Autophagy in Triptolide-Mediated Cytotoxicity in Hepatic Cells

Plant-derived compounds that target histone acetyltransferases inhibit Trypanosoma cruzi proliferation and viability and affect parasite ultrastructure

Trypanosoma cruzi, the causative agent of Chagas disease, exhibits a chromatin structure and organization similar to that of other eukaryotes, undergoing certain epigenetic modifications, such as histone acetylation and deacetylation. Histone acetyltransferase inhibitors have been frequently applied as therapy agents against tumor cells, but their effects on protozoa have not yet been adequately explored. In this study, the effects of three acetyltransferase inhibitors, curcumin, triptolide and anacardic acid, were investigated on T. cruzi. Curcumin was able to inhibit epimastigote and amastigote proliferation and was the most effective compound. Triptolide also impaired T. cruzi proliferation and, along with curcumin, promoted the unpacking of nuclear heterochromatin and nucleolus disorganization. Anacardic acid did not alter parasite growth or viability, but caused ultrastructural changes, such as mitochondrial swelling and cristae enlargement. None of these compounds affected the microtubule cytoskeleton. These findings indicate that histone acetyltransferase inhibitors, especially curcumin, display the potential to be applied in chemotherapeutic studies against T. cruzi. Our results reinforce the necessity of developing new compounds that can be used successfully in therapy against neglected diseases.

Isobavachin induces autophagy-mediated cytotoxicity in AML12 cells via AMPK and PI3K/Akt/mTOR pathways

Isobavachin (IBA) is a dihydroflavonoid compound with various pharmacological effects. However, further investigation into the hepatotoxicity of IBA is necessary. This study aims to identify the hepatotoxic effects of IBA and explore its potential mechanisms. The study assessed the impact of IBA on the viability of AML12, HepG2, LO2, rat, and mouse primary hepatocytes using MTT and LDH assays. Autophagy was detected in AML12 cells after IBA treatment using electron microscopy, MDC, and Ad-mCherry-GFP-LC3B fluorescence. The effect of IBA on autophagy-related proteins was examined using Western blot. The results showed that IBA had dose-dependent inhibitory effects on five cells, induced autophagy in AML12 cells, and promoted autophagic flux. The study found that IBA treatment inhibited phosphorylation of PI3K, Akt, and mTOR, while increasing phosphorylation levels of AMPK and ULK1. Treatment with both AMPK and PI3K inhibitors reversed the expression of AMPK and PI3K-Akt-mTOR signaling pathway proteins. These results suggest that IBA may have hepatocytotoxic effects but can also prevent IBA hepatotoxicity by inhibiting the AMPK and PI3K/Akt/mTOR signaling pathways. This provides a theoretical basis for preventing and treating IBA hepatotoxicity in clinical settings.

The Yin and Yang of the Natural Product Triptolide and Its Interactions with XPB, an Essential Protein for Gene Expression and DNA Repair

Triptolide, a bioactive diterpene tri-epoxide extracted from Tripterygium wilfordii Hook F (TWHF), exhibits notable pharmacological activities, including anti-inflammatory, immunosuppressive, antifertility, and anticancer effects. Despite its promising therapeutic potential, clinical applications of triptolide are significantly limited by its poor water solubility and substantial toxicity, particularly hepatotoxicity, nephrotoxicity, and cardiotoxicity. These toxic effects are difficult to separate from many of its desired therapeutic effects, the Yin and Yang of triptolide applications. Triptolide's therapeutic and toxic effects are linked to its inhibitory interactions with XPB, a DNA helicase essential for transcription by RNA polymerase II (RNAPII) and nucleotide excision repair (NER). By irreversibly binding to XPB, triptolide inhibits its ATPase activity, leading to global repression of transcription and impaired NER, which underlies its cytotoxic and antitumor properties. Recent developments, including triptolide prodrugs such as Minnelide and derivatives like glutriptolides, aim to enhance its pharmacokinetic properties and reduce toxicity. This review critically examines triptolide's chemical structure, therapeutic applications, toxicological profile, and molecular interactions with XPB and other protein targets to inform future strategies that maximize therapeutic efficacy while minimizing adverse effects.

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.

