Induction of molecular chaperones in carbon tetrachloride–treated rat liver: implications in protection against liver damage

Advanced Diagnostic Tools in Hypothermia-Related Fatalities-A Pathological Perspective

BACKGROUND AND OBJECTIVES

Although classical gross features are known in hypothermia victims, they lack specific diagnosis features. The aim of our study was to reveal specific brain and lung pathological features in a group of hypothermia-related fatalities.

MATERIALS AND METHODS

The study group comprised 107 cases from our files associated with hypothermia. Routine hematoxylin-eosin (H&E) staining and postmortem immunohistochemistry were performed.

RESULTS

The microscopic cerebral exam revealed diffuse perineuronal and perivascular edema, gliosis, mononuclear cell infiltration, acute brain injuries, focal neuronal ischemia, lacunar infarction, and variable hemorrhages. Variable alveolar edema, pulmonary emphysema, intra-alveolar and/or pleural hemorrhage, and bronchopneumonia, as well as other pre-existing lesions, were identified in lung tissue samples. Glial cells displayed S100β expression, while neurons showed moderate Hsp70 immunopositivity. Alveolar basal membranes exhibited diffuse ICAM-1 positive expression, while ICAM-1 and AQP-1 positivity was observed in the alveolar septum vascular endothelium. Statistical analysis revealed a significant correlation between S100β and Hps70 immunoexpression and cerebral pathological features, between ICAM-1 immunoexpression and alveolar edema and pulmonary emphysema, and between AQP-1 immunoexpression and pulmonary emphysema.

CONCLUSIONS

Our results add supplementary data to brain and lung pathological findings in hypothermia-related fatalities, with potential therapeutic value in hypothermia patients.

S100A6 Activates Kupffer Cells via the p-P38 and p-JNK Pathways to Induce Inflammation, Mononuclear/macrophage Infiltration Sterile Liver Injury in Mice

Noninfectious liver injury, including the effects of chemical material, drugs and diet, is a major cause of liver diseases worldwide. In chemical and drugs-induced liver injury, innate inflammatory responses are mediated by extracellular danger signals. The S100 protein can act as danger signals, which can promote the migration and chemotaxis of immune cells, promote the release of various inflammatory cytokines, and regulate the body's inflammatory and immune responses. However, the role of S100A6 in inflammatory response in chemical and drugs-induced sterile liver injury remains unclear. We constructed the model of sterile liver injury induced by carbon tetrachloride (CCl₄)/Paracetamol (APAP) and performed RNA sequencing (RNA-seq) on the liver tissues after injury (days 2 and 5). We analyzed inflammatory protein secretion in the liver tissue supernatant by enzyme-linked immunosorbent assay (ELISA), determined the inflammation response by bioinformatic analysis during sterile liver injury, and assessed mononuclear/macrophage infiltration by immunohistochemistry and flow cytometry. Immunohistochemistry was used to analyze the location of S100A6. We conducted inflammatory factor expression analysis and molecular mechanistic studies in Kupffer cells (KCs) induced by S100A6 using quantitative reverse transcription-polymerase chain reaction (qRT-PCR), ELISA, and western blot in vitro experiments. We performed chemokine CCL2 expression analysis and molecular mechanism studies using the same method. We used a Transwell assay to show the infiltration of mononuclear/macrophage. We here observed that aggravated inflammatory response was shown in CCl₄ and APAP-administrated mice, as evidenced by enhanced production of inflammatory cytokines (TNF-α, IL-1β), and elevated mononuclear/macrophage infiltration and activation of immunity. The expression of S100A6 was significantly increased on day 2 after sterile liver injury, which is primarily produced by injured liver cells. Mechanistic studies established that S100A6 activates Kupffer cells (KCs) via the p-P38, p-JNK and P65 pathways to induce inflammation in vitro. Furthermore, TNF-α can stimulate liver cells via the p-P38 and p-JNK pathways to produce CCL2 and promote the infiltration of mononuclear/macrophage. In summary, we showed that S100A6 plays an important role in regulating inflammation, thus influencing sterile liver injury. Our findings provide novel evidence that S100A6 can as a danger signal that contributes to pro-inflammatory activation through p-P38 and p-JNK pathways in CCl₄ and APAP-induced sterile liver injury in mice. In addition, the inflammatory factor TNF-α induces a large amount of CCL2 production in normal liver cells surrounding the injured area through a paracrine action, which is chemotactic for blood mononuclear/macrophage infiltration.

