Selenium and Selenoproteins in Immune Mediated Thyroid Disorders

Clinical comparative efficacy and therapeutic strategies for the Hashimoto's thyroiditis: A systematic review and network meta-analysis

Ethnopharmacological relevance

Vitamin D (VD), selenium preparations (Se), and thyroid hormone replacement therapy are commonly used to treat Hashimoto thyroiditis (HT). Increasing evidence suggests that traditional Chinese medicine (TCM) is an effective therapeutic strategy in the treatment of HT.

Aim of the study

This study aimed to investigate the efficacy and safety of commonly-used drugs for HT.

Materials and methods

A literature search was performed using PubMed, Web of Science, Cochrane Library, EMBASE, Chinese China National Knowledge Infrastructure (CNKI), Clinical Trial Registry (Chi CTR), China Science and Technology Journal Database (the VIP), Wanfang Database, and China Chinese Biomedical Database (CBM) from January 1, 2003, to December 31, 2022. The outcomes included TPOAb, TgAb, TSH, FT3, FT4, and adverse events. Our study was registered in PROSPERO (CRD42023449705).

Results

Sixty trials and 4719 participants were included, comparing 16 treatments: VD, Se, LT-4, Se + LT-4, HM, placebo + LT-4, HM + LT-4, Se + myolnositol, Se + VD, HM + Se, mannan peptide, LT-4+prednisone, Methimazole, Methimazole + HM, Tapazole + Propranolol, and placebo. We found that Chinese herbal medicine has significant effect vs. LT-4 [MD 0.10, 95 % confidence interval 0.02 to 0.50]) and LT-4+placebo [MD 0.10, 95 % confidence interval 0.01 to 0.77]) in reducing TPOAb. Although receiving LT-4+prednisone was not statistically significant, the treatment ranking showed that this combination therapy had the highest probability of reducing TPOAb levels (72.8 %). In addition, the effect of Se plus LT-4 was not statistically significant; however, the treatment ranking showed that this combination therapy had the highest probability (78.6 %) of reducing TgAb levels, followed by HM (64.0 %). Reports on side effects have mainly focused on the digestive and cardiovascular systems.

Conclusion

Our analyses showed that HM alone or in combination with other treatments for patients with HT can improve the side effects of other drugs, enhance efficacy, and maybe the most effective option for treating HT. However, there still need further verified using high-quality evidence.

Targeting Metabolic Diseases: The Role of Nutraceuticals in Modulating Oxidative Stress and Inflammation

The escalating prevalence of metabolic and cardiometabolic disorders, often characterized by oxidative stress and chronic inflammation, poses significant health challenges globally. As the traditional therapeutic approaches may sometimes fall short in managing these health conditions, attention is growing toward nutraceuticals worldwide; with compounds being obtained from natural sources with potential therapeutic beneficial effects being shown to potentially support and, in some cases, replace pharmacological treatments, especially for individuals who do not qualify for conventional pharmacological treatments. This review delves into the burgeoning field of nutraceutical-based pharmacological modulation as a promising strategy for attenuating oxidative stress and inflammation in metabolic and cardiometabolic disorders. Drawing from an extensive body of research, the review showcases various nutraceutical agents, such as polyphenols, omega-3 fatty acids, and antioxidants, which exhibit antioxidative and anti-inflammatory properties. All these can be classified as novel nutraceutical-based drugs that are capable of regulating pathways to mitigate oxidative-stress- and inflammation-associated metabolic diseases. By exploring the mechanisms through which nutraceuticals interact with oxidative stress pathways and immune responses, this review highlights their potential to restore redox balance and temper chronic inflammation. Additionally, the challenges and prospects of nutraceutical-based interventions are discussed, encompassing bioavailability enhancement, personalized treatment approaches, and clinical translation. Through a comprehensive analysis of the latest scientific reports, this article underscores the potential of nutraceutical-based pharmacological treatment modulation as a novel avenue to fight oxidative stress and inflammation in the complex landscape of metabolic disorders, particularly accentuating their impact on cardiovascular health.

