The Roles of MicroRNAs in Asthma and Emerging Insights into the Effects of Vitamin D3 Supplementation.

Asthma is one of the most common chronic non-communicable diseases worldwide, characterized by variable airflow limitation secondary to airway narrowing, airway wall thickening, and increased mucus resulting from chronic inflammation and airway remodeling. Current epidemiological studies reported that hypovitaminosis D is frequent in patients with asthma and is associated with worsening the disease and that supplementation with vitamin D3 improves asthma symptoms. However, despite several advances in the field, the molecular mechanisms of asthma have yet to be comprehensively understood. MicroRNAs play an important role in controlling several biological processes and their deregulation is implicated in diverse diseases, including asthma. Evidence supports that the dysregulation of miR-21, miR-27b, miR-145, miR-146a, and miR-155 leads to disbalance of Th1/Th2 cells, inflammation, and airway remodeling, resulting in exacerbation of asthma. This review addresses how these molecular mechanisms explain the development of asthma and its exacerbation and how vitamin D3 may modulate these microRNAs to improve asthma symptoms.

Effect of Obesity on Lung Function in the Pediatric and Adult Populations with Asthma: A Review.

Obesity and asthma are major global health concerns, particularly in industrialized nations. Obesity has been shown to have detrimental effects on the respiratory system and lung function owing to metabolic issues and immunological consequences. Research has indicated that obese patients with asthma (atopic or T2-high and non-atopic or T2-low) have diminished lung function in terms of functional residual capacity (FRC), residual volume (RV), expiratory reserve volume (ERV), the FEV1/FVC ratio, and FEF 25-75% due to mechanical fat loading on the diaphragm and central adiposity when compared to non-obese asthmatic patients. Therefore, it is plausible that changes in lung function are the result of a combination of mechanical (fat loading on the diaphragm, central adiposity, bronchial hyper-reactivity, and an increase in cholinergic tone), environmental (diet and exercise), and inflammatory factors (local and systemic), which can lead to the obesity-related asthma phenotype characterized by severe asthma symptoms, poor response to corticosteroid treatment, loss of lung function, and poor quality of life from an early age.

Have the prevalence of eczema symptoms increased in the Mexican pediatric population? Prevalence and associated factors according to Global Asthma Network Phase I.

Background: In children, atopic dermatitis or eczema is the most common inflammatory disease of the skin. According to the International Study of Asthma and Allergies in Childhood (ISAAC) Phase IIIB in Mexico, 5.8% of children and 4.9% of adolescents had eczema symptoms. In 2012, Global Asthma Network (GAN) was established to update the prevalence of eczema and estimate potential factors contributing to its development. Objective: To estimate the prevalence and associated factors for atopic eczema symptoms and diagnosis in children and adolescents according to GAN Phase I and compare the results with ISAAC Phase IIIB in Mexico. Methods: A cross-sectional, multicenter survey was conducted in 15 Mexican centers during the period of 2015-2017 using the GAN Phase I questionnaires in children (6-7-year-olds) and adolescents (13-14-year-olds). The prevalences obtained from the GAN Phase I study, were compared with ISAAC Phase IIIB results; a Spearman's correlation analysis was conducted between temperature, relative humidity, and altitude and eczema symptoms, and a logistic regression was performed to predict current eczema symptoms by age group. Results: A total of 35 777 children and 41 399 adolescents were included. Since ISAAC Phase IIIB, the prevalence of itchy rash in the past 12 months significantly increased in the children's group [6.6% (95% CI 5.7-7.4) vs 7.8 (95% CI 7.5-8.1), p = 0.000] and adolescents' group [5.8% (95% CI 5.0-6.7) vs 6.7% (95% CI 6.5-7.0), p = 0.000].In the adolescents' group, the prevalence of nocturnal awakenings caused by rash symptoms on more than one night per week had a negative correlation between altitude (Spearman's Rho = -0.558, p value = 0.031), and a positive correlation with the average annual temperature (Spearman's Rho = 0.604, p value = 0.017) and annual relative humidity (Spearman's Rho = 0.742, p value = 0.002). The most significant associations in children were the presence of sneezing or runny or blocked nose in the past 12 months [(OR 3.13, 95% CI 2.60-3.77), p = 0.000], the use of paracetamol in the first year of life ([OR 1.52, 95% CI 1.15-2.01), p = 0.003] and the use of antibiotics in the first year of life [(OR 1.30, 95% CI 1.08-1.55) p = 0.004]. Moreover, altitude at 100-1000 m above sea level was associated with current eczema symptoms in adolescents (p = 0.001). Conclusions: There has been a significant increase in eczema symptoms in both age groups since ISAAC Phase IIIB study. Additionally, eczema symptoms were associated with temperature, relative humidity, asthma, hay fever symptoms, the use of paracetamol and antibiotics.

