The role of inflammasome activation in Triptolide-induced acute liver toxicity

Podophyllotoxin mediates hepatic toxicity via the C5a/C5aR/ROS/NLRP3 and cGMP/PKG/mTOR axis in rats based on toxicological evidence chain (TEC) concept by phosphoproteomic analysis

BACKGROUND

Podophyllotoxin (PPT), a highly active compound extracted from the rhizome of Dysosma versipellis (DV), has been used as an effective anti-cancer drug clinically since the 1950s. It possesses various biological activities, including antiviral and antitumor effects. However, its clinical application is severely limited due to its hepatotoxicity, and the underlying mechanisms remain unclear. This study aims to elucidate the mechanisms of PPT-induced hepatotoxicity using tandem quality tag (TMT) based quantitative proteomics and phosphoproteomics, providing potential targets and directions for developing new therapeutic strategies to facilitate the safe and rational use of podophyllotoxin in clinical settings.

METHODS

We employed a comprehensive assessment of PPT-induced hepatotoxicity based on the Toxicology Evidence Chain (TEC) concept, originally proposed by our research group in 2018. This approach involves a tiered search for evidence of Harmful Ingredients Evidence (HIE), Injury Phenotype Evidence (IPE), Adverse Outcomes Evidence (AOE), and Toxic Events Evidence (TEE) during the development of PPT-induced hepatotoxicity, thereby constructing a guiding toxicology evidence chain. Sprague-Dawley (SD) rats were administered 20 mg/kg PPT for 4 consecutive days (HIE). Indicators such as hepatic function, oxidative stress, inflammatory factors, as well as the histopathology of liver tissue were evaluated to assess liver damage and synthetic function (AOE). Proteomics and phosphoproteomics were conducted to systematically assess PPT-induced hepatotoxicity at the level of modified proteins and verify the molecular mechanisms of key molecular pathways (TEE1). Furthermore, in vitro THLE-2 cell models were used in conjunction with CCK8, immunofluorescence, and ELISA assays to validate cytotoxicity and its underlying mechanisms (TEE2).

RESULTS

Our results showed that after 4 days of PPT administration at 20 mg/kg (HIE), serum levels of AST/ALT, TBA, TP, and ALB in SD rats were significantly increased (P < 0.05), indicating severe liver damage. SOD and T-AOC levels were significantly decreased (P < 0.05), suggesting an oxidative stress state. TNF-α levels were significantly elevated, while IL-10 and IL-3 levels were significantly reduced (P < 0.05), indicating strong activation of the inflammatory response in the liver. Histopathological examination revealed liver sinusoidal congestion in the liver tissue (AOE). Omics analysis revealed that hepatotoxicity primarily affected the complement-pyroptosis and cGMP-PKG-autophagy pathways. Western blot (WB) and RT-qPCR results showed significant upregulation of complement-pyroptosis pathway proteins (C5a, C5aR, NLRP3) and cGMP-PKG-autophagy pathway proteins (PKG, mTOR) in the PPT group (P < 0.05) (TEE1). In vitro cell experiments showed that PPT significantly reduced cell viability (P < 0.05) and increased the expression of proteins associated with pyroptosis and autophagy pathways, including ROS, NLRP3, PKG, and mTOR (P < 0.05) (TEE2).

CONCLUSION

PPT activates the complement system through the C5a/C5aR/ROS/NLRP3 pathway and induces the formation of inflammasomes, promoting pyroptosis. Simultaneously, PPT activates the cGMP-PKG pathway, inhibiting autophagy and further accelerating pyroptosis, ultimately leading to hepatotoxicity. In conclusion, this study comprehensively revealed the underlying mechanisms of PPT-induced hepatotoxicity using the TEC concept. This approach transforms fragmented toxicity indicators into systematic evidence of toxicity, presenting a hierarchical progression of toxicity evidence and avoiding data accumulation in natural drug toxicology. Our findings represent a significant breakthrough in the elucidation of the mechanisms of hepatotoxicity induced by podophyllotoxin.

Triptolide exposure triggers ovarian inflammation by activating cGAS-STING pathway and decrease oocyte quality in mouse

Triptolide (TPL), a prominent bioactive constituent derived from the Chinese herb Tripterygium wilfordii, exhibits diverse pharmacological effects such as anti-tumor and anti-immune properties. Despite its extensive clinical application for the treatment of arthritis and immune disorders, TPL has been associated with multiorgan toxicity, including adverse effects on the female reproductive system. However, the precise mechanisms underlying TPL-induced ovarian damage remain poorly understood. In this study, employing a mouse toxicological model, exposure to TPL was observed to result in decreased ovarian coefficient and fertility. Subsequent research demonstrated TPL exposure affected mitochondrial function, increased mitochondrial outer membrane permeability, resulted in mtDNA releasing into the cytoplasm. These events subsequently activated cGAS-STING pathway, leading to ovarian inflammation. Furthermore, TPL exposure has been found to disrupt the meiotic maturation of oocytes, which is mechanistically associated with suboptimal morphology of spindle and microtubule organizing centers (MTOCs). This association has been further confirmed through the use of reduced representation bisulfite sequencing (RRBS). In conclusion, our study demonstrates that TPL exposure can hinder follicular development, resulting in ovarian inflammation and reduced oocyte quality.

Triptolide-induced acute liver injury and its mechanism with estradiol in regulating macrophage-mediated inflammation and hepatocyte function

Triptolide (TP), a diterpene from Tripterygium wilfordii, exhibits potent anti-inflammatory, immunomodulatory, and antitumor properties but is limited by severe hepatotoxicity. This study investigates sex differences in TP-induced liver injury and the protective role of estradiol (E2) in modulating macrophage-mediated inflammation and hepatocyte function. An acute liver injury model was established in male and female Balb/c mice using intraperitoneal TP injection. Liver function tests, histological analyses, and immunohistochemical staining were performed. THP-1 macrophage and various liver cell lines were used to study the effects of TP and E2 in vitro. Virtual screening, molecular docking, luciferase assays, and qPCR were employed to identify potential targets and elucidate underlying mechanisms. TP caused more severe liver injury in female mice, evidenced by increased liver indices, aspartate aminotransferase (AST) levels, and extensive hepatocyte damage. TP promoted M1 macrophage polarization, enhancing inflammation, particularly in female mice. E2 mitigated TP-induced inflammatory responses by downregulating pro-inflammatory cytokines and macrophage activation markers. Molecular docking and functional assays identified Nuclear receptor subfamily 1 group I member 2 (NR1I2) as a key target mediating the protective effects of E2. The study highlights significant sex differences in TP-induced hepatotoxicity, with females being more susceptible. E2 exerts protective effects against TP-induced liver injury by modulating immune responses, presenting a potential therapeutic approach to mitigate drug-induced liver injury (DILI). Further research on NR1I2 could lead to targeted therapies for reducing drug-induced liver damage.

