Primary Porcine Hepatocytes Research Articles

Cold storage of porcine hepatocyte spheroids for spheroid bioartificial liver.

Cell-based therapies for liver disease such as bioartificial liver rely on a large quantity and high quality of hepatocytes. Cold storage was previously shown to be a better way to preserve the viability and functionality of hepatocytes during transportation rather than freezing, but this was only proved at a lower density of rat hepatocytes spheroids. The purpose of this study was to optimize conditions for cold storage of high density of primary porcine hepatocyte spheroids. Porcine hepatocytes were isolated by a three-step perfusion method; hepatocyte spheroids were formed by a 24hours rocked culture technique. Hepatocyte cell density was 5×106 /mL in 1000mL spheroid forming medium. Spheroids were then maintained in rocked culture at 37°C (control condition) or cold stored at 4°C for 24, 48 or 72hours in four different cold storage solutions: histidine-tryptophan-ketoglutarate (HTK) alone; HTK+1mM deferoxamine (DEF); HTK+5mM N-acetyl-L-cysteine (NAC); and HTK+1mM DEF+5mM NAC. The viability, ammonia clearance, albumin production, gene expression, and functional activity of cytochrome P450 enzymes were measured after recovery from the cold storage. In this study, we observed that cold-induced injury was reduced by the addition of the iron chelator. Viability of HTK+DEF group hepatocyte spheroids was increased compared with other cold storage groups (P<0.05). Performance metrics of porcine hepatocyte spheroids cold stored for 24hours were similar to those in control conditions. The hepatocyte spheroids in control conditions started to lose their ability to clear ammonia while production of albumin was still active at 48 and 72hours (P<0.05). In contrast, the viability and functionality of hepatocyte spheroids including ammonia clearance and albumin secretion were preserved in HTK+DEF group at both 48- and 72-hour time points (P<0.05). The beneficial effects of HTK supplemented with DEF were more obvious after cold storage of high density of porcine hepatocyte spheroids for 72hours. The porcine hepatocyte spheroids were above the cutoff criteria for use in a spheroid-based bioartificial liver.

Randomized Trial of Spheroid Reservoir Bioartificial Liver in Porcine Model of Posthepatectomy Liver Failure.

Acute liver failure (ALF) is a catastrophic condition that can occur after major liver resection. The aim of this study was to determine theeffects ofthe spheroid reservoir bio-artificial liver (SRBAL) on survival, serum chemistry, and liver regeneration in posthepatectomy ALF pigs. Wild-type large white swine (20 kg-30 kg) underwentintracranial pressure (ICP) probe placementfollowed by 85% hepatectomy. Computed tomography (CT) volumetrics were performed to measure the extent of resection, and at 48 hours following hepatectomy to assess regeneration of the remnant liver. Animals were randomized into three groups based on treatment delivered 24-48 hours after hepatectomy: Group1-standard medical therapy (SMT, n = 6); Group2-SMT plus bio-artificial liver treatment using no hepatocytes (0 g, n = 6); and Group3-SMT plus SRBAL treatment using 200 g of primary porcine hepatocyte spheroids (200 g, n = 6). The primary endpoint was survival to 90 hours following hepatectomy. Death equivalent was defined as unresponsive grade 4 hepatic encephalopathy or ICP greater than 20 mmHg with clinical evidence of brain herniation. All animals in both (SMT and 0 g) control groups met the death equivalent before 51 hours following hepatectomy. Five of 6 animals in the 200-g group survived to 90 hours (P < 0.01). The mean ammonia, ICP, and international normalized ratio values were significantly lower in the 200-g group. CT volumetrics demonstrated increased volume regeneration at 48 hours following hepatectomy in the 200-g group compared with the SMT (P < 0.01) and 0-g (P < 0.01) groups. Ki-67 staining showed increased positive staining at 48 hours following hepatectomy (P < 0.01). Conclusion: The SRBAL improved survival, reduced ammonia, and accelerated liver regeneration in posthepatectomy ALF. Improved survival was associated with a neuroprotective benefit of SRBAL therapy. These favorable results warrant further clinical testing of the SRBAL.

Cyadox regulates the transcription of different genes by activation of the PI3K signaling pathway in porcine primary hepatocytes.

