Relationship of serum antioxidants to asthma prevalence in youth

High body mass index and dietary pattern are associated with childhood asthma

The increasing prevalence of asthma has coincided with an increase of body mass index (BMI) in both children and adults. We investigated the relationship between BMI and the symptom prevalence of asthma and the possible influences of dietary pattern. This was a community-based, cross-sectional study of 24,260 school children aged 6-12 years. Prevalences of asthma and potential confounding factors were assessed using a Korean version of the International Study of Asthma and Allergies in Childhood (ISAAC) questionnaire which was completed by parents. We analyzed the relationship between BMI and symptoms of asthma and the possible influences of dietary pattern. A significant positive association between high BMI and previous 12-month prevalence of wheeze remained in boys (adjusted odds ratio, 1.610; 95% confidence interval, 1.274-2.033) but not in girls. In addition, there were significant associations between high BMI and lifetime prevalence of wheeze, previous 12-month wheeze, exercise-induced wheeze, diagnosis, and treatment of asthma. There were significant associations between high BMI and previous 12-month wheeze regardless of breast-milk feeding or whole-milk feeding. Frequent intake of fresh seafood, fresh fruits, and vegetables was associated with reduced prevalence of current asthma symptoms and was also associated with decreased BMI. These results indicate that BMI may be an independent risk factor for the development of asthma symptoms in boys. Intake of fresh seafood, fresh fruit, and vegetables, which may be associated with decreased BMI, may contribute to protect against the development of asthma symptoms in Korean elementary schoolchildren.

The increase in the prevalence of asthma and allergy: food for thought

Since about 1960, the prevalence of asthma and allergic disease has increased sufficiently to become a major public-health concern. Concurrently, there have been marked changes in our diet, and it has been proposed that these changes have contributed to the increase in the prevalence of asthma and allergy. In this article, these hypotheses about diet are described, together with the postulated mechanisms and the evidence for and against, leading to the most recent evidence indicating that maternal diet during pregnancy might be particularly important in the development of childhood asthma.

Impact of diet on the immunological microenvironment of the pregnant uterus and its relationship to allergic disease in the offspring--a review of the recent literature

Medical progress has reduced the mortality from infectious diseases in most countries, but allergic diseases have become more prevalent worldwide over the same period, especially in industrialized countries. This has prompted speculation that modern lifestyles have altered the relationship between heredity and environment so as to promote development of an atopic phenotype when exposure to infection decreases. A healthy uterine microenvironment is known to favor Th2 lymphocyte development. However, some evidence suggests that persistence of the Th2 pattern of immunity directs the developing organism's immune response towards a long-lasting atopic phenotype. Even though the outcome also depends on other factors (such as infection, functional state of the intestinal microflora, and exposure to environmental allergens at times critical to development), it seems that the immune system during the perinatal period is responsive to interventions that are no longer effective in adulthood. We have reviewed the literature accessible through Medline to identify recent advances in the prevention of allergic disease through interventions in the fetal-maternal relationship. Diet seems to have a significant impact on the immunological profile of the pregnant uterus, as well as on the postnatal development of allergic disease in the offspring, as suggested by the effects of probiotic bacteria and by manipulations of the dietary content of polyunsaturated fatty acids and antioxidants. This highlights the need for further studies, in order to define the best intervention methods, the most appropriate time interval and the individuals who will most likely benefit from them.

Low maternal vitamin E intake during pregnancy is associated with asthma in 5-year-old children

RATIONALE

We have previously reported an association between reduced maternal vitamin E intake during pregnancy and wheezing in 2-yr-old children.

OBJECTIVES

To assess whether maternal nutrient intake during pregnancy is associated with asthma-related outcomes in children aged 5 yr.

METHODS

A longitudinal cohort study of 1,861 children born to women recruited during pregnancy and followed up at 5 yr.

MEASUREMENTS

Maternal nutrient status was assessed by a food frequency questionnaire and plasma levels. Respiratory and food frequency questionnaires were completed at 5 yr and children were invited for measurement of spirometry and skin-prick testing.

