The cell cycle arrest and apoptosis of bursa of Fabricius induced by low selenium in chickens

BPA and low-Se exacerbate apoptosis and autophagy in the chicken bursa of Fabricius by regulating the ROS/AKT/FOXO1 pathway

Bisphenol A (BPA) is a ubiquitous environmental pollutant that can have harmful effects on human and animal immune systems by inducing oxidative stress. Selenium (Se) deficiency damages immune organ tissues and exhibits synergistic effects on the toxicity of environmental pollutants. However, oxidative stress, cell apoptosis, and autophagy caused by the combination of BPA and low-Se, have not been studied in the bursa of Fabricius of the immune organ of poultry. Therefore, in this study, BPA and/or low-Se broiler models and chicken lymphoma cells (MDCC-MSB-1 cells) models were established to investigate the effects of BPA and/or low-Se on the bursa of Fabricius of poultry. The data showed that BPA and/or low-Se disrupted the normal structure of the bursa of Fabricius, BPA (60 μM) significantly reduced the activity of MDCC-MSB-1 cells and disrupted normal morphology (IC50 = 192.5 ± 1.026 μM). Compared with the Control group, apoptosis and autophagy were increased in the BPA or low-Se groups, and the generation of reactive oxygen species (ROS) was increased. This inhibited the AKT/FOXO1 pathway, leading to mitochondrial fusion/division imbalance (Mfn1, Mfn2, OPA1 were increased, DRP1 was decreased) and dysfunction (CI-NDUFB8, CII-SDHB, CIII-UQCRC2, CIV-MTCO1, CV-ATP5A1, ATP). Furthermore, combined exposure of BPA and low-Se aggravated the above-mentioned changes. Treatment with N-acetylcysteine (NAC) reduced ROS levels and activated the AKT/FOXO1 pathway to further alleviate BPA and low-Se-induced apoptosis and autophagy. Apoptosis induced by low-Se + BPA was exacerbated after 3-Methyladenine (3-MA, autophagy inhibitor) treatment. Together, these results indicated that BPA and low-Se aggravated apoptosis and autophagy of the bursa of Fabricius in chickens by regulating the ROS/AKT/FOXO1 pathway.

MiR-144-3p targets STC1 to activate PI3K/AKT pathway to induce cell apoptosis and cell cycle arrest in selenium deficiency broilers

Selenium (Se) is an indispensable trace element in vertebrate. Se deficiency can damage the immune system. Studies have shown that Se deficiency can cause immune organ damage by regulating the expression of microRNA. Bursa of Fabricius is a special immune organ in poultry. In order to explore the mechanism of bursa of Fabricius injury caused by Se deficiency and the role of miRNA in this process. Firstly, we established the Se deficient model of broilers in vivo and found that Se deficiency could induce apoptosis and cell cycle arrest of bursa of Fabricius cells through Phosphoinositide 3-kinase (PI3K)/Protein Kinase B (AKT) pathway. Secondly, we inferred miRNA (miR-144-3p) and target gene Stanniocalcin 1 (STC1) that may regulate PI3K/AKT pathway through biological analysis system, and further predicted and determined the targeting relationship between them through dual luciferase, it was found that miR-144-3p was highly expressed in the process of cell apoptosis and cell cycle arrest induced by Se deficiency. Finally, in order to further understand whether miR-144-3p/STC1 axis is involved in the process, miR-144-3p knockdown and overexpression experiments were carried out, it was found that miR-144-3p inhibitor can reduce the occurrence of cell apoptosis and cell cycle arrest. In conclusion, Se deficiency can induce apoptosis and cell cycle arrest of bursa of Fabricius in Broilers by up regulating miR-144-3p targeting STC1 and activating PI3K/AKT pathway, leading to injury of bursa of Fabricius in broilers.

