Inflammation, an inducer of metallothionein, inhibits carbon-tetrachloride-induced hepatotoxicity in rats

Trace Element Levels in Serum Are Potentially Valuable Diagnostic Markers in Dogs

The objective of this study was to obtain information about the role of trace element imbalance in the pathogenesis of certain diseases in dogs and to evaluate the suitability of trace element profiling as an additional tool in the diagnosis. Serum trace element concentrations (copper, molybdenum, selenium and zinc) were measured in a cohort of healthy (control) dogs (n = 42) and dogs affected by hepatic (n = 25), gastrointestinal (n = 24), inflammatory/infection (n = 24), and renal (n = 22) diseases. These data were analyzed together with data on basic biochemical parameters (alanine aminotransferase, alkaline phosphatase, blood urea nitrogen, creatinine, albumin, globulin, and glucose) by using chemometric techniques. The chemometric analysis revealed distinctive association patterns between trace elements and biochemical parameters for each clinical disorders. The findings provide clear evidence for the important role of trace elements in disease, particularly in relation to acute phase reactions, with serum copper providing an indirect measurement of ceruloplasmin (positive acute-phase protein) and serum selenium and zinc acting as negative acute phase reactants. Molybdenum may also be a suitable marker of incipient renal disease. Thus, the analysis of trace element profiles, by multielement techniques, in a single serum sample would be a valuable additional tool for the diagnosis of certain diseases.

Preventive Effect of Blueberry Extract on Liver Injury Induced by Carbon Tetrachloride in Mice

The blueberry is a common fruit that is rich in nutritional value and polyphenol substances. In this study, the blueberry polyphenol content in extract was analysed by spectrophotometry. The results showed that the blueberry polyphenol content in the extract reached 52.7%. A mouse model of liver injury induced by carbon tetrachloride (CCl₄) was established to study the preventive effect of blueberry extract (BE) on liver injury in mice and the experimental animals were examined using biochemical and molecular biological methods. Aspartate aminotransferase (AST) and alanine aminotransferase (ALT) are important clinical liver function indicators; the changes of triglyceride (TG) and total cholesterol (TC) are observed after liver injury; interleukin-6 (IL-6), tumour necrosis factor-α (TNF-α) and interferon-γ (IFN-γ) are important inflammatory indexes; superoxide dismutase (SOD) activity and thiobarbituric acid reactive substances (TBARS) are important changes of oxidative stress indexes. The in vivo animal experiment results showed that BE decreased the liver index of mice with liver injury, BE could reduce the AST, ALT, TG and TC levels and also could reduce the serum cytokine IL-6, TNF-α and IFN-γ levels in mice with liver injury. Moreover, BE increased the SOD activity and decreased the TBARS level in the gastric tissues of mice with liver injury. After treatment with the highest concentration of BP in liver injury mice, these levels returned close to those obtained after treatment with the standard drug of silymarin. Detection of messenger RNA (mRNA) in liver tissue showed that BE upregulated the Cu/Zn-SOD, Mn-SOD and chloramphenicol acetyltransferase (CAT) expression levels and downregulated cyclooxygenase (COX)-2 expression. The effect of BE on mice with liver injury was positively correlated with the BE concentration and was similar to that of silymarin, which is a drug for liver injury, suggesting that BE had a good preventive effect on liver injury. Thus, BE rich in polyphenols is a bioactive substance with value for development and utilization.

Preventive Effect of Alkaloids from Lotus plumule on Acute Liver Injury in Mice

Lotus plumule is a traditional Chinese food that can be used as a beverage. In this study, three kinds of Lotus plumules from different regions of China were selected to observe the preventive effects of extracted alkaloids on CCl₄-induced liver injuries. Animal experiments revealed that alkaloids extracted from Lotus plumules decreased the serum AST (aspartate aminotransferase), ALT (alanine aminotransferase), and TBIL (total bilirubin) levels, enhanced SOD (superoxide dismutase) activity, and reduced MDA (malondialdehyde) level in the liver tissues of mice with liver injury. H&E observation confirmed that alkaloids from Lotus plumules could alleviate CCl₄-induced injuries of liver tissues and inhibit the inflammatory effect on hepatocytes. Further qPCR experiments also demonstrated that alkaloids from Lotus plumules upregulated the expression of IκB-α (inhibitor of NF-κB alpha), Cu/Zn-SOD (copper/zinc superoxide dismutase), Mn-SOD (manganese superoxide dismutase), and CAT (catalase) mRNA and downregulated TNF-α (tumor necrosis factor alpha) and NF-κB (nuclear factor kappa B) expression in the liver tissues of mice with liver injury. All three kinds of alkaloids from Lotus plumules could prevent CCl₄-induced liver injuries by regulating the levels of oxidative stress and inflammation in mice, and the therapeutic effect was comparable to that of silymarin, the medicine commonly used in the treatment of liver diseases. In summary, alkaloids from Lotus plumules contain bioactive substances with hepatic protective efficacy and possess potential application value in the field of functional food.

