[Air pollution and allergic airway diseases]

Haze facilitates sensitization to house dust mites in children

Allergy to house dust mites (HDMs) can cause allergic rhinitis, allergic asthma and allergic skin disorders, which is becoming an enormous worldwide health and economic burden. To explore the relationship between air pollution and HDMs sensitization in children, this study used immunoblotting to determine the concentration of HDM serum-specific IgE (sIgE) in children with allergic diseases in Hangzhou. HDM sIgE was used to reflect the sensitization of children with HDMs. Using the meteorological and atmospheric pollutant data for Hangzhou, a distributed lag nonlinear model was founded to evaluate the effect of atmospheric pollutants on HDMs sensitization. Particulate matter (PM) _2.5 and PM₁₀ were the main air pollutants in Hangzhou. The positive rate of HDM sIgE in children's serum increased with increasing PM_2.5 and PM₁₀ concentrations, and this effect was most obvious on the seventh and tenth days after increased PM_2.5 and PM₁₀ concentrations, respectively. In addition, there was a significant positive correlation between the concentration of HDM sIgE and the total serum IgE concentration. The rate of sensitization to HDMs rose dramatically in the first 3 years after birth. In addition, the period between June and November had the largest number of HDM sIgE-positive patients. Studies have shown that PM_2.5 and PM₁₀ are important factors in HDM sensitization, which presented obvious dose effects and lag effects. Children under the age of 3 years were the most susceptible to HDMs, and the period from June to November had a high risk of dust mite exposure. Avoiding exposure to particulate matter may have benefits in preventing HDM sensitization in children.

Do the levels of particulate matters less than 10 μm and seasons affect sleep?

Background: There are few studies showing that the increase in particulate matters less than 10 μm (PM10) values increases the apnea-hypopnea index (AHI). We aimed to investigate relationship between air quality parameters and the seasons with the AHI.Methods: This was a retrospective study that included 500 adults. Polysomnography (PSG) was performed on all patients. Oxygen saturation, air temperature, relative humidity, and PM10 values were recorded in Düzce for every year. The parameters of the national air quality network and sleep parameters of 500 individuals hospitalized between 2015 and 2017 were checked.Results: A total of 500 patients were included in the study, of whom 316 (63.2%) were male and 184 (36.8%) were female. While the AHI value of patients who presented during 2016 was 27.5, it had significantly declined to 20.2 in 2017 (p = .024). A significant decline was observed in AHI values of OSA patients from 2016 to 2017 (p = .043). A significant positive correlation was observed between REM-related AHI and relative humidity (r  =  0.183, p = .002). Conclusions: This study showed a clear relationship between AHI and PM10 during winter when air pollution parameters are high in the region. PM10 emerged as a parameter that substantially increases the relative risk for OSA.

[Protective role of Nrf2 in the lungs against oxidative airway diseases]

Airways are continually exposed to multiple inhaled oxidants and protect themselves with cellular and extracellular antioxidants throughout the epithelial lining fluid and tissues. Oxidative stress, resulting from the increased oxidative burden and decreased level of antioxidant proteins, is involved in cellular and tissue damage related to the pathogenesis of many acute and chronic respiratory diseases. Evidence suggested that nuclear factor erythroid-2-related factor 2 (Nrf2), a transcription factor that controls antioxidant response element (ARE)-regulated antioxidant and cytoprotective genes has an essential protective role in the lungs against oxidative airway diseases. Therefore, Nrf2 promises to be an attractive therapeutic target for intervention and prevention strategies in respiratory diseases. We have reviewed major findings on the mechanisms of lung protection against oxidative stress by Nrf2 and the current literature suggesting that Nrf2 is a valuable therapeutic target.

Quantitative assessments of indoor air pollution and respiratory health in a population-based sample of French dwellings

BACKGROUND

Various volatile organic compounds (VOCs) have been related to respiratory health effects, but have generally been assessed individually without taking into account the fact that such pollutants are highly correlated to one other.

AIMS

We investigated the effects of exposure to various VOC, and considered their combined effect on adult asthma and rhinitis.

