Activation of pregnane X receptor protects against cholestatic liver injury by inhibiting hepatocyte pyroptosis.

Our previous study shows that activation of pregnane X receptor (PXR) exerts hepatoprotection against lithocholic acid (LCA)-induced cholestatic liver injury. In this study we investigated whether PXR activation could inhibit hepatocyte pyroptosis, as well as the underlying mechanisms. Male mice were treated with mouse PXR agonist pregnenolone 16α-carbonitrile (PCN, 50 mg·kg-1·d-1, i.p.) for 7 days, and received LCA (125 mg/kg, i.p., bid) from D4, then sacrificed 12 h after the last LCA injection. We showed that LCA injection resulted in severe cholestatic liver injury characterized by significant increases in gallbladder size, hepatocellular necrosis, and neutrophil infiltration with a mortality rate of 68%; PCN treatment significantly inhibited hepatocyte pyroptosis during LCA-induced cholestatic liver injury, as evidenced by reduced serum lactic dehydrogenase (LDH) levels, TUNEL-positive cells and hepatocyte membrane damage. Furthermore, PXR activation suppressed both the NOD-like receptor protein 3 (NLRP3) inflammasome-induced canonical pyroptosis and the apoptosis protease activating factor-1 (APAF-1) pyroptosome-induced non-canonical pyroptosis. Inhibition of the nuclear factor kappa B (NF-κB) and forkhead box O1 (FOXO1) signaling pathways was also observed following PXR activation. Notably, dual luciferase reporter assay showed that PXR activation inhibited the transcriptional effects of NF-κB on NLRP3, as well as FOXO1 on APAF-1. Our results demonstrate that PXR activation protects against cholestatic liver injury by inhibiting the canonical pyroptosis through the NF-κB-NLRP3 axis and the non-canonical pyroptosis through the FOXO1-APAF-1 axis, providing new evidence for PXR as a prospective anti-cholestatic target.

An updated review of the genus Rhododendron since 2010: Traditional uses, phytochemistry, and pharmacology.

Rhododendron, the largest genus of Ericaceae, consists of approximately 1000 species that are widely distributed in Europe, Asia, and North America but mainly exist in Asia. Rhododendron plants have not only good ornamental and economic value but also significant medicinal potential. In China, many Rhododendron plants are used as traditional Chinese medicine or ethnic medicine for the treatment of respiratory diseases, pain, bleeding and inflammation. Rhododendron is known for its abundant metabolites, especially diterpenoids. In the past 13 years, a total of 610 chemical constituents were reported from Rhododendron plants, including 222 diterpenoids, 122 triterpenoids, 103 meroterpenoids, 71 flavonoids and 92 other constituents (lignans, phenylpropanoids, phenolic acids, monoterpenoids, sesquiterpenoids, coumarins, steroids, fatty acids). Moreover, the bioactivities of various extracts and isolates, both in vitro and in vivo, were also investigated. Our review summarized the research progress of Rhododendron regarding traditional uses, phytochemistry and pharmacology in the past 13 years (2010 to December 2022), which will provide new insight for prompting further research on Rhododendron application and drug development.

Peroxisome proliferator-activated receptor α agonist induces mouse hepatomegaly through the spatial hepatocyte enlargement and proliferation.

