Selenium and selenoproteins: from endothelial cytoprotection to clinical outcomes

The Potential of Selenium-Based Therapies for Ocular Oxidative Stress

Oxidative stress plays a critical role in the development of chronic ocular conditions including cataracts, age-related macular degeneration, and diabetic retinopathy. There is a need to explore the potential of topical antioxidants to slow the progression of those conditions by mediating oxidative stress and maintaining ocular health. Selenium has attracted considerable attention because it is a component of selenoproteins and antioxidant enzymes. The application of selenium to a patient can increase selenoprotein expression, counteracting the effect of reactive oxygen species by increasing the presence of antioxidant enzymes, and thus slowing the progression of chronic ocular disorders. Oxidative stress effects at the biomolecular level for prevalent ocular conditions are described in this review along with some of the known defensive mechanisms, with a focus on selenoproteins. The importance of selenium in the eye is described, along with a discussion of selenium studies and uses. Selenium's antioxidant and anti-inflammatory qualities may prevent or delay eye diseases. Recent breakthroughs in drug delivery methods and nanotechnology for selenium-based ocular medication delivery are enumerated. Different types of selenium may be employed in formulations aimed at managing ocular oxidative stress conditions.

The mechanism of selenium regulating the permeability of vascular endothelial cells through selenoprotein O

Vascular diseases, a leading cause of death in human, are strongly associated with pathological damage to blood vessels. The selenoprotein (Sel) have been reported to play important roles in vascular disease. However, the role of SelO in vascular disease has not been conclusively investigated. The present experiment was to investigate the regulatory mechanism of the effect of SelO on the permeability of vascular endothelial. The H.E staining, FITC-Dextran staining, Dil-AC-LDL staining and FITC-WGA staining showed that vascular structure was damaged, and intercellular junctions were disrupted with selenium (Se)-deficient. Immunohistochemistry, qPCR and Western blot revealed decreased expression of the adhesion plaque proteins vinculin, talin and paxillin, decreased expression of the vascular connectivity effector molecules connexin, claudin-1 and E-cadherin and increased expression of JAM-A and N-cadherin, as well as decreased expression of the ZO-1 signaling pathways ZO-1, Rock, rhoGEF, cingulin and MLC-2. In a screening of 24 Sel present in mice, SelO showed the most pronounced changes in vascular tissues, and a possible association between SelO and vascular intercellular junction effectors was determined using IBM SPSS Statistics 25. Silencing of SelO, vascular endothelial intercellular junction adverse effects present. The regulatory relationship between SelO and vascular endothelial intercellular junctions was determined. The results showed that Se deficiency lead to increased vascular endothelial permeability and vascular tissue damage by decreasing SelO expression, suggesting a possible role for SelO in regulating vascular endothelial permeability.

Four-week administration of an energy and protein dense oral nutritional supplement improves micronutrient concentrations but does not completely correct deficiencies in institutionalized malnourished older adults

Introduction

Poor food intake is common among elderly living in nursing homes, leading to micronutrient deficiency (MD). There are no recommendations for the management of MD in malnourished older adults.

Methods

We conducted a single arm, open-label, multicenter interventional study in institutionalized malnourished older adults to describe the effect of a 4-week daily energy and protein dense oral nutritional supplementation (ONS, 600 kcal, 30 g protein per unit) containing 50% of the recommended daily micronutrient intake on micronutrient status. Plasma concentrations of vitamins (A, B9, B12, C, E), magnesium (Mg), selenium (Se) and zinc (Zn), and erythrocyte vitamin B9 were measured at baseline and after 4 weeks.

Results

Forty-six participants completed the study (age 87.4 ± 6.6). At baseline, the most frequent MD were Se (48%), Zn (35%), Mg (24%) and vitamin C (24%). Plasma concentrations of vitamins B9, B12, C and E, Mg, Se and Zn significantly increased and the proportion of subjects with at least one MD decreased (p = 0.006). However, after 4 weeks, 40% of subjects still had at least one MD.

Discussion

ONS consumption improved micronutrient status but did not correct MD in all participants. Our data suggest that the prescription of vitamin, mineral and trace element supplementation should be considered in institutionalized malnourished older adults in addition to high energy and high protein ONS.

