Reactive oxygen species during ischemia-reflow injury in isolated perfused rat liver

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.

Intraoperative High Fraction of Inspiratory Oxygen is Independently Associated with Worse Outcome After Living-Donor Liver Transplantation: A Retrospective Study

Background

Ischemia and reperfusion injury is an important factor that determines graft function after liver transplantation, and oxygen plays a crucial role in this process. However, the relationship between the intraoperative high fraction of inspiratory oxygen (FiO₂) and living-donor-liver-transplantation (LDLT) outcome remains unclear.

Patients and Methods

A total of 199 primary adult-to-adult LDLT cases in Kyoto University Hospital between January 2010 and December 2017 were enrolled in this study. The intraoperative FiO₂ was averaged using the total amount of intraoperative oxygen and air and defined as the calculated FiO₂ (cFiO₂). The cutoff value of cFiO₂ was set at 0.5.

Results

Between the cFiO₂ <0.5 (n = 156) and ≥0.5 group (n = 43), preoperative recipients’ background, donor factors, and intraoperative parameters were almost comparable. Postoperatively, the cFiO₂ ≥0.5 group showed a higher early allograft dysfunction (EAD) rate (P = 0.049) and worse overall graft survival (P = 0.036) than the cFiO₂ <0.5 group. Although the cFiO₂ ≥0.5 was not an independent risk factor for EAD in multivariable analysis (OR 2.038, 95%CI 0.992–4.186, P = 0.053), it was an independent risk factor for overall graft survival after LDLT (HR 1.897, 95%CI 1.007–3.432, P = 0.048).

Conclusion

The results of this study suggest that intraoperative high FiO₂ may be associated with worse graft survival after LDLT. Avoiding higher intraoperative FiO₂ may be beneficial for LDLT recipients.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00268-022-06544-7.

Mitochondrial Dysfunction and Oxidative Stress in Liver Transplantation and Underlying Diseases: New Insights and Therapeutics

Mitochondria are essential organelles for cellular energy and metabolism. Like with any organ, the liver highly depends on the function of these cellular powerhouses. Hepatotoxic insults often lead to an impairment of mitochondrial activity and an increase in oxidative stress, thereby compromising the metabolic and synthetic functions. Mitochondria play a critical role in ATP synthesis and the production or scavenging of free radicals. Mitochondria orchestrate many cellular signaling pathways involved in the regulation of cell death, metabolism, cell division, and progenitor cell differentiation. Mitochondrial dysfunction and oxidative stress are closely associated with ischemia-reperfusion injury during organ transplantation and with different liver diseases, including cholestasis, steatosis, viral hepatitis, and drug-induced liver injury. To develop novel mitochondria-targeting therapies or interventions, a better understanding of mitochondrial dysfunction and oxidative stress in hepatic pathogenesis is very much needed. Therapies targeting mitochondria impairment and oxidative imbalance in liver diseases have been extensively studied in preclinical and clinical research. In this review, we provide an overview of how oxidative stress and mitochondrial dysfunction affect liver diseases and liver transplantation. Furthermore, we summarize recent developments of antioxidant and mitochondria-targeted interventions.

Hydrogen regulates the M1/M2 polarization of alveolar macrophages in a rat model of chronic obstructive pulmonary disease

OBJECTIVE

Chronic obstructive pulmonary disease (COPD) is a respiratory disease with high morbidity and mortality worldwide, so far there is no ideal treatment method. Previous studies have shown that hydrogen (H₂) is involved in the treatment of COPD as an antioxidant. In this study, the effect of H₂ on M1/M2 polarization of alveolar macrophages in COPD rats was observed, and its anti-inflammatory mechanism was further elucidated. Methods: Twenty-four Sprague-Dawley rats were randomly divided into three groups including the control, COPD and H₂ group. A rat model of COPD was established by cigarette exposure combined with lipopolysaccharide (LPS) induction. H₂ therapy was administered 2 hours per day for 14 days. Lung function and pathology were assessed. The levels of interleukin (IL)-6, tumor necrosis factor (TNF)-α, transforming growth factor (TGF)-β1 and IL-10 in bronchoalveolar lavage fluid (BALF) and lung tissue were measured by enzyme-linked immunosorbent assay. The mRNA, protein expression and immunoreactivity of inducible nitric oxide synthase (iNOS) and arginase (Arg)-1 in lung were observed by quantitative real-time PCR, western blot and immunohistochemistry. Results: Compared with the control rats, there were a significant decline in lung function, a marked inflammatory infiltration and pulmonary parenchymal remodeling and the increases of IL-6, TNF-α and TGF-β1 levels in BALF and lung tissue, but a lower expression of IL-10 in COPD rats. The iNOS mRNA and protein expression, as well as its optical density (OD), were increased significantly in lung tissue, while those of Arg-1 decreased significantly. H₂ treatment improved the lung function and the parenchymal inflammation, reversed the increased levels of IL-6, TNF-α and TGF-β1, and the lower IL-10. Meanwhile, H₂ also down-regulated the expression of iNOS, but up-regulated expression of Arg-1 in lung tissue. Conclusion: H₂ reduces inflammation in the lung of COPD, which may be related to its inhibition of M1 type polarization and activation of M2 type polarization of alveolar macrophage.

Ferroptosis and Acetaminophen Hepatotoxicity: Are We Going Down Another Rabbit Hole?

Acetaminophen (APAP) hepatotoxicity is the most frequent cause of acute liver failure in the US. The mechanisms of APAP-induced liver injury have been under extensive investigations for decades, and many key events of this necrotic cell death are known today. Initially, two opposing hypotheses for cell death were proposed: reactive metabolite and protein adduct formation versus reactive oxygen and lipid peroxidation (LPO). In the end, both mechanisms were reconciled, and it is now generally accepted that the toxicity starts with formation of reactive metabolites that, after glutathione depletion, bind to cellular proteins, especially on mitochondria. This results in a mitochondrial oxidant stress, which requires amplification through a mitogen-activated protein kinase cascade, leading ultimately to enough reactive oxygen and peroxynitrite formation to trigger the mitochondrial membrane permeability transition and cell death. However, the earlier rejected LPO hypothesis seems to make a comeback recently under a different name: ferroptosis. Therefore, the objective of this review was to critically evaluate the available information about intracellular signaling mechanisms of APAP-induced cell death and those of ferroptosis. Under pathophysiologically relevant conditions, there is no evidence for quantitatively enough LPO to cause cell death, and thus APAP hepatotoxicity is not caused by ferroptosis. However, the role of mitochondria-localized minor LPO remains to be further investigated.

Melatonin and its protective role in attenuating warm or cold hepatic ischaemia/reperfusion injury

Although the liver is the only organ with regenerative capacity, various injury factors induce irreversible liver dysfunction and end‐stage liver disease. Liver resection and liver transplantation (LT) are effective treatments for individuals with liver failure, liver cirrhosis and liver cancers. The remnant or transplanted liver tissues will undergo hepatic ischaemia/reperfusion (IR), which leads to oxidative stress, inflammation, immune injury and liver damage. Moreover, systemic ischaemia induced by trauma, stroke, myocardial ischaemia, haemorrhagic shock and other injury factors also induces liver ischaemia/reperfusion injury (IRI) in individuals. Hepatic IRI can be divided into warm IRI, which is induced by liver surgery and systemic ischaemia, and cold IRI, which is induced by LT. Multiple studies have shown that melatonin (MT) acts as an endogenous free radical scavenger with antioxidant capacity and is also able to attenuate hepatic IRI via its anti‐inflammatory and antiapoptotic capacities. In this review, we discuss the potential mechanisms and current strategies of MT administration in liver surgery for protecting against warm or cold hepatic IRI. We highlight strategies to improve the efficacy and safety of MT for attenuating hepatic IRI in different conditions. After the potential mechanisms underlying the interactions between MT and other important cellular processes during hepatic IR are clarified, more opportunities will be available to use MT to treat liver diseases in the future.

