Tissue Repair in the Mouse Liver Following Acute Carbon Tetrachloride Depends on Injury-Induced Wnt/β-Catenin Signaling

Prunella vulgaris polyphenols alleviate liver injury-uveitis comorbidity by regulating acylcarnitine via the S100A9-PP2A-AMPK pathway

BACKGROUND

Liver injury and uveitis pose severe threats to human health. Owing to the close relationship of physiology and pathology between the liver and the eyes, cases in which both conditions occur simultaneously are not uncommon in clinical settings, significantly complicating treatment. However, no suitable comorbid animal model has been reported, and research on the pathological mechanisms of this comorbidity is lacking. Prunella vulgaris L., a well-known traditional Chinese medicine renowned for its liver-clearing and eye-brightening properties. Prunella vulgaris polyphenols (PVPs) hold promise for improving liver injury and uveitis. However, research exploring their dual therapeutic effects within a single organism remains lacking, leaving the key active components and mechanisms of action largely uninvestigated.

PURPOSE

This exploratory study aimed to establish a rat model of liver injury combined with uveitis and investigated its pathological mechanisms, evaluating the therapeutic efficacy of PVPs in alleviating liver injury combined with uveitis in rats. Additionally, it explored the mechanism of action and identified key active ingredients of PVPs, offering potential new directions for the development of clinical therapeutic drugs.

METHODS

A rat model of liver injury with uveitis was established through intraperitoneal d-GalN/LPS injection. Metabolomics and proteomics were applied to investigate pathological mechanisms, followed by validation using acylcarnitine and S100A9 inhibitors. PVPs were administered to evaluate therapeutic effects and explore mechanisms involved in alleviating liver injury and uveitis. Network pharmacology combined with molecular docking identified critical active components in PVPs. Subsequent animal experiments verified the efficacy of the representative component in improving liver injury and uveitis.

RESULTS

d-GalN/LPS (150 mg/kg : 1 mg/kg) induced significant liver injury and uveitis in rats. Metabolomics analysis pointed to acylcarnitine as a key metabolite, and its inhibition reduced inflammation. Proteomics analysis implicated S100A9 in inflammation and immunity. Then, we intervened with S100A9 inhibitors in the model rats. The results suggested that the pathological mechanism of liver injury and uveitis caused by d-GalN/LPS involved the upregulation of S100A9 expression, an increase in PP2A activity, the inhibition of AMPK phosphorylation, and the downregulation of CPT1A, leading to the accumulation of acylcarnitine and promoting the inflammatory response in the liver and retina. Further, experiments involving PVPs demonstrated dose-dependent improvements in liver injury and uveitis caused by d-GalN/LPS. The underlying mechanism of action involved suppression of S100A9 expression, reduction of PP2A activity, activation of AMPK, upregulation of CPT1A, and subsequent reduction in acylcarnitine accumulation in both the liver and retina. This mechanism effectively alleviated the inflammatory effects induced by d-GalN/LPS. Network pharmacology and molecular docking analyses pinpointed several key active components of PVPs-namely, rosmarinic acid, salviaflaside, esculetin, 2-hydroxycinnamic acid, 3,4-dihydroxybenzaldehyde, and 7,8-dihydroxycoumarin-that play significant roles in mitigating liver injury and uveitis. Follow-up experiments using the representative active component rosmarinic acid in rats confirmed its efficacy in improving symptoms of d-GalN/LPS-induced liver injury and uveitis, further validating the therapeutic potential of these key active components.

CONCLUSIONS

This study successfully established a rat model of liver injury combined with uveitis and confirmed the efficacy of PVPs in alleviating this condition. Furthermore, it determined that the underlying mechanism involves regulation of the S100A9-PP2A-AMPK pathway, with rosmarinic acid identified as a key active compound. These findings provide a basis for clinical studies on liver-eye comorbidities and offer critical evidence for further research and drug development of PVPs in liver-clearing and eye-brightening.

A combined "eat me/don't eat me" strategy based on exosome for acute liver injury treatment

Drug-induced liver injury (DILI) involves multifaceted pathogenesis, necessitating effective therapeutic strategies. Wnt2, secreted by liver sinusoidal endothelial cell (LSEC), activates the Wnt/β-catenin signaling pathway to promote hepatocyte proliferation after injury. To address the dual challenges of targeted delivery and phagocytosis evasion, we develop a combined "eat me/don't eat me" strategy. RLTRKRGLK (RLTR) peptide-functionalized exosomes are engineered by inserting DMPE-PEG2000-CRLTRKRGLK into the lipid membrane of exosome derived from bEnd.3 cell. Surface-displayed RLTR mediates exosomal enrichment in LSEC, while CD47 engineering reduces macrophage clearance via "don't eat me" signaling. Then, lentiviral transfection enables stable encapsulation of functional Wnt2 mRNA into ExoCD47 (designated Wnt2@ExoCD47). In both acetaminophen (APAP) and dimethylnitrosamine (DMN)-induced murine liver injury models, RLTR-Wnt2@ExoCD47 demonstrates LSEC-specific targeting and significant hepatoprotection. This engineered exosome platform provides a therapeutic strategy for DILI.

MST1/2 DKO abates salvianolic acid B's therapeutic effect on CCl4-induced liver injury mice

MST1 and MST2 (MST1/2) are core kinases of the Hippo/YAP signaling pathway in mammals and play key roles in various liver diseases. Deep molecular profiling has shown that the Hippo/YAP pathway interacts synergistically with TGF-β1/Smad2 signaling. Salvianolic acid B (SAB) is an ingredient extracted from Salvia miltiorrhiza that can be used to treat liver diseases. Previous studies have confirmed that SAB hold commendable efficacy against liver injury by inhibition of inflammatory response and Smad2C/2L phosphorylation. However, scientific evidence involving how mutations in the Hippo/YAP pathway are related to the hepatoprotective function of SAB in MST1/2 double knockout (MST1/2 DKO) mice remains vague. Nowadays, the MST1-/- MST2fl/fl Alb-Cre mice were generated to establish a CCl4-induced liver injury model to investigate the potential effects of MST1/2 gene knockout on inflammatory reactions and pSmad2C/pSmad2L signal transduction with the intervention of SAB. As it turns out, genotype identification and western blot assays confirmed that we have successfully obtained MST1-/- MST2fl/fl Alb-Cre mice. General observation, HE staining, and biochemical assays promulgated that genetic deletion of MST1/2 could diminish SAB's hepatoprotective effect on liver injury by promoting the phosphorylation of smad2C/2L and boosting the expression of the inflammatory factors IL- 6 and TNF-α. In summary, these results suggest that MST1/2 play a key role in mediating SAB's effects on liver injury.

C-reactive protein attenuates CCl4-induced acute liver injury by regulating complement system activation

Acute liver injury is liver dysfunction caused by multiple factors without any pre-existing liver disease. C-reactive protein (CRP) is an acute-phase protein produced by hepatocytes, serving as a marker of inflammation and tissue damage. However, its role in CCl4-induced acute liver injury has not been elucidated. Here, we report that CRP protects against CCl4-induced acute liver injury by regulating complement activation. CRP knockout exacerbates CCl4-induced acute liver injury in mice and rats, markedly enhances tissue damage, and reduces survival. Administration of exogenous CRP to CRP-knockout mice rescues the CCl4-induced liver injury phenotype. The protective effect of CRP is independent of its cellular receptor FcγR2b and early metabolic pathways. Instead, CRP suppresses the late-phase amplification of inflammation by inhibiting terminal complement pathway overactivation in injured hepatocytes via factor H recruitment. In complement C3 knockout (C3-/-) mice, the protective effect of CRP against CCl4-induced acute liver injury is lost. These results suggest that CRP can alleviate CCl4-induced acute liver injury by regulating the complement pathway, providing a theoretical basis for CRP's potential involvement and regulation of disease severity.

Functional mechanisms and potential therapeutic strategies for lactylation in liver diseases

Lactylation, a novel form of lactate-mediated protein post-translational modification (PTM), has been identified as a crucial regulator of gene expression and protein function through the modification of both histone and non-histone proteins. Liver disease is frequently characterized by a reprogramming of glucose metabolism and subsequent lactate accumulation. Recent research has implicated lactylation in a diverse array of hepatic pathologies, including liver injury, non-alcoholic fatty liver disease, liver fibrosis, and hepatocellular carcinoma. Consequently, lactylation has emerged as a pivotal regulatory mechanism in liver disease pathogenesis. This review aims to elucidate the intricate regulatory and functional mechanisms underlying lactylation, synthesize recent advancements in its role in various liver diseases, and highlight its potential as a therapeutic target for future interventions in hepatic disorders.

