Perspectives on Scaffold Designs with Roles in Liver Cell Asymmetry and Medical and Industrial Applications by Using a New Type of Specialized 3D Bioprinter

Cellular asymmetry is an important element of efficiency in the compartmentalization of intracellular chemical reactions that ensure efficient tissue function. Improving the current 3D printing methods by using cellular asymmetry is essential in producing complex tissues and organs such as the liver. The use of cell spots containing at least two cells and basement membrane-like bio support materials allows cells to be tethered at two points on the basement membrane and with another cell in order to maintain cell asymmetry. Our model is a new type of 3D bioprinter that uses oriented multicellular complexes with cellular asymmetry. This novel approach is necessary to replace the sequential and slow processes of organogenesis with rapid methods of growth and 3D organ printing. The use of the extracellular matrix in the process of bioprinting with cells allows one to preserve the cellular asymmetry in the 3D printing process and thus preserve the compartmentalization of biological processes and metabolic efficiency.

VEGF signaling governs the initiation of biliary-mediated liver regeneration through the PI3K-mTORC1 axis

Biliary epithelial cells (BECs) are a potential source to repair the damaged liver when hepatocyte proliferation is compromised. Promotion of BEC-to-hepatocyte transdifferentiation could be beneficial to the clinical therapeutics of patients with end-stage liver diseases. However, mechanisms underlying the initiation of BEC transdifferentiation remain largely unknown. Here, we show that upon extreme hepatocyte injury, vegfaa and vegfr2/kdrl are notably induced in hepatic stellate cells and BECs, respectively. Pharmacological and genetic inactivation of vascular endothelial growth factor (VEGF) signaling would disrupt BEC dedifferentiation and proliferation, thus restraining hepatocyte regeneration. Mechanically, VEGF signaling regulates the activation of the PI3K-mammalian target of rapamycin complex 1 (mTORC1) axis, which is essential for BEC-to-hepatocyte transdifferentiation. In mice, VEGF signaling exerts conserved roles in oval cell activation and BEC-to-hepatocyte differentiation. Taken together, this study shows VEGF signaling as an initiator of biliary-mediated liver regeneration through activating the PI3K-mTORC1 axis. Modulation of VEGF signaling in BECs could be a therapeutic approach for patients with end-stage liver diseases.

Hepatocyte-specific HDAC3 ablation promotes hepatocellular carcinoma in females by suppressing Foxa1/2

BACKGROUND

Hepatocellular carcinoma (HCC), the most common primary liver cancer, prevails mainly in males and has long been attributed to androgens and higher circumstantial levels of interleukin-6 (IL-6) produced by resident hepatic macrophages.

METHODS

Constitutively hepatocyte-specific histone deacetylase 3 (HDAC3)-deficient (HDAC3LCKO) mice and constitutively hepatocyte-specific HDAC3 knockout and systemic IL-6 simultaneously ablated (HDAC3LCKO& IL-6-/-) mice were used in our study to explore the causes of sex differences in HCC. Additionally, we performed human HCC tissues with an IHC score. Correlation analysis and linear regression plots were constructed to reveal the association between HDAC3 and its candidate genes. To further elucidate that HDAC3 controls the expression of Foxa1/2, we knocked down HDAC3 in HUH7 liver cancer cells.

RESULTS

We observed a contrary sex disparity, with an earlier onset and higher incidence of HCC in female mice when HDAC3 was selectively ablated in the liver. Loss of HDAC3 led to constant liver injury and the spontaneous development of HCC. Unlike the significant elevation of IL-6 in male mice at a very early age, female mice exhibit stable IL-6 levels, and IL-6 ablation did not eliminate the sex disparity in hepatocarcinogenesis in HDAC3-deficient mice. Oestrogen often protects the liver when combined with oestrogen receptor alpha (ERα); however, ovariectomy in HDAC3-ablated female mice significantly delayed tumourigenesis. The oestrogen-ERα axis can also play a role in tumour promotion in the absence of Foxa1 and Foxa2 in the receptor complex. Loss of HDAC3 profoundly reduced the expression of both Foxa1 and Foxa2 and impaired the binding between Foxa1/2 and ERα. Furthermore, a more frequent HDAC3 decrease accompanied by the simultaneous Foxa1/2 decline was found in female HCC compared to that in male HCC.

CONCLUSION

In summary, we reported that loss of HDAC3 reduces Foxa1/2 and thus promotes HCC development in females in an oestrogen-dependent manner.

Induced Pluripotent Stem Cells (Ipscs) Based Liver Organoid: the Benefits and Challenges

The liver is the main metabolic organ and functions to regulate many physiological functions in the human body. Approximately 70% of liver mass consists of hepatic cells (hepatocytes), which execute the liver's metabolic processes. When liver damage progresses to a chronic condition, such as end-stage liver disease (ESLD) or cirrhosis of the liver, the patient's only option for therapy is organ transplantation if the supply of available transplanted organs is insufficient to meet the patient's needs. The fundamental objective of the search for alternatives to organ transplantation has been to make liver tissue replacement more accessible and to produce hepatic and bioartificial liver tissue. Multiple hepatic cell lineages can be formed from human-induced pluripotent stem cells (hiPSCs) from embryoid bodies to become mature hepatocytes. hiPSCs also show a promising source for manufacturing human liver spheroids and are made to produce three-dimensional hepatobiliary organoids, and in some ways, it also briefly highlights important features of early hepatogenesis. Unquestionably, the art of cell culture has evolved to include the use of organoid technology as a resource for learning human biology in the context of health and illness. Organoids are essentially miniature organs that can grow in a three-dimensional matrix to resemble genuine organs in terms of both structure and function. This review summarized alternative protocols to differentiate hepatocytes from iPSC and to produce liver organoids based on iPSC in various ways. The growth of human iPSCs into liver organoids has been accomplished using several procedures.

Protective effect of solanesol in glucose-induced hepatocyte injury: Mechanistic insights on oxidative stress and mitochondrial preservation

Solanesol is a tetra sesquiterpene enol with various biological activities. Modern medical studies have confirmed that solanesol has the function of lipid antioxidation and scavenges free radicals. This study aimed to investigate the protective effect of solanesol against oxidative damage induced by high glucose on human normal hepatocytes (L-02 cells) and its possible mechanism. The results showed that solanesol could effectively improve the decrease of cell viability induced by high glucose, decrease the contents of alanine aminotransferase (ALT), aspartate aminotransferase (AST), and lactate dehydrogenase (LDH) in the extracellular medium, increased the enzyme activities of glutathione peroxidase (GSH-Px), superoxide dismutase (SOD), catalase (CAT), balanced the level of reactive oxygen species (ROS) in cells, inhibited lipid peroxidation of all kinds of biological membranes, and restored mitochondrial membrane potential (MMP). In addition, Solanesol also inhibited the expression of Keap1, promoted the nuclear translocation of Nrf2 by hydrogen bonding with Nrf2, and activated the expression of downstream antioxidant factors NQO1 and HO-1. Altogether, these findings suggest that solanesol may be a potential protectant against diabetic liver injury.

Berberine protects hepatocyte from hypoxia/reoxygenation-induced injury through inhibiting circDNTTIP2

Background

During hepatic ischemia-reperfusion injury, the excessive release of inflammatory cytokines can activate the intracellular signal transduction cascade to induce hepatocyte injury. Apoptosis is an important way of cell death after I/R injury. Berberine, a common quaternary ammonium alkaloid, has anti-inflammatory, anti-oxidative stress, and anti-apoptotic effects. An increasing number of studies have revealed the importance of non-coding RNAs, including microRNA, long non-coding RNAs and circular RNAs (circRNAs), as regulators of the effects of berberine.

Purpose

In this study, we investigated the mechanism of berberine against liver ischemia-reperfusion injury in vitro.

Study Design and Methods

In this study, hypoxia-reoxygenation (H/R)-treated L02 cells were pretreated with berberine to study the role and mechanism of berberine in resisting hepatic ischemia-reperfusion injury.

Results

The results show that berberine pre-treatment increased the cell viability of H/R-challenged cells, reduced H/R-induced apoptosis and ROS production, reversed H/R-increased on IL-6, IL-1β, TNF-α, and H/R-decreased IL-10 expression. Mechanically, berberine protect hepatocyte from H/R injury, at least partially, through circDNTTIP2. In addition, circDNTTIP2 can bind to the TATA box of caspase3 promoter, thereby promoting caspase 3-related cell apoptosis and the release of inflammatory cytokines.

