Lactoferrin protects against acetaminophen-induced liver injury in mice

Lactoferrin attenuates cardiac fibrosis and cardiac remodeling after myocardial infarction via inhibiting mTORC1/S6K signaling pathway

Rationale: Myocardial infarction (MI) causes a severe injury response that eventually leads to adverse cardiac remodeling and heart failure. Lactoferrin (Ltf), as a secreted protein, bears multi-pharmacological properties. Present study aims to establish the cardioprotective function and corresponding mechanism of Ltf in MI process. Methods and results: We performed proteomic analysis in Tregs derived from MI heart, and identified Ltf as a remarkably upregulated secreted protein. However, Ltf was decreased in circulation and positively correlated with cardiac function both in mice and patients after MI. Ltf administration remarkably alleviated cardiac fibrosis and remodeling, improved cardiac function, and reduced incidence of heart failure in mice post-MI. In vitro, Ltf suppressed fibroblast to myofibroblast conversion induced by transforming growth factor-β (TGF-β). Mechanistically, phosphoproteomic landscape analysis revealed that Ltf repressed the activation of mTORC1/S6K/eIF-4B signaling pathway via interaction with CD74 receptor. Administration of mTORC1/S6K/eIF-4B axis agonist MHY1485 abolished the cardioprotective effects of Ltf. Besides, MHY1485 also markedly reversed the effects of Ltf on suppressing the transformation of fibroblast to myofibroblast mediated by TGF-β. Conclusion: Our study established the cardiac protective role of Ltf in attenuating cardiac remodeling and improving cardiac function by inhibiting the activation of myofibroblasts through suppressing mTORC1/S6K/eIF-4B signaling pathway post-MI. Treatment with Ltf may serve as a potential novel therapeutic intervention in patients with MI.

Lactoferrin averts neurological and behavioral impairments of thioacetamide-induced hepatic encephalopathy in rats via modulating HGMB1/TLR-4/MyD88/Nrf2 pathway

Hepatic encephalopathy (HE) is a life-threatening disease caused by acute or chronic liver failure manifested by aberrant CNS changes. In the present study, we aimed to explore the neuroprotective effect of lactoferrin (LF) against thioacetamide (TAA)-induced HE in rats. Animals were divided into four groups, control, LF control, TAA-induced HE, and LF treatment, where LF was administered (300 mg/kg, p.o.) for 15 days in groups 2 and 4 meanwhile, TAA (200 mg/kg, i.p.) was given as two injections on days 13 and 15 for the 3rd and 4th groups. Pretreatment with LF significantly improved liver function observed as a marked decline in serum AST, ALT, and ammonia, together with lowering brain ammonia and enhancing motor coordination as well as cognitive performance. Restoration of brain oxidative status was also noted in the LF-treated group, where lipid peroxidation was hampered, and antioxidant parameters, Nrf2, HO-1, and GSH, were increased. Additionally, LF downregulated HMGB1, TLR-4, MyD88, and NF-κB signaling pathways, together with reducing inflammatory cytokine, TNF-α, and enhancing brain BDNF levels. Moreover, the histopathology of brain and liver tissues revealed that LF alleviated TAA-induced liver and brain deficits. In conclusion, the promising results of LF in attenuating HMGB1/TLR-4/MyD88 signaling highlight its neuroprotective role against HE associated with acute liver injury via ameliorating neuroinflammation, oxidative stress, and stimulating neurogenesis.

Ginsenoside Rc, as an FXR activator, alleviates acetaminophen-induced hepatotoxicity via relieving inflammation and oxidative stress

Acetaminophen (APAP) intake leads to excessive NAPQI deposition, stimulating inflammatory and oxidative stress and causing fatal liver injury. However, the detailed molecular mechanism involved is unknown, and effective therapeutic approaches remain insufficient. In this study, we discovered that treatment with ginsenoside Rc can prevent the inflammatory response caused by APAP and oxidative stress in mouse primary hepatocytes (MPHs), along with the corresponding changes in related genes. Additionally, Ginsenoside Rc effectively alleviates APAP-induced cellular apoptosis and NAPQI accumulation in MPHs. In vivo, Ginsenoside Rc administration remarkably attenuates APAP-induced hepatotoxicity, repairing liver damage and improving survival. Moreover, Ginsenoside Rc treatment modulates genes involved in APAP metabolism, leading to a decrease in NAPQI and resulting in the alleviation of fatal oxidative stress and inflammatory response after APAP exposure, along with the expression of their related indicators. Furthermore, our RNA-seq and molecular docking analysis implies that FXR expression and FXR transcriptional activity are stimulated by Ginsenoside Rc treatment. Notably, due to the lack of FXR in mice and MPHs, ginsenoside Rc can no longer play its original protective role against hepatotoxicity and cell damage caused by APAP, and it is difficult to improve the corresponding survival rate and prevent hepatic apoptosis, NAPQI generation, fatal oxidative stress, and the inflammatory response induced by APAP and the expression of related genes. In summary, our results indicate that Ginsenoside Rc could act as an effective FXR activator and effectively regulate FXR-induced antioxidant stress and eliminate inflammation while also having an anti-apoptotic function.