A comprehensive review on celastrol, triptolide and triptonide: Insights on their pharmacological activity, toxicity, combination therapy, new dosage form and novel drug delivery routes

Celastrol, triptolide and triptonide are the most significant active ingredients of Tripterygium wilfordii Hook F (TWHF). In 2007, the 'Cell' journal ranked celastrol, triptolide, artemisinin, capsaicin and curcumin as the five natural drugs that can be developed into modern medicinal compounds. In this review, we collected relevant data from the Web of Science, PubMed and China Knowledge Resource Integrated databases. Some information was also acquired from government reports and conference papers. Celastrol, triptolide and triptonide have potent pharmacological activity and evident anti-cancer, anti-tumor, anti-obesity and anti-diabetes effects. Because these compounds have demonstrated unique therapeutic potential for acute and chronic inflammation, brain injury, vascular diseases, immune diseases, renal system diseases, bone diseases and cardiac diseases, they can be used as effective drugs in clinical practice in the future. However, celastrol, triptolide and triptonide have certain toxic effects on the liver, kidney, cholangiocyte heart, ear and reproductive system. These shortcomings limit their clinical application. Suitable combination therapy, new dosage forms and new routes of administration can effectively reduce toxicity and increase the effect. In recent years, the development of different targeted drug delivery formulations and administration routes of celastrol and triptolide to overcome their toxic effects and maximise their efficacy has become a major focus of research. However, in-depth investigation is required to elucidate the mechanisms of action of celastrol, triptolide and triptonide, and more clinical trials are required to assess the safety and clinical value of these compounds.

Cross-talk between the RAS-ERK and mTOR signalings-associated autophagy contributes to tripterygium glycosides tablet-induced liver injury

BACKGROUND AND AIMS

Drug-induced liver injury (DILI) remains a critical issue and a hindrance to clinical application of Tripterygium Glycosides Tablet (TGT) despite its favorable therapeutic efficacy in rheumatoid arthritis. Herein, we aimed to elucidate the molecular mechanisms underlying TGT-induced hepatotoxicity.

METHODS

Chemical profiling of TGT was identified by UPLC-Q/TOF-MS/MS and its putative targets were predicted based on chemical structure similarity calculation. Following "DILI-related gene-TGT putative target" interaction network construction, a list of key network targets was screened according to nodes' topological importance and functional relevance. Both in vivo and in vitro experiments were performed to determine drug hepatotoxicity and the underlying mechanisms.

RESULT

A total of 49 chemical components and 914 putative targets of TGTs were identified. Network calculation and functional modularization screened RAS-ERK and mTOR signalings-associated autophagy to be one of the candidate targets of TGT-induced hepatotoxicity. Experimentally, TGT significantly activated RAS-ERK axis, elevated the number of autophagosomes and the expression of LC3II protein, but reduced the expression of p62 protein and suppressed mTOR phosphorylation in the liver tissues of TGT-induced acute liver injury mice and chronic liver injury mice in vivo and AML12 cells in vitro. Moreover, TGT and mL-098 (an activator of RAS) co-treatment reduced AML12 cell viability via regulating autophagy and TGT-induced liver injury-related indicators more dramatically than TGT treatment alone, whereas Salirasib (an inhibitor of RAS) had an opposite effect.

CONCLUSION

RAS-ERK-mTOR cross-talk may play a crucial role in TGT-induced hepatocyte autophagy, offering a promising target for developing novel therapeutics to combat TGT-induced hepatotoxicity.

Friend or foe? The dual role of triptolide in the liver, kidney, and heart

Triptolide, a controversial natural compound due to its significant pharmacological activities and multiorgan toxicity, has gained much attention since it was isolated from the traditional Chinese herb Tripterygium wilfordii Hook F. However, in addition to its severe toxicity, triptolide also presents powerful therapeutic potency in the same organs, such as the liver, kidney, and heart, which corresponds to the Chinese medicine theory of You Gu Wu Yun (anti-fire with fire) and deeply interested us. To determine the possible mechanisms involved in the dual role of triptolide, we reviewed related articles about the application of triptolide in both physiological and pathological conditions. Inflammation and oxidative stress are the two main ways triptolide exerts different roles, and the cross-talk between NF-κB and Nrf2 may be one of the mechanisms responsible for the dual role of triptolide and may represent the scientific connotation of You Gu Wu Yun. For the first time, we present a review of the dual role of triptolide in the same organ and propose the possible scientific connotation of the Chinese medicine theory of You Gu Wu Yun, hoping to promote the safe and efficient use of triptolide and other controversial medicines.