Role of the mTOR-autophagy-ER stress pathway in high fructose-induced metabolic-associated fatty liver disease

Metabolic-associated fatty liver disease (MAFLD) is the most common metabolic disease with a global prevalence of 25%. While MAFLD is serious and incurable at the later stage, it can be controlled or reversed at the early stage of hepatosteatosis originating from unhealthy diets. Recent laboratory evidence implicates a critical role of the mammalian target of rapamycin (mTOR)-autophagy signaling pathway in the pathogenesis of MAFLD induced by a high-fructose diet mimicking the overconsumption of sugar in humans. This review discusses the possible molecular mechanisms of mTOR-autophagy-endoplasmic reticulum (ER) stress in MAFLD. Based on careful analysis of recent studies, we suggest possible new therapeutic concepts or targets that can be explored for the discovery of new anti-MAFLD drugs.

Mushroom-Derived Medicine? Preclinical Studies Suggest Potential Benefits of Ergothioneine for Cardiometabolic Health

Medicinal use of mushrooms has been documented since ancient times, and in the modern world, mushrooms have a longstanding history of use in Eastern medicine. Recent interest in plant-based diets in Westernized countries has brought increasing attention to the use of mushrooms and mushroom-derived compounds in the prevention and treatment of chronic diseases. Edible mushrooms are the most abundant food sources of the modified amino acid, ergothioneine. This compound has been shown to accumulate in almost all cells and tissues, but preferentially in those exposed to oxidative stress and injury. The demonstrated cytoprotectant effect of ergothioneine has led many to suggest a potential therapeutic role for this compound in chronic conditions that involve ongoing oxidative stress and inflammation, including cardiovascular and metabolic diseases. However, the in vivo effects of ergothioneine and its underlying therapeutic mechanisms in the whole organism are not as clear. Moreover, there are no well-defined, clinical prevention and intervention trials of ergothioneine in chronic disease. This review highlights the cellular and molecular mechanisms of action of ergothioneine and its potential as a Traditional, Complementary and Alternative Medicine for the promotion of cardiometabolic health and the management of the most common manifestations of cardiometabolic disease.

Mannan-binding lectin deficiency exacerbates sterile liver injury in mice through enhancing hepatic neutrophil recruitment

Noninfectious liver injury, including the effects of drugs and diet, is a major cause of liver diseases worldwide. The innate inflammatory response to hepatocyte death plays a crucial role in the outcome of liver injury. Mannan-binding lectin (MBL) is a pattern recognition molecule of the innate immune system, which is primarily produced by liver. MBL deficiency occurs with high frequency in the population and is reported associated with predisposition to infectious diseases. We here observed that genetic MBL ablation strongly sensitizes mice to sterile liver injury induced by carbon tetrachloride (CCl₄ ). Aggravated liver damage was shown in CCl₄ -administrated MBL^-/- mice, as evidenced by severe hepatocyte death, elevated serum alanine aminotransferase and lactate dehydrogenase activity, and enhanced production of inflammatory cytokines. Mechanistic studies established that MBL deficiency caused increased chemokine CXCL2 production from liver macrophages upon CCl₄ stimulation, thereby promoting the hepatic recruitment of neutrophils and subsequent liver damage. Furthermore, MBL-mediated protection from CCl₄ -induced liver injury was validated by administration of an MBL-expressing liver-specific adeno-associated virus, which effectively ameliorated the hepatic damage in CCl4-treated MBL^-/- mice. We propose that MBL may be exploited as a new therapeutic approach in the treatment of chemical-induced sterile liver injury in patients with MBL deficiency.

