Role of glutathione peroxidase 1 in glucose and lipid metabolism-related diseases

A comprehensive review on selenium and blood pressure: Recent advances and research perspectives

BACKGROUND

Globally, approximately 31.1 % of adults are affected by hypertension(HTN), and there is currently no effective treatment for this condition. Selenium (Se), an essential trace element in the human body, has been shown to play a role in various biological processes, including anti-inflammation, antioxidative stress, anti-ferroptosis, and regulation of immune response. Research suggests that Se may have potential hypotensive effects.

OBJECTIVE

This review aims to comprehensively investigate the relationship between Se and blood pressure(BP), elucidate the mechanisms through which Se influences BP, and explore its prospective applications in clinical practice.

METHODS

We conducted a systematic search on PubMed for a thorough review of articles concerning the relationship between Se and BP, as well as the mechanisms by which Se may lower BP.

RESULTS AND CONCLUSIONS

Although some findings indicate that Se might increase BP, its anti-inflammatory, anti-oxidant, anti-vascular remodeling, anti-atherosclerotic, anti-ferroptosis, and regulation of immune response effects suggest that maintaining an appropriate level of Se may contribute to BP reduction and possibly lower the risk of pregnancy-induced hypertension(PIH). While Se shows promise in the management of HTN, further exploration is necessary for its development. Future studies should clarify the mechanisms involved and identify relevant targets through clinical research, which may provide adjunctive therapies for HTN.

The Inhibitory Effects of NCT503 and Exogenous Serine on High-Selenium Induced Insulin Resistance in Mice

OBJECTIVE

This study aims to identify whether the development of insulin resistance (IR) induced by high selenium (Se) is related to serine deficiency via the inhibition of the de novo serine synthesis pathway (SSP) by the administrations of 3-phosphoglycerate dehydrogenase (PHGDH) inhibitor (NCT503) or exogenous serine in mice.

METHOD

forty-eight male C57BL/6J mice were randomly divided into four groups: adequate-Se (0.1 mgSe/kg), high-Se (0.8 mgSe/kg), high-Se +serine (240 mg/kg/day), and high-Se +NCT503 (30 mg/kg, twice a week) for 5 months. The glucose tolerance test (GTT) and insulin tolerance test (ITT) were used to confirm the development of IR in mice with high-Se intake, and fasting blood glucose levels were measured monthly. The Se contents in plasma and tissues were detected by ICP-MS. The levels of insulin (INS), homocysteine (HCY), and serine in plasma were tested by ELISA. Western blot analyses were conducted to evaluate the protein expressions of glutathione peroxidase 1 (GPX1), selenoprotein P (SELENOP) and PHGDH, the PI3K-AKT-mTOR pathway, folate cycle (SHMT1, MTHFR), and methionine cycle (MS).

RESULTS

An IR model was developed in mice from the high-Se group with elevated fasting blood glucose and INS levels, impaired glucose tolerance, and reduced insulin sensitivity, but not in both the high-Se +serine group and the high-Se +NCT503 group. Compared with the high-Se and high-Se +serine groups, the expressions of GPX1 and SELENOP significantly decreased for the high-Se +NCT503 group in the liver, muscle, and pancreas tissues. The expression of PHGDH of high-Se group was significantly higher than that of the adequate-Se group in the liver (p < 0.05) and pancreas (p < 0.001). Also, the expected high expression of PHGDH was effectively inhibited in mice from the high-Se +serine group but not from the high-Se +NCT503 group. The expression of p-AKT (Ser-473) for the high-Se group was significantly lower than that of the adequate-Se group in the liver, muscle, and pancreas.

CONCLUSIONS

The IR induced by high-Se intake in the body has been confirmed to be partially due to serine deficiency, which led to the initiation of SSP to produce endogenous serine. The supplementations of exogenous serine or inhibitors of PHGDH in this metabolic pathway could be used for the intervention.

Activation of the De Novo Serine Synthesis Pathway and Disruption of Insulin Signaling Induced by Supplemental SeMet in Vitro

Selenium (Se) intake or selenoprotein overexpression can cause abnormal glucose metabolism and increase the risk of type 2 diabetes (T2D). The purpose of this study is to observe whether glycolysis bypass in the de novo serine synthesis pathway (SSP) is activated under high-Se stress in vitro. Initially, HCT-116, L02, HepG2, and differentiated C2C12 cells were exposed to five selenomethionine (SeMet) concentrations (0.001 to 10 µmol/L) for 48 h. The expressions of glutathione peroxidase 1 (GPX1), selenoprotein P (SELENOP), 3-phosphoglycerate dehydrogenase (PHGDH), and serine hydroxy-methyltransferases 1 (SHMT1) were assessed by western blotting (WB). Then, corresponding to the peak expressions of GPX1, SELENOP, and PHGDH, 0.1 µmol/L SeMet was identified as the highest intervention concentration. With more detailed levels of SeMet (0.001 to 0.1 µmol/L) given, the differentiated C2C12 cells were treated for 48 h to analyze the expressions of selenoproteins, enzymes related with serine metabolism and insulin signaling pathway. Among the four cell lines, the expressions of selenoproteins and metabolic enzymes of serine in C2C12 cells were more sensitive to changes in Se concentrations, which was similar to that in L02 cells. In C2C12 cells, the expressions of GPX1, SELENOP, selenoprotein N (SELENON), PHGDH, and SHMT1 exhibited a parabolic inflection point at SeMet concentrations of 0.05 µmol/L or 0.075 µmol/L, while 5,10-methylenetetrahydrofolate reductase (MTHFR) and methionine synthase (MS) showed no such trend. After 15 min of insulin stimulation, glucose retained more in the culture medium due to the decreased uptake by C2C12 cells. The expressions of key enzymes (AKT, AKT (Ser-473), AKT (Thr-308), mTOR, and PI3K) in the PI3K-AKT-mTOR signaling pathway decreased with the increased level of SeMet. This study demonstrated that excessive Se intake could induce abnormal glucose metabolism via SSP and impair the normal signaling of insulin in the differentiated C2C12 cells.

Possible Metabolic Remodeling based on de novo Biosynthesis of L-serine in Se-Subtoxic or -Deficient Mammals

Current research studies point to an increased risk of diabetes with selenium (Se) intake beyond the physiological requirement used to prevent cancers. The existing hypothesis of "selenoprotein overexpression leads to intracellular redox imbalance" cannot clearly explain the U-shaped dose-effect relationship between Se intake and the risk of diabetes. In this review, it is speculated that metabolic remodeling based on the de novo biosynthesis of L-serine may occur in mammals at supranutritional or subtoxic levels of Se. It is also speculated that a large amount of L-serine is consumed by the body during insufficient Se intake, thus resulting in similar metabolic reprogramming. The increase in atypical ceramide and its derivatives due to the lack of L-serine may also play a role in the development of diabetes.

Neural Precursor Cell-Expressed Developmentally Downregulated Protein 4 (NEDD4)-Mediated Ubiquitination of Glutathione Peroxidase 4 (GPX4): A Key Pathway in High-Glucose-Induced Ferroptosis in Corpus Cavernosum Smooth Muscle Cells

Pharmacological treatment of diabetes mellitus-induced erectile dysfunction (DMED) has become increasingly challenging due to the limited efficacy of phosphodiesterase type 5 inhibitors (PDE5i). As the global prevalence of DM continues, there is a critical need for novel therapeutic strategies to address DMED. In our previous studies, we found that Glutathione peroxidase 4 (GPX4), a ferroptosis inhibitor, can ameliorate DMED in diabetic rats. However, the specific role of GPX4 in corpus cavernosum smooth muscle cells (CCSMCs) and its regulatory mechanisms remain unclear. In this study, we established primary cultures of CCSMCs and systematically analyzed the role of GPX4 under high-glucose conditions. To further elucidate the upstream regulatory pathways of GPX4, we employed immunoprecipitation coupled with mass spectrometry (IP-MS) to identify potential interacting proteins. Additionally, co-immunoprecipitation (Co-IP) and cycloheximide (CHX) chase assays were conducted to explore the regulatory dynamics and post-translational stability of GPX4. Under high-glucose conditions, the expression of GPX4 in CCSMCs is significantly downregulated, leading to an increase in intracellular oxidative stress and heightened levels of ferroptosis, accompanied by dysfunction in smooth muscle cell relaxation. Furthermore, the CHX chase assay revealed that high glucose accelerates GPX4 protein degradation via the ubiquitin-proteasome pathway. Subsequent IP-MS identified NEDD4, an E3 ubiquitin ligase, as a potential interacting partner of GPX4. Further validation demonstrated that NEDD4 modulates the ubiquitination process of GPX4, thereby influencing its stability and expression. In conclusion, we identified NEDD4 as a key regulator of GPX4 stability through ubiquitin-mediated proteasomal degradation. These findings suggest potential therapeutic strategies targeting the NEDD4-GPX4 axis to alleviate DMED pathology.