MAIN RESULTS

Symptom and food frequency questionnaire data were available for 1,253 and 1,120 children, respectively; 700 children were skin prick tested, and FEV(1) was measured in 478 and exhaled nitric oxide in 167 children. In 5-yr-old children, maternal vitamin E intake during pregnancy was negatively associated with wheeze in previous year (odds ratio per intake quintile, 0.82; 95% confidence interval, 0.71-0.95), asthma ever (0.84, 0.72-0.98), asthma and wheeze in previous year (0.79, 0.65-0.95), and persistent wheezing (0.77, 0.63-0.93). Maternal plasma alpha-tocopherol during pregnancy was positively associated with post-bronchodilator FEV(1) at 5 yr, with a 7-ml (95% confidence interval, 0-14; p = 0.04) increase in FEV(1) per microg/ml alpha-tocopherol. Maternal zinc intake during pregnancy was negatively associated with asthma ever (0.83, 0.71-0.78) and active asthma (0.72, 0.59-0.89). There were no associations between children's nutrient intake and respiratory outcomes.

CONCLUSION

Maternal intake of foods containing vitamin E and zinc during pregnancy is associated with differences in the risks of developing childhood wheeze and asthma.

The role of selenium, zinc and antioxidant vitamin supplementation in the treatment of bronchial asthma: adjuvant therapy or not?

In the last few years, nutrition has represented an important conditioning factor of many cardiovascular, gastrointestinal and pulmonary chronic diseases. Many published works have documented specific inflammatory abnormalities in the airways of subjects with mild-to-moderate persistent bronchial asthma in which the inflammation state is often associated with an increased generation of reactive oxygen species and free radical-mediated reactions. This evidence has stimulated many researchers to suppose that the oxidative stress could be an important pathogenetic determining factor in the progression of chronic diseases, and the decrease of oxidant insults to the lung can be modified with antioxidant supplementary therapy. There are many studies regarding dietary interventions that confirm the relationship to oxidative stress, bronchial inflammation, the development of asthmatic symptoms and the lowered cellular reducing capacity. Simple dietary and environmental supplementations significantly reduce the oxidant stress, minimise the development of asthmatic symptoms, and should prove to be an effective new approach to asthma management in addition to current pharmacological strategies. Many randomised controlled trials with antioxidant vitamins and trace element supplements have not confirmed the results shown in other clinical trials. The aim of this review is to focus the attention on published works discussing the relationship between asthma and nutritional supplements (some trace elements and vitamins) and the effectiveness of these supplements in the treatment of bronchial asthma.

Oxidative stress in asthma and COPD: antioxidants as a therapeutic strategy

Asthma and chronic obstructive pulmonary disease (COPD) are inflammatory lung diseases that are characterized by systemic and chronic localized inflammation and oxidative stress. Sources of oxidative stress arise from the increased burden of inhaled oxidants, as well as elevated amounts of reactive oxygen species (ROS) released from inflammatory cells. Increased levels of ROS, either directly or via the formation of lipid peroxidation products, may play a role in enhancing the inflammatory response in both asthma and COPD. Moreover, in COPD it is now recognized as the main pathogenic factor for driving disease progression and increasing severity. ROS and lipid peroxidation products can influence the inflammatory response at many levels through its impact on signal transduction mechanisms, activation of redox-sensitive transcriptions factors, and chromatin regulation resulting in pro-inflammatory gene expression. It is this impact of ROS on chromatin regulation by reducing the activity of the transcriptional co-repressor, histone deacetylase-2 (HDAC-2), that leads to the poor efficacy of corticosteroids in COPD, severe asthma, and smoking asthmatics. Thus, the presence of oxidative stress has important consequences for the pathogenesis, severity, and treatment of asthma and COPD. However, for ROS to have such an impact, it must first overcome a variety of antioxidant defenses. It is likely, therefore, that a combination of antioxidants may be effective in the treatment of asthma and COPD. Various approaches to enhance the lung antioxidant screen and clinical trials of antioxidant compounds are discussed.

Disruption of Nrf2 enhances susceptibility to severe airway inflammation and asthma in mice

Oxidative stress has been postulated to play an important role in the pathogenesis of asthma; although a defect in antioxidant responses has been speculated to exacerbate asthma severity, this has been difficult to demonstrate with certainty. Nuclear erythroid 2 p45-related factor 2 (Nrf2) is a redox-sensitive basic leucine zipper transcription factor that is involved in the transcriptional regulation of many antioxidant genes. We show that disruption of the Nrf2 gene leads to severe allergen-driven airway inflammation and hyperresponsiveness in mice. Enhanced asthmatic response as a result of ovalbumin sensitization and challenge in Nrf2-disrupted mice was associated with more pronounced mucus cell hyperplasia and infiltration of eosinophils into the lungs than seen in wild-type littermates. Nrf2 disruption resulted in an increased expression of the T helper type 2 cytokines interleukin (IL)-4 and IL-13 in bronchoalveolar lavage fluid and in splenocytes after allergen challenge. The enhanced severity of the asthmatic response from disruption of the Nrf2 pathway was a result of a lowered antioxidant status of the lungs caused by lower basal expression, as well as marked attenuation, of the transcriptional induction of multiple antioxidant genes. Our studies suggest that the responsiveness of Nrf2-directed antioxidant pathways may act as a major determinant of susceptibility to allergen-mediated asthma.