Evaluation with endothelial nitric oxide synthase (eNOS) immunoreactivity of the protective role of astaxanthin on hepatorenal injury of remote organs caused by ischaemia reperfusion of the lower extremities

Introduction

Ischemia and following reperfusion triggers local and systemic damage with the involvement of free oxygen radicals and inflammatory mediators. Although blood flow saves extremity from necrosis,multi organ dysfunction may progress and cause death of the patient.

Aim

The study aims to examine the effect of astaxanthin (AST) on the prevention of remote tissue injury resulting from lower extremity ischaemia–reperfusion (I/R). To elucidate the potential hepatoprotective and renoprotective effects of AST, in addition to histopathological findings, the intrahepatic and intrarenal kinetics of endothelial nitric oxide synthase (eNOS) during I/R were determined by using the immunohistochemical method.

Material and methods

Twenty-eight male Wistar albino rats were divided into four groups. For the control group, only the anaesthesia procedure (2 h) was conducted without I/R. In the I/R group, 2 h of reperfusion was conducted following ischaemia under anaesthesia. For the I/R group + AST, 7 days prior to ischaemia, 125 mg/kg AST was given with gavage, and 2 h of ischaemia and 2 h of reperfusion were conducted under anaesthesia. Following necropsy, liver and kidney tissue samples were fixed in 10% buffered formalin for 48 h for histopathological and immunohistochemical investigation.

Results

The histological analysis revealed that severe I/R hepatorenal injury such as inflammatory cell infiltration, dilatation in sinusoids and lumen of tubuli, congestion in glomerular capillaries, degeneration in hepatocyte and epithelial cells of tubuli, and necrosis was ameliorated by AST. Immunohistochemical studies showed that the I/R-induced elevation in eNOS expression was reduced by AST treatment.

Conclusions

In the case of acute lower extremity I/R, AST decreased the ischaemic injury in liver and renal tissues by protecting the microcirculation and providing a cytoprotective effect with vasodilatation.

Hypericum Humifusum Leaves Attenuates Hepatic Ischemia-Reperfusion Injury in a Rat Model

INTRODUCTION

Effective prevention strategies require specific actions during the different phases of ischemia-reperfusion (I-R) injury. The objective of our study is to evaluate the effect of aqueous extract of Hypericum humifusum leaves (HHL) on liver I-R model in Rat.

MATERIAL AND METHODS

Animals were subjected to 90 min of hepatic ischemia followed by reperfusion (120 min). HHL extract (25 mg/mL/kg) was injected 15 min before reperfusion. To evaluate the effect of HHL extract on I-R, we have monitored transaminases levels, Malondialdehyde (MDA) concentration, histological lesions (apoptosis and necrosis) and compared the results to a reference oxidant vitamin E.

RESULTS

The determination of total phenol extracts of HHL was 59.91 ± 0.35 mg of Gallic Acid/g dry plant material with higher antioxidant activity (91.73% ± 1.67) compared to vitamin E (87.42%). Using aqueous extract of HHL, we noted a significant decrease of AST and ALT [1129 UI (585/1995) and 768 UI (335/1375)] compared to no-treated group [5,585.5 UI (5,035/12,070) and 8,099.5 UI (5,040/12,326)] as a decrease in MDA content [85.7% protection (50.9/91.5)]. HHL extract reduce the damage induced by I-R of 48.7% (27/48.7) and 96.1% (95.7/96.5) for necrosis and apoptosis lesions respectively.

CONCLUSION

HHL aqueous extract have potential to protect liver from the damage effect induced by I-R better than vitamin E solution.

Loss of ATF3 exacerbates liver damage through the activation of mTOR/p70S6K/ HIF-1α signaling pathway in liver inflammatory injury

Activating transcription factor 3 (ATF3) is a stress-induced transcription factor that plays important roles in regulating immune and metabolic homeostasis. Activation of the mechanistic target of rapamycin (mTOR) and hypoxia-inducible factor (HIF) transcription factors are crucial for the regulation of immune cell function. Here, we investigated the mechanism by which the ATF3/mTOR/HIF-1 axis regulates immune responses in a liver ischemia/reperfusion injury (IRI) model. Deletion of ATF3 exacerbated liver damage, as evidenced by increased levels of serum ALT, intrahepatic macrophage/neutrophil trafficking, hepatocellular apoptosis, and the upregulation of pro-inflammatory mediators. ATF3 deficiency promoted mTOR and p70S6K phosphorylation, activated high mobility group box 1 (HMGB1) and TLR4, inhibited prolyl-hydroxylase 1 (PHD1), and increased HIF-1α activity, leading to Foxp3 downregulation and RORγt and IL-17A upregulation in IRI livers. Blocking mTOR or p70S6K in ATF3 knockout (KO) mice or bone marrow-derived macrophages (BMMs) downregulated HMGB1, TLR4, and HIF-1α and upregulated PHD1, increasing Foxp3 and decreasing IL-17A levels in vitro. Silencing of HIF-1α in ATF3 KO mice ameliorated IRI-induced liver damage in parallel with the downregulation of IL-17A in ATF3-deficient mice. These findings demonstrated that ATF3 deficiency activated mTOR/p70S6K/HIF-1α signaling, which was crucial for the modulation of TLR4-driven inflammatory responses and T cell development. The present study provides potential therapeutic targets for the treatment of liver IRI followed by liver transplantation.

5-N-Carboxyimino-6-N-chloroaminopyrimidine-2,4(3H)-dione as a hypochlorite-specific oxidation product of uric acid

Although uric acid is known to react with many reactive oxygen species, its specific oxidation products have not been fully characterized. We now report that 5-N-carboxyimino-6-N-chloroaminopyrimidine-2,4(3H)-dione (CCPD) is a hypochlorite (ClO^-)-specific oxidation product of uric acid. The yield of CCPD was 40-70% regardless of the rate of mixing of ClO^- with uric acid. A previously reported product, allantoin (AL), was a minor product. Its yield (0-20%) decreased with decreasing rate of mixing of ClO^- with uric acid, indicating that allantoin is less important in vivo. Kinetic studies revealed that the formation of CCPD required two molecules of ClO^- per uric acid reacted. The identity of CCPD was determined from its molecular formula (C₅H₃ClN₄O₄) measured by LC/time-of-flight mass spectrometry and a plausible reaction mechanism. This assumption was verified by the fact that all mass fragments (m/z -173, -138, -113, and -110) fit with the chemical structure of CCPD and its tautomers. Isolated CCPD was stable at pH 6.0-8.0 at 37°C for at least 6 h. The above results and the fact that uric acid is widely distributed in the human body at relatively high concentrations indicate that CCPD is a good marker of ClO^- generation in vivo.

Oxidative Stress and Acute Hepatic Injury

Reactive oxygen species have long been implicated in the pathophysiology of acute liver injury. However, the translation of these findings to the clinic and the development of therapeutic agents have been slow mainly due to the poor mechanistic understanding of the pathophysiology and the many indirect approaches used to characterize the role of oxidant stress in liver injury. The current review discusses in depth the sources of reactive oxygen, the oxidants involved and the impact of this oxidant stress in the mechanism of cell death in 3 different clinically relevant acute liver injury models.

Parabanic acid is the singlet oxygen specific oxidation product of uric acid

Uric acid quenches singlet oxygen physically or reacts with it, but the oxidation product has not been previously characterized. The present study determined that the product is parabanic acid, which was confirmed by LC/TOFMS analysis. Parabanic acid was stable at acidic pH (<5.0), but hydrolyzed to oxaluric acid at neutral or alkaline pH. The total yields of parabanic acid and oxaluric acid based on consumed uric acid were ~100% in clean singlet oxygen production systems such as UVA irradiation of Rose Bengal and thermal decomposition of 3-(1,4-dihydro-1,4-epidioxy-4-methyl-1-naphthyl)propionic acid. However, the ratio of the amount of uric acid consumed to the total amount of singlet oxygen generated was less than 1/180, indicating that most of the singlet oxygen was physically quenched. The total yields of parabanic acid and oxaluric acid were high in the uric acid oxidation systems with hydrogen peroxide plus hypochlorite or peroxynitrite. They became less than a few percent in peroxyl radical-, hypochlorite- or peroxynitrite-induced oxidation of uric acid. These results suggest that parabanic acid could be an in vivo probe of singlet oxygen formation because of the wide distribution of uric acid in human tissues and extracellular spaces. In fact, sunlight exposure significantly increased human skin levels of parabanic acid.

