Oxidative stress induced by Se-deficient high-energy diet implicates neutrophil dysfunction via Nrf2 pathway suppression in swine

RELATIONSHIP BETWEEN SELENIUM NUTRITIONAL STATUS AND MARKERS OF LOW-GRADE CHRONIC INFLAMMATION IN OBESE WOMEN

Low-grade chronic inflammation is one of the main disorders that characterize adipose tissue dysfunction in obesity and is an important element in the pathogenesis of several comorbidities. In this context, selenium is an essential micronutrient that exerts important anti-inflammatory functions, and the role of selenium in controlling inflammation associated with obesity is not well defined. Thus, this study aimed to evaluate the relationship between markers of the nutritional status of selenium and low-grade chronic inflammation in obese women. This cross-sectional study included 81 women aged between 18 and 50 years, who were divided into two groups according to body mass index (BMI): the obesity group (n = 38) and normal weight group (n = 43). Selenium intake was assessed by 3-day diet records. The plasma, erythrocyte, and urinary selenium concentrations were determined using inductively coupled plasma optical emission spectrometry. The analysis of serum cytokines interleukin (IL)-8, IL-1β, IL-6, IL-10, and tumor necrosis factor alpha (TNFα) was performed using flow cytometry. The results of this study revealed that the obese women had higher dietary intake of selenium than eutrophic women. However, obese participants showed decreased selenium concentrations in plasma and erythrocytes, in parallel with increased concentrations of selenium in the urine. Regarding the inflammatory parameters, obese women exhibited higher concentrations of IL-6 and lower concentrations of the cytokines IL-8, IL-1β, and TNFα than eutrophic women. In the binary logistic regression analysis, erythrocyte selenium was considered an independent predictor of the serum concentrations of cytokine IL-8 in obese women, reflecting the anti-inflammatory action of this micronutrient.

Cognitive Healthy Aging in Mice: Boosting Memory by an Ergothioneine-Rich Hericium erinaceus Primordium Extract

Brain aging is a crucial risk factor for several neurodegenerative disorders and dementia. The most affected cognitive function is memory, worsening early during aging. Inflammation and oxidative stress are known to have a role in pathogenesis of cognitive impairments, and a link exists between aging/frailty and immunosenescence/inflammaging. Based on anti-aging properties, medicinal mushrooms represent a source to develop medicines and functional foods. In particular, Hericium erinaceus (He) displays several actions ranging from boosting the immune system to fighting senescence, due to its active ingredients/metabolites. Among these, Ergothioneine (ERGO) is known as the longevity vitamin. Currently, we demonstrated the efficacy of an ERGO-rich He primordium extract (He2) in preventing cognitive decline in a murine model of aging. We focused on recognition memory deterioration during aging, monitored through spontaneous behavioral tests assessing both memory components and frailty index. A parallel significant decrease in key markers of inflammation and oxidative stress, i.e., IL6, TGFβ1, GFAP, Nrf2, SOD1, COX2, NOS2, was revealed in the hippocampus by immunohistochemistry, accompanied by an enhancement of NMDAR1and mGluR2, crucially involved in glutamatergic neurotransmission. In summary, we disclosed a selective, preventive and neuroprotective effect of He2 on aged hippocampus, both on recognition memory as well on inflammation/oxidative stress/glutamate receptors expression.

Relationship between selenium status, selenoproteins and COVID-19 and other inflammatory diseases: A critical review

The antioxidant effects of selenium as a component of selenoproteins has been thought to modulate host immunity and viral pathogenesis. Accordingly, the association of low dietary selenium status with inflammatory and immunodeficiency has been reported in the literature; however, the causal role of selenium deficiency in chronic inflammatory diseases and viral infection is still undefined. The COVID-19, characterized by acute respiratory syndrome and caused by the novel coronavirus 2, SARS-CoV-2, has infected millions of individuals worldwide since late 2019. The severity and mortality from COVID-19 have been associated with several factor, including age, sex and selenium deficiency. However, available data on selenium status and COVID-19 are limited, and a possible causative role for selenium deficiency in COVID-19 severity has yet to be fully addressed. In this context, we review the relationship between selenium, selenoproteins, COVID-19, immune and inflammatory responses, viral infection, and aging. Regardless of the role of selenium in immune and inflammatory responses, we emphasize that selenium supplementation should be indicated after a selenium deficiency be detected, particularly, in view of the critical role played by selenoproteins in human health. In addition, the levels of selenium should be monitored after the start of supplementation and discontinued as soon as normal levels are reached. Periodic assessment of selenium levels after supplementation is a critical issue to avoid over production of toxic metabolites of selenide because under normal conditions, selenoproteins attain saturated expression levels that limits their potential deleterious metabolic effects.

