The Protective Roles of PPARα Activation in Triptolide-induced Liver Injury

Celastrol induced the autophagy of spermatogonia cells contributed to tripterygium glycosides-related testicular injury

Tripterygium glycosides (TG) is extracted from the roots of Chinese herbal medicine named Tripterygium wilfordii Hook F (TwHF). TG tablets are the representative TwHF-based agents with anti-inflammatory and immunomodulatory activities for treating rheumatoid arthritis. Although the curative effect of TG is remarkable, the clinical application is limited by a variety of organ toxicity. One of the most serious side-effects induced by TG is damage of the male reproductive system and the toxic mechanism is still not fully elucidated. TG-induced testicular injury was observed in male mice by treated with different concentrations of TG. The results showed that TG induced a significant decrease in testicular index. Pathological observation showed that spermatogenic cells were obviously shed, arranged loosely, and the spermatogenic epithelium was thin compared with control mice. In addition, the toxic effect of TG on mouse spermatogonia GC-1 cells was investigated. The results displayed that TG induced significant cytotoxicity in mouse GC-1 cells. To explore the potential toxic components that triggered testicular injury, the effects of 8 main components of TG on the viability of GC-1 cells were detected. The results showed that celastrol was the most toxic component of TG to GC-1 cells. Western blot analysis showed that LC3-II and the ratio of LC3-II/LC3-I were significantly increased and the expression level of p62 were decreased in both TG and celastrol treated cells, which indicated the significant activation of autophagy in spermatogonia cells. Therefore, autophagy plays an important role in the testicular injury induced by TG, and inhibition of autophagy is expected to reduce the testicular toxicity of TG.

Protective effect of Qingluotongbi formula against Tripterygium wilfordii induced liver injury in mice by improving fatty acid β-oxidation and mitochondrial biosynthesis

CONTEXT

Qingluotongbi formula (QLT) is a Chinese medicine compound consisting of Tripterygium wilfordii Hook. f. (Celastraceae, TW), Panax notoginseng (Burkill) F.H.Chen (Araliaceae, PN), Rehmannia glutinosa (Gaertn.) DC. (Orobanchaceae, RG), Sinomenium acutum (Thunb.) Rehder & E.H. Wilson (Menispermaceae, SA), and Bombyx mori L. (Bombycidae, BM).

OBJECTIVE

This study investigated the protective effect and possible mechanism of QLT against TW-induced liver injury in mice.

MATERIALS AND METHODS

To establish the model of TW-induced liver injury in mice, C57BL/6J mice were randomly divided into 4 groups: control group, low-dose TW group, middle-dose TW group, and high-dose TW group. To observe the effects of QLT and its individual ingredients against TW-induced liver injury, C57BL/6J mice were randomly divided into 7 groups: control group, TW group, QLT group, PN group, RG group, SA group, BM group.After administration for 7 days, C57BL/6J mice were tested for biochemical indicators and liver pathological changes. Then, we evaluated the mitochondrial function and analysed the gene and protein expression related to the peroxisome proliferator-activated receptor alpha (PPARα)/peroxisome proliferator-activated receptor gamma coactivator-1 alpha (PGC-1α) pathway by quantitative real-time PCR (qRT-PCR) and Western blotting.

RESULTS

Compared with the control group (0.30 ± 0.35), TW significantly increased mice liver histological score (L, 0.95 ± 1.14; M, 1.25 ± 1.16; H, 4.00 ± 1.13). QLT and its ingredients significantly improved the pathology scores (CON, 0.63 ± 0.74; TW, 4.19 ± 1.53; QLT, 1.56 ± 0.62; PN, 1.94 ± 0.68; RG, 2.75 ± 1.39; SA, 4.13 ± 0.99; BM, 4.13 ± 0.99). Western blot and qRT-PCR analysis revealed that QLT and its ingredients reversed TW-induced suppression of PPARα/PGC1-α pathway.Discussion and conclusions: These findings provide valuable information for compound compatibility studies and TW clinical applications.

The impact of vaccine-linked chemotherapy on liver health in a mouse model of chronic Trypanosoma cruzi infection

BACKGROUND

Chagas disease, chronic infection with Trypanosoma cruzi, mainly manifests as cardiac disease. However, the liver is important for both controlling parasite burdens and metabolizing drugs. Notably, high doses of anti-parasitic drug benznidazole (BNZ) causes liver damage. We previously showed that combining low dose BNZ with a prototype therapeutic vaccine is a dose sparing strategy that effectively reduced T. cruzi induced cardiac damage. However, the impact of this treatment on liver health is unknown. Therefore, we evaluated several markers of liver health after treatment with low dose BNZ plus the vaccine therapy in comparison to a curative dose of BNZ.

