Curcumin Alleviates Hepatic Ischemia-Reperfusion Injury by Inhibiting Neutrophil Extracellular Traps Formation

BACKGROUND

Hepatic ischemia-reperfusion injury (IRI) is a common innate immune-mediated sterile inflammatory response in liver transplantation and liver tumor resection. Neutrophil extracellular traps (NETs) can aggravate liver injury and activates innate immune response in the process of liver IRI. However, Curcumin (Cur) can reverse this damage and reduce NETs formation. Nevertheless, the specific regulatory mechanism is still unclear in liver IRI. This study aimed to explore the potential mechanisms that how does Cur alleviate hepatic IRI by inhibits NETs production and develop novel treatment regimens.

METHODS

We established a hepatic IRI model by subjecting C57BL/6J mice to 60 min of ischemia, followed by reperfusion for 2 h, 6 h, 12 h, and 24 h respectively. Subsequently, we were separated into 5 groups, namely the I/R group, Cur group, DNase-1 group, Cur + DNase1 group and sham operation group. Serum alanine aminotransferase (ALT) and aspartate transaminase (AST), Hematoxylin-eosin staining, immunofluorescence, and TUNEL analysis were applied to assess liver injury degree and NETs levels. Western blot assay was used to detect the protein levels of apoptosis-related proteins and MEK pathway proteins.

RESULTS

Cur could alleviate hepatic IRI by inhibiting the generation of NETs via suppressing the MEK/ERK pathway. In addition, this study also revealed that DNase-1 is vital for alleviating hepatic IRI by reducing the generation of NETs.

CONCLUSIONS

Cur combined with DNase-1 was more effective than the two drugs administered alone in alleviating hepatic IRI by inhibiting the generation of NETs. These results also suggested that curcumin combined with DNase-1 was a potential therapeutic strategy to mitigate hepatic IRI.

Mesoporous Hollow Manganese Doped Ceria Nanoparticle for Effectively Prevention of Hepatic Ischemia Reperfusion Injury

Introduction

Hepatic ischemia-reperfusion injury (HIRI) is the main reason for liver dysfunction or failure after liver resection and liver transplantation. As excess accumulation of reactive oxygen species (ROS) is the leading factor, ceria nanoparticle, a cyclic reversible antioxidant, is an excellent candidate for HIRI.

Methods

Manganese doped mesoporous hollow ceria nanoparticles (MnO_x-CeO₂ NPs) were prepared, and the physicochemical characteristics, such as particle size, morphology, microstructure, etc. were elucidated. The in vivo safety and liver targeting effect were examined after i.v. injection. The anti-HIRI was determined by a mouse HIRI model.

Results

MnO_x-CeO₂ NPs with 0.40% Mn doped exhibited the strongest ROS-scavenging capability, which may due to the increased specific surface area and surface oxygen concentration. The nanoparticles accumulated in the liver after i.v. injection and exhibited good biocompatibility. In the HIRI mice model, MnO_x-CeO₂ NPs significantly reduced the serum ALT and AST level, decreased the MDA level and increased the SOD level in the liver, prevent pathological damages in the liver.

Conclusion

MnO_x-CeO₂ NPs were successfully prepared and it could significantly inhibit the HIRI after i.v. injection.

Treprostinil Supplementation Ameliorates Hepatic Ischemia Reperfusion Injury and Regulates Expression of Hepatic Drug Transporters: An Isolated Perfused Rat Liver (IPRL) Study

Purpose

IR injury is an unavoidable consequence in deceased donor liver transplantation. Cold preservation and warm reperfusion may change the expression and function of drug transporters in the liver due to vasoconstriction, infiltration of neutrophils and release of cytokines. We hypothesize that vasodilation, anti-platelet aggregation and proinflammatory downregulation activities of treprostinil will diminish the IR injury and its associated effects.