Liver ergothioneine accumulation in a guinea pig model of non-alcoholic fatty liver disease. A possible mechanism of defence?

L-ergothioneine (ET), a putative antioxidant compound acquired by animals through dietary sources, has been suggested to accumulate in certain cells and tissues in the body that are predisposed to high oxidative stress. In the present study, we identified an elevation of ET in the liver of a guinea pig model of non-alcoholic fatty liver disease (NAFLD), elucidated a possible mechanism for the increased uptake and investigated the possible role for this accumulation. This increase in liver ET levels correlated with cholesterol accumulation and disease severity. We identified an increase in the transcriptional factor, RUNX1, which has been shown to upregulate the expression of the ET-specific transporter OCTN1, and could consequently lead to the observable elevation in ET. An increase was also seen in heat shock protein 70 (HSP70) which seemingly corresponds to ET elevation. No significant increase was observed in oxidative damage markers, F2-isoprostanes, and protein carbonyls, which could possibly be attributed to the increase in liver ET through direct antioxidant action, induction of HSP70, or by chelation of Fe(2+), preventing redox chemistry. The data suggest a novel mechanism by which the guinea pig fatty liver accumulates ET via upregulation of its transporter, as a possible stress response by the damaged liver to further suppress oxidative damage and delay tissue injury. Similar events may happen in other animal models of disease, and researchers should be aware of the possibility.

Effects of a mixture of volatile organic compounds on total DNA and gene expression of heat shock proteins in Drosophila melanogaster

The genotoxic effects of a mixture of 13 volatile organic compounds (VOCs) on total DNA profiles and the expression of heat shock proteins (HSPs) HSP26, HSP60, HSP70, and HSP83 in fruit fly tissues were examined. Drosophila melanogaster Oregon R(+), reared under controlled conditions on artificial diets, was treated with 13 VOCs commonly found in water at concentrations of 10, 20, 50, and 75 ppb for 1 and 5 days. Band changes were clearly detected in random amplified polymorphic DNA assay, especially at the 50- and 75-ppb exposure levels, for both treatment periods. In addition, there were clear differences in the band profiles of the treated and untreated flies with changes in the band intensity and the loss/appearance of bands. Although the genomic template stability (GTS) exhibited irregular changes at the first day, significant decreases in GTS were observed after 5 days of VOC application. The lowest GTS value (27.77 ± 1.96 %) was detected at the 75-ppb level after 5 days of the treatment. Quantitative real-time polymerase chain reaction analysis showed a significant increase in the relative expression of HSP26 and HSP60 after 1 and 5 days of the treatment, respectively. The expression of HSP70 increased significantly at all treatment concentrations and times. However, the greatest increase in expression level of HSP70 (4.2-fold) occurred at 20 ppb after 5 days of the treatment. HSP83 was the least affected by exposure to the VOCs. We conclude that trace levels of a mixture of VOCs can exert genotoxic effects on both total DNA and HSP levels in Drosophila.

Semi-quantitative analyses of hippocampal heat shock protein-70 expression based on the duration of ischemia and the volume of cerebral infarction in mice

Objective

We investigated the expression of hippocampal heat shock protein 70 (HSP-70) infarction volume after different durations of experimental ischemic stroke in mice.

Methods

Focal cerebral ischemia was induced in mice by occluding the middle cerebral artery with the modified intraluminal filament technique. Twenty-four hours after ischemia induction, both hippocampi were extracted for HSP-70 protein analyses. Slices from each hemisphere were stained with 2,3,5-triphenyltetrazolium chloride (2%), and infarction volumes were calculated. HSP-70 levels were evaluated using western blot and enzyme-linked immunosorbent assay (ELISA). HSP-70 subtype (hsp70.1, hspa1a, hspa1b) mRNA levels in the hippocampus were measured using reverse transcription-polymerase chain reaction (RT-PCR).

