Selenium and RNA Virus Interactions: Potential Implications for SARS-CoV-2 Infection (COVID-19)

Nutrition and immunity: lessons from coronavirus disease-2019

This review will provide an overview of the immune system and then describe the effects of frailty, obesity, specific micronutrients and the gut microbiota on immunity and susceptibility to infection including data from the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic where relevant. A key role for the immune system is providing host defence against pathogens. Impaired immunity predisposes to infections and to more severe infections and weakens the response to vaccination. A range of nutrients, including many micronutrients, play important roles in supporting the immune system to function. The immune system can decline in later life and this is exaggerated by frailty. The immune system is also weakened with obesity, generalised undernutrition and micronutrient deficiencies, which all result in increased susceptibility to infection. Findings obtained during the SARS-CoV-2 pandemic support what was already known about the effects of ageing, frailty and obesity on immunity and susceptibility to infection. Observational studies conducted during the pandemic also support previous findings that multiple micronutrients including vitamins C, D and E, zinc and selenium and long-chain n-3 fatty acids are important for immune health, but whether these nutrients can be used to treat those already with coronavirus disease discovered in 2019 (COVID-19), particularly if already hospitalised, is uncertain from current inconsistent or scant evidence. There is gut dysbiosis in patients with COVID-19 and studies with probiotics report clinical improvements in such patients. There is an inverse association between adherence to a healthy diet and risk of SARS-CoV-2 infection and hospitalisation with COVID-19 which is consistent with the effects of individual nutrients and other dietary components. Addressing frailty, obesity and micronutrient insufficiency will be important to reduce the burden of future pandemics and nutritional considerations need to be a central part of the approach to preventing infections, optimising vaccine responses and promoting recovery from infection.

Melatonin: A novel and beneficial substance in sweet potatoes through selenium application

The effects of foliar Se (selenium) fertilizer on melatonin and its biosynthesis in four different colored sweet potatoes were studied. Solutions containing 1.25 mg Se/plant of inorganic selenium (ISe) and organic selenium (OSe) and a control check (CK) were applied three times during the swelling stage. Except for ISe in purple variety, both types of Se applications significantly increased melatonin in four colored varieties. The effect of OSe was greater than that of ISe, mainly because of higher concentration of tryptophan and activities of tryptophan decarboxylase, tryptamine-5 hydroxylase, 5-hydroxytryptamine N-acetyltransferase and N-acetyl-5-hydroxytryptamine methyltransferase. The orange variety had highest melatonin with the application of ISe and OSe, and highest melatonin among all applications was achieved by OSe in orange variety, followed by OSe in purple variety. These findings revealed that melatonin with extremely strong health benefits could be found and significantly increased in sweet potatoes through Se applications.

Role of Metals on SARS-CoV-2 Infection: a Review of Recent Epidemiological Studies

PURPOSE OF REVIEW

Metals and metalloids are known for their nutritional as well as toxic effects in humans. In the context of the SARS-CoV-2 pandemic, understanding the role of metals on COVID-19 infection is becoming important due to their role in infectious diseases. During the past 2 years, a significant number of studies have examined the impact of metals and metalloids on COVID-19 morbidity and mortality. We conducted a systematic review of peer-reviewed manuscripts on the association of metals and metalloids with SARS-CoV-2 infection and COVID-19 severity published since the onset of the pandemic.

RECENT FINDINGS

We searched for epidemiological studies available through the PubMed database published from January 2020 to December 2022. Of 92 studies identified, 20 met our inclusion criteria. These articles investigated the association of zinc (Zn), iron (Fe), selenium (Se), manganese (Mn), cadmium (Cd), arsenic (As), copper (Cu), magnesium (Mg), chromium (Cr), and/or lead (Pb) levels on SARS-CoV-2 infection and/or COVID-19 severity. Of the ten metals and metalloids of interest that reported either positive, negative, or no associations, Zn yielded the highest number of articles (n = 13), followed by epidemiological studies on Se (n = 7) and Fe (n = 5). Elevated serum Zn and Se were associated with reduced COVID-19 severity and mortality. Similarly, higher levels of serum Fe were associated with lower levels of cellular damage and symptoms of SARS-CoV-2 infection and with faster recovery from COVID-19. On the other hand, higher serum and urinary Cu and serum Mg levels were associated with higher COVID-19 severity and mortality. Along with the positive or negative effects, some studies reported no impact of metals on SARS-CoV-2 infection. This systematic review suggests that metals, particularly Zn, Fe, and Se, may help reduce the severity of COVID-19, while Cu and Mg may aggravate it. Our review suggests that future pandemic mitigation strategies may evaluate the role of Zn, Se, and Fe as potential therapeutic interventions.

Metal-coding assisted serological multi-omics profiling deciphers the role of selenium in COVID-19 immunity

Uncovering how host metal(loid)s mediate the immune response against invading pathogens is critical for better understanding the pathogenesis mechanism of infectious disease. Clinical data show that imbalance of host metal(loid)s is closely associated with the severity and mortality of COVID-19. However, it remains elusive how metal(loid)s, which are essential elements for all forms of life and closely associated with multiple diseases if dysregulated, are involved in COVID-19 pathophysiology and immunopathology. Herein, we built up a metal-coding assisted multiplexed serological metallome and immunoproteome profiling system to characterize the links of metallome with COVID-19 pathogenesis and immunity. We found distinct metallome features in COVID-19 patients compared with non-infected control subjects, which may serve as a biomarker for disease diagnosis. Moreover, we generated the first correlation network between the host metallome and immunity mediators, and unbiasedly uncovered a strong association of selenium with interleukin-10 (IL-10). Supplementation of selenium to immune cells resulted in enhanced IL-10 expression in B cells and reduced induction of proinflammatory cytokines in B and CD4+ T cells. The selenium-enhanced IL-10 production in B cells was confirmed to be attributable to the activation of ERK and Akt pathways. We further validated our cellular data in SARS-CoV-2-infected K18-hACE2 mice, and found that selenium supplementation alleviated SARS-CoV-2-induced lung damage characterized by decreased alveolar inflammatory infiltrates through restoration of virus-repressed selenoproteins to alleviate oxidative stress. Our approach can be readily extended to other diseases to understand how the host defends against invading pathogens through regulation of metallome.

Selenium intake and multiple health-related outcomes: an umbrella review of meta-analyses

Selenium is an essential trace metalloid element that is associated with fundamental importance to human health. Our umbrella review aimed to evaluate the quality of evidence, validity, and biases in the relationship between selenium intake and health-related outcomes according to published systematic reviews with pooled data and meta-analyses. Selenium intake is associated with a decreased risk of digestive system cancers, all-cause mortality, depression, and Keshan disease, when in children reduce the risk of Kashin-Beck disease. Additionally, selenium supplementation can improve sperm quality, polycystic ovary syndrome, autoimmune thyroid disease, cardiovascular disease, and infective outcomes. Selenium supplementation also has relationship with a decreased concentration of serum lipids including total cholesterol and very low-density lipoprotein cholesterol. However, no evidence has shown that selenium is associated with better outcomes among patients in intensive care units. Furthermore, selenium intake may be related with a higher risk of type 2 diabetes and non-melanoma skin cancers. Moreover, most of included studies are evaluated as low quality according to our evidence assessment. Based on our study findings and the limited advantages of selenium intake, it is not recommended to receive extra supplementary selenium for general populations, and selenium supplementation should not be continued in patients whose selenium-deficient status has been corrected.