Molecular mechanisms in liver repair and regeneration: from physiology to therapeutics

Liver repair and regeneration are crucial physiological responses to hepatic injury and are orchestrated through intricate cellular and molecular networks. This review systematically delineates advancements in the field, emphasizing the essential roles played by diverse liver cell types. Their coordinated actions, supported by complex crosstalk within the liver microenvironment, are pivotal to enhancing regenerative outcomes. Recent molecular investigations have elucidated key signaling pathways involved in liver injury and regeneration. Viewed through the lens of metabolic reprogramming, these pathways highlight how shifts in glucose, lipid, and amino acid metabolism support the cellular functions essential for liver repair and regeneration. An analysis of regenerative variability across pathological states reveals how disease conditions influence these dynamics, guiding the development of novel therapeutic strategies and advanced techniques to enhance liver repair and regeneration. Bridging laboratory findings with practical applications, recent clinical trials highlight the potential of optimizing liver regeneration strategies. These trials offer valuable insights into the effectiveness of novel therapies and underscore significant progress in translational research. In conclusion, this review intricately links molecular insights to therapeutic frontiers, systematically charting the trajectory from fundamental physiological mechanisms to innovative clinical applications in liver repair and regeneration.

Deciphering the cell type-specific and zonal distribution of drug-metabolizing enzymes, transporters, and transcription factors in livers of mice using single-cell transcriptomics

The liver contains multiple cell types, including resident cell types and immune cells. The liver is also categorized into 3 zones: periportal (zone 1), midzonal (zone 2), and centrilobular (zone 3). The goal of this study was to characterize the distribution of drug-processing genes (DPGs) in mouse liver using published single-cell and nuclei transcriptomic datasets, which were subjected to zonal deconvolution. Filtering, normalization, clustering, and differential expression analyses were performed using Seurat V5 in R. Hepatocytes were assigned to 3 zones based on known zonal markers and validated with published spatial transcriptomics data. Among the 195 DPGs profiled, most were expressed highest in hepatocytes (61.3%). Interestingly, certain DPGs were expressed most highly in nonparenchymal cells, such as in cholangiocytes (11.2%, eg, carboxylesterase [Ces] 2e, Ces2g), endothelial cells (7.2%, eg, aldo-keto reductase [Akr] 1c19, Akr1e1), Kupffer cells (5.3%, eg, Akr1a1, Akr1b10), stellate cells (5.1%, eg, retinoic acid receptor [Rar] α, Rarβ), myofibroblasts (2.9%, RAR-related orphan receptor [Rar] α), and a few were expressed in immune cell types. In hepatocytes, 72.4% of phase-I enzymes were enriched in zone 3. Phase-II conjugation enzymes such as UDP-glucuronosyltransferases (75%) were enriched in zone 3, whereas sulfotransferases (40%) were enriched in zone 1. Hepatic xenobiotic transporters were enriched in zone 3. The xenobiotic biotransformation-regulating transcription factors were enriched in zone 3 hepatocytes. The enrichment of DPGs in liver cell types, including non-parenchymal cells and zone 1 hepatocytes, may serve as an additional repertoire for xenobiotic biotransformation. SIGNIFICANCE STATEMENT: Our study is among the first to systematically characterize the baseline mRNA enrichment of important drug-processing genes in different cell types and zones in the liver. This finding will aid in further understanding the mechanisms of chemical-induced liver injury with improved resolution and precision.

Wnt Pathway-Targeted Therapy in Gastrointestinal Cancers: Integrating Benchside Insights with Bedside Applications

The Wnt signaling pathway is critical in the onset and progression of gastrointestinal (GI) cancers. Anomalies in this pathway, often stemming from mutations in critical components such as adenomatous polyposis coli (APC) or β-catenin, lead to uncontrolled cell proliferation and survival. In the case of colorectal cancer, dysregulation of the Wnt pathway drives tumor initiation and growth. Similarly, aberrant Wnt signaling contributes to tumor development, metastasis, and resistance to therapy in other GI cancers, such as gastric, pancreatic, and hepatocellular carcinomas. Targeting the Wnt pathway or its downstream effectors has emerged as a promising therapeutic strategy for combating these highly aggressive GI malignancies. Here, we review the dysregulation of the Wnt signaling pathway in the pathogenesis of GI cancers and further explore the therapeutic potential of targeting the various components of the Wnt pathway. Furthermore, we summarize and integrate the preclinical evidence supporting the therapeutic efficacy of potent Wnt pathway inhibitors with completed and ongoing clinical trials in GI cancers. Additionally, we discuss the challenges of Wnt pathway-targeted therapies in GI cancers to overcome these concerns for effective clinical translation.

Wnt/β-Catenin Signaling in Liver Pathobiology

The liver has a critical role in regulating host metabolism, immunity, detoxification, and homeostasis. Proper liver function is essential for host health, and dysregulation of hepatic signaling pathways can lead to the onset of disease. The Wnt/β-catenin signaling pathway is an important regulator of liver homeostasis and function. Throughout life, hepatic Wnt/β-catenin signaling contributes to liver development and growth, metabolic zonation, and regeneration. Extensive research has demonstrated that aberrant Wnt/β-catenin signaling drives liver pathologies, including cancers, steatohepatitis, and cholestasis. In this review, we discuss the Wnt/β-catenin pathway as it pertains to liver function and how disruptions in this pathway contribute to the onset and progression of liver diseases. Further, we discuss ongoing research that targets the Wnt/β-catenin pathway for the treatment of liver pathologies.

Cell-Cycle-Related and Expression Elevated Protein in Tumor Upregulates the Antioxidant Genes via Activation of NF-κB/Nrf2 in Acute Liver Injury

BACKGROUND AND AIMS

Cell-cycle-related and expression elevated protein in tumor (CREPT, also named RPRD1B) is highly expressed in tumors and functions to promote tumorigenesis. However, the role of CREPT in the pathophysiology of acute liver injury is limited. Here, we demonstrate that CREPT plays an essential role during acute liver injury.

APPROACH AND RESULTS

Hepatocyte-specific CREPT knockout (CREPThep-/-) and CREPTflox/flox mice were generated and subjected to the CCl4 challenge for the acute (24 h) liver injury. The acute CCl4 challenge triggered increased inflammation as well as liver injury, associated with stronger apoptotic and necroptotic cell death in CREPThep-/- mice. CREPT knockout down-regulated the expression of different genes involved in cell survival, inflammation and fibrosis under acute CCl4 challenge conditions. Antioxidant enzymes such as superoxide dismutase 2 (Sod2) and ferritin heavy chain 1 (Fth1) are dramatically induced at 24 h post-CCl4 treatment, but this induction is blocked by transcriptional inactivation of NF-κB/Nrf2, indicating that CREPT might promote hepatocyte survival in acute liver injury by participating in the transactivation of antioxidant genes.

CONCLUSIONS

These results elucidate the role of CREPT in acute liver injury and provide hints for future research on how CREPT might function in hepatocyte renewal.

β-Catenin disruption decreases macrophage exosomal α-SNAP and impedes Treg differentiation in acute liver injury

Hepatic macrophages and regulatory T cells (Tregs) play an important role in the maintenance of liver immune homeostasis, but the mechanism by which hepatic macrophages regulate Tregs in acute liver injury remains largely unknown. Here, we found that the hepatic Treg proportion and β-catenin expression in hepatic macrophages were associated with acetaminophen- and d-galactosamine/LPS-induced acute liver injury. Interestingly, β-catenin was markedly upregulated only in infiltrating macrophages but not in resident Kupffer cells. Myeloid-specific β-catenin-knockout mice showed an increased inflammatory cell infiltration and hepatocyte apoptosis. Moreover, myeloid β-catenin deficiency decreased the hepatic Treg proportion in the injured liver. Mechanistically, in vitro coculture experiments revealed that macrophage β-catenin modulated its exosome composition and influenced Treg differentiation. Using mass spectrometry-based proteomics, we identified that macrophage β-catenin activation increased the level of exosomal alpha soluble NSF attachment protein (α-SNAP), which in turn promoted Treg differentiation. Overall, our findings demonstrated a molecular mechanism that macrophage β-catenin regulated the Treg proportion in the liver by enhancing the expression of exosomal α-SNAP, providing insights into the pathophysiology of acute liver injury.

Hepatotoxicity of N-nitrosodin-propylamine in larval zebrafish by upregulating the Wnt pathway

N-nitrosodin-propylamine is an organic compound mainly used in organic synthesis. As a typical pollutant, the accidental release of N-nitrosodin-propylamine may cause environmental pollution, especially water environment pollution. In the present study, we used the zebrafish model for the first time to evaluate the developmental toxicity of this drug in the liver. Zebrafish larvae fertilized at 72hpf showed a range of toxic responses after 72hpf exposure to the drug. These include increased mortality, delayed absorption of yolk sac nutrients, shorter body length, abnormal liver morphology, gene disruption, and altered expression of various indicators with increasing dose. Studies on the mechanism of toxicity showed that N-nitrosodin-propylamine exposure increased the level of oxidative stress, increased the level of apoptosis in hepatocytes, and up-regulated the transcriptional expression level of Wnt signaling pathway genes. Astaxanthin and IWR-1 can effectively save the liver toxicity in zebrafish caused by N-nitrosodin-propylamine. Our study showed that the drug exposure induced hepatotoxicity in zebrafish larvae through the up-regulation of Wnt signaling pathway, oxidative stress and apoptosis.

