Environmental Exposure and Childhood Atopic Dermatitis in Shanghai: A Season-Stratified Time-Series Analysis

Physical influences on the skin barrier and pathogenesis of allergy

PURPOSE OF REVIEW

As the incidence of allergic conditions has increased in recent decades, the effects of climate change have been implicated. There is also increased knowledge on the effects of other physical influences, such as scratching and Staphylococcus aureus . The skin barrier is the first line of defense to the external environment, so understanding the ways that these factors influence skin barrier dysfunction is important.

RECENT FINDINGS

Although the impact on environmental exposures has been well studied in asthma and other allergic disorders, there is now more literature on the effects of temperature, air pollution, and detergents on the skin barrier. Factors that cause skin barrier dysfunction include extreme temperatures, air pollution (including greenhouse gases and particulate matter), wildfire smoke, pollen, scratching, S. aureus, and detergents.

SUMMARY

Understanding the ways that external insults affect the skin barrier is important to further understand the mechanisms in order to inform the medical community on treatment and prevention measures for atopic conditions.

Impact of Air Pollution on Atopic Dermatitis: A Comprehensive Review

Air pollution is associated with multiple health problems worldwide, contributing to increased morbidity and mortality. Atopic dermatitis (AD) is a common allergic disease, and increasing evidence has revealed a role of air pollution in the development of atopic dermatitis. Air pollutants are derived from several sources, including harmful gases such as nitrogen dioxide (NO2), sulfur dioxide (SO2), and carbon monoxide (CO), as well as particulate matter (PM) of various sizes, and bioaerosols. Possible mechanisms linking air pollution to atopic dermatitis include damage to the skin barrier through oxidative stress, increased water loss, physicochemical injury, and an effect on skin microflora. Furthermore, oxidative stress triggers immune dysregulation, leading to enhanced sensitization to allergens. There have been multiple studies focusing on the association between various types of air pollutants and atopic dermatitis. Since there are many confounders in the current research, such as climate, synergistic effects of mixed pollutants, and diversity of study population, it is not surprising that inconsistencies exist between different studies regarding AD and air pollution. Still, it is generally accepted that air pollution is a risk factor for AD. Future studies should focus on how air pollution leads to AD as well as effective intervention measures.

Air pollution and global healthcare use for atopic dermatitis: A systematic review

Increasing air pollution is common around the world, but the impacts of outdoor air pollution exposure on atopic dermatitis (AD) are unclear. We synthesized the current global epidemiologic evidence for air pollution exposure and associated medical visits for AD among adults and children. This review followed PRISMA guidelines, and searches were conducted on PubMed, MEDLINE, Web of Science and EMBASE databases. The searches yielded 390 studies, and after screening, 18 studies around the world assessing at least 5,197,643 medical visits for AD in total were included for the final analysis. We found that exposure to particulate matter ≤2.5 μm in diameter (PM2.5 ) [(10/11) of studies], particulate matter ≤10 μm in diameter (PM10 ) (11/13), nitrogen dioxide (NO2 ) (12/14) and sulfur dioxide (SO2 ) (10/13) was positively associated with AD visits. Results were equivocal for ozone [(4/8) of studies reported positive association] and limited for carbon monoxide [(1/4) of studies reported positive association]. When stratifying results by patient age, patient sex and season, we found that the associations with particulate matter, NO2 and O3 may be affected by temperature. Exposure to selected air pollutants is associated with AD visits, and increasingly poor worldwide air quality may increase global healthcare use for AD.

Environmental Exposures may Hold the Key; Impact of Air Pollution, Greenness, and Rural/Farm Lifestyle on Allergic Outcomes

PURPOSE OF REVIEW

There has been an increased prevalence of allergy. Due to this relatively rapid rise, changes in environmental exposures are likely the main contributor. In this review, we highlight literature from the last 3 years pertaining to the role of air pollution, greenness, and the rural/farm lifestyle and their association with the development of allergic sensitization, atopic dermatitis, food allergy, and allergic rhinitis in infancy and childhood. Because asthma has a more complex pathophysiology, it was excluded from this review.

RECENT FINDINGS

Recent studies support a role for air pollution, greenness, and rural/farming lifestyle influencing atopic outcomes that continue to be defined. While many studies have examined singular environmental exposures, the interconnectedness of these exposures and others points to a need for future work to consider an individual's whole exposure. Environmental exposures' influence on atopic disease development remains an ongoing and important area of study.

