High-mobility Group Box 1 In Hepatocytes Research Articles

Overexpression of HMGB1 in hepatocytes accelerates PTEN inactivation-induced liver cancer.

Liver cancer is increasing due to the rise in metabolic dysfunction-associated steatohepatitis (MASH). High-mobility group box-1 (HMGB1) is involved in the pathogenesis of chronic liver disease, but its role in MASH-associated liver cancer is unknown. We hypothesized that an increase in hepatocyte-derived HMGB1 in a mouse model of inactivation of PTEN that causes MASH could promote MASH-induced tumorigenesis. We analyzed publicly available transcriptomics datasets, and to explore the effect of overexpressing HMGB1 in cancer progression, we injected 1.5-month-old Pten∆Hep mice with adeno-associated virus serotype-8 (AAV8) vectors to overexpress HMGB1-EGFP or EGFP, and sacrificed them at 3, 9 and 11 months of age. We found that HMGB1 mRNA increases in human MASH and MASH-induced hepatocellular carcinoma (MASH-HCC) compared to healthy livers. Male and female Pten∆Hep mice overexpressing HMGB1 showed accelerated liver tumor development at 9 and 11 months, respectively, with increased tumor size and volume, compared to control Pten∆Hep mice. Moreover, Pten∆Hep mice overexpressing HMGB1, had increased incidence of mixed HCC-intrahepatic cholangiocarcinoma (iCCA). All iCCAs were positive for nuclear YAP and SOX9. Male Pten∆Hep mice overexpressing HMGB1 showed increased cell proliferation and F4/80+ cells at 3 and 9 months. Overexpression of HMGB1 in hepatocytes accelerates liver tumorigenesis in Pten∆Hep mice, enhancing cell proliferation and F4/80+ cells to drive MASH-induced liver cancer.

Inhibition of macrophages inflammasome activation via autophagic degradation of HMGB1 by EGCG ameliorates HBV-induced liver injury and fibrosis.

Liver fibrosis is a reversible wound-healing response that can lead to end-stage liver diseases without effective treatment, in which HBV infection is a major cause. However, the underlying mechanisms for the development of HBV-induced fibrosis remains elusive, and efficacious therapies for this disease are still lacking. In present investigation, we investigated the effect and mechanism of green tea polyphenol epigallocatechin-3-gallate (EGCG) on HBV-induced liver injury and fibrosis. The effect of EGCG on liver fibrosis was examined in a recombinant cccDNA (rcccDNA) chronic HBV mouse model by immunohistochemical staining, Sirius red and Masson's trichrome staining. The functional relevance between high mobility group box 1 (HMGB1) and inflammasome activation and the role of EGCG in it were analyzed by Western blotting. The effect of EGCG on autophagic flux was determined by Western blotting and flow cytometric analysis. EGCG treatment efficiently was found to alleviate HBV-induced liver injury and fibrosis in a recombinant cccDNA (rcccDNA) chronic HBV mouse model, a proven suitable research platform for HBV-induced fibrosis. Mechanistically, EGCG was revealed to repress the activation of macrophage NLRP3 inflammasome, a critical trigger of HBV-induced liver fibrosis. Further study revealed that EGCG suppressed macrophage inflammasome through downregulating the level of extracellular HMGB1. Furthermore, our data demonstrated that EGCG treatment downregulated the levels of extracellular HMGB1 through activating autophagic degradation of cytoplasmic HMGB1 in hepatocytes. Accordingly, autophagy blockade was revealed to significantly reverse EGCG-mediated inhibition on extracellular HMGB1-activated macrophage inflammasome and thus suppress the therapeutic effect of EGCG on HBV-induced liver injury and fibrosis. EGCG ameliorates HBV-induced liver injury and fibrosis via autophagic degradation of cytoplasmic HMGB1 and the subsequent suppression of macrophage inflammasome activation. These data provided a new pathogenic mechanism for HBV-induced liver fibrosis involving the extracellular HMGB1-mediated macrophage inflammasome activation, and also suggested EGCG administration as a promising therapeutic strategy for this disease.

Leukocyte-Derived High-Mobility Group Box 1 Governs Hepatic Immune Responses to Listeria monocytogenes.

