Potential impact of steatosis on cytochrome P450 enzymes of human hepatocytes isolated from fatty liver grafts.

Liver grafts discarded for transplantation because of macrosteatosis can constitute a valuable source of human hepatocytes for in vitro metabolic and pharmacotoxicological studies or for therapeutic applications. A condition for using hepatocyte suspensions for these purposes is the preservation of their metabolic competence and, particularly, drug-metabolizing enzymes. A reduction in microsomal cytochrome P450 (P450) activities was observed in fatty livers (>40% steatosis) with respect to normal tissue. Similarly, decreased levels of 7-ethoxycoumarin O-deethylation and testosterone metabolism were observed in human hepatocyte cultures prepared from steatotic liver tissue. To clarify the potential impact of lipid accumulation on human hepatic P450 enzymes, we have used an in vitro model of "cellular steatosis" by incubation of cultured hepatocytes with increasing concentrations (0.25-3 mM) of long-chain free fatty acids (FFA). A dose-dependent accumulation of lipids in the cytosol is induced by FFA mixture. Hepatocytes exposed to 1 mM FFA for 14 h showed lower activity values of CYP1A2, CYP2A6, CYP2B6, CYP2C9, CYP2D6, CYP2E1, and CYP3A4 enzymes than nontreated hepatocytes (about 45-65% reduction). This treatment also produced significant decreases in CYP1A2, CYP2A6, CYP2C9, CYP2D6, CYP2E1, and CYP3A4 mRNA to about 55 to 75% of mRNA levels in control cells. Our results suggest that although human hepatocytes isolated from steatotic liver show reduced P450 activities, they are metabolically competent and can be used for drug metabolism studies.     

Experimental observations and clinical implications of fasting and diet supplementation in fatty livers

Fatty accumulation per se does not appear to affect liver function; however, interest has recently renewed to fatty liver because of the clinical relevance of non alcoholic steato-hepatitis (NASH) and for the increased risk of post-transplant failure in grafted livers with steatosis. Clinical and experimental studies have doubtless demonstrated that oxidative stress ensues in steatotic livers. Mitochondria represent the preferential target of the oxidative injury associated to fatty degeneration and show reduced content of glutathione, higher levels of oxidative products and damages to enzymes involved in the process of ATP synthesis, which become more evident under stressing conditions. Although obese patients with fatty liver are advantaged by weight loss, clinical and experimental observations suggest that fatty livers poorly tolerate excessive food deprivation. These observations represent the rationale for treatment strategies based on the supplementation of antioxidants and energetic substrates rather than solely a diet restriction. This review focuses on data emerging from a series of investigations performed in rats with fatty livers induced by a choline-deficient diet, which resembles human steatosis due to an excessive intake of carbohydrates, and aims to give the cue for the development of therapeutic options able to preserve hepatic function after transplantation of steatotic organs.     

Mice with liver composed of human hepatocytes as an animal model for drug testing

Conventionally, rodents, mostly mice and rats, have been utilized as animal models for studying drug metabolism and toxicity of new medicines. However, there have been two major problems inherent to these models. One is that there are species differences in major enzymes responsible for drug metabolisms and detoxification such as cytochrome P450 between rodents and humans, and the other is that human hepatitis viruses do not infect rodent livers, which hampers studies for anti-hepatitis virus drugs using these models. As an approach to overcome these intrinsic shortages, we devised a method to generate mice whose livers are mostly ( > 80%) repopulated with healthy human hepatocytes 7 years ago. Since then, these mice called simply chimeric mice or liver-humanized mice have been widely utilized among researchers in the areas for new drug developments, which, as a result, have proved that the chimeric mouse is a practical solution to solve the above two issues. The hitherto accumulated studies demonstrating the similarities of the chimeric mouse liver to the human crude liver are summarized and reviewed in the present article. In addition, there have been also studies that show us the presence of dissimilarities between them, such as human hepatocytes' manifestation of hyperplasia in mouse liver and their steatotic alterations when the mice are maintained for > 50 days post-transplantation. These dissimilarities between them are also reviewed in details, considering that the information of the similarities and the dissimilarities is quite useful to researchers who utilize chimeric mice as a drug discovery tool for correctly evaluating the obtained results.     

