Vitamin D Status Modifies the Response to Indoor Particulate Matter in Obese Urban Children with Asthma

Outdoor Air Pollution and Pediatric Respiratory Disease

Outdoor air pollution is ubiquitous, and no safe level of exposure has been identified for the most common air pollutants such as ozone and particle pollution. Children are uniquely more susceptible to the harms of outdoor air pollution, which can cause and exacerbate respiratory disease. Although challenging to identify the effects of outdoor air pollution on individual patients, understanding the basics of outdoor air pollution is essential for pediatric respiratory health care providers. This review covers basic information regarding outdoor air pollution, unique considerations for children, mechanisms for increased susceptibility, and association with incident and exacerbation of respiratory disease in children.

Vitamin D ameliorates particulate matter induced mitochondrial damages and calcium dyshomeostasis in BEAS-2B human bronchial epithelial cells

BACKGROUND

Mitochondria is prone to oxidative damage by endogenous and exogenous sources of free radicals, including particulate matter (PM). Given the role of mitochondria in inflammatory disorders, such as asthma and chronic obstructive pulmonary disease, we hypothesized that supplementation of vitamin D may play a protective role in PM-induced mitochondrial oxidative damages of human bronchial epithelial BEAS-2B cells.

METHODS

BEAS-2B cells were pretreated with 1,25(OH)2D3, an active form of vitamin D, for 1 h prior to 24-hour exposure to PM (SRM-1648a). Oxidative stress was measured by flow cytometry. Mitochondrial functions including mitochondrial membrane potential, ATP levels, and mitochondrial DNA copy number were analyzed. Additionally, mitochondrial ultrastructure was examined using transmission electron microscopy. Intracellular and mitochondrial calcium concentration changes were assessed using flow cytometry based on the expression of Fluo-4 AM and Rhod-2 AM, respectively. Pro-inflammatory cytokines, including IL-6 and MCP-1, were quantified using ELISA. The expression levels of antioxidants, including SOD1, SOD2, CAT, GSH, and NADPH, were determined.

RESULTS

Our findings first showed that 24-hour exposure to PM led to the overproduction of reactive oxygen species (ROS) derived from mitochondria. PM-induced mitochondrial oxidation resulted in intracellular calcium accumulation, particularly within mitochondria, and alterations in mitochondrial morphology and functions. These changes included loss of mitochondrial membrane integrity, disarrayed cristae, mitochondrial membrane depolarization, reduced ATP production, and increased mitochondrial DNA copy number. Consequently, PM-induced mitochondrial damage triggered the release of certain inflammatory cytokines, such as IL-6 and MCP-1. Similar to the actions of mitochondrial ROS inhibitor MitoTEMPO, 1,25(OH)2D3 conferred protective effects on mtDNA alterations, mitochondrial damages, calcium dyshomeostasis, thereby decreasing the release of certain inflammatory cytokines. We found that greater cellular level of 1,25(OH)2D3 upregulated the expression of enzymatic (SOD1, SOD2, and CAT) and non-enzymatic (GSH and NADPH) antioxidants to modulate cellular redox homeostasis.

CONCLUSION

Our study provides new evidence that 1,25(OH)2D3 acts as an antioxidant, enhancing BEAS-2B antioxidant responses to regulate mitochondrial ROS homeostasis and mitochondrial function, thereby enhancing epithelial defense against air pollution exposure.

Effect modification by maternal vitamin D status in the association between prenatal exposure to per- and polyfluoroalkyl substances and neurodevelopment in 2-year-old children

BACKGROUND

Pregnant women in the Shanghai Birth Cohort (SBC) of China faced dual threats of per- and polyfluoroalkyl substances (PFAS) exposure and vitamin D (VD) insufficiency, potentially impacting offspring neurodevelopment. However, little is known about whether maternal VD status modifies PFAS-related neurodevelopment effect.

OBJECTIVES

To explore the modifying role of maternal VD status in the effect of prenatal PFAS exposure on childhood neurodevelopment.

METHODS

We included 746 mother-child pairs from the SBC. Ten PFAS congeners and VD levels were measured in maternal blood samples collected during the first and second trimester respectively. At 2 years of age, toddlers underwent neurodevelopment assessments using Bayley-III Scales. Multivariate linear, logistic regression, and weighted quantile sum approach were used to estimate associations of Bayley-III scores with individual and mixture PFAS. We stratified participants into VD sufficient and insufficient groups and further balanced PFAS differences between these groups by matching all PFAS levels. We fitted the same statistical models in each VD group before and after matching.

RESULTS

Nearly half (46.5 %) of pregnant women were VD insufficient (<30 ng/mL). In the overall population, PFAS exposure was associated with lower language scores and an increased risk for neurodevelopmental delay, but higher cognitive scores. However, adverse associations with PFAS were mainly observed in the VD sufficient group, while the VD insufficient group showed positive cognitive score associations. Higher PFAS concentrations were found in the VD sufficient group compared to the VD insufficient group. Post-matching, adverse associations in the VD sufficient group were nullified, whereas in the VD insufficient group, positive associations disappeared and adverse associations becoming more pronounced.

CONCLUSION

In this Chinese birth cohort, high prenatal PFAS exposure and low maternal VD levels collectively heighten the risk of adverse childhood neurodevelopment. However, disentangling PFAS and VD interrelationships is crucial to avoid paradoxical findings.

Unveiling the potent effect of vitamin D: harnessing Nrf2/HO-1 signaling pathways as molecular targets to alleviate urban particulate matter-induced asthma inflammation

BACKGROUND

Asthma is the most common allergic disease characterized by an inflammatory response in the airways. Mechanismly, urban particulate matter (PM) is the most widely air pollutant associated with increased asthma morbidity and airway inflammation. Current research found that vitamin D is an essential vitamin with anti-inflammatory, antioxidant and other medical efficacy. Inadequate or deficient vitamin D often leads to the pathogenesis and stability of asthma. NGF exacerbates airway inflammation in asthma by promoting smooth muscle cell proliferation and inducing the Th2 immune response. Activation of the Nrf2/HO-1 signaling pathway can exert a protective effect on the inflammatory response in bronchial asthma. However, the specific mechanism of this pathway in PM-involved asthmatic airway smooth muscle cells remains unclear.