Increased Expression of PHGDH Under High-Selenium Stress In Vivo

The purpose of this study is to explore the glycolytic remodeling under high-selenium (Se) stress. Three groups of male C57BL/6J mice were fed on diets with different Se contents (0.03, 0.15, and 0.30 mg Se/kg). Glucose tolerance test (GTT) and insulin tolerance test (ITT) were measured at the third month. Mice were killed at the fourth month. Plasma, liver, and muscle tissues were fetched for biochemistry and Se analysis. The expressions of insulin signaling pathway (PI3K-AKT-mTOR), glutathione peroxidase 1 (GPX1), selenoprotein N (SELENON), 3-phosphoglycerate dehydrogenase (PHGDH), serine hydroxymethyltransferases 1 (SHMT1), 5,10-methylenetetrahydrofolate reductase (MTHFR), and methionine synthase (MS) were analyzed by western blotting (WB) in liver and muscle tissues. The results of GTT and ITT showed that glucose tolerance and insulin tolerance were both abnormal in the 0.03 mg Se/kg and 0.3 mg Se/kg groups. Se concentrations in plasma, liver, and muscle of 0.03 mg Se/kg group were significantly lower than that of 0.15 mg Se/kg and 0.30 mg Se/kg groups (p < 0.05 or p < 0.01). The expressions of P-Akt (Thr-308) in muscle (p < 0.05) and PI3K and mTOR in liver (p < 0.001) of 0.30 mg Se/kg group were downregulated. The expressions of GPX1 in liver and muscle (p < 0.05 and p < 0.001), SELENON in muscle (p < 0.05), PHGDH in liver and muscle (p < 0.05), and SHMT1 (p < 0.05), MTHFR (p < 0.001), and MS (p < 0.001) in muscle of 0.3 mg Se/kg group were upregulated. The de novo serine synthesis pathway (SSP) was found to be activated in liver and muscle tissues of mice with a high-Se diet for the first time.

Tracing links between micronutrients and type 2 diabetes risk: the singular role of selenium

Background

Type 2 diabetes (T2D) is a growing global health concern. While micronutrients are crucial for physiological functions and metabolic balance, their precise links to T2D are not fully understood.

Methods

We investigated the causal relationships between 15 key micronutrients and T2D risk using both univariate and multivariate Mendelian randomization (MR) methods. Our analysis leveraged data from a large prospective cohort genome-wide association study (GWAS) on these micronutrients and T2D. We employed MR techniques such as inverse variance weighting (IVW), MR Egger, weighted median, and simple models. Multivariate analysis adjusted for diabetes-related factors like body mass index (BMI) and hypertension to assess the independent effects of micronutrients, particularly selenium, on T2D risk.

Results

Selenium intake was associated with an increased risk of T2D, with an odds ratio (OR) of 1.045, a 95% confidence interval (CI) ranging from 1.009 to 1.082, and a P-value of 0.015. This association was consistent in multivariate analyses, suggesting an independent effect of selenium on T2D risk after adjusting for confounders.

Conclusion

Our study presents novel evidence of a positive correlation between selenium intake and T2D risk, underscoring the importance of micronutrients in diabetes prevention and treatment strategies. Further research is necessary to confirm these findings and to clarify the specific biological mechanisms through which selenium influences diabetes risk.

Effects of grape seed proanthocyanidin extract on cholesterol metabolism and antioxidant status in finishing pigs

Grape seed proanthocyanidin extract (GSPE) is a natural polyphenolic compound, which plays an important role in anti-inflammatory and antioxidant. The present study aimed to investigate the effects of GSPE supplementation on the cholesterol metabolism and antioxidant status of finishing pigs. In longissimus dorse (LD) muscle, the data showed that GSPE significantly decreased the contents of total cholesterol (T-CHO) and triglyceride (TG), and decreased the mRNA expression of 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMG-CoAR) and Fatty acid synthase (FAS), while increased the mRNA expression of carnitine palmitoyl transferase-1b (CPT1b), peroxisome proliferator-activated receptors (PPARα) and peroxisome proliferator activated receptor-γ coactivator-1α (PGC-1α). GSPE also reduced the enzyme activities of HMG-CoAR and FAS, and meanwhile amplified the activity of CPT1b in LD muscle of finishing pigs. Furthermore, dietary GSPE supplementation increased the serum catalase (CAT) and total antioxidant capacity (T-AOC), serum and liver total superoxide dismutase (T-SOD) and glutathione peroxidase (GSH-Px) levels, while reduced serum and liver malondialdehyde (MDA) level in finishing pigs. In the liver, Superoxide Dismutase 1 (SOD1), catalase (CAT), glutathione peroxidase 1 (GPX1), Nuclear Factor erythroid 2-Related Factor 2 (NRF2) mRNA levels were increased by GSPE. In conclusion, this study showed that GSPE might be an effective dietary supplement for improving cholesterol metabolism and antioxidant status in finishing pigs.

Selenium, diabetes, and their intricate sex-specific relationship

Selenium (Se) is an essential trace element, which is inserted as selenocysteine (Sec) into selenoproteins during biosynthesis, orchestrating their expression and activity. Se is associated with both beneficial and detrimental health effects; deficient supply or uncontrolled supplementation raises concerns. In particular, Se was associated with an increased incidence of type 2 diabetes (T2D) in a secondary analysis of a randomized controlled trial (RCT). In this review, we discuss the intricate relationship between Se and diabetes and the limitations of the available clinical and experimental studies. Recent evidence points to sexual dimorphism and an association of Se deficiency with gestational diabetes mellitus (GDM). We highlight the emerging evidence linking high Se status with improved prognosis in patients with T2D and lower risk of macrovascular complications.

Is oxidative stress - antioxidants imbalance the physiopathogenic core in pediatric obesity?

Despite the early recognition of obesity as an epidemic with global implications, research on its pathogenesis and therapeutic approach is still on the rise. The literature of the 21st century records an excess weight found in up to 1/3 of children. Both the determining factors and its systemic effects are multiple and variable. Regarding its involvement in the potentiation of cardio-vascular, pulmonary, digestive, metabolic, neuro-psychic or even dermatological diseases, the information is already broadly outlined. The connection between the underlying disease and the associated comorbidities seems to be partially attributable to oxidative stress. In addition to these, and in the light of the recent COVID-19 pandemic, the role played by oxidative stress in the induction, maintenance and potentiation of chronic inflammation among overweight children and adolescents becomes a topic of interest again. Thus, this review's purpose is to update general data on obesity, with an emphasis on the physiopathological mechanisms that underlie it and involve oxidative stress. At the same time, we briefly present the latest principles of pathology diagnosis and management. Among these, we will mainly emphasize the impact played by endogenous and exogenous antioxidants in the evolutionary course of pediatric obesity. In order to achieve our objectives, we will refer to the most recent studies published in the specialized literature.

Biomimetic MicroRNAs-Selenium-Nanocomposites for Targeted and Combined Hyperlipidemia Therapy

Hyperlipidemia is considered as a high-risk factor for leading to coronary heart disease. MicroRNA-148a-3p (miR-148a-3p) inhibitor is a potential therapeutic target to bind low-density lipoprotein cholesterol receptors (LDLR) for decreasing the levels of low-density lipoprotein cholesterol in plasma. However, the therapeutic effects are not ideal in the clinical translation of nucleic acids treatment, owing to the short circulation time in vivo. Therefore, a platelet membrane (PM) cloaks Se nanoparticles (SeNPs) delivery system with chitosan (CS) modifies and miR-148a-3p inhibitors encapsulated is designed (PM/CS-SeNPs/miR). The PM/CS-SeNPs/miR shows a uniform shell-core structure with a particle size of ≈90 nm. Co-delivering miR-148a-3p inhibitors and Se effectively alleviate hyperlipidemia via LDLR pathway and Toll-Like Receptor 4 (TLR-4)/NF-κB signaling pathway, respectively. Furthermore, coated by PM, PM/CS-SeNPs/miR successfully prolong circulation time to 48 h in vivo and quickly target to liver with no toxicity. This dual combination therapy with miRNAs and Se based on nanoparticles targeted delivery presents a high-performance strategy for precise hyperlipidemia treatment.

