DPPIV enzyme activity by the methods of differential proteomics, to clarify the mechanisms of relieving I/RI after lung transplantation with the activity of DDPIV enzyme inhibition.Objective:To setup rat lung transplantation model, study the effect of inhibition of donor's inhibiting donor's DPPIV enzyme activity on long time lung function post-transplantation, and to find the expression of differential proteins in lung tissue after inhibiting donor's DPPâ…£enzyme activity at 1d post-transplantation by the technique of differential proteomics, and probe the mechanism of relieving IR injury after lung transplantation by inhibiting DPPIV enzyme activity.Methods:SD rats for experimental animals, we use modified "tri-cannulations" model to set up rat in-situ allograft lung transplantation. Donor lung tissue was perfused with specific DPPâ…£enzyme inhibitor AB192 and preserved for 18h before transplantation, I/R injury after transplatation and effects for long-term lung function were observed. Proteomics was studied betweem the lung tissues perfused and preserved with AB192 and the non-interference ones in control groups, then two set of total protein were separated by two-dimensional polyacrylamide electrophoresis and differentially expressed protein site were searched. Under using MALDI-TOF mass chromatographic analysis, the proteins were detected by mass spectrum. Finally, we validate the protein by euzymelinked immunosorbent assay, and the use the protein to investigate its effect on lung I/R injury.Result:Stable pattern of in situ rat lung transplantation was setup. All the rats of control group died in 7d after transplantation, while all survived exceed 7days in the experimental group(DPPâ…£enzyme was inhibited specificitily). Comparing with the control group, PIP decreased(P<0.05), PO2 increased (P< 0.05) and W/D decreased (P<0.05), MPO activity and MDA content decreased (P<0.05) in experimental groups. The indexes mentioned above improved in experimental group along with the time and every index approached normal level at the 7 day after operation. Differential proteomics was applied to find the discrepancy protein expression in donor lung tissue after DPPW enzyme was inhibited,2D-PAGE icons at the 1 days after operation were compared between the two set of lung tissues, and 87 discrepancy protein spots were obtained. Multiple discrepancy proteins were identified after mass spectrum peptide finger print map analysis for 15 spots. Amomg the total,9 discrepancy proteins were over-expressed in experimental group while were hypo-expressed or non-expressed in control group.6 were over-expressed in control group.Conclusion:Specific DPPâ…£enzyme inhibitor can obviously relieve the IR injury after rat lung transplantation and promote the recovery of lung function. We successfully construct 2-DE icons of rat lung tissue by protein electrophoresis, detect multiple discrepancy protein expression and identify 15 of them. Proteins that can protect lung function or participate in cell signal transduction pathways were detected. ATâ…¢May be the substrate of DPPâ…£enzyme to protect lung function.
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