Global Hepatic Gene Expression Research Articles

Comparative Analysis of Global Hepatic Gene Expression in Adolescents and Adults with Non-alcoholic Fatty Liver Disease.

To gain insights into the mechanisms underlying distinct nonalcoholic fatty liver disease (NAFLD) histological phenotypes between children and adults, we compared hepatic gene expression profiles associated with NAFLD phenotypes between the two age groups. Histological characteristics of intra-operative liver biopsies from adolescents and adults undergoing bariatric surgery were assessed by the same pathologist using the non-alcoholic steatohepatitis (NASH) Clinical Research Network scoring system. Hepatic gene expression was measured by microarray analysis. Transcriptomic signatures of histological phenotypes between the two groups were compared, with significance defined as p-value <0.05 and a fold change >1.5. In 67 adolescents and 76 adults, distribution of histological phenotypes was: not-NAFLD (controls) 51% vs 39%, NAFL 39% vs 37%, and NASH 10% vs 24%, respectively. There were 279 differentially expressed genes in adolescents and 213 in adults with NAFLD vs controls. In adolescents, transcriptomes for NAFL vs controls, and borderline vs definite NASH were undifferentiable, whereas in adults, NAFL and borderline NASH demonstrated a transcriptomic gradient between controls and definite NASH. When applied to adolescents, significant adult genes discriminated borderline and definite NASH from control and NAFL, but the majority of significant pediatric genes were not portable to adults. Genes associated with NASH in adolescents and adults showed some ontological consistency but notable differences. There is some similarity but major differences in the transcriptomic profiles associated with NAFLD between adolescents and adults with severe obesity. These data suggest different mechanisms contribute to the pathogenesis of NAFLD severity at different stages in life.

Effect of dietary restriction and subsequent realimentation on hepatic oxidative phosphorylation in cattle

Compensatory growth (CG) is a naturally accelerated growth which occurs upon realimentation, following a prior period of dietary restriction. The process is harnessed worldwide as a management practice to reduce feed costs in beef cattle production. The objective of this study was to assess the potential contribution of hepatic cellular mitochondrial capacity to CG through global hepatic oxidative phosphorylation gene expression analyses as well as functional mitochondrial enzyme activity assays. Holstein–Friesian bulls were separated into two groups: (i) restricted feed allowance for 125 days (Period 1) (RES; n = 30) followed by ad-libitum feeding for 55 days (Period 2) or (ii) ad-libitum access to feed throughout (Periods 1 and 2) (ADLIB; n = 30). At the end of each period, 15 animals from each treatment group were slaughtered and hepatic tissue was collected. Tissue samples were subjected to RNAseq and spectrophotometric analysis for the functional assessment of mitochondria. RES and ADLIB groups grew at 0.6 kg/day and 1.9 kg/day, respectively, during Period 1. During Period 2, the RES group underwent CG growing at 2.5 kg/day, with ADLIB animals gaining 1.4 kg/day. Oxidative phosphorylation genes were differentially expressed in response to both dietary restriction and CG. Spectrophotometric assays indicated that mitochondrial abundance was greater in animals undergoing dietary restriction at the end of Period 1 and subsequently reduced during realimentation (P < 0.02). Results indicate that mitochondrial capacity may be enhanced during dietary restriction to more effectively utilize diet-derived nutrients. However, enhanced mitochondrial capacity does not appear to be directly contributing to CG in cattle.

The Diurnal Timing of Starvation Differently Impacts Murine Hepatic Gene Expression and Lipid Metabolism - A Systems Biology Analysis Using Self-Organizing Maps.

