Role In Life Research Articles

Hepatocyte growth factor suppresses acute renal inflammation by inhibition of endothelial E-selectin

Vascular endothelial activation, marked by de novo expression of E-selectin, is an early and essential event in the process of leukocyte extravasation and inflammation. Evidence suggests that hepatocyte growth factor (HGF) ameliorates inflammation in animal models of renal disease, implying that HGF might inhibit specific components of the inflammatory response. This study examined the effect of HGF on endothelial E-selectin expression in acute inflammation induced by tumor necrosis factor (TNF)-α. In vitro, HGF suppressed TNF-α-induced cell surface expression of E-selectin in human umbilical vein endothelial cells (HUVEC) and inhibited E-selectin mediated monocytic adhesion to endothelial monolayers. HGF activated phosphatidylinositol 3-kinase (PI3K)–Akt that in turn inhibited its downstream transducer glycogen synthase kinase (GSK)3. Blockade of the PI3K–Akt pathway with specific inhibitors abrogated HGF induced inhibitory phosphorylation of GSK3 and suppression of E-selectin. In addition, selective inhibition of GSK3 activity by lithium suppressed TNF-α-induced E-selectin expression and monocytic adhesion, reminiscent of the action of HGF. Moreover, ectopic expression of an uninhibitable mutant GSK3β, in which the regulatory serine-9 is replaced by alanine, abolished HGF's suppressive effect on endothelial E-selectin. In vivo, administration of exogenous HGF reduced endothelial expression of E-selectin induced by bolus injection of TNF-α. This was associated with less sequestration of circulating fluorescence-labeled macrophages in the kidney. These findings suggest that HGF ameliorates acute renal inflammation in part by downregulating E-selectin mediated macrophage adhesion to the inflamed endothelium.

Overexpression of rat long chain acyl‐CoA synthetase 1 alters fatty acid metabolism in rat primary hepatocytes

Disturbance of fatty acid (FA) metabolism in liver plays an important role in disorders such as hepatic steatosis, hyperlipidemia, and insulin resistance. Long chain acyl-CoA synthetases (ACSL) activate FAs in the first step of FA metabolism. We hypothesized that different ACSL isoforms have different functional and tissue-specific roles. In adipose tissue, ACSL1 is related to triacylglycerol (TAG) accumulation; its role in liver is unknown. To elucidate the function of ACSL1 in hepatic FA metabolism, we infected rat primary hepatocytes with adenoviruses carrying either rat ACSL1 or green fluorescent protein, and labeled the cells with 100 or 750 μM [1-14C]oleate for 3 h. Lipids were extracted and subjected to thin layer chromatography. ACSL1 overexpression increased total ACSL activity 4.7-fold. In the presence of both 100 μM and 750 μM oleate, ACSL1 overexpression reduced [1-14C]oleate incorporation into both acid-soluble metabolites (ASM) and cholesterol ester (CE), while increasing [1-14C]oleate incorporation into diacylglycerol (DAG) and phospholipids. However, [1-14C]oleate incorporation into TAG was decreased and cellular TAG mass was unchanged. To examine the effect of ACSL1 on FA recycling, hepatocytes were prelabeled with 750 μM [1-14C]oleate for 3 h and chased for 12 h. During the chase, ACSL1 overexpression attenuated the loss of labeled cellular TAG, attenuated the increase of labeled CE, and decreased the label in ASM. These results indicate that hepatic ACSL1 channels FA towards DAG synthesis and reesterification, and away from CE synthesis and oxidation. (NIH-DK-59935)

Rat activin-γE mRNA expression during development and in acute and chronic liver injury

