Plasma activity of Thioredoxin Reductase as a Novel Biomarker in Gastric Cancer.

Gastric cancer (GC) is one of the leading malignancies around the world. Identification of novel and efficient biomarkers for GC diagnosis and evaluation of therapeutic efficiency could improve the therapeutic strategy in future clinical application. This study aims to evaluate the levels of plasma thioredoxin reductase (TrxR) activity in GC patients to confirm its validity and efficacy in GC diagnosis and evaluation of therapeutic efficiency. 923 cases were enrolled in the current study. In the group of GC patients before clinical intervention, plasma TrxR activity [9.09 (7.96, 10.45) U/mL] was significantly higher than in healthy controls [3.69 (2.38, 5.32) U/mL]. The threshold of TrxR activity for GC diagnosis was set at 7.34 U/mL with a sensitivity of 85.5% and a specificity of 97.9%. In GC patients after chemotherapy, plasma TrxR activity was remarkably higher in patients with progressive disease or uncontrolled condition [10.07 (8.19, 11.02) U/mL] compared with patients with complete or partial response [7.12 (6.08, 8.37) U/mL] in response to chemotherapy. TrxR activity displayed the higher efficiency to distinguish between GC patients with two distinct clinical outcomes than carcinoembryonic antigen (CEA), cancer antigen 72-4 (CA72-4) and cancer antigen 19-9 (CA19-9). Moreover, combination of TrxR, CEA, CA72-4 and CA19-9 was demonstrated to be more effective in both GC diagnosis and evaluation of therapeutic efficiency than was each biomarker individually. Together, plasma TrxR activity was identified as a novel and efficient biomarker of GC, both in diagnosis and monitoring of therapeutic efficiency in response to chemotherapy.

Thioredoxin Reductase as a Novel and Efficient Plasma Biomarker for the Detection of Non-Small Cell Lung Cancer: a Large-scale, Multicenter study.

There is an increased demand for efficient biomarkers for the diagnosis of non-small cell lung cancer (NSCLC). This study aimed to evaluate plasma levels of TrxR activity in a large population to confirm its validity and efficacy in NSCLC diagnosis. Blood samples were obtained from 1922 participants (638 cases of NSCLC, 555 cases of benign lung diseases (BLDs) and 729 sex- and age-matched healthy controls). The plasma levels of TrxR activity in patients with NSCLC (15.66 ± 11.44 U/ml) were significantly higher (P < 0.01) than in patients with BLDs (6.27 ± 3.78 U/ml) or healthy controls (2.05 ± 1.86 U/ml). The critical value of plasma TrxR activity levels for diagnosis of NSCLC was set at 10.18 U/ml, with a sensitivity of 71.6% and a specificity of 91.9%. The combination of NSE, CEA, CA19-9, Cyfra21-1, and TrxR was more effective for NSCLC diagnosis (sensitivity and specificity in the training set: 85.6%, 90.2%; validation set: 86.2%, 92.4%) than was each biomarker individually (P < 0.001). TrxR can also efficiently distinguish the metastatic status of the tumor, and it can further differentiate between various histological differentiations. Together, plasma TrxR activity was identified as a convenient, non-invasive, and efficient biomarker for the diagnosis of NSCLCs, particularly for discriminating between metastatic and non-metastatic tumors, or for histologic differentiation.

Thioredoxin reductase gene expression and activity among human T-cell lymphotropic virus type 1-infected patients.