Characterization of the acute temporal changes in excisional murine cutaneous wound inflammation by screening of the wound-edge transcriptome

This work represents a maiden effort to systematically screen the transcriptome of the healing wound-edge tissue temporally using high-density GeneChips. Changes during the acute inflammatory phase of murine excisional wounds were characterized histologically. Sets of genes that significantly changed in expression during healing could be segregated into the following five sets: up-early (6-24 h; cytokine-cytokine receptor interaction pathway), up-intermediary (12-96 h; leukocyte-endothelial interaction pathway), up-late (48-96 h; cell-cycle pathway), down-early (6-12 h; purine metabolism) and down-intermediary (12-96 h; oxidative phosphorylation pathway). Results from microarray and real-time PCR analyses were consistent. Results listing all genes that were significantly changed at any specific time point were further mined for cell-type (neutrophils, macrophages, endothelial, fibroblasts, and pluripotent stem cells) specificity. Candidate genes were also clustered on the basis of their functional annotation, linking them to inflammation, angiogenesis, reactive oxygen species (ROS), or extracellular matrix (ECM) categories. Rapid induction of genes encoding NADPH oxidase subunits and downregulation of catalase in response to wounding is consistent with the fact that low levels of endogenous H2O2 is required for wound healing. Angiogenic genes, previously not connected to cutaneous wound healing, that were induced in the healing wound-edge included adiponectin, epiregulin, angiomotin, Nogo, and VEGF-B. This study provides a digested database that may serve as a valuable reference tool to develop novel hypotheses aiming to elucidate the biology of cutaneous wound healing comprehensively.

Dose- and time-dependent effects of luteolin on liver metallothioneins and metals in carbon tetrachloride-induced hepatotoxicity in mice

The aim of this study was to investigate the protective effect of luteolin on liver Ca, Mg, Zn, Cu, Fe, and Mn content in mice with carbon tetrachloride (CCl4)-induced hepatotoxicity. Additionally, liver metallothionein (MT) expression was studied. Luteolin was administered intraperitoneally (i.p.) as a single 5- or 50-mg/kg dose or once daily for two consecutive days, respectively. Two hours after the last injection, the mice were treated with CCl4 (20 mg/kg, i.p.). CCl4 injection reduced hepatic level of all metals except Ca, with an intense cytoplasmic staining pattern in hepatocytes located in periportal areas, indicating induction of MTs. Pretreatment with 50 mg/kg of luteolin for 2 days remarkably elevated metal content to control values (Mg and Cu) or even above them (Zn and Fe). Luteolin pretreatment increased pericentral MTs immunopositivity and histological architecture improvement in a time- and dose-dependent manner, being the most prominent in mice pretreated with 50 mg/kg for 2 days. The liver in this group showed pronounced MT expression in almost all hepatocytes throughout the liver parenchyma. In conclusion, these results suggest the protective effect of luteolin on CCl4-induced hepatotoxicity and an enhancement of hepatocyte proliferative capabilities.

Acute phase reaction and acute phase proteins

A review of the systemic acute phase reaction with major cytokines involved, and the hepatic metabolic changes, negative and positive acute phase proteins (APPs) with function and associated pathology is given. It appears that APPs represent appropriate analytes for assessment of animal health. Whereas they represent non-specific markers as biological effect reactants, they can be used for assessing nutritional deficits and reactive processes, especially when positive and negative acute phase variables are combined in an index. When such acute phase index is applied to separate healthy animals from animals with some disease, much better results are obtained than with single analytes and statistically acceptable results for culling individual animals may be reached. Unfortunately at present no cheap, comprehensive and easy to use system is available for assessing various acute phase proteins in serum or blood samples at the same time. Protein microarray or fluid phase microchip technology may satisfy this need; and permit simultaneous analysis of numerous analytes in the same small volume sample and enable integration of information derived from systemic reactivity and nutrition with disease specific variables. Applying such technology may help to solve health problems in various countries not only in animal husbandry but also in human populations.