Cyadox, a new derivative of quinoxalines, has been ascertained as an antibiotic with significant growth promoting, low poison, quick absorption, swift elimination, brief residual period, and noncumulative effect. Seven differential expressed genes, including Insulin-like Growth Factor-1 ( IGF-1), Epidermal Growth Factor ( EGF), Poly ADP-ribose polymerase ( PARP), the Defender Against Apoptotic Death 1 ( DAD1), Complement Component 3 ( C3), Transketolase ( TK) and a New gene, were induced by cyadox in swine liver tissues by messenger RNA differential display reverse transcription polymerase chain reaction (DDRT-PCR) in our laboratory. However, the signal mechanism that cyadox altered these genes expression is not completely elucidated. The signaling pathways involved in the expressions of seven genes induced by cyadox were determined in porcine primary hepatocytes by RT-qPCR and the application of various signal pathway inhibitors. 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay revealed that cyadox could stimulate proliferation of porcine primary hepatocytes in a time-dependent manner. In porcine primary cultured hepatocytes, phosphoinositide 3-kinase (PI3K) and transforming growth factor-β (TGF-β) signal pathways were the main signal pathways involved in the expressions of seven genes induced by cyadox. Taken together, these results demonstrate for the first time that seven cyadox-related genes expressions in porcine primary hepatocytes treated with cyadox are mediated mainly through the PI3K signaling pathway, potentially leading to enhanced cell growth and cell immunity. EGF might be the early response gene of cyadox, and a primary regulator of the other gene expressions such as IGF-1 and DAD1, playing an important role in cell proliferation promoted by cyadox.

Porcine interleukin-6 enhances the expression of CYP2C33 through a constitutive androstane receptor/retinoid X receptor-mediated pathway

Cytochrome P450, which is expressed in humans and other animals, is a superfamily of drug-metabolizing enzymes that play important roles in the metabolism of endogenous and xenobiotic substrates via oxidation, peroxidation and reduction. Of endogenous substrates, interleukin (IL)-6 is a crucial cytokine involved in inflammation in the liver. The present study aims to elucidate the mechanisms through which IL-6 modulates cytochrome P450 expression.CYP2C33 expression was found to be increased in HepLi cells and primary porcine hepatocytes treated with IL-6 in a concentration-dependent manner. IL-6 treatment also increased the expression of the transcriptional regulators, constitutive androstane receptor (CAR) and pregnane X receptor.Overexpression of CAR promoted CYP2C33 expression at the mRNA and protein levels, whereas knockdown of CAR by small interfering RNA reduced CYP2C33 expression. Luciferase assays showed that IL-6 treatment of HepLi cells and primary porcine hepatocytes increased CYP2C33 promoter activity. Co-immunoprecipitation and western blotting demonstrated that CAR and RXR could form heterodimers.IL-6 affects CYP2C33 expression through CAR/retinoid X receptor (RXR) heterodimers.

Decellularization and Solubilization of Porcine Liver for Use as a Substrate for Porcine Hepatocyte Culture

Biologic substrates, prepared by decellularizing and solubilizing tissues, have been of great interest in the tissue engineering field because of the preservation of complex biochemical constituents found in the native extracellular matrix (ECM). The integrity of the ECM is critical for cell behavior, adhesion, migration, differentiation, and proliferation that in turn affect homeostasis and tissue regeneration. Previous studies have shown that various processing methods have a distinctive way of affecting the composition of the decellularized ECM. In this study, we developed a bioactive substrate for hepatocytes in vitro, made of decellularized and solubilized liver tissue. The present work is a comparative approach of 2 different methods. First, we decellularized porcine liver tissue with ammonium hydroxide versus a sodium deoxycholate method, then characterized the decellularized tissue using various methods including double stranded DNA (dsDNA) content, DNA size, immunogenicity, and mass spectrometry. Second, we solubilized the decellularized porcine liver with hydrochloric acid versus acetic acid (AA) and characterized the resultant solubilized tissues using relevant methodologies including protein yield, immunogenicity, and bioactivity. Finally, we isolated primary porcine hepatocytes, cultured, and evaluated their bioactivity on the optimized decellularized–solubilized liver substrate. The decellularized porcine liver ECM processed by the ammonium hydroxide method and solubilized with AA displayed higher ECM integrity, low dsDNA, no evidence of intact nuclei, low human monocyte chemoattraction, and the presence of key molecules typically found in the native liver, a very important element for normal cell function. In addition, primary porcine hepatocytes showed enhanced functionality including albumin and urea production and bile canaliculi formation when cultured on the developed liver substrate compared to type I collagen.