Peroxisome proliferator-activated receptor alpha (PPARα) activation-induced hepatomegaly is accompanied by hepatocyte hypertrophy around the central vein (CV) area and hepatocyte proliferation around the portal vein (PV) area. However, the molecular mechanisms underlying this spatial change of hepatocytes remains unclear. In this study, we examined the characteristics and possible reasons for the zonation distinction of hypertrophy and proliferation during PPARα activation-induced mouse liver enlargement. Mice were injected with corn oil or a typical mouse PPARα agonist WY-14643 (100 mg·kg-1·d-1, i.p.) for 1, 2, 3, 5 or 10 days. At each time point, the mice were sacrificed after the final dose, and liver tissues and serum were harvested for analysis. We showed that PPARα activation induced zonal changes in hepatocyte hypertrophy and proliferation in the mice. In order to determine the zonal expression of proteins related to hepatocyte hypertrophy and proliferation in PPARα-induced liver enlargement, we performed digitonin liver perfusion to separately destroy the hepatocytes around the CV or PV areas, and found that PPARα activation-induced increase magnitude of its downstream targets such as cytochrome P450 (CYP) 4 A and acyl-coenzyme A oxidase 1 (ACOX1) levels around the CV area were higher compared with those around the PV area. Upregulation of proliferation-related proteins such as cell nuclear antigen (PCNA) and cyclin A1 (CCNA1) after WY-14643-induced PPARα activation mainly occurred around the PV area. This study reveals that the zonal expression of PPARα targets and proliferation-related proteins is responsible for the spatial change of hepatocyte hypertrophy and proliferation after PPARα activation. These findings provide a new insight into the understanding of PPARα activation-induced liver enlargement and regeneration.

Long-term treatment with the mPXR agonist PCN promotes hepatomegaly and lipid accumulation without hepatocyte proliferation in mice.

Pregnane X receptor (PXR) is highly expressed in the liver and plays a pivotal role in xenobiotic and endobiotic metabolism. We previously reported that PXR activation by its specific mouse agonist pregnenolone 16α-carbonitrile (PCN) significantly induces liver enlargement and lipid accumulation. However, the effect of long-term PCN treatment on PXR and mouse liver is still unknown. This study aimed to explore the influence of long-term administration of PCN on mouse liver and hepatic lipid homeostasis. Male C57BL/6 mice were injected intraperitoneally with PCN (100 mg/kg once a week) for 42 weeks. Serum and liver samples were collected for biochemical and histological analysis. PXR activation was investigated by Western blot. Ultra-high-performance liquid chromatography coupled with electrospray ionization high-resolution mass spectrometry (UHPLC-ESI-HRMS)-based lipidomics analysis was performed to explore the change in different lipid categories. The results showed that long-term treatment with PCN significantly promoted hepatomegaly without hepatocyte proliferation and enlargement. Long-term treatment with PCN did not upregulate PXR target proteins in mice, and there was no significant upregulation of CYP3A11, CYP2B10, UGT1A1, MRP2, or MRP4. Lipidomics analysis showed obvious hepatic lipid accumulation in the PCN-treated mice, and the most significant change was found in triglycerides (TGs). Additionally, long-term treatment with PCN had no risk for carcinogenesis. These findings demonstrated that long-term PCN treatment induces hepatomegaly and lipid accumulation without hepatocyte proliferation or enlargement.

Hepatoprotective Effect of Oplopanax elatus Nakai Adventitious Roots Extract by Regulating CYP450 and PPAR Signaling Pathway.

O. elatus Nakai is a traditional medicine that has been confirmed to exert effective antioxidant and anti-inflammatory functions, and is used for the treatment of different disorders. However, its potential beneficial effects on drug induced hepatotoxicity and relevant molecular mechanisms remain unclear. This study investigated the protective effect and further elucidated the mechanisms of action of O. elatus on liver protection. O. elatus chlorogenic acids-enriched fraction (OEB), which included chlorogenic acid and isochlorogenic acid A, were identified by HPLC-MS/MS. OEB was administrated orally daily for seven consecutive days, followed by a single intraperitoneal injection of an overdose of APAP after the final OEB administration. The effects of OEB on immune cells in mice liver were analyzed using flow cytometry. APAP metabolite content in serum was detected using HPLC-MS/MS in order to investigate whether OEB affects CYP450 activities. The intestinal content samples were processed for 16 s microbiota sequencing. Results demonstrated that OEB decreased alanine aminotransferase, aspartate aminotransferase contents, affected the metabolism of APAP, and decreased the concentrates of APAP, APAP-CYS and APAP-NAC by inhibiting CYP2E1 and CYP3A11 activity. Furthermore, OEB pretreatment regulated lipid metabolism by affecting the peroxisome proliferator-activated receptors (PPAR) signaling pathway in mice and also increased the abundance of Akkermansia and Parabacteroides. This study indicated that OEB is a potential drug candidate for treating hepatotoxicity because of its ability to affect drug metabolism and regulate lipid metabolism.