BACKGROUND: The thioredoxin (Trx) system is a reducing complex, consisting of Trx, Trx reductase (TrxR), and NADPH, that scavenges reactive oxygen species. The system is a natural protective mechanism to prevent apoptosis and progression of oxidative stress-related diseases. The present study was conducted to explore possible changes in TrxR activity and gene expression as a response to the oxidative stress during HTLV-1 infection. MATERIALS AND METHODS: Blood samples were collected from 40 HTLV-1-infected patients and 40 age- and sex-matched healthy controls. The patient group consisted of chronic asymptomatic carriers and HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM-TSP) patients. A commercial kit was used to measure the TrxR enzyme activity, and real-time polymerase chain reaction was performed to evaluate TrxR gene expression in extracted peripheral blood mononuclear cells (PBMCs). RESULTS: A decreasing pattern of TrxR enzyme activity was observed among control, carrier, and HAM-TSP groups (mean ± SD; controls, 0.1734 ± 0.056; carriers, 0.134 ± 0.065; and HAM-TSP, 0.0928 ± 0.047 µmol/min/mL). Cellular TrxR gene expression showed the same decreasing trend. The fold differences of gene expression in carriers and HAM-TSP groups compared with healthy controls were 0.8 and 0.7 vs 1, respectively. CONCLUSION: We found a reduction in TrxR expression as well as serum enzyme activity in HTLV-1-infected individuals, particularly in HAM-TSP patients. The reduced TrxR activity during HTLV-1 infection may hamper the natural protective mechanisms, thereby contributes to virus-induced complications.

8-F2-isoprostane, thioredoxin and thioredoxin reductase levels in children with obsessive-compulsive disorder.

PURPOSE: Accumulating data demonstrate that oxidative stress may play a crucial role in obsessive-compulsive disorder (OCD). This study aimed to investigate the role of 8-F2-isoprostane, thioredoxin (Trx), and thioredoxin reductase (TrxR) in children with OCD. MATERIALS AND METHODS: Thirty-three drug-free children with OCD and 35 healthy controls were included in this study. The severity of OCD symptoms was assessed via the Children's Yale Brown Obsessive-Compulsive Scale. The severity of anxiety levels was determined through the Screen for Child Anxiety-Related Emotional Disorders. Plasma levels of 8-F2-isoprostane, Trx, and TrxR were measured using commercial enzyme-linked immunosorbent assay kits. RESULTS: Plasma 8-F2-isoprostane, Trx, and TrxR levels did not show any significant differences between patient and control groups. There were no significant correlations between plasma levels of these antioxidants and severity of OCD. CONCLUSIONS: Findings of this study did not support the involvement of oxidative stress in the etiology of childhood OCD.

Spectrophotometric assays for measuring redox biomarkers in blood and tissues: the NADPH network.

Nicotinamide adenine dinucleotide (NAD+/NADH) along with its phosphorylated form (NADP+/NADPH) are two molecules ubiquitously present in all organisms, and they play key roles as cofactors in fundamental catabolic and anabolic processes, respectively. The oxidation of NADPH to NADP+ initiates a cascade of reactions, where a network of molecules is implicated. The molecules of this cascade form a network with eminent translational potential in redox metabolism. A special point of interest is that spectrophotometric assays have been developed both for NADH/NADPH and the molecules directly regulated by them. Therefore, crucial molecules of the NADPH-dependent redox network can be measured, and the results can be used to assess the bioenergetic and/or oxidative stress status. The main aim of this review is to collectively present the NADPH-related molecules, namely NADPH, NADH, NAD+ kinase, NADPH oxidase, peroxiredoxin, thioredoxin, thioredoxin reductase, and nitric oxide synthase, that can be measured in blood and tissues with the use of a spectrophotometer, which is probably the most simple, inexpensive and widely used tool in biochemistry. We are providing the researchers with reliable and valid spectrophotometric assays for the measurement of the most important biomarkers of the NADPH network in blood and other tissues, thus allowing the opportunity to follow the redox changes in response to a stimulus.

[Effect of oxidative stress-associated damage to the lung tissue caused by different body mass index in the rat models].

