Emodin Attenuates Acetaminophen-Induced Hepatotoxicity via the cGAS-STING Pathway

Preclinical liver toxicity models: Advantages, limitations and recommendations

Experimental animal models are crucial for elucidating the pathophysiology of liver injuries and for assessing new hepatoprotective agents. Drugs and chemicals such as acetaminophen, isoniazid, valproic acid, ethanol, carbon tetrachloride (CCl4), dimethylnitrosamine (DMN), and thioacetamide (TAA) are metabolized by the CYP2E1 enzyme, producing hepatotoxic metabolites that lead to both acute and chronic liver injuries. In experimental settings, acetaminophen (centrilobular necrosis), carbamazepine (centrilobular necrosis and inflammation), sodium valproate (necrosis, hydropic degeneration and mild inflammation), methotrexate (sinusoidal congestion and inflammation), and TAA (centrilobular necrosis and inflammation) are commonly used to induce various types of acute liver injuries. Repeated and intermittent low-dose administration of CCl4, TAA, and DMN activates quiescent hepatic stellate cells, transdifferentiating them into myofibroblasts, which results in abnormal extracellular matrix production and fibrosis induction, more rapidly with DMN and CCL4 than TAA (DMN > CCl4 > TAA). Regarding toxicity and mortality, CCl4 is more toxic than DMN and TAA (CCl4 > DMN > TAA). Models used to induce metabolic dysfunction-associated liver disease (MAFLD) vary, but MAFLD's multifactorial nature driven by factors like obesity, fatty liver, dyslipidaemia, type II diabetes, hypertension, and cardiovascular disease makes it challenging to replicate human metabolic dysfunction-associated steatohepatitis accurately. From an experimental point of view, the degree and pattern of liver injury are influenced by various factors, including the type of hepatotoxic agent, exposure duration, route of exposure, dosage, frequency of administration, and the animal model utilized. Therefore, there is a pressing need for standardized protocols and regulatory guidelines to streamline the selection of animal models in preclinical studies.

Progress of cGAS-STING signaling pathway-based modulation of immune response by traditional Chinese medicine in clinical diseases

The cGAS-STING signaling pathway is a critical component of the innate immune response, playing a significant role in various diseases. As a central element of this pathway, STING responds to both endogenous and exogenous DNA stimuli, triggering the production of interferons and pro-inflammatory cytokines to enhance immune defenses against tumors and pathogens. However, dysregulated activation of the STING pathway is implicated in the pathogenesis of multiple diseases, including autoinflammation, viral infections, and cancer. Traditional Chinese Medicines (TCMs), which have a long history of use, have been associated with positive effects in disease prevention and treatment. TCM formulations (e.g., Lingguizhugan Decoction, Yi-Shen-Xie-Zhuo formula) and active compounds (e.g., Glabridin, Ginsenoside Rd) can modulate the cGAS-STING signaling pathway, thereby influencing the progression of inflammatory, infectious, or oncological diseases. This review explores the mechanisms by which TCMs interact with the cGAS-STING pathway to regulate immunity, focusing on their roles in infectious diseases, malignancies, and autoimmune disorders.

The crucial roles and research advances of cGAS‑STING pathway in liver diseases

Inflammation responses have identified as a key mediator of in various liver diseases with high morbidity and mortality. cGAS-STING signalling is essential in innate immunity since it triggers release of type I interferons and various of proinflammatory cytokines. The potential connection between cGAS-STING pathway and liver inflammatory diseases has recently been reported widely. In our review, the impact of cGAS-STING on liver inflammation and regulatory mechanism are summarized. Furthermore, many inhibitors of cGAS-STING signalling as promising agents to cure liver inflammation are also explored in detail. A comprehensive knowledge of molecular mechanisms of cGAS-STING signalling in liver inflammation is vital for exploring novel treatments and providing recommendations and perspectives for future utilization.

Emodin suppresses mast cell migration via modulating the JAK2/STAT3/JMJD3/CXCR3 signaling to prevent cystitis

AIMS

This study aimed to determine the preventive effects of emodin on cyclophosphamide (CYP)-induced cystitis and to explore the molecular mechanism.