High‐mobility group box 1 (HMGB1) is a nucleoprotein with proinflammatory functions following cellular release during tissue damage. Moreover, antibody‐mediated HMGB1 neutralization alleviates lipopolysaccharide (LPS)‐induced shock, suggesting a role for HMGB1 as a superordinate therapeutic target for inflammatory and infectious diseases. Recent genetic studies have indicated cell‐intrinsic functions of HMGB1 in phagocytes as critical elements of immune responses to infections, yet the role of extracellular HMGB1 signaling in this context remains elusive. We performed antibody‐mediated and genetic HMGB1 deletion studies accompanied by in vitro experiments to discern context‐dependent cellular sources and functions of extracellular HMGB1 during murine bloodstream infection with Listeria monocytogenes. Antibody‐mediated neutralization of extracellular HMGB1 favors bacterial dissemination and hepatic inflammation in mice. Hepatocyte HMGB1, a key driver of postnecrotic inflammation in the liver, does not affect Listeria‐induced inflammation or mortality. While we confirm that leukocyte HMGB1 deficiency effectuates disseminated listeriosis, we observed no evidence of dysfunctional autophagy, xenophagy, intracellular bacterial degradation, or inflammatory gene induction in primary HMGB1‐deficient phagocytes or altered immune responses to LPS administration. Instead, we demonstrate that mice devoid of leukocyte HMGB1 exhibit impaired hepatic recruitment of inflammatory monocytes early during listeriosis, resulting in alterations of the transcriptional hepatic immune response and insufficient control of bacterial dissemination. Bone marrow chimera indicate that HMGB1 from both liver‐resident and circulating immune cells contributes to effective pathogen control. Conclusion: Leukocyte‐derived extracellular HMGB1 is a critical cofactor in the immunologic control of bloodstream listeriosis. HMGB1 neutralization strategies preclude an efficient host immune response against Listeria.

Hepatocyte high-mobility group box 1 protects against steatosis and cellular stress during high fat diet feeding

BackgroundCirculating high-mobility group box 1 (HMGB1) plays important roles in the pathogenesis of nonalcoholic fatty liver disease (NAFLD). Intracellular HMGB1 is critical for the biology of hepatocytes. However, the intracellular role of HMGB1 in hepatocellular steatosis is unknown. Therefore, we aimed to investigate the role of hepatocyte-specific HMGB1 (HC-HMGB1) in development of hepatic steatosis.MethodsWild type (WT) C57BL/6 and HC-HMGB1−/− mice were fed high-fat diet (HFD) or low-fat diet (LFD) for up to 16 weeks.ResultsAs expected, HMGB1 translocated from nuclear into cytoplasm and released into circulation after HFD treatment. HC-HMGB1 deficiency significantly reduced circulating HMGB1, suggesting that hepatocyte is a major source of circulating HMGB1 during NAFLD. Unexpectedly, HC-HMGB1 deficiency promoted rapid weight gain with enhanced hepatic fat deposition compared with WT at as early as 4 weeks after HFD treatment. Furthermore, there was no difference between WT and HC-HMGB1−/− mice in glucose tolerance, energy expenditure, liver damage or systemic inflammation. Interestingly, hepatic gene expression related to free fatty acid (FFA) β-oxidation was significantly down-regulated in HC-HMGB1−/− mice compared with WT, and endoplasmic reticulum (ER) stress markers were significantly higher in livers of HC-HMGB1−/− mice. In vitro experiments using primary mouse hepatocytes showed absence of HMGB1 increased FFA-induced intracellular lipid accumulation, accompanied by increased ER-stress, significant downregulation of FFA β-oxidation, and reduced oxidative phosphorylation.ConclusionsOur findings suggest that hepatocyte HMGB1 protects against dysregulated lipid metabolism via maintenance of β-oxidation and prevention of ER stress. This represents a novel mechanism for HMGB1-regulation of hepatocellular steatosis, and suggests that stabilizing HMGB1 in hepatocytes may be effective strategies for prevention and treatment of NAFLD.

LPS Induces Active HMGB1 Release From Hepatocytes Into Exosomes Through the Coordinated Activities of TLR4 and Caspase-11/GSDMD Signaling.