Natural product-based screening led to the discovery of a novel PXR agonist with anti-cholestasis activity.

Cholestasis is a major cause of a series of bile flow malfunction-related liver diseases. Pregnane X receptor (PXR) is a key regulator in endo- and xeno-biotics metabolism, which has been considered as a promising therapeutic target for cholestasis. In this study we conducted human PXR (hPXR) agonistic screening using dual-luciferase reporter gene assays, which led to discovering a series of potent hPXR agonists from a small Euphorbiaceae diterpenoid library, containing 35 structurally diverse diterpenoids with eight different skeleton types. The most active compound 6, a lathyrane diterpenoid (5/11/3 ring system), dose-dependently activated hPXR with a high selectivity, and significantly upregulated the expression of hPXR downstream genes CYP3A4 and UGT1A1. In LCA-induced cholestasis mouse model, administration of compound 6 (50 mg· kg-1. d-1, ip) for 7 days significantly suppressed liver necrosis and decreased serum levels of AST, ALT, Tbili, ALP, and TBA, ameliorating LCA-induced cholestatic liver injury. We further revealed that compound 6 exerted its anti-cholestatic efficacy via activation of PXR pathway, accelerating the detoxification of toxic BAs and promoting liver regeneration. These results suggest that lathyrane diterpenoids may serve as a promising scaffold for future development of anti-cholestasis drugs.

Hepatic Vps33b deficiency aggravates cholic acid-induced cholestatic liver injury in male mice.

Vacuolar protein sorting 33B (VPS33B) is important for intracellular vesicular trafficking process and protein interactions, which is closely associated with the arthrogryposis, renal dysfunction, and cholestasis syndrome. Our previous study has shown a crucial role of Vps33b in regulating metabolisms of bile acids and lipids in hepatic Vps33b deficiency mice with normal chow, but it remains unknown whether VPS33B could contribute to cholestatic liver injury. In this study we investigated the effects of hepatic Vps33b deficiency on bile acid metabolism and liver function in intrahepatic cholestatic mice. Cholestasis was induced in Vps33b hepatic knockout and wild-type male mice by feeding 1% CA chow diet for 5 consecutive days. We showed that compared with the wild-type mice, hepatic Vps33b deficiency greatly exacerbated CA-induced cholestatic liver injury as shown in markedly increased serum ALT, AST, and ALP activities, serum levels of total bilirubin, and total bile acid, as well as severe hepatocytes necrosis and inflammatory infiltration. Target metabolomics analysis revealed that hepatic Vps33b deficiency caused abnormal profiles of bile acids in cholestasis mice, evidenced by the upregulation of conjugated bile acids in serum, liver, and bile. We further demonstrated that the metabolomics alternation was accompanied by gene expression changes in bile acid metabolizing enzymes and transporters including Cyp3a11, Ugt1a1, Ntcp, Oatp1b1, Bsep, and Mrp2. Overall, these results suggest a crucial role of hepatic Vps33b deficiency in exacerbating cholestasis and liver injury, which is associated with the altered metabolism of bile acids.

PXR mediates mifepristone-induced hepatomegaly in mice.

