Systemic oxidative stress in children with cystic fibrosis with bacterial infection including Pseudomonas Aeruginosa

Introduction

Oxidative stress (OS) occurs in cystic fibrosis (CF).

Objective

The objective of this work is to evaluate the influence of bacterial infection on biomarkers of OS (catalase [CAT], glutathione peroxidade [GPx], reduced glutathione [GSH]), markers of oxidative damage (protein carbonyls [PC], thiobarbituric acid reactive substances [TBARS]), together with the nutritional status and lung function in children with CF.

Methods

Cross‐sectional study including CF group (CFG, n = 55) and control group (CG, n = 31), median age: 3.89 and 4.62 years, respectively. CFG was distributed into CFG negative bacteriology (CFGB−, n = 27) or CFG positive bacteriology (CFGB+, n = 28), and CFG negative Pseudomonas aeruginosa (CFGPa−, n = 36) or CFG positive Pseudomonas aeruginosa (CFGPa+, n = 19).

Results

Compared with CG, CFG (P = .034) and CFGB+ (P = .042) had lower body mass index‐for‐age z‐score; forced expiratory volume in the first second was lower in CFGB+ and CFGPa+ (both P < .001). After adjusting for confounders and compared with CG: CFG showed higher TBARS (P ≤ .001) and PC (P = .048), and lower CAT (P = .004) and GPx (P = .003); the increase in PC levels was observed in CFGB+ (P = .011) and CFGPa+ (P = .001) but not in CFGB− (P = .510) and CFGPa− (P = .460).

Conclusions

These results indicate a systemic OS in children with CF. The presence of bacterial infection particularly Pseudomonas aeruginosa seems to be determinant to exacerbate the oxidative damage to proteins, in which PC may be a useful biomarker of OS in CF.

Antioxidant supplementation for lung disease in cystic fibrosis

BACKGROUND

Airway infection leads to progressive damage of the lungs in cystic fibrosis (CF) and oxidative stress has been implicated in the etiology. Supplementation of antioxidant micronutrients (vitamin E, vitamin C, beta-carotene and selenium) or N-acetylcysteine (NAC) as a source of glutathione, may therefore potentially help maintain an oxidant-antioxidant balance. Glutathione or NAC can also be inhaled and if administered in this way can also have a mucolytic effect besides the antioxidant effect. Current literature suggests a relationship between oxidative status and lung function. This is an update of a previously published review.

OBJECTIVES

To synthesise existing knowledge on the effect of antioxidants such as vitamin C, vitamin E, beta-carotene, selenium and glutathione (or NAC as precursor of glutathione) on lung function through inflammatory and oxidative stress markers in people with CF.

SEARCH METHODS

The Cochrane Cystic Fibrosis and Genetic Disorders Group's Cystic Fibrosis Trials Register and PubMed were searched using detailed search strategies. We contacted authors of included studies and checked reference lists of these studies for additional, potentially relevant studies. We also searched online trials registries.Last search of Cystic Fibrosis Trials Register: 08 January 2019.

SELECTION CRITERIA

Randomised and quasi-randomised controlled studies comparing antioxidants as listed above (individually or in combination) in more than a single administration to placebo or standard care in people with CF.

DATA COLLECTION AND ANALYSIS

Two authors independently selected studies, extracted data and assessed the risk of bias in the included studies. We contacted study investigators to obtain missing information. If meta-analysed, studies were subgrouped according to supplement, method of administration and the duration of supplementation. We assessed the quality of the evidence using GRADE.

