Selenium alleviates endoplasmic reticulum calcium depletion-induced endoplasmic reticulum stress and apoptosis in chicken myocardium after mercuric chloride exposure.

Mercury is a highly toxic heavy metal with definite cardiotoxic properties and can affect the health of humans and animals through diet. Selenium (Se) is a heart-healthy trace element and dietary Se has the potential to attenuate heavy metal-induced myocardial damage in humans and animals. This study was designed to explore antagonistic effect of Se on the cardiotoxicity of mercuric chloride (HgCl2) in chickens. Hyline brown hens received a normal diet, a diet containing 250 mg/L HgCl2, or a diet containing 250 mg/L HgCl2 and 10 mg/kg Na2SeO3 for 7 weeks, respectively. Histopathological observations demonstrated that Se attenuated HgCl2-induced myocardial injury, which was further confirmed by the results of serum creatine kinase and lactate dehydrogenase levels assay and myocardial tissues oxidative stress indexes assessment. The results showed that Se prevented HgCl2-induced cytoplasmic calcium ion (Ca2+) overload and endoplasmic reticulum (ER) Ca2+ depletion mediated by Ca2+-regulatory dysfunction of ER. Importantly, ER Ca2+ depletion led to unfolded protein response and endoplasmic reticulum stress (ERS), resulting in apoptosis of cardiomyocytes via PERK/ATF4/CHOP pathway. In addition, heat shock protein expression was activated by HgCl2 through these stress responses, which was reversed by Se. Moreover, Se supplementation partially eliminated the effects of HgCl2 on the expression of several ER-settled selenoproteins, including selenoprotein K (SELENOK), SELENOM, SELENON, and SELENOS. In conclusion, these results suggested that Se alleviated ER Ca2+ depletion and oxidative stress-induced ERS-dependent apoptosis in chicken myocardium after HgCl2 exposure.

Protective mechanism of selenium on mercuric chloride-induced testis injury in chicken via p38 MAPK/ATF2/iNOS signaling pathway.

Mercuric chloride (HgCl2) is a well-known toxic heavy metal contaminant, which causes male reproductive function defects. Selenium (Se) has been recognized as an effective antioxidant against heavy metals-induced male reproductive toxicity. The aim of present study was to explore the potentially protective mechanism of Se on HgCl2-induced testis injury in chicken. Firstly, the results showed that Se mitigated HgCl2-induced testicular injury through increasing the blood-testis barrier (BTB) cell-junction proteins expression of occludin, zonula occludens-1 (ZO-1), connexin 43 (Cx43), and N-cadherin. Secondly, Se alleviated HgCl2-induced oxidative stress through decreasing the malondialdehyde (MDA) content and increasing the superoxidase dismutase (SOD), glutathione peroxidase (GSH-Px) activities as well as the total antioxidant capacity (T-AOC) level. Thirdly, Se inhibited the activation of p38 MAPK signaling through decreasing the proteins expression of phosphorylated-p38 (p-p38) and phosphorylated-ATF2 (p-ATF2), and alleviated inflammation response through decreasing the proteins expression of inducible nitric oxide synthase (iNOS), nuclear factor kappa B (NF-κB), tissue necrosis factor-alpha (TNF-α), and cyclooxygenase 2 (COX2). Collectively, these results demonstrated that Se effectively alleviated HgCl2-induced testes injury via improving antioxidant capacity to reduce inflammation mediated by p38 MAPK/ATF2/iNOS signaling pathway in chicken. Our data shed a new light on potential mechanisms of Se antagonized HgCl2-induced male reproductive toxicity.

Antagonistic effect of selenium on mercuric chloride in the central immune organs of chickens: The role of microRNA-183/135b-FOXO1/TXNIP/NLRP3 inflammasome axis.