Mifepristone (Mif), an effective synthetic steroidal antiprogesterone drug, is widely used for medical abortion and pregnancy prevention. Due to its anti-glucocorticoid effect, high-dose Mif is also used to treat Cushing's syndrome. Mif was reported to active pregnane X receptor (PXR) in vitro and PXR can induce hepatomegaly via activation and interaction with yes-associated protein (YAP) pathway. High-dose Mif was reported to induce hepatomegaly in rats and mice, but the underlying mechanism remains unclear. Here, the role of PXR was studied in Mif-induced hepatomegaly in C57BL/6 mice and Pxr-knockout mice. The results demonstrated that high-dose Mif (100 mg · kg-1 · d-1, i.p.) treatment for 5 days significantly induced hepatomegaly with enlarged hepatocytes and promoted proliferation, but low dose of Mif (5 mg · kg-1 · d-1, i.p.) cannot induce hepatomegaly. The dual-luciferase reporter gene assays showed that Mif can activate human PXR in a concentration-dependent manner. In addition, Mif could promote nuclear translocation of PXR and YAP, and significantly induced the expression of PXR, YAP, and their target proteins such as CYP3A11, CYP2B10, UGT1A1, ANKRD, and CTGF. However, Mif (100 mg · kg-1 · d-1, i.p.) failed to induce hepatomegaly in Pxr-knockout mice, as well as hepatocyte enlargement and proliferation, further indicating that Mif-induced hepatomegaly is PXR-dependent. In summary, this study demonstrated that PXR-mediated Mif-induced hepatomegaly in mice probably via activation of YAP pathway. This study provides new insights in Mif-induced hepatomegaly, and provides novel evidence on the crucial function of PXR in liver enlargement and regeneration.

Lathyrane Diterpenoids as Novel hPXR Agonists: Isolation, Structural Modification, and Structure-Activity Relationships.

Pregnane X receptor (PXR) that orchestrates the intricate network of xeno- and endobiotic metabolism is considered as a promising therapeutic target for cholestasis. In this study, the human PXR (hPXR) agonistic bioassay-guided isolation of Euphorbia lathyris followed by the structural modification led to the construction of a lathyrane diterpenoid library (1-34). Subsequent assay of this library led to the identification of a series of potent hPXR agonists, showing better efficacy than that of typical hPXR agonist, rifampicin. The most active compound, 8, could dose-dependently activate hPXR at micromolar concentrations and significantly up-regulate the expressions of PXR downstream genes CYP3A4, CYP2B6, and MDR1. The structure-activity relationships (SARs) studied in combination with molecular modeling suggested that acyloxy at C-7 and the presence of 14-carbonyl were essential to the activity. These findings suggested that lathyrane diterpenoids could serve as a new type of hPXR agonist for future anticholestasis drug development.

Xanthine oxidase activity in thiopurine curative Chinese inflammatory bowel disease patients.

Xanthine oxidase (XO) competes with thiopurine S-methyltransferase (TPMT) and hypoxanthine guanine phosphoribosyltransferase (HPRT) to metabolize azathioprine (AZA)/6-mercaptopurine (6-MP) in vivo. A retrospective investigation was performed to detect the activity of XO in thiopurine curative Chinese inflammatory bowel disease (IBD) patients. We also evaluated whether a relationship between XO activity and incidence of thiopurine-induced adverse effects (AEs) existed. Clinical data and blood samples were collected from 140 IBD patients before receiving AZA/6-MP therapy, and the erythrocyte XO activity was measured. The XO activities of all patients were 20.29 ± 4.43 U/g Hb. No sex difference in XO activity was observed (p = .728), and the XO activity showed no difference between the UC and CD patients (p = .082). AEs were observed in 41 (29.3%) patients including leukopenia (26, 18.57%), gastrointestinal intolerance (11, 7.86%), flu-like symptom (5, 3.57%), alopecia (5, 3.57%), and hepatotoxicity (1, 0.71%). XO activity was significantly lower in the patients with AEs than in those without AEs (18.40 ± 3.73 vs. 21.07 ± 4.48 U/g Hb, p = .001), especially in the patients with leukopenia (18.29 ± 3.68 vs. 21.07 ± 4.48 U/g Hb, p = .004). However, no significant difference in XO activity was found between patients with and without other AEs. Decreased XO activity was observed in the patients who developed flu-like symptoms (17.58 ± 3.50 U/g Hb) and alopecia (18.67 ± 2.91 U/g Hb) compared to those who did not, although the differences did not reach statistical significance. These findings suggested that patients with low XO expression might have a high risk of thiopurine-induced toxicity.

