Activation of PXR causes drug interactions with Paxlovid in transgenic mice

Paxlovid is a nirmatrelvir (NMV) and ritonavir (RTV) co-packaged medication used for the treatment of coronavirus disease 2019 (COVID-19). The active component of Paxlovid is NMV and RTV is a pharmacokinetic booster. Our work aimed to investigate the drug/herb-drug interactions associated with Paxlovid and provide mechanism-based guidance for the clinical use of Paxlovid. By using recombinant human cytochrome P450s (CYPs), we confirmed that CYP3A4 and 3A5 are the major enzymes responsible for NMV metabolism. The role of CYP3A in Paxlovid metabolism were further verified in Cyp3a-null mice, which showed that the deficiency of CYP3A significantly suppressed the metabolism of NMV and RTV. Pregnane X receptor (PXR) is a ligand-dependent transcription factor that upregulates CYP3A4/5 expression. We next explored the impact of drug- and herb-mediated PXR activation on Paxlovid metabolism in a transgenic mouse model expressing human PXR and CYP3A4/5. We found that PXR activation increased CYP3A4/5 expression, accelerated NMV metabolism, and reduced the systemic exposure of NMV. In summary, our work demonstrated that PXR activation can cause drug interactions with Paxlovid, suggesting that PXR-activating drugs and herbs should be used cautiously in COVID-19 patients receiving Paxlovid.

Activating Effect of Effective Components in Medicinal and Edible Substances on Human Pregnane X Receptor and Cytotoxicity Screening / 中国实验方剂学杂志

ObjectiveTo explore the activating effects of ten important effective components in seven medicinal and edible substances on human pregnane X receptor （PXR）， including Glycyrrhizae Radix et Rhizoma （liquiritin and glycyrrhizic acid）， Houttuyniae Herba （quercetin and houttuyfonate）， Prunellae Spica （rosmarinic acid）， Cassiae Semen （aurantio-obtusin）， Poria （pachymic acid）， Lilii Bulbus （Lilium brownii saponin and colchicine）， and Lycii Fructus （Lycium barbarum polysaccharide） and screen potentially toxic components. MethodCell counting kit-8 （CCK-8） assay was used to investigate the cytotoxic effect of liquiritin， glycyrrhizic acid， quercetin， houttuyfonate， rosmarinic acid， pachymic acid， aurantio-obtusin， and colchicine （10， 20， and 50 μmol·L-1）， and L. brownii saponin and L. barbarum polysaccharide （10， 20， and 50 mg·L-1） on normal human hepatocyte cell line （L02）. The release of lactate dehydrogenase （LDH） in L02 cells after drug treatments was detected by the biochemical analyzer. The apoptosis induced by ten effective components was explored by Hoechst 33342 staining. The secreted luciferase reporter system was used to co-transfect the PXR expression vector and reporter gene vector containing cytochrome P450 3A4 （CYP3A4） transcriptional regulatory region into L02 cells， with 10 μmol·L-1 rifampicin （RIF） as a positive control. After treated with liquiritin， glycyrrhizic acid， quercetin， houttuyfonate， rosmarinic acid， aurantio-obtusin， pachymic acid， and colchicine （5， 10， and 20 μmol·L-1） and L. brownii saponin and L. barbarum polysaccharide （5， 10， and 20 mg·L-1） for 24 h， the cells were tested for secreted luciferase activity. ResultCompared with the control group， colchicine， L. brownii saponin， and quercetin decreased the cell viability （P<0.05， P<0.01）. Compared with the control group， quercetin， rosmarinic acid， glycyrrhizic acid， colchicine， aurantio-obtusin， and pachymic acid increased the release rate of LDH in L02 cells （P<0.05， P<0.01）. The proportion of hyperchromatic nuclei increased gradually after rosmarinic acid， liquiritin， and L. barbarum polysaccharide treatments as compared with the control group （P<0.05， P<0.01）. In terms of co-transfection of pcDNA3.1-PXR and pGLuc-CYP3A4 into L02 cells， compared with the control group， aurantio-obtusin and pachymic acid showed activating effects on PXR （P<0.05）， whereas liquiritin and glycyrrhizic acid showed inhibitory effects （P<0.05）. ConclusionThe findings suggest that when medicinal and edible substances are taken for a long time， attention should be paid to their influence on drug-metabolizing enzymes and possible interactions， so as to improve their safety.