METHODS

In vivo, mice were modeled by CYP. Before a half hour of CYP treatment, Jumonji domain-containing protein-3 (JMJD3) inhibitors (GSK-J4) and emodin were used to treat CYP model mice. Bladder samples were stained for hematoxylin-eosin and toluidine blue. Next, JMJD3 was quantified by immunofluorescence staining, RT-PCR, and Western blot. CXCR3 was quantified by Western blot and ELISA. In vitro, before stimulated by lipopolysaccharide (LPS), human bladder smooth muscle cells (hBSMCs) were transfected with pcDNA3.1-JMJD3 plasmids, shRNA-JMJD3 plasmids or pretreated with emodin. Collected cells to detect JMJD3 and CXCR3 ligands again; collected supernatant of culture for Transwell assay. Finally, as the JAK2 inhibitor, AG490 was used to pretreat LPS-induced hBSMCs. Western blot was performed to quantify proteins.

RESULTS

Emodin inhibited mast cell migration and suppressed the expression of JMJD3, CXCR3, and CXCR3 ligands, not only in vivo but also in vitro. The pharmacological effects of emodin were similar to GSK-J4 or JMJD3 inhibition. In addition, emodin significantly downregulated the phosphorylation of JAK2 and STAT3, and inhibited JMJD3/CXCR3 axis transduction like AG490.

CONCLUSION

Emodin has a preventive effect on cystitis by inhibiting mast cell migration through inhibition of the JAK2/STAT3/JMJD3/CXCR3 signaling pathway.

Evaluating the therapeutic potential of genetically engineered probiotic Zbiotics (ZB183) for non-alcoholic steatohepatitis (NASH) management via modulation of the cGAS-STING pathway

NAFLD/NASH has emerged as a global health concern with no FDA-approved treatment, necessitating the exploration of novel therapeutic elements for NASH. Probiotics are known as an important adjunct therapy in NASH. Zbiotics (ZB183) is the first commercially available genetically engineered probiotic. Herein, we aimed to evaluate the potential therapeutic effects of Zbiotics administration on NASH management by modulating the cGAS-STING-signaling pathway-related RNA network. In silico data analysis was performed and three DEGs (MAPK3/EDN1/TNF) were selected with their epigenetic modulators (miR-6888-5p miRNA, and lncRNA RABGAP1L-DT-206). The experimental design included NASH induction with an HSHF diet in Wistar rats and Zbiotics administration in NASH rats in comparison to statin treatment. Liver functions and lipid profile were assessed. Additionally, the expression levels of the constructed molecular network were assessed using RT-PCR. Moreover, the Zbiotics effects in NASH were further validated with histopathological examination of liver and colon samples. Also, immunohistochemistry staining of hepatic TNF-α and colonic occludin was assessed. Oral administration of Zbiotics for four weeks downregulated the expression of the cGAS-STING-related network (MAPK3/EDN1/TNF/miR-6888-5p miRNA/lncRNA RABGAP1L-DT-206) in NASH models. Zbiotics also ameliorated hepatic inflammation and steatosis, as evidenced by a notable improvement in NAS score and decreased hepatic TNF-α levels. Furthermore, Zbiotics exhibited favorable effects on colon health, including increased crypt length, reduced inflammatory cell infiltration, and restoration of colonic mucosa occludin expression. In conclusion, our findings suggest that Zbiotics has potential therapeutic effects on NASH via modulating the gut-liver axis and the cGAS-STING signaling pathway.

Empagliflozin impact on experimentally induced acetaminophen toxicity: Imprint of mitochondrial dynamics, biogenesis, and cGAS/STING signal in amending liver insult

