Overexpression of metallothionein-II sensitizes rodent cells to apoptosis induced by DNA cross-linking agent through inhibition of NF-kappa B activation

Long-term Hyperandrogenemia and/or Western-style Diet in Rhesus Macaque Females Impairs Preimplantation Embryogenesis

Hyperandrogenemia and obesity are common in women with polycystic ovary syndrome, but it is currently unclear how each alone or in combination contribute to reproductive dysfunction and female infertility. To distinguish the individual and combined effects of hyperandrogenemia and an obesogenic diet on ovarian function, prepubertal female rhesus macaques received a standard control (C) diet, testosterone (T) implants, an obesogenic Western-style diet (WSD), or both (T + WSD). After 5 to 6 years of treatment, the females underwent metabolic assessments and controlled ovarian stimulations. Follicular fluid (FF) was collected for steroid and cytokine analysis and the oocytes fertilized in vitro. Although the T + WSD females exhibited higher insulin resistance compared to the controls, there were no significant differences in metabolic parameters between treatments. Significantly higher concentrations of CXCL-10 were detected in the FF from the T group, but no significant differences in intrafollicular steroid levels were observed. Immunostaining of cleavage-stage embryos revealed multiple nuclear abnormalities in the T, WSD, and T + WSD groups. Single-cell DNA sequencing showed that while C embryos contained primarily euploid blastomeres, most cells in the other treatment groups were aneuploid. Despite yielding a higher number of mature oocytes, T + WSD treatment resulted in significantly reduced blastocyst formation rates compared to the T group. RNA sequencing analysis of individual blastocysts showed differential expression of genes involved in critical implantation processes between the C group and other treatments. Collectively, we show that long-term WSD consumption reduces the capacity of fertilized oocytes to develop into blastocysts and that the addition of T further impacts gene expression and embryogenesis.

Proprotein convertases blockage up-regulates specifically metallothioneins coding genes in human colon cancer stem cells

Despite continuous exertion made, colon cancer still represents a major health problem and its incidence continues being high worldwide. There is growing evidence in support of the cancer stem cells (CSCs) being central in the initiation of this cancer, and CSCs have been the focus of various studies for the identification of new ways of treatment. Lately, the proprotein convertases (PCs) were reported to regulate the maturation and expression of various molecules involved in the malignant phenotype of colon cancer cells, however, the identity of the molecules regulated by these serine proteases in CSCs is unknown. In this study, we used the general PCs inhibitor, the Decanoyl-RVKR-chloromethylketone (Decanoyl-RVKR-CMK) that inhibits all the PCs found in the secretory pathway, and analyzed its effect on CSCs using RNA-seq analysis. Remarkably, from the only 9 up-regulated genes in the human SW620-derived sphere-forming cells, we identified 7 of the 11 human metallothioneins, all of them localized on chromosome 16, and zinc related proteins as downstream effectors of the PCs. The importance of these molecules in the regulation of cell proliferation, differentiation and chemoresistance, and their reported potential tumor suppressor role and loss in colon cancer patients associated with worse prognosis, suggests that targeting PCs in the control of the malignant phenotype of CSCs is a new potential therapeutic strategy in colon cancer.

A systems toxicology approach to compare the heavy metal mixtures (Pb, As, MeHg) impact in neurodegenerative diseases

Conventional toxicological risk assessment methods mainly working on single chemicals that fail to adequately address the simultaneous exposure and their potential toxicity in humans. We herein investigated the toxic heavy metals lead (Pb), arsenic (As), and methylmercury (MeHg) and their binary mixtures role in neurodegenerative diseases. To characterize the toxicity of metal mixtures at the molecular level, we established a non-animal omics-based organ relevant cell model system. The obtained experimental data was refined by using the statistical and downstream functional analysis. The protein expression information substantiates the previous findings of single metal (Pb, As, and MeHg) induced alterations to mitochondrial dysfunction, oxidative stress, mRNA splicing, and ubiquitin system dysfunction relation to neurodegenerative diseases. The functional downstream analysis of single and binary mixtures protein data is presented in a comparative manner. The heavy metals mixtures' outcome showed significant differences in the protein expression compared to single metals that indicate metal mixtures exposure is more hazardous than single metal exposure. These results suggest that more comprehensive strategies are needed to improve the mixtures risk assessment in the future.

