Metallothionein synthesis induced by interferon alpha/beta in mice of various zinc status

The soluble CD83 protein prevents bone destruction by inhibiting the formation of osteoclasts and inducing resolution of inflammation in arthritis

Here we show that soluble CD83 induces the resolution of inflammation in an antigen-induced arthritis (AIA) model. Joint swelling and the arthritis-related expression levels of IL-1β, IL-6, RANKL, MMP9, and OC-Stamp were strongly reduced, while Foxp3 was induced. In addition, we observed a significant inhibition of TRAP⁺ osteoclast formation, correlating with the reduced arthritic disease score. In contrast, cell-specific deletion of CD83 in human and murine precursor cells resulted in an enhanced formation of mature osteoclasts. RNA sequencing analyses, comparing sCD83- with mock treated cells, revealed a strong downregulation of osteoclastogenic factors, such as Oc-Stamp, Mmp9 and Nfatc1, Ctsk, and Trap. Concomitantly, transcripts typical for pro-resolving macrophages, e.g., Mrc1/2, Marco, Klf4, and Mertk, were upregulated. Interestingly, members of the metallothionein (MT) family, which have been associated with a reduced arthritic disease severity, were also highly induced by sCD83 in samples derived from RA patients. Finally, we elucidated the sCD83-induced signaling cascade downstream to its binding to the Toll-like receptor 4/(TLR4/MD2) receptor complex using CRISPR/Cas9-induced knockdowns of TLR4/MyD88/TRIF and MTs, revealing that sCD83 acts via the TRIF-signaling cascade. In conclusion, sCD83 represents a promising therapeutic approach to induce the resolution of inflammation and to prevent bone erosion in autoimmune arthritis.

Type I Interferons Ameliorate Zinc Intoxication of Candida glabrata by Macrophages and Promote Fungal Immune Evasion

Host and fungal pathogens compete for metal ion acquisition during infectious processes, but molecular mechanisms remain largely unknown. Here, we show that type I interferons (IFNs-I) dysregulate zinc homeostasis in macrophages, which employ metallothionein-mediated zinc intoxication of pathogens as fungicidal response. However, Candida glabrata can escape immune surveillance by sequestering zinc into vacuoles. Interestingly, zinc-loading is inhibited by IFNs-I, because a Janus kinase 1 (JAK1)-dependent suppression of zinc homeostasis affects zinc distribution in macrophages as well as generation of reactive oxygen species (ROS). In addition, systemic fungal infections elicit IFN-I responses that suppress splenic zinc homeostasis, thereby altering macrophage zinc pools that otherwise exert fungicidal actions. Thus, IFN-I signaling inadvertently increases fungal fitness both in vitro and in vivo during fungal infections. Our data reveal an as yet unrecognized role for zinc intoxication in antifungal immunity and suggest that interfering with host zinc homeostasis may offer therapeutic options to treat invasive fungal infections.

Zinc is a potent and specific inhibitor of IFN-λ3 signalling

Lambda interferons (IFNL, IFN-λ) are pro-inflammatory cytokines important in acute and chronic viral infection. Single-nucleotide polymorphisms rs12979860 and rs8099917 within the IFNL gene locus predict hepatitis C virus (HCV) clearance, as well as inflammation and fibrosis progression in viral and non-viral liver disease. The underlying mechanism, however, is not defined. Here we show that the rs12979860 CC genotype correlates with increased hepatic metallothionein expression through increased systemic zinc levels. Zinc interferes with IFN-λ3 binding to IFNL receptor 1 (IFNLR1), resulting in decreased antiviral activity and increased viral replication (HCV, influenza) in vitro. HCV patients with high zinc levels have low hepatocyte antiviral and inflammatory gene expression and high viral loads, confirming the inhibitory role of zinc in vivo. We provide the first evidence that zinc can act as a potent and specific inhibitor of IFN-λ3 signalling and highlight its potential as a target of therapeutic intervention for IFN-λ3-mediated chronic disease.