New Properties of a Well-Known Antioxidant: Pleiotropic Effects of Human Lactoferrin in Mice Exposed to Gamma Irradiation in a Sublethal Dose

We studied the effects of human lactoferrin (hLf), a multifunctional protein from the transferrin family, on integral (survival, lifespan during the experiment, body weight, behavior, subfractional compositions of blood serum) and systemic (hemoglobin level, leukocyte number, differential leukocyte count, histological structure of the liver and spleen) parameters of the body in mice after acute gamma irradiation in a sublethal dose. The experiments were performed on male C57BL/6 mice. The mice in the experimental groups were exposed to whole-body gamma radiation in a dose of 7.5 Gy from a ⁶⁰Co source. Immediately after irradiation and 24 h after it, some animals received an intraperitoneal injection of hLf (4 mg/mouse). Single or repeated administration of hLf had a positive pleiotropic effect on irradiated animals: animal survival increased from 28% to 78%, and the mean life expectancy during the experiment (30 days) increased from 16 to 26 days. A compensatory effect of hLf on radiation-induced body weight loss, changes in homeostasis parameters, and a protective effect on the structural organization of the spleen were demonstrated. These data indicate that Lf has potential as a means of early therapy after radiation exposure.

Diacerein ameliorates acetaminophen hepatotoxicity in rats via inhibiting HMGB1/TLR4/NF-κB and upregulating PPAR-γ signal

BACKGROUND

Acetaminophen (APAP) is a worldwide antipyretic as well as an analgesic medication. It has been extensively utilized during the outbreak of coronavirus 2019 (COVID-19). APAP misuse would lead to liver injury. Diacerein (DIA), an anthraquinone derivative, has antioxidant and inflammatory properties. Hence, this study attempted to evaluate the impact of DIA treatment on liver injury induced by APAP and its influence on nuclear factor-κB (NF-κB) /toll-like receptor 4 (TLR4)/high mobility group box-1(HMGB-1) signaling as well as the expression of peroxisome proliferator-activated receptor-gamma (PPAR-γ) expression.

METHODS

Male albino rats received 25 as well as 50 mg/kg/day DIA orally for seven days. One hour after the last administration, rats received APAP (1gm/kg, orally). For histopathological analysis, liver tissues and blood were collected, immunohistochemical (IHC) assay, biochemical assay, as well as quantitative real-time polymerase chain reaction (qRT-PCR).

RESULTS

DIA markedly reduced liver injury markers and ameliorated histopathological changes. Moreover, DIA dose-dependently alleviated oxidative stress status caused by APAP administration along with inflammatory markers, including the level of interleukin-1 beta (IL-1β), myeloperoxidase (MPO), tumor necrosis factor-alpha (TNF-α), and interleukin 6 (IL-6). Furthermore, DIA downregulated protein levels as well as mRNA of HMGB-1, TLR4, NF-κB p65 expression, and enhanced PPAR-γ expression. Moreover, DIA ameliorated apoptotic (Bax) and caspase-3 expressions and increased the anti-apoptotic (Bcl2) expression.

CONCLUSIONS

This study demonstrated that DIA exerts anti-apoptotic, anti-inflammatory, and antioxidant properties against liver injury induced by APAP that is attributed to inhibition of the HMGB1/TLR4/NF-κB pathway, besides upregulation of the expression of PPAR-γ.

Atractylenolide I Ameliorates Acetaminophen-Induced Acute Liver Injury via the TLR4/MAPKs/NF-κB Signaling Pathways

Background: Acetaminophen (APAP) overdose results in the production of reactive oxygen species (ROS), induces hepatocyte necrosis, and leads to acute liver failure. Atractylenolide I (AO-I), a phytochemical found in Atractylodes macrocephala Koidz, is known to exhibit antioxidant activity. However, its clinical benefits against drug-induced liver injury remain largely unclear.

Purpose: This study aimed at evaluating the protective effects of AO-I against APAP-induced acute liver injury.

Methods: C57BL/6 mice were administered 500 mg/kg APAP to induce hepatotoxicity. AO-Ⅰ (60 and 120 mg/kg) was intragastrically administered 2 h before APAP dosing. Liver histopathological changes, oxidative stress and hepatic inflammation markers from each group were observed.

Results: We observed that AO-I treatment significantly reversed APAP-induced liver injury, as evidenced by improved plasma alanine transaminase (ALT) level, aspartate aminotransferase (AST) and liver H&E stain. APAP treatment increased liver malondialdehyde (MDA) content and reduced catalase (CAT) and glutathione (GSH) level; however, these effects were alleviated by AO-I intervention. Moreover, AO-I treatment significantly inhibited APAP-induced activation of pro-inflammatory factors, such as IL-1β, IL-6, and TNF-α, at both the mRNA and protein levels. Mechanistic studies revealed that AO-I attenuated APAP-induced activation of TLR4, NF-κB and MAPKs (including JNK and p38).

Conclusion: AO-I mediates protective effects against APAP-induced hepatotoxicity via the TLR4/MAPKs/NF-κB pathways. Thus, AO-I is a candidate therapeutic compound for APAP-induced hepatotoxicity.

A ROS-Sensitive Nanozyme-Augmented Photoacoustic Nanoprobe for Early Diagnosis and Therapy of Acute Liver Failure

Early diagnosis of acute liver failure (ALF) is critical for curable treatment of patients, because most existing ALF therapies have narrow therapeutic time windows after disease onset. Reactive oxygen species (ROS), which lead to the sequential occurrences of hepatocyte necrosis and the leakage of alanine aminotransferase (ALT), represent early biomarkers of ALF. Photoacoustic imaging is emerging as a powerful tool for in vivo imaging of ROS. However, high-performance imaging probes that can boost the photoacoustic signals of the short-lived ROS of ALF are yet to be developed, and there remains a great challenge for ROS-based imaging of ALF. Herein, a ROS-sensitive nanozyme-augmented photoacoustic nanoprobe for successful in vivo imaging of ALF is presented. The deep-penetrating photoacoustic signals of the nanoprobe can be activated by the overexpressed ROS in ALF due to the synergy between nanocatalytic bubbles generation and thermoelastic expansion. Impressively, the nanozyme-augmented ROS imaging enables earlier diagnosis of ALF than the clinical ALT method, and the ROS-activated catalytic activity of nanoprobe permits timely nanocatalytic therapy of ALF.