Population status of selenium in Colombia and associated factors: a cross-sectional study

OBJECTIVES

This study aims to investigate the population status of selenium in Colombia and other associated factors.

METHODS

Cross-sectional study, in population of urban or rural origin (n=412). Main outcome measures were: median serum selenium, thyrotropin, the prevalence of and positivity of anti-thyroid peroxidase, anti-thyroglobulin, and anti-TSH receptor.

RESULTS

This study found that 96.6% of the subjects had normal selenium levels, and no significant associations were found between the population median of selenium and overweight/obesity, sociodemographic variables, age, goiter, and thyroid antibody positivity.

CONCLUSIONS

In Colombia, the population status of selenium is normal, and the geological characteristics may contribute to the state of selenium in this population. However, additional studies are required to evaluate the content of selenium in plants and other foods.

Relationship between selenium status, selenoproteins and COVID-19 and other inflammatory diseases: A critical review

The antioxidant effects of selenium as a component of selenoproteins has been thought to modulate host immunity and viral pathogenesis. Accordingly, the association of low dietary selenium status with inflammatory and immunodeficiency has been reported in the literature; however, the causal role of selenium deficiency in chronic inflammatory diseases and viral infection is still undefined. The COVID-19, characterized by acute respiratory syndrome and caused by the novel coronavirus 2, SARS-CoV-2, has infected millions of individuals worldwide since late 2019. The severity and mortality from COVID-19 have been associated with several factor, including age, sex and selenium deficiency. However, available data on selenium status and COVID-19 are limited, and a possible causative role for selenium deficiency in COVID-19 severity has yet to be fully addressed. In this context, we review the relationship between selenium, selenoproteins, COVID-19, immune and inflammatory responses, viral infection, and aging. Regardless of the role of selenium in immune and inflammatory responses, we emphasize that selenium supplementation should be indicated after a selenium deficiency be detected, particularly, in view of the critical role played by selenoproteins in human health. In addition, the levels of selenium should be monitored after the start of supplementation and discontinued as soon as normal levels are reached. Periodic assessment of selenium levels after supplementation is a critical issue to avoid over production of toxic metabolites of selenide because under normal conditions, selenoproteins attain saturated expression levels that limits their potential deleterious metabolic effects.

Correlations of selenium and selenoprotein P with asymmetric dimethylarginine and lipid profile in patients with polycystic ovary syndrome

BACKGROUND

Polycystic ovary syndrome (PCOS) is associated with an increased risk of cardiovascular diseases (CVD). Accumulating evidence has suggested that selenium (Se) is of importance for optimal function of the cardiovascular system. This study aimed to investigate the associations of selenium and selenoprotein P (SePP) with asymmetric dimethylarginine (ADMA) and lipid profile in women with PCOS.

METHODS

In this cross-sectional study, 125 females aged 18-45 years diagnosed with PCOS were recruited. An interviewer-administered questionnaire was applied to gather the relevant demographic characteristics, detailed clinical information, and lifestyle habits of participants. Fasting blood samples were obtained to measure biochemical parameters. Serum concentrations of total testosterone, sex hormone-binding globulin (SHBG), ADMA, and lipid profiles as well as anthropometric measurements were assessed across tertiles of serum Se and SePP concentrations.

RESULTS

There was a positive correlation between serum Se and SePP concentrations (r = 0.434, p < 0.001). Serum Se level was inversely correlated with ADMA (r = -0.21, p = 0.025) and TG (r = -0.17, p = 0.041) concentrations. There were also inverse correlations between SePP and ADMA (r = -0.34, p < 0.001), TG (r = -0.21, p = 0.019), and oxidized low density lipoprotein (ox-LDL) (r = -0.25, p = 0.007) levels. No significant relationship was found between serum Se and SePP concentrations with total cholesterol, low density lipoprotein cholesterol (LDL-C), high density lipoprotein cholesterol (HDL-C), apolipoprotein-A1 (Apo-A1), apolipoprotein-B (Apo-B100), total testosterone, SHBG, and free androgen index as well as anthropometric parameters (All p > 0.05).

CONCLUSION

The present study found that Se and SePP levels were inversely correlated with ADMA and TG concentrations as well as ox-LDL levels.