PXR activation impairs hepatic glucose metabolism partly via inhibiting the HNF4α-GLUT2 pathway

Drug-induced hyperglycemia/diabetes is a global issue. Some drugs induce hyperglycemia by activating the pregnane X receptor (PXR), but the mechanism is unclear. Here, we report that PXR activation induces hyperglycemia by impairing hepatic glucose metabolism due to inhibition of the hepatocyte nuclear factor 4-alpha (HNF4α)‒glucose transporter 2 (GLUT2) pathway. The PXR agonists atorvastatin and rifampicin significantly downregulated GLUT2 and HNF4α expression, and impaired glucose uptake and utilization in HepG2 cells. Overexpression of PXR downregulated GLUT2 and HNF4α expression, while silencing PXR upregulated HNF4α and GLUT2 expression. Silencing HNF4α decreased GLUT2 expression, while overexpressing HNF4α increased GLUT2 expression and glucose uptake. Silencing PXR or overexpressing HNF4α reversed the atorvastatin-induced decrease in GLUT2 expression and glucose uptake. In human primary hepatocytes, atorvastatin downregulated GLUT2 and HNF4α mRNA expression, which could be attenuated by silencing PXR. Silencing HNF4α downregulated GLUT2 mRNA expression. These findings were reproduced with mouse primary hepatocytes. Hnf4α plasmid increased Slc2a2 promoter activity. Hnf4α silencing or pregnenolone-16α-carbonitrile (PCN) suppressed the Slc2a2 promoter activity by decreasing HNF4α recruitment to the Slc2a2 promoter. Liver-specific Hnf4α deletion and PCN impaired glucose tolerance and hepatic glucose uptake, and decreased the expression of hepatic HNF4α and GLUT2. In conclusion, PXR activation impaired hepatic glucose metabolism partly by inhibiting the HNF4α‒GLUT2 pathway. These results highlight the molecular mechanisms by which PXR activators induce hyperglycemia/diabetes.

Dynamic change of hepatocyte during PXR-induced liver enlargement / 药学学报

Pregnane X receptor (PXR), a member of nuclear receptor superfamily, plays an important role in xenobiotic and endogenous metabolism, endocrine balance, and cell proliferation, etc. Previous study has shown that pregnenolone 16α-carbonitrile (PCN), a mouse PXR agonist, could induce liver enlargement. And we found that the change in hepatocytes exhibits regional distribution characteristics: hepatocyte enlargement occurs around the central vein (CV) area, while hepatocyte proliferation occurs around the portal vein (PV) area. In this study, the dynamic changes of hepatocytes during PXR-induced liver enlargement were determined. Serum and liver samples from male C57BL/6 mice were collected for biochemical and pathological analysis after PCN treatment for 1, 2, 3, 5 days, respectively. The animal experiment was approved by the Animal Ethics Committee of Sun Yat-Sen University. The results showed that with the increase in the PCN treatment days, the feature of this regional change of hepatocyte around the CV and PV areas became more and more obvious. At the same time, the factors related to hepatocyte enlargement, such as the expression of PXR downstream genes and the hepatic content of triglyceride (TG), has gradually increased. The upregulation of proliferation-related proteins and downregulation of cyclin-dependent kinases inhibitor proteins were observed in the early stage of PCN treatment, suggesting that hepatocyte proliferation occurs earlier than hepatocyte enlargement during PXR-induced liver enlargement. This study reveals the dynamic change of hepatocytes during PXR-induced liver enlargement and provides a new insight in liver enlargement promoted via PXR activation.