MAIN RESULTS

One quasi-randomised and 19 randomised controlled studies (924 children and adults) were included; 16 studies (n = 639) analysed oral antioxidant supplementation and four analysed inhaled supplements (n = 285). Only one of the 20 included studies was judged to be free of bias.Oral supplements versus controlThe change from baseline in forced expiratory volume in one second (FEV₁) % predicted at three months and six months was only reported for the comparison of NAC to control. Four studies (125 participants) reported at three months; we are uncertain whether NAC improved FEV₁ % predicted as the quality of the evidence was very low, mean difference (MD) 2.83% (95% confidence interval (CI) -2.16 to 7.83). However, at six months two studies (109 participants) showed that NAC probably increased FEV₁ % predicted from baseline (moderate-quality evidence), MD 4.38% (95% CI 0.89 to 7.87). A study of a combined vitamin and selenium supplement (46 participants) reported a greater change from baseline in FEV₁ % predicted in the control group at two months, MD -4.30% (95% CI -5.64 to -2.96). One study (61 participants) found that NAC probably makes little or no difference in the change from baseline in quality of life (QoL) at six months (moderate-quality evidence), standardised mean difference (SMD) -0.03 (95% CI -0.53 to 0.47), but the two-month combined vitamin and selenium study reported a small difference in QoL in favour of the control group, SMD -0.66 (95% CI -1.26 to -0.07). The NAC study reported on the change from baseline in body mass index (BMI) (62 participants) and similarly found that NAC probably made no difference between groups (moderate-quality evidence). One study (69 participants) found that a mixed vitamin and mineral supplement may lead to a slightly lower risk of pulmonary exacerbation at six months than a multivitamin supplement (low-quality evidence). Nine studies (366 participants) provided information on adverse events, but did not find any clear and consistent evidence of differences between treatment or control groups with the quality of the evidence ranging from low to moderate. Studies of β-carotene and vitamin E consistently reported greater plasma levels of the respective antioxidants.Inhaled supplements versus controlTwo studies (258 participants) showed inhaled glutathione probably improves FEV₁ % predicted at three months, MD 3.50% (95% CI 1.38 to 5.62), but not at six months compared to placebo, MD 2.30% (95% CI -0.12 to 4.71) (moderate-quality evidence). The same studies additionally reported an improvement in FEV₁ L in the treated group compared to placebo at both three and six months. One study (153 participants) reported inhaled glutathione probably made little or no difference to the change in QoL from baseline, MD 0.80 (95% CI -1.63 to 3.23) (moderate-quality evidence). No study reported on the change from baseline in BMI at six months, but one study (16 participants) reported at two months and a further study (105 participants) at 12 months; neither study found any difference at either time point. One study (153 participants) reported no difference in the time to the first pulmonary exacerbation at six months. Two studies (223 participants) reported treatment may make little or no difference in adverse events (low-quality evidence), a further study (153 participants) reported that the number of serious adverse events were similar across groups.

AUTHORS' CONCLUSIONS

With regards to micronutrients, there does not appear to be a positive treatment effect of antioxidant micronutrients on clinical end-points; however, oral supplementation with glutathione showed some benefit to lung function and nutritional status. Based on the available evidence, inhaled and oral glutathione appear to improve lung function, while oral administration decreases oxidative stress; however, due to the very intensive antibiotic treatment and other concurrent treatments that people with CF take, the beneficial effect of antioxidants remains difficult to assess in those with chronic infection without a very large population sample and a long-term study period. Further studies, especially in very young children, using outcome measures such as lung clearance index and the bronchiectasis scores derived from chest scans, with improved focus on study design variables (such as dose levels and timing), and elucidating clear biological pathways by which oxidative stress is involved in CF, are necessary before a firm conclusion regarding effects of antioxidants supplementation can be drawn. The benefit of antioxidants in people with CF who receive CFTR modulators therapies should also be assessed in the future.

Dietary intake and nutritional status of micronutrients in adults with cystic fibrosis in relation to current recommendations

An increased prevalence of cystic fibrosis (CF) related complications such as impaired bone health and diabetes has accompanied increased survival of patients with CF. This review was conducted to determine the extent to which adults with CF are meeting current nutrition recommendations for micronutrients in association with CF-related complications management. Although dietary intake and nutritional status in CF has improved significantly in recent decades, micronutrient status seems to have diverged. While vitamin A and E intakes appear adequate, frequent vitamin D and K deficiency/insufficiency and compromised bone health in CF, occurs despite supplementation. Although deficiency of water-soluble vitamins and minerals is uncommon, ongoing surveillance will enhance overall health outcomes, particularly in cases of CF-related liver disease and deteriorated lung function and bone health. Salt and fluid status in CF may also need attention due to diminished thirst sensation and voluntary rehydration. Further investigation in micronutrient status optimisation in CF will inform the development of more effective and targeted nutrition therapies to enable integration of more refined recommendations for micronutrient intakes in CF based on individual needs and disease progression.

Antioxidant supplementation for lung disease in cystic fibrosis

BACKGROUND

Airway infection leads to progressive damage of the lungs in cystic fibrosis and oxidative stress has been implicated in the etiology. Supplementation of antioxidant micronutrients (vitamin E, vitamin C, ß-carotene and selenium) or glutathione may therefore potentially help maintain an oxidant-antioxidant balance. Current literature suggests a relationship between oxidative status and lung function.

OBJECTIVES

To synthesize existing knowledge of the effect of antioxidants such as vitamin C, vitamin E, ß-carotene, selenium and glutathione in cystic fibrosis lung disease.

SEARCH METHODS

The Cochrane Cystic Fibrosis and Genetic Disorders Group's Cystic Fibrosis Trials Register and PubMed were searched using detailed search strategies. We contacted authors of included studies and checked reference lists of these studies for additional, potentially relevant studies.Last search of Cystic Fibrosis Trials Register: 29 August 2013.

SELECTION CRITERIA

Randomized controlled studies and quasi-randomized controlled studies of people with cystic fibrosis comparing antioxidants as listed above (individually or in combination) in more than a single administration to placebo or standard care.