Analysis of the liver-gut axis including metabolomics and intestinal flora to determine the protective effects of kiwifruit seed oil on CCl4-induced acute liver injury

The hepatoprotective effects of kiwifruit seed oil (KSO) were evaluated on acute liver injury (ALI) induced by carbon tetrachloride (CCl4) in vivo. Network pharmacology was used to predict active compounds and targets. Metabolomics and gut microbiota analyses were used to discover the activity mechanism of KSO. KSO improved the liver histological structure, significantly reduced serum proinflammatory cytokine levels, and increased liver antioxidant capacity. The metabolomics analysis showed that KSO may have hepatoprotective effects by controlling metabolites through its participation in signaling pathways like tryptophan metabolism, glycolysis/gluconeogenesis, galactose metabolism, and bile secretion. The gut microbiota analysis demonstrated that KSO improved the composition and quantity of the gut flora. Network pharmacological investigations demonstrated that KSO operated by altering Ptgs2, Nos2, Ppara, Pparg and Serpine1 mRNA levels. All evidence shows that KSO has a hepatoprotective effect, and the mechanism is connected to the regulation of metabolic disorders and intestinal flora.

Pituitary-derived small extracellular vesicles promote liver repair by its cargo miR-143-3p

The small Extracellular vesicles (sEV) has been recognized to be significant for intercellular communication due to their ability to transfer important cellular cargoes like miRNAs through circulation. The pituitary gland has not been clearly known about the role of its secreted sEV under normal physiological conditions. And Liver disease is a global public health burden. The present study is the first to investigate the effect of pituitary sEV on the liver. Sequencing and qRT-PCR revealed miR-143-3p is one of the richest in the pituitary sEV. MiR-143 Knockout (KO) mice resulted in a remarkable decrease in insulin-like growth factor 1 (IGF-1) levels and a significant increase in insulin-like growth factor binding protein 5 (IGFBP5) levels along with a reduction in liver primary cell growth. More importantly, compared with miR-143-KO-sEV, WT-sEV possesses a more robust capacity to improve miR-143 KO mice liver repair through the Wnt/β-catenin pathway after an acute injury caused by carbon tetrachloride (CCl4). Our results indicate that pituitary-derived sEV promotes hepatocyte proliferation and liver repair by its cargo miR-143-3p and provides new insight into the regulation mechanism of the pituitary-liver axis, and open a new window for endocrine regulation by using sEV.

Research on the mechanism of sea buckthorn leaf Fu tea in the treatment of hyperlipidemia

Background

Hyperlipidemia (HLP) presents a significant challenge to global public health. Mounting evidence suggests that statins, the recommended first-line lipid-lowering agents, have significant adverse effects. Consequently, the quest for natural and efficacious alternative therapies is steadily emerging as a research priority for HLP prevention and treatment. Consumption of tea, which is rich in diverse biologically active compounds with the capacity to regulate lipid metabolism and combat obesity, has emerged as a promising alternative therapy. Sea buckthorn leaves are rich in a multitude of biologically active substances, have a hypolipidemic effect, and can be used as a raw material for tea because of their unique flavor. There is a suggestion that combining Aspergillus cristatus with tea could modify or boost the lipid-lowering active compounds present in tea, thereby increasing its efficacy in regulating lipid metabolism.

Results

Sea Buckthorn Leaf Fu Tea (SBLFT) was obtained by fermentation when sea buckthorn leaves contained 42 % moisture, inoculated with Aspergillus cristatus 0.2 mL/g, and incubated for 8 d at constant temperature. Animal experiments demonstrated that SBLFT significantly inhibited body weight gain in HLP rats and reduced lipid content and serum oxidative stress. In addition, liver tissue sections and functional indices showed that SBLFT can improve liver morphology and function abnormalities. Reverse transcription-polymerase chain reaction results indicated that the expression of Liver kinase B1 (LKB1), adenosine 5'-monophosphate (AMP)-activated protein kinase (AMPK), acetyl CoA carboxylase 1 (ACC1), and sterol-regulatory element binding protein-1 (SREBP1c) gene related to lipid metabolism was altered.

Conclusion

SBLFT improved HLP, specifically via promoting the expression of LKB1 in the liver of HLP rats, activating AMPK, and inhibiting ACC1 and SREBP1c expression, resulting in the inhibition of fatty acid and triglyceride synthesis-related enzymes at the transcriptional level.

TRIM26 deficiency enhancing liver regeneration through macrophage polarization and β-catenin pathway activation

Liver regeneration is a complex process involving the crosstalk between parenchymal and non-parenchymal cells, especially macrophages. However, the underlying mechanisms remain incompletely understood. Here, we identify the E3 ubiquitin ligase TRIM26 as a crucial regulator of liver regeneration. Following partial hepatectomy or acute liver injury induced by carbon tetrachloride, Trim26 knockout mice exhibit enhanced hepatocyte proliferation compared to wild-type controls, while adeno-associated virus (AAV)-mediated overexpression of Trim26 reverses the promotional effects. Mechanistically, Trim26 deficiency promotes the recruitment of macrophages to the liver and their polarization towards pro-inflammatory M1 phenotype. These M1 macrophages secrete Wnts, including Wnt2, which subsequently stimulate hepatocyte proliferation through the activation of Wnt/β-catenin signaling. In hepatocytes, Trim26 knockdown reduces the ubiquitination and degradation of β-catenin, thereby further enhancing Wnt/β-catenin signaling. Pharmacological inhibition of Wnt/β-catenin pathway by ICG-001 or depletion of macrophages by clodronate liposomes diminishes the pro-regenerative effects of Trim26 deficiency. Moreover, bone marrow transplantation experiments provide evidence that Trim26 knockout in myeloid cells alone can also promote liver regeneration, highlighting the critical role of macrophage Trim26 in this process. Taken together, our study uncovers TRIM26 as a negative regulator of liver regeneration by modulating macrophage polarization and Wnt/β-catenin signaling in hepatocytes, providing a potential therapeutic target for promoting liver regeneration in clinical settings.

Multimodal decoding of human liver regeneration

The liver has a unique ability to regenerate1,2; however, in the setting of acute liver failure (ALF), this regenerative capacity is often overwhelmed, leaving emergency liver transplantation as the only curative option3-5. Here, to advance understanding of human liver regeneration, we use paired single-nucleus RNA sequencing combined with spatial profiling of healthy and ALF explant human livers to generate a single-cell, pan-lineage atlas of human liver regeneration. We uncover a novel ANXA2+ migratory hepatocyte subpopulation, which emerges during human liver regeneration, and a corollary subpopulation in a mouse model of acetaminophen (APAP)-induced liver regeneration. Interrogation of necrotic wound closure and hepatocyte proliferation across multiple timepoints following APAP-induced liver injury in mice demonstrates that wound closure precedes hepatocyte proliferation. Four-dimensional intravital imaging of APAP-induced mouse liver injury identifies motile hepatocytes at the edge of the necrotic area, enabling collective migration of the hepatocyte sheet to effect wound closure. Depletion of hepatocyte ANXA2 reduces hepatocyte growth factor-induced human and mouse hepatocyte migration in vitro, and abrogates necrotic wound closure following APAP-induced mouse liver injury. Together, our work dissects unanticipated aspects of liver regeneration, demonstrating an uncoupling of wound closure and hepatocyte proliferation and uncovering a novel migratory hepatocyte subpopulation that mediates wound closure following liver injury. Therapies designed to promote rapid reconstitution of normal hepatic microarchitecture and reparation of the gut-liver barrier may advance new areas of therapeutic discovery in regenerative medicine.

Testosterone Exacerbates the Formation of Liver Cancer Induced by Environmental N-Nitrosamines Exposure: Potential Mechanisms and Implications for Human Health

Background

Humans are frequently exposed to N-nitrosamines through various sources, including diet, cigarette smoking, contaminated water, the atmosphere, and endogenous nitrosation. Exposure to these carcinogens may also contribute to the gender-specific incidence of liver cancer, which is significantly higher in males than in females, possibly due to the influence of endogenous hormones such as testosterone. However, the effect of testosterone on N-nitrosamine-induced liver cancer and its underlying mechanism remains unclear.

Purpose

To investigate the effect of testosterone on the development of liver cancer induced by N-nitrosamines exposure.

