Epithelial barrier hypothesis: Effect of the external exposome on the microbiome and epithelial barriers in allergic disease.

Environmental exposure plays a major role in the development of allergic diseases. The exposome can be classified into internal (e.g., aging, hormones, and metabolic processes), specific external (e.g., chemical pollutants or lifestyle factors), and general external (e.g., broader socioeconomic and psychological contexts) domains, all of which are interrelated. All the factors we are exposed to, from the moment of conception to death, are part of the external exposome. Several hundreds of thousands of new chemicals have been introduced in modern life without our having a full understanding of their toxic health effects and ways to mitigate these effects. Climate change, air pollution, microplastics, tobacco smoke, changes and loss of biodiversity, alterations in dietary habits, and the microbiome due to modernization, urbanization, and globalization constitute our surrounding environment and external exposome. Some of these factors disrupt the epithelial barriers of the skin and mucosal surfaces, and these disruptions have been linked in the last few decades to the increasing prevalence and severity of allergic and inflammatory diseases such as atopic dermatitis, food allergy, allergic rhinitis, chronic rhinosinusitis, eosinophilic esophagitis, and asthma. The epithelial barrier hypothesis provides a mechanistic explanation of how these factors can explain the rapid increase in allergic and autoimmune diseases. In this review, we discuss factors affecting the planet's health in the context of the 'epithelial barrier hypothesis,' including climate change, pollution, changes and loss of biodiversity, and emphasize the changes in the external exposome in the last few decades and their effects on allergic diseases. In addition, the roles of increased dietary fatty acid consumption and environmental substances (detergents, airborne pollen, ozone, microplastics, nanoparticles, and tobacco) affecting epithelial barriers are discussed. Considering the emerging data from recent studies, we suggest stringent governmental regulations, global policy adjustments, patient education, and the establishment of individualized control measures to mitigate environmental threats and decrease allergic disease.

The effects of diet-induced weight loss on asthma control and quality of life in obese adults with asthma: a randomized controlled trial.

Objective: While the effects of obesity on asthma are yet to be fully clarified, increased fat tissue is known to increase the severity of asthma and to impair asthma control. This study evaluated the effects of diet-induced weight loss on the characteristics of asthma in obese adults with asthma.Methods: A total of 55 obese individuals (BMI ≥ 30.0) with asthma were enrolled in the study and randomized into the diet or control groups. The anthropometric measurements, asthma control test (ACT) scores, asthma quality of life questionnaire (AQLQ) scores, pulmonary function tests (PFT) and daily food consumption of the participants were recorded and compared at the baseline and at study completion.Results: The changes recorded in body weight (diet -5.2 (4, 5); control, -0.1 (1.3)), ACT score (diet 2.0 (2.0); control 0.0 (1.7)) and AQLQ score (diet 0.8 ± 0.1; control -0.02 ± 0.5) of the participants in the diet group were significantly higher than in the control group (p = 0.00). The increases in forced expiratory volume in one second (FEV1) and the forced vital capacity (FVC) measurements of the participants with weight loss of ≥5.0 percent were significant when compared to those with weight loss of <5.0 percent (p < 0.05). While total energy uptake and carbohydrate consumption at the end of study were found to be decreased in the diet group, they had increased in the control group (p < 0.05).Conclusion: Diet intervention improved asthma control and quality of life in obese patients with controlled asthma in this study. However to generalize this finding to all asthma patients, further studies including uncontrolled asthmatics are needed.

The effects of obesity on pulmonary function in adults with asthma.

OBJECTIVE: While the effects of obesity on asthma are unclear, an increased body mass index (BMI) is known to enhance the symptoms and severity of asthma and to impair asthma control. The present study evaluates the effects of nutritional habits and obesity on pulmonary function and asthma control in individuals with asthma. METHODS: This cross-sectional study included 60 obese respondents and 60 respondents with normal body weight, who were referred to pulmonology clinics over a period of 2 months. The anthropometric measurements and macro-micro nutrient consumption records of the patients in both groups were obtained, and the two groups were compared in terms of pulmonary function and asthma control test (ACT) scores. RESULTS: The mean age of the normal weight and obese respondents was 39.55 ± 11.0 and 45.1 ± 10.3 years, respectively. The ACT scores of the respondents decreased significantly with increasing BMI, waist circumference (WC), and waist-hip ratio (WHR) measurements (P < 0.05). The obese respondents had a lower mean forced vital capacity (FVC), forced expiratory volume in 1 s (FEV1), midexpiratory flow (MEF) between 25% and 75% of the maximal expiration (MEF25-75), MEF75, MEF50, MEF25, and FEV1/FVC values when compared to the respondents with normal weight (P < 0.05). The total energy and carbohydrate intake was higher in the obese respondents, while their total protein intake was lower when compared to the normal weight respondents (P < 0.05), and a significant positive correlation was found between the omega 3 intake and ACT scores of the respondents (P < 0.05). CONCLUSIONS: Pulmonary functions and ACT scores decrease with increasing BMI, WC, and WHR. Obese respondents with asthma should be referred to diet clinics to improve their asthma symptoms.

The Relationship between Dietary Inflammatory Index, Pulmonary Functions and Asthma Control in Asthmatics.

This cross-sectional study evaluates the relationship of the dietary inflammatory index (DII), a novel tool developed to measure the inflammatory capacity of a diet, with pulmonary functions and asthma control test (ACT) scores in asthmatic individuals. The study included 120 patients who were diagnosed with asthma for at least one year.  The anthropometric measurements, one-day long nutrition uptake records, pulmonary function tests, and ACT scores of the respondents were recorded and compared according to categories of the DII which was calculated from 24- hour recalls. Forced vital capacity (FVC), forced expiratory volume in one second (FEV1) and ACT scores decreased with increasing DII tertiles (p<0.05). The total energy, carbohydrate, fat, and saturated fat uptake of the participants increased in parallel to DII (p<0.05); while vitamin A, C, and E uptakes, on the other hand, decreased as DII increased (p=0.0001). In conclusion, an increase in the inflammatory potential of diet among asthmatics decreases pulmonary functions and asthma control.