Environmental risk factors related to the incidence of wheeze and asthma in adolescence

The impact of indoor pollution on asthma-related outcomes: A systematic review for the EAACI guidelines on environmental science for allergic diseases and asthma

Systematic review using GRADE of the impact of exposure to volatile organic compounds (VOCs), cleaning agents, mould/damp, pesticides on the risk of (i) new-onset asthma (incidence) and (ii) adverse asthma-related outcomes (impact). MEDLINE, EMBASE and Web of Science were searched for indoor pollutant exposure studies reporting on new-onset asthma and critical and important asthma-related outcomes. Ninety four studies were included: 11 for VOCs (7 for incidenceand 4 for impact), 25 for cleaning agents (7 for incidenceand 8 for impact), 48 for damp/mould (26 for incidence and 22 for impact) and 10 for pesticides (8 for incidence and 2 for impact). Exposure to damp/mould increases the risk of new-onset wheeze (moderate certainty evidence). Exposure to cleaning agents may be associated with a higher risk of new-onset asthma and with asthma severity (low level of certainty). Exposure to pesticides and VOCs may increase the risk of new-onset asthma (very low certainty evidence). The impact on asthma-related outcomes of all major indoor pollutants is uncertain. As the level of certainty is low or very low for most of the available evidence on the impact of indoor pollutants on asthma-related outcomes more rigorous research in the field is warranted.

Proliferation of Lung Epithelial Cells Is Regulated by the Mechanisms of Autophagy Upon Exposure of Soots

Background

Soots are known to cause many diseases in humans, but their underlying mechanisms of toxicity are still not known. Here, we report that soots induce cell proliferation of lung epithelial cells via modulating autophagy pathways.

Results

Fullerene soot and diesel exhaust particles (DEP) induced cell proliferation of lung epithelial, A549 cells via distinct autophagic mechanisms and did not cause cell death. Exposure of fullerene soot protected the cell death of A549 cells, caused by hydrogen peroxide, and inhibited LPS-induced autophagy. Fullerene soot co-localized with the autophagic proteins and inhibited starvation-induced autophagy (downregulated ATG-5, beclin-1, p62, and LC3 expressions) independent of its antioxidant properties. Similarly, it decreased the expression profile of autophagic genes and upregulated the proliferation-responsive gene, Ki-67, in mice. We observed that expressions of fullerene soot-responsive genes (Beclin-1, ATG-5, and p62) were reverted by Akt Inhibitor X, indicating an important role of the Akt pathway. At an elemental level, we found that elemental carbon of fullerene soot may be converted into organic carbon, as measured by OCEC, which may point fullerene soot as a source of carbon. On the other hand, DEP upregulated the expressions of autophagy genes. Akt Inhibitor X did not attenuate DEP-induced cell proliferation and autophagic response. However, an autophagic inhibitor, chloroquine, and significantly inhibited DEP-induced cell proliferation.

Conclusion

It can be said that distinct autophagic mechanisms are operational in cell proliferation of lung epithelial cells due to soots, which may be responsible for different diseases. Understanding the mechanism of these pathways provides some important targets, which can be utilized for the development of future therapeutics.

Developments in the field of clinical allergy in 2015 through the eyes of Clinical and Experimental Allergy

In the second of two papers, we describe developments in the field of clinical allergy as documented by Clinical and Experimental Allergy in 2015. Epidemiology, clinical allergy, asthma and rhinitis are all covered.

Different clinical effect of several types of airborne allergens on the severity of bronchial hyperreactivity

BACKGROUND

Atopic sensitization belongs to the most common risk factors for bronchial asthma. However, in clinical practice, it is not clear whether sensitization against pollen and perennial allergens is differently associated with the severity of bronchial hyperresponsiveness (BHR).

AIM

To find out whether patients sensitized to perennial allergens differ in severity of bronchial hyperresponsiveness from patients sensitized to pollen allergens.

METHODS

The study includes 109 patients. Based on the results of skin prick tests, patients were divided into three groups: sensitivity to pollen allergens - group A; sensitivity to perennial allergens - group B; sensitivity to both pollen and perennial allergens - group C. Based on the histamine bronchoprovocation test, we compared the values of histamine provocative concentration causing a 20% drop in FEV₁ (PC₂₀) among particular groups of patients. Mild bronchial hyperresponsiveness was determined if the value of PC₂₀ was >4 mg/ml, while if the value of PC₂₀ was <4 mg/ml, the bronchial hyperresponsiveness was considered as moderate/severe.

RESULTS

A statistically significant difference was found in the degrees of bronchial hyperresponsiveness between the three groups of patients, namely, group A with the patients sensitized only to the pollen allergens, group B comprising patients sensitized to the perennial allergens only, and group C, involving patients sensitized to the combination of both pollen and perennial allergens. The PC₂₀ values were higher among the patients from the group A (7.46 mg/ml) compared to group B (4.25 mg/ml) and C (4.52 mg/ml). The odds ratio for moderate/severe BHR was 5.21 and 5.04 in group B and group C, respectively.