Activin-betaE mRNA expression was investigated in male and female rats using gel-based and quantitative RT-PCR, in fetal and post-natal liver during development and in a variety of tissues from 200 gm adult animals. Activin-betaE expression was also assessed in rat liver after partial hepatectomy, and after repeated toxic insult. Male Sprague Dawley rats were subjected to partial hepatectomy or sham operations. Samples were collected from the caudate liver lobe during regeneration, from 12 to 240 hr after surgery. Three groups of 5 male rats were treated with CCl(4) for 0 (control), 5 or 10 weeks, to induce liver fibrosis and cirrhosis. Activin-betaE mRNA was predominantly expressed in liver, with much lower amounts of mRNA observed in pituitary, adrenal gland and spleen, in both males and females. Low activin-betaE expression was observed in liver at fetal day 16, with higher levels seen between post-natal days 3 and 35 and a further increase noted by day 47, in both males and females. Liver activin-betaE mRNA concentrations did not change from control values 12-72 hr after PHx, but significantly increased over six fold, 168 hr post-hepatectomy, when liver mass was restored. Activin-betaE mRNA was up-regulated after 5 weeks of CCl(4) treatment, but not after 10 weeks. The changes in activin-betaE mRNA concentrations after liver insult did not always parallel those reported for the activin-betaC subunit, suggesting activin-betaE may have an independent role in liver under certain conditions.

Different roles of liver X receptor α and β in lipid metabolism: Effects of an α-selective and a dual agonist in mice deficient in each subtype

Liver X receptor (LXR) α and LXRβ are closely related nuclear receptors that respond to elevated levels of intracellular cholesterol by enhancing transcription of genes that control cholesterol efflux and fatty acid biosynthesis. The consequences of inactivation of either LXR isoform have been thoroughly studied, as have the effects of simultaneous activation of both LXRα and LXRβ by synthetic compounds. We here describe the effects of selective activation of LXRα or LXRβ on lipid metabolism. This was accomplished by treating mice genetically deficient in either LXRα or LXRβ with an agonist with equal potency for both isoforms (Compound B) or a synthetic agonist selective for LXRα (Compound A). We also determined the effect of these agonists on gene expression and cholesterol efflux in peritoneal macrophages derived from wild-type and knockout mice. Both compounds raised HDL-cholesterol and increased liver triglycerides in wild-type mice; in contrast, in mice deficient in LXRα, Compound B increased HDL-cholesterol but did not cause hepatic steatosis. Compound B induced ATP-binding cassette transporter (ABC) A1 expression and stimulated cholesterol efflux in macrophages from both LXRα and LXRβ-deficient mice. Our data lend further experimental support to the hypothesis that LXRβ-selective agonists may raise HDL-cholesterol and stimulate macrophage cholesterol efflux without causing liver triglyceride accumulation.

Molecular cloning and expression pattern of 14 kDa apolipoprotein in orange-spotted grouper, Epinephelus coioides

A novel fish-specific apolipoprotein ( apo-14 kDa) has been recently cloned from eel and pufferfish. However, its expression pattern has not been elucidated. In this study, EcApo-14 has been screened from hypothalamic cDNA library of male orange-spotted grouper, which shows 62.9%, 51%, 46.9%, 43.2%, and 31.9% identities to Apo-14 of European flounder, pufferfish, Japanese eel, gibel carp, and grass carp, respectively. RT-PCR analysis reveals that this gene is first transcribed in neurula embryos and maintains a relatively stable expression level during the following embryogenesis. EcApo-14 transcripts are at a very high level during embryonic and early larval development in the yolk syncytial layer (YSL), and decrease in YSL and form intense staining in liver at 3 days after hatching. In adult tissues, EcApo-14 is predominantly expressed in liver and brain. The data suggested that EcApo-14 might play an important role in liver and brain morphogenesis and growth.