Immunostimulants for preventing respiratory tract infection in children: A systematic review and meta-analysis.

Childhood acute respiratory tract infections (ARTIs) are a significant cause of morbidity and mortality, so, immunostimulants have been used as a preventative measure. Despite this, there is no updated evidence regarding the safety and efficacy of immunostimulant drugs for this purpose. This study aimed to determine the effectiveness and safety of immunostimulants in preventing ARTIs in children based on the most recent scientific evidence. Data sources such as PubMed, Cochrane Central Register of Controlled Trials, Embase, Google Scholar, and Scopus were searched from 1965 to 10 January 2022 to identify randomized controlled trials (RCTs) comparing immunostimulants administered by any method, with placebo to prevent ARTIs on children under 18 years of age without immunodeficiencies, anatomical, genetic, or allergic conditions. In order to analyze data from the studies, we used Review Manager 5.4 (The Cochrane Collaboration, 2020), assessed the certainty of the evidence with Grading of Recommendations, Assessment, Development and Evaluations (GRADE), and assessed the quality and risk of bias of the studies using the RoB tool 1.0. Further, outcomes were combined and analyzed using meta-analysis, subgroup analysis, and sensitivity analysis. Throughout the review, we included 72 placebo-controlled clinical trials involving 12,229 children. The meta-analyses, however, included only 38 studies (52.8%) with 4643 children (38% of the total) with data on mean number of ARTIs. These studies demonstrated a reduction in the ARTIs (MD -1.12 [95%CI -1.39 to -0.85]) and ratio of means of ARTIs (0.61 [95%CI 0.54-0.69]), corresponding to a percentage reduction of 39% (95%CI, 46%-31%) with moderate-quality data. Nevertheless, since there was considerable to substantial heterogeneity and bias was unclear in all domains in 32 out of 72 trials, the quality of the evidence for efficacy was deemed low. Only 14 trials reported adverse events. The review indicates that immunostimulants reduce the incidence of ARTIs by 40% on average in susceptible children, despite low-quality evidence, heterogeneity, and the possibility of publication bias. However, further studies are needed to establish immunostimulants' safety and efficacy profiles. This review was conducted without the support of any funding and has no registered number.

Prevalence and risk factors associated with allergic rhinitis in Mexican school children: Global Asthma Network Phase I.

BACKGROUND: The International Study of Asthma and Allergies in Childhood (ISAAC) showed a wide variability in prevalence and severity of allergic rhinitis (AR) and rhinoconjunctivitis (ARC), in addition to other atopic diseases (Asher et al, 2006).1 The Global Asthma Network (GAN) has continued to study these conditions. OBJECTIVE: To estimate the prevalence of AR and ARC in children and adolescents in Mexico and to assess their association with different risk factors. METHODS: GAN Phase I is a cross-sectional, multicentre survey carried out in 15 centres corresponding to 14 Mexican cities throughout 2016-2019 using the validated Spanish language version of the GAN Phase I questionnaires. The questionnaires were completed by 35 780 parents of 6-7 year old primary school pupils (children) and by 41 399 adolescents, 13-14 years old. RESULTS: The current and cumulative prevalence of AR was higher in the adolescents (26.2-37.5%, respectively) in comparison to the children (17.9-24.9%, respectively), especially in female participants. This tendency was also observed in the current prevalence of ARC, where 15.1% of female adolescents reported nasal symptoms accompanied with itchy-watery eyes in the past year. The most important risk factors for AR and ARC were the presence of wheezing in the past 12 months, wheezing in the first year of life, the previous diagnosis of asthma and eczema symptoms. Furthermore, allergic symptoms had a negative tendency concerning altitude. CONCLUSION: This is the largest AR epidemiological study ever conducted in Mexico. It shows an increase in AR prevalence, as well as significant associations with modifiable risk factors, which could help to establish recommendations to reduce the burden of this condition.