Conclusion

This study found that berberine has a protective effect on H/R-induced hepatocyte damage by inhibiting a novel circRNA, circDNTTIP2. This study provides potential treatment strategies and treatment targets for liver ischemia-reperfusion injury.

The Combined Effect of Copper Nanoparticles and Microplastics on Transcripts Involved in Oxidative Stress Pathway in Rainbow Trout (Oncorhynchus Mykiss) Hepatocytes

Copper nanoparticles (CuNPs) and microplastics (MPs) are two emerging contaminants of freshwater systems. Despite their co-occurrence in many water bodies, the combined effects of CuNPs and MPs on aquatic organisms are not well-investigated. In this study, primary cultures of rainbow trout hepatocytes were exposed to dissolved Cu, CuNPs, MPs, or a combination of MPs and CuNPs for 48 h, and the transcript abundances of oxidative stress-related genes were investigated. Exposure to CuNPs or dissolved Cu resulted in a significant increase in the transcript abundances of two antioxidant enzymes, catalase (CAT) and superoxide dismutase (SOD). Exposure to CuNPs also led to an upregulation in the expression of Na+/K+ ATPase alpha 1 subunit (ATP1A1). Microplastics alone or in combination with CuNPs did not have a significant effect on abundances of the target gene transcripts. Overall, our findings suggested acute exposure to CuNPs or dissolved ions may induce oxidative stress in hepatocytes, and the Cu-induced effect on target gene transcripts was not associated with MPs.

Mitochondrial IRG1 traps MCL-1 to induce hepatocyte apoptosis and promote carcinogenesis

Hepatocarcinogenesis is initiated by repeated hepatocyte death and liver damage, and the underlying mechanisms mediating cell death and the subsequent carcinogenesis remain to be fully investigated. Immunoresponsive gene 1 (IRG1) and its enzymatic metabolite itaconate are known to suppress inflammation in myeloid cells, and its expression in liver parenchymal hepatocytes is currently determined. However, the potential roles of IRG1 in hepatocarcinogenesis are still unknown. Here, using the diethylnitrosamine (DEN)-induced hepatocarcinogenesis mouse model, we found that IRG1 expression in hepatocytes was markedly induced upon DEN administration. The DEN-induced IRG1 was then determined to promote the intrinsic mitochondrial apoptosis of hepatocytes and liver damage, thus enhancing the subsequent hepatocarcinogenesis. Mechanistically, the mitochondrial IRG1 could associate and trap anti-apoptotic MCL-1 to inhibit the interaction between MCL-1 and pro-apoptotic Bim, thus promoting Bim activation and downstream Bax mitochondrial translocation, and then releasing cytochrome c and initiating apoptosis. Thus, the inducible mitochondrial IRG1 promotes hepatocyte apoptosis and the following hepatocarcinogenesis, which provides mechanistic insight and a potential target for preventing liver injury and HCC.

Micropatterned primary hepatocyte co-culture (HEPATOPAC) for fatty liver disease modeling and drug screening

Non-alcoholic fatty liver disease (NAFLD) is a highly prevalent, progressive disorder and growing public health concern. To address this issue considerable research has been undertaken in pursuit of new NAFLD therapeutics. Development of effective, high-throughput in vitro models is an important aspect of drug discovery. Here, a micropatterned hepatocyte co-culture (MPCC) was used to model liver steatosis. The MPCC model (HEPATOPACTM) is comprised of hepatocytes and 3T3-J2 mouse stromal cells plated onto a patterned standard 96-well or 24-well plate, allowing the cultures to be handled and imaged in a standardized multi-well format. These studies employed high content imaging (HCI) analysis to assess lipid content in cultures. HCI analysis of lipid accumulation allows large numbers of samples to be imaged and analyzed in a relatively short period of time compared to manual acquisition and analysis methods. Treatment of MPCC with free fatty acids (FFA), high glucose and fructose (HGF), or a combination of both induces hepatic steatosis. MPCC treatment with ACC1/ACC2 inhibitors, as either a preventative or reversal agent, showed efficacy against FFA induced hepatic steatosis. Drug induced steatosis was also evaluated. Treatment with valproic acid showed steatosis induction in a lean background, which was significantly potentiated in a fatty liver background. Additionally, these media treatments changed expression of fatty liver related genes. Treatment of MPCC with FFA, HGF, or a combination reversibly altered expression of genes involved in fatty acid metabolism, insulin signaling, and lipid transport. Together, these data demonstrate that MPCC is an easy to use, long-term functional in vitro model of NAFLD having utility for compound screening, drug toxicity evaluation, and assessment of gene regulation.

The Origin and Fate of Liver Myofibroblasts

Liver fibrosis of different etiologies is a serious health problem worldwide. There is no effective therapy available for liver fibrosis except the removal of the underlying cause of injury or liver transplantation. Development of liver fibrosis is caused by fibrogenic myofibroblasts that are not present in the normal liver, but rather activate from liver resident mesenchymal cells in response to chronic toxic or cholestatic injury. Many studies indicate that liver fibrosis is reversible when the causative agent is removed. Regression of liver fibrosis is associated with the disappearance of activated myofibroblasts and resorption of the fibrous scar. In this review, we discuss the results of genetic tracing and cell fate mapping of hepatic stellate cells and portal fibroblasts, their specific characteristics, and potential phenotypes. We summarize research progress in the understanding of the molecular mechanisms underlying the development and reversibility of liver fibrosis, including activation, apoptosis, and inactivation of myofibroblasts.

An unexpected role of neutrophils in clearing apoptotic hepatocytes in vivo

Billions of apoptotic cells are removed daily in a human adult by professional phagocytes (e.g. macrophages) and neighboring nonprofessional phagocytes (e.g. stromal cells). Despite being a type of professional phagocyte, neutrophils are thought to be excluded from apoptotic sites to avoid tissue inflammation. Here, we report a fundamental and unexpected role of neutrophils as the predominant phagocyte responsible for the clearance of apoptotic hepatic cells in the steady state. In contrast to the engulfment of dead cells by macrophages, neutrophils burrowed directly into apoptotic hepatocytes, a process we term perforocytosis, and ingested the effete cells from the inside. The depletion of neutrophils caused defective removal of apoptotic bodies, induced tissue injury in the mouse liver, and led to the generation of autoantibodies. Human autoimmune liver disease showed similar defects in the neutrophil-mediated clearance of apoptotic hepatic cells. Hence, neutrophils possess a specialized immunologically silent mechanism for the clearance of apoptotic hepatocytes through perforocytosis, and defects in this key housekeeping function of neutrophils contribute to the genesis of autoimmune liver disease.

The Different Mechanisms of Lipid Accumulation in Hepatocytes Induced by Oleic Acid/Palmitic Acid and High-Fat Diet

Non-alcoholic fatty liver disease (NAFLD) is the primary chronic liver disease worldwide, mainly manifested by hepatic steatosis. Hepatic lipids may be derived from dietary intake, plasma free fatty acid (FFA) uptake, or hepatic de novo lipogenesis (DNL). Currently, cellular and animal models of hepatocellular steatosis are widely used to study the pathogenesis of NAFLD and to investigate therapeutic agents. However, whether there are differences between the in vivo and in vitro models of the mechanisms that cause lipid accumulation has not been reported. We used OA/PA-induced NCTC 1469 cells and high-fat-diet-fed C57BL/6J mice to simulate a hepatocyte steatosis model of NAFLD and to detect indicators related to FFA uptake and DNL. In addition, when serological indicators were analysed in the mouse model, it was found that serum FASN levels decreased. The results revealed that, in the cellular model, indicators related to DNL were decreased, FASN enzyme activity was unchanged, and indicators related to FFA uptake were increased, including the high expression of CD36; while, in the animal model, indicators related to both FFA uptake and de novo synthesis were increased, including the high expression of CD36 and the increased protein levels of FASN with enhanced enzyme activity. In addition, after an analysis of the serological indicators in the mouse model, it was found that the serum levels of FASN were reduced. In conclusion, the OA/PA-induced cellular model can be used to study the mechanism of FFA uptake, whereas the high-fat-diet-induced mouse model can be used to study the mechanism of FFA uptake and DNL. Combined treatment with CD36 and FASN may be more effective against NAFLD. FASN in the serum can be used as one of the indicators for the clinical diagnosis of NAFLD.

