Immunomodulatory effect of low molecular-weight seleno-aminopolysaccharides in intestinal epithelial cells

Humic acid chelated selenium is suitable for wheat biofortification

BACKGROUND

Selenium rich bread is a good carrier of selenium, but the inorganic selenium used in the actual production process is toxic. It is necessary to develop a new green bread production technology. The extraction and utilization of humic acid chelated selenium from selenium-rich soil is beneficial for reducing resource waste and pollution without destroying the soil ecosystem in selenium-deficient areas. Sodium selenite and nanoselenium were selected as controls because they are commonly used as selenium agronomic enhancers in production.

RESULTS

Humic acid chelated selenium can be absorbed and accumulated by wheat leaves, and humic acid chelated selenium had no significant effect on wheat yield, which was also shown in the treatments with nanoselenium and sodium selenite. Excessive accumulation of selenium in wheat grains can lead to a deterioration of processing quality. Among them, the use of excessive nanoselenium at the filling stage inhibited the accumulation of wheat grain protein, whereas humic acid chelated selenium is beneficial to grain protein accumulation and has the least negative effect on the processing quality. The accumulation of excessive selenium in wheat seeds had a negative effect on seed germination and growth; specifically, the seed vigor of wheat treated with humic acid chelated selenium was higher than that of untreated wheat.

CONCLUSION

Humic acid chelated selenium is particularly suitable for the whole process of Se-enriched bread wheat production. The seed vigour of wheat treated with humic acid chelated selenium, which supplied a moderate amount of selenium, was higher than that of untreated wheat. Conversely, the accumulation of excessive selenium in wheat seeds reduced germination and seedling growth. © 2023 Society of Chemical Industry.

Nano selenium-enriched probiotic Lactobacillus enhances alum adjuvanticity and promotes antigen-specific systemic and mucosal immunity

Nano selenium-enriched probiotics have been identified to improve immune responses, such as alleviating inflammation, antioxidant function, treatment of tumors, anticancer activity, and regulating intestinal flora. However, so far, there is little information on improving the immune effect of the vaccine. Here, we prepared nano selenium-enriched Levilactobacillus brevis 23017 (SeL) and heat-inactivated nano selenium-enriched L. brevis 23017 (HiSeL) and evaluated their immune enhancing functions on the alum-adjuvanted, inactivated Clostridium perfringens type A vaccine in mouse and rabbit models, respectively. We found that SeL enhanced immune responses of the vaccine by inducing a more rapid antibody production, eliciting higher immunoglobulin G (IgG) antibody titers, improving secretory immunoglobulin A (SIgA) antibody level and cellular immune response, and regulating Th1/Th2 immune response, thus helping to induce better protective efficacy after challenge. Moreover, we confirmed that the immunoenhancement effects are related to regulating oxidative stress, cytokine secretion, and selenoprotein expression. Meanwhile, similar effects were observed in HiSeL. In addition, they show enhanced humoral immune response at 1/2 and 1/4 standard vaccine doses, which confirms their prominent immune enhancement effect. Finally, the effect of improving vaccine immune responses was further confirmed in rabbits, which shows that SeL stimulates the production of IgG antibodies, generates α toxin-neutralizing antibodies rapidly, and reduces the pathological damage to intestine tissue. Our study demonstrates that nano selenium-enriched probiotics improve the immune effect of the alum adjuvants vaccine and highlight its potential usage in remedying the disadvantages of alum adjuvants.

Toward improved human health: efficacy of dietary selenium on immunity at the cellular level

Selenium, an essential trace element in the body, participates in various biological processes in the form of selenoproteins. In humans, a suitable concentration of selenium is essential for maintaining normal cellular function. Decreased levels of selenoproteins can lead to obstruction of the normal physiological functions of tissues and cells and even death. In addition, the level of selenium in the body affects cellular immunity, humoral immunity, and the balance between type 2 and type 1 helper T cells. Selenium can affect the immune function of the body through the reactive oxygen species (ROS), NF-κB, ferroptosis and NRF2 pathways. This paper reviews the immune effect of selenium on the body and the process of signal transduction and aims to serve as a reference for follow-up studies of immune function and research on the development of new selenium compounds and active targets.

Selenomethionine ameliorates LPS-induced intestinal immune dysfunction in chicken jejunum

Selenomethionine (SeMet) is a widely used food supplement. However, the research on the effect of SeMet on intestinal immune function is not enough. Therefore, in this experiment, SeMet was added to the diet of chickens, and lipopolysaccharide (LPS) was used as harmful stimulation to study the effect of SeMet on intestinal immune function in chickens. We chose chicken jejunum as the research object. The results showed that LPS treatment decreased the expressions of selenoproteins and induced inflammatory reaction, cytokine disorder, decreases of immunoglobulin levels, heat shock protein expression disorder, and decreases of defensin expression levels in jejunum. However, dietary SeMet can effectively alleviate the above injury caused by LPS. Our results showed that SeMet could improve the intestinal immunity in chickens, and feeding SeMet could alleviate the intestinal immune dysfunction caused by LPS. The application range of SeMet in feed can be roughly given through our experiment; i.e. 0.35-0.5 mg/kg SeMet was effective. We speculated that dietary SeMet could effectively alleviate the intestinal immune dysfunction caused by harmful stimulation and help to resist the further damage caused by harmful stimulation.

