Selenium Deficiency Deteriorate the Inflammation of S. aureus Infection via Regulating NF-κB and PPAR-γ in Mammary Gland of Mice

Enhancing bovine immune, antioxidant and anti-inflammatory responses with vitamins, rumen-protected amino acids, and trace minerals to prevent periparturient mastitis

Mastitis, the inflammatory condition of mammary glands, has been closely associated with immune suppression and imbalances between antioxidants and free radicals in cattle. During the periparturient period, dairy cows experience negative energy balance (NEB) due to metabolic stress, leading to elevated oxidative stress and compromised immunity. The resulting abnormal regulation of reactive oxygen species (ROS) and reactive nitrogen species (RNS), along with increased non-esterified fatty acids (NEFA) and β-hydroxybutyric acid (BHBA) are the key factors associated with suppressed immunity thereby increases susceptibility of dairy cattle to infections, including mastitis. Metabolic diseases such as ketosis and hypocalcemia indirectly contribute to mastitis vulnerability, exacerbated by compromised immune function and exposure to physical injuries. Oxidative stress, arising from disrupted balance between ROS generation and antioxidant availability during pregnancy and calving, further contributes to mastitis susceptibility. Metabolic stress, marked by excessive lipid mobilization, exacerbates immune depression and oxidative stress. These factors collectively compromise animal health, productive efficiency, and udder health during periparturient phases. Numerous studies have investigated nutrition-based strategies to counter these challenges. Specifically, amino acids, trace minerals, and vitamins have emerged as crucial contributors to udder health. This review comprehensively examines their roles in promoting udder health during the periparturient phase. Trace minerals like copper, selenium, and calcium, as well as vitamins; have demonstrated significant impacts on immune regulation and antioxidant defense. Vitamin B12 and vitamin E have shown promise in improving metabolic function and reducing oxidative stress followed by enhanced immunity. Additionally, amino acids play a pivotal role in maintaining cellular oxidative balance through their involvement in vital biosynthesis pathways. In conclusion, addressing periparturient mastitis requires a holistic understanding of the interplay between metabolic stress, immune regulation, and oxidative balance. The supplementation of essential amino acids, trace minerals, and vitamins emerges as a promising avenue to enhance udder health and overall productivity during this critical phase. This comprehensive review underscores the potential of nutritional interventions in mitigating periparturient bovine mastitis and lays the foundation for future research in this domain.

Effects of Gestational Diabetes Mellitus and Selenium Deficiency on the Offspring Growth and Blood Glucose Mechanisms of C57BL/6J Mice

This study aimed to explore the effects and mechanisms of maternal gestational diabetes mellitus (GDM) and selenium (Se) deficiency on the growth and glucose metabolism of offspring. Female C57BL/6J mice were divided into four groups as follows: a control group, a GDM group, a Se deficiency group, and a GDM with Se deficiency group. GDM animal models were established via S961. Pregnant mice fed their offspring until weaning. Then, offspring continued to be fed with a basic diet until adulthood. Body weight and fasting blood glucose were measured weekly. Se content, oxidative stress indicators, and the protein expression of the PI3K/Akt signaling pathway were detected. GDM increased susceptibility to obesity in lactating offspring, with gender differences observed in adult offspring. The effect of Se deficiency on SOD activity only appeared in female offspring during adulthood but was shown in male offspring during weaning though it disappeared during adulthood. GDM and Se deficiency increased the risk of abnormal glucose metabolism in female offspring from weaning to adulthood but gradually decreased in male offspring. The influence on the expression of PI3K/Akt signaling pathway-related proteins showed the same trend. GDM and Se deficiency affected the growth and glucose metabolism of offspring through oxidative stress and PI3K/Akt signaling pathway-related proteins, and gender differences existed.