Insights gained into the injury mechanism of drug and herb induced liver injury in the hepatic microenvironment

Drug-Induced Liver Injury (DILI) and herb Induced Liver Injury (HILI) continues to pose a substantial challenge in both clinical practice and drug development, representing a grave threat to patient well-being. This comprehensive review introduces a novel perspective on DILI and HILI by thoroughly exploring the intricate microenvironment of the liver. The dynamic interplay among hepatocytes, sinusoidal endothelial cells, Kupffer cells, hepatic stellate cells, cholangiocytes, and the intricate vascular network assumes a central role in drug metabolism and detoxification. Significantly, this microenvironment is emerging as a critical determinant of susceptibility to DILI and HILI. The review delves into the multifaceted interactions within the liver microenvironment, providing valuable insights into the complex mechanisms that underlie DILI and HILI. Furthermore, we discuss potential strategies for mitigating drug-induced liver injury by targeting these influential factors, emphasizing their clinical relevance. By highlighting recent advances and future prospects, our aim is to shed light on the promising avenue of leveraging the liver microenvironment for the prevention and mitigation of DILI and HILI. This deeper understanding is crucial for advancing clinical practices and ensuring patient safety in the realm of DILI and HILI.

Celastrol induces premature ovarian insufficiency by inducing apoptosis in granulosa cells

Celastrol, a natural compound purified from the Chinese herb Tripterygium wilfordii Hook. f., has excellent pharmacological activity for the treatment of various diseases. Assessing the safety of its use is essential for its development into a clinical medicine. However, research assessing its toxicity on the female reproductive system has never been reported. In this study, the ovarian toxicity of celastrol and its underlying mechanism were investigated. We found that celastrol induced premature ovarian insufficiency and apoptosis in granulosa cells. Activity-based protein profiling results showed that high mobility group box 1 was a candidate target protein of celastrol. Celastrol directly bound to Cys106 of high mobility group box 1. Knocking down high mobility group box 1 induced apoptosis of granulosa cells, while overexpression of this gene reversed celastrol-induced apoptosis. Celastrol treatment upregulated p21 transcription, but overexpression of high mobility group box 1 reversed this upregulation. Thus, Celastrol induces premature ovarian insufficiency and apoptosis in granulosa cells by directly binding to high mobility group box 1 and interfering with its biological function to regulate p21 transcription. This study provides valuable information for assessing the safety of the clinical application of celastrol on female patients.

Recent advances in the pharmacological applications and liver toxicity of triptolide

Triptolide is a predominant active component of Triptergium wilfordii Hook. F, which has been used for the treatment of cancers and autoimmune diseases such as rheumatoid arthritis, systemic lupus erythematosus and diabetic nephropathy. Therefore, triptolide and its derivates are considered to have promising prospects for development into drugs. However, the clinical application of triptolide is limited due to various organ toxicities, especially liver toxicity. The potential mechanism of triptolide-induced hepatotoxicity has attracted increasing attention. Over the past five years, studies have revealed that triptolide-induced liver toxicity is involved in metabolic imbalance, oxidative stress, inflammations, autophagy, apoptosis, and the regulation of cytochrome P450 (CYP450) enzymes, gut microbiota and immune cells. In this review, we summarize the pharmacological applications and hepatotoxicity mechanism of triptolide, which will provide solid theoretical evidence for further research of triptolide.

New Insights into Herb-Induced Liver Injury

Significance: Herbs are widely used worldwide. However, inappropriate use of some of the herbs can lead to herb-induced liver injury (HILI). Intriguingly, HILI incidents are on the rise, and our understanding of the underlying etiologies is in progress, and hence, an update on the current status of incidents as well as our understanding on the etiologies of HILI is appropriate. Recent Advances: HILI reports due to the use of some herbs that are traditionally considered to be safe are also on the rise. Furthermore, HILI due to the use of certain herbs in combination with other herbs (herb-herb interaction [HHI]) or non-herb components (herb-drug interaction [HDI]) has also been reported, suggesting a potentially important new type of inappropriate use of herbs. Critical Issues: Updated overviews focus on the epidemiology, etiology, phenotypes, and risk factors of HILI, as well as HDI and HHI, and analysis on several types of newly reported "toxic" effects of herbs based on types of hepatotoxicity and the HILI mechanisms. Future Directions: HILI will continue to be a significant public health challenge in the near future. In the light of the lack of broadly available guidelines and regulations for proper and safe uses of herbs worldwide, raising the public awareness of HILI will remain one of the most effective measures. In particular, it should include a better understanding of the contributing factors; a more detail subclassification and description of HILI, better characterization of the components/substances that could induce HILI; and development of HILI diagnosis based on the Roussel Uclaf Causality Assessment Method (RUCAM). Antioxid. Redox Signal. 38, 1138-1149.

Toxic effects of Tripterygium glycoside tablets on the reproductive system of male rats by metabolomics, cytotoxicity, and molecular docking

BACKGROUND

Tripterygium glycoside tablets (TGT) is the most common preparation from Tripterygium wilfordii Hook F, which is widely used in clinical for treating rheumatoid arthritis (RA) and other autoimmune diseases. However, its serious reproductive toxicity limits its application.

PURPOSE

This study aimed to elucidate the toxic effects of TGT on the reproductive system of male RA rats and its potential toxic components and mechanism.