Alcohol-induced Hsp90 acetylation is a novel driver of liver sinusoidal endothelial dysfunction and alcohol-related liver disease

BACKGROUND & AIMS

Liver sinusoidal endothelial cell (LSEC) dysfunction has been reported in alcohol-related liver disease, yet it is not known whether LSECs metabolize alcohol. Thus, we investigated this, as well as the mechanisms of alcohol-induced LSEC dysfunction and a potential therapeutic approach for alcohol-induced liver injury.

METHODS

Primary human, rat and mouse LSECs were used. Histone deacetylase 6 (HDAC6) was overexpressed specifically in liver ECs via adeno-associated virus (AAV)-mediated gene delivery to decrease heat shock protein 90 (Hsp90) acetylation in ethanol-fed mice.

RESULTS

LSECs expressed CYP2E1 and alcohol dehydrogenase 1 (ADH1) and metabolized alcohol. Ethanol induced CYP2E1 in LSECs, but not ADH1. Alcohol metabolism by CYP2E1 increased Hsp90 acetylation and decreased its interaction with endothelial nitric oxide synthase (eNOS) leading to a decrease in nitric oxide (NO) production. A non-acetylation mutant of Hsp90 increased its interaction with eNOS and NO production, whereas a hyperacetylation mutant decreased NO production. These results indicate that Hsp90 acetylation is responsible for decreases in its interaction with eNOS and eNOS-derived NO production. AAV8-driven HDAC6 overexpression specifically in liver ECs deacetylated Hsp90, restored Hsp90's interaction with eNOS and ameliorated alcohol-induced liver injury in mice.

CONCLUSION

Restoring LSEC function is important for ameliorating alcohol-induced liver injury. To this end, blocking acetylation of Hsp90 specifically in LSECs via AAV-mediated gene delivery has the potential to be a new therapeutic strategy.

LAY SUMMARY

Alcohol metabolism in liver sinusoidal endothelial cells (LSECs) and the mechanism of alcohol-induced LSEC dysfunction are largely unknown. Herein, we demonstrate that LSECs can metabolize alcohol. We also uncover a mechanism by which alcohol induces LSEC dysfunction and liver injury, and we identify a potential therapeutic strategy to prevent this.

Lactoferrin could alleviate liver injury caused by Maillard reaction products with furan ring through regulating necroptosis pathway

As classical MRPs, the toxic effects of furosine, pyralline, and 5-hydroxymethylfurfural (5-HMF) in liver tissue are evaluated and the related mechanism is investigated here, and the protective effects of lactoferrin on liver injury caused by Maillard reaction products (MRPs) with furan ring are proved in vitro and in vivo. First, we detect the concentrations of furosine, pyralline, and 5-HMF in several foods using ultrahigh-performance liquid chromatography (UHPLC). Then, the effects of the three MRPs on liver cells (HL-7702) viability, as well as liver tissue, are performed and evaluated. Furthermore, the regulations of three MRPs on necroptosis-related pathway in liver cells are investigated. Additionally, the effects of lactoferrin in alleviating liver injury, as well as regulating necroptosis pathway, were evaluated. Results elucidate that lactoferrin protects liver injury caused by MRPs with furan ring structure through activating RIPK1/RIPK3/p-MLKL necroptosis pathway and downstream inflammatory reaction.

Role of liver sinusoidal endothelial cells in liver diseases

Liver sinusoidal endothelial cells (LSECs) form the wall of the hepatic sinusoids. Unlike other capillaries, they lack an organized basement membrane and have cytoplasm that is penetrated by open fenestrae, making the hepatic microvascular endothelium discontinuous. LSECs have essential roles in the maintenance of hepatic homeostasis, including regulation of the vascular tone, inflammation and thrombosis, and they are essential for control of the hepatic immune response. On a background of acute or chronic liver injury, LSECs modify their phenotype and negatively affect neighbouring cells and liver disease pathophysiology. This Review describes the main functions and phenotypic dysregulations of LSECs in liver diseases, specifically in the context of acute injury (ischaemia-reperfusion injury, drug-induced liver injury and bacterial and viral infection), chronic liver disease (metabolism-associated liver disease, alcoholic steatohepatitis and chronic hepatotoxic injury) and hepatocellular carcinoma, and provides a comprehensive update of the role of LSECs as therapeutic targets for liver disease. Finally, we discuss the open questions in the field of LSEC pathobiology and future avenues of research.

Drug-induced-acute liver failure: A critical appraisal of the thioacetamide model for the study of hepatic encephalopathy

Hepatic encephalopathy (HE) following acute and chronic liver failure is defined as a complex of neuropsychiatric abnormalities, such as discrete personal changes, sleep disorder, forgetfulness, confusion, and decreasing the level of consciousness to coma. The use and design of suitable animal models that represent clinical features and pathological changes of HE are valuable to map the molecular mechanisms that result in HE. Among different types of animal models, thioacetamide (TAA) has been used extensively for the induction of acute liver injury and HE. This agent is not directly hepatotoxic but its metabolites induce liver injury through the induction of oxidative stress and produce systemic inflammation similar to that seen in acute HE patients. In this short review article, we shortly review the most important pathological findings in animal models of acute HE following the administration of TAA.