Low ethanol consumption induces enhancement of insulin sensitivity in liver of normal rats

Moderate amounts of alcohol intake have been reported to have a protective effect on the cardiovascular system and this may involve enhanced insulin sensitivity. We established an animal model of increased insulin sensitivity by low ethanol consumption and here we investigated metabolic parameters and molecular mechanisms potentially involved in this phenomenon. For that, Wistar rats have received drinking water either without (control) or with 3% ethanol for four weeks. The effect of ethanol intake on insulin sensitivity was analyzed by insulin resistance index (HOMA-IR), intravenous insulin tolerance test (IVITT) and lipid profile. The role of liver was investigated by the analysis of insulin signaling pathway, GLUT2 gene expression and tissue glycogen content. Rats consuming 3% ethanol showed lower values of HOMA-IR and plasma free fatty acids (FFA) levels and higher hepatic glycogen content and glucose disappearance constant during the IVITT. Neither the phosphorylation of insulin receptor (IR) and insulin receptor substrate-1 (IRS-1), nor its association with phosphatidylinositol-3-kinase (PI3-kinase), was affected by ethanol. However, ethanol consumption enhanced liver IRS-2 and protein kinase B (Akt) phosphorylation (3 times, P < 0.05), which can be involved in the 2-fold increased ( P < 0.05) hepatic glycogen content. The GLUT2 protein content was unchanged. Our findings point out that liver plays a role in enhanced insulin sensitivity induced by low ethanol consumption.

Delineation of molecular changes in intrahepatic cholesterol metabolism resulting from diminished cholesterol absorption

The absorption of cholesterol by the small intestine is a major route for the net entry of cholesterol into the body and can therefore affect the plasma low density lipoprotein-cholesterol (LDL-C) concentration. These studies used ezetimibe, a potent inhibitor of cholesterol absorption, to delineate the biochemical and molecular changes in intrahepatic metabolism and biliary lipid secretion when there is a major reduction in chylomicron cholesterol delivery to the liver. In female LDL receptor (LDLR)-deficient (LDLR-/-) mice fed a basal diet containing ezetimibe (0-10 mg/day/kg body weight), cholesterol absorption was reduced up to 91%, fecal neutral sterol excretion was increased up to 4.7-fold, and plasma total cholesterol concentrations decreased by up to 18%. Blocking cholesterol absorption prevented the accumulation of very low density lipoproteins and LDL in the circulation of LDLR-/- mice fed a lipid-rich diet. In female LDLR+/+ mice fed the lipid-rich diet with ezetimibe, the relative mRNA level for the LDLR in the liver was 2-fold greater than in matching mice given the lipid-rich diet alone. We conclude that in the mouse the reduction in plasma LDL-C levels induced by blocking cholesterol absorption reflects both a diminished rate of LDL-C production and a modest increase in hepatic LDLR expression.

Amphiregulin: An early trigger of liver regeneration in mice

Liver regeneration is a unique response directed to restore liver mass after resection or injury. The survival and proliferative signals triggered during this process are conveyed by a complex network of cytokines and growth factors acting in an orderly manner. Activation of the epidermal growth factor receptor is thought to play an important role in liver regeneration. Amphiregulin is a member of the epidermal growth factor family whose expression is not detectable in healthy liver. We have investigated the expression of amphiregulin in liver injury and its role during liver regeneration after partial hepatectomy. Amphiregulin gene expression was examined in healthy and cirrhotic human and rat liver, in rodent liver regeneration after partial hepatectomy, and in primary hepatocytes. The proliferative effects and intracellular signaling of amphiregulin were studied in isolated hepatocytes. The in vivo role of amphiregulin in liver regeneration after partial hepatectomy was analyzed in amphiregulin-null mice. Amphiregulin gene expression is detected in chronically injured human and rat liver and is rapidly induced after partial hepatectomy in rodents. Amphiregulin expression is induced in isolated hepatocytes by interleukin 1beta and prostaglandin E(2), but not by hepatocyte growth factor, interleukin 6, or tumor necrosis factor alpha. We show that amphiregulin behaves as a primary mitogen for isolated hepatocytes, acting through the epidermal growth factor receptor. Finally, amphiregulin-null mice display impaired proliferative responses after partial liver resection. Our findings indicate that amphiregulin is an early-response growth factor that may contribute to the initial phases of liver regeneration.