Emerging Insights and Global Trends in the Relationship between Selenium and Thyroid Diseases: A Bibliometric Analysis

OBJECTIVE

Selenium, a significant trace element needed by the human body, is closely related to thyroid. Therefore, this study aimed to explore the status of selenium and thyroid diseases, analyze emerging insights, and predict future trends.

METHODS

Literature on selenium and thyroid included in the core database of Web of Science from January 1992 to October 2022 was retrieved. CiteSpace and VOSviewer software were used for visual analysis in terms of publication, author, country, institution, co-citation, and keywords.

RESULTS

A total of 1,142 works of literature were included after the screening, and the annual publication showed a fluctuating upward trend. The country and the institution with the highest publication volume were the United States and Charité Universitätsmedizin Berlin, respectively. In terms of authors, Schomburg L has formed a cooperative network and has published the largest number of papers and made great contributions in this field. The biggest cluster of keywords was trace elements, and the hot keywords in recent years were oxidative stress, Hashimoto's thyroiditis, cadmium, copper, etc. Conclusion: This paper analyzes the current status, insights, and trends of the studies on selenium and thyroid diseases by the method of bibliometrics and delivers ideas and methods for subsequent research in this field. The therapeutic effect of selenium on Hashimoto's thyroiditis is controversial and needs further research, and oxidative stress is also a research hotspot in this field. The crossstudy of multiple trace elements and diseases may be the development trend in the future.

Gut microbiota bridges dietary nutrients and host immunity

Dietary nutrients and the gut microbiota are increasingly recognized to cross-regulate and entrain each other, and thus affect host health and immune-mediated diseases. Here, we systematically review the current understanding linking dietary nutrients to gut microbiota-host immune interactions, emphasizing how this axis might influence host immunity in health and diseases. Of relevance, we highlight that the implications of gut microbiota-targeted dietary intervention could be harnessed in orchestrating a spectrum of immune-associated diseases.

Thyroid hormones and minerals in immunocorrection of disorders in autoimmune thyroid diseases

Thyroid hormones and essential elements iodine (I), selenium (Se), iron (Fe), copper (Cu), zinc (Zn), calcium (Ca), magnesium (Mg), etc. play an important role in the work of many organs and systems of the body, including the immune system and the thyroid gland, and a violation of their supply can be the cause of pathological changes in them. In pathology, the interaction between thyroid hormones (TG), minerals and the immune system is disturbed. The review of the literature examines the immunomodulatory role of TG, minerals, their properties, and their participation in the pathogenesis of autoimmune thyroid diseases (AITD). The study of the relationship between the excess or deficiency of minerals and AITD is described. The basis of the development of AITD - Hashimoto's thyroiditis (HT), Graves' disease (GD), Graves' ophthalmopathy (GO) is the loss of immune tolerance to thyroid antigens - thyroid peroxidase (TPO), thyroglobulin (Tg) and thyroid-stimulating hormone receptor (TSH-R). Immune-mediated mechanisms - production of autoantibodies to thyroid antigens and lymphocytic thyroid infiltration - are involved in the pathogenesis of AITD. Insufficiency of regulatory T cells (Treg) and regulatory B cells (Breg), imbalance between Th17-lymphocytes and Treg-lymphocytes, abnormal production of pro-inflammatory cytokines has a significant influence on the progression of AITD. With AITD, the balance between oxidants and antioxidants is disturbed and oxidative stress (OS) occurs. The lack of modern effective pharmacological therapy of AITD prompted us to consider the mechanisms of influence, possibilities of immunocorrection of pathogenetic factors using TG, micro/macronutrients. In order to develop a more effective treatment strategy, as well as approaches to prevention, a critical analysis of the ways of immunotherapeutic use of dietary supplements of I, Se, Zn, Mg and other minerals in AITD was carried out.