METHOD

A national cross-sectional representative survey conducted by the Indoor Air Quality Observatory objectively assessed 20 VOCs in 490 main dwellings in France. A standardized questionnaire determined the prevalence of asthma and rhinitis among 1012 inhabitants of the dwellings (≥ 15 years). Marginal models for binary outcome were used to relate VOCs exposure to asthma and rhinitis, controlling for potential confounders. A global score representing the number of VOCs in each dwelling with an elevated concentration (using the 3(rd) quartile value of the distribution as a threshold value) was then derived as a measure of the combined effect of VOCs. Specific scores were built using a similar approach, grouping VOCs by family.

RESULTS

Asthma (8.6%) was significantly associated with N-undecane and 1,2,4-trimethylbenzene and rhinitis (38.3%) with ethylbenzene, trichloroethylene, m/p- and o-xylene. The global VOC score was associated with a significant risk of asthma and rhinitis (odds ratio (OR) of 1.40 and 1.22, respectively, for 5 additional VOCs with high exposure level). Both specific scores for aromatic hydrocarbons and aliphatic hydrocarbons were associated with a significantly risk of asthma (OR=1.12; 95% confidence interval (CI): 1.01-1.24 and OR=1.41; 95% CI=1.03-1.93, respectively). The specific VOC score for halogenated hydrocarbons was associated with a significant risk of rhinitis (OR=1.28; 95% CI: 1.07-1.54).

CONCLUSION

We have shown that high concentrations of VOCs in homes were associated with an increasing prevalence of asthma and rhinitis in adults.

PM 2.5 collected in a residential area induced Th1-type inflammatory responses with oxidative stress in mice

Epidemiologists have tried to establish an association between human health and exposure to particulate matter (PM). In addition, many researchers have investigated the adverse effects of PM as a trigger of cardiovascular and pulmonary diseases. It is known that a number of environmental contaminants are attached to PM and the toxicity of PM may depend on the sources. We investigated the effects of PM collected in a residential area of Seoul on the immunotoxic responses including cytokine production in BAL fluid and in blood after a single intratracheal instillation in mice with the characterization of physico-chemical properties of PM 2.5 samples. As results, pro-inflammatory cytokines (IL-1, TNF-α, and IL-6), Th0-type cytokine (IL-2), and Th1-type cytokines (IL-12 and IFN-γ) were increased by a dose-dependent manner. Cell infiltration in the alveolar area and phagocytosis by macrophage was observed until day 28 after instillation. The expressions of oxidative stress-related genes (HSP 1a, HSP 8, and SOD) and tissue damage-related genes (MMP-15, -19, and Slpi) were time-dependently increased. PM 2.5 also induced an increase of T cell distribution in lymphocyte and decreased the CD4+/CD8+ ratio. Based on the results, we suggest that PM 2.5 collected in a residential area of Seoul may induce Th1 type-inflammatory responses with oxidative stress and trigger adverse effects in human health.

[Allergic respiratory diseases and outdoor air pollution]

INTRODUCTION

After having increased for some time, the prevalence of allergic diseases may have reached a plateau. During this increase, considerable concomitant changes in air pollution have occurred. Photo-oxidant air pollution, related to traffic, has become preponderant. The implication of air pollution in the epidemic of allergies is still debated.

BACKGROUND

Experimental studies have suggested that the effect of air pollutants, including particulates and ozone, on the worsening and even the induction of allergies is biologically plausible. In addition, epidemiological studies have shown a short term impact of the peaks of air pollution on exacerbations of asthma. On the other hand, the results of epidemiological studies dealing with the long-term effects of chronic exposure to air pollution on the prevalence of allergies are less consistent.

VIEWPOINTS

The implementation of new-born cohorts, the use of dispersion models to improve exposure assessment and the study of gene-environment correlations, should increase our knowledge of the role of traffic-related air pollutants in the development of allergies and identify subjects more sensitive to their effects.

CONCLUSIONS

Some traffic-related air pollutants may have played a more important role in the increase in the prevalence of allergies than was assumed from the first epidemiological studies.