Targeted tumor dual mode CT/MR imaging using multifunctional polyethylenimine-entrapped gold nanoparticles loaded with gadolinium

We report the construction and characterization of polyethylenimine (PEI)-entrapped gold nanoparticles (AuNPs) chelated with gadolinium (Gd) ions for targeted dual mode tumor CT/MR imaging in vivo. In this work, polyethylene glycol (PEG) monomethyl ether-modified PEI was sequentially modified with Gd chelator and folic acid (FA)-linked PEG (FA-PEG) was used as a template to synthesize AuNPs, followed by Gd(III) chelation and acetylation of the remaining PEI surface amines. The formed FA-targeted PEI-entrapped AuNPs loaded with Gd (FA-Gd-Au PENPs) were well characterized in terms of structure, composition, morphology, and size distribution. We show that the FA-Gd-Au PENPs with an Au core size of 3.0?nm are water dispersible, colloidally stable, and noncytotoxic in a given concentration range. Thanks to the coexistence of Au and Gd elements within one nanoparticulate system, the FA-Gd-Au PENPs display a better X-ray attenuation property than clinical iodinated contrast agent (e.g. Omnipaque) and reasonable r₁ relaxivity (1.1?mM^?1s^?1). These properties allow the FA-targeted particles to be used as an efficient nanoprobe for dual mode CT/MR imaging of tumors with excellent FA-mediated targeting specificity. With the demonstrated organ biocompatibility, the designed FA-Gd-Au PENPs may hold a great promise to be used as a nanoprobe for CT/MR dual mode imaging of different FA receptor-overexpressing tumors.     

UDP-glucuronosyltransferase expression in mouse liver is increased in obesity- and fasting-induced steatosis

UDP-glucuronosyltransferases (Ugt) catalyze phase II conjugation reactions with glucuronic acid, which enhances chemical polarity and the elimination from the body. Few studies have addressed whether Ugt expression and activity are affected by liver disease, such as steatosis. The purpose of this study was to determine whether steatosis induced by obesity or fasting could affect liver Ugt mRNA expression and activity. Male C57BL/6J and Lep(ob/ob) (ob/ob) mice were fed ad libitum or food was withheld for 24 h. In steatotic livers of ob/ob mice, Ugt1a1, -1a6, -1a9, -2a3, -3a1, and -3a2 mRNA expression increased. Fasting, which also induced steatosis, increased hepatic Ugt1a1, -1a6, -1a7, -1a9, -2b1, -2b5, -2a3, -3a1, and -3a2 mRNA expression in mouse liver. Likewise, acetaminophen glucuronidation increased by 47% in hepatic microsomes from ob/ob mice compared with that in C57BL/6J mice, but not after fasting. In both steatosis models, Ugt induction was accompanied by increased aryl hydrocarbon receptor, constitutive androstane receptor (CAR), peroxisome proliferator-activated receptor (PPAR)-α, pregnane X receptor, nuclear factor (erythroid-derived 2)-like 2 (Nrf2), and peroxisome proliferator-activated receptor-γ coactivator-1α mRNA expression. In addition, fasting increased CAR, PPAR, and Nrf2 binding activity. The work points to hepatic triglyceride concentrations corresponding with nuclear receptor and Ugt expression. The findings indicate that steatosis significantly alters hepatic Ugt expression and activity, which could have a significant impact on determining circulating hormone levels, drug efficacy, and environmental chemical clearance.     

