Glutathione peroxidase and viral replication: implications for viral evolution and chemoprevention

Optimization of Se- and Zn-Enriched Mycelium of Lentinula edodes (Berk.) Pegler as a Dietary Supplement with Immunostimulatory Activity

Mycelial cultures of Lentinula edodes, an edible and medicinal mushroom, have been used in our previous research to obtain selenium-containing immunomodulatory preparations. Our current attempts to obtain a new preparation containing both selenium and zinc, two micronutrients necessary for the functioning of the immune system, extended our interest in the simultaneous accumulation of these elements by mycelia growing in media enriched with selenite and zinc(II) ions. Subsequently, we have studied the effects of new L. edodes mycelium water extracts with different concentrations of selenium and zinc on the activation of T cell fraction in human peripheral blood mononuclear cells (PBMCs). Flow cytometry analysis was used to measure the expression of activation markers on human CD4+ and CD8+ T cells stimulated by anti-CD3 and anti-CD3/CD28 antibodies (Abs). It was demonstrated that statistically significant changes were observed for PD-1 and CD25 antigens on CD8+ T cells. The selenium and zinc content in the examined preparations modified the immunomodulatory activity of mycelial polysaccharides; however, the mechanisms of action of various active ingredients in the mycelial extracts seem to be different.

Molecular insights on bioactive compounds againstCovid-19: A Network pharmacological and computational study

BACKGROUND

Network pharmacology based identification of phytochemicals in the form of cocktails against off-targets can play a significant role in inhibition of SARS_CoV2 viral entry and its propagation. This study includes network pharmacology, virtual screening, docking and molecular dynamics to investigate the distinct antiviral mechanisms of effective phytochemicals against SARS_CoV2.

METHODS

SARS_CoV2 human-protein interaction network was explored from the BioGRID database and analysed using Cytoscape. Further analysis was performed to explore biological function, protein-phytochemical/drugs network and up-down regulation of pathological host target proteins. This lead to understand the antiviral mechanism of phytochemicals against SARS_CoV2. The network was explored through g:Profiler, EnrichR, CTD, SwissTarget, STITCH, DrugBank, BindingDB, STRING and SuperPred. Virtual screening of phytochemicals against potential antiviral targets such as M-Pro, NSP1, Receptor binding domain, RNA binding domain, and ACE2 discloses the effective interaction between them. Further, the binding energy calculations through simulation of the docked complex explains the efficiency and stability of the interactions.

RESULTS

The network analysis identified quercetin, genistein, luteolin, eugenol, berberine, isorhamnetin and cinnamaldehyde to be interacting with host proteins ACE2, DPP4, COMT, TUBGCP3, CENPF, BRD2 and HMOX1 which are involved in antiviral mechanisms such as viral entry, viral replication, host immune response, and antioxidant activity. Thus indicating that herbal cocktails can effectively tackle the viral hijacking of the crucial biological functions of human host. Further exploration through Virtual screening, docking and molecular dynamics recognizes the effective interaction of phytochemicals such as punicalagin, scutellarin, and solamargine with their respective potential targets.

CONCLUSION

This work illustrates probable strategy for identification of phytochemical based cocktails and off-targets which are effective against SARS_CoV 2.

Human glutathione peroxidase codon 198 variant increases nasopharyngeal carcinoma risk and progression

PURPOSE

Glutathione peroxidase 1 (GPx-1) is a selenium-dependent detoxifying enzyme involved in the protection of cells against oxidative damage. Some genetic association studies reported significant associations between GPx-1 Pro198Leu variant and carcinogenesis across different populations; however, the impact of this variant on nasopharyngeal carcinoma (NPC) has not been explored. Therefore, the present study was planned to evaluate the potential involvement of the GPx-1 Pro198Leu variant and plasma GPx activity in the risk of developing NPC in a Tunisian population.

METHODS

The GPx-1 Pro198Leu genotype was determined in 327 NPC patients and 150 healthy controls by the RFLP-PCR analysis. The correlation between the GPx-1 variant and the clinicopathological parameters was examined. GPx activity was assessed in the plasma of 119 NPC patients and 58 healthy control subjects and according to GPx-1 genotypes and clinicopathological characteristics of NPC patients.