Ambrisentan for pulmonary arterial hypertension

Endothelin receptor antagonists (ERAs) are an important class of agents used for the treatment of pulmonary arterial hypertension (PAH). Ambrisentan is an oral, once-daily, endothelin type-A receptor (ETA)-selective, propanoic acid class ERA under clinical investigation for the treatment of PAH. In a Phase II study, ambrisentan improved 6-minute walk distance, Borg dyspnea index, World Health Organization Functional Class, and hemodynamics. Ambrisentan was well tolerated and adverse events were not dose related, including a low incidence and severity of liver function test abnormalities. There are no relevant interactions between ambrisentan and cytochrome P450 isoenzymes (metabolism, induction or inhibition) that might alter the activity of P450-metabolized drugs. Potential benefits of ambrisentan include oral, once-daily dosing, ETA-receptor selectivity, and the decreased risks of liver toxicity and adverse drug–drug interactions compared with other ERAs.

Correlation of systemic superoxide dismutase deficiency to airflow obstruction in asthma

RATIONALE

Increased oxidative stress and decreased superoxide dismutase (SOD) activity in the asthmatic airway are correlated to airflow limitation and hyperreactivity. We hypothesized that asthmatic individuals with higher levels of oxidative stress may have greater loss of SOD activity, which would be reflected systemically in loss of circulating SOD activity and clinically by development of severe asthma and/or worsening airflow limitation.

METHODS

To investigate this, serum SOD activity and proteins, the glutathione peroxidase/glutathione antioxidant system, and oxidatively modified amino acids were measured in subjects with asthma and healthy control subjects.

RESULTS

SOD activity, but not Mn-SOD or Cu,Zn-SOD protein, was lower in asthmatic serum as compared with control, and activity loss was significantly related to airflow limitation. Further, serum SOD activity demonstrated an inverse correlation with circulating levels of 3-bromotyrosine, a posttranslational modification of proteins produced by the eosinophil peroxidase system of eosinophils. Exposure of purified Cu,Zn-SOD to physiologically relevant levels of eosinophil peroxidase-generated reactive brominating species, reactive nitrogen species, or tyrosyl radicals in vitro confirmed that eosinophil-derived oxidative pathways promote enzyme inactivation.

CONCLUSION

These findings are consistent with greater oxidant stress in asthma leading to greater inactivation of SOD, which likely amplifies inflammation and progressive airflow obstruction.

Decreased exhaled nitric oxide in pulmonary arterial hypertension: response to bosentan therapy

RATIONALE

Decreased nitric oxide (NO) is considered an important pathogenetic mechanism in pulmonary arterial hypertension (PAH), but clear evidence is lacking.

OBJECTIVES

We used multiple techniques to assess endogenous NO in 10 patients with untreated PAH (8 idiopathic and 2 anorexigen-associated PAH) and 12 control subjects.

METHODS

After a nitrite/nitrate-restricted diet, NO metabolites (NOx) were assayed in 24-hour urine collections and exhaled NO (FE(NO)) determined at multiple expiratory flows. Analysis of the relation between FE(NO) and flow allowed derivation of three flow-independent parameters: airway wall concentration (C(W)), diffusing capacity (D(NO)), and alveolar concentration (C(A)). Seven patients underwent follow-up testing after 3 months of bosentan treatment.

RESULTS

At baseline, FE(NO) was markedly decreased at the two lowest expiratory flows in PAH: 21 +/- 4 versus 36 +/- 4 ppb at 18 ml/second and 11 +/- 2 versus 17 +/- 2 ppb at 50 ml/second, for subjects with PAH and control subjects, respectively (p < 0.05). C(W) was 33 +/- 11 ppb in subjects with PAH versus 104 +/- 34 in control subjects (p = 0.04). Urinary NOx was also reduced in PAH (42 +/- 6 microM NOx/mM creatinine versus 62 +/- 7 in control subjects; p = 0.04). After bosentan, FE(NO), C(W), and urine NOx increased to control values (p < 0.05). Exclusion of the two anorexigen cases did not alter these results.