Assessing the possible association between MTHFR (rs1801133) and GPx-1 (rs1050450) polymorphisms with the risk of type 2 diabetes, diabetic neuropathy, and diabetic retinopathy

PURPOSE

Oxidative stress in chronic hyperglycemia could injure the tissues and onset of diabetes-related complications like retinopathy and neuropathy. This study investigates the association between methylenetetrahydrofolate reductase (MTHFR) and glutathione peroxidase (GPx) genetic variants with these complications.

METHODS

In this case-control study, 400 individuals, including 100 healthy subjects and 300 patients with type 2 diabetes mellitus (T2DM) in three subgroups: with retinopathy(n = 100), with neuropathy(n = 100), and without complication (n = 100) from West Iran, were studied. MTHFR (rs1801133) and GPx-1 (rs1050450) variants were identified by the PCR-RFLP method. The plasma levels of GPx activity, glutathione, malondialdehyde (MDA), total antioxidant capacity (TAC), and total oxidative stress (TOS) were measured by chemical methods.

RESULTS

Higher BMI, TOS and MDA levels were observed in patients with neuropathy compared to other patients and controls. Diabetic patients with neuropathy had lower levels of glutathione (7.8 ± 4.5; P < 0.001), GPx activity (39.5 ± 8.5; P < 0.001), and TAC (703.1 ± 129.1; P = 0.0001) in comparison with other groups. The patients without complication and retinopathic patients had higher plasma levels of glutathione (12.2 ± 2.4; p = 0.02) and TAC (793.4 ± 124.6; P < 0.001), respectively. MTHFR TT genotype significantly correlated with lower levels of TOS (3.5 ± 1.1; P < 0.001) and OSI (0.0050 ± 0.001; P < 0.001). Subjects with the GPx-1 TT genotype had higher levels of MDA (6.8 ± 2.5; P = 0.02) and lower levels of TOS (3.7 ± 1.6; P < 0.001), which is statistically significant. TT genotype of MTHFR was associated with 3.9 fold (95% CI 1.04-4.76; P = 0.0436) increased risk of neuropathy. Also, GPx-1 CT genotype increased the risk of retinopathy [OR = 2.7 (95% CI = 1.38-5.44; P = 0.0039)].

CONCLUSION

The MTHFR TT genotype increased the risk of neuropathy in diabetic patients significantly. The GPx-1 CT genotype is related to increased retinopathy risk among diabetic patients. Both MTHFR and Gpx-1 TT genotypes were associated with higher BMI levels.

The Bioactivity and Phytochemicals of Muscari comosum (Leopoldia comosa), a Plant of Multiple Pharmacological Activities

Leopoldia comosa (LC), popularly known as Muscari comosum, spontaneously grows in the Mediterranean region and its bulbs are used as a vegetable. Traditionally, they are also used to treat various diseases and conditions, which has inspired the study of the pharmacological activities of different parts of LC. These studies revealed the numerous biological properties of LC including antioxidant, anti-inflammatory, anti-diabetes, anti-obesity, anti-cancer, anti-Alzheimer's disease, antibacterial, and immune stimulant. High antioxidant activity compared to other non-cultivated plants, and the potential role of antioxidant activity in other reported activities make LC an excellent candidate to be developed as an antioxidant plant against important associated diseases. The presence of a diverse class of phytochemicals (n = 85), especially flavonoids and homoisoflavones, in LC, also imparts significance to the nutraceutical candidature of the plant. However, limited animal studies and the lack of a directional approach have limited the further design of effective clinical studies for the development of LC. The current study is the first attempt to comprehensively compile information regarding the phytochemicals and pharmacological activities of LC, emphasize the targets/markers targeted by LC, important in other activities, and also highlight the current gaps and propose possible bridges for the development of LC as a therapeutic and/or supplement against important diseases.

MX1 and UBE2L6 are potential metaflammation gene targets in both diabetes and atherosclerosis

Background

The coexistence of diabetes mellitus (DM) and atherosclerosis (AS) is widespread, although the explicit metabolism and metabolism-associated molecular patterns (MAMPs) responsible for the correlation are still unclear.

Methods

Twenty-four genetically wild-type male Ba-Ma mini pigs were randomly divided into five groups distinguished by different combinations of 90 mg/kg streptozotocin (STZ) intravenous injection and high-cholesterol/lipid (HC) or high-lipid (HL) diet feeding for 9 months in total. Pigs in the STZ+HC and STZ+HL groups were injected with STZ first and then fed the HC or HL diet for 9 months. In contrast, pigs in the HC+STZ and HL+STZ groups were fed the HC or HL diet for 9 months and injected with STZ at 3 months. The controls were only fed a regular diet for 9 months. The blood glucose and abdominal aortic plaque observed through oil red O staining were used as evaluation indicators for successful modelling of DM and AS. A microarray gene expression analysis of all subjects was performed.

Results

Atherosclerotic lesions were observed only in the HC+STZ and STZ+HC groups. A total of 103 differentially expressed genes (DEGs) were identified as common between them. The most significantly enriched pathways of 103 common DEGs were influenza A, hepatitis C, and measles. The global and internal protein-protein interaction (PPI) networks of the 103 common DEGs consisted of 648 and 14 nodes, respectively. The top 10 hub proteins, namely, ISG15, IRG6, IRF7, IFIT3, MX1, UBE2L6, DDX58, IFIT2, USP18, and IFI44L, drive aspects of DM and AS. MX1 and UBE2L6 were the intersection of internal and global PPI networks. The expression of MX1 and UBE2L6 was 507.22 ± 342.56 and 96.99 ± 49.92 in the HC+STZ group, respectively, which was significantly higher than others and may be linked to the severity of hyperglycaemia-related atherosclerosis. Further PPI network analysis of calcium/micronutrients, including MX1 and UBE2L6, consisted of 58 and 18 nodes, respectively. The most significantly enriched KEGG pathways were glutathione metabolism, pyrimidine metabolism, purine metabolism, and metabolic pathways.

Conclusions

The global and internal PPI network of the 103 common DEGs consisted of 648 and 14 nodes, respectively. The intersection of the nodes of internal and global PPI networks was MX1 and UBE2L6, suggesting their key role in the comorbidity mechanism of DM and AS. This inference was partly verified by the overexpression of MX1 and UBE2L6 in the HC+STZ group but not others. Further calcium- and micronutrient-related enriched KEGG pathway analysis supported that MX1 and UBE2L6 may affect the inflammatory response through micronutrient metabolic pathways, conceptually named metaflammation. Collectively, MX1 and UBE2L6 may be potential common biomarkers for DM and AS that may reveal metaflammatory aspects of the pathological process, although proper validation is still needed to determine their contribution to the detailed mechanism.

Reduction of neutral lipid reservoirs, bioconversion and untargeted metabolomics reveal distinct roles for vitamin K isoforms on lipid metabolism

Vitamin K isoforms are known as co-factors for the synthesis of blood-clotting proteins, but several other bioactivities were reported. In this work, we isolated a vitamin K1-analogue (OH-PhQ) from the cyanobacterium Tychonema sp. LEGE 07196 with lipid reducing activity. OH-PhQ reduced neutral lipid reservoirs with an EC50 value of 31 μM after 48 h exposure in zebrafish larvae, while other vitamin K isoforms had EC50 values of 21.1 μM (K2) and 1.2 μM (K3). No lipid reducing activity was observed for K1 up to 50 μM. The presence of vitamin K isoforms was studied in zebrafish after exposure (OH-PhQ, K1, K2 and K3), and a clear preference for bioconversion was observed to retain K1 and OH-PhQ. Untargeted metabolomics revealed different biological effects for vitamin K isoforms on the subclass and metabolite level, but similarities were present on the compound class level, particularly on the regulation of glycerophospholipids. Our data showed for the first time a lipid reducing activity of OH-PhQ and performed a comparative analysis of vitamin K isoforms, which could be important for the development of future nutraceuticals or food supplements.

Selenium bioavailability modulates the sensitivity of thyroid cells to iodide excess

INTRODUCTION

Iodide is an essential micronutrient for the synthesis of thyroid hormones and its imbalance is involved in the origin of different thyroid pathological processes. Selenium (Se) is another essential trace element that contributes to thyroid preservation through the control of the redox homeostasis. Different studies have demonstrated that sodium-iodide-symporter (NIS) is downregulated in the presence of iodide excess and Se supplementation reverses this effect. We also demonstrated that NOX4-derived ROS are involved in NIS repression induced by iodide excess. The aim of this study was to investigate how Se bioavailability is decisive in the sensitivity to iodide excess on a differentiated rat thyroid cell line (FRTL-5).