An extensive review on antifungal approaches in the treatment of mucormycosis

During the period of COVID-19, the occurrences of mucormycosis in immunocompromised patients have increased significantly. Mucormycosis (black fungus) is a rare and rapidly progressing fungal infection associated with high mortality and morbidity in India as well as globally. The causative agents for this infection are collectively called mucoromycetes which are the members of the order Mucorales. The diagnosis of the infection needs to be performed as soon as the occurrence of clinical symptoms which differs with types of Mucorales infection. Imaging techniques magnetic resonance imaging or computed tomography scan, culture testing, and microscopy are the approaches for the diagnosis. After the diagnosis of the infection is confirmed, rapid action is needed for the treatment in the form of antifungal therapy or surgery depending upon the severity of the infection. Delaying in treatment declines the chances of survival. In antifungal therapy, there are two approaches first-line therapy (monotherapy) and combination therapy. Amphotericin B (1) and isavuconazole (2) are the drugs of choice for first-line therapy in the treatment of mucormycosis. Salvage therapy with posaconazole (3) and deferasirox (4) is another approach for patients who are not responsible for any other therapy. Adjunctive therapy is also used in the treatment of mucormycosis along with first-line therapy, which involves hyperbaric oxygen and cytokine therapy. There are some drugs like VT-1161 (5) and APX001A (6), Colistin, SCH 42427, and PC1244 that are under clinical trials. Despite all these approaches, none can be 100% successful in giving results. Therefore, new medications with favorable or little side effects are required for the treatment of mucormycosis.

Targeted Application of Functional Foods as Immune Fitness Boosters in the Defense against Viral Infection

In recent times, the emergence of viral infections, including the SARS-CoV-2 virus, the monkeypox virus, and, most recently, the Langya virus, has highlighted the devastating effects of viral infection on human life. There has been significant progress in the development of efficacious vaccines for the prevention and control of viruses; however, the high rates of viral mutation and transmission necessitate the need for novel methods of control, management, and prevention. In recent years, there has been a shift in public awareness on health and wellbeing, with consumers making significant dietary changes to improve their immunity and overall health. This rising health awareness is driving a global increase in the consumption of functional foods. This review delves into the benefits of functional foods as potential natural means to modulate the host immune system to enhance defense against viral infections. We provide an overview of the functional food market in Europe and discuss the benefits of enhancing immune fitness in high-risk groups, including the elderly, those with obesity, and people with underlying chronic conditions. We also discuss the immunomodulatory mechanisms of key functional foods, including dairy proteins and hydrolysates, plant-based functional foods, fermentates, and foods enriched with vitamin D, zinc, and selenium. Our findings reveal four key immunity boosting mechanisms by functional foods, including inhibition of viral proliferation and binding to host cells, modulation of the innate immune response in macrophages and dendritic cells, enhancement of specific immune responses in T cells and B cells, and promotion of the intestinal barrier function. Overall, this review demonstrates that diet-derived nutrients and functional foods show immense potential to boost viral immunity in high-risk individuals and can be an important approach to improving overall immune health.

Preventative and therapeutic potential of animal milk components against COVID-19: A comprehensive review

The global pandemic of COVID-19 is considered one of the most catastrophic events on earth. During the pandemic, food ingredients may play crucial roles in preventing infectious diseases and sustaining people's general health and well-being. Animal milk acts as a super food since it has the capacity to minimize the occurrence of viral infections due to inherent antiviral properties of its ingredients. SARS-CoV-2 virus infection can be prevented by immune-enhancing and antiviral properties of caseins, α-lactalbumin, β-lactoglobulin, mucin, lactoferrin, lysozyme, lactoperoxidase, oligosaccharides, glycosaminoglycans, and glycerol monolaurate. Some of the milk proteins (i.e., lactoferrin) may work synergistically with antiviral medications (e.g., remdesivir), and enhance the effectiveness of treatment in this disease. Cytokine storm during COVID-19 can be managed by casein hydrolyzates, lactoferrin, lysozyme, and lactoperoxidase. Thrombus formation can be prevented by casoplatelins as these can inhibit human platelet aggregation. Milk vitamins (i.e., A, D, E, and B complexes) and minerals (i.e., Ca, P, Mg, Zn, and Se) can have significantly positive effects on boosting the immunity and health status of individuals. In addition, certain vitamins and minerals can also act as antioxidants, anti-inflammatory, and antivirals. Thus, the overall effect of milk might be a result of synergistic antiviral effects and host immunomodulator activities from multiple components. Due to multiple overlapping functions of milk ingredients, they can play vital and synergistic roles in prevention as well as supportive agents during principle therapy of COVID-19.

Individual blood concentrations of persistent organic pollutants and chemical elements, and COVID-19: A prospective cohort study in Barcelona

BACKGROUND

There is wide, largely unexplained heterogeneity in immunological and clinical responses to SARS-CoV-2 infection. Numerous environmental chemicals, such as persistent organic pollutants (POPs) and chemical elements (including some metals, essential trace elements, rare earth elements, and minority elements), are immunomodulatory and cause a range of adverse clinical events. There are no prospective studies on the effects of such substances on the incidence of SARS-CoV-2 infection and COVID-19.

OBJECTIVE

To investigate the influence of blood concentrations of POPs and elements measured several years before the pandemic on the development of SARS-CoV-2 infection and COVID-19 in individuals from the general population.

METHODS

We conducted a prospective cohort study in 154 individuals from the general population of Barcelona. POPs and elements were measured in blood samples collected in 2016-2017. SARS-CoV-2 infection was detected by rRT-PCR in nasopharyngeal swabs and/or by antibody serology using eighteen isotype-antigen combinations measured in blood samples collected in 2020-2021. We analyzed the associations between concentrations of the contaminants and SARS-CoV-2 infection and development of COVID-19, taking into account personal habits and living conditions during the pandemic.

RESULTS

Several historically prevalent POPs, as well as arsenic, cadmium, mercury, and zinc, were not associated with COVID-19, nor with SARS-CoV-2 infection. However, DDE (adjusted OR = 5.0 [95% CI: 1.2-21]), lead (3.9 [1.0-15]), thallium (3.4 [1.0-11]), and ruthenium (5.0 [1.8-14]) were associated with COVID-19, as were tantalum, benzo(b)fluoranthene, DDD, and manganese. Thallium (3.8 [1.6-8.9]), and ruthenium (2.9 [1.3-6.7]) were associated with SARS-CoV-2 infection, and so were lead, gold, and (protectively) iron and selenium. We identified mixtures of up to five substances from several chemical groups, with all substances independently associated to the outcomes.

CONCLUSIONS

Our results provide the first prospective and population-based evidence of an association between individual concentrations of some contaminants and COVID-19 and SARS-CoV-2 infection. POPs and elements may contribute to explain the heterogeneity in the development of SARS-CoV-2 infection and COVID-19 in the general population. If the associations are confirmed as causal, means are available to mitigate the corresponding risks.

N-Acetyl Cysteine Restores the Diminished Activity of the Antioxidant Enzymatic System Caused by SARS-CoV-2 Infection: Preliminary Findings

SARS-CoV-2 infects type II pneumocytes and disrupts redox homeostasis by overproducing reactive oxygen species (ROS). N-acetyl cysteine (NAC) is a precursor of the synthesis of glutathione (GSH) and it restores the loss of redox homeostasis associated to viral infections. The aim of the study is to evaluate the effect of the treatment with NAC on the enzymatic antioxidant system in serum from patients infected by SARS-CoV-2. We evaluated the enzymatic activities of thioredoxin reductase (TrxR), glutathione peroxidase (GPx), -S-transferase (GST), and reductase (GR) by spectrophotometry and the concentrations of the glutathione (GSH), total antioxidant capacity (TAC), thiols, nitrites (NO₂^-), and lipid peroxidation (LPO) in serum. The activity of the extracellular super oxide dismutase (ecSOD) was determined by native polyacrylamide gels, and 3-nitrotyrosine (3-NT) was measured by ELISA. A decrease in the activities of the ecSOD, TrxR, GPx, GST GR, (p = 0 ≤ 0.1), and the GSH, TAC, thiols, and NO₂^- (p ≤ 0.001) concentrations and an increase in LPO and 3-NT (p = 0.001) concentrations were found in COVID-19 patients vs. healthy subjects. The treatment with NAC as an adjuvant therapy may contribute to a reduction in the OS associated to the infection by SARS-CoV-2 through the generation of GSH. GSH promotes the metabolic pathways that depend on it, thus contributing to an increase in TAC and to restore redox homeostasis.

