Effect of selenium supplementation on glutathione peroxidase enzyme activity in patients with chronic kidney disease: a randomized clinical trial

Benefits and risks of essential trace elements in chronic kidney disease: a narrative review

Background and Objective

Chronic kidney disease (CKD) is an important public health concern. With the decline of renal function, CKD patients gradually progress to end-stage kidney disease and need to undergo dialysis or kidney transplantation to maintain life, bringing a heavy economic burden to the family and society. Therefore, it is necessary to effectively prevent and delay the progression of CKD. Essential trace elements play an indispensable role in CKD, and the objective of this study is to systematically review their benefits in the disease and summarize the risks of their excess.

Methods

The keywords "trace elements", "chronic kidney disease", "dialysis", "inflammation", and "fibrosis" and their combinations were used to search for relevant literature published in the PubMed database and Web of Science. We then summarized the role of trace element abnormalities in CKD patients in anemia, oxidative stress, inflammation, and chronic fibrosis, and the risk of their excess.

Key Content and Findings

Imbalance of essential trace elements is a common complication of CKD and a risk factor for CKD progression, cardiovascular events, and death. This article reviews the effects of essential trace elements (iron, zinc, selenium, copper, iodine, and manganese) on CKD. We analyze literature and discuss the advantages and disadvantages of various essential trace elements.

Conclusions

Research shows CKD patients have an imbalance of essential trace elements, and treatment based on these is an important direction for future exploration. A knowledge of the homeostasis of trace elements is important to improving the prognosis of CKD patients and delaying the progression of the disease.

The time pattern of selenomethionine administration in preventing free radicals due to exposure to electric cigarette smoke

BACKGROUND

Most people believe that electric cigarettes have no negative effect on health,  which causes them to use it more. However, exposure to the smoke from these cigarettes is bad for the health and causes cell damage. Antioxidants play an important role in preventing cell damage, and they can be obtained through the oral administration of selenomethionine.

DESIGN AND METHODS

This study used an experimental method and a post-test control group design. Male Wistar rats, which were exposed to cigarette smoke were given selenomethionine orally and then tested for the presence of free radicals. The measurement of lung tissue damage was conducted by assessing the level of malondialdehyde in the blood and immunohistochemistry (IHC) of the lung tissue.

RESULT

The study showed that differences in the time of administration of selenomethionine affect the levels of malondialdehyde in the blood and expression of malondialdehyde in the lung tissue (p<0.05). Consequently, the two groups showed a strong (r=0.861) and significant (p=0.000) relationship with each other.

CONCLUSION

The early application of selenomethionine can prevent increased levels of malondialdehyde in the blood and lung tissue due to exposure to e-cigarette smoke.

Renal changes and apoptosis caused by subacute exposure to Aroclor 1254 in selenium-deficient and selenium-supplemented rats

Aroclor 1254 (A1254), a mixture of polychlorinated biphenyls, exerts hepatic, renal, and reproductive toxicity in rodents. This study aimed to determine a protective role of selenium on histopathological changes, oxidative stress, and apoptosis caused by A1254 in rat kidney. It included a control group, which received regular diet containing 0.15 mg/kg Se (C), a Se-supplemented group (SeS) receiving 1 mg/kg Se, a Se-deficient group (SeD) receiving Se-deficient diet of ≤0.05 mg/kg Se, an A1254-treated group (A) receiving 10 mg/kg of Aroclor 1254 and regular diet, an A1254-treated group receiving Se-supplementation (ASeS), and an A1254-treated group receiving Se-deficient diet (ASeD). Treatments lasted 15 days. After 24 h of the last dose of A1254, the animals were decapitated under anaesthesia and their renal antioxidant enzyme activities, lipid peroxidation (LP), glutathione, protein oxidation, and total antioxidant capacity levels measured. Histopathological changes were evaluated by light and electron microscopy. Apoptosis was detected with the TUNEL assay. Kidney weights, CAT activities, and GSH levels decreased significantly in all A1254-treated groups. Renal atrophic changes and higher apoptotic cell counts were observed in the A and ASeD groups. Both groups also showed a significant drop in GPx1 activities (A – 34.92 % and ASeD – 86.46 %) and rise in LP (A – 30.45 % and ASeD – 20.44 %) vs control. In contrast, LP levels and apoptotic cell counts were significantly lower in the ASeS group vs the A group. Histopathological changes and renal apoptosis were particularly visible in the ASeD group. Our findings suggest that selenium supplementation provides partial protection against renal toxicity of Aroclor 1254.