RESULTS

We demonstrated that siRNA-mediated silencing of Nox4 suppressed AKT phosphorylation induced by iodide excess. Iodide increases TGF-β1 mRNA expression, AKT phosphorylation, ROS levels and decreases GPX1 and TXRND1 mRNAs expression while Se reversed these effects. Furthermore, iodide induced Nrf2 transcriptional activity only in Se-supplemented cultures, suggesting that Se positively influences Nrf2 activation and selenoenzyme response in FRTL-5. Se, also inhibited NF-κB phosphorylation induced by iodide excess. In addition, we found that iodide excess decreased total phosphatase activity and PTP1B and PTEN mRNA expression. Se supply restored only PTEN mRNA expression. Finally, we studied the 2-α-iodohexadecanal (2-IHD) effects since it has been proposed as intermediary of iodide action on thyroid autoregulation. 2-IHD stimulated PI3K/AKT activity and reduced NIS expression by a ROS-independent mechanism. Also, we found that 2-IHD increased TGF-β1 mRNA and TGF-β inhibitor (SB431542) reverses the 2-IHD inhibitory effect on NIS mRNA expression, suggesting that TGF-β1 signaling pathway could be involved. Although Se reduced 2-IHD-induced TGFB1 levels, it could not reverse its inhibitory effect on NIS expression.

CONCLUSION

Our study suggests that Se bioavailability may improve the expression of antioxidant genes through the activation of Nrf2, interfere in PI3K/AKT signaling and NIS expression by redox modulation.

Essential Trace Elements in Patients with Dyslipidemia: A Meta-analysis

BACKGROUND

Lipid metabolism is a complex process that includes lipid uptake, transport, synthesis, and degradation. Trace elements are vital in maintaining normal lipid metabolism in the human body. This study explores the relationship between serum trace elements and lipid metabolism.

METHODS

In this study, we reviewed articles on the relationship between alterations in somatic levels of zinc, iron, calcium, copper, chrome, manganese, selenium, and lipid metabolism. In this systematic review and mate-analysis, databases such as PubMed, Web of Science, and China National Knowledge Infrastructure (CNKI), Wanfang was searched for articles on the relationship published between January 1, 1900, and July 12, 2022. The meta-analysis was performed using Review Manager5.3 (Cochrane Collaboration).

RESULTS

No significant association was found between serum zinc and dyslipidemia, while other serum trace elements (iron, selenium, copper, chromium, and manganese) were associated with hyperlipidemia.

CONCLUSION

The present study suggested that the human body's zinc, copper, and calcium content may be related to lipid metabolism. However, findings on lipid metabolism and Iron, Manganese have not been conclusive. In addition, the relationship between lipid metabolism disorders and selenium levels still needs to be further studied. Further research is needed on treating lipid metabolism diseases by changing trace elements.

The Regulation of Selenoproteins in Diabetes: A New Way to Treat Diabetes

Selenium is an essential micronutrient required for the synthesis and function of selenoproteins, most of which are enzymes involved in maintaining oxidative balance in the body. Diabetes is a group of metabolic disorders characterized by high blood glucose levels over a prolonged period of time. There are three main types of diabetes: type 1, type 2, and gestational diabetes. This review summarizes recent advances in the field of diabetes research with an emphasis on the roles of selenoproteins on metabolic disturbance in diabetes. We also discuss the interaction between selenoproteins and glucose and lipid metabolism to provide new insights into the prevention and treatment of diabetes.

Behavioral and histological assessment of a novel treatment of neuroHIV in humanized mice

Neurocognitive deficits are prevalent among people living with HIV, likely due to chronic inflammation and oxidative stress in the brain. To date, no pharmaceutical treatments beyond antiretroviral therapy (ARV) has been shown to reduce risk for, or severity of, HIV-associated neurocognitive disorder. Here we investigate a novel compound, CDDO-Me, with documented neuroprotective effects via activation of the nrf2 and inhibition of the NFkB pathways.

Methods

We conducted three studies to assess the efficacy of CDDO-Me alone or in combination with antiretroviral therapy in humanized mice infected with HIV; behavioral, histopathological, and immunohistochemical.

Results

CDDO-Me in combination with ARV rescued social interaction deficits; however, only ARV was associated with preserved functioning in other behaviors, and CDDO-Me may have attenuated those benefits. A modest neuroprotective effect was found for CDDO-Me when administered with ARV, via preservation of PSD-95 expression; however, ARV alone had a more consistent protective effect. No significant changes in antioxidant enzyme expression levels were observed in CDDO-Me-treated animals. Only ARV use seemed to affect some antioxidant levels, indicating that it is ARV rather than CDDO-Me that is the major factor providing neuroprotection in this animal model. Finally, immunohistochemical analysis found that several cellular markers in various brain regions varied due to ARV rather than CDDO-Me.

Conclusion

Limited benefit of CDDO-Me on behavior and neuroprotection were observed. Instead, ARV was shown to be the more beneficial treatment. These experiments support the future use of this chimeric mouse for behavioral experiments in neuroHIV research.

Transcriptome analysis reveals molecular regulation mechanism of Tibet sheep tolerance to high altitude oxygen environment

As one of the most important livestock breeds on the Qinghai-Tibet Plateau, Tibetan sheep are of great importance to the local economy, agriculture and culture. Its adaptive mechanism in low temperature and low oxygen at highland altitudes has not been reported. In this study, transcriptome sequencing was used to analyze the heart, liver, spleen, lung, kidney, and muscle tissue of sheep at low and highland altitudes. LOC101112291, SELENOW, COL3A1, GPX1, TMSB4X and HSF4 were selected as candidate genes for adapting to plateau characteristics in Tibet Sheep. Besides, glutathione metabolism, arachidonic acid metabolism, nucleotide excision repair, regulation of actin cytoskeleton, protein digestion and absorption, thyroid hormone synthesis, relaxation signaling pathways may play important roles in the adaptation to plateau hypoxia, and cold tolerance. Structural analysis also showed that sequencing genes related to the adaptation mechanism of Tibet sheep to highland altitude. This study will lay a certain foundation for Tibet sheep research.

Biological and Catalytic Properties of Selenoproteins

Selenocysteine is a catalytic residue at the active site of all selenoenzymes in bacteria and mammals, and it is incorporated into the polypeptide backbone by a co-translational process that relies on the recoding of a UGA termination codon into a serine/selenocysteine codon. The best-characterized selenoproteins from mammalian species and bacteria are discussed with emphasis on their biological function and catalytic mechanisms. A total of 25 genes coding for selenoproteins have been identified in the genome of mammals. Unlike the selenoenzymes of anaerobic bacteria, most mammalian selenoenzymes work as antioxidants and as redox regulators of cell metabolism and functions. Selenoprotein P contains several selenocysteine residues and serves as a selenocysteine reservoir for other selenoproteins in mammals. Although extensively studied, glutathione peroxidases are incompletely understood in terms of local and time-dependent distribution, and regulatory functions. Selenoenzymes take advantage of the nucleophilic reactivity of the selenolate form of selenocysteine. It is used with peroxides and their by-products such as disulfides and sulfoxides, but also with iodine in iodinated phenolic substrates. This results in the formation of Se-X bonds (X = O, S, N, or I) from which a selenenylsulfide intermediate is invariably produced. The initial selenolate group is then recycled by thiol addition. In bacterial glycine reductase and D-proline reductase, an unusual catalytic rupture of selenium-carbon bonds is observed. The exchange of selenium for sulfur in selenoproteins, and information obtained from model reactions, suggest that a generic advantage of selenium compared with sulfur relies on faster kinetics and better reversibility of its oxidation reactions.

Salat dhuha effect on oxidative stress in elderly women: A randomized controlled trial

Background

The aging process and a chronic sedentary lifestyle in the elderly as a result of physical restrictions during the COVID-19 pandemic, induces oxidative stress through oxygen supply and antioxidant activity imbalance which in turn induce degenerative diseases. Salat dhuha as a prayer and mind-body medicine which is practiced by the Muslim community can hopefully be a solution to decrease oxidative stress in the elderly.

Objective

To evaluate the acute physiological effects of salat dhuha on Glutathione Peroxidase activity (GPx) as an antioxidant and Malondialdehyde (MDA) as an oxidant in healthy elderly Muslim women population who have done salat dhuha regularly.

