Effect of Conversion to CTLA4Ig on Tacrolimus-Induced Diabetic Rats

CTLA4-Ig protects tacrolimus-induced oxidative stress via inhibiting the AKT/FOXO3 signaling pathway in rats

BACKGROUND/AIMS

Although the conversion from tacrolimus (TAC) to cytotoxic T-lymphocyte-associated antigen 4-immunoglobulin (CTLA4-Ig) is effective in reducing TAC-induced nephrotoxicity, it remains unclear whether CTLA4-Ig has a direct effect on TAC-induced renal injury. In this study, we evaluated the effects of CTLA4-Ig on TAC-induced renal injury in terms of oxidative stress.

METHODS

In vitro study was performed to assess the effect of CTLA4-Ig on TAC-induced cell death, reactive oxygen species (ROS), apoptosis, and the protein kinase B (AKT)/forkhead transcription factor (FOXO) 3 pathway in human kidney 2 cells. In the in vivo study, the effect of CTLA4-Ig on TAC-induced renal injury was evaluated using renal function, histopathology, markers of oxidative stress (8-hydroxy-2'-deoxyguanosine) and metabolites (4-hydroxy-2-hexenal, catalase, glutathione S-transferase, and glutathione reductase), and activation of the AKT/FOXO3 pathway with insulin-like growth factor 1 (IGF-1).

RESULTS

CTLA4-Ig significantly decreased cell death, ROS, and apoptosis caused by TAC. TAC treatment increased apoptotic cell death and apoptosis-related proteins (increased Bcl-2-associated X protein and caspase-3 and decreased Bcl-2), but it was reversed by CTLA4-Ig treatment. The activation of p-AKT and p-FOXO3 by TAC decreased with CTLA4-Ig treatment. TAC-induced renal dysfunction and oxidative marker levels were significantly improved by CTLA4-Ig in vivo. Concomitant IGF-1 treatment abolished the effects of CTLA4-Ig.

CONCLUSION

CTLA4-Ig has a direct protective effect on TAC-induced renal injury via the inhibition of AKT/FOXO3 pathway.

Effect of dual inhibition of DPP4 and SGLT2 on tacrolimus-induced diabetes mellitus and nephrotoxicity in a rat model

Sodium/glucose co-transporter-2 inhibitor (SGLT2i) or dipeptidyl peptidase IV inhibitor (DPP4i) is a newer anti-diabetic drug in type II diabetes mellitus (DM), but their use in tacrolimus (TAC)-induced DM is still undetermined. We performed this study to evaluate the effect of these two drugs in TAC-induced DM and nephrotoxicity in ex vivo and in vivo. In the experimental Sprague Dawley rat model of TAC-induced DM and nephrotoxicity, dual inhibition of DPP4 and SGLT2 significantly decreased blood glucose level, HbA1C and increased plasma insulin levels and pancreatic islet size compared with each drug. In the kidney, dual inhibition improved renal function decreased interstitial fibrosis and profibrotic cytokines compared with DPP4i and SGLT2i alone. Increased oxidative stress by TAC was remarkably decreased with DPP4i or SGLT2i in serum, pancreatic and renal tissues and this decrease was much more significant in the combination group. In in vitro study, TAC decreased the cell viability of human kidney-2(HK-2) cells and insulin-secreting beta-cell-derived line(INS-1) cells. SGLT2i protected TAC-induced cell death in HK-2 cells, but not in INS-1 cells. The addition of DPP4i to SGLT2i compensated for a lack of protective effect of SGLT2i on INS-1 cells. This finding provides the rationale for the combined treatment of SGLG2i and DPP4i in TAC-induced DM and nephrotoxicity.

