Effects of selenium on proliferation, interleukin-2 production and selenoprotein mRNA expression of normal and dexamethasone-treated porcine splenocytes

Hydroxy Selenomethionine Exert Different Protective Effects Against Dietary Oxidative Stress-Induced Inflammatory Responses in Spleen and Thymus of Pigs

Oxidative stress (OS) is widespread in animal husbandry, which causes edema in immune organs and suppresses immune function of animals. Selenium (Se) is an essential trace element involved in immune regulation and improves animals' immunity. In present study, growing and finishing pigs were used to determine the protective effects of the new organic Se (hydroxy selenomethionine, OH-SeMet) on dietary oxidative stress (DOS) induced inflammatory responses, and the corresponding response of selenotranscriptome in spleen and thymus. Forty castrated male pigs (25.0 ± 3.0 kg) were randomly grouped into 5 dietary treatments (n = 8) and fed on basal diet (formulated with normal corn and normal oils) or oxidized diet (formulated with aged corn and oxidized oils) supplied with 0.0, 0.3, 0.6, or 0.9 mg Se/kg OH-SeMet, after 16 weeks, the corresponding indicators were determined. Results showed that DOS moderately increased the spleen and thymus index, decreased the antioxidant capacity of serum, spleen and thymus, and increased the concentration of serum inflammatory cytokines (IL-6 and TNF-α). The inflammatory response in spleen and thymus under DOS were discrepancies, DOS increased the expression of inflammation-related gene (IFN-β and TNF-α) in thymus, while exhibited no impact on that of the spleen. Dietary OH-SeMet supplementation exhibited protective effects, which decreased the spleen and thymus index, improved the antioxidant capacity of serum, spleen and thymus, and decreased the serum IL-1β and IL-6 levels. Se supplementation exhibited limited impact on the inflammation-related genes in spleen, except decreased the mRNA expression of IL-8. On the contrary, Se supplementation showed more impact on that of the thymus, which decreased the mRNA expression of IL-8 and TNF-α, increased the expression of IFN-β, IL-6, IL-10, and MCP1. In addition, selenotranscriptome responsive to dietary Se levels in spleen and thymus were discrepancies. Se supplementation increased the mRNA expression of  the selenotranscriptome in thymus, while exhibited limited impact on that of in spleen. In conclusion, dietary OH-SeMet supplementation mitigates the DOS-induced immunological stress by increasing the antioxidant capacity and altering the expression of inflammation-related genes and selenotranscriptome in immune organs, and these response in spleen and thymus were discrepancies.

Effects of Selenomethionine on Cell Viability, Selenoprotein Expression and Antioxidant Function in Porcine Mammary Epithelial Cells

This study investigated the effects of selenomethionine (Se-Met) on the cell viability, selenoprotein expression, and antioxidant function of porcine mammary epithelial cells (pMECs) to reveal the underlying molecular mechanism of Se-Met on the lactation performance and antioxidant capacity of sows in vitro. The pMECs were used as an in vitro model and were treated with various concentrations of Se-Met (0, 0.5, 1, 2, and 4 μM). Cells were analyzed for cell viability, selenoprotein transcriptome, selenoprotein expression, and antioxidant enzyme activities. The results showed that, with increasing Se-Met concentrations, cell viability first increased and then decreased at 24, 48, or 72 h posttreatment with maximum values at 0.5-μM Se-Met. As the Se-Met concentrations increased, the mRNA expression of 17 selenoproteins first upregulated and then downregulated, with maximum values at 0.5-μM Se-Met. The 17 selenoproteins included SEPHS2, SELENOP, GPX1, GPX2, GPX3, GPX6, TXNRD1, SELENOK, SELENOW, DIO1, DIO2, DIO3, SELENOF, SELENOS, SELENOH, SELENOI, and SELENOT. Additionally, the protein expression levels of SEPHS2, SELENOP, GPX1, and TXNRD1 and the activities of glutathione peroxidase and thioredoxin were highest at 0.5-μM Se-Met. In conclusion, 0.5-μM Se-Met promotes cell viability partially by improving selenoprotein expression and antioxidant function in pMECs, which provides evidence for the potential ability of Se-Met to improve mammary gland health in sows.