Patients and Methods

Histopathological and immunohistochemical staining techniques were employed to analyze the expression levels and nuclear localizations of key signaling molecules, including androgen receptor (AR), β-catenin, and HMGB1, in both tumor and non-tumor regions of liver samples obtained from human patients and mice.

Results

The findings demonstrated a strong correlation between AR and β-catenin in the nuclear region of tumor areas. AR also showed a significant correlation with HMGB1 in the cytoplasmic region of non-tumor areas in both human and mice samples. The study further analyzed the expression levels and patterns of these three proteins during the progression of liver tumors.

Conclusion

This study confirms that AR has the ability to modulate the expression levels and patterns of β-catenin and HMGB1 in vivo, thereby exacerbating the progression of liver cancer induced by environmental N-nitrosamines exposure. Importantly, the effect of testosterone on the formation of liver cancer induced by environmental N-nitrosamine exposure intensifies this progression. These findings have important implications for drug safety in clinical practice and emphasize the significance of reducing N-nitrosamines exposure through conscious choices regarding diet and lifestyle to ensure environmental safety.

Systematic screening of hepatoprotective components from traditional Chinese medicine: Zuojin Pill as an example

ETHNOPHARMACOLOGICAL RELEVANCE

Zuojin Pill (ZJP), composed of Coptis chinensis Franch. and Euodia ruticarpa (A. Juss.) Benth. in a mass ratio of 6:1, is a famous traditional Chinese medicine (TCM) formula recorded in "Danxi's Experiential Therapy", an ancient medical book from the Ming Dynasty of China. It is used to treat liver fire invading the stomach, which is caused by liver stagnation transforming into fire and disharmony between the liver and stomach.

AIM OF THE STUDY

To develop a systematic strategy to screen hepatoprotective components from TCM using ZJP as a model sample.

MATERIALS AND METHODS

A CCl4-induced mouse model of acute liver injury was used for the verification of the hepatoprotective effects of ZJP. UPLC-Q-Exactive Plus Orbitrap MS/MS was used for the identification of the components in mouse serum after intragastric administration of ZJP. The hepatoprotective activities of the components found in mouse serum were tested in primary cultured mouse hepatocytes induced by CCl4.

RESULTS

Nine components with significant hepatoprotective activity including berberine, epiberberine, coptisine, palmatine, jatrorrhizine, rutaecarpin, dehydroevodiamine, evocarpine and chlorogenic acid were successfully screened out.

CONCLUSIONS

Our developed strategy has the advantages of high efficiency and low cost, and would provide a powerful tool for screening potential hepatoprotective components from TCM.

Region-specific cellular and molecular basis of liver regeneration after acute pericentral injury

Liver injuries often occur in a zonated manner. However, detailed regenerative responses to such zonal injuries at cellular and molecular levels remain largely elusive. By using a fate-mapping strain, Cyp2e1-DreER, to elucidate liver regeneration after acute pericentral injury, we found that pericentral regeneration is primarily compensated by the expansion of remaining pericentral hepatocytes, and secondarily by expansion of periportal hepatocytes. Employing single-cell RNA sequencing, spatial transcriptomics, immunostaining, and in vivo functional assays, we demonstrated that the upregulated expression of the mTOR/4E-BP1 axis and lactate dehydrogenase A in hepatocytes contributes to pericentral regeneration, while activation of transforming growth factor β (TGF-β1) signaling in the damaged area mediates fibrotic responses and inhibits hepatocyte proliferation. Inhibiting the pericentral accumulation of monocytes and monocyte-derived macrophages through an Arg-Gly-Asp (RGD) peptide-based strategy attenuates these cell-derived TGF-β1 signalings, thus improving pericentral regeneration. Our study provides integrated and high-resolution spatiotemporal insights into the cellular and molecular basis of pericentral regeneration.

Hepatocellular carcinoma: signaling pathways, targeted therapy, and immunotherapy

Hepatocellular carcinoma (HCC) is the most common primary liver cancer with a high mortality rate. It is regarded as a significant public health issue because of its complicated pathophysiology, high metastasis, and recurrence rates. There are no obvious symptoms in the early stage of HCC, which often leads to delays in diagnosis. Traditional treatment methods such as surgical resection, radiotherapy, chemotherapy, and interventional therapies have limited therapeutic effects for HCC patients with recurrence or metastasis. With the development of molecular biology and immunology, molecular signaling pathways and immune checkpoint were identified as the main mechanism of HCC progression. Targeting these molecules has become a new direction for the treatment of HCC. At present, the combination of targeted drugs and immune checkpoint inhibitors is the first choice for advanced HCC patients. In this review, we mainly focus on the cutting-edge research of signaling pathways and corresponding targeted therapy and immunotherapy in HCC. It is of great significance to comprehensively understand the pathogenesis of HCC, search for potential therapeutic targets, and optimize the treatment strategies of HCC.

Targeted Therapy of Acute Liver Injury via Cryptotanshinone-Loaded Biomimetic Nanoparticles Derived from Mesenchymal Stromal Cells Driven by Homing

Acute liver injury (ALI) has the potential to compromise hepatic function rapidly, with severe cases posing a considerable threat to human health and wellbeing. Conventional treatments, such as the oral administration of antioxidants, can inadvertently lead to liver toxicity and other unwanted side effects. Mesenchymal stromal cells (MSCs) can target therapeutic agents directly to inflammatory sites owing to their homing effect, and they offer a promising avenue for the treatment of ALI. However, the efficacy and feasibility of these live cell products are hampered by challenges associated with delivery pathways and safety concerns. Therefore, in this work, MSC membranes were ingeniously harnessed as protective shells to encapsulate synthesized PLGA nanoparticle cores (PLGA/MSCs). This strategic approach enabled nanoparticles to simulate endogenous substances and yielded a core-shell nano-biomimetic structure. The biomimetic nanocarrier remarkably maintained the homing ability of MSCs to inflammatory sites. In this study, cryptotanshinone (CPT)-loaded PLGA/MSCs (CPT@PLGA/MSC) were prepared. These nanoparticles can be effectively internalized by LO2 cells. They reduced cellular oxidative stress and elevated inflammatory levels. In vivo results suggested that, after intravenous administration, CPT@PLGA/MSCs significantly reduced uptake by the reticuloendothelial system and immune recognition compared to PLGA nanoparticles without MSC membrane coatings, subsequently resulting in their targeted and enhanced accumulation in the liver. The effectiveness of CPT@PLGA/MSCs in alleviating carbon tetrachloride-induced oxidative stress and inflammation in a mouse model was unequivocally demonstrated through comprehensive histological examination and liver function tests. This study introduces a pioneering strategy with substantial potential for ALI treatment.

Wnt-β-catenin in hepatobiliary homeostasis, injury, and repair

Wnt-β-catenin signaling has emerged as an important regulatory pathway in the liver, playing key roles in zonation and mediating contextual hepatobiliary repair after injuries. In this review, we will address the major advances in understanding the role of Wnt signaling in hepatic zonation, regeneration, and cholestasis-induced injury. We will also touch on some important unanswered questions and discuss the relevance of modulating the pathway to provide therapies for complex liver pathologies that remain a continued unmet clinical need.

"Small Hepatocytes" in the Liver

Mature hepatocytes (MHs) in an adult rodent liver are categorized into the following three subpopulations based on their proliferative capability: type I cells (MH-I), which are committed progenitor cells that possess a high growth capability and basal hepatocytic functions; type II cells (MH-II), which possess a limited proliferative capability; and type III cells (MH-III), which lose the ability to divide (replicative senescence) and reach the final differentiated state. These subpopulations may explain the liver's development and growth after birth. Generally, small-sized hepatocytes emerge in mammal livers. The cells are characterized by being morphologically identical to hepatocytes except for their size, which is substantially smaller than that of ordinary MHs. We initially discovered small hepatocytes (SHs) in the primary culture of rat hepatocytes. We believe that SHs are derived from MH-I and play a role as hepatocytic progenitors to supply MHs. The population of MH-I (SHs) is distributed in the whole lobules, a part of which possesses a self-renewal capability, and decreases with age. Conversely, injured livers of experimental models and clinical cases showed the emergence of SHs. Studies demonstrate the involvement of SHs in liver regeneration. SHs that appeared in the injured livers are not a pure population but a mixture of two distinct origins, MH-derived and hepatic-stem-cell-derived cells. The predominant cell-derived SHs depend on the proliferative capability of the remaining MHs after the injury. This review will focus on the SHs that appeared in the liver and discuss the significance of SHs in liver regeneration.