High-mobility group box-1 (HMGB1), a ubiquitous nuclear protein, acts as a late mediator of lethality when released extracellularly during sepsis. The major source of circulating HMGB1 in sepsis is hepatocytes. However, the mechanism of HMGB1 release of hepatocytes during sepsis is not very clear. We have previously shown that bacterial endotoxin [lipopolysaccharide (LPS)] sensing pathways, including Toll-like receptor (TLR)4 and caspase-11, regulate hepatocyte HMGB1 release in response to LPS. Here, we report the novel function of caspase-11 and gasdermin D (GsdmD) in LPS-induced active HMGB1 released from hepatocytes. HMGB1 release during endotoxemia was caspase-11/GsdmD dependent via an active way in vivo and in vitro. Caspase-11/GsdmD was responsible for HMGB1 translocation from nucleus to the cytoplasm via calcium changing-induced phosphorylation of calcium-calmodulin kinase kinase (camkk)β during endotoxemia. Cleaved GsdmD accumulated on the endoplasmic reticulum, suggesting this may lead to calcium leak and intracellular calcium increase. Furthermore, we investigated that exosome was an important pathway for HMGB1 release from hepatocytes; this process was dependent on TLR4, independent of caspase-11 and GsdmD in vivo and in vitro. These findings provide a novel mechanism that TLR4 signaling results in an increase in caspase-11 expression, as well as increased exosome release, while caspase-11/GsdmD activation/cleavage leads to accumulation of HMGB1 in the cytoplasm through a process associated with the release of calcium from the endoplasmic reticulum and camkkβ activation.

HMGB1 is a Central Driver of Dynamic Pro-inflammatory Networks in Pediatric Acute Liver Failure induced by Acetaminophen

Acetaminophen (APAP) overdose (APAPo) is predominant in the NIH Pediatric Acute Liver Failure (PALF) Study. We assayed multiple inflammatory mediators in serial serum samples from 13 PALF survivors with APAPo + N-acetylcysteine (NAC, the frontline therapy for APAPo), 8 non-APAPo + NAC, 40 non-APAPo non-NAC, and 12 non-survivors. High Mobility Group Box 1 (HMGB1) was a dominant mediator in dynamic inflammation networks in all sub-groups, associated with a threshold network complexity event at d1–2 following enrollment that was exceeded in non-survivors vs. survivors. We thus hypothesized that differential HMGB1 network connectivity after day 2 is related to the putative threshold event in non-survivors. DyNA showed that HMGB1 is most connected in non-survivors on day 2–3, while no connections were observed in APAPo + NAC and non-APAPo + NAC survivors. Inflammatory dynamic networks, and in particular HMGB1 connectivity, were associated with the use of NAC in the context of APAPo. To recapitulate hepatocyte (HC) damage in vitro, primary C57BL/6 HC and HC-specific HMGB1-null HC were treated with APAP + NAC. Network phenotypes of survivors were recapitulated in C57BL/6 mouse HC and were greatly altered in HMGB1-null HC. HC HMGB1 may thus coordinate a pro-inflammatory program in PALF non-survivors (which is antagonized by NAC), while driving an anti-inflammatory/repair program in survivors.

Recombinant relaxin protects liver transplants from ischemia damage by hepatocyte glucocorticoid receptor: From bench-to-bedside.

This translational study underscores the role of rhRLX-GR signaling as a regulator of hepatocellular protection against IR stress in OLT. In the context of a recent phase III clinical trial demonstrating positive outcomes of rhRLX in patients with acute heart failure, studies on rhRLX for the management of IRI in OLT recipients are warranted. (Hepatology 2018;68:258-273).

Regulation of HMGB1 in Hepatocytes by MyD88 and Type‐I interferon (IFN‐I) During Ehrlichia‐induced acute liver injury.