Effects of selenium on the proliferation and apoptosis of sheep spermatogonial stem cells in vitro

The objective of this study was to investigate effects of selenium (Se) on proliferation and apoptosis of sheep spermatogonial stem cells (SSC) in vitro. The SSC were assigned to five treatment groups (0, 2.0, 4.0, 8.0 and 16.0 μmol/L Se). After treatment with Se for 96 h, cell proliferation and apoptosis were evaluated. The relative abundance of P53 mRNA transcript and protein, cell cycle and apoptosis-related genes were detected using real-time PCR and Western blot quantifications, respectively. The results indicate there were the least cell proliferation rates in the Se_16.0 group. Treatments with relatively greater Se concentrations (8.0 and 16.0 μmol/L) resulted in a greater percentage of apoptotic cells, which was consistent with the relative abundances of P53, P21, P27 and pro-apoptosis mRNA transcripts. There were relatively greater ROS concentrations in the control, Se_8.0 and Se_16.0 groups. Compared with the control group, treatment with the Se concentration of 16.0 μmol/L resulted in an increased abundance of P53, P21, P27 and BAX proteins. Treatment with Pifithrin-α suppressed the increase in abundance of P53 and P21 proteins induced by the relatively greater concentration of Se (16.0 μmol/L), however, did not result in a change in abundances of P27 and BAX proteins. These results indicate the regulatory functions of Se on proliferation and apoptosis of sheep SSC is associated with the P21-mediated P53 signalling pathway. The P27 and BAX proteins have limited functions during the apoptotic process of SSC induced by the relatively greater concentrations of Se.

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.

Nutritional requirements of meat-type and egg-type ducks: what do we know?

The demand for duck meat, duck eggs, and associated products is increasing each year. Classic and modern selection programs have been applied to enhance the economic traits of ducks to satisfy the requirements of consumers and enhance the incomes of producers. The nutritional requirements of unselected ducks may not be adequate, however, to fulfill the potential productivity performance of modern birds, including both meat-type and egg-type ducks. In particular, an imbalanced diet is associated with low productive performance and signs of nutritional deficiency (if insufficient nutrients are supplied), as well as with high feed costs and manure problems that reflect flock health and welfare (if excessive nutrients are supplied). Thus, the main aim of this review is to summarize the results of previous studies that estimated the nutrient requirements of meat-type and egg-type ducks in order to evaluate current knowledge and to identify further issues that need to be addressed. In addition, the results obtained in previous studies are compared in order to understand how to lower commercial feed costs, fulfill the genetic potential of selected ducks, protect the environment from pollution, and satisfy the welfare and health needs of ducks.

The Molecular Mechanisms of Protective Role of Se on the G2/M Phase Arrest of Jejunum Caused by AFB1

Aflatoxin B₁ (AFB₁) is the most toxic among the mycotoxins and causes detrimental health effects on human and animals. Selenium (Se) plays an important role in chemopreventive, antioxidant, anticarcinogen, and detoxification and involved in cell cycle regulation. The aim of this study was to explore the molecular mechanisms of selenium involved in inhibition of G₂/M cell cycle arrest of broiler's jejunum. A total of 240 one-day-old healthy Cobb broilers were randomly divided into four groups and fed with basal diet (control group), 0.6 mg/kg AFB₁ (AFB₁ group), 0.4 mg/kg Se (+Se group), and 0.6 mg/kg AFB₁ + 0.4 mg/kg Se (AFB₁ + Se group) for 21 days, respectively. The histological observation and morphological analysis revealed that 0.4 mg/kg Se prevented the AFB₁-associated lesions of jejunum including the shedding of the apical region of villi, the decreased villus height, and villus height/crypt ratio. The cell cycle analysis by flow cytometry showed that 0.4 mg/kg Se ameliorated the AFB₁-induced G₂/M phase arrest in jejunal cells. Moreover, the expressions of ATM, Chk2, p53, Mdm2, p21, PCNA, Cdc25, cyclin B, and Cdc2 analyzed by immunohistochemistry and qRT-PCR demonstrated that 0.4 mg/kg Se restored these parameters to be close to those in the control group. In conclusion, Se promoted cell cycle recovery from the AFB₁-induced G₂/M phase arrest by the molecular regulation of ATM pathway in the jejunum of broilers. The outcomes from the present study may lead to a better understanding of the nature of selenium's essentiality and its protective roles against AFB₁.

