Definition of the Chemical and Immunological Signals Involved in Drug-Induced Liver Injury

Involvement of Extracellular Vesicles in the Proinflammatory Response to Clozapine: Implications for Clozapine-Induced Agranulocytosis

Most idiosyncratic drug reactions (IDRs) appear to be immune-mediated, but mechanistic events preceding severe reaction onset remain poorly defined. Damage-associated molecular patterns (DAMPs) may contribute to both innate and adaptive immune phases of IDRs, and changes in extracellular vesicle (EV) cargo have been detected post-exposure to several IDR-associated drugs. To explore the hypothesis that EVs are also a source of DAMPs in the induction of the immune response preceding drug-induced agranulocytosis, the proteome and immunogenicity of clozapine- (agranulocytosis-associated drug) and olanzapine- (non-agranulocytosis-associated drug) exposed EVs were compared in two preclinical models: THP-1 macrophages and Sprague-Dawley rats. Compared with olanzapine, clozapine induced a greater increase in the concentration of EVs enriched from both cell culture media and rat serum. Moreover, treatment of drug-naïve THP-1 cells with clozapine-exposed EVs induced an inflammasome-dependent response, supporting a potential role for EVs in immune activation. Proteomic and bioinformatic analyses demonstrated an increased number of differentially expressed proteins with clozapine that were enriched in pathways related to inflammation, myeloid cell chemotaxis, wounding, transforming growth factor-β signaling, and negative regulation of stimuli response. These data indicate that, although clozapine and olanzapine exposure both alter the protein cargo of EVs, clozapine-exposed EVs carry mediators that exhibit significantly greater immunogenicity. Ultimately, this supports the working hypothesis that drugs associated with a risk of IDRs induce cell stress, release of proinflammatory mediators, and early immune activation that precedes severe reaction onset. Further studies characterizing EVs may elucidate biomarkers that predict IDR risk during development of drug candidates. SIGNIFICANCE STATEMENT: This work demonstrates that clozapine, an idiosyncratic drug-induced agranulocytosis (IDIAG)-associated drug, but not olanzapine, a safer structural analogue, induces an acute proinflammatory response and increases extracellular vesicle (EV) release in two preclinical models. Moreover, clozapine-exposed EVs are more immunogenic, as measured by their ability to activate inflammasomes, and contain more differentially expressed proteins, highlighting a novel role for EVs during the early immune response to clozapine and enhancing our mechanistic understanding of IDIAG and other idiosyncratic reactions.

A transcriptomics and network pharmacology approach to elucidate the mechanism of action of geniposide on carbon tetrachloride-induced liver injury in rats

Geniposide, the main active component of Fructus Gardeniae (FG), is known to confer protection against liver diseases. Herein we explored the hepatoprotective effects of geniposide and elucidated its molecular mechanism by transcriptome RNA-seq and network pharmacology. Liver injury was modeled by intraperitoneally injecting CCl₄ (0.15% prepared with refined peanut oil) at a dose of 1.5 mL/kg thrice a week; from the second week, rats were administered geniposide (20 mg/kg or 40 mg/kg) by gavage for 6 weeks. Serum and liver samples were then collected to assess liver function indicators and inflammatory factors and to observe pathological changes in the liver. The Illumina HiSeq 4000 platform was used to obtain transcriptome data from the liver tissue of rats after geniposide administration. Core targets and pathways related to the liver protection mechanism of geniposide were further analyzed by integrating transcriptomics and network pharmacology. Differentially expressed genes (DEGs), core targets, and signaling pathways were identified by methods such as q-PCR, molecular docking, and Western blotting. We found that after geniposide administration, the levels of aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase, and inflammatory factors decreased in the model group, and liver injury cells be effectively repaired. RNA-seq data analysis showed that compared to control group, the model group reversed 1,451 DEGs; further, compared to model group, geniposide reversed 511 DEGs. Eight key targets, including PIK3R1, ACOX3, and EGF, were found through further analyses. Geniposide was determined to mainly regulate the PPAR signaling pathway, apoptosis signaling pathway, and MAPK signaling pathway in liver tissues. To summarize, the protective and restorative effects of geniposide on rat liver may seem to be related to its efficacy in inhibiting the activation of inflammatory pathways, thereby reducing cell apoptosis. Our findings should serve as the basis for the development of functional foods or drugs to prevent and treat liver diseases.