RESULTS

A significant association was found between GPx-1 Pro198Leu variant and NPC risk in a Tunisian population. The allelic frequencies of Pro and Leu alleles were 32% versus 68% and 41% versus 59% in NPC cases and controls, respectively. Thus, the minor 198 Leu allele increased significantly in NPC patients and appeared as a potential risk factor for NPC occurrence (OR = 1.48, CI 95% = 1.14-1.91, p = 0.002). The plasma GPx activity was significantly higher in NPC patients than in controls (p = 0.03). According to the clinicopathological characteristics of NPC patients, GPx activity decreased significantly in patients with lymph node metastasis (p = 0.004).

CONCLUSION

This is the first study showing a strong association between GPx-1 Pro198Leu genetic variant and NPC risk. GPx-1 Pro198Leu variant increased the development of regional lymph node metastasis. Plasma GPx activity was higher in NPC patients. Thus, GPx-1 gene could be considered as a determinant factor influencing NPC risk and progression.

Food policy, nutrition and nutraceuticals in the prevention and management of COVID-19: Advice for healthcare professionals

BACKGROUND

The 2019 novel coronavirus (2019-nCoV) represents an ongoing major global health crisis with a potentially unprecedented death toll and socio-economic impact in the modern era. Measures taken to reduce the rate of transmission are too unprecedented, but are deemed necessary. The extensive strain on public health services has meant that individual agency is increasingly called for. To support this, there is a need to review policy and procedure governing the food and commerce industries in particular. Additionally, it is necessary to convey a more comprehensive and nuanced understanding of relevant diet and lifestyle factors to both healthcare practitioners and the general public.

SCOPE AND APPROACH

To our knowledge, a review of possible additional measures for healthcare proffesionals, which includes the possible nutritional management COVID-19 pandemic does not yet exist.Key Findings and Conclusions: This review identifies i) changing trends in consumer awareness and purchasing patterns in response to COVID-19, and their potential future implications for the food and food-commerce industry ii) problematic elements of policy relevant to the outbreak of COVID-19, including the handling of wild-life and food-commerce, ii) newly emergent technologies in food science which represent viable and cost-effective means to reduce the risk of transmission of coronavirus, such as anti-microbial packaging, iii) important nutritional considerations with regard to coronavirus disease prevention and management, including nutrition in early infancy, and the role of select micronutrients (vitamins and minerals), phytochemicals and probiotics in conferring protection against both viral infection and pathogenicity.

Connected Community and Household Food-Based Strategy (CCH-FBS): its importance for health, food safety, sustainability and security in diverse localities

In this article, I argue that Connected Community and Household Food-Based Strategy (CCH-FBS) could contribute to the resolution of outstanding nutritionally-related health problems. The 1995 Food-Based Dietary Guidelines (FBDGs) have been customized in regions and nations, encouraging integrated food systems and culturally-sensitive food-health relationships with economic development. Climate change and diminishing fuel and food affordability have made their role in promoting food security critical. Localities with their eco-systems, communities and households, could apply FBDGs to correct mismatches between food systems, individual health needs, and environmental integrity. Improved infrastructure should allow communities and households to be usefully connected and operate with CCH-FBSs.

Role of selenium in HIV infection

HIV infection is a global disease that disproportionately burdens populations with nutritional vulnerabilities. Laboratory experiments have shown that selenium has an inhibitory effect on HIV in vitro through antioxidant effects of glutathione peroxidase and other selenoproteins. Numerous studies have reported low selenium status in HIV-infected individuals, and serum selenium concentration declines with disease progression. Some cohort studies have shown an association between selenium deficiency and progression to AIDS or mortality. In several randomized controlled trials, selenium supplementation has reduced hospitalizations and diarrheal morbidity, and improved CD4(+) cell counts, but the evidence remains mixed. Additional trials are recommended to study the effect of selenium supplementation on opportunistic infections, and other HIV disease-related comorbidities in the context of highly active antiretroviral therapy in both developing and developed countries.