Selenocompounds and Sepsis-Redox Bypass Hypothesis: Part B-Selenocompounds in the Management of Early Sepsis

Significance: Endothelial barrier damage, which is in part caused by excess production of reactive oxygen, halogen and nitrogen species (ROHNS), especially peroxynitrite (ONOO^-), is a major event in early sepsis and, with leukocyte hyperactivation, part of the generalized dysregulated immune response to infection, which may even become a complex maladaptive state. Selenoenzymes have major antioxidant functions. Their synthesis is related to the need to limit deleterious oxidant redox cycling by small selenocompounds, which may be of therapeutic cytotoxic interest. Plasma selenoprotein-P is crucial for selenium transport from the liver to the tissues and for antioxidant endothelial protection, especially against ONOO^-. Above micromolar concentrations, sodium selenite (Na₂SeO₃) becomes cytotoxic, with a lower cytotoxicity threshold in activated cells, which has led to cancer research. Recent Advances: Plasma selenium (<2% of total body selenium) is mainly contained in selenoprotein-P, and concentrations decrease rapidly in the early phase of sepsis, because of increased selenoprotein-P binding and downregulation of hepatic synthesis and excretion. At low concentrations, Na₂SeO₃ acts as a selenium donor, favoring selenoprotein-P synthesis in physiology, but probably not in the acute phase of sepsis. Critical Issues: The cytotoxic effects of Na₂SeO₃ against hyperactivated leukocytes, especially the most immature forms that liberate ROHNS, may be beneficial, but they may also be harmful for activated endothelial cells. Endothelial protection against ROHNS by selenoprotein-P may reduce Na₂SeO₃ toxicity, which is increased in sepsis. Future Direction: The combination of selenoprotein-P for endothelial protection and the cytotoxic effects of Na₂SeO₃ against hyperactivated leukocytes may be a promising intervention for early sepsis. Antioxid. Redox Signal. 37, 998-1029.

Selenium supplementation for polycystic ovary syndrome: a meta-analysis of randomized controlled trials

Introduction: The efficacy of selenium supplementation was elusive for polycystic ovary syndrome. This meta-analysis aimed to explore the efficacy of selenium supplementation for polycystic ovary syndrome. Methods: PubMed, EMbase, Web of science, EBSCO, Cochrane library database, CNKI, Chongqing VIP database and Wanfang databases have been searched through July 2022 and we included randomized controlled trials (RCTs) reporting the effect of selenium supplementation versus placebo in patients with polycystic ovary syndrome. Results: Five RCTs were included in the meta-analysis. Compared with placebo group for polycystic ovary syndrome, selenium supplementation was associated with significantly reduced total testosterone (SMD=-0.42; 95% CI=-0.78 to -0.06; p = 0.02) and cholesterol (SMD=-0.71; 95% CI=-1.41 to -0.02; p = 0.04), but revealed no remarkable influence on SHBG (SMD=-0.52; 95% CI=-1.29 to 0.25; p = 0.19), triglyceride (SMD=-1.45; 95% CI=-3.62 to 0.73; p = 0.19), LDL (SMD=-0.17; 95% CI=-0.72 to 0.37; p = 0.53), FPG (SMD=-0.95; 95% CI=-3.72 to 1.82; p = 0.50) or HOMA-IR (SMD=-0.51; 95% CI=-3.79 to 2.77; p = 0.76). Conclusions: Selenium supplementation may be able to improve the metabolic response for polycystic ovary syndrome, and this finding should be interpreted with caution.

ESPEN micronutrient guideline

BACKGROUND

Trace elements and vitamins, named together micronutrients (MNs), are essential for human metabolism. Recent research has shown the importance of MNs in common pathologies, with significant deficiencies impacting the outcome.

OBJECTIVE

This guideline aims to provide information for daily clinical nutrition practice regarding assessment of MN status, monitoring, and prescription. It proposes a consensus terminology, since many words are used imprecisely, resulting in confusion. This is particularly true for the words "deficiency", "repletion", "complement", and "supplement".

METHODS

The expert group attempted to apply the 2015 standard operating procedures (SOP) for ESPEN which focuses on disease. However, this approach could not be applied due to the multiple diseases requiring clinical nutrition resulting in one text for each MN, rather than for diseases. An extensive search of the literature was conducted in the databases Medline, PubMed, Cochrane, Google Scholar, and CINAHL. The search focused on physiological data, historical evidence (published before PubMed release in 1996), and observational and/or randomized trials. For each MN, the main functions, optimal analytical methods, impact of inflammation, potential toxicity, and provision during enteral or parenteral nutrition were addressed. The SOP wording was applied for strength of recommendations.