Selenoproteins as regulators of T cell proliferation, differentiation, and metabolism

Selenium (Se) is an essential micronutrient that plays a key role in regulating the immune system. T cells are of particular interest due to their important role in promoting adaptive immunity against pathogens and cancer as well as regulating tolerance, all of which are influenced by dietary Se levels. The biological effects of Se are mainly exerted through the actions of the proteins into which it is inserted, i.e. selenoproteins. Thus, the roles that selenoproteins play in regulating T cell biology and molecular mechanisms involved have emerged as important areas of research for understanding how selenium affects immunity. Members of this diverse family of proteins exhibit a wide variety of functions within T cells that include regulating calcium flux induced by T cell receptor (TCR) engagement, shaping the redox tone of T cells before, during, and after activation, and linking TCR-induced activation to metabolic reprogramming required for T cell proliferation and differentiation. This review summarizes recent insights into the roles that selenoproteins play in these processes and their implications in understanding how Se may influence immunity.

Dysfunction of thioredoxin triggers inflammation through activation of autophagy in chicken cardiomyocytes

Thioredoxin (Txn) is a hydrogen carrier protein and exists widely in organism. Txn deficiency implicates cardiomyocytes injury has been proven. However, the exact mechanism remains unclear. To understand the mechanistic response of cardiomyocytes subsequent to Txn suppression, we established the model of Txn dysfunction by employing gene interference technology (siRNA) and Txn inhibitor (PX-12) in cardiomyocytes. We detected the ROS levels, inflammation factors, and key proteins in the autophagy and apoptosis. In addition, heat map was used for further analysis. Our results revealed that Txn dysfunction increased the release of ROS and induced activation of autophagy via upregulation of Becline-1, LC3-1, 2, which further regulated the inflammatory response, meanwhile, Txn silence inhibited apoptosis in chicken cardiomyocytes through Caspase-3 inhibition. Altogether we concluded that Txn-deficient chicken cardiomyocytes experienced autophagy, which caused severe inflammatory reactions and resulting in damage to cardiomyocytes.

Selenium alleviates lipopolysaccharide-induced endometritisviaregulating the recruitment of TLR4 into lipid rafts in mice

Selenium (Se) is an essential trace element for living organisms and plays diverse biological roles.

The hydroxy-analogue of selenomethionine alleviated lipopolysaccharide-induced inflammatory responses is associated with recover expression of several selenoprotein encoding genes in the spleens of Kunming mice

This study aimed to determine whether hydroxy-analogue of selenomethionine (HMSeBA) supplementation could alleviate LPS-induced immunological stress in mice. A total of 90 Kunming mice were randomly assigned into 5 groups. The CON-LPS and CON+LPS groups were fed basal diet (BD), the others were fed BD with different levels of HMSeBA (0.15, 0.30 and 0.45 mg Se per kg) for 4 weeks. Mice were injected with LPS (3 mg per kg BW) or the corresponding physiological saline at 14 d and 28 d. Plasma and spleens were collected at 28 d. The results showed that: (1) LPS injection decreased ADG of mice at the 3^rd week, and increased the concentration of IL-6 and TNF-α in plasma and the spleen index; (2) LPS injection induced immunological stress, up-regulated 8 inflammation-related genes and 3 selenoprotein encoding genes, and down-regulated 16 selenoprotein encoding genes in spleens; (3) compared with the CON+LPS group, HMSeBA supplementation increased ADG of mice at 3 weeks and GSH-Px activity in plasma and spleens, decreased spleen index and plasma IL-6 and TNF-α levels, down-regulated mRNA levels of COX-2, ICAM-1, TNF-α, IL-6, and MCP-1, and up-regulated IL-10 and iNOS in spleens. 0.30 mg Se per kg of HMSeBA exhibited the optimal protective effect; (4) HMSeBA supplementation modestly recovered the expression of 8 selenoprotein encoding genes in the spleens of the stressed mice. The results indicated that HMSeBA supplementation alleviated LPS-induced immunological stress accompanied up-regulation of a subset of selenoprotein encoding genes in spleens of mice.