CONCLUSION

Severity of bronchial hyperresponsiveness shows differences according to sensitization to particular allergens. Perennial allergens are more often associated with serious forms of bronchial hyperresponsiveness which also have an impact on the severity and prognosis of bronchial asthma.

Upper airway and skin symptoms in allergic and non-allergic asthma: Results from the Swedish GA2LEN study

BACKGROUND

Allergic and non-allergic asthma are viewed as separate entities, despite sharing similarities. The aims of this study were to determine differences in symptoms from the upper airways and the skin in allergic and non-allergic asthma. The secondary aims were to identify childhood risk factors and to compare quality of life in the two asthma groups.

METHODS

This cohort (age 17-76 years) consisted of 575 subjects with allergic or non-allergic asthma and 219 controls. The participants participated in an interview, spirometry, FeNO, skin prick test, and responded to the Mini Asthma Quality of Life Questionnaire.

RESULTS

Self-reported allergic rhinitis was significantly more common in both allergic and non-allergic asthma (82.3 and 40.7%) groups compared with the controls. The prevalence of chronic rhinosinusitis (CRS) was similar in both asthma groups. Eczema was significantly more common in both asthmatic groups (72.3 and 59.8%) than controls (47.0%) (p < 0.001 and p = 0.012). Severe respiratory infection in childhood and parental allergy were risk factors for both allergic and non-allergic asthma groups. Quality of life was significantly lower in non-allergic than allergic asthma groups (p = 0.01).

CONCLUSION

Concomitant symptoms from the upper airways and the skin were significantly more common in both allergic and non-allergic asthma. This indicates that non-allergic asthma has a systemic component with similarities to what is found in allergic asthma. There were similarities in the childhood risk factor pattern between the two types of asthma but asthma-related quality of life was lower in the non-allergic asthma group.

High incidence and persistence of airborne allergen sensitization up to age 19 years

BACKGROUND

Longitudinal population-based studies about the natural history of allergic sensitization are rare. The aim was to study incidence and persistence of airborne allergen sensitization up to young adulthood and risk factors for early and late onset of sensitization.

METHODS

All children aged 7-8 years in two municipalities in Northern Sweden were invited to a parental questionnaire and skin prick tests (SPTs) to ten airborne allergens, and 2148 (88%) participated. The protocol was repeated at age 11-12 and 19 years, and 1516 participated in all three examinations.

RESULTS

Prevalence of any positive SPT increased from 20.6% at age 7-8 years to 30.6% at 11-12 years, and 42.1% at 19 years. Animals were the primary sensitizers at age 7-8 years, 16.3%, followed by pollen, 12.4%. Mite and mold sensitization was low. Mean annual incidence of any positive SPT varied between 2.8 and 3.4/100 per year, decreased by age for animal, and was stable for pollen. Sensitization before age 7-8 years was independently associated with family history of allergy, OR 2.1 (95% CI 1.6-2.8), urban living, OR 1.9 (95% CI 1.2-2.9), and male sex, OR 1.3 (95% CI 1.0-1.7), and negatively associated with birth order, OR 0.8 (95% CI 0.7-1.0), and furry animals at home, OR 0.7 (95% CI 0.7-0.9). Incidence after age 11-12 years was associated only with family history of allergy. Multisensitization at age 19 years was significantly associated with early age at sensitization. Remission of sensitization was uncommon.

CONCLUSION

The increasing prevalence of allergic sensitization by age was explained by high incidence and persistence. After age 11-12 years, the factors urban living, number of siblings, and male sex lost their importance.

Smoking and New-Onset Asthma in a Prospective Study on Italian Adults

BACKGROUND

The existence of a cause-effect relation between active smoking and new-onset asthma in adults, although supported by several studies, has not been proven yet.

AIMS

We aimed to prospectively study asthma incidence as a function of smoking habits in the Italian adult population.

METHODS

A population-based cohort of 5,241 non-asthmatics was enrolled in Verona and Sassari in 1998-2000. The cohort was contacted again in 2007-2009 within the Gene-Environment Interactions in Respiratory Diseases study, and 3,187 subjects (60.8%) answered a screening questionnaire on smoking habits and respiratory disorders. The relation between smoking habits and self-reported new-onset asthma, defined as asthma attacks/use of medicines for asthma, was investigated by a multivariable logistic model.