Elemental Zn and its Binding Protein Zinc-α2-Glycoprotein are Elevated in HPV-Positive Oropharyngeal Squamous Cell Carcinoma

Human papillomavirus (HPV)-positive head and neck squamous cell carcinoma (HNSCC) is biologically distinct from HPV-negative HNSCC. Outside of HPV-status, few tumor-intrinsic variables have been identified that correlate to improved survival. As part of exploratory analysis into the trace elemental composition of oropharyngeal squamous cell carcinoma (OPSCC), we performed elemental quanitification by X-ray fluorescence microscopy (XFM) on a small cohort (n = 32) of patients with HPV-positive and -negative OPSCC and identified in HPV-positive cases increased zinc (Zn) concentrations in tumor tissue relative to normal tissue. Subsequent immunohistochemistry of six Zn-binding proteins—zinc-α2-glycoprotein (AZGP1), Lipocalin-1, Albumin, S100A7, S100A8 and S100A9—revealed that only AZGP1 expression significantly correlated to HPV-status (p < 0.001) and was also increased in tumor relative to normal tissue from HPV-positive OPSCC tumor samples. AZGP1 protein expression in our cohort significantly correlated to a prolonged recurrence-free survival (p = 0.029), similar to HNSCC cases from the TCGA (n = 499), where highest AZGP1 mRNA levels correlated to improved overall survival (p = 0.023). By showing for the first time that HPV-positive OPSCC patients have increased intratumoral Zn levels and AZGP1 expression, we identify possible positive prognostic biomarkers in HNSCC as well as possible mechanisms of increased sensitivity to chemoradiation in HPV-positive OPSCC.

Synergistic cellular responses to heavy metal exposure: A minireview

BACKGROUND

Metal-responsive transcription factor 1 (MTF-1) induces the expression of metallothioneins (MTs) which bind and sequester labile metal ions. While MTF-1 primarily responds to excess metal exposure, additional stress response mechanisms are activated by excess metals. Evidence suggests potential crosstalk between responses mediated by MTF-1 and stress signaling enhances cellular tolerance to metal exposure.

SCOPE OF REVIEW

This review aims to summarize the current understanding of interaction between the stress response mediated by MTF-1 and other cellular mechanisms, notably the nuclear factor κB (NF-κB) and heat shock response (HSR).

MAJOR CONCLUSIONS

Crosstalk between MTF-1 mediated metal response and NF-κB signaling or HSR can modulate expression of stress proteins in response to metal exposure via effects on precursor signals or direct interaction of transcriptional activators. The interaction between stress signaling pathways can enhance cell survival and tolerance through a unified response system.

GENERAL SIGNIFICANCE

Elucidating the interactions between MTF-1 and cell stress response mechanisms is critical to a comprehensive understanding of metal-based cellular effects. Co-activation of HSR and NF-κB signaling allows the cell to detect metal contamination in the environment and improve survival outcomes.

Reappraisal of metallothionein: Clinical implications for patients with diabetes mellitus