Mercury (Hg) is a persistent environmental and industrial pollutant that accumulated in the body and induces oxidative stress and inflammation damage. Selenium (Se) has been reported to antagonize immune organs damage caused by heavy metals. Here, we aimed to investigate the prevent effect of Se on mercuric chloride (HgCl2 )-induced thymus and bursa of Fabricius (BF) damage in chickens. The results showed that HgCl2 caused immunosuppression by reducing the relative weight, cortical area of the thymus and BF, and the number of peripheral blood lymphocytes. Meanwhile, HgCl2 induced oxidative stress and imbalance in cytokines expression in the thymus and BF. Further, we found that thioredoxin-interacting protein (TXNIP) and the NOD-like receptor pyrin domain containing 3 (NLRP3) inflammasome mediated HgCl2 -induced oxidative stress and inflammation. Mechanically, the targeting and inhibitory effect of microRNA (miR)-135b/183 on forkhead box O1 (FOXO1) were an upstream event for HgCl2 -activated TXNIP/NLRP3 inflammasome pathway. Most importantly, Se effectively attenuated the aforementioned damage in the thymus and BF caused by HgCl2 and inhibited the TXNIP/NLRP3 inflammasome pathway by reversing the expression of FOXO1 through inhibiting miR-135b/183. In conclusion, the miR-135b/183-FOXO1/TXNIP/NLRP3 inflammasome axis might be a novel mechanism for Se to antagonize HgCl2 -induced oxidative stress and inflammation in the central immune organs of chickens.

Isoandrographolide inhibits NLRP3 inflammasome activation and attenuates silicosis in mice.

Silicosis is an irreversible occupational disease caused by silica particle exposure. Abundant evidences suggest that NLRP3-mediated inflammation acts an essential role in fibrogenesis and the pathogenesis of silicosis. In the current work, we firstly reported that (8R-12S)-isoandrographolide (ISA), a diterpenoid lactone ingredient of Chinese traditional medicinal plant Andrographis paniculata (Burm.f.) Nees, could reduce pulmonary inflammation and fibrosis by inhibiting NLRP3, and thereby ameliorate silicosis. ISA administration significantly alleviated lung injury, and attenuated inflammatory response, EMT, as well as collagen deposition in the lung of silica-induced mice. Further studies verified that ISA inhibited the expressions of NLRP3 inflammasome-related proteins NLRP3, ASC and caspase-1 in vivo and in vitro, leading to the attenuation of inflammation and EMT. Additionally, the molecular docking assay indicated that ISA possibly interacted with the residues of LYS26 and GLU47 of NLRP3, implying that ISA might directly bond to protein NLRP3. Of note, ISA revealed a lower cytotoxicity but more potent therapeutic effect than andrographolide (AD), the major active extract of A. paniculata, which has been traditionally used to treat inflammation-related diseases. Taken together, our study clarified a novel role of ISA in attenuating inflammation and fibrosis in silicosis, and indicated a bright future of ISA as a lead compound for developing therapeutic drug for silicosis.

Aberrant Gene Expression of Selenoproteins in Chicken Spleen Lymphocytes Induced by Mercuric Chloride.

Mercury (Hg) is a heavy metal widely distributed in ecological environment, poisoning the immune system of humans and animals. Selenium (Se) is an essential microelement and selenoproteins involved in the procedure of Se antagonizing organ toxicity induced by heavy metals. The aim of this research was to investigate the changes of gene expression profile of selenoproteins induced by mercuric chloride (HgCl2) in chicken spleen lymphocytes. We established cytotoxicity model of chicken spleen lymphocytes by HgCl2 exposure, the messenger RNA (mRNA) expression levels of 25 selenoproteins in spleen lymphocytes were analyzed by real-time quantitative PCR (qPCR), and the gene expression pattern of selenoproteins was revealed by principal component analysis (PCA). The results showed that the mRNA expression levels of 13 selenoproteins (GPX3, GPX4, TXNRD2, TXNRD3, DIO2, SELENOS, SELENON, SELENOT, SELENOO, SELENOP, SELENOP2, MSRB1, and SEPHS2) were decreased in HgCl2 treatment group, and there was strong positive correlation between these selenoproteins and component 1 as well as component 2 of the PCA. At the same time, the protein expression levels of GPX4, TXNRD1, TXNRD2, SELENOM, SELENOS, and SELENON were detected by Western blotting, which were consistent with the changes of gene expression. The results showed that the expression levels of selenoproteins were aberrant in response to HgCl2 toxicity. The information presented in this study provided clues for further research on the interaction between HgCl2 and selenoproteins, and the possible mechanism of immune organ toxicity induced by HgCl2.