Determination of the serum metallothionein (MT)1/2 concentration in patients with Wilson's disease and Menkes disease

We have developed an easy and specific enzyme-linked immunoassay (ELISA) for the simultaneous determination of serum metallothinein-1 (MT-1) and 2 (MT-2) in both humans and experimental animals. A competitive ELISA was established using a specific polyclonal antibody against rat MT-2. The antibody used for this ELISA had exhibited the same cross-reactivity with MT in humans and experimental animals. The NH2 terminal peptide of MT containing acetylated methionine was shown to be the epitope of this antibody. The reactivity of this ELISA system with the liver, kidney and brain in MT1/2 knock-out mice was significantly low, but was normal in an MT-3 knock-out mouse. The lowest detection limit of this ELISA was 0.6ng/ml and the spiked MT-1was fully recovered from the plasma. We investigated the normal range of MT1/2 (25-75%tile) in 200 healthy human serum and found it to be 27-48ng/ml, and this was compared with the serum levels in various liver diseases. The serum MT1/2 levels in chronic hepatitis C (HCV) patients were significantly lower than healthy controls and also other liver diseases. In the chronic hepatitis cases, the MT1/I2 levels increased gradually, followed by the progression of the disease to liver cirrhosis and hepatocellular carcinoma. In particular, we found significantly elevated MT1/2 plasma levels in Wilson's disease patients, levels which were very similar to those in the Long-Evans Cinnamon (LEC) rat (model animal of Wilson's disease). Furthermore, a significantly elevated MT1/2 level was found in patients with Menkes disease, an inborn error of copper metabolism such as Wilson's disease.

Production of late IFN-α induced by plasma γ-globulin fraction proteins and their metal complexes

Plasma γ-globulin fraction proteins, copper and zinc cations, and metal complexes they form with human serum γ-globulin induce the production of IFN-α by human blood cells throughout the periods of up to 72 h. Zinc cation-modified protein by 1.6 times (p<0.05) more actively induces late IFN-α than the control γ-globulin; γ-globulin-copper metal complex is 2-fold (p<0.002) more effective than the control protein. The results indicate that functional relationships between the components inducing the production of late IFN-α differ from the effects realized during the early period of induction.

The two faces of metallothionein in carcinogenesis: photoprotection against UVR-induced cancer and promotion of tumour survival

Metallothionein is a multi-functional protein that protects the host against toxic heavy metals. Under stressful situations it can protect against oxidative damage, contribute to tissue repair, modulate immune responses and limit inflammatory processes. Recently, metallothionein's role in ultraviolet radiation (UVR)-induced injury has been investigated. These studies have shown that when metallothionein is upregulated following exposure to UVR, it can protect against UVR-induced damage and the subsequent development of skin cancer. We propose that this initial protection is achieved through its anti-oxidant role resulting in reduced oxidative stress, reduced apoptosis, reduced NFkappaB activation and enhanced repair of DNA damage. However, once UVR-induced neoplasia has occurred, the cancer cells can hijack metallothionein's protective functions, resulting in increased tumour progression and malignancy. These two discordant sets of attributes are context-dependent, and represent the two faces of metallothionein.

Detection of IFN-alpha produced in the presence of plasma gamma-globulin fraction proteins

Interferon-alpha was detected in IFN pool produced by human leukocytes in the presence of gamma-globulin fraction proteins, copper and zinc cations, and metal-modified gamma-globulins. The cytokine appeared in culture medium at early terms (24 h) of incubation, is characterized by acid resistance, and is neutralized by antibodies to IFN-alpha. The content of IFN-alpha in supernatants of induced leukocytes reached 60-90 pg/ml and correlated with antiviral activity of the samples. Zinc bound to human serum gamma-globulin attenuated and copper stimulated the realization of IFN-inducing characteristics of the protein at early terms of incubation.

Discovery of genes implicated in whirling disease infection and resistance in rainbow trout using genome-wide expression profiling

Background

Whirling disease, caused by the pathogen Myxobolus cerebralis, afflicts several salmonid species. Rainbow trout are particularly susceptible and may suffer high mortality rates. The disease is persistent and spreading in hatcheries and natural waters of several countries, including the U.S.A., and the economic losses attributed to whirling disease are substantial. In this study, genome-wide expression profiling using cDNA microarrays was conducted for resistant Hofer and susceptible Trout Lodge rainbow trout strains following pathogen exposure with the primary objective of identifying specific genes implicated in whirling disease resistance.

