The effect of Na-selenite treatment on the oxidative stress-antioxidants balance of multiple organ failure

The effect of selenium therapy in critically ill patients: an umbrella review of systematic reviews and meta-analysis of randomized controlled trials

BACKGROUND

Selenium is an essential nutrient with antioxidant, anti-inflammatory, and immuno-regulatory properties. Studies have displayed that in critically ill patients, selenium supplementation may be a potentially promising adjunctive therapy.

OBJECTIVE

We aimed to present an overview of the effects of selenium supplementation in adult critically ill patients based on published systematic reviews and meta-analyses (SRMAs) of randomized controlled trials (RCTs).

METHODS

A literature search in three electronic databases, PubMed, Scopus, and Web of Science, was performed to find eligible SRMAs until July 2022. For each outcome, the risk ratios (RRs) or mean differences (MDs) and 95% confidence intervals (CIs) were recalculated using either random or fixed effect models. The methodological quality and quality of evidence of the SRMAs were assessed by applying "A Measurement Tool to Assess Systematic Reviews" (AMSTAR2) and Grading of Recommendations Assessment, Development, and Evaluation(GRADE) tools, respectively.

RESULTS

We included 17 meta-analyses containing 24 RCTs based on inclusion criteria. Selenium supplementation can reduce the incidence of mortality (RR: 0.83, 95% CI 0.71, 0.98, P = 0.024) and incidence of acute renal failure (RR: 0.67, 95% CI 0.46, 0.98, P: 0.038) significantly; however, the certainty of evidence was low. Moreover, with moderate to very low certainty of evidence, no significant effects were found for risk of infection (RR: 0.92, 95% CI 0.80, 1.05, P: 0.207), pneumonia (RR: 1.11, 95% CI 0.72, 1.72, P: 0.675), as well as the length of ICU (MD: 0.15, 95% CI - 1.75, 2.05, P: 0.876) and hospital stay (MD: - 0.51, 95% CI - 3.74, 2.72, P: 0.757) and days on ventilation (MD: - 0.98, 95% CI - 2.93, 0.98, P: 0.329).

CONCLUSIONS

With low quality of evidence, the use of selenium supplementation could improve the risk of mortality and acute renal failure, but not other outcomes in critically ill patients.

Potential Antioxidant Multitherapy against Complications Occurring in Sepsis

Septic shock currently represents one of the main causes of mortality in critical patient units with an increase in its incidence in recent years, and it is also associated with a high burden of morbidity in surviving patients. Within the pathogenesis of sepsis, oxidative stress plays an important role. The excessive formation of reactive oxygen species (ROS) leads to mitochondrial damage and vasomotor dysfunction that characterizes those patients who fall into septic shock. Currently, despite numerous studies carried out in patients with septic shock of different causes, effective therapies have not yet been developed to reduce the morbidity and mortality associated with this pathology. Despite the contribution of ROS in the pathophysiology of sepsis and septic shock, most studies performed in humans, with antioxidant monotherapies, have not resulted in promising data. Nevertheless, some interventions with compounds such as ascorbate, N-acetylcysteine, and selenium would have a positive effect in reducing the morbidity and mortality associated with this pathology. However, more studies are required to demonstrate the efficacy of these therapies. Taking into account the multifactorial features of the pathophysiology of sepsis, we put forward the hypothesis that a supplementation based on the association of more than one antioxidant compound should result in a synergistic or additive effect, thus improving the beneficial effects of each of them alone, potentially serving as a pharmacological adjunct resource to standard therapy to reduce sepsis complications. Therefore, in this review, it is proposed that the use of combined antioxidant therapies could lead to a better clinical outcome of patients with sepsis or septic shock, given the relevance of oxidative stress in the pathogenesis of this multi-organ dysfunction.