Survey on selenium clinical supplementation in autoimmune thyroid disease

Objective

Previous trials show that selenium could be a very useful tool in the control and treatment of autoimmune thyroid diseases. In this cross-sectional study, through a survey, we aim to evaluate Portuguese endocrinologists' perception and pattern of prescription of selenium supplements in these diseases and verify its agreement with current guidelines.

Methods

The endocrinologists registered in the Portuguese Medical Association were sent an email with a web-based questionnaire, regarding their knowledge and use of selenium supplements in thyroid autoimmune pathology.

Results

A total of 105 physicians (33% of the total) submitted the survey. The selenium serum concentration in the general population was unknown to 80% of respondents. Over a third of respondents have never prescribed selenium for autoimmune thyroid disease. However, 89% are not afraid of recommending it, and 61% indicate Graves' orbitopathy as the pathology they would supplement. In Hashimoto's thyroiditis, 36% of respondents use selenium occasionally or frequently, and this percentage rises to 60% in Graves' disease.

Conclusions

Although recommendations only encompass mild Graves' orbitopathy, selenium is prescribed across the spectrum of autoimmune thyroid diseases, probably due to recent studies that consistently show improvement of biochemical hallmarks in these patients. Further investigation is required on the impact of selenium supplements on primarily clinical outcomes and to identify disorders and/or patients who will benefit the most. Also, there is still insufficient knowledge of this field in the medical community, and evidence-based practice should continue to be promoted by endocrinology societies.

Conundrum for Psoriasis and Thyroid Involvement

Strategies concerning thyroid anomalies in patients confirmed with psoriasis, either on clinical level or molecular levels, and their genetic findings remain an open issue. Identification of the exact subgroup of individuals that are candidates to endocrine assessments is also controversial. Our purpose in this work was to overview clinical and pathogenic data concerning psoriasis and thyroid comorbidities from a dual perspective (dermatologic and endocrine). This was a narrative review of English literature between January 2016 and January 2023. We included clinically relevant, original articles with different levels of statistical evidence published on PubMed. We followed four clusters of conditions: thyroid dysfunction, autoimmunity, thyroid cancer, and subacute thyroiditis. A new piece of information in this field was the fact that psoriasis and autoimmune thyroid diseases (ATD) have been shown to be related to the immune-based side effects of modern anticancer drugs-namely, immune checkpoint inhibitors (ICP). Overall, we identified 16 confirmatory studies, but with heterogeneous data. Psoriatic arthritis had a higher risk of positive antithyroperoxidase antibodies (TPOAb) (25%) compared to cutaneous psoriasis or control. There was an increased risk of thyroid dysfunction versus control, and hypothyroidism was the most frequent type of dysfunction (subclinical rather than clinical), among thyroid anomalies correlated with >2-year disease duration, peripheral > axial and polyarticular involvement. With a few exceptions, there was a female predominance. Hormonal imbalance included, most frequently, low thyroxine (T4) and/or triiodothyronine (T3) with normal thyroid stimulating hormone (TSH), followed by high TSH (only one study had higher total T3). The highest ratio of thyroid involvement concerning dermatologic subtypes was 59% for erythrodermic psoriasis. Most studies found no correlation between thyroid anomalies and psoriasis severity. Statistically significant odds ratios were as follows: hypothyroidism: 1.34-1.38; hyperthyroidism: 1.17-1.32 (fewer studies than hypo); ATD: 1.42-2.05; Hashimoto's thyroiditis (HT): 1.47-2.09; Graves' disease: 1.26-1.38 (fewer studies than HT). A total of 8 studies had inconsistent or no correlations, while the lowest rate of thyroid involvement was 8% (uncontrolled studies). Other data included 3 studies on patients with ATD looking for psoriasis, as well as 1 study on psoriasis and thyroid cancer. ICP was shown to potentially exacerbate prior ATD and psoriasis or to induce them both de novo (5 studies). At the case report level, data showed subacute thyroiditis due to biological medication (ustekinumab, adalimumab, infliximab). Thyroid involvement in patients with psoriasis thus remained puzzling. We observed significant data that confirmed a higher risk of identifying positive antibodies and/or thyroid dysfunction, especially hypothyroidism, in these subjects. Awareness will be necessary to improve overall outcomes. The exact profile of individuals diagnosed with psoriasis who should be screened by the endocrinology team is still a matter of debate, in terms of dermatological subtype, disease duration, activity, and other synchronous (especially autoimmune) conditions.