METHODS

Mice were sensitized and challenged with Ovalbumin (OVA) to establish an asthma model. They were then exposed to either PM, vitamin D or a combination of both, and inflammatory responses were observed. Including, acetylcholine stimulation at different concentrations measured airway hyperresponsiveness in mice. Bronchoalveolar lavage fluid (BALF) and serum were collected for TNF-α, IL-1β, IL-6, and Nerve growth factor (NGF) analysis. Additionally, lung tissues underwent histopathological examination to observe alveolar structure and inflammatory cell infiltration. Specific ELISA kits were utilized to determine the levels of the inflammatory factors TNF-α, IL-1β, IL-6, and Nerve growth factor (NGF). Nrf2/HO-1 signaling pathways were examined by western blot analysis. Meanwhile, we constructed a cell system with low HO-1 expression by lentiviral transfection of airway smooth muscle cells. The changes of Nrf2, HO-1, and NGF were observed after the treatment of OVA, PM, and Vit D were given.

RESULTS

The in vivo results showed that vitamin D significantly alleviated pathological changes in lung tissue of PM-exposed mice models. Mechanismly, vitamin D decreased substantial inflammatory cell infiltration in lung tissue, as well as the number of inflammatory cells in BALF. Furthermore, vitamin D reduced the heightened inflammatory factors including of TNF-α, IL-1β, IL-6, and NGF caused by PM exposure, and triggered the activity of nucleus Nrf2 and HO-1 in PM-exposed asthmatic mice. Notably, knockdown HO-1 weakens the Vitamin D- mediated inhibition to pollution toxicity in asthma. Importantly, in vitro experiments on OVA-stimulated mice airway smooth muscle cells, the results showed that OVA and PM, respectively, reduced Nrf2/HO-1 and increased NGF's expression, while vitamin D reversed the process. And in the HO-1 knockdown cell line of Lenti-si-HO-1 ASMCs, OVA and PM reduced Nrf2's expression, while HO-1 and NGF's expression were unchanged.

CONCLUSIONS

The above results demastrate that vitamin D downregulated the inflammatory response and the expression of NGF by regulating the Nrf2/HO-1 signaling pathways in airway smooth muscle cells, thereby showing potent anti-inflammatory activity in asthma.

The Role of Vitamins in the Pathogenesis of Asthma

Vitamins play a crucial role in the proper functioning of organisms. Disturbances of their levels, seen as deficiency or excess, enhance the development of various diseases, including those of the cardiovascular, immune, or respiratory systems. The present paper aims to summarize the role of vitamins in one of the most common diseases of the respiratory system, asthma. This narrative review describes the influence of vitamins on asthma and its main symptoms such as bronchial hyperreactivity, airway inflammation, oxidative stress, and airway remodeling, as well as the correlation between vitamin intake and levels and the risk of asthma in both pre- and postnatal life.

Exposures to Organophosphate Esters and Respiratory Morbidity among School-Aged Children with Asthma

Organophosphate esters (OPEs) are an emerging class of chemicals used in a variety of consumer products as flame retardants, plasticizers, and additives. While prior epidemiologic studies suggest that OPEs may impact respiratory health, results remain inconclusive. We examined associations between urinary biomarkers of OPEs and symptoms of respiratory morbidity in a panel study of 147 predominantly Black school-aged children with asthma living in Baltimore City, Maryland. The study consisted of up to four seasonal, week-long, in-home visits where urine samples and self-reported asthma symptoms were collected on days 4 and 7 (nsamples = 438). We quantified concentrations of nine urinary OPE biomarkers: bis(2-chloroethyl) phosphate (BCEtp), bis(1-chloro-2-propyl) phosphate (BCPP), bis(1,3-dichloro-2-propyl) phosphate (BDCIPP), di-n-butyl phosphate (DBuP), di-benzyl phosphate (DBzP), di-o-cresylphosphate (DOCP), di-p-cresylphosphate (DPCP), di-(2-propylheptyl) phthalate (DPHP), and 2,3,4,5-tetrabromo benzoic acid (TBBA). We estimated prevalence odds ratios (POR) of respiratory morbidity symptoms using logistic regression with generalized estimating equations to account for our repeated measure design. We assessed BDCIPP and DPHP as continuous (log2) concentrations and dichotomized exposure of BCEtP, DBuP, and DPCP (detect vs non-detect) based on their lower detection frequencies. We adjusted models for season, visit day, age, gender, caregiver education, health insurance type, exposure to household smoking, atopy, and PM2.5. Higher DPHP concentrations were significantly associated with odds of daytime symptoms (POR: 1.26; 95% CI: 1.04-1.53; p = 0.02) where daytime symptoms consisted of trouble breathing due to asthma, reporting bother caused by asthma, and/or limitation in activities due to asthma. DBuP detection was associated with use of rescue medication on the day of sample collection (POR: 2.36; 95% CI: 1.05-5.29; p = 0.04). We also observed several consistent, albeit non-significant (p > 0.05), positive associations for BCEtP and DPCP and respiratory morbidity measures. This is the first study to evaluate the relationship between OPE biomarkers and respiratory morbidity symptoms in children with asthma, and findings suggest that further studies are warranted to confirm whether these associations are causal.

Maternal vitamin D status modifies the effects of early life tobacco exposure on child lung function

BACKGROUND

Prior studies suggest that vitamin D may modify the effects of environmental exposures; however, none have investigated gestational vitamin D and cumulative tobacco smoke exposure (TSE) throughout pregnancy and early life.

OBJECTIVES

This study investigated the effects of early life TSE on child lung function and the modulatory effects of gestational vitamin D on this association.

METHODS

The VDAART (Vitamin D Antenatal Asthma Reduction Trial) recruited nonsmoking pregnant women and followed the mother-child pairs to age 6 years. TSE was assessed with questionnaires and plasma cotinine measurements in the mothers (10-18 and 32-38 gestational weeks) and children (1, 3, and 6 years). Cumulative TSE was calculated from the repeated cotinine measurements. 25-hydroxyvitamin D (25[OH]D) levels were measured at 10-18 and 32-38 gestational weeks. Lung function was assessed at 6 years with spirometry and impulse oscillometry.

RESULTS

Of the 476 mother-child pairs, 205 (43%) had increased cotinine levels at ≥1 time point. Cumulative TSE was associated with decreased FEV1 (β = -0.043 L, P = .018) and increased respiratory resistance at 5 Hz (R5; β = 0.060 kPa/L/s, P = .002). This association persisted in subjects with insufficient (<30 ng/mL) 25(OH)D levels throughout pregnancy (β = 0.077 kPa/L/s, P = .016 for R5) but not among those with sufficient levels throughout pregnancy.