The Role of Selenium in Oxidative Stress and in Nonthyroidal Illness Syndrome (NTIS): An Overview

Selenium is a trace element, nutritionally classified as an essential micronutrient, involved in maintaining the correct function of several enzymes incorporating the selenocysteine residue, namely the selenoproteins. The human selenoproteome including 25 proteins is extensively described here. The most relevant selenoproteins, including glutathione peroxidases, thioredoxin reductases and iodothyronine deiodinases are required for the proper cellular redox homeostasis as well as for the correct thyroid function, thus preventing oxidative stress and related diseases. This review summarizes the main advances on oxidative stress with a focus on selenium metabolism and transport. Moreover, thyroid-related disorders are discussed, considering that the thyroid gland contains the highest selenium amount per gram of tissue, also for future possible therapeutic implication.

Glutathione is Involved in Detoxification of Peroxide and Root Nodule Symbiosis of Mesorhizobium huakuii

Legumes interact with symbiotic rhizobia to produce nitrogen-fixation root nodules under nitrogen-limiting conditions. The contribution of glutathione (GSH) to this symbiosis and anti-oxidative damage was investigated using the M. huakuii gshB (encoding GSH synthetase) mutant. The gshB mutant grew poorly with different monosaccharides, including glucose, sucrose, fructose, maltose, or mannitol, as sole sources of carbon. The antioxidative capacity of gshB mutant was significantly decreased by these treatments with H₂O₂ under the lower concentrations and cumene hydroperoxide (CUOOH) under the higher concentrations, indicating that GSH plays different roles in response to organic peroxide and inorganic peroxide. The gshB mutant strain displayed no difference in catalase activity, but significantly lower levels of the peroxidase activity and the glutathione reductase activity than the wild type. The same level of catalase activity could be associated with upregulation of the transcriptional activity of the catalase genes under H₂O₂-induced conditions. The nodules infected by the gshB mutant were severely impaired in abnormal nodules, and showed a nodulation phenotype coupled to a 60% reduction in the nitrogen fixation capacity. A 20-fold decrease in the expression of two nitrogenase genes, nifH and nifD, is observed in the nodules induced by gshB mutant strain. The symbiotic deficiencies were linked to bacteroid early senescence.

Impact of Supplementary Amino Acids, Micronutrients, and Overall Diet on Glutathione Homeostasis

Glutathione (GSH) is a critical endogenous antioxidant found in all eukaryotic cells. Higher GSH concentrations protect against cellular damage, tissue degeneration, and disease progression in various models, so there is considerable interest in developing interventions that augment GSH biosynthesis. Oral GSH supplementation is not the most efficient option due to the enzymatic degradation of ingested GSH within the intestine by γ-glutamyltransferase, but supplementation of its component amino acids-cysteine, glycine, and glutamate-enhances tissue GSH synthesis. Furthermore, supplementation with some non-precursor amino acids and micronutrients appears to influence the redox status of GSH and related antioxidants, such as vitamins C and E, lowering systemic oxidative stress and slowing the rate of tissue deterioration. In this review, the effects of oral supplementation of amino acids and micronutrients on GSH metabolism are evaluated. And since specific dietary patterns and diets are being prescribed as first-line therapeutics for conditions such as hypertension and diabetes, the impact of overall diets on GSH homeostasis is also assessed.