METHODOLOGY

Female BALB/c mice were infected with a bioluminescent T. cruzi H1 clone for approximately 70 days, then randomly divided into groups of 15 mice each. Mice were treated with a 25mg/kg BNZ, 25μg Tc24-C4 protein/ 5μg E6020-SE (Vaccine), 25mg/kg BNZ followed by vaccine, or 100mg/kg BNZ (curative dose). At study endpoints we evaluated hepatomegaly, parasite burden by quantitative PCR, cellular infiltration by histology, and expression of B-cell translocation gene 2(BTG2) and Peroxisome proliferator-activated receptor alpha (PPARα) by RT-PCR. Levels of alanine transaminase (ALT), aspartate transaminase (AST), alkaline phosphatase (ALP) and lactate dehydrogenase (LDH) were quantified from serum.

RESULTS

Curative BNZ treatment significantly reduced hepatomegaly, liver parasite burdens, and the quantity of cellular infiltrate, but significantly elevated serum levels of ALT, AST, and LDH. Low BNZ plus vaccine did not significantly affect hepatomegaly, parasite burdens or the quantity of cellular infiltrate, but only elevated ALT and AST. Low dose BNZ significantly decreased expression of both BTG2 and PPARα, and curative BNZ reduced expression of BTG2 while low BNZ plus vaccine had no impact.

CONCLUSIONS

These data confirm toxicity associated with curative doses of BNZ and suggest that while dose sparing low BNZ plus vaccine treatment does not reduce parasite burdens, it better preserves liver health.

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.

The impact of vaccine-linked chemotherapy on liver health in a mouse model of chronic Trypanosoma cruzi infection

Background

Chagas disease, chronic infection with Trypanosoma cruzi, mainly manifests as cardiac disease. However, the liver is important for both controlling parasite burdens and metabolizing drugs. Notably, high doses of anti-parasitic drug benznidazole (BNZ) causes liver damage. We previously showed that combining low dose BNZ with a prototype therapeutic vaccine is a dose sparing strategy that effectively reduced T. cruzi induced cardiac damage. However, the impact of this treatment on liver health is unknown. Therefore, we evaluated several markers of liver health after treatment with low dose BNZ plus the vaccine therapy in comparison to a curative dose of BNZ.

Methodology

Female BALB/c mice were infected with a bioluminescent T. cruzi H1 clone for approximately 70 days, then randomly divided into groups of 15 mice each. Mice were treated with a 25mg/kg BNZ, 25μg Tc24-C4 protein/5μg E6020-SE (Vaccine), 25mg/kg BNZ followed by vaccine, or 100mg/kg BNZ (curative dose). At study endpoints we evaluated hepatomegaly, parasite burden by quantitative PCR, cellular infiltration by histology, and expression of B-cell translocation gene 2(BTG2) and Peroxisome proliferator-activated receptor alpha (PPARα) by RT-PCR. Levels of alanine transaminase (ALT), aspartate transaminase (AST), alkaline phosphatase (ALP) and lactate dehydrogenase (LDH) were quantified from serum.

Results

Curative BNZ treatment significantly reduced hepatomegaly, liver parasite burdens, and the quantity of cellular infiltrate, but significantly elevated serum levels of ALT, AST, and LDH. Low BNZ plus vaccine did not significantly affect hepatomegaly, parasite burdens or the quantity of cellular infiltrate, but only elevated ALT and AST. Low dose BNZ significantly decreased expression of both BTG2 and PPARα, and curative BNZ reduced expression of BTG2 while low BNZ plus vaccine had no impact.

Conclusions

These data confirm toxicity associated with curative doses of BNZ and suggest that the dose sparing low BNZ plus vaccine treatment better preserves liver health.