Bisphenol A aggravate selenium deficiency-induced apoptosis via miR-215-3p/Dio1 to activate ROS/PI3K/AKT pathway in chicken arterial

Both bisphenol A (BPA) and selenium (Se) deficiency can affect the expression of microRNAs (miRNAs), which can specifically regulate its target mRNA and induce apoptosis, and play a significant role in cardiovascular injury diseases. To explore the mechanism of apoptosis induced by BPA and Se deficiency in chicken arterial endothelial tissue and the role of miRNAs in this process, the model of BPA exposure/Se deficiency in chicken and PAEC cells have been employed. The targeting relationship between miR-215-3p and iodothyronine deiodinase 1 (Dio1) in PAEC was verified by double luciferase gene report. The level of miR-215-3p was detected by qRT-PCR. The oxidative stress level of arterial endothelial cells was detected by oxidative stress kit and DCFH-DA probe method. The PI3K/AKT pathway, mitochondrial dynamics, and apoptosis-related genes were detected by qRT-PCR and western blot. The mitochondrial ATP level and nitric oxide synthases (NOSs) level were detected with the kit. TUNEL, acridine orange/ethidium bromide, and flow cytometry were used to detect the level of apoptosis. The results showed that BPA exposure and Se deficiency led to overexpression of miR-215-3p, aggravated oxidative stress, inhibited activation of PI3K/AKT pathway, promoted mitochondrial division, increased expression of apoptosis related genes, and finally led to apoptosis of chicken arterial endothelial cells. We also established knockdown/overexpression models of miR-215-3p and Dio1 in vitro, and found that overexpression of miR-215-3p and knockout of Dio1 can induce apoptosis. Interestingly, miR-215-3p-Inhibitor and N-acetyl- l-cysteine (NAC) partially prevented apoptosis caused by BPA exposure and Se deficiency, and LY294002 aggravated apoptosis. These results suggest that BPA exposure aggravates the apoptosis of Se deficient arterial endothelial cells in chickens by regulating the ROS/PI3K/AKT pathway activated by miR-215-3p/Dio1. The miR-215-3p/Dio1 axis provides a new way to understand the toxic mechanism of BPA exposure and Se deficiency, and reveals a new regulatory model of apoptosis damage in vascular diseases.

Selenomethionine alleviates NF-κB-mediated inflammation in bovine mammary epithelial cells induced by Escherichia coli by enhancing autophagy

Autophagy is crucial for the maintenance of homeostasis under stimuli related to infection. Selenium (Se) plays variable roles in defence against infection and Selenomethionine (Se-Met) is a common Se supplementation. This study aimed to understand whether Se-Met could regulate the nuclear factor-kappa B (NF-κB) signaling pathway through autophagy. Mammary alveolar cell-T (MAC-T) was challenged with Escherichia coli (E. coli). Western blotting and real-time quantitative PCR (RT-qPCR) were used to detect the protein expression and mRNA expression of cytokines. Immunofluorescence assays were performed to observe the expression of intracellular LC3. The results showed that E. coli inhibited autophagy by decreasing the LC3-Ⅱ protein levels, and the Atg5 and Beclin1 protein levels were increased after 4 h. Infection also decreased the number of LC3 puncta. E. coli increased the phosphorylation of p65 and IκBα protein. Concomitantly, the levels of interleukin (IL)-1β, IL-6, IL-8 and tumour necrosis factor (TNF)-α mRNA increased at 3 and 4 h post-infection. We further explored the regulatory role of autophagy on NF-κB-mediated inflammation with autophagy modulators and shAtg5. The results indicated that the autophagy activator reduced the phosphorylation of p65 and IκBα and the mRNA expression of IL-1β, IL-6, IL-8 and TNF-α. Additionally, activating autophagy weakened the adhesion to MAC-T of E. coli. Autophagy inhibitors exacerbated NF-κB-mediated inflammation and strengthened the adhesion of E. coli to cells. We then examined the effects of Se-Met on NF-κB-mediated inflammation through autophagy. The data suggested that Se-Met enhanced LC3-II expression, inhibited the E. coli-induced phosphorylation of p65 and IκBα, and suppressed the adhesion ability of E. coli to MAC-T and that the effects of Se-Met in attenuating NF-κB-mediated inflammation were partially blocked by an autophagy inhibitor. In summary, Se-Met alleviated NF-κB-mediated inflammation induced by E. coli by enhancing autophagy in bovine mammary epithelial cells.