Acetaminophen (APAP) is one of the most clinically relevant medications associated with acute liver damage. A prolific deal of research validated the hepatoprotective effect of empagliflozin (EMPA); however, its effect on APAP-induced hepatotoxicity has still not been investigated. In this study, the prospective hepatoprotective impact of EMPA against APAP-induced hepatotoxicity was investigated. Twenty-eight Balb-C mice were assigned to four groups: control, APAP, EMPA10/APAP, and EMPA25/APAP. At the end of the experiment, serum hepatotoxicity biomarkers, MDA level, and GSH content were estimated. Hepatic mitofusin-2 (MFN2), optic atrophy 1 (OPA1), dynamin-related protein 1 (Drp1), and mitochondrial fission 1 protein (FIS1) were immunoassayed. PGC-1α, cGAS, and STING mRNA expression were assessed by real-time PCR. Histopathological changes and immunohistochemistry of INF-β, p-NF-κB, and iNOS were evaluated. APAP treatment caused significant hepatic functional impairment and increased hepatic MDA levels, as well as a concomitant decrease in GSH content. Marked elevation in Drp1 and FIS1 levels, INF-ß, p-NF-κB, and iNOS immunoreactivity, and reduction in MFN2 and OPA1 levels in the APAP-injected group, PGC-1α downregulation, and high expression of cGAS and STING were also documented. EMPA effectively ameliorated APAP-generated structural and functional changes in the liver, restored redox homeostasis and mitochondrial dynamics balance, and enhanced mitochondrial biogenesis, remarkably diminished hepatic expression of cGAS and STING, and elicited a reduction in hepatic inflammation. Moreover, the computational modeling data support the interaction of APAP with antioxidant system-related proteins as well as the interactions of EMPA against Drp1, cGAS, IKKA, and iNOS proteins. Our findings demonstrated for the first time that EMPA has an ameliorative impact against APAP-induced hepatotoxicity in mice via modulation of mitochondrial dynamics, biogenesis, and cGAS/STING-dependent inflammation. Thus, this study concluded that EMPA could be a promising therapeutic modality for acute liver toxicity.

Emodin alleviates cholestatic liver injury by modulating Sirt1/Fxr signaling pathways

Emodin (EMO) has the effect of anti-cholestasis induced by alpha-naphthylisothiocyanate (ANIT). But its mechanism is still unclear. The farnesoid X receptor (Fxr) is the master bile acid nuclear receptor. Recent studies have reported that Sirtuin 1 (Sirt1) can regulate the activities of Fxr. The purpose of the current study was to investigate the mechanism of EMO against ANIT-induced liver injury based on Sirt1/Fxr signaling pathway. The ANIT-induced cholestatic rats were used with or without EMO treatment. Serum biochemical indicators, as well as liver histopathological changes were examined. The genes expressions of Sirt1, Fxr, Shp, Bsep and Mrp2 were detected. The expressions of Sirt1, Fxr and their downstream related genes were investigated in vitro. The results showed that EMO significantly alleviated ANIT-induced liver injury in rats, and increased Sirt1, Fxr, Shp, Bsep and Mrp2 gene expression in liver, while decreased the expression of Cyp7a1. EMO significantly activated Fxr, while Sirt1 inhibitor and Sirt1 gene silencing significantly reduced Fxr activity in vitro. Collectively, EMO in the right dose has a protective effect on liver injury induced by ANIT, and the mechanism may be through activation of Fxr by Sirt1, thus regulating bile acid metabolism, and reducing bile acid load in hepatocytes.

Dahuang-Wumei decoction protects against hepatic encephalopathy in mice: Behavioural, biochemical, and molecular evidence

BACKGROUND

Disturbance of the blood‒brain barrier (BBB) and associated inflammatory responses are observed in patients with hepatic encephalopathy (HE) and can cause long-term complications. Dahuang-Wumei decoction (DWD) is a renowned traditional Chinese herbal medicine with a long history of clinical use and has been widely employed as an effective treatment for hepatic encephalopathy (HE). Despite its established efficacy, the precise mechanisms underlying the therapeutic effects of DWD have not been fully elucidated.

PURPOSE

The present study aimed to comprehensively explore the potential effects and underlying molecular mechanisms of DWD on HE through an integrated investigation that included both in vivo and in vitro experiments.

METHODS

In the present study, carbon tetrachloride (CCl4) and thioacetamide (TAA) were used to establish an HE model in mice. The therapeutic effects of DWD on liver injury, fibrosis, brain injury, behaviour, and consciousness disorders were evaluated in vivo. C8-D1A and bEnd.3 cells were used to construct a BBB model in vitro. The effects of DWD on proinflammatory factor expression, BBB damage and the Wnt/β-catenin pathway were detected in vivo and in vitro.