Objective: To investigate the influence of different diets on serum protein expression levels of 4-hydroxynonenal (4-HNE), thioredoxin (Trx), thioredoxin reductase (TrxR) and the activities of Trx and TrxR, and to explore the effect of damage to the lung tissue and the underlying mechanisms of different body mass index caused by different diets in the rat models . Method: Healthy clean male SD rats were randomly divided into normal group, emaciation group and fat group, which were raised by different diets for 6 months.Then the rats were sacrificed and the serum and lung tissue were prepared. The levels of 4-HNE, Trx and TrxR in peripheral blood were quantitatively analyzed by enzyme-linked immunosorbent assay(ELISA), and the activities of Trx and TrxR were measured by chemical methods. Results: Compared with the normal group, the lung tissue had more apparent emphysema in the emaciation and the fat groups under light microscope, and more inflammatory cell infiltration in alveolar septum was observed in the fat group.The levels of 4-HNE in the fat group[(24.7±8.7)mg/L]was significantly higher than that in the normal group[(15.4±4.7)mg/L, P<0.05)], but there was no significant difference(P>0.05)in the levels of 4-HNE between the emaciation and the normal groups. The levels of TrxR in the emaciation group[(7.7±1.4)µg/ml]was significantly higher than that in the normal and the fat groups[(6.2±1.1), (4.9±1.4)µg/ml, all P<0.05)]. The level of TrxR in the fat group was significantly lower than that in the normal group(P<0.05); The differences in the levels of Trx among the 3 groups were not significant(P>0.05). The activity of Trx in the emaciation group[(32.4±8.5)×10-3A·min-1·mg-1]was significantly higher than that in the normal group[(19.6±3.3)×10-3A·min-1·mg-1]and the fat group[(11.3±7.5)×10-3A·min-1·mg-1, all P<0.01]. The activity of Trx in the fat group was significantly lower than that in the normal group(P<0.05). The activity of TrxR in the emaciation group[(17.6±4.6)×10-3A·min-1·mg-1]was significantly higher than that in the fat group[(7.8±2.3)×10-3A·min-1·mg-1, P<0.01], but the TrxR activity of the 2 groups showed no significant difference as compared with the normal group(P>0.05). Conclusion: Both high BMI and low BMI can affect the oxidative stress of the body, resulting in increased oxidants and decreased antioxidants, and can cause damage to the lung tissue in the rat models.

Serum thioredoxin reductase is highly increased in mice with hepatocellular carcinoma and its activity is restrained by several mechanisms.

Increased thioredoxin reductase (TrxR) levels in serum were recently identified as possible prognostic markers for human prostate cancer or hepatocellular carcinoma. We had earlier shown that serum levels of TrxR protein are very low in healthy mice, but can in close correlation to alanine aminotransferase (ALT) increase more than 200-fold upon chemically induced liver damage. We also found that enzymatic TrxR activity in serum is counteracted by a yet unidentified oxidase activity in serum. In the present study we found that mice carrying H22 hepatocellular carcinoma tumors present highly increased levels of TrxR in serum, similarly to that reported in human patients. In this case ALT levels did not parallel those of TrxR. We also discovered here that the TrxR-antagonistic oxidase activity in serum is due to the presence of quiescin Q6 sulfhydryl oxidase 1 (QSOX1). We furthermore found that the chemotherapeutic agents cisplatin or auranofin, when given systemically to H22 tumor bearing mice, can further inhibit TrxR activities in serum. The TrxR serum activity was also inhibited by endogenous electrophilic inhibitors, found to increase in tumor-bearing mice and to include protoporphyrin IX (PpIX) and 4-hydroxynonenal (HNE). Thus, hepatocellular carcinoma triggers high levels of serum TrxR that are not paralleled by ALT, and TrxR enzyme activity in serum is counteracted by several different mechanisms. The physiological role of TrxR in serum, if any, as well as its potential value as a prognostic marker for tumor progression, needs to be studied further.

Tissue and plasma thioredoxin reductase expressions in patients with glioblastoma multiforme.