Methods

Livers obtained from male SD rats (n = 20) were divided into 1) Control, 2) IR, 3) Treprostinil-1 (preservation only), and 4) Treprostinil-2 (preservation and reperfusion) groups. Control livers were procured and immediately reperfused. Livers in the other groups underwent preservation for 24 h and were reperfused. All the livers were perfused using an Isolated Perfused Rat Liver (IPRL) system. Periodic perfusate, cumulative bile samples and liver tissue at the end of perfusion were collected. Liver injury markers, bile flow rates, m-RNA levels for uptake and efflux transporters (qRT-PCR) were measured.

Results

Cold preservation and warm reperfusion significantly increased the release of AST and ALT in untreated livers. Treprostinil supplementation substantially reduced liver injury. Bile flow rate was significantly improved in treprostinil-2 group. m-RNA levels of Slc10a1, Slc22a1, and Slc22a7 in liver were increased and m-RNA levels of Mdr1a were decreased by IR. Treprostinil treatment increased Abcb11 and Abcg2 m-RNA levels and maintained Slc22a1m-RNA similar to control livers.

Conclusions

Treprostinil treatment significantly reduced liver injury. IR injury changed expression of both uptake and efflux transporters in rat livers. Treprostinil significantly altered the IR injury mediated changes in m-RNA expression of transporters.

PPARγ Mediates Protective Effect against Hepatic Ischemia/Reperfusion Injury via NF-κB Pathway

BACKGROUND

Hepatic ischemia/reperfusion injury (HIRI) is an unavoidable complication in liver surgery, however its pathological process is still unclear. Therefore, in this study, the role and mechanism of peroxisome proliferator-activated receptor gamma (PPARγ) was investigated in HIRI.

MATERIALS AND METHODS

We constructed mice models with HIRI and L02 cell models insulted hypoxia/re-oxygenation (H/R). PPARγ agonist rosiglitazone was administered prior to HIRI in mice and PPARγ-siRNA was to H/R treatment in L02 cells. Liver injury was measured by serum ALT, AST and LDH levels and performing H&E staining; the inflammatory injury was reflected by inflammatory markers IL-1β, IL-6 and TNF-α, which were assayed by Real-time PCR and Western blotting, MPO activity was determined using commercial kits; oxidative stress injury was evaluated by iNOS, MDA, SOD and GSH-PX levels; apoptosis was detected by cleaved-Caspase-3, TUNEL staining and flow cytometry; NF-κB signaling activation was reflected by phosphorylation of IκBα (p-IκBα) and nuclear translocation of NF-κB p65.

RESULTS

The level of PPARγ expression was obviously down-regulated both in mice liver subjected to IRI and in L02 cells to H/R. Overexpression of PPARγ presented protective effect on HIRI by reducing serum levels of aminotransferase and hepatic necrosis, inhibiting inflammation and apoptosis and alleviating oxidative stress in vivo. But PPARγ-siRNA aggravate H/R insult by promoting inflammation and apoptosis in vitro. Mechanistically, the NF-κB pathway activity was increased with PPARγ down-regulation by PPARγ-siRNA. Importantly, inhibition of NF-κB signaling abolished PPARγ knockdown-mediated hepatic injury.

CONCLUSIONS

PPARγ present protective effects on HIRI by attenuating liver injury, inflammatory response, oxidative stress and apoptosis in vivo and in vitro, and its mechanism may be related to down-regulation of NF-κB signaling.

Perioperative kidney injury in liver transplantation: a prospective study with renal histology and measured glomerular filtration rates

BACKGROUND

Acute kidney injury (AKI) is frequent after liver transplantation (LT), with impact on graft function, morbidity and mortality. Although multifactorial, the pathophysiology of perioperative kidney injury remains unclear. Our aims were to analyze the frequency, evolution and risk factors for kidney impairment during the peri- and early post-operative period.