Selenium relieves oxidative stress, inflammation, and apoptosis within spleen of chicken exposed to mercuric chloride.

Mercuric chloride (HgCl2) is a widely distributed environmental pollutant with multiorgan toxicity including immune organs such as spleen. Selenium (Se) is an essential trace element in animal nutrition and exerts biological activity to antagonize organ toxicity caused by heavy metals. The objective of this study was to explore the underlying mechanism of the protective effects of Se against spleen damage caused by HgCl2 in chicken. Ninety male Hyline brown chicken were randomly divided into 3 groups namely Cont, HgCl2, and HgCl2+Se group. Chicken were provided with the standard diet and nontreated water, standard diet and HgCl2-treated water (250 ppm), and sodium selenite-treated diet (10 ppm) plus HgCl2-treated water (250 ppm), respectively. After being fed for 7 wk, the spleen tissues were collected, and spleen index, the microstructure of the spleen, and the indicators of oxidative stress, inflammation, apoptosis as well as heat shock proteins (HSP) were detected. First, the results of spleen index and pathological examination confirmed that Se exerted an antagonistic effect on the spleen injury induced by HgCl2. Second, Se ameliorated HgCl2-induced oxidative stress by decreasing the level of malondialdehyde and increasing the levels of glutathione, glutathione peroxidase, and total antioxidant capacity. Third, Se attenuated HgCl2-induced inflammation by decreasing the protein expression of nuclear factor kappa-B, inducible nitric oxide synthase, and cyclooxygenase-2, and the gene expression of interleukin (IL)-1ß, IL-6, IL-8, IL-12ß, IL-18 as well as tumor necrosis factor-α. Fourth, Se inhibited HgCl2-induced apoptosis by downregulating the protein expression of BCL2 antagonist/killer 1 and upregulating the protein expression of B-cell lymphoma-2. Finally, Se reversed HgCl2-triggered activation of HSP 60, 70, and 90. In conclusion, Se antagonized HgCl2-induced spleen damage in chicken, partially through the regulation of oxidative stress, inflammatory, and apoptotic signaling.

Response of selenoproteins gene expression profile to mercuric chloride exposure in chicken kidney.

Kidney is a primary target organ for mercuric chloride (HgCl2) toxicity. Selenium (Se) can exert antagonistic effect on heavy metals-induced organ toxicity by regulating the expression of selenoproteins. The objective of this study was to investigate the effect of HgCl2 on the gene expression of selenoproteins in chicken kidney. Sixty male Hyline brown chickens were randomly and evenly divided into two groups. After acclimatization for one week, chickens were provided with the standard diet as well as non-treated water (CON group), and standard diet as well as HgCl2-treated water (250 ppm, HgCl2 group). After seven weeks, kidney tissues were collected to examine the mRNA expression levels of 25 selenoproteins genes and protein expression levels of 4 selenoproteins. Moreover, correlation analysis and principal component analysis (PCA) were used to analyze the expression patterns of 25 selenoproteins. The results showed that HgCl2 exposure significantly decreased the mRNA expression of Glutathione peroxidase 1 (GPX1), GPX4, Thioredoxin reductase 2 (TXNRD2), Iodothyronine deiodinase 1 (DIO1), Methionine-Rsulfoxide reductase 1 (SELR), 15-kDa selenoprotein (SEP15), selenoprotein I (SELI), SELK, SELM, SELN, SELP, SELS, SELT, SELW, and SEPHS2. Meanwhile, HgCl2 exposure significantly increased the mRNA expression of GPX3, TXNRD1, and SELU. Western blot analysis showed that the expression levels of GPX3, TXNRD1, SELK, and SELN were concordant with these mRNA expression levels. Analysis results of selenoproteins expression patterns showed that HgCl2-induced the main disorder expression of selenoproteins with antioxidant activity and endoplasmic reticulum resident selenoproteins. In conclusion, selenoproteins respond to HgCl2 exposure in a characteristic manner in chicken kidney.

Effects of beta-1,3-glucan supplementation on concentrations of serum metabolites in transition Holstein cows.