METHODS

Collagen-induced arthritis (CIA) rat model was established, and TGT suspension was given at low, medium, and high doses. Gonadal index, pathological changes, and the number of spermatogenic cells were used to evaluate the toxic effects of TGT on the reproductive system. Non-targeted metabolomics of testicular tissue was conducted by UHPLC-QTOF/MS. Combined with network toxicology, the key targets of TGT-induced reproductive toxicity were screened and RT-qPCR was used to validation. In vitro toxicity of 19 components of TGT was evaluated using TM3 and TM4 cell lines. Molecular docking was used to predict the interaction between toxic components and key targets.

RESULTS

TGT reduced testicular and epididymis weight. Pathology analysis showed a lot of deformed and atrophic spermatogenic tubules. The number of spermatogenic cells decreased significantly (P<0.0001). A total of 58 different metabolites including platelet-activating factor (PAF), lysophosphatidylcholine (Lyso PC), phosphatidylinositol (PI), glutathione (GSH), and adenosine monophosphate (AMP) were identified by testicular metabolomics. Glycerophospholipid metabolism, ether lipid metabolism, and glutathione metabolism were key pathways responsible for the reproductive toxicity of TGT. Ten key reproductive toxicity targets were screened by network toxicology. The cytotoxicity test showed that triptolide, triptonide, celastrol, and demethylzeylasteral could significantly reduce the viability of TM3 and TM4 cells. Alkaloids had no apparent toxic effects. Molecular docking showed that the four toxic components had a good affinity with 10 key targets. All binding energies were less than -7 kcal/mol. The RT-qPCR results showed the Cyp19a1 level was significantly up-regulated. Pik3ca and Pik3cg levels were significantly down-regulated.

CONCLUSION

Through testicular metabolomics, we found that TGT may cause reproductive toxicity through CYP19A1, PIK3CA, and PIK3CG three target, which was preliminarily revealed. This study laid the foundation for elucidating the toxicity mechanism of TGT and evaluating its safety and quality.

Obeticholic acid improved triptolide/lipopolysaccharide-induced hepatotoxicity by inhibiting caspase-11-GSDMD pyroptosis pathway

This study was designed to investigate the potential role of farnesoid X receptor (FXR) in abnormal bile acid metabolism and pyroptosis during the pathogenesis of triptolide (TP)/lipopolysaccharide (LPS)-induced hepatotoxicity. Moreover, the protective effect of obeticholic acid (OCA) was explored under this condition. In vivo, female C57BL/6 mice were administrated with OCA (40 mg/kg bw, intragastrical injection) before (500 μg/kg bw, intragastrical injection)/LPS (0.1 mg/kg bw, intraperitoneal injection) administration. In vitro, AML12 cells were treated with TP (50 nM) and TNF-α (50 ng/ml) to induce hepatotoxicity; GW4064 (5 μM) and cholestyramine (CHO) (0.1 mg/ml and 0.05 mg/ml) were introduced to explain the role of FXR/total bile acid (TBA) in it. Serum TBA level was significantly elevated, which was induced by FXR suppression. And both GW4064 and CHO intervention presented remarkable protective effects against TP/TNF-α-induced NLRP3 upregulation and pyroptosis pathway activation. Pre-administration of FXR agonist OCA successfully attenuated TP/LPS-induced severe liver injury by reducing serum bile acids accumulation and inhibiting the activation of caspase-11-GSDMD (gasdermin D) pyroptosis pathway. We have drawn conclusions that TP aggravated liver hypersensitivity to LPS and inhibited FXR-SHP (small heterodimer partner) axis, which was served as endogenous signals to activate caspase-11-GSDMD-mediated pyroptosis contributing to liver injury. OCA alleviated TP/LPS-induced liver injury accompanied by inhibiting caspase-11-GSDMD-mediated pyroptosis pathway and decreased serum TBA level. The results indicated that FXR might be an attractive therapeutic target for TP/LPS-induced hepatotoxicity, providing an effective strategy for drug-induced liver injury.

The mechanism of NLRP3 inflammasome activation and its pharmacological inhibitors

NLRP3 (NOD-, LRR-, and pyrin domain-containing protein 3) is a cytosolic pattern recognition receptor (PRR) that recognizes multiple pathogen-associated molecular patterns (PAMPs) and damage-associated molecular patterns (DAMPs). Once activated, NLRP3 initiates the inflammasome assembly together with the adaptor ASC and the effector caspase-1, leading to caspase-1 activation and subsequent cleavage of IL-1β and IL-18. Aberrant NLRP3 inflammasome activation is linked with the pathogenesis of multiple inflammatory diseases, such as cryopyrin-associated periodic syndromes, type 2 diabetes, non-alcoholic steatohepatitis, gout, and neurodegenerative diseases. Thus, NLRP3 is an important therapeutic target, and researchers are putting a lot of effort into developing its inhibitors. The review summarizes the latest advances in the mechanism of NLRP3 inflammasome activation and its pharmacological inhibitors.

Triptolide leads to hepatic intolerance to exogenous lipopolysaccharide and natural-killer-cell mediated hepatocellular damage by inhibiting MHC class I molecules

BACKGROUND

Tripterygium wilfordii Hook. F (TWHF) is used as a traditional Chinese medicine, called thunder god vine, based on its efficacy for treating inflammatory diseases. However, its hepatotoxicity has limited its clinical application. Triptolide (TP) is the major active and toxic component of TWHF. Previous studies reported that a toxic pretreatment dose of TP leads to hepatic intolerance to exogenous lipopolysaccharide (LPS) stimulation, and to acute liver failure, in mice, but the immune mechanisms of TP-sensitised hepatocytes and the TP-induced excessive immune response to LPS stimulation are unknown.

PURPOSE

To identify both the key immune cell population and mechanism involved in TP-induced hepatic intolerance of exogenous LPS.

STUDY DESIGN

In vitro and in vivo experiments were conducted to investigate the inhibitory signal of natural killer (NK) cells maintained in hepatocytes, and the ability of TP to impair that signal.

METHODS

Flow cytometry was performed to determine NK cell activity and hepatocyte histocompatibility complex (MHC) class I molecules expression; the severity of liver injury was determined based on blood chemistry values, and drug- or cell-mediated hepatocellular damage, by measuring lactate dehydrogenase (LDH) release. In vivo H-2K^b transduction was carried out using an adeno-associated viral vector.