Reactive oxygen and nitrogen species (ROS and RNS, respectively) are byproducts of cellular physiological processes of the metabolism of intermediary nutrients. Although physiological defense mechanisms readily convert these species into water or urea, an improper balance between their production and removal leads to oxidative stress (OS), which is harmful to cellular components. This OS may result in uncontrolled growth or, ultimately, cell death. In addition, ROS and RNS are closely related to the development of diabetes and its complications. Therefore, numerous researchers have proposed the development of strategies for the removal of ROS/RNS to prevent or treat diabetes and its complications. Some molecules that are synthesized in the body or obtained from food participate in the removal and neutralization of ROS and RNS. Metallothionein, a cysteine-rich protein, is a metal-binding protein that has a wide range of functions in cellular homeostasis and immunity. Metallothionein can be induced by a variety of conditions, including zinc supplementation, and plays a crucial role in mediating anti-OS, anti-apoptotic, detoxification, and anti-inflammatory effects. Metallothionein can modulate various stress-induced signaling pathways (mitogen-activated protein kinase, Wnt, nuclear factor-κB, phosphatidylinositol 3-kinase, sirtuin 1/AMP-activated protein kinase and fibroblast growth factor 21) to alleviate diabetes and diabetic complications. However, a deeper understanding of the functional, biochemical, and molecular characteristics of metallothionein is needed to bring about new opportunities for OS therapy. This review focuses on newly proposed functions of a metallothionein and their implications relevant to diabetes and its complications.

Epigenetic Upregulation of Metallothionein 2A by Diallyl Trisulfide Enhances Chemosensitivity of Human Gastric Cancer Cells to Docetaxel Through Attenuating NF-κB Activation

AIMS

Metallothionein 2A (MT2A) and nuclear factor-kappaB (NF-κB) are both involved in carcinogenesis and cancer chemosensitivity. We previously showed decreased expression of MT2A and IκB-α in human gastric cancer (GC) associated with poor prognosis of GC patients. The present study investigated the effect of diallyl trisulfide (DATS), a garlic-derived compound, and docetaxel (DOC) on regulation of MT2A in relation to NF-κB in GC cells.

RESULTS

DATS attenuated NF-κB signaling in GC cells, resulting in G2/M cell cycle arrest and apoptosis, culminating in the inhibition of cell proliferation and tumorigenesis in nude mice. The anti-GC effect of DATS was attributable to its capacity to epigenetically upregulate MT2A, which in turn enhanced transcription of IκB-α to suppress NF-κB activation in GC cells. The combination of DATS with DOC exhibited a synergistic anti-GC activity accompanied by MT2A upregulation and NF-κB inactivation. Histopathologic analysis of GC specimens from patients showed a significant increase in MT2A expression following DOC treatment. GC patients with high MT2A expression in tumor specimens showed significantly improved response to chemotherapy and prolonged survival compared with those with low MT2A expression in tumors.

INNOVATION AND CONCLUSION

We conclude that DATS exerts its anti-GC activity and enhances chemosensitivity of GC to DOC by epigenetic upregulation of MT2A to attenuate NF-κB signaling. Our findings delineate a mechanistic basis of MT2A/NF-κB signaling for DATS- and DOC-mediated anti-GC effects, suggesting that MT2A may be a chemosensitivity indicator in GC patients receiving DOC-based treatment and a promising target for more effective treatment of GC by combination of DATS and DOC. Antioxid. Redox Signal. 24, 839-854.

Metallothionein 1G and zinc sensitize human colorectal cancer cells to chemotherapy

Metallothioneins (MT) are a family of low molecular weight proteins that are silenced during colorectal cancer progression, mainly through epigenetic mechanisms, and this loss is associated with poor survival. In this article, we show that overexpression of the MT1G isoform sensitizes colorectal cell lines to the chemotherapeutic agents oxaliplatin (OXA) and 5-fluorouracil (5-FU), in part through enhancing p53 and repressing NF-κB activity. Despite being silenced, MTs can be reinduced by histone deacetylase inhibitors such as trichostatin A and sodium butyrate. In fact, this induction contributes to the cytotoxicity of these agents, given that silencing of MTs by siRNAs reduces their growth-inhibitory activities. Zinc ions also potently enhance MT expression and are cytotoxic to cancer cells. We show for the first time that OXA and 5-FU induce higher levels of intracellular labile zinc, as measured using the fluorescent probe FLUOZIN-3, and that such zinc contributes to the activation of p53 and repression of NF-κB. Addition of zinc enhanced growth inhibition by OXA and 5-FU, and was also capable of resensitizing 5-FU-resistant cell lines to levels comparable with sensitive cell lines. This effect was MT independent because silencing MTs did not affect zinc cytotoxicity. In conclusion, we show that MT induction and zinc administration are novel strategies to sensitize colorectal cancer cells to presently utilized chemotherapeutic agents.

