The Shanghai Women's Asthma and Allergy Study: objectives, design, and recruitment results

Pre-asthma: a useful concept? A EUFOREA paper. Part 2-late onset eosinophilic asthma

The concept of pre-diabetes has led to provision of measures to reduce disease progression through identification of subjects at risk of diabetes. We previously considered the idea of pre-asthma in relation to allergic asthma and considered that, in addition to the need to improve population health via multiple measures, including reduction of exposure to allergens and pollutants and avoidance of obesity, there are several possible specific means to reduce asthma development in those most at risk (pre- asthma). The most obvious is allergen immunotherapy (AIT), which when given for allergic rhinitis (AR) has reasonable evidence to support asthma prevention in children (2) but also needs further study as primary prevention. In this second paper we explore the possibilities for similar actions in late onset eosinophilic asthma.

Interaction of vitamin E isoforms on asthma and allergic airway disease

Prospective epidemiological studies, observational cross-sectional studies and some randomised prevention trials have demonstrated inconsistent findings of the impact of vitamin E on asthma risk. The goals of this study were to explore whether this differing association of vitamin E on asthma risk is due to an interaction of vitamin E isoforms. To address this question, in a population-based asthma incidence study we assessed the interaction between the plasma concentrations of vitamin E isoforms α-tocopherol and γ-tocopherol on asthma risk. Second, to understand the mechanisms of any interaction of these isoforms, we conducted experimental supplementation of α-tocopherol and γ-tocopherol isoforms in mice on the outcome of allergic airway inflammation. We found that in the highest γ-tocopherol tertile, low levels of α-tocopherol were associated with increased asthma risk, while highest tertile α-tocopherol levels trended to be protective. Similarly, in a mouse model of asthma, diet supplementation with α-tocopherol decreased lung inflammation in response to house dust mite (HDM) challenge. In contrast, diet supplementation with γ-tocopherol increased lung inflammation in response to HDM. These human and animal studies provide evidence for the competing effects of the vitamin E isoforms, in physiological concentrations, on asthma and allergic airway disease.

New risk factors for adult-onset incident asthma. A nested case-control study of host antioxidant defense

RATIONALE

Host antioxidant defense, consisting of enzymatic antioxidant activity and nonenzymatic antioxidant micronutrients, is implicated in asthma pathogenesis. Studies of antioxidant defense and adult incident asthma have either used measures of antioxidants estimated from questionnaires or not considered enzymatic aspects of host defense.

OBJECTIVES

We conducted the first study designed and powered to investigate the association of antioxidant defenses on adult incident asthma.

METHODS

In a nested case-control study, we followed Shanghai women (aged 40-70 years) without prevalent asthma at baseline, over 8 years. Subjects with incident asthma were ascertained prospectively by gold standard testing of symptomatic women and matched to two asymptomatic control subjects.

MEASUREMENTS AND MAIN RESULTS

Baseline urinary F2-isoprostanes, plasma concentrations of antioxidant micronutrients (tocopherols, xanthines, carotenes, and lycopene), and antioxidant enzyme activity (platelet-activating factor acetylhydrolase [PAF-AH] and superoxide dismutase) were measured from samples collected before disease onset. Among 65,372 women, 150 (0.24%) developed asthma. F2-isoprostane levels before asthma onset were not different between cases and control subjects. Doubling of α-tocopherol concentrations and PAF-AH activity was associated with 50 and 37% decreased risk of incident asthma (α-tocopherol: adjusted odds ratio = 0.52; 95% confidence interval, 0.32-0.84; PAF-AH: adjusted odds ratio = 0.63; 95% confidence interval, 0.42-0.93).

CONCLUSIONS

In this prospective study, α-tocopherol, within normal reference ranges, and PAF-AH enzymatic activity were associated with decreased asthma development. These modifiable risk factors may be an effective strategy to test for primary asthma prevention.