Modulation of the Functional State of Mouse Neutrophils by Selenium Nanoparticles In Vivo

This study aimed to discover the immunomodulatory effect of selenium nanoparticles (SeNPs) on the functional state of neutrophils in vivo. Intraperitoneal injections of SeNPs (size 100 nm) 2.5 mg/kg/daily to BALB/c mice for a duration of 7-28 days led to the development of an inflammatory reaction, which was registered by a significant increase in the number of neutrophils released from the peritoneal cavity, as well as their activated state, without additional effects. At the same time, subcutaneous injections of the same SeNPs preparations at concentrations of 0.1, 0.5, and 2.5 mg/kg, on the contrary, modulated the functional state of neutrophils depending on the concentration and duration of SeNPs administration. With the use of fluorescence spectroscopy, chemiluminescence, biochemical methods, and PCR analysis, it was found that subcutaneous administration of SeNPs (0.1, 0.5, and 2.5 mg/kg) to mice for a short period of time (7-14 days) leads to modification of important neutrophil functions (adhesion, the number of migrating cells into the peritoneal cell cavity, ROS production, and NET formation). The obtained results indicated the immunostimulatory and antioxidant effects of SeNPs in vivo during short-term administration, while the most pronounced immunomodulatory effects of SeNPs were observed with the introduction of a low concentration of SeNPs (0.1 mg/kg). Increase in the administration time of SeNPs (0.1 mg/kg or 2.5 mg/kg) up to 28 days led to a decrease in the adhesive abilities of neutrophils and suppression of the expression of mRNA of adhesive molecules, as well as proteins involved in the generation of ROS, with the exception of NOX2; there was a tendency to suppress gene expression pro-inflammatory factors, which indicates the possible manifestation of immunosuppressive and anti-inflammatory effects of SeNPs during their long-term administration. Changes in the expression of selenoproteins also had features depending on the concentration and duration of the administered SeNPs. Selenoprotein P, selenoprotein M, selenoprotein S, selenoprotein K, and selenoprotein T were the most sensitive to the introduction of SeNPs into the mouse organism, which indicates their participation in maintaining the functional status of neutrophils, and possibly mediated the immunomodulatory effect of SeNPs.

A Mechanistic Link Between Selenium and Coronavirus Disease 2019 (COVID-19)

PURPOSE OF REVIEW

Coronavirus disease 2019 (COVID-19) is a rapidly emerging disease caused by a highly contagious virus called severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), and this disease has affected millions of people across the world and led to hundreds of thousands of deaths worldwide. Nutrition is a key factor related to this disease, and nutritional status may determine the risk and outcomes of SARS-CoV-2 infection. Selenium is one of the major trace elements required for redox functions and has significant roles in viral infections. The purpose of this review was to examine the current evidence on the role of selenium in COVID-19. We reviewed studies on selenium and COVID-19, and other relevant studies to understand how selenium status can modify the risk of SARS-CoV-2 infection, and how selenium status might affect a person post-infection.

RECENT FINDINGS

We found that oxidative stress is a characteristic feature of COVID-19 disease, which is linked with the immunopathological disorder observed in individuals with severe COVID-19. Selenium plays a key role in strengthening immunity, reducing oxidative stress, preventing viral infections and supporting critical illness. Moreover, selenium deficiency is related to oxidative stress and hyperinflammation seen in critical illness, and selenium deficiency is found to be associated with the severity of COVID-19 disease. Selenium supplementation at an appropriate dose may act as supportive therapy in COVID-19. Future studies in large cohorts of COVID-19 are warranted to verify the benefits of selenium supplementation for reducing risk and severity of COVID-19.

Roles of selenoprotein S in reactive oxygen species-dependent neutrophil extracellular trap formation induced by selenium-deficient arteritis

Selenium (Se) deficiency and poor plasma Se levels can cause cardiovascular diseases by decreasing selenoprotein levels. Neutrophil extracellular traps (NETs) may be the vicious cycle center of inflammation in vasculitis. Here, we show that Se deficiency induced arteritis mainly by reducing selenoprotein S (SelS), and promoted the progression of arteritis by regulating the recruitment of neutrophils and NET formation. Silencing SelS induced chicken arterial endothelial cells (PAECs) to secrete cytokines, and activated neutrophils to promote NET formation. Conversely, scavenging DNA-NETs promoted cytokine secretion in PAECs. The NET formation regulated by siSelS was dependent on a reactive oxygen species (ROS) burst. We also found that the PPAR pathway was a major mediator of NET formation induced by Se-deficient arteritis. Overall, our results reveal how Se deficiency regulates NET formation in the progression of arteritis and support silencing-SelS worsens arteritis.

The role of selenium in cell survival and its correlation with protective effects against cardiovascular disease: A literature review

Selenium is a trace element that provides protection against cellular damage and death. Previous research using several types of cells identified anti-oxidant, anti-inflammatory, and anti-apoptotic effects for selenium. One of the diseases related to selenium is cardiovascular disease, as low selenium intake has been linked to cardiomyopathy. However, the mechanism of the cardioprotective effects of selenium is not thoroughly understood. Several studies supported the possible effects of selenium on heart cell survival. In this review, we analyzed recent research (2015-2020) on the roles and mechanism of action of selenium in cell survival and its cardioprotective effects. Furthermore, the prevention of apoptosis through both intrinsic and extrinsic pathways is discussed in this review. Signalling pathways that regulate cell survival such as the p-AMPK, poly (ADP-ribose) polymerase-1, nuclear factor-erythroid 2-related factor-2, AKT/PI3K, and STAT pathways are involved in the protective effects of selenium. In addition, signaling pathways that affect heart cell survival include the AKT and STAT pathways. It also affects autophagy through the PPAR-γ pathway. These findings should facilitate further research on the cardioprotective effects of selenium.