Schisandrol B promotes liver enlargement via activation of PXR and YAP pathways in mice.

BACKGROUND: Schisandrol B (SolB) is one of the bioactive components from a traditional Chinese medicine Schisandra chinensis or Schisandra sphenanthera. It has been demonstrated that SolB exerts hepatoprotective effects against drug-induced liver injury and promotes liver regeneration. It was found that SolB can induce hepatomegaly but the involved mechanisms remain unknown. PURPOSE: This study aimed to explore the mechanisms involved in SolB-induced hepatomegaly. METHODS: Male C57BL/6 mice were injected intraperitoneally with SolB (100 mg/kg) for 5 days. Serum and liver samples were collected for biochemical and histological analyses. The mechanisms of SolB were investigated by qRT-PCR and western blot analyses, luciferase reporter gene assays and immunofluorescence. RESULTS: SolB significantly increased hepatocyte size and proliferation, and then promoted liver enlargement without liver injury and inflammation. SolB transactivated human PXR, activated PXR in mice and upregulated hepatic expression of its downstream proteins, such as CYP3A11, CYP2B10 and UGT1A1. SolB also significantly enhanced nuclear translocation of PXR and YAP in human cell lines. YAP signal pathway was activated by SolB in mice. CONCLUSION: These findings demonstrated that SolB can significantly induce liver enlargement, which is associated with the activation of PXR and YAP pathways.

Co-administration of Wuzhi tablet (Schisandra sphenanthera extract) alters tacrolimus pharmacokinetics in a dose- and time-dependent manner in rats.

ETHNOPHARMACOLOGY RELEVANCE: Tacrolimus is a well-known potent but expensive immunosuppressant. We previously clarified the herb-drug interaction between tacrolimus and Wuzhi tablet (WZ), a prescribed drug of ethanol extract of Schisandra sphenanthera, and showed the ideal effect of WZ on maintaining therapeutic level of tacrolimus and reducing the total drug expense. However, WZ possesses a biphasic effect on regulating CYP3A (the major metabolizing enzyme of tacrolimus), which could induce the mRNA and protein expression after long-term treatment while transiently inhibit the activity of CYP3A. In clinic, clinicians are confused about the relationship between the blood concentration of tacrolimus and the dose and the duration of pretreatment of WZ. Therefore, the effects of the pretreatment time and the dose of WZ on the pharmacokinetics of tacrolimus is urgently needed to be clarified to better combine the use of WZ and tacrolimus in clinic. AIM OF THE STUDY AND METHOD: This study aimed to investigate the effects of the pretreatment time and the dose of WZ on the pharmacokinetics of tacrolimus in rats. RESULTS AND CONCLUSIONS: After pretreated rats with WZ for 0, 0.5, 2, 6, 12 or 24 h, the area under the curve (AUC) of tacrolimus was 2.27 ± 0.59, 1.87 ± 1.14, 2.86 ± 0.64, 1.62 ± 0.70, 1.54 ± 1.06 and 1.12 ± 0.69-fold of that of the tacrolimus alone group, respectively. The ratio of AUC of tacrolimus to that of the co-administration group with 0, 62.5, 125, 250, 500 or 750 mg/kg of WZ was 1.00: 1.07: 1.44: 2.60: 2.32: 2.42, respectively. These findings suggested that WZ increased tacrolimus AUC in a pretreatment time- and dose-dependent manner. In line with the in vivo findings, WZ extract inhibited CYP3A activity in a pre-treatment time- and concentration-dependent manner in human liver microsomes. In conclusion, the pharmacokinetics of tacrolimus was significantly affected by the pretreatment time and the dose of WZ. Oral pretreatment with WZ for 0-2 h or co-dosing of 250 mg/kg of WZ most significantly increased the blood concentration of tacrolimus. These findings would be helpful for guiding the reasonable use of WZ and tacrolimus in clinic.