RESULTS

Our results showed that DWD can improve liver injury and fibrosis and brain damage and inhibit neurofunctional and behavioural disorders in mice with HE. Afterwards, we found that DWD decreased the levels of proinflammatory factors and suppressed BBB disruption by increasing the levels of junction proteins in vivo and vitro. Further studies verified that the Wnt/β-catenin pathway may play a pivotal role in mediating the inhibitory effect of DWD on HE.

CONCLUSION

These results demonstrated that DWD can treat HE by preventing BBB disruption, and the underlying mechanisms involved were associated with the activation of the Wnt/β-catenin pathway and the inhibition of inflammatory responses.

The dual function of cGAS-STING signaling axis in liver diseases

Numerous liver diseases, such as nonalcoholic fatty liver disease, hepatitis, hepatocellular carcinoma, and hepatic ischemia-reperfusion injury, have been increasingly prevalent, posing significant threats to global health. In recent decades, there has been increasing evidence linking the dysregulation of cyclic-GMP-AMP synthase (cGAS)-stimulator of interferon gene (STING)-related immune signaling to liver disorders. Both hyperactivation and deletion of STING can disrupt the immune microenvironment dysfunction, exacerbating liver disorders. Consequently, there has been a surge in research investigating medical agents or mediators targeting cGAS-STING signaling. Interestingly, therapeutic manipulation of the cGAS-STING pathway has yielded inconsistent and even contradictory effects on different liver diseases due to the distinct physiological characteristics of intrahepatic cells that express and respond to STING. In this review, we comprehensively summarize recent advancements in understanding the dual roles of the STING pathway, highlighting that the benefits of targeting STING signaling depend on the specific types of target cells and stages of liver injury. Additionally, we offer a novel perspective on the suitability of STING agonists and antagonists for clinical assessment. In conclusion, STING signaling remains a highly promising therapeutic target, and the development of STING pathway modulators holds great potential for the treatment of liver diseases.

cGAS-STING, inflammasomes and pyroptosis: an overview of crosstalk mechanism of activation and regulation

BACKGROUND

Intracellular DNA-sensing pathway cGAS-STING, inflammasomes and pyroptosis act as critical natural immune signaling axes for microbial infection, chronic inflammation, cancer progression and organ degeneration, but the mechanism and regulation of the crosstalk network remain unclear. Cellular stress disrupts mitochondrial homeostasis, facilitates the opening of mitochondrial permeability transition pore and the leakage of mitochondrial DNA to cell membrane, triggers inflammatory responses by activating cGAS-STING signaling, and subsequently induces inflammasomes activation and the onset of pyroptosis. Meanwhile, the inflammasome-associated protein caspase-1, Gasdermin D, the CARD domain of ASC and the potassium channel are involved in regulating cGAS-STING pathway. Importantly, this crosstalk network has a cascade amplification effect that exacerbates the immuno-inflammatory response, worsening the pathological process of inflammatory and autoimmune diseases. Given the importance of this crosstalk network of cGAS-STING, inflammasomes and pyroptosis in the regulation of innate immunity, it is emerging as a new avenue to explore the mechanisms of multiple disease pathogenesis. Therefore, efforts to define strategies to selectively modulate cGAS-STING, inflammasomes and pyroptosis in different disease settings have been or are ongoing. In this review, we will describe how this mechanistic understanding is driving possible therapeutics targeting this crosstalk network, focusing on the interacting or regulatory proteins, pathways, and a regulatory mitochondrial hub between cGAS-STING, inflammasomes, and pyroptosis.

SHORT CONCLUSION

This review aims to provide insight into the critical roles and regulatory mechanisms of the crosstalk network of cGAS-STING, inflammasomes and pyroptosis, and to highlight some promising directions for future research and intervention.