The Role of Diet and Specific Nutrients during the COVID-19 Pandemic: What Have We Learned over the Last Three Years?

Nutrients and diets have an important impact on our immune system and infection risk and a huge number of papers have been published dealing with various aspects of nutrition in relation to SARS-CoV-2 infection risk or COVID-19 severity. This narrative review aims to give an update on this association and tries to summarize some of the most important findings after three years of pandemic. The analysis of major studies and systematic reviews leads to the conclusion that a healthy plant-based diet reduces the risks for SARS-CoV-2 infection and especially COVID-19 severity. Regarding micronutrients, vitamin D is to the fore, but also zinc, vitamin C and, to some extent, selenium may play a role in COVID-19. Furthermore, omega-3-fatty acids with their anti-inflammatory effects also deserve attention. Therefore, a major aim of societal nutritional efforts in future should be to foster a high quality plant-based diet, which not only exerts beneficial effects on the immune system but also reduces the risk for non-communicable diseases such as type 2 diabetes or obesity which are also primary risk factors for worse COVID-19 outcomes. Another aim should be to focus on a good supply of critical immune-effective nutrients, such as vitamin D and zinc.

Selenium Status and Oxidative Stress in SARS-CoV-2 Patients

Background and Objectives: Insufficient intake of essential micronutrient selenium (Se) increases the susceptibility to diseases associated with oxidative stress. The study aim was to assess Se status and oxidative stress in COVID-19 patients depending on severity of the disease. Materials and Methods: Blood plasma of 80 post-COVID-19 disease patients and 40 acutely ill patients were investigated. Concentration of Se was detected by a fluorometric method with di-amino-naphthalene using acidic hydrolysis. Selenoprotein P (Sepp1), malondialdehyde (MDA), and 4-hydroxynonenal (4-HNE) and their metabolite adducts were evaluated by spectrophotometric methods using commercial assay kits. Results: Obtained results demonstrated that Se and Sepp1 concentration in acute patients were significantly (p < 0.05 for Se and p < 0.001 for Sepp1) decreased compared with post-COVID-19 disease patients. However, in post-COVID-19 disease patients, Se values were close to the low limit of the norm for the European population. 4-HNE adducts concentration as a marker of lipid peroxidation was significantly increased in the acute patients group compared to the recovery group (p < 0.001). Conclusions: COVID-19 pathology is characterized by the induction of oxidative stress and suppression of antioxidant defenses during the acute phase. Lower levels of Se and Sepp1 and higher levels of reactive oxygen species reflect this imbalance, highlighting the role of oxidative stress in the disease’s pathogenesis.

An insight into biofabrication of selenium nanostructures and their biomedical application

Evidence shows that nanoparticles exert lower toxicity, improved targeting, and enhanced bioactivity, and provide versatile means to control the release profile of the encapsulated moiety. Among different NPs, inorganic nanoparticles (Ag, Au, Ce, Fe, Se, Te, Zn, etc.) possess a considerable place owing to their unique bioactivities in nanoforms. Selenium, an essential trace element, played a vital role in the growth and development of living organisms. It has attracted great interest as a therapeutic factor without significant adverse effects in medicine at recommended dose. Selenium nanoparticles can be fabricated by physical, biological, and chemical approaches. The biosynthesis of nanoparticles is shown an advance compared to other procedures, because it is environmentally friendly, relatively reproducible, easily accessible, biodegradable, and often results in more stable materials. The effect of size, shape, and synthesis methods on their applications in biological systems investigated by several studies. This review focused on the procedures for the synthesis of selenium nanoparticles, in particular the biogenesis of selenium nanoparticles and their biomedical characteristics, such as antibacterial, antiviral, antifungal, and antiparasitic properties. Eventually, a comprehensive future perspective of selenium nanoparticles was also presented.

An overview on role of nutrition on COVID-19 immunity: Accumulative review from available studies

The novel coronavirus infection (COVID-19) conveys a serious global threat to health and economy. A common predisposing factor for development to serious progressive disease is presence of a low-grade inflammation, e.g., as seen in diabetes, metabolic syndrome, and heart failure. Micronutrient deficiencies may also contribute to the development of this state. Therefore, the aim of the present study is to explore the role of the nutrition to relieve progression of COVID-19. According PRISMA protocol, we conducted an online databases search including Scopus, PubMed, Google Scholar and web of science for published literatures in the era of COVID-19 Outbreak regarding to the status of nutrition and COVID-19 until December 2021. There were available studies (80 studies) providing direct evidence regarding the associations between the status of nutrition and COVID-19 infection. Adequate nutritional supply is essential for resistance against other viral infections and also for improvement of immune function and reduction of inflammation. Hence, it is suggested that nutritional intervention which secures an adequate status might protect against the novel coronavirus SARS-CoV-2 (Severe Acute Respiratory Syndrome - coronavirus-2) and mitigate its course. We also recommend initiation of adequate nutritional supplementation in high-risk areas and/or soon after the time of suspected infection with SARS-CoV-2. Subjects in high-risk groups should have high priority for applying this nutritive adjuvant therapy that should be started prior to administration of specific and supportive medical measures.

Selenium in the Prevention of SARS-CoV-2 and Other Viruses

The rapid spread of new pathogens (SARS-CoV-2 virus) that negatively affect the human body has huge consequences for the global public health system and the development of the global economy. Appropriate implementation of new safety regulations will improve the functioning of the current model supervising the inhibition of the spread of COVID-19 disease. Compliance with all these standards will have a key impact on the health behavior of individual social groups. There have been demonstrably effective treatments that proved to be effective but were rapidly dismissed for unknown reasons, such as ivermectin and hydroxychloroquine. Various measures are used in the world to help inhibit its development. The properties of this element provide hope in preventing the development of the SARS-CoV-2 virus. The aim of this review is to synthesize the latest literature data and to present the effect of sodium selenite in reducing the incidence of COVID-19 disease.

Biogenic Selenium Nanoparticles in Biomedical Sciences: Properties, Current Trends, Novel Opportunities and Emerging Challenges in Theranostic Nanomedicine

Selenium is an important dietary supplement and an essential trace element incorporated into selenoproteins with growth-modulating properties and cytotoxic mechanisms of action. However, different compounds of selenium usually possess a narrow nutritional or therapeutic window with a low degree of absorption and delicate safety margins, depending on the dose and the chemical form in which they are provided to the organism. Hence, selenium nanoparticles (SeNPs) are emerging as a novel therapeutic and diagnostic platform with decreased toxicity and the capacity to enhance the biological properties of Se-based compounds. Consistent with the exciting possibilities offered by nanotechnology in the diagnosis, treatment, and prevention of diseases, SeNPs are useful tools in current biomedical research with exceptional benefits as potential therapeutics, with enhanced bioavailability, improved targeting, and effectiveness against oxidative stress and inflammation-mediated disorders. In view of the need for developing eco-friendly, inexpensive, simple, and high-throughput biomedical agents that can also ally with theranostic purposes and exhibit negligible side effects, biogenic SeNPs are receiving special attention. The present manuscript aims to be a reference in its kind by providing the readership with a thorough and comprehensive review that emphasizes the current, yet expanding, possibilities offered by biogenic SeNPs in the biomedical field and the promise they hold among selenium-derived products to, eventually, elicit future developments. First, the present review recalls the physiological importance of selenium as an oligo-element and introduces the unique biological, physicochemical, optoelectronic, and catalytic properties of Se nanomaterials. Then, it addresses the significance of nanosizing on pharmacological activity (pharmacokinetics and pharmacodynamics) and cellular interactions of SeNPs. Importantly, it discusses in detail the role of biosynthesized SeNPs as innovative theranostic agents for personalized nanomedicine-based therapies. Finally, this review explores the role of biogenic SeNPs in the ongoing context of the SARS-CoV-2 pandemic and presents key prospects in translational nanomedicine.