Hypoxia-Inducible Factor-2α Reprograms Liver Macrophages to Protect Against Acute Liver Injury Through the Production of Interleukin-6

BACKGROUND AND AIMS

Acetaminophen (APAP) overdose represents the most frequent cause of acute liver failure, resulting in death or liver transplantation in more than one third of patients in the United States. The effectiveness of the only antidote, N-acetylcysteine, declines rapidly after APAP ingestion, long before patients are admitted to the clinic with symptoms of severe liver injury. The direct hepatotoxicity of APAP triggers a cascade of innate immune responses that may exacerbate or limit the progression of tissue damage. A better understanding of this complex mechanism will help uncover targets for therapeutic interventions.

APPROACH AND RESULTS

We observed that APAP challenge caused stabilization of hypoxia-inducible factors (HIFs) in the liver and hepatic macrophages (MΦs), particularly HIF-2α. Genetic deletion of the HIF-2α gene in myeloid cells (HIF-2α^mye/- ) markedly exacerbated APAP-induced liver injury (AILI) without affecting APAP bioactivation and detoxification. In contrast, hepatic and serum levels of the hepatoprotective cytokine interleukin 6 (IL-6), its downstream signal transducer and transcription factor 3 activation in hepatocytes, as well as hepatic MΦ IL-6 expression were markedly reduced in HIF-2α^mye/- mice compared to wild-type mice post-APAP challenge. In vitro experiments revealed that hypoxia induced IL-6 production in hepatic MΦs and that such induction was abolished in HIF-2α-deleted hepatic MΦs. Restoration of IL-6 by administration of exogenous IL-6 ameliorated AILI in HIF-2α^mye/- mice. Finally, IL-6-mediated hepatoprotection against AILI was abolished in hepatocyte-specific IL-6 receptor knockout mice.

CONCLUSIONS

The data demonstrate that APAP treatment leads to HIF-2α stabilization in hepatic MΦs and that HIF-2α subsequently reprograms hepatic MΦs to produce the hepatoprotective cytokine IL-6, thereby ameliorating AILI.

Hepatoprotective Actions of Ascorbic Acid, Alpha Lipoic Acid and Silymarin or Their Combination Against Acetaminophen-Induced Hepatotoxicity in Rats

Background and objectives: Ascorbic acid, alpha lipoic acid (ALA) and silymarin are well-known antioxidants that have hepatoprotective effects. This study aims to investigate the effects of these three compounds combined with attenuating drug-induced oxidative stress and cellular damage, taking acetaminophen (APAP)-induced toxicity in rats as a model both in vivo and in vitro. Materials and Methods: Freshly cultured primary rat hepatocytes were treated with ascorbic acid, ALA, silymarin and their combination, both with and without the addition of APAP to evaluate their in vitro impact on cell proliferation and mitochondrial activity. In vivo study was performed on rats supplemented with the test compounds or their combination for one week followed by two toxic doses of APAP. Results: Selected liver function tests and oxidative stress markers including superoxide dismutase (SOD), malondialdehyde (MDA) and oxidized glutathione (GSSG) were detected. The in vivo results showed that all three pretreatment compounds and their combination prevented elevation of SOD and GSSG serum levels indicating a diminished burden of oxidative stress. Moreover, ascorbic acid, ALA and silymarin in combination reduced serum levels of liver enzymes; however, silymarin markedly maintained levels of all parameters to normal ranges. Silymarin either alone or combined with ascorbic acid and ALA protected cultured rat hepatocytes and increased cellular metabolic activity. The subjected agents were capable of significantly inhibiting the presence of oxidative stress induced by APAP toxicity and the best result for protection was seen with the use of silymarin. Conclusions: The measured liver function tests may suggest an augmented hepatoprotection of the combination preparation than when compared individually.

Acetaminophen hepatotoxicity: A mitochondrial perspective

Acetaminophen (APAP) is a highly effective analgesic, which is safe at therapeutic doses. However, an overdose can cause hepatotoxicity and even liver failure. APAP toxicity is currently the most common cause of acute liver failure in the United States. Decades of research on mechanisms of liver injury have established the role of mitochondria as central players in APAP-induced hepatocyte necrosis and this chapter examines the various facets of the organelle's involvement in the process of injury as well as in resolution of damage. The injury process is initiated by formation of a reactive metabolite, which binds to sulfhydryl groups of cellular proteins including mitochondrial proteins. This inhibits the electron transport chain and leads to formation of reactive oxygen species, which induce the activation of redox-sensitive members of the MAP kinase family ultimately causing activation of c-Jun N terminal kinase, JNK. Translocation of JNK to the mitochondria then amplifies mitochondrial dysfunction, ultimately resulting in mitochondrial permeability transition and release of mitochondrial intermembrane proteins, which trigger nuclear DNA fragmentation. Together, these events result in hepatocyte necrosis, while adaptive mechanisms such as mitophagy remove damaged mitochondria and minimize the extent of the injury. This oscillation between recovery and necrosis is predominant in cells at the edge of the necrotic area in the liver, where induction of mitochondrial biogenesis is important for liver regeneration. All these aspects of mitochondria in APAP hepatotoxicity, as well as their relevance to humans with APAP overdose and development of therapeutic approaches will be examined in detail in this chapter.

Antioxidative stress effects of vitamins C, E, and B12, and their combination can protect the liver against acetaminophen-induced hepatotoxicity in rats

BACKGROUND

Several vitamins, including C, E, and B12, have been recognized as antioxidants and have shown hepatoprotective effects against the hepatotoxicity caused by acetaminophen (APAP) overdose. The current investigation aims to study the effect of these vitamins and their combination in protecting the liver from APAP hepatotoxicity in rats.

MATERIALS AND METHODS

An in vitro model of freshly isolated rat hepatocytes was utilized for assessing hepatocyte mitochondrial activity conducted by cell proliferation assay (MTT). The isolated hepatocytes were treated with vitamin C, vitamin E, vitamin B12 and their combination, with and without further addition of toxic concentrations of APAP. In addition, an in vivo experiment was carried out on Sprague Dawley rats treated intraperitoneally for 8 days with emulsions of the vitamins or their combination prior to injecting them with APAP.