Microphysiological Models for Mechanistic-Based Prediction of Idiosyncratic DILI

Drug-induced liver injury (DILI) is a major contributor to high attrition rates among candidate and market drugs and a key regulatory, industry, and global health concern. While acute and dose-dependent DILI, namely, intrinsic DILI, is predictable and often reproducible in preclinical models, the nature of idiosyncratic DILI (iDILI) limits its mechanistic understanding due to the complex disease pathogenesis, and recapitulation using in vitro and in vivo models is extremely challenging. However, hepatic inflammation is a key feature of iDILI primarily orchestrated by the innate and adaptive immune system. This review summarizes the in vitro co-culture models that exploit the role of the immune system to investigate iDILI. Particularly, this review focuses on advancements in human-based 3D multicellular models attempting to supplement in vivo models that often lack predictability and display interspecies variations. Exploiting the immune-mediated mechanisms of iDILI, the inclusion of non-parenchymal cells in these hepatoxicity models, namely, Kupffer cells, stellate cells, dendritic cells, and liver sinusoidal endothelial cells, introduces heterotypic cell-cell interactions and mimics the hepatic microenvironment. Additionally, drugs recalled from the market in the US between 1996-2010 that were studies in these various models highlight the necessity for further harmonization and comparison of model characteristics. Challenges regarding disease-related endpoints, mimicking 3D architecture with different cell-cell contact, cell source, and the underlying multi-cellular and multi-stage mechanisms are described. It is our belief that progressing our understanding of the underlying pathogenesis of iDILI will provide mechanistic clues and a method for drug safety screening to better predict liver injury in clinical trials and post-marketing.

Pharmacokinetic-pharmacodynamic (PK/PD) modeling to study the hepatoprotective effect of Perilla Folium on the acute hepatic injury rats

ETHNOPHARMACOLOGICAL RELEVANCE

Perilla Folium (PF), is a traditional medicinal material with the homology of medicine and food in China and has been widely used due to its rich nutritional content and medicinal value. The hepatoprotective effects of PF extract include their protection against acute hepatic injury, tert-butylhydroperoxide (t-BHP) induced oxidative damage, and Lipopolysaccharide (LPS) and D-galactosamine (D-GalN) induced hepatic injury have been well studied. However, there are few reports on the pharmacokinetics studies of PF extract in acute hepatic injury model rats, and the anti-hepatic injury activity of PF is still unclear.

AIM OF THE STUDY

The differences in the plasma pharmacokinetic of 21 active compounds between the normal and model groups were compared， and established pharmacokinetics/pharmacodynamics (PK/PD) modeling was to analyze the hepatoprotective effects of PF.

MATERIALS AND METHODS

The acute hepatic injury model was induced with an intraperitoneal injection of lipopolysaccharide (LPS) and D-galactosamine (D-GalN), and the plasma pharmacokinetics of 21 active compounds of PF were analyzed in the normal and model groups using ultra-high performance liquid chromatography/tandem mass spectrometry (UPLC-MS/MS). The correlation between plasma components and hepatoprotective effects indicators (the alanine aminotransferase (ALT), aspartate aminotransferase (AST) and lactic dehydrogenase (LDH)) in the model group was also investigated and established a Pharmacokinetic/pharmacodynamic (PK/PD) correlation analysis of the hepatoprotective effects of PF.

RESULTS

The results revealed that organic acid compounds possessed the characteristics of faster absorption, shorter peak time and slower metabolism, while the flavonoid compounds had slower absorption and longer peak time, and the pharmacokinetics of various components were significantly affected after modeling. The results of PK/PD modeling analysis demonstrated that the plasma drug concentration of each component existed a good correlation with the three AST, ALT, and LDH, and the lag time of the efficacy of each component is relatively long.

CONCLUSIONS

The plasma drug concentration of each component existed a good correlation with the three AST, ALT, and LDH, and the lag time of the efficacy of each component is relatively long in vivo.

Hepatotoxicity Induced by Azole Antifungal Agents: A Review Study

Context

Fungal infections are very common, and several medications are used to treat them. Azoles are prescribed widely to treat fungal infections. In addition to therapeutic effects, any drug can be accompanied by side effects in patients. One of the most important complications in this regard is liver injury. Therefore, hepatotoxicity induced by azole antifungal drugs were reviewed in this study.

Evidence Acquisition

English scientific papers were evaluated to review the effects of hepatotoxicity by azole antifungal agents, and the related studies' results were summarized using a table. The systematic search was implemented on electronic databases, including PubMed, Google Scholar, and Science Direct. Original articles and review articles that were published before April 1, 2022, were included in the study. Those articles without available full text or non-English articles were excluded. Also, articles that reported pediatric data were excluded.

Results

Most studies have reported the effects of hepatotoxicity by azole antifungal agents, and their mechanisms have been described.