Effects of different dl-selenomethionine and sodium selenite levels on growth performance, immune functions and serum thyroid hormones concentrations in broilers

This trial was conducted in a 2 × 3 + 1 factorial arrangement based on a completely randomized design to evaluate the effects of different dl-selenomethionine (dl-Se-Met) and sodium selenite (SS) levels on growth performance, immune functions and serum thyroid hormones concentrations in broilers. A total of 840 Ross 308 broilers (7 days old) were allocated by body weight to seven treatments (three replicates of 40 birds each treatment) including (1) basal diet (containing 0.04 mg of selenium (Se)/kg; control) without supplementary Se; (2, 3 and 4) basal diet + 0.05, 0.15 or 0.25 mg/kg Se as SS; (5, 6 and 7) basal diet + 0.05, 0.15 or 0.25 mg/kg Se as dl-Se-Met. The experiment lasted 42 days. The results revealed that dietary Se supplementation improved (p < 0.05) average daily gain, feed efficiency, immune organ index, serum immunoglobulin A (IgA), immunoglobulin G (IgG), immunoglobulin M (IgM) and triiodothyronine (T3 ) concentrations and decreased (p < 0.01) thyroxine (T4 )/T3 ratio in serum compared with the control. Broilers receiving the dl-Se-Met-supplemented diets had higher (p < 0.05) feed efficiency, thymus index, the amounts of IgA, IgG, IgM and T3 as well as lower (p < 0.05) serum T4 concentrations and T4 /T3 ratio than those consuming the SS-supplemented diets. Serum IgA and IgM levels of broilers fed 0.15 mg Se/kg were significantly higher (p < 0.05) than those of broilers fed 0.05 or 0.25 mg Se/kg. In summary, we concluded that dl-Se-Met is more effective than SS in increasing immunity and promoting conversion of T4 to T3 , thus providing an effective way to improve the growth performance of broilers. Besides, based on a consideration of all experiment indices, 0.15 mg Se/kg was suggested to be the optimal level of Se supplementation under the conditions of this study.

Selenoproteins and heat shock proteins play important roles in immunosuppression in the bursa of Fabricius of chickens with selenium deficiency

Selenium (Se) is necessary for the immune system in chicken and mediates its physiological functions through selenoproteins. Heat shock proteins (Hsps) are indispensable for maintaining normal cell function and for directing the immune response. The aim of the present study was to investigate the effects of Se deficiency on the messenger ribonucleic acid (mRNA) expression levels of selenoproteins and Hsps as well as immune functions in the chicken bursa of Fabricius. Two groups of chickens, namely the control and Se-deficient (L group) groups, were reared for 55 days. The chickens were offered a basal diet, which contained 0.15 mg Se/kg in the diet fed to the control group and 0.033 mg Se/kg in the diet fed to the L group. We performed real-time quantitative polymerase chain reaction to detect the mRNA expression levels of selenoproteins and Hsps on days 15, 25, 35, 45 and 55. Western blotting was used to determine the protein expression levels of Hsps on days 35, 45 and 55, and immune functions were assessed through an enzyme-linked immunosorbent assay on days 15, 35, and 55. The data showed that the mRNA expression levels of selenoproteins, such as Txnrd1, Txnrd2, Txnrd3, Dio1, Dio2, Dio3, GPx1, GPx2, GPx3 GPx4, Sepp1, Selo, Sel-15, Sepx1, Sels, Seli, Selu, Selh, and SPS2, were significantly lower (P < 0.05) in the L group compared with the control group. Additionally, the mRNA and protein expression levels of Hsps (Hsp27, Hsp40, Hsp60, Hsp70, and Hsp90) were also significantly higher (P < 0.05) in the L group. The expression levels of IL-2, IL-6, IL-8, IL-10, IL-17, IL-1β, IFN-α, IFN-β, and IFN-γ were significantly lower (P < 0.05) and TNF-α was significantly higher (P < 0.05) in the L group compared with the control group. Our results show that immunosuppression was accompanied by a downregulation of mRNA expression levels of selenoproteins and an upregulation of the Hsp mRNA expression levels. Thus, Se deficiency causes defects in the chicken bursa of Fabricius, and selenoproteins and Hsps play important roles in immunosuppression in the bursa of Fabricius of chickens with Se deficiency.