Anticonvulsivantes y su efecto en el metabolismo de la vitamina D: revisión del tema, a propósito de un caso / Anticonvulsants and their effect on the metabolism of vitamin D: literature review with case report

La epilepsia es una enfermedad neurológica frecuente que afecta a cerca de 50.000 millones de personas en el mundo. En Chile, la prevalencia estimada es de 10.8 a 17 por 1.000 habitantes. La primera opción para su tratamiento son los fármacos antiepilépticos (FAE) los cuales logran un aceptable control de enfermedad en la mayoría de los casos, sin embargo, tienen la potencialidad de desencadenar una serie de efectos adversos destacando entre ellos el desarrollo de hipocalcemia (HC) secundaria a hipovitaminosis D (HD), alteración que por lo general es leve y asintomática. Presentamos el caso de una mujer perimenopausica con antecedente de epilepsia en tratamiento con anticonvulsivante que desarrolla hipocalcemia severa. Además revisamos los mecanismos descritos a través de los cuales los FAE afectan el metabolismo de esta vitamina.

Epilepsy is a common neurological disease that affects about 50,000 million people in the world. The estimated prevalence is 10.8 to 17 per 1.000 inhabitants in Chile. The first option for its treatment are antiepileptic drugs (AEDs) which achieve an acceptable control of the disease in most cases, however, they have the potential to trigger a series of adverse effects (AE) highlighting among them the development of hypocalcemia (HC) secondary to hypovitaminosis D (HD), an alteration that is generally mild and asymptomatic. We present the case of a perimenopausal woman with a history of epilepsy under treatment with an anticonvulsant who develops severe hypocalcemia. We also review the mechanisms described through which AEDs affect the metabolism of this vitamin.

Effect of six components in Polygoni Multiflori Radix on regulation of CYP3A4 mediated by human pregnane X receptor / 中国中药杂志

This paper aimed to study the six chemical components of Polygoni Multiflori Radix (gallic acid, quercetin, luteolin, kaempferol, resveratrol, apigenin). By the established pregnane X receptor (human pregnant X receptor, PXR) CYP3A4 mediated drug induced rapid screening technique, the effect of chemical components on the cell activity was detected by MTS cell method, and the value of IC₅₀ was calculated. The dual luciferase reporter system was used to co-transfect PXR reporter gene expression vector containing transcriptional regulation and CYP3A4 with HepG2 cells, with 10 μmol·L⁻¹ rifampicin (RIF) as a positive control, and 10 μmol·L⁻¹ of ketoconazole (TKZ) as negative control. Gallic acid, quercetin, luteolin, kaempferol, apigenin, resveratrol(5, 10, 20 μmol·L⁻¹) were used to incubate for 24 h, and the luciferase activity was detected. The results showed that when plasmid pcDNA3.1 was co-transfected with pGL4.17-CYP3A4, gallic acid and resveratrol had an inhibitory effect on the regulation of CYP3A4, and quercetin, luteolin, kaempferol had an inductive effect on CYP3A4; when pcDNA3.14-PXR was co-transfected with pGL4.17-CYP3A4, quercetin, luteolin, kaempferol, apigenin, resveratrol had an inductive effect. To sum up, the 6 reported liver injury components had inhibitory or activating effects on CYP3A4. After PXR plasmid was involved, 5 components had an inductive effect on CYP3A4, and the inductive effects of 2 components were significantly different. In this experiment, we found that 2 kinds of potential liver injury components in Polygoni Multiflori Radix had been induced by CYP3A4, which was achieved through PXR regulation. It suggested that attention shall be paid to potential drug interactions when combined with Polygoni Multiflori Radix, so as to improve the safety and efficacy.

Mechanism of Berberine in the Regulation of CYP3A4 and P-gp via PXR Signaling Pathway / 中国药师

Objective: To investigate the regulation of CYP3A4 and P-gp by berberine hydrochloride ( BBR) via pregnane X re-ceptor (PXR) pathway. Methods: pLKO. 1-PXR vector, a lentivirus plasmid expressing PXR shRNA, was packaged into 293T cells. Human hepatoma (HepG2) cells were infected with the lentivirus and the cell clones stably expressing PXR shRNA were selected by puromycin according to pLKO. 1 vector characteristics. Real-time RT-PCR and Western blot were used to evaluate CYP3A4 and P-gp mRNA and protein in berberine treated HepG2 cells and PXR-silenced HepG2 cells. Results: The PXR expression in PXR silenced cells significantly decreased (P<0.01) when compared with that in HepG2 cells, while there was no significant difference (P >0. 05) in the expression of CYP3A4 and P-gp between the groups. Compared with that in HepG2 cells, the inhibition of berberine on the mRNA and protein expression of CYP3A4 and P-gp in PXR-silenced HepG2 cells was weakened (P<0. 05 or P<0. 01). Conclu-sion: Berberine can regulate the expression of CYP3A4 and P-gp via PXR signaling pathway, while it is not the only one.