Metallothioneins and zinc in cancer diagnosis and therapy

Metallothioneins (MTs) are involved in protection against oxidative stress (OS) and toxic metals and they participate in zinc metabolism and its homeostasis. Disturbing of zinc homeostasis can lead to formation of reactive oxygen species, which can result in OS causing alterations in immunity, aging, and civilization diseases, but also in cancer development. It is not surprising that altered zinc metabolism and expression of MTs are of great interest in the case of studying of oncogenesis and cancer prognosis. The role of MTs and zinc in cancer development is tightly connected, and the structure and function of MTs are strongly dependent on Zn²⁺ redox state and its binding to proteins. Antiapoptic effects of MTs and their interactions with proteins nuclear factor kappa B, protein kinase C, esophageal cancer-related gene, and p53 as well as the role of MTs in their proliferation, immunomodulation, enzyme activation, and interaction with nitric oxide are reviewed. Utilization of MTs in cancer diagnosis and therapy is summarized and their importance for chemoresistance is also mentioned.

Impaired synthesis of erythropoietin, glutamine synthetase and metallothionein in the skin of NOD/SCID/gamma(c)(null) and Foxn1 nu/nu mice with misbalanced production of MHC class II complex

Most skin pathologies are characterized by unbalanced synthesis of major histocompatability complex II (MHC-II) proteins. Healthy skin keratinocytes simultaneously produce large amounts of MHC-II and regeneration-supporting proteins, e.g. erythropoietin (EPO), EPO receptor (EPOR), glutamine synthetase (GS) and metallothionein (MT). To investigate the level of regeneration-supporting proteins in the skin during misbalanced production of MHC-II, skin sections from nonobese diabetic/severe combined immunodeficient (NOD/SCID)/gamma (c) (null) and or Foxn1 nu/nu mice which are a priory known to under- and over-express MHC II, respectively, were used. Double immunofluorescence analysis of NOD/SCID/gamma (c) (null) skin sections showed striking decrease in expression of MHC-II, EPO, GS and MT. In Foxn1 nu/nu mouse skin, GS was strongly expressed in epidermis and in hair follicles (HF), which lacked EPO. In nude mouse skin EPO and MHC-II were over-expressed in dermal fibroblasts and they were completely absent from cortex, channel, medulla and keratinocytes surrounding the HF, suggest a role for EPO in health and pathology of hair follicle. The level of expression of EPO and GS in both mutant mice was confirmed by results of Western blot analyses. Strong immunoresponsiveness of EPOR in the hair channels of NOD/SCID/gamma (c) (null) mouse skin suggests increased requirements of skin cells for EPO and possible benefits of exogenous EPO application during disorders of immune system accompanied by loss MHC-II in skin cells.

Metallothionein-III provides neuronal protection through activation of nuclear factor-kappaB via the TrkA/phosphatidylinositol-3 kinase/Akt signaling pathway

Metallothionein (MT)-III is associated with resistance to neuronal injury. However, the underlying mechanism for its effects is unclear. The present study investigated the mechanisms of MT-III protection of neuronal cells from hypoxia or DNA damage-induced cell death. MT-III reduced the hydrogen peroxide- or DNA damage-induced effects on neuronal cells, including the cell death, the activation of caspase-3 and -9, and the release of mitochondrial cytochrome c to the cytoplasm in a dose-dependent manner. MT-III also increased the activation of Akt, the phosphorylation and degradation of IkappaB, the nuclear translocation/accumulation and the transcriptional activity of nuclear factor-kappaB (NF-kappaB) in neuronal cells in a dose-dependent manner. The MT-III-induced antiapoptotic effects and increase in NF-kappaB activity were blocked by specific inhibitors of TrkA, phosphatidylinositol-3 kinase (PI3K), Akt, or NF-kappaB, indicating that MT-III provides neuronal protection by activating NF-kappaB through the TrkA/PI3K/Akt signaling pathway.