Bioaccessible selenium sourced from Se-rich mustard cake facilitates protection from TBHP induced cytotoxicity in melanoma cells

Selenium (Se) is an essential dietary supplement that resolves inflammatory responses and offers antioxidant cytoprotection. In this study, we present the data on the cytoprotective effect of Se-rich mustard protein isolated from mustard cultivated in seleniferous soils in Punjab, India. The concentrations of total Se in mustard seed, oil-free mustard cake, and mustard protein were 110.0 ± 3.04, 143.0 ± 5.18, and 582.3 ± 6.23 μg g-1, respectively. The cytoprotective effect of Se-rich mustard protein was studied on tert-butyl hydroperoxide (TBHP)-induced cytotoxicity in a mouse melanoma cell line (B16-F10). When compared with TBHP treated cells (where no viable cells were found), Se-rich protein made bioaccessible through simulated gastrointestinal digestion protected melanoma cells from cytotoxicity with decreased levels of oxidative stress resulting in 73% cell viability. Such an effect was associated with a significant increase in glutathione peroxidase activity as a function of bioaccessible Se and its response towards cytoprotection.

Naturally Occurring Compounds: New Potential Weapons against Oxidative Stress in Chronic Kidney Disease

Oxidative stress is a well-described imbalance between the production of reactive oxygen species (ROS) and the antioxidant defense system of cells and tissues. The overproduction of free radicals damages all components of the cell (proteins, lipids, nucleic acids) and modifies their physiological functions. As widely described, this condition is a biochemical hallmark of chronic kidney disease (CKD) and may dramatically influence the progression of renal impairment and the onset/development of major systemic comorbidities including cardiovascular diseases. This state is exacerbated by exposure of the body to uremic toxins and dialysis, a treatment that, although necessary to ensure patients' survival, exposes cells to non-physiological contact with extracorporeal circuits and membranes with consequent mitochondrial and anti-redox cellular system alterations. Therefore, it is undeniable that counteracting oxidative stress machinery is a major pharmacological target in medicine/nephrology. As a consequence, in recent years several new naturally occurring compounds, administered alone or integrated with classical therapies and an appropriate lifestyle, have been proposed as therapeutic tools for CKD patients. In this paper, we reviewed the recent literature regarding the "pioneering" in vivo testing of these agents and their inclusion in small clinical trials performed in patients affected by CKD.

Evaluation of selenium on kidney function following ischemic injury in rats; protective effects and antioxidant activity

Introduction: Renal dysfunction is caused by ischemia-reperfusion (I/R) injury, which is a common problem in kidney surgery or kidney transplantation. The human body consists of enormous complex antioxidant systems, which inquires adequate selenium (Se) absorption for normal physiologic function. It is known that Se has some antioxidant effects. Objectives: In the present research, effects of the Se on damages caused by I/R injury investigated. Materials and Methods: In this experimental research, four groups of rats (weighing 220±10 g) used, include control group, I/R group, healthy group treated with Se for two weeks, and I/R group with two-week Se treatment. On the test day, I/R was treated in both right and left renal arteries for 45 minutes and the reperfusion was done for 24 hours. Results: In I/R group, the amount of urea and serum creatinine (Cr) was an injury indicator of the kidney cells which showed a significant increase compared with the control group. When the treatment with Se significantly reduced these indicators, glutathione (GSH) enzyme levels reduced significantly in the second group and the enzyme levels increased due to Se treatment in the fourth group. Furthermore, malondialdehyde (MDA) enzyme levels increased in I/R group due to the Se treatment in the fourth group which was significantly reduced. In addition, the tissue damage was reduced in the fourth group compared with I/R group. Conclusion: Se has a protective effect against the I/R injury. This effect might be due to the antioxidant properties of Se.

The effect of selenium supplementation on acute phase reactants and thyroid function tests in hemodialysis patients

BACKGROUND

Selenium deficiency is a common problem in patients with chronic kidney disease (CKD). This micronutrient has anti-inflammatory and anti-oxidant effects. Selenium is also found in high concentrations in the thyroid gland.