Conclusions

Clinical evaluations regarding the hepatotoxicity of antifungal agents provided in the literature were reviewed. Therefore, it is recommended to prescribe these drugs with caution in high-risk patients suffering from liver diseases, and patients should be monitored for hepatotoxicity. However, more research is needed to evaluate the hepatotoxicity of azole antifungal agents and select appropriate drugs according to cost-effectiveness and the side effects' profiles, relying on lower incidence of this liver complication.

Correlation between serum cytokines and clinicopathological features in patients with drug-induced liver injury

Objectives: Changes in serum levels of cytokines have been proposed as possible biological markers of tissue damage, including drug-induced liver injury (DILI). Here, we aimed to screen cytokine markers that have guiding significance for the degree of inflammation of DILI. Patients and methods: 54 patients with DILI were retrospectively analyzed as the experimental group, and 14 healthy subjects were randomly selected as the control group. A total of 20 cytokines were detected by using a cytokine protein antibody chip, and differentially expressed proteins were screened. Results: There were significant differences in serum cytokines between DILI patients and healthy controls. Compared with the control group, the DILI group expressed 11 differential proteins. IL-8, TNF RII, TNFα, TNF RI, MIP-1β, MIP-1α, and IL-1β were differentially expressed in DILI patients with different degrees of inflammation from G1 to G4. MIG, IL-12p40, and IL-10 were differentially expressed in the higher degree of inflammation groups (G2, G3, and G4 groups). Tissue inhibitor of metalloproteinases-1 (TIMP-1) was differentially expressed in the group with the highest inflammation degree (G4 group). Chemokine C-C motif ligand 1 (I-309) was only differentially expressed in the lowest inflammation group (G1 group). Conclusion: The changes and differential expression of specific cytokine levels were helpful for evaluating different degrees of inflammation of DILI.

Targeting innate immune responses to attenuate acetaminophen-induced hepatotoxicity

Acetaminophen (APAP) hepatotoxicity is an important cause of acute liver failure, resulting in massive deaths in many developed countries. Currently, the metabolic process of APAP in the body has been well studied. However, the underlying mechanism of APAP-induced liver injury remains elusive. Increasing clinical and experimental evidences indicate that the innate immune responses are involved in the pathogenesis of APAP-induced acute liver injury (AILI), in which immune cells have dual roles of inducing inflammation to exacerbate hepatotoxicity and removing dead cells and debris to help liver regeneration. In this review, we summarize the latest findings of innate immune cells involved in AILI, particularly emphasizing the activation of innate immune cells and their different roles during the injury and repair phases. Moreover, current available treatments are discussed according to the different roles of innate immune cells in the development of AILI. This review aims to update the knowledge about innate immune responses in the pathogenesis of AILI, and provide potential therapeutic interventions for AILI.

Idiosyncratic Drug Reactions: A 35-Year Chemical Research in Toxicology Perspective

When Larry Marnett founded Chemical Research in Toxicology, the study of idiosyncratic drug reactions (IDRs) was in its infancy. There was evidence that IDRs involve chemically reactive metabolites, and many of the papers in Chemical Research in Toxicology investigated the bioactivation of drugs. However, it became clear that not all drugs that form reactive metabolites are associated with a high risk of IDRs, and some drugs that do not appear to form reactive metabolites do cause IDRs. Some of the early Chemical Research in Toxicology papers investigated involvement of the adaptive immune system in the mechanism of IDRs, and HLA associations provided strong evidence for an immune mechanism of IDRs. This led to the question of how reactive metabolites might induce an immune response. The classic hapten hypothesis provided an obvious explanation, but a new hypothesis the danger hypothesis, added another dimension. Although there are common features to IDRs, it is becoming increasingly clear that there are also many differences in the mechanisms caused by different drugs. Other pharmacological effects of drugs may also play a role in the mechanism, and that is obviously true of IDRs caused by biological agents. The requirement for specific HLA and T-cell receptors is presumably the major factor that makes IDRs idiosyncratic. However, an innate immune response is required to prime the adaptive immune response. In contrast to the adaptive immune response, the innate immune response is unlikely to be idiosyncratic, and studies of the innate immune response to drugs may provide a much more accurate way to screen drugs for their potential to cause IDRs. For essential drugs that are known to cause IDRs, it may be possible to markedly decrease risk by a slow dose titration to induce immune tolerance. Significant progress has been made in the study of IDRs, but there is still a long way to go.