Low Molecular Seleno-Aminopolysaccharides Protect the Intestinal Mucosal Barrier of Rats under Weaning Stress

Low molecular seleno-aminopolysaccharide (LSA) was synthesized with sodium selenite and low molecular aminopolysaccharide (LA), which is an organic selenium compound. This study is aimed to investigate the protective effect of LSA on the intestinal mucosal barrier in weaning stress rats by detecting the intestinal tissue morphology and function, mucosal thickness and permeability, the structure of MUC2, antioxidant index, the expression level of intracellular transcription factor NF-E2-related factor 2 (Nrf2), and its related factors. The results showed that LSA significantly increased the height of intestinal villi (p < 0.05) and increased the thickness of intestinal mucosa and the number of goblet cells, which indicated that LSA has a protective effect on the intestinal mucosal barrier that is damaged by weaning. Moreover, LSA significantly reduced the level of DAO, D-LA, and LPS compared with the weaning group (p < 0.05), which indicated that LSA reduced the intestinal damage and permeability of weaning rats. In addition, LSA could increase the number and length of glycans chains and the abundance of acid glycans structures in the MUC2 structure, which indicated that LSA alleviated the changes of intestinal mucus protein structure. LSA significantly increased the levels of GSH-Px, SOD, LDH, and CAT, while it decreased the level of MDA in serum and intestinal tissue, which suggested that LSA significantly enhanced the antioxidant capacity and reduced oxidative stress of weaning rats. RT-PCR results showed that LSA significantly increased the expression level of antioxidant genes (GSH-Px, SOD, Nrf2, HO-1), glycosyltransferase genes (GalNT1, GalNT3, GalNT7) and mucin gene (MUC2) in intestinal mucosa (p < 0.05). The results of western blot showed that the LSA activated the Nrf2 signaling pathway by down-regulating the expression of Keap1and up-regulating the expression of Nrf2, and protected the intestinal mucosa from oxidative stress. Overall, LSA could play a protective role in intestinal mucosal barrier of weaning rats by activating the Nrf2 pathway and alleviating the alnormal change of mucin MUC2.

Protective Effect of Low Molecular Weight Seleno-Aminopolysaccharide on the Intestinal Mucosal Oxidative Damage

Low molecular weight seleno-aminopolysaccharide (LSA) is an organic selenium compound comprising selenium and low molecular weight aminopolysaccharide (LA), a low molecular weight natural linear polysaccharide derived from chitosan. LSA has been found to exert strong pharmacological activity. In this study, we aimed to investigate the protective effect of LSA on intestinal mucosal oxidative stress in a weaning piglet model by detecting the growth performance, intestinal mucosal structure, antioxidant indices, and expression level of intracellular transcription factor nuclear factor erythroid 2-related factor 2 (Nrf2) and its related factors. Our results indicated that LSA significantly increased the average daily gain and feed/gain (p < 0.05), suggesting that LSA can effectively promote the growth of weaning piglets. The results of scanning electron microscope (SEM) microscopy showed that LSA effectively reduced intestinal damage, indicating that LSA improved the intestinal stress response and protected the intestinal structure integrity. In addition, diamine oxidase (DAO) and d-lactic acid (d-LA) levels remarkably decreased in LSA group compared with control group (p < 0.05), suggesting that LSA alleviated the damage and permeability of weaning piglets. LSA significantly increased superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSH-Px), and total antioxidant capacity (T-AOC) levels, but decreased malondialdehyde (MDA) level, indicating that LSA significantly enhanced the antioxidant capacity and reduced oxidative stress in weaning piglets. RT-PCR results showed that LSA significantly increased GSH-Px1, GSH-Px2, SOD-1, SOD-2, CAT, Nrf2, HO-1, and NQO1 gene expression (p < 0.05). Western blot analysis revealed that LSA activated the Nrf2 signaling pathway by downregulating the expression of Keap1 and upregulating the expression of Nrf2 to protect intestinal mucosa against oxidative stress. Collectively, LSA reduced intestinal mucosal damage induced by oxidative stress via Nrf2-Keap1 pathway in weaning stress of infants.

A Summary of New Findings on the Biological Effects of Selenium in Selected Animal Species-A Critical Review

Selenium is an essential trace element important for many physiological processes, especially for the functions of immune and reproductive systems, metabolism of thyroid hormones, as well as antioxidant defense. Selenium deficiency is usually manifested by an increased incidence of retention of placenta, metritis, mastitis, aborts, lowering fertility and increased susceptibility to infections. In calves, lambs and kids, the selenium deficiency demonstrates by WMD (white muscle disease), in foals and donkey foals, it is associated with incidence of WMD and yellow fat disease, and in pigs it causes VESD (vitamin E/selenium deficiency) syndrome. The prevention of these health disorders can be achieved by an adequate selenium supplementation to the diet. The review summarizes the survey of knowledge on selenium, its biological significance in the organism, the impact of its deficiency in mammalian livestock (comparison of ruminants vs. non-ruminants, herbivore vs. omnivore) and possibilities of its peroral administration. The databases employed were as follows: Web of Science, PubMed, MEDLINE and Google Scholar.