Apatinib induces zebrafish hepatotoxicity by inhibiting Wnt signaling and accumulation of oxidative stress

Apatinib, a small-molecule VEGFR2-tyrosine kinase inhibitor, has shown potent anticancer activity in various clinical cancer treatments, but also different adverse reactions. Therefore, it is necessary to study its potential toxicity and working mechanism. We used zebrafish to investigate the effects of apatinib on the development of embryos. Zebrafish exposed to 2.5, 5, and 10 μM apatinib showed adverse effects such as decreased liver area, pericardial oedema, slow yolk absorption, bladder atrophy, and body length shortening. At the same time, it leads to abnormal liver tissue structure, liver function and related gene expression. Furthermore, after exposure to apatinib, oxidative stress levels were significantly elevated but liver developmental toxicity was effectively ameliorated with oxidative stress inhibitor treatment. Apatinib induces down-regulation of key target genes of Wnt signaling pathway in zebrafish, and it is found that Wnt activator can significantly rescue liver developmental defects. These results suggest that apatinib may induce zebrafish hepatotoxicity by inhibiting the Wnt signaling pathway and up-regulating oxidative stress, helping to strengthen our understanding of rational clinical application of apatinib.

Hepatotoxicity evaluation and possible mechanisms of decabrominated diphenyl ethers (BDE-209) in broilers: Oxidative stress, inflammatory, and transcriptomics

Decabrominated diphenyl ether (BDE-209), a persistent organic pollutant, is linked to a great number of health problems, the most severe of which impact the liver due to its role in the elimination and degradation of exogenous harmful substances. Though the hepatotoxicity of BDE-209 has been observed, its underlying mechanism is yet unknown. The purpose of this study is to thoroughly investigate the hepatotoxicity of BDE-209 and its molecular processes in broilers by subjecting 120 male broilers to varied concentrations of BDE-209 for 42 days. We observed that the bioaccumulation of BDE-209 in the liver in a dose-dependent manner, and that BDE-209 exposure can raise the concentrations of ALT, AST, and GGT, accompanied by hepatocyte fatty degeneration and inflammatory foci. In the hepatic homogenates, oxidative stress was evidenced by elevated levels of MDA and ROS and decreased activies of SOD and CAT. Additionally, pro-inflammatory cytokines including IL-1, IL-1β, TNF-α, IL-8 levels were increased, whereas anti-inflammatory cytokine IL-4 level was declined. Furthermore, RNA sequencing revealed that genes involved in inflammation were considerably dysregulated, and real-time PCR verified the expressed alterations of numerous genes related to the MAPK and WNT signaling pathways. The protein concentrations of NF-κB, β-catenin, and WNT5A, and the phosphorylation levels of JNK and ERK were all dramatically enhanced. The current study indicates that BDE-209 exposure can cause hepatotoxicity in broilers via bioaccumulation and oxidative stress, which then activates the MAPK and WNT signaling pathways, subsequently generating inflammation and hepatic injury.

Serum metabolome profiling, network pharmacology analysis, and experimental validation of Anoectochilus roxburghii in the treatment of carbon tetrachloride-induced liver injury

Anoectochilus roxburghii (Wall.) Lindl. (AR) has been traditionally used to treat inflammatory diseases, but the specific mechanism underlying its hepatoprotective effect remains unclear. Here, serum metabolomics and network pharmacology were employed to investigate the hepatoprotective mechanism of AR. Thirty male Sprague-Dawley rats were divided into six groups: normal, model, positive, high-dose AR, middle-dose AR, and low-dose AR. The positive group received therapeutic doses of silibinin, whereas the AR-treated groups received different doses of AR extract once daily. After 10 days of intragastric administration, the rats were intraperitoneally injected with a 50% CCl4 olive oil solution (2 mL/kg) to induce liver injury. Serum and liver samples were obtained, and GC-MS was utilized to monitor changes in serum metabolome. The levels of alkaline phosphatase, aspartate aminotransferase, alanine aminotransferase, and hydrooxproline in serum significantly increased in the model group. On the contrary, AR-treated group showed a significant decrease in the levels of alkaline phosphatase, aspartate aminotransferase, alanine aminotransferase, and hydrooxproline. Histopathological observation also revealed that the extent of liver injury was alleviated in the AR-treated group. Fifty differential metabolites were identified, suggesting that AR may prevent liver damage by modulating carbohydrate and amino acid metabolism.

Bavachin induces liver injury and cell apoptosis by targeting Wnt/β-catenin/DRP1 signaling pathway mediated mitochondrial dysfunction

Psraleae Fructus (PF) is a well-known traditional Chinese medicine in China. While numerous liver injury reports caused by PF limits its clinical application. Bavachin, a flavonoid compound isolated from the fruits of Psoralea corylifolia L., has been validated to induce direct apoptosis in hepatocytes and liver tissues in our previous studies. However, the subcellular mechanisms of bavachin induced liver injury is still elusive. Here, utilizing 6-week-old C57BL/6 J mice and human embryonic hepatocytes (L02 cells), we report that bavachin activates dynamic-related protein 1 (DRP1) mediated excess mitochondrial fission and endoplasmic reticulum (ER) stress related apoptosis via Wnt/β-catenin signaling pathway. Notably, DRP1 knockdown or XAV-939 induced Wnt/β-catenin inhibition decreased bavachin-induced ER stress and cell apoptosis in L02 cells. In addition, bavachin impaired mitochondrial structural and function in the mice liver tissues. Mdivi-1, a mitochondrial fission inhibitor targeting DRP1, prevented bavachin-induced mitochondrial and ER structural damage, ER stress, and liver injury. Our results demonstrated that bavachin induced mitochondrial fission plays a crucial role in bavachin induced ER stress related liver injury, via the mechanism that involved activation of Wnt/β-catenin signaling pathway.

Humanized mouse liver reveals endothelial control of essential hepatic metabolic functions

Hepatocytes, the major metabolic hub of the body, execute functions that are human-specific, altered in human disease, and currently thought to be regulated through endocrine and cell-autonomous mechanisms. Here, we show that key metabolic functions of human hepatocytes are controlled by non-parenchymal cells (NPCs) in their microenvironment. We developed mice bearing human hepatic tissue composed of human hepatocytes and NPCs, including human immune, endothelial, and stellate cells. Humanized livers reproduce human liver architecture, perform vital human-specific metabolic/homeostatic processes, and model human pathologies, including fibrosis and non-alcoholic fatty liver disease (NAFLD). Leveraging species mismatch and lipidomics, we demonstrate that human NPCs control metabolic functions of human hepatocytes in a paracrine manner. Mechanistically, we uncover a species-specific interaction whereby WNT2 secreted by sinusoidal endothelial cells controls cholesterol uptake and bile acid conjugation in hepatocytes through receptor FZD5. These results reveal the essential microenvironmental regulation of hepatic metabolism and its human-specific aspects.

Precise and efficient C-to-U RNA base editing with SNAP-CDAR-S

Site-directed RNA base editing enables the transient and dosable change of genetic information and represents a recent strategy to manipulate cellular processes, paving ways to novel therapeutic modalities. While tools to introduce adenosine-to-inosine changes have been explored quite intensively, the engineering of precise and programmable tools for cytidine-to-uridine editing is somewhat lacking behind. Here we demonstrate that the cytidine deaminase domain evolved from the ADAR2 adenosine deaminase, taken from the RESCUE-S tool, provides very efficient and highly programmable editing when changing the RNA targeting mechanism from Cas13-based to SNAP-tag-based. Optimization of the guide RNA chemistry further allowed to dramatically improve editing yields in the difficult-to-edit 5'-CCN sequence context thus improving the substrate scope of the tool. Regarding editing efficiency, SNAP-CDAR-S outcompeted the RESCUE-S tool clearly on all tested targets, and was highly superior in perturbing the β-catenin pathway. NGS analysis showed similar, moderate global off-target A-to-I and C-to-U editing for both tools.

Distinct hepatocyte identities in liver homeostasis and regeneration

The process of metabolic liver zonation is spontaneously established by assigning distributed tasks to hepatocytes along the porto-central blood flow. Hepatocytes fulfil critical metabolic functions, while also maintaining hepatocyte mass by replication when needed. Recent technological advances have enabled us to fine-tune our understanding of hepatocyte identity during homeostasis and regeneration. Subsets of hepatocytes have been identified to be more regenerative and some have even been proposed to function like stem cells, challenging the long-standing view that all hepatocytes are similarly capable of regeneration. The latest data show that hepatocyte renewal during homeostasis and regeneration after liver injury is not limited to rare hepatocytes; however, hepatocytes are not exactly the same. Herein, we review the known differences that give individual hepatocytes distinct identities, recent findings demonstrating how these distinct identities correspond to differences in hepatocyte regenerative capacity, and how the plasticity of hepatocyte identity allows for division of labour among hepatocytes. We further discuss how these distinct hepatocyte identities may play a role during liver disease.

