Naturally Oxidized Olive Oil Promotes Active Cutaneous Anaphylaxis and Th2 Cytokine Production.

The excessive ingestion of oxidized dietary oils may exacerbate some allergic diseases. We previously reported that oxidized olive oil exacerbates active cutaneous anaphylaxis (ACA), one of the immediate allergic reactions. This study was conducted to clarify the effects of oxidized olive oil on the T cell response during ACA. BALB/c female mice were orally administered naturally oxidized olive oil once every 2 d for 2 weeks after ovalbumin (OVA)/aluminum hydroxide gel sensitization, after which ACA was elicited by intracutaneous administration of OVA into the ear auricles. Compared with fresh olive oil, oxidized olive oil administration increased the antigen-specific immunoglobulin E (IgE) antibody titer 2 weeks after OVA-sensitization and vascular hyperpermeability increased due to ACA. In the oxidized olive oil-administered mice, the mRNA expression levels of T-helper 2 (Th2) cytokines, interleukin (IL)-4, -5, -6, and -10, in the lymph nodes increased, as did the proportion of cluster designation (CD)3+CD4+ cells in the spleen and lymph nodes. In CD3+CD4+ cells, the mRNA expression levels of IL-4 and GATA-binding protein 3 (GATA3), the master regulator of Th2, were higher in the oxidized olive oil-group. Antigen-stimulated specific IL-4 production was promoted in CD3+CD4+ cells of oxidized olive oil-administered mice. This suggests that oxidized olive oil exacerbates ACA by promoting Th2 dominance in immediate allergic diseases.

Seleno-L-Methionine Suppresses Immunoglobulin E-Mediated Allergic Response in RBL-2H3 Cells.

The effect of seleno-L-methionine (SeMet) on immunoglobulin (Ig) E-mediated allergic responses were investigated using rat basophilic leukemia RBL-2H3 cells. Cells were first treated with or without SeMet, sensitized with anti-dinitrophenyl IgE and stimulated with the antigen dinitrophenyl-human serum albumin, before the measurement of degranulation, calcium mobilization, mRNA expression and protein secretion of interleukin (IL)-4 and tumor necrosis factor (TNF)-α, and phosphorylation of spleen tyrosine kinase (Syk), Akt, and mitogen-activated protein kinases (MAPKs). The antigen-induced ß-hexosaminidase release, a degranulation marker, was significantly inhibited by SeMet treatment. SeMet also significantly suppressed antigen-induced calcium mobilization. Antigen-induced increases in the mRNA expression and protein secretion of IL-4 and TNF-α were both significantly attenuated by SeMet treatment. In addition, SeMet significantly suppressed antigen-induced phosphorylation of Syk, Akt, and MAPKs. These results demonstrate that SeMet suppresses antigen-induced degranulation, and mRNA expression and protein secretion of IL-4 and TNF-α, and inhibits antigen-induced mobilization of calcium and activation of Syk, Akt, and MAPKs. Our study provides valuable information that may be useful in the prevention and treatment of allergic diseases.

Glutathione-dependent cell cycle G1 arrest and apoptosis induction in human lung cancer A549 cells caused by methylseleninic acid: comparison with sodium selenite.

The aim of the present study was to clarify the mechanism underlying the inhibition of cell proliferation in human lung cancer A549 cells by selenium (Se) compounds. Methylseleninic acid (CH3SeO2H, abbreviated as MSA), a synthetic Se compound, is a direct precursor of active methylselenol (CH3SeH) and is considered to be one of beneficial agents for cancer prevention and therapy. Sodium selenite (Na2SeO3), an inorganic Se form, is utilized in clinical Se supplementation. MSA markedly inhibited the growth of A549 cells at a concentration of 2.5×10(-6) mol/L for 1 d. On Day 1, Na2SeO3 also inhibited A549 cell growth at the concentration of 7.5×10(-6) mol/L. These compounds induced cell cycle arrest at the G1 phase and apoptosis under the inhibitory condition. Reduced glutathione (GSH) is critical to MSA or Na2SeO3 metabolism. The depletion of intracellular GSH suppressed Na2SeO3-induced G1 arrest, but promoted Na2SeO3-induced apoptosis. Therefore, Na2SeO3 appears to have directly induced apoptosis. In contrast, the MSA-induced G1 arrest was ameliorated by a marked decrease in GSH content. Additionally, the depletion of GSH slightly suppressed MSA-induced apoptosis. The difference in inhibitory effects between MSA and Na2SeO3 may be due to this variation in GSH-related metabolism. After exposure of A549 cells to MSA, the GSH content was significantly decreased. These results indicate that because MSA-induced G1 arrest and apoptosis induction are enhanced by GSH, the maintenance of GSH is essential for the effective anticancer action of MSA in A549 cells.