Selenoprotein V protects against endoplasmic reticulum stress and oxidative injury induced by pro-oxidants

Selenoprotein V (SELENOV) contains a thioredoxin-like fold and a conserved CxxU motif with a potential redox function. This study was to assess its in vivo and in vitro roles and mechanisms in coping with different oxidant insults. In Experiment (Expt.)1, SELENOV knockout (KO) and wild type (WT) mice (male, 8-wk old) were given an ip injection of saline, diquat (DQ, 12.5 mg/kg), or N-acetyl-para-aminophenol (APAP, 300 mg/kg) (n = 10), and killed 5 h after the injection. In Expt. 2, primary hepatocytes of WT and KO were treated with DQ (0-0.75 mM) or APAP (0-6 mM) for 12 h. In Expt. 3, 293 T cells overexpressing Selenov gene (OE) were treated with APAP (0-4 mM) for 24 h or H₂O₂ (0-0.4 mM) for 12 h. Compared with the WT, the DQ- and APAP-injected KO mice had higher (P < 0.05) serum alanine aminotransferase activities and hepatic malondialdehyde (MDA), protein carbonyl, endoplasmic reticulum (ER) stress-related proteins (BIP and CHOP), apoptosis-related proteins (FAK and caspase-9), and 3-nitrotyrosine, along with lower total anti-oxidizing-capability (T-AOC) and severer hepatic necrosis. Likewise, the DQ and APAP-treated KO hepatocytes had elevated (P < 0.05) cell death (10-40%), decreased (P < 0.05) T-AOC (63-83%), glutathione (26-87%), superoxide dismutase (SOD) activity (28-36%), mRNA levels of redox enzymes (Cat, Gcs, Gpx3, and Sod) and (or) sharper declines (P < 0.05) in cellular respiration and ATP production than that of the WT cells. In contrast, the OE cells had greater viability and T-AOC and lower MDA, and carbonyl contents after the APAP and H₂O₂ exposures (all at P < 0.05) than the controls. Moreover, the OE cells had greater (P < 0.05) redox enzyme activities (GPX, TrxR, and SOD), and lower (P < 0.05) expressions of ER stress-related genes (Atf4, Atf6, Bip, Xbp1t, Xbp1s, and Chop) and proteins (BIP, CHOP, FAK, and caspase-9) than the control cells after the treatment of H₂O₂ (0.4 mM). In conclusion, SELENOV conferred protections in vivo and in vitro against the reactive oxygen and nitrogen species-mediated ER stress-related signaling and oxidative injuries.

Melatonin-Nrf2 Signaling Activates Peroxisomal Activities in Porcine Cumulus Cell-Oocyte Complexes

Melatonin and Nrf2 signaling synergistically improve mammalian oocyte maturation and embryonic development. Furthermore, previous studies have suggested an interplay between peroxisomes and Nrf2 signaling in cells, but it is still unclear whether peroxisomes are involved in oocyte maturation. The aim of the present study was to identify the possible roles of peroxisomes in the melatonin-Nrf2 signaling pathway during in vitro maturation (IVM) of porcine oocytes. Porcine oocytes were treated with melatonin (10^-9 M) and brusatol, a Nrf2 specific inhibitor, in order to investigate the mechanism. Then, the rates of maturation and related gene and protein expression were analyzed. During oocyte maturation, melatonin upregulated the expression of gene and protein related to Nrf2 signaling and peroxisomal activities; RNA sequencing partially validated these results. Our results demonstrate that melatonin can activate Nrf2 signaling by binding to melatonin receptor 2, resulting in the upregulation of catalase. Moreover, peroxisomes were also found to be activated in response to melatonin treatment, causing the activation of catalase; together with Nrf2 signaling, peroxisomes synergistically prevented the generation of reactive oxygen species and enhanced oocyte quality. Thus, we suggest that a crosstalk might exist between Nrf2 signaling and peroxisomal activities in porcine oocytes.