Induction of cytochrome P450 mRNA in porcine primary hepatocytes cultured under serum free conditions: Comparison of freshly isolated cells and cryopreserved

Primary hepatocytes are widely used in the study of dynamic events like regulation of gene expression, as they are superior to most cell-lines. However, the culturing of the hepatocytes often results in loss of phenotype, e.g. the expression of the cytochrome p450s (CYP). The present study investigated the impact of serum in the culture medium of porcine primary hepatocytes (PPH) on markers of dedifferentiation as well as the impact on CYP induction. The effects were studied in both freshly isolated primary hepatocytes as well as cryopreserved. The exclusion of serum in the culturing media were not introducing significant dedifferentiation as judged by the gene expression of α-fetoprotein, albumin, glucose-6-phosphatase and the constitutive expression of selected transcription factors and CYP. The induction of CYP2B22 and CYP3A29 by phenobarbital and rifampicin, were greater in hepatocytes cultured without serum. The same were not observed for TCDD induced CYP1A2 expression. In conclusion, PPH cultured under serum free conditions results in little or no dedifferentiation, while being more responsive to known CYP inducers. Hence, it can be suggested that PPH cultured under serum free conditions provides a reliable hepatocyte model to investigate CYP gene regulation.

Generation of Induced Hepatocyte-Like Cells From Bone Marrow Mesenchymal Stem Cells Derived From an α1, 3-Galactosyltransferase Knockout Pig

Transplantation of porcine hepatocytes for the treatment of humans with acute and chronic liver diseases is considered an alternative to liver transplantation treatment. Especially, a bioartificial liver using porcine hepatocytes has the potential to facilitate liver transplantation for patients with acute-on-chronic liver failure. However, the use of porcine primary hepatocytes is limited by their low survivability under in vitro culture systems and complicated methods of isolation. To address this concern, we attempted to generate induced hepatocyte-like cells from bone marrow mesenchymal stem cells (BM-MSCs) derived from an α1, 3-Galactosyltransferase knockout (GalT KO) pig by transfecting three hepatocyte transcription factors (HNF1A, HNF4A, and FOXA3) and an additional small molecule such as A83-01, an inhibitor of TGF-ß receptor. BM-MSCs derived from the GalT KO pig could be used to minimize immune rejection in xenotransplantation in the future. The ratio of BM-MSCs and the three lentiviral vectors was maintained at MOI =1 and at one day post infection, they were cultured in a hepatocyte culture medium with or without 2 μM A83-01 for 4 weeks. Porcine induced hepatocyte-like cells (piHeps) were observed at a low frequency from 1 week onwards, regardless of A83-01; however, the presence of A83-01 increased the colony number of piHeps. Up to 4 weeks, piHeps maintained A83-01 treatment group but not without A83-01. qPCR analysis of liver-specific genes such as albumin and transferrin genes revealed that A83-01 improved the expression of these genes in the piHeps. Notably, A83-01 treatment could induce the activation of endogenic genes (pHNF1A, pHNF4A, and pFOXA3) in piHeps, as indicated by qPCR results. These results suggest that piHeps could be generated using the three mentioned factors, although at a low efficiency, and that A83-01 could improve the efficiency of piHep generation by the inhibition of epithelial-to-mesenchymal transition. These findings provide valuable information in the field of translational liver research and testing cells for the development of a bioartificial liver system and novel pharmaceuticals. This work was supported by the Cooperative Research Program for Agriculture Science & Technology Development (Project No. PJ01100203), RDA, Republic of Korea.

Co-treatment with indole-3-carbinol and resveratrol modify porcine CYP1A and CYP3A activities and expression

1. Humans and animals are commonly exposed to indole-3-carbinol (I3C) and resveratrol (RES) via food or beverages. Moreover, these compounds have been demonstrated to potentially cause food–drug interactions. However, information about their combined effects is limited. Therefore, we investigated the effects of I3C and RES, both as single compounds and in combination, on cytochrome P450 1A and 3A activity and gene expression.2. Using porcine microsomes, we demonstrated that RES caused non-competitive inhibition of CYP1A activity and un-competitive inhibition of CYP3A activity. Compared to the effect of single compounds, co-treatment with I3C and RES increased a degree of inhibition of CYP1A activity.3. In porcine primary hepatocytes, treatment with I3C and RES resulted in induction of CYP1A1, CYP1A2 and CYP3A29 mRNA expression.4. In conclusion, we demonstrated that both RES and I3C could cause food–drug interactions and that the combined effect could be more potent in doing so.