RESULTS

During follow-up, 145 new cases of asthma were observed, yielding a cumulative incidence of 4.6% (95% CI 3.9-5.4); cumulative incidence of asthma did not significantly differ among never-smokers (76/1,666 = 4.6%), ex-smokers (30/554 = 5.4%) and current smokers (39/883 = 4.4%) (p = 0.641). In a multivariable analysis, the most important risk factor for asthma onset was allergic rhinitis (OR = 4.00, 95% CI 3.68-4.35). Compared to never-smokers, the risk of asthma onset was slightly increased in ex-smokers (OR = 1.28, 1.09-1.49) but not in current smokers (OR 1.01, 0.66-1.53). Current smoking became a significant predictor only when both new-onset wheezing and new-onset asthma were considered as the outcome (OR = 2.03, 1.35-3.05).

CONCLUSIONS

In this prospective study, current smoking was not a risk factor for new-onset asthma, unless new-onset wheezing was also considered. The increase in asthma incidence among ex-smokers was likely due to reverse causation.

The effects of lutein on respiratory health across the life course: A systematic review

BACKGROUND

Lutein, a fat-soluble carotenoid present in green leafy vegetables and eggs, has strong antioxidant properties and could therefore be important for respiratory health.

DESIGN

We systematically reviewed the literature for articles that evaluated associations of lutein (intake, supplements or blood levels) with respiratory outcomes, published in Medline, Embase, Cochrane Central, PubMed, Web of Science and Google Scholar, up to August 2014.

RESULTS

We identified one Randomized Control Trial (RCT), two longitudinal, four prospective and six cross-sectional studies. The individual studies obtained a Quality Score ranging between 3 and 9. Six studies were performed in children, which examined bronchopulmonary dysplasia (BPD), asthma and wheezing. In adults, 7 studies investigated asthma, respiratory function and respiratory mortality. The RCT found a borderline significant effect of lutein/zeaxanthin supplementation in neonates on the risk of BPD (OR 0.43 (95% CI 0.15; 1.17). No association was found between lutein intake or levels and respiratory outcomes in children. A case-control study in adults showed lower lutein levels in asthma cases. Three studies, with a prospective or longitudinal study design, in adults found a small but a significant positive association between lutein intake or levels and respiratory function. No association was found in the other two studies. In relation to respiratory mortality, one longitudinal study showed that higher lutein blood levels were associated with a decreased mortality (HR 0.77 (95% CI 0.60; 0.99), per SD increase in lutein).

CONCLUSION

The published literature suggests a possible positive association between lutein and respiratory health. However, the literature is scarce and most studies are of observational nature.

Recent Understandings of Pet Allergies

Allergic reactions to pets have been recognized for at least a hundred years. Yet our understanding of the effects of all of the interactions between pet exposures and human immune responses continues to grow. Allergists, epidemiologists, and immunologists have spent years trying to better understand how exposures to pet allergens lead to allergic sensitization (the production of allergen-specific immunoglobulin class E [IgE] antibodies) and subsequent allergic disease. A major new development in this understanding is the recognition that pet exposures consist of not only allergen exposures but also changes in microbial exposures. Exposures to certain pet-associated microbes, especially in the neonatal period, appear to be able to dramatically alter how a child’s immune system develops and this in turn reduces the risk of allergic sensitization and disease. An exciting challenge in the next few years will be to see whether these changes can be developed into a realistic preventative strategy with the expectation of significantly reducing allergic disease, especially asthma.

Birth weight and asthma incidence by asthma phenotype pattern in a racially diverse cohort followed through adolescence

OBJECTIVE

Low birth weight (LBW) has been shown to be an independent risk factor for asthma. We hypothesized that LBW would have its greatest impact on early onset disease.

METHODS

A racially diverse cohort of children born from 1983 to 1985 at two hospitals, one urban and one suburban in the same metropolitan area, and oversampled for babies weighing ≤2500 g, was identified retrospectively when the children were 6 years of age and followed periodically. At the age 17 years study visit, cohort members and their parent/guardians were separately interviewed face-to-face regarding the subject's history of asthma using the standardized ISAAC questionnaire. We measured the cumulative incidence of asthma from birth through adolescence defined by age of diagnosis and persistence/remittance.

RESULTS

Six-hundred and eighty teens (82.6% of the original cohort) were included in the analyses, 387 with LBW and 293 of normal birth weight. The prevalence of physician-diagnosed "Current Asthma" was associated with LBW (p = 0.003 for trend), with patterns stronger in males and whites. LBW was associated most strongly with Late Onset Persistent asthma (current asthma that was diagnosed after 8 years); p for trend 0.032. This trend was again most evident in males and whites. None of the asthma categories classified as "remittent" were statistically associated with LBW.

CONCLUSIONS

LBW was not associated with diagnosed asthma that remitted before age 17 years. LBW was associated with asthma diagnosis in mid-childhood that persisted through adolescence, suggesting that the asthmagenic effects of LBW can become evident post the early years of childhood and persist into adulthood.