RESULTS

There was a limited number of interventional trials, preventing meta-analysis and leading to a low level of evidence. The recommendations underwent a consensus process, which resulted in a percentage of agreement (%): strong consensus required of >90% of votes. Altogether the guideline proposes sets of recommendations for 26 MNs, resulting in 170 single recommendations. Critical MNs were identified with deficiencies being present in numerous acute and chronic diseases. Monitoring and management strategies are proposed.

CONCLUSION

This guideline should enable addressing suboptimal and deficient status of a bundle of MNs in at-risk diseases. In particular, it offers practical advice on MN provision and monitoring during nutritional support.

Comparative study of the ameliorative effects of omega-3 versus selenium on etoposide-induced changes in Sertoli cells and ectoplasmic specialization of adult rat testes: immunohistochemical and electron microscopic study

Etoposide (Eto) is an anti-cancer drug that is associated with serious adverse effects on male reproductive function. Omega-3 polyunsaturated fatty acids (ω-3 PUFAs) and selenium (Se) are known as anti-inflammatory, anti-apoptotic and anti-oxidant agents. This work was designed to investigate changes in the biochemical parameters as well as alterations in Sertoli cell vimentin expression, ultrastructure and ectoplasmic specializations (ESs) following Eto treatment and to assess the ameliorative effect of ω-3 versus Se on these alterations. Eighty four adult male albino rats were used and classified into four groups: group I (control group), group II (Eto group) received Eto in a single intra-peritoneal (IP) dose (60 mg/kg B.W.), group III (Eto & ω-3 group) received the single IP dose of Eto as well as ω-3 (300 mg/kg B.W./day by intra-gastric intubation) starting 5 days before Eto injection till the time of sacrifice & group IV (Eto & Se group) received the single IP dose of Eto as well as Se (0.5 mg/kg B.W./day IP) starting 5 days before Eto injection till the time of sacrifice. The rats were subdivided into 2 subgroups (a) and (b) that were sacrificed 3 and 7 days after Eto injection respectively. Eto administration in group II induced increase in malondialdehyde (MDA), decrease in superoxide dismutase (SOD), collapse of Sertoli cell vimentin filaments and ultrastructural degenerative changes in both Sertoli cells and ESs. Se (group IV) reversed Eto toxic effects potently, while ω-3 (group III) had some limited protective effects.

Supportive treatment of vascular dysfunction in pediatric subjects with obesity: the OBELIX study

INTRODUCTION

Overweight or obese children develop abnormal endothelial cell dysfunction and arterial intima-media thickening with increased vasomotor tone and inflammation. Curcumin, resveratrol, zinc, magnesium, selenium, and vitamin D have shown beneficial effects on endothelial function. We test, among overweight and obese pediatric subjects, the effects on the endothelium of a combination of curcumin, resveratrol, zinc, magnesium, selenium, and vitamin D.

METHODS

Forty-eight subjects (6-17 years) were randomized into two groups (placebo vs treatment) attended three visits at 0, 3, and 6 months (±15 days). Endothelial function was assessed by means of a post-occlusive release hyperemic (PORH) test for estimation of delta flow (DF) and hyperemic AUC index, and a heat provocation test (HPT) to measure DF HPT (DF_HPT).

RESULTS

Significant DF difference was noted at 6 months in both groups (p < 0.001). Overall time trend was significantly different between baseline, 3 months, and 6 months both in placebo (p < 0.05) and treatment (p < 0.001) groups and their comparison (p < 0.001). No differences were noted in hyperemic AUC index (3 and 6 months), whilst there were significant differences in time trends of rreatment (p < 0.001) and placebo (p < 0.05) groups and their comparison (p < 0.001). DF_HPT difference between groups was significant at 3 and 6 months (p < 0.05). The overall time trend was significant exclusively in Treatment group between 3 and 6 months (p < 0.05). Correlation with anthropometrics was found for DF and body mass index (r = 0.677 6 months, p < 0.05), as well as for hyperemic AUC index and males (r = 0.348, p < 0.05), while DF_HPT showed no correlation.