The WOMED model of benign thyroid disease: Acquired magnesium deficiency due to physical and psychological stressors relates to dysfunction of oxidative phosphorylation

BACKGROUND

The aim of this study was to discern whether a relation between biochemical parameters, sonography and musculoskeletal data exists in cases of hyperthyroidism and whether they are modifiable through supplementation with selenomethionine and magnesium citrate as well as by acupuncture and manual medicine methods.

RESULTS

A direct correlation between whole blood selenium and serum magnesium was found in subjects without thyroid disease and in menopausal women while it was reversed in cases of thyroid diseases as well as in patients with depression, infection, and in infertile women. Vascularization indices were elevated in cases of newly diagnosed benign thyroid diseases. Musculoskeletal changes i.e. lateral tension and idiopathic moving toes, as well as situations of physical and psychological stress and minor trauma and infection led to an increase of vascularization. Magnesium levels correlated negatively with these two conditions. The supplementation brought a reduction of the vascularization indices and reduced the incidence of idiopathic moving toes. Treatment of lateral tension required manual medicine methods and acupuncture (gastrocnemius). A small subgroup of patients showed a further reduction of hyper-vascularization after receiving coenzyme Q10.

CONCLUSIONS

We interpret the elevated thyroid vascularization and low magnesium levels as signs of an inflammatory process related to the musculoskeletal changes. Improvement of thyroid function and morphology can be achieved after correcting the influence of stressors together with the supplementation regime. We hypothesize that the central biochemical event in thyroid disease is that of an acquired, altered mitochondrial function due to deficiency of magnesium, selenium, and coenzyme Q10.

Developmental changes in cell proliferation and apoptosis in the normal duck bursa of Fabricius

The aim of this work was to investigate developmental changes in cell proliferation and apoptosis in normal duck bursa of Fabricius using flow cytometry and immunohistochemistry. Studies were carried out on Tianfu ducks on days 24 and 27 of embryogenesis (E24 and E27) along with days 20, 70, and 200 of postnatal development (P20, P70, and P200). Results showed that the percentage of G₀/G₁ bursa cells significantly increased between E24 and P200 while the percentage of cells in the S phase or G₂ + M phase as well as the proliferating index obviously decreased during the same period. Proliferation cell nuclear antigen was detected in lymphocyte and interfollicular epithelium. The proliferative lymphocyte density tended to decrease from E24 to P200. Apoptotic bodies in macrophages, free apoptotic bodies, or nuclei with condensed chromatin in lymphocytes in follicles were identified by transferase-mediated dUTP nick-end labeling. Both flow cytometry and microscopic analysis reveal that the proportion of apoptotic cells and apoptotic lymphocyte density increased from E24 to P20, fell on P70, then rose again on P200. Our foundings demonstrate that cell proliferation decreases and apoptosis increases with age. These changes may account for duck bursa development and involution.

Effect of oxygen free radicals and nitric oxide on apoptosis of immune organ induced by selenium deficiency in chickens

Selenium is an essential element with antioxidant roles in immune regulation, but there is little understanding of how Se acts in apoptosis in the immune organs of birds. The aim of study was to evaluate the influence of Se deficiency on oxygen free radicals, NO and apoptosis in immune organ of chickens. 160 1-day-old chickens were randomly assigned to two groups of 80 each and were fed on a low-Se diet (0.032 mg/kg Se) or a control diet (0.282 mg/kg Se), respectively. OFR production in blood was determined on days 30, 45, 60 and 75, respectively. The iNOS-NO system activity in immune organ (thymus, spleen, bursa of fabricius) was identified by NO content and NOS activity assay on days 30, 45, 60 and 75, respectively. Apoptosis was measured by DNA ladder analysis, ultrastructural observations, TdT-mediated dUTP nick end labeling TUNEL assay and flow cytometric analysis of apoptotic DNA. The transcription of factor-associated suicide, caspase-3 mRNA was tested by fluorescence quantitative PCR. The results showed that OFR production, NO and inducible NO synthases (iNOS) activity in the low-Se group were significantly increased (p < 0.05) than in the control group. In addition, apoptosis was observed in chicken immune organ in the low-Se group. The degree and the number of apoptotic cells rose in a time-dependent manner. The expression of Fas and caspase-3 mRNA increased (p < 0.05) than in the control group. It indicated that the oxidative stress and NO played a causative role in the apoptosis of immune tissues induced by selenium deficiency.