Supplementation with myo-inositol and Selenium improves the clinical conditions and biochemical features of women with or at risk for subclinical hypothyroidism

Purpose

The present study aims to evaluate the effect of myo-Inositol plus Selenium supplementation in patients affected by subclinical hypothyroidism.

Methods

One hundred and forty-eight patients were included in the study from 8 different centers of Slovakia, and treated for 6 months with a daily dose of 600 mg myo-Ins plus 83 mcg Se. The patients included at the enrollment were women of reproductive age (18-50), who exhibit values of TSH in the range 2.5-5 mU/l and positivity to antibodies TPO-Ab/TG-Ab, or otherwise values of TSH in the range 5-10 mU/l both with and without positivity to antibodies TPO-Ab/TG-Ab.

Results

Patients affected by subclinical hypothyroidism exhibited a significant improvement of their condition when treated for 6 months with a combination of myo-Inositol and Selenium. The TSH values significantly ameliorated along with the index of autoimmunity and the thyroid status. In a sub-class of patients, the auto-antibody titer decreased after myo-inositol + Selenium administration. The treatment also induces a regularization of the menstrual cycle and a reduction of the cholesterol in the patients enrolled for the study. Furthermore, a significant improvement is observed in the perception of the symptoms associated with subclinical hypothyroidism over the treatment period.

Conclusion

A dietary supplementation with of myo-Inositol and Selenium in the treatment of patients affected by subclinical hypothyroidism exhibits a beneficial role in the recovery of TSH values, in the improvement of the symptoms associated to this condition and in the maintenance of the thyroid functions.The trial was approved by the Ethical Committee from National Institute of Endocrinology and Diabetology of Lubochna, Slovakia, date 18.12.2018, registration number: 3124/2018.

Seleno-Metabolites and Their Precursors: A New Dawn for Several Illnesses?

Selenium (Se) is an essential element for human health as it is involved in different physiological functions. Moreover, a great number of Se compounds can be considered potential agents in the prevention and treatment of some diseases. It is widely recognized that Se activity is related to multiple factors, such as its chemical form, dose, and its metabolism. The understanding of its complex biochemistry is necessary as it has been demonstrated that the metabolites of the Se molecules used to be the ones that exert the biological activity. Therefore, the aim of this review is to summarize the recent information about its most remarkable metabolites of acknowledged biological effects: hydrogen selenide (HSe-/H2Se) and methylselenol (CH3SeH). In addition, special attention is paid to the main seleno-containing precursors of these derivatives and their role in different pathologies.

Serum selenium concentration in patients with autoimmune thyroid disease

Abstract.

Selenium and Selenoproteins at the Intersection of Type 2 Diabetes and Thyroid Pathophysiology

Type 2 diabetes (T2D) is considered one of the largest global public-health concerns, affecting approximately more than 400 million individuals worldwide. The pathogenesis of T2D is very complex and, among the modifiable risk factors, selenium (Se) has recently emerged as a determinant of T2D pathogenesis and progression. Selenium is considered an essential element with antioxidant properties, and is incorporated into the selenoproteins involved in the antioxidant response. Furthermore, deiodinases, the enzymes responsible for homeostasis and for controlling the activity of thyroid hormones (THs), contain Se. Given the crucial action of oxidative stress in the onset of insulin resistance (IR) and T2D, and the close connection between THs and glucose metabolism, Se may be involved in these fundamental relationships; it may cover a dual role, both as a protective factor and as a risk factor of T2D, depending on its basal plasma concentration and the individual’s diet intake. In this review we discuss the current evidence (from experimental, observational and randomized clinical studies) on how Se is associated with the occurrence of T2D and its influence on the relationship between thyroid pathophysiology, IR and T2D.