METHODS

In a prospective, single-center study of 27 adult patients undergoing first single-organ LT, we analyzed measured glomerular filtration rate (mGFR) pre-transplant, at post-operative day (POD) 10, and at 1, 3, 12 and 36 months. Kidney and liver graft biopsies were performed during LT.

RESULTS

A median mGFR decline of 45% was detected from pre-transplant to POD 10, correlating strongly with the mGFR evolution from baseline to 12 months (rs = 0.80, p<.001) and baseline to 36 months (rs = 0.82, p<.001). AKI occurred in 59% of recipients within 48 h of LT, notably before the introduction of calcineurin inhibitors on POD 3. AKI was strongly associated with mGFR at 12 and 36 months. Kidney and liver graft biopsies showed only minor histological changes. Donor and recipient body mass index, recipient age, model of end-stage liver disease score, diagnosis of hepatitis C, donor cause of death, as well as bleeding, transfusions and duration of the anhepatic phase correlated with early kidney dysfunction.

CONCLUSION

The greatest decline in mGFR was evident within 10 days and AKI within hours of LT, irrespective of baseline mGFR and before introduction of calcineurin inhibitors. Very early post-LT kidney injury has substantial consequences for long-term kidney function.

Aging aggravates hepatic ischemia-reperfusion injury in mice by impairing mitophagy with the involvement of the EIF2α-parkin pathway

Hepatic ischemia-reperfusion (I/R) injury fundamentally influences the performance of aged liver grafts. The significance of mitophagy in the age dependence of sensitivity to I/R injury remains poorly understood. Here, we show that aging aggravated hepatic I/R injury with decreased mitophagy in mice. The enhancement of mitophagy resulted in significant protection against hepatic I/R injury. Parkin, an E3 ubiquitin ligase, was found depleted by I/R in aged livers. In oxygen-glucose deprivation reperfusion (OGD-Rep.)-treated L02 cells, parkin silencing impaired mitophagy and aggravated cell damage through a relative large mitochondrial membrane potential transition. The phosphorylation of the endoplasmic reticulum stress response protein EIF2α, which was also reduced in the aged liver, induced parkin expression both in vivo and vitro. Forty-six hepatic biopsy specimens from liver graft were collected 2 hours after complete revascularization, followed by immunohistochemical analyses. Parkin expression was negatively correlated to donor age and the peak level of aspartate aminotransferase within first week after liver transplantation. Our translational study demonstrates that aging aggravated hepatic I/R injury by impairing the age-dependent mitophagy function via an insufficient parkin expression and identifies a new strategy to evaluate the capacity of an aged liver graft in the process of I/R through the parkin expression.

Repressor and activator protein accelerates hepatic ischemia reperfusion injury by promoting neutrophil inflammatory response

Repressor and activator protein (Rap1) directly regulates nuclear factor-κB (NF-κB) dependent signaling, which contributes to hepatic IRI. We here intended to investigate the effect of Rap1 in hepatic ischemia reperfusion injury (IRI) and to explore the underlying mechanisms. The association of Rap1 expression with hepatic inflammatory response were investigated in both human and rat liver transplantation. The effect of Rap1 in hepatic IRI was studied in Rap1 knockout mice IRI model in vivo and primary cells in vitro. Our results showed that over expression of Rap1 was associated with severe liver graft inflammatory response, especially in living donor liver transplantation. The results were also validated in rat liver transplantation model. In mice hepatic IRI model, the knockout of Rap1 reduced hepatic damage and hepatic inflammatory response. In primary cells, the knockout of Rap1 suppressed neutrophils migration activity and adhesion in response to liver sinusoidal endothelial cells through down-regulating neutrophils F-Actin expression and CXCL2/CXCR2 pathway. In addition, the knockout of Rap1 also decreased production of pro-inflammatory cytokines/chemokines in primary neutrophils and neutrophils-induced hepatocyte damage. In conclusion, Rap1 may induce hepatic IRI through promoting neutrophils inflammatory response. Rap1 may be the potential therapeutic target of attenuating hepatic IRI.