Results

Cerebral infarctions were found ipsilateral to the occlusion in 10 mice exposed to transient ischemia (5 each in the 30-min and 60-min occlusion groups), whereas no focal infarctions were noted in any of the sham mice. The average infarct volumes of the 2 ischemic groups were 22.28±7.31 mm³ [30-min group±standard deviation (SD)] and 38.06±9.53 mm³ (60-min group±SD). Western blot analyses and ELISA showed that HSP-70 in hippocampal tissues increased in the infarction groups than in the sham group. However, differences in HSP-70 levels between the 2 infarction groups were statistically insignificant. Moreover, RT-PCR results demonstrated no relationship between the mRNA expression of HSP-70 subtypes and occlusion time or infarction volume.

Conclusion

Our results indicated no significant difference in HSP-70 expression between the 30- and 60-min occlusion groups despite the statistical difference in infarction volumes. Furthermore, HSP-70 subtype mRNA expression was independent of both occlusion duration and cerebral infarction volume.

Comprehensive review on the HSC70 functions, interactions with related molecules and involvement in clinical diseases and therapeutic potential

Heat shock cognate protein 70 (HSC70) is a constitutively expressed molecular chaperone which belongs to the heat shock protein 70 (HSP70) family. HSC70 shares some of the structural and functional similarity with HSP70. HSC70 also has different properties compared with HSP70 and other heat shock family members. HSC70 performs its full functions by the cooperation of co-chaperones. It interacts with many other molecules as well and regulates various cellular functions. It is also involved in various diseases and may become a biomarker for diagnosis and potential therapeutic targets for design, discovery, and development of novel drugs to treat various diseases. In this article, we provide a comprehensive review on HSC70 from the literatures including the basic general information such as classification, structure and cellular location, genetics and function, as well as its protein association and interaction with other proteins. In addition, we also discussed the relationship of HSC70 and related clinical diseases such as cancer, cardiovascular, neurological, hepatic and many other diseases and possible therapeutic potential and highlight the progress and prospects of research in this field. Understanding the functions of HSC70 and its interaction with other molecules will help us to reveal other novel properties of this protein. Scientists may be able to utilize this protein as a biomarker and therapeutic target to make significant advancement in scientific research and clinical setting in the future.

Differentially expressed genes associated with cisplatin resistance in human ovarian adenocarcinoma cell line A2780

Ovarian cancer cells are usually initially sensitive to platinum-based chemotherapy, such as cisplatin (CDDP), but typically become resistant over time. Such drug resistance is a serious impediment to successful disease treatment, and the molecular mechanisms responsible for resistance are not fully understood. In search of novel mechanisms that may lead to the development of CDDP chemoresistance, we used subtractive hybridization to identify differentially expressed genes in CDDP resistant CP70 and C200 cells vs. CDDP sensitive A2780 human ovarian adenocarcinoma cells. We analyzed 256 randomly selected clones. Subtraction efficiency was determined by dot blot and DNA sequencing. Confirmation of differentially expressed cDNAs was done by virtual northern blot analysis, and 17 genes that were differentially expressed in CDDP resistant cell lines vs. CDDP sensitive A2780 cells were identified. The expression of 10 of these genes was low or undetectable in sensitive A2780 cells in comparison to resistant cells and an additional seven genes were more highly expressed in resistant CP70 and C200 vs. A2780 cells. Our identified genes are involved in numerous and diverse cellular processes, such as inhibition of apoptosis (ARHGDIB), stress response (HSPCA, TRA1), chromatin condensation (CNAP1, RanBP2), invasiveness of cells (MMP10), alteration of Ca(2+) homeostasis (ASPH, ATP2B1) and others. Further characterization of these genes and gene products should yield important insights into the biology of CDDP resistance in ovarian carcinoma.