Molecular consequences of genetic variations in the glutathione peroxidase 1 selenoenzyme

Accumulating data have implicated the selenium-containing cytosolic glutathione peroxidase, GPx-1, as a determinant of cancer risk and a mediator of the chemopreventive properties of selenium. Genetic variants of GPx-1 have been shown to be associated with cancer risk for several types of malignancies. To investigate the relationship between GPx-1 enzyme activity and genotype, we measured GPx-1 enzyme activity and protein levels in human lymphocytes as a function of the presence of two common variations: a leucine/proline polymorphism at codon 198 and a variable number of alanine-repeat codons. Differences in GPx activity among these cell lines, as well as in the response to the low-level supplementation of the media with selenium, indicated that factors other than just genotype are significant in determining activity. To restrict the study to genotypic effects, human MCF-7 cells were engineered to exclusively express allelic variants representing a combination of either a codon 198 leucine or proline and either 5 or 7 alanine-repeat codons following transfection of GPx-1 expression constructs. Transfectants were selected and analyzed for GPx-1 enzyme activity and protein levels. GPx-1 with 5 alanines and a leucine at codon 198 showed a significantly higher induction when cells were incubated with selenium and showed a distinct pattern of thermal denaturation as compared with GPx-1 encoded by the other examined alleles. The collective data obtained using both lymphocytes and MCF-7 indicate that both intrinsic and extrinsic factors cooperate to ultimately determine the levels of this enzyme available to protect cells against DNA damage and mutagenesis.

Effects of an oral superoxide dismutase enzyme supplementation on indices of oxidative stress, proviral load, and CD4:CD8 ratios in asymptomatic FIV-infected cats

This study was designed to test the effect of antioxidant supplementation on feline immunodeficiency virus (FIV)-infected felines. Six acutely FIV-infected cats (> or =16 weeks post-inoculation) were given a propriety oral superoxide dismutase (SOD) supplement (Oxstrin; Nutramax Laboratories) for 30 days. Following supplementation, the erythrocyte SOD enzyme concentration was significantly greater in the supplemented FIV-infected group than the uninfected control group or the unsupplemented FIV-infected group. The CD4+ to CD8+ ratio increased significantly (0.66-0.88) in the SOD supplemented FIV-infected cats but not in the unsupplemented FIV-infected cats. Proviral load and reduced glutathione (GSH) levels in leukocyte cell types did not change significantly following supplementation. Antioxidant supplementation resulted in an increase in SOD levels, confirming the oral bioavailability of the compound in FIV-infected cats. This result warrants further investigation with trials of antioxidant therapy in FIV-infected cats that are showing clinical manifestations of their disease, as well as in other feline patients where oxidative stress likely contributes to disease pathogenesis, such as diabetes mellitus and chronic renal failure.

Relationship between plasma selenium concentrations and lower genital tract levels of HIV-1 RNA and interleukin type 1beta

OBJECTIVE

To examine the relationship between selenium nutritional status and intermediates of human immunodeficiency virus (HIV)-1 transmission.

DESIGN

Prospective cohort study.

SETTING

A study clinic at Muhimbili National Hospital, Dar es Salaam, Tanzania.

SUBJECTS

A total of 340 HIV-1-infected pregnant women with gestational ages 12-27 weeks.

METHODS

Women's plasma selenium concentrations were determined at enrollment and modeled as tertiles (tertile 1: <114 microg/l (reference); tertile 2: 114-131 microg/l; tertile 3: >131 microg/l). Cervicovaginal lavage specimens were obtained at 36 weeks of gestation to determine HIV-1 RNA and interleukin-1beta (IL-1beta) levels. In subgroup analyses, 123 women with genital tract infections at enrollment were excluded.