Selenium Supplementation in Pregnant Women with Autoimmune Thyroiditis: A Practical Approach

Selenium (Se) is an essential trace element with antioxidant and anti-inflammatory properties and a pivotal role in thyroid metabolism. Ensuring a sufficient Se supply is possible via a balanced, wholesome diet; however, Se content in foods may be different throughout geographical areas. Se supplementation is expected to improve inflammatory status in patients with autoimmune thyroiditis, especially in those with high activity, and has been demonstrated as effective in reducing the thyroid peroxidase antibodies titer. Se status seems to affect thyroid function in pregnancy, which prompts the potential role of Se supplementation in such patients. Few clinical trials have investigated the effectiveness of Se supplementation in pregnant women with thyroiditis, and their results suggest the safety and effectiveness of this element in reducing autoantibody levels and preventing postpartum thyroiditis development, although limited. Hence, more robust evidence is needed to confirm these data. The current study aims to summarize published data on the relationship between Se and thyroid status in pregnant women with thyroiditis and the potential use of Se. Moreover, an algorithm for Se supplementation is proposed for pregnant women with thyroiditis to help endocrinologists in daily clinical practice to consider Se status.

The Role and Mechanism of Essential Selenoproteins for Homeostasis

Selenium (Se) is one of the essential trace elements that plays a biological role in the body, mainly in the form of selenoproteins. Selenoproteins can be involved in the regulation of oxidative stress, endoplasmic reticulum (ER) stress, antioxidant defense, immune and inflammatory responses and other biological processes, including antioxidant, anti-inflammation, anti-apoptosis, the regulation of immune response and other functions. Over-loading or lack of Se causes certain damage to the body. Se deficiency can reduce the expression and activity of selenoproteins, disrupt the normal physiological function of cells and affect the body in antioxidant, immunity, toxin antagonism, signaling pathways and other aspects, thus causing different degrees of damage to the body. Se intake is mainly in the form of dietary supplements. Due to the important role of Se, people pay increasingly more attention to Se-enriched foods, which also lays a foundation for better research on the mechanism of selenoproteins in the future. In this paper, the synthesis and mechanism of selenoproteins, as well as the role and mechanism of selenoproteins in the regulation of diseases, are reviewed. Meanwhile, the future development of Se-enriched products is prospected, which is of great significance to further understand the role of Se.

Effect of Selenium-Enriched Yeast Supplementation on Serum Thyroid-Stimulating Hormone and Anti-Thyroid Peroxidase Antibody Levels in Subclinical Hypothyroidism: Randomized Controlled Trial

Background

In the subclinical hypothyroidism, T4 or T3 levels are normal and thyroid-stimulating hormone (TSH) is slightly high. Selenium deficiency can lead to thyroid dysfunction. The present study aims to investigate the effect of selenium supplementation on the thyroid hormone and anti-thyroid peroxidase antibody (anti-TPO AB) levels.

Materials and Methods

In this double-blinded, randomized, placebo-controlled clinical trial, 42 patients with subclinical hypothyroidism were randomly assigned to receive 200 μg selenium or placebo for 8 weeks. In the both groups, the serum TSH and anti-TPO antibody levels were measured and assessed before and after the intervention.