Expression of HSP70 in cerebral ischemia and neuroprotetive action of hypothermia and ketoprofen

Heat shock proteins (HSPs) are molecular chaperones that bind to other proteins to shepherd them across membranes and direct them to specific locations within a cell. Several injurious stimuli can induce Hsp70 expression, including ischemia. This study aimed to investigate the pattern of expression of protein (immunohistochemistry) and gene (real-time PCR) Hsp70 in experimental focal cerebral ischemia in rats by occlusion of the middle cerebral artery for 1 hour and the role of neuroprotection with hypothermia (H) and ketoprofen (K). The infarct volume was measured using morphometric analysis defined by triphenyl tetrazolium chloride. It was observed increases in the protein (p=0.0001) and gene (p=0.0001) Hsp70 receptor in the ischemic areas that were reduced by H (protein and gene: p<0.05), K (protein: p<0.001), and H+K (protein: p<0.01 and gene: p<0.05). The Hsp70 increases in the ischemic area suggests that the Hsp70-mediated neuroexcitotoxicity plays an important role in cell death and that the neuroprotective effect of both, H and K are directly involved with the Hsp70.

Hsp70 inhibits aminoglycoside-induced hair cell death and is necessary for the protective effect of heat shock

Sensory hair cells of the inner ear are sensitive to death from aging, noise trauma, and ototoxic drugs. Ototoxic drugs include the aminoglycoside antibiotics and the antineoplastic agent cisplatin. Exposure to aminoglycosides results in hair cell death that is mediated by specific apoptotic proteins, including c-Jun N-terminal kinase (JNK) and caspases. Induction of heat shock proteins (Hsps) is a highly conserved stress response that can inhibit JNK- and caspase-dependent apoptosis in a variety of systems. We have previously shown that heat shock results in a robust upregulation of Hsps in the hair cells of the adult mouse utricle in vitro. In addition, heat shock results in significant inhibition of both cisplatin- and aminoglycoside-induced hair cell death. In our system, Hsp70 is the most strongly induced Hsp, which is upregulated over 250-fold at the level of mRNA 2 h after heat shock. Therefore, we have begun to examine the role of Hsp70 in mediating the protective effect of heat shock. To determine whether Hsp70 is necessary for the protective effect of heat shock against aminoglycoside-induced hair cell death, we utilized utricles from Hsp70.1/3 (-/-) mice. While heat shock inhibited gentamicin-induced hair cell death in wild-type utricles, utricles from Hsp70.1/3 (-/-) mice were not protected. In addition, we have examined the role of the major heat shock transcription factor, Hsf1, in mediating the protective effect of heat shock. Utricles from Hsf1 (-/-) mice and wild-type littermates were exposed to heat shock followed by gentamicin. The protective effect of heat shock on aminoglycoside-induced hair cell death was only observed in wild-type mice and not in Hsf1 (-/-) mice. To determine whether Hsp70 is sufficient to protect hair cells, we have utilized transgenic mice that constitutively overexpress Hsp70. Utricles from Hsp70-overexpressing mice and wild-type littermates were cultured in the presence of varying neomycin concentrations for 24 h. The Hsp70-overexpressing utricles were significantly protected against neomycin-induced hair cell death at moderate to high doses of neomycin. This protective effect was achieved without a heat shock. Taken together, these data indicate that Hsp70 and Hsf1 are each necessary for the protective effect of heat shock against aminoglycoside-induced death. Furthermore, overexpression of Hsp70 alone significantly inhibits aminoglycoside-induced hair cell death.