In vitro cell-based models of drug-induced hepatotoxicity screening: progress and limitation

Drug-induced liver injury (DILI) is one of the major causes of post-approval withdrawal of therapeutics. As a result, there is an increasing need for accurate predictive in vitro assays that reliably detect hepatotoxic drug candidates while reducing drug discovery time, costs, and the number of animal experiments. In vitro hepatocyte-based research has led to an improved comprehension of the underlying mechanisms of chemical toxicity and can assist the prioritization of therapeutic choices with low hepatotoxicity risk. Therefore, several in vitro systems have been generated over the last few decades. This review aims to comprehensively present the development and validation of 2D (two-dimensional) and 3D (three-dimensional) culture approaches on hepatotoxicity screening of compounds and highlight the main factors affecting predictive power of experiments. To this end, we first summarize some of the recognized hepatotoxicity mechanisms and related assays used to appraise DILI mechanisms and then discuss the challenges and limitations of in vitro models.

Successful Treatment with Ensartinib After Alectinib-induced Hyperbilirubinemia in ALK-Positive NSCLC

Background

Alectinib is approved for the treatment of advanced non-small-cell lung cancer (NSCLC) harboring ALK rearrangements. Although generally well tolerated, alectinib can cause serious or life-threatening side effects.

Case Presentation

Here, we report a case of a patient with NSCLC with an EML4-ALK fusion and was treated with alectinib but who developed grade 4 hyperbilirubinemia after five months on therapy. Alectinib was discontinued, and an artificial liver support system (ALSS) was used with an impressive decline in bilirubin levels. After two months drug-free, the patient experienced disease progression. Ensartinib was initiated as second-line treatment with a best response of stable disease after three months of therapy with no evidence of hyperbilirubinemia.

Conclusion

This is the first report of ensartinib treatment after alectinib-induced hyperbilirubinemia which was successfully relieved by ALSS treatment and targeted drug cessation.

The Emerging Role of the Innate Immune Response in Idiosyncratic Drug Reactions

Idiosyncratic drug reactions (IDRs) range from relatively common, mild reactions to rarer, potentially life-threatening adverse effects that pose significant risks to both human health and successful drug discovery. Most frequently, IDRs target the liver, skin, and blood or bone marrow. Clinical data indicate that most IDRs are mediated by an adaptive immune response against drug-modified proteins, formed when chemically reactive species of a drug bind to self-proteins, making them appear foreign to the immune system. Although much emphasis has been placed on characterizing the clinical presentation of IDRs and noting implicated drugs, limited research has focused on the mechanisms preceding the manifestations of these severe responses. Therefore, we propose that to address the knowledge gap between drug administration and onset of a severe IDR, more research is required to understand IDR-initiating mechanisms; namely, the role of the innate immune response. In this review, we outline the immune processes involved from neoantigen formation to the result of the formation of the immunologic synapse and suggest that this framework be applied to IDR research. Using four drugs associated with severe IDRs as examples (amoxicillin, amodiaquine, clozapine, and nevirapine), we also summarize clinical and animal model data that are supportive of an early innate immune response. Finally, we discuss how understanding the early steps in innate immune activation in the development of an adaptive IDR will be fundamental in risk assessment during drug development. SIGNIFICANCE STATEMENT: Although there is some understanding that certain adaptive immune mechanisms are involved in the development of idiosyncratic drug reactions, the early phase of these immune responses remains largely uncharacterized. The presented framework refocuses the investigation of IDR pathogenesis from severe clinical manifestations to the initiating innate immune mechanisms that, in contrast, may be quite mild or clinically silent. A comprehensive understanding of these early influences on IDR onset is crucial for accurate risk prediction, IDR prevention, and therapeutic intervention.

Hepatotoxicity of FDA-approved small molecule kinase inhibitors

Introduction: Given their importance in cellular processes and association with numerous diseases, protein kinases have emerged as promising targets for drugs. The FDA has approved greater than fifty small molecule kinase inhibitors (SMKIs) since 2001. Nevertheless, severe hepatotoxicity and related fatal cases have grown as a potential challenge in the advancement of these drugs, and the identification and diagnosis of drug-induced liver injury (DILI) are thorny problems for clinicians.Areas covered: This article summarizes the progression and analyzes the significant features in the study of SMKI hepatotoxicity, including clinical observations and investigations of the underlying mechanisms.Expert opinion: The understanding of SMKI-associated hepatotoxicity relies on the development of preclinical models and improvement of clinical assessment. With a full understanding of the role of inflammation in DILI and the mediating role of cytokines in inflammation, cytokines are promising candidates as sensitive and specific biomarkers for DILI. The emergence of three-dimensional spheroid models demonstrates potential use in providing clinically relevant data and predicting hepatotoxicity of SMKIs.