RESULTS

Interferon (IFN)-γ-mediated necroptosis occurred in C57BL/6N mice treated with 500 μg TP/kg and 0.1 mg LPS/kg to induce fulminant hepatitis. Primary hepatocytes pretreated with TP were more prone to necroptosis when exposed to recombinant murine IFN-γ. In mice administered TP and LPS, the intracellular IFN-γ levels of NK cells increased significantly. Subsequent study confirmed that NK cells were activated and resulted in potent hepatocellular toxicity. In vivo and in vitro TP administration significantly inhibited MHC class I molecules in murine hepatocytes. An in vitro analysis demonstrated the susceptibility of TP-pretreated hepatocytes to NK-cell-mediated cytotoxicity, an effect that was significantly attenuated by the induction of hepatocyte MHC-I molecules by IFN-α. In vivo induction or overexpression of hepatocyte MHC-I also protected mouse liver against TP and LPS-induced injury.

CONCLUSION

The TP-induced inhibition of hepatocyte MHC-I molecules expression leads to hepatic intolerance to exogenous LPS and NK-cell mediated cytotoxicity against self-hepatocytes. These findings shed light on the toxicity of traditional Chinese medicines administered for their immunomodulatory effects.

Macrophage malfunction in Triptolide-induced indirect hepatotoxicity

Background and Objective: Indirect hepatotoxicity is a new type of drug-induced hepatotoxicity in which the character of a drug that may induce its occurrence and the underlying mechanism remains elusive. Previously, we proved that Triptolide (TP) induced indirect hepatotoxicity upon LPS stimulation resulting from the deficiency of cytoprotective protein of hepatocyte. However, whether immune cells participated in TP-induced indirect hepatotoxicity and the way immune cells change the liver hypersensitivity to LPS still need to be deeply investigated. In this study, we tried to explore whether and how macrophages are involved in TP-induced indirect hepatotoxicity.

Method: Firstly, TP (500 μg/kg) and LPS (0.1 mg/kg) were administrated into female C57BL/6 mice as previously reported. Serum biochemical indicators, morphological changes, hepatic macrophage markers, as well as macrophage M1/M2 markers were detected. Secondly, macrophage scavenger clodronate liposomes were injected to prove whether macrophages participated in TP-induced indirect hepatotoxicity. Also, the ability of macrophages to secrete inflammatory factors and macrophage phagocytosis were detected. Lastly, reverse docking was used to find the target of TP on macrophage and the possible target was verified in vivo and in RAW264.7 cells.

Results: TP pretreatment increased the liver hypersensitization to LPS accompanied by the recruitment of macrophages to the liver and promoted the transformation of macrophages to M1 type. Depletion of hepatic macrophages almost completely alleviated the liver injury induced by TP/LPS. TP pretreatment increased the secretion of pro-inflammatory factors and weakened the phagocytic function of macrophages upon LPS exposure. Reverse docking results revealed that MerTK might be the real target of TP.

Conclusion: TP disrupts inflammatory cytokines profile and phagocytic function of hepatic macrophages, resulting in the production of massive inflammatory factors and the accumulation of endotoxin in the liver, ultimately leading to the indirect hepatotoxicity of TP. MerTK might be the target of TP on the macrophage, while the binding of TP to MerTK should be investigated in vivo and in vitro.

Th17/Treg imbalance mediates hepatic intolerance to exogenous lipopolysaccharide and exacerbates liver injury in triptolide induced excessive immune response

ETHNOPHARMACOLOGICAL RELEVANCE

Triptolide (TP) is a major active ingredient and toxic component of Tripterygium wilfordii Hook F (TWHF), which exhibits multiple activities and remarkable hepatotoxicity, the latter of which limits its clinical application due to the risk of liver injury. Previous research has revealed the hepatotoxicity of TP resulting in liver hypersensitivity upon lipopolysaccharide (LPS) stimulation. However, existing research has not elucidated the potential immune mechanism such as Th17/Treg imbalance in TP-induced hepatic excessive immune response to exogenous LPS.

AIM OF THE STUDY

To investigate the role of Th17/Treg imbalance in TP-induced hepatic excessive immune response to exogenous LPS.

MATERIALS AND METHODS

Mice were administered with TP, LPS, neutralization antibody and small molecule inhibitor respectively. Serum transaminase level was measured to determine the severity of liver injury. Frequencies of liver Th17 and Treg cells were analyzed by flow cytometry. Serum cytokine levels were performed by ELSIA, and mRNA levels of liver cytokine were performed by qPCR. The status of neutrophil infiltration was performed by myeloperoxidase (MPO) IHC measurement. Morphological observation of liver was performed by hematoxylin and eosin (H&E) staining.

RESULTS

Mice given a single intragastric dose of TP (500 μg/kg) developed lethal fulminant hepatitis following intraperitoneal injection of LPS (0.1 mg/kg), characterized by low survival rate, severe liver injury, high levels of inflammation and neutrophil infiltration. Hepatic Th17/Treg imbalance emerged together with liver injury in these mice. Neutralization of IL-17A attenuated the liver injury and ameliorated the neutrophil infiltration. The TP-induced alteration of hepatic Th17/Treg balance was closely related to the outcome of immune-mediated acute liver injury triggered by LPS. Pretreatment with the STAT3 inhibitor AG490 effectively restored Th17/Treg balance, significantly reducing the production of IL-17A and finally attenuating the degree of liver injury.

CONCLUSION

Hepatic Th17/Treg imbalance not only exacerbates TP- and LPS-induced liver injury, but also serves as an indispensable part in the mechanisms of TP-induced hepatic intolerance to exogenous endotoxin.

The molecular pathogenesis of triptolide-induced hepatotoxicity

Triptolide (TP) is the major pharmacologically active ingredient and toxic component of Tripterygium wilfordii Hook. f. However, its clinical potential is limited by a narrow therapeutic window and multiple organ toxicity, especially hepatotoxicity. Furthermore, TP-induced hepatotoxicity shows significant inter-individual variability. Over the past few decades, research has been devoted to the study of TP-induced hepatotoxicity and its mechanism. In this review, we summarized the mechanism of TP-induced hepatotoxicity. Studies have demonstrated that TP-induced hepatotoxicity is associated with CYP450s, P-glycoprotein (P-gp), oxidative stress, excessive autophagy, apoptosis, metabolic disorders, immunity, and the gut microbiota. These new findings provide a comprehensive understanding of TP-induced hepatotoxicity and detoxification.