CONCLUSIONS

Cumulative TSE from pregnancy to childhood is associated with dose- and duration-dependent decreases in child lung function at 6 years even in the absence of reported maternal smoking. Gestational vitamin D may modulate this effect and have therapeutic potential for minimizing the adverse effect of TSE on lung throughout early life.

RANDOMIZED TRIAL

Maternal Vitamin D Supplementation to Prevent Childhood Asthma (VDAART); clinicaltrials.gov identifier: NCT00920621.

The associations of particulate matter short-term exposure and serum lipids are modified by vitamin D status: A panel study of young healthy adults

Particulate matter (PM) exposure is associated to the adverse change in blood lipids. Vitamin D is beneficial to lipid metabolism, but whether vitamin D levels modifies the impact of air pollutants on lipids is unclear. The purpose of the study was to investigate if vitamin D modifies the associations of PM and serum lipids in young healthy people. From December 2017 to January 2018, a panel study with five once weekly follow-ups was conducted on 88 healthy adults aged 21.09 (1.08) (mean (SD)) years on average in Guangzhou, China. We measured serum lipids, serum 25-hydroxyvitamin D (25(OH)D) concentrations (440 blood samples in total), mass concentrations of particulate matter with diameters ≤2.5 μm (PM_2.5), ≤1.0 μm (PM_1.0), and ≤0.5 μm (PM_0.5), and number concentrations of particulate matter with diameters ≤0.2 μm (PN_0.2) and ≤0.1 μm (PN_0.1) at each follow-up. Linear mixed-effect models were applied to assess the interaction of vitamin D and size-fractionated PM short-term exposure on four lipid metrics. We found the interactions between 25(OH)D and size-fractionated PM exposure on blood lipids in different lags (lag 3 days and 4 days). An interquartile range increase in PM_2.5, PM_1.0, PM_0.5 were significantly associated with increments of 12.30%, 12.99%, and 13.66% in triglycerides (TGs) at lag 4 days at vitamin D levels <15 ng/mL group, respectively. Similar results were found for PN_0.2, PN_0.1 and low-density lipoprotein cholesterol (LDL-C). All the associations between size-fractionated PM and blood lipids were found null statistically significant in vitamin D levels ≥15 ng/mL group.

Effects of vitamin D on associations between air pollution and mental health outcomes in Korean adults: Results from the Korea National Health and Nutrition Examination Survey (KNHANES)

BACKGROUND

Evidence suggests that low individual vitamin D levels enhance adverse effects associated with air pollution on mental health conditions. The aim of this study was to identify associations between ambient air pollution exposure, mental health, and serum vitamin D status in the general population of South Korea.

METHODS

We included national representative data for 29,373 adults in the final analysis. We measured serum 25-hydroxyvitamin D concentrations to assess vitamin D status for each participant. We assessed mental health factors (i.e., perceived stress, depressive symptoms, and suicidal ideation), and analyzed associations between these factors and individuals' annual average exposures to air pollutants, including particulate matter with an aerodynamic diameter ≤ 10 μm (PM₁₀), nitrogen dioxide (NO₂), sulfur dioxide, and carbon monoxide (CO).

RESULTS

Using an adjusted model, we found PM₁₀ affected mental health outcomes, such as perceived stress (odds ratio [OR] = 1.04; 95 % confidence interval [CI] = 1.00-1.09), depression symptoms (OR = 1.12; 95 % CI = 1.06-1.18), and suicidal ideation (OR = 1.11; 95 % CI = 1.05-1.17). Effects of the pollutants NO₂ and CO were significant only in the group with perceived stress and depressive symptoms. PM₁₀ and NO₂ exposures were significantly associated with increased odds of adverse mental health in participants with vitamin D deficiency.

LIMITATIONS

Since the cross-sectional design of KNHANES data, it is not possible to evaluate the causal relationship between air pollution exposure, vitamin D status and mental health.

CONCLUSIONS

This study results suggest that associations between ambient air pollution and mental health outcomes were stronger in participants with vitamin D deficiency.

Maternal exposure to urinary polycyclic aromatic hydrocarbons (PAH) in pregnancy and childhood asthma in a pooled multi-cohort study

BACKGROUND

Prenatal exposure to polycyclic aromatic hydrocarbons (PAH) may increase risk of pediatric asthma, but existing human studies are limited.

OBJECTIVES

We estimated associations between gestational PAHs and pediatric asthma in a diverse US sample and evaluated effect modification by child sex, maternal asthma, and prenatal vitamin D status.

METHODS

We pooled two prospective pregnancy cohorts in the ECHO PATHWAYS Consortium, CANDLE and TIDES, for an analytic sample of N = 1296 mother-child dyads. Mono-hydroxylated PAH metabolites (OH-PAHs) were measured in mid-pregnancy urine. Mothers completed the International Study on Allergies and Asthma in Childhood survey at child age 4-6 years. Poisson regression with robust standard errors was used to estimate relative risk of current wheeze, current asthma, ever asthma, and strict asthma associated with each metabolite, adjusted for potential confounders. We used interaction models to assess effect modification. We explored associations between OH-PAH mixtures and outcomes using logistic weighted quantile sum regression augmented by a permutation test to control Type 1 errors.

RESULTS

The sociodemographically diverse sample spanned five cities. Mean (SD) child age at assessment was 4.4 (0.4) years. While there was little evidence that either individual OH-PAHs or mixtures were associated with outcomes, we observed effect modification by child sex for most pairs of OH-PAHs and outcomes, with adverse associations specific to females. For example, a 2-fold increase in 2-hydroxy-phenanthrene was associated with current asthma in females but not males (RRfemale = 1.29 [95 % CI: 1.09, 1.52], RRmale = 0.95 [95 % CI: 0.79, 1.13]; pinteraction = 0.004). There was no consistent evidence of modification by vitamin D status or maternal asthma.

DISCUSSION

This analysis, the largest cohort study of gestational PAH exposure and childhood asthma to date, suggests adverse associations for females only. These preliminary findings are consistent with hypothesized endocrine disruption properties of PAHs, which may lead to sexually dimorphic effects.