The extracellular matrix in hepatocellular carcinoma: Mechanisms and therapeutic vulnerability

The tumor microenvironment (TME) is influenced by a "disorganized" extracellular matrix (ECM) that sensitizes cancer cells toward mechanical stress, signaling, and structural alterations. In hepatocellular carcinoma (HCC), lack of knowledge about key ECM proteins driving the TME refractory to targeted therapies poses a barrier to the identification of new therapeutic targets. Herein, we discuss the contributions of various ECM components that impact hepatocytes and their surrounding support network during tumorigenesis. In addition, the underpinnings by which ECM proteins transduce mechanical signals to the liver TME are detailed. Finally, in view of the bidirectional feedback between the ECM, transformed hepatocytes, and immune cells, we highlight the potential role of the ECM disorganization process in shaping responses to immune checkpoint inhibitors and targeted therapies. Our comprehensive characterization of these ECM components may provide a roadmap for innovative therapeutic approaches to restrain HCC.

Isolation of primary human liver cells from normal and nonalcoholic steatohepatitis livers

Here, we present a protocol for isolating human hepatocytes and neural progenitor cells from normal and nonalcoholic steatohepatitis livers. We describe steps for perfusion for scaled-up liver cell isolation and optimization of chemical digestion to achieve maximal yield and cell viability. We then detail a liver cell cryopreservation and potential applications, such as the use of human liver cells as a tool to link experimental and translational research.

Therapeutic blockade of ER stress and inflammation prevents NASH and progression to HCC

The incidence of hepatocellular carcinoma (HCC) is rapidly rising largely because of increased obesity leading to nonalcoholic steatohepatitis (NASH), a known HCC risk factor. There are no approved treatments to treat NASH. Here, we first used single-nucleus RNA sequencing to characterize a mouse model that mimics human NASH-driven HCC, the MUP-uPA mouse fed a high-fat diet. Activation of endoplasmic reticulum (ER) stress and inflammation was observed in a subset of hepatocytes that was enriched in mice that progress to HCC. We next treated MUP-uPA mice with the ER stress inhibitor BGP-15 and soluble gp130Fc, a drug that blocks inflammation by preventing interleukin-6 trans-signaling. Both drugs have progressed to phase 2/3 human clinical trials for other indications. We show that this combined therapy reversed NASH and reduced NASH-driven HCC. Our data suggest that these drugs could provide a potential therapy for NASH progression to HCC.

Protocol for enrichment, purification, and cytocentrifugation of mouse liver endothelial cells

Liver endothelial cells (LECs) are critical in maintaining liver homeostasis. To understand the mechanistic processes occurring in these cells, high-quality isolation protocols must be in place. Here, we present a protocol for LEC enrichment, subsequent LEC purification using fluorescence-assisted cell sorting, and cytocentrifugation of sorted LECs for imaging. We describe steps for isolation of LEC-enriched population from mouse livers, immunolabeling and sorting, and cytospin and immunostaining. We then mention procedures for downstream analysis. For complete details on the use and execution of this protocol, please refer to Drzewiecki et al. (2021).1.

Fatty acid challenge shifts cellular energy metabolism in a substrate-specific manner in primary bovine neonatal hepatocytes

Adipose tissue mobilization increases circulating fatty acid (FA) concentrations, leads to increased hepatic FA uptake, and influences hepatic metabolism. Our objective was to trace carbon flux through metabolic pathways in primary bovine neonatal hepatocytes challenged with FA, and to examine the effect of FA challenge on oxidative stress. Primary bovine neonatal hepatocytes were isolated from 4 Holstein bull calves and maintained for 24 h before treatment with either 0 or 1 mM FA cocktail. After 21 h, either [1-14C]C16:0 or [2-14C]sodium pyruvate was added to measure complete and incomplete oxidation and cellular glycogen. Cellular and media triglyceride (TG), and glucose and ß-hydroxybutyrate (BHB) export were quantified, as well as reactive oxygen species and cellular glutathione (GSH/GSSH). Fatty acid treatment increased cellular, but not media TG, and although complete oxidation of [1-14C]C16:0 was not affected by FA, BHB export was increased. Reactive oxygen species were increased with FA treatment and GSSH was marginally increased such that the ratio of GSH:GSSG was marginally decreased. Glucose export increased, and cellular glycogen marginally increased with FA treatment while [2-14C]sodium pyruvate oxidation was decreased. These data suggest that FA treatment shifts cellular energy metabolism in a substrate-specific manner, spares pyruvate carbon from oxidation, and stimulates glucose synthesis.

Oit3, a promising hallmark gene for targeting liver sinusoidal endothelial cells

Liver sinusoidal endothelial cells (LSECs) play a pivotal role in maintaining liver homeostasis and influencing the pathological processes of various liver diseases. However, neither LSEC-specific hallmark genes nor a LSEC promoter-driven Cre mouse line has been introduced before, which largely restricts the study of liver diseases with vascular disorders. To explore LSEC-specific hallmark genes, we compared the top 50 marker genes between liver endothelial cells (ECs) and liver capillary ECs and identified 18 overlapping genes. After excluding globally expressed genes and those with low expression percentages, we narrowed our focus to two final candidates: Oit3 and Dnase1l3. Through single-cell RNA sequencing (scRNA-seq) and analysis of the NCBI database, we confirmed the extrahepatic expression of Dnase1l3. The paired-cell sequencing data further demonstrated that Oit3 was predominantly expressed in the midlobular liver ECs. Subsequently, we constructed inducible Oit3-CreERT2 transgenic mice, which were further crossed with ROSA26-tdTomato mice. Microscopy validated that the established Oit3-CreERT2-tdTomato mice exhibited significant fluorescence in the liver rather than in other organs. The staining analysis confirmed the colocalization of tdTomato and EC markers. Ex-vivo experiments further confirmed that isolated tdTomato+ cells exhibited well-differentiated fenestrae and highly expressed EC markers, confirming their identity as LSECs. Overall, Oit3 is a promising hallmark gene for tracing LSECs. The establishment of Oit3-CreERT2-tdTomato mice provides a valuable model for studying the complexities of LSECs in liver diseases.

Association between IL-10 gene polymorphisms (- 1082 A/G, -819 T/C, -592 A/C) and hepatocellular carcinoma: a meta-analysis and trial sequential analysis

BACKGROUND

The carcinogenesis of hepatocellular carcinoma is complicated, and genetic factor may have the role in the malignant transformation of liver cells. IL-10 gene polymorphisms have been investigated for their potential roles in hepatocellular carcinoma This study aimed to investigate the relationship between polymorphisms of IL-10 (-1082 A/G, -819 T/C, -592 A/C), and hepatocellular carcinoma by performing a meta-analysis with eligible individual studies.

METHODS

This study followed the PRISMA 2020 Checklist. Relevant studies were searched in health-related databases. The Newcastle-Ottawa Scale criteria were used to evaluate the studies quality. Pooled odds ratio (OR) and its 95% confidence interval (CI) were used to determine the strength of association between each polymorphism and hepatocellular carcinoma using five genetic models. Stratification was done by ethnic groups. Trial sequential analysis (TSA) was performed to determine the required information size.

RESULTS

Fifteen case-control studies (n = 8182) were identified. Overall, the heterozygous model showed a marginal significant association only between IL-10 (-1082 A/G) and hepatocellular carcinoma risk (OR: 0.82, 95% CI: 0.67-1.00, 9 studies). On stratification, IL-10 (-1082 A/G) was significantly associated with hepatocellular carcinoma risk in the non-Asian population under dominant (OR: 0.62, 95% CI: 0.45-0.86, 4 studies), heterozygous (OR: 0.60, 95% CI: 0.43-0.85) and allelic models (OR: 0.79, 95% CI: 0.64-0.99). IL-10 (-819 T/C) was significantly associated with hepatocellular carcinoma risk only among non-Asians under the dominant (OR: 1.47, 95% CI: 1.02-2.13, 8 studies), recessive (OR: 1.99, 95% CI: 1.03-3.86, and homozygous models (OR: 2.18, 95% CI: 1.13-4.23). For IL-10 (-592 A/C) with 11 studies, there was no significant association with hepatocellular carcinoma in all five genetic models (P values > 0.5). TSA plots indicated that the information size for firm evidence of effect was sufficient only for the analysis of IL-10 (-592 A/C), but not for the - 1082 A/G or -819 T/C.

CONCLUSIONS

Findings suggest that IL-10 (-1082 A/G and - 819 T/C) polymorphisms are associated with hepatocellular carcinoma in ethnic-specific manner. However, this evidence is not conclusive because the sample size was insufficient. IL-10 (-592 A/C) polymorphism was not associated with hepatocellular carcinoma albeit with sufficient information size. Future well-designed large case-control studies on IL-10 (-1082 A/G and - 819 T/C) with different ethnicities are recommended.