Antibiotic pretreatment promotes orally-administered triptolide absorption and aggravates hepatotoxicity and intestinal injury in mice

ETHNOPHARMACOLOGICAL RELEVANCE

Triptolide (TP) exhibits extensive pharmacological activity, but its hepatotoxicity and intestinal injury are significant and limit its clinical use.

AIM OF THE STUDY

To investigate the effect of gut microbiota disturbance after antibiotic pretreatment on TP-induced hepatotoxicity, intestinal injury and their mechanism.

MATERIALS AND METHODS

We compared the characteristics of TP-induced hepatotoxicity and intestinal injury in mice with or without antibiotic pretreatment. The levels of cytokines in the serum, immunohistochemistry, and the pharmacokinetics of TP were determined.

RESULT

Antibiotic pretreatment aggravates TP-induced hepatotoxicity and ileum/colon injury. TP induces hepatotoxicity in a dose-dependent manner after antibiotic pretreatment. Serum IL-1β and IL-6 levels were increased in mice given oral TP after antibiotic pretreatment. TP can increase the expression of NLRP3 inflammasome in hepatocytes, and Oral TP after antibiotic pretreatment can significantly enhance its expression, but NLRP3 inflammasome no significant change in colon and ileum. The pharmacokinetic characteristics of TP are altered significantly by antibiotic pretreatment, as shown by a 145.87% increase in C_max, a 155.11% increase in AUC_0-t, a 155.1% increase in relative bioavailability, and a 15.44% delay in MRT. Moreover, TP causes hepatotoxicity in a time-dependent manner.

CONCLUSIONS

Antibiotic pretreatment aggravates triptolide-induced hepatotoxicity and intestinal injury through elevated inflammatory response and promoted triptolide absorption.

The key role of organic anion transporter 3 in the drug-drug interaction between tranilast and methotrexate

Tranilast, N-(3',4'-dimethoxycinnamoyl)-anthranilic acid, is an anti-allergic drug and is considered for use in the treatment of rheumatoid arthritis. Methotrexate, an antimetabolite and folate antagonist to treat some cancers, is also a first-line drug for RA. The aim of this study was to understand whether tranilast could inhibit renal uptake transporters (Oat1, Oat3, and Oct2) and whether MTX combined with TL would have drug-drug interactions. The results of kidney slices and HEK293T-OAT3 cell uptake experiments showed that TL (10 μM) could inhibit the uptake of penicillin G and MTX, which are substrates of OAT3. When TL (10 mg/kg) was combined with MTX (5 mg/kg), the area under the curve and peak concentration of MTX increased by 46.46% and 113.51%, respectively, while the pharmacokinetic process of tranilast (10 mg/kg) was not changed by methotrexate (5 mg/kg). TL could increase plasma exposure of MTX by inhibiting Oat3 in vitro and in vivo.

Tripterygium hypoglaucum (Lévl.) Hutch and Its Main Bioactive Components: Recent Advances in Pharmacological Activity, Pharmacokinetics and Potential Toxicity

Tripterygium hypoglaucum (Lévl.) Hutch (THH) is believed to play an important role in health care and disease treatment according to traditional Chinese medicine. Moreover, it is also the representative of medicine with both significant efficacy and potential toxicity. This characteristic causes THH hard for embracing and fearing. In order to verify its prospect for clinic, a wide variety of studies were carried out in the most recent years. However, there has not been any review about THH yet. Therefore, this review summarized its characteristic of components, pharmacological effect, pharmacokinetics and toxicity to comprehensively shed light on the potential clinical application. More than 120 secondary metabolites including terpenoids, alkaloids, glycosides, sugars, organic acids, oleanolic acid, polysaccharides and other components were found in THH based on phytochemical research. All these components might be the pharmacological bases for immunosuppression, anti-inflammatory and anti-tumour effect. In addition, recent studies found that THH and its bioactive compounds also demonstrated remarkable effect on obesity, insulin resistance, fertility and infection of virus. The main mechanism seemed to be closely related to regulation the balance of immune, inflammation, apoptosis and so on in various disease. Furthermore, the study of pharmacokinetics revealed quick elimination of the main component triptolide. The feature of celastrol was also investigated by several models. Finally, the side effect of THH was thought to be the key for its limitation in clinical application. A series of reports indicated that multiple organs or systems including liver, kidney and genital system were involved in the toxicity. Its potential serious problem in liver was paid specific attention in recent years. In summary, considering the significant effect and potential toxicity of THH as well as its components, the combined medication to inhibit the toxicity, maintain effect might be a promising method for clinical conversion. Modern advanced technology such as structure optimization might be another way to reach the efficacy and safety. Thus, THH is still a crucial plant which remains for further investigation.

Targeted therapy of rheumatoid arthritis via macrophage repolarization

The polarization of macrophages plays a critical role in the physiological and pathological progression of rheumatoid arthritis (RA). Activated M1 macrophages overexpress folate receptors in arthritic joints. Hence, we developed folic acid (FA)-modified liposomes (FA-Lips) to encapsulate triptolide (TP) (FA-Lips/TP) for the targeted therapy of RA. FA-Lips exhibited significantly higher internalization efficiency in lipopolysaccharide (LPS)-stimulated RAW 264.7 cells than liposomes (Lips) in the absence of folate. Next, an adjuvant-induced arthritis (AIA) rat model was established to explore the biodistribution profiles of FA-Lips which showed markedly selective accumulation in inflammatory paws. Moreover, FA-Lips/TP exhibited greatly improved therapeutic efficacy and low toxicity in AIA rats by targeting M1 macrophages and repolarizing macrophages from M1 to M2 subtypes. Overall, a safe FA-modified liposomal delivery system encapsulating TP was shown to achieve inflammation-targeted therapy against RA via macrophage repolarization.