Neonatal activation of Pxr results in persistent altered expression of DMEs in adult mice / 中国药理学与毒理学杂志

OBJECTIVE To demonstrate the long-or short-term impacts of neonatal Pxr(pregnane X receptor) agonists exposureon DMEs (drug metabolism enzymes) expression in adulthood. METHODS C57BL/6 mice(day 5,postnatal)were injected with different doses(0,50,100,150,200 mg·kg-1·d-1, constitutive 4 d)of PCN(pregnenolone-16a-carbonitrile).Mice at different ages(day 5,10,15,25,postna-tal)were administrated with 200 mg·kg-1·d-1PCN in constitutive 4 d.All mice were sacrificed at day 60 after birth. Liver samples were collected for detecting the expression of Pxr target genes. RESULTS Compared with vehicle group, the significant inductions of Cyp2b10, Cyp3a11 and Pxrwere observed in high dose groups (150, 200 mg·kg-1·d-1, 5-8 d after birth) both in male and female mice (n=4-9/group,P<0.05).Furthermore,high dose groups(200 mg·kg-1·d-1,5-8 d after birth)were found to have higher mRNA expression levels of Cyp2a4,Ugt1a1,Abcc4,and Oatpla4 in female mice,while Papss2 in male mice compared with vehicle groups (n= 4-9/group, P<0.05). Interestingly, a decreased mRNA expression of Sult2a1 was identified in 200 (5-8 d) groups (n=4-9/group, P<0.05). Consistent with these results, the protein expression of Cyp3a11 was only increased in 200 (5-8 d) groups compared with the vehicle groups(n=3/group,P<0.05).Importantly,the persistent impacts on DMEs only occurred in day 5 and day 25 treatment groups,not day 10 and day 15 groups(n=4/group).CONCLUSION Neonatal Pxr activation has a long-term effect on the expression of DMEs in C57BL/6 mice.Dose and treatment exposure time are two key factors involved in this permanent alteration procedure.

Protective Effects of Matrine on α-Naphthl Isocyanate-Induced Cholestatic Liver Injury in Rats / 中国药学杂志

OBJECTIVE: To investigate the preventive protective effect of matrine(MT) on α-naphthl isocyanate(ANIT)-induced cholestasis in rat, and to explore its possible mechanism. METHODS: Thirty SD rats were randomly divided into five groups with six rats in each group: normal control group, model group, low dose matrine(5 mgkg-1), high dose matrine group(10 mgkg-1) and positive control group(ursodeoxycholic acid 100 mgkg-1), which were administered continuously for 7 d. All groups except the normal control group were given 60 mgkg-1 ANIT at the fifth day. After the last administration, all rats were fasted 24 h and arterial blood were collected to detect the indexes of total bilirubin(TBIL), aspartate aminotransferase(AST), alanine aminotransferase(ALT) and alkaline phosphatase(ALP). The livers were picked for HE staining, immunohistochemistry(IHC) analysis and Western blot(WB), to indentify the protein expressions of CYP3A4 and PXR. RESULTS: Compared to model group, low-dose and high-dose matrine decreased TBIL, AST, ALT and ALP significantly; IHC analysis showed that the expression of CYP3A4 in high-dose group was significantly higher than that in model group(P<0.05). The results of WB showed that the expressions of CYP3A4 and PXR in two matrine groups were significantly higher than that in model group(P<0.05), however, only CYP3A4 expression in UDCA group was significantly higher than that in model group(P<0.05). CONCLUSION: Matrine could improve cholestatic liver injury in rats and its mechanism might be related to the upregulation of CYP3A4 expression controled by inducing PXR expression.