BackgroundLiver is the major target organ in Human Monocytic ehrlichiosis (HME), an undifferentiated febrile illness that is life‐threatening and caused by intracellular bacterial pathogen, Ehrlichia, that target liver and infect macrophages, hepatocytes and endothelial cells. Severe Hepatic inflammation is the common cause of acute liver injury following systemic infection with Ehrlichia. Our previous studies have shown that Myeloid differentiation primary response gene 88 (MYD88) and type I IFN (IFN‐I) promotes excessive inflammation and liver damage following fatal Ehrlichia infection. In this study, we explored the role of the MyD88 and IFN‐I in liver inflammation.ResultsIn this study, we provide evidence to support that high mobility group box 1 (HMGB1), a chromosomal protein and damage‐associated molecular patterns (DAMPs), plays a role in the regulation of innate responses and autophagy during Ehrlichia infection. Wild‐type (WT) mice infected with virulent Ehrlichia develop sepsis and liver injury marked by excessive systemic production of pro‐inflammatory cytokines and chemokines as well as HMGB1. To determine the cellular source of HMGB1 and regulatory mechanisms, we infected hepatocytes (HC) from WT and MYD88−/− knockout mice with virulent Ehrlichia. To mimic paracrine effect of IFN‐I cytokines produced by immune cells on HC response to Ehrlichia infection, we cultured infected HC in the presence or absence of IFN‐β (100 IU/mL). Our data indicate that in‐vitro infected HC produces low levels of IFN‐beta compared to uninfected cells. Exogenous stimulation of infected HC with IFN‐β induced elevated expression and cytoplasmic translocation of HMGB1 in WT‐HC. This was associated with increased autophagy and higher expression of IL‐23R, IFNAR, and heightened JAK/STAT signaling. Importantly, the effect of high dose IFN‐I on autophagy and HMGB1 was MYD88‐dependent. Interestingly, infection of MYD88−/− HC with Ehrlichia, in the absence of exogenous IFN‐β, enhanced autophagy induction and cytosolic translocation of HMGB1, suggesting that MYD88 negatively regulate HMGB1 and autophagy in HC in the absence of the paracrine effect of IFN‐β.ConclusionTogether, our data suggest that autophagy regulation and HMGB1 response in hepatocytes during Ehrlichia‐induced sepsis is controlled by the strength of IFN‐I signaling and dependent on interplay between MYD88 and IFN‐I pathways.Support or Funding InformationThis work was supported by grants from NIAMS, NIGMD, and NIAID (AR68317 CCY, RO1‐GM102146 MS, and R56A1097679 NI)This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Quercetin attenuates the activation of hepatic stellate cells and liver fibrosis in mice through modulation of HMGB1-TLR2/4-NF-κB signaling pathways

This study aimed to investigate the effects of quercetin on liver fibrogenesis in mice and to elucidate the underlying molecular mechanisms. Mice were administered with carbon tetrachloride (CCl4) for eight weeks to induce liver fibrosis and concomitantly orally treated with quercetin (50mgkg−1day−1). Here, we demonstrated that quercetin dramatically ameliorated liver injury, inflammation, and hepatic fibrogenesis induced by CCl4. Quercetin also inhibited the activation of hepatic stellate cells (HSC) in vivo and in vitro, as evaluated by α-smooth muscle actin (α-SMA) expression, which is a specific marker of HSC activation. Moreover, reduced fibrosis was associated with decreased high-mobility group box 1 (HMGB1), toll like receptor (TLR) 2 and TLR4 genes, and protein expression. Quercetin also inhibited the cytoplasmic translocation of HMGB1 in hepatocytes of fibrotic livers. Further investigation demonstrated that quercetin treatment significantly attenuated CCl4-induced nuclear translocation of the nuclear factor-κB (NF-κB) p65 and inhibited degradation of IκBα (an inhibitor of NF-κB) expression in the liver compared with vehicle-treated fibrotic mice. Considered together, our data indicate that quercetin has hepatoprotective and anti-fibrotic effects in animal models of liver fibrosis, the mechanism of which may be involved in modulating the HMGB1-TLR2/4-NF-κB signaling pathways.

Association between protective effect of Liuwei Wuling tablets against acute liver injury and its inhibitory effect on cytoplasmic translocation of high-mobility group box-1 in hepatocytes in mice