Therapeutic potential of triptolide in autoimmune diseases and strategies to reduce its toxicity

With the increasing epidemiology of autoimmune disease worldwide, there is an urgent need for effective drugs with low cost in clinical treatment. Triptolide, the most potent bioactive compound from traditional Chinese herb Tripterygium Wilfordii Hook F, possesses immunosuppression and anti-inflammatory activity. It is a potential drug for the treatment of various autoimmune diseases, but its clinical application is still restricted due to severe toxicity. In this review, the pharmacodynamic effects and pharmacological mechanisms of triptolide in autoimmune diseases are summarized. Triptolide exerts therapeutic effect by regulating the function of immune cells and the expression of cytokines through inflammatory signaling pathways, as well as maintaining redox balance and gut microbiota homeostasis. Meanwhile, the research progress on toxicity of triptolide to liver, kidney, reproductive system, heart, spleen, lung and gastrointestinal tract has been systematically reviewed. In vivo experiments on different animals and clinical trials demonstrate the dose- and time- dependent toxicity of triptolide through different administration routes. Furthermore, we focus on the strategies to reduce toxicity of triptolide, including chemical structural modification, novel drug delivery systems, and combination pharmacotherapy. This review aims to reveal the potential therapeutic prospect and limitations of triptolide in treating autoimmune diseases, thus providing guiding suggestions for further study and promoting its clinical translation.

The Immunological Mechanisms and Immune-Based Biomarkers of Drug-Induced Liver Injury

Drug-induced liver injury (DILI) has become one of the major challenges of drug safety all over the word. So far, about 1,100 commonly used drugs including the medications used regularly, herbal and/or dietary supplements, have been reported to induce liver injury. Moreover, DILI is the main cause of the interruption of new drugs development and drugs withdrawn from the pharmaceutical market. Acute DILI may evolve into chronic DILI or even worse, commonly lead to life-threatening acute liver failure in Western countries. It is generally considered to have a close relationship to genetic factors, environmental risk factors, and host immunity, through the drug itself or its metabolites, leading to a series of cellular events, such as haptenization and immune response activation. Despite many researches on DILI, the specific biomarkers about it are not applicable to clinical diagnosis, which still relies on the exclusion of other causes of liver disease in clinical practice as before. Additionally, circumstantial evidence has suggested that DILI is mediated by the immune system. Here, we review the underlying mechanisms of the immune response to DILI and provide guidance for the future development of biomarkers for the early detection, prediction, and diagnosis of DILI.

Palliative effects of metformin on testicular damage induced by triptolide in male rats

As a widely existing traditional Chinese medicine component, TP (triptolide) has serious reproductive toxicity which causes severe damage to the reproductive system and limits its application prospect. TP and MET (metformin) have shown great potential in combined with each other in anticancer and anti-inflammatory. Whether metformin can resist the reproductive toxicity caused by triptolide, the effects of MET on TP-induced reproductive capacity has not been reported. In this study, metformin was used to investigate the therapeutic effect on reproductive toxicity induced by TP in rat. The results showed that metformin had significant therapeutic effects on oxidative stress damage, destruction of the blood-testosterone barrier and apoptosis. And it proved that its therapeutic effect is mainly to restore the structural and functional stability of testis through antioxidant stress. It will provide guidance for the treatment of reproductive toxicity caused by TP and the adjuvant detoxification of TP application.

Bavachin enhances NLRP3 inflammasome activation induced by ATP or nigericin and causes idiosyncratic hepatotoxicity

Psoraleae Fructus (PF) is a well-known traditional herbal medicine in China, and it is widely used for osteoporosis, vitiligo, and other diseases in clinical settings. However, liver injury caused by PF and its preparations has been frequently reported in recent years. Our previous studies have demonstrated that PF could cause idiosyncratic drug-induced liver injury (IDILI), but the mechanism underlying its hepatotoxicity remains unclear. This paper reports that bavachin isolated from PF enhances the specific stimuli-induced activation of the NLRP3 inflammasome and leads to hepatotoxicity. Bavachin boosts the secretion of IL-1β and caspase-1 caused by ATP or nigericin but not those induced by poly(I:C), monosodium urate crystal, or intracellular lipopolysaccharide. Bavachin does not affect AIM2 or NLRC4 inflammasome activation. Mechanistically, bavachin specifically increases the production of nigericin-induced mitochondrial reactive oxygen species among the most important upstream events in the activation of the NLRP3 inflammasome. Bavachin increases the levels of aspartate transaminase and alanine aminotransferase in serum and hepatocyte injury accompanied by the secretion of IL-1β via a mouse model of lipopolysaccharide-mediated susceptibility to IDILI. These results suggest that bavachin specifically enhances the ATP- or nigericin-induced activation of the NLRP3 inflammasome. Bavachin also potentially contributes to PF-induced idiosyncratic hepatotoxicity. Moreover, bavachin and PF should be evaded among patients with diseases linked to the ATP- or nigericin-mediated activation of the NLRP3 inflammasome, which may be a dangerous factor for liver injury.

NLRP3 Inflammasome: A Promising Therapeutic Target for Drug-Induced Toxicity

Drug-induced toxicity, which impairs human organ function, is a serious problem during drug development that hinders the clinical use of many marketed drugs, and the underlying mechanisms are complicated. As a sensor of infections and external stimuli, nucleotide-binding oligomerization domain (NOD)-like receptor family pyrin domain containing 3 (NLRP3) inflammasome plays a key role in the pathological process of various diseases. In this review, we specifically focused on the role of NLRP3 inflammasome in drug-induced diverse organ toxicities, especially the hepatotoxicity, nephrotoxicity, and cardiotoxicity. NLRP3 inflammasome is involved in the initiation and deterioration of drug-induced toxicity through multiple signaling pathways. Therapeutic strategies via inhibiting NLRP3 inflammasome for drug-induced toxicity have made significant progress, especially in the protective effects of the phytochemicals. Growing evidence collected in this review indicates that NLRP3 is a promising therapeutic target for drug-induced toxicity.