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.

Sodium Selenite As Potential Adjuvant Therapy for COVID-19

The review considers the role that selenium plays in RNA virus infections and, in particular, COVID-19. Many RNA viruses are selenium dependent because antisense interactions arise between viral RNAs and host mRNA regions containing the selencysteine insertion sequence to cause selenium deficiency, oxidative stress, immune response impairment, etc. Sodium selenite is a licensed selenium-containing product and is widely used in medicine, veterinary, and agriculture. Its advantages include the following. Sodium selenite rapidly penetrates through cell membranes in all tissues of the body; is intensely involved in metabolic processes accompanied by oxidation of sulfur-containing cell proteins; exerts an antiaggregation effect by reducing thromboxane activity; interrupts the contact of a virion (SARS-CoV-1 and SARS-CoV-2) with the membrane of a healthy cell; and suppresses NF-κB activity, which significantly increases in coronavirus infections. Arguments supporting the use of sodium selenite as adjuvant therapy in COVID-19 are discussed.

Vitamins, microelements and the immune system: current standpoint in the fight against coronavirus disease 2019

Coronavirus disease 2019 (COVID-19) is an acute respiratory disease associated with severe systemic inflammation. The optimal status of vitamins and microelements is considered crucial for the proper functioning of the immune system and necessary for successful recovery. Most patients with respiratory distress in COVID-19 are vitamin and microelement deficient, with vitamin D and Se deficiency being the most common. Anyway, various micronutrient supplements are widely and arbitrarily used for prevention or in the treatment of COVID-19. We aimed to summarise current knowledge about molecular and physiological mechanisms of vitamins (D, A, C, B₆, B₉ and B₁₂) and microelements (Se, Zn, Cu and Fe) involved in the immune system regulation in consideration with COVID-19 pathogenesis, as well as recent findings related to their usage and effects in the prevention and treatment of COVID-19. In the early course of the pandemic, several, mainly observational, studies reported an association of some micronutrients, such as vitamin C, D and Zn, with severity reduction and survival improvement. Still, emerging randomised controlled trials showed no effect of vitamin D on hospitalisation length and no effect of vitamin C and Zn on symptom reduction. Up to date, there is evidence neither for nor against the use of micronutrients in the treatment of COVID-19. The doses that exceed the recommended for the general population and age group should not be used, except in clinical trials. Benefits of supplementation are primarily expected in populations prone to micronutrient deficiencies, who are, as well, at a higher risk of worse outcomes in COVID-19.

Selenium and COVID-19: A spotlight on the clinical trials, inventive compositions, and patent literature

Selenium is an indispensable trace element for all living organisms. It is an essential structural component of several selenium-dependent enzymes, which support the human body's defense mechanism. Recently, the significance of selenium in preventing/treating COVID-19 has been documented in the literature. This review highlights the clinical studies, compositions, and patent literature on selenium to prevent/treat COVID-19. Selenium exerts its anti-COVID-19 action by reducing oxidative stress, declining the expression of the ACE-2 receptor, lowering the discharge of pro-inflammatory substances, and inhibiting the 3CLPro (main protease) and PLpro enzyme of SARS-CoV-2. The data of clinical studies, inventive compositions, and patent literature revealed that selenium monotherapy and its compositions with other nutritional supplements/drugs (vitamin, iron, zinc, copper, ferulic acid, resveratrol, spirulina, N-acetylcysteine, fish oil, many herbs, doxycycline, azithromycin, curcumin, quercetin, etc.,) might be practical to prevent/treat COVID-19. The studies have also suggested a correlation between COVID-19 and selenium deficiency. This indicates that adequate selenium supplementation may provide promising treatment outcomes in COVID-19 patients. The authors foresee the development and commercialization of Selenium-based compositions and dosage forms (spray, inhalers, control release dosage forms, etc.) to battle COVID-19. We also trust that numerous selenium-based compositions are yet to be explored. Accordingly, there is good scope for scientists to work on developing novel and inventive selenium-based compositions to fight against COVID-19. However, there is also a need to consider the narrow therapeutic window and chemical interaction of selenium before developing selenium-based compositions.

Antioxidant, Anti-inflammatory, and Immunomodulatory Roles of Nonvitamin Antioxidants in Anti-SARS-CoV-2 Therapy

Viral pathologies encompass activation of pro-oxidative pathways and inflammatory burst. Alleviating overproduction of reactive oxygen species and cytokine storm in COVID-19 is essential to counteract the immunogenic damage in endothelium and alveolar membranes. Antioxidants alleviate oxidative stress, cytokine storm, hyperinflammation, and diminish the risk of organ failure. Direct antiviral roles imply: impact on viral spike protein, interference with the ACE2 receptor, inhibition of dipeptidyl peptidase 4, transmembrane protease serine 2 or furin, and impact on of helicase, papain-like protease, 3-chyomotrypsin like protease, and RNA-dependent RNA polymerase. Prooxidative environment favors conformational changes in the receptor binding domain, promoting the affinity of the spike protein for the host receptor. Viral pathologies imply a vicious cycle, oxidative stress promoting inflammatory responses, and vice versa. The same was noticed with respect to the relationship antioxidant impairment-viral replication. Timing, dosage, pro-oxidative activities, mutual influences, and interference with other antioxidants should be carefully regarded. Deficiency is linked to illness severity.

Exploring nanoselenium to tackle mutated SARS-CoV-2 for efficient COVID-19 management

Despite ongoing public health measures and increasing vaccination rates, deaths and disease severity caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and its new emergent variants continue to threaten the health of people around the world. Therefore, there is an urgent need to develop novel strategies for research, diagnosis, treatment, and government policies to combat the variant strains of SARS-CoV-2. Since the state-of-the-art COVID-19 pandemic, the role of selenium in dealing with COVID-19 disease has been widely discussed due to its importance as an essential micronutrient. This review aims at providing all antiviral activities of nanoselenium (Nano-Se) ever explored using different methods in the literature. We systematically summarize the studied antiviral activities of Nano-Se required to project it as an efficient antiviral system as a function of shape, size, and synthesis method. The outcomes of this article not only introduce Nano-Se to the scientific community but also motivate scholars to adopt Nano-Se to tackle any serious virus such as mutated SARS-CoV-2 to achieve an effective antiviral activity in a desired manner.

Nutrition, Immunosenescence, and Infectious Disease: An Overview of the Scientific Evidence on Micronutrients and on Modulation of the Gut Microbiota

The immune system is key to host defense against pathogenic organisms. Aging is associated with changes in the immune system, with a decline in protective components (immunosenescence), increasing susceptibility to infectious disease, and a chronic elevation in low-grade inflammation (inflammaging), increasing the risk of multiple noncommunicable diseases. Nutrition is a determinant of immune cell function and of the gut microbiota. In turn, the gut microbiota shapes and controls the immune and inflammatory responses. Many older people show changes in the gut microbiota. Age-related changes in immune competence, low-grade inflammation, and gut dysbiosis may be interlinked and may relate, at least in part, to age-related changes in nutrition. A number of micronutrients (vitamins C, D, and E and zinc and selenium) play roles in supporting the function of many immune cell types. Some trials report that providing these micronutrients as individual supplements can reverse immune deficits in older people and/or in those with insufficient intakes. There is inconsistent evidence that this will reduce the risk or severity of infections including respiratory infections. Probiotic, prebiotic, or synbiotic strategies that modulate the gut microbiota, especially by promoting the colonization of lactobacilli and bifidobacteria, have been demonstrated to modulate some immune and inflammatory biomarkers in older people and, in some cases, to reduce the risk and severity of gastrointestinal and respiratory infections, although, again, the evidence is inconsistent. Further research with well-designed and well-powered trials in at-risk older populations is required to be more certain about the role of micronutrients and of strategies that modify the gut microbiota-host relationship in protecting against infection, especially respiratory infection.