Melatonin alleviates PM2.5 -induced glucose metabolism disorder and lipidome alteration by regulating endoplasmic reticulum stress

Exposure to fine particulate matter (PM_2.5 ) was associated with an increased incidence of liver metabolic disease. Melatonin has been shown to prevent liver glucolipid metabolism disorders. However, whether melatonin could rescue PM_2.5 -induced liver metabolic abnormalities remains uncertain. This study was to evaluate the mitigating effect of melatonin on PM_2.5 -accelerated hepatic glucose metabolism imbalance in vivo and in vitro. Schiff periodic acid shiff staining and other results showed that PM_2.5 led to a decrease in hepatic glycogen reserve and an increase in glucose content, which was effectively alleviated by melatonin. Targeted lipidomics is used to identify lipid biomarkers associated with this process, including glycerolipids, glycerophospholipids, and sphingolipids. In addition, gene microarray and quantitative polymerase chain reaction analysis of ApoE^-/- mice liver suggested that PM_2.5 activated the miR-200a-3p and inhibited DNAJB9, and the targeting relationship was verified by luciferase reports for the first time. Further investigation demonstrated that DNAJB9 might motivate endoplasmic reticulum (ER) stress by regulating Ca²⁺ homeostasis, thus altering the protein expression of GSK3B, FOXO1, and PCK2. Meanwhile, melatonin effectively inhibited miR-200a-3p and glucose metabolism disorder. Knockout of miR-200a-3p in L02 cells revealed that miR-200a-3p is indispensable in the damage of PM_2.5 and the therapeutic effect of melatonin. In summary, melatonin alleviated PM_2.5 -induced liver metabolic dysregulation by regulating ER stress via miR-200a-3p/DNAJB9 signaling pathway. Our data provide a prospective targeted therapy for air pollution-related liver metabolism disorders.

Obesity-related asthma in children and adolescents

There is substantial epidemiological and experimental evidence of an obesity-related asthma phenotype. Compared to children of healthy weight, children with obesity are at higher risk of asthma. Children with obesity who have asthma have greater severity and poorer control of their asthma symptoms, more frequent asthma exacerbations, and overall lower asthma-related quality of life than children with asthma who have a healthy weight. In this Review, we examine some of the latest evidence on the characteristics of this phenotype and its main underlying mechanisms, including genetics and genomics, changes in airway mechanics and lung function, sex hormone differences, alterations in immune responses, systemic and airway inflammation, metabolic dysregulation, and modifications in the microbiome. We also review current recommendations for the treatment of these children, including in the management of their asthma, and current evidence for weight loss interventions. We then discuss initial evidence for potential novel therapeutic approaches, such as dietary modifications and supplements, antidiabetic medications, and statins. Finally, we identify knowledge gaps and future directions to improve our understanding of asthma in children with obesity, and to improve outcomes in these susceptible children. We highlight important needs, such as designing paediatric-specific studies, implementing large multicentric trials with standardised interventions and outcomes, and including racial and ethnic groups along with other under-represented populations that are particularly affected by obesity and asthma.

Vitamin D Supplementation and Allergic Diseases during Childhood: A Systematic Review and Meta-Analysis

We performed a systematic review and meta-analysis to investigate the effects of vitamin D (VitD) supplementation on children with allergic diseases. MEDLINE, Embase, Web of Science, the Cochrane library, and three Chinese databases were searched up to 15 August 2022. Randomized controlled trials (RCTs) comparing a VitD supplementation versus a placebo for children with allergic diseases were included. Thirty-two RCTs with 2347 participants were included. VitD supplementation did not reduce the risk of asthma exacerbations in children compared with placebo overall (risk ratio (RR) = 0.84, 95% confidence interval (CI): 0.65 to 1.08, p = 0.18), but reduced the risk of asthma exacerbation in children with baseline serum 25(OH)D of <10 ng/mL compared with placebo (RR = 0.48, 95% CI: 0.28 to 0.83, p = 0.009). VitD supplementation significantly reduced Scoring Atopic Dermatitis or the Eczema Area and Severity Index scores in children with atopic dermatitis compared with placebo (standard mean difference = −0.5, 95% CI: −0.87 to −0.12, p = 0.009). VitD supplementation also reduced the symptom-medication score in children with allergic rhinitis compared with placebo (mean (standard deviation): 43.7 (3.3) vs. 57.8 (4.4), p = 0.001). In conclusion, VitD supplementation did not reduce asthma exacerbation risk in children overall but may reduce asthma exacerbation risk in children with serum 25(OH)D concentration < 10 ng/mL. VitD supplementation reduces the severity of atopic dermatitis and symptoms of allergic rhinitis in children.

Asthma interactions between obesity and other risk factors

OBJECTIVE

To review and critically discuss published evidence on interactions between obesity and selected risk factors on asthma in children and adults, and to discuss potential future directions in this field.

DATA SOURCES

National Library of Medicine (via PubMed) STUDY SELECTION: A literature search was conducted for human studies on obesity and selected interactions (with sex, race and ethnicity, socioeconomic status, indoor and outdoor pollutants, depression, anxiety, and diet) on asthma. Studies that were published in English and contained a full text were considered for inclusion in this review.

RESULTS

Current evidence supports interactions between obesity and outdoor and indoor air pollutants (including second-hand smoke [SHS]) on enhancing asthma risk, although there are sparse data on the specific pollutants underlying such interactions. Limited evidence also suggests that obesity may modify the effects of depression or anxiety on asthma, whereas little is known about potential interactions between obesity and sex-hormone levels or dietary patterns.

CONCLUSION

Well-designed observational prospective studies (eg, for pollutants and sex hormones) and randomized clinical trials (eg, for the treatment of depression) should help establish the impact of modifying coexisting exposures to reduce the harmful effects of obesity on asthma. Such studies should be designed to have a sample size that is large enough to allow adequate testing of interactions between obesity and risk factors that are identified a priori and thus, well characterized, using objective measures and biomarkers (eg, urinary or serum cotinine for SHS, epigenetic marks of specific environmental exposures).