Anti-Proliferative and Apoptotic Activities of Rumex crispus

Colorectal cancer is the fourth leading cause of cancer death and the third most common cancer diagnosed in the United States. Several anticancer compounds from natural products have been of great interest in cancer chemotherapy and are currently in clinical trials. Natural products that present the targeted killing of cancerous cell and are soluble in water with minimal side effects are ideal candidates. In this study, water-soluble compounds from Rumex crispus plants were screened for anti-proliferative and apoptotic activity against human colorectal adenocarcinoma (DLD-1) cells. The most potent fraction with the highest cell killing and caspase fold change rates was selected for further experiments. The observed changes were further validated by measuring the caspase fold change using RT-qPCR. Furthermore, gene transcript levels were evaluated using an RT2 Profiler assay and a microarray experiment. Our results showed that the most potent L19 fraction exhibits anti-proliferative activity in a dose-dependent manner. The L19 fraction was found to induce apoptotic pathways by triggering different caspases and inflammatory pathways through the activation of non-apoptotic genes. Our study identified and validated the anticancer property of the L19 fraction, which can serve as a strong lead compound for the synthesis of other novel potent analogues.

Natural Products for Acetaminophen-Induced Acute Liver Injury: A Review

The liver plays a vital role in metabolism, synthesis, and detoxification, but it is susceptible to damage from various factors such as viral infections, drug reactions, excessive alcohol consumption, and autoimmune diseases. This susceptibility is particularly problematic for patients requiring medication, as drug-induced liver injury often leads to underestimation, misdiagnosis, and difficulties in treatment. Acetaminophen (APAP) is a widely used and safe drug in therapeutic doses but can cause liver toxicity when taken in excessive amounts. This study aimed to investigate the hepatotoxicity of APAP and explore potential treatment strategies using a mouse model of APAP-induced liver injury. The study involved the evaluation of various natural products for their therapeutic potential. The findings revealed that natural products demonstrated promising hepatoprotective effects, potentially alleviating liver damage and improving liver function through various mechanisms such as oxidative stress and inflammation, which cause changes in signaling pathways. These results underscore the importance of exploring novel treatment options for drug-induced liver injury, suggesting that further research in this area could lead to the development of effective preventive and therapeutic interventions, ultimately benefiting patients with liver injury caused by medicine.

Polydatin alleviates sepsis‑induced acute lung injury via downregulation of Spi‑B

Sepsis-induced acute lung injury (ALI) is related to the dysregulation of inflammatory responses. Polydatin supplement was reported to exhibit anti-inflammatory effects in several diseases. The present study aimed to investigate the role of polydatin in sepsis-induced ALI. A cecum ligation and puncture (CLP)-induced mouse ALI model was established first and the pathological changes of lung tissues were assessed using hematoxylin and eosin staining. Meanwhile, to mimic sepsis-induced ALI in vitro, pulmonary microvascular endothelial cells (PMVECs) were treated with lipopolysaccharide (LPS). Pro-inflammatory cytokines levels were measured in lung tissues and PMVECs using ELISA. Reverse transcription-quantitative PCR was used to measure the mRNA levels of Spi-B in lung tissues and PMVECs. Moreover, the expression levels of Spi-B, p-PI3K, p-Akt, and p-NF-κB in lung tissues and PMVECs were determined using western blotting. The data revealed that polydatin attenuated CLP-induced lung injury and inhibited sepsis-induced inflammatory responses in mice. Furthermore, polydatin significantly inhibited the expression of Spi-B, p-PI3K, p-Akt, and p-NF-κB in lung tissues of mice subjected to CLP-induced ALI, while this phenomenon was reversed through Spi-B overexpression. Consistently, the anti-inflammatory effect of polydatin was abolished by Spi-B overexpression. Taken together, the current findings revealed that polydatin alleviated sepsis-induced ALI via the downregulation of Spi-B.

