Desferrioxamine in warm reperfusion media decreases liver injury aggravated by cold storage

Ferroptosis: A New Target for Hepatic Ischemia-Reperfusion Injury?

Ischemia-reperfusion injury (IRI) can seriously affect graft survival and prognosis and is an unavoidable event during liver transplantation. Ferroptosis is a novel iron-dependent form of cell death characterized by iron accumulation and overwhelming lipid peroxidation; it differs morphologically, genetically, and biochemically from other well-known cell death types (autophagy, necrosis, and apoptosis). Accumulating evidence has shown that ferroptosis is involved in the pathogenesis of hepatic IRI, and targeting ferroptosis may be a promising therapeutic approach. Here, we review the pathways and phenomena involved in ferroptosis, explore the associations and implications of ferroptosis and hepatic IRI, and discuss possible strategies for modulating ferroptosis to alleviate the hepatic IRI.

Combined administration of membrane-permeable and impermeable iron-chelating drugs attenuates ischemia/reperfusion-induced hepatic injury

BACKGROUND

The underlying pathophysiological mechanisms of hepatic ischemia-reperfusion (I/R) injury have not been completely elucidated. However, it is well known that oxidative stress, caused by a burst of reactive oxygen species (ROS) production during the reperfusion phase, plays a crucial role. A growing body of evidence indicates that the intracellular availability of free iron represents a requirement for ROS-induced adverse effects, as iron catalyzes the generation of highly reactive free radicals. The aim of this study was to examine whether a combination of iron chelators with varying lipophilicity could offer enhanced protection against I/R by diminishing the conversion of weak oxidants, like H₂O₂, to extremely reactive ones such as hydroxyl radicals (HO^.).

METHODS

HepG2 cells (hepatocellular carcinoma cell line) were exposed to oxidative stress conditions after pre-treatment with the iron chelators desferrioxamine (DFO) and deferiprone (DFP) alone or in combination. Labile iron pool was estimated using the calcein-acetoxymethyl ester (calcein-AM) method and DNA damage with the comet assay. We subsequently used a rabbit model (male New Zealand white rabbits) of hepatic I/R-induced injury to investigate, by measuring biochemical (ALT, ALT, ALP, γGT) and histological parameters, whether this may be true for in vivo conditions.

RESULTS

The combination of a membrane-permeable iron chelator (DFP) with a strong membrane-impermeable one (DFO) raises the level of protection in both hepatic cell lines exposed to oxidative stress conditions and hepatic I/R rabbit model.

CONCLUSIONS

Our results show that combinations of iron chelators with selected lipophilicity and iron-binding properties may represent a valuable strategy to protect against tissue damage during reperfusion after a period of ischemia.

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-1β 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-1β 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.

Novel NMP split liver model recapitulates human IRI and demonstrates ferroptosis modulators as a new therapeutic strategy

BACKGROUND

Almost 9%of deceased donor livers are discarded as marginal donor livers (MDL) due to concern of severe ischemia reperfusion injury (IRI). Emerging data supports ferroptosis (iron regulated hepatocellular death) as an IRI driver, however lack of robust preclinical model limits therapeutic testing. In this manuscript we describe the development of a novel rigorous internal control system utilizing normothermic perfusion of split livers to test ferroptosis regulators modulating IRI.

METHODS

Upon institutional approval, split human MDLs were placed on our normothermic perfusion machine, Perfusion Regulated Organ Therapeutics with Enhanced Controlled Testing (PROTECT), pumping arterial and portal blood. Experiment 1 compared right (UR) and left (UL) lobes to validate PROTECT. Experiment 2 assessed ferroptosis regulator Deferoxamine in Deferoxamine Agent Treated (DMAT) vs. No Agent Internal Control (NAIC) lobes. Liver serology, histology, and ferroptosis genes were assessed.

RESULTS

Successful MDL perfusion validated PROTECT with no ALT or AST difference between UR and UL (∆ALT UR: 235, ∆ALT UL: 212; ∆AST UR: 576, ∆AST UL: 389). Liver injury markers increased in NAIC vs. DMAT (∆ALT NAIC: 586, ∆ALT DMAT: -405; ∆AST NAIC: 617, ∆AST DMAT: -380). UR and UL had similar expression of ferroptosis regulators RPL8,HO-1 and HIFα. Significantly decreased intrahepatic iron (p = .038), HO-1 and HIFα in DMAT (HO-1 NAIC: 6.93, HO-1 DMAT: 2.74; HIFαNAIC: 8.67, HIFαDMAT: 2.60)and no hepatocellular necrosis or immunohistochemical staining (Ki67/Cytokeratin-7) differences were noted.

CONCLUSION

PROTECT demonstrates the therapeutic utility of a novel normothermic perfusion split liver system for drug discovery and rapid translatability of therapeutics, driving a paradigm change in organ recovery and transplant medicine. Our study using human livers, provides preliminary proof of concept for the novel role of ferroptosis regulators in driving IRI.