The effects of selenium supplementation on inflammatory markers in critically ill patients

Abstract

Low serum selenium (Se) levels have been shown in critical illness, which is associated with poor clinical outcomes and a higher mortality rate. Se plays an important role in inflammation and oxidative stress. Since the overproduction of inflammatory cytokines and increased oxidative stress is a major component of critical illnesses, its supplementation has been demonstrated to have promising effects on critically ill patients. This study aims to review the evidence regarding the effects of Se supplementation on inflammatory and oxidative markers in critically ill patients. The literature review highlights alterations of inflammatory markers, including procalcitonin, leukocyte count, albumin, prealbumin, C-reactive protein (CRP), inflammatory cytokines, and cholesterol following Se supplementation in critically ill patients. Besides, the antioxidant properties of Se due to its presence in the structure of several selenoenzymes have been reported.

Article highlights

Low serum Se level have been shown in critical illness, which is associated with poor clinical outcome and higher mortality rate.

Se plays an important role in inflammation and oxidative stress.

Se supplementation can have promising effects by alterations of inflammatory markers and its antioxidant properties for critically ill patients.

Daily parenteral selenium therapy in critically ill patients: An updated systematic review and meta-analysis of randomized controlled trials

BACKGROUND AND AIM

Patients hospitalized at the intensive care unit (ICU) are more prone to oxidative stress. Antioxidants such as selenium (Se) may have beneficial effects on outcomes in these patients. Studies and systematic reviews in this field have inconclusive results.

METHODS

An updated systematic search was done to find clinical trials published in PubMed, Cochrane's library, ISI web of Science, Scopus, and Ovid databases from January 1980 up to April 2020, to assess the effects of daily Se supplementation on patient's survival, hospital and ICU stay, duration of mechanical ventilation, infection, acute renal failure (ARF) occurrence and serum creatinine levels.

RESULTS

From 1394 papers found in the first step of the search, after deleting duplicate findings, 24 studies were included in this meta-analysis. Results of the pooled random-effect size analysis of 24 trials showed no remarkable effect of daily parenteral Se administration on patient's hospital and ICU stay, duration of mechanical ventilation, infectious complications, ARF, survival and serum creatinine levels (p > 0.05). The subgroup analysis showed that daily parenteral Se administration (in doses higher than 1000 μg/d) increased the length of ICU stay by 4.48-folds (95%CI: -0.5, 9.46, p = 0.07). Parenteral Se supplementation at the first and following dose of ≤1000 μg reduced the number of ARF at the hospitalized patients by 76% and 45%, respectively (p = 0.02, and p = 0.05).

CONCLUSIONS

High doses of Se increases days of ICU stay, but low doses decreases the number of ARF occurrence in ICU patients. More trials are needed to assess its effect on ARF occurrence.

Oral intake of α‑glucosyl‑hesperidin ameliorates selenite‑induced cataract formation

Hesperetin is a natural flavonoid with robust antioxidant properties. Our previous study reported that hesperetin can prevent cataract formation. However, an important consideration regarding hesperetin consumption is the limited bioavailability due to its poor solubility. The present study investigated the anti‑cataract effects of α‑glucosyl hesperidin in vivo and in vitro using a selenite‑induced cataract model. SD rats (age, 13 days) were orally administered PBS (0.2 ml) or α‑glucosyl hesperidin (200 mg/kg) on days 0, 1 and 2. Sodium selenite was subcutaneously administered to the rats 4 h after the first oral administration on day 0. Antioxidant levels in the lens and blood were measured on day 6. In vitro, human lens epithelial cells were treated with sodium selenite (10 µM) and/or hesperetin (50 or 100 mM) for 24 h and analyzed for apoptosis markers using sub‑G1 population and Annexin V‑FITC/propidium iodide staining and DNA ladder formation. α‑glucosyl hesperidin treatment significantly reduced the severity of selenite‑induced cataract. The level of antioxidants was significantly reduced in the selenite‑treated rats compared with in the controls; however, they were normalized with α‑glucosyl hesperidin treatment. In vitro, hesperetin could significantly reduce the number of cells undergoing apoptosis induced by sodium selenite in human lens epithelial cell lines. Overall, oral consumption of α‑glucosyl hesperidin could delay the onset of selenite‑induced cataract, at least in part by modulating the selenite‑induced cell death in lens epithelial cells.