Organisms adapt their metabolism and draw on reserves as a consequence of food deprivation. The central role of the liver in starvation response is to coordinate a sufficient energy supply for the entire organism, which has frequently been investigated. However, knowledge of how circadian rhythms impact on and alter this response is scarce. Therefore, we investigated the influence of different timings of starvation on global hepatic gene expression. Mice (n = 3 each) were challenged with 24-h food deprivation started in the morning or evening, coupled with refeeding for different lengths and compared with ad libitum fed control groups. Alterations in hepatocyte gene expression were quantified using microarrays and confirmed or complemented with qPCR, especially for lowly detectable transcription factors. Analysis was performed using self-organizing maps (SOMs), which bases on clustering genes with similar expression profiles. This provides an intuitive overview of expression trends and allows easier global comparisons between complex conditions. Transcriptome analysis revealed a strong circadian-driven response to fasting based on the diurnal expression of transcription factors (e.g., Ppara, Pparg). Starvation initiated in the morning produced known metabolic adaptations in the liver; e.g., switching from glucose storage to consumption and gluconeogenesis. However, starvation initiated in the evening produced a different expression signature that was controlled by yet unknown regulatory mechanisms. For example, the expression of genes involved in gluconeogenesis decreased and fatty acid and cholesterol synthesis genes were induced. The differential regulation after morning and evening starvation were also reflected at the lipidome level. The accumulation of hepatocellular storage lipids (triacylglycerides, cholesteryl esters) was significantly higher after the initiation of starvation in the morning compared to the evening. Concerning refeeding, the gene expression pattern after a 12 h refeeding period largely resembled that of the corresponding starvation state but approached the ad libitum control state after refeeding for 21 h. Some components of these regulatory circuits are discussed. Collectively, these data illustrate a highly time-dependent starvation response in the liver and suggest that a circadian influence cannot be neglected when starvation is the focus of research or medicine, e.g., in the case of treating victims of sudden starvation events.

Investigation of the molecular mechanisms of hepatic injury upon naphthalene exposure in zebrafish (Danio rerio).

Naphthalene has been used worldwide as a commercial insecticide for decades, which when detected in the environment can have various negative effects on non-target organism, such as hepatotoxicity. However, the molecular mechanisms of how naphthalene acts to affect the liver in zebrafish (Danio rerio) remains unknown. In this study, we evaluated the potential toxic effects of naphthalene on livers in female adult zebrafish over a 21-day subacute exposure. Global hepatic gene expression was examined by microarrays and the results indicated the regulated genes were associated significantly with vital hepatic injury pathways and GO categories upon naphthalene exposure, such as disruptions in lipid metabolism, inflammatory response, and the carcinogenic processes. According to our observations of liver histology, nuclear enlargement as a potential indicator of cancers and hepatic lipometabolic disorder precisely were supported. The 96 h acute naphthalene tests on Tg(lysC:DsRed) and LiPan lines larvae revealed recruitment of neutrophils by the liver, as well as decreased liver size, which further confirmed hepatic inflammation response to naphthalene exposure. Thus, these findings advance the field of ecotoxicology by unveiling a new role of naphthalene as a leading cause of liver damage and provide potential biomarker-genes for environmental naphthalene monitoring.

Maternal Obesity Programs Offspring's Predisposition to Non‐Alcoholic Fatty Liver Disease and Steatohepatitis