Peroxiredoxin-6 Negatively Regulates Bactericidal Activity and NF-κB Activity by Interrupting TRAF6-ECSIT Complex

A TRAF6-ECSIT complex is crucial for the generation of mitochondrial reactive oxygen species (mROS) and nuclear factor-kappa B (NF-κB) activation induced by Toll-like receptor 4 (TLR4). Peroxiredoxin-6 (Prdx6) as a member of the peroxiredoxin family of antioxidant enzymes is involved in antioxidant protection and cell signaling. Here, we report on a regulatory role of Prdx6 in mROS production and NF-κB activation by TLR4. Prdx6 was translocated into the mitochondria by TLR4 stimulation and Prdx6-knockdown (Prdx6^KD) THP-1 cells had increased level of mitochondrial reactive oxygen species levels and were resistant to Salmonella typhimurium infection. Biochemical studies revealed Prdx6 interaction with the C-terminal TRAF-C domain of TRAF6, which drove translocation into the mitochondria. Interestingly, Prdx6 competitively interacted with ECSIT to TRAF6 through its C-terminal TRAF-C domain, leading to the interruption of TRAF6-ECSIT interaction. The inhibitory effect was critically implicated in the activation of NF-κB induced by TLR4. Overexpression of Prdx6 led to the inhibition of NF-κB induced by TLR4, whereas Prdx6^KD THP-1 cells displayed enhanced production of pro-inflammatory cytokines including interleukin-6 and -1β, and the up-regulation of NF-κB-dependent genes induced by TLR4 stimulation. Taken together, the data demonstrate that Prdx6 interrupts the formation of TRAF6-ECSIT complex induced by TLR4 stimulation, leading to suppression of bactericidal activity because of inhibited mROS production in mitochondria and the inhibition of NF-κB activation in the cytoplasm.

The impact of sterile inflammation in acute liver injury

BACKGROUND

The liver has a number of functions in innate immunity. These functions predispose the liver to innate immune-mediated liver injury when inflammation goes unchecked. Significant progress has been made in the last 25 years on sterile inflammatory liver injury in a number of models; however, a great deal of controversy and many questions about the nature of sterile inflammation still exist.

AIM

The goal of this article is to review sterile inflammatory liver injury using both a basic approach to what constitutes the inflammatory injury, and through examination of current models of liver injury and inflammation. This information will be tied to human patient conditions when appropriate.

RELEVANCE FOR PATIENTS

Inflammation is one of the most critical factors for managing in-patient liver disease in a number of scenarios. More information is needed for both scientists and clinicians to develop rational treatments.

Kupffer cells-dependent inflammation in the injured liver increases recruitment of mesenchymal stem cells in aging mice

Mesenchymal stem cells (MSCs) repair tissue injury and may be used to treat immune associated diseases. In carbon tetrachloride (CCl4)-induced liver injury murine model, we administered MSCs. When MSCs were transmitted to young and old mice with liver injury, more MSCs were recruited in old mice. In old mice, inflammation, characterized by TNF-α and IL-6, was increased due to hyper-activation and hyper-function of Kupffer cells. Blocking Kupffer cells decreased MSCs migration in old mice. In vitro, Kupffer cells isolated from old mice secreted more inflammatory cytokines and chemokines. Thus, hyper-activation of Kupffer cells in old mice increased recruitment of MSCs after their therapeutic administration.

Leveraging oxidative stress questions in vivo: Implications and limitations

The elegance of Helmut Sies' original definition of oxidative stress belies the complexity of the reactions that are potentially involved. This is by no means a criticism of the author, but rather how the words have been used to oversimplify the concept by some. Reactive oxygen and nitrogen species (ROS and RNS, respectively) can be products of a myriad of events within the living body. Indeed, it is now understood that ROS/RNS are critical for normal cellular metabolism and have beneficial effects (e.g., cytotoxicity against invading bacteria). A general problem of studying prooxidants in vivo is that, due to their inherent reactivity, they generally cannot be measured directly. This indirect detection of 'footprints' leaves a very large black box that we are to this day only beginning to understand. This manuscript will summarize some considerations that are of utmost importance when translating oxidative stress into in vivo research. Helmut has been a key thought leader, researcher and mentor whose contributions to this field are immeasurable.

Melatonin pretreatment enhances the therapeutic effects of exogenous mitochondria against hepatic ischemia-reperfusion injury in rats through suppression of mitochondrial permeability transition

We tested the hypothesis that melatonin (Mel) enhances exogenous mitochondria (Mito) treatment against rodent hepatic ischemia-reperfusion (IR) injury. In vitro study utilized three groups of hepatocytes (i.e. nontreatment, menadione, and menadione-melatonin treatment, 4.0 × 10(5) each), while in vivo study used adult male Sprague Dawley rats (n = 40) equally divided into sham-control (SC), IR (60-min left-lobe ischemia + 72-hr reperfusion), IR-Mel (melatonin at 30 min/6/8 hr after reperfusion), IR-Mito (mitochondria 15,000 μg/rat 30 min after reperfusion), and IR-Mel-Mito. Following menadione treatment in vitro, oxidative stress (NOX-1/NOX-2/oxidized protein), apoptotic (cleaved caspase-3/PARP), DNA damage (γ-H2AX/CD90/XRCC1), mitochondria damage (cytosolic cytochrome c) biomarkers, and mitochondrial permeability transition were found to be lower, whereas mitochondrial cytochrome c were found to be higher in hepatocytes with melatonin treatment compared to those without (all P < 0.001). In vivo study demonstrated highest liver injury score and serum AST in IR group, but lowest in SC group and higher in IR-Mito group than that in groups IR-Mel and IR-Mel-Mito, and higher in IR-Mel group than that in IR-Mel-Mito group after 72-hr reperfusion (all P < 0.003). Protein expressions of inflammatory (TNF-α/NF-κB/IL-1β/MMP-9), oxidative stress (NOX-1/NOX-2/oxidized protein), apoptotic (caspase-3/PARP/Bax), and mitochondria damage (cytosolic cytochrome c) biomarkers displayed an identical pattern, whereas mitochondria integrity marker (mitochondrial cytochrome c) showed an opposite pattern compared to that of liver injury score (all P < 0.001) among five groups. Microscopically, expressions of apoptotic nuclei, inflammatory (MPO(+) /CD68(+) /CD14(+) cells), and DNA damage (γ-H2AX(+) cells) biomarkers exhibited an identical pattern compared to that of liver injury score (all P < 0.001) among five groups. Melatonin-supported mitochondria treatment offered an additional benefit of alleviating hepatic IR injury.