Effect of selenite on T-cell mitogenesis: contribution of ROS production and apoptosis signal-regulating kinase 1.

Although supplementation with the selenocompound, sodium selenite has been shown to stimulate the concanavalin A-induced T-cell mitogenic response, the mechanisms responsible remain unclear. This study was conducted to evaluate the relationships between the induction of apoptosis, formation of tumor necrosis factor (TNF)-alpha and reactive oxygen species (ROS), activation of apoptosis signal-regulating kinase (ASK) 1 and the thioredoxin (Trx) system when mitogenesis was stimulated by selenite. TNF-alpha was dose-dependently released by mouse splenocytes treated with selenite, and apoptosis was induced when TNF-alpha was added at the indicated concentrations. However, supplementation with selenite at low concentrations inhibited the accumulation of ROS with the increased expression of Trx reductase 1 and induction of apoptosis in wild-type splenocytes, and also at high concentrations in Trx-1-transgenic mouse splenocytes. The suppression of apoptosis was accompanied by a decrease in the expression of phospho-ASK1. These results suggest that the stimulation of T-cell mitogenesis by selenite may be partly attributed to the inhibited accumulation of ROS due to a reduced Trx-1/TR1 system, the inactivation of ASK1, and the suppression of apoptosis.

Low-dose ethanol aggravates allergic dermatitis in mice.

Alcohol injures dendritic cells and suppresses cellular immunity, while some evidence indicates that drinking alcohol aggravates allergic asthma. This study investigated the effect of low doses of ethanol in enhancing allergic reactions in the skin of mice. Liquid food containing alcohol was administered to conventional NC/Nga mice to induce alcoholic hepatic steatosis, and spontaneous dermatitis was evaluated. BALB/c mice were administered approximately 1 g/kg body weight of ethanol by gavage, and contact hypersensitivity (CHS) or active cutaneous anaphylaxis (ACA) was induced. Spleens were collected 24 h after the elicitation of CHS and mRNA expressions of interferon (IFN)-γ, interleukin (IL)-4, IL-6, IL-10, and IL-18 were measured by quantitative RT-PCR. Alcohol-containing diet exaggerated spontaneous dermatitis in conventional NC/Nga mice and contact hypersensitivity in BALB/c mice. Ethanol administered by gavage for 5 days enhanced contact hypersensitivity in BALB/c mice. Ethanol administration with gavage also enhanced ACA of BALB/c mice. Ethanol did not affect mRNA expression of IFN-γ and IL-4, but did enhance IL-6, IL-10, and IL-18 mRNA expression. Histological evaluation revealed an absence of hepatic steatosis in mice administered ethanol by gavage for 5 days. In ethanol-administered mice, inflamed areas presented as lesions or a local extreme accumulation of mononuclear cells in the epidermis. These findings suggest that ethanol enhances the expression of inflammatory cytokines independently from T helper (Th)1/Th2 cytokine phenotypes, causing abnormalities in the epidermis resulting in exacerbated allergic reactivity.

Methylseleninic acid (MSA) inhibits 17ß-estradiol-induced cell growth in breast cancer T47D cells via enhancement of the antioxidative thioredoxin/ thioredoxin reductase system.