Effects of downregulated pregnane X receptor on glutamate-induced expression and activity of P-glycoprotein in the mouse brain microvascular endothelial cells / 临床神经病学杂志

Objective To investigate the effects of downregulated pregnane X receptor (PXR)on expression and activity of P-glycoprotein(P-gp)in mouse brain microvascular endothelial cells (mBMEC)exposed to glutamate (GLU)to mimic conditions during seizures. Methods The bEnd.3 cells,were cultured in vitro and treated with culture medium containing 0 μmol,10 μmol,50 μmol,100 μmol GLU for 30 min and exposed to 100 μM GLU for different durations (0 min,15 min,30 min). With PXR knockdown using siRNA,the cells were divided into NC siRNA plus GLU group and siRNA-PXR plus GLU group. Western blotting was used to detect the protein expressions of P-gp and PXR in each group. Immunofluorescence assay was used to detect localization of PXR in cells. The expression of P-gp mRNA was detected by RT-qPCR. Rhodamine123 (Rh123)accumulation assay was used to study the activity of the P-gp in cells.Results PXR and P-gp protein expressions in the 50 μmol and 100 μmol GLU group were significantly higher than that in the blank group(P＜0.05),especially maximal expressions occurred in the 100 μmol GLU group. GLU exposures as short as 15 min and 30 min significantly increased PXR expressions(all P＜0.05);P-gp expression in the 30 min groups was higher than that in the blank group (P＜0.05 ). The data of immunofluorescence analysis suggested that the PXR nuclear accumulation increased in the 100 μM GLU group, compared with the blank group(P＜0.05). Compared with NC siRNA plus GLU group,the protein level of PXR was decreased by approximately 37%[(1.00 ± 0.00)vs(0.63 ± 0.18);t＝3.41,P＝0.02]and the levels of P-gp protein and mRNA were respectively decreased by 43%[(1.00 ± 0.00)vs (0.57 ± 0.09);t＝7.94,P＝0.00] and 52%[(1.00 ± 0.04)vs (0.48 ± 0.08);t ＝10.98,P＝0.00]in the siRNA-PXR plus GLU group. The fluorescence intensity of intracellular Rh123 in the GLU group (0.72 ± 0.01)was lower than that in the blank group [(1.00 ± 0.03);t ＝9.66,P＝0.00]. The fluorescence intensity of Rh123 in the GLU plus verapamil (P-gp inhibitor)group (1.07 ± 0.04)was higher than that in the GLU group (t＝ －11.93,P＝0.00). The fluorescence intensity of Rh123 in the siRNA-PXR plus GLU group (0.91 ± 0.03)was higher than that in the NC siRNA plus GLU group[(0.69 ± 0.05);t＝ －7.52,P＝0.00]. Conclusions Downregulation of PXR expression results in the inhibition of P-gp expression and activity in the mBMEC exposed to GLU to mimic seizures. PXR may play an important role in the regulation of seizure-induced expression and activity of P-gp in the blood-brain barrier.

Regulation of P-glycoprotein gene expression by PKC/NF-κB-PXR signaling pathway / 药学学报

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.

In silico investigation of agonist activity of a structurally diverse set of drugs to hPXR using HM-BSM and HM-PNN / 华中科技大学学报（医学）（英德文版）

The human pregnane X receptor (hPXR) plays a critical role in the metabolism, transport and clearance of xenobiotics in the liver and intestine. The hPXR can be activated by a structurally diverse of drugs to initiate clinically relevant drug-drug interactions. In this article, in silico investigation was performed on a structurally diverse set of drugs to identify critical structural features greatly related to their agonist activity towards hPXR. Heuristic method (HM)-Best Subset Modeling (BSM) and HM-Polynomial Neural Networks (PNN) were utilized to develop the linear and non-linear quantitative structure-activity relationship models. The applicability domain (AD) of the models was assessed by Williams plot. Statistically reliable models with good predictive power and explain were achieved (for HM-BSM, r (2)=0.881, q LOO (2) =0.797, q EXT (2) =0.674; for HM-PNN, r (2)=0.882, q LOO (2) =0.856, q EXT (2) =0.655). The developed models indicated that molecular aromatic and electric property, molecular weight and complexity may govern agonist activity of a structurally diverse set of drugs to hPXR.