Optimal Timing for Venous Systemic Oxygen Persufflation Supplemented with Nitric Oxide Gas in Cold-Stored, Warm Ischemia-Damaged Experimental Liver Grafts

Background/Aim: Worldwide shortage of donor organs has increased the use of donation after cardiac death (DCD). The aim of this study was to analyze the best time point for venous systemic oxygen persufflation (VSOP) supplemented with nitric oxide (NO) gas during the 1st and 24th hour of cold storage (CS) in warm ischemia (WI)-damaged experimental liver grafts. Materials and Methods: Liver grafts (n = 5) were retrieved after 30 min of WI induced by cardiac arrest and CS in histidine-tryptophan-ketoglutarate solution at 4°C. The 1st hour group was immediately persufflated with a VSOP plus NO (VSOP+NO) mixture for 1 h followed by 23 h of static CS (DCD+NO 1st hour). The 24th hour group entailed CS for 23 h followed by 1 h of VSOP+NO persufflation (DCD+NO 24th hour). CS livers without WI but with VSOP served as controls. CS livers with WI represented the fourth group (DCD). Viability of the liver grafts was assessed by normothermic isolated reperfusion for 45 min with oxygenated Krebs-Henseleit buffer. Results: Data are presented as mean ± SEM (control vs. DCD vs. DCD+NO 1st hour vs. DCD+NO 24th hour). After 45 min of reperfusion, the DCD+NO 1st hour group showed significantly lower aspartate aminotransferase (13.4 ± 5.3, 63.2 ± 17.3, 25.6 ± 3.9, and 82.8 ± 27.3 U/l) and lactate dehydrogenase levels (289.4 ± 41.2, 2,139.4 ± 542.7, 577.2 ± 117.2, and 2,429 ± 221.6 U/l). Malondialdehyde levels were significantly abrogated (1.0 ± 0.3, 2.7 ± 1, 1.0 ± 0, and 3.9 ± 1.2 nmol/ml). Significantly higher levels of portal venous pressure were recorded in the DCD+NO 24th hour group (12.0 ± 1, 21.2 ± 3.1, 16.1 ± 1, and 23.2 ± 3.5 mm Hg). NO levels were recorded after 5 min of reperfusion (1.42 ± 0.17, 1.8 ± 0.2, 2.7 ± 0.2, and 2.6 ± 0.1 μmol/l). Bile production levels showed no statistical significance (23.2 ± 3.8, 27.3 ± 1.8, 43.5 ± 18, and 31 ± 2.5 μl/45 min). Conclusion: Our results present the beneficial effects of NO combined with VSOP during the 1st hour of CS of WI-damaged experimental liver grafts.

Effect of breviscapine against hepatic ischemia reperfusion injury

BACKGROUND

Breviscapine is an active ingredient extracted from traditional Chinese medicine Erigeron breviscapus. The purpose of this study was to investigate the effect of breviscapine injection on hepatic ischemia and/or reperfusion injury.

METHODS

Forty rats were randomly divided into five groups (n = 8): Sham group, Ischemia reperfusion 1 (I/R1) + normal saline (NS) group, I/R1 + breviscapine (Bre), I/R2 + NS group, and I/R2 + Bre group. Group1 and group2 represent ischemia time for 10 min and 30 min, respectively. Breviscapine or normal saline was administered to rats (single dose of 10 mg/Kg, intravenously) 30 min before hepatic ischemia. Serum transaminases, histopathologic changes, malondialdehyde (MDA), and superoxide dismutase (SOD) in liver tissues were evaluated. The expression level of mitochondrial fusion 2 (Mfn2) was also investigated.

RESULTS

After 24-h reperfusion, based on the histopathologic analysis, compared with NS control group, the liver function was improved in breviscapine group. Liver enzymes aspartate and alanine aminotransferase levels were significantly lower in the I/R + Bre group, when compared with the I/R + NS group. Pretreatment with breviscapine reduced MDA level (P < 0.05) and increased SOD activity significantly in I/R + Bre compared with I/R + NS group. Western blot and RT-q polymerase chain reaction showed that Mfn2 was significantly downregulated in breviscapine preconditioning group as compared to normal saline control group.

CONCLUSIONS

Breviscapine preconditioning attenuates liver ischemia reperfusion injury via inhibiting liver oxidative stress reaction. The protective mechanism probably inhibits Mfn2 protein and mRNA expression.

Anti-CD163-dexamethasone protects against apoptosis after ischemia/reperfusion injuries in the rat liver

Aim

The Pringle maneuver is a way to reduce blood loss during liver surgery. However, this may result in ischemia/reperfusion injury in the development of which Kupffer cells play a central role. Corticosteroids are known to have anti-inflammatory effects. Our aim was to investigate whether a conjugate of dexamethasone and antibody against the CD163 macrophage cell surface receptor could reduce ischemia/reperfusion injury in the rat liver.

Methods

Thirty-six male Wistar rats were used for the experiments. Animals were randomly divided into four groups of eight receiving anti-CD163-dexamethasone, high dose dexamethasone, low dose dexamethasone or placebo intravenously 18 h before laparotomy with subsequent 60 min of liver ischemia. After reperfusion for 24 h the animals had their liver removed. Bloods were drawn 30 min and 24 h post ischemia induction. Liver cell apoptosis and necrosis were analyzed by stereological quantification.

Results

After 24 h' reperfusion, the fraction of cell in non-necrotic tissues exhibiting apoptotic profiles was significantly lower in the high dose dexamethasone (p = 0.03) and anti-CD163-dex (p = 0.03) groups compared with the low dose dexamethasone and placebo groups. There was no difference in necrotic cell volume between groups. After 30 min of reperfusion, levels of haptoglobin were significantly higher in the anti-CD163-dex and high dose dexamethasone groups. Alanine aminotransferase and alkaline phosphatase were significantly higher in the high dose dexamethasone group compared to controls after 24 h' reperfusion.

Conclusions

We show that pharmacological preconditioning with anti-CD163-dex and high dose dexamethasone reduces the number of apoptotic cells following ischemia/reperfusion injury.

•

We investigated the effect of pharmacologic preconditioning with HDD, LDD and anti-CD163-dex on ischemia/reperfusion injury.

•

Liver cell apoptosis and necrosis were analyzed by stereological quantification.

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Anti-CD163-dex and high dose dexamethasone reduces the number of apoptotic cells following ischemia/reperfusion injury.

Unfeasible experimental model of normothermic hepatic ischemia and reperfusion in rats using the Pringle maneuver

BACKGROUND

The negative result of a research does not always indicate failure, and when the data do not permit a proper conclusion, or are contrary to the initial project, should not simply be discarded and archived.

AIM

To report failure after performing experimental model of liver ischemia and reperfusion normothermic, continuous or intermittent, in small animals aiming at the study of biochemical and histological parameters after postoperative recovery.

METHODS

Fifteen Wistar rats were divided into three groups of five animals each; all underwent surgery, the abdomen was sutured after the proposed procedures for each group and the animals were observed for 6 h or until they died, and then were reoperated. In Group 1, control (sham-operated): dissection of the hepatic hilum was performed; in Group 2: clamping of the hepatic hilum for 30 m; in Group 3: clamping of the hepatic hilum for 15 m, reperfusion for 5 m and another 15 m of clamping. Data from Groups 2 and 3 were compared with Student's t test.

RESULTS

All animals of Group 1 survived for 6 h. Two animals in Group 2 died before the 6 h needed to validate the experiment; two did not recover from anesthesia and one survived until the end. In Group 3, four animals died before the 6 h established and one of them survived the required time. Only one animal in Group 2 and one in Group 3 survived and were able to accomplish the study. There was no statistical significance when the results of Groups 2 and 3 were compared (p>0.05).

CONCLUSION

The death of six animals before the necessary period of observation turned the initial proposal of the experiment unfeasible.

Hypoxia activation of mitophagy and its role in disease pathogenesis

SIGNIFICANCE

Mitochondria utilize most of the oxygen to produce adenosine triphosphate via electron transfer coupled with oxidative phosphorylation. Hypoxia undoubtedly induces reduced energy production via decreased mitochondrial metabolic activity or altered hypoxia-inducible factor-1- and peroxisome proliferator-activated receptor gamma coactivator 1-dependent mitochondrial biogenesis. Hypoxia may also activate mitophagy to selectively remove damaged or unwanted mitochondria for both mitochondrial quantity and quality control. Increasing evidence has shown that the accumulation of damaged mitochondria is a characteristic of aging and aging-related diseases, such as metabolic disorder, cancer, and neurodegenerative disease.