Role of Selenium and Vitamins E and B9 in the Alleviation of Bovine Mastitis during the Periparturient Period

Mastitis (inflammation of the mammary gland) commonly occurs in dairy cattle during the periparturient period (transition period), in which dairy cattle experience physiological and hormonal changes and severe negative energy balance, followed by oxidative stress. To maintain successful lactation and combat negative energy balance (NEB), excessive fat mobilization occurs, leading to overproduction of reactive oxygen species (ROS). Excessive fat mobilization also increases the concentrations of nonesterified fatty acids (NEFA) and β-hydroxybutyric acid (BHB) during the periparturient period. In addition, the excessive utilization of oxygen by cellular respiration in the mammary causes abnormal production of oxidative stress (OS). OS impairs the immunity and anti-inflammatory efficiency of periparturient dairy cattle, increasing their susceptibility to mastitis. To alleviate oxidative stress and subsequent mastitis, antioxidants are supplemented to dairy cattle from an external source. Extensive studies have been conducted on the supplementation of selenium (Se) and vitamins E and B9 to mitigate mastitis during the transition period in dairy cattle. Altogether, in the current review, we discuss the research development on bovine mastitis and its major causes, with special emphasis on oxidative stress during the transition period. Moreover, we discuss the antioxidant, immunoregulatory, and anti-inflammatory properties of Se and vitamins E and B9 and their role in the control of bovine mastitis in periparturient dairy cattle.

Protective Effects of Selenium Nanoparticle-Enriched Lactococcus lactis NZ9000 against Enterotoxigenic Escherichia coli K88-Induced Intestinal Barrier Damage in Mice

Composite microecological agents have received widespread attention due to their advantageous properties, including safety, multiple effects, and low cost. This study was conducted to evaluate the protective effects of selenium (Se) nanoparticle (SeNP)-enriched Lactococcus lactis NZ9000 (L. lactis NZ9000-SeNPs) against enterotoxigenic Escherichia coli (ETEC) K88-induced intestinal barrier damage in C57BL/6 mice. The oral administration of L. lactis NZ9000-SeNPs significantly increased the villus height and the number of goblet cells in the ileum; reduced the levels of serum and ileal interleukin-1β (IL-1β), tumor necrosis factor alpha (TNF-α), and interferon gamma (IFN-γ); and increased the activities of thioredoxin reductase (TrxR) and glutathione peroxidase (GSH-Px) compared with the ETEC K88-infected group not treated with L. lactis NZ9000-SeNPs. In addition, L. lactis NZ9000-SeNPs significantly attenuated the reduction of the expression levels of occludin and claudin-1, dysbiosis of the gut microbiome, and activation of the Toll-like receptor (TLR)/nuclear factor kappa B (NF-κB)-mediated signaling pathway induced by ETEC K88. These findings suggested that L. lactis NZ9000-SeNPs may be a promising and safe Se supplement for food or feed additives. IMPORTANCE The beneficial effects of microecological agents have been widely proven. Se, which is a nutritionally essential trace element for humans and animals, is incorporated into selenoproteins that have a wide range of pleiotropic effects, ranging from antioxidant to anti-inflammatory effects. However, sodium selenite, a common addition form of Se in feed and food, has disadvantages such as strong toxicity and low bioavailability. We investigated the protective effects of L. lactis NZ9000-SeNPs against ETEC K88-induced intestinal barrier injury in C57BL/6 mice. Our results show that L. lactis NZ9000-SeNPs effectively alleviate ETEC K88-induced intestinal barrier dysfunction. This study highlights the importance of developing a promising and safe Se supplement for the substitution of sodium selenite applied in food, feed, and biomedicine.