Objectives of this study were to evaluate the alleviating effects of a commercial beta-1,3-glucan product (Aleta, containing 50% beta-1,3-glucan, Kemin Industries) on metabolic stress in transition Holstein cows as reflected by circulating metabolites and enzymes. Fifty-four multiparous Holstein cows were randomly allocated to three groups with 18 cows each. Cows in each group received a commercial basal diet or the basal diet supplemented with Aleta calculated to supply 5 or 10 g of Aleta per cow per day. Blood samples were collected at day -21, 1, and 21 relative to calving for determination of serum triglyceride (TG), total cholesterol (TC), low density lipoprotein cholesterol (LDL-C), high density lipoprotein cholesterol (HDLC), very low density lipoprotein (VLDL), glucose, insulin, ß-hydroxybutyric acid (BHBA), aspartate aminotransferase (AST), alanine aminotransferase (ALT), glutamyl transpeptidase (GGT), and non-esterified fatty acid (NEFA). Supplementation with Aleta markedly elevated serum concentrations of TG, TC, HDLC, LDL-C and VLDL, implying its positive effect on lipid metabolism in transition dairy cows. Aleta treatment significantly decreased the serum concentrations of NEFA and BHBA, but markedly elevated the serum concentrations of glucose and insulin. Also, Aleta treatment significantly elevated the dry matter intake and milk production in postpartum cows, indicating the alleviating effect of Aleta on negative energy balance in transition cows. Moreover, Aleta treatment significantly reduced the serum activities of AST, ALT and GGT, indicating its hepatoprotective effect on transition cows. These results suggest that Aleta supplementation may help to improve fat metabolism disorder initiated by negative energy balance in transition dairy cows.

The proteomic profiling of multiple tissue damage in chickens for a selenium deficiency biomarker discovery.

Over the past decades, substantial advances have been made in both the early diagnosis and accurate prognosis of numerous cancers because of the impressive development of novel proteomic strategies. Selenium (Se) is an essential trace element in humans and animals. Se deficiency could lead to Keshan disease in humans, mulberry heart disease in pigs and damage of tissues including cardiac injury, apoptosis in the liver, reduction in the immune responses in spleen and cerebral lesions in chickens. However, it is well know that plasma biomarkers are not specific and also show alterations in various diseases including those caused by Se deficiency. Therefore, new definition biomarkers are needed to improve disease surveillance and reduce unnecessary chicken losses due to Se deficiency. To identify new biomarkers for Se deficiency, we performed exploratory heart, liver, spleen, muscle, vein, and artery proteomic screens to further validate the biomarkers using Venn analysis, GO enrichment, heatmap analysis, and IPA analysis. Based on the bioinformatics methods mentioned above, we found that differentially expressed genes and proteins are enriched to the PI3K/AKT/mTOR signal pathway and insulin pathway. We further used western blot to detect the expression of proteins related to the two pathways. Results showed that the components of the PI3K/AKT/mTOR signal pathway were definitely decreased in heart, liver, spleen, muscle, vein and artery tissues in the Se deficient group. Expression IGF and IGFBP2 of the insulin pathway were differentially increased in the heart, liver, and spleen in Se deficient group samples and decreased in muscle and artery. In conclusion, 5 proteins, namely PI3K, AKT, mTOR, IGF, and IGFBP2, were differentially expressed, which could be potentially useful Se deficient biomarkers. In the present study, proteomic profiling was used to elucidate protein biomarkers that distinguished Se deficient samples from the controls, which might provide a new direction for the diagnosis and targeted treatment induced by Se deficiency in chickens.

Selenium Mitigates Cadmium-Induced Adverse Effects on Trace Elements and Amino Acids Profiles in Chicken Pectoral Muscles.