Curcumin protects against hepatic ischemia/reperfusion induced injury through inhibiting TLR4/NF-κB pathway

The TLR4/NF-κB pathway had important roles in hepatic ischemia/reperfusion (I/R) injury. In this study, we reported a protective effect of curcumin against hepatic I/R injury via TLR4/NF-κB pathway. Curcumin significantly inhibited cell apoptosis, and decreased levels of LDH and production of TNF-a, IL-1b, and IL-6 in the cell supernatant. In addition, curcumin ameliorated elevated TLR4 and NF-κB caused by hypoxia/reoxygenation stimulation in BRL-3A cells. In vivo assays revealed that curcumin reduce levels of ALT and AST, and reversed TLR4/NF-κB signaling pathway caused by hepatic I/R stimulation in liver tissues. These results suggested that curcumin ameliorates hepatic I/R injury, which may be mediated in part via the TLR4/NF-κB signaling pathway.

Mechanism of Hepatocyte Apoptosis

Hepatocyte apoptosis plays important roles in both the removal of external microorganisms and the occurrence and development of liver diseases. Different conditions, such as virus infection, fatty liver disease, hepatic ischemia reperfusion, and drug-induced liver injury, are accompanied by hepatocyte apoptosis. This review summarizes recent research on the mechanism of hepatocyte apoptosis involving the classical extrinsic and intrinsic apoptotic pathways, endoplasmic reticulum stress, and oxidative stress-induced apoptosis. We emphasized the major causes of apoptosis according to the characteristics of different liver diseases. Several concerns regarding future research and clinical application are also raised.

Protective role of silent information regulator 1 against hepatic ischemia: effects on oxidative stress injury, inflammatory response, and MAPKs

OBJECTIVE

Previous studies have verified that silent information regulator 1 (SIRT1), a class III histone deacetylase, protects against ischemia reperfusion (IR) injury (IRI) in some organs. In this study, we examined whether SIRT1 could protect against hepatic IRI and explored the potential mechanisms.

RESEARCH DESIGN AND METHODS

We examined whether SIRT1 could protect against hepatic IRI in vivo and in vitro using hepatic-specific SIRT1(-/-) mice, SIRT1 siRNA-transfected hepatocytes and SIRT1(+/+) hepatocytes.

RESULTS

The expression and activity of SIRT1 were significantly reduced during reperfusion compared with that observed in the control group. Hepatic-specific SIRT1(-/-) mice exhibited significant increase of hepatic damage markers and augment of oxidative stress and inflammatory response compared with control mice. In vitro studies demonstrated similar results. Furthermore, SIRT1 upregulation protects against hepatic IRI, through the overexpression of p-JNK, p-p38MAPK, and p-ERK. The protection of SIRT1 can be effectively reversed by the inhibitors of p38MAPK, JNK, and ERK.

CONCLUSION

The activation of SIRT1 significantly inhibits the oxidative stress and inflammatory response during hepatic IRI, which can be developed as a novel method to protect against hepatic IRI.

Paeoniflorin attenuates hepatic ischemia/reperfusion injury via anti-oxidative, anti-inflammatory and anti-apoptotic pathways