RECENT ADVANCES

Both receptor-dependent and PTEN-induced putative kinase 1-PARKIN-dependent mitophagy have been described. Mitophagy receptors include Atg32 in yeast, as well as NIX/BNIP3L, B-cell lymphoma 2/adenovirus E1B 19-kDa-interacting protein 3 and FUN14 domain containing 1 in mammals. In response to hypoxia or mitochondrial oxidative stress, receptor-mediated mitophagy was found to be activated via both transcriptional and post-translational modification.

CRITICAL ISSUES

To date, the molecular mechanisms by which hypoxia triggers mitophagy and by which mitophagy contributes to the pathogenesis of aging-related diseases remain to be explored.

FUTURE DIRECTIONS

An improved understanding of the regulation of mitochondrial quality may provide a strategy for treating aging-related diseases by targeting mitochondria and mitophagy pathways.

Biomarkers distinguish apoptotic and necrotic cell death during hepatic ischemia/reperfusion injury in mice

Hepatic ischemia/reperfusion (IRP) injury is a significant clinical problem during tumor-resection surgery (Pringle maneuver) and liver transplantation. However, the relative contribution of necrotic and apoptotic cell death to the overall liver injury is still controversial. To address this important issue with a standard murine model of hepatic IRP injury, plasma biomarkers of necrotic cell death such as micro-RNA 122, full-length cytokeratin 18 (FK18), and high-mobility group box 1 (HMGB1) protein and plasma biomarkers of apoptosis such as plasma caspase-3 activity and caspase-cleaved fragment of cytokeratin 18 (CK18) coupled with markers of inflammation (hyperacetylated HMGB1) were compared by histological features in hematoxylin and eosin-stained and terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick-end labeling (TUNEL)-stained liver sections. After 45 minutes of hepatic ischemia and 1 to 24 hours of reperfusion, all necrosis markers increased dramatically in plasma by 40- to >10,000-fold over the baseline with a time course similar to that of alanine aminotransferase. These data correlated well with histological characteristics of necrosis. Within the area of necrosis, most cells were TUNEL positive; initially (≤3 hours of reperfusion), the staining was restricted to nuclei, but it later spread to the cytosol, and this is characteristic of karyorrhexis during necrotic cell death. In contrast, the lack of morphological evidence of apoptotic cell death and relevant caspase-3 activity in the postischemic liver correlated well with the absence of caspase-3 activity and CK18 (except for a minor increase at 3 hours of reperfusion) in plasma. A quantitative comparison of FK18 (necrosis) and CK18 (apoptosis) release indicated dominant cell death by necrosis during IRP and only a temporary and very minor degree of apoptosis. These data suggest that the focus of future research should be the elucidation of necrotic signaling mechanisms to identify relevant targets, which may be used to attenuate hepatic IRP injury.

Role of preferential cyclooxygenase-2 inhibition by meloxicam in ischemia/reperfusion injury of the rat liver

BACKGROUND

Ischemia/reperfusion injury (IRI) is one of the major clinical problems in liver and transplant surgery. Livers subjected to warm ischemia in vivo often show a severe dysfunction and the release of numerous inflammatory cytokines and arachidonic acid metabolites. Cyclooxygenase (COX)-2 is the inducible isoform of an intracellular enzyme that converts arachidonic acid into prostaglandins. The aim of the study was to evaluate the effect of COX-2 inhibition and the role of Kupffer cells in IRI of the liver.

METHODS

Male Wistar rats [250- 280 g body weight (BW)] were anesthetized and subjected to 30-min warm ischemia of the liver (Pringle's maneuver) and 60-min reperfusion after median laparotomy. The I/R group received no additional treatment. In the COX-2 inhibitor (COX-2I) group, the animals received 1 mg/kg BW meloxicam prior to operation. Gadolinium chloride (GdCl3) (10 mg/kg BW) was given 24 h prior to operation in the GdCl3 and GdCl3 + COX-2I groups for the selective depletion of Kupffer cells. The GdCl3 + COX-2I group received both GdCl3 and meloxicam treatment prior to operation. Blood and liver samples were obtained at the end of the experiments for further investigations.

RESULTS

After 30 min of warm ischemia in vivo, severe hepatocellular damage was observed in the I/R group. These impairments could be significantly prevented by the selective COX-2 inhibition and the depletion of Kupffer cells. Alanine aminotransferase was significantly reduced upon meloxicam and GdCl3 treatment compared to the I/R group: I/R, 3,240 ± 1,262 U/l versus COX-2I, 973 ± 649 U/l, p < 0.001; I/R versus GdCl3, 1,611 ± 600 U/l, p < 0.05, and I/R versus GdCl3 + COX-2I, 1,511 ± 575 U/l, p < 0.01. Plasma levels of tumor necrosis factor alpha (TNF-α) were significantly reduced in the COX-2I treatment group compared to I/R (3.5 ± 1.5 vs. 16.3 ± 11.7 pg/ml, respectively; p < 0.05). Similarly, the amount of TxB2, a marker for COX-2 metabolism, was significantly reduced in the meloxicam treatment groups compared to the I/R group: I/R, 22,500 ± 5,210 pg/ml versus COX-2I, 1,822 ± 938 pg/ml, p < 0.001, and I/R versus GdCl3 + COX-2I, 1,530 ± 907 pg/ml, p < 0.001. All values are given as mean ± SD (n = 6).

CONCLUSION

These results suggest that the inhibition of COX-2 suppressed the initiation of an inflammatory cascade by attenuating the release of TNF-α, which is an initiator of the inflammatory reaction in hepatic IRI. Therefore, we conclude that preferential inhibition of COX-2 is a possible therapeutic approach against warm IRI of the liver.

Sivelestat sodium hydrate inhibits neutrophil migration to the vessel wall and suppresses hepatic ischemia-reperfusion injury

BACKGROUND

Sivelestat sodium hydrate (sivelestat) is a specific neutrophil elastase inhibitor that is effective in treating acute lung injury associated with systemic inflammatory response syndrome. As such, it may be useful in treating hepatic ischemia-reperfusion injury (IRI), a condition in which neutrophils transmigrate into the interstitium, leading to release of neutrophil elastase from neutrophils and consequent damage to the affected tissue, particularly in cases of hepatic failure after liver transplantation or massive liver resection.

AIMS

The purpose of this study was to examine whether treatment with sivelestat inhibits neutrophil adhesion and migration to the vessel wall and suppresses hepatic IRI.

METHODS

Whether and, if so, the extent to which sivelestat suppresses the adhesion and migration of neutrophils and reduces liver damage in hepatic IRI was examined in a human umbilical vein endothelial cell (HUVEC) model and a rat hepatic IRI model.

RESULTS

In the HUVEC model, the extent of the adhesion and migration of neutrophils stimulated by platelet-activating factor were found to be dose-dependently inhibited by sivelestat treatment (p < 0.05). In the rat model, serum liver enzyme levels were significantly lower at 12 h after reperfusion, and the number of neutrophils that had migrated to extravascular sites was significantly less in the treatment group compared to the control group (p < 0.05).

CONCLUSION

Sivelestat inhibits the adhesion and migration of neutrophils to vascular endothelium in hepatic IRI, thereby suppressing liver injury.

Hepatic ischemia and reperfusion injury and trauma: current concepts

Context

Ischemia-reperfusion injury is a fascinating topic which has drawn a lot of interest in the last several years. Hepatic ischemia reperfusion injury may occur in a variety of clinical situations. These include transplantation, liver resection, trauma, and vascular surgery.

Evidence Acquisition

The purpose of this review was to outline the molecular mechanisms underlying hepatic I/R injury and present the latest approaches, both surgical and pharmacological, regarding the prevention of it. A comprehensive electronic literature search in MEDLINE/PubMed was performed to identify relative articles published within the last 2 years.