CONCLUSION

Curcumin, resveratrol, zinc, magnesium, selenium, and vitamin D appear to be promising in enhancing endothelial function by improvement of both DF in the PORH test and DF in the HPT, lowering the risk of developing cardiovascular diseases in overweight and obese pediatric subjects.

Selenoprotein T Protects Endothelial Cells against Lipopolysaccharide-Induced Activation and Apoptosis

Sepsis is an exaggerated immune response upon infection with lipopolysaccharide (LPS) as the main causative agent. LPS-induced activation and apoptosis of endothelial cells (EC) can lead to organ dysfunction and finally organ failure. We previously demonstrated that the first twenty amino acids of the Apurinic/Apyrimidinic Endodeoxyribonuclease 1 (APEX1) are sufficient to inhibit EC apoptosis. To identify genes whose regulation by LPS is affected by this N-terminal APEX1 peptide, EC were transduced with an expression vector for the APEX1 peptide or an empty control vector and treated with LPS. Following RNA deep sequencing, genes upregulated in LPS-treated EC expressing the APEX1 peptide were identified bioinformatically. Selected candidates were validated by semi-quantitative real time PCR, a promising one was Selenoprotein T (SELENOT). For functional analyses, an expression vector for SELENOT was generated. To study the effect of SELENOT expression on LPS-induced EC activation and apoptosis, the SELENOT vector was transfected in EC. Immunostaining showed that SELENOT was expressed and localized in the ER. EC transfected with the SELENOT plasmid showed no activation and reduced apoptosis induced by LPS. SELENOT as well as APEX1(1-20) can protect EC against activation and apoptosis and could provide new therapeutic approaches in the treatment of sepsis.

Selenocompounds and Sepsis: Redox Bypass Hypothesis for Early Diagnosis and Treatment: Part A-Early Acute Phase of Sepsis: An Extraordinary Redox Situation (Leukocyte/Endothelium Interaction Leading to Endothelial Damage)

Significance: Sepsis is a health disaster. In sepsis, an initial, beneficial local immune response against infection evolves rapidly into a generalized, dysregulated response or a state of chaos, leading to multiple organ failure. Use of life-sustaining supportive therapies creates an unnatural condition, enabling the complex cascades of the sepsis response to develop in patients who would otherwise die. Multiple attempts to control sepsis at an early stage have been unsuccessful. Recent Advances: Major events in early sepsis include activation and binding of leukocytes and endothelial cells in the microcirculation, damage of the endothelial surface layer (ESL), and a decrease in the plasma concentration of the antioxidant enzyme, selenoprotein-P. These events induce an increase in intracellular redox potential and lymphocyte apoptosis, whereas apoptosis is delayed in monocytes and neutrophils. They also induce endothelial mitochondrial and cell damage. Critical Issues: Neutrophil production increases dramatically, and aggressive immature forms are released. Leukocyte cross talk with other leukocytes and with damaged endothelial cells amplifies the inflammatory response. The release of large quantities of reactive oxygen, halogen, and nitrogen species as a result of the leukocyte respiratory burst, endothelial mitochondrial damage, and ischemia/reperfusion processes, along with the marked decrease in selenoprotein-P concentrations, leads to peroxynitrite damage of the ESL, reducing flow and damaging the endothelial barrier. Future Directions: Endothelial barrier damage by activated leukocytes is a time-sensitive event in sepsis, occurring within hours and representing the first step toward organ failure and death. Reducing or stopping this event is necessary before irreversible damage occurs.

Selenium, Selenoproteins, and Heart Failure: Current Knowledge and Future Perspective

PURPOSE OF REVIEW

(Mal-)nutrition of micronutrients, like selenium, has great impact on the human heart and improper micronutrient intake was observed in 30-50% of patients with heart failure. Low selenium levels have been reported in Europe and Asia and thought to be causal for Keshan disease. Selenium is an essential micronutrient that is needed for enzymatic activity of the 25 so-called selenoproteins, which have a broad range of activities. In this review, we aim to summarize the current evidence about selenium in heart failure and to provide insights about the potential mechanisms that can be modulated by selenoproteins.

