Correlation Between Tacrolimus And New-onset Diabetes Mellitus After Liver Transplantation And Its Mechanism Research

Background:New-onset diabetes mellitus (NODM) is one of the most common complications after liver transplantation, whose incidence after organ transplantation is up to15%-38%reported by various transplantation centers around the world. NODM is closely related to some severe complications, such as infection, renal failure, graft dysfunction, and cardiovascular complications, greatly affecting the life quality of organ transplant recipients and long-term survival rate. In this decade, with the rapid progress in the field of organ transplantation, and steadily increased survival rate of recipients, postoperative NODM has becoming a particularly prominent problem.The pathogenesis of NODM is complex, has not been fully elucidated yet. It’s reported that many factors may be associated with NODM:such as the use of immunosuppressants, hepatitis C virus (HCV) infection, overweight, and the mononucleotide polymorphism of TCF7L2gene, etc. Clinical studies have shown that the increased blood glucose and insulin resistance caused by high-dose tacrolimus, can be improved by reducing the drug concentration, therefore, low-dose tacrolimus regiment is widely accepted. However, the incidence of NODM remains stubbornly high, for some patients taking low-dose tacrolimus, the synthesis and secretion of insulin is normal, but NODM still occurs, the specific mechanism has not fully elucidated yet. At present, vast majority of clinical analysis and basic research on NODM are based on kidney transplant recipients, it’s relatively insufficient on the liver transplantation research, and the considered confounding factors are limited, there’s lack of more persuasive multi-center clinical research with large cases and long-term follow-up.In recent years, the relationship between glucose transporters and diabetes has gradually attracted the attention of scholars. Research reports have suggested that the intestinal glucose transporters expression in diabetics is3.3times that in non-diabetic patients; after gastric bypass operation in diabetic mice, proton tracer test shows a decrease in the intestinal absorption of glucose, blood sugar is under control, suggesting the possible function of intestinal glucose transporters in the occurrence and treatment of diabetes. According to above research status at home and abroad, there are reasons to doubt the association between tacrolimus with NODM after liver transplantation, and glucose transporters (especially SGLT1) may participate in the action mechanism of tacrolimus-related NODM occurred after liver transplantation.First Part Effect of preoperative diabetes on liver transplant recipients Objective:To assess the effect of diabetes mellitus (DM) on the long-term survival rate of liver transplant recipients.Methods:23240adults cases receiving their first liver transplantation during January1,2008to December31,2012, were enrolled from Scientific Registry of Transplant Recipients (SRTR), divided into DM group and DM-free group according to whether have a preoperative DM or not. The graft survival and overall survival rates were compared between two groups.Results:The1-year,3-year and5-year graft survival rates of liver transplant recipients in DM group were significantly lower than those in DM-free group (86%,74%,62%vs87%,77%,67%, Log rank:P<0.001). Such confounding factors as age, MELD score, portal vein thrombosis, acute rejection, abdominal surgery history, HCV infection and donor risk index, etc. were included into the multivariable cox regression analysis, results showed that DM was an independent risk factor for graft failure in liver transplant recipients (risk ratio of1.124;95%confidence interval,1.052-1.201, P<0.001). The further time-dependent covariate statistical analysis derived from cox regression found that, the risk ratio of graft failure in diabetic recipients was significantly increased with the extension of survival time after liver transplantation.Conclusions:Preoperative DM is an independent predictor for long-term survival and graft survival of liver transplant recipients, and for its effect on the prognosis of recipients, the hazard level is increased exponentially with the passage of time.Second Part Correlation between tacrolimus and new-onset diabetes mellitus after liver transplantationObjective:The occurrence of NODM after organ transplantation has association with many factors. Currently, it’s generally believed that immunosuppressants play a leading role, but vast majority of clinical analysis and basic research on NODM are based on kidney transplant recipients, this study intends to explore the correlation between immunosuppressants (especially tacrolimus) with NODM in liver transplant recipients.Methods:18741cases of preoperative DM-free adult recipients, were selected from SRTR database, who underwent liver transplantation alone for the first time