Maternal obesity and unbalanced diets during pregnancy are key factors in determining the risk of obesity in later life. Non‐alcoholic fatty liver disease (NAFLD) is an important co‐morbidity associated with obesity and metabolic dysfunction and a precursor to steatohepatitis (NASH). However, the contributions of gestational and early neonatal influences on development of NAFLD and subsequent NASH remain poorly appreciated. Using a model of controlled overfeeding, we have previously demonstrated that in utero exposure to maternal obesity during pregnancy alone leads to metabolic programming of liver, characterized by metabolic inflexibility. Here we examine the hypothesis that maternal over‐nutrition via in utero exposure to high fat diet induces inflammation and leads to exacerbated hepatic responses to post‐natal high fat diets (HFD) and methionine choline deficient (MCD) diets in the offspring. Female C57BL6/J mice were fed diets with either low (10%) or HFD (45% of calories) for 12 wk starting at 5 wk of age. Dams were mated with males on control diets and provided access to respective diets during pregnancy and lactation. At weaning, offspring were weaned onto control and HFD, creating four groups (CC, CH, HC, HH, denoting maternal and offspring diets, respectively). Offspring of obese mice dams (HH n=7) gained greater body weight and fat mass when fed HFD, compared to offspring from lean dam (CH n=11). Serum cholesterol concentrations were higher in HH compared to CH groups. Global hepatic gene expression and microbial ecology of the cecal contents in offspring was studied using RNAseq and 16S rRNA sequencing. Hepatic expression of Mcp1 and MMP13 gene expression was higher in HH compared to CC and CH indicative of inflammation in response to maternal high fat diet. Analysis of microbial OTUs with Multivariate association with linear models (MaAsLin) and LeFSE showed higher abundance of Firmicutes and lower abundance of Bacteriodetes in HH as well as CH compared to CC. To assess the susceptibility of offspring to NASH, 8 wk old offspring in a separate study were challenged with either control or MCD diets for 4 wk. MCD diet led to significant weight reduction irrespective of maternal nutritional background. Serum ALT was modestly higher in offspring from obese dams (HFD/MCD) relative to lean dam cohorts. Offspring of HF dams showed similar inflammatory changes but greater pro‐fibrogenic alterations following MCD diet. MaAsLin and LeFSE analysis revealed association between serum ALT levels, Coprococcus and MCD treatment. Genome‐scale DNA methylation of livers showed alterations in CpGs associated with cell adhesion, cell communication and development with MCD challenge, including genes in the TGF‐β signaling pathways. Overall, our findings indicate that maternal obesity during gestation and lactation detrimentally alters epigenetic and gut microbiome pathways to favor development of fatty liver disease and its progressive sequelae.Support or Funding InformationSupport USDA CRIS 6206‐51000‐010‐05S

Acute Exposure to Tris(1,3-dichloro-2-propyl) Phosphate (TDCIPP) Causes Hepatic Inflammation and Leads to Hepatotoxicity in Zebrafish.

Tris(1,3-dichloro-2-propyl) phosphate (TDCIPP) has been frequently detected in environmental media and has adverse health effect on wildlife and humans. It has been implicated to have hepatotoxicity, but its molecular mechanisms remain unclear. In the present study, adult male zebrafish were exposed to TDCIPP and global hepatic gene expression was examined by RNA-Seq and RT-qPCR in order to understand the molecular mechanisms of TDCIPP-induced hepatotoxicity. Our results indicated that TDCIPP exposure significantly up-regulated the expression of genes involved in endoplasmic reticulum stress and Toll-like receptor (TLR) pathway, implying an inflammatory response, which was supported by up-regulation of inflammation-related biomaker genes. Hepatic inflammation was further confirmed by histological observation of increase of infiltrated neutrophils and direct observation of liver recruitment of neutrophils labeled with Ds-Red fluorescent protein of Tg(lysC:DsRed) zebrafish upon TDCIPP exposure. To further characterize the hepatotoxicity of TDCIPP, the expression of hepatotoxicity biomarker genes, liver histopathology and morphology were examined. The exposure to TDCIPP significantly up-regulated the expression of several biomarker genes for hepatotoxicity (gck, gsr and nqo1) and caused hepatic vacuolization and apoptosis as well as increase of the liver size. Collectively, our results suggest that exposure to TDCIPP induces hepatic inflammation and leads to hepatotoxicity in zebrafish.

Changes in cholesterol homeostasis and acute phase response link pulmonary exposure to multi-walled carbon nanotubes to risk of cardiovascular disease

Adverse lung effects following pulmonary exposure to multi-walled carbon nanotubes (MWCNTs) are well documented in rodents. However, systemic effects are less understood. Epidemiological studies have shown increased cardiovascular disease risk after pulmonary exposure to airborne particles, which has led to concerns that inhalation exposure to MWCNTs might pose similar risks.We analyzed parameters related to cardiovascular disease, including plasma acute phase response (APR) proteins and plasma lipids, in female C57BL/6 mice exposed to a single intratracheal instillation of 0, 18, 54 or 162μg/mouse of small, entangled (CNTSmall, 0.8±0.1μm long) or large, thick MWCNTs (CNTLarge, 4±0.4μm long). Liver tissues and plasma were harvested 1, 3 and 28days post-exposure. In addition, global hepatic gene expression, hepatic cholesterol content and liver histology were used to assess hepatic effects.The two MWCNTs induced similar systemic responses despite their different physicochemical properties. APR proteins SAA3 and haptoglobin, plasma total cholesterol and low-density/very low-density lipoprotein were significantly increased following exposure to either MWCNTs. Plasma SAA3 levels correlated strongly with pulmonary Saa3 levels. Analysis of global gene expression revealed perturbation of the same biological processes and pathways in liver, including the HMG-CoA reductase pathway. Both MWCNTs induced similar histological hepatic changes, with a tendency towards greater response following CNTLarge exposure.Overall, we show that pulmonary exposure to two different MWCNTs induces similar systemic and hepatic responses, including changes in plasma APR, lipid composition, hepatic gene expression and liver morphology. The results link pulmonary exposure to MWCNTs with risk of cardiovascular disease.