RECENT FINDINGS

Suboptimal selenium levels (<100 μg/L) are prevalent in more than 70% of patients with heart failure and were associated with lower exercise capacity, lower quality of life, and worse prognosis. Small clinical trials assessing selenium supplementation in patients with HF showed improvement of clinical symptoms (NYHA class), left ventricular ejection fraction, and lipid profile, while governmental interventional programs in endemic areas have significantly decreased the incidence of Keshan disease. In addition, several selenoproteins are found impaired in suboptimal selenium conditions, potentially aggravating underlying mechanisms like oxidative stress, inflammation, and thyroid hormone insufficiency. While the current evidence is not sufficient to advocate selenium supplementation in patients with heart failure, there is a clear need for high level evidence to show whether treatment with selenium has a place in the contemporary treatment of patients with HF to improve meaningful clinical endpoints. Graphical summary summarizing the potential beneficial effects of the various selenoproteins, locally in cardiac tissues and systemically in the rest of the body. In short, several selenoproteins contribute in protecting the integrity of the mitochondria. By doing so, they contribute indirectly to reducing the oxidative stress as well as improving the functionality of immune cells, which are in particular vulnerable to oxidative stress. Several other selenoproteins are directly involved in antioxidative pathways, next to excreting anti-inflammatory effects. Similarly, some selenoproteins are located in the endoplasmic reticulum, playing roles in protein folding. With exception of the protection of the mitochondria and the reduction of oxidative stress, other effects are not yet investigated in cardiac tissues. The systemic effects of selenoproteins might not be limited to these mechanisms, but also may include modulation of endothelial function, protection skeletal muscles, in addition to thyroid metabolism.

ABBREVIATIONS

DIO, iodothyronine deiodinase; GPx, glutathione peroxidase; MsrB2, methionine-R-sulfoxide reductase B2; SELENOK, selenoprotein K; SELENON, selenoprotein N; SELENOP, selenoprotein P; SELENOS, selenoprotein S; SELENOT, selenoprotein T; TXNRD, thioredoxin reductase.

Selenium-related nutritional status in patients with common variable immunodeficiency: association with oxidative stress and atherosclerosis risk

Background

Common variable immunodeficiency (CVID) is an inborn errors of immunity, that leads to recurrent chronic infections and autoimmune/ inflammatory diseases and neoplasms. It is considered that these condition is related to persistent this immune-inflammatory stimulation and increased oxidative stress. A positive impact on the survival of patients with an inborn error of immunity was observed with advanced clinical care protocols, thus raising concerns about the risk of developing other associated chronic diseases, such as atherosclerosis. Studies suggest that selenium (Se) is a protective trace element against damage caused by oxidative stress. Thus, it is postulated that adequate consumption reduces the risk of some chronic diseases.

Results

Se median levels (ug/L) [45.6 (37.3–56.2) vs. 57.8 (46.0–66.0); p = 0.004] and GPX activity (U/L) [7682 (6548–8446) vs. 9284(8440–10,720); p = 0,002) were significantly lower in patients compared to controls. Inadequacy of Se levels was observed in 50% of the patients. There was a higher percentage of high values of C-reactive protein in the group of CVID patients compared to controls [8 (36.4%) vs. 2 (11.1%); p = 0.082]. Higher concentrations of oxidized LDL (45.3 mg/dL vs. 33.3 mg/dL; p = 0.016) and lower concentrations of Apo A-1 (98.5 mg/dL) vs. 117.0 mg/dL; p = 0.008) were observed in the CVID group compared to the control. There was a significant and positive correlation between Se plasma levels and apolipoprotein A-1 concentrations in CVID group (rho = 0.577; p = 0.001). Se values less than 46 μg / L (OR = 3.590; 95% CI 1.103 to 11.687; p = 0.034) and GPX activity below the 4th quartile (OR = 21.703; 95% CI 2.534 to 185.914; p = 0.005) were independently associated, after adjustment for age, overweight and dyslipidemia, with the CVID group (Table 5).

Conclusion

This study showed an higher percentage of high us-CRP, lower values of plasma Se and GPX activity, higher concentrations of LDLox and lower levels of Apo A-1 in CVID patients in comparison to controls, suggesting oxidative stress and cardiovascular risk.These data point to the importance of assessing the Se status and cardiovascular risk in these patients.