MiR-1696/GPx3 axis is involved in oxidative stress mediated neutrophil extracellular traps inhibition in chicken neutrophils

As an important immune mechanism of neutrophils, the release of Web-like chromatin structures known as neutrophil extracellular traps (NETs) can rapidly locate and capture invading pathogens, which has received sustained attention. There are still some fundamental questions surrounding established studies on the mechanism of balance between reactive oxygen species (ROS) dependent release and neutrophil antioxidant response. Glutathione peroxidase 3 (GPx3) is an important antioxidant protein and has been identified can regulate the immune response. However, the effect of GPx3 on the NETs formation and microRNA in this process remain poorly understood. In the present study, we used chicken peripheral blood neutrophils treated with Phorbol-12-myristate-13-acetate (PMA) for 3 h as NETs formation model. The result of morphological observation showed that GPx3 inactivation compromised the release of NETs. Further analysis revealed that knockdown of GPx3 significantly disturbed oxidative balance by inhibiting antioxidant enzymes activity and increasing H₂ O₂ content. Quantitative analysis of NETs-related genes found that the phosphorylation level of mitogen-activated protein kinase (MAPK) pathway genes (ERK, JNK, and p38) and expression of phosphoinositide-3-kinase (PI3K)/AKT pathway genes (PI3K and AKT) were suppressed with the downregulation of GPx3. Meanwhile, we identified that miR-1696 can target GPx3 expression by using dual luciferase reporter system. Additionally, overexpression of miR-1696 can not only inhibit the formation of NETs by restraining the expression of GPx3, interfering with the generation of ROS and activation of the MAPK and PI3K/AKT pathways, but also reducing the release of PMA-induced NETs promoted by overexpression of GPx3. These results provide evidence that miR-1696 targeted GPx3 activities in neutrophils could be used to regulate the NETs formation stimulated by PMA.

l-Arginine supplementation of gilts during early gestation modulates energy sensitive pathways in pig conceptuses

Dietary l-arginine (ARG) supplementation has been studied as a nutritional strategy to improve reproductive performance of pregnant sows, since arginine is a conditionally essential amino acid. However, reports addressing the molecular mechanisms that mediate supplementation effects on embryos and fetuses development are still scarce. Therefore, we aimed to evaluate the effects of 1.0% ARG supplementation of commercial pregnant gilts on genes and proteins from energy metabolism and antioxidant defense pathways in embryos and fetuses. We also analyzed the global transcriptome profile of 25- and 35-day-old conceptuses. At Day 25, we observed a lower abundance of phospho-AMP-activated protein kinase (phospho-AMPK) protein and downregulation of oxidative phosphorylation system genes in ARG embryos. On the other hand, ARG fetuses showed greater expression of MLST8 and lower expression of MTOR genes, in addition to lower abundance of phospho-AMPK and phospho-mammalian target of rapamycin (phospho-mTOR) proteins. Transcriptome analysis at Day 35 did not present differentially expressed genes. For the antioxidant defense pathway, no differences were found between CON and ARG conceptuses, only trends. In general, supplementation of gilts with 1.0% ARG during early gestation affects energy sensitive pathways in 25- and 35-day conceptuses; however, no effects of supplementation were found on the antioxidative defense pathway in 25-day embryos.

Selenium deficiency induced necroptosis, Th1/Th2 imbalance, and inflammatory responses in swine ileum

Selenium (Se) deficiency has a significant impact on the swine breeding industry by inducing digestive system damage and diarrhea. However, the molecular mechanism remains unclear. Our objectives were to investigate if different amounts of necroptosis, inflammatory responses, and T helper cell 1/T helper cell 2 (Th1/Th2) imbalances were induced by Se deficiency in intestinal porcine jejunal epithelial cells (IPEC-J2) and swine ileum tissue. Therefore, Se-deficient models were successfully established both in vitro and in vivo. In the current study, the cell morphological observation results showed that Se deficiency seriously affected the growth and differentiation of IPEC-J2 cells. Moreover, the necroptosis staining and histomorphology observation results showed that the number of necroptotic cells increased significantly, and the ileal tissue exhibited abnormal structures, including necroptotic features and inflammatory cell infiltration, in the Se-deficient group. Furthermore, Se deficiency resulted in accelerated cell necroptosis by increasing (p < .05) the expression of genes related to the tumor necrosis factor-α pathway at both the protein and messenger RNA (mRNA) levels compared to the control group. Moreover, the relative mRNA and protein expression of the inflammatory genes and their responses to dietary Se deficiency were consistent with the resultant Th1/Th2 imbalances in vitro and in vivo. Taken together, the results suggested that Se deficiency caused necroptosis, inflammatory responses, and abnormal expression of cytokines in swine ileum tissue. These findings might help us to explain the damage induced by Se deficiency to the digestive system of swine.

The role of necroptosis and apoptosis through the oxidative stress pathway in the liver of selenium-deficient swine

Necroptosis is regarded as a new paradigm of cell death that plays a key role in the liver damage observed with selenium (Se) deficiency.

The association between plasma selenium and chronic kidney disease related to lead, cadmium and arsenic exposure in a Taiwanese population

This study aimed to determine the interaction of red blood cell cadmium and lead, total urinary arsenic, and plasma selenium in chronic kidney disease (CKD). We recruited 220 CKD patients as well as 438 gender- and age-matched controls, and we defined CKD as <60 mL/min/1.73 m² estimated glomerular filtration rate (eGFR) for three or more consecutive months. Plasma selenium and red blood cell cadmium and lead concentrations were measured by ICP-MS. Urinary arsenic species were determined via HPLC-HG-AAS and were summed to determine the total urinary arsenic concentration. Plasma selenium was positively correlated to eGFR, and subjects with high plasma selenium levels (>243.90 μg/L) had a significantly lower odds ratio (OR) and 95% confidence interval (CI) (0.23, 0.13-0.42) for CKD compared to those with low plasma selenium levels (≤ 196.70 μg/L). High plasma selenium and low red blood cell cadmium or lead concentrations interacted to decrease the OR and 95% CI for CKD (0.12, 0.06-0.26; 0.09, 0.04-0.19). High plasma selenium and low red blood cell lead levels also interacted to increase the eGFR (20.70, 15.56-26.01 mL/min/1.73 m²). This study is the first to suggest that selenium modifies the eGFR and OR in CKD induced by environmental toxicants.