Pregnane receptor gene polymorphisms, pathogenic bacteria distribution and drug sensitivity, and TCM syndrome differentiation in patients with cholelithiasis

OBJECTIVE@#To investigate the distribution of pathogens and drug resistance in bile and the association between the pregnane X receptor (PXR) gene polymorphisms, traditional Chinese medicine (TCM) syndromes and the risk of cholesterol gallstone disease (CGD).@*METHODS@#A total of 392 samples were enrolled in this study from January 2014 to February 2015, among which 192 patients were with CGD, and 200 samples were healthy. Strains were isolated and susceptibility testing was the disk diffusion method susceptibility testing. The patients were divided into hepatochlic hygropyrexia, stagnation of liver-qi, and the accumulation of damp. The PXR gene polymorphisms were analyzed by polymerase chain reaction-restriction fragment length polymorphism. The association between the PXR gene polymorphisms and the risk of CGD was examined by logistic regression analysis.@*RESULTS@#A total of 192 cases were detected in 230 of bile culture pathogens, including Gram-negative bacteria 133 (57.83%), Gram-positive bacteria 76 (33.04%), and fungi 21 (9.13%). The top five pathogens were Escherichia coli, Klebsiella pneumoniae, Enterococcus faecalis, Candida albicans, and Enterococcus feces, of which 110 cases was of single infection, 48 cases of mixed infection of two strains, eight cases of mixed infection of three bacteria. Among 59 Escherichia coli, the yield extended-spectrum beta-lactamases had 40 (67.80%). The hepatochlic hygropyrexia was the most TCM syndrome, followed by stagnation of liver-qi, and the accumulation of damp was least. Different pathogens and the rs6785049 genotypes distributed differently in cholelithiasis patients with different TCM syndromes (P < 0.05). In hepatochlic hygropyrexia patients the Gram-negative bacteria was most. There was significant differences between CGD group and control group in rs6785049 (P < 0.001). Comparison with wild-type portable GG, GA genotype increased the risk of the occurrence of gallstones (OR = 0.40, 95%CI: 0.16-0.79); likewise, carrying the GA+AA genotype also increased the risk (OR = 0.38, 95%CI: 0.19-0.81). There was no significant differences in rs2276707, rs3814055 site polymorphic loci alleles in CGD group and control group.@*CONCLUSIONS@#In the treatment of cholelithiasis, bile samples should be collected for bacterial culture and sensitivity test, and drugs should be strictly chosen based on the results. The rs6785049 polymorphisms in PXR gene may increase the risk of gallstones ontogeny, and gallstones can be early detected and prevented by detecting genotypes. rs6785049 polymorphisms in PXR gene may has relationship with TCM syndromes.

Pregnane receptor gene polymorphisms, pathogenic bacteria distribution and drug sensitivity, and TCM syndrome differentiation in patients with cholelithiasis