Excretion and Metabolism of DA-7867, a New Oxazolidinone, in Rats

Almost negligible hepatic metabolism (minor role of liver for the metabolism) and extensive urinary and fecal excretion of DA-7867 were investigated after intravenous administration at a dose of 10 mg/kg to rats. Pharmacokinetic parameters, especially nonrenal clearances of DA-7867, were very similar between control rats and rats pretreated with SKF 525-A, a nonspecific inhibitor of CYP isozymes, in rats. Similar results were also obtained between control rats and rats with liver cirrhosis induced by dimethylnitrosamine. Hepatic first-pass effect of DA-7867 was almost negligible in rats; the areas under the plasma concentration-time curve from time zero to time infinity of DA-7867 were not significantly different between intravenous and intraportal administration. The above data indicated that liver had almost negligible metabolic activity for DA-7867 in rats. Since metabolism of DA-7867 was not considerable in rats, urinary and fecal excretion of the drug was measured for up to 14 days in ten rats. Fecal excretion was the major route for elimination of DA-7867 in rats; approximately 85.0% of intravenous dose of DA-7867 at 10 mg/kg was recovered from urine (17.0% of intravenous dose), feces (64.0% of intravenous dose), washings of the metabolic cage (3.16% of intravenous dose), and entire gastrointestinal tract (0.421% of intravenous dose).

Protective role of dehydroascorbate in rat liver ischemia-reperfusion injury

Oxidative stress plays an important role in liver ischemia/reperfusion (I/R) injury. Thus, enhancing the liver antioxidant capacity could be a promising therapeutic strategy. Ascorbate (AA) is considered the perfect antioxidant, but its therapeutic efficacy is greatly limited by its slow achievement of high intracellular levels. This might be circumvented by administering dehydroascorbate (DHA), which presents a several-fold greater uptake than AA, and undergoes rapid intracellular reduction to AA. Thus, our aim was to assess the protective role of DHA in liver I/R injury. Wistar rats (200-300 g bw) were pretreated iv with different doses of AA or DHA 20 min before liver ischemia, followed by 6 h reperfusion. Liver damage was assessed by biochemical and morphological indices. DHA pretreatment induced a rapid increase in liver ascorbate levels, significantly higher than findings for AA, without any significant reduction in glutathione levels. Liver damage during I/R in controls showed significant increases in serum transaminases and hepatic thiobarbituric acid reactive substances with alterations of liver morphology. DHA administration induced a clear, significant protection against I/R injury, whereas liver damage was only moderately prevented by AA. DHA might represent a simple, effective therapeutic option to prevent liver damage associated with ischemia/reperfusion.

Crosstalk between PKCζ and the IL4/Stat6 pathway during T-cell-mediated hepatitis

PKCzeta is required for nuclear factor kappa-B (NF-kappaB) activation in several cell systems. NF-kappaB is a suppressor of liver apoptosis during development and in concanavalin A (ConA)-induced T-cell-mediated hepatitis. Here we show that PKCzeta-/- mice display inhibited ConA-induced NF-kappaB activation and reduced damage in liver. As the IL-4/Stat6 pathway is necessary for ConA-induced hepatitis, we addressed here the potential role of PKCzeta in this cascade. Interestingly, the loss of PKCzeta severely attenuated serum IL-5 and liver eotaxin-1 levels, two critical mediators of liver damage. Stat6 tyrosine phosphorylation and Jak1 activation were ablated in the liver of ConA-injected PKCzeta-/- mice and in IL-4-stimulated PKCzeta-/- fibroblasts. PKCzeta interacts with and phosphorylates Jak1 and PKCzeta activity is required for Jak1 function. In contrast, Par-4-/- mice have increased sensitivity to ConA-induced liver damage and IL-4 signaling. This unveils a novel and critical involvement of PKCzeta in the IL-4/Stat6 signaling pathway in vitro and in vivo.