Variability and predictors of urinary organophosphate ester concentrations among school-aged children

Organophosphate esters (OPE) are flame retardants and plasticizers used in a wide range of consumer products. Despite their widespread use, few studies have characterized pediatric exposures. We assessed variability and predictors of OPE exposures in a cohort panel study of 179 predominantly Black school-aged children with asthma in Baltimore City, MD. The study design included up to four seasonal week-long in-home study visits with urine sample collection on days 4 and 7 of each visit (nsamples = 618). We quantified concentrations of 9 urinary OPE biomarkers: bis(2-chloroethyl) phosphate (BCEtp), bis(1-chloro-2-propyl) phosphate, bis(1,3-dichloro-2-propyl) phosphate (BDCPP), di-benzyl phosphate (DBuP), di-benzyl phosphate, di-o-cresylphosphate, di-p-cresylphosphate (DPCP), di-(2-propylheptyl) phthalate (DPHP), 2,3,4,5-tetrabromo benzoic acid. We assessed potential predictors of exposure, including demographic factors, household characteristics, and cleaning behaviors. We calculated Spearman/tetrachoric correlations and intraclass correlation coefficients (ICCs) to examine within-week and seasonal intra-individual variability, respectively. We assessed OPE predictors using linear models for continuous log2 concentrations (BDCPP and DPHP) and logistic models for odds of detection (BCEtP, DBuP, DPCP), with generalized estimating equations to account for repeated measures. For all OPEs, we observed moderate within-week correlations (rs: 0.31-0.63) and weak to moderate seasonal reliability (ICC: 0.18-0.38). BDCPP and DPHP concentrations were higher in the summer compared to other seasons. DPHP concentrations were lower among males than females (%diff: -53.5%; 95% CI: -62.7, -42.0) and among participants spending >12 h/day indoors compared to ≤12 h (%diff: -20.7%; 95% CI: -32.2, -7.3). BDCPP concentrations were lower among children aged 8-10 years compared to 5-7 years (%diff: -39.1%; 95% CI: -55.9, -15.9) and higher among children riding in a vehicle on the day of sample collection compared to those who had not (%diff: 28.5%; 95% CI: 3.4, 59.8). This study is the first to characterize within-week and seasonal variability and identify predictors of OPE biomarkers among Black school-aged children, a historically understudied population.

Exposure to outdoor and indoor air pollution and risk of overweight and obesity across different life periods: A review

Due to the highly evolved industrialization and modernization, air quality has deteriorated in most countries. As reported by the World Health Organization (WHO), air pollution is now considered as one of the major threats to global health and a principal risk factor for noncommunicable diseases. Meanwhile, the increasing worldwide prevalence of overweight and obesity is attracting more public attentions. Recently, accumulating epidemiological studies have provided evidence that overweight and obesity may be partially attributable to environmental exposure to air pollution. This review summarizes the epidemiological evidence for the correlation between exposure to various outdoor and indoor air pollutants (mainly particulate matter (PM), nitrogen oxides (NO_x), ozone (O₃), and polycyclic aromatic hydrocarbons (PAHs)) and overweight and obesity outcomes in recent years. Moreover, it discusses the multiple effects of air pollution during exposure periods throughout life and sex differences in populations. This review also describes the potential mechanism underlying the increased risk of obesity caused by air pollution, including inflammation, oxidative stress, metabolic imbalance, intestinal flora disorders and epigenetic modifications. Finally, this review proposes macro- and micro-measures to prevent the negative effects of air pollution exposure on the obesity prevalence.

Melatonin Alleviates PM2.5-Induced Hepatic Steatosis and Metabolic-Associated Fatty Liver Disease in ApoE-/- Mice

Background

Exposure to fine particulate matter (PM_2.5) is associated with the risk of developing metabolic-associated fatty liver disease (MAFLD). Melatonin is the main secreted product of the pineal gland and has been reported to prevent hepatic lipid metabolism disorders. However, it remains uncertain whether melatonin could protect against PM_2.5-induced MAFLD.

Methods and Results

The purpose of our study was to investigate the mitigating effects of melatonin on hepatic fatty degeneration accelerated by PM_2.5 in vivo and in vitro. Histopathological analysis and ultrastructural images showed that PM_2.5 induced hepatic steatosis and lipid vacuolation in ApoE^−/− mice, which could be effectively alleviated by melatonin administration. Increased ROS production and decreased expression of antioxidant enzymes were detected in the PM_2.5-treated group, whereas melatonin showed recovery effects after PM_2.5-induced oxidative damage in both the liver and L02 cells. Further investigation revealed that PM_2.5 induced oxidative stress to activate PTP1B, which in turn had a positive feedback regulation effect on ROS release. When a PTP1B inhibitor or melatonin was administered, SP1/SREBP-1 signalling was effectively suppressed, while Nrf2/Keap1 signalling was activated in the PM_2.5-treated groups.

Conclusion

Our study is the first to show that melatonin alleviates the disturbance of PM_2.5-triggered hepatic steatosis and liver damage by regulating the ROS-mediated PTP1B and Nrf2 signalling pathways in ApoE^−/− mice. These results suggest that melatonin administration might be a prospective therapy for the prevention and treatment of MAFLD associated with air pollution.

Association between Diet Quality and Adolescent Wheezing: Effect Modification by Environmental Tobacco Smoke Exposure

RATIONALE

Protective effects of a high quality diet on respiratory health, particularly among youths exposed to environmental tobacco smoke (ETS), are unknown.

OBJECTIVES

To assess if a higher quality diet is associated with improved respiratory symptoms and lung function among adolescents, and if these associations are modified by ETS exposure.

METHODS

This was a cross-sectional study on 7,026 nonsmoking adolescents of the 2003-2012 National Health and Nutrition Examination Survey. Diet quality was assessed using the Healthy Eating Index-2010 score (HEI-2010), categorized into quintiles. ETS exposure was measured using serum cotinine, dichotomized as high (>2.99 ng/ml) or low (≤2.99 ng/ml). Outcomes included the presence of wheezing and cough symptoms in the past 12 months, and in a sub-group, spirometric lung function. Survey-design adjusted logistic and linear models evaluated associations between diet and 1) respiratory symptoms and 2) lung function, respectively, and assessed the interaction between HEI-2010 and serum cotinine.

RESULTS

While there were no significant associations between diet quality and respiratory symptoms, there was a significant interaction between HEI-2010 and serum cotinine on wheezing (pint = 0.011). In models stratified by serum cotinine, adolescents with high serum cotinine and the healthiest diet (5th quintile HEI-2010) experienced lower wheezing odds (OR, 0.10; 95% CI, 0.02-0.61), compared to those with the poorest diet (1st quintile HEI-2010). In contrast, among adolescents with low serum cotinine, there were no significant differences in any respiratory symptoms between those with the highest, compared to the lowest diet quality. Of the sub-group with spirometry data (n = 3,166), there was a trend towards better lung function with improving diet quality, although this did not achieve statistical significance. There was no effect modification by ETS exposure on the relationship between diet quality and lung function.

CONCLUSIONS

Consuming a higher quality diet was associated with lower wheezing odds in adolescents with substantial ETS exposure. While longitudinal studies are needed, public health interventions to improve diet quality in vulnerable, environmentally-exposed populations merit consideration.