The dipeptide Pro-Asp promotes IGF-1 secretion and expression in hepatocytes by enhancing JAK2/STAT5 signaling pathway

It has been implicated that IGF-1 secretion can be regulated by dietary protein. However, whether the dipeptides, one of digested products of dietary protein, have influence on IGF-1 secretion remain largely unknown. Our study aimed to investigate the effects of the dipeptide Pro-Asp on IGF-1 secretion and expression in hepatocytes and to explore the possible underlying mechanisms. Our findings demonstrated that Pro-Asp promoted the secretion and gene expression of IGF-1 in HepG2 cells and primary porcine hepatocytes. Meanwhile, Pro-Asp activated the ERK and Akt signaling pathways, downstream of IGF-1. In addition, Pro-Asp enhanced GH-mediated JAK2/STAT5 signaling pathway, while inhibition of JAK2/STAT5 blocked the promotive effect of Pro-Asp on IGF-1 secretion and expression. Moreover, acute injection of Pro-Asp stimulated IGF-1 expression and activated JAK2/STAT5 signaling pathway in mice liver. Together, these results suggested that the dipeptide Pro-Asp promoted IGF-1 secretion and expression in hepatocytes by enhancing GH-mediated JAK2/STAT5 signaling pathway.

Abstract 2050: Porcine drug metabolism and toxicity in vitro model utilizing transformed hepatocyte cell lines (HepCre)

Abstract To date, in vitro cytotoxicity assays are not highly predictive of in vivo toxicity. The adverse effects of new drugs are often not discovered until preclinical animal safety studies or even clinical trials; 40% of drugs drop out in preclinical animal studies and 89% of those that reach clinical trials fail. There is a critical need for more predictive and reliable in vitro testing methods. Due to its physiological similarities with humans, pigs have emerged as a suitable and reliable animal model for pharmacological and toxicological studies. To further the pigs’ suitability, we have developed and characterized a transformed porcine hepatocyte cell line to support drug toxicity and metabolism assessments. Primary porcine hepatocytes isolated by a modified procedure of Panda's method (Panda et al., 2015) express phase I and II drug metabolism, phase-III transport, and nuclear receptors involved in regulation of drug metabolism transcripts. However, primary hepatocytes have a limited life span in culture and usually within 8 days post culture more than 50% of cells undergo apoptosis. Moreover, normal gene expression declines from day 5 in culture. To overcome these limitations, we have generated and characterized transformed hepatocyte cell lines (HepCre) derived from the transgenic Oncopig. Hepatocytes were isolated from Oncopigs (Schook et at., 2015) and transformed by treatment with Cre recombinase. When cultured in the presence of a differentiating agent (DMSO), the HepCre cell lines maintained normal hepatic functions, as well as the potential to express all the main drug metabolism and regulation genes comparable to that of cultured primary hepatocytes. The effect of model CYP (cytochrome P450) inducers (3- methylcholanthrene, rifampicin and phenobarbital) on the expression of CYP enzymes in primary hepatocytes and HepCre were studied. Treatment of 3-methylcholanthrene caused a significant upregulation of CYPA1 and CYPA2 transcripts, but the transcript of other CYPs remain unchanged. Both rifampicin and phenobarbital exposure resulted in the upregulation of several CYP transcripts, including CYP2A19, CYP2B22, and CYP3A. The gene transcription patterns in HepCre were similar to those of primary hepatocytes and in vitro human models. Toxicity responses of HepCre cells to hepatotoxic drugs (i.e. aflatoxin B1, chlorpromazine, amiodarone, and acetaminophen) was evaluated. After 72 hr of exposure, cell viability decreased in a concentration-dependent manner with IC50 of 5 μm, 50 μm, 20 μm, and 70 μm for aflatoxin B1, amiodarone, chlorpromazine, and acetaminophen, respectively. These findings indicate that this porcine transformed HepCre cell line represents a useful and predictive model for high throughput screening of new drugs as well as studies on metabolism and hepatotoxicity of chemicals.