Modulatory effect of cadmium exposure on deltamethrin-induced oxidative stress in Channa punctata Bloch

The modulatory effect of cadmium pretreatment (0.2 mg/kg b.w. i.p.) on deltamethrin-induced oxidative stress and alterations of antioxidants was studied in freshwater fish Channa punctata Bloch. Lipid peroxidation (LPO) was measured as one of the indicators of oxidative stress. Activities of glutathione peroxidase, glutathione reductase, and glutathione-S-transferase were also studied in liver, kidney, and gills. Levels of reduced glutathione (GSH) were measured in various tissues. Fish pretreated with cadmium and subsequently exposed to deltamethrin showed significantly reduced LPO values when compared with deltamethrin-exposed fish. Conversely, in the kidney, a potentiation response was observed. Deltamethrin exposure in fish resulted in significant alteration in activities of glutathione-dependent antioxidant enzymes. In the cadmium preexposed fish, which were subsequently exposed to deltamethrin, antioxidant enzymes showed a tendency toward normalization over deltamethrin-only exposed fish in liver and gills. GSH also showed a similar pattern in liver and gills but in kidney it remained elevated. Cadmium alone had no significant effect on various parameters at the concentration used in this study. When metallothionein (MT) induction was studied, only liver showed an MT-like protein band in sodium dodecylsulfate-polyacrylamide gel electrophoresis analysis. These results demonstrate a modulatory role of cadmium on the oxidative stress and other related parameters in liver and gills. These findings are important in the context of exposure to a mixture of pollutants in aquatic environment.

Prognostic significance of metallothionein expression in renal cell carcinoma

Background

Metallothionein (MT) protein expression deficiency has been implicated in carcinogenesis while MT over expression in tumors is indicative of tumor resistance to anti-cancer treatment. The purpose of the study was to examine the expression of MT expression in human renal cell carcinoma (RCC) and to correlate MT positivity, the pattern and extent of MT expression with tumor histologic cell type and nuclear grade, pathologic stage and patients' survival.

Patients and methods

The immunohistochemical expression of MT was determined in 43 formalin-fixed and paraffin-embedded RCC specimens, using a mouse monoclonal antibody that reacts with both human MT-I and MT-II. Correlation was sought between immunohistochemical (MT positivity, intensity and extension of staining) and clinico-pathological data (histological cell type, tumor nuclear grade, pathologic stage and patients' survival).

Results

Positive MT staining was present in 21 cases (49%), being mild/moderate and intense in 8 and 13 cases, respectively. The pattern was cytoplasmic in 7 cases and was both cytoplasmic and nuclear in 14 cases. MT expression in a percentage of up to 25% of tumor cells (negative MT staining included) was observed in 31 cases, in a percentage 25–50% of tumor cells in 7 cases, and in a percentage of 50–75% of tumor cells in 5 cases. There was no significant correlation of MT intensity of staining to histological type, stage and patients' survival, while it was inversely correlated to higher tumor nuclear grade. MT extent of staining did not correlate with histological type, nuclear grade, and pathologic stage while a statistically significant association was found with patients' survival.

Conclusions

The inverse correlation between MT staining intensity and tumor nuclear grade in RCC suggests a role of MT in tumor differentiation process. Since extent of MT expression is inversely correlated with survival it may be possibly used as a clinical prognostic parameter.

Expression of metallothionein in lung carcinoma: correlation with histological type and grade

AIMS

Over-expression of cellular metallothionein occurs frequently in human tumours but the underlying mechanism remains unknown. The aim of this study was to assess metallothionein expression in cases of lung carcinoma and to correlate it with histopathological parameters.

METHODS AND RESULTS

Tumour tissue samples from 89 patients with lung carcinoma were immunostained by the streptavidin-biotin-peroxidase technique, using a monoclonal antibody against both metallothionein-1 and -2 isoforms. Positive matallothionein immunostaining was prominent in 44 out of 89 (49%) and negative in 45 out of 89 (51%) cases of lung carcinoma examined. Metallothionein positivity was prominent in 32 out of 43 (74%) cases of squamous cell lung carcinoma, and in 12 out of 35 (34%) cases of adenocarcinoma, while it was negative in all 11 cases of small-cell lung carcinoma examined, presenting a statistically significant difference between the different histological types. The intensity of metallothionein staining revealed a statistically significant difference between the squamous cell and adenocarcinoma cases examined. The pattern and extent of metallothionein staining in tumour cells and the expression of metallothionein in stromal cells were not correlated with histopathological parameters (type and grade) in metallothionein-positive cases of lung carcinoma examined. No association was found between metallothionein expression and lymph node status in the examined cases of lung carcinoma.