"Toxic memory" via chaperone modification is a potential mechanism for rapid Mallory-Denk body reinduction

The cytoplasmic hepatocyte inclusions, Mallory-Denk bodies (MDBs), are characteristic of several liver disorders, including alcoholic and nonalcoholic steatohepatitis. In mice, MDBs can be induced by long-term feeding with 3,5-diethoxycarbonyl-1,4-dihydrocollidine (DDC) for 3 to 4 months or rapidly reformed in DDC-induced then recovered mice by DDC refeeding or exposure to a wide range of toxins for only 5 to 7 days. The molecular basis for such a rapid reinduction of MDBs is unknown. We hypothesized that protein changes retained after DDC priming contribute to the rapid MDB reappearance and associate with MDB formation in general terms. Two-dimensional differential-in-gel-electrophoresis coupled with mass spectrometry were used to characterize protein changes in livers from the various treatment groups. The alterations were assessed by real-time reverse-transcription polymerase chain reaction and confirmed by immunoblotting. DDC treatment led to pronounced charged isoform changes in several chaperone families, including Hsp25, 60, 70, GRP58, GRP75, and GRP78, which lasted at least for 1 month after discontinuation of DDC feeding, whereas changes in other proteins normalized during recovery. DDC feeding also resulted in altered expression of Hsp72, GRP75, and Hsp25 and in functional impairment of Hsp60 and Hsp70 as determined using a protein complex formation and release assay. The priming toward rapid MDB reinduction lasts for at least 3 months after DDC discontinuation, but becomes weaker after prolonged recovery. MDB reinduction parallels the rapid increase in p62 and Hsp25 levels as well as keratin 8 cross-linking that is normally associated with MDB formation.

CONCLUSION

Persistent posttranslational modifications in chaperone proteins, coupled with protein cross-linking and altered chaperone expression and function likely contribute to the "toxic memory" of DDC-primed mice. We hypothesize that similar changes are important contributors to inclusion body formation in several diseases.

Up-regulation of hepatic heme oxygenase-1 expression by locally induced interleukin-6 in rats administered carbon tetrachloride intraperitoneally

We previously reported that interleukin-6 (IL-6) was locally produced in the early period after intraperitoneal (i.p.) or subcutaneous carbon tetrachloride (CCl4) administration, but not after oral (p.o.) administration. In the present study, we focused on the up-regulation of stress-inducible proteins induced by IL-6 after i.p. CCl4 administration. The expression of heme oxygenase-1 (HO-1) (EC 1.14.99.3) mRNA and protein were induced more in rats administered CCl4 via the i.p. route, compared with the p.o. route; however, expression of heat shock protein (HSP) 72 and HSP90 mRNA were increased to similar extents in both experimental groups. The induction of HO-1 mRNA and protein after i.p. CCl4 administration were significantly reduced after pretreatment with anti-rat IL-6 antibody. Activation of the signal transducer and activator of transcription factor 3 (STAT3), which promotes HO-1 expression, peaked together with plasma levels of IL-6 after i.p. CCl4 administration, suggesting that hepatic HO-1 expression was increased by IL-6 via the Janus kinase/STAT3 pathway. The present data indicate that hepatic HO-1 is up-regulated by endogenously produced IL-6, in addition to its up-regulation by heme derived from cytochrome P450 which has already been reported in rats administered i.p. CCl4. The up-regulation of hepatic HO-1 expression may reduce the tissue injury to livers caused by CCl4.

Mechanism of direct hepatotoxic effect of KC chemokine: sequential activation of gene expression and progression from inflammation to necrosis

This work aimed to show that an important, yet unrecognized, role of KC chemokine in the liver is regulation of gene expression. KC expression in the liver stimulated three classes of genes in this temporal order: immediate-early genes, proinflammatory genes, and profibrotic genes. Transcription factors E2F5 and early growth response 1 (EGR1), Ca(2+) signaling molecules S100A8 and S100A9, and two oxidative stress-induced genes were identified as immediate-early genes of KC. Expression of these genes was stimulated at 3-5-fold increased KC concentrations. Expression of proinflammatory genes was activated 6 h after the immediateearly genes, and they included interleukin-1alpha (IL-1alpha) and IL-1beta. KC receptor gene CXCR2 was also upregulated, suggesting that KC may act through a positive feedback loop. Stimulation of expression of profibrotic genes, including type I collagen, was seen only after the proinflammatory genes were highly expressed for 12 h. KC is a potent regulator of gene expression that proceeds in a sequential manner. Immediate-early genes of KC stimulation were identified. The positive feedback regulation and an increased oxidative stress induced by KC may explain the poor prognosis in liver patients with elevated levels of CXC chemokines.