Circular RNA encoded MET variant promotes glioblastoma tumorigenesis

Activated by its single ligand, hepatocyte growth factor (HGF), the receptor tyrosine kinase MET is pivotal in promoting glioblastoma (GBM) stem cell self-renewal, invasiveness and tumorigenicity. Nevertheless, HGF/MET-targeted therapy has shown limited clinical benefits in GBM patients, suggesting hidden mechanisms of MET signalling in GBM. Here, we show that circular MET RNA (circMET) encodes a 404-amino-acid MET variant (MET404) facilitated by the N⁶-methyladenosine (m⁶A) reader YTHDF2. Genetic ablation of circMET inhibits MET404 expression in mice and attenuates MET signalling. Conversely, MET404 knock-in (KI) plus P53 knock-out (KO) in mouse astrocytes initiates GBM tumorigenesis and shortens the overall survival. MET404 directly interacts with the MET β subunit and forms a constitutively activated MET receptor whose activity does not require HGF stimulation. High MET404 expression predicts poor prognosis in GBM patients, indicating its clinical relevance. Targeting MET404 through a neutralizing antibody or genetic ablation reduces GBM tumorigenicity in vitro and in vivo, and combinatorial benefits are obtained with the addition of a traditional MET inhibitor. Overall, we identify a MET variant that promotes GBM tumorigenicity, offering a potential therapeutic strategy for GBM patients, especially those with MET hyperactivation.

Resveratrol attenuated fatty acid synthesis through MAPK-PPAR pathway in red tilapia

High-fat (HF) diets have been shown to cause hepatic impairment in fish species, but the mode of action, especially the pathways involved, has not yet been determined. In this study, the effects of resveratrol (RES) supplementation on the hepatic structure and fat metabolism of red tilapia (Oreochromis niloticus) were determined. Based on transcriptome and proteomics results, RES was found to promote fatty acid β-oxidation in the blood, liver, and liver cells associated with apoptosis and the MAPK/PPAR signaling pathway. RES supplementation was found to alter the expression of genes related to apoptosis and fatty acid pathways like blood itga6a and armc5 which were upregulated and downregulated respectively by high-fat feeding while ggh and ensonig00000008711 increased and decreased, respectively, with RES addition. Relative to the PPAR signaling pathway, fabp10a and acbd7 showed a reverse U-shaped tendency, both in different treatments and at different times. Proteomics results demonstrated that MAPK/PPAR, carbon/glyoxylate, dicarboxylate/glycine serine, and threonine/drug-other enzymes/beta-alanine metabolism pathways in the RES group were significantly affected, and Fasn and Acox1 decreased and increased, respectively, with RES addition. Seven subgroups were obtained using scRNA-seq, and enrichment analysis showed that the PPAR signaling pathway was upregulated with RES supplementation. RES significantly increased the expression of the marked genes (pck1) ensonig00000037711, fbp10a, granulin, hbe1, and zgc:136461, which are liver cell-specific genes. In conclusion, RES resulted in significantly enriched DGEs associated with fat metabolism and synthesis via the MAPK-PPAR signaling pathway.

Hepatocyte β-catenin loss is compensated by Insulin-mTORC1 activation to promote liver regeneration

BACKGROUND AND AIMS

Liver regeneration (LR) following partial hepatectomy (PH) occurs via activation of various signaling pathways. Disruption of a single pathway can be compensated by activation of another pathway to continue LR. The Wnt-β-catenin pathway is activated early during LR and conditional hepatocyte loss of β-catenin delays LR. Here, we study mechanism of LR in the absence of hepatocyte-β-catenin.

APPROACH AND RESULTS

Eight-week-old hepatocyte-specific Ctnnb1 knockout mice (β-catenin ΔHC ) were subjected to PH. These animals exhibited decreased hepatocyte proliferation at 40-120 h and decreased cumulative 14-day BrdU labeling of <40%, but all mice survived, suggesting compensation. Insulin-mediated mechanistic target of rapamycin (mTOR) complex 1 (mTORC1) activation was uniquely identified in the β-catenin ΔHC mice at 72-96 h after PH. Deletion of hepatocyte regulatory-associated protein of mTOR (Raptor), a critical mTORC1 partner, in the β-catenin ΔHC mice led to progressive hepatic injury and mortality by 30 dys. PH on early stage nonmorbid Raptor ΔHC -β-catenin ΔHC mice led to lethality by 12 h. Raptor ΔHC mice showed progressive hepatic injury and spontaneous LR with β-catenin activation but died by 40 days. PH on early stage nonmorbid Raptor ΔHC mice was lethal by 48 h. Temporal inhibition of insulin receptor and mTORC1 in β-catenin ΔHC or controls after PH was achieved by administration of linsitinib at 48 h or rapamycin at 60 h post-PH and completely prevented LR leading to lethality by 12-14 days.

CONCLUSIONS

Insulin-mTORC1 activation compensates for β-catenin loss to enable LR after PH. mTORC1 signaling in hepatocytes itself is critical to both homeostasis and LR and is only partially compensated by β-catenin activation. Dual inhibition of β-catenin and mTOR may have notable untoward hepatotoxic side effects.

Single-Cell Transcriptome Sequencing Reveals Molecular Mechanisms of Renal Injury in Essential Hypertension

INTRODUCTION

Hypertensive nephropathy is characterized by glomerular and tubulointerstitial damage, but we know little about changes in cell-specific gene expression in the early stages of hypertensive kidney injury, which usually has no obvious pathological changes.

METHODS

We performed unbiased single-cell RNA sequencing of rat kidney samples from hypertensive kidney injury to generate 10,602 single-cell transcriptomes from 2 control and 2 early stage hypertensive kidney injury samples.

RESULTS

All major cell types of the kidney were represented in the final dataset. Side-by-side comparisons showed that cell type-specific changes in gene expression are critical for functional impairment of glomeruli and tubules and activation of immune cells. In particular, we found a significantly reduced gene expression profile of maintaining vascular integrity in glomerular cells of hypertensive kidney injury. Meanwhile, the expression of genes associated with oxidative stress injury and fibrosis in the renal tubules and collecting ducts was elevated, but the degree of tubular cells response to injury differed between parts. We also found a signature of immune cell infiltration in hypertensive kidney injury.

CONCLUSION

Exploring the changes of gene expression in hypertension-injured kidneys may be helpful to identify the early biomarkers and signal pathways of this disease. Our data provide rich resources for understanding the pathogenesis of hypertensive renal injury and formulating effective treatment strategies.

The Expression of NHE8 in Liver and Its Role in Carbon Tetrachloride-Induced Liver Injury

BACKGROUND AND AIMS

Sodium-hydrogen exchanger 8 (NHE8) is expressed in array of tissues and has pleiotropic functions beyond simply exchanging sodium and hydrogen across cell membrane. This study investigates the expression pattern of liver NHE8 and its roles in carbon tetrachloride (CCl4)-induced liver injury.

METHODS

NHE8 expression pattern was investigated in mouse livers of different ages and in HepG2 cells. CCl4 was given to mice to determine NHE8 expression in CCl4-induced liver injury. Tumor necrosis factor (TNF)-α and interleukin (IL)-1β were used to treat HepG2 cells to evaluate their effect on NHE8 expression. The CCl4-induced acute and chronic liver injuries were also used in NHE8KO mice to determine the role of NHE8 deficiency in liver injury.

RESULTS

NHE8 was mainly detected in the peripheral area of hepatocytes in mouse liver and in HepG2 cells. The liver NHE8 expression was 47% of NHE1, and liver NHE8 expression was the lowest at suckling age and reached plateau at 4 weeks of age. Similar to dextran sulfate sodium colitis reduced intestinal NHE8, CCl4-induced acute liver injury also inhibited NHE8 expression. The absence of NHE8 in the liver displayed abnormal hepatocyte morphology and has elevated expression of IL-1β and Lgr5. However, unlike NHE8 deficiency enhanced dextran sulfate sodium-induced colon tissue damage, the absence of NHE8 in the liver did not exacerbate CCl4-induced liver injury. Although both TNF-α and IL-1β were elevated in CCl4-induced liver injury, they could not inhibit NHE8 expression in hepatocytes, which is in contrast with TNF-α-mediated NHE8 inhibition in the intestine.

CONCLUSION

Liver NHE8 has unique roles that are different from the intestine.