Donor liver steatosis and graft selection for liver transplantation: a short review

Early graft dysfunction develops in up to 10-50% of liver transplanted patients and is related to the number of risk factors which identify marginal livers. Marginal livers are defined by the presence of af least one of the following risk factors: (1) donor aged > 50 years; (2) donor with hemodynamic instability or with a residence time in ICU greater than 5 days; (3) donor with hypersodiemia; (4) donor with HCV or HBV infection; and (5) donor with macrovescicular steatosis present in > 25% of hepatocytes. The presence of steatosis involving less than 25% of hepatocytes is not considered sufficient to identify a marginal donor, although it may be associated with some risk of early or late graft failure. The reason is that the steatotic liver is characterized by a decreased tolerance to ischemia/reperfusion. It has been observed that the accumulation of fat in the hepatocytes and the increased cell volume cause an impairment of liver microcirculation. Steatosis is associated with decreased capability of ATP production and storage, with increased lipid peroxidation, and with increased release of tumor necrosis factor-a which is believed to be responsible of the lung damage possibly occurring after transplant. The assessment of the type and extent of steatosis requires liver biopsy, not usually indicated in healthy individual. In the transplant setting a precise assessment of steatosis is the prominent reason for performing a liver biopsy of the donor liver.     

Strategies for the early detection of drug-induced hepatic steatosis in preclinical drug safety evaluation studies

Hepatic steatosis is characterized by the accumulation of lipid droplets in the liver. Although relatively benign, simple steatosis can eventually lead to the development of steatohepatitis, a more serious condition characterized by fibrosis, cirrhosis, and eventual liver failure if the underlying cause is not eliminated. According to the "two hit" theory of steatohepatitis, the initial hit involves fat accumulation in the liver, and a second hit leads to inflammation and subsequent tissue injury. Because some xenobiotics target liver fatty acid metabolism, especially mitochondrial β-oxidation, it is important to avoid potential drug candidates that can contribute to either the initiation of liver steatosis or progression to the more injurious steatohepatitis. The gold standard for the detection of these types of hepatic effects is histopathological examination of liver tissue. In animal studies, these examinations are slow, restricted to a single sampling time, and limited tissue sections. Recent literature suggests that rapid in vitro screening methods can be used early in the drug R&D process to identify compounds with steatotic potential. Further, progress in the identification of potential serum or plasma protein biomarkers for these liver changes may provide additional in vivo tools to the preclinical study toxicologist. This review summarizes recent developments for in vitro screening and in vivo biomarker detection for steatotic drug candidates.     

In vitro cellular accumulation of gadolinium incorporated into chitosan nanoparticles designed for neutron-capture therapy of cancer.

The accumulation of gadolinium loaded as gadopentetic acid (Gd-DTPA) in chitosan nanoparticles (Gd-nanoCPs), which were designed for gadolinium neutron-capture therapy (Gd-NCT) for cancer, was evaluated in vitro in cultured cells. Using L929 fibroblast cells, the Gd accumulation for 12 h at 37 degrees C was investigated at Gd concentrations lower than 40 ppm. The accumulation leveled above 20 ppm and reached 18.0+/-2.7 (mean+/-S.D.) microg Gd/10(6) cells at 40 ppm. Furthermore, the corresponding accumulations in B16F10 melanoma cells and SCC-VII squamous cell carcinoma, which were used in the previous Gd-NCT trials in vivo, were 27.1+/-2.9 and 59.8+/-9.8 microg Gd/10(6) cells, respectively, hence explaining the superior growth-suppression in the in vivo trials using SCC-VII cells. The accumulation of Gd-nanoCPs in these cells was 100-200 times higher in comparison to dimeglumine gadopentetate aqueous solution (Magnevist), a magnetic resonance imaging contrast agent. The endocytic uptake of Gd-nanoCPs, strongly holding Gd-DTPA, was suggested from transmission electron microscopy and comparative studies at 4 degrees C and with the solution system. These findings indicated that Gd-nanoCPs had a high affinity to the cells, probably contributing to the long retention of Gd in tumor tissue and leading to the significant suppression of tumor growth in the in vivo studies that were previously reported.     