The purpose of this study was to clarify the cell growth inhibitory mechanism of human breast cancer cells caused by selenium (Se) compounds. In the presence of 17ß-estradiol (E(2)) at physiological concentrations, growth of estrogen receptor α (ERα)-positive T47D cells was markedly inhibited by 1 × 10(-6) mol/L methylseleninic acid (MSA) with no Se related toxicity.Under conditions where cell growth was inhibited, MSA decreased ERα mRNA levels and subsequent protein levels; further decreasing expression of estrogen-responsive finger protein (Efp) which is a target gene product of ERα and promotes G2/M progression of the cell cycle. Therefore, the decline in Efp expression is presumed to be involved in G2 arrest. Coincidentally, the antioxidative thioredoxin/ thioredoxin reductase (Trx/TrxR) system in cells was enhanced by the synergistic action of E(2) and MSA. It has been reported that ROS-induced oxidative stress enhanced ERα expression. E(2) increased production of intracellular ROS in T47D cells. Meanwhile, MSA significantly decreased E(2)-induced ROS accumulation. From these results, activation of the Trx/TrxR system induced by the coexistence of MSA and E(2) suppresses oxidative stress and decreases expression of ERα, and finally induces the growth arrest of T47D cells through disruption of ERα signaling.

Effects of selenium status and supplementary seleno-chemical sources on mouse T-cell mitogenesis.

Although selenium is thought to be essential for various immune responses, the excess supplementation may have an adverse effect on certain immunological functions. The present study was designed to determine the effective chemical forms of selenium and their optimal levels on T-cell mitogenesis with splenic cells from mice given a selenium-deficient diet for 8 weeks to avoid effects of cellular selenium sources. Although selenium in tissues, except for spleen and thymus, was almost depleted by feeding selenium-deficient diet, the lymphoid organs still contained low levels of selenium. Both activities of cellular glutathione peroxidase (cGPx) and thioredoxin reductase (TR) in liver and splenic cells showed a tendency to decrease by selenium deficiency. However, splenic cells were tolerant against decrease of the selenoenzyme activities, and TR was also more tolerant than cGPx. T-cell proliferation of the selenium-insufficient splenic cells induced by concanavalin A was increased by addition of Na2SeO3, Na2SeO4, Na2Se, seleno-DL-cystine, seleno-L-methionine and selenocystamine. Their promoting action was observed at levels lower than 0.1 micromol/L and was completely suppressed at the highest concentration (1 micromol/L), except for selenocystamine. Na2SeO3 was one of the efficient selenocompounds for the mitogenesis, which was concomitant with the significant induction of cGPx and TR. However, recovery of cGPx activity in the selenium-insufficient cells by supplementary Na2SeO3 was only partial,while TR activity was readily recovered from selenium deficiency. These results therefore indicate that only low levels of selenium is essential for T-cell mitogenesis even in selenium-insufficient splenic cells, and TR, which is readily recovered by Na2SeO3, may be the critical enzyme.

Cystathionine gamma-lyase contributes to selenomethionine detoxification and cytosolic glutathione peroxidase biosynthesis in mouse liver.

We earlier found that seleno-l-methionine (L-SeMet) as a food source of selenium (Se) is directly converted to methylselenol (CH3SeH), alpha-ketobutyrate, and ammonia by the mouse hepatic cystathionine gamma-lyase. The purpose of this study was to clarify the biological role of cystathionine gamma-lyase in Se detoxification and cytosolic glutathione peroxidase (cGPx) biosynthesis because another metabolic pathway to CH3SeH via seleno-l-cystathionine and seleno-l-cysteine (l-SeCyH) from l-SeMet has been shown by several enzymatic reactions. When mice were treated with either toxic doses of l-SeMet or a Se-deficient diet, the cystathionine gamma-lyase activity for l-SeMet was invariable, suggesting that this enzyme was effective in both detoxification and biotransformation of Se. Concerning Se biotransformation into cGPx, production of H2Se as the possible precursor was not observed by the in vitro reaction of the liver cytosol with CH3SeH. When l-SeMet was administered at the nutritional dose to mice fed a Se-deficient diet, levels of both cGPx mRNA and cGPx protein were significantly restored. This recovery was not comparatively suppressed by coadministration of periodate-oxidized adenosine, an inhibitor of S-adenosylhomocysteinase, where the conversion of l-SeMet to l-SeCyH is inhibited. However, the recovery was strongly suppressed when propargylglycine, an inhibitor of cystathionine gamma-lyase that catalyzes the alpha,gamma-elimination reaction of both l-SeMet and seleno-l-cystathionine, was treated. These results suggest that cystathionine gamma-lyase is a notable enzyme in SeMet metabolism and that CH3SeH produced by the enzymatic reaction is utilized for cGPx biosynthesis.