Method

A randomized controlled study was done on elderly women (aged 60-74 years old) who are treated in the North Sumatra Government's Nursing Home in Binjai and who routinely do 2 rakaat of salat dhuha every day. Several physical, clinical, and blood examinations were done pre and post-intervention. 101 elderly Muslim women in the nursing home were selected, 26 met the study criteria and were included in the study. The volunteers were randomized into 2 groups using lottery papers, the "2-rakaat salat dhuha group" (n = 13) and the "8-rakaat salat dhuha group" (n = 13). All volunteers did salat dhuha for at least 5 days per week for 6 weeks.

Result

24 elderly women completed the study, and one volunteer from each group dropped out. The characteristics of participants from both groups were homogenous. Results of the t-independent analysis showed that MDA concentrations in both groups in the pre and post-test were not significantly different (p > 0,05). Mann Whitney analysis showed that GPx on both groups in the pre and post-test were not significantly different (p > 0,05). Paired sample t-test analysis on the MDA concentrations pre and post-test in the 8-rakaat group showed a significant difference in MDA levels (p < 0,05). The 8-rakaat salat dhuha group showed that GPx activity increases as much as 8,9% and MDA levels decrease as much as 48,35 % after 6 weeks.

Conclusion

Salat dhuha promotes redox homeostasis and has the potential to prevent oxidative stress in elderly women.

Microalgae as a Nutraceutical Tool to Antagonize the Impairment of Redox Status Induced by SNPs: Implications on Insulin Resistance

Microalgae represent a growing innovative source of nutraceuticals such as carotenoids and phenolic compound which are naturally present within these single-celled organisms or can be induced in response to specific growth conditions. The presence of the unfavourable allelic variant in genes involved in the control of oxidative stress, due to one or more SNPs in gene encoding protein involved in the regulation of redox balance, can lead to pathological conditions such as insulin resistance, which, in turn, is directly involved in the pathogenesis of type 2 diabetes mellitus. In this review we provide an overview of the main SNPs in antioxidant genes involved in the promotion of insulin resistance with a focus on the potential role of microalgae-derived antioxidant molecules as novel nutritional tools to mitigate oxidative stress and improve insulin sensitivity.

Role of selenium in type 2 diabetes, insulin resistance and insulin secretion

Selenium is a trace mineral essential for life that acts physiologically through selenoproteins. Among other actions, the endogenous antioxidant selenoprotein glutathione peroxidase and the selenium transporter in blood, selenoprotein P, seem to play an important role in type 2 diabetes mellitus and insulin resistance by weakening the insulin signaling cascade through different mechanisms. Recent findings also suggest that selenoproteins also affect insulin biosynthesis and insulin secretion. This review discussed the role of selenium in type 2 diabetes and the complex interplay between selenoproteins and insulin pathways.

Molecular Genetics of Abnormal Redox Homeostasis in Type 2 Diabetes Mellitus

Numerous studies have shown that oxidative stress resulting from an imbalance between the production of free radicals and their neutralization by antioxidant enzymes is one of the major pathological disorders underlying the development and progression of type 2 diabetes (T2D). The present review summarizes the current state of the art advances in understanding the role of abnormal redox homeostasis in the molecular mechanisms of T2D and provides comprehensive information on the characteristics and biological functions of antioxidant and oxidative enzymes, as well as discusses genetic studies conducted so far in order to investigate the contribution of polymorphisms in genes encoding redox state-regulating enzymes to the disease pathogenesis.

Gpx4, Selenov, and Txnrd3 Are Three Most Testis-Abundant Selenogenes Resistant to Dietary Selenium Concentrations and Actively Expressed During Reproductive Ages in Rats

Almost all selenogenes are expressed in the testis, and those have the highest and constant expressions will be the primary candidates for functional analysis of selenium (Se) in male reproduction. This study aimed to profile the mRNA expressions of the testis-abundant selenogenes of rat models in responses to growth and dietary Se concentrations. Forty-eight weaning SD male rats were fed Se deficient basal diet (BD) for 5 weeks and then randomly grouped (n = 12/group) for being fed BD or BD plus 0.25, 3, or 5 mg Se/kg for 4 more weeks before sacrifice. Abundances of selenogenomic mRNAs in the liver and testis were determined with relative qPCR and those of the testis-abundant selenogenes in 13 kinds of tissues were assayed with a molecular beacon-based qPCR. Spatiotemporal expressions of rat selenogenome were also analyzed with the RNA-Seq transcriptomic data published by NCBI. mRNA abundances of glutathione peroxidase 4 (Gpx4), nuclear Gpx4 (nGpx4), selenoprotein V (Selenov), and thioredoxin reductase 3 (Txnrd3) in the testis were significantly higher than that in any other tissues (P < 0.05). Moreover, testicular mRNA abundances of Gpx4, Selenov, and Txnrd3 were not affected by levels of dietary Se supplementation (P > 0.05), and much higher at 6-21 weeks old than at 2 and 104 weeks old (P < 0.05). The result showed that Gpx4, Selenov, and Txnrd3 were most highly expressed in the testis of rats especially at reproductive ages and resistant to the impact of dietary Se levels, which suggested their specific importance in male reproduction.

The role of neurohumoral factors in the persistence of aseptic bone inflammation in patients with diabetic neuroosteoarthropathy

BACKGROUND: Diabetic neuroosteoarthropathy (DNOAP, Charcot foot) is a relatively rare complication of diabetes mellitus (DM), which can lead not only to impaired support function of the lower limb in such patients, but also to high amputation. DNOAP is characterized by persistent aseptic inflammation of the bone structures of the foot, which creates significant ­difficulties in planning therapeutic measures. In the medical literature, there are data demonstrating the role of individual ­cytokines and neurohumoral factors in the prolongation of the inflammatory process in diabetes, however, there are currently very few studies that determine reliable markers of aseptic inflammation in DNOAP.

AIM: To study the effect of neurohumoral factors and advanced glycation end products on the activity of aseptic inflammation in the bone structures of the foot in patients with type 2 diabetes mellitus (DM2) and diabetic neuroosteoarthropathy.

MATERIALS AND METHODS. The study included 88 patients with type 2 diabetes (45 men, 43 women). Group 1 consisted of patients with DM2 and inactive DNOAP (n= 43), group 2 (n= 45) consisted of patients with DM2 and distal diabetic neuropathy without osteoarticular pathology. The diagnosis of diabetic neuropathy was based on the analysis of the clinical picture and indicators of peripheral sensitivity. Diagnosis of DNOAP and determination of its stage was based on clinical data, the results of infrared thermometry and radiology tests of the foot bones. General clinical assessment was used, radiology tests (X-ray, MRI), evaluation of CRP, calprotectin, copeptin, glutathione peroxidase 1 (GP1).

RESULTS. According to the results of examination and palpation of the feet, as well as the analysis of the temperature gradient of the skin of the affected and contralateral limb (infrared thermometry), DNOAP was detected and the stage of this complication was determined. The diagnosis of the chronic stage of DNOAP was confirmed by the results of MRI and the clinical picture (no difference in skin temperature on the symmetrical areas of the feet). According to the results of laboratory analysis, a statistically significant difference in copeptin values was revealed — in group 1 — 0.232 µg/ml [0.147; 0.342], in group 2 — 0.115 µg/ml [0.065; 0.203] (p>0.05) and CRP — in group 1 — 7.113 mg/l [2.453; 16.505], in group 2 — 2.187 mg/l [1.131; 5.567] (p>0.05), leukocyte levels in the groups did not differ significantly: group 1 — 7.86 [6.40; 9.00]*10^9, group 2 — 7.00 [6.00; 8.15] (p>0.05). There was a trend towards an increase in the level of calprotectin and glutathione peroxidase-1 in the DNOAP group, however, the differences were not significant. calprotectin — in group 1 — 1.948 [1.229; 2.969], in group 2 — 1.692 [1.16; 2.514] μg/ml and glutathione peroxidase-1 in group 1 — 24.72 [20.1; 31.82], in group 2 — 22.98 [18.94; 31.2] ng/ml.

CONCLUSION. In the study, statistically significant differences were obtained in the levels of copeptin and C-reactive protein: in patients with DNOAP, their values were significantly higher, which indicates the persistence of the aseptic inflammatory process in the bone tissue of patients even in the chronic stage of DNOAP. These data may help in deciding whether to use one or another method of unloading the affected joints, which will affect the clinical prognosis. The study of neurohumoral markers of arthropathy in the blood serum of patients with DM2 is carried out for the first time, and therefore it is difficult to compare with the results of other authors. It can be assumed that copeptin and CRP are significant markers of persistent inflammation of the osteoarticular structures of the foot in DNOAP.