Bromodeoxyuridine (BrdU) treatment to measure hepatocellular proliferation does not mask furan-induced gene expression changes in mouse liver.

Bromodeoxyuridine (BrdU) is a synthetic nucleoside used to detect cellular proliferation. BrdU incorporates in the place of thymine but pairs with guanine, thereby increasing the risk of transition mutations in dividing cells. Given its mutagenicity, standard practice is to use a second cohort of animals for parallel toxicogenomics studies; however, the impact of BrdU on global gene expression is unknown. To test this, we performed a case study to determine whether the molecular mode of action of furan, a liver carcinogen, could be detected in BrdU-treated samples. We measure global hepatic gene expression using Agilent DNA microarrays in female B6C3F1 mice that were sub-chronically exposed to 0, 1, 4, or 8mg/kg bodyweight (bw) per day furan either in the presence (+BrdU) or absence (-BrdU) of BrdU. Exposure to 0.02% BrdU in drinking water for five days resulted in minimal gene expression changes. A comparison of +BrdU versus -BrdU control mice revealed only 11 probes with fold change≥1.5 and false discovery rate (FDR) corrected p≤0.05. The same comparison in the high dose group yielded only 3 differentially expressed probes. Differentially expressed gene lists generated for furan-treated versus control mice and were compared for the -BrdU and +BrdU groups. The high dose of furan had 452 shared probes and 27 and 90 unique probes for -BrdU and +BrdU groups, respectively. These differences did not impact hierarchical clustering. Further, they did not impair detection of the previously reported furan mode of action, which was well represented in the BrdU-treated samples. Taken together, we demonstrate that BrdU treatment does not mask important furan-induced transcriptional changes. We suggest that BrdU-treated mice could be used for toxicogenomic analysis, which would generally halve the number of rodents required for toxicogenomics studies. However, we also recommend that this type of case study be repeated for other chemicals before the use of BrdU-treated animals in omics studies becomes common practice.

Effects of contact dermatitis on hepatic gene expression in broilers

1. Severe foot and hock dermatitis in broiler chickens can reduce growth rate and increase susceptibility to bacterial infection, affecting both profitability and welfare. However, little is known about the underlying physiological changes associated with foot and hock lesions. 2. This study compared global hepatic gene expression in control birds and those with ammonia-induced foot and hock lesions using Agilent 44 K chicken oligonucleotide microarrays (8 birds per group). 3. In total, 417 genes were differentially expressed of which 174 could be mapped onto the genome. Genes associated with energy metabolism, thyroid hormone activity and cellular control were affected, while there was also evidence of an up-regulation of genes linked to a pro-inflammatory response. 4. It is conceivable that pain is the underlying cause for the observed changes in energy metabolism genes. 5. Changes in hepatic gene expression provide new information on how a chicken's physiological mechanisms alter to cope with foot and hock lesions. The findings support other data indicating that birds with increased severity of lesions are likely to be in pain and that growth will be compromised. Reduction of the incidence of dermatitis by improved husbandry should therefore benefit both welfare and commercial performance.