Identification of mouse selenomethionine alpha,gamma-elimination enzyme: cystathionine gamma-lyase catalyzes its reaction to generate methylselenol.

The purpose of this study was to identify the seleno-L-methionine (L-SeMet) alpha,gamma-elimination enzyme that catalyzes L-SeMet to generate methylselenol (CH3SeH), a notable intermediate for the metabolism of selenium compounds, in mammalian tissues. The enzyme purified from ICR mouse liver was separated by one-dimensional gel electrophoresis, and the specific band was subjected to in-gel trypsin digestion followed by matrix-assisted laser desorption/ionization-time-of-flight mass spectrometric analysis. In the peptide mass fingerprinting search, the mass numbers of 14 peptides produced by tryptic digestion of the enzyme were consistent with the theoretical mass numbers calculated from the amino acid sequence of murine cystathionine gamma-lyase (E.C. 4.4.1.1). The peptide sequence tags search was also performed to obtain the amino acid sequence data of five tryptic peptides. These peptides were significantly identical to the partial amino acid sequences of cystathionine gamma-lyase. This enzyme was clearly shown to catalyze the alpha,gamma-elimination reaction of L-cystathionine by the enzymological research. The Km value for the catalysis of L-cystathionine was 0.81 mM and Vmax was 0.0013 unit/mg protein. These results suggested that cystathionine gamma-lyase catalyzes L-SeMet to generate CH3SeH by its alpha,gamma-elimination reaction.

Purification and characterization of mouse hepatic enzyme that converts selenomethionine to methylselenol by its alpha,gamma-elimination.

The objective of this study was to purify and characterize a mouse hepatic enzyme that directly generates CH3SeH from seleno-l-methionine (l-SeMet) by the alpha,gamma-elimination reaction. The l-SeMet alpha,gamma-elimination enzyme was ubiquitous in tissues from ICR mice and the activity was relatively high in the large intestine, brain, and muscle, as well as the liver. Aging and sex of the mice did not have any significant influence on the activity in the liver. The enzyme was purified from the mouse liver by ammonium sulfate precipitation and four kinds of column chromatography. These procedures yielded a homogeneous enzyme, which was purified approx 1000-fold relative to mouse liver extract. Overall recovery was approx 8%. The purified enzyme had a molecular mass of approx 160 kDa with four identical subunits. The Km value of the enzyme for the catalysis of l-SeMet was 15.5 mM, and the Vmax was 0.29 units/mg protein. Pyridoxal 5'-phosphate (pyridoxal-P) was required as a cofactor because the holoenzyme could be resolved to the apoenzyme by incubation with hydroxylamine and reconstituted by addition of pyridoxal-P. The enzyme showed the optimum activity at around pH 8.0 and the highest activity at 50 degrees C; it catalyzed the alpha,gamma-elimination reactions of several analogs such as d,l-homocysteine and l-homoserine in addition to l-SeMet. This enzyme also catalyzed the alpha,beta-elimination reaction of Se-methylseleno-l-cysteine. However, l-methionine was inert. Therefore, the purified enzyme was different from the bacterial l-methionine gamma-lyase that metabolizes l-SeMet to CH3SeH, in terms of the substrate specificity. These results were the first identification of a mammalian enzyme that specifically catalyzes the alpha,gamma-elimination reaction of l-SeMet and immediately converts it to CH3SeH, an important metabolite of Se.