Antioxidant and Antiapoptotic Properties of n-Butanol Fraction the Acanthopanax senticosus Extracts in H2O2-RAW264.7 Cells and CCl4-Induced Liver Injury in Mice

The Acanthopanax senticosus has been shown to have a wide range of pharmacological activities, which are associated with health benefits, such as antioxidant, anti-inflammatory, and antiapoptotic properties. A previous study has shown that the n-butanol fraction of A. senticosus extract had the strongest antioxidant effect in vitro. This study aimed to investigate the effects that the n-butanol fraction of A. senticosus extract could relieve oxidative stress damage through antioxidant and antiapoptotic in the H₂O₂-stimulated RAW264.7 macrophages and the CCl₄-induced liver injury. The result showed that the n-butanol fraction extract could relieve damage by increasing the intracellular antioxidant enzymes (SOD) level, decreasing intracellular ROS and MDA levels, and regulating antioxidant and antiapoptotic-related gene expression levels. The morphological observation of HE, TUNE, and immunohistochemistry staining of liver tissue verified that the n-butanol fraction extract is though anti-oxidative and antiapoptotic to alleviate cellular oxidative damage. The RT-PCR assay showed that the Keap1-Nrf2-ARE and the Bax/Bcl-2 signaling pathway were related to the molecular mechanism of action. The experimental results show that Acanthopanax senticosus extract has a good effect in treating liver injury and enhancing the antioxidant capacity of the body.

Single-cell spatial transcriptomics reveals a dynamic control of metabolic zonation and liver regeneration by endothelial cell Wnt2 and Wnt9b

The conclusive identity of Wnts regulating liver zonation (LZ) and regeneration (LR) remains unclear despite an undisputed role of β-catenin. Using single-cell analysis, we identified a conserved Wnt2 and Wnt9b expression in endothelial cells (ECs) in zone 3. EC-elimination of Wnt2 and Wnt9b led to both loss of β-catenin targets in zone 3, and re-appearance of zone 1 genes in zone 3, unraveling dynamicity in the LZ process. Impaired LR observed in the knockouts phenocopied models of defective hepatic Wnt signaling. Administration of a tetravalent antibody to activate Wnt signaling rescued LZ and LR in the knockouts and induced zone 3 gene expression and LR in controls. Administration of the agonist also promoted LR in acetaminophen overdose acute liver failure (ALF) fulfilling an unmet clinical need. Overall, we report an unequivocal role of EC-Wnt2 and Wnt9b in LZ and LR and show the role of Wnt activators as regenerative therapy for ALF.

The RSPO-LGR4/5-ZNRF3/RNF43 module in liver homeostasis, regeneration, and disease

WNT/β-catenin signaling plays pivotal roles during liver development, homeostasis, and regeneration. Likewise, its deregulation disturbs metabolic liver zonation and is responsible for the development of a large number of hepatic tumors. Liver fibrosis, which has become a major health burden for society and a hallmark of NASH, can also be promoted by WNT/β-catenin signaling. Upstream regulatory mechanisms controlling hepatic WNT/β-catenin activity may constitute targets for the development of novel therapies addressing these life-threatening conditions. The R-spondin (RSPO)-leucine-rich repeat-containing G protein-coupled receptor (LGR) 4/5-zinc and ring finger (ZNRF) 3/ring finger 43 (RNF43) module is fine-tuning WNT/β-catenin signaling in several tissues and is essential for hepatic WNT/β-catenin activity. In this review article, we recapitulate the role of the RSPO-LGR4/5-ZNRF3/RNF43 module during liver development, homeostasis, metabolic zonation, regeneration, and disease. We further discuss the controversy around LGR5 as a liver stem cell marker.

HLJ1 amplifies endotoxin-induced sepsis severity by promoting IL-12 heterodimerization in macrophages

Heat shock protein (HSP) 40 has emerged as a key factor in both innate and adaptive immunity, whereas the role of HLJ1, a molecular chaperone in HSP40 family, in modulating endotoxin-induced sepsis severity is still unclear. During lipopolysaccharide (LPS)-induced endotoxic shock, HLJ1 knockout mice shows reduced organ injury and IFN-γ (interferon-γ)-dependent mortality. Using single-cell RNA sequencing, we characterize mouse liver nonparenchymal cell populations under LPS stimulation, and show that HLJ1 deletion affected IFN-γ-related gene signatures in distinct immune cell clusters. In CLP models, HLJ1 deletion reduces IFN-γ expression and sepsis mortality rate when mice are treated with antibiotics. HLJ1 deficiency also leads to reduced serum levels of IL-12 in LPS-treated mice, contributing to dampened production of IFN-γ in natural killer cells but not CD4⁺ or CD8⁺ T cells, and subsequently to improved survival rate. Adoptive transfer of HLJ1-deleted macrophages into LPS-treated mice results in reduced IL-12 and IFN-γ levels and protects the mice from IFN-γ-dependent mortality. In the context of molecular mechanisms, HLJ1 is an LPS-inducible protein in macrophages and converts misfolded IL-12p35 homodimers to monomers, which maintains bioactive IL-12p70 heterodimerization and secretion. This study suggests HLJ1 causes IFN-γ-dependent septic lethality by promoting IL-12 heterodimerization, and targeting HLJ1 has therapeutic potential in inflammatory diseases involving activated IL-12/IFN-γ axis.

Nicotine exposure of male mice protects offspring against carbon tetrachloride-induced acute liver injury

Paternal nicotine exposure can cause a phenotypic change in offspring. To study whether paternal nicotine exposure influences acute liver injury and repair of the offspring, we established a paternal nicotine exposure model in mice and treated the offspring mice with carbon tetrachloride (CCl₄ ) to induce acute liver injury. After the treatment of CCl₄ , the levels of alanine aminotransferase and aspartate aminotransferase in offspring serum of paternal nicotine exposed mice are about 37.44%, and 30.21% lower than the control mice, respectively. Transcription profiling screen and bioinformatics analysis of differently expressed genes in F1 mice liver revealed that the Wnt pathway was altered. The results demonstrate that nicotine exposure in male mice could enhance the activation of the Wnt pathway in F1 mice liver. The Wnt pathway facilitates cell proliferation and tissue repair. In conclusion, our findings showed that nicotine exposure of male mice protects hepatic against CCl₄ -induced acute injury in offspring by activating the Wnt pathway in the F1 liver.

Hepatoprotective Effect of the Penthorum Chinense Pursh Extract against the CCl4-Induced Acute Liver Injury via NF-κB and p38-MAPK PATHWAYS in Dogs

Acute liver injury (ALI), manifested by acute hepatocellular damages and necrosis, is a life-threatening clinical syndrome and Penthorum Chinense Pursh (PCP) is a well-known folk medicine practiced for liver-related diseases. This study aimed to investigate the ameliorative effects of PCP extract (PCPE) on carbon tetrachloride (CCl4) induced ALI in dogs via mitogen-activated protein kinase (MAPK) and Nuclear factor κB (NF-κB) signaling pathway. Healthy dogs were induced by CCl4 and treated with different dosage regimes of PCPE for 7 days. CCl4 produced acute liver injury and induced both oxidative stress and an inflammatory response in dogs. The PCPE significantly ameliorated and improved vacuolar inflammatory lesions in liver tissues during ALI, enhanced activity of superoxide dismutase, and restored glutathione peroxidase, further significantly reducing the indices of malondialdehyde and nitric oxide in serum. Inflammatory factors (IL-1β, IL-6, and TNF-α) were declined and anti-inflammatory factors (IL-10) were increased by the application of PCPE. PCPE treatment, down-regulated the MEKK4, MKK3, p38MAPK, MSK1, and NF-κB, and upregulated the IkB mRNA levels (p < 0.01) in ALI affected dogs. In conclusion, PCPE repaired acute liver injury by improving antioxidant enzymes and by reducing oxidation products. Furthermore, the PCPE inhibited the MAPK/NF-κB signaling pathway, which resulted in anti-inflammatory and antioxidant effects on ALI-induced dogs. In the future, PCPE could be a useful ethnomedicine in veterinary clinical practices for the treatment of liver injuries or failures.

Aurora kinase A regulates liver regeneration through macrophages polarization and Wnt/β-catenin signalling

BACKGROUND AND AIMS

Liver regeneration is a complex process regulated by a variety of cells, cytokines and biological pathways. Aurora kinase A (AURKA) is a serine/threonine kinase that plays a role in centrosome maturation and spindle formation during the cell division cycle. The purpose of this study was to further explore the mechanism of AURKA on liver regeneration and to identify new possible targets for liver regeneration.

METHODS

The effect and mechanism of AURKA on liver regeneration were studied using a 70% hepatectomy model. Human liver organoids were used as an in vitro model to investigate the effect of AURKA on hepatocyte proliferation.

RESULTS

AURKA inhibition significantly reduced the level of β-catenin protein by reducing the phosphorylation level of glycogen synthase kinase-3β (GSK-3β), leading to the inhibition of liver regeneration. Further studies showed that AURKA co-localized and interacted with GSK-3β in the cytoplasm of hepatocytes. When phosphorylation of GSK-3β was enhanced, the total GSK-3β level remained unchanged, while AURKA was not affected, and β-catenin protein levels were increased. In addition, AURKA inhibition affected the formation and proliferation of human liver organoids. Furthermore, AURKA inhibition led to the polarization of M1 macrophages and the release of interleukin-6 and Tumour necrosis factor α, which also led to reduced liver regeneration and increased liver injury.

