D-Galactosamine/Lipopolysaccharide-Induced Hepatotoxicity Downregulates Sirtuin 1 in Rat Liver: Role of Sirtuin 1 Modulation in Hepatoprotection

The role of sirtuin1 in liver injury: molecular mechanisms and novel therapeutic target

Liver disease is a common and serious threat to human health. The progression of liver diseases is influenced by many physiologic processes, including oxidative stress, inflammation, bile acid metabolism, and autophagy. Various factors lead to the dysfunction of these processes and basing on the different pathogeny, pathology, clinical manifestation, and pathogenesis, liver diseases are grouped into different categories. Specifically, Sirtuin1 (SIRT1), a member of the sirtuin protein family, has been extensively studied in the context of liver injury in recent years and are confirmed the significant role in liver disease. SIRT1 has been found to play a critical role in regulating key processes in liver injury. Further, SIRT1 seems to cause divers outcomes in different types of liver diseases. Recent studies have showed some therapeutic strategies involving modulating SIRT1, which may bring a novel therapeutic target. To elucidate the mechanisms underlying the role of sirtuin1 in liver injury and its potentiality as a therapeutic target, this review outlines the key signaling pathways associated with sirtuin1 and liver injury, and discusses recent advances in therapeutic strategies targeting sirtuin1 in liver diseases.

Investigation of the usefulness of liver-specific deconvolution method by establishing a liver benchmark dataset

Immune responses in the liver are related to the development and progression of liver failure, and precise prediction of their behavior is important. Deconvolution is a methodology for estimating the immune cell proportions from the transcriptome, and it is mainly applied to blood-derived samples and tumor tissues. However, the influence of tissue-specific modeling on the estimation results has rarely been investigated. Here, we constructed a system to evaluate the performance of the deconvolution method on liver transcriptome data. We prepared seven mouse liver injury models using small-molecule compounds and established a benchmark dataset with corresponding liver bulk RNA-Seq and immune cell proportions. RNA-Seq expression for nine leukocyte subsets and four liver-associated cell types were obtained from the Gene Expression Omnibus to provide a reference. We found that the combination of reference cell sets affects the estimation results of reference-based deconvolution methods and established a liver-specific deconvolution by optimizing the reference cell set for each cell to be estimated. We applied this model to independent datasets and showed that liver-specific modeling is highly extrapolatable. We expect that this approach will enable sophisticated estimation from rich tissue data accumulated in public databases and to obtain information on aggregated immune cell trafficking.

Resolvin D1 promotes the resolution of inflammation in the ACLF rat model by increasing the proportion of Treg cells

OBJECTIVE

Acute-on-chronic liver failure (ACLF) causes organ system failures in patients and increases the risk of mortality. One of the main predictors of ACLF development in patients is the severity of systemic inflammation. The purpose of this study was to explore the effects of resolvin D1 (RvD1) on the rat model of ACLF.

METHODS

The ACLF rats were induced by first intraperitoneally (ip) injecting CCl4 and porcine serum for 6 weeks to establish the chronic liver injury, followed by once administration (ip) of lipopolysaccharide and d-galactose d-GalN to cause acute liver injury (ALI). An hour before the ALI-induced treatment, rats were administrated (ip) with 0.9% saline or different doses of RvD1 (0.3 or 1 µg/kg). Afterward, the control and treated rats were killed and samples were collected. Biochemical analysis, hematoxylin-eosin and Sirius red staining, flow cytometry assay, and real-time polymerase chain reaction were used to assess the rat liver histopathological injury, the percentage of Treg cells in the spleen, and the messenger RNA (mRNA) levels of transcription factors and immunologic cytokines in liver.

RESULTS

The necroinflammatory scores and the serum levels of transaminase significantly increased in ACLF rats compared with those in control rats. These impaired changes observed in ACLF rats could be attenuated by the administration of a low dose of RvD1 before the induction of ALI, which was associated with the increased proportion of regulatory T cells (Treg) in the spleen together with the increased gene expression ratio of Foxp3/RORγt and decreased mRNA level of Il-17a and Il-6 in the liver.

CONCLUSION

A low dose of RvD1 can promote the resolution of inflammation in ACLF rats by increasing the proportion of Treg cells. RvD1, therefore, may be used as a potential drug for the treatment of patients with ACLF.

Pharmacological effects of mTORC1/C2 inhibitor in a preclinical model of NASH progression

Knowledge of the benefits of mTOR inhibition concerning adipogenesis and inflammation has recently encouraged the investigation of a new generation of mTOR inhibitors for non-alcoholic steatohepatitis (NASH). We investigated whether treatment with a specific mTORC1/C2 inhibitor (Ku-0063794; KU) exerted any beneficial impacts on experimentally-induced NASH in vitro and in vivo. The results indicated that KU decreases palmitic acid-induced lipotoxicity in cultivated primary hepatocytes, thus emerging as a successful candidate for testing in an in vivo NASH dietary model, which adopted the intraperitoneal KU dosing route rather than oral application due to its significantly greater bioavailability in mice. The pharmacodynamics experiments commenced with the feeding of male C57BL/6 mice with a high-fat atherogenic western-type diet (WD) for differing intervals over several weeks aimed at inducing various phases of NASH. In addition to the WD, the mice were treated with KU for 3 weeks or 4 months. Acute and chronic KU treatments were observed to be safe at the given concentrations with no toxicity indications in the mice. KU was found to alleviate NASH-related hepatotoxicity, mitochondrial and oxidative stress, and decrease the liver triglyceride content and TNF-α mRNA in at least one set of in vivo experiments. The KU modulated liver expression of selected metabolic and oxidative stress-related genes depended upon the length and severity of the disease. Although KU failed to completely reverse the histological progression of NASH in the mice, we demonstrated the complexity of mTORC1/C2 signaling regulation and suggest a stratified therapeutic management approach throughout the disease course.