[Selenium compounds in redox regulation of inflammation and apoptosis]

Monocytes and macrophages play a key role in the development of inflammation: under the action of lipopolysaccharides (LPS), absorbed from the intestine, monocytes and macrophages form reactive oxygen species (ROS) and cytokines, this leads to the development of oxidative stress, inflammation and/or apoptosis in all types of tissues. In the cells LPS induce an "internal" TLR4-mediated MAP-kinase inflammatory signaling pathway and cytokines through the superfamily of tumor necrosis factor receptor (TNFR) and the "death domain" (DD) initiate an "external" caspase apoptosis cascade or necrosis activation that causes necroptosis. Many of the proteins involved in intracellular signaling cascades (MYD88, ASK1, IKKa/b, NF-kB, AP-1) are redox-sensitive and their activity is regulated by antioxidants thioredoxin, glutaredoxin, nitroredoxin, and glutathione. Oxidation of these signaling proteins induced by ROS enhances the development of inflammation and apoptosis, and their reduction with antioxidants, on the contrary, stabilizes the signaling cascades speed, preventing the vicious circle of oxidative stress, inflammation and apoptosis that follows it. Antioxidant (AO) enzymes thioredoxin reductase (TRXR), glutaredoxin reductase (GLRXR), glutathione reductase (GR) are required for reduction of non-enzymatic antioxidants (thioredoxin, glutaredoxin, nitroredoxin, glutathione), and AO enzymes (SOD, catalase, GPX) are required for ROS deactivation. The key AO enzymes (TRXR and GPX) are selenium-dependent; therefore selenium deficiency leads to a decrease in the body's antioxidant defense, the development of oxidative stress, inflammation, and/or apoptosis in various cell types. Nrf2-Keap1 signaling pathway activated by selenium deficiency and/or oxidative stress is necessary to restore redox homeostasis in the cell. In addition, expression of some genes is changed with selenium deficiency. Consequently, growth and proliferation of cells, their movement, development, death, and survival, as well as the interaction between cells, the redox regulation of intracellular signaling cascades of inflammation and apoptosis, depend on the selenium status of the body. Prophylactic administration of selenium-containing preparations (natural and synthetic (organic and inorganic)) is able to normalize the activity of AO enzymes and the general status of the body. Organic selenium compounds have a high bioavailability and, depending on their concentration, can act both as selenium donors to prevent selenium deficiency and as antitumor drugs due to their toxicity and participation in the regulation of signaling pathways of apoptosis. Known selenorganic compounds diphenyldiselenide and ethaselen share similarity with the Russian organo selenium compound, diacetophenonylselenide (DAPS-25), which serves as a source of bioavailable selenium, exhibits a wide range of biological activity, including antioxidant activity, that governs cell redox balance, inflammation and apoptosis regulation.

Selenium-Yeast Alleviated Inflammatory Damage Caused by Lead via Inhibiting Ras/ERK Pathway and Inflammatory Factors in Chicken Skeletal Muscles

The aim of this study was to investigate the ameliorative effects of selenium-enriched yeast (Se-yeast) on the inflammatory damage induced by lead (Pb) in chicken skeletal muscles. A total of 108 1-day-old broiler chickens were randomly allocated into four groups (n = 27/group): the control group (C group), the Se-yeast-supplemented group (Se group), the lead-treated group (Pb group), and finally the Se- and Pb-combined group (Pb/Se group). The C group was fed with a basic diet comprising 0.049 mg/kg Se and 0.1 mg/kg Pb while the Se group was fed a Se-yeast diet containing 0.30 mg/kg Se and 0.1 mg/kg Pb. Similarly, the Pb group was fed a Pb acetate diet containing 0.049 mg/kg Se and 350 mg/kg Pb while the Pb/Se group was fed with a Se-yeast diet containing 0.30 mg/kg Se and 350 mg/kg Pb. On days 7, 21, and 35 after commencing the experiment, nine chicks belonging to each group were euthanized and the samples were analyzed by employing the techniques of inductively coupled plasma mass spectrometry and real-time quantitative PCR, along with Western blotting. The results indicated that excess Pb increased the nitric oxide concentration, enhanced the activity of inducible nitric oxide synthase (iNOS), and the mRNA levels of interleukin 1β (IL-1β), interleukin 4 (IL-4), interleukin 10 (IL-10), and interferon gamma (IFN-γ) in a time-dependent manner. Further, it was found that Se reduced damage caused by Pb by decreasing the expression of inflammatory factors in chicken skeletal muscles. Taken together, the results from this study provide the theoretical basis for an alleviate effect of Se on Pb-induced inflammatory damage in chicken skeletal muscles, mediated by inhibiting the Ras/extracellular signal-regulated kinase (ERK) pathway and the inflammatory factors.