Assessment of Serum Zinc and Selenium Levels in Children with COVID-19

Objective Zinc and selenium levels are being investigated with increasing frequency in adult patients with coronavirus disease 2019 (COVID-19). However, levels of zinc and selenium in children with COVID-19 have not been adequately studied to date.

Methods This prospective, observational study was conducted on 146 pediatric patients diagnosed with COVID-19 and 49 healthy controls between 2020 and 2021. Normal serum zinc reference values were 0.60 to 1.20 µg/mL for children 0 to 10 years old and 0.66 to 1.10 µg/mL for children ≥11 years old. The normal range for serum selenium concentration was considered between 70 and 150 µg/L. Deficiencies were defined for values below the reference range.

Results Zinc and selenium levels were significantly lower in the COVID-19 (+) group compared with the controls (zinc: 0.7 ± 0.2 vs 0.9 ± 0.2 µg/mL, p < 0.001; selenium: 57.1 ± 9.1 vs 66.5 ± 11.4 µg/L, p < 0.01, respectively). Also, zinc and selenium levels were found to be statistically significantly lower in the hospitalized group compared with the outpatient group (zinc: 0.6 ± 0.2 vs 0.8 ± 0.2 µg/mL, p < 0.001; selenium: 52.1 ± 9.6 vs 58.8 ± 8.3 µg/L, p < 0.001). In the receiver operating characteristic curve analysis, selenium levels with a cutoff value of 55.50 µg/L, with 75% sensitivity and 70% specificity, and zinc levels with a cutoff value of 0.7 µg/mL, with 56% sensitivity and 53% specificity, predicted hospitalization.

Conclusion Our data showed that serum zinc and selenium levels were significantly lower in patients with COVID-19 compared with healthy control group. Also, zinc and selenium levels were found to be lower in the hospitalized group compared with the outpatient COVID-19 group.

Thyroidal and Extrathyroidal Requirements for Iodine and Selenium: A Combined Evolutionary and (Patho)Physiological Approach

Iodide is an antioxidant, oxidant and thyroid hormone constituent. Selenoproteins are needed for triiodothyronine synthesis, its deactivation and iodine release. They also protect thyroidal and extrathyroidal tissues from hydrogen peroxide used in the 'peroxidase partner system'. This system produces thyroid hormone and reactive iodine in exocrine glands to kill microbes. Exocrine glands recycle iodine and with high urinary clearance require constant dietary supply, unlike the thyroid. Disbalanced iodine-selenium explains relations between thyroid autoimmune disease (TAD) and cancer of thyroid and exocrine organs, notably stomach, breast, and prostate. Seafood is iodine unconstrained, but selenium constrained. Terrestrial food contains little iodine while selenium ranges from highly deficient to highly toxic. Iodine vs. TAD is U-shaped, but only low selenium relates to TAD. Oxidative stress from low selenium, and infection from disbalanced iodine-selenium, may generate cancer of thyroid and exocrine glands. Traditional Japanese diet resembles our ancient seashore-based diet and relates to aforementioned diseases. Adequate iodine might be in the milligram range but is toxic at low selenium. Optimal selenoprotein-P at 105 µg selenium/day agrees with Japanese intakes. Selenium upper limit may remain at 300-400 µg/day. Seafood combines iodine, selenium and other critical nutrients. It brings us back to the seashore diet that made us what we currently still are.

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.

Selenium and mercury concentrations in biological samples from patients with COVID-19

BACKGROUND

Coronavirus disease 2019 (COVID-19) is a systemic disease affecting multiple organs. Furthermore, viral infection depletes several trace elements and promotes complex biochemical reactions in the body. Smoking has been linked to the incidence of COVID-19 and associated mortality, and it may impact clinical effects, viral and bacterial conversion, and treatment outcomes.

OBJECTIVES

To study the relationship between severe acute respiratory syndrome coronavirus type 2 and the elemental concentrations of selenium (Se) and mercury (Hg) in biological samples from smokers and nonsmokers infected with the virus and in healthy individuals.

METHOD

We evaluated changes in the concentrations of essential (Se) and toxic (Hg) elements in biological samples (blood, nasal fluid, saliva, sputum, serum, and scalp hair) collected from male smokers and nonsmokers (aged 29-59 years) infected with COVID-19 and from healthy men in the same age group. The patients lived in different cities in Sindh Province, Pakistan. The Se and Hg concentrations were determined using atomic absorption spectrophotometry.

RESULTS

Se concentrations in all types of biological samples from smokers and nonsmokers with COVID-19 were lower than those of healthy smokers and nonsmokers. Hg concentrations were elevated in both smokers and nonsmokers with COVID-19.

CONCLUSIONS

In the current study, persons infected with COVID-19 had higher concentrations of toxic Hg, which could cause physiological disorders, and low concentrations of essential Se, which can also cause weakness. COVID-19 infection showed positive correlations with levels of mercury and selenium. Thus, additional clinical and experimental investigations are essential.

COVID-19 and Selenium Deficiency: a Systematic Review

Several studies have indicated that selenium deficiency may be detrimental in the context of various viral disorders, and in the case of COVID-19, several studies have reported heterogeneous results concerning the association of selenium deficiency with the severity of disease. To summarize the available data surrounding the association of body selenium levels with the outcomes of COVID-19, a systematic search was performed in the Medline database (PubMed), Scopus, Cochrane Library, Embase, and Web of Science using keywords including "SARS-CoV-2," "COVID-19," and "selenium," Studies evaluating the association of COVID-19 with body selenium levels were included. Among 1,862 articles viewed in the database search, 10 articles were included after title, abstract, and full-text review. One study was further included after searching the literature again for any newly published articles. Out of 11 included studies, 10 studies measured serum selenium level, and one study investigated urinary selenium level. Three of 10 studies measured serum SELENOP level as well as selenium level. Glutathione peroxidase-3 level in serum was also assessed in one study. The reported outcomes were severity, mortality, and risk of COVID-19. Nine studies indicated that a lower serum selenium level is associated with worse outcomes. Two studies reported no significant association between serum selenium level and COVID-19. In one study, urinary selenium level was reported to be higher in severe and fatal cases compared to non-severe and recovered patients, respectively. In most cases, selenium deficiency was associated with worse outcomes, and selenium levels in COVID-19 patients were lower than in healthy individuals. Thus, it could be concluded that cautious selenium supplementation in COVID-19 patients may be helpful to prevent disease progression. However, randomized clinical trials are needed to confirm this.

Clinical nutrition approach in medical management of COVID-19 hospitalized patients: A narrative review

BACKGROUND

Malnutrition in COVID-19 hospitalized patients is associated with a high-risk condition to increase disease severity and prolonging the recovery period. Therefore, nutritional therapy, including supplements plays a critical role to reduce disease-related complications and the length of hospital stay.

AIM

To review the latest evidence on nutritional management options in COVID-19 hospitalized patients, as well as possibly prescribed supplements. Methods: This review was conducted by considering the latest recommendations, using the guidelines of the American Society of Enteral and Parenteral (ASPEN) and the European Society of Enteral and Parenteral (ESPEN), and searching Web of Science, PubMed/Medline, ISI, and Medline databases. The relevant articles were found using a mix of related mesh terms and keywords. We attempted to cover all elements of COVID-19 hospitalized patients' dietary management. Results: Energy demand in COVID-19 patients is a vital issue. Indirect Calorimetry (IC) is the recommended method to measure resting energy expenditure. However, in the absence of IC, predictive equations may be used. The ratio of administered diet for the macronutrients could be based on the phase and severity of Covid-19 disease. Moreover, there are recommendations for taking micronutrient supplements with known effects on improving the immune system or reducing inflammation. Conclusions: Nutritional treatment of COVID-19 patients in hospitals seems to be an important element of their medical care. Enteral nutrition would be the recommended feeding method for early nutrition support. However, data in the COVID-19 nutritional domain relating to micronutrient supplementation are still fragmentary and disputed, and further study is required.