Prescription of statins to dyslipidemic patients affected by liver diseases: a subtle balance between risks and benefits

Statins reduce cardiovascular morbidity and mortality in the general population with an excellent risk-benefit profile. The most frequent adverse events are myopathy and increase in hepatic aminotransferases. In this review, we consider the role of liver in metabolism of statins, their potential hepatic toxicity and the guidelines for their prescription in patients affected by different liver diseases. Statin-induced hepatic toxicity: i) occurs in 1-3% of patients; ii) is characterized by increased aminotransferase levels; iii) is dose-related; iv) is frequently asymptomatic; v) usually reverts after dosage reduction or treatment withdrawal. Finally, after recovery, a rechallenge with the same or other statins may not result in increased aminotranferases. Caution is needed when prescribing statins to patients with liver disease, and liver toxicity should always be monitored during statin treatment. In particular, i) the potential hepatic toxicity requires frequent control of biochemical parameters related to hepatic cytolysis and cholestasis in all patients on statins; ii) administration of statins is counterindicated in patients with advanced or end-stage parenchymal liver disease due to the relevant impairment of their metabolism; iii) cholestatic disorders with secondary dyslipidemia do not require statin treatment even if relevant alterations of the lipid pattern are detected; iv) patients with acute liver disease of viral or alcoholic etiology should not receive statins until normalization of cytolysis enzymes; v) chronic hepatitis patients may be treated by statins if their cardiovascular risk is elevated and provided that careful follow-up is carried out to rapidly recognize the onset of further liver damage; vi) liver transplantation recipients affected by dyslipidemia induced by immunosuppressive therapy can be treated with statins under careful clinical control; vii) the benefits of statins should likely overcome the risks in the large majority of dyslipidemic patients affected by non-alcoholic hepatosteatosis, a disease frequently diagnosed in insulin-resistant subjects.

Quantitative analysis of the expression of ACAT genes in human tissues by real-time PCR2

ACAT (also called sterol o-acyltransferase) catalyzes the esterification of cholesterol by reaction with long-chain acyl-CoA derivatives and plays a pivotal role in the regulation of cholesterol homeostasis. Although two human ACAT genes termed ACAT-1 and ACAT-2 have been reported, prior research on differential tissue expression is qualitative and incomplete. We have developed a quantitative multiplex assay for each ACAT isoform after RT treatment of total RNA using TaqMan real-time quantitative PCR normalized to beta-actin in the same reaction tube. This enabled us to calculate the relative abundance of transcripts in several human tissues as an ACAT-2/ACAT-1 ratio. In liver (n = 17), ACAT-1 transcripts were on average 9-fold (range, 1.7- to 167-fold) more abundant than ACAT-2, whereas in duodenal samples (n = 10), ACAT-2 transcripts were on average 3-fold (range, 0.39- to 12.2-fold) more abundant than ACAT-1. ACAT-2 was detected for the first time in peripheral blood mononuclear cells. Interesting differences in ACAT-2 mRNA expression were evident in subgroup analysis of samples from different sources. These results demonstrate quantitatively that ACAT-1 transcripts predominate in human liver and ACAT-2 transcripts predominate in human duodenum and support the notion that ACAT-2 has an important regulatory role in liver and intestine.

Abnormal liver function tests following bone marrow transplantation: aetiology and role of liver biopsy.

Liver dysfunction is common in bone marrow transplant recipients. Common causes are graft-versus-host disease, drugs, veno-occlusive disease, sepsis and iron overload. We studied the prevalence and aetiology of abnormal liver function tests following bone marrow transplantation and the role of liver biopsy. All allogeneic and autologous bone marrow transplantations undertaken in our institution over a 2-year period were studied. Subsequent liver function tests, the use and timing of liver biopsy and the final cause of liver dysfunction were determined in each case. We studied 121 patients (58 allogeneic, 63 autologous). Abnormal liver function tests were found in 52% of bone marrow transplant recipients (72% allogeneic and 33% autologous; P = 0.015). The most common causes of liver dysfunction were graft-versus-host disease, drugs and iron overload in the allogeneic group, and drugs and sepsis in the autologous group. Nineteen patients (16%; 18 allogeneic) underwent liver biopsy. The majority of liver biopsies were carried out in the late post-transplant period to exclude or confirm graft-versus-host disease, although only one case was confirmed. Sixteen of the 19 patients who underwent biopsy had significant hepatic iron overload, but no biopsy revealed evidence of fibrosis or cirrhosis. Liver dysfunction following bone marrow transplantation is common and most diagnoses can be ascertained without resorting to liver biopsy. In our series, hepatic iron overload was the most common finding in those who underwent liver biopsy.