Discovering the Protective Effects of Quercetin on Aflatoxin B1-Induced Toxicity in Bovine Foetal Hepatocyte-Derived Cells (BFH12)

Aflatoxin B1 (AFB1) induces lipid peroxidation and mortality in bovine foetal hepatocyte-derived cells (BFH12), with underlying transcriptional perturbations associated mainly with cancer, cellular damage, inflammation, bioactivation, and detoxification pathways. In this cell line, curcumin and resveratrol have proven to be effective in mitigating AFB1-induced toxicity. In this paper, we preliminarily assessed the potential anti-AFB1 activity of a natural polyphenol, quercetin (QUE), in BFH12 cells. To this end, we primarily measured QUE cytotoxicity using a WST-1 reagent. Then, we pre-treated the cells with QUE and exposed them to AFB1. The protective role of QUE was evaluated by measuring cytotoxicity, transcriptional changes (RNA-sequencing), lipid peroxidation (malondialdehyde production), and targeted post-transcriptional modifications (NQO1 and CYP3A enzymatic activity). The results demonstrated that QUE, like curcumin and resveratrol, reduced AFB1-induced cytotoxicity and lipid peroxidation and caused larger transcriptional variations than AFB1 alone. Most of the differentially expressed genes were involved in lipid homeostasis, inflammatory and immune processes, and carcinogenesis. As for enzymatic activities, QUE significantly reverted CYP3A variations induced by AFB1, but not those of NQO1. This study provides new knowledge about key molecular mechanisms involved in QUE-mediated protection against AFB1 toxicity and encourages in vivo studies to assess QUE's bioavailability and beneficial effects on aflatoxicosis.

The multifaceted role of macrophages during acute liver injury

The liver is situated at the interface of the gut and circulation where it acts as a filter for blood-borne and gut-derived microbes and biological molecules, promoting tolerance of non-invasive antigens while driving immune responses against pathogenic ones. Liver resident immune cells such as Kupffer cells (KCs), a subset of macrophages, maintain homeostasis under physiological conditions. However, upon liver injury, these cells and others recruited from circulation participate in the response to injury and the repair of tissue damage. Such response is thus spatially and temporally regulated and implicates interconnected cells of immune and non-immune nature. This review will describe the hepatic immune environment during acute liver injury and the subsequent wound healing process. In its early stages, the wound healing immune response involves a necroinflammatory process characterized by partial depletion of resident KCs and lymphocytes and a significant infiltration of myeloid cells including monocyte-derived macrophages (MoMFs) complemented by a wave of pro-inflammatory mediators. The subsequent repair stage includes restoring KCs, initiating angiogenesis, renewing extracellular matrix and enhancing proliferation/activation of resident parenchymal and mesenchymal cells. This review will focus on the multifaceted role of hepatic macrophages, including KCs and MoMFs, and their spatial distribution and roles during acute liver injury.

Hepatocarcinogenesis Is Supported by Sublethal Necroptosis Signaling

NF-κB activation in hepatocytes with low RIPK3 expression can trigger sublethal necrosome activation.

Apical bulkheads accumulate as adaptive response to impaired bile flow in liver disease

Hepatocytes form bile canaliculi that dynamically respond to the signalling activity of bile acids and bile flow. Little is known about their responses to intraluminal pressure. During embryonic development, hepatocytes assemble apical bulkheads that increase the canalicular resistance to intraluminal pressure. Here, we investigate whether they also protect bile canaliculi against elevated pressure upon impaired bile flow in adult liver. Apical bulkheads accumulate upon bile flow obstruction in mouse models and patients with primary sclerosing cholangitis (PSC). Their loss under these conditions leads to abnormally dilated canaliculi, resembling liver cell rosettes described in other hepatic diseases. 3D reconstruction reveals that these structures are sections of cysts and tubes formed by hepatocytes. Mathematical modelling establishes that they positively correlate with canalicular pressure and occur in early PSC stages. Using primary hepatocytes and 3D organoids, we demonstrate that excessive canalicular pressure causes the loss of apical bulkheads and formation of rosettes. Our results suggest that apical bulkheads are a protective mechanism of hepatocytes against impaired bile flow, highlighting the role of canalicular pressure in liver diseases.

Modulation of the immune response by the host defense peptide IDR-1002 in chicken hepatic cell culture

IDR-1002, a synthetic host defense peptide (HDP), appears to be a potential candidate for the treatment of bacterial infections and the consequent inflammatory response due to its potent immunomodulatory activity. This is of relevance to the emerging issue of antimicrobial resistance in the farming sector. In this study, the effects of IDR-1002 were investigated on a chicken hepatocyte‒non-parenchymal cell co-culture, and the results revealed that IDR-1002 had complex effects on the regulation of the hepatic innate immunity. IDR-1002 increased the levels of both RANTES (Regulated on Activation, Normal T cell Expressed and Secreted) and Macrophage colony stimulating factor (M-CSF), suggesting the peptide plays a role in the modulation of macrophage differentiation, also reflected by the reduced concentrations of interleukin (IL)-6 and IL-10. The pro-inflammatory cytokine release triggered by the bacterial cell wall component lipoteichoic acid (LTA) was ameliorated by the concomitantly applied IDR-1002 based on the levels of IL-6, chicken chemotactic and angiogenic factor (CXCLi2) and interferon (IFN)-γ. Moreover, the production of nuclear factor erythroid 2-related factor 2 (Nrf2), an essential transcription factor in the antioxidant defense pathway, was increased after IDR-1002 exposure, while protein carbonyl (PC) levels were also elevated. These findings suggest that IDR-1002 affects the interplay of the cellular immune response and redox homeostasis, thus the peptide represents a promising tool in the treatment of bacterially induced inflammation in chickens.

CD73 mitigates hepatic damage in alcoholic steatohepatitis by regulating PI3K/AKT-mediated hepatocyte pyroptosis

BACKGROUND

Alcohol use is a major risk factor for death and disability, resulting in a significant global disease burden. Alcoholic steatohepatitis (ASH) reflects an acute exacerbation of alcoholic liver disease (ALD) and is a growing health care and economic burden worldwide. Pyroptosis plays a central role in the pathogenesis of ASH. Nt5e (CD73) is a cell surface ecto-5'-nucleotidase, which is a key enzyme that converts the proinflammatory signal ATP to the anti-inflammatory mediator adenosine (ADO). Studies have found that CD73 is involved in multiple diseases and can alleviate gasdermin D (GSDMD)-mediated pyroptosis; however, its role and mechanism in ASH are not explicit.

AIM

To investigate the role and mechanisms of CD73-mediated hepatocyte pyroptosis in alcohol-induced liver injury through in vivo and in vitro experiments.

METHODS

CD73 knockout (CD73-/-) mice, wild-type (WT) mice, and AML-12 cells were used to evaluate the effect of CD73 on hepatocyte pyroptosis in vivo and in vitro. A combination of molecular and histological methods was performed to assess pyroptosis and investigate the mechanism both in vivo and in vitro.

RESULTS

The protein expression of CD73 and pyroptosis pathway-associated genes was increased significantly in hepatocyte injury model both in vivo and in vitro. In vivo, CD73 knockout dramatically aggravated inflammatory damage, lipid accumulation, and hepatocyte pyroptosis in the liver. In vitro, overexpression of CD73 by pEGFP-C1/CD73 can decrease NLRP3 inflammasome activation and pyroptosis in hepatocytes. Further analysis revealed that the phosphatidylinositol 3-kinase (PI3K)/protein kinase B (AKT) signaling pathway is a possible mechanism of CD73 regulation. Meanwhile, this pathological process was inhibited after the use of PI3K inhibitors.

CONCLUSION

Our results show a novel function of CD73 regulates hepatocytes pyroptosis and highlights the therapeutic opportunity for reducing the disease process in ALD.

Single-cell RNA transcriptome landscape of murine liver following systemic administration of mesoporous silica nanoparticles

Due to the unique physicochemical properties, mesoporous silica nanoparticles (MONs) have been widely utilized in biomedical fields for drug delivery, gene therapy, disease diagnosis and imaging. With the extensive applications and large-scale production of MONs, the potential effects of MONs on human health are gaining increased attention. To better understand the cellular and molecular mechanisms underlying the effects of MONs on the mouse liver, we profiled the transcriptome of 63,783 single cells from mouse livers following weekly intravenous administration of MONs for 2 weeks. The results showed that the proportion of endothelial cells and CD4+ T cells was increased, whereas that of Kupffer cells was decreased, in a dose-dependent manner after MONs treatment in the mouse liver. We also observed that the proportion of inflammation-related Kupffer cell subtype and wound healing-related hepatocyte subtype were elevated, but the number of hepatocytes with detoxification characteristics was reduced after MONs treatment. The cell-cell communication network revealed that there was more crosstalk between cholangiocytes and Kupffer cells, liver capsular macrophages, hepatic stellate cells, and endothelial cells following MONs treatment. Furthermore, we identified key ligand-receptor pairs between crucial subtypes after MONs treatment that are known to promote liver fibrosis. Collectively, our study explored the effects of MONs on mouse liver at a single-cell level and provides comprehensive information on the potential hepatotoxicity of MONs.