Selenium and hydrogen selenide: essential micronutrient and the fourth gasotransmitter?

Selenium (Se) is an essential micronutrient required by organisms of diverse lineage. Dietary Se is converted to hydrogen selenide either enzymatically or by endogenous antioxidant proteins. This convergent biochemical step crucially underlies the subsequent biological activity of Se and argues for inclusion of hydrogen selenide as the fourth endogenous gasotransmitter alongside nitric oxide, carbon monoxide and hydrogen sulfide.Endogenously generated hydrogen selenide is incorporated into numerous 'selenoprotein' oxidoreductase enzymes, essential for maintaining redox-status homeostasis in health and disease. Direct effects of endogenous hydrogen selenide on cellular and molecular targets are currently unknown. Given exogenously, hydrogen selenide acts as a modulator of metabolism via transient inhibition of mitochondrial cytochrome C oxidase. Here we provide an overview of Se biology, its impact on several physiological systems (immune, endocrine, cardiovascular and metabolic) and its utility as a supplement in acute and critical illness states. We further explore the evidence base supporting its role as the fourth gasotransmitter and propose a strategic case towards generation of novel selenomimetic therapeutics.

The clinical outcomes of selenium supplementation on critically ill patients: A meta-analysis of randomized controlled trials

PURPOSE

Selenium supplementation is a potentially promising adjunctive therapy for critically ill patients, but the results are controversy among studies. Accordingly, we performed this meta-analysis to more clearly detect the efficacy and safety of selenium supplementation on critically ill patients.

METHODS

Systematic literature retrieval was carried out to obtain RCTs on selenium supplementation for critically ill patients up to August 2017. Data extraction and quality evaluation of these studies were performed by 2 investigators. Statistical analyses was performed by RevMan 5.3. Trial sequential analysis (TSA) was conducted to control the risks of type I and type II errors and calculate required information size (RIS).

RESULTS

Totally 19 RCTs involving 3341 critically ill patients were carried out in which 1694 participates were in the selenium supplementation group, and 1647 in the control. The aggregated results suggested that compared with the control, intravenous selenium supplement as a single therapy could decrease the total mortality (RR = 0.86, 95% CI: 0.78-0.95, P = .002, TSA-adjusted 95% CI = 0.77-0.96, RIS = 4108, n = 3297) and may shorten the length of stay in hospital (MD -2.30, 95% CI -4.03 to -0.57, P = .009), but had no significant treatment effect on 28-days mortality (RR = 0.96, 95% CI: 0.85-1.09, P = .54) and could not shorten the length of ICU stay (MD -0.15, 95% CI -1.68 to 1.38, P = .84) in critically ill patients. Our results also showed that selenium supplementation did not increase incidence of drug-induced side effect compared with the control (RR 1.04, 95% CI 0.83 to 1.30, P = .73).

CONCLUSIONS

The current evidence suggests that the use of selenium could reduce the total mortality, and TSA results showed that our outcome is reliable and no more randomized controlled trials are needed. But selenium supplementation might have no effect on reducing 28-days mortality as well as the incidence of new infections, or on length of stay in ICU or mechanical ventilation. However, the results should be used carefully because of potential limitations.

A meta-analysis of randomized controlled trials: Efficacy of selenium treatment for sepsis

BACKGROUND

To understand the clinical outcomes of selenium therapy in patients with sepsis syndrome, we conducted a meta-analysis of randomized controlled trials (RCT).

METHODS

A total of 13 RCTs comparing selenium and placebo for patients with sepsis were reviewed systematically.