BACKGROUND AND STUDY AIMS: Thioredoxin reductase (TrxR) is a redox protein that is considered to play a role in tumor progression. The purpose of this study was to assess the expression of TrxR in blood and tumor samples of glioblastoma multiforme (GBM) patients. PATIENTS: TrxR levels were evaluated in blood and GBM tissues extracted from 27 patients, in normal brain tissues of 12 autopsy cases, and in blood samples of 12 healthy subjects. The results were compared between tumor and control groups. RESULTS: The mean level of TrxR in GBM tissues (74.5 ± 14.9 U/g wet tissue) was remarkably higher than in normal brain tissues (14.8 ± 3.4 U/g wet tissue). The mean TrxR levels in blood were significantly higher in GBM patients (296.3 ± 43.6 U/mL) than in the controls (203.0 ± 11.3 U/mL). CONCLUSIONS: These findings suggest that high levels of TrxR may be related to progression of GBM.

Selenium speciation in paired serum and cerebrospinal fluid samples.

Se speciation was performed in 24 individual paired serum and cerebrospinal fluid (CSF) samples from neurologically healthy persons. Strong anion exchange (SAX) separation, coupled to inductively coupled plasma-dynamic reaction cell-mass spectrometry (ICP-DRC-MS), was employed. Species identification was done by standard matched retention time, standard addition and by size exclusion chromatography followed from SAX (2-D SEC-SAX-ICP-DRC-MS) and by SAX followed from CE-ICP-DRC-MS (2-D SAX-CE-ICP-DRC-MS). Limit of detection (LoD, 3×standard deviation (SD) of noise) was in the range of 0.026-0.031 µg/L for all investigated species and thus was set uniformly to 0.032 µg/L. Quality control for total Se determination was performed by analysing control materials "human serum" and "urine", where determined values met target values. Several Se species were found in both sample types having following median values (sequence: serum/CSF, each in µg Se/L): total Se, 58.39/0.86; selenoprotein P (SePP), 5.19/0.47; Se-methionine (SeM), 0.23/ 65 µg/L; however, SePP(-CSF) appeared independent of SePP(-serum). For Se-HSA(-serum) versus (vs.) Se-HSA(-CSF), a weak linear relationship was found (r(2)=0.1722). On the contrary, for anti-oxidative Se-enzymes, higher r (2) values were calculated: GPx(-serum) vs. GPx(-CSF), r(2)=0.3837; TrxR(-serum) vs. TrxR(-CSF), r(2)=0.6293. Q(-Se-species) values (= ratios of CSF(-Se-species)/serum(-Se-species)) were compared with the Q (-Alb) value (HSA(-CSF)/HSA(-serum)=clinical index of NB integrity) for deeper information about NB passage of Se species. The Q (-Se-HSA) value (3.8×10(-3)) was in accordance to the molecular mass dependent restriction at NB (Q(-Alb) at 5.25×10(-3)). Increased Q values were seen for TrxR (21.3×10(-3)) and GPx (8.3×10(-3)) which are not (completely) explained by molecular size. For these two anti-oxidative Se-enzymes (GPx, TrxR), we hypothesize that there might be either a facilitated diffusion across NB or they might be additionally synthesized in the brain.

Blood thioredoxin reductase activity, oxidative stress and hematological parameters in painters and battery workers: relationship with lead and cadmium levels in blood.

Oxidative stress has been shown to be involved in lead and cadmium toxicity. We recently showed that the activity of the antioxidant enzyme thioredoxin reductase (TrxR) is increased in the kidneys of lead-exposed rats. The present study evaluated the blood cadmium and blood lead levels (BLLs) and their relationship with hematological and oxidative stress parameters, including blood TrxR activity in 50 painters, 23 battery workers and 36 control subjects. Erythrocyte δ-aminolevulinate dehydratase (δ-ALA-D) activity and its reactivation index were measured as biomarkers of lead effects. BLLs increased in painters, but were even higher in the battery workers group. In turn, blood cadmium levels increased only in the painters group, whose levels were higher than the recommended limit. δ-ALA-D activity was inhibited only in battery workers, whereas the δ-ALA-D reactivation index increased in both exposed groups; both parameters were correlated to BLLs (r = -0.59 and 0.84, P < 0.05), whereas the reactivation index was also correlated to blood cadmium levels (r = 0.27, P < 0.05). The changes in oxidative stress and hematological parameters were distinctively associated with either BLLs or blood cadmium levels, except glutathione-S-transferase activity, which was correlated with both lead (r = 0.34) and cadmium (r = 0.47; P < 0.05). However, TrxR activity did not correlate with any of the metals evaluated. In conclusion, blood TrxR activity does not seem to be a good parameter to evaluate oxidative stress in lead- and cadmium-exposed populations. However, lead-associated changes in biochemical and hematological parameters at low BLLs underlie the necessity of re-evaluating the recommended health-based limits in occupational exposure to this metal.