System Biology Investigation Revealed Lipopolysaccharide and Alcohol-Induced Hepatocellular Carcinoma Resembled Hepatitis B Virus Immunobiology and Pathogenesis

Hepatitis B infection caused by the hepatitis B virus is a life-threatening cause of liver fibrosis, cirrhosis, and hepatocellular carcinoma. Researchers have produced multiple in vivo models for hepatitis B virus (HBV) and, currently, there are no specific laboratory animal models available to study HBV pathogenesis or immune response; nonetheless, their limitations prevent them from being used to study HBV pathogenesis, immune response, or therapeutic methods because HBV can only infect humans and chimpanzees. The current study is the first of its kind to identify a suitable chemically induced liver cirrhosis/HCC model that parallels HBV pathophysiology. Initially, data from the peer-reviewed literature and the GeneCards database were compiled to identify the genes that HBV and seven drugs (acetaminophen, isoniazid, alcohol, D-galactosamine, lipopolysaccharide, thioacetamide, and rifampicin) regulate. Functional enrichment analysis was performed in the STRING server. The network HBV/Chemical, genes, and pathways were constructed by Cytoscape 3.6.1. About 1546 genes were modulated by HBV, of which 25.2% and 17.6% of the genes were common for alcohol and lipopolysaccharide-induced hepatitis. In accordance with the enrichment analysis, HBV activates the signaling pathways for apoptosis, cell cycle, PI3K-Akt, TNF, JAK-STAT, MAPK, chemokines, NF-kappa B, and TGF-beta. In addition, alcohol and lipopolysaccharide significantly activated these pathways more than other chemicals, with higher gene counts and lower FDR scores. In conclusion, alcohol-induced hepatitis could be a suitable model to study chronic HBV infection and lipopolysaccharide-induced hepatitis for an acute inflammatory response to HBV.

The sirtuin family in health and disease

Sirtuins (SIRTs) are nicotine adenine dinucleotide(+)-dependent histone deacetylases regulating critical signaling pathways in prokaryotes and eukaryotes, and are involved in numerous biological processes. Currently, seven mammalian homologs of yeast Sir2 named SIRT1 to SIRT7 have been identified. Increasing evidence has suggested the vital roles of seven members of the SIRT family in health and disease conditions. Notably, this protein family plays a variety of important roles in cellular biology such as inflammation, metabolism, oxidative stress, and apoptosis, etc., thus, it is considered a potential therapeutic target for different kinds of pathologies including cancer, cardiovascular disease, respiratory disease, and other conditions. Moreover, identification of SIRT modulators and exploring the functions of these different modulators have prompted increased efforts to discover new small molecules, which can modify SIRT activity. Furthermore, several randomized controlled trials have indicated that different interventions might affect the expression of SIRT protein in human samples, and supplementation of SIRT modulators might have diverse impact on physiological function in different participants. In this review, we introduce the history and structure of the SIRT protein family, discuss the molecular mechanisms and biological functions of seven members of the SIRT protein family, elaborate on the regulatory roles of SIRTs in human disease, summarize SIRT inhibitors and activators, and review related clinical studies.

Bromelain ameliorates D-galactosamine-induced acute liver injury: role of SIRT1/LKB1/AMPK, GSK3β/Nrf2 and NF-κB p65/TNF-α/caspase-8, -9 signalling pathways

OBJECTIVES

The present research focused on estimating, for the first time, the potential protective effects of bromelain against D-galactosamine-induced acute liver injury in rats as well as identifying the possible underlying mechanisms.

METHODS

Silymarin (100 mg/kg/day, p.o.) as a reference drug or bromelain (20 and 40 mg/kg/day, p.o.) were administered for 10 days, and on the 8th day of the experiment, a single dose of galactosamine (400 mg/kg/i.p.) induced acute liver injury.

KEY FINDINGS

Pretreatment with bromelain improved liver functions and histopathological alterations induced by galactosamine. Bromelain ameliorated oxidative stress by inducing SIRT1 protein expression and increasing LKB1 content. This resulted in phosphorylating the AMPK/GSK3β axis, which stimulated Nrf2 activation in hepatic cells and thus increased the activity of its downstream antioxidant enzymes [HO-1 and NQO1]. Besides, bromelain exerted significant anti-apoptotic and anti-inflammatory effects by suppressing hepatic contents of TNF-α, NF-κB p65, as well as caspase-8 and caspase-9. The protective effects of bromelain40 were proved to be better than silymarin and bromelain20 in most of the assessed parameters.

CONCLUSIONS

Our results highlight the significant hepatoprotective effects of bromelain against acute liver injury through modulation of SIRT1/LKB1/AMPK, GSK3β/Nrf2 signalling in addition to NF-κB p65/TNF-α/ caspase-8 and -9 pathway.

Blood Coral Polysaccharide Helps Prevent D-Gal/LPS-Induced Acute Liver Failure in Mice

Objective

The liver protection of blood coral polysaccharide (BCP) was investigated.

Materials and Methods

We evaluated the effect of BCP on liver pathology, liver function, oxidation and inflammation-related indicators of D-Gal/LPS-induced acute liver failure (ALF) mice in vivo.