Effect of Low-Selenium/High-Fat Diet on Pig Peripheral Blood Lymphocytes: Perspectives from Selenoproteins, Heat Shock Proteins, and Cytokines

The aim of the present study was to clarify the effect of low selenium (Se)/high fat on the mRNA expression of selenoproteins, heat shock proteins (HSPs) and cytokines in pig peripheral blood lymphocytes. Forty crossbred boar piglets with healthy lean body weights of 10 kg were randomly divided into four treatment groups (group C, group L-Se, group H-fat, and group L-Se-H-fat) (n = 10/group) and fed with the corresponding diet for 16 weeks. The pig peripheral blood lymphocytes were extracted, and the mRNA expression of selenoproteins, HSPs, and cytokines was measured. Most mRNA levels for selenoproteins decreased in group L-Se, group H-fat, and group L-Se-H-fat, except Gpx1, Gpx2, Selt, and Selm, which were elevated in group H-fat. At the same time, low-Se/high-fat diet increased the expression of HSPs (HSP40, HSP60, HSP70, and HSP90) and inflammatory cytokines (IL-1α, IL-1β, IL-6, IL-8, IL-9, iNOS, COX-2, NF-κB, and TNF-α) in group L-Se, group H-fat, and group L-Se-H-fat, and genes in group L-Se-H-fat showed greater increases. Also, low-Se/high-fat diet inhibits the expression of TGF-β1 and IFN-γ. In summary, a low-Se/high-fat diet can cause relevant selenoprotein expression changes and promote the expression of pro-inflammatory factors and HSPs, and low Se enhances the expression of HSPs and inflammation factors induced by high fat. This information is helpful for understanding the effects of low-Se and high-fat diet on pig peripheral blood lymphocytes.

Lower Selenoprotein T Expression and Immune Response in the Immune Organs of Broilers with Exudative Diathesis Due to Selenium Deficiency

The objective of the present study was to investigate whether dietary selenium (Se) deficiency would affect the expression of selenoprotein T (SelT) and immune response in the immune organs of broilers. Changes in expression of inflammatory cytokines and oxidative stress response caused by Se deficiency can lead to organism damage, which in turn leads to immune response. Sixty (1-day-old) broilers were divided into the control group and Se-deficiency group. Animal models with exudative diathesis were duplicated in the broilers by feeding them Se-deficient diet for 20 days. After the Se-deficient group exhibited symptoms of exudative diathesis, all the broilers were euthanized, and their immune organs were taken for analysis. The tissues including spleen, bursa of Fabricius, and thymus were treated to determine the pathological changes (including microscopic and ultramicroscopic), the messenger RNA (mRNA) expression levels of SelT and its synthetase (SecS and SPS1), cytokine mRNA expression levels, and antioxidant status. The microscopic and ultramicroscopic analyses showed that immune tissues were obviously injured in the Se-deficient group. The mRNA expression of SelT was decreased compared with that in the control group. Meanwhile, the mRNA expression levels of SecS and SPS1 were downregulated. In the Se-deficient group, the mRNA expression levels of IL-1R and IL-1β were higher than those of three control organs. Additionally, the IL-2 and INF-γ mRNA expression levels were lower than those of the control group. The activity of CAT was decreased, and the contents of H₂O₂ and •OH were increased due to Se deficiency. Pearson method analysis showed that the expression of SelT had a positive correlation with IL-2, INF-γ, SecS, and SPS1 and a negative correlation with IL-1R and IL-1β. In summary, these data indicated that Se-deficient diet decreased the SelT expression and its regulation of oxidative stress, and it inhibited a pleiotropic mechanism of the immune response.

Antagonistic effects of selenium on lead-induced autophagy by influencing mitochondrial dynamics in the spleen of chickens

Lead (Pb) may damage the immune function in human and animal. Selenium (Se) has antagonistic effects on Pb. In our study, brown layer chickens were randomly allocated to control group, Se group (1 mg/kg Se), Se+Pb group (1 mg/kg Se and 350 mg/kg Pb), and Pb group (350 mg/kg Pb). The chickens were sacrificed on the 90^th day; spleen tissues were subjected to observation of ultrastructure and detection of spleen-related indexes. The results revealed that in the Pb group, expression levels of the cytokines IL-1 and TNF-α significantly increased, and expression levels of IL-2 and INF-γ significantly decreased; activities of antioxidant enzyme GPX, SOD and CAT significantly decreased, and expression level of malondialdehyde (MDA) significantly increased; expression levels of mitochondrial fission-related genes (Mff and Drp1) significantly increased, and expression levels of mitochondrial fusion-related genes (Opa1, Mfn1 and Mfn2) significantly decreased; expression of autophagy-related genes (Beclin 1, Dynein, Atg 5, LC3-I and LC-II) was upregulated, while expression of mammalian target of rapamycin (mTOR) was downregulated. The results of transmission electron microscopy indicated that Pb induced mitochondrial fragmentation, and triggered autophagy in the spleen of chickens. The Se and Pb co-treatment remarkably alleviated these injuries induced by Pb in the spleen of chickens. In conclusion, Pb can induce the oxidative stress to influence the mitochondrial dynamics balance and lead to autophagy, which triggers the immune dysfunction in the spleen of chickens; the Se exhibits the antagonistic effects on lead-induced autophagy by influencing mitochondrial dynamics in the spleen of chickens.