Triptolide and l-ascorbate palmitate co-loaded micelles for combination therapy of rheumatoid arthritis and side effect attenuation

Triptolide (TP) has its unique curative effect in the treatment of rheumatoid arthritis (RA), but its application is limited by the poor water solubility and multi-organ toxicity. We herein developed a novel nanoparticle platform composed of L-ascorbate palmitate (VP, vitamin C derivative) that can deliver TP to synergistically treat arthritis and inhibit the occurrence of oxidative stress. The TP-loaded nanoparticles (termed TP-VP NPs) showed the suitable particle size (about 145 nm) and good physical stability. TP-VP NPs effectively down-regulated IL-1β, IL-6 and TNF-α levels to inhibit the erosion of synovitis and bone tissue, and alleviate the swelling and deformation of CIA mice’s feet. Compared to the TP, TP-VP NPs could inhibit effectively the oxidative stress in liver, and alleviate significantly the triptolide-induced toxicity injury in liver, kidney and testicle. The results demonstrated that TP-VP NPs is a promising triptolide delivery system for the treatment of RA, which enhances the water solubility of TP and reduces the toxicity of TP in vivo.

Inflammation aggravated the hepatotoxicity of triptolide by oxidative stress, lipid metabolism disorder, autophagy, and apoptosis in zebrafish

Triptolide is a major compound isolated from the Tripterygium wilfordii Hook that is mainly used for the treatment of autoimmune disorders and inflammatory diseases. Though triptolide-induced hepatotoxicity has been widely reported, the hepatic effects when the patients are in an inflammatory state are not clear. In this study, we used low-dose Lipopolysaccharides (LPS) to disrupt the inflammation homeostasis in the liver of zebrafish and explored the hepatotoxicity of triptolide under an inflammatory state. Compared with the Triptolide group, LPS-Triptolide cotreatment exacerbate the liver injury with a remarkable decrease of liver size and liver-specific fluorescence intensity, accompanied by significant elevation of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) activities. Liver cell damages were further demonstrated by histological staining and scanning electron microscopy observation. Lipid metabolism was severely impaired as indicated by delayed yolk sac absorption, accumulated triglycerides in the liver, and dysregulation of the related genes, such as ppar-α, cpt-1, mgst, srebf1/2, and fasn. Oxidative stress could be involved in the molecular mechanism as the Nrf2/keap1 antioxidant pathways were down-regulated when the zebrafish in an inflammatory state. Moreover, the expression of autophagy-related genes such as beclin, atg5, map1lc3b, and atg3 was also dysregulated. Finally, apoptosis was significantly induced in responses to LPS-Triptolide co-treatment. We speculate that triptolide could exacerbate the immune response and impair lipid metabolism, resulting in enhanced sensitivity of the zebrafish liver to triptolide-induced toxic effects through disruption of the antioxidant system and induction of apoptosis.

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.

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.

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.

Arctiin Antagonizes Triptolide-Induced Hepatotoxicity via Activation of Nrf2 Pathway

Triptolide (TP) is the most effective ingredient found in the traditional Chinese herbal Tripterygium wilfordii Hook F, and it is widely used in therapies of autoimmune and inflammatory disorders. However, the hepatotoxicity induced by TP has restricted its use in clinical trials. Arctiin is known as a protective agent against oxidative stress, and it exerts liver-protecting effect. This study was aimed at investigating the protective role of arctiin against TP-induced hepatotoxicity using in vitro and in vivo models. The results indicated that TP not only obviously induced liver injury in mice but also significantly inhibited the growth of HepG2 cells and increased the level of intracellular reactive oxygen. Furthermore, TP obviously decreased the expressions of proteins of Nrf2 pathway including HO-1, NQO1, and Nrf2 associated with oxidative stress pathway. However, the above experimental indexes were reversed by the treatment of arctiin. Our results suggested that arctiin could alleviate TP-induced hepatotoxicity, and the molecular mechanism is likely related to its capacity against oxidative stress.