Results

Several genes were significantly up-regulated in skin following pathogen exposure for both the resistant and susceptible rainbow trout strains. For both strains, response to infection appears to be linked with the interferon system. Expression profiles for three genes identified with microarrays were confirmed with qRT-PCR. Ubiquitin-like protein 1 was up-regulated over 100 fold and interferon regulating factor 1 was up-regulated over 15 fold following pathogen exposure for both strains. Expression of metallothionein B, which has known roles in inflammation and immune response, was up-regulated over 5 fold in the resistant Hofer strain but was unchanged in the susceptible Trout Lodge strain following pathogen exposure.

Conclusion

The present study has provided an initial view into the genetic basis underlying immune response and resistance of rainbow trout to the whirling disease parasite. The identified genes have allowed us to gain insight into the molecular mechanisms implicated in salmonid immune response and resistance to whirling disease infection.

Zinc supplementation prevents the increase of transaminase in chronic hepatitis C patients during combination therapy with pegylated interferon alpha-2b and ribavirin

We investigated the effects of zinc supplementation on clinical observations in chronic hepatitis C patients receiving pegylated interferon (PEG-IFN) alpha-2b plus ribavirin combination therapy. Patients were randomly allocated to receive 150 mg polaprezinc (zinc group, n=11) or no supplement (control group, n=12) daily in addition to PEG-IFN alpha-2b plus ribavirin therapy and 300 mg vitamin E and 600 mg vitamin C supplementation daily for 48 wk. Among the patients who continued treatment, the serum alanine aminotransferase (ALT) level at 12 wk in the zinc group was significantly lower than that in the control group. All patients in the zinc group (9/9) and 67% (8/12) of the control patients at 24 wk, and all patients in the zinc group (7/7) and 60% (6/10) of the control patients at 48 wk showed a decrease in serum ALT levels to within the normal range (7-44 U/L). HCV RNA disappeared in all patients (7/7) in the zinc group and in 8 of 10 control patients at 48 wk. Polaprezinc supplementation decreased plasma thiobarbituric acid reactive substances and prevented the decrease of polyunsaturated fatty acids of erythrocyte membrane phospholipids. No significant differences were observed in the dosage of medicines or other clinical data during the treatment. These observations indicate that polaprezinc supplementation may have induced some antioxidative functions in the liver which resulted in reduced hepatocyte injury during PEG-IFN alpha-2b plus ribavirin therapy.

Interferonbeta-induced changes in metallothionein expression and subcellular distribution of zinc in HepG2 cells

We evaluated the changes of metallothionein induction and cellular zinc distribution in HepG2 cells by interferonbeta treatment. Immunohistochemical staining of metallothionein was observed in the cytoplasm and nuclei of hepatocytes; which was observed predominantly in the cells treated with interferon and zinc compared to those with zinc alone, interferon alone or the no-treated control. The cellular zinc level was higher in order of the interferon- and zinc-treated cells, the zinc-alone-treated cells, and the interferon-alone-treated cells. Flow cytometry showed that S-phase population increased in interferon-alone-treated cells and interferon- and zinc-treated cells, but not in zinc-alone-treated ones. Cellular elemental distribution was analyzed using in-air micro-particle induced X-ray emission. In zinc-alone-treated sample, X-ray spectra showed good consistency between the enhanced cellular zinc distribution and the phosphorous map. Localizations of bromine followed by interferon treatment were found accompanying a spatial correlation with the phosphorous map. The samples treated with interferon and zinc showed the marked accumulation of zinc and bromine. Discrete bromine accumulation sites were clearly visible with a strong spatial correlation followed by zinc accumulation. These findings suggest that interferonbeta in combination with zinc predominantly induces metallothionein expression in HepG2 cells. In addition, interferonbeta may promote the translocation of metallothionein-bound zinc from cytoplasm to S-phase nuclei.

The effect of zinc supplementation on the treatment of chronic hepatitis C patients with interferon and ribavirin

OBJECTIVES

To evaluate the effects of zinc supplementation on serum zinc and copper levels, and the severity of adverse reactions and virologic responses in chronic hepatitis C patients undergoing interferon (IFN)/ribavirin therapy.