Fine particulate matter, vitamin D, physical activity, and major depressive disorder in elderly adults: Results from UK Biobank

OBJECTIVE

The present study aims to investigate the association between PM2.5 exposure and major depressive disorder, and to examine whether vitamin D and physical activity could attenuate the impact of PM2.5 on major depressive disorder.

METHODS

39168 elderly adults (age≥60 years) who had valid estimates on exposure of PM2.5 in 2010 and data on major depressive disorder were extracted from the UK Biobank. Major depressive disorder was assessed by lifetime experience of mild, moderate, and severe major depression with validated instruments. Logistic regression models were used to estimate the association between PM2.5 exposure and major depressive disorder.

RESULTS

A total of 9079 participants had major depressive disorder, with a prevalence of 23.2%. The odds ratio (OR) of major depressive disorder was 1.096 (1.023, 1.175) for participants in the highest quartile compared with the lowest quartile of PM2.5. The correlation of PM2.5 with major depressive disorder generally increased with the decreasing levels of vitamin D. For instance, in participants with the highest quartile of PM2.5, the corresponding ORs were 1.141 (0.951, 1.369), 1.232 (1.027, 1.478), 1.286 (1.072, 1.543), and 1.390 (1.159, 1.667) for those who had adequate, desirable, insufficient, and deficient levels of vitamin D, respectively. Additionally, significant modification effects of physical activity on the relationship between PM2.5 and major depressive disorder were also observed.

CONCLUSIONS

Our study suggests that high levels of vitamin D and physical activity may attenuate the relationship between PM2.5 and major depressive disorder among elderly adults.

Pediatric Obesity-Related Asthma: The Role of Nutrition and Nutrients in Prevention and Treatment

Childhood obesity rates have dramatically risen in numerous countries worldwide. Obesity is likely a factor in increased asthma risk, which is already one of the most widespread chronic respiratory pathologies. The pathogenic mechanism of asthma risk has still not yet been fully elucidated. Moreover, the role of obesity-related inflammation and pulmonary overreaction to environmental triggers, which ultimately result in asthma-like symptoms, and the importance of dietary characteristics is well recognized. Diet is an important adjustable element in the asthma development. Food-specific composition of the diet, in particular fat, sugar, and low-quality nutrients, is likely to promote the chronic inflammatory state seen in asthmatic patients with obesity. An unbalanced diet or supplementation as a way to control asthma more efficiently has been described. A personalized dietary intervention may improve respiratory symptoms and signs and therapeutic response. In this narrative review, we presented and discussed more recent literature on asthma associated with obesity among children, focusing on the risk of asthma among children with obesity, asthma as a result of obesity focusing on the role of adipose tissue as a mediator of systemic and local airway inflammation implicated in asthma regulation, and the impact of nutrition and nutrients in the development and treatment of asthma. Appropriate early nutritional intervention could possibly be critical in preventing and managing asthma associated with obesity among children.

The Effect of Particulate Matter Reduction by Indoor Air Filter Use on Respiratory Symptoms and Lung Function: A Systematic Review and Meta-analysis

PURPOSE

Exposure to particulate matter (PM) is a key public health issue, but effective intervention has not yet been established. A systematic literature review and meta-analysis has been conducted to assess the relationship between the use of air filters, one of the most commonly studied interventions, and respiratory outcomes in patients with chronic respiratory diseases.

METHODS

We systematically reviewed intervention studies on PM using PubMed, EMBASE, and Cochrane databases up to September 2019. Studies that included data on PM concentration changes and respiratory symptoms or lung function in patients with respiratory diseases were eligible for inclusion. Effect estimates were quantified separately using the random-effects model.

RESULTS

Six studies were included in the quantitative analysis. Air filter use reduced indoor PM2.5 by 11.45 µg/m³ (95% confidence interval [CI], 6.88, 16.01 µg/m³). Air filter use was not associated with improvements in respiratory symptoms in 5 of the 6 studies or significant changes in the predicted forced expiratory volume in one second (FEV1) (mean change, -1.77%; 95% CI, -8.25%, 4.71%). Air filter use was associated with improved peak expiratory flow rate by 5.86 (95% CI, 3.5, 8.19 of standardized difference).

CONCLUSIONS

The findings of this systematic review suggest that air filters may reduce indoor PM and increase peak expiratory rate in asthmatic patients. However, most studies showed no significant effects of air filters on respiratory symptoms or FEV1. Further studies in regions with high-density PM may provide additional information on this issue.

TRIAL REGISTRATION

PROSPERO Identifier: CRD42020156258.

Long-term exposure to fine particulate matter and incident asthma among elderly adults

RATIONALE

Although an association of fine particulate matter (PM_2.5) with asthma incidence has been assumed, there is insufficient evidence regarding the effect of long-term exposure to PM_2.5 on incident asthma among elderly adults.

OBJECTIVES

This study aimed to investigate an association between long-term exposure to PM_2.5 and incident asthma among elderly adults in South Korea.

METHODS

Adults ≥65 years of age (n = 1,220,645) who did not visit hospitals for asthma during a washout period (between 2008 and 2010) were followed up until 2016 using data from the National Health Insurance System in South Korea. Incident asthma was defined as the number of patients with a primary diagnostic code of asthma who visited hospitals more than twice. We linked the health data with district-level PM_2.5 concentrations and estimated hazard ratios (HRs) and 95% confidence intervals (CIs) for incident asthma after adjusting for potential confounders in time-varying Cox proportional hazard models.

MEASUREMENTS AND MAIN RESULTS

Over 5,942,256 person-years, 54,522 patients developed asthma, with an incidence of 9.2 cases/1000 person-years. A 10 μg/m³ increase in the 36-month mean PM_2.5 concentration was significantly associated with a 9% increase in incident asthma (HR = 1.09, 95% CI: 1.04-1.14). This association was found to be robust for different definitions of incident asthma and washout periods.

CONCLUSION

Long-term exposure to PM_2.5 was associated with the incidence of asthma in elderly adults. This finding provides evidence of an association between PM_2.5 and adult-onset asthma.