Global hepatic gene expression in rainbow trout exposed to sewage effluents: A comparison of different sewage treatment technologies

Effluents from sewage treatment plants contain a mixture of micropollutants with the potential of harming aquatic organisms. Thus, addition of advanced treatment techniques to complement existing conventional methods has been proposed. Some of the advanced techniques could, however, potentially produce additional compounds affecting exposed organisms by unknown modes of action. In the present study the aim was to improve our understanding of how exposure to different sewage effluents affects fish. This was achieved by explorative microarray and quantitative PCR analyses of hepatic gene expression, as well as relative organ sizes of rainbow trout exposed to different sewage effluents (conventionally treated, granular activated carbon, ozonation (5 or 15mg/L), 5mg/L ozone plus a moving bed biofilm reactor, or UV-light treatment in combination with hydrogen peroxide). Exposure to the conventionally treated effluent caused a significant increase in liver and heart somatic indexes, an effect removed by all other treatments. Genes connected to xenobiotic metabolism, including cytochrome p450 1A, were differentially expressed in the fish exposed to the conventionally treated effluents, though only effluent treatment with granular activated carbon or ozone at 15mg/L completely removed this response. The mRNA expression of heat shock protein 70kDa was induced in all three groups exposed to ozone-treated effluents, suggesting some form of added stress in these fish. The induction of estrogen-responsive genes in the fish exposed to the conventionally treated effluent was effectively reduced by all investigated advanced treatment technologies, although the moving bed biofilm reactor was least efficient. Taken together, granular activated carbon showed the highest potential of reducing responses in fish induced by exposure to sewage effluents.

MODULATION OF TOLL-LIKE RECEPTOR GENES WITH SELECTIVE GUT DECONTAMINATION IN CIRRHOTIC ANIMALS PREVENTS THE DEVELOPMENT OF ACUTE-ON CHRONIC LIVER FAILURE (ACLF)

Introduction Acute deterioration in the liver function following precipitating illness in patients with cirrhosis often lead to multiple organ failure. Inflammation is thought to be a major contributing factor. We hypothesised that toll like receptor9s (TLRs) play a pivotal role in lipopolysaccharide (LPS) mediated cytokine surge in patients with cirrhosis culminating in acute-on-chronic liver failure (ACLF). Selective gut decontamination with Norfloxacin would dampen this inflammatory cascade. Methods Global hepatic gene expression was studied in a rodent model of cirrhosis induced by bile duct ligation (BDL) (Agilent microarray) and compared the results to sham animals. TLR related genes were among the differentially expressed genes in the liver. We validated gene expression in the Liver and Kidney in a second set of experiment in Sham, BDL, BDL+LPS, BDL+Norfloxacin, BDL+Norfloxacin+LPS groups using the quantitative real-time PCR. Cytokines (Becton Dickenson) and biochemistry were measured (COBAS Integra 400). Results Among the several genes with high expression in the BDL group as detected by the microarray, both TLR 4 and 2 had significantly higher expression in liver and Kidney compared with the sham group. We also found a marked upregulation of the C-C motif ligand 2 (CCl2) and C-X-C motif ligand 2(CxCl2) Furthermore, LPS administration in BDL animals accentuated not only the TLRs (4 and 2) expression in both kidney and liver but also the Cxcl2 and CCl2 in both these organs associated with deterioration organ function as suggested with a rise in the liver enzyme, creatinine and a rise in plasma and tissue cytokines. Norfloxacin pre-treatment in BDL group (BDL+Norfloxacin) attenuated the TLR4 and TLR2 expression in both liver and kidney. Selective decontamination with Norfloxacin in BDL +LPS animals limited the upregulation of TLR4 and TLR2 in the Liver and Kidney. It also prevented the upregulation of the CxcL2 and CCl2 in both these organs. This was associated with significant improvement in liver enzymes, creatinine and cytokines. Conclusion This study shows that the liver and kidneys in cirrhotic animals are primed by upregulation of TLR9s and its downstream inflammatory mediators in the Liver and Kidney which make them exquisitely sensitive to the effects of superimposed infection/inflammation leading to organ failure. Selective decontamination with Norfloxacin prevents the progression of ACLF by reducing gene expression of TLR 2 and 4 and its associated inflammatory adaptors. Competing interests None declared.

