Unraveling the effect of intra- and intercellular processes on acetaminophen-induced liver injury

Hepatoprotective effects of wine-steamed Schisandra sphenanthera fruit in alleviating APAP-induced liver injury via the gut-liver axis

Drug-induced liver injury (DILI) is a common adverse drug reaction that can result in liver injury, particularly in cases of paracetamol (APAP) abuse. Schisandra sphenanthera Rehd. et Wils. has attracted attention due to its hepatoprotective properties, and the underlying mechanism is unclear. In this study, a mouse model of APAP-induced liver injury was employed to evaluate network pharmacology analysis, histopathological analysis, the gut microbiota, and fecal metabolome to investigate the mechanism by which S. sphenanthera fruit extract (SFE) alleviates DILI. Network pharmacology indicated that the SFE can attenuate APAP-induced liver injury via key targets, including MAPK3 and CASP3. Furthermore, SFE effectively alleviated APAP-induced oxidative stress (MDA, SOD, and GSH) and inflammation (IL-6, TNF-α, and IL-1β). Further analysis of gut microbiota and fecal metabolites revealed that SFE promoted the growth of Bacteroidales and Erysipelotrichales, and decreased the growth of Lactobacillales, leading to increased production of tryptophan metabolites. Correlation analysis showed that the increase in gut microbiota by SFE was positively correlated with improved antioxidant ability and improved liver and gut function. In conclusion, SFE pretreatment can alleviate APAP-induced liver injury by targeting the gut-liver axis, and provides a valuable reference for the clinical use of SFE in the prevention or treatment of DILI.

Cohabitation facilitates microbiome shifts that promote isoflavone transformation to ameliorate liver injury

Acetaminophen overuse is a leading cause of acute liver injury (ALI). Although ALI is linked to inter-individual differences in microbiome composition, the mechanisms remain unclear. We demonstrate that horizontal transmission of gut microbiota between male and female mice impacts ALI and identify Rikenellamicrofusus-mediated isoflavone transformation as determinants of ALI severity. R. microfusus increases upon cohabitation with bacterial β-galactosidase enhancing intestinal absorption of isoflavone biochanin-A (Bio-A). R. microfusus mono-colonization reduced ALI severity following acetaminophen overdose. Genetic or chemical-mediated inhibition of β-galactosidase blocked Bio-A release and negated the hepatoprotective effects of R. microfusus. Bio-A directly binds to pyruvate carboxylase (PC) and propionyl-CoA carboxylase subunit alpha (PCCA), augmenting the tricarboxylic acid cycle and promoting protective glutathione synthesis in hepatocytes. Additionally, immunohistochemical analysis revealed reduced hepatic PC and PCCA expression in liver failure (LF) patients. These findings highlight the impacts of microbiome composition on ALI and the ability of microbial isoflavone absorption to mitigate ALI severity.

Computational modelling identifies primary mediators of crosstalk between DNA damage and oxidative stress responses

Cells exposed to toxicants, such as drugs, activate a wide variety of stress pathways, often simultaneously. Two important pathways that can influence cell fate and consequently adverse reactions are the oxidative stress response (OSR) and the DNA damage response (DDR). Previous studies have presented evidence of crosstalk between the OSR and DDR. We aimed to develop computational models to describe experimentally observed dynamics of both OSR and DDR proteins in liver (HepG2) cells in vitro upon exposure to various concentrations of either diethyl maleate (DEM; an agent primarily invoking oxidative stress) or etoposide (an agent primarily causing DNA damage). With these models, we aimed to identify the key interactions that cause crosstalk and their importance in describing protein dynamics. We developed a new model for the OSR pathway, coupled it to a previously developed model for the DDR pathway, and extended the resulting combined model based on multiple potential modes of crosstalk described in the literature. The different models were applied to previously published data of HepG2 GFP-reporter cells with time-dynamic information on the relative amount of proteins important for the OSR (NRF2, SRXN1) or DDR (p53, p21, BTG2 and MDM2). The developed models properly described key OSR and DDR protein dynamics, and in silico knockdowns of key model components in most cases led to a moderate effect on the connected pathway. The largest effect occurred after knockdown of p21, which resulted in a substantial decrease in NRF2 and SRXN1. We expect these models could play a role in adversity predictions by coupling our models with other models that predict cell fate or adversity based on the expression of specific proteins.