Results

Liver index and liver pathology observation in mice showed that BCP could inhibit liver tissue swelling and hemorrhage, hepatocyte damage, and inflammatory infiltration in ALF. Serum liver function results showed that BCP effectively inhibits the levels of aspartate aminotransferase (AST), alanine aminotransferase (ALT), lactate dehydrogenase (LDH), total bilirubin (TBil), alkaline phosphatase (AKP), myeloperoxidase (MPO). High dose-blood coral polysaccharide (H-BCP) was better than silymarin. Serum antioxidant and immune results showed that BCP increased the levels of superoxide dismutase (SOD), catalase (CAT), glutathione (GSH), and glutathione peroxidase (GSH-Px), and inhibited the levels of malondialdehyde (MDA) and nitric oxide (NO). Also, BCP increased immunoglobulins G (IgG) and A (IgA) levels, thereby enhancing humoral immunity. Liver anti-inflammatory ELISA results showed that BCP reduced the levels of interleukin (IL)-6, IL-1β, IL-17, tumor necrosis factor (TNF)-α, and interferon (IFN)-γ, and enhanced the level of anti-inflammatory factor IL-10. H-BCP was the most effective treatment. Real-time quantitative reverse transcription-polymerase chain reaction (RT-qPCR) of liver tissues confirmed that BCP increases the relative expression levels of antioxidant and anti-inflammatory-related cuprozinc superoxide dismutase (Cu/Zn-SOD, SOD1), manganese superoxide dismutase (Mn-SOD, SOD2), CAT, GSH, GSH-Px, and IL-10. In contrast, it inhibits inflammation-related genes IL-6, IL-1β, IL-17, TNF-α, IFN-γ, inducible nitric oxide synthase (iNOS, NOS2), and cyclooxygenase (COX)-2. In addition, BCP also inhibits the nuclear factor κ-light-chain-enhancer of activated B cells (NF-κB) and enhance B-cell inhibitor-α (IκB-α) gene relative expression in the liver, which may be related to NF-κB pathway inhibition.

Conclusion

BCP prevents D-Gal/LPS-induced ALF in mice, and its effect is concentration dependent.

Combination of resveratrol and luteolin ameliorates α-naphthylisothiocyanate-induced cholestasis by regulating the bile acid homeostasis and suppressing oxidative stress

Cholestasis is a common liver injury without any effective therapeutic drugs so far. Resveratrol (RES) and luteolin (LUT) are natural polyphenols that exert protective effects on multiple liver injuries. Coadministration of RES and LUT could significantly improve the bioavailability of LUT and increase the systemic exposure to RES, and the combined treatment could also benefit from their multi-component and multi-target characteristics. Our current aim is to study the protective effects of coadministration of RES and LUT on α-naphthylisothiocyanate (ANIT)-induced cholestasis. Serum biochemical indices and liver histopathology in rats indicated that coadministration of RES and LUT could improve liver function by suppressing oxidative stress. Dysregulated bile acid (BA) homeostasis is a significant pathological feature of cholestasis, which was determined to explore the potential biomarkers and to clarify the protection mechanism of coadministration of RES and LUT. The levels of cholic acid, chenodeoxycholic acid, taurine conjugates and glycine conjugates, and the ratios of taurine conjugates to their free forms could be used as diagnosis indicators for cholestasis in rats. Furthermore, the coadministration of RES and LUT could restore the BA levels and exert better protective effects than administration alone. This study suggested that the coadministration of RES and LUT could protect against ANIT-induced cholestasis and the mechanism was closely related to regulating BA homeostasis and suppressing oxidative stress.

Animal models applied to acute-on-chronic liver failure: Are new models required to understand the human condition?

The liver is a multifaceted organ; its location and detoxifying function expose this organ to countless injuries. Acute-on-chronic failure liver (ACLF) is a severe syndrome that affects the liver due to acute decompensation in patients with chronic liver disease. An infection environment, ascites, increased liver enzymes and prothrombin time, encephalopathy and fast-evolving multiorgan failure, leading to death, usually accompany this. The pathophysiology remains poorly understand. In this context, animal models become a very useful tool in this regard, as understanding; the disease may be helpful in developing novel therapeutic methodologies for ACLF. However, although animal models display several similarities to the human condition, they do not represent all ACLF manifestations, resulting in significant challenges. An initial liver cirrhosis framework followed by the induction of an acute decompensation by administering lipopolysaccharide and D-GaIN, potentiating liver damage supports the methodologies applied to induce experimental ACLF. The entire methodology has been described mostly for rats. Nevertheless, a quick PubMed database search indicates about 30 studies concerning ACFL models and over 1000 regarding acute liver failure models. These findings demonstrate the clear need to establish easily reproducible ACFL models to elucidate questions about this quickly established and often fatal syndrome.

Animal models applied to acute-on-chronic liver failure: Are new models required to understand the human condition?

The liver is a multifaceted organ; its location and detoxifying function expose this organ to countless injuries. Acute-on-chronic failure liver (ACLF) is a severe syndrome that affects the liver due to acute decompensation in patients with chronic liver disease. An infection environment, ascites, increased liver enzymes and prothrombin time, encephalopathy and fast-evolving multiorgan failure, leading to death, usually accompany this. The pathophysiology remains poorly understand. In this context, animal models become a very useful tool in this regard, as understanding; the disease may be helpful in developing novel therapeutic methodologies for ACLF. However, although animal models display several similarities to the human condition, they do not represent all ACLF manifestations, resulting in significant challenges. An initial liver cirrhosis framework followed by the induction of an acute decompensation by administering lipopolysaccharide and D-GaIN, potentiating liver damage supports the methodologies applied to induce experimental ACLF. The entire methodology has been described mostly for rats. Nevertheless, a quick PubMed database search indicates about 30 studies concerning ACFL models and over 1000 regarding acute liver failure models. These findings demonstrate the clear need to establish easily reproducible ACFL models to elucidate questions about this quickly established and often fatal syndrome.