Metabolic profiling of 19 amino acids in triptolide-induced liver injured rats by gas chromatography-triple quadrupole mass spectrometry

The liver is an important organ for amino acid metabolism, and its damage can be reflected in the changes of amino acid level in the body. Triptolide (TP) has broad anti-inflammatory and anti-tumor activities, but its clinical application is limited due to hepatotoxicity. In this work, a simple, accurate and sensitive gas chromatography-triple quadrupole mass spectrometry (GC-QqQ-MS/MS) method was developed and validated for evaluating the serum levels of amino acids from control and TP-induced liver injured rats, and chemometric analysis was employed for amino acid metabolic profiles analysis. It was found that 11 amino acids showed significant changes after TP administration, and they were mainly involved in 5 metabolic pathways that are phenylalanine, tyrosine and tryptophan biosynthesis, alanine, aspartate and glutamate metabolism, glutamine and glutamate metabolism, phenylalanine metabolism and arginine biosynthesis. Five amino acids including tyrosine, glutamine, glutamic acid, tryptophan and alanine were identified as biomarkers of TP hepatotoxicity by further analysis. These results indicated that the novel amino acid metabolic profiling study based on the GC-QqQ-MS/MS provided not only exact concentrations of serum amino acids, but also a prospective methodology for evaluation of chemically induced liver injury.

Metabolic profiling of fatty acids in Tripterygium wilfordii multiglucoside- and triptolide-induced liver-injured rats

Tripterygium wilfordii multiglucoside (TWM) is a fat-soluble extract from a Chinese herb T. wilfordii, that’s used in treating rheumatoid arthritis, nephrotic syndrome and other skin diseases. Triptolide (TP) is a major active component in TWM. However, clinical applications of TWM are limited by its various toxicities especially hepatotoxicity. In recent studies, it has been reported that drug-induced liver injury (DILI) could induce the disorder of lipid metabolism in animals. Hence, this study focuses on the metabolic profile of fatty acids in TWM- and TP-induced liver-injured rats. In serum and liver tissue, 16 free and 16 esterified fatty acids were measured by gas chromatography coupled with mass spectrometry. Metabolic profile of serum fatty acids in rats with liver injury was identified by multivariate statistical analysis. The fatty acid levels in the serum of TWM- and TP-treated rats significantly decreased, whereas those in the liver tissue of TWM- and TP-treated rats obviously increased when compared with the vehicle-treated rats. Four free fatty acids were identified as candidate biomarkers of TWM- and TP-induced liver injury. Therefore, the targeted metabolomic method may be used as a complementary approach for DILI diagnosis in clinic.

Triptolide and atorvastatin synergistically promote hepatotoxicity in cultured hepatocytes and female Sprague-Dawley rats by inhibiting pregnane X receptor-mediated transcriptional activation of CYP3A4

Triptolide (TP), an active component of Tripterygium wilfordii Hook. F, has been widely used in China for treating autoimmune and inflammatory diseases, and has also been validated by modern science and developed as a candidate anti-cancer treatment. However, liver toxicity of TP has seriously hindered its use and development, the clinical features and primary toxicological mechanism have been unclear. Considering the major target regulation mechanism of TP is the suppression of global transcription regulated by RNAPII, which is closed related with the detoxification of drugs. This paper tries to verify the synergistic liver injury and its mechanism of TP when co-administered with CYP3A4 substrate drug. The experiments showed that TP dose-dependently blocked transcriptional activation of CYP3A4 in both hPXR and hPXR-CYP3A4 reporter cell lines, lowered the mRNA and protein expression of PXR target genes such as CYP3A1, CYP2B1, and MDR1, and inhibited the functional activity of CYP3A in a time- and concentration-dependent manner in sandwich-cultured rat hepatocytes (SCRH) and female Sprague-Dawley (f-SD) rats. Furthermore, TP combined with atorvastatin (ATR), the substrate of CYP3A4, synergistically enhanced hepatotoxicity in cultured HepG2 and SCRH cells (CI is 0.38 and 0.29, respectively), as well as in f-SD rats, with higher exposure levels of both drugs. These results clearly indicate that TP inhibits PXR-mediated transcriptional activation of CYP3A4, leading to a blockade on the detoxification of itself and ATR, thereby greatly promoting liver injury. This study may implies the key cause of TP related liver injury and provides experimental data for the rational use of TP in a clinical scenario.

Network pharmacology modeling identifies synergistic interaction of therapeutic and toxicological mechanisms for Tripterygium hypoglaucum Hutch

Background

Tripterygium hypoglaucum Hutch (THH) both has prominent efficacy and unwarranted toxicity in the treatment of autoimmune diseases. Nevertheless, its pharmacological and toxicological profiles still remain to be elucidated. In the current study, the network pharmacology approach was applied to identify synergistic interaction and mechanism of efficacy and toxicity for THH from a holistic perspective.

Methods

The compounds from THH were collected using literature retrieval and relevant databases. After the production of putative therapeutic targets for dominant diseases and harmful targets of adverse reactions (ADRs) induced by THH, the protein-protein interactions (PPIs), topological analysis and pathway enrichment were established to distinguish the hub targets and pathways. Additionally, the binding activity of candidate ingredients with core targets were revealed by molecular docking simulation.

Results

A total of eight bioactive components in THH were enrolled, and 633 targets were responsible for rheumatoid arthritis (RA), 1067 targets were corresponding to systemic lupus erythematosus (SLE), 1318 targets of ADRs were obtained. The results of enrichment analysis among THH-RA, THH-SLE and THH-ADR networks indicated that pathway in cancer, hepatitis B, rheumatoid arthritis, and PI3K-Akt signaling pathway might participate in THH for treating RA and SLE. Besides, the mechanism of ADRs that induced by THH were associated with viral carcinogenesis, p53 signaling pathway, PI3K-Akt signaling pathway, and so on. Whereas, these active ingredients of THH exerted the superior binding activities with crucial targets including STAT3, VEGFA, TP53 and MMP9 that functioned synergistically efficacy and toxicity as observed via molecular docking simulation.

Conclusion

The present research preliminarily interpreted the synergistic interaction of therapeutic and toxicological mechanisms for THH through the comprehensive analysis of relationship and binding activity between primary components and core targets, providing a feasible and promising approach to facilitate the development of toxic and irreplaceable herbs.