To investigate the effect of Liuwei Wuling tablets on the cytoplasmic translocation and release of high-mobility group box-1 (HMGB1) in hepatocytes in mice with acute live injury induced by D-galactosamine (D-GalN) and lipopolysaccharide (LPS). A Balb/c mouse model of acute liver injury was established by intraperitoneal injection of D-GalN (400 mg/kg) and LPS (5 ug/kg). A total of 24 healthy mice were randomly and equally divided into acute liver injury control group and Liuwei Wuling tablet treatment group. The serum levels of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) were measured in both groups at each time point within one week. Liver tissues were collected at 36 hours to perform pathological examination. The serum levels of HMGB1, tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), interleukin-6 (IL-6), complement 3a (C3a), and complement 5a (C5a) were measured. Immunohistochemistry was used to determine the expression and cytoplasmic translocation of HMGB1 in hepatocytes. At 6, 12, and 24 hours, the Liuwei Wuling tablet treatment group had significantly lower serum levels of ALT than the control group (225.33±181.64 U/L vs 471.17±174.72 U/L, t = 3.38, P < 0.01; 1509.53±182.51 U/L vs 7149.52±734.25 U/L, t = 25.82, P < 0.01; 162.89±86.51 U/L vs 1318.16±557.71 U/L, t = 7.09, P < 0.01), as well as significantly lower serum levels of AST than the control group (179.22±94.57 U/L vs 561.91±209.6 U/L, t = 5.76, P < 0.01; 590.92±190.92 U/L vs 2266.48±705.64 U/L, t = 7.94, P < 0.01; 231.24±87.7 U/L vs 444.32±117.01 U/L, t = 5.05, P < 0.01). The treatment group had significantly lower levels of HMGB1 than the control group at 6 and 12 hours (54.21±11.89 ng/ml vs 72.07±13.65 ng/ml, t = 3.41, P < 0.01; 49.23±5.97 ng/ml vs 68.71±13.07 ng/ml, t = 4.70, P < 0.01). The treatment group had significantly lower levels of TNF-α, IL-1β, and IL-6 than the control group at 12 hours (163.62±9.12 pg/ml vs 237.09±51.47 pg/ml, t = 4.86, P < 0.01; 15.66±13.13 pg/ml vs 37.43±18.68 pg/ml, t = 3.30, P < 0.01; 7.10±3.06 pg/ml vs 21.42±8.23 pg/ml, t = 5.65, P < 0.01). The treatment group had significantly lower levels of C3a and C5a than the control group at 12 hours (2.52±1.27 pg/ml vs 9.83±2.96 ng/ml, t = 7.86, P < 0.01; 2.16±1.03 ng/ml vs 7.23±1.55 ng/ml, t = 9.67, P < 0.01). Compared with the control group, the treatment group had significantly reduced liver inflammation and necrosis, and a significantly lower cytoplasmic translocation rate of HMGB1 in hepatocytes (38.76%±7.37% vs 8.15%±2.11%, P < 0.01). Liuwei Wuling tablets can reduce the cytoplasmic translocation of HMGB1 in hepatocytes and relieve liver inflammation in mice with acute liver injury.

High Mobility Group Box-1 (HMGB1) Participates in the Pathogenesis of Alcoholic Liver Disease (ALD)

Growing clinical and experimental evidence suggests that sterile inflammation contributes to alcoholic liver disease (ALD). High mobility group box-1 (HMGB1) is highly induced during liver injury; however, a link between this alarmin and ALD has not been established. Thus, the aim of this work was to determine whether HMGB1 contributes to the pathogenesis of ALD. Liver biopsies from patients with ALD showed a robust increase in HMGB1 expression and translocation, which correlated with disease stage, compared with healthy explants. Similar findings were observed in chronic ethanol-fed wild-type (WT) mice. Using primary cell culture, we validated the ability of hepatocytes from ethanol-fed mice to secrete a large amount of HMGB1. Secretion was time- and dose-dependent and responsive to prooxidants and antioxidants. Selective ablation of Hmgb1 in hepatocytes protected mice from alcohol-induced liver injury due to increased carnitine palmitoyltransferase-1, phosphorylated 5'AMP-activated protein kinase-α, and phosphorylated peroxisome proliferator-activated receptor-α expression along with elevated LDL plus VLDL export. Native and post-translationally modified HMGB1 were detected in humans and mice with ALD. In liver and serum from control mice and in serum from healthy volunteers, the lysine residues within the peptides containing nuclear localization signals (NLSs) 1 and 2 were non-acetylated, and all cysteine residues were reduced. However, in livers from ethanol-fed mice, in addition to all thiol/non-acetylated isoforms of HMGB1, we observed acetylated NLS1 and NLS2, a unique phosphorylation site in serine 35, and an increase in oxidation of HMGB1 to the disulfide isoform. In serum from ethanol-fed mice and from patients with ALD, there was disulfide-bonded hyperacetylated HMGB1, disulfide-bonded non-acetylated HMGB1, and HMGB1 phosphorylated in serine 35. Hepatocytes appeared to be a major source of these HMGB1 isoforms. Thus, hepatocyte HMGB1 participates in the pathogenesis of ALD and undergoes post-translational modifications (PTMs) that could condition its toxic effects.