The Protective Effects of a Modified Xiaohua Funing Decoction against Acute Liver Failure in Mice Induced by D-Gal and LPS

Objective

The aim of this study was to evaluate the effects of a modified Xiaohua Funing decoction (Xfd) on acute liver failure (ALF) and determine whether the protective mechanisms are related to alterations in the gut microbiota.

Methods

An animal model of ALF was induced by intraperitoneal injection of D-galactosamine (D-Gal, 0.5 g/kg) and lipopolysaccharide (LPS, 100 μg/kg). Male BALB/c mice were randomly divided into the following 4 groups: the control group (saline, Con), model group (D-Gal/LPS, Mod), silymarin pretreatment group (200 mg/kg, Sil), and modified Xfd pretreatment group (650 mg/kg, Xfd). The Sil and Xfd groups received the respective intervention orally for 14 days and 2 h before D-Gal/LPS treatment. The liver injury markers included alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels and liver histology. 16S rRNA gene sequencing was performed to assess the effects on the caecum content.

Results

D-Gal/LPS treatment caused severe ALF, illustrating that the ALF model was successfully established. The administration of Sil and Xfd greatly reduced the serum ALT and AST levels and improved the pathological signs of liver injury. However, no significant difference was found between the two groups. In contrast to the Mod group, the Sil and Xfd groups showed a shift toward the Con group in terms of the gut microbiota structure. The abundances of Firmicutes and Bacteroidetes and the Bacteroidetes/Firmicutes ratio in the Mod group significantly differed from those in the Con group. The Sil and Xfd groups showed restoration of the disordered microbiota. Significantly increased relative abundances of Lachnospiraceae_NK4A136_group and Candidatus_Saccharimonas and a markedly decreased Muribaculaceae abundance were found in the Sil and Xfd mice compared with those in the Mod mice (P < 0.01, P < 0.05). Interestingly, a negative correlation was observed between the abundances of the gut microbiota constituents, specifically Clostridia_UCG-014, and ALT and AST levels.

Conclusion

In summary, our results indicate that Xfd may protect the liver and modify the gut microbiota in ALF mice.

Chinese medicine in the treatment of autoimmune hepatitis: Progress and future opportunities

Autoimmune hepatitis (AIH) is a chronic inflammatory liver disease occurring in individuals of all ages with a higher incidence in females and characterized by hypergammaglobulinemia, elevated serum autoantibodies and histological features of interface hepatitis. AIH pathogenesis remains obscure and still needs in‐depth study, which is likely associated with genetic susceptibility and the loss of immune homeostasis. Steroids alone and in combination with other immunosuppressant agents are the primary choices of AIH treatment in the clinic, whereas, in some cases, severe adverse effects and disease relapse may occur. Chinese medicine used for the treatment of AIH has proven its merits over many years and is well tolerated. To better understand the pathogenesis of AIH and to evaluate the efficacy of novel therapies, several animal models have been generated to recapitulate the immune microenvironment of patients with AIH. In the current review, we summarize recent advances in the study of animal models for AIH and their application in pharmacological research of Chinese medicine‐based therapies and also discuss current limitations. This review aims to provide novel insights into the discovery of Chinese medicine‐originated therapies for AIH using cutting‐edge animal models.

Oyster-Derived Tyr-Ala (YA) Peptide Prevents Lipopolysaccharide/D-Galactosamine-Induced Acute Liver Failure by Suppressing Inflammatory, Apoptotic, Ferroptotic, and Pyroptotic Signals

Models created by the intraperitoneal injection of lipopolysaccharide (LPS) and D-galactosamine (D-GalN) have been widely used to study the pathogenesis of human acute liver failure (ALF) and drug development. Our previous study reported that oyster (Crassostrea gigas) hydrolysate (OH) had a hepatoprotective effect in LPS/D-GalN-injected mice. This study was performed to identify the hepatoprotective effect of the tyrosine-alanine (YA) peptide, the main component of OH, in a LPS/D-GalN-injected ALF mice model. We analyzed the effect of YA on previously known mechanisms of hepatocellular injury in the model. LPS/D-GalN-injected mice showed inflammatory, apoptotic, ferroptotic, and pyroptotic liver injury. The pre-administration of YA (10 mg/kg or 50 mg/kg) significantly reduced the liver damage factors. The hepatoprotective effect of YA was higher in the 50 mg/kg YA pre-administered group than in the 10 mg/kg YA pre-administered group. These results showed that YA had a hepatoprotective effect by reducing inflammation, apoptosis, ferroptosis, and pyroptosis in the LPS/D-GalN-injected ALF mouse model. We suggest that YA can be used as a functional peptide for the prevention of acute liver injury.