Childhood Origins of Adult Lung Disease as Opportunities for Prevention

Prenatal and childhood exposures have been shown to impact lung development, lung function trajectory, and incidence and prevalence of respiratory disease. Early life may serve as a window of susceptibility to such exposures, with the potential to influence lifelong respiratory health. Risk factors encountered in early life with potentially durable impact on lung health include prematurity, respiratory viral illness, allergen sensitization and exposure, tobacco use and exposure, indoor and outdoor pollution, diet, and obesity. These exposures vary in the extent to which they are modifiable, and interventions aimed at reducing harmful exposures range from individual-level behavior modification to policy initiatives implemented to promote population health. For many exposures, including tobacco-related exposures, multilevel interventions are needed. Future research is needed to provide insight as to early-life interventions to promote optimal lung growth and prevent development of chronic respiratory disease. Clinicians should play an active role, assisting individual patients in avoiding known detrimental exposures including maternal smoking during pregnancy and initiation of active smoking. Clinicians can be empowered by evidence to support policies promoting reduction of population-level risk factors, such as restriction on electronic cigarette sales and legislation to uphold air quality standards, to encourage attainment of maximal lung function and reduce risk of chronic lung disease.

The role of nutrition in asthma prevention and treatment

Asthma is a chronic respiratory condition characterized by airway inflammation and hyperreactivity. Prevalence has continued to rise in recent decades as Western dietary patterns have become more pervasive. Evidence suggests that diets emphasizing the consumption of plant-based foods might protect against asthma development and improve asthma symptoms through their effects on systemic inflammation, oxidation, and microbial composition. Additionally, increased fruit and vegetable intake, reduced animal product consumption, and weight management might mediate cytokine release, free radical damage, and immune responses involved in the development and course of asthma. The specific aim of this review paper is to examine the current literature on the associations between dietary factors and asthma risk and control in children and adults. Clinical trials examining the mechanism(s) by which dietary factors influence asthma outcomes are necessary to identify the potential use of nutritional therapy in the prevention and management of asthma.

Oxidative stress and obesity-related asthma

Obesity is an asthma comorbidity associated with poor control, increased exacerbation risk and reduced response to inhaled and systemic corticosteroids. It affects children and adults differentially. In those with early onset asthma, it associated with increased eosinophilic inflammation, whereas in late onset, it correlates with lower nitric oxide (NO) and predominantly non-T2 inflammation. There are probably multiple pathways by which obesity impacts asthma; airway and systemic oxidative stress has been proposed as a mechanism that could potentially explain the obesity mediated increased comorbidity and poor response to treatment. More likely than not, oxidative stress is an epiphenomenon of a very diverse set of processes driven by complex changes in airway and systemic metabolism. This article provides a comprehensive overview of the clinical, metabolic, pathophysiological and therapeutic aspects of oxidative stress in patients with obesity and asthma.

Obesity-related asthma in children: A role for vitamin D

Excess adipose tissue predisposes to an enhanced inflammatory state and can contribute to the pathogenesis and severity of asthma. Vitamin D has anti-inflammatory properties and low-serum levels are seen in children with asthma and in children with obesity. Here we review the intersection of asthma, obesity, and hypovitaminosis D in children. Supplementation with vitamin D has been proposed as a simple, safe, and inexpensive adjunctive therapy in a number of disease states. However, little research has examined the pharmacokinetics of vitamin D and its therapeutic potential in children who suffer from obesity-related asthma.

Prenatal PM2.5 exposure and vitamin D-associated early persistent atopic dermatitis via placental methylation

BACKGROUND

The effects of prenatal particulate matter with an aerodynamic diameter ranging from 0.1 μm to 2.5 μm (PM_2.5) and vitamin D on atopic dermatitis (AD) phenotypes have not been evaluated. DNA methylation and cord blood (CB) vitamin D could represent a plausible link between prenatal PM_2.5 exposure and AD in an offspring.

OBJECTIVE

To determine the critical windows of prenatal PM_2.5 exposure on the AD phenotypes, if vitamin D modulated these effects, and if placental DNA methylation mediated these effects on AD in offspring.

METHODS

Mother-child pairs were enrolled from the birth cohort of the Cohort for Childhood Origin of Asthma and allergic diseases (COCOA) study. PM_2.5 was estimated by land-use regression models, and CB vitamin D was measured by chemiluminescence immunoassay. AD was identified by the parental report of a physician's diagnosis. We defined the following 4 AD phenotypes according to onset age (by the age of 2 years) and persistence (by the age of 3 years): early-onset transient and persistent, late onset, and never. Logistic regression analysis and Bayesian distributed lag interaction model were used. DNA methylation microarray was analyzed using an Infinium Human Methylation EPIC BeadChip (Illumina, San Diego, California) in placenta.

RESULTS

PM_2.5 exposure during the first trimester of pregnancy, especially during 6 to 7 weeks of gestation, was associated with early-onset persistent AD. This effect increased in children with low CB vitamin D, especially in those with PM_2.5 exposure during 3 to 7 weeks of gestation. AHRR (cg16371648), DPP10 (cg19211931), and HLADRB1 (cg10632894) were hypomethylated in children with AD with high PM_2.5 and low CB vitamin D.

CONCLUSION

Higher PM_2.5 during the first trimester of pregnancy and low CB vitamin D affected early-onset persistent AD, and the most sensitive window was 6 to 7 weeks of gestation. Placental DNA methylation mediated this effect.

Occupational risk prevention, education and support in black, Asian and ethnic minority health worker in the COVID-19 pandemic

The onset of the COVID-19 in the UK has resulted in an inordinate amount of deaths affecting Black, Asian and Ethnic Minority (BAME) healthcare workers. The occupational risk to this group is thought to be a contributory factor, but other factors include race, genetics, medical co-morbidities, socio-economic status, and access to personal protection equipment. Why COVID-19 appears to be more deadly in BAME members remains unknown, but the UK government is investigating this now. It does appear that certain factors may worsen the disease process in BAME members, but which ones are pertinent to prevention remain to be determined, until a vaccine is available. Thus, the onus should rest on risk prevention, education, and support for all.

Some of the safety strategies that may be instituted to help guide those in the workplace include education, treating potential therapeutic targets and ensuring protection in the working environment. The consideration of a compensation scheme, for families of healthcare workers that have suffered because of COVID-19, would go some way to support the recovery process.

Suboptimal Serum 25-Hydroxy-Vitamin D Is Associated with a History of Recent Disease Exacerbation in Pediatric Patients with Bronchial Asthma or Asthma-Suggestive Recurrent Wheezing

Even though vitamin D is widely acknowledged as having a potential immunomodulatory role in asthma, its exact beneficial mechanisms are yet to be clarified. An optimal serum 25-hydroxy-vitamin D (25-OH-VitD) level in pediatric asthma patients might not rely solely on the effect of dose-dependent vitamin D₃ intake, but might also be influenced by factors related to insufficient asthma control. We aimed to survey the prevalence of serum 25-OH-VitD deficiency and analyze whether suboptimal levels were associated with asthma severity factors. The current cross-sectional study enrolled 131 pediatric asthma or asthma-suggestive recurrent wheezing patients, for whom serum 25-OH-VitD, IgE, and eosinophil count were assessed. The prevalence of suboptimal serum 25-OH-VitD was 58.8%. A suboptimal vitamin D status was associated with asthma exacerbation in the previous month (p = 0.02). Even under seasonal oral vitamin D₃ supplementation, patients with a positive history of asthma attack in the previous four weeks presented significantly lower serum 25-OH-VitD concentrations, compared to their peers with no disease exacerbation. In conclusion, sequential measurements of serum 25-OH-VitD might prove useful for future studies evaluating the dynamic changes in vitamin D₃ status in regard to asthma, especially in symptomatic patients.