Cadmium (Cd), as one of the most toxic heavy metals, has become a widespread environmental contaminant and threats the food quality and safety. The protective effect of selenium (Se) on Cd-induced tissue lesion and cytotoxicity in chicken has been extensively reported. The objective of this study was to investigate the antagonistic effect of Se on Cd-induced damage of chicken pectoral muscles via analyzing the trace elements and amino acids profiles. Firstly, 19 trace elements contents were analyzed by inductively coupled plasma mass spectrometry (ICP-MS). The results showed that under Cd exposure, the contents of Cd, lead (Pb), mercury (Hg), aluminum (Al), and lithium (Li) were significantly elevated, and the contents of Se, iron (Fe), and chromium (Cr) were significantly reduced. However, supplementing Se significantly reversed the effects induced by Cd. Secondly, the amino acids contents were detected by L-8900 automatic amino acid analyzer. The results showed that supplementing Se increased significantly Cd-induced decrease of valine (Val), leucine (Leu), arginine (Arg), and proline (Pro). Thirdly, the results of principal component analysis (PCA) showed that cobalt (Co), manganese (Mn), silicium (Si), and Pro may play special roles in response to the process of Se antagonizes Cd-induced damage of pectoral muscles in chickens. In summary, these results indicated that different trace elements and amino acids possessed and exhibited distinct responses to suffer from Se and/or Cd in chicken pectoral muscles. Notably, Se alleviated Cd-induced adverse effects by regulating trace elements and amino acids profiles in chicken pectoral muscles.

Selenium alleviates cadmium-induced inflammation and meat quality degradation via antioxidant and anti-inflammation in chicken breast muscles.

Cadmium (Cd) as a widespread toxic heavy metal accumulates in animal food including chicken meat through food chain enrichment and finally threatens human health. Selenium (Se) is an essential mineral and possesses antagonistic effects on Cd-induced multiple organs' toxicity in chickens. The objective of the present study was to reveal the antagonistic mechanisms of Se to Cd from the aspects of oxidative stress, inflammation, and meat quality in chicken breast muscles. Firstly, the results showed that Cd significantly elevated the levels of malondialdehyde (MDA), hydrogen peroxide (H2O2), and protein carbonyl, and declined the levels of glutathione peroxidase (GSH-Px), superoxide dismutase (SOD), and catalase (CAT) to trigger oxidative stress in chicken breast muscles. However, Se treatment significantly alleviated Cd-induced oxidative stress by increasing the levels of GSH-Px, SOD, and CAT, and decreasing the levels of MDA, H2O2, and protein carbonyl. Secondly, Se obviously inhibited the expressions of Cd-activated inflammation-related genes including tumor necrosis factor (TNF-α), nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB), inducible nitric oxide synthase (iNOS), prostaglandin-endoperoxide synthase 2 (COX-2), and prostaglandin E synthase (PTGEs) in chicken breast muscles. Thirdly, meat quality-related parameters including pH45min, ultimate pH (pHu), and drip loss were also detected, and the results showed that Se markedly recovered Cd-induced dropt of pH45min and increase of drip loss in chicken breast muscles. In brief, these findings demonstrated that Se significantly alleviated Cd-induced oxidative stress and inflammation, and declined meat quality of chicken breast muscles.

Cadmium-mediated miR-30a-GRP78 leads to JNK-dependent autophagy in chicken kidney.

Cadmium-mediated microRNAs have become a heavily researched topic. Few studies mention the regulation of autophagy by cadmium through microRNAs, especially regarding poultry. The kidney is one of the organs most severely affected by cadmium, as it is involved in the accumulation of metal ions; causing such types of damage as apoptosis, necrosis and autophagy to the body. However, the relationship between miR-30a and GRP78 in the chicken kidney during ER stress and autophagy via JNK has not been thoroughly elucidated to date. In our research, we randomly assigned 128 Hy-Line Brown laying chickens to four groups with different diet treatments. The four groups consisted of the control group (0.2 mg Se kg-1), the Se group (2 mg kg-1 of Na2SeO3), the Se + Cd group (150 mg kg-1 of CdCl2 and 2 mg kg-1 of Na2SeO3) and the Cd group (150 mg kg-1 of CdCl2). On the 90th day, we detected the expression of miR-30a, GRP78, ER stress-related genes, IRE-1-JNK and autophagy-related genes. Compared with the control group, the mRNA levels of IRE-1-JNK, ER stress-related genes, autophagy-related genes and GRP78 were significantly increased (P < 0.05), while the expression of miR-30a was significantly decreased (p < 0.05) in the Cd group. However, those changes were clearly alleviated in the Se + Cd group (p < 0.05). In summary, we demonstrated that Cd triggered an miR-30a-GRP78 signaling axis disorder, increasing ER stress and activating the IRE-1-JNK pathway, thereby promoting autophagy in the chicken kidney. Moreover, Se could antagonize the negative impact of Cd.