Combined transcriptomics and metabolomics analysis reveals lipid metabolic disruption in swamp eel (Monopterus albus) under chronic waterborne copper exposure

Excessive copper can induce many adverse effects although it's an essential trace element in organisms. The effects of copper on the lipid metabolism have aroused increasing attention. This study investigated the liver lipid metabolism in swamp eel (Monopterus albus, M. albus) chronically exposed to 0, 10, 50, and 100 μg/L Cu²⁺ for 56 days. The results showed that copper increased the contents of triglyceride (TG), total cholesterol (T-CHO), non-esterified fatty acids (NEFA), and lipid droplets. Transcriptomic analysis found 1901 differentially expressed genes (DEGs) and 140 differential alternative splicing (DAS) genes in the 50 μg/L Cu²⁺ group, and 1787 DEGs and 184 DAS genes in the 100 μg/L Cu²⁺ group, respectively, which were enriched in peroxisome proliferator-activated receptor (PPAR), adenosine 5'-monophosphate (AMP)-activated protein kinase (AMPK), and other signaling pathways. The expression levels of key genes related to PPAR and AMPK signaling pathways were significantly down-regulated after chronic exposure to Cu²⁺. Meanwhile, metabolomics analysis showed that 52 and 110 differentially expressed metabolites (DEMs) were identified, which were mainly enriched in glycerophospholipids metabolism and steroid synthesis. Moreover, combined analysis of transcriptome and metabolome showed that glycerophospholipid metabolism co-enriched 19 down-regulated DEGs and 4 down-regulated DEMs. Taken together, our results suggested that chronic waterborne copper exposure promoted lipid synthesis, disrupted the metabolic homeostasis of glycerophospholipid, and led to excessive hepatic lipid deposition in M. albus. The combined omics approach enhanced our understanding of copper pollution to lipid metabolism.

The potential health risks of short-chain chlorinated paraffin: A mini-review from a toxicological perspective

Short-chain chlorinated paraffins (SCCPs) are ubiquitously distributed in various environmental matrics due to their wide production and consumption globally in the past and ongoing production and use in some developing countries. SCCPs have been detected in various human samples including serum, milk, placenta, nail, and hair, and internal SCCP levels were found to be positively correlated with biomarkers of some diseases. While the environmental occurrence has been reported in a lot of studies, the toxicity and underlying molecular mechanisms of SCCPs remain largely unknown. The current tolerable daily intakes (TDIs) recommended by the world health organization/international programme on chemical safety (WHO/IPCS, 100 μg/kg bw/d) and the UK Committee on Toxicity (COT, 30 μg/kg bw/d) were obtained based on a no observed adverse effect level (NOAEL) of SCCP from the repeated-dose study (90 d exposure) in rodents performed nearly 40 years ago. Importantly, the health risks assessment of SCCPs in a variety of studies has shown that the estimated daily intakes (EDIs) may approach and even over the established TDI by UK COT. Furthermore, recent studies revealed that lower doses of SCCPs could also result in damage to multiple organs including the liver, kidney, and thyroid. Long-term effects of SCCPs at environmental-related doses are warranted.

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.

3,3',5-triiodo-l-thyronine inhibits drug-induced liver injury through activation of PPARα as revealed by network pharmacology and biological experimental verification

Drug-induced liver injury (DILI) has increased in recent years, leading to acute liver failure. 3,3',5-triiodo-l-thyronine (T3) has been reported to exert a potent hepatoprotective effect. However, the mechanism and efficacy of T3 on DILI remain undocumented. In this study, an MTT assay was used to detect the effect of T3 on hepatotoxicity of acetaminophen (APAP) in L02 cells. Then, we screened key targets and related biological pathways by network pharmacology. Finally, enzyme-linked immunosorbent assay (ELISA) and quantitative reverse transcription-polymerase chain reaction (qRT-PCR) were used to verify the mechanism and key targets of T3 on DILI. The results of the MTT assay showed that T3 significantly decreased hepatocellular injury induced by APAP. Network pharmacology and bioinformatics analysis showed that 118 intersection targets of T3 and DILI were identified and the mechanism of T3 on DILI was related to cell proliferation and oxidative stress. ELISA results showed that T3 may be an effective treatment for DILI as biomarkers of hepatocellular injury such as AST, ALP were decreased compared to APAP only treated cells, and the mechanism of T3 may be mediated in part through improving redox balance. The topological parameter screening results suggested 12 key targets of T3 for DILI. Among them, PPARα is associated with DILI, and activation of PPARα can reduce oxidative stress and cell necrosis. Therefore, PPARα was identified as a target for verification. qRT-PCR analysis demonstrated that T3 could reverse the down-regulation of PPARα induced by APAP exposure. Taken together, we demonstrated for the first time that T3 could activate PPARα, promote cell proliferation and reduce oxidative stress, and play a vital role in the treatment of DILI, which provides a reference for T3 as a candidate treatment for DILI.