Results

After the interventions, the mean serum TSH reduction in the intervention and placebo groups was -10.98 ± 33.31 and -3.20 ± 38.36, respectively, which were not statistically significant. However, the mean serum anti-TPO Ab concentration increased in the intervention and placebo groups (109.81 ± 51.49% vs. 173.17 ± 96.26%), between which the difference was not statistically significant (P >0.05) despite a slight increase in the mean anti-TPO level in the intervention group.

Conclusion

The results of the current study indicated that selenium supplementation has no significant effect on serum anti-TPO Ab and TSH levels in the patients with subclinical hypothyroidism. Studies with larger sample size and with different doses of selenium are needed to reach more precise results.

Antimicrobial Activity of Se-Nanoparticles from Bacterial Biotransformation

Selenium nanoparticles (SeNPs) are gaining importance in the food and medical fields due to their antibacterial properties. The microbial inhibition of these kinds of particles has been tested in a wide range of Gram (+) and Gram (−) pathogenic bacteria. When SeNPs are synthesized by biological methods, they are called biogenic SeNPs, which have a negative charge caused by their interaction between surface and capping layer (bioorganic material), producing their high stability. This review is focused on SeNPs synthesis by bacteria and summarizes the main factors that influence their main characteristics: shape, size and surface charge, considering the bacteria growth conditions for their synthesis. The different mechanisms of antimicrobial activity are revised, and this review describes several biosynthesis hypotheses that have been proposed due to the fact that the biological mechanism of SeNP synthesis is not fully known.

Effect of selenium on thyroid autoimmunity and regulatory T cells in patients with Hashimoto's thyroiditis: A prospective randomized-controlled trial

Selenium (Se) is an essential trace element in human. Recent studies of Se supplementation on the effect of Hashimoto's thyroiditis (HT) have been reported, but the exact benefit is unclear as well as the underlying immunologic mechanism. We aimed to evaluate the clinical effect of Se supplement in patients with HT, and explore the potential mechanism against thyroid autoimmunity. A prospective, randomized-controlled study was performed in patients with HT assigned to two groups. Se-treated group (n = 43) received selenious yeast tablet (SYT) for 6 months, whereas no treatment in control group (n = 47). The primary outcome is the change of thyroid peroxidase antibody (TPOAb) or thyroglobulin antibody (TGAb). Second, thyroid function, urinary iodine, Se, Glutathione peroxidase3 (GPx3), and Selenoprotein P1 (SePP1) levels were measured during the SYT treatment. Meanwhile, regulatory T cells (Tregs) and their subsets activated Tregs (aTregs), resting Tregs, and secreting Tregs, as well as Helios and PD-1 expression on these cells were also detected. The results showed that SYT treatment significantly decreased TPOAb, TGAb, and thyroid stimulating hormone (TSH) levels, accompanied with the increased Se, GPx3, and SePP1, compared with the control group. Subgroup analysis revealed that subclinical HT may benefit more from this treatment in the decrease of TSH levels by interaction test. Moreover, the percentage of aTregs, Helios/Tregs, and Helios/aTregs were significantly higher in the Se-treated group than control. In conclusion, Se supplementation may have a beneficial effect on thyroid autoantibodies and thyroid function by increasing the antioxidant activity and upregulating the activated Treg cells.

Minerals in Pregnancy and Their Impact on Child Growth and Development

During pregnancy, women undergo metabolic and physiological changes, and their needs are higher, to maintain growth and development of the fetus. If the nutritional status of the expectant mother is not satisfactory, some maternal and neonatal complications can occur. In the second and third trimester of pregnancy, there is a reserve of nutrients in the fetus that can be utilized after birth; thereby, children present an accelerated growth in the first years of life, which is a proven response to the available nutrition pattern. However, if such a pattern is insufficient, there will be deficits during development, including brain function. Therefore, despite many recent published works about gestational nutrition, uncertainties still remain on the mechanisms of absorption, distribution, and excretion of micronutrients. Further elucidation is needed to better understand the impacts caused either by deficiency or excess of some micronutrients. Thus, to illustrate the contributions of minerals during prenatal development and in children, iodine, selenium, iron, zinc, calcium, and magnesium were selected. Our study sought to review the consequences related to gestational deficiency of the referred minerals and their impact on growth and development in children born from mothers with such deficiencies