Selenium levels and glutathione peroxidase activity in patients with ataxia-telangiectasia: association with oxidative stress and lipid status biomarkers

Introduction

Ataxia-Telangiectasia (A-T) is a multi-system disorder that may be associated with endocrine changes, oxidative stress in addition to inflammation. Studies suggest that selenium is a trace element related to protection against damage caused by oxidative stress.

Objective

To describe the plasma levels of selenium and erythrocyte glutathione peroxidase activity in A-T patients and to relate them to oxidative stress and lipid status biomarkers.

Methods

This is a cross-sectional and controlled study evaluating 22 A-T patients (age median, 12.2 years old) matched by gender and age with 18 healthy controls. We evaluated: nutritional status, food intake, plasma selenium levels, erythrocyte glutathione peroxidase activity, lipid status, inflammation and oxidative stress biomarkers.

Results

Adequate levels of selenium were observed in 24/36 (66.7%) in this evaluated population. There was no statistically significant difference between the groups in selenium levels [47.6 μg/L (43.2–57.0) vs 54.6 (45.2–62.6) μg/dL, p = 0.242]. Nine of A-T patients (41%) had selenium levels below the reference value. The A-T group presented higher levels of LDL-c, non-HDL-c, oxidized LDL, Apo B, Apo-B/Apo-A-I1, LDL-c/HDL-c ratio, malondialdehyde [3.8 µg/L vs 2.8 µg/L, p = 0.029] and lower Apo-A-I1/HDL-c and glutathione peroxidase activity [7300 U/L vs 8686 U/L, p = 0.005]. Selenium levels were influenced, in both groups, independently, by the concentrations of oxidized LDL, malonaldehyde and non-HDL-c. The oxidized LDL (AUC = 0.849) and ALT (AUC = 0.854) were the variables that showed the greatest discriminatory power between groups.

Conclusion

In conclusion, we observed the presence of selenium below the reference value in nearly 40% and low GPx activity in A-T patients. There was a significant, inverse and independent association between selenium concentrations and oxidative stress biomarkers. Those data reinforce the importance of assessing the nutritional status of selenium in those patients.

Impairment in selenocysteine synthesis as a candidate mechanism of inducible coagulopathy in COVID-19 patients

Coagulopathy has recently been recognized as a recurring complication of COVID-19, most typically associated with critical illness. There are epidemiological, mechanistic and transcriptomic evidence that link Selenium with SARS-CoV-2’s intracellular latency. Taking into consideration the vital role of selenoproteins in maintaining an adequate immune response, endothelial homeostasis and a non-prothrombotic platelet activation status, we propose that impairment in selenocysteine synthesis, via perturbations in the aforementioned physiological functions, potentially constitutes a mechanism of coagulopathy in COVID 19 patients other than those developed in critical illness.

Flavonoids and Mitochondria: Activation of Cytoprotective Pathways?

A large number of diverse mechanisms that lead to cytoprotection have been described to date. Perhaps, not surprisingly, the role of mitochondria in these phenomena is notable. In addition to being metabolic centers, due to their role in cell catabolism, ATP synthesis, and biosynthesis these organelles are triggers and/or end-effectors of a large number of signaling pathways. Their role in the regulation of the intrinsic apoptotic pathway, calcium homeostasis, and reactive oxygen species signaling is well documented. In this review, we aim to characterize the prospects of influencing cytoprotective mitochondrial signaling routes by natural substances of plant origin, namely, flavonoids (e.g., flavanones, flavones, flavonols, flavan-3-ols, anthocyanidins, and isoflavones). Flavonoids are a family of widely distributed plant secondary metabolites known for their beneficial effects on human health and are widely applied in traditional medicine. Their pharmacological characteristics include antioxidative, anticarcinogenic, anti-inflammatory, antibacterial, and antidiabetic properties. Here, we focus on presenting mitochondria-mediated cytoprotection against various insults. Thus, the role of flavonoids as antioxidants and modulators of antioxidant cellular response, apoptosis, mitochondrial biogenesis, autophagy, and fission and fusion is reported. Finally, an emerging field of flavonoid-mediated changes in the activity of mitochondrial ion channels and their role in cytoprotection is outlined.