RESULTS

In vitro results showed that vitamins C and B and the combination preparation significantly increased the percentage of hepatocyte mitochondrial activity, both with and without the addition of APAP (P<0.01). The mitochondrial activity in the isolated cultured hepatocytes was further enhanced with APAP addition. In vivo, the vitamins and their combination effectively reduced APAP-induced serum liver enzymes levels, namely ALT, AST, and ALP, and also attenuated oxidative stress and lipids peroxidation confirmed by the results of glutathione, superoxide dismutase, and maloondialdehyde.

CONCLUSION

Pretreatment with vitamins C, E, B12, or their combination was found to be beneficial in preventing in vivo hepatic oxidative stress induced by APAP overdose. Vitamin C on its own showed superior protection against APAP-induced liver injury in rats compared to the other vitamins. The proliferation of APAP-intoxicated liver cells in vitro was highest when protected with the vitamins' combination.

Mechanisms of acetaminophen-induced liver injury and its implications for therapeutic interventions

Acetaminophen (APAP) overdose is the leading cause of drug-induced acute liver failure in many developed countries. Mitochondrial oxidative stress is considered to be the predominant cellular event in APAP-induced liver injury. Accordingly, N-acetyl cysteine, a known scavenger of reactive oxygen species (ROS), is recommended as an effective clinical antidote against APAP-induced acute liver injury (AILI) when it is given at an early phase; however, the narrow therapeutic window limits its use. Hence, the development of novel therapeutic approaches that can offer broadly protective effects against AILI is clearly needed. To this end, it is necessary to better understand the mechanisms of APAP hepatotoxicity. Up to now, in addition to mitochondrial oxidative stress, many other cellular processes, including phase I/phase II metabolism, endoplasmic reticulum stress, autophagy, sterile inflammation, microcirculatory dysfunction, and liver regeneration, have been identified to be involved in the pathogenesis of AILI, providing new targets for developing more effective therapeutic interventions against APAP-induced liver injury. In this review, we summarize intracellular and extracellular events involved in APAP hepatotoxicity, along with emphatic discussions on the possible therapeutic approaches targeting these different cellular events.

Structure-guided chemical modification of guide RNA enables potent non-viral in vivo genome editing

Efficient genome editing with Cas9-sgRNA in vivo has required the use of viral delivery systems, which have limitations for clinical applications. Translational efforts to develop other RNA therapeutics have shown that judicious chemical modification of RNAs can improve therapeutic efficacy by reducing susceptibility to nuclease degradation. Guided by the structure of the Cas9-sgRNA complex, we identify regions of sgRNA that can be modified while maintaining or enhancing genome-editing activity, and we develop an optimal set of chemical modifications for in vivo applications. Using lipid nanoparticle formulations of these enhanced sgRNAs (e-sgRNA) and mRNA encoding Cas9, we show that a single intravenous injection into mice induces >80% editing of Pcsk9 in the liver. Serum Pcsk9 is reduced to undetectable levels, and cholesterol levels are significantly lowered about 35% to 40% in animals. This strategy may enable non-viral, Cas9-based genome editing in the liver in clinical settings.

Macrophage-derived IL-1α promotes sterile inflammation in a mouse model of acetaminophen hepatotoxicity

The metabolic intermediate of acetaminophen (APAP) can cause severe hepatocyte necrosis, which triggers aberrant immune activation of liver non-parenchymal cells (NPC). Overzealous hepatic inflammation determines the morbidity and mortality of APAP-induced liver injury (AILI). Interleukin-1 receptor (IL-1R) signaling has been shown to play a critical role in various inflammatory conditions, but its precise role and underlying mechanism in AILI remain debatable. Herein, we show that NLRP3 inflammasome activation of IL-1β is dispensable to AILI, whereas IL-1α, the other ligand of IL-1R1, accounts for hepatic injury by a lethal dose of APAP. Furthermore, Kupffer cells function as a major source of activated IL-1α in the liver, which is activated by damaged hepatocytes through TLR4/MyD88 signaling. Finally, IL-1α is able to chemoattract and activate CD11b⁺Gr-1⁺ myeloid cells, mostly neutrophils and inflammatory monocytes, to amplify deteriorated inflammation in the lesion. Therefore, this work identifies that MyD88-dependent activation of IL-1α in Kupffer cells plays a central role in the immunopathogenesis of AILI and implicates that IL-1α is a promising therapeutic target for AILI treatment.

RNAi-nanoparticulate manipulation of gene expression as a new functional genomics tool in the liver

BACKGROUND & AIMS

The Hippo pathway controls organ size through a negative regulation of the transcription co-activator Yap1. The overexpression of hyperactive mutant Yap1 or deletion of key components in the Hippo pathway leads to increased organ size in different species. Analysis of interactions of this pathway with other cellular signals corroborating organ size control is limited in part due to the difficulties associated with development of rodent models.

METHODS

Here, we develop a new model of reversible induction of the liver size in mice using siRNA-nanoparticles targeting two kinases of the Hippo pathway, namely, mammalian Ste20 family kinases 1 and 2 (Mst1 and Mst2), and an upstream regulator, neurofibromatosis type II (Nf2).