Da-Chai-Hu-Tang Protects From Acute Intrahepatic Cholestasis by Inhibiting Hepatic Inflammation and Bile Accumulation via Activation of PPARα

Cholestasis is caused by intrahepatic retention of excessive toxic bile acids and ultimately results in hepatic failure. Da-Chai-Hu-Tang (DCHT) has been used in China to treat liver and gallbladder diseases for over 1800 years. Here, we demonstrated that DCHT treatment prevented acute intrahepatic cholestasis with liver injury in response to α-naphthylisothiocyanate (ANIT) not to bile duct ligation (BDL) induced-extrahepatic cholestasis. ANIT (80 mg/kg) increased serum levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST), direct bilirubin (DBiL), total bilirubin (TBiL), and total bile acids (TBA) which was attenuated by DCHT treatment in a dose-dependent manner. DCHT treatment at high dose of 1.875 g/kg restored bile acid homeostasis, as evidenced by the recovery of the transcription of genes implicated in bile acid biosynthesis, uptake and efflux. DCHT treatment (1.875 g/kg) reversed ANIT-evoked disordered glutathione homeostasis (as determined by GSH/GSSG ratio) and increased in the mRNA levels for Il6, Il1b and Tnfa associated with liver inflammation. Using network pharmacology-based approaches, we identified 22 putative targets involved in DCHT treatment for intrahepatic cholestasis not extrahepatic cholestasis. In addition, as evidenced by dual-luciferase reporter assays, compounds from DCHT with high affinity of PPARα increased luciferase levels from a PPARα-driven reporter. PPARα agonist fenofibrate was able to mimic the cytoprotective effect of DCHT on intrahepatic cholestasis, which was abolished by the PPARα antagonist GW6471. KEGG enrichment and western blot analyses showed that signaling axes of JNK/IL-6/NF-κB/STAT3 related to PPARα might be the principal pathway DCHT affects intrahepatic cholestasis. Taken together, the present study provides compelling evidence that DCHT is a promising formula against acute intrahepatic cholestasis with hepatotoxicity which works via PPARα activation.

Metabolomic Profiling Reveals Protective Effects and Mechanisms of Sea Buckthorn Sterol against Carbon Tetrachloride-Induced Acute Liver Injury in Rats

The present study was designed to examine the efficacy and protection mechanisms of sea buckthorn sterol (SBS) against acute liver injury induced by carbon tetrachloride (CCl₄) in rats. Five-week-old male Sprague-Dawley (SD) rats were divided into six groups and fed with saline (Group BG), 50% CCl₄ (Group MG), or bifendate 200 mg/kg (Group DDB), or treated with low-dose (Group LD), medium-dose (Group MD), or high-dose (Group HD) SBS. This study, for the first time, observed the protection of SBS against CCl₄-induced liver injury in rats and its underlying mechanisms. Investigation of enzyme activities showed that SBS-fed rats exhibited a significant alleviation of inflammatory lesions, as evidenced by the decrease in cyclooxygenase-2 (COX-2), prostaglandin E2 (PGE2), and gamma-glutamyl transpeptidase (γ-GT). In addition, compared to the MG group, the increased indices (superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), catalase (CAT), total antioxidant capacity (T-AOC), and total protein (TP)) of lipid peroxidation and decreased malondialdehyde (MDA) in liver tissues of SBS-treated groups showed the anti-lipid peroxidation effects of SBS. Using the wide range of targeted technologies and a combination of means (UPLC-MS/MS detection platform, self-built database, and multivariate statistical analysis), the addition of SBS was found to restore the expression of metabolic pathways (e.g., L-malic acid, N-acetyl-aspartic acid, N-acetyl-l-alanine, etc.) in rats, which means that the metabolic damage induced by CCl₄ was alleviated. Furthermore, transcriptomics was employed to analyze and compare gene expression levels of different groups. It showed that the expressions of genes (Cyp1a1, Noct, and TUBB6) related to liver injury were regulated by SBS. In conclusion, SBS exhibited protective effects against CCl₄-induced liver injury in rats. The liver protection mechanism of SBS is probably related to the regulation of metabolic disorders, anti-lipid peroxidation, and inhibition of the inflammatory response.