OBJECTIVES

To determine the effect of selenium supplementation on thyroid function tests and acute phase reactants in hemodialysis patients.

PATIENTS AND METHODS

In this double-blinded randomized clinical in 3 months, 64 hemodialysis patients with selenium deficiency were divided into experimental (received selenium supplementation; 32 cases) or control group (received placebo; 32 cases). Erythrocyte sedimentation rate (ESR), ferritin, quantitative C-reactive protein (CRP) and thyroid function tests (TFTs) including thyroid stimulating hormone (TSH), T3 resin uptake (T3RU), and free T4 were measured before and after the intervention and compared between experimental and control groups.

RESULTS

At baseline, no significant difference was found between experimental and control groups regarding CRP, ESR and ferritin serum levels. Likewise, after intervention, no significant difference was found between experimental and control groups for CRP (14.77 ± 17.93 vs. 18.29 ± 21.56 mg/L), ESR (32.90 ± 32.62 vs. 33.91 ± 31.15 mm/h) and ferritin (528.6 ± 423.07 vs. 519.52 ± 345.59 ng/mL). At baseline, no significant difference was found between experimental and control groups regarding TFTs. Likewise, after intervention, no significant difference was found between experimental and control groups for TSH (3.7 ± 2.22 vs. 2.84 ± 1.88 µU/mL), free T4 (7.19 ± 1.98 vs. 7.02 ± 1.87 µg/dL) and T3RU (30.04 ± 2.28% vs. 29.2 ± 1.98%).

CONCLUSIONS

Oral selenium supplementation for three months did not have any significant effect on thyroid function tests or acute phase reactants.

Selenium and selenium-dependent antioxidants in chronic kidney disease

Oxidative stress plays a key role in numerous disease processes including chronic kidney disease (CKD). In general, oxygen metabolism leads to the formation of reactive oxygen species (ROS) dangerous to cells. Although enzymes and low-molecular-weight antioxidants protect against ROS, chronic imbalances of formation and elimination can eventually overwhelm endogenous defenses leading to deleterious consequences. In CKD, glutathione peroxidases (GSH-Px) play an important role in ROS metabolism. Plasma GSH-Px is synthesized in the kidney and requires selenium (Se) as a cofactor. Interestingly, Se and plasma GSH-Px are both significantly reduced in CKD, especially for those patients on hemodialysis. Supplementation of Se in these patients results in modest increases of GSH-Px, presumably from residual renal tissue. Kidney transplantation rapidly restores plasma GSH-Px. In this chapter, the relevance of these findings to CKD is explored with emphasis on renal disease processes and impact on attendant disorders including cancer and cardiovascular disease.

Association between plasma selenium and glutathione peroxidase levels and severity of diabetic nephropathy in patients with type two diabetes mellitus

Background:

Oxidative stress is thought to be involved in the pathogenesis of diabetic nephropathy. Selenium (Se), and antioxidant enzymes such as glutathione peroxidase (GPx) play an important protective role in diabetes complications.

Objectives:

This study aimed to evaluate the association between plasma Se and GPx levels with severity of diabetic nephropathy.

Patients and Methods:

In a case-control study, we measured plasma Se and GPx concentrations in patients with type two diabetes without microalbuminuria (group 1), with microalbuminuria (group 2), with macroalbuminuria (group 3), and healthy control subjects (group 4). We also assessed plasma glucose, urea, creatinine, and glycated hemoglobin levels in all study patients.

Results:

Plasma Se and GPx concentrations were significantly lower in diabetic patients with macroalbuminuria than other study groups (P < 0.001). Albuminuria (Alb/Cr in random urine sample) had a negative correlation with plasma Se (r = -0.40, P = 0.01), and GPx (r = -0.23, P = 0.03) concentrations.

Conclusions:

Plasma Se and GPx levels were lower in type two diabetic patients with macroalbuminuria and related to the stage of diabetic nephropathy.