Differential hepatic gene expression in the broiler chicken in response to the combined stressors of food withdrawal, catching and transport at the end of production

Broiler (meat) chickens experience the combined acute stressors of food withdrawal, catching and transport (FCT) prior to slaughter as part of normal commercial practice at the end of their lives. This has associated physiological consequences, potentially affecting both welfare and meat quality, some of which are mediated through altered hepatic function. This study compared global hepatic gene expression between control birds and those exposed to commercial FCT using 20K chicken oligonucleotide microarrays. In response to FCT, 733 genes were differentially expressed of which 486 could be mapped onto the genome. The principal molecular and cellular functions thus affected by FCT involved lipid and carbohydrate metabolism with a suppression of mRNA expression for genes involved in lipogenesis, glycolysis and glycogenolysis and an induction of those involved in gluconeogenesis, fatty acid metabolism and ketone synthesis. There was also significant differential expression of genes associated with cellular control and immune function. These stressful events associated with FCT in commercial broiler chickens altered expression of hepatic genes associated with energy metabolism, with exhaustion of stored hepatic and pectoral muscle glycogen. A better understanding of FCT-induced stress through the use of gene expression arrays may in future inform husbandry practices, to improve both welfare and meat quality.

Diclofenac in fish: Blood plasma levels similar to human therapeutic levels affect global hepatic gene expression

Diclofenac is a nonsteroidal anti-inflammatory drug frequently found in the aquatic environment. Previous studies have reported histological changes in the liver, kidney, and gills of fish at concentrations similar to those measured in treated sewage effluents (approximately 1 µg/L). Analyses or predictions of blood plasma levels in fish allow a direct comparison with human therapeutic plasma levels and may therefore be used to indicate a risk for pharmacological effects in fish. To relate internal exposure to a pharmacological interaction, we investigated global hepatic gene expression together with bioconcentration in blood plasma and liver of rainbow trout (Oncorhynchus mykiss) exposed to waterborne diclofenac. At the highest exposure concentration (81.5 µg/L), the fish plasma concentration reached approximately 88% of the human therapeutic levels (C(max) ) after two weeks. Using an oligonucleotide microarray followed by quantitative PCR, we found extensive effects on hepatic gene expression at this concentration, and some genes were found to be regulated down to the lowest exposure concentration tested (1.6 µg/L), corresponding to a plasma concentration approximately 1.5% of the human C(max) . Thus, at concentrations detected in European surface waters, diclofenac can affect the expression of multiple genes in exposed fish. Functional analysis of differentially expressed genes revealed effects on biological processes such as inflammation and the immune response, in agreement with the mode of action of diclofenac in mammals. In contrast to some previously reported results, the bioconcentration factor was found to be stable (4.02 ± 0.75 for blood plasma and 2.54 ± 0.36 for liver) regardless of the water concentration.

Hepatic gene networks in morbidly obese patients with nonalcoholic fatty liver disease.

Genetic factors alter the risk for nonalcoholic fatty liver disease (NAFLD). We sought to identify NAFLD-associated genes and elucidate gene networks and pathways involved in the pathogenesis of NAFLD. Quantitative global hepatic gene expression analysis was performed on 53 morbidly obese Caucasian subjects undergoing bariatric surgery (27 with NAFLD and 26 controls). After standardization of data, gene expression profiles were compared between patients with NAFLD and controls. The set of genes that significantly correlated with NAFLD was further analyzed by hierarchical clustering and ingenuity pathways analyses. There were 25,643 quantitative transcripts, of which 108 were significantly associated with NAFLD (p < 0.001). Canonical pathway analysis in the NAFLD-associated gene clusters showed that the hepatic fibrosis signaling was the most significant pathway in the up-regulated NAFLD gene cluster containing three (COL1A1, IL10, IGFBP3) significantly altered genes, whereas the endoplasmic reticulum stress and protein ubiquitination pathways were the most significant pathways in the down-regulated NAFLD gene cluster, with the first pathway containing one (HSPA5) and the second containing two (HSPA5, USP25) significantly altered genes. The four primary gene networks associated with NAFLD were involved in cell death, immunological disease, cellular movement, and lipid metabolism with several significantly altered "hub" genes in these networks. This study reveals the canonical pathways and gene networks associated with NAFLD in morbidly obese Caucasians. The application of gene network analysis highlights the transcriptional relationships among NAFLD-associated genes and allows identification of hub genes that may represent high-priority candidates for NAFLD.