Antibody specific to thioredoxin reductase as a new biomarker for serodiagnosis of invasive aspergillosis in non-neutropenic patients.

BACKGROUND: Invasive aspergillosis (IA) is an important cause of mortality in critically ill patients, but the diagnosis is difficult as clinical and radiological signs are neither sensitive nor specific. Serum galactomannan (GM) is a useful marker for IA, but exhibits low sensitivity in non-neutropenic patients. In our previous work, strong antibody reactivity to thioredoxin reductase of Aspergillus fumigatus was found in non-neutropenic IA patients. METHODS AND RESULTS: Using recombinant thioredoxin reductase GliT (TR), an antigenic protein secreted by A. fumigatus, as the coating antigen, an enzyme-linked immunosorbent assay (ELISA) for detecting anti-TR antibodies was developed. The antibody response to TR in IA animal models and 42 non-neutropenic patients with culture- and/or histology-documented IA was investigated. The results showed that anti-TR antibody was detectable in rabbit serum 7-9 days after exposure to the fungus. The sensitivity and specificity of the anti-TR antibody assay in patients were 80.9% and 96%, respectively, while the sensitivity of GM in this group of patients was only 52.3%. The specificity of the assay was confirmed by testing the sera from patients infected with other pathogenic fungal species and bacteria.

Counteraction of oxidative damage in the rat liver by an ancient grain (Kamut brand khorasan wheat).

OBJECTIVE: We previously demonstrated in rat plasma the antioxidant protective effect of whole-grain bread, particularly when made from Kamut brand khorasan wheat. In the present study, we investigated the effects of the same experimental breads in rat liver using two different bread-making procedures (baker's yeast and sourdough fermentation). METHODS: Rats were examined in the basal condition and after the administration of doxorubicin, a pro-oxidative agent. The following parameters were measured in liver homogenates: glutathione peroxidase and thioredoxin reductase activities, as antioxidant enzymes containing selenium; glutathione, α-tocopherol and ß-carotene, as major non-enzymatic cell antioxidants; malondialdehyde and advanced oxidation protein products, as markers of oxidative damage to lipids and proteins, respectively. A histologic evaluation of liver tissue was also conducted. RESULTS: In agreement with our previous work, we observed a lower oxidative status and a different activity of glutathione peroxidase and thioredoxin reductase in rats fed the whole-grain Kamut khorasan bread than in rats fed the modern whole-grain durum wheat bread. Histologic evaluation of the hepatic tissue showed the onset of inflammation in response to doxorubicin only in rats fed the modern durum wheat bread. CONCLUSION: Our data confirm that bread made from whole-grain Kamut khorasan protects rats from oxidative stress better than bread made from whole-grain durum wheat. This is consistent with their different antioxidant profiles. The type of wheat used for bread-making appeared to be the main determinant of the observed protective effect.

Novel metabolic biomarkers related to sulfur-dependent detoxification pathways in autistic patients of Saudi Arabia.