Genomic profiling of cortical neurons following exposure to beta-amyloid

In vitro and in vivo studies have shown that beta-amyloid peptide induces neuronal cell death. To explore the molecular basis underlying beta-amyloid-induced toxicity, we analyzed gene expression profiles of cultured rat cortical neurons treated for 24 and 48 h with synthetic beta-amyloid peptide. From the 8740 genes interrogated by oligonucleotide microarray analysis, 241 genes were found to be differentially expressed and segregated into distinct clusters. Functional clustering based on gene ontologies showed coordinated expression of genes with common biological functions and metabolic pathways. The comparison with genes differentially expressed in cerebellar granule neurons following serum and potassium deprivation indicates the existence of common regulatory mechanisms underlying neuronal cell death. Our results offer a genomic view of the changes that accompany beta-amyloid-induced neurodegeneration.

Increased hepatotoxicity of acetaminophen in Hsp70i knockout mice

The effect of the inducible forms of 70 kDa heat shock protein (Hsp70i) on acetaminophen (APAP) hepatotoxicity was assessed in an Hsp70i knockout mouse model. Absence of the Hsp70i protein in liver was verified by monitoring Hsp levels in knockout and control mice after heat stress (41.5 degrees C water bath immersion for 30 min). Hsp70i knockout mice were more susceptible to APAP-induced hepatotoxicity than controls, as indicated by elevated serum alanine aminotransferase activities 24 and 48 h after the APAP dose. Increased APAP hepatotoxicity in knockout mice was verified by morphological evaluation of liver sections. The difference in toxic response to APAP between knockout and control strain mice could not be attributed to differences in APAP bioactivation, assessed by measurement of CYP2E1 and glutathione S-transferase activities, hepatic nonprotein sulfhydryl content, or covalent binding of reactive APAP metabolites to proteins. Pretreatment with transient hyperthermia to produce a general upregulation of Hsps resulted in decreased APAP hepatotoxicity in both the knockout and control strains. Among thermally-pretreated mice, hepatotoxicity of APAP was greater in the knockouts compared with the control strain. These observations suggest that increased Hsp70i expression in response to APAP acts to limit the extent of tissue injury. Results further suggest that other factors related to heat stress can also contribute to protection against APAP toxicity.

Dynamic gene expression changes precede dioxin-induced liver pathogenesis in medaka fish

A major challenge for environmental genomics is linking gene expression to cellular toxicity and morphological alteration. Herein, we address complexities related to hepatic gene expression responses after a single injection of the aryl hydrocarbon receptor (AHR) agonist 2,3,7,8-tetrachlorodibenzo-p-dioxin (dioxin) and illustrate an initial stress response followed by cytologic and adaptive changes in the teleost fish medaka. Using a custom 175-gene array, we find that overall hepatic gene expression and histological changes are strongly dependent on dose and time. The most pronounced dioxin-induced gene expression changes occurred early and preceded morphologic alteration in the liver. Following a systematic search for putative Ah response elements (AHREs) (5'-CACGCA-3') within 2000 bp upstream of the predicted transcriptional start site, the majority (87%) of genes screened in this study did not contain an AHRE, suggesting that gene expression was not solely dependent on AHRE-mediated transcription. Moreover, in the highest dosage, we observed gene expression changes associated with adaptation that persisted for almost two weeks, including induction of a gene putatively identified as ependymin that may function in hepatic injury repair. These data suggest that the cellular response to dioxin involves both AHRE- and non-AHRE-mediated transcription, and that coupling gene expression profiling with analysis of morphologic pathogenesis is essential for establishing temporal relationships between transcriptional changes, toxicity, and adaptation to hepatic injury.