Protective Effects of Microbiome-Derived Inosine on Lipopolysaccharide-Induced Acute Liver Damage and Inflammation in Mice via Mediating the TLR4/NF-κB Pathway

This research assessed the anti-inflammatory and hepatoprotective properties of inosine and the associated mechanism. Inosine pretreatment significantly reduced the secretion of several inflammatory factors and serum alanine transaminase (ALT) and aspartate amino transferase (AST) levels in a dose-dependent manner compared with the lipopolysaccharide (LPS) group. In LPS-treated mice, inosine pretreatment significantly reduced the ALT and malondialdehyde (MDA) concentration and significantly elevated the antioxidant enzyme activity. Furthermore, inosine pretreatment significantly altered the relative abundance of the genera, Bifidobacterium, Lachnospiraceae UCG-006, and Muribaculum. Correlation analysis showed that Bifidobacterium and Lachnospiraceae UCG-006 were positively related to the cecal short-chain fatty acids but negatively related to the serum IL-6 and hepatic AST and ALT levels. Notably, inosine pretreatment significantly modulated the hepatic TLR4, MYD88, NF-κB, iNOS, COX2, AMPK, Nfr2, and IκB-α expression. These results suggested that inosine pretreatment alters the intestinal microbiota structure and improves LPS-induced acute liver damage and inflammation through modulating the TLR4/NF-κB signaling pathway.

Gensenoside Rg1 protects against lipopolysaccharide- and d-galactose-induced acute liver failure via suppressing HMGB1-mediated TLR4-NF-κB pathway

AIM

Acute liver failure (ALF) is a life-threatening acute liver injury (ALI) with high mortality. Gensenoside Rg1 (G-Rg1) effects on Lipopolysaccharide- (LPS-) and d-galactose-(D-gal-) induced ALI, but its effects on ALF remained unclear. This paper aimed to validate its possible efficacy on ALF prevention.

METHODS

For in vivo studies, histological examination was performed using hematoxylin-eosin (H&E) staining, and alanine aminotransferase (ALT), aspartate aminotransminase (AST), malondialdehyde (MDA), superoxide dismutase (SOD) and glutathione (GSH) contents were measured. Levels of inflammatory cytokines tumor necrosis factor-α (TNF-α) and Interleukin-6 (IL-6) were quantified via enzyme-linked immunosorbent assay (ELISA). Human bronchial epithelial cell line BEAS-2B was used for ALF model in vitro and its viability was measured by MTT assay. Expressions of high mobility group box 1 (HMGB1) and toll-like receptor 4-Nuclear Factor-κB (TLR4-NF-κB) pathway-related proteins were measured by quantitative real-time polymerase chain reaction (qRT-PCR) and Western blot as needed.

RESULTS

G-Rg1 relieved LPS- and D-gal-induced hepatic injury, and reduced ALT, AST and MDA levels but upregulated SOD and GSH levels, with downregulation on TNF-α and IL-6 levels. Expressions of HMGB1, TLR4 and NF-κB pathway-related proteins were also down-regulated after G-Rg1 treatment both in vivo and in vitro, while BEAS-2B cell viability was increased. However, overexpressed HMGB1 reversed the effects of G-Rg1 treatment in vitro.

CONCLUSION

G-Rg1 had a protective effect against LPS- and D-gal-induced ALF both in vitro and in vivo, which might be related to inhibited HMGB1-mediated TLR4-NF-κB Pathway. These discoveries suggested that G-Rg1 could be a potential agent for prevention against ALF.

Intraportally delivered stem cell spheroids localize in the liver and protect hepatocytes against GalN/LPS-induced fulminant hepatic toxicity

Background

Systemic inflammatory response syndrome (SIRS) is common in severe fulminant hepatic failure (FHF) and has a high mortality rate (20–50%) due to irreversible cerebral edema or sepsis. Stem cell-based treatment has emerged as a promising alternative therapeutic strategy to prolong the survival of patients suffering from FHF via the inhibition of SIRS due to their immunomodulatory effects.

Methods

3D spheroids of adipose-derived mesenchymal stem cells (3D-ADSC) were prepared by the hanging drop method. The efficacy of the 3D-ADSC to rescue FHF was evaluated in a d-galactosamine/lipopolysaccharide (GalN/LPS)-induced mouse model of FHF via intraportal transplantation of the spheroids.

Results

Intraportally delivered 3D-ADSC better engrafted and localized into the damaged livers compared to 2D-cultured adipose-derived mesenchymal stem cells (2D-ADSC). Transplantation of 3D-ADSC rescued 50% of mice from FHF-induced lethality, whereas only 20% of mice survived when 2D-ADSC were transplanted. The improved transplantation outcomes correlated with the enhanced immunomodulatory effect of 3D-ADSC in the liver microenvironment.

Conclusion

The study shows that the transplantation of optimized 3D-ADSC can efficiently ameliorate GalN/LPS-induced FHF due to improved viability, resistance to exogenous ROS, and enhanced immunomodulatory effects of 3D-ADSC.

Electronic supplementary material

The online version of this article (10.1186/s13287-019-1337-3) contains supplementary material, which is available to authorized users.

Luteolin and luteolin-7-O-glucoside protect against acute liver injury through regulation of inflammatory mediators and antioxidative enzymes in GalN/LPS-induced hepatitic ICR mice

BACKGROUND/OBJECTIVES

Anti-inflammatory and antioxidative activities of luteolin and luteolin-7-O-glucoside were compared in galactosamine (GalN)/lipopolysaccharide (LPS)-induced hepatitic ICR mice.

MATERIALS/METHODS

Male ICR mice (6 weeks old) were divided into 4 groups: normal control, GalN/LPS, luteolin, and luteolin-7-O-glucoside groups. The latter two groups were administered luteolin or luteolin-7-O-glucoside (50 mg/kg BW) daily by gavage for 3 weeks after which hepatitis was induced by intraperitoneal injection of GalN and LPS (1 g/kg BW and 10 µg/kg BW, respectively).