Activation of cDCs and iNKT cells contributes to triptolide-induced hepatotoxicity via STING signaling pathway and endoplasmic reticulum stress

Triptolide (TP) exhibits therapeutic potential against multiple diseases. However, its application in clinics is limited by TP-induced hepatoxicity. TP can activate invariant natural killer T (iNKT) cells in the liver, shifting Th1 cytokine bias to Th2 cytokine bias. The damaging role of iNKT cells in TP-induced hepatoxicity has been established, and iNKT cell deficiency can mitigate hepatotoxicity. However, the activation of iNKT cells in vitro by TP requires the presence of antigen-presenting cells. Therefore, we hypothesized that TP could induce dendritic cells (DCs) to activate iNKT cells, thereby leading to hepatotoxicity. The hepatic conventional DCs (cDCs) exhibited immunogenic activities after TP administration, upregulating the expression of CD1d, co-stimulatory molecules, and IL-12. Neutralization with IL-12p40 antibody extenuated TP-induced hepatotoxicity and reduced iNKT cell activation, suggesting that IL-12 could cause liver injury by activating iNKT cells. TP triggered the activation and upregulation of STING signaling pathway and increased endoplasmic reticulum (ER) stress. Downregulation of STING reduced cDC immunogenicity, inhibiting the activation of iNKT cells and hepatic damage. These indicated the regulatory effects of STING pathway on cDCs and iNKT cells, and the important roles it plays in hepatoxicity. ER stress inhibitor, 4-phenylbutyrate (4-PBA), also suppressed iNKT cell activation and liver injury, which might be regulated by the STING signaling pathway. Our results demonstrated the possible mechanisms underlying TP-induced hepatoxicity, where the activation of cDCs and iNKT cells was stimulated by upregulated STING signaling and increased ER stress as a result of TP administration.

Emodin attenuates inflammation and demyelination in experimental autoimmune encephalomyelitis

Emodin, a substance extracted from herbs such as rhubarb, has a protective effect on the central nervous system. However, the potential therapeutic effect of emodin in the context of multiple sclerosis remains unknown. In this study, a rat model of experimental autoimmune encephalomyelitis was established by immune induction to simulate multiple sclerosis, and the rats were intraperitoneally injected with emodin (20 mg/kg/d) from the day of immune induction until they were sacrificed. In this model, the nucleotide-binding domain-like receptor family pyrin domain containing 3 (NLRP3) inflammasome and the microglia exacerbated neuroinflammation, playing an important role in the development of multiple sclerosis. In addition, silent information regulator of transcription 1 (SIRT1)/peroxisome proliferator-activated receptor-alpha coactivator (PGC-1α) was found to inhibit activation of the NLRP3 inflammasome, and SIRT1 activation reduced disease severity in experimental autoimmune encephalomyelitis. Furthermore, treatment with emodin decreased body weight loss and neurobehavioral deficits, alleviated inflammatory cell infiltration and demyelination, reduced the expression of inflammatory cytokines, inhibited microglial aggregation and activation, decreased the levels of NLRP3 signaling pathway molecules, and increased the expression of SIRT1 and PGC-1α. These findings suggest that emodin improves the symptoms of experimental autoimmune encephalomyelitis, possibly through regulating the SIRT1/PGC-1α/NLRP3 signaling pathway and inhibiting microglial inflammation. These findings provide experimental evidence for treatment of multiple sclerosis with emodin, enlarging the scope of clinical application for emodin.

Induction of Nrf2-EpRE-mediated gene expression by hydroxyanthraquinones present in extracts from traditional Chinese medicine and herbs

Hydroxyanthraquinones that can be present in traditional Chinese medicine (TCM) and herbal extracts have claimed beneficial intestinal effects. We examined the ability of a panel hydroxyanthraquinones, and methanolic extracts from selected TCM and herbal granules to activate Nrf2-EpRE mediated gene expression using a reporter-gene assay. The results indicate that purpurin, aloe-emodin, 2-hydroxy-3-methylanthraquinone and rhein induced Nrf2 mediated gene expressions with a high induction factor (IFs>10), with BMCL₁₀ values (the lower confidence limit of the concentration giving 10% added response above background) of 16 μM, 1.1 μM, 23 μM and 2.3 μM, respectively, while aurantio-obtusin, obtusifolin, rubiadin 1-methyl ether and emodin were less potent (IFs<5), with BMCL₁₀ values for added response above background level of 4.6 μM, 15 μM, 9.8 μM and 3.8 μM, respectively. All TCM extracts and the herbal extracts of Aloe Vera, Polygonum multiflorum, Rubia (cordifolia) and Rheum officinale activated the Nrf2-EpRE pathway. Of the TCM extracts, Chuan-Xin-Lian-Kang-Yan-Pian was the most potent Nrf2-inducer. LC-MS/MS analysis indicated the presence of selected hydroxyanthraquinones in the extracts and herbs, in part explaining their Nrf2-EpRE mediated activity. In conclusion, different hydroxyanthraquinones have different potencies of Nrf2 activation. The Nrf2 activation by extracts from TCM and herbs can be partially explained by the presence of selected hydroxyanthraquinones.