Metal binding and antioxidant properties of chimeric tri- and tetra-domained metallothioneins

An unusual tri-domained (alpha-beta-beta) natural oyster metallothionein (MT) is known, and non-oxidative MT dimers occur in vivo in mollusk species and in mammals. To assess the respective role of the MT domains, two chimeric MTs were constructed: a tetra-domained oyster MT corresponding to the alpha-beta-alpha-beta structure, in order to mimic the natural non-oxidative dimeric form, and a tri-domained alpha-beta-alpha oyster MT. Metal binding and putative antioxidant properties of these two chimeric MTs were investigated using expression of the related genes in the bacteria Escherichia coli. In a wild-type strain these MTs could efficiently bind Cd. In a superoxide dismutase (sodA sodB) null mutant, the tri-domained MT was found to exacerbate Cd toxicity whereas the tetra-domained MT efficiently protected bacteria from Cd. The paradoxical toxicity displayed by the tri-domained MT upon Cd contamination was linked to the generation of superoxide radicals generated by a mechanism which most probably involves a copper-redox cycling reaction, since a Cd-contaminated sodA sodB strain expressing this MT produced 4 times more O2(-) than the control bacteria, and MT toxicity disappeared in the presence of bathocuproine disulfonic acid, a copper chelator. In contrast, the tetra-domained form did not. Interestingly, in bacteria producing superoxide dismutase but hypersensitive to oxidative stress due to either mutations in thioredoxin and glutathione reductase pathways (WM104 mutant) or to a lack of gamma-glutamylcysteine synthetase (gshA mutant), both chimeric MTs were protecting against Cd toxicity. However, an unexpected lack of antioxidant function was observed for both chimeric MTs, which were found to enhance the toxicity of hydrogen peroxide in WM104, or that of menadione in QC1726. Altogether, our results suggest that superoxide dismutase activity counteracts the potential prooxidative effect of the tri-domained MT mediated by Cu ions and that the tetra-domained form is a very efficient protector against metal toxicity in vivo.

Role of metallothioneins in superoxide radical generation during copper redox cycling: Defining the fundamental function of metallothioneins

In order to demonstrate the in vivo antioxidant properties of metallothioneins (MTs), the bacteria Escherichia coli was used as a cell reactor in which we compared the metal binding and antioxidative functions of MTs from different species, with different structures and polypeptide lengths. No protective effects of cytoplasmic MTs from cadmium (Cd) or zinc (Zn) contamination were observed in a wild-type E. coli strain, although these MTs can efficiently bind both Cd and Zn. To test their antioxidant properties, MTs were expressed within the cytoplasm of a sodA sodB deficient mutated strain (QC1726). However, a paradoxical MT toxicity was found when this strain was contaminated with Cd and Zn, suggesting that in a wild-type strain, superoxide dismutase counteracts MT toxicity. The most toxic MT was the one with the strongest Cd and Zn binding capacities. This toxic effect was linked to the generation of superoxide radicals, since a Cd-contaminated QC1726 strain expressing oyster MT isoforms produced 75-85% more O(2)*(-) than the control QC1726 strain. Conversely, under anaerobiosis or in the presence of a copper chelator, MTs protected QC1726 strain from Cd and Zn contamination. A model is proposed to explain the observed MT toxicity.