Objective: To investigate the distribution of pathogens and drug resistance in bile and the association between the pregnane X receptor (PXR) gene polymorphisms, traditional Chinese medicine (TCM) syndromes and the risk of cholesterol gallstone disease (CGD). Methods: A total of 392 samples were enrolled in this study from January 2014 to February 2015, among which 192 patients were with CGD, and 200 samples were healthy. Strains were isolated and susceptibility testing was the disk diffusion method susceptibility testing. The patients were divided into hepatochlic hygropyrexia, stagnation of liver-qi, and the accumulation of damp. The PXR gene polymorphisms were analyzed by polymerase chain reaction-restriction fragment length polymorphism. The association between the PXR gene polymorphisms and the risk of CGD was examined by logistic regression analysis. Results: A total of 192 cases were detected in 230 of bile culture pathogens, including Gram-negative bacteria 133 (57.83%), Gram-positive bacteria 76 (33.04%), and fungi 21 (9.13%). The top five pathogens were Escherichia coli, Klebsiella pneumoniae, Enterococcus faecalis, Candida albicans, and Enterococcus feces, of which 110 cases was of single infection, 48 cases of mixed infection of two strains, eight cases of mixed infection of three bacteria. Among 59 Escherichia coli, the yield extended-spectrum beta-lactamases had 40 (67.80%). The hepatochlic hygropyrexia was the most TCM syndrome, followed by stagnation of liver-qi, and the accumulation of damp was least. Different pathogens and the rs6785049 genotypes distributed differently in cholelithiasis patients with different TCM syndromes (P < 0.05). In hepatochlic hygropyrexia patients the Gram-negative bacteria was most. There was significant differences between CGD group and control group in rs6785049 (P < 0.001). Comparison with wild-type portable GG, GA genotype increased the risk of the occurrence of gallstones (OR = 0.40, 95%CI: 0.16-0.79); likewise, carrying the GA+AA genotype also increased the risk (OR = 0.38, 95%CI: 0.19-0.81). There was no significant differences in rs2276707, rs3814055 site polymorphic loci alleles in CGD group and control group. Conclusions: In the treatment of cholelithiasis, bile samples should be collected for bacterial culture and sensitivity test, and drugs should be strictly chosen based on the results. The rs6785049 polymorphisms in PXR gene may increase the risk of gallstones ontogeny, and gallstones can be early detected and prevented by detecting genotypes. rs6785049 polymorphisms in PXR gene may has relationship with TCM syndromes.

A brief history of the discovery of PXR and CAR as xenobiotic receptors

The nuclear receptors pregnane X receptor (PXR) and constitutive androstane receptor (CAR) were cloned and/or established as xenobiotic receptors in 1998. Due to their activities in the transcriptional regulation of phase I and phase II enzymes as well as drug transporters, PXR and CAR have been defined as the master regulators of xenobiotic responses. The discovery of PXR and CAR provides the essential molecular basis by which drugs and other xenobiotic compounds regulate the expression of xenobiotic enzymes and transporters. This article is intended to provide a historical overview on the discovery of PXR and CAR as xenobiotic receptors.

PXR Mediated Protection against Liver Inflammation by Ginkgolide A in Tetrachloromethane Treated Mice

The pregnane X receptor (PXR), a liver and intestine specific receptor,, has been reported to be related with the repression of inflammation as well as activation of cytochromosome P450 3A (CYP3A) expression. We examined the effect of PXR on tetrachloromethane (CCl4)-induced mouse liver inflammation in this work. Ginkgolide A, one main component of Ginkgo biloba extracts (GBE), activated PXR and enhanced PXR expression level, displayed both significant therapeutic effect and preventive effect against CCl4-induced mouse hepatitis. siRNA-mediated decrease of PXR expression significantly reduced the efficacy of Ginkgolide A in treating CCl4-induced inflammation in mice. Flavonoids, another important components of GBE, were shown anti-inflammatory effect in a different way from Ginkgolide A which might be independent on PXR because flavonoids significantly inhibited CYP3A11 activities in mice. The results indicated that anti-inflammatory effect of PXR might be mediated by enhancing transcription level of IkappaBalpha through binding of IkappaBalpha. Inhibition of NF-kappaB activity by NF-kappaB-specific suppressor IkappaBalpha is one of the potential mechanisms of Ginkgolide A against CCl4-induced liver inflammation.

Application of pregnane X receptor′s regulation of induction of cytochrome P-450 CYP3A to incompatibility of traditional Chinese medicine and toxicity predetermination / 中国药理学与毒理学杂志

The incompatibility of traditional Chinese medicine is an important part of traditional Chinese medicine compatibility theory,while early toxicity predetermination of traditional Chinese medi?cine is an important component of drug safety evaluation. Once a simple and reliable method to predict the compatibility of Chinese medicine and Chinese traditional medicine is established,it is possible to obtain the data of toxic reaction of Chinese herbal medicine quickly and early. Pregnane X receptor (PXR)is a ligand dependent transcription factor,acting as a ligand or activator of a large number of clinical drugs and of cytochrome P-450 CYP3A (CYP3A) gene expression induced by PXR. In the course of treatment of diseases,the activation of PXR may increase the risk of drug interactions and adverse reactions,resulting in decreased efficacy and even toxicity. This paper may provide a new method of drug toxicity predetermination depending on the PXR-CYP3A pathway.