A virtual scalable model of the Hepatic Lobule for acetaminophen hepatotoxicity prediction

Addressing drug-induced liver injury is crucial in drug development, often causing Phase III trial failures and market withdrawals. Traditional animal models fail to predict human liver toxicity accurately. Virtual twins of human organs present a promising solution. We introduce the Virtual Hepatic Lobule, a foundational element of the Living Liver, a multi-scale liver virtual twin. This model integrates blood flow dynamics and an acetaminophen-induced injury model to predict hepatocyte injury patterns specific to patients. By incorporating metabolic zonation, our predictions align with clinical zonal hepatotoxicity observations. This methodology advances the development of a human liver virtual twin, aiding in the prediction and validation of drug-induced liver injuries.

Protective effects and mechanism of Sangyu granule on acetaminophen-induced liver injury in mice

ETHNOPHARMACOLOGICAL RELEVANCE

The Sang Yu granule (SY), a traditional Chinese medicine prescription of Xijing Hospital, was developed based on the Guanyin powder in the classical prescription "Hong's Collection of Proven Prescriptions" and the new theory of modern Chinese medicine. It has been proved to have a certain therapeutic effect on drug-induced liver injury (DILI), but the specific mechanism of action is still unclear.

AIM OF STUDY

Aim of the study was to explore the effect of SangYu granule on treating drug-induced liver injury induced by acetaminophen in mice.

MATERIALS AND METHODS

The chemical composition of SY, serum, and liver tissue was analyzed using ultrahigh-performance liquid chromatography quadrupole time-of-flight mass spectrometry. To assess hepatic function, measurements were taken using kits for total bile acids, as well as serum AST, ALT, and ALP activity. Concentrations of IL-1β and TNF-α in serum were quantified using ELISA kits. Transcriptome Sequencing Analysis and 2bRAD-M microbial diversity analysis were employed to evaluate gene expression variance in liver tissue and fecal microbiota diversity among different groups, respectively. Western blotting was performed to observe differences in the activation levels of FXR, SHP, CYP7A1 and PPARα in the liver, and the levels of FXR and FGF-15 genes and proteins in the ileum of mice. Additionally, fecal microbiota transplantation (FMT) experiments were conducted to investigate the potential therapeutic effect of administering the intestinal microbial suspension from mice treated with SY on drug-induced liver injury.

RESULTS

SY treatment exhibited significant hepatoprotective effects in mice, effectively ameliorating drug-induced liver injury while concurrently restoring intestinal microbial dysbiosis. Furthermore, SY administration demonstrated a reduction in the concentration of total bile acids, the expression of FXR and SHP proteins in the liver was up-regulated, CYP7A1 protein was down-regulated, and the expressions of FXR and FGF-15 proteins in the ileum were up-regulated. However, no notable impact on PPARα was observed. Furthermore, results from FMT experiments indicated that the administration of fecal suspensions derived from mice treated with SY did not yield any therapeutic benefits in the context of drug-induced liver injury.

CONCLUSION

The aforementioned findings strongly suggest that SY exerts a pronounced ameliorative effect on drug-induced liver injury through its ability to modulate the expression of key proteins involved in bile acid secretion, thereby preserving hepato-enteric circulation homeostasis.

Adenosine kinase protects against acetaminophen-induced acute liver injury by activating autophagy in hepatocytes

Acute liver injury (ALI) is a common life-threatening condition with a high mortality rate due to liver disease-related death. However, current therapeutic interventions for ALI remain ineffective, and the development of effective novel therapies is urgently needed. Liver samples from patients with drug-induced ALI were collected to detect adenosine kinase (ADK) expression. Male C57BL/6 J mice, hepatocyte-specific ADK knockout (ADKHKO) mice, and their controls (ADKf/f) were exposed to acetaminophen (APAP) and other treatments to investigate the mechanisms of APAP-related ALI. ADK expression was significantly decreased in APAP-injured livers. Hepatocyte-specific ADK deficiency exacerbated APAP-induced ALI, while a gain-of-function approach delivering AAV-ADK, markedly alleviated APAP-induced ALI, as indicated by changes in alanine aminotransferases (ALT) levels, aspartate aminotransferase (AST) levels, neutrophil infiltration and hepatocyte death. This study showed that ADK played a critical role in ALI by activating autophagy through two signaling pathways, the adenosine monophosphate-activated protein kinase (AMPK)-mTOR pathway and the adenosine receptor A1 (ADORA1)-Akt-mTOR pathway. Furthermore, we found that metformin upregulated ADK expression in hepatocytes and protected against APAP-induced ALI. These results demonstrate that ADK is critical in protecting against APAP-induced ALI and that developing therapeutics targeting ADK-adenosine-ADORA1 is a new approach for ALI treatment. Metformin is a potential candidate for preventing ALI by upregulating ADK.