Comparison of protein expression between human livers and the hepatic cell lines HepG2, Hep3B,and Huh7 using SWATH and MRM-HR proteomics: Focusing on drug-metabolizing enzymes

Human hepatic cell lines are widely used as an in vitro model for the study of drug metabolism and liver toxicity. However, the validity of this model is still a subject of debate because the expressions of various proteins in the cell lines, including drug-metabolizing enzymes (DMEs), can differ significantly from those in human livers. In the present study, we first conducted an untargeted proteomics analysis of the microsomes of the cell lines HepG2, Hep3B, and Huh7, and compared them to human livers using a sequential window acquisition of all theoretical mass spectra (SWATH) method. Furthermore, high-resolution multiple reaction monitoring (MRM-HR), a targeted proteomic approach, was utilized to compare the expressions of pre-selected DMEs between human livers and the cell lines. In general, the SWATH quantifications were in good agreement with the MRM-HR analysis. Over 3000 protein groups were quantified in the cells and human livers, and the proteome profiles of human livers significantly differed from the cell lines. Among the 101 DMEs quantified with MRM-HR, most were expressed at substantially lower levels in the cell lines. Thus, appropriate caution must be exercised when using these cell lines for the study of hepatic drug metabolism and toxicity.     

Hepatic uptake of the novel antifungal agent caspofungin.

Caspofungin (CANCIDAS, a registered trademark of Merck & Co., Inc.) is a novel echinocandin antifungal agent used in the treatment of esophageal and invasive candidiases, invasive aspergillosis, and neutropenia. Available data suggest that the liver is a key organ responsible for caspofungin elimination in rodents and humans. Caspofungin is primarily eliminated by metabolic transformation; however, the rate of metabolism is slow. Accordingly, it was hypothesized that drug uptake transporters expressed on the basolateral domain of hepatocytes could significantly influence the extent of caspofungin uptake and subsequent elimination. In this study, experiments ranging from perfused rat livers to heterologous expression of individual hepatic uptake transporters were utilized to identify the transporter(s) responsible for the observed liver-specific uptake of this compound. Data from perfused rat liver studies were consistent with the presence of carrier-mediated caspofungin hepatic uptake, although this process appeared to be slow. To identify a relevant hepatic uptake transporter, we developed novel Tet-on HeLa cells expressing OATP1B1 (OATP-C, SLC21A6) and OATP1B3 (OATP8, SLC21A8), whose target gene can be overexpressed by the addition of doxycycline. A modest but statistically significant uptake of caspofungin was observed in cells overexpressing OATP1B1, but not OATP1B3. Taken together, these findings suggest that OATP1B1-mediated hepatic uptake may contribute to the overall elimination of this drug from the body.     

Hydrogels for localized chemotherapy of liver cancer: a possible strategy for improved and safe liver cancer treatment

The systemic drug has historically been preferred for the treatment of the majority of pathological conditions, particularly liver cancer. Indeed, this mode of treatment is associated with adverse reactions, toxicity, off-target accumulation, and rapid hepatic and renal clearance. Numerous efforts have been made to design systemic therapeutic carriers to improve retention while decreasing side effects and clearance. Following systemic medication, local administration of therapeutic agents allows for higher ‘effective’ doses with fewer side effects, kidney accumulation, and clearance. Hydrogels are highly biocompatible and can be used for both imaging and therapy. Hydrogel-based drug delivery approach has fewer side effects than traditional chemotherapy and can deliver drugs to tumors for a longer time. The chemical and physical flexibility of hydrogels can be used to achieve disease-induced in situ accumulation as well as subsequent drug release and hydrogel-programmed degradation. Moreover, they can act as a biocompatible depot for localized chemotherapy when stimuli-responsive carriers are administrated. Herein, we summarize the design strategies of various hydrogels used for localized chemotherapy of liver cancer and their delivery routes, as well as recent research on smart hydrogels.     

Applications of Fourier transform infrared spectroscopic imaging to tablet dissolution and drug release

Introduction: Solid oral dosage forms are the most commonly used method for administering active pharmaceutical ingredients to patients. Understanding the mechanisms and processes of drug release is essential for improving the design of pharmaceutical tablets.