DATA COLLECTION AND ANALYSIS

Two authors independently selected studies, extracted data and assessed the risk of bias in the included studies. We contacted trial investigators to obtain missing information. Primary outcomes are lung function and quality of life; secondary outcomes are oxidative stress, inflammation, nutritional status, days on antibiotics and adverse events during supplementation. If meta-analysed, studies were subgrouped according to method of administration and the duration of supplementation.

MAIN RESULTS

One quasi-randomized and nine randomized controlled studies were included, with a total of 436 participants. Eight studies analyzed oral supplementation with antioxidants and two inhaled supplements.One study (n = 46) of an oral combined supplement demonstrated a significant difference in forced expiratory volume at one second expressed as per cent predicted after two weeks in favour of the control group, mean difference -4.30 (95% confidence interval -5.64 to -2.96); however a further study (n = 41) of oral supplementation with glutathione showed a significant improvement in this outcome and in forced vital capacity after six months from the treatment start, mean difference 17.40 (95% confidence interval 13.69 to 21.11) and 14.80 (95% confidence interval 9.66 to 19.94) respectively. The combined supplement study also indicated a significant improvement in quality of life favouring control, mean difference -0.06 points on the quality of well-being scale (95% confidence interval -0.12 to -0.01). Based on one study (n = 41) of oral glutathione supplementation in children, the supplements had a positive effect on the nutritional status (body mass index %) of the patients, mean difference 17.20 (95% confidence interval 12.17 to 22.23). In two studies (n = 83) that supplemented vitamin E, there was an improvement after two months in the blood levels of vitamin E, mean difference 11.78 μM/L (95% confidence interval 10.14 to 13.42).Based on one of the two studies of inhaled glutathione supplementation, there was an improvement in the forced expiratory volume at one second expressed as per cent predicted after three and six months (n = 153), mean difference 2.57 (95% confidence interval 2.24 to 2.90) and 0.97 (95% confidence interval 0.65 to 1.29) respectively. Only one of the studies reported quality of life data that could be analysed, but data showed no significant differences between treatment and control.None of the 10 included studies was judged to be free of bias.

AUTHORS' CONCLUSIONS

There appears to be conflicting evidence regarding the clinical effectiveness of antioxidant supplementation in cystic fibrosis. Based on the available evidence, glutathione (administered either orally or by inhalation) appears to improve lung function in some cases and decrease oxidative stress; however, due to the very intensive antibiotic treatment and other treatments that cystic fibrosis patients receive, the beneficial effect of antioxidants is very difficult to assess in patients with chronic infection without a very large population sample and a long-term (at least six months) study period. Further studies, especially in very young patients, examining clinically relevant outcomes, dose levels, timing and the elucidation of clear biological pathways by which oxidative stress is involved in cystic fibrosis, are necessary before a firm conclusion regarding effects of antioxidants supplementation can be drawn.

Study of selenium intake and disposition in various matrices based on mathematical algorithms derived from pooled biomonitoring data

Biomonitoring is increasingly used to assess exposure to selenium (Se) in the population. However, there is little harmonization among protocols used in the different studies (varying biological matrices, differences in expression of results (concentrations versus amounts, units)). This makes inter-comparison of biomonitoring results across studies difficult. From a public health risk perspective, it also becomes challenging to estimate baseline levels in biological matrices for populations exposed by various sources. The aim of this study was thus to perform a systematic analysis of the relationship between Se intakes and biological concentrations based on published data. Inclusion and exclusion criteria were used and led to select 75 published biomonitoring data in humans from an extended review of Se biomonitoring studies. This represents 8 628 individuals who provided biological samples aiming at documenting Se exposure and/or Se concentrations in two or more biological matrices. Mathematical algorithms that relate Se intakes to biological concentrations and establish matrix-to-matrix associations were derived from these pooled biomonitoring data. Logarithmic regressions showed good correlations between Se intakes and whole blood concentrations (R(2)=0.884), plasma concentrations (R(2)=0.863) and urinary excretion rates (R(2)=0.958). Blood and plasma concentrations were also strongly related (R(2)=0.874), as were whole blood concentrations and urinary excretion rates (R(2)=0.953). The interpretation of the log-regression coefficients allowed illustrating Se physiology. Se concentrations in plasma tend to plateau when daily intake exceed 150 μg/d, whereas Se in urine increases rapidly above this threshold. The application of the algorithms to other independent data sets in order to reconstruct past Se intakes confirmed that interpretation of results on the basis of Se in integuments may be misleading if external contamination is not avoided. This approach based on pooled data covered a wide range of exposure and the large number of data integrated increased the level of confidence of results.

Antioxidant micronutrients for lung disease in cystic fibrosis

BACKGROUND

Airway infection leads to progressive damage of the lungs in cystic fibrosis (CF), partly due to oxidative stress. Supplementation of antioxidant micronutrients (vitamin E, vitamin C, ß-carotene and selenium) may help maintain an oxidant-antioxidant balance. Current literature suggests a relationship between oxidative status and lung function.