T-2 toxin induces the expression of porcine CYP3A22 via the upregulation of the transcription factor, NF-Y

BackgroundT-2 toxin is one of the major pollutants in crops and feedstuffs. CYP3A22, one of hCYP3A4 homologs, detoxifies T-2 toxin in pigs. We investigated the mechanisms of expression activation of CYP3A22 under basal and induced conditions. MethodsBased on MatInspector analysis, several mutations in the CYP3A22 promoter were assayed by dual luciferase reporter to identify the function of cis elements in the region. EMSA experiments were used to assess the binding of transcription factors to the cis elements. The mRNA and protein levels of CYP3A22 and the transcription factors were measured by RT-qPCR and Western blot. The enhancement of NF-Y binding to the CYP3A22 promoter was assayed by ChIP. ResultsAs predicted, two cis DNA elements in the CYP3A22 promoter, a CCAAT box and GC box, were confirmed to be crucial in the activation of CYP3A22 transcription. These two DNA motifs recruited two transcription factors, NF-Y and Sp1, which are involved in the activation of the basal transcription of CYP3A22. More interestingly, CYP3A22 expression was induced in porcine primary hepatocytes by the treatment with 0.1μg/mL T-2 toxin. This induction of transcription by T-2 toxin was dominantly regulated by the binding of NF-Y to the CCAAT box, rather than GC box, which recruits Sp1 and functions only in the constitutive expression of CYP3A22. ConclusionsOur study reveals the regulatory mechanisms of both basal and inducible transactivation of CYP3A22 in pigs. In particular, we identified that the mechanism by which T-2 toxin induces CYP3A22 expression is mediated by the upregulation of NF-YA. General significanceAlthough porcine CYP3A22 is homologous to hCYP3A4, the regulation of basal and induced expression of CYP3A22 occurred via distinct mechanisms. This may account for the variety of CYP3A expression in animals and humans.

Efficacy of Fluidized Bed Bioartificial Liver in Treating Fulminant Hepatic Failure in Pigs: A Metabolomics Study.

Bioartificial livers may act as a promising therapy for fulminant hepatic failure (FHF) with better accessibility and less injury compared to orthotopic liver transplantation. This study aims to evaluate the efficacy and safety of a fluidized bed bioartificial liver (FBBAL) and to explore its therapeutic mechanisms based on metabolomics. FHF was induced by D-galactosamine. Eighteen hours later, pigs were treated with an FBBAL containing encapsulated primary porcine hepatocytes (B group), with a sham FBBAL (containing cell-free capsules, S group) or with only intensive care (C group) for 6 h. Serum samples were assayed using ultra-performance liquid chromatography-mass spectrometry. The difference in survival time (51.6 ± 7.9 h vs. 49.3 ± 6.6 h) and serum metabolome was negligible between the S and C groups, whereas FBBAL treatment significantly prolonged survival time (70.4 ± 11.5h, P < 0.01) and perturbed the serum metabolome, resulting in a marked decrease in phosphatidylcholines, lysophosphatidylcholines, sphingomyelinase, and fatty acids and an increase in conjugated bile acids. The FBBAL exhibits some liver functions and may exert its therapeutic effect by altering the serum metabolome of FHF pigs. Moreover, alginate–chitosan capsules have less influence on serum metabolites. Nevertheless, the alterations were not universally beneficial, revealing that much should be done to improve the FBBAL.

Use of a Closed Culture System to Improve the Safety of Lentiviral Vector Production.

We evaluated the possibility of introducing a combination of six oncogenes into primary porcine hepatocytes (PPH) using a lentiviral vector (LV)-mediated gene transfer in order to develop a porcine hepatocellular carcinoma model based on autologous transplantation of ex vivo-transformed hepatocytes. The six oncogenes were introduced into three plasmids, hence enabling the production of LVs encoding a luciferase reporter gene and hTERT+p53(DD), cyclinD1+CDK4(R24C), and c-myc(T58A)+HRas(G21V) genes, respectively. In order to improve the protection of the laboratory personnel manipulating such LVs, we used a compact cell culture cassette (CliniCell(®) device) as a closed cell culture system. We demonstrated that the CliniCell device allows to produce LVs, through plasmid transfection of 293T cells, and, after transfer to a second cassette, to transduce PPH with a similar efficacy as conventional open cell culture systems such as flasks or Petri dishes. Additionally, it is possible to cryopreserve at -80°C the transduced cells, directly in the CliniCell device used for the transduction. In conclusion, the use of a closed culture system for the safe handling of oncogene-encoding LVs lays the foundation for the development of porcine tumor models based on the autologous transplantation of ex vivo-transformed primary cells.