Limonene inhalation reduces allergic airway inflammation in Dermatophagoides farinae-treated mice

Limonene is one of the main flavonoids which is reported to inhibit the inflammatory response by suppressing the production of reactive oxygen species. The aim of this study was to evaluate whether limonene can inhibit Dermatophagoides farinae-induced airway hyperresponsiveness (AHR), eosinophilic infiltration and other histological changes in the lung, T helper (Th) 2 cytokine production and airway remodeling in a mice model of asthma. Treatment with limonene significantly reduced the levels of IL-5, IL-13, eotaxin, MCP-1, and TGF-β₁ in bronchoalveolar lavage fluid. The goblet cell metaplasia, thickness of airway smooth muscle, and airway fibrosis were markedly decreased in limonene-treated mice. Furthermore, AHR to acetylcholine was significantly abrogated in limonene-treated mice. These results indicate that limonene has a potential to reduce airway remodeling and AHR in asthma model.

Goishi tea consumption inhibits airway hyperresponsiveness in BALB/c mice

Background

Airway hyperresponsiveness (AHR) is one of the important traits that characterize bronchial asthma. Goishi tea is a post-heating fermented tea that has been reported to have higher free radical scavenging activity. In this study, we evaluated the prophylactic effects of Goishi tea on AHR in BALB/c mice.

Results

The number of inflammatory cells in BAL fluid was considerably reduced in Goishi tea/Der f and Gallic acid/Der f groups as compared with Tap water/Der f group. Regarding inflammatory cells in BAL, a significant reduction of eosinophils and neutrophils was observed in Goishi tea-treated mice (p < 0.01), as well as in the Gallic acid/Der f group (p < 0.05), as compared with Tap water/Der f group. In asthmatic mice (Tap water/Der f group), the intensity of airway resistance increased simultaneously with the increase in acetylcholine concentration in a dose-dependant way. AHR was significantly inhibited in Goishi tea/Der f and Gallic acid/Der f (p < 0.01) groups as compared with the Tap water/Der f group. Regarding serum specific-IgG₁, significantly lower levels of this antibody were observed in Goishi tea/Der f and Gallic acid/Der f groups as compared with the Tap water/Der f group (p < 0.05). In addition, adiponectin level was significantly higher in the Goishi tea group as compared with the Tap water treated mice (p < 0.01).

Conclusions

The results suggest that Goishi tea consumption exerted an inhibitory effect on eosinophilic and neutrophilic infiltration in the lung, attenuated the increase in airway resistance and increased the production of adiponectin; thus reducing Der f induced allergic inflammatory process in mice.

Development of a nomogram for identification of asthma among adults in epidemiologic studies

BACKGROUND

The criteria used to identify persons with asthma in epidemiologic studies are varying and, depending on the method used, can be challenging and resource consuming.

OBJECTIVE

To develop a nomogram (scoring system) to identify adult patients with asthma using a combination of variables collected via a validated questionnaire.

METHODS

We studied the first 268 women aged 40 to 69 years in the Shanghai Women's Asthma and Allergy Study who reported signs and symptoms of asthma and underwent either methacholine challenge testing or test of reversibility during the asthma screening survey between 2003 and 2007. These women were defined as having definite asthma (n=106) or not (n=162). Multivariable logistic regression analysis was performed to develop a predictive model for identifying asthma using survey information alone.

RESULTS

Clinically relevant questions were used for the predictive multivariable logistic regression model and included the following: ever wheezing or whistling in the chest, current medication use for asthma, self-reported ever asthma, self-reported ever allergic rhinitis, family history of allergy, and age. The area under the receiver operating characteristic curve of the prediction model was 0.75 (95% confidence interval, 0.69-0.81). A nomogram was developed to assess the individual probability of asthma based on individually weighted variables in the predictive model.

CONCLUSIONS

In clinical or epidemiologic studies, this asthma nomogram could be used as a tool to assess the probability of asthma for an individual patient by incorporating asthma-related predictor variables obtained through a field questionnaire.