Gga-let-7f-3p promotes apoptosis in selenium deficiency-induced skeletal muscle by targeting selenoprotein K.

Selenoprotein K (SELENOK) is primarily observed in the endoplasmic reticulum, and serves to maintain the normal physiological functions of skeletal muscle. Skeletal muscle development and regeneration are associated with significant changes in the expression of specific microRNAs (miRNAs). Downregulated SELENOK expression is observed in chicken muscles deficient of Se. However, the mechanisms of miRNA regulation of SELENOK expression remain elusive. Here, deep sequencing was used to detect the miRNA profiles of muscle in Se deficient (-Se group) and normal (C group) chickens. A dual-luciferase reporter assay was adopted to verify the relationship between SELENOK and gga-let-7f-3p. In addition, gga-let-7f-3p was either overexpressed or knocked-down in chicken myoblasts. Furthermore, the cells were treated with N-acetyl-l-cysteine (NAC) or hydrogen peroxide (H2O2) in order to probe the factors involved in oxidative stress, endoplasmic reticulum stress (ERS) and apoptosis, respectively. Relative to the C group, there were 132 differentially expressed miRNAs (including 57 upregulated and 75 downregulated) in the muscles of the -Se group. The dual-luciferase reporter assay showed that SELENOK was a primary target of gga-let-7f-3p. It was also observed that the overexpression or knock-down of gga-let-7f-3p significantly influenced the SELENOK expression. Moreover, NAC blocked mimics of ga-let-7f-3p, thus inducing oxidative stress, ERS and apoptosis. Simultaneously, gga-let-7f-3p inhibitors blocked the stimulant effects caused by H2O2 in chicken myoblasts. Furthermore, Se deficiency downregulated the SELENOK protein expression and induced oxidative stress, ERS and apoptosis in chicken muscles. In conclusion, the gga-let-7f-3p-SELENOK pathway played a pivotal role in Se deficiency mediated muscle injuries through the induction of oxidative stress and ERS, ultimately promoting apoptosis.

Inflammatory Response Occurs in Veins of Broiler Chickens Treated with a Selenium Deficiency Diet.

Selenium (Se) has been indicated to prevent chronic diseases including cancer, cardiovascular disease, and type 2 diabetes. However, a few studies have indicated that Se deficiency can induce vascular diseases. Thus, in the present study, we investigated the effect of Se deficiency on vascular pathology. A total of 60 male broiler chickens were randomly divided into 2 groups (n = 30). The control group (C group) was fed a basic diet, and the Se-deficient group (L group) was fed a Se-deficient, corn-soy-based diet. Changes in messenger RNA (mRNA) and protein levels of inflammatory factors and inflammation-related cytokines were examined by both RT-PCR and Western blot analysis. Our results indicate that the mRNA and protein levels of inflammatory factors and inflammation-related cytokines in the L group were significantly changed in the vein. In addition, principal component analysis (PCA) was used to define the most important parameters that could be used as key factors. The in vitro experiments also demonstrated that Se can enhance the anti-inflammatory ability of vein endothelial cells. In conclusion, Se deficiency induces an inflammatory response by modulating inflammatory factors and inflammation-related cytokines.

Alleviation of cadmium-induced oxidative stress by trehalose via inhibiting the Nrf2-Keap1 signaling pathway in primary rat proximal tubular cells.

Nuclear factor erythroid 2-related factor 2 (Nrf2) is a transcription factor that regulates a cluster of oxidative stress-inducible genes in cells. Here, we aimed to investigate whether trehalose (Tre) protects primary rat proximal tubular (rPT) cells against cadmium (Cd)-induced oxidative stress via Nrf2 antioxidant pathway. Data showed that Tre treatment inhibited Nrf2 nuclear translocation and restored the decline in Kelch-like ECH-associated protein 1 (Keap1) protein level in Cd-exposed rPT cells. Moreover, Cd-activated Nrf2 target genes, including phase II detoxifying enzymes, that is, NAD(P)H quinone oxidoreductase 1 and heme oxygenase-1, direct antioxidant proteins, that is, glutathione peroxidase, superoxide dismutase, catalase, and glutathione biosynthesis-related proteins, that is, glutamatecysteine ligase catalytic subunit, glutamate cysteine ligase modifier subunit, and glutathione reductase, were all downregulated by co-treatment with Tre. Collectively, these findings demonstrate that Tre treatment alleviates Cd-induced oxidative stress in rPT cells by inhibiting the Nrf2-Keap1 signaling pathway.