This study aimed to determine whether hydroxy-analogue of selenomethionine (HMSeBA) supplementation could alleviate LPS-induced immunological stress in mice.

Selenium Pretreatment Alleviated LPS-Induced Immunological Stress Via Upregulation of Several Selenoprotein Encoding Genes in Murine RAW264.7 Cells

This study was conducted to profile selenoprotein encoding genes in mouse RAW264.7 cells upon lipopolysaccharide (LPS) challenge and integrate their roles into immunological regulation in response to selenium (Se) pretreatment. LPS was used to develop immunological stress in macrophages. Cells were pretreated with different levels of Se (0, 0.5, 1.0, 1.5, 2.0 μmol Se/L) for 2 h, followed by LPS (100 ng/mL) stimulation for another 3 h. The mRNA expression of 24 selenoprotein encoding genes and 9 inflammation-related genes were investigated. The results showed that LPS (100 ng/mL) effectively induced immunological stress in RAW264.7 cells with induced inflammation cytokines, IL-6 and TNF-α, mRNA expression, and cellular secretion. LPS increased (P < 0.05) mRNA profiles of 9 inflammation-related genes in cells, while short-time Se pretreatment modestly reversed (P < 0.05) the LPS-induced upregulation of 7 genes (COX-2, ICAM-1, IL-1β, IL-6, IL-10, iNOS, and MCP-1) and further increased (P < 0.05) expression of IFN-β and TNF-α in stressed cells. Meanwhile, LPS decreased (P < 0.05) mRNA levels of 18 selenoprotein encoding genes and upregulated mRNA levels of TXNRD1 and TXNRD3 in cells. Se pretreatment recovered (P < 0.05) expression of 3 selenoprotein encoding genes (GPX1, SELENOH, and SELENOW) in a dose-dependent manner and increased (P < 0.05) expression of another 5 selenoprotein encoding genes (SELENOK, SELENOM, SELENOS, SELENOT, and TXNRD2) only at a high level (2.0 μmol Se/L). Taken together, LPS-induced immunological stress in RAW264.7 cells accompanied with the global downregulation of selenoprotein encoding genes and Se pretreatment alleviated immunological stress via upregulation of a subset of selenoprotein encoding genes.

Protective effects of zymosan on heat stress-induced immunosuppression and apoptosis in dairy cows and peripheral blood mononuclear cells

Dairy cows exposed to heat stress (HS) show decreased performance and immunity, but increased heat shock protein expressions and apoptosis. Zymosan, an extract from yeast cell walls, has been shown to modulate immune responses and defense against oxidative stress. However, few literatures are available about the effects of zymosan on immune responses and other parameters of the dairy cows under HS. Here, both primary peripheral blood mononuclear cell (PBMC) and dairy cow models were established to assess the effects of zymosan on performance, immunity, heat shock protein, and apoptosis-related gene expressions of dairy cows under HS. In vitro study showed that proliferation, IL-2 production, and Bcl-2/Bax-α ratio of cow primary PBMC were reduced, whereas hsp70 mRNA and protein expressions, as well as Annexin V-bing, were increased when PBMCs were exposed to heat. In contrast, zymosan significantly reversed these above changes induced by the HS. In the in vivo study, 40 Holstein dairy cows were randomly selected and assigned into zymosan group (supplemental zymosan; n = 20) and control group (no supplemental zymosan; n = 20). The results showed that zymosan improved significantly the dry matter intake and milk yield, increased IgA, IL-2, and tumor necrosis factor-α (TNF-α) contents in sera, as well as hepatic Bcl-2/Bax-α ratio, but decreased respiration rate and hepatic hsp70 expressions in the dairy cows under HS. Taken together, zymosan could alleviate HS-induced immunosuppression and apoptosis and improve significantly the productive performance and immunity of dairy cows under HS.