RESULTS

GalN/LPS produced acute hepatic injury by a sharp increase in serum AST, ALT, and TNF-α levels, increases that were ameliorated in the experimental groups. In addition, markedly increased expressions of cyclooxygenase (COX)-2 and its transcription factors, nuclear factor (NF)-κB and activator protein (AP)-1, were also significantly attenuated in the experimental groups. Compared to luteolin-7-O-glucoside, luteolin more potently ameliorated the levels of inflammatory mediators. Phase II enzymes levels and NF-E2 p45-related factor (Nrf)-2 activation that were decreased by GalN/LPS were increased by luteolin and luteolin-7-O-glucoside administration. In addition, compared to luteolin, luteolin-7-O-glucoside acted as a more potent inducer of changes in phase II enzymes. Liver histopathology results were consistent with the mediator and enzyme results.

CONCLUSION

Luteolin and luteolin-7-O-glucoside protect against GalN/LPS-induced hepatotoxicity through the regulation of inflammatory mediators and phase II enzymes.

SIRT1 Modulators in Experimentally Induced Liver Injury

This article is directed at highlighting the involvement of the endogenous stress sensor SIRT1 (silent information regulator T1) as a possible factor involved in hepatoprotection. The selective SIRT1 modulators whether activators (STACs) or inhibitors are being tried experimentally and clinically. We discuss the modulation of SIRT1 on cytoprotection or even cytotoxicity in the liver chemically injured by hepatotoxic agents in rats, to shed light on the crosstalk between SIRT1 and its modulators. A combination of D-galactosamine and lipopolysaccharide (D-GalN/LPS) downregulated SIRT1 expression, while SIRT1 activators, SRT1720, resveratrol, and quercetin, upregulated SIRT1 and alleviated D-GalN/LPS-induced acute hepatotoxicity. Liver injury markers exhibited an inverse relationship with SIRT1 expression. However, under subchronic hepatotoxicity, quercetin decreased the significant increase in SIRT1 expression to lower levels which are still higher than normal ones and mitigated the liver-damaging effects of carbon tetrachloride. Each of these STACs was hepatoprotective and returned the conventional antioxidant enzymes to the baseline. Polyphenols tend to fine-tune SIRT1 expression towards normal in the liver of intoxicated rats in both acute and subchronic studies. Together, all these events give an impression that the cytoprotective effects of SIRT1 are exhibited within a definite range of expression. The catalytic activity of SIRT1 is important in the hepatoprotective effects of polyphenols where SIRT1 inhibitors block and the allosteric SIRT1 activators mimic the hepatoprotective effects of polyphenols. Our findings indicate that the pharmacologic modulation of SIRT1 could represent both an important move in alleviating hepatic insults and a future major step in the treatment of xenobiotic-induced hepatotoxicity.

Protective Effects of Sesquiterpenoids from the Root of Panax ginseng on Fulminant Liver Injury Induced by Lipopolysaccharide/d-Galactosamine

It is reported that sesquiterpenoids from Panax ginseng (SPG) possess various pharmacological activities, for example, antidepressant, antioxidative, and anti-inflammatory activities. The purpose of this study was to examine the hepatoprotective effects of SPG (2.5 and 10 mg/kg, i.g.) on fulminant liver injury induced by d-galactosamine (d-GalN) and lipopolysaccharide (LPS) and discuss its mechanisms of action. After 24 h of d-GalN (400 mg/kg, i.p.) and LPS (25 μg/kg, i.p.) exposure, the serum levels of alanine transaminase (ALT) and aspartate transaminase (AST), hepatic malondialdehyde (MDA) level, hepatic activities of superoxide dismutase (SOD), catalase (CAT), and glutathione (GSH), and hepatic tissue histology were measured. Expression levels of tumor necrosis factor α (TNF-α) and interleukin-1β (IL-1β) were detected by enzyme-linked immunosorbent assay and real-time polymerase chain reaction. Moreover, the nuclear factor κ-light-chain-enhancer of activated B cell (NF-κB), nuclear factor erythroid 2-related factor 2 (Nrf2), sirtuin type 1 (Sirt 1), and heme oxygenase 1 (HO-1) were determined by western blotting. The results indicated that SPG evidently restrained the increase of serum ALT and AST levels induced by d-GalN/LPS. SPG obviously downregulated TNF-α and IL-1β levels and their mRNA expression in liver. In addition, d-GalN/LPS injection induced severe oxidative stress in liver by boosting the MDA level as well as decreasing CAT, GSH, and SOD capacities, and SPG reversed these changes. Meanwhile, SPG inhibited NF-κB activation induced by d-GalN/LPS and upregulated Sirt 1, Nrf2, and HO-1 expression levels. Therefore, SPG might protect against the fulminant liver injury induced by d-GalN/LPS via inhibiting inflammation and oxidative stress. The protective effect of SPG on fulminant liver injury induced by d-GalN/LPS might be mediated by the Sirt 1/Nrf2/NF-κB signaling pathway. All of these results implied that SPG might be a promising food additive and therapeutic agent for fulminant liver injury.