CONCLUSIONS

Our findings indicate that expression of metallothionein was evident in squamous cell lung carcinoma and adenocarcinoma, but absent in small-cell lung carcinoma, supporting evidence for participation of this protein in the biological mechanisms underlying the carcinogenic evolution in the lung.

Induction of metallothionein in the liver of carbon tetrachloride intoxicated rats: an immunohistochemical study

Metallothioneins (MTs), are low molecular weight proteins, mainly implicated in metal ion detoxification. In the present study, we investigated the expression of hepatic MT in a rat model of injury and regeneration, induced by carbon tetrachloride (CCl(4)) administration. A single intraperitoneal injection of 1 ml CCl(4)/kg body weight was performed in male Wistar rats, killed at different time points post-administration. The enzymatic activities of aspartate and alanine aminotransferases in serum were determined, in addition to the liver histological findings, to estimate hepatotoxicity. The rate of tritiated thymidine incorporation into hepatic DNA, the enzymatic activity of thymidine kinase in liver tissue and the assessment of the mitotic index in hepatocytes, were used as indices of regeneration. MT was detected immunohistochemically in liver tissue sections. CCl(4) administration caused severe hepatic injury, followed by regeneration. MT expression became prominent as early as 12 h after the administration of CCl(4), in the nuclei of hepatocytes, while at 24 and 36 h intense cytoplasmic staining for MT appeared in the hepatocytes in the vicinity of necrotic areas. The peak of hepatocyte proliferative capacity, occurring at 48 h post-CCl(4) administration coincides with the maximum nuclear and cytoplasmic MT expression. At further time points MT expression presented a decreasing trend. Induction of MT expression was observed in the liver after a single administration of CCl(4), being more prominent at the time of maximum hepatocellular proliferation, participating actively in the replication of hepatocytes.

Metallothionein: an intracellular protein to protect against cadmium toxicity

Metallothioneins (MT) are low-molecular-weight, cysteine-rich, metal-binding proteins. MT genes are readily induced by various physiologic and toxicologic stimuli. Because the cysteines in MT are absolutely conserved across species, it was suspected that the cysteines are necessary for function and MT is essential for life. In attempts to determine the function(s) of MT, studies have been performed using four different experimental paradigms: (a) animals injected with chemicals known to induce MT; (b) cells adapted to survive and grow in high concentrations of MT-inducing toxicants; (c) cells transfected with the MT gene; and (d) MT-transgenic and MT-null mice. Most often, results from studies using the first three approaches have indicated multiple functions of MT in cell biology: MT (a) is a "storehouse" for zinc, (b) is a free-radical scavenger, and (c) protects against cadmium (Cd) toxicity. However, studies using MT-transgenic and null mice have not strongly supported the first two proposed functions but strongly support its function in protecting against Cd toxicity. Repeated administration of Cd to MT-null mice results in nephrotoxicity at one tenth the dose that produces nephrotoxicity in control mice. Human studies indicate that 7% of the general population have renal dysfunction from Cd exposure. Therefore, if humans did not have MT, "normal" Cd exposure would be nephrotoxic to humans. Thus, it appears that during evolution, the ability of MT to protect against Cd toxicity might have taken a more pivotal role in the maintenance of life processes, as compared with its other proposed functions (i.e. storehouse for zinc and free radical scavenger).