Results

The basic mechanism of hepatic ischemia – reperfusion injury is one of blood deprivation during ischemia, followed by the return of flow during reperfusion. It involves a complex series of events, such as mitochondrial deenergization, adenosine-5'-triphosphate depletion, alterations of electrolyte homeostasis, as well as Kupffer cell activation, oxidative stress changes and upregulation of proinflammatory cytokine signaling. The great number of variable pathways, with several mediators interacting with each other, leads to a high number of candidates for potential therapeutic intervention. As far as surgical approaches are concerned, the modification of existing clamping techniques and the ischemic preconditioning are the most promising techniques till recently. In the search for novel techniques of protecting against hepatic ischemia reperfusion injury, many different strategies have been used in experimental models. The biggest part of this research lies around antioxidant therapy, but other potential solutions have been explored as well.

Conclusions

The management of hepatic trauma, in spite of the fact that it has become increasingly nonoperative, there still remains the possibility of hepatic resection in the hepatic trauma setting, especially in severe injuries. Hence, clinicians should be familiar with the concept of hepatic ischemia-reperfusion injury and respond appropriately and timely.

Isolated mitochondria infusion mitigates ischemia-reperfusion injury of the liver in rats

A recent study showed that the injection of mitochondria isolated from a nonischemic region mitigated myocardial injury. We tested the protective effects of infusing isolated mitochondria on the reperfusion injury in the liver of rats. A partial liver ischemia-reperfusion (I/R) model in male Wistar rats was used. At the 45th minute of liver ischemia, the recipient's spleen was infused with vehicle (I/R-vehicle group) or vehicle containing isolated mitochondria (7.7 × 10 ± 1.5 × 10/mL, I/R-mito group). After a 240-min reperfusion, the serum and livers were collected to assess tissue injury. Our results show that the elevation of serum alanine aminotransferase (414.3 ± 67.1 vs. 208.8 ± 30.2 U/L), the necrosis of hepatocytes on hematoxylin-eosin staining, increase in positive counts in TUNEL (terminal deoxynucleotidyl transferase dUTP nick end labeling) staining (59.5% ± 4.4% vs. 24.6% ± 9.1%), the expression of cytosolic cytochrome c, cleaved caspase 9, and 4-hydroxynonenal were all reduced in the I/R-mito group, compared with the I/R-vehicle group. The membrane potential of the isolated mitochondria measured by JC-1 fluorescence remained high, and the infused mitochondria were distributed in the liver parenchyma at 240 min after reperfusion. These results demonstrate that an intrasplenic infusion of viable mitochondria isolated from the donor before reperfusion significantly reduced I/R injury in the liver.

A comparison of hepatic ischemia/hypoxia-reperfusion injury models

INTRODUCTION

A number of hepatic ischemia/hypoxia-reperfusion models have been described. This study characterised the functional and structural changes induced by the most commonly used in vivo and in situ models for hypoxia/ischemia-reperfusion in the rat liver.

METHODS

A range of no-flow, slow-flow and lobar ischemia and reperfusion models were established in the rat liver. Changes following reperfusion were monitored using physiological, biochemical, histological and pharmacological assessments, including bile production, oxygen consumption, lignocaine extraction, enzyme release, and disposition of exogenous markers.

RESULTS

Short periods of hepatic ischemia/hypoxia-reperfusion led to minimal changes in liver function whereas long periods of ischemia-reperfusion led to substantial liver injury. The most severe injury was found with the slow flow, reflow model. The formation of cell vacuoles, blebs and focal hepatitis were the most important liver morphological changes observed as a consequence of ischemia/hypoxia. The major liver histological findings after reperfusion were dispersed apoptosis and local necrosis. Hepatic ischemia/hypoxia-reperfusion was also associated with significant changes in the hepatic extracellular and intracellular spaces.

DISCUSSION

The morphology and function of the liver associated with a range of hepatic ischemia/hypoxia-reperfusion models varies with the duration of the insult and between models. The choice of model is therefore an important consideration in seeking to resolve any particular hypothesis associated with hepatic ischemia/hypoxia-reperfusion.

Antioxidant Stress and Anti-Inflammation of PPARα on Warm Hepatic Ischemia-Reperfusion Injury

Hepatic ischemia-reperfusion (IR) injury is a serious clinical problem. Minimizing the adverse effect of ischemia-reperfusion injury after liver surgery or trauma is an urgent need. It has been proved that besides the effect of regulating the lipid and lipoprotein metabolism, PPARα also undertakes the task of organ protection. In this paper, related literature has been summarized and we come to the conclusion that administration of PPARα agonists can strengthen the antioxidant and anti-inflammation defense system by the upregulation of the expression of antioxidant enzymes and inhibition of NF-κB activity. This may provide a potential clinical treatment for hepatic ischemia-reperfusion injury.

Regulatory mechanisms of injury and repair after hepatic ischemia/reperfusion

Hepatic ischemia/reperfusion injury is an important complication of liver surgery and transplantation. The mechanisms of this injury as well as the subsequent reparative and regenerative processes have been the subject of thorough study. In this paper, we discuss the complex and coordinated responses leading to parenchymal damage after liver ischemia/reperfusion as well as the manner in which the liver clears damaged cells and regenerates functional mass.

Current strategies to minimize hepatic ischemia-reperfusion injury by targeting reactive oxygen species

Ischemia-reperfusion is a major component of injury in vascular occlusion both during liver surgery and during liver transplantation. The pathophysiology of hepatic ischemia-reperfusion includes a number of mechanisms including oxidant stress that contribute to various degrees to the overall organ damage. A large volume of recent research has focused on the use of antioxidants to ameliorate this injury, although results in experimental models have not translated well to the clinic. This review focuses on critical sources and mediators of oxidative stress during hepatic ischemia-reperfusion, the status of current antioxidant interventions, and emerging mechanisms of protection by preconditioning. While recent advances in regulation of antioxidant systems by Nrf2 provide interesting new potential therapeutic targets, an increased focus must be placed on more in-depth mechanistic investigations in hepatic ischemia-reperfusion injury and translational research in order to refine current strategies in disease management.

Recent progress toward hydrogen medicine: potential of molecular hydrogen for preventive and therapeutic applications

Persistent oxidative stress is one of the major causes of most lifestyle-related diseases, cancer and the aging process. Acute oxidative stress directly causes serious damage to tissues. Despite the clinical importance of oxidative damage, antioxidants have been of limited therapeutic success. We have proposed that molecular hydrogen (H₂) has potential as a “novel” antioxidant in preventive and therapeutic applications [Ohsawa et al., Nat Med. 2007: 13; 688-94]. H₂ has a number of advantages as a potential antioxidant: H₂ rapidly diffuses into tissues and cells, and it is mild enough neither to disturb metabolic redox reactions nor to affect reactive oxygen species (ROS) that function in cell signaling, thereby, there should be little adverse effects of consuming H₂. There are several methods to ingest or consume H₂, including inhaling hydrogen gas, drinking H₂-dissolved water (hydrogen water), taking a hydrogen bath, injecting H₂-dissolved saline (hydrogen saline), dropping hydrogen saline onto the eye, and increasing the production of intestinal H₂ by bacteria. Since the publication of the first H₂ paper in Nature Medicine in 2007, the biological effects of H₂ have been confirmed by the publication of more than 38 diseases, physiological states and clinical tests in leading biological/medical journals, and several groups have started clinical examinations. Moreover, H₂ shows not only effects against oxidative stress, but also various anti-inflammatory and anti-allergic effects. H₂ regulates various gene expressions and protein-phosphorylations, though the molecular mechanisms underlying the marked effects of very small amounts of H₂ remain elusive.