The effects of Acanthopanax senticosus on global hepatic gene expression in rats subjected to heat environmental stress

To determine whether heat environmental stress (HES) affects the livers of rats, we investigated microarray-based expression profiling using an Affymatrix Gene Chip Rat genome 230 2.0 Array. We were also able to examine the effects of Acanthopanax senticosus extract (ASE) on the gene expression profile. Heat environmental stress (HES) induced changes in gene expression transcript profiles, including those related to fatty acid synthase activity, oxidoreductase activity and lipid peroxidation (LPO). We observed dramatically increased malonaldehyde (MDA) levels after HES, which indicates that HES caused LPO through the regulation of oxidative stress and LPO-related transcripts, as revealed by microarray. When ASE was orally administered to the HES group, the number of candidate validation genes as well as the MDA content decreased in comparison to rats that did not receive ASE. Furthermore, rats in the HES group that received orally administered ASE experienced significantly lower oxidative stress, as indicated by the expression of certain genes. Based on the combined results of this study, we concluded that a number of the functional responses to HES at the RNA expression level were revealed by the increased MDA content, which supports the use of rodent models for the study of heat environmental stress. These data indicate that ASE acts as a strong antioxidant in addition to exerting anti-HES effects.

Modulation of hepatic PPAR expression during Ft LVS LPS-induced protection from Francisella tularensis LVS infection.

BackgroundIt has been shown previously that administration of Francisella tularensis (Ft) Live Vaccine Strain (LVS) lipopolysaccharide (LPS) protects mice against subsequent challenge with Ft LVS and blunts the pro-inflammatory cytokine response.MethodsTo further investigate the molecular mechanisms that underlie Ft LVS LPS-mediated protection, we profiled global hepatic gene expression following Ft LVS LPS or saline pre-treatment and subsequent Ft LVS challenge using Affymetrix arrays.ResultsA large number of genes (> 3,000) were differentially expressed at 48 hours post-infection. The degree of modulation of inflammatory genes by infection was clearly attenuated by pre-treatment with Ft LVS LPS in the surviving mice. However, Ft LVS LPS alone had a subtle effect on the gene expression profile of the uninfected mice. By employing gene set enrichment analysis, we discovered significant up-regulation of the fatty acid metabolism pathway, which is regulated by peroxisome proliferator activated receptors (PPARs).ConclusionsWe hypothesize that the LPS-induced blunting of pro-inflammatory response in mouse is, in part, mediated by PPARs (α and γ).

Pharmaceutical industry effluent diluted 1:500 affects global gene expression, cytochrome P450 1A activity, and plasma phosphate in fish

Patancheru, near Hyderabad, India, is a major production site for the global bulk drug market. Approximately 90 manufacturers send their wastewater to a common treatment plant in Patancheru. Extraordinary high levels of a wide range of pharmaceuticals have recently been demonstrated in the treated effluent. As little as 0.2% of this effluent can strongly reduce the growth rate of tadpoles, but the underlying mechanisms of toxicity are not known. To begin addressing how the effluent affects aquatic vertebrates, rainbow trout (Oncorhynchus mykiss) were exposed to 0.2% effluent for 5 d. Several physiological endpoints, together with effects on global hepatic gene expression patterns, were analyzed. The exposed fish showed both an induction of hepatic cytochrome P450 1A (CYP1A) gene expression, as well as enzyme activity. Clinical blood chemistry analyses revealed an increase in plasma phosphate levels, which in humans indicates impaired kidney function. Several oxidative stress-related genes were induced in the livers; however, no significant changes in antioxidant enzyme activities or in the hepatic glutathione levels were found. Furthermore, estrogen-regulated genes were slightly up-regulated following exposure, and moderate levels of estriol were detected in the effluent. The present study identifies changes in gene expression triggered by exposure to a high dilution of the effluent, supporting the hypothesis that these fish are responding to chemical exposure. The pattern of regulated genes may contribute to the identification of mechanisms of sublethal toxicity, as well as illuminate possible causative agents.