Tacrolimus Decreases Cognitive Function by Impairing Hippocampal Synaptic Balance: a Possible Role of Klotho

The influence of long-term tacrolimus treatment on cognitive function remains to be elucidated. Using a murine model of chronic tacrolimus neurotoxicity, we evaluated the effects of tacrolimus on cognitive function, synaptic balance, its regulating protein (Klotho), and oxidative stress in the hippocampus. Compared to vehicle-treated mice, tacrolimus-treated mice showed significantly decreased hippocampal-dependent spatial learning and memory function. Furthermore, tacrolimus caused synaptic imbalance, as demonstrated by decreased excitatory synapses and increased inhibitory synapses, and downregulated Klotho in a dose-dependent manner; the downregulation of Klotho was localized to excitatory hippocampal synapses. Moreover, tacrolimus increased oxidative stress and was associated with activation of the PI3K/AKT pathway in the hippocampus. These results indicate that tacrolimus impairs cognitive function via synaptic imbalance, and that these processes are associated with Klotho downregulation at synapses through tacrolimus-induced oxidative stress in the hippocampus.

pre-existing diabetes and PTDM in kidney transplant recipients: how to handle immunosuppression

INTRODUCTION

Preexisting diabetes (PD) and post-transplant diabetes mellitus (PTDM) are common and severe comorbidities posttransplantation. The immunosuppressive regimens are modifiable risk factors.

AREAS COVERED

We reviewed Pubmed and Cochrane database and we summarize the mechanisms and impacts of available immunosuppressive treatments on the risk of PD and PTDM. We also assess the possible management of these drugs to improve glycemic parameters while considering risks inherent in transplantation.

EXPERT OPINION

PD i) increases the risk of sepsis, ii) is an independent risk factor for infection-related mortality, and iii) increases acute rejection risk. Regarding PTDM development i) immunosuppressive strategies without corticosteroids significantly reduce the risk but the price may be a higher incidence of rejection; ii) minimization or rapid withdrawal of steroids are two valuable approaches; iii) the diabetogenic role of calcineurin inhibitors(CNIs) is also well-described and is more important for tacrolimus than for cyclosporine. Reducing tacrolimus-exposure may improve glycemic parameters but also has a higher risk of rejection. PTDM risk is higher in patients that receive sirolimus compared to mycophenolate mofetil. Finally, conversion from CNIs to belatacept may offer the best benefits to PTDM-recipients in terms of glycemic parameters, graft and patient-outcomes.

The therapeutic efficacy of water-soluble coenzyme Q10 in an experimental model of tacrolimus-induced diabetes mellitus

BACKGROUND/AIMS

Coenzyme Q10 (CoQ10) has antioxidant effects and is commercially available and marketed extensively. However, due to its low bioavailability, its effects are still controversial. We developed a water-soluble CoQ10-based micelle formulation (CoQ10-W) and tested it in an experimental model of tacrolimus (TAC)-induced diabetes mellitus (DM).

METHODS

We developed CoQ10-W from a glycyrrhizic-carnitine mixed layer CoQ10 micelle preparation based on acyltransferases. TAC-induced DM rats were treated with either lipid-soluble CoQ10 (CoQ10-L) or CoQ10-W for 4 weeks. Their plasma and pancreatic CoQ10 concentrations were measured using liquid chromatography- tandem mass spectrometry. The therapeutic efficacies of CoQ10-W and CoQ10-L on TAC-induced DM were compared using functional and morphological parameters and their effects on cell viability and reactive oxygen species (ROS) production were also evaluated in cultured rat insulinoma cells.

RESULTS

The plasma CoQ10 level was significantly increased in the CoQ10-W group compared to that in the CoQ10-L group. Intraperitoneal glucose tolerance tests and glucose-stimulated insulin secretion revealed that CoQ10-W controlled hyperglycemia and restored insulin secretion significantly better than CoQ10-L. The TAC-mediated decrease in pancreatic islet size was significantly attenuated by CoQ10-W but not by CoQ10-L. TAC-induced oxidative stress and apoptosis were significantly more reduced by CoQ10-W than CoQ10-L. Electron microscopy revealed that CoQ10-W restored TAC-induced attenuation in the number of insulin granules and the average mitochondrial area, unlike CoQ10-L. In vitro studies showed that CoQ10-L and CoQ10-W both improved cell viability and reduced ROS production in TAC-treated islet cells to a similar extent.