Impact of venous systemic oxygen persufflation supplemented with nitric oxide gas on cold-stored, warm ischemia-damaged experimental liver grafts

The increasing shortage of donor organs has led to the increasing use of organs from non-heart-beating donors. We aimed to assess the impact of venous systemic oxygen persufflation (VSOP) supplemented with nitric oxide (NO) gas during the cold storage (CS) of warm ischemia (WI)-damaged experimental liver grafts. Rat livers (n = 5 per group) were retrieved after 30 minutes of WI induced by cardiac arrest (the WI group) and were thereafter preserved for 24 hours by CS in histidine tryptophan ketoglutarate solution. During CS, gaseous oxygen was insufflated via the caval vein with 40 ppm NO (the VSOP-NO group) or without NO (the VSOP group). Cold-stored livers without WI served as controls. Liver viability was assessed after the preservation period by normothermic isolated reperfusion for 45 minutes with oxygenated Krebs-Henseleit buffer. After 45 minutes of reperfusion, the VSOP-NO-treated livers showed significantly lower alanine aminotransferase values than the WI-damaged livers (10.2 ± 0.2 versus 78.2 ± 14.6 IU/L), whereas the control livers showed no differences from the VSOP-NO-treated livers. The mitochondrial enzyme release was lower in the VSOP-NO group (4.0 ± 0.7 IU/L) versus the WI group (18.2 ± 4.9 IU/L). An increased portal vein pressure was observed throughout reperfusion (45 minutes) in the WI group (21.7 ± 0.2 mm Hg) versus the VSOP-NO group (12.2 ± 0.8 mm Hg) and the control group (19.9 ± 0.4 mm Hg). Furthermore, the NO concentration in the perfusate after 5 minutes of reperfusion was highest in the VSOP-NO group. The release of malondialdehyde into the perfusate was significantly reduced in the VSOP-NO group (0.9 ± 0.1 nmol/mL) versus the WI group (31.3 ± 5.3 nmol/mL). In conclusion, the resuscitation of livers after 30 minutes of WI to a level comparable to that of nonischemically damaged livers is possible with VSOP supplemented with NO gas. Moreover, the application of VSOP with NO minimizes the extent of injuries caused by oxygen free radicals during preservation.

Triptolide alleviates hepatic ischemia/reperfusion injury by attenuating oxidative stress and inhibiting NF-κB activity in mice

BACKGROUND

Hepatic I/R injury is unavoidable in liver transplantation and surgery. This remains a significant problem in surgical procedures. The purpose of this study was to investigate the effects of triptolide on liver ischemia/reperfusion (I/R) injury and related mechanisms in mice.

MATERIALS AND METHODS

Male C57BL/6 mice were randomized into four groups: (1) sham group; (2) sham-triptolide group; (3) I/R group; and (4) I-R/triptolide group. Ninety minutes of warm ischemia was induced and flow by 24 h reperfusion. Serum alanine aminotransferase and aspartate aminotransferase were assayed, pathologic alterations and (NF)-κB p65 immunohistochemistry were observed. Liver malondialdehyde (MDA) level, activity of endogenous antioxidant enzymes, superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GSH-Px) activities, and activity of neutrophil accumulation marker myeloperoxidase (MPO) were measured. TNF-α, IL-6, and IL-1β mRNA were detected by RT-PCR, whereas nuclear factor (NF)-κB p65 and IκBα were assessed with Western blotting.

RESULTS

Plasma aminotransferase activity was higher in the I/R group than in the I/R-triptolide group. MDA level and neutrophil infiltration were also markedly reduced, while SOD, CAT, and GSH-Px levels increased in I/R-triptolide group compared with I/R group. In group 4, histopathologic changes were significantly attenuated in triptolide-treated livers. In comparison with group 3, triptolide reduced NF-κB p65 nuclear and IκBα expression, and effectively suppressed pro-inflammatory cytokine level during the I/R.

CONCLUSIONS

These results suggest that triptolide has protective effects against hepatic I/R injury. Its mechanisms might be related to reduction of oxidative stress and neutrophil infiltration and inhibition NF-κB p65 activity.

Molecular biology of liver ischemia/reperfusion injury: established mechanisms and recent advancements

Hepatic ischemia/reperfusion (I/R) injury occurs in a variety of clinical contexts, including transplantation, liver resection surgery, trauma, and hypovolemic shock. The mechanism of organ damage after I/R has been studied extensively and consists of complex interactions of multiple inflammatory pathways. The major contributors to I/R injury include production of reactive oxygen species, release of proinflammatory cytokines and chemokines, and activation of immune cells to promote inflammation and tissue damage. Recent research has focused on the mechanisms by which these immune responses are initially activated through signaling molecules and their cellular receptors. Thorough understanding of the pathophysiology of liver I/R may yield novel therapeutic strategies to reduce I/R injury and lead to improved clinical outcomes.

Toll-like receptors in hepatic ischemia/reperfusion and transplantation

The family of Toll-like receptors (TLRs) function as pattern-recognition receptors (PRRs) that respond to a myriad of highly conserved ligands. These substrates include pathogen-associated molecular patterns (PAMPs) for the recognition of invading pathogens, as well as damage-associated molecular patterns (DAMPs) for the recognition of endogenous tissue injury. While the functions of TLRs are diverse, they have received much attention for their roles in ischemia/reperfusion (I/R) injury of the liver and other organs. The TLRs play central roles in sensing tissue damage and activating the innate immune system following I/R. Engagement of TLRs by endogenous DAMPs activates proinflammatory signaling pathways leading to the production of cytokines, chemokines and further release of endogenous danger signals. This paper focuses on the most recent findings regarding TLR family members in hepatic I/R injury and transplantation.

Antioxidant treatment during preservation of bovine ovaries increased the development potential of embryos

The overnight preservation of bovine ovaries would be highly useful in the subsequent harvest of viable oocytes for reproductive study. The present study aimed to optimize conditions for overnight preservation of bovine ovaries by examining the effects of temperature, solution and supplementation. In Experiment 1, the rate of development to the blastocyst stage of oocytes derived from ovaries preserved at 15°C was higher than that at either 5 or 25°C (p < 0.05). In Experiment 2, the rate of development to the blastocyst stage of oocytes derived from ovaries preserved in University of Wisconsin solution was higher than when PBS or saline was used (p < 0.05). In Experiment 3, oocytes preserved in saline supplemented with 0.3 mM glutathione (GSH) exhibited an increase in the rate of blastocyst formation compared with oocytes supplemented with 0 or 3 mM GSH (p < 0.05). In Experiment 4, supplementation with 10 μM epigallocatechin gallate during ovary preservation increased the rate of blastocyst formation (p < 0.05). The blastocysts derived from ovaries stored in saline supplemented with GSH at 15°C for 24 h were shown to develop into normal offsprings following transfer to recipient heifers. Our studies indicate that bovine IVM/IVF embryos derived from ovaries preserved in saline supplemented with an antioxidant at 15°C for 24 h can successfully develop to the blastocyst stage and result in offspring.

Curcumin reduces hepatic nitric oxide production in early-stage ischemia/reperfusion in rats

AIM: To investigate the effects of curcumin on the microcirculation in early-stage ischemia/reperfusion injury in rats.

METHODS: Wistar rats were randomized into three groups: sham-operation group, dimethyl sulfoxide (DMSO) group (treated with 1 mL of DMSO twice) and curcumin group (treated with 40 mg/kg of curcumin twice). The level of serum transaminase, the content of hepatic nitric oxide (NO), and the expression of nitric oxide synthase (NOS), inducible nitric oxide synthase (iNOS) and endothelial nitric oxide synthase (eNOS) mRNAs in liver tissue were determined to evaluate the effects of curcumin on the microcirculation in early-stage ischemia/reperfusion (reperfusion for 1 h and 3 h).