Hepatocyte-specific high-mobility group box 1 deletion worsens the injury in liver ischemia/reperfusion: A role for intracellular high-mobility group box 1 in cellular protection

High-mobility group box 1 (HMGB1) is an abundant chromatin-associated nuclear protein and released into the extracellular milieu during liver ischemia-reperfusion (I/R), signaling activation of proinflammatory cascades. Because the intracellular function of HMGB1 during sterile inflammation of I/R is currently unknown, we sought to determine the role of intracellular HMGB1 in hepatocytes after liver I/R. When hepatocyte-specific HMGB1 knockout (HMGB1-HC-KO) and control mice were subjected to a nonlethal warm liver I/R, it was found that HMGB1-HC-KO mice had significantly greater hepatocellular injury after I/R, compared to control mice. Additionally, there was significantly greater DNA damage and decreased chromatin accessibility to repair with lack of HMGB1. Furthermore, lack of hepatocyte HMGB1 led to excessive poly(ADP-ribose)polymerase 1 activation, exhausting nicotinamide adenine dinucleotide and adenosine triphosphate stores, exacerbating mitochondrial instability and damage, and, consequently, leading to increased cell death. We found that this was also associated with significantly more oxidative stress (OS) in HMGB1-HC-KO mice, compared to control. Increased nuclear instability led to a resultant increase in the release of histones with subsequently more inflammatory cytokine production and organ damage through activation of Toll-like receptor 9. The lack of HMGB1 within hepatocytes leads to increased susceptibility to cellular death after OS conditions.

High Mobility Group Box 1 Release from Hepatocytes during Ischemia and Reperfusion Injury Is Mediated by Decreased Histone Deacetylase Activity

The mobilization and extracellular release of nuclear high mobility group box-1 (HMGB1) by ischemic cells activates inflammatory pathways following liver ischemia/reperfusion (I/R) injury. In immune cells such as macrophages, post-translational modification by acetylation appears to be critical for active HMGB1 release. Hyperacetylation shifts its equilibrium from a predominant nuclear location toward cytosolic accumulation and subsequent release. However, mechanisms governing its release by parenchymal cells such as hepatocytes are unknown. In this study, we found that serum HMGB1 released following liver I/R in vivo is acetylated, and that hepatocytes exposed to oxidative stress in vitro also released acetylated HMGB1. Histone deacetylases (HDACs) are a family of enzymes that remove acetyl groups and control the acetylation status of histones and various intracellular proteins. Levels of acetylated HMGB1 increased with a concomitant decrease in total nuclear HDAC activity, suggesting that suppression in HDAC activity contributes to the increase in acetylated HMGB1 release after oxidative stress in hepatocytes. We identified the isoforms HDAC1 and HDAC4 as critical in regulating acetylated HMGB1 release. Activation of HDAC1 was decreased in the nucleus of hepatocytes undergoing oxidative stress. In addition, HDAC1 knockdown with siRNA promoted HMGB1 translocation and release. Furthermore, we demonstrate that HDAC4 is shuttled from the nucleus to cytoplasm in response to oxidative stress, resulting in decreased HDAC activity in the nucleus. Together, these findings suggest that decreased nuclear HDAC1 and HDAC4 activities in hepatocytes following liver I/R is a mechanism that promotes the hyperacetylation and subsequent release of HMGB1.

123: High-mobility group box 1 (HMGB1) release in response to hypoxia involves TLR4-dependent production of reactive oxygen species

Introduction: HMGB1 is a nuclear factor released extracellularly as a late mediator of lethality in sepsis and as an early mediator of inflammation following acute tissue injury. The mechanisms accounting for HMGB1 release are unknown. We have previously shown that hypoxia in vitro and ischemia-reperfusion (I/R) in vivo result in the upregulation of HMGB1 in hepatocytes. In addition, HMGB1-mediated hepatic injury after I/R is TLR4-dependent. Thus, we hypothesized that the release of HMGB1 due to oxidative stress may be associated with TLR4-dependent production of reactive oxygen species (ROS).