Metallothionein and catalase sensitize to diabetes in nonobese diabetic mice: reactive oxygen species may have a protective role in pancreatic beta-cells

It is widely proposed that reactive oxygen species (ROS) contribute to beta-cell death in type 1 diabetes. We tested this in nonobese diabetic (NOD) mice using beta-cell-specific overexpression of three antioxidant proteins: metallothionein (MT), catalase (Cat), or manganese superoxide dismutase (MnSOD). Unexpectedly, the cytoplasmic antioxidants, MT and catalase, greatly accelerated diabetes after cyclophosphamide and accelerated spontaneous diabetes in male NOD mice. This occurred despite the fact that they reduced cytokine-induced ROS production and MT reduced streptozotocin diabetes in NOD mice. Accelerated diabetes onset coincided with increased beta-cell death but not with increased immune attack. Islets from MTNOD mice were more sensitive to cytokine injury. In vivo and in vitro studies indicated reduced activation of the Akt/pancreatic duodenal homeobox-1 survival pathway in MTNOD and CatNOD islets. Our study indicates that cytoplasmic ROS may have an important role for protecting the beta-cell from autoimmune destruction.

Metallothionein as an adaptive protein prevents diabetes and its toxicity

Metallothioneins (MTs) are a group of intracellular metal-binding and cysteine-enriched proteins and are highly inducible in many tissues in response to various types of stress. Although it mainly acts as a regulator of metal homeostasis such as zinc and copper in tissues, MT also acts as a potent antioxidant and adaptive (or stress) protein to protect cells and tissues from oxidative stress. Diabetes affects many Americans and other populations, and its development and toxic effect on various organs have been attributed to increased oxidative stress. Studies showed that zinc-induced or genetically enhanced pancreatic MT synthesis prevented diabetes induced by chemicals such as streptozotocin and alloxan, and zinc pretreatment also prevented spontaneously developed diabetes. Since diabetic complications are the consequences of organ damage caused by diabetic hyperglycemia and hyperlipidemia through oxidative stress, whether MT in nonpancreatic organs also provides a preventive effect on diabetic toxicity has been recently investigated. We demonstrated that overexpression of cardiac MT significantly prevented diabetes-induced cardiomyopathy. Likewise, overexpression of renal MT also prevented diabetes-induced renal toxicity. In addition, we also found that MT as an adaptive protein is overexpressed in several organs in response to diabetes. Therefore, the biological importance of diabetes-induced MT in diabetic complications and subsequent other pathogenesis was further explored. We found that diabetes-induced hepatic and renal MT synthesis was accompanied by a significant prevention of endotoxin-induced hepatic toxicity and cisplatin-induced renal toxicity. These studies suggest that MT as an adaptive protein can prevent both diabetes development and its complications or subsequent suffered other pathogenic injury.

Metallothionein mediates the level and activity of nuclear factor kappa B in murine fibroblasts

The zinc-binding protein metallothionein (MT) is associated with resistance to apoptosis. We examined whether MT regulates the zinc-dependent antiapoptotic transcription factor nuclear factor KappaB (NF-KappaB), which is up-regulated under many conditions that lead to elevated MT expression. NF-KappaB protein levels and NF-KappaB-dependent reporter gene activity were examined in clonal MT(+) (MT-WT) and MT(-) (MT-KO) fibroblastic cell lines. The amount of cellular NF-KappaB p65 protein in MT-KO was less than 20% of the amount in MT-WT cells, in accord with increased sensitivity of MT-KO cells to apoptosis. NF-KappaB p65 mRNA levels, and NF-KappaB p50 subunit and IKappaBalpha protein levels, were unchanged. NF-KappaB activity assessed by expression of a transfected NF-KappaB reporter construct was less than half that observed in MT-KO cells. Decreased nuclear localization of NF-KappaB p65 in MT-KO clones was not responsible for differences in activity. In fact, MT-KO cells had higher nuclear levels of NF-KappaB p65 than did MT-WT cells, despite a lower cellular NF-KappaB level and function, suggesting that metallothionein mediated the specific activity of NF-KappaB. Reconstitution of MT by stable incorporation of an MT-1 expression vector in MT-KO cells resulted in increased NF-KappaB p65 (but not IKappaBalpha or NF-KappaB p50), increased NF-KappaB-dependent reporter activity, and increased resistance to apoptosis. These data support the hypothesis that metallothionein positively regulates the cellular level and activity of NF-KappaB.