RESULTS: Compared with the DMSO group, curcumin decreased the levels of serum alanine transaminase (603.8 U/L ± 64.5 U/L vs 758.1 U/L ± 114.7 U/L and 837.1 U/L ± 33.3 U/L vs 1012.7 U/L ± 119.8 U/L, respectively; both P < 0.01) and aspartate aminotransferase (605.7 U/L ± 65.7 U/L vs 779.5 U/L ± 124.3 U/L and 849.6 U/L ± 36.0 U/L vs 1027.8 U/L ± 139.8 U/L, respectively; both P < 0.01), relieved hepatic pathological damage, reduced the content of NO (0.455 ± 0.056 vs 0.594 ± 0.087 and 0.492 ± 0.040 vs 0.671 ± 0.079, respectively; both P < 0.01) derived from iNOS, and down-regulated the expression of iNOS mRNA (0.426 ± 0.075 vs 0.569 ± 0.073 and 0.527 ± 0.066 vs 0.702 ± 0.089, respectively; both P < 0.01) in the liver tissue in early-stage ischemia/reperfusion (reperfusion for 1 h and 3 h).

CONCLUSION: Curcumin can relieve hepatic cell injury by decreasing the content of NO derived from iNOS and reducing hepatic microcirculation disturbance in early-stage ischemia/reperfusion injury in rats.

In-chern-hau-tang and genipin reduces acute urinary bladder distension evoked sympathetic activation-induced hepatic dysfunction in rats

Increased norepinephrine production by acute urine retention (AUR) induced sympathetic activation may contribute to acute liver injury (ALI) via the action of hepatic vasoconstriction and increased reactive oxygen species (ROS) production. We evaluated whether In-Chern-Hau-Tang, a hepatoprotective herb medicine, and its major ingredient genipin, may ameliorate norepinephrine-induced liver injury in the rat. We determined the effects of In-Chern-Hau-Tang and genipin on norepinephrine-induced oxidative stress in the Kupffer and endothelial cells and AUR-induced ALI in the rat via a chemiluminescence analyzer, physiologic and biochemical determination and western blot. The results of in vitro study showed that genipin with efficient H(2)O(2) and HOCl scavenging activities decreased norepinephrine-enhanced ROS production in the Kupffer cell and endothelial cell cultures. AUR activated hepatic sympathetic nervous activity lead to a hepatic hypoxia/hypoperfusion, and a reduction in bile flow. AUR increased intercellular adhesion molecular 1 (ICAM-1) protein expression, and hepatic ROS production from the activated leukocyte NADPH oxidase activity subsequently leading to plasma aspartate aminotransferase (AST) elevation. Hepatic sympathetic denervation, or oral pretreatment of In-Chern-Hau-Tang or genipin for 1 week ameliorated the level in AUR-induced hepatic hypoxia/hypoperfusion, and bile stasis. Hepatic denervation, In-Chern-Hau-Yang and genipin inhibited AUR-enhanced hepatic ICAM-1 expression, hepatic ROS production, leukocyte NADPH oxidase activity and plasma AST activity. In conclusion, In-Chern-Hau-Tang along with its active component, genipin, can ameliorate AUR-induced ALI via the alleviation of oxidative stress possibly by the inhibition of sympathetic induced hypoxia/hypoperfusion and leukocyte NADPH oxidase activity.

Toll-like receptor 9 inhibition confers protection from liver ischemia-reperfusion injury

Endogenous ligands such as high-mobility group box 1 (HMGB1) and nucleic acids are released by dying cells and bind Toll-like receptors (TLRs). Because TLR9 sits at the interface of microbial and sterile inflammation by detecting both bacterial and endogenous DNA, we investigated its role in a model of segmental liver ischemia-reperfusion (I/R) injury. Mice were subjected to 1 hour of ischemia and 12 hours of reperfusion before assessment of liver injury, cytokines, and reactive oxygen species (ROS). Wild-type (WT) mice treated with an inhibitory cytosine-guanosine dinucleotide (iCpG) sequence and TLR9(-/-) mice had markedly reduced serum alanine aminotransferase (ALT) and inflammatory cytokines after liver I/R. Liver damage was mediated by bone marrow-derived cells because WT mice transplanted with TLR9(-/-) bone marrow were protected from hepatic I/R injury. Injury in WT mice partly depended on TLR9 signaling in neutrophils, which enhanced production of ROS, interleukin-6 (IL-6), and tumor necrosis factor (TNF). In vitro, DNA released from necrotic hepatocytes increased liver nonparenchymal cell (NPC) and neutrophil cytokine secretion through a TLR9-dependent mechanism. Inhibition of both TLR9 and HMGB1 caused maximal inflammatory cytokine suppression in neutrophil cultures and conferred even greater protection from I/R injury in vivo.

CONCLUSION

TLR9 serves as an endogenous sensor of tissue necrosis that exacerbates the innate immune response during liver I/R. Combined blockade of TLR9 and HMGB1 represents a clinically relevant, novel approach to limiting I/R injury.

Hepatoprotective evaluation of Anogeissus latifolia: in vitro and in vivo studies

AIM

To evaluate the hepatoprotective activity of a hydroalcoholic extract of the bark of Anogeissus latifolia; in vitro in primary rat hepatocyte monolayer culture and in vivo in the liver of Wistar rats intoxicated by carbon tetrachloride (CCl(4)).

METHODS

In the in vitro study, a primary hepatocyte monolayer culture was treated with CCl(4) and extract of Anogeissus latifolia. Hepatoprotective activity was demonstrated in the CCl(4) damaged primary monolayer culture. In the in vivo study, the hepatoprotective activity of a hydroalcoholic extract of Anogeissus latifolia was analyzed in liver injured CCl(4)-treated rats. Biochemical parameters including serum transaminases [aspartate aminotransferase (AST) and alanine aminotransferase (ALT)] and alkaline phosphatase (ALP) in serum were analyzed. The biochemical findings were supplemented with histopathological examination of rat liver sections.

RESULTS

In vitro: primary hepatocyte monolayer cultures were treated with CCl(4) and extract of Anogeissus latifolia. A protective activity could be demonstrated in the CCl(4) damaged primary monolayer culture. In vivo: Hydroalcoholic extract of Anogeissus latifolia (300 mg/kg) was found to have protective activity in rats with CCl(4)-induced liver damage as judged from serum marker enzyme activity.

CONCLUSION

The above findings lead to the conclusion that the hydroalcoholic extract of Anogeissus latifolia is hepatoprotective. Hence, we suggest that the inclusion of this plant in the management of liver disorders is justified.

Sialic acid reduces acute endotoxemia-induced liver dysfunction in the rat

Endotoxemia caused by LPS is a life-threatening and inflammatory condition contributing to multiple organ failure. Viruses or bacteria require sialic acid (SA) for target-cell binding. We suggest that exogenous SA through masking or mediating the binding of LPS to the target cells may attenuate LPS-induced liver dysfunction and cecal ligation and puncture-induced shock. We found that SA can directly scavenge O2-, H2O2, and NO activity by a chemiluminescence analyzer and bind to LPS with high affinity using surface plasmon resonance. Intravenous SA significantly increased plasma SA concentration within 4 h. We then assessed the potential effect of SA on LPS-induced acute endotoxemia in the rat. Intravenous LPS (10-50 mg/kg) dose-dependently increased plasma endotoxin and reactive oxygen species in the blood, bile, and liver and increased plasma alanine aminotransferase and aspartate aminotransferase levels as well as TNF-alpha, monocyte chemoattractant protein 1, tissue inhibitor of metalloproteinase 1, IL-1beta, and IL-6 levels in the rats. Thirty minutes after LPS stimulation, SA decreased LPS-enhanced endotoxin level, oxidative stress, alanine aminotransferase and aspartate aminotransferase levels, and cytokine concentration and ameliorated histopathologic alteration in the liver. We found that SA increased LPS-depressed Mn-superoxide dismutase, CuZn-superoxide dismutase, and heat shock protein 70 and decreased LPS-enhanced iNOS and proapoptotic Bax protein expression in the liver by Western blot. Sialic acid was given after treatment to rats subjected to cecal ligation and puncture, and the hypotensive effect was blunted for 6 h. In conclusion, SA treatment can counteract LPS-enhanced acute endotoxemia and oxidative injury via a direct scavenging reactive oxygen species activity and neutralization potential.