RESULTS

However, we could not detect the association of selenium treatment with a decreased mortality at different time course (relative risk [RR] [95% confidence interval, CI]: 0.94 [0.82-1.06] at day 28; 0.73 [0.36-1.47] at day 90; 1.16 [0.78-1.71] at 6 months; respectively). Selenium supplementation did not show favorable efficacy in the incidence of renal failure, secondary infection or duration of mechanical ventilation (RR [95% CI]: 0.65 [0.41-1.03]; 0.96 [0.87-1.06]; standard mean difference [SMD] [95% CI]: 0.17 [-0.30-0.63]; respectively). Interestingly, we found that selenium therapy was benefit for sepsis patients with reduced duration of vasopressor therapy, staying time in intensive care unit and hospital, and incidence of ventilator-associated pneumonia (SMD [95% CI]: -0.75 [-1.37 to -0.13]; -0.15 [CI: -0.25 to -0.04]; -1.22 [-2.44 to -0.01]; RR [95% CI]: 0.61 [0.42-0.89]; respectively).

CONCLUSION

Based on our findings, intravenous selenium supplementation could not be suggested for routine use.

Weaning from veno-venous extracorporeal membrane oxygenation: how I do it

Veno-venous extracorporeal membrane oxygenation (VV ECMO) is a rescue treatment for acute respiratory distress syndrome (ARDS) failing protective mechanical ventilation. It temporarily provides proper gas exchange: hypoxia is treated by adjusting the blood flow rate and fraction in spired oxygen over the ventilator (FiO2) on the extracorporeal membrane oxygenation (ECMO) circuit while CO2 removal is regulated by the ECMO fresh gas flow. Therefore, ventilator settings can be gradually reduced allowing the lungs to rest and recover. Nowadays, indications for ECMO referral and implantation are clearly formulated; on the contrary, little evidence currently exists to guide the process of weaning from ECMO support, especially concerning the timing during the course of lung healing. Therefore, indications to stop ECMO are less well standardized so that in clinical trials extracorporeal assistance is generally continued until lung recovery, with neither specific nor homogenous criteria for withdrawal. Notably, in almost all papers dealing with data on VV ECMO support, the management of weaning and the weaning procedure itself are not described. The aim of this paper is to make a picture of VV ECMO weaning, as it is performed in three European large volume intensive care units (ICUs) which represent referral centers for VV ECMO treatment. We focused on data concerning the timing of VV ECMO weaning and parameters at the time of weaning, in order to assess adequacy and safety of VV ECMO removal.

Antioxidant reserve of the lungs and ventilator-associated pneumonia: A clinical trial of high dose selenium in critically ill patients

PURPOSE

To evaluate the effect of supplemental selenium administration on the incidence of ventilator-associated pneumonia (VAP) in critically ill patients.

METHODS

Ninety-nine mechanically ventilated patients were randomized to receive either selenium or isotonic saline infusion for 10days. The primary endpoint was serum glutathione peroxidase-3 (GPX-3) activity and secondary endpoints were development of VAP or death, ICU stay and vasopressor requirement. Serum concentrations of selenium and GPX-3 were measured on Day-1, Day-4 and Day-10. Chi Square and log-rank analyses were used for statistical analyses and odds ratios were calculated.

RESULTS

Serum selenium and GPX-3 activity levels increased steadily in the treatment group within 10days (P<0.025), while they remained unchanged in the placebo group. The incidence of VAP was 19.4/1000days of mechanical ventilation in the placebo group while it was 15.8/1000 ventilated days in the treatment group (P=0.250). The risk of VAP or death was similar between the treatments and placebo groups.

CONCLUSION

Despite increasing the antioxidant activity, selenium supplementation did not affect the incidence of VAP in critically ill patients. The risk of developing VAP or death within 30days of ICU admission remained the same in the treatment and the controls.

