A novel rodent model of severe renal ischemia reperfusion injury

Epigenetic restoration of endogenous Klotho expression alleviates acute kidney injury-diabetes comorbidity

AIMS

The present study aimed at exploring the mechanisms behind Klotho regulation in hyperglycemia augmented AKI. In addition, epigenetic ways to restore the Klotho expression in AKI-diabetes comorbidity have been evaluated.

MAIN METHODS

Bilateral ischemia-reperfusion injury (IRI) and chemical hypoxia-reperfusion injury (HRI) were developed in diabetic rats and, NRK52E cells under high glucose conditions respectively, to mimic the AKI condition. Plasma, urine, tubular lysate of the kidney and NRK52E cell lysate were used for biochemical, ELISA, histology, immunoblotting, RT-PCR and RNA interference studies.

KEY FINDINGS

Hyperglycemia significantly aggravated IRI/HRI induced AKI as evidenced by biochemical and histological results. We also observed a significant increase in expressions of kidney specific histone deacetylases (HDACs), apoptotic and inflammatory proteins, and decrease in levels of endogenous Klotho, H3K9Ac and H3K27Ac proteins in hyperglycemic IRI/HRI groups.

SIGNIFICANCE

Diabetes comorbidity exaggerates AKI, where endogenous Klotho loss could be a potential connecting link. However, kidney-specific HDACs inhibition showed reno-protection via restoring the endogenous Klotho loss and thus prevention of inflammation and apoptosis, which could prove to be a potential therapeutic strategy against diabetes-AKI comorbidity.

A Rat Model of Orthotopic Kidney Transplantation Based on Nonanastomotic Technique

BACKGROUND

Renal transplantation is an effective treatment for end-stage renal disease, which involves pathophysiologic processes such as ischemia-reperfusion injury and immune rejection. The degree of ischemia-reperfusion injury is closely related to the functional state of the transplanted kidney. At present, the allogeneic kidney transplantation model has been widely used in related research. The traditional kidney transplantation model has the disadvantages of complicated vascular anastomosis, difficulty in ureteral reconstruction. The aim of this study was to establish a rat autologous orthotopic kidney transplantation model based on non-anastomotic technique.

METHODS

Inbred Wistar rats weighing 260 to 280 g were selected. The rats were anesthetized by intraperitoneal injections of 40 mg/kg body weight pentobarbital sodium. We exposed and freed the left kidney after laparotomy and separated the left renal artery and left renal vein, abdominal aorta, and posterior vena cava. A purse-string suture with a diameter of 1 to 2 mm was made through the tunica media of the abdominal aorta. A puncture was made through the center of the purse-string suture. The in-dwelling needle was placed in the renal artery along the blood flow direction, and was infused with constant flow of 4°C heparinized lactated ringer's solution until the kidney became pale yellow. The renal vein was ligated and the renal artery was clamped. The in-dwelling needle was removed, purse-string suture was ligated, and the kidney was stored in a self-made autologous kidney transplant cold storage bag for 4 hours. We then opened the vein and artery, removed the cold storage bag, and rewarmed with 37°C normal saline. The abdomen was then closed layer by layer.

RESULTS

Fifty-two orthotopic renal transplantations were performed, which included pre-experimental (40 operations) and experimental stages (12 operations). The success rates of the 2 stages were 75% and 91.7%, respectively. The main causes of failure were intraoperative hemorrhagic shock and postoperative infection. The operation time of orthotopic renal transplantation was 360 ± 30 minutes, including 30 ± 10 minutes for dissociation and management of kidney and blood vessels, 1 ± 0.5 minutes for warm ischemia and 240 ± 10 minutes for cold storage. Rats were sacrificed at 1 day and 7 day respectively. The rats were in good condition after operation. They could eat and drink freely. At 24 hours and 1 week after transplantation, the kidney's blood supply was good, the intestine was light or showed no adhesions, and the abdominal cavity had no ascites or peculiar smell. Hematoxylin & eosin (H&E) staining showed that there were no obvious pathologic changes in the sham group. The orthotopic kidney transplantation 1-day group showed pathologic changes of ischemia-reperfusion, such as swelling, necrosis, shedding, and cast formation of renal tubular cells. The orthotopic kidney transplantation 7-day group recovered well, with mild dilation of the renal capsule and mild dilatation of the renal tubules.

CONCLUSION

The new model of autologous kidney transplantation is simple to use, does not require vascular anastomosis and ureteral reconstruction, and has a high success rate.

Compound α-keto acid tablet supplementation alleviates chronic kidney disease progression via inhibition of the NF-kB and MAPK pathways

Background

Keto-analogues administration plays an important role in clinical chronic kidney disease (CKD) adjunctive therapy, however previous studies on their reno-protective effect mainly focused on kidney pathological changes induced by nephrectomy. This study was designed to explore the currently understudied alternative mechanisms by which compound α-ketoacid tablets (KA) influenced ischemia–reperfusion (IR) induced murine renal injury, and to probe the current status of KA administration on staving CKD progression in Chinese CKD patients at different stages.

Methods

In animal experiment, IR surgery was performed to mimic progressive chronic kidney injury, while KA was administrated orally. For clinical research, a retrospective cohort study was conducted to delineate the usage and effects of KA on attenuating CKD exacerbation. End-point CKD event was defined as 50% reduction of initial estimated glomerular filtration rate (eGFR). Kaplan–Meier analysis and COX proportional hazard regression model were adopted to calculate the cumulative probability to reach the end-point and hazard ratio of renal function deterioration.

Results

In animal study, KA presented a protective effect on IR induced renal injury and fibrosis by attenuating inflammatory infiltration and apoptosis via inhibition of nuclear factor-kappa B (NF-κB) and mitogen-activated protein kinase (MAPK) pathways. In clinical research, after adjusting basic demographic factors, patients at stages 4 and 5 in KA group presented a much delayed and slower incidence of eGFR decrease compared to those in No-KA group (hazard ratio (HR) = 0.115, 95% confidence interval (CI) 0.021–0.639, p = 0.0134), demonstrating a positive effect of KA on staving CKD progression.

Conclusion

KA improved IR induced chronic renal injury and fibrosis, and seemed to be a prospective protective factor in end stage renal disease.