Preparation, characterization, and in vivo evaluation of anti-inflammatory activities of selenium nanoparticles synthesized by Kluyveromyces lactis GG799

Selenium (Se) is an essential micronutrient that has implications in human diseases, including inflammatory bowel disease (IBD), especially with respect to Se deficiencies. Recently, selenium nanoparticles (SeNPs) have attracted significant attention due to their diversity of biological activities and unique advantages including low toxicity and high biological availability. In this study, an eco-friendly, efficient and low-cost method for synthesis of SeNPs by Kluyveromyces lactis GG799 (K. lactis GG799) was established, and the SeNPs were investigated for their physicochemical properties and anti-inflammatory activities in vivo. K. lactis GG799 was able to successfully transform sodium selenite into bright-red SeNPs with particle sizes of 80 and 150 nm and the nanoparticles accumulated intracellularly. Upon isolation, the SeNPs were found to be mainly capped by proteins and polysaccharides by components analysis. Dietary supplementation with 0.6 mg kg-1 Se (in the form of biogenic SeNPs) effectively attenuated dextran sulphate sodium (DSS)-induced ulcerative colitis (UC) in mice by alleviating oxidative stress and intestinal inflammation. These findings suggested that SeNPs synthesized by K. lactis GG799 may be a promising and safe Se supplement for the prevention and treatment of IBD.

Germanium Reduces Inflammatory Damage in Mammary Glands During Lipopolysaccharide-Induced Mastitis in Mice

Ge is a trace element needed for good nutrition and health protection in animals and humans. Ge can be consumed by drinking or eating or administered by injection and transferred with the blood to exert pharmacological activities. The blood is important in the formation of milk. Mastitis is a serious health hazard in animals and humans. The present study explored the effect of Ge on mastitis and the potential underlying mechanism. A mastitis mouse model was established with LPS. mMECs were prepared for study in vitro. Histopathological changes showed that Ge had a protective effect on mammary gland tissues. Ge inhibited MPO activity to reduce inflammatory cell infiltration during mastitis. ELISA and qPCR results for tissues and cells showed that the expression of TNF-α, IL-1β, and IL-6 was decreased and that of IL-10 was increased by Ge in a dose-dependent manner in mastitis. An analysis of protein phosphorylation was performed with sandwich ELISAs for both tissues and mMECs. The results showed that Ge significantly inhibited the phosphorylation of IκB, NF-κB p65, p38, ERK, and JNK, which was dramatically increased by LPS. These results demonstrate that Ge has an inhibitory effect on inflammation that protects mammary gland tissues by inhibiting NF-κB and MAPK pathway activation and reducing TNF-α, IL-1β, and IL-6 expression. Ge may be an effective clinical treatment for mastitis and other inflammatory diseases.

The protective effect of selenium on the lipopolysaccharide-induced oxidative stress and depressed gene expression related to milk protein synthesis in bovine mammary epithelial cells

The objective of this study was to determine the effects of selenium (Se) on antioxidative function and the synthesis of milk protein in bovine mammary epithelial cells (BMECs). Two experiments were conducted using a single-factor completely randomized design study. In part I, BMECs were randomly divided into seven groups: control (without Se) and six Se treatments (10, 20, 50, 100, 150, and 200 nmol/L). In part II, based on the results of part I, we used lipopolysaccharide (LPS) as the induced stress source to analyze the protective effect of Se on LPS-induced oxidative damage and the influence on milk protein synthesis of BMECs. BMECs were randomly divided into eight groups: control (without Se and LPS), LPS treatment (only LPS), and six Se treatments with LPS (LS10 to LS200). Treatment of BMECs with Se was found to significantly improve cell proliferation and antioxidant function. LPS could induce oxidative damage which significantly inhibited cell proliferation and antioxidant function in BMECs. Se had a protective effect on the oxidative damage of BMECs induced by LPS. Additionally, our results indicated that LPS damage downregulated the gene expression of milk protein synthesis. Se effectively relieved the inhibition due to LPS-induced oxidative damage on the synthesis of milk protein, and Se concentrations of 50 to 200 nmol/L showed the best effect. In conclusion, Se at concentrations of 50 to 100 nmol/L is better for antioxidant function but had no effect on milk protein synthesis in healthy BMECs. Se ameliorated the damage caused by LPS-induced by improving levels of antioxidant markers and upregulating milk protein synthesis and the expression of genes associated with milk protein in BMECs.

