3-O-Methyl-D-Glucose Blunts Cold Ischemia Damage in Kidney via Inhibiting Ferroptosis.

BACKGROUND: The glucose derivative 3-O-methyl-D-glucose (OMG) is used as a cryoprotectant in freezing cells. However, its protective role and the related mechanism in static cold storage (CS) of organs are unknown. The present study aimed to investigate the effect of OMG on cod ischemia damage in cold preservation of donor kidney. METHODS: Pretreatment of OMG on kidney was performed in an isolated renal cold storage model in rats. LDH activity in renal efflux was used to evaluate the cellular damage. Indicators including iron levels, mitochondrial damage, MDA level, and cellular apoptosis were measured. Kidney quality was assessed via a kidney transplantation (KTx) model in rats. The grafted animals were followed up for 7 days. Ischemia reperfusion (I/R) injury and inflammatory response were assessed by biochemical and histological analyses. RESULTS: OMG pretreatment alleviated prolonged CS-induced renal damage as evidenced by reduced LDH activities and tubular apoptosis. Kidney with pCS has significantly increased iron, MDA, and TUNEL+ cells, implying the increased ferroptosis, which has been partly inhibited by OMG. OMG pretreatment has improved the renal function (p <0.05) and prolonged the 7-day survival of the grafting recipients after KTx, as compared to the control group. OMG has significantly decreased inflammation and tubular damage after KTx, as evidenced by CD3-positive cells and TUNEL-positive cells. CONCLUSION: Our study demonstrated that OMG protected kidney against the prolonged cold ischemia-caused injuries through inhibiting ferroptosis. Our results suggested that OMG might have potential clinical application in cold preservation of donor kidney.

Effects of prolonged cold ischemia on the DCD kidney function and Inflammasome expression in rat kidney transplants.

BACKGROUND: Acute kidney injury (AKI) is the main reason for the bad outcome of the donation of circulatory death (DCD) kidney after transplantation. Prolonged cold storage (CS) is a risk factor for the occurrence of the delayed graft function in DCD kidney. The protein NLR-domain containing receptor 3 (NLRP3) plays a crucial role in renal ischemia reperfusion injury by triggering inflammasome formation. Herein, we investigated whether the NLRP3 signal participate in the CS-induced damage of DCD kidney in rat kidney transplantation models. MATERIALS AND METHODS: DCD kidney and living donor (LD) kidney of SD rats were preserved in UW solution at 4 °C for 2 h or 18 h, and then transplanted into syngeneic recipient. Thus, the animals were randomly divided into 4 groups: 2-h LD group, 2-h DCD group, 18-h LD group and 18-h DCD group. The renal function and pathological changes were determined. The expressions of NLRP3 and inflammatory factor IL-1ß were assessed. The concentration of ferrous iron (Fe2+) was analyzed both in kidneys and in the preservation solution. The renal morphological changes were examined by hematoxylin eosin staining. RESULTS: Our results showed that the levels of Cr and BUN were higher in 18-h LD group as compared to the 2-h LD group, which were remarkably increased in 18-h DCD group. The expression levels of NLRP3 and IL-1ß were increased by 18-h CS compared to 2-h CS in both LD kidney and DCD kidney. In addition, the Fe2+ concentration has significantly increased in 18-h LD group than that in 2-h LD group, and the elevation of Fe2+ was more remarkable in DCD kidneys. CONCLUSION: In conclusion, our study demonstrated that prolonged hypothermic storage of DCD kidney deteriorated the graft function via the increased Fe2+ concentration, which was associated with the upregulation of NLRP3 expression.

CXC Chemokine Receptor Type 4 Antagonism Ameliorated Allograft Fibrosis in Rat Kidney Transplant Model.

OBJECTIVES: In this study, we evaluated the effects of CXC chemokine receptor type 4 and stromal cell-derived factor 1 signaling in the progression of chronic allograft nephropathy in a rat model. MATERIALS AND METHODS: Experimental rats were divided into 3 groups: Lewis-to-Lewis isograft transplant (group A), Fisher 344 rat-to-Lewis allograft transplant with immunosuppressant cyclosporine (group B), and Fisher 344 rat-to-Lewis allograft transplant treated with cyclosporine and the CXC chemokine receptor type 4 antagonist AMD3100 (1 mg/kg/d) (group C). On day 90 after the operation, renal graft function, proteinuria, and histologic Banff score were measured. The expression levels of transforming growth factor ß1 and collagen IV were determined by quantitative real-time polymerase chain reaction. RESULTS: Renal function and urinary protein were increased in allografts of groups B and C compared with isografts of group A. The Banff score was significantly decreased in the AMD3100-treated animals (group C), with renal fibrosis being reduced. In addition, overexpressed levels of transforming growth factor ß1 and collagen IV in group B allografts were significantly reduced versus that shown with treatment with the CXC chemokine receptor type 4 antagonist in group C. CONCLUSIONS: Together, these data strongly implicate that CXC chemokine receptor type 4 antagonism alleviated renal interstitial fibrosis in long-term surviving allografts by down-regulating expression of transforming growth factor ß1.

Prolonged ischemia elicits acute allograft rejection involved in CXCR3 activation in rat kidney transplants.

BACKGROUND: Acute rejection is a major obstacle in patients with prolonged ischemia in deceased-donor renal transplantation. Chemokines and their receptors play a critical role in leukocyte trafficking, resulting in allograft rejection; therefore, the role of chemokine receptor CXCR3 in acute rejection induced by prolonged ischemia in rat kidney transplantation models was evaluated. METHODS: Syngeneic and allogeneic renal transplantations were performed. For cold ischemia, grafts were stored in 4.0°C University of Wisconsin solution for 12 or 16 h. Serum and renal tissues were harvested 7.0 d after surgery and serum TNF-α, IL-6, and renal function were measured. Graft histology was stained with periodic acid-Schiff and immunohistochemical staining and further evaluated for signs of acute rejection. CXCR3 proteins were quantified by Western blot. The transplanted rats were divided into 4 groups as follows: iso-12-h = isogeneic transplant with 12-h CIT graft; iso-16-h = isogeneic kidney transplant with 16-h CIT graft; allo-12-h = allogeneic renal transplant with 12-h CIT graft; allo-16 h = allogeneic renal transplant with 16-h CIT graft; and 16 h+T = allogeneic 16-h CIT graft received tacrolimus. RESULTS: Prolonged cold ischemia time (CIT; 16 h) enhanced acute glomerular damage, interstitial inflammation, and tubulointerstitial cellular infiltration in allografts with and without immunosuppressant tacrolimus; but it was not apparent in the isografts. The expression of CXCR3 protein and the proportion of CXCR3-positive cells were significantly higher in the allo-16 h and 16 h +T groups than that in the allo-12 h group 7d post-surgery. CONCLUSIONS: CIT triggered acute rejection in allogeneic, but not in isogeneic, kidney transplants, accompanied by an elevation of leukocyte recruitment and damaged graft function. The upregulated expression of chemokine receptor CXCR3 promoted inflammatory infiltration and acute allograft rejection.