Circulating trace elements status in COVID-19 disease: A meta-analysis

Trace elements are a group of essential metals or metalloids, which are necessary for life, and present in minute amounts. Despite substantial researches highlighting the importance of trace elements in Coronavirus disease 2019 (COVID-19) diseases, a thorough evaluation of the levels of circulating trace elements is lacking. Therefore, we conducted a systematic review and meta-analysis to evaluate the trace element status (Zn, Fe, Cu, Mg, and Se) in COVID-19 disease. We also assessed the relationship between circulating trace elements and COVID-19 disease severity and survival status during follow-up. We searched comprehensively MEDLINE, Web of Science, CNKI, and WangFang databases without language restriction, between November 1, 2019 and April 1, 2022. The search identified 1,566 preliminary references. A total of 49 studies met the eligibility criteria and were included in the review, and 42 studies were included in the final meta-analysis. Meta-analysis showed that COVID-19 patients had significantly lower circulating Zn (SMD: -0.83, 95% CI: -1.19 to -0.46, P < 0.001), Fe (SMD: -1.56, 95% CI: -2.90 to -0.21, P = 0.023), and Se (SMD: -0.75, 95% CI: -0.94 to -0.56, P < 0.001) levels than healthy controls, and circulating Zn (SMD: -0.47, 95% CI: -0.75 to -0.18, P = 0.002), Fe (SMD: -0.45, 95% CI: -0.79 to -0.12, P = 0.008), and Se (SMD: -0.27, 95% CI: -0.49 to -0.04, P = 0.020) levels were associated with the presence of severity status in COVID-19 patients. Moreover, circulating Fe levels in non-survivors were significantly lower than survivors in COVID-19 (SMD: -0.28, 95% CI: -0.44 to -0.12, P = 0.001). However, there was no significant difference in Cu and Mg levels between COVID-19 patients and controls, severity and non-severity status, and survivors and non-survivors (all P > 0.05). Taken together, COVID-19 patients displayed lower circulating levels of Zn, Fe, and Se, and their levels were associated with severity status. Moreover, circulating Fe levels may provide part of the explanation for the unfavorable survival status. Therefore, we presumed optimistically that supplements of trace elements might provide an adjutant treatment in the early stages of COVID-19.

Systematic review registration

[https://www.crd.york.ac.uk/prospero], identifier [CRD42022348599].

Protective and detoxifying effects conferred by selenium against mycotoxins and livestock viruses: A review

Animal feed can easily be infected with molds during production and storage processes, and this can lead to the production of secondary metabolites, such as mycotoxins, which eventually threaten human and animal health. Furthermore, livestock production is also not free from viral infections. Under these conditions, the essential trace element, selenium (Se), can confer various biological benefits to humans and animals, especially due to its anticancer, antiviral, and antioxidant properties, as well as its ability to regulate immune responses. This article reviews the latest literature on the antagonistic effects of Se on mycotoxin toxicity and viral infections in animals. We outlined the systemic toxicity of mycotoxins and the primary mechanisms of mycotoxin-induced toxicity in this analysis. In addition, we pay close attention to how mycotoxins and viral infections in livestock interact. The use of Se supplementation against mycotoxin-induced toxicity and cattle viral infection was the topic of our final discussion. The coronavirus disease 2019 (COVID-19) pandemic, which is currently causing a health catastrophe, has altered our perspective on health concerns to one that is more holistic and increasingly embraces the One Health Concept, which acknowledges the interdependence of humans, animals, and the environment. In light of this, we have made an effort to present a thorough and wide-ranging background on the protective functions of selenium in successfully reducing mycotoxin toxicity and livestock viral infection. It concluded that mycotoxins could be systemically harmful and pose a severe risk to human and animal health. On the contrary, animal mycotoxins and viral illnesses have a close connection. Last but not least, these findings show that the interaction between Se status and host response to mycotoxins and cattle virus infection is crucial.

Chitosan-Coated Selenium Nanoparticles Attenuate PRRSV Replication and ROS/JNK-Mediated Apoptosis in vitro

INTRODUCTION

Porcine reproductive and respiratory syndrome virus (PRRSV) is a highly prevalent and endemic swine pathogen that causes significant economic losses to the global swine industry. Selenium nanoparticles (SeNPs) have attracted increasing attention in the biomedical field, given their antiviral effects. This study aimed to investigate the inhibitory effect of chitosan-coated SeNPs (CS-SeNPs) on PRRSV replication.

METHODS

In this study, CS-SeNPs were synthesized by chemical reduction and characterized by assessing the morphology, size distribution, zeta potential, and element composition. Marc-145 cells were infected with r-PRRSV-EGFP (0.1 MOI) and inoculated with CS-SeNPs (10 μM). Subsequently, the concentrations of hydrogen peroxide (H2O2) and glutathione (GSH), and glutathione peroxidase (GSH-Px) activity were measured using specific commercial assay kits. ORF5 RNA expression, viral titer, and nucleocapsid (N) protein expression were assessed using qRT-PCR, TCID50, and Western blot. ROS generation, apoptosis rates, and JNK /caspase-3/PARP protein expression were evaluated using dihydroethidium staining, flow cytometry, and Western blot.

RESULTS

The results showed that CS-SeNPs treatment significantly suppressed oxidative stress induced by r-PRRSV-EGFP infection by increasing GSH-Px activity, promoting GSH production, and inhibiting H2O2 synthesis. CS-SeNPs treatment significantly inhibited ORF5 gene expression, viral titers, and N protein of r-PRRSV-EGFP at 24 and 48 hours post-infection (hpi) in Marc-145 cells. The increase in apoptosis rates induced by r-PRRSV-EGFP infection was significantly decreased by CS-SeNPs inoculation through inhibiting ROS generation, JNK phosphorylation levels, and cleavage of caspase-3 and PARP mainly at 48 hpi.

CONCLUSION

These results demonstrated that CS-SeNPs suppress PRRSV-induced apoptosis in Marc-145 cells via the ROS/JNK signaling pathway, thereby inhibiting PRRSV replication, which suggested the potential antiviral activity of CS-SeNPs that deserves further investigation for clinical applications.

The Roles and Pathogenesis Mechanisms of a Number of Micronutrients in the Prevention and/or Treatment of Chronic Hepatitis, COVID-19 and Type-2 Diabetes Mellitus

A trace element is a chemical element with a concentration (or other measures of an amount) that is very low. The essential TEs, such as copper (Cu), selenium (Se), zinc (Zn), iron (Fe) and the electrolyte magnesium (Mg) are among the most commonly studied micronutrients. Each element has been shown to play a distinctive role in human health, and TEs, such as iron (Fe), zinc (Zn) and copper (Cu), are among the essential elements required for the organisms' well-being as they play crucial roles in several metabolic pathways where they act as enzyme co-factors, anti-inflammatory and antioxidant agents. Epidemics of infectious diseases are becoming more frequent and spread at a faster pace around the world, which has resulted in major impacts on the economy and health systems. Different trace elements have been reported to have substantial roles in the pathogenesis of viral infections. Micronutrients have been proposed in various studies as determinants of liver disorders, COVID-19 and T2DM risks. This review article sheds light on the roles and mechanisms of micronutrients in the pathogenesis and prevention of chronic hepatitis B, C and E, as well as Coronavirus-19 infection and type-2 diabetes mellitus. An update on the status of the aforementioned micronutrients in pre-clinical and clinical settings is also briefly summarized.

Metallomic and Untargeted Metabolomic Signatures of Human Milk from SARS-CoV-2 Positive Mothers

Scope

Lack of information about the impact of maternal severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) infection on the elemental and metabolomic profile of human milk (HM).