Short-term effects of meteorological factors on childhood atopic dermatitis in Lanzhou, China

Atopic dermatitis (AD) is one of the leading burdens of skin disease in children globally. Meteorological factors are involved in the onset and development of AD. Several studies have examined the effects of meteorological factors on AD, but their results are inconsistent, and the understanding of the link between AD and meteorological factors remains inadequate. In this study, a total of 19,702 children aged 0 to 14 visited the outpatient clinic for AD from 2015 to 2019 in Lanzhou, China. A distributed lag nonlinear model (DLNM) applies to evaluate effects of meteorological factors on childhood AD in Lanzhou, China, and further explored age and gender differences. It was found that extremely high or low temperatures, extremely high diurnal temperature range (DTR), extremely low relative humidity (RH), and extremely high wind speed (WS) increased the risk of outpatient visits for childhood AD. Effects of extremely high DTR and extremely high WS were more intense, with maximum cumulative risks of 2.248 (95% CI 1.798, 2.811) and 3.834 (95% CI 3.086, 4.759) at lag 0-21, respectively. Furthermore, the combination of low temperature and low RH can also contribute to the higher risk of childhood AD. For extreme temperatures, children aged 7-14 years were more vulnerable. For extremely low RH, extremely high DTR and WS, boys and children aged 0-3 years were more vulnerable. Public health departments should strengthen publicity and education about how meteorological factors affect childhood AD and develop sex- and age-specific preventative measures.

The association between air pollution, meteorological factors, and daily outpatient visits for urticaria in Shijiazhuang, Hebei Province, China: a time series analysis

The associations of air pollution and meteorological factors with the outpatient visits of urticaria remain poorly studied. This study aimed to assess the association between air pollution, meteorological factors, and daily outpatient visits for urticaria in Shijiazhuang, China, during 2014-2019. Daily recordings of air pollutant concentrations, meteorological data, and outpatient visits data for urticaria were collected during the 6 years. Descriptive research methods were used to describe the distribution characteristics and demographic features of urticaria. A combination of the generalized linear regression model (GLM) and distribution lag nonlinear model (DLNM) was used to evaluate the lag association between environmental factors and daily outpatient visits for urticaria. Stratified analyses by gender (male; female) and age (< 18 years; 18-39 years; > 39 years) were further conducted. The dose-response relationship between daily urticaria visits and CO, NO₂, O₃, temperature, and relative humidity was nonlinear. High concentrations of CO, NO₂, O₃, and high temperatures increased the risk of urticaria outpatient visits. The maximum cumulative association of high concentrations of CO, NO₂, and O₃ was lag 0-14 days (CO: RR = 1.10, 95%CI: 1.06, 1.31; NO₂: RR = 1.09, 95%CI: 1.01, 1.08; O₃: RR = 1.16, 95%CI: 1.08, 1.25), and high temperatures was lag 0-7 days (RR = 1.27, 95%CI: 1.14, 1.41). Low concentrations of NO₂, O₃, and high humidity, on the other hand, act as protective factors for urticaria outpatient. The maximum cumulative association of low concentrations of NO₂ was the 0-day lag (RR = 0.97, 95%CI: 0.95, 0.99), O₃ was lag 0-5 days (RR = 0.94, 95%CI: 0.88, 0.99), and high humidity was lag 0-10 days (RR = 0.93, 95%CI: 0.89, 0.98). Stratified analyses showed that the risk of urticaria outpatient visits was higher for the males and in the < 18 years age group. In conclusion, we found that the development of urticaria in Shijiazhuang has a distinct seasonal and cyclical nature. Air pollutants and meteorological factors had varying degrees of influence on the risk of urticaria outpatient visits. This study provides indirect evidence for a link between air pollution, meteorological factors, and urticaria outpatient visits.

Gut microbiota and atopic dermatitis in children: a scoping review

BACKGROUND

Gut microbiota plays an important role in the development of atopic dermatitis (AD). We aimed to elucidate research trends in gut microbiota and AD in children, to provide evidence and insights to the clinical prevention and treatment of AD in children.

METHODS

A scoping literature review on the studies of gut microbiota and AD were conducted. Two authors independently searched Pubmed et al. databases for studies focused on gut microbiota and AD in children up to January 15, 2022. The literatures were screened and analyzed by two reviewers.

RESULTS

A total of 44 reports were finally included and analyzed. Current researches have indicated that abnormal human microecology is closely associated with AD, and the disturbance of intestinal microbiota plays an important role in the occurrence and development of AD. Probiotics can correct the microbiota disorder, have the functions of regulating immunity, antioxidant, and help to restore the microecological homeostasis. However, there is still a lack of high-quality research reports on the efficacy and safety of probiotics in the prevention and treatment of AD in children.

CONCLUSIONS

The changes of gut microbiota are essential to the development of AD in children, which may be an effective target for the prevention and treatment of AD. Future studies with larger sample size and rigorous design are needed to elucidate the effects and safety of probiotics in AD.