Emerging roles of selenium on metabolism and type 2 diabetes

Selenium is recognized as an essential element for human health and enters human body mainly via diet. Selenium is a key constituent in selenoproteins, which exert essential biological functions, including antioxidant and anti-inflammatory effects. Several selenoproteins including glutathione peroxidases, selenoprotein P and selenoprotein S are known to play roles in the regulation of type 2 diabetes. Although there is a close association between certain selenoproteins with glucose metabolism or insulin resistance, the relationship between selenium and type 2 diabetes is complex and remains uncertain. Here we review recent advances in the field with an emphasis on roles of selenium on metabolism and type 2 diabetes. Understanding the association between selenium and type 2 diabetes is important for developing clinical practice guidelines, establishing and implementing effective public health policies, and ultimately combating relative health issues.

Novel role and mechanism of glutathione peroxidase-4 in nutritional pancreatic atrophy of chicks induced by dietary selenium deficiency

Nutritional pancreatic atrophy (NPA) is a classical Se/vitamin E deficiency disease of chicks. To reveal molecular mechanisms of its pathogenesis, we fed day-old chicks a practical, low-Se diet (14 μg Se/kg), and replicated the typical symptoms of NPA including vesiculated mitochondria, cytoplasmic vacuoles, and hyaline bodies in acinar cells of chicks as early as day 18. Target pathway analyses illustrated a > 90% depletion (P < 0.05) of glutathione peroxidase 4 (GPX4) protein and up-regulated apoptotic signaling (cytochrome C/caspase 9/caspase 3) in the pancreas and(or) acinar cells of Se deficient chicks compared with Se-adequate chicks. Subsequently, we overexpressed and suppressed GPX4 expression in the pancreatic acinar cells and observed an inverse (P < 0.05) relationship between the GPX4 production and apoptotic signaling and cell death. Applying pull down and mass spectrometry, we unveiled that GPX4 bound prothymosin alpha (ProTalpha) to inhibit formation of apoptosome in the pancreatic acinar cells. Destroying this novel protein-protein interaction by silencing either gene expression accelerated H2O2-induced apoptosis in the cells. In the end, we applied GPX4 shRNA to silence GPX4 expression in chick embryo and confirmed the physiological relevance of the GPX4 role and mechanism shown ex vivo and in the acinar cells. Altogether, our results indicated that GPX4 depletion in Se-deficient chicks acted as a major contributor to their development of NPA due to the lost binding of GPX4 to ProTalpha and its subsequent inhibition on the cytochrome c/caspase 9/caspase 3 cascade in the acinar cells. Our findings not only provide a novel molecular mechanism for explaining pathogenesis of NPA but also reveal a completely new cellular pathway in regulating apoptosis by selenoproteins.

Impact of Sustained Exogenous Irisin Myokine Administration on Muscle and Myocyte Integrity in Sprague Dawley Rats

Irisin is an exercise-induced myokine implicated as a fundamental mediator of physical activity benefits. The aim of the present study was to investigate the role of the chronic administration model of irisin on the physiological and molecular status of skeletal muscle. A total of 20 female Sprague Dawley rats (250 ± 40 g) were implanted with an irisin-loaded osmotic pump (5 µg/kg/day) for 42 days; in addition, 3 females received a single subcutaneous injection of irisin (5 µg/kg). On a weekly basis for six weeks, animals were weighed and blood samples were collected. After 42 days, hind muscle biopsies were collected for histology and gene analysis. Serum irisin, clinical biochemistry, and histopathology were quantified and evaluated. Genes encoding for different physiological muscle activities, such as oxidative stress, fatty acid metabolism, muscle hypertrophy, mitochondrial fusion, and aging were assayed. The results showed a significant reduction in body weight percentage and creatine kinase level without affecting the morphological characteristics of skeletal muscle. Significant changes were noted in genes involved in muscle physiological activity, growth, and aging, as well as genes encoding for the antioxidant system, fatty acid oxidation processes, and mitochondrial fusion. In conclusion, exogenous irisin can induce the same physiological and molecular mechanisms that might be induced by exercise.

Higher selenium was associated with higher risk of diabetes: Consistent evidence from longitudinal and cross-sectional studies based on nail and serum selenium measures

Although the association between selenium (Se) and diabetes has been well-discussed in recent years, few studies have focused on the effects of long-term natural Se exposure and rarely concerned the effects of different Se biomarkers. To address this question, we carried out a 7-year longitudinal study on older adults aged over 65 and another cross-sectional study on middle-aged and older adults aged 40 and above from Chinese soil Se-deplete and Se-optimum areas. Cox proportional hazard models were used to evaluate the associations between nail Se levels and incidence risk of diabetes. Unconditional logistic regression models and analysis of variance models were used to examine the associations between serum Se levels and the prevalence risk of diabetes. The nail and serum Se levels were 0.47 ± 0.20 μg/g and 111.09 ± 55.01 μg/L for the two study populations, respectively. For both of the independent studies, higher Se levels were observed to be associated with a higher risk of diabetes and prediabetes. Compared with the Second nail Se quartile (Q2), the adjusted hazard ratios (HRs) and 95 % confidence intervals (95 % CIs) of diabetes for Q1, Q3 and Q4 were 1.24(0.70, 2.21), 1.53(0.98, 2.39) and 1.31(0.76, 2.26), respectively, and the adjusted HRs (95 % CIs) of prediabetes were 1.47(0.77, 2.81), 1.38(0.83, 2.30), and 1.97(1.13, 3.44), respectively. Compared with the first serum Se quintile (Q1), the adjusted odds ratios (ORs) and 95 % CIs of diabetes for higher quintiles were 1.12(0.75, 1.66), 1.05(0.71, 1.57), 1.09(0.73, 1.62) and 1.51(1.02, 2.19), and the adjusted ORs (95 % CIs) of prediabetes were 1.27(0.77, 2.09), 1.70(1.05, 2.74), 1.94(1.21, 3.11) and 1.67(1.03, 2.71). Our findings consistently suggest that higher Se status is associated with a higher risk of diabetes in adults.

Proteomic analysis of the liver regulating lipid metabolism in Chaohu ducks using two-dimensional electrophoresis

In this study, we aimed to characterize the liver protein profile of Chaohu ducks using two-dimensional electrophoresis and proteomics. The livers were quickly collected from 120 healthy, 84-day-old Chaohu ducks. The intramuscular fat (IMF) content of the left pectoralis muscle was determined using the Soxhlet extraction method. The total protein of liver tissues from the high and low IMF groups was extracted for proteomics. Functional enrichment analysis of the differentially expressed proteins (DEPs) was conducted using gene ontology (GO) and kyoto encyclopedia of genes and genomes (KEGG). In total, 43 DEPs were identified. Functional enrichment analysis indicated that these DEPs were significantly related to four lipid metabolic processes: carboxylic acid metabolic process, ATP metabolic process, oxoacid metabolic process, and organic acid metabolic process. Three pathways correlated with lipid metabolism were identified using KEGG analysis: glycolysis/gluconeogenesis, pentose phosphate pathway, fructose, and mannose metabolism. Eight key proteins associated with lipid metabolism were identified: ALDOB, GAPDH, ENO1, RGN, TPI1, HSPA9, PRDX1, and GPX1. Protein–protein interaction analysis revealed that the glycolysis/gluconeogenesis pathway mediated the interaction relationship. Key proteins and metabolic pathways were closely related to lipid metabolism and showed a strong interaction in Chaohu ducks.

Different Effects of Low Selenite and Selenium-Nanoparticle Supplementation on Adipose Tissue Function and Insulin Secretion in Adolescent Male Rats

Adolescence is a period of intense growth and endocrine changes, and obesity and insulin-resistance processes during this period have lately been rising. Selenium (Se) homeostasis is related to lipid metabolism depending on the form and dose of Se. This study tests the actions of low-dose selenite and Se nanoparticles (SeNPs) on white (WAT) and brown adipose tissue (BAT) deposition, insulin secretion, and GPx1, IRS-1 and FOXO3a expression in the WAT of adolescent rats as regards oxidative stress, adipocyte length and adipokine secretion. Four groups of male adolescent rats were treated: control (C), low selenite supplementation (S), low SeNP supplementation (NS) and moderate SeNP supplementation (NSS). Supplementation was received orally through water intake; NS and NSS rats received two- and tenfold more Se than C animals, respectively. SeNPs were obtained by reducing Se tetrachloride in the presence of ascorbic acid. For the first time in vivo, it was demonstrated that low selenite supplementation contributed to increased adipogenesis via the insulin signaling pathway and LCN2 modulation, while low SeNP administration prevented fat depots in WAT via the decrease in insulin signaling and FOXO3a autophagy in WAT, lowering inflammation. These effects were independent of GPx1 expression or activity in WAT. These findings provide data for dietary approaches to prevent obesity and/or anorexia during adolescence. These findings may be relevant to future studies looking at a nutritional approach aimed at pre-venting obesity and/or anorexia in adolescence.