Dibutyl phthalate aggravated asthma-like symptoms through oxidative stress and increasing calcitonin gene-related peptide release

Dibutyl phthalate (DBP) is one of the most ubiquitous phthalate esters found in everyday products, and is receiving increased attention as an immunologic adjuvant. However, information regarding DBP-aggravated allergic asthma is still limited. This study used a mouse model sensitized with ovalbumin (OVA) to determine any adverse effects of DBP on allergic asthma. Our results reveal that allergic asthmatic mice exposed to DBP for an extended period had a significant increase in inflammatory cell infiltration; a significant increase in levels of serum immunoglobulin and T helper 2 cell (Th2) and T helper 17 cell (Th17) cytokines in lung tissue; and significant changes in lung histology and AHR, all of which are typical asthmatic symptoms. The levels of oxidative stress and levels of the neuropeptide, calcitonin gene related peptide (CGRP), were also elevated after DBP exposure. Interestingly, blocking oxidative stress by administering melatonin (MT) not only reduced oxidative stress and CGRP levels, but also ameliorated the asthmatic symptoms. Collectively, these results show that DBP exacerbates asthma-like pathologies by increasing the expression of CGRP mediated by oxidative stress.

Addressing the impact of ethnicity on asthma care

PURPOSE OF REVIEW

In asthma, there is an increasing focus on personalizing treatment by targeting treatable traits. Ethnicity has effects on many biological and behavioural traits, and so is an important consideration when personalizing asthma care. This review has particular relevance in light of current patterns of international migration, which are leading to unprecedented levels of ethnic heterogeneity in many geographic regions.

RECENT FINDINGS

This review examines the effect of ethnicity on three key domains - biological traits, behavioural traits and health system behaviour. Ethnicity influences asthma biology by affecting biomarker reference ranges, response to drug therapy and asthma phenotypes. Ethnicity impacts behavioural traits through its effects on psychosocial well being, adherence and asthma self-management. Ethnic minorities are often disadvantaged with regards to healthcare access and healthcare interactions.

SUMMARY

Concerted action is needed to address current issues around behavioural traits and healthcare behaviour, which are influenced by ethnicity. More research is required to understand the impact of ethnicity on asthma biology, especially the interplay between genetic and environmental influences on asthma, and the differential response to asthma therapies.

Structural and Social Determinants of Health in Asthma in Developed Economies: a Scoping Review of Literature Published Between 2014 and 2019

PURPOSE OF REVIEW

Using the WHO Conceptual Framework for Action on the Social Determinants of Health, this review provides a discussion of recent epidemiologic, mechanistic, and intervention studies of structural and social determinants of health and asthma outcomes covering the period from 2014 to 2019.

RECENT FINDINGS

A majority of studies and interventions to date focus on the intermediary determinants of health (e.g., housing), which as the name suggests, exist between the patient and the upstream structural determinants of health (e.g., housing policy). Race/ethnicity remains a profound social driver of asthma disparities with cumulative risk from many overlapping determinants. A growing number of studies on asthma are beginning to elucidate the underlying mechanisms that connect social determinants to human disease. Several effective interventions have been developed, though a need for large-scale policy research and innovation remains. Strong evidence supports the key role of the structural determinants, which generate social stratification and inequity, in the development and progression of asthma; yet, interventions in this realm are challenging to develop and therefore infrequent. Proximal, intermediary determinants have provided a natural starting point for interventions, though structural interventions have the most potential for major impact on asthma outcomes. Further research to investigate the interactive effect of multiple determinants, as well as intervention studies, specifically those that are cross-sector and propose innovative strategies to target structural determinants, are needed to address asthma morbidities, and more importantly, close the asthma disparity gap.

The Journal of Allergy and Clinical Immunology: In Practice 2019 Highlights

This article provides highlights of the clinically impactful original studies and reviews published in The Journal of Allergy and Clinical Immunology: In Practice in 2019 on the subjects of anaphylaxis, asthma, dermatitis, drug allergy, food allergy, immunodeficiency, immunotherapy, rhinitis/sinusitis, and urticaria/angioedema/mast cell disorders. Within each topic, practical aspects of diagnosis and management are emphasized. Treatments discussed include lifestyle modifications, allergen avoidance therapy, positive and negative effects of pharmacologic therapy, and various forms of immunologic and desensitization management. We designed this review to help readers consolidate and use this extensive and practical knowledge for the benefit of their patients.

The Role and Potential Pathogenic Mechanism of Particulate Matter in Childhood Asthma: A Review and Perspective

Asthma, the most common chronic respiratory disease in children, affects numerous people worldwide. Accumulating evidence suggests that exposure to high levels of particulate matter (PM), either acutely or chronically, is associated with the exacerbation and incidence of pediatric asthma. However, the detailed pathogenic mechanisms by which PM contributes to the incidence of asthma remain largely unknown. In this short review, we summarize studies of relationships between PM and pediatric asthma and recent advances on the fundamental mechanisms of PM-related asthma, with emphases on cell death regulation and immune system responses. We further discuss the inadequacy of current studies and give a perspective on the prevention strategies for pediatric asthma.

The Immunomodulatory Role of Vitamin D in Respiratory Diseases

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The growing interest in the new role of vitamin D, particularly as an immunomodulatory factor, has spurred basic research and the development of clinical trials to better understand the influence of supplementation on various diseases. Vitamin D is an important nutrient factor in human health due to its role in calcium metabolism regulation, cellular growth, differentiation and its fundamental discovered activity in immune functions. It has influenced different diseases, particularly inflammatory and autoimmune diseases, through immune response regulation, modulating innate and adaptive immunity.

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The aim of this review was to explore the role of vitamin D in the main respiratory diseases in children such as asthma, chronic rhinosinusitis, cystic fibrosis and recurrent respiratory infections.