CONCLUSION

CoQ10-W has better therapeutic efficacy than CoQ10-L in TAC-induced DM.

Late Conversion From Calcineurin Inhibitors to Belatacept in Kidney-Transplant Recipients Has a Significant Beneficial Impact on Glycemic Parameters

Background.

Calcineurin inhibitors (CNIs) and steroids are strongly associated with new-onset diabetes after transplantation, worsening of pre-existing diabetes, and cardiovascular events. We assessed the benefit of conversion from CNI-based to belatacept-based immunosuppression in diabetic kidney-transplant (KT) recipients on glucose control and cardiovascular risk factors.

Methods.

In this retrospective, noncontrolled single-study conducted between May 2016 and October 26, 2018, we recruited KT recipients converted from CNIs to belatacept at least 6 months after KT. The primary endpoint was the evolution of hemoglobin A1c (HbA1c) between baseline and after 6 months of treatment. Secondary endpoints included modifications to antidiabetic drugs, other cardiovascular risk factors, and renal function.

Results.

One hundred and three KT recipients were included. Of these, 26 (25%) had type 2 diabetes. The patients were either receiving oral antidiabetic drugs (n = 21; 75%) or insulin therapy (n = 14; 54%). Overall HbA1c decreased significantly from 6.2 ± 1 to 5.8 ± 1%, P < 0.001. In diabetic patients, HbA1c decreased from 7.2 ± 1 to 6.5 ± 1%, P = 0.001. HbA1c significantly decreased in the subgroup of patients with new-onset diabetes after transplantation and whether diabetes was controlled at inclusion or not (ie, HA1c ≤7% or >7%). Moreover, no diabetic patient increased the number of oral antidiabetic drugs and the dose of basal insulin was not statistically different from baseline to 6 months (16 international unit at baseline and 16 international unit at 6 mo, P = 1). One patient had to start treatment by insulin pump. During follow-up, the renal function, body mass index, and hemoglobin level of all 103 patients remained stable, 2 patients presented acute cellular rejection, and no patient suffered from graft loss.

Conclusions.

A late switch from CNI to belatacept was a valuable therapeutic option for diabetic kidney recipients and substantially improved glycemic parameters.

Influence of Tacrolimus on Depressive-Like Behavior in Diabetic Rats Through Brain-Derived Neurotrophic Factor Regulation in the Hippocampus

The neurotoxicity of immunosuppressive agents and diabetes mellitus are known risk factors of neurological complications in kidney transplant recipients. The aim of the present study was to investigate the influence of tacrolimus on brain-derived neurotrophic factor (BDNF), the critical protein for maintenance of neuronal functions, in the hippocampus in a diabetic condition. A diabetic rat model was established by a single streptozotocin injection (60 mg/kg). Control and diabetic rats then received daily tacrolimus (1.5 mg/kg per day) injections for 6 weeks. BDNF expression in the hippocampus was examined in the dentate gyrus (DG) and CA3 region using immunohistochemistry. There was a significant decrease of BDNF expression in the DG and CA3 region in tacrolimus-treated and diabetic rats compared with that of the control group injected with vehicle only. However, there was no difference in BDNF expression between the two experimental groups. Tacrolimus treatment in diabetic rats further decreased the BDNF expression level in the DG and CA3 region. Interestingly, mossy fiber sprouting, demonstrated by prominent punctate immunolabeling of BDNF with synaptoporin, was observed in the diabetic group treated with tacrolimus, which localized at the stratum oriens of the CA3 region. These data suggest that tacrolimus treatment or a diabetic condition decreases BDNF expression in the hippocampus, and that tacrolimus treatment in the diabetic condition further injures the CA3 region of the hippocampus. In addition to BDNF expression, decreased locomotor activity and evident depressive behavior were observed in tacrolimus-treated diabetic rats. Moreover, there were significant decreases of the mRNA levels of γ-aminobutyric acid and serotonin receptors in the diabetic hippocampus with tacrolimus treatment. This finding suggests that tacrolimus treatment may cause further psychiatric and neurological complications for patients with diabetes, and should thus be used with caution.