Trace Elements, PPARs, and Metabolic Syndrome

Metabolic syndrome (MetS) is a constellation of metabolic derangements, including central obesity, insulin resistance, hypertension, glucose intolerance, and dyslipidemia. The pathogenesis of MetS has been intensively studied, and now many factors are recognized to contribute to the development of MetS. Among these, trace elements influence the structure of proteins, enzymes, and complex carbohydrates, and thus an imbalance in trace elements is an independent risk factor for MetS. The molecular link between trace elements and metabolic homeostasis has been established, and peroxisome proliferator-activated receptors (PPARs) have appeared as key regulators bridging these two elements. This is because on one hand, PPARs are actively involved in various metabolic processes, such as abdominal adiposity and insulin sensitivity, and on the other hand, PPARs sensitively respond to changes in trace elements. For example, an iron overload attenuates hepatic mRNA expression of Ppar-α; zinc supplementation is considered to recover the DNA-binding activity of PPAR-α, which is impaired in steatotic mouse liver; selenium administration downregulates mRNA expression of Ppar-γ, thereby improving lipid metabolism and oxidative status in the liver of high-fat diet (HFD)-fed mice. More importantly, PPARs' expression and activity are under the control of the circadian clock and show a robust 24 h rhythmicity, which might be the reasons for the side effects and the clinical limitations of trace elements targeting PPARs. Taken together, understanding the casual relationships among trace elements, PPARs' actions, and the pathogenesis of MetS is of great importance. Further studies are required to explore the chronopharmacological effects of trace elements on the diurnal oscillation of PPARs and the consequent development of MetS.

Role of Selenoproteins in Bacterial Pathogenesis

The trace element selenium is an essential micronutrient that plays an important role in maintaining homeostasis of several tissues including the immune system of mammals. The vast majority of the biological functions of selenium are mediated via selenoproteins, proteins which incorporate the selenium-containing amino acid selenocysteine. Several bacterial infections of humans and animals are associated with decreased levels of selenium in the blood and an adjunct therapy with selenium often leads to favorable outcomes. Many pathogenic bacteria are also capable of synthesizing selenocysteine suggesting that selenoproteins may have a role in bacterial physiology. Interestingly, the composition of host microbiota is also regulated by dietary selenium levels. Therefore, bacterial pathogens, microbiome, and host immune cells may be competing for a limited supply of selenium. Elucidating how selenium, in particular selenoproteins, may regulate pathogen virulence, microbiome diversity, and host immune response during a bacterial infection is critical for clinical management of infectious diseases.

The Effects of Selenium Supplementation on Gene Expression Related to Insulin and Lipid in Infertile Polycystic Ovary Syndrome Women Candidate for In Vitro Fertilization: a Randomized, Double-Blind, Placebo-Controlled Trial