Anti-Oxidant and Anti-Endothelial Dysfunctional Properties of Nano-Selenium in vitro and in vivo of Hyperhomocysteinemic Rats

Purpose

Elevation of blood homocysteine (Hcy) level (hyperhomocysteinemia) is a risk factor for cardiovascular disorders and is closely associated with endothelial dysfunction. The present study aims to investigate the protective effect and underlying mechanism of nanoscale selenium (Nano-Se) in Hcy-mediated vascular endothelial cell dysfunction in vitro and in vivo.

Materials and Methods

By incubating vascular endothelial cells with exogenous Hcy and generating hyperhomocysteinemic rat model, the effects of Nano-Se on hyperhomocysteinemia-mediated endothelial dysfunction and its essential mechanisms were investigated.

Results

Nano-Se inhibited Hcy-induced mitochondrial oxidative damage and apoptosis by preventing the downregulation of glutathione peroxidase enzyme 1 and 4 (GPX1, GPX4) in the vascular endothelial cells, thus effectively prevented the vascular damage in vitro and in vivo in the hyperhomocysteinemic rats. Nano-Se possessed similar protective effects but lower toxicity against Hcy in vascular endothelial cells when compared with other forms of Se.

Conclusion

The application of Nano-Se could serve as a novel promising strategy against Hcy-mediated vascular dysfunction with reduced risk of Se toxicity.

The Role of PGC-1α and Mitochondrial Biogenesis in Kidney Diseases

Chronic kidney disease (CKD) is one of the fastest growing causes of death worldwide, emphasizing the need to develop novel therapeutic approaches. CKD predisposes to acute kidney injury (AKI) and AKI favors CKD progression. Mitochondrial derangements are common features of both AKI and CKD and mitochondria-targeting therapies are under study as nephroprotective agents. PGC-1α is a master regulator of mitochondrial biogenesis and an attractive therapeutic target. Low PGC-1α levels and decreased transcription of its gene targets have been observed in both preclinical AKI (nephrotoxic, endotoxemia, and ischemia-reperfusion) and in experimental and human CKD, most notably diabetic nephropathy. In mice, PGC-1α deficiency was associated with subclinical CKD and predisposition to AKI while PGC-1α overexpression in tubular cells protected from AKI of diverse causes. Several therapeutic strategies may increase kidney PGC-1α activity and have been successfully tested in animal models. These include AMP-activated protein kinase (AMPK) activators, phosphodiesterase (PDE) inhibitors, and anti-TWEAK antibodies. In conclusion, low PGC-1α activity appears to be a common feature of AKI and CKD and recent characterization of nephroprotective approaches that increase PGC-1α activity may pave the way for nephroprotective strategies potentially effective in both AKI and CKD.

Significant decrease of von Willebrand factor and plasminogen activator inhibitor-1 by providing supplementation with selenium and coenzyme Q10 to an elderly population with a low selenium status

Purpose

Endothelial dysfunction and inflammation are conditions which fuel atherosclerosis and ischaemic heart disease. We have previously reported reduced cardiovascular (CV) mortality following supplementation with selenium and coenzyme Q10 to 443 elderly individuals with low selenium status (mean 67 μg/L) for 4 years. Here, we wanted to evaluate a possible association between the supplementation and the plasma concentrations of the von Willebrand factor (vWf), and the plasminogen activator inhibitor-1 (PAI-1), as they, besides other functions, are also strongly associated with endothelial function.

Methods

In this sub-study, 308 individuals (active substance: 157, placebo: 151) were included. Blood samples were drawn after 6 and 36 months and vWf and PAI-1 were determined in plasma by ELISA. Changes in concentrations of the biomarkers were evaluated by the use of T tests, repeated measures of variance, and ANCOVA analyses.

Results

The active treatment group presented a lower level of vWf after 36 months compared with the placebo group (1.08 U/mL vs. 5.10 U/mL; p = 0.0007). The results were validated through the repeated measures of variance evaluation. The PAI-1 levels showed an equally significant decrease in the active group (26.2 ng/mL vs. 49.2 ng/mL; p = 0.0002) and were also validated through repeated measures of variance evaluation.

Conclusion

In this sub-study on elderly receiving selenium and coenzyme Q10, or placebo we found significantly lower levels of vWf and PAI-1 in the active treatment group as compared to the placebo group. We interpret this as a better endothelial function because of the intervention, which accords with a previous finding of reduced CV mortality.