Comparison of glutathione peroxidase-3 protein expression and enzyme bioactivity in normal subjects and patients with sepsis

BACKGROUND

Serum glutathione peroxidase-3 (GPx-3) is known as a key selenoprotein with antioxidant properties. GPx-3 deficiency has been associated with sepsis. The objectives of this study are (1) to compare the GPx-3 protein concentrations and GPx-3 bioactivity in normal healthy subjects and septic patients, and (2) to evaluate the relationship between GPx-3 bioactivity and its protein concentration.

METHODS

Serum samples were collected from 50 normal healthy subjects and 70 septic patients. The reliable bioanalytical methods for GPx-3 protein concentration and bioactivity in human serum were developed and validated. Analyses of GPx-3 bioactivity and GPx-3 protein concentration were then performed.

RESULTS

Geometric mean GPx-3 bioactivity was 78.13U/l for patients with sepsis, significantly lower than normal subjects with 108.21U/l (p<0.0001). Similarly, the GPx-3 protein concentration was significantly lower in patients with sepsis than in normal subjects, with the mean GPx-3 value of 0.78 vs 3.10μg/ml, respectively (p<0.0001). A positive correlation was observed between the GPx-3 bioactivity and its corresponding protein concentration in septic serum samples (R=0.74, p<0.0001), regardless of gender or age difference.

CONCLUSION

These findings suggest that the decrease in GPx-3 bioactivity observed in the septic patients was resulted from the significant sepsis-related decline of GPx-3 protein concentrations.

Influence of selenium supplementation on patients with inflammation: A pilot double blind randomized study

OBJECTIVE

The aim of the study was to analyze the effect of selenium supplementation on patients with inflammation receiving PN.

METHODS

This double-blind randomized study included 20 hospitalized patients experiencing an inflammatory process while being fed by PN, who were monitored in three stages: first 72 h (0), day 7 (1), and day 14 (2) of PN. The supplemented patients group (G+S) received 60 μg/d (0.75 μmol) of selenium as selenious acid which was added to the PN bag. The nonsupplemented group (G-S) did not receive selenium. The concentration range of 84 to 100 μg/L (1.07-1.27 μmol/L) was used as a reference of plasma selenium.

RESULTS

The study included 20 patients (8 G+S and 12 G-S) mainly diagnosed with cancer and/or sepsis. Most of them were hospitalized in the intensive care unit and were receiving PN for clinical reasons. Plasma selenium was greater in the G+S than in the G-S (P = 0.05) in two stages (0 and 1). Since the start of assessment, C-reactive protein (CRP) levels were elevated; however, there was no statistical difference in CRP values between groups (P > 0.05). There was no significant change of glutathione peroxidase over time or between groups (P > 0.05).

CONCLUSION

The selenium concentration was greater in the G+S than in the G-S, acting independently from CRP behavior. However, supplementation was not enough to reach the reference values.

Role of divalent metals in infectious disease susceptibility and outcome

BACKGROUND

Divalent metals play important roles in maintaining metabolism and cellular growth of both eukaryotic hosts and invading microbes. Both metal deficiency and overload can result in abnormal cellular function or damage. Given its central role in host-pathogen interactions, subtle alterations of divalent metal homeostasis can occur in the course of infectious diseases which aim, from the host perspective, either to reduce the availability of respective metals to microbes or to use toxic metal accumulation to eliminate pathogens.

AIMS

To provide the reader with background information and clinical data on divalent metal homeostasis in host-pathogen interactions, how this affects the course of infectious disease and whether correction of metal disturbances has shown benefit in infections.

SOURCES

An in-depth analysis of PubMed articles related to the topic of this review published in English between 1970 and 2016 was performed.

CONTENT

From the microbial perspective, divalent metals are essential for growth and pathogenicity and to mount effective protection against antimicrobial host responses, including toxic radical formation. Microbes have evolved multiple strategies to control their access to divalent metals. From the clinical perspective, alterations of divalent metal levels may result in increased or decreased susceptibility to infection and often occur in response to infections. However, keeping in mind the strategies underlying such alterations, for which the term 'nutritional immunity' was coined, the uncritical correction of such divalent metal imbalances may cause harm to patients. This review addresses the role of the divalent metals iron, selenium, zinc, manganese and copper in infectious diseases from a mechanistic and clinical perspective.