Protective Role of Selenium in Immune-Relevant Cytokine and Immunoglobulin Production by Piglet Splenic Lymphocytes Exposed to Deoxynivalenol

Deoxynivalenol (DON) is a mycotoxin that causes immunosuppression, especially in swine. Selenium (Se) is essential for proper functioning of the immune system in animals. However, little is known about the effects of DON and Se on cytokine or immunoglobulin production in piglets. Here, we addressed this gap by examining piglet splenic lymphocyte responses in vitro. Cells were stimulated with concanavalin A, a T cell stimulatory lectin, in the absence or presence of DON (0.1, 0.2, 0.4, and 0.8 μg/mL), Se (Na₂SeO₃, 2 μM), or combinations of Se 2 μM and DON 0.1-0.8 μg/mL for 12, 24, or 48 h. At each time point, supernatants and cells were collected and the expression of cytokine and immunoglobulin protein and mRNA was examined. Compared with control and Se-alone treatments, DON exposure significantly and dose dependently decreased the expression levels of IL-2, IL-4, IL-6, IL-10, IFN-γ, IgG, and IgM mRNA and protein. By contrast, co-treatment with DON + Se significantly increased the mRNA and protein levels of all factors examined, except IL-4 and IL-6, compared with DON treatment alone. The results of this investigation demonstrate that Se has the potential to counteract DON-induced immunosuppression in piglets and is a promising treatment for DON-mediated toxicity.

Protective role of selenium in the activities of antioxidant enzymes in piglet splenic lymphocytes exposed to deoxynivalenol

We evaluated the effects of selenium (Se) on antioxidant enzymes of piglet splenic lymphocytes exposed to deoxynivalenol (DON). We measured cell viability, the activities of several antioxidant enzymes, and lactate dehydrogenase (LDH), as well as total antioxidant capacity (T-AOC) and the levels of malonaldehyde (MDA) and hydrogen peroxide (H₂O₂). We found that DON exposure increased the concentrations of LDH, MDA, and H₂O₂ in all experimental groups in a dose-dependent manner, while the concentrations of other antioxidant enzymes were decreased. In Se-pretreated DON-exposed cells, damage to antioxidant enzymes was reduced, especially in the lower-dose DON groups over longer exposure times. These results may indicate that in piglet splenic lymphocytes, Se can alleviate DON-induced damage to antioxidant enzymes by improving glutathione peroxidase activity. Se may function as a potential antioxidative agent to alleviate DON-induced oxidative stress.

Effects of Se on the Diversity of SelT Synthesis and Distribution in Different Smooth Muscle Tissues in Rats

Selenium (Se) is a nutritionally essential trace element associated with health and disease, including many muscle diseases. Selenoprotein T (SelT) has been identified as a member of the redoxin protein family that includes selenocysteine, localizing to the endoplasmic reticulum. The synthesis of selenoprotein is influenced by Se. However, there is currently no data concerning the pattern of SelT expression in smooth muscle tissues. To investigate the effects of dietary Se on the expression of SelT, 90 rats were randomly allocated into three groups: LG, NG, and HG. The LG group was fed a basal diet deficient in Se (containing 0.023 mg/kg Se); the NG and HG groups were fed Se-supplemented diets containing either 0.3 or 1.5 mg/kg Se, respectively, for 90 days. The smooth muscle of the esophagus, trachea, stomach, intestine, and blood vessels was collected when the rats were 90 days old. The Se content in the blood and tissues was examined. The messenger RNA (mRNA) of selenocysteine-tRNA([Ser]Sec) synthase (SecS), selenophosphate synthetase 1 (SPS1), selenophosphate synthetase 2 (SPS2), and SelT were examined using qPCR, and SelT protein was detected by Western blotting. The results indicated that Se had an effect on the mRNA levels of SecS, with little effect on those of SPS1 in smooth muscle tissues. SelT was expressed in the smooth muscle tissues of blood vessels, esophagus, bronchus, stomach, and intestine, and the transcription of the SelT was very sensitive to dietary Se. Thus, SelT may play a major role in the mechanisms underlying the biological activity of Se in smooth muscle tissues.