DESIGN AND METHODS

Forty subjects were randomly assigned to receive IFN-alpha-2a/ribavirin with or without zinc gluconate for 24 weeks, then a period of 6 months for follow-up. Twenty healthy controls were also enrolled in the study. Blood samples were collected at different time points during therapy and at 6 months after the completion of therapy and were analyzed for zinc and copper levels. The adverse reactions and the virologic responses were also examined accordingly.

RESULTS

Serum zinc levels were significantly lower in chronic hepatitis C patients than in healthy controls and further depressed by IFN/ribavirin treatment. However, serum zinc levels in patients were remediable by zinc supplements. No apparent difference was seen in virologic responses between subjects with or without zinc supplements, but certain adverse side effects associated with the zinc therapy were significantly decreased.

CONCLUSIONS

Zinc supplementation may be a complementary therapy in chronic hepatitis C patients to increase the tolerance to IFN-alpha-2a and ribavirin.

Interferon alpha induction of metallothionein in rat liver is not linked to interleukin-1, interleukin-6, or tumor necrosis factor alpha

Synthesis of metallothionein (MT) is induced by interferon-alpha (IFN-alpha) in vitro and in vivo. In addition, IFN-alpha promotes redistribution of zinc (Zn) from the plasma to the liver in mice. However, it is not clear if IFN-alpha induces hepatic MT synthesis directly or indirectly via liberation of other cytokines. In order to address this issue, we determined hepatic MT levels, Zn concentration in plasma, liver, and urine, and plasma levels interleukin-1 (IL-1), interleukin-6 (IL-6), and tumor necrosis factor-alpha (TNFalpha) in rats following intramuscular injection of human IFN-alpha (1.5 x 10(6) UI/m(2)). Animals were housed in metabolic cages and sacrificed at various times after IFN-alpha administration. Zn concentrations in serum, urine, and hepatic tissue were determined by atomic absorption spectrophotometry. MT protein was measured using the MT silver saturation method and expression of MT-1 and MT-2 mRNA was measured by RT-PCR. Plasma levels of rat IL-1, IL-6, and TNFalpha were determined using an ELISA method. Hepatic MT levels began to increase at 2 h following IFN-alpha administration and reached maximum levels at 12 h post-treatment. Induction of MT gene expression was confirmed by increases in MT-1 and MT-2 mRNA levels 6, 12, and 18 h after IFN-alpha administration. IFN-alpha treatment also resulted in biphasic increases in hepatic Zn, with levels peaking at 2 h, the time-point when MT levels are first increased, and again at 18 h. Concurrently, there were decreases in serum Zn levels at these time points, suggesting IFN-alpha induced movement of Zn from the blood to hepatic tissue. The decrease in serum Zn was not due to increased excretion since urinary Zn levels were unaffected following IFN-alpha treatment. IFN-alpha administration had no effect on plasma IL-1, IL-6, and TNFalpha levels. These results show that IFN-alpha promotes the increase of hepatic MT levels and plasma/liver redistribution directly, without IL-1, IL-6, or TNFalpha participation.

C-terminal deletion mutant of MRE-binding transcription factor-1 inhibits MRE-driven gene expression

Heavy metal-induced transcriptional activation of the genes coding for metallothionein (MT) is mediated by a cis-acting DNA element, the metal-responsive element (MRE). MRE-binding transcription factor-1 (MTF-1) is a highly conserved heavy metal-induced transcriptional activator. MTF-1 also activates transcription in response to oxidative stress and regulates the expression of several cytoprotective factor genes, including MT, gamma-glutamylcysteine synthetase, and Cu/Zn-superoxide dismutase. It is thus thought that MTF-1 plays a role in cellular stress response. The physiological role of MTF-1 remains unclear because of the lack of MTF-1-specific activators and/or inhibitors. To obtain an MTF-1-specific inhibitor, we constructed an MTFDeltaC (amino acids 1-317), a C-terminal deletion mutant of MTF-1. MTFDeltaC could bind MRE and competed with MTF-1 for MTF-MRE complex formation. Transient expression of MTFDeltaC in HepG2 cells reduced MRE-driven gene expression, demonstrating that MTFDeltaC is dominant to MTF-1. HepG2 cells stably expressing MTFDeltaC showed increased susceptibility to the cytotoxic effects of tert-butyl hydroperoxide (tBH). Furthermore, we constructed Ad5MTFDeltaC, a recombinant adenovirus that expresses MTFDeltaC. Infection with the virus induced MTFDeltaC expression and increased susceptibility to the cytotoxic effects of tBH. These results indicate that MTF-1 participates in controlling the cellular redox state.