Protection against carbon tetrachloride hepatotoxicity by oleanolic acid is not mediated through metallothionein

Oleanolic acid is a triterpenoid compound that has been shown to protect against liver injury produced by some hepatotoxicants. This study was designed to characterize the protective effects of oleanolic acid on carbon tetrachloride-induced hepatotoxicity, and the role of metallothionein in the protection. Oleanolic acid pretreatment (100-400 micromol/kg, s.c.) protected Sprague-Dawley rats and mice from carbon tetrachloride-induced liver injury in a dose- and time-dependent manner, as evidenced by serum alanine aminotransferase and sorbitol dehydrogenase activities, as well as by histopathology. The protection against carbon tetrachloride hepatotoxicity was not evident until animals were pretreated with oleanolic acid 12 h, and lasted for 72 h after a single injection. This suggests that the protection might be due to induction of some adaptive mechanisms. Metallothionein (MT), an acute-phase protein proposed to decrease carbon tetrachloride-induced liver injury, was dramatically induced following oleanolic acid treatment. To examine whether oleanolic acid protection is mediated through MT, MT-I and II knock-out (MT-null) mice were utilized. Oleanolic acid pretreatment increased MT levels in control mice (20-fold), but not in MT-null mice, however, it protected equally against carbon tetrachloride-induced hepatotoxicity in both control and MT-null mice. These data indicate that oleanolic acid is effective in protecting rats and mice from the hepatotoxicity produced by carbon tetrachloride, and the protection is not mediated through induction of MT.

Paracetamol hepatotoxicity in metallothionein-null mice

The role of metallothionein (MT) in protecting the liver against paracetamol (PCT) toxicity was investigated in vivo and in vitro in mice lacking expression of MT-1 and MT-2 genes (MT -/-). In the fed, glycogen replete state, hepatotoxicity (PCT 300 mg/kg i.p.) at 6 h was significantly greater in MT -/- than MT +/+ mice. Plasma lactate dehydrogenase (LD) and alanine aminotransferase (ALT) were 5- and 13-fold greater respectively than in MT +/+ mice. Liver glycogen, glucose and zinc levels were significantly lower in MT -/- mice at this time. In contrast, hepatotoxicity (PCT 135 mg/kg i.p.) at 6 h was similar in both MT +/+ and MT -/- mice fasted 24 h, despite a doubling in liver MT in MT +/+ mice. No differences were found between MT -/- and MT +/+ mice in cytochrome P450 activity. Liver glutathione levels were the same in both groups of mice prior to fasting and were decreased to a similar extent (55-65%) following PCT treatment. Investigation of lower PCT doses (< or = 120 mg/kg) in fasted mice over 24 h demonstrated a greater susceptibility in female MT -/- mice with plasma LD, 2.4-fold and ALT, 7.5-fold greater than in MT +/+ mice at 120 mg/kg PCT. In male MT -/- mice, there was only a trend towards greater susceptibility at 110 mg/kg PCT compared to male MT +/+ mice, and at 120 mg/kg, both male genotypes were equally affected. Investigations with cultured hepatocytes supported the in vivo findings in that there was a trend towards greater toxicity (PCT at 1 and 5 mM for 24 h) in hepatocytes from fed MT -/- mice, with the difference diminished in association with greater hepatotoxicity in hepatocytes from fasted mice. Use of dexamethasone (Dex) to increase MT in the MT +/+ mouse hepatocytes protected from PCT toxicity. Zn alone was not protective. Zn plus Dex offered no protection despite higher MT levels. Generation of apo-MT with Dex may offer more protection than Zn-MT. In conclusion, MT -/- mice were more susceptible than MT +/+ mice to PCT toxicity in the fed state, but the increased susceptibility was much smaller, but still significant, when the effects of glycogen were minimised by fasting.

Effects of mild zinc deficiency, plus or minus acute phase response, on CCl4 hepatotoxicity

Low zinc (Zn) intake could be expected to compromise resistance to oxidative stress, even when accompanied by a normally protective acute phase response pretreatment. Mildly Zn deficient rats showed very high degrees of CCl4-induced hepatic cell membrane injury as assessed by serum sorbitol dehydrogenase activities. Rats pair-fed adequate Zn also showed above normal degrees of injury, but much less than rats fed low Zn. An acute phase response, elicited by leg inflammation, strongly protected rats consuming adequate Zn, either ad libitum or pair-fed, against the CCl4-induced rise in sorbitol dehydrogenase. However, the effect was partially absent in rats fed low Zn. Zinc intake had no effect on CCl4-produced microsomal injury, assessed by glucose-6-phosphatase activities. Rats fed low Zn showed normal hepatic levels of metallothionein, a Zn protein with proposed antioxidant functions, but did not show the rise in metallothionein levels normally associated with acute phase response. In summary, mild Zn deficiency caused poor resistance to CCl4-induced plasma membrane injury and partially negated acute phase response protective effects. Metallothionein was not involved in the former effect, but may have contributed to the latter.