CONCLUSIONS

These results provide more details on the mechanism of liver regeneration and suggest that AURKA is an important regulator of this mechanism.

Wnt/β-catenin signalling: function, biological mechanisms, and therapeutic opportunities

The Wnt/β-catenin pathway comprises a family of proteins that play critical roles in embryonic development and adult tissue homeostasis. The deregulation of Wnt/β-catenin signalling often leads to various serious diseases, including cancer and non-cancer diseases. Although many articles have reviewed Wnt/β-catenin from various aspects, a systematic review encompassing the origin, composition, function, and clinical trials of the Wnt/β-catenin signalling pathway in tumour and diseases is lacking. In this article, we comprehensively review the Wnt/β-catenin pathway from the above five aspects in combination with the latest research. Finally, we propose challenges and opportunities for the development of small-molecular compounds targeting the Wnt signalling pathway in disease treatment.

Hepatocyte organoids and cell transplantation: What the future holds

Historically, primary hepatocytes have been difficult to expand or maintain in vitro. In this review, we will focus on recent advances in establishing hepatocyte organoids and their potential applications in regenerative medicine. First, we provide a background on the renewal of hepatocytes in the homeostatic as well as the injured liver. Next, we describe strategies for establishing primary hepatocyte organoids derived from either adult or fetal liver based on insights from signaling pathways regulating hepatocyte renewal in vivo. The characteristics of these organoids will be described herein. Notably, hepatocyte organoids can adopt either a proliferative or a metabolic state, depending on the culture conditions. Furthermore, the metabolic gene expression profile can be modulated based on the principles that govern liver zonation. Finally, we discuss the suitability of cell replacement therapy to treat different types of liver diseases and the current state of cell transplantation of in vitro-expanded hepatocytes in mouse models. In addition, we provide insights into how the regenerative microenvironment in the injured host liver may facilitate donor hepatocyte repopulation. In summary, transplantation of in vitro-expanded hepatocytes holds great potential for large-scale clinical application to treat liver diseases.

Exosomes as Part of the Human Adipose-Derived Stem Cells Secretome- Opening New Perspectives for Cell-Free Regenerative Applications

Human adipose-derived stem cells (hASCs) represent a great resource for regenerative medicine based on their accessibility, self-renewal potential, low immunogenicity, high proliferative rate and potential to differentiate on multiple lineages. Their secretome is rich in chemokines, cytokines and protein growth factors that are actively involved in regeneration processes. In addition, part of this secretome are also the exosomes (hASC-exos), which display high content in proteins, messenger RNAs (mRNAs) and non-coding RNAs (ncRNAs). Due to their content, exosomes promote tissue regeneration by different mechanisms, either by activating or inhibiting several signaling pathways involved in wound healing, extracellular matrix remodeling, immunomodulation, angiogenesis, anti-apoptotic activity and cell migration, proliferation and differentiation. The use of hASC-exos may provide an improved alternative to standard therapies used in regenerative medicine, as a cell-free new approach with multiple possibilities to be modulated according to the patient needs. This review offers an updated overview on the functions and applications of hASC-exos in all areas of tissue regeneration, aiming to highlight to the reader the benefits of using hASCs in modern tissue engineering and regenerative medicine applications.

Beneficial effects of an endogenous enrichment in n3-PUFAs on Wnt signaling are associated with attenuation of alcohol-mediated liver disease in mice

Alcohol-associated liver disease (ALD) is a major human health issue for which there are limited treatment options. Experimental evidence suggests that nutrition plays an important role in ALD pathogenesis, and specific dietary fatty acids, for example, n6 or n3-PUFAs, may exacerbate or attenuate ALD, respectively. The purpose of the current study was to determine whether the beneficial effects of n3-PUFA enrichment in ALD were mediated, in part, by improvement in Wnt signaling. Wild-type (WT) and fat-1 transgenic mice (that endogenously convert n6-PUFAs to n3) were fed ethanol (EtOH) for 6 weeks followed by a single LPS challenge. fat-1 mice had less severe liver damage than WT littermates as evidenced by reduced plasma alanine aminotransferase, hepatic steatosis, liver tissue neutrophil infiltration, and pro-inflammatory cytokine expression. WT mice had a greater downregulation of Axin2, a key gene in the Wnt pathway, than fat-1 mice in response to EtOH and LPS. Further, there were significant differences between WT and fat-1 EtOH+LPS-challenged mice in the expression of five additional genes linked to the Wnt signaling pathway, including Apc, Fosl1/Fra-1, Mapk8/Jnk-1, Porcn, and Nkd1. Compared to WT, primary hepatocytes isolated from fat-1 mice exhibited more effective Wnt signaling and were more resistant to EtOH-, palmitic acid-, or TNFα-induced cell death. Further, we demonstrated that the n3-PUFA-derived lipid mediators, resolvins D1 and E1, can regulate hepatocyte expression of several Wnt-related genes that were differentially expressed between WT and fat-1 mice. These data demonstrate a novel mechanism by which n3-PUFAs can ameliorate ALD.

Wnt/-Catenin Signaling and Liver Regeneration: Circuit, Biology, and Opportunities

The liver is uniquely bestowed with an ability to regenerate following a surgical or toxicant insult. One of the most researched models to demonstrate the regenerative potential of this organ is the partial hepatectomy model, where two thirds of the liver is surgically resected. The remnant liver replenishes the lost mass within 1014 days in mice. The distinctive ability of the liver to regenerate has allowed living donor and split liver transplantation. One signaling pathway shown to be activated during the process of regeneration to contribute toward the mass and functional recovery of the liver is the Wnt/-catenin pathway. Very early after any insult to the liver, the cellmolecule circuitry of the Wnt/-catenin pathway is set into motion with the release of specific Wnt ligands from sinusoidal endothelial cells and macrophages, which, in a paracrine manner, engage Frizzled and LDL-related protein-5/6 coreceptors on hepatocytes to stabilize -catenin inducing its nuclear translocation. Nuclear -catenin interacts with T-cell factor family of transcription factors to induce target genes including cyclin D1 for proliferation, and others for regulating hepatocyte function. Working in collaboration with other signaling pathways, Wnt/-catenin signaling contributes to the restoration process without any compromise of function at any stage. Also, stimulation of this pathway through innovative means induces liver regeneration when this process is exhausted or compromised and thus has applications in the treatment of end-stage liver disease and in the field of liver transplantation. Thus, Wnt/-catenin signaling pathway is highly relevant in the discipline of hepatic regenerative medicine.

β-Catenin Activation in Hepatocellular Cancer: Implications in Biology and Therapy

Simple Summary

Liver cancer is a dreadful tumor which has gradually increased in incidence all around the world. One major driver of liver cancer is the Wnt–β-catenin pathway which is active in a subset of these tumors. While this pathway is normally important in liver development, regeneration and homeostasis, it’s excessive activation due to mutations, is detrimental and leads to tumor cell growth, making it an important therapeutic target. There are also some unique characteristics of this pathway activation in liver cancer. It makes the tumor addicted to specific amino acids and in turn to mTOR signaling, which can be treated by certain existing therapies. In addition, activation of the Wnt–β-catenin in liver cancer appears to alter the immune cell landscape making it less likely to respond to the new immuno-oncology treatments. Thus, Wnt–β-catenin active tumors may need to be treated differently than non-Wnt–β-catenin active tumors.

Abstract

Hepatocellular cancer (HCC), the most common primary liver tumor, has been gradually growing in incidence globally. The whole-genome and whole-exome sequencing of HCC has led to an improved understanding of the molecular drivers of this tumor type. Activation of the Wnt signaling pathway, mostly due to stabilizing missense mutations in its downstream effector β-catenin (encoded by CTNNB1) or loss-of-function mutations in AXIN1 (the gene which encodes for Axin-1, an essential protein for β-catenin degradation), are seen in a major subset of HCC. Because of the important role of β-catenin in liver pathobiology, its role in HCC has been extensively investigated. In fact, CTNNB1 mutations have been shown to have a trunk role. β-Catenin has been shown to play an important role in regulating tumor cell proliferation and survival and in tumor angiogenesis, due to a host of target genes regulated by the β-catenin transactivation of its transcriptional factor TCF. Proof-of-concept preclinical studies have shown β-catenin to be a highly relevant therapeutic target in CTNNB1-mutated HCCs. More recently, studies have revealed a unique role of β-catenin activation in regulating both tumor metabolism as well as the tumor immune microenvironment. Both these roles have notable implications for the development of novel therapies for HCC. Thus, β-catenin has a pertinent role in driving HCC development and maintenance of this tumor-type, and could be a highly relevant therapeutic target in a subset of HCC cases.