Acetaminophen-induced liver injury: Molecular mechanism and treatments from natural products

Acetaminophen (APAP) is a widely used analgesic and antipyretic over-the-counter medicine worldwide. Hepatotoxicity caused by APAP overdose is one of the leading causes of acute liver failure (ALF) in the US and in some parts of Europe, limiting its clinical application. Excessive APAP metabolism depletes glutathione and increases N-acetyl-p-benzoquinoneimide (NAPQI) levels, leading to oxidative stress, DNA damage, and cell necrosis in the liver, which in turn leads to liver damage. Studies have shown that natural products such as polyphenols, terpenes, anthraquinones, and sulforaphane can activate the hepatocyte antioxidant defense system with Nrf2 as the core player, reduce oxidative stress damage, and protect the liver. As the key enzyme metabolizing APAP into NAPQI, cytochrome P450 enzymes are also considered to be intriguing target for the treatment of APAP-induced liver injury. Here, we systematically review the hepatoprotective activity and molecular mechanisms of the natural products that are found to counteract the hepatotoxicity caused by APAP, providing reference information for future preclinical and clinical trials of such natural products.

The immunological mechanisms and therapeutic potential in drug-induced liver injury: lessons learned from acetaminophen hepatotoxicity

Acute liver failure caused by drug overdose is a significant clinical problem in developed countries. Acetaminophen (APAP), a widely used analgesic and antipyretic drug, but its overdose can cause acute liver failure. In addition to APAP-induced direct hepatotoxicity, the intracellular signaling mechanisms of APAP-induced liver injury (AILI) including metabolic activation, mitochondrial oxidant stress and proinflammatory response further affect progression and severity of AILI. Liver inflammation is a result of multiple interactions of cell death molecules, immune cell-derived cytokines and chemokines, as well as damaged cell-released signals which orchestrate hepatic immune cell infiltration. The immunoregulatory interplay of these inflammatory mediators and switching of immune responses during AILI lead to different fate of liver pathology. Thus, better understanding the complex interplay of immune cell subsets in experimental models and defining their functional involvement in disease progression are essential to identify novel therapeutic targets for the treatment of AILI. Here, this present review aims to systematically elaborate on the underlying immunological mechanisms of AILI, its relevance to immune cells and their effector molecules, and briefly discuss great therapeutic potential based on inflammatory mediators.

Long-Term Consumption of Food-Derived Chlorogenic Acid Protects Mice against Acetaminophen-Induced Hepatotoxicity via Promoting PINK1-Dependent Mitophagy and Inhibiting Apoptosis

Hepatotoxicity brought on by acetaminophen (APAP) is significantly impacted by mitochondrial dysfunction. Mitophagy, particularly PINK1-mediated mitophagy, maintains the stability of cell function by eliminating damaged mitochondria. One of the most prevalent dietary polyphenols, chlorogenic acid (CGA), has been shown to have hepatoprotective properties. It is yet unknown, nevertheless, whether its defense against hepatocyte apoptosis involves triggering PINK1-mediated mitophagy. In vitro and in vivo models of APAP-induced hepatotoxicity were established to observe CGA's effect and mechanism in preventing hepatotoxicity in the present study. Serum aminotransferase levels, mouse liver histology, and the survival rate of HepG2 cells and mice were also assessed. The outcomes showed that CGA could reduce the activities of serum enzymes such as alanine transaminase (ALT), aspartate transaminase (AST), and lactate dehydrogenase (LDH), and alleviate liver injury in mice. It could also significantly increase the cell viability of HepG2 cells and the 24-h survival rate of mice. TUNEL labeling and Western blotting were used to identify the hepatocyte apoptosis level. According to data, CGA could significantly reduce liver cell apoptosis in vivo. Additionally, Tom20 and LC3II colocalization in mitochondria may be facilitated by CGA. CGA considerably increased the levels of genes and proteins associated with mitophagy (PINK1, Parkin, LC3II/LC3I), while considerably decreasing the levels of p62 and Tom20, suggesting that it might activate PINK1/Parkin-mediated mitophagy in APAP-induced liver damage. Additionally, the protection of CGA was reduced when PINK1 was knocked down by siPINK1 in HepG2 cells, and it did not upregulate mitophagy-related proteins (PINK1, Parkin, LC3II/LC3I). In conclusion, our findings revealed that long-term consumption of food-derived CGA could prevent APAP hepatotoxicity via increasing PINK1-dependent mitophagy and inhibiting hepatocyte apoptosis.