Effects of oxidative stress on immunosuppression induced by selenium deficiency in chickens

Selenium (Se) is an important nutritional trace element possessing immune-stimulatory properties. The aim of this 75-day study was to investigate effect of oxidative stress on immunosuppression induced by selenium deficiency by determining antioxidative function, morphological changes, DNA damage, and immune function in immune organ of chickens. One hundred sixty 1-day-old chickens (egg-type birds) were randomly assigned to two groups of 80 each and were fed on a low-Se diet (0.032 mg/kg Se) or a control diet (0.282 mg/kg Se, sodium selenite), respectively. Se contents in blood and immune organ (thymus, spleen, bursa of Fabricius) were determined on days 30, 45, 60, and 75, respectively. Antioxidative function was examined by total antioxidant capacity (T-AOC), superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), and xanthine oxidase (XOD), and oxidative damage was examined by malondialdehyde (MDA) detection. DNA damage was measured by comet assay, and immune function was examined by determining serum interleukin-1β (IL-1β), interleukin-2 (IL-2), and tumor necrosis factor (TNF) contents. The results showed that Se concentrations in the low-Se group were significantly lower (P < 0.05) than in the control group. Low-Se diet caused a decrease in the activities of T-AOC, SOD, GSH-Px, and an increase in XOD activity and MDA content. Pathological lesions and DNA damage of immune tissues were observed in low-Se group, while the serum IL-1β and IL-2 contents decreased, and TNF content increased. The present study demonstrated that chickens fed deficient in Se diets exhibited lesions in immune organs, decreased serum IL-1β, IL-2 content, and serum TNF content, indicating that oxidative stress inhibited the development of immune organs and finally impaired the immune function of chickens.

Low selenium diet alters cell cycle phase, apoptotic population and modifies oxidative stress markers of spleens in broilers

The purpose of this 42-day study was to investigate the effects of low selenium (Se) on histopathological changes of spleen, cell cycle and apoptosis of splenocytes, and oxidative status of the spleen. One hundred twenty 1-day-old avian broilers were randomly divided into two groups of 60 each and were fed on a low Se diet (0.0342 mg/kg Se) or a control diet (0.2 mg/kg Se), respectively. The weight and relative weight of the spleen were significantly decreased in the low Se group when compared with those of the control group. Histopathologically, splenic lesions in low-Se chicken were characterized by lymphocyte depletion and congestion of red pulp. As measured by flow cytometry, splenocytes in G(0)/G(1) phase were significantly increased, while splenocytes in S phase and G(2) + M phase were obviously decreased in the low Se group. The percentage of apoptotic splenocytes was greatly increased in the low Se group when compared with that of control group. At the same time, the occurrence frequencies of apoptotic splenocytes was markedly increased in the low Se group with the appearance of condensed nucleus ultrastructurally. Oxidative stress in the spleens of the low Se group was evidenced by decrease in glutathione peroxidase and catalase activities and increase in malondialdehyde contents. The results showed that low Se diet intake caused increased apoptosis, arrested cell cycle, and obvious oxidative stress, which provided a possible pathway for the injured structure and immune function of the spleen in chickens.

Low-selenium diet induces cell cycle arrest of thymocytes and alters serum IL-2 content in chickens

The purpose of this 42-day study was to investigate the effects of low selenium (Se) on cellular immune function by determining cell cycle of thymus, serum IL-2 content, and mitogenesis of peripheral blood T-lymphocytes. One hundred twenty 1-day-old Avian broilers were randomly assigned to two groups of 60 each and were fed on a low-Se diet (0.0342 mg/kg Se) or a control diet (0.2 mg/kg Se), respectively. Cell cycle analysis by flow cytometry showed that low-Se diet caused an increase in G(0)G(1) phase cells that corresponded to a decrease in S-phase cells in thymus. Ultrastructurally, mitochondria injury and increased apoptotic cells with condensed nuclei were observed. Low-Se diet decreased the serum IL-2 contents and mitogenesis of peripheral blood lymphocytes to concanavalin A in comparison with those of control group. These data indicate that low-Se diet inhibits the development of thymus by arresting the cell cycle and decreasing the IL-2 content.