RESULTS

The triple siRNAs nanoparticle-induced hepatomegaly in mice phenocopies one observed with Mst1(-/-)Mst2(-/-) liver-specific depletion, as shown by extensive proliferation of hepatocytes and activation of Yap1. The simultaneous co-treatment with a fourth siRNA nanoparticle against Yap1 fully blocked the liver growth. Hippo pathway-induced liver enlargement is associated with p53 activation, evidenced by its accumulation in the nuclei and upregulation of its target genes. Moreover, injections of the triple siRNAs nanoparticle in p53(LSL/LSL) mice shows that livers lacking p53 expression grow faster and exceed the size of livers in p53 wild-type animals, indicating a role of p53 in controlling Yap1-induced liver growth.

CONCLUSION

Our data show that siRNA-nanoparticulate manipulation of gene expression can provide the reversible control of organ size in adult animals, which presents a new avenue for the investigation of complex regulatory networks in liver.

Experimental models of hepatotoxicity related to acute liver failure

Acute liver failure can be the consequence of various etiologies, with most cases arising from drug-induced hepatotoxicity in Western countries. Despite advances in this field, the management of acute liver failure continues to be one of the most challenging problems in clinical medicine. The availability of adequate experimental models is of crucial importance to provide a better understanding of this condition and to allow identification of novel drug targets, testing the efficacy of new therapeutic interventions and acting as models for assessing mechanisms of toxicity. Experimental models of hepatotoxicity related to acute liver failure rely on surgical procedures, chemical exposure or viral infection. Each of these models has a number of strengths and weaknesses. This paper specifically reviews commonly used chemical in vivo and in vitro models of hepatotoxicity associated with acute liver failure.

Methods of Liver Stem Cell Therapy in Rodents as Models of Human Liver Regeneration in Hepatic Failure

Cell therapy is a promising intervention for treating liver diseases and liver failure. Different animal models of human liver cell therapy have been developed in recent years. Rats and mice are the most commonly used liver failure models. In fact, rodent models of hepatic failure have shown significant improvement in liver function after cell infusion. With the advent of stem-cell technologies, it is now possible to re-programme adult somatic cells such as skin or hair-follicle cells from individual patients to stem-like cells and differentiate them into liver cells. Such regenerative stem cells are highly promising in the personalization of cell therapy. The present review article will summarize current approaches to liver stem cell therapy with rodent models. In addition, we discuss common cell tracking techniques and how tracking data help to direct liver cell therapy research in animal models of hepatic failure.

Potential Use of Biological Proteins for Liver Failure Therapy

Biological proteins have unlimited potential for use as pharmaceutical products due to their various biological activities, which include non-toxicity, biocompatibility, and biodegradability. Recent scientific advances allow for the development of novel innovative protein-based products that draw on the quality of their innate biological activities. Some of them hold promising potential for novel therapeutic agents/devices for addressing hepatic diseases such as hepatitis, fibrosis, and hepatocarcinomas. This review attempts to provide an overview of the development of protein-based products that take advantage of their biological activity for medication, and discusses possibilities for the therapeutic potential of protein-based products produced through different approaches to specifically target the liver (or hepatic cells: hepatocytes, hepatic stellate cells, liver sinusoidal endothelial cells, and Kupffer cells) in the treatment of hepatic diseases.

Lactoferrin Enhanced Apoptosis and Protected Against Thioacetamide-Induced Liver Fibrosis in Rats

BACKGROUND:

Liver fibrosis is the common pathologic consequence of all chronic liver diseases.

AIM:

Lactoferrin (Lf) was investigated for its possible hepatoprotective effect against thioacetamide (TAA)-induced liver fibrosis rat model.

MATERIAL AND METHODS:

Rats received TAA (200 mg/kg/biweekly, ip) for four successive weeks. Lf (200 mg/kg/day, p.o.) or vehicle (VHC) was administered for one month before and another month during TAA injection. Body weight and mortality rate were assessed during the month of TAA-intoxication. Thereafter, serum and liver tissues were analyzed for liver function, oxidative, fibrotic and apoptotic markers.

RESULTS:

Lf conserved rats against TAA-induced body weight-loss and mortality. Preservation of serum albumin, alkaline phosphatase and total bilirubin levels was also observed. Lf also protected rats against TAA-induced decrease in reduced glutathione and increase in malondialdehyde liver contents. Normal liver contents of hydroxyproline, nuclear factor kappa B and alpha fetoprotein; as markers of fibrosis; were increased with TAA and conserved with Lf-TAA. Lf maintained the normal architecture of the liver and immunohistochemical findings revealed increase in apoptotic bodies compared to TAA that favored necrosis.

CONCLUSION:

In conclusion, Lf improved liver function, reduced oxidative stress and liver fibrosis, and enhanced apoptosis in rats with liver fibrosis, suggesting it to have useful therapeutic potential in patients with liver fibrosis.

Bee venom phospholipase A2 protects against acetaminophen-induced acute liver injury by modulating regulatory T cells and IL-10 in mice

The aim of this study was to investigate the protective effects of phospholipase A2 (PLA2) from bee venom against acetaminophen-induced hepatotoxicity through CD4⁺CD25⁺Foxp3⁺ T cells (Treg) in mice. Acetaminophen (APAP) is a widely used antipyretic and analgesic, but an acute or cumulative overdose of acetaminophen can cause severe hepatic failure. Tregs have been reported to possess protective effects in various liver diseases and kidney toxicity. We previously found that bee venom strongly increased the Treg population in splenocytes and subsequently suppressed immune disorders. More recently, we found that the effective component of bee venom is PLA2. Thus, we hypothesized that PLA2 could protect against liver injury induced by acetaminophen. To evaluate the hepatoprotective effects of PLA2, C57BL/6 mice or interleukin-10-deficient (IL-10^−/−) mice were injected with PLA2 once a day for five days and sacrificed 24 h (h) after acetaminophen injection. The blood sera were collected 0, 6, and 24 h after acetaminophen injection for the analysis of aspartate aminotransferase (AST) and alanine aminotransferase (ALT). PLA2-injected mice showed reduced levels of serum AST, ALT, proinflammatory cytokines, and nitric oxide (NO) compared with the PBS-injected control mice. However, IL-10 was significantly increased in the PLA2-injected mice. These hepatic protective effects were abolished in Treg-depleted mice by antibody treatment and in IL-10^−/− mice. Based on these findings, it can be concluded that the protective effects of PLA2 against acetaminophen-induced hepatotoxicity can be mediated by modulating the Treg and IL-10 production.