The Antagonistic Effect of Selenium on Cadmium-Induced Damage and mRNA Levels of Selenoprotein Genes and Inflammatory Factors in Chicken Kidney Tissue

Selenium (Se) is a necessary trace mineral in the diet of humans and animals. Cadmium (Cd) is a toxic heavy metal that can damage animal organs, especially the kidneys. Antagonistic interactions between Se and Cd have been reported in previous studies. However, little is known about the effects of Se against Cd toxicity and on the mRNA levels of 25 selenoprotein genes and inflammatory factors in chicken kidneys. In the current study, we fed chickens with a Se-treated, Cd-treated, or Se/Cd treated diet for 90 days. We then analyzed the mRNA expression of inflammatory factors (including prostaglandin E synthase (PTGES), nuclear factor-kappa B (NF-κB), tumor necrosis factor-α (TNF-α), and cyclooxygenase-2 (COX-2)) and 25 selenoprotein genes (Gpx1, Gpx2, Gpx3, Gpx4, Txnrd1, Txnrd2, Txnrd3, Dio1, Dio2, Dio3, SPS2, Sepp1, SelPb, Sep15, Selh, Seli, Selm, Selo, Sels, Sepx1, Selu, Selk, Selw, Seln, Selt). The results demonstrated that Cd exposure increased the Cd content in the chicken kidneys, renal tubular epithelial cells underwent denaturation and necrosis, and the tubules became narrow or disappeared. However, Se supplementation reduced the Cd content in chicken kidneys and induced normal development of renal tubular epithelial cells. In addition, we also observed that Se alleviated the Cd-induced increase in the mRNA levels of inflammatory factors and ameliorated the Cd-induced downtrend in the mRNA levels of 25 selenoprotein genes in chicken kidneys.

Regulation of autophagy factors by oxidative stress and cardiac enzymes imbalance during arsenic or/and copper induced cardiotoxicity in Gallus gallus

Basal autophagy has an indispensable role in the functioning and maintenance of cardiac geometry under physiological conditions. Recently, increasing evidence has demonstrated that arsenic (As)/copper (Cu) play important roles in the autophagy of the heart. The current study was to evaluate whether oxidative damage by As or/and Cu was correlated with autophagy through the phosphatidylinositol 3-kinase (PI3K)/protein kinase B (AKT)/mammalian target of rapamycin (mTOR) pathway in the heart of birds. Arsenic trioxide (30mg/kg) or/and cupric sulfate (300mg/kg) were administered in a basal diet to male Hy-line chickens (one-day-old) for 12 weeks. The results showed that heart weight/body weight ratio decreased in the As + Cu group only at 4, 8 and 12 weeks. Moreover, we observed that As or/and Cu decreased high-density lipoprotein cholesterol (HDL-C) concentrations, increased total cholesterol (T-CHO) concentrations and cardiac enzymes activities in the serum. On the other hand, As or/and Cu significantly reduced the activities of total antioxidant (T-AOC), superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSH-Px)) along with decreased nonenzymic antioxidant (glutathione (GSH)) concentrations and increased malondialdehyde (MDA) concentrations in the heart. Furthermore, As or/and Cu could induce autophagy in the heart of chickens through decreased mRNA levels of TORC1, TORC2, microtubule associated light chains 3-I (LC3-I) and increased PI3K, AKT1, Beclin1, autophagy associated gene 4B (Atg4B), microtubule associated light chains 3-II (LC3-II), autophagy associated gene 5 (Atg5) and Dynein. Meanwhile, ultrastructural examinations showed that As/Cu could result in the appearance of autolygosomes, autophagic vacuoles and double-membrane structures in the heart. In conclusion, As or/and Cu induced cardiac damage and autophagy via elevating cardiac enzymes activities, inducing oxidative stress and activating the PI3K/AKT/mTORC pathway in heart of chickens. Moreover, As and Cu had a possible synergistic relationship in the heart of chickens.