A liver digital twin for in silico testing of cellular and inter-cellular mechanisms in regeneration after drug-induced damage

This communication presents a mathematical mechanism-based model of the regenerating liver after drug-induced pericentral lobule damage resolving tissue microarchitecture. The consequence of alternative hypotheses about the interplay of different cell types on regeneration was simulated. Regeneration dynamics has been quantified by the size of the damage-induced dead cell area, the hepatocyte density and the spatial-temporal profile of the different cell types. We use deviations of observed trajectories from the simulated system to identify branching points, at which the systems behavior cannot be explained by the underlying set of hypotheses anymore. Our procedure reflects a successful strategy for generating a fully digital liver twin that, among others, permits to test perturbations from the molecular up to the tissue scale. The model simulations are complementing current knowledge on liver regeneration by identifying gaps in mechanistic relationships and guiding the system toward the most informative (lacking) parameters that can be experimentally addressed.

3D microperfusion of mesoscale human microphysiological liver models improves functionality and recapitulates hepatic zonation

Hepatic in vitro models that accurately replicate phenotypes and functionality of the human liver are needed for applications in toxicology, pharmacology and biomedicine. Notably, it has become clear that liver function can only be sustained in 3D culture systems at physiologically relevant cell densities. Additionally, drug metabolism and drug-induced cellular toxicity often follow distinct spatial micropatterns of the metabolic zones in the liver acinus, calling for models that capture this zonation. We demonstrate the manufacture of accurate liver microphysiological systems (MPS) via engineering of 3D stereolithography printed hydrogel chips with arrays of diffusion open synthetic vasculature channels at spacings approaching in vivo capillary distances. Chip designs are compatible with seeding of cell suspensions or preformed liver cell spheroids. Importantly, primary human hepatocytes (PHH) and hiPSC-derived hepatocyte-like cells remain viable, exhibit improved molecular phenotypes compared to isogenic monolayer and static spheroid cultures and form interconnected tissue structures over the course of multiple weeks in perfused culture. 3D optical oxygen mapping of embedded sensor beads shows that the liver MPS recapitulates oxygen gradients found in the acini, which translates into zone-specific acet-ami-no-phen toxicity patterns. Zonation, here naturally generated by high cell densities and associated oxygen and nutrient utilization along the flow path, is also documented by spatial proteomics showing increased concentration of periportal- versus perivenous-associated proteins at the inlet region and vice versa at the outlet region. The presented microperfused liver MPS provides a promising platform for the mesoscale culture of human liver cells at phenotypically relevant densities and oxygen exposures. STATEMENT OF SIGNIFICANCE: A full 3D tissue culture platform is presented, enabled by massively parallel arrays of high-resolution 3D printed microperfusion hydrogel channels that functionally mimics tissue vasculature. The platform supports long-term culture of liver models with dimensions of several millimeters at physiologically relevant cell densities, which is difficult to achieve with other methods. Human liver models are generated from seeded primary human hepatocytes (PHHs) cultured for two weeks, and from seeded spheroids of hiPSC-derived human liver-like cells cultured for two months. Both model types show improved functionality over state-of-the-art 3D spheroid suspensions cultured in parallel. The platform can generate physiologically relevant oxygen gradients driven by consumption rather than supply, which was validated by visualization of embedded oxygen-sensitive microbeads, which is exploited to demonstrate zonation-specific toxicity in PHH liver models.