Acetaminophen-induced Liver Injury: from Animal Models to Humans

Drug-induced liver injury is an important clinical problem and a challenge for drug development. Whereas progress in understanding rare and unpredictable (idiosyncratic) drug hepatotoxicity is severely hampered by the lack of relevant animal models, enormous insight has been gained in the area of predictable hepatotoxins, in particular acetaminophen-induced liver injury, from a broad range of experimental models. Importantly, mechanisms of toxicity obtained with certain experimental systems, such as in vivo mouse models, primary mouse hepatocytes, and metabolically competent cell lines, are being confirmed in translational studies in patients and in primary human hepatocytes. Despite this progress, suboptimal models are still being used and experimental data can be confusing, leading to controversial conclusions. Therefore, this review attempts to discuss mechanisms of drug hepatotoxicity using the most studied drug acetaminophen as an example. We compare the various experimental models that are used to investigate mechanisms of acetaminophen hepatotoxicity, discuss controversial topics in the mechanisms, and assess how these experimental findings can be translated to the clinic. The success with acetaminophen in demonstrating the clinical relevance of experimental findings could serve as an example for the study of other drug toxicities.

MicroRNAs in Drug-induced Liver Injury

Drug-induced liver injury (DILI) is a leading cause of acute liver failure, and a major reason for the recall of marketed drugs. Detection of potential liver injury is a challenge for clinical management and preclinical drug safety studies, as well as a great obstacle to the development of new, effective and safe drugs. Currently, serum levels of alanine and aspartate aminotransferases are the gold standard for evaluating liver injury. However, these levels are assessed by nonspecific, insensitive, and non-predictive tests, and often result in false-positive results. Therefore, there is an urgent need for better DILI biomarkers to guide risk assessment and patient management. The discovery of microRNAs (miRNAs) as a new class of gene expression regulators has triggered an explosion of research, particularly on the measurement of miRNAs in various body fluids as biomarkers for many human diseases. The properties of miRNA-based biomarkers, such as tissue specificity and high stability and sensitivity, suggest they could be used as novel, minimally invasive and stable DILI biomarkers. In the current review, we summarize recent progress concerning the role of miRNAs in diagnosing and monitoring both clinical and preclinical DILI, and discuss the main advantages and challenges of miRNAs as novel DILI biomarkers.

Pharmacologic cholinesterase inhibition improves survival in acetaminophen-induced acute liver failure in the mouse

Background

Acetaminophen (APAP) is one of the most widely used analgesic and antipyretic pharmaceutical substances in the world and accounts for most cases of drug induced liver injury resulting in acute liver failure. Acute liver failure initiates a sterile inflammatory response with release of cytokines and innate immune cell infiltration in the liver. This study investigates, whether pharmacologic acetylcholinesterase inhibition with neostigmine diminishes liver damage in acute liver failure via the cholinergic anti-inflammatory pathway.

Methods

Acute liver failure was induced in BALB/c mice by a toxic dose of acetaminophen (APAP). Neostigmine and/or N-acetyl-cysteine (NAC) were applied therapeutically at set time points and the survival was investigated. Liver damage was assessed by serum parameters, histopathology and serum cytokine assays 12 h after initiation of acute liver failure.

Results

Serum parameters, histopathology and serum cytokine assays showed pronounced features of acute liver failure 12 h after application of acetaminophen (APAP). Neostigmine treatment led to significant reduction of serum liver enzymes (LDH (47,147 ± 12,726 IU/l vs. 15,822 ± 10,629 IU/l, p = 0.0014) and ALT (18,048 ± 4,287 IU/l vs. 7,585 ± 5,336 IU/l, p = 0.0013), APAP-alone-treated mice vs. APAP + neostigmine-treated mice), inflammatory cytokine levels (IL-1β (147 ± 19 vs. 110 ± 25, p = 0.0138) and TNF-α (184 ± 23 vs. 130 ± 33, p = 0.0086), APAP-alone-treated mice vs. APAP + neostigmine-treated mice) and histopathological signs of damage.

Animals treated with NAC in combination with the peripheral cholinesterase inhibitor neostigmine showed prolonged survival and improved outcome.

Conclusions

Neostigmine is an acetylcholinesterase inhibitor that ameliorates the effects of APAP-induced acute liver failure in the mouse and therefore may provide new treatment options for affected patients.