Detoxification strategies of triptolide based on drug combinations and targeted delivery methods

Tripterygium wilfordii Hook f. has a long history of use in Chinese medicine. Triptolide (TP), as its main pharmacological component, has been widely explored in various diseases, including systemic lupus erythematosus, rheumatoid arthritis and cancer. However, due to its poor water solubility, limited therapeutic range and multi-organ toxicity, TP's clinical application has been greatly hampered. To improve its clinical potential, many attenuated drug combinations have been developed based on its toxicity mechanism and targeted delivery systems aimed at its water-solubility and structure. This review, conducted a systematic review of TP detoxification strategies including drug combination detoxification strategies from metabolic and toxic mechanisms, as well as drug delivery detoxification strategies from the prodrug strategy and nanotechnology. Many detoxification strategies have demonstrated promising potential in vitro and in vivo due to previous extensive studies on TP. Therefore, summarizing and discussing TP detoxification strategies for clinical problems can serve as a reference for developing novel TP detoxification strategies, and provide opportunities for future clinical applications.

Metabolomics reveals the role of PPARα in Tripterygium Wilfordii-induced liver injury

ETHNOPHARMACOLOGICAL RELEVANCE

Tripterygium glycosides tablets (TGT) and Tripterygium wilfordii tablets (TWT) have been used to treat autoimmune diseases clinically, however, the side effects of TWT are higher than TGT, especially for hepatotoxicity.

THE AIM OF THE STUDY

This study aims to determine the mechanism of TWT-induced liver injury.

MATERIALS AND METHODS

We performed metabolomic analysis of samples from mice with liver injury induced by TGT and TWT. Ppara-null mice were used to determine the role of PPARα in TWT-induced liver injury.

RESULTS

The results indicated that TWT induced the accumulation of medium- and long-chain carnitines metabolism, which was associated with the disruption of PPARα-IL6-STAT3 axis. PPARα agonists fenofibrate could reverse the liver injury from TWT and TP/Cel, and its protective role could be attenuated in Ppara-null mice. The toxicity difference of TWT and TGT was due to the different ratio of triptolide (TP) and celastrol (Cel) in the tablet in which TP/Cel was lower in TWT than TGT. The hepatotoxicity induced by TP and Cel also inhibited PPARα and upregulated IL6-STAT3 axis, which could be alleviated following by PPARα activation.

CONCLUSIONS

These results indicated that PPARα plays an important role in the hepatotoxicity of Tripterygium wilfordii, and PPARα activation may offer a promising approach to prevent hepatotoxicity induced by the preparations of Tripterygium wilfordii.

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.

Oleuropein-Induced Acceleration of Cytochrome P450-Catalyzed Drug Metabolism: Central Role for Nuclear Receptor Peroxisome Proliferator-Activated Receptor α

Oleuropein (OLE), the main constituent of Olea europaea, displays pleiotropic beneficial effects in health and disease, which are mainly attributed to its anti-inflammatory and cardioprotective properties. Several food supplements and herbal medicines contain OLE and are available without a prescription. This study investigated the effects of OLE on the main cytochrome P450s (P450s) catalyzing the metabolism of many prescribed drugs. Emphasis was given to the role of peroxisome proliferator-activated receptor α (PPARα), a nuclear transcription factor regulating numerous genes including P450s. 129/Sv wild-type and Ppara-null mice were treated with OLE for 6 weeks. OLE induced Cyp1a1, Cyp1a2, Cyp1b1, Cyp3a14, Cyp3a25, Cyp2c29, Cyp2c44, Cyp2d22, and Cyp2e1 mRNAs in liver of wild-type mice, whereas no similar effects were observed in Ppara-null mice, indicating that the OLE-induced effect on these P450s is mediated by PPARα. Activation of the pathways related to phosphoinositide 3-kinase/protein kinase B (AKT)/forkhead box protein O1, c-Jun N-terminal kinase, AKT/p70, and extracellular signal-regulated kinase participates in P450 induction by OLE. These data indicate that consumption of herbal medicines and food supplements containing OLE could accelerate the metabolism of drug substrates of the above-mentioned P450s, thus reducing their efficacy and the outcome of pharmacotherapy. Therefore, OLE-induced activation of PPARα could modify the effects of drugs due to their increased metabolism and clearance, which should be taken into account when consuming OLE-containing products with certain drugs, in particular those of narrow therapeutic window. SIGNIFICANCE STATEMENT: This study indicated that oleuropein, which belongs to the main constituents of the leaves and olive drupes of Olea europaea, induces the synthesis of the major cytochrome P450s (P450s) metabolizing the majority of prescribed drugs via activation of peroxisome proliferator-activated receptor α. This effect could modify the pharmacokinetic profile of co-administered drug substrates of the P450s, thus altering their therapeutic efficacy and toxicity.