Role of Specificity Protein 1, Hepatocyte Nuclear Factor 1α, and Pregnane X Receptor in the Basal and Rifampicin-Induced Transcriptional Regulation of Porcine Cytochrome P450 3A46.

Cytochrome P450 (CYP) 3A46, one of human CYP3A4 homologs, functions as a key enzyme in the metabolism of xenobiotics in pigs. However, the regulatory mechanism for the transcriptional activation of CYP3A46 in porcine liver remains unknown. In this study, we confirmed that CYP3A46 is constitutively expressed in porcine primary hepatocytes, and its expression was significantly induced by rifampicin (RIF) instead of dexamethasone. We further found that a proximal GC box and a distal hepatocyte nuclear factor 1 (HNF1) binding site within the 5'-flanking region of CYP3A46 are the important cis-regulatory elements involved in regulating the constitutive expression of CYP3A46, via recruiting specificity protein 1 (Sp1) and HNF1α, respectively. Furthermore, we revealed that HNF1α and pregnane X receptor (PXR) activate the RIF-mediated transcription of CYP3A46 by binding to the distal HNF1 binding site and the proximal direct repeats of AGGTCA separated by 4 bases motif, respectively. Meanwhile, HNF1α is also involved in regulating RIF-induced expression of CYP3A4 through a novel distal HNF1 binding site identified in the xenobiotic-responsive enhancer module. In summary, our data demonstrate that several transcription factors, including Sp1, HNF1α, and PXR, function in the basal and RIF-mediated transcriptional regulation of CYP3A46 by binding to their related cis-regulatory elements in the proximal promoter and distal enhancer.

Development and Characterization of a Novel Anti-idiotypic Monoclonal Antibody to Growth Hormone, Which Can Mimic Physiological Functions of Growth Hormone in Primary Porcine Hepatocytes.

B-32 is one of a panel of monoclonal anti-idiotypic antibodies to growth hormone (GH) that we developed. To characterize and identify its potential role as a novel growth hormone receptor (GHR) agonist, we determined that B-32 behaved as a typical Ab2β based on a series of enzyme-linked immunosorbent assay assays. The results of fluorescence-activated cell sorting, indirect immunofluorescence and competitive receptor binding assays demonstrated that B-32 specifically binds to the GHR expressed on target cells. Next, we examined the resulting signal transduction pathways triggered by this antibody in primary porcine hepatocytes. We found that B-32 can activate the GHR and Janus kinase (2)/signal transducers and activators of transcription (JAK2/STAT5) signalling pathways. The phosphorylation kinetics of JAK2/STAT5 induced by either GH or B-32 were analysed in dose-response and time course experiments. In addition, B32 could also stimulate porcine hepatocytes to secrete insulin-like growth factors-1. Our work indicates that a monoclonal anti-idiotypic antibody to GH (B-32) can serve as a GHR agonist or GH mimic and has application potential in domestic animal (pig) production.

Deoxidation rates play a critical role in DNA damage mediated by important synthetic drugs, quinoxaline 1,4-dioxides.

Quinoxaline 1,4-dioxides (QdNOs) are synthetic agents with a wide range of biological activities. However, the mechanism of DNA damage mediated by QdNOs is far from clear. Five classical QdNOs, quinocetone (QCT), mequindox (MEQ), carbadox (CBX), olaquindox (OLA), and cyadox (CYA), were used to investigate the genotoxicity of QdNOs. The deoxidation rate of QdNOs was presumed to play a role in their genotoxicity. Deoxidation rates of QdNOs in both rat and pig liver microsomes were investigated using LC/MS-IT/TOF, and their relative quantification was achieved with HPLC. To reveal the relationships between the deoxidation rate and genotoxicity, cell damage, oxidative stress, and DNA damage were detected. Under low oxygen conditions, the rank order of the desoxy and bidesoxy rates in rat and pig liver microsomes was QCT < CBX < MEQ < OLA < CYA and QCT < MEQ < CBX < OLA < CYA, respectively. Only desoxy-quinoxalines were detected under aerobic conditions. The concentrations of deoxidized metabolites under low oxygen conditions were at least 6 times higher than those under aerobic conditions. In rats, porcine primary hepatocytes, and HepG2 cells, oxidative stress indices and DNA damage showed inverse relationships with the deoxidation rate, indicating that the deoxidation rate of QdNOs, especially bidesoxy rates, might play a critical role in mediating their ability to promote DNA damage. These results indicated that faster deoxidation of QdNOs results in lower DNA-damage-induced toxicity. Our results shed new light on the prevention of DNA damage mediated by QdNOs and help to understand the relationships among the chemical structures, metabolism, and DNA damage of QdNOs.