during January1,2008to December31,2012. Logist regression analyzed the risk factors of NODM, and hierarchical analysis compared the DM-free survival rate. Then hierarchically analyzed the relevance with NODM according to immunosuppressants.Results:The overall incidence of NODM after liver transplantation is16.3%, and more than60%occurs in the first year after liver transplantation. With Kaplan-Meier survival analysis, we found that the1-year,3-year and5-year diabetes-free survival rates in the living donor liver transplantation (LDLT) group were significantly higher than those in the deceased donor liver transplantation (DDLT) group (91%,85%and79%vs85%,80%and71%, P<0.001). While in the Logist regression analysis aiming at the multivariate risk index of NODM, we found that DDLT (risk ratio,1.341;95%confidence interval,1.059-1.698, P=0.015), tacrolimus (risk ratio,1.542;95%confidence interval,1.319-1.804, P<0.001) and hormone (risk ratio,1.531;95%confidence interval,1.374-1.706, P<0.001) were independent risk factors of NODM. Conducted hierarchical analysis according to the different sources of donor, we found that in DDLT group, tacrolimus and hormone were closely related to NODM, especially in liver transplant recipients taking tacrolimus, whose risk of postoperative NODM increased66.2%; In LDLT group, it’s only found hormone was associated with NODM after living donor liver transplantation. In the further research on marginal donor liver, we found that the liver transplantation of donor liver carrying hepatitis B virus didn’t reduce the survival rate of liver transplant recipients; the graft survival and overall survival rates were significantly higher in patients taking tacrolimus than those not taking; but similarly, the diabetes-free survival rate was significantly lower in patients taking tacrolimus than that not taking.Conclusions:In patients with liver transplantation, tacrolimus is closely related to the occurrence of NODM; Patients receiving tacrolimus immunosuppressant regime have higher graft survival rate and overall survival rate; The effect of tacrolimus on the postoperative NODM in DDLT group was far greater than that in LDLT group; In addition, the liver donor carrying hepatitis B virus does not affect the survival rate of recipients and graft survival rate, the use of hepatitis B hyper-immune globulin and tacrolimus can prolong the survival rate of patients, but the latter will also increase the incidence of postoperative NODM.Third Part Research on the molecular mechanism of diabetes caused by tacrolimus based on the intestinal glucose transportersObjective:Previous studies have confirmed that tacrolimus is closely related to the occurrence of NODM, and the role of glucose transporters in diabetes has gradually attracted attention. This study intends to explore the molecular mechanism of diabetes caused by tacrolimus based on the intestinal glucose transporters.Methods:24male C57BL/6mice of8weeks were randomly divided into four groups: control group, low-dose group (tacrolimus0.5mg/kg/d), medium-dose group (tacrolimus1mg/kg/d), and high-dose group (tacrolimus5mg/kg/d). Daily measured the body weight, blood sugar and food intake of mice in every group; conducted oral glucose tolerance test (OGTT) after sustained drug injection for2weeks; detected the intestinal absorption function of sugar with Ussing Chamber technology, quantified it with short-circuit current (Isc) generated by sodium ions co-transported with glucose; observed the postoperative morphologic changes of intestinal tract with hematoxylin and eosin staining; detected the gene transcription and protein expression of glucose transporters with real-time quantitative polymerase chain reaction (qRT-PCR) and Western blot, respectively.Results:When compared with the control group, there had no obvious differences in food intake and body weight in tacrolimus groups; also without significant differences in intestinal histo-morphology; OGTT showed a significant increase in the intestinal absorption of sugar, and accordingly the insulin rose in the body. The glucose-induced Isc was increased significantly in tacrolimus groups, suggesting the activity of intestinal SGLT1was enhanced, PCR and Western Blot also accordingly found a significant increase in SGLT1protein expression, but no significant differences in the mRNA and protein expression levels of intestinal GLUT2and GLUT5, above experimental results had nothing to do with the dose of tacrolimus.Conclusions:For the first time, we confirmed that the intestinal absorption function of glucose plays a certain role in the process of tacrolimus-induced DM; The intestinal glucose transporter SGLT1is closely related to the tacrolimus-related DM; Tacrolimus may cause the occurrence of diabetes by up-regulating the expression and activity of intestinal SGLT1, to enhance the intestinal absorption of glucose and transport, and then increase the blood glucose leading to abnormal glucose tolerance.