Selenium deficiency-induced alterations in ion profiles in chicken muscle.

Ion homeostasis plays important roles in development of metabolic diseases. In the present study, we examined the contents and distributions of 25 ions in chicken muscles following treatment with selenium (Se) deficiency for 25 days. The results revealed that in chicken muscles, the top ranked microelements were silicon (Si), iron (Fe), zinc (Zn), aluminum (Al), copper (Cu) and boron (B), showing low contents that varied from 292.89 ppb to 100.27 ppm. After Se deficiency treatment, essential microelements [Cu, chromium (Cr), vanadium (V) and manganese (Mn)], and toxic microelements [cadmium (Cd) and mercury (Hg)] became more concentrated (P < 0.05). Elements distribution images showed generalized accumulation of barium (Ba), cobalt (Co), Cu, Fe and V, while Cr, Mn, and Zn showed pin point accumulations in muscle sections. Thus, the ion profiles were generally influenced by Se deficiency, which suggested a possible role of Se deficiency in muscle dysfunctions caused by these altered ion profiles.

Selenium antagonizes cadmium-induced apoptosis in chicken spleen but not involving Nrf2-regulated antioxidant response.

The nuclear transcription factor NF-E2-related factor 2 (Nrf2) binds to antioxidant response elements (AREs) and is involved in the regulation of genes participated in defending cells against oxidative damage, which have been confirmed in animal models. Selenium (Se), known as an important element in the regulation of antioxidant activity, can antagonize Cadmium (Cd) toxicity in birds. However, the role of Nrf2 in selenium-cadmium interaction has not been reported in birds. To further explore the mechanism of selenium attenuating spleen toxicity induced by cadmium in chickens, cadmium chloride (CdCl2, 150mg/kg) and sodium selenite (Na2SeO3, 2mg/kg) were co-administrated or individually administered in the diet of chickens for 90 days. The results showed that Cd exposure increased the level of hydrogen peroxide (H2O2) and malondialdehyde (MDA) and decreased the antioxidant enzyme activities, including superoxide dismutase (SOD), glutathione peroxidase (Gpx), total antioxidative capacity (T-AOC), catalase (CAT). Cd exposure increased obviously nuclear accumulation of Nrf2, and the expression of Nrf2 downstream heme oxygenase-1 (HO-1) and NAD(P)H: quinine oxidoreductase 1 (NQO1), reduced the expression of Kelch-like ECH-associated protein (keap1), Gpx-1 and thioredoxin reductase-1 (TrxR1). In addition, Cd induced the increase of bak, caspase9, p53, Cyt c mRNA levels, increased bax/bcl-2 ratio, increased caspase3 mRNA and protein levels. Selenium treatment reduced the accumulation of Cd in the spleen, attenuates Cd-induced Nrf2 nuclear accumulation, enhanced antioxidant enzyme activities, ameliorated Cd-induced oxidative stress and apoptosis in the spleen. In summary, our results demonstrate that Se ameliorated spleen toxicity induced by cadmium by modulating the antioxidant system, independently of Nrf2-regulated antioxidant response pathway.

Impact of exudative diathesis induced by selenium deficiency on LncRNAs and their roles in the oxidative reduction process in broiler chick veins.