This study was conducted to evaluate the effects of selenium supplementation on gene expression related to insulin and lipid in infertile women with polycystic ovary syndrome (PCOS) candidate for in vitro fertilization (IVF). This randomized double-blind, placebo-controlled trial was conducted among 40 infertile women with PCOS candidate for IVF. Subjects were randomly allocated into two groups to intake either 200-μg selenium (n = 20) or placebo (n = 20) per day for 8 weeks. Gene expression levels related to insulin and lipid were quantified in lymphocytes of women with PCOS candidate for IVF with RT-PCR method. Results of RT-PCR demonstrated that after the 8-week intervention, compared with the placebo, selenium supplementation upregulated gene expression of peroxisome proliferator-activated receptor gamma (PPAR-γ) (1.06 ± 0.15-fold increase vs. 0.94 ± 0.18-fold reduction, P = 0.02) and glucose transporter 1 (GLUT-1) (1.07 ± 0.20-fold increase vs. 0.87 ± 0.18-fold reduction, P = 0.003) in lymphocytes of women with PCOS candidate for IVF. In addition, compared with the placebo, selenium supplementation downregulated gene expression of low-density lipoprotein receptor (LDLR) (0.88 ± 0.17-fold reduction vs. 1.05 ± 0.22-fold increase, P = 0.01) in lymphocytes of women with PCOS candidate for IVF. We did not observe any significant effect of selenium supplementation on gene expression levels of lipoprotein(a) [LP(a)] in lymphocytes of women with PCOS candidate for IVF. Overall, selenium supplementation for 8 weeks in lymphocytes of women with infertile PCOS candidate for IVF significantly increased gene expression levels of PPAR-γ and GLUT-1 and significantly decreased gene expression levels of LDLR, but did not affect LP(a).

CLINICAL TRIAL REGISTRATION NUMBER

http://www.irct.ir : IRCT201704245623N113.

Selenium Deficiency Augments the Levels of Inflammatory Factors and Heat Shock Proteins via the Redox Regulatory Pathway in the Skeletal Muscles of Mice

Dietary selenium (Se) deficiency is known to cause myodynia syndrome and Se influences immune responses by changing the expression of inflammatory cytokines and heat shock proteins (Hsps), but the details are not completely elucidated. In the present study, 72 1-day-old mice were divided into two groups; the first group was fed a Se-sufficient diet, while the second group was fed a Se-deficient diet. Skeletal muscles and blood samples were taken from all mice after 42 days of treatment. The activities of glutathione peroxidase (GPX) and glutathione (GSH), mRNA and protein expression levels of inflammatory cytokines (including TNF-α, inducible NO synthase, cyclooxygenase-2, and prostaglandin E synthases), protein expression levels of NF-κB, and the mRNA expression levels of Hsps in the skeletal muscles of mice were examined. The results showed that GPX and GSH activities were decreased, while the mRNA and protein expression levels of inflammatory cytokines and the mRNA levels of Hsps were increased by Se deficiency in mouse skeletal muscles. In the present study, the protective role of Se in oxidative stress, inflammatory cytokines, and Hsps in the skeletal muscles of mice was summarized.

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.

Selenium Deficiency-Induced Inflammation and Increased Expression of Regulating Inflammatory Cytokines in the Chicken Gastrointestinal Tract

Selenium (Se), a nutritionally essential trace element, plays an important role in various aspects of health for a wide range of species, including birds. Se deficiency inhibits the growth of immune organs and decreases immune function, leading to many inflammatory diseases. The present study determined the effects and mechanism of dietary Se deficiency on gastrointestinal tract tissue inflammation. The histopathological changes showed that Se deficiency induced inflammatory lesions in the gastrointestinal tract tissues (glandular stomach, gizzard, duodenum, small intestine, and rectum). The expression levels of PTGE (prostagland E synthase), COX-2 (cyclooxygenase-2), TNF-α (tumor necrosis factor α), and NF-κB (nuclear transfer factor κB) in the gastrointestinal tract tissues (glandular stomach, gizzard, duodenum, small intestine, and rectum) were determined by qPCR on days 15, 25, 35, 45, and 55, respectively. The results showed that Se deficiency induced high expression levels of PTGE, COX-2, TNF-α, and NF-κB in the gastrointestinal tract tissues. The effects were more obvious in the duodenum and small intestine than those in the glandular stomach, gizzard, and rectum. In addition, the expression levels of these proteins in the gastrointestinal tract tissue increased in a time-dependent manner with Se deficiency feeding time. Furthermore, Se deficiency induced the production of pro-inflammatory factors, thus aggravating inflammatory lesions in the gastrointestinal tract. The effect of Se deficiency on inflammation and other gastrointestinal tract diseases should be further studied.