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Zinc-induced NF-kappaB inhibition can be modulated by changes in the intracellular metallothionein level

Metallothionein (MT), a small metal-binding protein, is involved in the regulation of cellular metal homeostasis. Sequestration and the release of metals to and from MT plays an important role in the attenuation or amplification of signal transduction. Zinc has been suggested to be an important regulator of nuclear factor kappaB (NF-kappaB). In this study, the effect of MT expression on the zinc-induced inhibition of NF-kappaB activity was examined. In HeLa cells, pyrrolidine dithiocarbamate (PDTC), a zinc ionophore, and zinc itself inhibited NF-kappaB activity. When the cells were pretreated with MT-inducers, cadmium, or dexamethasone, PDTC did not inhibit NF-kappaB activity. We transfected HeLa cells with a DNA construct in which expression of MT-IIA is controlled by tet operator protein. Treatment of HeLa cells with doxycycline, a tetracycline analogue, induced the expression of MT-IIA, which attenuated the effect of PDTC on NF-kappaB activity. These results implicate MT in the zinc regulation of NF-kappaB and identify MT as one of the potential intracellular modulators of NF-kappaB activation.

Hepatic metallothionein in patients with chronic hepatitis C: relationship with severity of liver disease and response to treatment

OBJECTIVES

Reactive oxygen species may be involved in the pathogenesis of chronic hepatitis C virus infection. Metallothionein (MT) is an essential protein for the protection of cells against reactive oxygen species. The aim of this prospective study was to assess the influence of the hepatic level and cellular distribution of MT in hepatitis C virus (HCV) infection and in the liver disease outcome.

METHODS

In liver biopsy samples of 32 patients with chronic HCV infection and of 12 control subjects, quantification of MT was performed by radioimmunoassay, MT, interleukin (IL)-1 and -6, and tumor necrosis factor (INF)-alpha mRNA by reverse transcription-polymerase chain reaction (PCR) and cellular distribution by immunohistochemistry.

RESULTS

In HCV-infected patients, MT liver protein level was 3-fold lower than in control specimens. A significant inverse linear regression between MT protein or mRNA expression and the Histological Activity Index, the necroinflammatory grade, and the stage of fibrosis was observed. MT immunostaining was located in the nucleus and cytoplasm in hepatocytes of control subjects, whereas it was mainly cytoplasmic in HCV-infected patients. Before interferon (IFN) therapy, the hepatic MT level in patients that were nonsustained responders was half that of sustained responders. Intrahepatic IL-6 and MT were simultaneously down-regulated, but no correlation was found between MT and intrahepatic cytokine mRNA expression in patients with chronic HCV infection.

CONCLUSIONS

This study shows that hepatic MT expression could reflect the severity of chronic HCV infection and could be one of the factors associated with a favorable clinical outcome in the response to interferon therapy.

Shaping gene expression in activated and resting primary macrophages by IL-10

IL-10 regulates inflammation by reducing cytokine and chemokine production from activated macrophages. We performed microarray experiments to identify possible effector molecules of IL-10 and to investigate the global effect of IL-10 on the transcriptional response induced in LPS-activated macrophages. To exclude background effects of endogenous IL-10, macrophages from IL-10-deficient mice were used. IL-10 up-regulated expression of a small number of genes (26 and 37 after 45 min and 3 h, respectively), including newly identified and previously documented targets such as suppressor of cytokine signaling-3 and IL-1 receptor antagonist. However, the activation program triggered by LPS was profoundly affected by IL-10. IL-10 repressed 62 and further increased 15 of 259 LPS-induced genes. For all genes examined, the effects of IL-10 were determined to be STAT3-dependent. These results suggest that IL-10 regulates STAT3-dependent pathways that selectively target a broad component of LPS-induced genes at the mRNA level.