19-substituted benzoquinone ansamycin heat shock protein-90 inhibitors: biological activity and decreased off-target toxicity

The benzoquinone ansamycins (BQAs) are a valuable class of antitumor agents that serve as inhibitors of heat shock protein (Hsp)-90. However, clinical use of BQAs has resulted in off-target toxicities, including concerns of hepatotoxicity. Mechanisms underlying the toxicity of quinones include their ability to redox cycle and/or arylate cellular nucleophiles. We have therefore designed 19-substituted BQAs to prevent glutathione conjugation and nonspecific interactions with protein thiols to minimize off-target effects and reduce hepatotoxicity. 19-Phenyl- and 19-methyl-substituted versions of geldanamycin and its derivatives, 17-allylamino-17-demethoxygeldanamycin and 17-(dimethylaminoethylamino)-17-demethoxygeldanamycin (17-DMAG), did not react with glutathione, whereas marked reactivity was observed using parent BQAs. Importantly, although 17-DMAG induced cell death in primary and cultured mouse hepatocytes, 19-phenyl and 19-methyl DMAG showed reduced toxicity, validating the overall approach. Furthermore, our data suggest that arylation reactions, rather than redox cycling, are a major mechanism contributing to BQA hepatotoxicity. 19-Phenyl BQAs inhibited purified Hsp90 in a

NAD(P)H

quinone oxidoreductase 1 (NQO1)-dependent manner, demonstrating increased efficacy of the hydroquinone ansamycin relative to its parent quinone. Molecular modeling supported increased stability of the hydroquinone form of 19-phenyl-DMAG in the active site of human Hsp90. In human breast cancer cells, 19-phenyl BQAs induced growth inhibition also dependent upon metabolism via NQO1 with decreased expression of client proteins and compensatory induction of Hsp70. These data demonstrate that 19-substituted BQAs are unreactive with thiols, display reduced hepatotoxicity, and retain Hsp90 and growth-inhibitory activity in human breast cancer cells, although with diminished potency relative to parent BQAs.

Role of hepatic resident and infiltrating macrophages in liver repair after acute injury

Treatment of liver disease, caused by hepatotoxins, viral infections, alcohol ingestion, or autoimmune conditions, remains challenging and costly. The liver has a powerful capacity to repair and regenerate, thus a thorough understanding of this tightly orchestrated process will undoubtedly improve clinical means of restoring liver function after injury. Using a murine model of acute liver injury caused by overdose of acetaminophen (APAP), our studies demonstrated that the combined absence of liver resident macrophages (Kupffer cells, KCs), and infiltrating macrophages (IMs) resulted in a marked delay in liver repair, even though the initiation and extent of peak liver injury was not impacted. This delay was not due to impaired hepatocyte proliferation but rather prolonged vascular leakage, which is caused by APAP-induced liver sinusoidal endothelial cell (LSEC) injury. We also found that KCs and IMs express an array of angiogenic factors and induce LSEC proliferation and migration. Our mechanistic studies suggest that hypoxia-inducible factor (HIF) may be involved in regulating the angiogenic effect of hepatic macrophages (Macs), as we found that APAP challenge resulted in hypoxia and stabilization of HIF in the liver and hepatic Macs. Together, these data indicate an important role for hepatic Macs in liver blood vessel repair, thereby contributing to tissue recovery from acute injury.

Acetaminophen hepatotoxicity and repair: the role of sterile inflammation and innate immunity

Acetaminophen (APAP) hepatotoxicity because of overdose is the most frequent cause of acute liver failure in the western world. Metabolic activation of APAP and protein adduct formation, mitochondrial dysfunction, oxidant stress, peroxynitrite formation and nuclear DNA fragmentation are critical intracellular events in hepatocytes. However, the early cell necrosis causes the release of a number of mediators such as high-mobility group box 1 protein, DNA fragments, heat shock proteins (HSPs) and others (collectively named damage-associated molecular patterns), which can be recognized by toll-like receptors on macrophages, and leads to their activation with cytokine and chemokine formation. Although pro-inflammatory mediators recruit inflammatory cells (neutrophils, monocytes) into the liver, neither the infiltrating cells nor the activated resident macrophages cause any direct cytotoxicity. In contrast, pro- and anti-inflammatory cytokines and chemokines can directly promote intracellular injury mechanisms by inducing nitric oxide synthase or inhibit cell death mechanisms by the expression of acute-phase proteins (HSPs, heme oxygenase-1) and promote hepatocyte proliferation. In addition, the newly recruited macrophages (M2) and potentially neutrophils are involved in the removal of necrotic cell debris in preparation for tissue repair and resolution of the inflammatory response. Thus, as discussed in detail in this review, the preponderance of experimental evidence suggests that the extensive sterile inflammatory response during APAP hepatotoxicity is predominantly beneficial by limiting the formation and the impact of pro-inflammatory mediators and by promoting tissue repair.

Acetaminophen hepatotoxicity and HIF-1α induction in acetaminophen toxicity in mice occurs without hypoxia

HIF-1α is a nuclear factor important in the transcription of genes controlling angiogenesis including vascular endothelial growth factor (VEGF). Both hypoxia and oxidative stress are known mechanisms for the induction of HIF-1α. Oxidative stress and mitochondrial permeability transition (MPT) are mechanistically important in acetaminophen (APAP) toxicity in the mouse. MPT may occur as a result of oxidative stress and leads to a large increase in oxidative stress. We previously reported the induction of HIF-1α in mice with APAP toxicity and have shown that VEGF is important in hepatocyte regeneration following APAP toxicity. The following study was performed to examine the relative contribution of hypoxia versus oxidative stress to the induction of HIF-1α in APAP toxicity in the mouse. Time course studies using the hypoxia marker pimonidazole showed no staining for pimonidazole at 1 or 2h in B6C3F1 mice treated with APAP. Staining for pimonidazole was present in the midzonal to periportal regions at 4, 8, 24 and 48h and no staining was observed in centrilobular hepatocytes, the sites of the toxicity. Subsequent studies with the MPT inhibitor cyclosporine A showed that cyclosporine A (CYC; 10mg/kg) reduced HIF-1α induction in APAP treated mice at 1 and 4h and did not inhibit the metabolism of APAP (depletion of hepatic non-protein sulfhydryls and hepatic protein adduct levels). The data suggest that HIF-1α induction in the early stages of APAP toxicity is secondary to oxidative stress via a mechanism involving MPT. In addition, APAP toxicity is not mediated by a hypoxia mechanism.