Regulation of the NLRP3 inflammasome with natural products against chemical-induced liver injury

The past decades have witnessed significant progress in understanding the process of sterile inflammation, which is dependent on a cytosolic complex termed the nucleotide-binding oligomerization domain (NOD)-like receptor containing pyrin domain 3 (NLRP3) inflammasome. Activation of NLRP3 inflammasome requires two steps, including the activation of Toll-like receptor (TLR) by its ligands, resulting in transcriptional procytokine and inflammasome component activation, and the assembly and activation of NLRP3 inflammasome triggered by various danger signals, leading to caspase-1 activation, which could subsequently cleave procytokines into their active forms. Metabolic disorders, ischemia and reperfusion, viral infection and chemical insults are common pathogenic factors of liver-related diseases that usually cause tissue damage and cell death, providing numerous danger signals for the activation of NLRP3 inflammasome. Currently, natural products have attracted much attention as potential agents for the prevention and treatment of liver diseases due to their multitargets and nontoxic natures. A great number of natural products have been shown to exhibit beneficial effects on liver injury induced by various chemicals through regulating NLRP3 inflammasome pathways. In this review, the roles of the NLRP3 inflammasome in chemical-induced liver injury (CILI) and natural products that exhibit beneficial effects in CILI through the regulation of inflammasomes were systematically summarized.

Tripterygium wilfordii: An inspiring resource for rheumatoid arthritis treatment

Tripterygium wilfordii Hook F (TwHF)-based therapy is among the most efficient and crucial therapeutics for the treatment of rheumatoid arthritis (RA), which indicates that TwHF is a potential source of novel anti-RA drugs. However, accumulating studies have observed that TwHF-based therapy induces multi-organ toxicity, which prevents the wide use of this herb in clinical practice, although several recent studies have attempted to reduce the toxicity of TwHF. Notably, our research group developed a "Clinical Practice Guideline for Tripterygium Glycosides/Tripterygium wilfordii Tablets in the Treatment of Rheumatoid Arthritis" (No. T/CACM 1337-2020) approved by the China Association of Chinese Medicine to standardize the clinical application of TwHF-based therapy and thus avoid adverse effects. Although great strides have been made toward the characterization of TwHF-based therapy and revealing its underlying pharmacological and toxicological mechanisms, several crucial gaps in knowledge remain as potential barriers to enhance its therapeutic effects on the premise of safety assurance. This review offers a global view of TwHF, ranging from its chemical constituents, quality control, clinical observations, and underlying pharmacological mechanisms to toxic manifestations and mechanisms. We focus on the important and emerging aspects of this field and highlight the major challenges and strategies for using novel techniques and approaches to gain new insights into unresolved questions. We hope that this review will improve the understanding of TwHF application and draw increasing interdisciplinary attention from clinicians that practice both Chinese and Western medicine, basic researchers, and computer scientists.

Hepatoprotective effect of gentiopicroside in combination with leflunomide and/or methotrexate in arthritic rats

AIMS

This study aimed to examine whether gentiopicroside (GPS) could exert hepatoprotective effects on leflunomide (LEF)- and/or methotrexate (MTX)-treated arthritic rats through anti-inflammatory and antioxidant pathways.

MAIN METHODS

We observed the external symptoms of joints, analysed serum indicators, measured haematological parameters and mRNA levels, and performed HE staining.

KEY FINDINGS

LEF and/or MTX combined with GPS ameliorated oxidative stress by increasing the mRNA levels of the antioxidant gene Nrf2, GCLC, HO-1, and NQO1, increasing the antioxidant enzymes superoxide dismutase (SOD), glutathione (GSH) and catalase (CAT), reducing the oxidant substance malondialdehyde (MDA), reducing the inflammatory response by decreasing the mRNA levels of NF-κB, tumour necrosis factor-α (TNF-α), interleukin-1β (IL-1β), and interleukin-6 (IL-6), and inhibiting the secretion of the pro-inflammatory cytokines TNFα, IL-6, IL-1β and reducing C-reactive protein (CRP), as well as alleviating the external symptoms of arthritis.

SIGNIFICANCE

These results show that GPS plays an antioxidant and anti-inflammatory role in LEF- and/or MTX-treated arthritic rats by affecting the Nrf2 and NF-κB signalling pathways, thus exerting hepatoprotective effects.

Monotropein alleviates secondary liver injury in chronic colitis by regulating TLR4/NF-κB signaling and NLRP3 inflammasome

Recently, it has reported that many inflammatory bowel disease (IBD) patients were contracted secondary liver injury. Monotropein (MON), an iridoid glycoside, is demonstrated to possess protective effects on acute colitis mice due to its anti-inflammatory activities. However, it was remained unknown whether MON could inhibit secondary liver injury caused by IBD. The aim of the present study was to investigate the protective roles and mechanisms of MON on secondary liver injury in chronic colitis mice model. In this study, 2% Dextran sodium sulfate (DSS) was used to induce mice model of chronic colitis. The results showed that MON attenuated DSS-induced hepatic pathological damage, liver parameters, infiltration of macrophages and cytokines levels. Furthermore, we found that MON attenuated liver injury through suppressing the activation of the toll-like receptor 4 (TLR4)/nuclear factor-kappa B (NF-κB) signaling pathway and down-regulating the activity of NLRP3 (NOD-, LRR- and pyrin domain-containing 3) inflammasome. All the data indicated that MON may be an effective therapeutic reagent to attenuate secondary liver injury induced by chronic colitis.

Effect of CYP3A4 on liver injury induced by triptolide

Triptolide (TP), one of the main bioactive diterpenes of the herbal medicine Tripterygium wilfordii Hook F, is used for the treatment of autoimmune diseases in the clinic and is accompanied by severe hepatotoxicity. CYP3A4 has been reported to be responsible for TP metabolism, but the mechanism remains unclear. The present study applied a UPLC-QTOF-MS-based metabolomics analysis to characterize the effect of CYP3A4 on TP-induced hepatotoxicity. The metabolites carnitines, lysophosphatidylcholines (LPCs) and a serious of amino acids were found to be closely related to liver damage indexes in TP-treated female mice. Metabolomics analysis further revealed that the CYP3A4 inducer dexamethasone improved the level of LPCs and amino acids, and defended against oxidative stress. On the contrary, pretreatment with the CYP3A4 inhibitor ketoconazole increased liver damage with most metabolites being markedly altered, especially carnitines. Among these metabolites, except for LPC18:2, LPC20:1 and arginine, dexamethasone and ketoconazole both affected oxidative stress induced by TP. The current study provides new mechanistic insights into the metabolic alterations, leading to understanding of the role of CYP3A4 in hepatotoxicity induced by TP.