Nerve growth factor upregulates sirtuin 1 expression in cholestasis: a potential therapeutic target

This study investigated the regulatory role of nerve growth factor (NGF) in sirtuin 1 (SIRT1) expression in cholestatic livers. We evaluated the expression of NGF and its cognate receptors in human livers with hepatolithiasis and the effects of NGF therapy on liver injury and hepatic SIRT1 expression in a bile duct ligation (BDL) mouse model. Histopathological and molecular analyses showed that the hepatocytes of human diseased livers expressed NGF, proNGF (a precursor of NGF), TrkA and p75NTR, whereas only p75NTR was upregulated in hepatolithiasis, compared with non-hepatolithiasis livers. In the BDL model without NGF therapy, p75NTR, but not TrkA antagonism, significantly deteriorated BDL-induced liver injury. By contrast, the hepatoprotective effect of NGF was abrogated only by TrkA and not by p75NTR antagonism in animals receiving NGF therapy. Intriguingly, a positive correlation between hepatic SIRT1 and NGF expression was found in human livers. In vitro studies demonstrated that NGF upregulated SIRT1 expression in mouse livers and human Huh-7 and rodent hepatocytes. Both NGF and proNGF induced protective effects against hydrogen peroxide-induced cytotoxicity in Huh-7 cells, whereas inhibition of TrkA and p75NTR activity prevented oxidative cell death. Mechanistically, NGF, but not proNGF, upregulated SIRT1 expression in human Huh-7 and rodent hepatocytes via nuclear factor (NF)-κB activity, whereas NGF-induced phosphoinositide-3 kinase/Akt, extracellular signal–regulated kinase and NF-κB signaling and SIRT1 activity were involved in its hepatoprotective effects against oxidative injury. These findings suggest that pharmacological manipulation of the NGF/SIRT1 axis might serve as a novel approach for the treatment of cholestatic disease.

Berberine protects acute liver failure in mice through inhibiting inflammation and mitochondria-dependent apoptosis

Acute liver failure (ALF) is characterized by sudden large area of inflammation and extensive hepatocyte apoptosis. This study identified the natural product berberine as a potential agent for acute liver failure(ALF). First, in vitro, BBR pre-incubation (5, 10 and 20μM) alleviated L02 hepatocytes injury induced by D-GalN (5mM)/TNF-α (100ng/ml). Second, in vivo, BBR pre-treatment attenuated D-Galactosamine (D-GalN)/lipopolysaccharide (LPS)-induced acute liver failure, as evidenced by the reduction of mortality, the alleviation of liver pathological changes and the inhibition of alanine aminotransferase (ALT)/aspartate aminotransferase (AST). Our results further illustrated that BBR inhibited the nuclear translocation of NF-κB p65 and subsequently suppressed the expressions of inflammatory cytokines, tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) at both mRNA and protein levels in ALF. Moreover, western blotting demonstrated that BBR effectively inhibited apoptosis via reducing cytochrome c release, Bax/Bcl-2 ratio and caspase-3/-9 cleavage in vitro and in vivo. In conclusion, our findings suggest that BBR serves as a potential agent for preventing or treating human ALF by inhibiting inflammation and mitochondria-dependent apoptosis.

Protective Effect of Unacylated Ghrelin on Compression-Induced Skeletal Muscle Injury Mediated by SIRT1-Signaling

Unacylated ghrelin, the predominant form of circulating ghrelin, protects myotubes from cell death, which is a known attribute of pressure ulcers. In this study, we investigated whether unacylated ghrelin protects skeletal muscle from pressure-induced deep tissue injury by abolishing necroptosis and apoptosis signaling and whether these effects were mediated by SIRT1 pathway. Fifteen adult Sprague Dawley rats were assigned to receive saline or unacylated ghrelin with or without EX527 (a SIRT1 inhibitor). Animals underwent two 6-h compression cycles with 100 mmHg static pressure applied over the mid-tibialis region of the right limb whereas the left uncompressed limb served as the intra-animal control. Muscle tissues underneath the compression region, and at the similar region of the opposite uncompressed limb, were collected for analysis. Unacylated ghrelin attenuated the compression-induced muscle pathohistological alterations including rounding contour of myofibers, extensive nucleus accumulation in the interstitial space, and increased interstitial space. Unacylated ghrelin abolished the increase in necroptosis proteins including RIP1 and RIP3 and attenuated the elevation of apoptotic proteins including p53, Bax, and AIF in the compressed muscle. Furthermore, unacylated ghrelin opposed the compression-induced phosphorylation and acetylation of p65 subunit of NF-kB. The anti-apoptotic effect of unacylated ghrelin was shown by a decrease in apoptotic DNA fragmentation and terminal dUTP nick-end labeling index in the compressed muscle. The protective effects of unacylated ghrelin vanished when co-treated with EX527. Our findings demonstrated that unacylated ghrelin protected skeletal muscle from compression-induced injury. The myoprotective effects of unacylated ghrelin on pressure-induced tissue injury were associated with SIRT1 signaling.

Sirtuin-Activating Compounds (STACs) Alleviate D-Galactosamine/Lipopolysaccharide-Induced Hepatotoxicity in Rats: Involvement of Sirtuin 1 and Heme Oxygenase 1