Acetylcholinesterase inhibition in electric eel and human donor blood: an in vitro approach to investigate interspecies differences and human variability in toxicodynamics

In chemical risk assessment, default uncertainty factors are used to account for interspecies and interindividual differences, and differences in toxicokinetics and toxicodynamics herein. However, these default factors come with little scientific support. Therefore, our aim was to develop an in vitro method, using acetylcholinesterase (AChE) inhibition as a proof of principle, to assess both interspecies and interindividual differences in toxicodynamics. Electric eel enzyme and human blood of 20 different donors (12 men/8 women) were exposed to eight different compounds (chlorpyrifos, chlorpyrifos-oxon, phosmet, phosmet-oxon, diazinon, diazinon-oxon, pirimicarb, rivastigmine) and inhibition of AChE was measured using the Ellman method. The organophosphate parent compounds, chlorpyrifos, phosmet and diazinon, did not show inhibition of AChE. All other compounds showed concentration-dependent inhibition of AChE, with IC50s in human blood ranging from 0.2-29 µM and IC20s ranging from 0.1-18 µM, indicating that AChE is inhibited at concentrations relevant to the in vivo human situation. The oxon analogues were more potent inhibitors of electric eel AChE compared to human AChE. The opposite was true for carbamates, pointing towards interspecies differences for AChE inhibition. Human interindividual variability was low and ranged from 5-25%, depending on the concentration. This study provides a reliable in vitro method for assessing human variability in AChE toxicodynamics. The data suggest that the default uncertainty factor of ~ 3.16 may overestimate human variability for this toxicity endpoint, implying that specific toxicodynamic-related adjustment factors can support quantitative in vitro to in vivo extrapolations that link kinetic and dynamic data to improve chemical risk assessment.

Comprehensive analysis of transcriptomics and metabolomics to understand triptolide-induced liver injury in mice

Triptolide, a major active component of Triptergium wilfordii Hook. f, is used in the treatment of autoimmune disease. However, triptolide is associated with severe adverse reactions, especially hepatotoxicity, which limits its clinical application. To examine the underlying mechanism of triptolide-induced liver injury, a combination of dose- and time-dependent toxic effects, RNA-seq and metabolomics were employed. Triptolide-induced toxicity occurred in a dose- and time-dependent manners and was characterized by apoptosis and not necroptosis. Transcriptomics profiles of the dose-dependent response to triptolide suggested that PI3K/AKT, MAPK, TNFα and p53 signaling pathways were the vital steps in triptolide-induced hepatocyte apoptosis. Metabolomics further revealed that glycerophospholipid, fatty acid, leukotriene, purine and pyrimidine metabolism were the major metabolic alterations after triptolide exposure. Finally, acylcarnitines were identified as potential biomarkers for the early detection of triptolide-induced liver injury.

Celastrol ameliorates acute liver injury through modulation of PPARα

Celastrol, derived from the roots of the Tripterygium Wilfordi, has attracted interest for its potential anti-inflammatory and lipid-lowering activities. In the present study, the protective effect of celastrol on carbon tetrachloride (CCl4)-induced acute liver injury was investigated. Celastrol improved the increased transaminase activity, inflammation, and oxidative stress induced by CCl4, resulting in improved metabolic disorders found in mice with liver injury. Dual-luciferase reporter assays and primary hepatocyte studies demonstrated that the peroxisome proliferator-activated receptor α (PPARα) signaling mediated the protective effect of celastrol, which was not observed in Ppara-null mice, and co-treatment of wild-type mice with the PPARα antagonist GW6471. Mechanistically, PPARα deficiency potentiated CCl4-induced liver injury through a deoxycholic acid (DCA)-EGR1-inflammatory factor axis. These data demonstrate a novel role for celastrol in protection against acute liver injury through modulating PPARα signaling.

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.