Crotonpenoids A and B, Two Highly Modified Clerodane Diterpenoids with a Tricyclo[7.2.1.02,7]dodecane Core from Croton yanhuii: Isolation, Structural Elucidation, and Biomimetic Semisynthesis.

Crotonpenoids A (1) and B (2), two highly modified clerodane diterpenoids featuring a new 10-(butan-2-yl)-1,6,12-trimethyltricyclo[7.2.1.02,7]dodecane skeleton, were isolated from the leaves and twigs of Croton yanhuii. Their structures including the absolute configurations were determined by spectroscopic analysis, single-crystal X-ray diffraction, and biomimetic semisynthesis. Compounds 1 and 2 exhibited an agonistic effect on pregnane X receptor at 10 µM.

Targeted bile acids and gut microbiome profiles reveal the hepato-protective effect of WZ tablet (Schisandra sphenanthera extract) against LCA-induced cholestasis.

Cholestasis is caused by the obstacle of bile formation or secretion and can develop into severe liver diseases. We previously reported the ethanol extract of Schisandra sphenanthera (Wuzhi tablet, WZ) can significantly protect against lithocholic acid (LCA)-induced intrahepatic cholestasis in mice, partially due to the activation of PXR pathway and promotion of liver regeneration. However, the effect of WZ on the bile acids profile and gut microbiome in cholestastic mice remain unknown. In this study, the effect of WZ against LCA-induced liver injury was evaluated and its effect on the bile acids metabolome and gut microbiome profiles in cholestastic mice was further investigated. Targeted metabolomics analysis was performed to examine the change of bile acids in the serum, liver, intestine and feces. The change of intestinal flora were detected by the genomics method. Targeted metabolomics analysis revealed that WZ enhanced the excretion of bile acids from serum and liver to intestine and feces. Genomics analysis of gut microbiome showed that WZ can reverse LCA-induced gut microbiome disorder to the normal level. In conclusion, WZ protects against LCA-induced cholestastic liver injury by reversing abnormal bile acids profiles and alteration of gut microbiome.

Neobavaisoflavone Induces Bilirubin Metabolizing Enzyme UGT1A1 via PPARα and PPARγ.

UDP-glucuronosyltransferase 1A1 (UGT1A1) is an essential enzyme in mammals that is responsible for detoxification and metabolic clearance of the endogenous toxin bilirubin and a variety of xenobiotics, including some crucial therapeutic drugs. Discovery of potent and safe UGT1A1 inducers will provide an alternative therapy for ameliorating hyperbilirubinaemia and drug-induced hepatoxicity. This study aims to find efficacious UGT1A1 inducer(s) from natural flavonoids, and to reveal the mechanism involved in up-regulating of this key conjugative enzyme by the flavonoid(s) with strong UGT1A1 induction activity. Among all the tested flavonoids, neobavaisoflavone (NBIF) displayed the most potent UGT1A1 induction activity, while its inductive effects were confirmed by both western blot and glucuronidation activity assays. A panel of nuclear receptor reporter assays demonstrated that NBIF activated PPARα and PPARγ in a dose-dependent manner. Meanwhile, we also found that NBIF could up-regulate the expression of PPARα and PPARγ in hepatic cells, suggesting that the induction of UGT1A1 by NBIF was mainly mediated by PPARs. In silico simulations showed that NBIF could stably bind on pocket II of PPARα and PPARγ. Collectively, our results demonstrated that NBIF is a natural inducer of UGT1A1, while this agent induced UGT1A1 mainly via activating and up-regulating PPARα and PPARγ. These findings suggested that NBIF can be used as a promising lead compound for the development of more efficacious UGT1A1 inducers to treat hyperbilirubinaemia and UGT1A1-associated drug toxicities.