Protective effects of caffeine against palmitate-induced lipid toxicity in primary rat hepatocytes is associated with modulation of adenosine receptor A1 signaling

BACKGROUND

Epidemiological evidence has shown an association between coffee consumption and reduced risk for chronic liver diseases, including metabolic-dysfunction-associated liver disease (MALFD). Lipotoxicity is a key cause of hepatocyte injury during MAFLD. The coffee component caffeine is known to modulate adenosine receptor signaling via the antagonism of adenosine receptors. The involvement of these receptors in the prevention of hepatic lipotoxicity has not yet been explored. The aim of this study was to explore whether caffeine protects against palmitate-induced lipotoxicity by modulating adenosine receptor signaling.

METHODS

Primary hepatocytes were isolated from male rats. Hepatocytes were treated with palmitate with or without caffeine or 1,7DMX. Lipotoxicity was verified using Sytox viability staining and mitochondrial JC-10 staining. PKA activation was verified by Western blotting. Selective (ant)agonists of A1AR (DPCPX and CPA, respectively) and A2AR (istradefyline and regadenoson, respectively), the AMPK inhibitor compound C, and the Protein Kinase A (PKA) inhibitor Rp8CTP were used. Lipid accumulation was verified by ORO and BODIPY 453/50 staining.

RESULTS

Caffeine and its metabolite 1,7DMX prevented palmitate-induced toxicity in hepatocytes. The A1AR antagonist DPCPX also prevented lipotoxicity, whereas both the inhibition of PKA and the A1AR agonist CPA (partially) abolished the protective effect. Caffeine and DPCPX increased lipid droplet formation only in palmitate-treated hepatocytes and decreased mitochondrial ROS production.

CONCLUSIONS

The protective effect of caffeine against palmitate lipotoxicity was shown to be dependent on A1AR receptor and PKA activation. Antagonism of A1AR also protects against lipotoxicity. Targeting A1AR receptor may be a potential therapeutic intervention with which to treat MAFLD.

Molybdenum and/or cadmium induce NLRP3 inflammasome production by causing mitochondria-associated endoplasmic reticulum membrane dysfunction in sheep hepatocytes

Accumulation of the heavy metals molybdenum (Mo) and cadmium (Cd) in the liver can induce organelle damage and inflammation, resulting in hepatotoxicity. The effect of Mo and/or Cd on sheep hepatocytes was investigated by determining the relationship between the mitochondria-associated endoplasmic reticulum membrane (MAM) and NLRP3 inflammasome. Sheep hepatocytes were divided into four groups: the control group, Mo group (600 μM Mo), Cd group (4 μM Cd) and Mo + Cd group (600 μM Mo+4 μM Cd). The results showed that Mo and/or Cd exposure increased the levels of lactate dehydrogenase (LDH) and nitric oxide (NO) in the cell culture supernatant, elevated the levels of intracellular Ca2+ and mitochondrial Ca2+, downregulated the expression of MAM-related factors (IP3R, GRP75, VDAC1, PERK, ERO1-α, Mfn1, Mfn2, ERP44), shortened the length of the MAM and reduced the formation of the MAM structure, eventually causing MAM dysfunction. Moreover, the expression levels of NLRP3 inflammasome-related factors (NLRP3, Caspase1, IL-1β, IL-6, TNF-α) were also dramatically increased after Mo and Cd exposure, triggering NLRP3 inflammasome production. However, an IP3R inhibitor, 2-APB treatment significantly alleviated these changes. Overall, the data indicate that Mo and Cd coexposure leads to structural disruption and dysfunction of MAM, disrupts cellular Ca2+ homeostasis, and increases NLRP3 inflammasome production in sheep hepatocytes. However, the inhibition of IP3R alleviates NLRP3 inflammasome production induced by Mo and Cd.

Mechanism of action and side effects of colchicine based on biomechanical properties of cells

Many diseases are related to changes in the biomechanical properties of cells; their study can provide a theoretical basis for drug screening and can explain the internal working of living cells. In this study, the biomechanical properties of nephrocytes (VERO cells), hepatocytes (HL-7702 cells), and hepatoma cells (SMCC-7721 cells) in culture were detected by atomic force microscopy (AFM) to analyse the side effects of colchicine at different concentrations (0.1 μg/mL (A) and 0.2 μg/mL (B)) at the nanoscale for 2, 4 and 6 h. Compared with the corresponding control cells, the damage to the treated cells increased in a dose-dependent manner. Among normal cells, the injury of nephrocytes (VERO cells) was markedly worse than that of hepatocytes (HL-7702 cells) in both colchicine solutions A and B. Based on the analyses of biomechanical properties, the colchicine solution reduced the rate of division and inhibited metastasis of SMCC-7721 cells. By comparing these two concentrations, we found that the anticancer effect of colchicine solution A was greater than that of solution B. Studying the mechanical properties of biological cells can help understand the mechanism of drug action at the molecular level and provide a theoretical basis for preventing the emergence and diagnosis of diseases at the nanoscale.

Comparative analysis of YAP/TEAD inhibitors in 2D and 3D cultures of primary human hepatocytes reveals a novel non-canonical mechanism of CYP induction

Induction of cytochrome P450 (CYP) genes constitutes an important cause of drug-drug interactions and preclinical evaluation of induction liability is mandatory for novel drug candidates. YAP/TEAD signaling has emerged as an attractive target for various oncological indications and multiple chemically distinct YAP/TEAD inhibitors are rapidly progressing towards clinical stages. Here, we tested the liability for CYP induction of a diverse set of YAP/TEAD inhibitors with different modes of action and TEAD isoform selectivity profiles in monolayers and 3D spheroids of primary human hepatocytes (PHH). We found that YAP/TEAD inhibition resulted in broad induction of CYPs in 2D monolayers, whereas, if at all, only marginal induction was seen in spheroid culture. Comprehensive RNA-Seq indicated that YAP/TEAD signaling was increased in 2D culture compared to spheroids, which was paralleled by elevated activities of the interacting transcription factors LXR and ESRRA, likely at least in part due to altered mechanosensing. Inhibition of this YAP/TEAD hyperactivation resulted in an overall reduction of hepatocyte dedifferentiation marked by increased hepatic functionality, including CYPs. These results thus demonstrate that the observed induction is due to on-target effects of the compounds rather than direct activation of xenobiotic sensing nuclear receptors. Combined, the presented data link hepatocyte dedifferentiation to YAP/TEAD dysregulation, reveal a novel non-canonical pathway of CYP induction and highlight the advantage of organotypic 3D cultures to predict clinically relevant pharmacokinetic properties, particularly for atypical induction mechanisms.

Scalable production of tissue-like vascularized liver organoids from human PSCs

The lack of physiological parity between 2D cell culture and in vivo culture has led to the development of more organotypic models, such as organoids. Organoid models have been developed for a number of tissues, including the liver. Current organoid protocols are characterized by a reliance on extracellular matrices (ECMs), patterning in 2D culture, costly growth factors and a lack of cellular diversity, structure, and organization. Current hepatic organoid models are generally simplistic and composed of hepatocytes or cholangiocytes, rendering them less physiologically relevant compared to native tissue. We have developed an approach that does not require 2D patterning, is ECM independent, and employs small molecules to mimic embryonic liver development that produces large quantities of liver-like organoids. Using single-cell RNA sequencing and immunofluorescence, we demonstrate a liver-like cellular repertoire, a higher order cellular complexity, presenting with vascular luminal structures, and a population of resident macrophages: Kupffer cells. The organoids exhibit key liver functions, including drug metabolism, serum protein production, urea synthesis and coagulation factor production, with preserved post-translational modifications such as N-glycosylation and functionality. The organoids can be transplanted and maintained long term in mice producing human albumin. The organoids exhibit a complex cellular repertoire reflective of the organ and have de novo vascularization and liver-like function. These characteristics are a prerequisite for many applications from cellular therapy, tissue engineering, drug toxicity assessment, and disease modeling to basic developmental biology.