Areas covered: In this review, recent approaches where attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopic imaging has been applied to study tablet dissolution and drug release have been investigated. Drug release studies of model pharmaceutical systems composed of drug/polymer mixtures in the presence of aqueous solutions have been discussed, as has the subsequent combination with UV/Vis spectroscopic detection to quantify the amount of drug dissolved as a function of time. The use of a single-reflection ATR accessory with a diamond crystal allows for in situ FTIR imaging of tablet compaction and dissolution.

Expert opinion: ATR-FTIR imaging can address the challenges of investigating the mechanisms of drug release from a range of innovative new delivery systems. Unlike standard dissolution tests, this spectroscopic imaging method obtains insight and information about changes within the tablet during dissolution. Areas where ATR-FTIR imaging has shown further potential to be particularly useful are for the study of multi-layered solid tablets, high-throughput analysis, use of microfluidic devices and for surface-enhanced ATR-FTIR spectroscopy.     

白芍总苷对免疫性肝纤维化大鼠肝组织NF-κB和TGF-β1蛋白表达的影响

目的研究免疫性肝纤维化大鼠肝组织中核转录因子-κB(nuclear factor-κB,NF-κB)和转化生长因子β1(trans-forming growth factor beta1,TGF-β1)的变化以及白芍总苷(TGP)对两者蛋白表达的影响。方法采用猪血清诱导建立大鼠肝纤维化模型,肝组织HE染色和V-G染色观察肝组织损伤及胶原表达变化;免疫组化S-P法观察NF-κB p65和TGF-β1蛋白表达;显微摄像及图像分析检测胶原、NF-κBp65和TGF-β1蛋白的表达量。结果与正常组比较,模型组大鼠肝组织明显破坏,胶原合成增加,NF-κB p65和TGF-β1表达增强(P<0.01);与模型组比较,TGP治疗组肝组织破坏减轻,纤维化程度也明显改善,胶原面积、NF-κB p65和TGF-β1表达均明显减少(P<0.01),三者呈相关性。结论NF-κB介导TGF-β1产生或活化在免疫性肝纤维化过程中可能发挥着重要作用,而TGP抑制纤维化大鼠肝组织NF-κB和TGF-β1的表达可能是TGP的抗肝纤维化主要作用机制之一。     

In vivo imaging for biodistribution and metabolism evaluations of new chemical entities

Due to numerous technical developments, in vivo imaging is suitable for pharmacokinetic and metabolism studies of new chemical entities as well as for evaluating their pharmacological or biological effects. MRI, nuclear medicine, X-Ray, ultrasound and optical imaging are available for both clinical and experimental imaging with even higher performance. For all these imaging modalities, diagnostic agents are useful to improve contrast and specificity. Specific targeting of biological events is addressed by molecular imaging. From a pharmacodynamic perspective, radiolabeling of a new chemical entity allows in vivo visualization quantitative measure of its biodistribution, its elimination and its specific molecular binding. Non-invasive imaging methods are useful for longitudinal investigations of biological changes. Based on nanotechnologies, specificity of drug delivery can be monitored by imaging. New developments in hybrid imaging technologies as well as multimodal contrast agents reinforce in vivo experimental and clinical proof of mechanism of new chemical entities.     

Acanthoic acid modulates lipogenesis in nonalcoholic fatty liver disease via FXR/LXRs-dependent manner