Molecular Mechanisms Related to Responses to Oxidative Stress and Antioxidative Therapies in COVID-19: A Systematic Review

The coronavirus disease (COVID-19) pandemic is a leading global health and economic challenge. What defines the disease's progression is not entirely understood, but there are strong indications that oxidative stress and the defense against reactive oxygen species are crucial players. A big influx of immune cells to the site of infection is marked by the increase in reactive oxygen and nitrogen species. Our article aims to highlight the critical role of oxidative stress in the emergence and severity of COVID-19 and, more importantly, to shed light on the underlying molecular and genetic mechanisms. We have reviewed the available literature and clinical trials to extract the relevant genetic variants within the oxidative stress pathway associated with COVID-19 and the anti-oxidative therapies currently evaluated in the clinical trials for COVID-19 treatment, in particular clinical trials on glutathione and N-acetylcysteine.

Potential role of oxidative stress in the pathogenesis of diabetic bladder dysfunction

Diabetes mellitus is a chronic metabolic disease, posing a considerable threat to global public health. Treating systemic comorbidities has been one of the greatest clinical challenges in the management of diabetes. Diabetic bladder dysfunction, characterized by detrusor overactivity during the early stage of the disease and detrusor underactivity during the late stage, is a common urological complication of diabetes. Oxidative stress is thought to trigger hyperglycaemia-dependent tissue damage in multiple organs; thus, a growing body of literature has suggested a possible link between functional changes in urothelium, muscle and the corresponding innervations. Improved understanding of the mechanisms of oxidative stress could lead to the development of novel therapeutics to restore the redox equilibrium and scavenge excessive free radicals to normalize bladder function in patients with diabetes.

The role of glutathione peroxidase-1 in health and disease

Glutathione peroxidase 1 (GPx1) is an important cellular antioxidant enzyme that is found in the cytoplasm and mitochondria of mammalian cells. Like most selenoenzymes, it has a single redox-sensitive selenocysteine amino acid that is important for the enzymatic reduction of hydrogen peroxide and soluble lipid hydroperoxides. Glutathione provides the source of reducing equivalents for its function. As an antioxidant enzyme, GPx1 modulates the balance between necessary and harmful levels of reactive oxygen species. In this review, we discuss how selenium availability and modifiers of selenocysteine incorporation alter GPx1 expression to promote disease states. We review the role of GPx1 in cardiovascular and metabolic health, provide examples of how GPx1 modulates stroke and provides neuroprotection, and consider how GPx1 may contribute to cancer risk. Overall, GPx1 is protective against the development and progression of many chronic diseases; however, there are some situations in which increased expression of GPx1 may promote cellular dysfunction and disease owing to its removal of essential reactive oxygen species.

The role of glutathione peroxidase-1 in health and disease

Glutathione peroxidase 1 (GPx1) is an important cellular antioxidant enzyme that is found in the cytoplasm and mitochondria of mammalian cells. Like most selenoenzymes, it has a single redox-sensitive selenocysteine amino acid that is important for the enzymatic reduction of hydrogen peroxide and soluble lipid hydroperoxides. Glutathione provides the source of reducing equivalents for its function. As an antioxidant enzyme, GPx1 modulates the balance between necessary and harmful levels of reactive oxygen species. In this review, we discuss how selenium availability and modifiers of selenocysteine incorporation alter GPx1 expression to promote disease states. We review the role of GPx1 in cardiovascular and metabolic health, provide examples of how GPx1 modulates stroke and provides neuroprotection, and consider how GPx1 may contribute to cancer risk. Overall, GPx1 is protective against the development and progression of many chronic diseases; however, there are some situations in which increased expression of GPx1 may promote cellular dysfunction and disease owing to its removal of essential reactive oxygen species.

Binge drinking during the adolescence period causes oxidative damage-induced cardiometabolic disorders: A possible ameliorative approach with selenium supplementation

Binge drinking (BD) is the most common alcohol consumption model among adolescents. BD exposure during adolescence disrupts the nervous system function, being involved in the major mortality causes at this age: motor vehicle accidents, homicides and suicides. Recent studies have also shown that BD consumption during adolescence affects liver, renal and cardiovascular physiology, predisposing adolescents to future adult cardiometabolic damage. BD is a particularly pro-oxidant alcohol consumption pattern, because it leads to the production of a great source of reactive oxygen species (ROS) via the microsomal ethanol oxidizing system, also decreasing the antioxidant activity of glutathione peroxidase (GPx). Selenium (Se) is a mineral which plays a pivotal role against oxidation; it forms part of the catalytic center of different antioxidant selenoproteins such as GPxs (GPx1, GPx4, GPx3) and selenoprotein P (SelP). Specifically, GPx4 has an essential role in mitochondria, preventing their oxidation, apoptosis and NFkB-inflamative response, being this function even more relevant in heart's tissue. Se serum levels are decreased in acute and chronic alcoholic adult patients, being correlated to the severity of oxidation, liver damage and metabolic profile. Experimental studies have described that Se supplementation to alcohol exposed mice clearly decreases oxidative and liver damage. However, clinical BD effects on Se homeostasis and selenoproteins' tissue distribution related to oxidation during adolescence are not yet studied. In this narrative review we will describe the use of sodium selenite supplementation as an antioxidant therapy in adolescent BD rats in order to analyze Se homeostasis implication during BD exposure, oxidative balance, apoptosis and inflammation, mainly in liver, kidney, and heart. These biomolecular changes and the cardiovascular function will be analyzed. Se supplementation therapies could be a good strategy to prevent the oxidation, inflammation and apoptosis generated in tissues by BD during adolescence, such as liver, kidney and heart, improving cardiovascular functioning.

Gene Networks of Hyperglycemia, Diabetic Complications, and Human Proteins Targeted by SARS-CoV-2: What Is the Molecular Basis for Comorbidity?

People with diabetes are more likely to have severe COVID-19 compared to the general population. Moreover, diabetes and COVID-19 demonstrate a certain parallelism in the mechanisms and organ damage. In this work, we applied bioinformatics analysis of associative molecular networks to identify key molecules and pathophysiological processes that determine SARS-CoV-2-induced disorders in patients with diabetes. Using text-mining-based approaches and ANDSystem as a bioinformatics tool, we reconstructed and matched networks related to hyperglycemia, diabetic complications, insulin resistance, and beta cell dysfunction with networks of SARS-CoV-2-targeted proteins. The latter included SARS-CoV-2 entry receptors (ACE2 and DPP4), SARS-CoV-2 entry associated proteases (TMPRSS2, CTSB, and CTSL), and 332 human intracellular proteins interacting with SARS-CoV-2. A number of genes/proteins targeted by SARS-CoV-2 (ACE2, BRD2, COMT, CTSB, CTSL, DNMT1, DPP4, ERP44, F2RL1, GDF15, GPX1, HDAC2, HMOX1, HYOU1, IDE, LOX, NUTF2, PCNT, PLAT, RAB10, RHOA, SCARB1, and SELENOS) were found in the networks of vascular diabetic complications and insulin resistance. According to the Gene Ontology enrichment analysis, the defined molecules are involved in the response to hypoxia, reactive oxygen species metabolism, immune and inflammatory response, regulation of angiogenesis, platelet degranulation, and other processes. The results expand the understanding of the molecular basis of diabetes and COVID-19 comorbidity.

Chokeberry (A. melanocarpa (Michx.) Elliott)—A Natural Product for Metabolic Disorders?

Abnormal metabolism of substances in the body can result in metabolic disorders which include obesity, cardiovascular diseases, diabetes, hypertension, chronic kidney disease, liver disease, or cancer. Foods rich in antioxidants can help to prevent and treat various types of disorders. Chokeberry fruits are rich in polyphenols, especially cyanidins, and therefore, can show a beneficial health effect. The aim of this study was to summarize and systematize reports about the effects of chokeberry on various metabolic parameters. Studies from 2000 to 2021, published in the PubMed and Google Scholar databases, were reviewed. The review of studies shows that chokeberry may have a positive effect in dyslipidemia and hypertension and may increase the body’s antioxidant defense mechanisms. The anti-inflammatory effect, in turn, may translate into a reduction in the risk of metabolic disorders over a longer period of use. Changes in glucose levels were reported by studies in which the intervention lasted more than 10 weeks in patients with carbohydrate metabolism disorders. The effects of protecting the liver, inhibiting platelet aggregation, lowering uric acid levels, and having a protective effect on the kidneys require additional confirmation in human clinical trials. Consumption of chokeberry fruit did not impact on anthropometric measurements; however, it seems that chokeberry fruit can be recommended in many metabolic disorders due to the richness of bioactive ingredients.