IMPLICATIONS

We point out areas of research needed to expand our limited knowledge, hoping to improve the clinical management of patients with infections and to identify promising new targets for treatment by modulation of host or microbe divalent metal metabolism.

High-dose intravenous selenium does not improve clinical outcomes in the critically ill: a systematic review and meta-analysis

Background

Selenium (Se) is an essential trace element with antioxidant, anti-inflammatory, and immunomodulatory effects. So far, several randomized clinical trials (RCTs) have demonstrated that parenteral Se may improve clinical outcomes in intensive care unit (ICU) patients. Since publication of our previous systematic review and meta-analysis on antioxidants in the ICU, reports of several trials have been published, including the largest RCT on Se therapy. The purpose of the present systematic review was to update our previous data on intravenous (IV) Se in the critically ill.

Methods

We searched MEDLINE, Embase, and the Cochrane Central Register of Controlled Trials. We included RCTs with parallel groups comparing parenteral Se as single or combined therapy with placebo. Potential trials were evaluated according to specific eligibility criteria, and two reviewers abstracted data from original trials in duplicate independently. Overall mortality was the primary outcome; secondary outcomes were infections, ICU length of stay (LOS), hospital LOS, ventilator days, and new renal dysfunction.

Results

A total of 21 RCTs met our inclusion criteria. When the data from these trials were aggregated, IV Se had no effect on mortality (risk ratio [RR] 0.98, 95 % CI 0.90–1.08, P = 0.72, heterogeneity I² = 0 %). In addition, when the results of ten trials in which researchers reported on infections were statistically aggregated, there was no significant treatment effect of parenteral Se (RR 0.95, 95 % CI 0.88–1.02, P = 0.15, I² = 0 %). There was no positive or negative effect of Se therapy on ICU and hospital LOS, renal function, or ventilator days.

Conclusions

In critically ill patients, IV Se as monotherapy does not improve clinical outcomes.

Electronic supplementary material

The online version of this article (doi:10.1186/s13054-016-1529-5) contains supplementary material, which is available to authorized users.

Reduced endogenous urinary total antioxidant power and its relation of plasma antioxidant activity of superoxide dismutase in individuals with autism spectrum disorder

Individuals with autism spectrum disorders (ASD) have impaired detoxification capacity. Investigating　the neurobiological bases of　impaired antioxidant capacity is thus a research priority in the pathophysiology of ASD.　We measured　the urinary levels of hexanoyl-lysine (HEL) which is a new oxidative stress　biomarker, total antioxidant power (TAP) and DNA methylation biomarker 8-hydroxy-2'-deoxyguanosine (8-OHdG), and the plasma levels of superoxide dismutase (SOD), which is a major antioxidant enzyme. We examined whether the urinary levels of these enzymes and biomarkers may be related to symptoms of social impairment in 20 individuals with ASD (meanage,11.1±5.2years) and 12 age- and gender-matched healthy controls (meanage,14.3±6.2years). Symptoms of social impairment were　assessed using the Social Responsiveness Scale (SRS). The dietary TAP of the fruit juice, chocolate, cookies, biscuits, jam and marmalade were significantly higher in the ASD group than in the control group, although the intake of nutrients was not significantly different between the groups. The urinary TAP levels were significantly lower in the ASD group than in the control group. There were no significantly differences in urinary HEL and 8-OHdG levels between the ASD and control groups. The SRS scores were significantly higher in the ASD group than in the control group. Stepwise regression analysis revealed that urinary TAP levels and plasma SOD levels can differences in the biomarkers and the SRS scores between the ASD group and the control group. The endogenous antioxidant capacity may be deficient without altered urinary HEL and 8-OHdG levels in individuals with ASD. The plasma SOD levels may be related to reduced endogenous antioxidant capacity.