Selenium Supplementation Changes the Ion Profile in the Pancreas of Chickens Treated with Cadmium

Increasing evidence indicates that selenium (Se) could antagonize metal toxicity, including cadmium (Cd) toxicity. However, the effects of Se on Cd-induced changes in the ion profile in the pancreas of chickens have not been reported. In the present study, 128 Hy-Line brown laying chickens were divided into the control group, Se-treated group, Se/Cd-treated group, and Cd-treated group, and we detected the concentrations of 28 ions in the four groups by inductively coupled plasma mass spectrometry. In the Cd-treated group, the accumulation of Cd in the pancreas was 836.8 times higher that than in the control group (27,353.71 ppb/32.69 ppb). Meanwhile, the Ca, Ti, Fe, Mo, Li, Al, and Pb levels increased and the Cr, Mn, Ni, Cu, Zn, Se, Sr, and Sb levels decreased due to sub-chronic Cd poisoning. The Fe, Mo, Ba, and Pb levels decreased in the Se/Cd-treated group. Our findings suggest that Cd can accumulate in the chicken pancreas and affect the ion profiles, whereas Se can ameliorate the accumulation of Cd and change the ion profiles in the chicken pancreas.

Selenium against lead-induced apoptosis in chicken nervous tissues via mitochondrial pathway

To investigate alleviative effect of selenium (Se) on lead (Pb)-induced apoptosis in chicken nervous tissues, 7-day-old chickens were randomly divided into four groups. The control group was fed a standard diet and drinking water. In the Pb and Se/Pb groups, (CH₃OO)₂Pb was dissolved in drinking water. In the Se and Se/Pb groups, Na₂SeO₃ was put into the standard diet. Embryonic neurocytes were divided into the control, Se (containing Na₂SeO₃), Pb (containing (CH₃COO)₂Pb), and Se/Pb (containing Na₂SeO₃ and (CH₃COO)₂Pb) groups. The following contents were performed: Morphologic observation for 90 days in brain tissues and for 12, 24, 36, and 48 hours in embryonic neurocytes; and antioxidant indexes, messenger RNA (mRNA) expression of twenty-five selenoproteins, and mRNA and protein expression of five apoptosis-related genes for 30, 60, and 90 days in brain tissues and for 12, 24, 36, and 48 hours in embryonic neurocytes. The results indicated that Se alleviated Pb-caused morphological changes; the decrease of superoxide dismutase, glutathione peroxidase (GPx), GPx1, GPx2, GPx3, GPx4, thioredoxin reductases (Txnrd)1, Txnrd2, Txnrd3, iodothyronine deiodinases (Dio)1, Dio2, Dio3, selenoprotein (Sel)T, SelK, SelS, SelH, SelM, SelU, SelI, SelO, Selpb, selenoprotein (Sep)n1, Sepp1, Sepx1, Sepw1, 15-kDa selenoprotein, and selenophosphate synthetases 2, and B-cell lymphoma-2 (Bcl-2); the increase of malondialdehyde, p53, Bcl-2 associated X protein, cytochrome c, and Caspase-3. Pb had time-dependent effects on GPx4, SelM, and malondialdehyde in the brain tissues; and on SelU in the embryonic neurocytes. Our data demonstrated that Se alleviated Pb-induced apoptosis in the chicken nervous tissues via mitochondrial pathway.

Selenium accelerates chicken dendritic cells differentiation and affects selenoproteins expression

Selenium (Se) promotes immune cell differentiation and improves immune response. Antigen-presenting cells such as dendritic cells (DCs) play an important role in immune system, however, the impact of Se on DCs is still unclear. In this study, we successfully induced and cultured chicken DCs from peripheral blood mononuclear cells by incubating mononuclear cells with 50 ng/mL recombinant chicken granulocyte-macrophage colony stimulating factor and 10 ng/mL recombinant chicken interleukin-4 for total 9 days. In + Se group, we added 10^-7 mol/L sodium selenite from the first day of cell culture. The results showed that Se supplementation expedited and increased the expression of cell surface markers including CD11c, CD40, CD86, and MHC II. Principal component analysis showed that the expression of selenoproteins SelW, SelK, Dio3, GPX1, GPX2, SelN, SelS, SelH in chicken DCs was highly correlated, and SelW had highest correlation with the cell surface markers MHC II and CD11c. In conclusion, Se accelerates the differentiation and maturation of chicken DCs. Se regulates the differentiation and maturation of chicken DCs by selenoproteins. Selenoproteins has closely correlated to surface markers of chicken DCs.

Selenium suppresses inflammation by inducing microRNA-146a in Staphylococcus aureus-infected mouse mastitis model

We studied the effects of selenium (Se) on the inflammatory response in Staphylococcus aureus (S. aureus)-infected mastitis-model mice and mammary epithelial cells. In infected mice, Se elicited a dose-dependent decrease in mammary gland pathology that included inflammatory cell infiltration, disorganized acinar structure and mammary cell necrosis. Se decreased inflammation by increasing miR-146a and decreasing TLR2/6 as well as NF-κB and MAPK signaling pathways in mammary tissue from infected mice and mammary epithelial cells. A miR-146a inhibitor suppressed the anti-inflammatory effects of Se in infected mammary epithelial cells. Se, miR-146a and TLR2 were associated in determining the inflammatory response in mouse with infection-induced mastitis. Thus, Se inhibits pro-inflammatory responses in mammary tissues from S. aureus-infected mice by inducing miR-146a.