Evaluation on Hepatoprotection of Dihydromyricetin in Acetaminophen-Induced Hepatotoxicity Based on Analysis of Inflammation and Apoptosis Mediated by PI3K/AKT Pathway

Purpose: We aimed to investigate whether dihydromyricetin (DHM) could alleviate acetaminophen (APAP)-induced liver damage in mice, and to verify whether the process is associated with the PI3K/AKT signaling pathway. Methods: The contents of DHM in serum and related physiological indicators in blood and liver tissue were measured, respectively. We used haematoxylin and eosin (H&E), TUNEL, Hoechst 33,258, immunofluorescence assay and western blot methods to comprehensively assess the protective mechanism and therapeutic effect of DHM on liver damage induced by APAP (250 mg/kg) in mice. Results: APAP (250 mg/kg) could increase the expression of alanine aminotransferase (ALT), aspartate aminotransferase (AST), tumor necrosis factor-α (TNF-α), and interleukin 1β (IL-1β) and cause 4-hydroxy-2-nonenal (4-HNE) and Cytochrome P450 2E1 (CYP2E1) overexpression and stress response in the PI3K/AKT pathway. DHM was also detected in the serum of mice about five minutes after administration. DHM pretreatment could reverse GSH depletion and CYP2E1 overexpression, reduce the expression of ALT, AST, malondialdehyde, 4-HNE, TNF-α, and IL-1β, meanwhile it could reverse the abnormal expression of PI3K/AKT signaling pathway-related proteins which were induced by APAP. DHM pretreatment significantly reduced APAP-induced liver tissue apoptosis, necrosis, and inflammatory infiltration. Conclusion: DHM had a hepatoprotective effect on hepatotoxicity induced by APAP, which was shown by inhibiting oxidative stress and inflammatory responses, and reducing hepatocyte apoptosis by activating the PI3K/AKT signaling pathway.

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.

Emodin Alleviates High-Glucose-Induced Pancreatic β-Cell Pyroptosis by Inhibiting NLRP3/GSDMD Signaling

Diabetes mellitus (DM) is a chronic noninfectious disease that is mainly featured by pancreatic β-cell (β-cell) dysfunction and impaired glucose homeostasis. Currently, the pathogenesis of dysfunction of the β-cells in DM remains unclear, and therapeutic approaches to it are limited. Emodin (EMD), a natural anthraquinone derivative, has been preliminarily proven to show antidiabetic effects. However, the underlying mechanism of EMD on β-cells still needs to be elucidated. In this study, we investigated the protective effects of EMD on the high glucose (50 mM)-induced INS-1 cell line and the underlying mechanism. INS-1 cells were treated with EMD (5, 10, and 20 μM) when exposed to high glucose. The effects of EMD were examined by using the inverted phase-contrast microscope, qRT-PCR, ELISA, and western blot. The results showed that EMD could alleviate cellular morphological changes, suppress IL-1β and LDH release, and promote insulin secretion in high-glucose-induced INS-1 cells. Furthermore, EMD inhibits NOD-like receptor protein 3 (NLRP3) activation and gasdermin D (GSDMD) cleavage to alleviate pyroptosis induced by high glucose. Overexpression of NLRP3 reversed the above changes caused by EMD. Collectively, our findings suggest that EMD attenuates high-glucose-induced β-cell pyroptosis by inhibiting NLRP3/GSDMD signaling.