CONCLUSIONS

FE(NO) at low expiratory flows was decreased in PAH due to reduced C(W). Bosentan reversed these abnormalities, suggesting that suppression of NO in PAH may have been caused by endothelin.

Dietary intake of fatty acids, antioxidants and selected food groups and asthma in adults

OBJECTIVE

Within a prospective study, we explored the associations between dietary intake of fatty acids, antioxidants and relevant food sources of these nutrients on the clinical manifestation of asthma in adulthood.

METHOD

A total of 105 newly physician-diagnosed cases of asthma from the European Prospective Investigation into Cancer and Nutrition (EPIC)-Heidelberg cohort were identified during follow-up and matched with 420 controls. Baseline dietary intake was obtained by means of validated food frequency questionnaires. The association of dietary intake variables and asthma risk was explored by unconditional logistic regression models.

RESULTS

A high intake of oleic acid (C18:1 n-9) was positively associated with asthma (P-value for trend 0.035), while no significant associations were found for the other dietary fatty acids. Most prominently, a high margarine intake increased the risk of onset of asthma in adulthood (adjusted odds ratio (OR) 3rd tertile: 1.73 (95% confidence interval (95% CI): 1.05-2.87), P for trend=0.050), the effect being stronger in men (2nd tertile: OR=1.66, 3rd tertile: OR=2.51) than in women (2nd tertile: OR=0.91; 3rd tertile: OR=1.47). The dietary intake of antioxidants and their main food sources had no effect on asthma risk.

CONCLUSIONS

In summary, the present results provide evidence that even in adulthood a high margarine intake increases the risk of clinical onset of asthma. Whether oleic acid may serve as a proxy for margarine-derived trans-fatty acids (C18:1 t9) remains to be clarified.

Dietary and biochemical selenium status of urban 6- to 24-month-old South Island New Zealand children and their postpartum mothers

A community-based, cross-sectional survey was conducted in the South Island of New Zealand to assess the dietary and biochemical selenium status of children (n = 136) and their mothers (n = 302), and to assess factors influencing selenium status. Serum and plasma samples from children and their mothers were analyzed for selenium using graphite furnace atomic absorption spectrometry. Dietary selenium intakes were analyzed from 3-d weighed diet records, and food sources of selenium were quantified. Mean dietary selenium intakes in infants (6-11.9 mo), toddlers (12-24 mo), and mothers were below recommended levels. Toddlers had higher selenium intakes than infants (13.7 +/- 8.4 and 7.9 +/- 6.2 microg/d, respectively, P = 0.0001) and the selenium density of their diets was also higher [3.2 +/- 1.7 and 2.4 +/- 1.7 microg/(MJ . d), respectively, P = 0.003]. Household smoking was associated with lower serum selenium concentrations in infants and toddlers (P = 0.02). South Island women who were currently pregnant had lower plasma selenium concentrations (0.74 +/- 0.15 micromol/L) than nonpregnant lactating and nonpregnant nonlactating women (0.94 +/- 0.16 and 0.93 +/- 0.16 micromol/L, respectively, P = 0.0001). Clearly, pregnant women, infants and toddlers are at risk of suboptimal selenium status, and further research is warranted to assess potential effects in these groups. The finding of an association between household smoking and lower selenium concentrations in children should be investigated further. Dietary interventions are recommended to improve dietary selenium intakes in South Island children and their mothers.

Advances in pediatric allergy

PURPOSE OF REVIEW

The purpose of this review is to highlight several important findings related to the broad topic of pediatric allergic diseases reported over the past year, focusing primarily on asthma, urticaria, food allergy, and vaccine reactions.

RECENT FINDINGS

Progress continues to be made in identifying environmental exposures during the first years of life that are important for the development of atopic diseases, including asthma. Interventions are being sought based on these findings, to prevent the development of atopic diseases. Chronic urticaria in children is difficult to manage and there is little data related specifically to children to guide treatment and education. Two reports of large populations of children with chronic urticaria were reported in the past year; one dealing with chronic idiopathic, urticaria and one with acquired cold urticaria. Food allergy continues to increase in prevalence and improvements in diagnosis and management continue. Finally, a report of vaccine anaphylaxis cases among a large database was reported.

SUMMARY

Allergic disorders comprise a major component of pediatric practice. Advances continue in understanding the origins and natural history of these disorders and treatments are now available that allow effective management in most cases. Patient and parent education remains key to prevent unnecessary restrictions on these children and ensure optimal treatment success.