RESULTS

Plasma selenium concentrations >or=114 microg/l were related to increased risk of lower-genital shedding of HIV-1 RNA. Excluding women with genital tract infections strengthened the associations (relative risk (RR) tertile 2: 1.46, 95% confidence interval (CI)=1.10, 1.92; RR tertile 3: 1.39, 95% CI=1.05, 1.84). There was evidence for an association between plasma selenium concentrations >or=114 microg/l and increased HIV-1 RNA levels among the entire cohort and after excluding women with genital tract infections. There was no association between plasma selenium and IL-1beta concentrations.

CONCLUSIONS

High selenium status may lead to increased risk of genital HIV-1 shedding, but data from other studies indicate that the evidence is mixed. Results from ongoing selenium trials are awaited to clarify the impact of selenium on HIV-1-related transmission endpoints.

SPONSORSHIP

National Institute of Child Health and Human Development (NICHD R01 32257) and the Fogarty International Center (NIH D43 TW00004).

Selenoproteins and their impact on human health through diverse physiological pathways

In the last few decades, the importance of selenium in human health has been the subject of numerous studies. It is believed that the physiological effects of selenium occur mainly through the function of selenoproteins, which incorporate selenium in the form of one or more selenocysteine residues. Recent advances in understanding the complex regulation of selenoprotein synthesis and functional characterization of several members of the selenoprotein family have contributed to an improved comprehension of the role(s) of selenium in human health and the great diversity of physiological pathways influenced by this trace element.

HIV-1-induced pulmonary oxidative and nitrosative stress: exacerbated response to endotoxin administration in HIV-1 transgenic mouse model

Human immunodeficiency virus (HIV)-1 causes lung disease by increasing the host's susceptibility to pathogens. HIV-1 also causes an increase in systemic oxidative/nitrosative stress, perhaps enhancing the deleterious effects of secondary infections. Here we examined the ability of HIV-1 proteins to increase lung oxidative/nitrosative stress after lipopolysaccharide (LPS) (endotoxin) administration in an HIV-1 transgenic mouse model. Lung oxidative/nitrosative stress biomarkers studied 3 and 6 h after LPS administration were as follows: lung edema, tissue superoxide, NO metabolites, nitrotyrosine, hydrogen peroxide, and bronchoalveolar lavage fluid (BALF) glutathione (GSH). Blood serum cytokine levels were quantified to verify immune function of our nonimmunocompromised animal model. Results indicate that 3 h after LPS administration, HIV-1 transgenic mouse lung tissue has significantly greater edema and superoxide. Furthermore, NO metabolites are significantly elevated in HIV-1 transgenic mouse BALF, lung tissue, and blood plasma compared with those of wild-type mice. HIV-1 transgenic mice also produce significantly greater lung nitrotyrosine and hydrogen peroxide than wild-type mice. In addition, HIV-1 transgenic mice produce significantly less BALF GSH than wild-type mice 3 h after LPS treatment. Without treatment, serum cytokine levels are similar for HIV-1 transgenic and wild-type mice. After treatment, serum cytokine levels are significantly elevated in both HIV-1 transgenic and wild-type mice. Therefore, HIV-1 transgenic mice have significantly greater lung oxidative/nitrosative stress after endotoxin administration than wild-type mice, independent of immune function. These results indicate that HIV-1 proteins may increase pulmonary complications subsequent to a secondary infection by altering the lung redox potential.

Functional studies of an HIV-1 encoded glutathione peroxidase

In an alternate reading frame overlapping the viral envelope gene, HIV-1 has been shown to encoded a truncated glutathione peroxidase (GPx) module. Essential active site residues of the catalytic core regions of mammalian GPx sequences are conserved in the putative viral GPx (vGPx, encoded by the env-fs gene). Cells transfected with an HIV-1 env-fs construct show up to a 100% increase in GPx enzyme activity, and are protected against the loss of mitochondrial transmembrane potential and subsequent cell death induced by exogenous oxidants or mitochondrial reactive oxygen species. An intact vGPx gene was observed to be more common in HIV-1-infected long-term non-progressors, as compared to HIV-1 isolates from patients developing AIDS. An antioxidant/antiapoptotic protective role of the vGPx is also consistent with the observation that -1 frameshifting induced by the HIV-1 env-fs sequence AAAAAGA (which contains a potential "hungry" arginine codon, AGA) increases during arginine deficiency, which has been associated with increased oxidative stress. Under arginine-limited conditions, nitric oxide synthase generates superoxide, which rapidly combines with NO to form peroxynitrite, which can cause activated T-cells to undergo apoptosis. Thus, biosynthesis of the HIV-1 GPx as an adaptive response to low arginine conditions might delay oxidant-induced apoptotic cell death, providing an enhanced opportunity for viral replication.