AMPKα1 confers survival advantage of colorectal cancer cells under metabolic stress by promoting redox balance through the regulation of glutathione reductase phosphorylation.

Patients with stage II or III colorectal cancer (CRC) exhibit various clinical outcomes after radical treatments. The 5-year survival rate was between 50 and 87%. However, the underlying mechanisms of the variation remain unclear. Here we show that AMPKα1 is overexpressed in CRC patient specimens and the high expression is correlated with poor patient survival. We further reveal a previously unrecognized function of AMPKα1, which maintains high level of reduced glutathione to keep reduction-oxidation reaction (redox) homeostasis under stress conditions, thus promoting CRC cell survival under metabolic stress in vitro and enhancing tumorigenesis in vivo. Mechanistically, AMPKα1 regulate the glutathione reductase (GSR) phosphorylation possibly through residue Thr507 which enhances its activity. Suppression of AMPKα1 by using nano-sized polymeric vector induces a favorable therapeutic effect, especially when in combination with oxaliplatin. Our study uncovers a novel function of AMPKα1 in redox regulation and identifies a promising therapeutic strategy for treatment of CRC.

Physiologically based pharmacokinetic modeling of tea catechin mixture in rats and humans.

Although green tea (Camellia sinensis) (GT) contains a large number of polyphenolic compounds with anti-oxidative and anti-proliferative activities, little is known of the pharmacokinetics and tissue dose of tea catechins (TCs) as a chemical mixture in humans. The objectives of this study were to develop and validate a physiologically based pharmacokinetic (PBPK) model of tea catechin mixture (TCM) in rats and humans, and to predict an integrated or total concentration of TCM in the plasma of humans after consuming GT or Polyphenon E (PE). To this end, a PBPK model of epigallocatechin gallate (EGCg) consisting of 13 first-order, blood flow-limited tissue compartments was first developed in rats. The rat model was scaled up to humans by replacing its physiological parameters, pharmacokinetic parameters and tissue/blood partition coefficients (PCs) with human-specific values. Both rat and human EGCg models were then extrapolated to other TCs by substituting its physicochemical parameters, pharmacokinetic parameters, and PCs with catechin-specific values. Finally, a PBPK model of TCM was constructed by linking three rat (or human) tea catechin models together without including a description for pharmacokinetic interaction between the TCs. The mixture PBPK model accurately predicted the pharmacokinetic behaviors of three individual TCs in the plasma of rats and humans after GT or PE consumption. Model-predicted total TCM concentration in the plasma was linearly related to the dose consumed by humans. The mixture PBPK model is able to translate an external dose of TCM into internal target tissue doses for future safety assessment and dose-response analysis studies in humans. The modeling framework as described in this paper is also applicable to the bioactive chemical in other plant-based health products.

[Regulation of P-glycoprotein gene expression by PKC/NF-κB-PXR signaling pathway].

P-glycoprotein (P-gp), an ATP binding cassette protein, plays a major role in efflux transport of drugs and xenobiotics due to its abundant expression on several barriers. This study aimed to investigate the potential role of PKC/NF-κB-PXR signaling pathway in modulation of P-gp gene expression in human colon adenocarcinoma LS174T. The effect of PMA on MDR1 luciferase activity was investigated by PXR-MDR1 dual luciferase reporter gene assay. Real-time qPCR assay and Western blot analysis were used to study the gene expression of P-gp and NF-κB, respectively. Compared to the vehicle-treated group, PMA statistically decreased P-gp luciferase activity, mRNA expression and protein expression. Moreover, PMA treatment yielded a significant and dose-dependent increase in RelA/p65 translocation to nucleus. Meanwhile, a remarkable increase of the pho-IκBα status was observed in LS174T cells after treatment with PMA (1-100 nmol·L(-1)). In addition, knockdown of PKCα, NF-κB or PXR can significantly attenuate PMA-induced P-gp suppression. These results suggested that PKC/NF-κB-PXR signaling pathway might play crucial roles in modulation of P-gp gene expression.