BACKGROUND: Xenobiotics are neurotoxins that dramatically alter the health of the child. In addition, an inefficient detoxification system leads to oxidative stress, gut dysbiosis, and immune dysfunction. The consensus among physicians who treat autism with a biomedical approach is that those on the spectrum are burdened with oxidative stress and immune problems. In a trial to understand the role of detoxification in the etiology of autism, selected parameters related to sulfur-dependent detoxification mechanisms in plasma of autistic children from Saudi Arabia will be investigated compared to control subjects. METHODS: 20 males autistic children aged 3-15 years and 20 age and gender matching healthy children as control group were included in this study. Levels of reduced glutathione (GSH), total (GSH+GSSG), glutathione status (GSH/GSSG), glutathione reductase (GR), glutathione- s-transferase (GST), thioredoxin (Trx), thioredoxin reductase (TrxR) and peroxidoxins (Prxs I and III) were determined. RESULTS: Reduced glutathione, total glutathione, GSH/GSSG and activity levels of GST were significantly lower, GR shows non-significant differences, while, Trx, TrxR and both Prx I and III recorded a remarkably higher values in autistics compared to control subjects. CONCLUSION: The impaired glutathione status together with the elevated Trx and TrxR and the remarkable over expression of both Prx I and Prx III, could be used as diagnostic biomarkers of autism.

trans-Resveratrol downregulates Txnip overexpression occurring during liver ischemia-reperfusion.

Txnip (thioredoxin-interacting protein) is a protein with multifunctional roles in cellular responses and stress-related diseases. Txnip is involved in intracellular redox regulation and has been recently described as a possible link between redox state and metabolism. trans-Resveratrol (T-res) is a natural phytoalexin with antiproliferative, antiapoptotic and antioxidative effects. However, to date there have been no reports of the implication of Txnip in a model of liver acute stress such as ischemia-reperfusion (I/R) and no work has looked for a T-res effect on Txnip. Here we studied the effects of a post-ischemic treatment of T-res on the liver thioredoxin (Trx)/Txnip system and investigated whether the T-res effects were dependent on *NO production. In this work, liver I/R induced hepatic Txnip expression and T-res inhibited I/R Txnip expression. This decrease in Txnip expression by T-res was associated with an increase in liver Trx redox activity and a decrease in hepatic I/R-induced Trx-1 expression with no effect on Trx-2, on plasma Trx redox activity or on liver and plasma Trx reductase activity, independently of *NO production. In conclusion, these results show that in our model, not only did T-res protect Trx redox activity by diminishing the Txnip protein expression; it also reduced secretion of Trx1. This is the first report of a major implication of the Trx1/Txnip system in hepatic I/R injuries. It also affirms the importance of the antioxidant effect of T-res on the Trx1/Txnip system.

Decreased serum levels of thioredoxin in patients with coronary artery disease plus hyperhomocysteinemia is strongly associated with the disease severity.

OBJECTIVE: Elevation of homocysteine and thioredoxin (Trx) levels was found in some patients with coronary artery diseases (CAD). However, their correlations with CAD were not clear. Dysfunction of thioredoxin/thioredoxin reductase (TrxR) may cause oxidative stress that is common to CAD. We seek to determine the association among homocysteine, Trx/TrxR and CAD. METHODS: Serum samples were collected from 150 CAD patients under statin treatment and 122 non-CAD controls. Risk factors for atherosclerosis including homocysteine, lipids and glucose levels were analyzed. Trx/TrxR activities and protein levels were determined using super-insulin assay and Western blot, respectively. One-way ANOVA, Tukey's post hoc test and Spearman's rank correlation coefficient were used for statistical analysis. CAD severity was evaluated by angiographic Gensini score. RESULTS: Compared with non-CAD group, CAD group had significantly increased TrxR activity (P<0.05) and homocysteine levels (P<0.01), but not Trx activity. After further dividing CAD group using homocysteine below 15 microM as reference, Trx activity decreased significantly in CAD group with high homocysteine, and was inversely associated with homocysteine levels (r=-0.199, P<0.05) that was, however, weakly positively associated with TrxR activity. Neither lipids nor glucose significantly affected Trx/TrxR activity. Association of CAD severity with low Trx plus high homocysteine was strong (r=-0.458, P<0.001), but with high homocysteine alone was rather weak (r=0.125, P=0.225). CONCLUSION: In CAD patients, high homocysteine levels may cause low Trx activity, which is closely correlated to the extent and severity of CAD.