9-POHSA prevents NF-kB activation and ameliorates LPS-induced inflammation in rat hepatocytes

Liver inflammation has become increasingly prevalent in recent years, leading to the development of diseases like hepatitis, alcoholic liver disease, and fatty liver disease. One factor that has been linked to liver inflammation is increased levels of lipopolysaccharides (LPS), which can be caused by poor diets and sedentary lifestyles that contribute to liver inflammation. There is promising research on a new class of lipids called fatty acid esters of hydroxy fatty acids (FAHFAs), which have been shown to potentiate insulin release and exert an anti-inflammatory effect. Specifically, one type of FAHFA called 9-POHSA (palmitoleic acid ester of 9-hydroxy stearic acid) has been studied for its potential to attenuate inflammation-related indexes induced by LPS in hepatocytes, which play a critical role in the progression of liver inflammation. This study found that following LPS treatment, tumor necrosis factor- α, interleukin-6, and connective tissue growth factor (CTGF) were upregulated and increased cell migration, but 9-POHSA pre-treatment attenuated the upregulation of these markers and prevented cell migration induced by LPS. Using flowcytometry analysis, intracellular reactive oxygen species (ROS) was found to be responsible for CTGF upregulation. In addition, the effects of 9-POHSA were likely associated with its inhibition of the activation of the NF-kB. These results suggest that 9-POHSA has potential as a therapy for liver inflammation and fibrosis by attenuating inflammation-related indexes induced by LPS in hepatocytes. This study provides important insight into the mechanisms of liver inflammation and the potential for new treatments to address liver diseases.

Conserved use of the sodium/bile acid cotransporter (NTCP) as an entry receptor by hepatitis B virus and domestic cat hepadnavirus

The Orthohepadnavirus genus includes hepatitis B virus (HBV) that can cause chronic hepatitis and hepatocarcinoma in humans. Recently, a novel hepadnavirus in cats, domestic cat hepadnavirus (DCH), was identified that is genetically close to HBV. DCH infection is associated with chronic hepatitis in cats, suggesting a similarity with HBV pathogenesis and the potential to use DCH as a novel animal model for HBV research. HBV is shown to use the sodium/bile acid cotransporter (NTCP) as a major cell entry receptor, but the equivalent receptor for DCH remains unknown. Here we sought to identify the entry receptor for DCH. HBV- and DCH-derived preS1 peptides efficiently bound to both human and cat NTCPs, and residue 158 of NTCP proteins determined the species-specific binding of the DCH preS1 peptide. Myrcludex B, an HBV entry inhibitor, blocked the binding of the DCH preS1 peptide. Thus, DCH and HBV may share cell entry molecules, suggesting a possibility of inter-species transmission. Furthermore, our study suggests that DCH can be useful as a novel model for HBV research.

Towards reliable hepatocytic anatomy segmentation in laparoscopic cholecystectomy using U-Net with Auto-Encoder

BACKGROUND

Most bile duct (BDI) injuries during laparoscopic cholecystectomy (LC) occur due to visual misperception leading to the misinterpretation of anatomy. Deep learning (DL) models for surgical video analysis could, therefore, support visual tasks such as identifying critical view of safety (CVS). This study aims to develop a prediction model of CVS during LC. This aim is accomplished using a deep neural network integrated with a segmentation model that is capable of highlighting hepatocytic anatomy.

METHODS

Still images from LC videos were annotated with four hepatocystic landmarks of anatomy segmentation. A deep autoencoder neural network with U-Net to investigate accurate medical image segmentation was trained and tested using fivefold cross-validation. Accuracy, Loss, Intersection over Union (IoU), Precision, Recall, and Hausdorff Distance were computed to evaluate the model performance versus the annotated ground truth.

RESULTS

A total of 1550 images from 200 LC videos were annotated. Mean IoU for segmentation was 74.65%. The proposed approach performed well for automatic hepatocytic landmarks identification with 92% accuracy and 93.9% precision and can segment challenging cases.

CONCLUSION

DL, can potentially provide an intraoperative model for surgical video analysis and can be trained to guide surgeons toward reliable hepatocytic anatomy segmentation and produce selective video documentation of this safety step of LC.

Recapitulation of Skewed X-Inactivation in Female Ornithine Transcarbamylase-Deficient Primary Human Hepatocytes in the FRG Mouse: A Novel System for Developing Epigenetic Therapies

Realization of the immense therapeutic potential of epigenetic editing requires development of clinically predictive model systems that faithfully recapitulate relevant aspects of the target disease pathophysiology. In female patients with ornithine transcarbamylase (OTC) deficiency, an X-linked condition, skewed inactivation of the X chromosome carrying the wild-type OTC allele is associated with increased disease severity. The majority of affected female patients can be managed medically, but a proportion require liver transplantation. With rapid development of epigenetic editing technology, reactivation of silenced wild-type OTC alleles is becoming an increasingly plausible therapeutic approach. Toward this end, privileged access to explanted diseased livers from two affected female infants provided the opportunity to explore whether engraftment and expansion of dissociated patient-derived hepatocytes in the FRG mouse might produce a relevant model for evaluation of epigenetic interventions. Hepatocytes from both infants were successfully used to generate chimeric mouse-human livers, in which clusters of primary human hepatocytes were either OTC positive or negative by immunohistochemistry (IHC), consistent with clonal expansion from individual hepatocytes in which the mutant or wild-type OTC allele was inactivated, respectively. Enumeration of the proportion of OTC-positive or -negative human hepatocyte clusters was consistent with dramatic skewing in one infant and minimal to modest skewing in the other. Importantly, IHC and fluorescence-activated cell sorting analysis of intact and dissociated liver samples from both infants showed qualitatively similar patterns, confirming that the chimeric mouse-human liver model recapitulated the native state in each infant. Also of importance was the induction of a treatable metabolic phenotype, orotic aciduria, in mice, which correlated with the presence of clonally expanded OTC-negative primary human hepatocytes. We are currently using this unique model to explore CRISPR-dCas9-based epigenetic targeting strategies in combination with efficient adeno-associated virus (AAV) gene delivery to reactivate the silenced functional OTC gene on the inactive X chromosome.

Evaluation of the Selectivity of Several Organic Anion Transporting Polypeptide 1B Biomarkers Using Relative Activity Factor Method

In recent years, some endogenous substrates of organic anion transporting polypeptide 1B (OATP1B) have been identified and characterized as potential biomarkers to assess OATP1B-mediated clinical drug-drug interactions (DDIs). However, quantitative determination of their selectivity to OATP1B is still limited. In this study, we developed a relative activity factor (RAF) method to determine the relative contribution of hepatic uptake transporters OATP1B1, OATP1B3, OATP2B1, and sodium-taurocholate co-transporting polypeptide (NTCP) on hepatic uptake of several OATP1B biomarkers, including coproporphyrin I (CPI), coproporphyrin I CPIII, and sulfate conjugates of bile acids: glycochenodeoxycholic acid sulfate (GCDCA-S), glycodeoxycholic acid sulfate (GDCA-S), and taurochenodeoxycholic acid sulfate (TCDCA-S). RAF values for OATP1B1, OATP1B3, OATP2B1, and NTCP were determined in cryopreserved human hepatocytes and transporter transfected cells using pitavastatin, cholecystokinin, resveratrol-3-O-β-D-glucuronide, and taurocholic acid (TCA) as reference compounds, respectively. OATP1B1-specific pitavastatin uptake in hepatocytes was measured in the absence and presence of 1 µM estropipate, whereas NTCP-specific TCA uptake was measured in the presence of 10 µM rifampin. Our studies suggested that CPI was a more selective biomarker for OATP1B1 than CPIII, whereas GCDCA-S and TCDCA-S were more selective to OATP1B3. OATP1B1 and OATP1B3 equally contributed to hepatic uptake of GDCA-S. The mechanistic static model, incorporating the fraction transported of CPI/III estimated by RAF and in vivo elimination data, predicted several perpetrator interactions with CPI/III. Overall, RAF method combined with pharmacogenomic and DDI studies is a useful tool to determine the selectivity of transporter biomarkers and facilitate the selection of appropriate biomarkers for DDI evaluation. SIGNIFICANCE STATEMENT: The authors developed a new relative activity factor (RAF) method to quantify the contribution of hepatic uptake transporters organic anion transporting polypeptide (OATP)1B1, OATP1B3, OATP2B1, and sodium taurocholate co-transporting polypeptide (NTCP) on several OATP1B biomarkers and evaluated their predictive value on drug-drug interactions (DDI). These studies suggest that the RAF method is a useful tool to determine the selectivity of transporter biomarkers. This method combined with pharmacogenomic and DDI studies will mechanistically facilitate the selection of appropriate biomarkers for DDI prediction.