[Construction and function identification of luciferase reporter gene vectors containing SNPs in NFKBIA gene 3'UTR].

This study aims to investigate the function of two SNPs (rs8904C > T and rs696G >A) in 3' untranslated region (3'UTR) of NFKBIA gene by constructing luciferase reporter gene. A patient's genomic DNA with rs8904 CC and rs696 GA genotype was used as the PCR template. Full-length 3'UTR of NFKBIA gene was amplified by different primers. After sequencing validation, these fragments were inserted to the luciferase reporter vector, pGL3-promoter to construct recombinant plasmids containing four kinds of haplotypes, pGL3-rs8904C/rs696G, pGL3-rs8904C/rs696A, pGL3-rs8904T/rs696G and pGL3-rs8904T/rs696A. Then these plasmids were transfected into LS174T cells and the luciferase activity was detected. Compared with pGL3-vector transfected cells (negative control), the luciferase activity of the four kinds of recombinant plasmids was significantly decreased (P < 0.001). For rs696G > A, the luciferase activity of the recombinant plasmids containing A allele (pGL3-rs8904C/rs696A and pGL3-rs8904T/rs696A) was about 45.1% (P < 0.05) and 56.1% (P < 0.001) lower than those containing G allele (pGL3-rs8904C/rs696G and pGL3-rs8904T/rs696G), respectively. For rs8904C > T, there were no significant differences in the luciferase activity between the recombinant plasmids containing T allele and those with C allele. Together, the luciferase reporter gene vectors containing SNPs in NFKBIA gene 3'UTR were constructed successfully and rs696G > A could decrease the luciferase activity while rs8904C >T didn't have much effect on the luciferase activity.

Schisandrol B protects against acetaminophen-induced acute hepatotoxicity in mice via activation of the NRF2/ARE signaling pathway.

AIM: The nuclear factor erythroid 2-related factor 2 (NRF2) acts through the antioxidant response element (ARE) to regulate the expression of many detoxifying and antioxidant genes responsible for cytoprotective processes. We previously reported that Schisandrol B (SolB) isolated from Schisandra sphenanthera produced a protective effect against acetaminophen (APAP)-induced liver injury. In this study we investigated whether the NRF2/ARE signaling pathway was involved in this hepato-protective effect. METHODS: Male C57BL/6 mice were treated with SolB (200 mg · kg(-1) · d(-1), ig) for 3 d before injection of APAP (400 mg/kg, ip). Serum and liver tissue samples were collected 6 h later. The mRNA and protein expression were measured using qRT-PCR and Western blot assay, respectively. The activation of NRF2 was examined in HepG2 cells using luciferase reporter gene assay. RESULTS: SolB pretreatment significantly alleviated the hepatic injury (large patchy necrosis and hyperemia of the hepatic sinus), the increase of serum AST, ALT levels and hepatic MDA contents, and the decrease of liver and mitochondrial glutathione levels in APAP-treated mice. Furthermore, SolB pretreatment significantly increased nuclear accumulation of NRF2 and increased hepatic expression of NRF2 downstream proteins, including GCLC, GSR, NQO1, GSTs, MRP2, MRP3 and MRP4 in APAP-treated mice. Moreover, treatment with SolB (2.5-20 µmol/L) dose-dependently increased the activity of NRF2 reporter gene in HepG2 cells. CONCLUSION: SolB exhibits a remarkable protective effect against APAP-induced hepatotoxicity, partially via activation of the NRF2/ARE pathway and regulation of NRF2 target genes, which induce detoxification and increase antioxidant capacity.