How HIV-1 causes AIDS: implications for prevention and treatment

HIV-1 encodes for one of the human glutathione peroxidases. As a consequence, as it is replicated, its genetic needs cause it to deprive HIV-1 seropositive individuals not only of glutathione peroxidase, but also of the four basic components of this selenoenzyme, namely selenium, cysteine, glutamine, and tryptophan. Eventually this depletion process causes severe deficiencies of all these substances. These, in turn, are responsible for the major symptoms of AIDS which include immune system collapse, greater susceptibility to cancer and myocardial infarction, muscle wasting, depression, diarrhea, psychosis and dementia. As the immune system fails, associated pathogenic cofactors become responsible for a variety of their own unique symptoms. Any treatment for HIV/AIDS must, therefore, include normalization of body levels of glutathione, glutathione peroxidase, selenium, cysteine, glutamine, and tryptophan. Although various clinical trials have improved the health of AIDS patients by correcting one or more of these nutritional deficiencies, they have not, until the present, been addressed together. Physicians involved in a selenium and amino-acid field trial in Botswana, however, are reporting that this nutritional protocol reverses AIDS in 99% of patients receiving it, usually within three weeks.

Selenium status is associated with accelerated HIV disease progression among HIV-1-infected pregnant women in Tanzania

Selenium deficiency has been implicated in accelerated disease progression and poorer survival among populations infected with HIV in developed countries, yet these associations remain unexamined in developing countries. Among 949 HIV-1-infected Tanzanian women who were pregnant, we prospectively examined the association between plasma selenium levels and survival and CD4 counts over time. Over the 5.7-y median follow-up time, 306 of 949 women died. In a Cox multivariate model, lower plasma selenium levels were significantly associated with an increased risk of mortality (P-value, test for trend = 0.01). Each 0.1 micromol/L increase in plasma selenium levels was related to a 5% (95% CI = 0%-9%) decreased risk of mortality. Plasma selenium levels were not associated with time to progression to CD4 cell count < 200 cells/mm(3) but were weakly and positively related to CD4 cell count in the first years of follow up. Selenium status may be important for clinical outcomes related to HIV disease in sub-Saharan Africa.

Selenium and its relationship to cancer: an update

Selenomethionine (Semet) is the major seleno-compound in cereal grains and enriched yeast whereas Se-methylselenocysteine (SeMCYS) is the major seleno-compound in Se-accumulator plants and some plants of economic importance such as garlic and broccoli exposed to excess Se. Animals can metabolize both Semet and SeMCYS. Epidemiological studies have indicated an inverse relationship between Se intake and the incidence of certain cancers. Blood or plasma levels of Se are usually lower in patients with cancer than those without this disorder, but inconsistent results have been found with toenail-Se values and the incidence of cancer. There have been eight trials with human subjects conducted on the influence of Se on cancer incidence or biomarkers, and except for one, all have shown a positive benefit of Se on cancer reduction or biomarkers of this disorder. This is consistent with about 100 small-animal studies where Se has been shown to reduce the incidence of tumours in most of these trials. Se-enriched yeast is the major form of Se used in trials with human subjects. In the mammary-tumour model, SeMCYS has been shown to be the most effective seleno-compound identified so far in reduction of tumours. Several mechanisms have been proposed on the mechanism whereby Se reduces tumours. Even though SeMCYS was shown to be the most effective seleno-compound in the reduction of mammary tumours, it may not be the most effective seleno-compound for reduction of colon tumours.