CCAAT-enhancer binding protein (C/EBP) β regulates insulin-like growth factor (IGF) 1 expression in porcine liver during prenatal and postnatal development.

IGF1 expression regulation attracts numerous interests because of its important role during mammalian growth and development. Domestic pig can be used as a valuable animal model to investigate human development since they share the high similarity in general physiology and metabolism. In this study, we examined the expression pattern of IGF1 and found it associated with liver C/EBP β expression pattern in porcine liver during embryonic and postnatal development. Both IGF1 and C/EBP β expression in liver maintained at low levels before birth and increased after birth. Correspondingly, C/EBP β demonstrated high binding activity to two sites at IGF1 promoter region in liver after birth. Additionally, IGF1 expression can be activated by C/EBP β overexpression in porcine primary hepatocytes. These results indicated that C/EBP β can activate IGF1 expression after birth by binding to IGF1 promoter. Our study may contribute to a better understanding of mammalian development and bring a novel anti-aging pathway in human.

IFN-γ regulates cytochrome 3A29 through pregnane X receptor in pigs

1. The expression and the activity of cytochromes P450 (CYPs) can be elevated by the activation of nuclear receptors. The pregnane X receptor (PXR, or nuclear receptor NR1I2) is a ligand-activated transcription factor that mediates responses to diverse xenobiotics and endogenous chemicals. Here we investigated the regulatory role of PXR in IFN-γ-mediated CYP3A29 expression in pig liver microsomes, primary porcine hepatocytes, and a cultured hepatocyte cell line.2. IFN-γ significantly up-regulated CYP3A29 and PXR expressions at mRNA and protein levels in a dose-dependent manner. IFN-γ treatment significantly increased the metabolism of nifedipine. PXR and IFN-γ treatments significantly enhanced the activity of CYP3A29 promoter and the upstream region from −1473 to −1021 of CYP3A29 might be PXR-binding site. Moreover, the IFN-γ-induced CYP3A29 expression was blocked by PXR knockdown, whereas CYP3A29 mRNA and protein expression levels were dramatically elevated by PXR overexpression.3. The regulatory effect of IFN-γ on CYP3A29 expression is mediated via PXR.

Pregnane X receptor is required for IFN-α-mediated CYP3A29 expression in pigs

Pregnane X receptor (PXR) has been identified as a central mediator for coordinate responses to xenobiotic and drug metabolism, and is the major transcriptional regulator of cytochrome P-450 (CYP). Interferon (IFN)-α is known to induce antiviral mechanisms and exert immune regulatory capacity in various cell types. Here, we used primary porcine hepatocytes and a cultured hepatocyte cell line to identify the metabolic role of PXR in IFN-α-mediated CYP3A29 expression. We found that IFN-α could activate PXR in both time- and dose-dependent manners in pigs. Activation of PXR significantly increased CYP3A29 mRNA and protein expression. Meanwhile, the expression of CYP3A29 induced by IFN-α occurred after the increase of PXR expression in porcine hepatocytes. In addition, the IFN-α-induced CYP3A29 expression was blocked by PXR knockdown. The PXR-overexpressed cells (transfected with porcine PXR) increased CYP3A29 mRNA and protein expression. Furthermore, in animal experiments, we found that IFN-α increased both CYP3A29 mRNA and protein levels. Collectively, our results suggest that PXR plays an important role in IFN-α-mediated CYP3A29 expression in porcine hepatocytes.

Potential Interactions of Herbal Extracts of St. John´s Wort with Metabolites of Diazepam in an Organotypical Sandwich Culture of Primary Porcine Hepatocytes

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