Redox Status and Antioxidative Cofactor Metals Influence Clinical and Pathological Characteristics of Papillary Thyroid Carcinoma and Colloid Goiter

Papillary thyroid carcinoma (PTC) is the endocrine neoplasm that occurs the most often worldwide, and its molecular pathophysiology is still not well characterized. Redox status is recognized as an important factor of carcinogenesis, but its influence on the PTC's clinical course needs to be better elucidated. The aim of this research was to determine the tissue redox status of 65 PTC and 45 colloid goiter (CG) patients together with antioxidative cofactor metal profiling. The malondialdehyde (MDA) concentration was used to access the prooxidation level, while antioxidant mechanisms were estimated by assaying the activities of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), and glutathione reductase (GR). The antioxidative cofactor metals included quantification of Se, Cu, Zn, and Mn concentration. PTC tissues had normal prooxidation levels and increased GPx and GR activity. The activity of SOD has been significantly reduced in multicentric PTC dissemination and increased in smokers. SOD activity was directly dependent on MDA levels in CG tissues. CG patients with retrosternal goiter had reduced MDA concentration and SOD activity. Numerous correlations between redox parameters in PTC tissues reveal good co-activation of antioxidative mechanisms and cooperative response on prooxidation. PTC tissues had decreased Se levels and increased concentration of Cu and Mn in comparison to other tissues. MDA concentration and SOD activity were significant predictors of PTC's multicentric dissemination and for the existence of lymph node metastases, respectively. Particularly, the concentration of Cu predicted the retrosternal localization in CG patients. Significant findings presented in this study provide a possibility for development of novel prognostic molecular biomarkers of PTC and CG.

Selenium and Nano-Selenium Biofortification for Human Health: Opportunities and Challenges

Selenium is an essential micronutrient required for the health of humans and lower plants, but its importance for higher plants is still being investigated. The biological functions of Se related to human health revolve around its presence in 25 known selenoproteins (e.g., selenocysteine or the 21st amino acid). Humans may receive their required Se through plant uptake of soil Se, foods enriched in Se, or Se dietary supplements. Selenium nanoparticles (Se-NPs) have been applied to biofortified foods and feeds. Due to low toxicity and high efficiency, Se-NPs are used in applications such as cancer therapy and nano-medicines. Selenium and nano-selenium may be able to support and enhance the productivity of cultivated plants and animals under stressful conditions because they are antimicrobial and anti-carcinogenic agents, with antioxidant capacity and immune-modulatory efficacy. Thus, nano-selenium could be inserted in the feeds of fish and livestock to improvise stress resilience and productivity. This review offers new insights in Se and Se-NPs biofortification for edible plants and farm animals under stressful environments. Further, extensive research on Se-NPs is required to identify possible adverse effects on humans and their cytotoxicity.

Biosynthesis of selenoproteins by Saccharomyces cerevisiae and characterization of its antioxidant activities

The study investigated biosynthesis of selenoproteins by Saccharomyces. cerevisiae using inorganic selenium. Selenium supplement via two stages was carried out during fermentation and the physicochemical characteristics of selenoproteins and its antioxidant activities were examined through in vitro assessment procedures. After fermentation, dry cells weight (7.47 g/L) and selenium content (3079.60 μg/kg) in the yeast were achieved when fermentation time points at the 6th hour and the 9th hour were chosen to supplement 30% and 70% of 30 μg/mL Na₂SeO₃ respectively. A maximal yield of selenium content in selenoproteins reached 1013.07 μg/g under optimized culture conditions and was 133-fold higher than the control. One new band with molecular weight of 26.76 KDa appeared in conjugated selenoproteins of sodium dodecyl sulphate-polyacrylamide gel electrophoresis. Surface structure of selenoproteins and the control was different by Scanning electron microscopy images. Infrared spectrometry analysis demonstrated that groups of HSe, SeO and C-Se-O involved in selenoproteins were important pieces of evidence showing presence of Se embedded in the protein molecule. Selenoproteins showed strong antioxidant activities on DPPH·, OH and ·O^2-, which was much higher than the control proteins. Therefore, the study provided an efficient selenium-enriched culture method of inorganic selenite to organic selenium and basis for selenoproteins applications.