Study of Clotrimazole on Cell Apoptosis in Rat Liver After Ischemia-reperfusion Injury / 医药导报

Objective To investigate the effect of clotrimazole on apoptosis of hepatic cells after ischemia-reperfusion injury and its mechanism. Methods Hepatic ischemia-reperfusion rat model was established. Thirty-two male Sprague-Dawley rats were randomly allocated into sham-operated group, model control group, low dose clotrimazole group and high dose clotrimazole group. Apoptosis in hepatic tissue was assessed by TUNEL method. Protein expression levels of CYP3A1,Bcl-2,Bax and PARP were measured by Western blotting. Results As compared with model control group, the apoptosis rate, tissue injury,activity of plasma enzymes and the Bax/Bcl-2 expression ratio were reduced in low and high dose clotrimazole groups. The apoptotic index in both clotrimazole-treated groups was lower than that of model control group with statistically significant difference. CYP3A1 expression was significantly induced by clotrimazole compared to the sham-operated group. Conclusion Clotrimazole may inhibit apoptosis of hepatic cells by up-regulating Bcl-2 and down-regulating Bax, thus produce a protective effect on hepatic ischemia-reperfusion injury and it is also related to the inhibition of PARP shear.

Ginkgolide B induces CYP3 A4 expression through activation of human pregnane X receptor / 中国药理学通报

Aim To study the induction effect of Ginkgolide B on CYP3A4,and further verify the role of pregnane X receptor in CYP3 A4 induction expres-sion. Methods With different concentrations of Ginkgolide B treatment on LS174T cells,the CYP3A4 mRNA expression was detected by Q-PCR assay,fur-ther PXR-CYP3 A4 stable translation HepG2 cell lines were used to test the effect of Ginkgolide B on activity of PXR by reporter gene screening assay.CYP3A4 protein expression was detected by Western blot.PXR was knocked down with transfected with siRNA, CYP3 A4 mRNA and protein were detected in the con-dition of PXR low expression.Results The results revealed that the level of CYP 3 A 4 gene and protein expression were significantly increased by Ginkgolide B,and there was no induction effect on PXR.Reporter gene screening showed that Ginkgolide B could en-hance the transcriptional activity of PXR in a concen-tration-dependent manner.Under conditions of low ex-pression of PXR ,Ginkgolide B could also increase ex-pression of CYP3A4,but the induction folds were low-er than those of normal PXR group.Conclusion Ginkgolide B can signicantly up-regulate CYP3 A4 ex-pression via the PXR-CYP3 A4 pathway,and it has no effects on PXR gene expression.

Establishment of hPXR mediated reporter gene model for UGT1A1 and its application / 中国药学杂志

OBJECTIVE: To develop hPXR mediated reporter gene model for UGT1A1, and use it as an in vitro model for determination of induction activity toward UGT1A1 of various commonly used traditional Chinese medicines (TCMs) extracts. METHODS: The distal and proximal promoters of UGT1A1 were amplified from human genetic DNA, and were cloned into pGL3 vector as pGL3-PXRE plasmid, which was then cotransfected into HepG2 cells with hPXR expression plasmid to establish the reporter gene model. Then the model was applied to determine the induction activity toward UGT1 A1 of various commonly used TCMs extracts. RESULTS: The promoters of UGT1A1 were successfully cloned into pGL3 vector to form pGL3-PXRE recombinant plasmid, and the reporter gene model was successfully established. Nine kinds of TCMs extracts were investigated, and three were found to activate hPXR and therefore have the potential to induce UGT1A1. CONCLUSION: The model established is an effective method for determination of activators of hPXR and potential inducers of UGT1A1 in vitro. Copyright 2012 by the Chinese Pharmaceutical Association.