Sirtuin activating compounds (STACs) attenuate various type of liver insults through mechanisms which are not fully understood. In the present study, we investigated the ameliorative potential of quercetin (natural polyphenol) and SRT1720 (synthetic SIRT1 activator) against D-galactosamine/lipopolysaccharide-induced hepatotoxicity (an experimental model of acute liver failure). Moreover, we compared and contrasted the roles of stress responsive enzymes, sirtuin 1 (SIRT1) and heme oxygenase 1 (HO-1) in hepatoprotection/ hepatotoxicity. Liver injury was induced in male Wistar rats by intraperitoneal injection of D-galactosamine (400 mg/kg) and lipopolysaccharide (10 µg/kg). Some animals were pretreated with quercetin (50 mg/kg i.p.) or SRT1720 (5 mg/kg i.p.). Twenty-four hours later, the effects of these treatments were evaluated by biochemical studies and Western blot. D-GalN/LPS treatment upregulated HO-1 expression, downregulated SIRT1 expression, decreased AST:ALT ratio and markedly increased bilirubin, catalase and conjugated diene levels. Pretreatment of D-GalN/LPS rats with either quercetin or SRT1720 returned SIRT1 expression, HO-1 expression and all the aforementioned markers towards normal. Collectively, these findings suggest that elevated HO-1 and low SIRT1 expressions are involved in the pathogenesis of D-GalN/LPS-induced hepatotoxicity. Drugs that downregulate HO-1 and/or upregulate SIRT1 seem to have antihepatotoxic effects and need further exploration.

The angiotensin-converting enzyme inhibitor captopril rescues mice from endotoxin-induced lethal hepatitis

The renin–angiotensin system is classically regarded as a crucial regulator of circulatory homeostasis, but recent studies also revealed its pro-inflammatory roles. The beneficial effects of the angiotensin-converting enzyme inhibitor (ACEI) in severe inflammatory injury in the lung and heart have been previously reported, but its potential effects on lethal hepatitis were unknown. In this study, a mouse model with LPS/d-galactosamine (GalN)-induced fulminant hepatitis were used to test the protective potential of captopril, a representative ACEI. The results indicated that treatment with captopril significantly decreased the plasma level of alanine aminotransferase and aspartate aminotransferase, alleviated the histopathological damage of the liver tissue and improve the survival rate of LPS/GalN-challenged mice. These effects were accompanied by reduced mRNA levels of TNF-α and IL-6 in the liver, and decreased protein level of TNF-α and IL-6 in the plasma. In addition, the activation of caspases 3, 8 and 9, and the presence of TUNEL-positive apoptotic cells, were also suppressed by captopril treatment. The above evidence suggested that the renin–angiotensin system might be involved in the development of LPS/GalN-induced fulminant hepatitis and ACEI might have potential value in lethal hepatitis.

Inactivation of Sirt1 in mouse livers protects against endotoxemic liver injury by acetylating and activating NF-κB

Sirtuin 1 (Sirt1) is a deacetylase that regulates many cellular processes in the liver, and so far its role in endotoxemic liver injury is elusive. So we conditionally inactivate Sirt1 in murine hepatocytes to determine its role in d-galactosamine (GalN)/lipopolysaccharide (LPS)-induced liver damage, which is a well-established experimental model mimicking septic liver injury and fulminant hepatitis. Ablation of Sirt1 shows remarkable protection against GalN/LPS-induced liver injury, which is a result of enhanced NF-κB response because knockdown of RelA/p65 negates the protective effect of Sirt1 knockout. Mechanistically, NF-κB p65 is maintained in a hyperacetylated, DNA-binding competent state in tumor necrosis factor-α (TNF-α)-challenged albumin-Cre⁺ (AlbCre⁺) hepatocytes. Transfection of hepatocytes with a recombinant acetylated p65 expression construct replicates the protection afforded by Sirt1 knockout. Transfection of AlbCre⁺ hepatocytes with a recombinant wild-type Sirt1 construct, rather than a deacetylase-defective one, compromises NF-κB activation and resensitizes hepatocytes to TNF-α-induced apoptosis. Taken together, our results demonstrate that Sirt1 deacetylates p65 and compromises NF-κB activity in hepatocytes when confronted with LPS/TNF-α stimulation, leading to increased susceptibility to endotoxemic injury. These findings identify a possible protein effector to maneuver the hepatic NF-κB signaling pathway under inflammatory circumstances and a feasible way to increase hepatocellular resistance to endotoxin/TNF-α toxicity.

Hepatoprotective effect of grape seed oil against carbon tetrachloride induced oxidative stress in liver of γ-irradiated rat

Carbon tetrachloride (CCl4) and ionizing radiation are well known environmental pollutants that generate free radicals and induce oxidative stress. The liver is the primary and major target organ responsible for the metabolism of drugs, toxic chemicals and affected by irradiation. This study investigated the effect of grape seed oil (GSO) on acute liver injury induced by carbon tetrachloride (CCl4) in γ-irradiated rats (7Gy). CCl4-intoxicated rats exhibited an elevation of ALT, AST activities, IL-6 and TNF-α level in the serum. Further, the levels of MDA, NO, NF-κB and the gene expression of CYP2E1, iNOS and Caspase-3 were increased, and SOD, CAT, GSH-Px, GST activities and GSH content were decreased. Furthermore, silent information regulator protein 1 (SIRT1) gene expression was markedly down-regulated. Additionally, alterations of the trace elements; copper, manganese, zinc and DNA fragmentation was observed in the hepatic tissues of the intoxicated group. These effects were augmented in CCl4-intoxicated-γ-irradiated rats. However, the administration of GSO ameliorated these parameters. GSO exhibit protective effects on CCl4 induced acute liver injury in γ-irradiated rats that could be attributed to its potent antioxidant, anti-inflammatory and anti-apoptotic activities. The induction of the antioxidant enzymes activities, down-regulation of the CYP2E1, iNOS, Caspase-3 and NF-κB expression, up-regulation of the trace elements concentration levels and activation of SIRT1 gene expression are responsible for the improvement of the antioxidant and anti-inflammatory status in the hepatic tissues and could be claimed to be the hepatoprotective mechanism of GSO.