During liver surgery, hepatic blood flow needs to be blocked in order to reduce bleeding, which inevitably results in hepatic ischemia/reperfusion injury (HI/R). Paeoniflorin (PF) is the main active ingredient of the traditional Chinese herbal medicine peony, which has been shown to exert anti-oxidative and anti-apoptotic properties. In the present study, a mouse model of HI/R was generated by clamping the hepatoportal vein, hepatic artery, and hepatic duct of BALB/c mice with a vascular clamp for 30 min, followed by reperfusion for 6 h under anesthesia. Six mice in the three PF treatment groups (5, 10 and 20 mg/kg) were then injected with PF, via the tail vein. A sham group, consisting of six mice that did not undergo the procedure, and a vehicle group, consisting of 6 mice that underwent the procedure but subsequently received injections of physiological saline only, were used as controls. Liver injury was indicated by serum levels of the enzymes alanine transaminase (ALT) and aspartate transaminase (AST). The activities of oxidative stress biomarkers, including superoxide dismutase (SOD), glutathione (GSH), glutathione peroxidase (GSH-PX) and malondialdehyde (MDA), were also measured. Furthermore, the activity of caspase-3 was analyzed in hepatic tissue using a commercial kit. Treatment with PF significantly attenuated HI/R injury histologically, as compared with the vehicle group. In addition, significant reductions in the serum levels of ALT and AST were observed in the PF-treated ischemic mice. Furthermore, treatment with PF enhanced the activities of hepatic tissue SOD, GSH and GSH-PX, but decreased the MDA content. Treatment of ischemic mice with PF markedly reduced the expression levels of inflammatory mediators, including nuclear factor-κB, tumor necrosis factor-α, interleukin (IL)-6, and IL-1β, and decreased the HI/R injury-induced expression of caspase-3. The results of the present study suggest that PF attenuates the HI/R injury of mice via anti-oxidative, anti-inflammatory and anti-apoptotic activities.

Effect of remote ischemic preconditioning on hepatic microcirculation and function in a rat model of hepatic ischemia reperfusion injury

BACKGROUND

Liver transplantation involves a period of ischemia and reperfusion to the graft which leads to primary non-function and dysfunction of the liver in 5-10% of cases. Remote ischemic preconditioning (RIPC) has been shown to reduce ischemia reperfusion injury (IRI) injury to the liver and increase hepatic blood flow. We hypothesized that RIPC may directly modulate hepatic microcirculation and have investigated this using intravital microscopy.

METHODS

A rat model of liver IRI was used with 45 min of partial hepatic ischemia (70%) followed by 3 h of reperfusion. Four groups of animals (Sham, IRI, RIPC+IRI, RIPC+Sham) were studied (n= 6, each group). Intravital microscopy was used to measure red blood cell (RBC) velocity, sinusoidal perfusion, sinusoidal flow and sinusoidal diameter. Neutrophil adhesion was assessed by rhodamine labeling of neutrophils and cell death using propidium iodide.

RESULTS

RIPC reduced the effects of IRI by significantly increasing red blood cell velocity, sinusoidal flow and sinusoidal perfusion along with decreased neutrophil adhesion and cell death.

CONCLUSIONS

Using intravital microscopy, this study demonstrates that RIPC modulates hepatic microcirculation to reduce the effects of IRI. HO-1 may have a key role in the modulation of hepatic microcirculation and endothelial function.

Role of P-selectin and anti-P-selectin monoclonal antibody in apoptosis during hepatic/renal ischemia-reperfusion injury

AIM: To evaluale the potential role of P-selectin and anti-P-selectin monoclonal antibody (mAb) in apoptosis during -hepatic/renal ischemia-reperfusion injury.

METHODS: Plasma P-selectin level, hepatic/renal P-selectin expression and cell apoptosis were detected in rat model of hepatic/renal ischemia-reperfusion injury. ELISA, immunohist-ochemistry and TUNEL were used. Some ischemia-reperfusion rats were treated with anti-P-selectin mAb.

RESULTS: Hepatic/renal function insuffic-iency, up-regul ated expression of P-selectin in plasma and hepatic/renal tissue, hepatic/renal histopathological damages and cell apoptosis were found in rats with hepatic/renal ischemia-reperfusion injury, while these changes became less conspicuous in animals treated with anti-P-selectin mAb.

CONCLUSION: P-selectin might mediate neutrophil infiltration and cell apoptosis and contribute to hepatic/renal ischemia-reperfusion injury, anti-P-selectin mAb might be an efficient approach for the prevention and treatment of hepatic/renal ischemia-reperfusion injury.