Hypothermic oxygenated perfusion (HOPE) attenuates ischemia/reperfusion injury in the liver through inhibition of the TXNIP/NLRP3 inflammasome pathway in a rat model of donation after cardiac death

Hypothermic oxygenated perfusion (HOPE) is a relatively new dynamic preservation procedure that has not been widely implemented in liver transplantation despite its advantages. Improved graft protection is one such advantage offered by HOPE and has been attributed to multiple mechanisms, one of which may be the modulation of the thioredoxin-interacting protein (TXNIP)/NOD-like receptor protein 3 (NLRP3) inflammasome pathway. The TXNIP/NLRP3 inflammasome pathway plays a critical role in sterile inflammation under oxidative stress as a result of ischemia/reperfusion injury (IRI). In the current study, we aimed to investigate the graft protection offered by HOPE and its impact on the TXNIP/NLRP3 inflammasome pathway. To simulate conditions of donation after cardiac death (DCD) liver transplantation, rat livers were exposed to 30 min of warm ischemia after cardiac arrest. Livers were then preserved under cold storage (CS) or with HOPE for 3 h. Livers were then subjected to 1 h of isolated reperfusion. Liver injuries were assessed on the isolated perfusion rat liver model system before and after reperfusion. Compared with the CS group, the HOPE group had a significant reduction in liver injury and improvement in liver function. Our findings also revealed that reperfusion injury induced liver damage and activated the TXNIP/NLRP3 inflammasome pathway in DCD rat livers. Pretreatment of DCD rat livers with HOPE inhibited the TXNIP/NLRP3 inflammasome pathway and attenuated liver IRI. Attenuation of oxidative stress as a result of HOPE led to the down-regulation of the TXNIP/NLRP3 inflammasome pathway and thus offered superior protection compared with the traditional CS method of organ preservation.-He, W., Ye, S., Zeng, C., Xue, S., Hu, X., Zhang, X., Gao, S., Xiong, Y., He, X., Vivalda, S., Li, L., Wang, Y., Ye, Q. Hypothermic oxygenated perfusion (HOPE) attenuates ischemia/reperfusion injury in the liver through inhibition of the TXNIP/NLRP3 inflammasome pathway in a rat model of donation after cardiac death.

Molecular pathways in protecting the liver from ischaemia/reperfusion injury: a 2015 update

Ischaemia/reperfusion injury is an important cause of liver damage during surgical procedures such as hepatic resection and liver transplantation, and represents the main cause of graft dysfunction post-transplantation. Molecular processes occurring during hepatic ischaemia/reperfusion are diverse, and continuously include new and complex mechanisms. The present review aims to summarize the newest concepts and hypotheses regarding the pathophysiology of liver ischaemia/reperfusion, making clear distinction between situations of cold and warm ischaemia. Moreover, the most updated therapeutic strategies including pharmacological, genetic and surgical interventions, as well as some of the scientific controversies in the field are described.

Iron-induced oxidative rat liver injury after non-heart-beating warm ischemia is mediated by tumor necrosis factor α and prevented by deferoxamine

This study investigated iron-induced injury after warm ischemia in a non-heart-beating (NHB) rat liver model and the effects of deferoxamine (DFO). Livers from heart-beating (HB) rats or rats that were NHB for 60 minutes were stored in University of Wisconsin solution for 5 hours at 4°C [cold storage (CS)] and then were subjected to 2 hours of machine reperfusion (MRP) at 37°C. Three NHB groups were compared: (1) no DFO, (2) DFO 30 minutes before cardiac arrest and during CS and MRP, and (3) DFO during CS and MRP. Aspartate aminotransferase (AST) and lactate dehydrogenase (LDH) levels in the NHB perfusate were significantly elevated (P < 0.01) in comparison with levels in HB controls after CS and MRP. After CS, the levels of iron and tumor necrosis factor α (TNF-α) were 0.077 ± 0.007 μmol/g and 151 ± 26 pg/g, respectively, in the NHB group and 0.022 ± 0.004 μmol/g and 17 ± 7 pg/g, respectively, in the HB group (P < 0.01). After MRP, LDH significantly correlated with iron (R(2)  = 0.81, P < 0.01). The DFO pretreatment of NHB donors decreased AST (7.3 ± 0.8 versus 4.0 ± 0.5 U/g of liver, P < 0.05) and LDH (42.5 ± 4.1 versus 20.4 ± 2.5 U/g of liver, P < 0.05) with 2 hours of MRP and increased bile flow during MRP (142 ± 34 versus 240 ± 18 μL/g, P < 0.05). It also reduced the levels of iron (0.077 ± 0.007 versus 0.050 ± 0.008 μmol/g, P < 0.05) and TNF-α (151 ± 26 versus 51 ± 13 pg/g, P < 0.05) after CS and the levels of lipid peroxidation products F2-isoprostane (149 ± 11 versus 99 ± 10 ng/g, P < 0.05) and malondialdehyde (1.58 ± 0.1 versus 1.14 ± 0.08 μmol/g, P < 0.05) after MRP. In conclusion, iron-initiated oxidative stress is likely involved in NHB donor liver injury, and importantly, DFO pretreatment reduces liver damage.