Effect of prenatal vitamin supplementation on lower-genital levels of HIV type 1 and interleukin type 1 beta at 36 weeks of gestation

Micronutrient status has been associated with shedding of human immunodeficiency virus type 1 (HIV-1) in the lower-genital tract in observational studies. We examined the effect of vitamin supplements on genital HIV-1 shedding and interleukin-1 beta (IL-1 beta ), a cytokine marker of vaginal inflammation and promotion of HIV-1 infection. Consenting HIV-1-infected pregnant women were randomized to receive daily supplementation with vitamin A and/or multivitamins B-complex, C, and E with use of a factorial design. Cervicovaginal lavage (CVL) specimens were obtained shortly before delivery. Significantly more women who received vitamin A had detectable levels of HIV-1 in CVL (74.8%), compared with those who did not receive vitamin A (65.1%) (P=.04, by multivariate analysis). Multivitamin B-complex, C, and E had no effect on the risk of viral shedding. Our results raise concern about the use of vitamin A supplements by HIV-1-infected women. Use of prenatal multivitamin supplements (including vitamins B-complex, C, and E) should be continued despite the lack of effect on HIV-1 transmission because of previously reported positive effects on maternal health and pregnancy outcomes.

Trends in selenium biochemistry

The biochemistry of selenium-containing natural products, including selenoproteins, is reviewed up to May 2002. Particular emphasis is placed on the assimilation of selenium from inorganic and organic selenium sources for selenoprotein synthesis, the catalytic role of selenium in enzymes, and medical implications of an unbalanced selenium supply. The review contains 393 references on key discoveries and recent progress.

Intracellular trafficking of micronutrients: from gene regulation to nutrient requirements

The intracellular distribution of micronutrients, as well as their uptake, is important for cell function. In some cases the distribution of micronutrients or their related proteins is determined by gene expression mechanisms. The 3' untranslated region (3'UTR) of metallothionein-1 mRNA determines localisation of the mRNA, and in turn intracellular trafficking of the protein product. Using transfected cells we have evidence for the trafficking of metallothionein-1 into the nucleus and for its involvement in protection from oxidative stress and DNA damage. When nutritional supply of Se is limited, selenoprotein expression is altered, but not all selenoproteins are affected equally; the available Se is prioritised for synthesis of particular selenoproteins. The prioritisation involves differences in mRNA translation and stability due to 3'UTR sequences. Potentially, genetic variation in these regulatory mechanisms may affect nutrient requirements. Genetic polymorphisms in the 3'UTR from two selenoprotein genes have been observed; one polymorphism affects selenoprotein synthesis. These examples illustrate how molecular approaches can contribute at several levels to an increased understanding of nutrient metabolism and requirements. First, they provide the tools to investigate regulatory features in genes and their products. Second, understanding these processes can provide model systems to investigate nutrient metabolism at the cellular level. Third, once key features have been identified, the availability of human genome sequence information and single nucleotide polymorphism databases present possibilities to define the extent of genetic variation in genes of nutritional relevance. Ultimately, the functionality of any variations can be defined and subgroups of the population with subtly different nutrient requirements identified.

Peroxiredoxins

Present knowledge on peroxiredoxins is reviewed with special emphasis on catalytic principles, specificities and biological function. Peroxiredoxins are low efficiency peroxidases using thiols as reductants. They appear to be fairly promiscuous with respect to the hydroperoxide substrate; the specificities for the donor substrate vary considerably between the subfamilies, comprising GSH, thioredoxin, tryparedoxin and the analogous CXXC motifs in bacterial AhpF proteins. Peroxiredoxins are definitely responsible for antioxidant defense in bacteria (AhpC), yeast (thioredoxin peroxidase) and trypanosomatids (tryparedoxin peroxidase). They are considered to determine virulence of mycobacteria and trypanosomatids. In higher plants they are involved in balancing hydroperoxide production during photosynthesis. In higher animals peroxiredoxins appear to be involved in the redox-regulation of cellular signaling and differentiation, displaying in part opposite effects.