OBJECTIVES

To synthesize existing knowledge of the effect of vitamin C, vitamin E, ß-carotene and selenium in CF lung disease.

SEARCH STRATEGY

The Cochrane CF and Genetic Disorders Group CF Trials Register, PubMed, CINAHL and AMED were searched using detailed search strategies. We contacted authors of included studies and checked reference lists of these studies for additional, potentially relevant studies.Last search of CF Trials Register: 09 September 2010.

SELECTION CRITERIA

Randomized controlled trials and quasi-randomized controlled trials of people with CF with explicitly stated diagnostic criteria, comparing vitamin E, vitamin C, ß-carotene and selenium (individually or in combination) to placebo or standard care.

DATA COLLECTION AND ANALYSIS

Two authors independently selected trials, extracted data and assessed risk of bias. We contacted trialists to obtain missing information. Primary outcomes are lung function and quality of life; secondary outcomes are oxidative stress, inflammation, body mass index, days on antibiotics and adverse events during supplementation. If meta-analysed, studies were subgrouped according to combined or single antioxidant supplementation.

MAIN RESULTS

Four randomized controlled trials and one quasi-randomized controlled trial were included; only three trials (87 participants) presented data suitable for analysis. Based on two trials, there was no significant improvement in lung function; one trial indicated significant improvement in quality of life favouring control, mean difference -0.06 points on the quality of well-being scale (95% confidence interval -0.12 to -0.01). Based on two trials, selenium-dependent glutathione peroxidase enzyme significantly improved in favour of combined supplementation, mean difference 1.60 units per gram of haemoglobin (95% CI 0.30 to 2.90) and selenium supplementation, mean difference 10.20 units per gram of haemoglobin (95% CI 2.22 to 18.18). All plasma antioxidant levels, except vitamin C, significantly improved with supplementation.

AUTHORS' CONCLUSIONS

There appears to be conflicting evidence regarding the clinical effectiveness of antioxidant supplementation in CF. Based on the evidence, antioxidants appear to decrease quality of life and oxidative stress; however, few trials contributed data towards analysis. Further trials examining clinically important outcomes and elucidation of a clear biological pathway of oxidative stress in CF are necessary before a firm conclusion regarding effects of antioxidants supplementation can be drawn.

Are copper, zinc and selenium in erythrocytes valuable biological indexes of nutrition and pathology?

The real significance of the level of trace elements copper, zinc and selenium in erythrocytes is still a matter of debate. This review is an evaluation of the potential value of copper, zinc and selenium in red blood cells in physiology, nutrition and pathology, taking into account the other commonly used indices and the analytical difficulty encountered for erythrocyte determinations. The main analytical methods and reference values in erythrocytes are also presented. The literature of the last 3 decades was analyzed. On the basis of these papers, the role of erythrocyte copper in various pathologies should be re-investigated, especially when they include inflammatory processes or hormonal changes. The main interest of zinc determination in red blood cells concerns thyroid pathology. In general, the value of selenium in erythrocytes agrees with selenium in serum and its determination is often unnecessary.

Nutritional management of cystic fibrosis

Nutritional support is an integral part of the management of cystic fibrosis patients. It is arguably best provided by a qualified dietitian and nutritional care sister working in conjunction with the rest of the cystic fibrosis team. The patient's nutritional needs should be assessed, regularly reviewed, and nutritional treatment tailored to meet the changing clinical and psychosocial needs of the patient. Nutritional intervention is not without complications, and in particular attention to normal feeding behaviour and vigilance when instituting supplementary nutrition may prevent many feeding difficulties.

Effect of double-blind cross-over selenium supplementation on lipid peroxidation markers in cystic fibrosis patients

Lipid peroxidation was assessed in 27 cystic fibrosis children during a double-blind selenium supplementation study (2.8 micrograms of sodium selenite per kg per day) with a placebo control and inversion of treatment periods. Simultaneously, 17 healthy children living in the same area were also investigated as control subjects. Before any treatment whatsoever and despite a selenium status close to those of control subjects, cystic fibrosis patients showed significant increase in plasma lipid peroxidation markers. Thiobarbituric acid reactants (TBARs) were normalized after the first treatment period of 5 months in both cystic fibrosis groups receiving either selenium supplementation or placebo. In this latter group, TBARs were reduced despite a significant decrease in plasma selenium concentrations as compared with the control group. Organic hydroperoxide concentrations were also simultaneously normalized in both cystic fibrosis groups at the end of the second treatment period. These results showed that improvement of lipid peroxidation markers was not related to the selenium supplementation. Nevertheless, oxidative stress sustained by cystic fibrosis children must be taken into account so that it does not aggravate the prognosis of the disease.