Tangeretin and 4'-demethyltangeretin prevent damage to mouse hepatocytes from oxidative stress by activating the Nrf2-related antioxidant pathway via an epigenetic mechanism

Polymethoxyflavones (PMFs) in citrus fruits have a variety of biological activities, including antioxidant, anti-inflammatory, anticancer, and anti-atherosclerotic effects. The liver is the major detoxifying organ of the human body; however, factors such as acetaminophen (APAP) overdose may increase oxidative stress in liver cells and lead to severe liver failure. In this study we examined the effects of tangeretin (TAN), a common citrus PMF, and its metabolite 4'-demethyltangeretin (4'-OH-TAN) on activation of the Nrf2 antioxidant system in mouse AML-12 hepatocytes through regulation by epigenetic mechanisms. The ability of TAN and 4'-OH-TAN to inhibit APAP-induced hepatotoxicity was also evaluated. The results showed that TAN and 4'-OH-TAN significantly increased the mRNA and protein levels of Nrf2 and Nrf2-mediated antioxidant and detoxifying enzymes (UGT1A, HO-1, and NQO1) in AML-12 cells. TAN and 4'-OH-TAN also suppressed protein expression of histone deacetylases (HDACs) and DNA methyltransferases (DMNTs) and reduced DNA methylation of the nrf2 promoter. Furthermore, TAN and 4'-OH-TAN prevented APAP-induced injury and inhibited APAP-induced ROS generation in AML-12 cells. Based on these results, we conclude that TAN and 4'-OH-TAN may increase the antioxidant capacity of liver cells by regulating epigenetic alteration to activate the Nrf2-related antioxidant system, thereby preventing liver cells from being damaged by APAP-induced oxidative stress.

Aflatoxin B1 in poultry liver: Toxic mechanism

Aflatoxin B1 (AFB1) is the most common carcinogenic toxin in livestock and poultry feed, seriously endangering poultry production and public health. Liver is the most important organ for the metabolism of exogenous and endogenous substances in the body. AFB1 produces toxicity under the biotransformation of cytochrome P450 microparticle oxidase (CYP450). Hepatocytes are the most important cells for synthesizing CYP450 enzymes, so that AFB1 has the most significant effect on the liver. AFB1 can induce liver cell damage in poultry through a variety of molecular mechanisms, and the main of damage mechanisms have been discovered so far include oxidative damage, promoting apoptosis, influencing hepatocyte gene expression, interfering with hepatocyte autophagy, pyroptosis and necroptosis. This article reviewed the molecular mechanism of AFB1 inducing liver injury in poultry, hopefully, to provid a new direction and theoretical basis for the development of a new AFB1 detoxification method.

Evaluation of Human Hepatocyte Drug Metabolism Carrying High-Risk or Protection-Associated Liver Disease Genetic Variants

Metabolic-dysfunction-associated steatotic liver disease (MASLD), which affects 30 million people in the US and is anticipated to reach over 100 million by 2030, places a significant financial strain on the healthcare system. There is presently no FDA-approved treatment for MASLD despite its public health significance and financial burden. Understanding the connection between point mutations, liver enzymes, and MASLD is important for comprehending drug toxicity in healthy or diseased individuals. Multiple genetic variations have been linked to MASLD susceptibility through genome-wide association studies (GWAS), either increasing MASLD risk or protecting against it, such as PNPLA3 rs738409, MBOAT7 rs641738, GCKR rs780094, HSD17B13 rs72613567, and MTARC1 rs2642438. As the impact of genetic variants on the levels of drug-metabolizing cytochrome P450 (CYP) enzymes in human hepatocytes has not been thoroughly investigated, this study aims to describe the analysis of metabolic functions for selected phase I and phase II liver enzymes in human hepatocytes. For this purpose, fresh isolated primary hepatocytes were obtained from healthy liver donors (n = 126), and liquid chromatography-mass spectrometry (LC-MS) was performed. For the cohorts, participants were classified into minor homozygotes and nonminor homozygotes (major homozygotes + heterozygotes) for five gene polymorphisms. For phase I liver enzymes, we found a significant difference in the activity of CYP1A2 in human hepatocytes carrying MBOAT7 (p = 0.011) and of CYP2C8 in human hepatocytes carrying PNPLA3 (p = 0.004). It was also observed that the activity of CYP2C9 was significantly lower in human hepatocytes carrying HSD17B13 (p = 0.001) minor homozygous compared to nonminor homozygous. No significant difference in activity of CYP2E1, CYP2C8, CYP2D6, CYP2E1, CYP3A4, ECOD, FMO, MAO, AO, and CES2 and in any of the phase II liver enzymes between human hepatocytes carrying genetic variants for PNPLA3 rs738409, MBOAT7 rs641738, GCKR rs780094, HSD17B13 rs72613567, and MTARC1 rs2642438 were observed. These findings offer a preliminary assessment of the influence of genetic variations on drug-metabolizing cytochrome P450 (CYP) enzymes in healthy human hepatocytes, which may be useful for future drug discovery investigations.

Forced Hepatic Expression of NRF2 or NQO1 Impedes Hepatocyte Lipid Accumulation in a Lipodystrophy Mouse Model

Lipodystrophy is a disorder featuring loss of normal adipose tissue depots due to impaired production of normal adipocytes. It leads to a gain of fat deposition in ectopic tissues such as liver and skeletal muscle that results in steatosis, dyslipidemia, and insulin resistance. Previously, we established a Rosa NIC/NIC::AdiCre lipodystrophy model mouse. The lipodystrophic phenotype that included hepatomegaly accompanied with hepatic damage due to higher lipid accumulation was attenuated substantially by amplified systemic NRF2 signaling in mice with hypomorphic expression of Keap1; whole-body Nrf2 deletion abrogated this protection. To determine whether hepatic-specific NRF2 signaling would be sufficient for protection against hepatomegaly and fatty liver development, direct, powerful, transient expression of Nrf2 or its target gene Nqo1 was achieved by administration through hydrodynamic tail vein injection of pCAG expression vectors of dominant-active Nrf2 and Nqo1 in Rosa NIC/NIC::AdiCre mice fed a 9% fat diet. Both vectors enabled protection from hepatic damage, with the pCAG-Nqo1 vector being the more effective as seen with a ~50% decrease in hepatic triglyceride levels. Therefore, activating NRF2 signaling or direct elevation of NQO1 in the liver provides new possibilities to partially reduce steatosis that accompanies lipodystrophy.

Non-alcoholic fatty liver disease: Immunological mechanisms and current treatments

Non-alcoholic fatty liver disease (NAFLD) causes significant global disease burden and is a leading cause of mortality. NAFLD induces a myriad of aberrant changes in hepatocytes at both the cellular and molecular level. Although the disease spectrum of NAFLD is widely recognised, the precise triggers for disease progression are still to be fully elucidated. Furthermore, the propagation to cirrhosis is poorly understood. Whilst some progress in terms of treatment options have been explored, an incomplete understanding of the hepatic cellular and molecular alterations limits their clinical utility. We have therefore reviewed some of the key pathways responsible for the pathogenesis of NAFLD such as innate and adaptative immunity, lipotoxicity and fibrogenesis, and highlighted current trials and treatment options for NAFLD patients.

Protective effect of manganese treatment on insulin resistance in HepG2 hepatocytes

Introduction

Objectives: manganese (Mn) is closely related to type 2 diabetes mellitus and insulin resistance (IR), but the exact mechanism is unclear. This study aimed to explore the regulatory effects and mechanism of Mn on IR using hepatocyte IR model induced by high palmitate (PA), high glucose (HG) or insulin. Methods: HepG2 cells were exposed to PA (200 μM), HG (25 mM) or insulin (100 nM) respectively, alone or with 5 μM Mn for 24 hours. The expression of key proteins in insulin signaling pathway, intracellular glycogen content and glucose accumulation, reactive oxygen species (ROS) level and Mn superoxide dismutase (MnSOD) activity were detected. Results: compared with control group, the expression of phosphorylated protein kinase B (Akt), glycogen synthase kinase-3β (GSK-3β) and forkhead box O1 (FOXO1) in the three IR groups was declined, and this decrease was reversed by Mn. The reduction of intracellular glycogen content and increase in glucose accumulation in IR groups were also inhibited by Mn. Additionally, the production of ROS was increased in IR models, compared with normal control group, while Mn reduced the excessive production of ROS induced by PA, HG or insulin. However, Mn did not alter the activity of MnSOD in the three IR models. Conclusion: this study demonstrated that Mn treatment can improve IR in hepatocytes. The mechanism is probably by reducing the level of intracellular oxidative stress, enhancing the activity of Akt/GSK-3β/FOXO1 signal pathway, promoting glycogen synthesis, and inhibiting gluconeogenesis.