Methods and results

An observational study on HM from mothers with COVID‐19 is conducted including a prepandemic control group. Maternal–infant clinical records and symptomatology are recorded. The absolute quantification of elements and untargeted relative metabolomic profiles are determined by inductively coupled plasma mass spectrometry and gas chromatography coupled to mass spectrometry, respectively. Associations of HM SARS‐CoV‐2 antibodies with elemental and metabolomic profiles are studied. COVID‐19 has a significant impact on HM composition. COVID‐19 reduces the concentrations of Fe, Cu, Se, Ni, V, and Aluminium (Al) and increases Zn compared to prepandemic control samples. A total of 18 individual metabolites including amino acids, peptides, fatty acids and conjugates, purines and derivatives, alcohols, and polyols are significantly different in HM from SARS‐CoV‐2 positive mothers. Aminoacyl‐tRNA biosynthesis, phenylalanine, tyrosine and tryptophan biosynthesis, phenylalanine, and linoleic acid pathways are significantly altered. Differences are obtained depending on COVID‐19 symptomatic and asymptomatic status.

Conclusions

This study provides unique insights about the impact of maternal SARS‐CoV‐2 infection on the elemental and metabolomic profiles of HM that warrants further research due the potential implications for infant health.

Thyroid Dysfunction and COVID-19: The Emerging Role of Selenium in This Intermingled Relationship

COVID-19 represents a worldwide public health emergency, and, beyond the respiratory symptoms characterizing the classic viral disease, growing evidence has highlighted a possible reciprocal relationship between SARS-CoV-2 infection and thyroid dysfunction. The updated data discussed in this review suggests a role of SARS-CoV-2 infection on the thyroid gland, with multiple thyroid pictures described. Conversely, no conclusion can be drawn on the association between pre-existing thyroid disease and increased risk of SARS-CoV-2 infection. In this scenario, selenium (Se), an essential trace element critical for thyroid function and known as an effective agent against viral infections, is emerging as a potential novel therapeutic option for the treatment of COVID-19. Large multicentre cohort studies are required to elucidate the mechanisms underlying thyroid dysfunction during or following recovery from COVID-19, including Se status. Meanwhile, clinical trials should be performed to evaluate whether adequate intake of Se can help address COVID-19 in Se-deficient patients, also avoiding thyroid complications that can contribute to worsening outcomes during infection.

A Review of Different Vaccines and Strategies to Combat COVID-19

In December 2019, an unknown viral infection emerged and quickly spread worldwide, resulting in a global pandemic. This novel virus caused severe pneumonia and acute respiratory distress syndrome caused by Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2). It has caused 6.25 millions of deaths worldwide and remains a major concern for health, society, and the economy. As vaccination is one of the most efficient ways to combat this pandemic, different vaccines were developed in a short period. This review article discusses how coronavirus affected the top nations of the world and the vaccines being used for the prevention. Amongst the vaccines, some vaccines have already been approved, and some have been involved in clinical studies. The article also provides insight into different COVID-19 vaccine platforms, their preparation, working, efficacy, and side effects.

Decreased Serum Selenium Levels of COVID-19 Patients in Comparison with Healthy Individuals

BACKGROUND

Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2) is the cause of the COVID-19 pandemic and is the cause of increased mortality, especially among elderly patients and those who have severe complications, such as chronic pulmonary obstruction, hypertension, diabetes, and cancer. Nutrition, especially micronutrients, plays an important role in reducing mortality and complications from COVID-19 because micronutrients strengthen our immune system and nutritional status is an important factor that affects the outcome of patients with COVID-19. Among micronutrients, selenium has an important effect on both intrinsic and acquired immunity. Host selenium deficiency affects the viral genome and increases the virulence of viruses. We have investigated the serum selenium levels in COVID-19 patients and healthy control individuals.

METHODS

A total of 50 patients with COVID-19 infection were included in this study. During hospitalization, 13 patients died (non-survivor group) and 37 patients recovered (survivor group). We assessed the serum selenium levels in 50 COVID-19 patients and 50 healthy individuals by Agilent SpectrAA-240 Z atomic absorption spectrometer.

RESULTS

The serum selenium level was significantly lower in COVID-19 patients (77. 8 ± 13.9 μg/L) as compared to healthy control individuals (91.7 ± 16.7 μg/L), but there was no significant difference between the survivor and non-survivor groups. Also, there was no significant relationship between serum selenium levels and laboratory findings of COVID-19 patients.

CONCLUSIONS

These results suggest that decreased serum selenium levels may be a risk factor for the COVID-19 infection, but there was no significant relationship between selenium and severity and mortality of COVID-19 disease.

Ingestion, Immunity, and Infection: Nutrition and Viral Respiratory Tract Infections

Respiratory infections place a heavy burden on the health care system, particularly in the winter months. Individuals with a vulnerable immune system, such as very young children and the elderly, and those with an immune deficiency, are at increased risk of contracting a respiratory infection. Most respiratory infections are relatively mild and affect the upper respiratory tract only, but other infections can be more serious. These can lead to pneumonia and be life-threatening in vulnerable groups. Rather than focus entirely on treating the symptoms of infectious disease, optimizing immune responsiveness to the pathogens causing these infections may help steer towards a more favorable outcome. Nutrition may have a role in such prevention through different immune supporting mechanisms. Nutrition contributes to the normal functioning of the immune system, with various nutrients acting as energy sources and building blocks during the immune response. Many micronutrients (vitamins and minerals) act as regulators of molecular responses of immune cells to infection. It is well described that chronic undernutrition as well as specific micronutrient deficiencies impair many aspects of the immune response and make individuals more susceptible to infectious diseases, especially in the respiratory and gastrointestinal tracts. In addition, other dietary components such as proteins, pre-, pro- and synbiotics, and also animal- and plant-derived bioactive components can further support the immune system. Both the innate and adaptive defense systems contribute to active antiviral respiratory tract immunity. The initial response to viral airway infections is through recognition by the innate immune system of viral components leading to activation of adaptive immune cells in the form of cytotoxic T cells, the production of neutralizing antibodies and the induction of memory T and B cell responses. The aim of this review is to describe the effects of a range different dietary components on anti-infective innate as well as adaptive immune responses and to propose mechanisms by which they may interact with the immune system in the respiratory tract.

Immunomodulatory and Anti-Inflammatory Properties of Selenium-Containing Agents: Their Role in the Regulation of Defense Mechanisms against COVID-19

The review presents the latest data on the role of selenium-containing agents in the regulation of diseases of the immune system. We mainly considered the contributions of selenium-containing compounds such as sodium selenite, methylseleninic acid, selenomethionine, and methylselenocysteine, as well as selenoproteins and selenium nanoparticles in the regulation of defense mechanisms against various viral infections, including coronavirus infection (COVID-19). A complete description of the available data for each of the above selenium compounds and the mechanisms underlying the regulation of immune processes with the active participation of these selenium agents, as well as their therapeutic and pharmacological potential, is presented. The main purpose of this review is to systematize the available information, supplemented by data obtained in our laboratory, on the important role of selenium compounds in all of these processes. In addition, the presented information makes it possible to understand the key differences in the mechanisms of action of these compounds, depending on their chemical and physical properties, which is important for obtaining a holistic picture and prospects for creating drugs based on them.

Potential Role of Selenium in the Treatment of Cancer and Viral Infections

Selenium has been extensively evaluated clinically as a chemopreventive agent with variable results depending on the type and dose of selenium used. Selenium species are now being therapeutically evaluated as modulators of drug responses rather than as directly cytotoxic agents. In addition, recent data suggest an association between selenium base-line levels in blood and survival of patients with COVID-19. The major focus of this mini review was to summarize: the pathways of selenium metabolism; the results of selenium-based chemopreventive clinical trials; the potential for using selenium metabolites as therapeutic modulators of drug responses in cancer (clear-cell renal-cell carcinoma (ccRCC) in particular); and selenium usage alone or in combination with vaccines in the treatment of patients with COVID-19. Critical therapeutic targets and the potential role of different selenium species, doses, and schedules were discussed.