[Correlation of plasma thioredoxin reductase activity to growth of H22 hepatocellular carcinoma xenografts in Kunming mice].

BACKGROUND AND OBJECTIVE: The expression and activity of thioredoxin reductase (TrxR) are significantly higher in tumor tissues than in normal tissues, but the correlation of plasma TrxR activity to tumor growth has seldom been reported. This study was to evaluate the correlation of plasma TrxR activity to the growth of hepatocellular carcinoma (HCC) H22 cell xenografts in mice. METHODS: H22 cells were injected subcutaneously into Kunming mice to establish HCC model. The mice were divided into control group, mice group, low dose (36 mg/kg), moderate dose (72 mg/kg) and high dose (216 mg/kg) ethaselen groups. The mice in control group and model group were given 0.5% sodium carboxymethyl cellulose (CMC-Na). Blood samples were drawn before tumor cell inoculation, when tumor volume reached 100 mm3, and at Days 1, 4 and 10 of treatment. TrxR activity in plasma and tumor tissues was detected by dithio-bis-nitrobenzoic acid (DTNB) method. RESULTS: The inhibition rates of tumor growth were 59.5% in low dose ethaselen group, 74.3% in moderate dose ethaselen group, and 74.9% in high dose ethaselen group. Plasma TrxR activity was stable in control mice, and was correlated positively to tumor volume in tumor-bearing mice. At the end of treatment, the inhibition rates of TrxR activity in plasma and tumor were 59.2% and 15.3% in low dose ethaselen group, 68.4% and 25.8% in moderate dose ethaselen group, 68.9% and 29.8% in high dose ethaselen group. CONCLUSIONS: Plasma TrxR activity is correlated positively to tumor growth. Ethaselen can inhibit TrxR activity corresponding to tumor growth inhibition.

The gastrointestinal microbiota affects the selenium status and selenoprotein expression in mice.

Colonization of germ-free (GF) mice has been shown to induce the gastrointestinal form of the selenium-dependent glutathione peroxidases, GPx2. Since bacterial colonization of the gastrointestinal tract is associated with stress, we aimed to clarify how bacteria affect selenoprotein expression in unstressed conditions. GF and conventional (CV) FVB/NHan(TMHsd) mice were fed a selenium-poor (0.086 ppm) or a selenium-adequate (0.15 ppm) diet for 5 weeks starting from weaning. Each group consisted of five animals. Specific glutathione peroxidase (GPx) and thioredoxin reductase (TrxR) expression was measured in plasma, liver and intestinal sections by activity, protein and mRNA level as appropriate. Under selenium-adequate conditions, selenoprotein expression did not differ in GF and CV mice. Under selenium-limiting conditions, however, GF mice generally contained higher GPx and TrxR activities in the intestine and liver, higher GPx1 protein and RNA levels in the liver, higher GPx2 protein levels in the proximal and distal jejunum and colon and higher GPx1 and GPx2 RNA levels in the colon. In addition, higher selenium concentrations were estimated in plasma, liver and cecum. All differences were significant. It is concluded that bacteria may compete with the host for selenium when availability becomes limiting. A variable association with different microorganisms might influence the daily requirement of mice for selenium. Whether the microbiota also affects the human selenoprotein status appears worthy of investigation.

Hemolysate thioredoxin reductase and glutathione peroxidase activities correlate with serum selenium in a group of New Zealand men at high prostate cancer risk.