Selenium deficiency may induce exudative diathesis (ED) in broiler chick, and this damage is closely related to oxidative damage. Long noncoding RNA (LncRNA) can regulate the redox state in vivo. The aim of the present study was to clarify the LncRNA expression profile in broiler veins and filter and verify the LncRNAs related to oxidative damage of ED. This study established an ED model induced by selenium deficiency and presented the expression and characterization of LncRNAs in normal and ED samples. A total of 15412 LncRNAs (including 8052 novel LncRNAs) were generated in six cDNA libraries using the Illumina Hi-Seq 4000 platform. 635 distinct changes in LncRNAs (up-regulated fold change > 1.5, down-regulated fold change < 0.67 and differentially expressed LncRNAs) were filtered. Gene ontology enrichment on LncRNAs target genes showed that the oxidative reduction process was important. This study also defined and verified 19 target mRNAs of 23 LncRNAs related to the oxidative reduction process. The in vivo and vitro experiments also demonstrated these 23 LncRNAs can participate in the oxidative reduction process. This study presents LncRNAs expression profile in broiler chick veins for the first time and confirmed 23 LncRNAs involving in the vein oxidative damage in ED.

Effects of selenium-lead interaction on the gene expression of inflammatory factors and selenoproteins in chicken neutrophils.

Lead (Pb) is one of the most highly toxic metal pollutant that can cause damage to the immune system. It is known that selenium (Se) can antagonize heavy metals. To explore the toxic effects of Pb poisoning on bird immune cells, as well as the alleviating effects of Se on Pb, Se supplement and/or Pb poisoning chicken models were established. One hundred and eighty Hyline 7-day-old male chickens received either Se (1mg Se per kg of diet), Pb (350mg Pb per liter water) or Se+Pb in their diet and water for 90 days. Then, whole blood was collected from the four groups of chickens, and serum and neutrophils were isolated. The levels of Se and Pb in chicken serum, mRNA levels of 24 selenoproteins (GPX1, GPX2, GPX3, GPX4, Dio1, Dio2, Dio3, Txnrd1, Txnrd2, Txnrd3, SELS, SPS2, SELK, SELW1, SEP15, SEPX1, SELT, SELI, SELO, SELM, SEPN1, SEPP1, SELU, SELH) and inflammatory factors (TNF-α, COX-2, iNOS, NF-κB), and iNOS protein level in chicken neutrophils were determined, and protein-protein interaction prediction and principal component analysis were performed. The data showed that Pb exposure increased Pb content in serum, activated the NF-κB pathway, and increased the expression of selenoproteins in chicken neutrophils. Se supplements could reduce Pb concentration in serum, had a mitigative effect on the activation of the NF-κB pathway and further enhanced the upward trend of selenoprotein expression induced by Pb exposure. These results suggest that Se supplement could eliminate Pb in serum and alleviate the activation of the NF-κB pathway under Pb exposure by increasing the expression of selenoproteins.

Selenoprotein W redox-regulated Ca2+ channels correlate with selenium deficiency-induced muscles Ca2+ leak.

Selenium (Se) deficiency induces Ca2+ leak and calcification in mammal skeletal muscles; however, the exact mechanism is still unclear. In the present study, both Se-deficient chicken muscle models and selenoprotein W (SelW) gene knockdown myoblast and embryo models were used to study the mechanism. The results showed that Se deficiency-induced typical muscular injuries accompanied with Ca2+ leak and oxidative stress (P < 0.05) injured the ultrastructure of the sarcoplasmic reticulum (SR) and mitochondria; decreased the levels of the Ca2+ channels, SERCA, SLC8A, CACNA1S, ORAI1, STIM1, TRPC1, and TRPC3 (P < 0.05); and increased the levels of Ca2+ channel PMCA (P < 0.05). Similarly, SelW knockdown also induced Ca2+ leak from the SR and cytoplasm; increased mitochondrial Ca2+ levels and oxidative stress; injured SR and mitochondrial ultrastructure; decreased levels of SLC8A, CACNA1S, ORA1, TRPC1, and TRPC3; and caused abnormal activities of Ca2+ channels in response to inhibitors in myoblasts and chicken embryos. Thus, both Se deficiency and SelW knockdown induced Ca2+ leak, oxidative stress, and Ca2+ channel reduction. In addition, Ca2+ levels and the expression of the Ca2+ channels, RyR1, SERCA, CACNA1S, TRPC1, and TRPC3 were recovered to normal levels by N-acetyl-L-cysteine (NAC) treatment compared with SelW knockdown cells. Thus, with regard to the decreased Ca2+ channels, SelW knockdown closely correlated Se deficiency with Ca2+ leak in muscles. The redox regulation role of SelW is crucial in Se deficiency-induced Ca2+ leak in muscles.