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.

Glucocorticoid and type 1 interferon interactions at the blood-brain barrier: relevance for drug therapies for multiple sclerosis

The pharmacological effect of glucocorticoids and type 1 interferons (IFNs), simultaneously used as therapeuticals for multiple sclerosis (MS), on the (inflamed) blood-brain barrier (BBB) was investigated in vitro. Although both drugs additively decreased BBB permeability, they did not prevent the increase in BBB permeability induced by lipopolysaccharide (LPS), which served as a pro-inflammatory stimulus. The beneficial clinical effect of glucocorticoid and IFN therapy for MS seems there- fore not to be mediated through a direct action at the level of the BBB. Most strikingly, however, pretreatment with type 1 IFNs (alpha and beta) potentiated the effect of glucocorticoids by two orders of magnitude. This lead us to hypothesize that type 1 IFNs may restore the dysfunctional T-helper 1 (Th1)/Th2 balance associated with MS, by a mechanism that involves an increased sensitivity for glucocorticoids.

Astrocyte-targeted expression of interleukin-3 and interferon-alpha causes region-specific changes in metallothionein expression in the brain

Transgenic mice expressing IL-3 and IFN-alpha under the regulatory control of the GFAP gene promoter (GFAP-IL3 and GFAP-IFNalpha mice) exhibit a cytokine-specific, late-onset chronic-progressive neurological disorder which resemble many of the features of human diseases such as multiple sclerosis, Aicardi-Goutières syndrome, and some viral encephalopathies including HIV leukoencephalopathy. In this report we show that the metallothionein-I+II (MT-I+II) isoforms were upregulated in the brain of both GFAP-IL3 and GFAP-IFNalpha mice in accordance with the site and amount of expression of the cytokines. In the GFAP-IL3 mice, in situ hybridization analysis for MT-I RNA and radioimmunoassay results for MT-I+II protein revealed that a significant upregulation was observed in the cerebellum and medulla plus pons at the two ages studied, 1-3 and 6-10 months. Increased MT-I RNA levels occurred in the Purkinje and granular layers of the cerebellum, as well as in its white matter tracts. In contrast to the cerebellum and brain stem, MT-I+II were downregulated by IL-3 in the hippocampus and the remaining brain in the older mice. In situ hybridization for MT-III RNA revealed a modest increase in the cerebellum, which was confirmed by immunohistochemistry. MT-III immunoreactivity was present in cells that were mainly round or amoeboid monocytes/macrophages and in astrocytes. MT-I+II induction was more generalized in the GFAP-IFNalpha (GIFN12 and GIFN39 lines) mice, with significant increases in the cerebellum, thalamus, hippocampus, and cortex. In the high expressor line GIFN39, MT-III RNA levels were significantly increased in the cerebellum (Purkinje, granular, and molecular layers), thalamus, and hippocampus (CA2/CA3 and especially lacunosum molecular layers). Reactive astrocytes, activated rod-like microglia, and macrophages, but not the perivenular infiltrating cells, were identified as the cellular sources of the MT-I+II and MT-III proteins. The pattern of expression of the different MT isoforms in these transgenic mice differed substantially, demonstrating unique effects associated with the expression of each cytokine. The results indicate that the MT expression in the CNS is significantly affected by the cytokine-induced inflammatory response and support a major role of these proteins during CNS injury.