The regulatory role of prostaglandin E2 in liver (patho) physiology is controlled at its site of synthesis and its action on the receptors

Among the hormone class of the eicosanoids, PGE2 plays a predominant role in liver (patho) physiology. Liver-specific responses, like regulation of blood glucose homeostasis, sinusoidal blood flow within the liver, properties of the transendothelial barrier within the liver, synthesis and release of important other mediators like cytokines, growth factors or nitric oxide, and liver fibrogenesis have been shown to be mediated or regulated by PGE2 [1]. Within the liver, the main producers of PGE2 are the Kupffer cells. The synthesis of PGE2 in Kupffer cells is controlled at multiple levels. The action of PGE2 on its target cells is mediated by 4 classes of PGE2 receptors (EP1, EP2, EP3, EP4). Each of these receptors converts the information of PGE2 by different intracellular signal pathways to a specific cellular response [2].

The Role of Liver X Receptor-α in the Fatty Acid Regulation of Hepatic Gene Expression

Liver X receptors (LXR) alpha and beta play an important role in regulating the expression of genes involved in hepatic bile and fatty acid synthesis, glucose metabolism, as well as sterol efflux. Studies with human embryonic kidney 293 cells indicate that unsaturated fatty acids interfere with oxysterols binding to LXR and antagonize oxysterol-induced LXRalpha activity. In this report, we evaluated the effects of unsaturated fatty acids on LXR-regulated hepatic gene expression. The LXR agonist, T1317, induced mRNAs encoding sterol regulatory element-binding protein 1c (SREBP-1c) and two SREBP-1c-regulated lipogenic genes, e.g. fatty-acid synthase and the S14 protein in primary hepatocytes. Treatment of hepatocytes with eicosapentaenoic acid (20:5n-3) suppressed these mRNAs in the absence and presence of T1317. The cis-regulatory elements targeted by T1317 were not required for fatty-acid suppression of FAS or S14 promoter activity. In contrast to SREBP-1-regulated lipogenic genes, 20:5n-3 had no effect on the T1317 induction of ABCG5 or ABCG8 in the rat hepatoma cell line, FTO-2B. These two genes require LXR but not SREBP-1c for their expression. Feeding rats a diet supplemented with fish oil suppressed hepatic SREBP-1c-regulated genes and induced PPARalpha-regulated genes but had no effect on the LXR-regulated transcripts, CYP7A1, ABCG5, or ABCG8. Transfection studies, using either full-length hLXRalpha or a chimera containing only the LXRalpha ligand binding domain, indicate that a wide array of unsaturated fatty acids had little effect on LXRalpha activity in primary hepatocytes or FTO-2B. These studies suggest that LXRalpha is not a target for unsaturated fatty acid regulation in primary rat hepatocytes or in liver. Thus, oxysterol/LXR-mediated regulation of transcripts involved in bile acid synthesis or sterol efflux appear insensitive to dietary unsaturated fatty acids. The unsaturated fatty acid suppression of SREBP-1 and its targeted lipogenic genes is independent of LXRalpha

Detection of point mutations of the Axin1 gene in colorectal cancers.

Axin is a recently identified tumor suppressor that plays an important role in liver and colon cancers. To gain further insights into the structure and function of Axin in controlling cell growth, we analyzed 54 colorectal cancer tissues for mutations in AXIN1 gene. We employed PCR amplification with 23 sets of primers against introns that encompassed the whole coding region of AXIN1 followed by single-strand conformation polymorphism (SSCP) analysis. After subcloning and sequencing analysis of the reamplified DNA from the aberrant bands, we found, in addition to 3 silent mutations, 6 missense point mutations in different functionally important regions. The missense mutation rate is hence 11%, suggesting that Axin deficiency may contribute to the onset of colorectal tumorigenesis.