Swelling of hepatocytes injured by oxidative stress suggests pathological changes related to macromolecular crowding

A fundamental property of living matter is the ability to establish and maintain order. Mild changes in cell volume have a role in metabolic control. Furthermore, cellular swelling is a way of living cells to react to a variety of stressors. Data from experimental pathology, biochemistry and biophysics and theoretical arguments from biology, biochemical evolution, cytology and biophysics are considered to attempt an integration of several current concepts on different subjects (intracellular compartmentation, cellular swelling, macromolecular crowding, perturbing and non-perturbing solutes). The purpose is to provide a framework for conceptualizing in modern terms the question whether cellular swelling induced by oxidative stress should be considered merely a cell adaptation balanced by antioxidant defenses and by other biochemical devices apt to preserve the intracellular environment and normal cell functioning, or whether swelling of high amplitude should be regarded as a true pathological change. The basic question dated 1982: "how crowded is the cytoplasm?" is a matter for discussion as far as swollen cells are concerned. This paper examines the liver for cellular swelling of high amplitude (about+30%) caused by iron or by thyroid hormone+iron (histological picture of "cloudy swelling") or the steatogenic poison CCl(4), also known as a source of oxyradicals, which causes an even more pronounced cellular swelling. In CCl(4)-toxic fatty liver the strong increase of tissue water is substantially masked by the parallel increase of tissue dry solids due to fat accumulation. This example of a "tissue dilution artefact" is discussed in connection with the increase of tissue water also in toxic fatty liver induced by white phosphorus and ethanol. In CCl(4)-toxic fatty liver the normal K(+)/Na(+) ratio (about 3) is substantially maintained, whereas the concentrations of the two cations ("perturbing osmolytes") in tissue water are noticeably decreased, a finding which was not further studied at the time the observations were made because biochemistry was not yet advanced enough to allow an explanation. Today, a logic hypothesis is that an increase of non-perturbing solutes such as taurine and betaine, maintains the physiological intracellular osmotic pressure and that the harmful effects of CCl(4) are limited because of the protective effects of these molecules and of molecular chaperones against damage by oxyradicals. However, as a consequence of cellular swelling, intracellular changes in ionic strength and macromolecular crowding should occur thus affecting enzyme activities. Models and techniques apt to investigate this problem experimentally are suggested.

Differential signatures of protein expression in marmoset liver and thymus induced by single-dose TCDD treatment

2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) is an ubiquitously distributed environmental pollutant. Health effects have been studied intensively, but low-dose effects are quite complex and not yet fully understood. In many studies, the immune system was identified as the most sensitive target. Here, we demonstrate changes of protein expression in liver and thymus of male marmosets (Callithrix jacchus) which were subjected to a single dose of a subcutaneous injection of 100 ng/kg body weight TCDD. Histopathological examination revealed myocardial fibrosis, but there were no significant findings in pathology and histopathology of liver and thymus. In order to detect more subtle treatment-related changes, we performed a comparative proteomic investigation of liver and thymus using a 2-D gel electrophoresis based proteomics approach. Fluorescence labeling and automated image analysis was used to enhance sensitivity and reproducibility. In both organs, distinct changes of protein expression were detected which were more pronounced in thymus, where the pattern of deregulated proteins could be clearly related to immune responses. In the thymus of treated animals, several toxicologically relevant factors were increased, including chaperones, glycerol-3-phosphate dehydrogenase, and adseverin. Among others, vimentin, Ca-dependent protease and protein disulfide isomerase were downregulated. In the liver, transferrins, lamin A and HSP70 were upregulated, whereas thymidine phosphorylase (synonyms: endothelial cell growth factor, PD-ECGF, gliostatin) was significantly reduced. Comparative analysis of deregulated proteins in both organs revealed a pattern of related functions, which fits well into the existing knowledge of the toxic processes and mechanisms underlying TCDD-mediated toxicity.