OBJECTIVE To reveal the effect and mechanism of acanthoic acid(AA) on nonalcoholic fatty liver disease(NAFLD) associated with lipid accumulation by activating Farnesoid X receptor(FXR) and liver X receptors(LXRs) signaling. METHODS C57 BL/6 mice were received a modified Lieber-De Carli diet with 71%high-fat(L-D) and treated with AA(20 and 40 mg·kg~(-1)) or equal volume of saline for 12 weeks. The regulation of AA on lipid accumulation was also detected in pro-steatotic stimulated AML12 cells with palmitic acid(PA).RESULTS When L-D diet-fed mice were treated with AA, loss in body mass, liver index, and liver lipid droplet were observed along with reduced triglyceride(TG) and serum transaminase. Furthermore, AA decreased sterol regulatory element binding protein 1(SREBP-1) and target genes expression, regulated PPARα and PPARγ expressions, ameliorated hepatic fibrosis markers, enhanced hepatic FXR and LXR, and regulated AMPK-LKB1 and SIRT1 signaling pathway. Moreover, AA attenuated lipid accumulation via FXR and LXR activation in steatotic AML-12 cells, which was confirmed by guggulsterones(FXR antagonist) or GW3965(LXR agonist). CONCLUSION Activation of FXR and LXR signaling caused by AA might increase AMPK-SIRT1 signaling and then contribute to modulating lipid accumulation and fatty acid synthesis, which suggested that activated FXR-LXR axis by AA represented an effective strategy for relieving NAFLD.     

The reference liver – ABC and SLC drug transporters in healthy donor and metastatic livers

BackgroundAnalysis of results and conclusions in studies dedicated to pathology of the liver are usually based on comparison of pathological liver specimens and control/reference (considered as healthy) tissues. There are two main sources of the control liver samples used as the reference livers, i.e. deceased organ donor livers and non-tumorous tissue from metastatic livers, which are also applied for drug transporter investigations. However, no information has yet been published on drug transporters in these two major types of reference livers.MethodsWe explored ABC (P-gp, MRP1, MRP2, MRP3, MRP4, BCRP, BSEP) and SLC (NTCP, MCT1, OCT1, OCT3, OAT2, OATP1B1, OATP1B3, OATP2B1) family transporters expression (qPCR) and protein abundance (LC–MS/MS) in healthy donors (n = 9) and metastatic (n = 13) livers.ResultsThe analysis of mRNA content revealed significant differences in ABCB11, ABCC1, ABCG2, SLC10A1, SLC16A1, SLCO1B1 and SLCO2B1 gene expression between livers from organ donors and patients who underwent surgical resection of metastatic tumors. The protein abundance of NTCP was significantly higher, whereas of P-gp significantly lower in non-tumorous tissues from metastatic livers. Greater inter-individual variability in protein abundance of all studied transporters in subjects with metastatic colon cancer was also observed.ConclusionsThe results suggest that final conclusions in liver pathology studies may depend on the reference liver tissue used, especially in gene expression studies.     

Multimodal imaging of hallucinogens 25C‐ and 25I‐NBOMe on blotter papers

Due to the much lower production costs but similar effects to lysergic acid diethylamide (LSD), phenethylamine derivatives are sold as a cheaper replacement or deceptively as LSD itself. These potent hallucinogenic substances can lead to severe intoxication, thus a more profound understanding of their use is required. This includes the elucidation of the manufacturing processes for the commonly used blotter papers and the assessment of the risk of overdosing because of a heterogeneous distribution on the blotter papers. Besides the rapid detection of the analytes, the manufacturing process was elucidated by three different imaging techniques and liquid chromatography‐mass spectrometry (LC–MS). A blotter paper sample, containing the two hallucinogenic phenethylamine derivatives 25I‐NBOMe and 25C‐NBOMe, was analyzed by complementary techniques such as micro x‐ray fluorescence (μXRF), laser ablation (LA)‐inductively coupled plasma‐optical emission spectroscopy (ICP‐OES), matrix assisted laser desorption ionization (MALDI)‐MS, and with LC–MS after extraction. Using the signal from chlorine and iodine within the compounds, μXRF proved to be the fastest, cheapest and easiest method for identification, requiring no sample preparation at all. LA‐ICP‐OES provided three‐dimensional information of the elements in the blotter paper. These results helped to confirm the assumption that manufacturers spray the compounds onto the paper. Whereas μXRF and LA‐ICP‐OES detected signals for chlorine and iodine, MALDI‐MS‐imaging showed the molecular distribution of both analytes. LC–MS analyses as a complementary method support the imaging results. Quantitative results for different drug hotspots revealed a heterogeneous distribution of the drugs on the blotter paper implying an inherent risk of overdosing for consumers.