Role of IL-6 in the induction of hepatic metallothionein in mice after partial hepatectomy

Metallothioneins (MT) are induced upon partial hepatectomy (PH), possibly mediated by various cytokines. In the present study, we studied cytokine-dependent MT synthesis in partially hepatectomized IL-6 gene knock-out (GKO) mice in the remaining lobe of the liver. We focused on IL-6, TNFalpha and IL-1beta, the major cytokines thought to be involved in MT synthesis. The IL-6 GKO mice and B6J129Sv (wild-type control) mice were subjected to 70% PH or laparotomy. We found that MT was significantly decreased in IL-6 GKO mice, although PH induced hepatic MT in both strains of mice. Laparotomy induced MT in the liver of wild-type mice but not in IL-6 GKO mice. Pretreatment of IL-6 GKO mice with rIL-6 (5 microg/mouse) restored hepatic MT synthesis. Serum IL-6 level in wild-type mice was maximal at 6 h after surgery and decreased thereafter. Serum IL-1beta was the same in both strains of mice. Serum TNFalpha basal level in IL-6 GKO mice was higher than in wild-type mice. PH caused an increase in serum TNFalpha level in both strains of mice, and it was two times higher in IL-6 GKO mice than in wild-type mice at 18 h after surgery. We conclude that IL-6 plays a predominant role in hepatic MT synthesis after PH, but that IL-6 GKO mice still reserve the capacity to synthesize MT by an as yet unidentified mechanism.

Repeated administration of alpha-hederin results in alterations in maternal zinc status and adverse developmental outcome in the rat

The administration of alpha-hederin, an inducer of metallothionein, results in a secondary zinc deficiency that may be an important maternally mediated mechanism of developmental toxicity. Previous studies have shown adverse developmental outcome with a single administration of alpha-hederin to rats on gestation day (GD) 8 or 11. The objective of this study was to determine whether dosing of alpha-hederin throughout organogenesis would result in a sustained elevation of maternal hepatic metallothionein and subsequent developmental abnormalities. Rats were administered dosage levels of 0 (vehicle only), 20, or 30 mumol/kg from GD 6-15. Maternal hepatic metallothionein levels were 10-fold higher on GD 16 in the treatment groups than the controls. Consequently, liver zinc concentrations increased 60% and 54%, whereas plasma levels decreased 23% and 33% in the 20 and 30 mumol/kg treatment groups, respectively. At GD 20, mean fetal weights of the treatment litters were 11% less than control litters. The administration of alpha-hederin resulted in a threefold increase in the number of offspring that exhibited developmental abnormalities, including visceral and skeletal malformations. Following an oral pulse of 65Zn subsequent to treatment with 0 or 20 mumol/kg of alpha-hederin, the distribution of 65Zn to the liver of treated dams was twice that of controls, whereas the radiolabeled zinc apportioned to the decidua and uterus decreased by 44%. Furthermore, the 65Zn detected in the embryos from treated dams was 70% lower than in embryos from control dams. In conclusion, low doses of a metallothionein inducer administered to the dam from GD 6-15 resulted in a sustained elevation of hepatic metallothionein and a subsequent redistribution of zinc leading to a decrease in the zinc available to the embryo and ultimately to adverse development of the offspring. Repeated dosing throughout organogenesis, as required in regulated safety assessment testing, increased the severity of the effects previously observed with single large dosages of the toxicant administered during midgestation.

The possible role of zinc and metallothionein in the liver on the therapeutic effect of IFN-alpha to hepatitis C patients

We have studies zinc deficiency in hepatitis C patients (complete responder [CR] 22, nonresponder [NR] 25) with relation to the therapeutic effect of interferon-alpha (IFN-alpha). Circadian variations in serum zinc levels were high in the morning (basal level) and then gradually decreased during the day in both chronic hepatitis C patients and healthy controls. Basal zinc levels in serum were significantly lower in chronic hepatitis C patients (73 +/- 3 micrograms/dL, n = 12) than in controls (93 +/- 5 micrograms/dL). An injection of 10 MU of IFN-alpha to hepatitis C patients augmented the serum zinc reductions, up to 40% in 8 h. Serum cortisol levels were significantly elevated 8 h (25.6 +/- 2.3 micrograms/dL) after IFN-alpha dose. Forty-seven chronic hepatitis C patients were treated with IFN-alpha for 24 wk, and serum zinc and copper levels were determined 12 and 24 wk during and after the completion of IFN-alpha therapy. Serum zinc levels and zinc/copper ratio were higher in CRs than in NRs to IFN therapy at each time-point. Hepatic metallothionein staining became prominent after IFN therapy in most of CRs, whereas it diminished NRs. These data suggest that nutritional status of zinc influences the effect of IFN on hepatitis C patients.