Selenium, selenoprotein P, and oxidative stress levels in SARS-CoV-2 patients during illness and recovery

Background

This study aimed to assess tendency of oxidative stress in COVID-19 patients depending on severity.

Methods

The study was conducted with 80 post-COVID-19 disease patients and 40 acutely ill patients. Content of selenium in blood plasma was detected by a fluorimetric method with di-amino-naphthalene using acidic hydrolysis. Selenoprotein P, malondialdehyde and 4-hydroxynonenal and their metabolite adducts were evaluated by spectrophotometric methods using commercial assay kits.

Results

Obtained results showed that selenium content in blood for post-COVID-19 disease patients was of a similar lower norm for Latvian inhabitants. Selenium and seleno-protein P contents for acute patients were significantly decreased compared with post-COVID-19 disease patients.

Conclusion

In conclusion, COVID-19 involves induction of antioxidant systems—in case of severe disease, patients have significantly low concentration of selenium, seleno-protein P and higher level of oxidative stress, which, in turn, confirms the more intense formation of free radicals in the body.

Foods to deliver immune-supporting nutrients

PURPOSE OF REVIEW

This article will briefly describe the role of specific dietary components, mainly micronutrients, in supporting the immune response and summarise the literature regarding foods and dietary patterns in the context of immunity and infectious illness. Literature on SARS-COV-2 infection and COVID-19 is referred to where appropriate.

RECENT FINDINGS

Micronutrients, other nutrients and plant bioactives have roles in supporting the immune response. Low status of a number of micronutrients is associated with increased risk and severity of COVID-19. Recent studies report associations of plant-based diets with lower risk of, and less severe, COVID-19.

SUMMARY

In order to support the immune response, sufficient amounts of a range of essential and non-essential nutrients and other bioactives, mainly from a plant-based diet should be consumed. Further research should define cause-and-effect relationships of intakes of individual dietary components and foods, and of dietary patterns with susceptibility to, and severity of, viral infections.

The Role of Selenium in Pathologies: An Updated Review

Selenium is an essential microelement required for a number of biological functions. Selenium—and more specifically the amino acid selenocysteine—is present in at least 25 human selenoproteins involved in a wide variety of essential biological functions, ranging from the regulation of reactive oxygen species (ROS) concentration to the biosynthesis of hormones. These processes also play a central role in preventing and modulating the clinical outcome of several diseases, including cancer, diabetes, Alzheimer’s disease, mental disorders, cardiovascular disorders, fertility impairments, inflammation, and infections (including SARS-CoV-2). Over the past years, a number of studies focusing on the relationship between selenium and such pathologies have been reported. Generally, an adequate selenium nutritional state—and in some cases selenium supplementation—have been related to improved prognostic outcome and reduced risk of developing several diseases. On the other hand, supra-nutritional levels might have adverse effects. The results of recent studies focusing on these topics are summarized and discussed in this review, with particular emphasis on advances achieved in the last decade.

Potential metal-related strategies for prevention and treatment of COVID-19

Abstract

The coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has posed severe threats to human health, public safety, and the global economy. Metal nutrient elements can directly or indirectly take part in human immune responses, and metal-related drugs have served as antiviral drugs and/or enzyme inhibitors for many years, providing potential solutions to the prevention and treatment of COVID-19. Metal-based drugs are currently under a variety of chemical structures and exhibit wide-range bioactivities, demonstrating irreplaceable advantages in pharmacology. This review is an intention to summarize recent progress in the prevention and treatment strategies against COVID-19 from the perspective of metal pharmacology. The current and potential utilization of metal-based drugs is briefly introduced. Specifically, metallohydrogels that have been shown to present superior antiviral activities are stressed in the paper as potential drugs for the treatment of COVID-19.

Graphic abstract

Inhibition of selenoprotein synthesis by Zika virus may contribute to congenital Zika syndrome and microcephaly by mimicking SELENOP knockout and the genetic disease PCCA

Selenium status plays a major role in health impacts of various RNA viruses. We previously reported potential antisense interactions between viral mRNAs and host mRNAs encoding isoforms of the antioxidant selenoprotein thioredoxin reductase (TXNRD). Here, we examine possible targeting of selenoprotein mRNAs by Zika virus (ZIKV), because one of the most devastating outcomes of ZIKV infection in neonates, microcephaly, is a key manifestation of Progressive Cerebello-Cerebral Atrophy (PCCA), a genetic disease of impaired selenoprotein synthesis. Potential antisense matches between ZIKV and human selenoprotein mRNAs were identified computationally, the strongest being against human TXNRD1 and selenoprotein P (SELENOP), a selenium carrier protein essential for delivery of selenium to the brain. Computationally, ZIKV has regions of extensive (~30bp) and stable (ΔE < -50kcal/mol) antisense interactions with both TXNRD1 and SELENOP mRNAs. The core ZIKV/SELENOP hybridization was experimentally confirmed at the DNA level by gel shift assay using synthetic oligonucleotides. In HEK293T cells, using Western blot probes for SELENOP and TXNRD1, ZIKV infection knocked down SELENOP protein expression almost completely, by 99% (p<0.005), and TXNRD1 by ~90% (p<0.05). In contrast, by RT-qPCR, there was no evidence of significant changes in SELENOP and TXNRD1 mRNA levels after ZIKV infection, suggesting that their knockdown at the protein level is not primarily a result of mRNA degradation. These results suggest that knockdown of SELENOP and TXNRD1 by ZIKV in fetal brain, possibly antisense-mediated, could mimic SELENOP knockout, thereby contributing to neuronal cell death and symptoms similar to the genetic disease PCCA, including brain atrophy and microcephaly.

Vanadium as potential therapeutic agent for COVID-19: A focus on its antiviral, antiinflamatory, and antihyperglycemic effects

An increasing evidence suggests that vanadium compounds are novel potential drugs in the treatment of diabetes, atherosclerosis, and cancer. Vanadium has also demonstrated activities against RNA viruses and is a promising candidate for treating acute respiratory diseases. The antidiabetic, antihypertensive, lipid-lowering, cardioprotective, antineoplastic, antiviral, and other potential effects of vanadium are summarized here. Given the beneficial antihyperglycemic and antiinflammatory effects as well as the potential mechanistic link between the COVID-19 and diabetes, vanadium compounds could be considered as a complement to the prescribed treatment of COVID-19. Thus, further clinical trials are warranted to confirm these favorable effects of vanadium treatment in COVID-19 patients, which appear not to be studied yet.

Selenium and protozoan parasitic infections: selenocompounds and selenoproteins potential

The current drug treatments against protozoan parasitic diseases including Chagas, malaria, leishmaniasis, and toxoplasmosis represent good examples of drug resistance mechanisms and have shown diverse side effects. Therefore, the identification of novel therapeutic strategies and drug compounds against such life-threatening diseases is urgent. According to the successful usage of selenium (Se) compounds-based therapy against some diseases, this therapeutic strategy has been recently further underlined against these parasitic diseases by targeting different parasite´s essential pathways. On the other hand, due to the important functions played by parasite selenoproteins in their biology (such as modulating the host immune response), they can be also considered as a novel therapeutic strategy by designing specific inhibitors against these important proteins. In addition, the immunomodulatory potentiality of these compounds to trigger T helper type 1 (Th1) cells and cytokine-mediated immune response for the substantial induction of proinflammatory cytokines, thus, Se, selenoproteins, and parasite selenoproteins could be further investigated to find possible vaccine antigens. Herein, we collect and present the results of some studies regarding Se-based therapy against protozoan parasitic diseases and highlight relevant information and some viewpoints that might be insightful to advance toward more effective studies in the future.