Hepatic gene expression following consumption of soy protein isolate in female Sprague–Dawley rats differs from that produced by 17β-estradiol treatment

Although soy foods have been recognized as an excellent source of protein, there have been recent concerns regarding potential adverse effects of isoflavone phytochemicals found in soy products, which are known to bind and activate estrogen receptors. Here, we used global hepatic gene expression profiles in ovariectomized female Sprague-Dawley rats treated with 17beta-estradiol (E(2)) or fed with soy protein isolate (SPI) as a means of estimating potential estrogenicity of SPI. Female Sprague-Dawley rats were fed AIN-93G diets containing casein (CAS) or SPI starting at postnatal day (PND) 30. Rats were ovariectomized on PND 50 and infused with E(2) or vehicle in osmotic pumps for 14 d. Microarray analysis was performed on liver using Affymetrix GeneChip Rat 230 2.0. Serum E(2) levels were within normal ranges for the rat and SPI feeding did not increase uterine wet weight in the absence or presence of E(2). SPI feeding altered (P<0.05, >or=+/-1.5-fold) the expression of 82 genes, while E(2) treatment altered 892 genes. Moreover, only 4% of E(2)-affected genes were also modulated by SPI, including some whose expression was reversed by SPI feeding. The interaction between E(2) and SPI uniquely modulated the expression profile of 225 genes including the reduction of those involved in fatty acid biosynthesis or glucocorticoid signaling and an induction of those involved in cholesterol metabolism. The different hepatic gene signatures produced by SPI feeding compared with E(2) and the lack of increase in uterine wet weight in rats fed with SPI suggest that SPI is not estrogenic in these tissues.

Microarray analysis of mitogenic effects of T3 on the rat liver

A single dose of the thyroid hormone tri-iodothyronine, T3, can enhance both size and function of normal rodent liver, which is potentially of value in the treatment of liver disease. However the mechanism of this has not been fully elucidated, and it cannot be modeled in vitro. We therefore investigated the transcriptome response to T3 in rat liver in vivo. After adult rats were administered 5 microg T3 subcutaneously, a whole rat genome microarray comparing global hepatic gene expression against vehicle-only treated liver after 3 h was performed. Informative transcripts which had identifiable gene ontology biological processes were grouped according to function, broadly reflecting general metabolic effects and those linked to cell-proliferation control. We then compared the transcriptome response after 5-microg T3 initiating hepatocyte DNA synthesis (mitogenic) with that after 0.1 microg T3, a supraphysiological amount not initiating hepatocyte DNA synthesis. We compared the results with published results of the response to other primary mitogens, and identified the Gadd45beta/MyD118 gene as a common early factor upregulated during proliferation.

Leukocyte‐derived Myeloperoxidase modulates the expression of multiple Hepatic Gene Families during acute systemic Inflammation

Myeloperoxidase (MPO) is a hemoprotein/enzyme abundantly expressed by leukocytes [neutrophils, macrophages, kupfer cells (liver)] that catalyzes the formation of free radical species implicated in inflammatory processes. The capacity of MPO to modulate gene expression during inflammatory events remains incompletely characterized. We have compared global hepatic gene expression profiles in male wild‐type (MPO+/+) and MPO‐deficient (MPO−/−) mice subjected to endotoxemia. Male mice were euthanized 24 hrs following i.p. injection of either sterile saline or E. coli LPS (10 mg/kg), liver tissue harvested, mRNA extracted and subjected to microarray analysis using Affymetrix 430 2.0 GeneChips. Global gene expression analysis demonstrated that the number of differentially expressed genes in LPS treated MPO−/− mice were dramatically higher (3156 genes) than MPO+/+ mice (1519 genes). The data showed a LPS‐induced upregulation of genes related to inflammatory‐immune responses in both MPO+/+ and MPO−/− mice. Genes related to metabolic processes were downregulated in both MPO+/+ and MPO−/− mice treated with LPS, where the effect was more in MPO−/− mice (342 genes) as compared to MPO+/+ mice (128 genes). The present data suggest that inflammatory and metabolic processes are co‐ordinately dysregulated in LPS‐challenged MPO−/− mice and provide documentation of novel genes which might be regulated by MPO.