Induction of ATP-binding cassette A1 by all-trans retinoic acid: Possible role of liver X receptor-α

ATP binding cassette A1 (ABCA1) is involved in the lipid metabolism of macrophages and has been suggested to play an important role in the development of foam cells and in the pathogenesis of atherosclerosis. We have investigated the effects of all-trans retinoic acid (atRA) on the mRNA and protein levels of ABCA1 in THP-1 cells. Our results show that both mRNA and protein levels of ABCA1 were significantly increased upon treatment with atRA. Since ABCA1 is highly regulated by liver X receptor (LXR) we also analysed the mRNA and protein expressions of LXR-alpha and LXR-beta in the THP-1 cells after treatment with atRA. Also the levels of LXR-alpha were increased by atRA. In conclusion, our results show that LXR-alpha and ABCA1 are simultaneously induced by atRA. The results also imply that the induction of ABCA1 by atRA may in part depend on the induction of LXR.

Ischemic preconditioning decreases C-X-C chemokine expression and neutrophil accumulation early after liver transplantation in rats.

Polymorphonuclear neutrophil (PMN) plays a major role in liver ischemia/reperfusion injury. Protective effect of ischemic preconditioning (IP) has been confirmed in liver ischemia/reperfusion injury. The purpose of this study was to investigate the effect of IP on C-X-C chemokine expression and PMNs recruitment early after liver transplantation. Male Sprague-Dawley rats were used as donors and recipients of orthotopic liver transplantation (OLT). The donor liver was stored 24 hours in University of Wisconsin (UW) solution at 4 degrees pre-implantation. IP was done by clamp of the portal vein and hepatic artery of the donor liver for 10 minutes followed by reperfusion for 10 minutes before harvesting. The neutrophilic infiltration in liver was quantified using a myeloperoxidase (MPO) assay. Intragraft expression of macrophage inflammatory protein-2 (MIP-2) mRNA was investigated with in situ hybridization. The serum levels of MIP-2 and tumor necrosis factor (TNF)-alpha were also monitored. After liver transplantation without IP, the hepatic MPO increased significantly compared with sham operated group. In IP group, PMN in liver indicated by MPO was reduced significantly. In situ hybridization showed no MIP-2 mRNA in sham group but dramatic expression in hepatocytes in non-IP group. In IP group, MIP-2 mRNA was significantly down-regulated. Similarly, serum MIP-2 and TNF-alpha levels were significantly elevated in non-IP group and both were reduced in IP group. IP might protect graft liver from preservation-reperfusion injury after OLT through down-regulating C-X-C chemokine expression of hepatocytes, and alleviating PMNs recruitment after reperfusion.

Novel roles of liver X receptors exposed by gene expression profiling in liver and adipose tissue.

Liver X receptor (LXR) alpha and LXRbeta are nuclear oxysterol receptors whose biological function has so far been elucidated only with respect to cholesterol and lipid metabolism. To expose novel biological roles for LXRs, we performed genome-wide gene expression profiling studies in liver and white and brown adipose tissue from wild-type (LXRalpha(+/+)beta(+/+)) and knockout mice (LXRalpha(-/-)beta(-/-)) treated with a synthetic LXR agonist. By an adapted statistical analysis, we detected 319 genes significantly regulated by LXR agonist treatment in wild-type but not in knockout mice, fulfilling most stringent criteria with an overall confidence of 94%. Down-regulation of essential enzymes of gluconeogenesis in liver could point to possible beneficial effects of LXR agonists in diabetes mellitus. LXR agonist treatment also altered expression of genes involved in steroid hormone synthesis and growth hormone receptor signaling, emphasizing a potential impact on endocrine function. Notably, LXR agonist treatment up-regulated CYP4A10 and CYP4A14 together with cytochrome P450 reductase, indicating a possible enhancement of microsomal lipid peroxidation. In conclusion, these gene expression profiling data identify novel areas of regulation by LXRs and provide a highly valuable basis for further research on the biological functions of these nuclear receptors and the pharmacological characteristics of their ligands.