Acute Deletion of the Glucocorticoid Receptor in Hepatocytes Disrupts Postprandial Lipid Metabolism in Male Mice

Hepatic lipid metabolism is highly dynamic, and disruption of several circadian transcriptional regulators results in hepatic steatosis. This includes genetic disruption of the glucocorticoid receptor (GR) as the liver develops. To address the functional role of GR in the adult liver, we used an acute hepatocyte-specific GR knockout model to study temporal hepatic lipid metabolism governed by GR at several preprandial and postprandial circadian timepoints. Lipidomics analysis revealed significant temporal lipid metabolism, where GR disruption results in impaired regulation of specific triglycerides, nonesterified fatty acids, and sphingolipids. This correlates with increased number and size of lipid droplets and mildly reduced mitochondrial respiration, most noticeably in the postprandial phase. Proteomics and transcriptomics analyses suggest that dysregulated lipid metabolism originates from pronounced induced expression of enzymes involved in fatty acid synthesis, β-oxidation, and sphingolipid metabolism. Integration of GR cistromic data suggests that induced gene expression is a result of regulatory actions secondary to direct GR effects on gene transcription.

Hepatic SREBP signaling requires SPRING to govern systemic lipid metabolism in mice and humans

The sterol regulatory element binding proteins (SREBPs) are transcription factors that govern cholesterol and fatty acid metabolism. We recently identified SPRING as a post-transcriptional regulator of SREBP activation. Constitutive or inducible global ablation of Spring in mice is not tolerated, and we therefore develop liver-specific Spring knockout mice (LKO). Transcriptomics and proteomics analysis reveal attenuated SREBP signaling in livers and hepatocytes of LKO mice. Total plasma cholesterol is reduced in male and female LKO mice in both the low-density lipoprotein and high-density lipoprotein fractions, while triglycerides are unaffected. Loss of Spring decreases hepatic cholesterol and triglyceride content due to diminished biosynthesis, which coincides with reduced very-low-density lipoprotein secretion. Accordingly, LKO mice are protected from fructose diet-induced hepatosteatosis. In humans, we find common genetic SPRING variants that associate with circulating high-density lipoprotein cholesterol and ApoA1 levels. This study positions SPRING as a core component of hepatic SREBP signaling and systemic lipid metabolism in mice and humans.

ACLY as a modulator of liver cell functions and its role in Metabolic Dysfunction-Associated Steatohepatitis

BACKGROUND

Non-alcoholic Fatty Liver Disease (NAFLD), now better known as Metabolic (Dysfunction)-Associated Fatty Liver Disease (MAFLD) and its progression to Nonalcoholic Steatohepatitis (NASH), more recently referred to as Metabolic (Dysfunction)-Associated Steatohepatitis (MASH) are the most common causes of liver failure and chronic liver damage. The new names emphasize the metabolic involvement both in relation to liver function and pathological features with extrahepatic manifestations. This study aims to explore the role of the immunometabolic enzyme ATP citrate lyase (ACLY), with a critical function in lipogenesis, carbohydrate metabolism, gene expression and inflammation.

METHODS

ACLY function was investigated in TNFα-triggered human hepatocytes and in PBMC-derived macrophages from MASH patients. Evaluation of expression levels was carried out by western blotting and/or RT-qPCR. In the presence or absence of ACLY inhibitors, ROS, lipid peroxidation and GSSG oxidative stress biomarkers were quantified. Chromatin immunoprecipitation (ChIP), transient transfections, immunocytochemistry, histone acetylation quantitation were used to investigate ACLY function in gene expression reprogramming. IL-6 and IL-1β were quantified by Lumit immunoassays.

RESULTS

Mechanistically, ACLY inhibition reverted lipid accumulation and oxidative damage while reduced secretion of inflammatory cytokines in TNFα-triggered human hepatocytes. These effects impacted not only on lipid metabolism but also on other crucial features of liver function such as redox status and production of inflammatory mediators. Moreover, ACLY mRNA levels together with those of malic enzyme 1 (ME1) increased in human PBMC-derived macrophages from MASH patients when compared to age-matched healthy controls. Remarkably, a combination of hydroxycitrate (HCA), the natural ACLY inhibitor, with red wine powder (RWP) significantly lowered ACLY and ME1 mRNA amount as well as IL-6 and IL-1β production in macrophages from subjects with MASH.

CONCLUSION

Collectively, our findings for the first time highlight a broad spectrum of ACLY functions in liver as well as in the pathogenesis of MASH and its diagnostic and therapeutic potential value.

Exosomal MicroRNA and Protein Profiles of Hepatitis B Virus-Related Hepatocellular Carcinoma Cells

Infection with hepatitis B virus (HBV) is a main risk factor for hepatocellular carcinoma (HCC). Extracellular vesicles, such as exosomes, play an important role in tumor development and metastasis, including regulation of HBV-related HCC. In this study, we have characterized exosome microRNA and proteins released in vitro from hepatitis B virus (HBV)-related HCC cell lines SNU-423 and SNU-182 and immortalized normal hepatocyte cell lines (THLE2 and THLE3) using microRNA sequencing and mass spectrometry. Bioinformatics, including functional enrichment and network analysis, combined with survival analysis using data related to HCC in The Cancer Genome Atlas (TCGA) database, were applied to examine the prognostic significance of the results. More than 40 microRNAs and 200 proteins were significantly dysregulated (p < 0.05) in the exosomes released from HCC cells in comparison with the normal liver cells. The functional analysis of the differentially expressed exosomal miRNAs (i.e., mir-483, mir-133a, mir-34a, mir-155, mir-183, mir-182), their predicted targets, and exosomal differentially expressed proteins (i.e., POSTN, STAM, EXOC8, SNX9, COL1A2, IDH1, FN1) showed correlation with pathways associated with HBV, virus activity and invasion, exosome formation and adhesion, and exogenous protein binding. The results from this study may help in our understanding of the role of HBV infection in the development of HCC and in the development of new targets for treatment or non-invasive predictive biomarkers of HCC.

Induction of open-form bile canaliculus formation by hepatocytes for evaluation of biliary drug excretion

Biliary excretion is a major drug elimination pathway that affects their efficacy and safety. The currently available in vitro sandwich-cultured hepatocyte method is cumbersome because drugs accumulate in the closed bile canalicular lumen formed between hepatocytes and their amounts cannot be mealsured directly. This study proposes a hepatocyte culture model for the rapid evaluation of drug biliary excretion using permeation assays. When hepatocytes are cultured on a permeable support coated with the cell adhesion protein claudins, an open-form bile canalicular lumen is formed at the surface of the permeable support. Upon application to the basolateral (blood) side, drugs appear on the bile canalicular side. The biliary excretion clearance of several drugs, as estimated from the obtained permeabilities, correlates well with the reported in vivo biliary excretion clearance in humans. Thus, the established model is useful for applications in the efficient evaluation of biliary excretion during drug discovery and development.

Liver Injury and Regeneration: Current Understanding, New Approaches, and Future Perspectives

The liver is a complex organ with the ability to regenerate itself in response to injury. However, several factors can contribute to liver damage beyond repair. Liver injury can be caused by viral infections, alcoholic liver disease, non-alcoholic steatohepatitis, and drug-induced liver injury. Understanding the cellular and molecular mechanisms involved in liver injury and regeneration is critical to developing effective therapies for liver diseases. Liver regeneration is a complex process that involves the interplay of various signaling pathways, cell types, and extracellular matrix components. The activation of quiescent hepatocytes that proliferate and restore the liver mass by upregulating genes involved in cell-cycle progression, DNA repair, and mitochondrial function; the proliferation and differentiation of progenitor cells, also known as oval cells, into hepatocytes that contribute to liver regeneration; and the recruitment of immune cells to release cytokines and angiogenic factors that promote or inhibit cell proliferation are some examples of the regenerative processes. Recent advances in the fields of gene editing, tissue engineering, stem cell differentiation, small interfering RNA-based therapies, and single-cell transcriptomics have paved a roadmap for future research into liver regeneration as well as for the identification of previously unknown cell types and gene expression patterns. In summary, liver injury and regeneration is a complex and dynamic process. A better understanding of the cellular and molecular mechanisms driving this phenomenon could lead to the development of new therapies for liver diseases and improve patient outcomes.