The study provides data relating serum selenium concentration to activities of 2 key selenoenzymes, hemolysate thioredoxin reductase (TR) and glutathione peroxidase (GPx), measured by spectrophotometry, in a group of men at high risk for prostate cancer. This trial enrolled 43 patients with elevated prostate-specific antigen but negative biopsy for prostate cancer. Such individuals have a high risk of developing prostate cancer in the succeeding 5 y. In the men with baseline serum selenium concentrations ranging from 0.74-1.62 micromol/L (59-128 microg/L), hemolysate TR (r = 0.359, P < 0.05) and GPx (r = 0.341, P < 0.05) activities increased with increasing serum selenium. Furthermore, after a run-in period of 1 mo, men participated in a randomized, double-blind, placebo-controlled selenium supplementation trial for 6 mo and received a placebo, or 200 or 400 microg of Se per day, in the form of a seleno yeast. This study is a subsidiary of an ongoing Phase III cancer chemoprevention trial and, as such, randomization groups have not yet been revealed. After 6 mo of being on trial and with an estimated 66% of the group being supplemented with seleno yeast, the TR activity of the group increased by 80% relative to baseline. In contrast, 6 mo of selenium supplementation did not affect GPx activity. This study presents, to our knowledge for the first time, both measurements of human hemolysate TR activity and its relation to serum selenium.

Relationship of body condition score and oxidant stress to tumor necrosis factor expression in dairy cattle.

The relationship between body condition score (BCS) with measures of oxidative status and TNF-alpha production was examined in 16 mid-lactation dairy cows. Cows were selected based on either a normal (2.5-2.7) or a high (> or =3.5) BCS using the standard five-point scaling system. The metabolic status of all cows was determined by plasma nonesterified fatty acid levels (NEFA). Plasma samples or white blood cell lysates also were analyzed for indices of oxidant stress and for the expression of TNF-alpha. Cows with a high BCS had significantly lower NEFA levels when compared to normal BCS cows and the over-conditioned animals were not in a state of negative energy balance. No significant changes in lipid hydroperoxide levels, glutathione peroxidase activity, or the ratio of reduced (GSH) to oxidized (GSSG) glutathione was detected with respect to BCS. However, high BCS cows did have a significantly lower overall antioxidant potential and reduced TrxR activities when compared with the normal BCS cows. Changes in the oxidative state of over-conditioned cows were accompanied by a significantly higher expression of TNF-alpha. Results from this study suggest that cows with a high BCS can experience oxidant stress in the absence of altered energy status. Increased TNF-alpha expression may be related to the pro-oxidant state of over-conditioned cows and possibly be a contributing factor to the enhanced susceptibility to disease in high BCS dairy cattle.

High redox thioredoxin but low thioredoxin reductase activities in the serum of patients with rheumatoid arthritis.

BACKGROUND: Thioredoxin (Trx)/thioredoxin reductase (TrxR) is a redox-active system induced by oxidative stress. We investigated its status as a function of RA disease activity. METHODS: 64 consecutive RA patients and 27 healthy subjects were enrolled in the study. Serum Trx protein levels were evaluated using an immunoassay and immunoblot, while redox Trx and TrxR activities and oxidative stress markers (carbonyl groups, thiols), were determined using spectrophotometric methods. RESULTS: Redox Trx activity and Trx protein concentrations were significantly higher in RA patients than in controls (redox Trx activity: 37.7+/-22.6 versus 21.1+/-7.9 ng/mL, p<0.01; Trx protein: 25.5+/-12.0 versus 12.3+/-5.1 ng/mL, p<0.0001). Redox Trx activity correlated with the DAS score (r=0.45, p=0.004) and with the tender joint count (r=0.49, p=0.002) whereas there was no correlation with Trx protein concentrations. Immunoblot analysis showed that circulating Trx was partially aggregated. TrxR activity was lower in the serum of RA patients than in healthy subjects (197+/-70 versus 263+/-56 U/L, p=0.002). TrxR activity was correlated with the DAS score (r=0.53, p<0.001) and with the tender joint count (r=0.36, p<0.01). There were no correlations between oxidative stress marker levels and redox Trx activity, Trx protein concentrations or TrxR activity. CONCLUSION: Redox Trx and TrxR activities correlated with the disease activity of RA patients consistent with the hypothesis that Trx/TrxR activities may contribute to disease activity in RA.