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

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

Glutathione Peroxidase GPX1 and Its Dichotomous Roles in Cancer

As the first identified selenoprotein, glutathione peroxidase 1 (GPX1) is a widely and abundantly expressed antioxidant enzyme. GPX1 utilizes glutathione as a substrate to catalyze hydrogen peroxide, lipid peroxide, and peroxynitrite, thereby reducing intracellular oxidative stress. The GPX1 gene is regulated at transcriptional, post-transcriptional, and translational levels. Numerous case-control studies and meta-analyses have assessed the association between a functional genetic polymorphism of the GPX1 gene, named Pro198Leu (rs1050450 C>T), and cancer susceptibility in different populations. GPX1 polymorphism has type-specific effects as a candidate marker for cancer risk, but the association between GPX1 variants and cancer susceptibility remains controversial in different studies. GPX1 is abnormally elevated in most types of cancer but has complex dichotomous roles as tumor suppressor and promoter in different cancers. GPX1 can participate in various signaling pathways to regulate tumor biological behaviors, including cell proliferation, apoptosis, invasion, immune response, and chemoresistance. In this review, we comprehensively summarize the controversial associations between GPX1 polymorphism and cancer risks and further discuss the relationships between the aberrant expressions of GPX1 and tumorigenesis. Further studies are needed to elucidate the clinical significance of GPX1 as a potential prognostic biomarker and novel therapeutic target in various malignancies.

Comparative Proteomic Analysis Reveals the Effect of Selenoprotein W Deficiency on Oligodendrogenesis in Fear Memory

The essential trace element selenium plays an important role in maintaining brain function. Selenoprotein W (SELENOW), the smallest selenoprotein that has been identified in mammals, is sensitive to selenium levels and abundantly expressed in the brain. However, its biological role in the brain remains to be clarified. Here, we studied the morphological and functional changes in the brain caused by SELENOW deficiency using its gene knockout (KO) mouse models. Histomorphological alterations of the amygdala and hippocampus, specifically in the female SELENOW KO mice, were observed, ultimately resulting in less anxiety-like behavior and impaired contextual fear memory. Fear conditioning (FC) provokes rapidly intricate responses involving neuroplasticity and oligodendrogenesis. During this process, the females generally show stronger contextual FC than males. To characterize the effect of SELENOW deletion on FC, specifically in the female mice, a Tandem mass tag (TMT)-based comparative proteomic approach was applied. Notably, compared to the wildtype (WT) no shock (NS) mice, the female SELENOW KO NS mice shared lots of common differentially expressed proteins (DEPs) with the WT FC mice in the hippocampus, enriched in the biological process of ensheathment and oligodendrocyte differentiation. Immunostaining and Western blotting analyses further confirmed the proteomic results. Our work may provide a holistic perspective of gender-specific SELENOW function in the brain and highlighted its role in oligodendrogenesis during fear memory.

Selenium-enriched Polysaccharide: an Effective and Safe Selenium Source of C57 Mice to Improve Growth Performance, Regulate Selenium Deposition, and Promote Antioxidant Capacity

Selenium-enriched polysaccharide (SeEPS) was prepared by reducing Se(IV) to elemental selenium and organic selenium in polysaccharide medium by the obtained Enterobacter cloacae strain Z0206 under aerobic conditions. In the present study, we focused on investigating the role of short-term supplementation of SeEPS at supernutritional doses in the regulation of growth performance, liver damage, antioxidant capacity, and selenium (Se) accumulation in C57 mice. Thirty-two C57 mice were randomly divided into four groups: the control group was gavaged with equal volume of phosphate-buffered saline, while the sodium selenite (Na2SeO3), selenomethionine (SeMet), and SeEPS groups were gavaged with 0.5 mg Se/kg BW of Na2SeO3, SeMet, and selenium-enriched polysaccharide (n = 8), respectively. We examined liver injury indicators, antioxidant capacity in the serum and liver, selenium deposition at different sites, selenoprotein levels, and selenocysteine-synthesizing and degradation-associated gene expression in mouse livers. SeEPS supplementation dramatically increased average daily weight gain but reduced the feed-to-gain ratio (F/G) of mice (P < 0.05). Compared to Na2SeO3 and SeMet supplementation, SeEPS supplementation at supernutritional doses did not cause the liver damage. SeEPS supplementation also markedly enhanced total antioxidant capacity (T-AOC), catalase (CAT), glutathione peroxidase (GSH-PX), and total superoxide dismutase (T-SOD) activities but reduced malondialdehyde (MDA) levels in the liver and serum (P < 0.05), while significantly increasing selenocysteine-synthesizing and degradation-related gene (SEPHS2, SEPSECS, Secisbp, Scly) expression at the mRNA level (P < 0.05), thus upregulating the mRNA levels of selenoproteins (SELENOP, SELENOK) (P < 0.05). We suggest that SeEPS could be a potential replacement for inorganic selenium to improve animals' growth performance, promote antioxidant capacity, and regulate selenium deposition.

EGCG-derived polymeric oxidation products enhance insulin sensitivity in db/db mice

The present study investigated the influence of epigallocatechin-3-gallate (EGCG) and its autoxidation products on insulin sensitivity in db/db mice. Compared to EGCG, autoxidation products of EGCG alleviated diabetic symptoms by suppressing the deleterious renal axis of the renin-angiotensin system (RAS), activating the beneficial hepatic axis of RAS, and downregulating hepatic and renal SELENOP and TXNIP. A molecular weight fraction study demonstrated that polymeric oxidation products were of essential importance. The mechanism of action involved coating polymeric oxidation products on the cell surface to protect against cholesterol loading, which induces abnormal RAS. Moreover, polymeric oxidation products could regulate RAS and SELENOP at doses that were far below cytotoxicity. The proof-of-principal demonstrations of EGCG-derived polymeric oxidation products open a new avenue for discovering highly active polymeric oxidation products based on the oxidation of naturally occurring polyphenols to manage diabetes and other diseases involving abnormal RAS.

•

EGCG autoxidation forms polymeric oxidation products.

•

The polymeric oxidation products are coated on the surface of cells or tissues.

•

The surface coating regulates RAS, SELENOP, and TXNIP in db/db mice.

•

The surface coating increases insulin sensitivity in db/db mice.

Hair Se Is a Sensitive Biomarker to Monitor the Effects of Se Supplementation in Elderly

It is rapidly increasing to have selenium (Se) supplementation for urban elderly population in China since they are facing a widespread deficiency daily Se intake. However, until now, there is no low-cost, non-invasive, rapid, and reliable method to monitor the health improvement or risk for elderly Se-supplemented population in China. The present cross-sectional study (229 participants with older than 55 years old) performed in Beijing, China, revealed that the Se concentrations of non-supplementer users (n = 27) were 55 ± 23 μg/L in urine, 139.9 ± 102.3 μg/L in serum, and 487.6 ± 158.7 μg/kg in hair. But a significant increase on hair Se concentrations (615.4 ± 238.8 μg/kg) was observed for Se supplementer users (n = 202) (p < 0.05); there were no significant statistical differences in serum and urine between the Se-supplemented (n = 202) and Se non-supplemented groups (n = 27). This indicated the hair Se levels could be a more sensitive biomarker for Se-supplemented elderly population. Participants who consumed Se supplements for 7-12 months had the highest Se status based on hair and serum Se concentrations (p < 0.05). The present study also revealed that most elderly adults in Beijing just need to supplement 50 μg Se per day to achieve Se plateau status. Furthermore, hair Se levels were positively related with triglycerides/TG levels (p < 0.05) but not body mass index/BMI, total cholesterol/TC, and low-density lipoprotein cholesterol/LDL, implicating Se supplementation for Se sufficiency baseline in elderly population in Beijing likely posed health risk, especially on TG because of excessive Se oxidation stress. An ongoing monitoring of Se status via hair is still warranted to prevent future Se deficiency or excess in China.

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.

Selenium Deficiency in COVID-19-A Possible Long-Lasting Toxic Relationship

In the last two years, there has been a surge in the number of publications on the trace element selenium (Se) and selenocysteine-containing selenoproteins in human health, largely due to the pandemic and the multiple roles that this micronutrient and Se-dependent selenoproteins play in various aspects of the disease [...].