Diphtheria toxin-derived, anti-PD-1 immunotoxin, a potent and practical tool to selectively deplete PD-1+ cells

Programmed death-1 (PD-1), an immune checkpoint receptor, is expressed on activated lymphocytes, macrophages, and some types of tumor cells. While PD-1+ cells have been implicated in outcomes of cancer immunity, autoimmunity, and chronic infections, the exact roles of these cells in various physiological and pathological processes remain elusive. Molecules that target and deplete PD-1+ cells would be instrumental in defining the roles unambiguously. Previously, an immunotoxin has been generated for the depletion of PD-1+ cells though its usage is impeded by its low production yield. Thus, a more practical molecular tool is desired to deplete PD-1+ cells and to examine functions of these cells. We designed and generated a novel anti-PD1 diphtheria immunotoxin, termed PD-1 DIT, targeting PD-1+ cells. PD-1 DIT is comprised of two single chain variable fragments (scFv) derived from an anti-PD-1 antibody, coupled with the catalytic and translocation domains of the diphtheria toxin. PD-1 DIT was produced using a yeast expression system that has been engineered to efficiently produce protein toxins. The yield of PD-1 DIT reached 1-2 mg/L culture, which is 10 times higher than the previously reported immunotoxin. Flow cytometry and confocal microscopy analyses confirmed that PD-1 DIT specifically binds to and enters PD-1+ cells. The binding avidities between PD-1 DIT and two PD-1+ cell lines are approximately 25 nM. Moreover, PD-1 DIT demonstrated potent cytotoxicity toward PD-1+ cells, with a half maximal effective concentration (EC50 ) value of 1 nM. In vivo experiments further showed that PD-1 DIT effectively depleted PD-1+ cells and enabled mice inoculated with PD-1+ tumor cells to survive throughout the study. Our findings using PD-1 DIT revealed the critical role of pancreatic PD-1+ T cells in the development of type-1 diabetes (T1D). Additionally, we observed that PD-1 DIT treatment ameliorated relapsing-remitting experimental autoimmune encephalomyelitis (RR-EAE), a mouse model of relapsing-remitting multiple sclerosis (RR-MS). Lastly, we did not observe significant hepatotoxicity in mice treated with PD-1 DIT, which had been reported for other immunotoxins derived from the diphtheria toxin. With its remarkable selective and potent cytotoxicity toward PD-1+ cells, coupled with its high production yield, PD-1 DIT emerges as a powerful biotechnological tool for elucidating the physiological roles of PD-1+ cells. Furthermore, the potential of PD-1 DIT to be developed into a novel therapeutic agent becomes evident.

To be or not to be: The double-edged sword roles of liver progenitor cells

Given the liver's remarkable and unique regenerative capacity, researchers have long focused on liver progenitor cells (LPCs) and liver cancer stem cells (LCSCs). LPCs can differentiate into both hepatocytes and cholangiocytes. However, the mechanism underlying cell conversion and its distinct contribution to liver homeostasis and tumorigenesis remain unclear. In this review, we discuss the complicated conversions involving LPCs and LCSCs. As the critical intermediate state in malignant transformation, LPCs play double-edged sword roles. LPCs are not only involved in hepatic wound-healing responses by supplementing liver cells and bile duct cells in the damaged liver but may transform into LCSCs under dysregulation of key signaling pathways, resulting in refractory malignant liver tumors. Because LPC lineages are temporally and spatially dynamic, we discuss crucial LPC subgroups and summarize regulatory factors correlating with the trajectories of LPCs and LCSCs in the liver tumor microenvironment. This review elaborates on the double-edged sword roles of LPCs to help understand the liver's regenerative potential and tumor heterogeneity. Understanding the sources and transformations of LPCs is essential in determining how to exploit their regenerative capacity in the future.

In vitro to in vivo acetaminophen hepatotoxicity extrapolation using classical schemes, pharmacodynamic models and a multiscale spatial-temporal liver twin

In vitro to in vivo extrapolation represents a critical challenge in toxicology. In this paper we explore extrapolation strategies for acetaminophen (APAP) based on mechanistic models, comparing classical (CL) homogeneous compartment pharmacodynamic (PD) models and a spatial-temporal (ST), multiscale digital twin model resolving liver microarchitecture at cellular resolution. The models integrate consensus detoxification reactions in each individual hepatocyte. We study the consequences of the two model types on the extrapolation and show in which cases these models perform better than the classical extrapolation strategy that is based either on the maximal drug concentration (Cmax) or the area under the pharmacokinetic curve (AUC) of the drug blood concentration. We find that an CL-model based on a well-mixed blood compartment is sufficient to correctly predict the in vivo toxicity from in vitro data. However, the ST-model that integrates more experimental information requires a change of at least one parameter to obtain the same prediction, indicating that spatial compartmentalization may indeed be an important factor.