DAFS-25k impact on cattle’s thyroid hormonal status

The paper studies the impact of selenium organic preparation DAFS-25k on thyroid capacity in pregnant cows. A stud farm which the work is done in is a biogeochemical province distinguished by a sharp deficit of selenium and iodine in the diet. DAFS-25k had been implanted into the animals subcutaneously during 1 month 30 days before the predicted calving. A sterile 0.6 % DAFS-25k oil solution was used in doses containing 2 mg/cow/day, 6 mg/cow/day and 12 mg/cow/day. It was found that the cows’ diet is deficient in iodine and selenium by 63 and 82 % respectively. Daily use of selenium in DAFS-25k in the dose range causes a decrease in the concentration of free thyroxine due to deiodination activating by selenium dependent deiodinases of the first and second types. Consequently, there is a progressive increase in the blood content of total triiodothyronine in all experimental animals as relating to the background values. In this case, the concentration of thyroid-stimulating hormone decreases in blood serum by the 30th day according to the principle of negative feedback. In control animals, an increase in the serum concentration of thyroid-stimulating hormone reached the point 1.8 by the 30th day, total triiodothyronine increased by 14 and 19 % by the 21st day and the 30th day respectively, while the concentration of free thyroxine was reduced by 19 % by the 30th day. The use of selenium in the setting of iodine deficiency leads to aggravation of iodine deficiency.

Cadmium as main endocrine disruptor in papillary thyroid carcinoma and the significance of Cd/Se ratio for thyroid tissue pathophysiology

BACKGROUND

The etiology of papillary thyroid carcinoma (PTC) is unknown and some literature data support the hypothesis that heavy metals, as endocrine disrupters, could play a major role in the pathogenesis of thyroid cancer. This study aimed to estimate the content of selected toxic and essential trace metals (Mn, Co, Ni, Cu, Zn, As, Se, Cd, Pb, Th, and U), as well as the selected ratio's (Cu/Zn and Cd/Se) in the malignant thyroid tissues according to sex, age, smoking habits, familial history of any thyroid disease, pathohistological (PH) types of PTC, tumor size, the existence of a thyroid capsular invasion, intrathyroid tumor dissemination, retrosternal thyroid growth, and TNM progress of PTC.

METHODS

The study included 66 patients with PTC (women/men ratio = 46/20, mean age: 54 ± 14 years). A comparative analysis was made by collecting the healthy thyroid tissues (HTTs) of the same patients, making the total number of samples 132. All trace metals were quantified by inductively coupled plasma-mass spectrometry (ICP-MS).

RESULTS

Metals that significantly separated papillary thyroid tissues (PTTs) from the HTTs were Cd, U and Se (p < 0.05). The obtained negative correlation between Cd and Se in the PTTs could explain extrusion of essential Se caused by increased content of Cd. Only Cd had an influence on the retrosternal thyroid growth, while the essential metals (Mn, Co, and Zn) had an influence on thyroid capsular invasion.

CONCLUSION

It was found that Cd act as the main endocrine disrupter, which could highlight its role in the etiology of PTC. Considering that the Cd/Se ratio significantly separated two studied groups and had an influence on the retrosternal thyroid growth, its altered content could contribute to the better understanding of the molecular basis for pathophysiological changes in the PTC.