Have asthma symptoms in Mexico changed in the past 15 years? Time trends from the International Study of Asthma and Allergies in Childhood to the Global Asthma Network

BACKGROUND: The Global Asthma Network (GAN) builds on the International Study of Asthma and Allergies in Childhood (ISAAC). OBJECTIVE: To compare asthma prevalence time trends in primary and secondary school children in four Mexican centers participating in ISAAC and GAN. METHODS: GAN is a cross-sectional, multicenter, epidemiological methodology carried out in groups of primary school children aged 6-7 and adolescents aged 13-14 following the ISAAC Phase Three protocol, with additional questions on risk factors and asthma management. RESULTS: Overall, the prevalence of asthma symptoms and diagnosis in primary school children was higher in males than in females both in ISAAC (p < 0.05) and in GAN (p < 0.01), while adolescent females had a higher prevalence, also both in ISAAC (p < 0.001) and in GAN (p < 0.001). CONCLUSION: The prevalence of asthma and its symptoms has increased from ISAAC Phase Three since 2003 to GAN Phase I in Mexico in 2019. These findings are in line with the increases observed in the centers with low asthma baseline prevalence in ISAAC Phase One in comparison with ISAAC Phase Three

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Global Asthma Network Phase I study in Mexico: prevalence of asthma symptoms, risk factors and altitude associations-a cross-sectional study.

BACKGROUND: Global Asthma Network (GAN) was established in 2012 as a development to the International Study of Asthma and Allergies in Childhood to improve asthma care globally. OBJECTIVE: To survey asthma, allergic rhinitis and atopic dermatitis in primary and secondary school children and to investigate and evaluate its prevalence, severity, management and risk factors in Mexico. METHODS: GAN Phase I is a cross-sectional, multicentre survey carried out in 15 centres corresponding to 14 Mexican cities throughout 2016-2019 using the validated Spanish language version of the GAN Phase I questionnaires. The questionnaires were completed by parents of 6-7-year-old primary school pupils (school children) and by 13-14-year-old adolescents. RESULTS: A total of 35 780 school children and 41 399 adolescents participated. Wheezing ever prevalence was 26.2% (95% CI 25.8% to 26.7%) in school children and 23.9% (95% CI 23.4% to 24.3%) in adolescents. The corresponding frequencies for current wheeze were 10.2% (95% CI 9.9% to 10.5%) and 11.6% (95% CI 11.2% to 11.9%). In school children, the risk factors for current wheeze were rhinitis (OR 4.484; 95% CI 3.915% to 5.134%) and rash symptoms (OR 1.735; 95% CI 1.461% to 2.059%). For adolescents, rhinitis symptoms (OR 3.492; 95% CI 3.188% to 3.825%) and allergic rhinitis diagnosis (OR 2.144; 95% CI 1.787% to 2.572%) were the most significant. For both groups, there was a negative relation with centres' sea level altitude higher than 1500 m above mean sea level (p<0.005). CONCLUSIONS: The most important risk factors for asthma symptoms in both age groups were the presence of rhinitis and rash symptoms or diagnosis. On the other hand, sea level altitude higher than 1500 metres was a protective factor.

The burden of asthma in an inner-city area: A historical review 10 years after Isaac.

BACKGROUND: According to the International Study of Asthma and Allergies in Childhood (ISAAC) methodology, in 2003, the prevalence of asthma symptoms in children 6-7 years old and adolescents 13-14 years old was 11.6% and 13.7%, respectively. Since then, the number of asthma cases has increased worldwide. The study was conducted in several districts in northern Mexico City to evaluate the prevalence of asthma in these age groups and examine possible risk factors. The data were compared to the 2003 results from the same area. METHODS: This was a comparative cross-sectional study following the official Global Asthma Network (GAN) methodology. The parents or guardians of participants completed a questionnaire that explored demographics, asthma symptoms, diagnoses, and possible risk factors. Central tendency measurements were determined for statistical analysis and chi-squared distribution for possible risk factors. RESULTS: A total of 2515 children aged 6-7 years and 3375 adolescents aged 13-14 years participated in the study. Compared to the ISAAC results, we found a greater prevalence of wheezing in both children (at some time in life, 19.2% vs. 27.1%; over the last year, 6.8% vs. 10.6%) and adolescents (at some time in life, 16.9% vs. 19.7%), and for children with an asthma diagnosis (4.5% vs. 5.1%). For both groups, the most common risk factor associated with wheezing was the presence of rhinitis symptoms. CONCLUSIONS: Asthma symptoms are highly prevalent in Mexico City, occurring in almost 20% of adolescents. Compared to a decade ago, there was a 7.9% increase in the prevalence of asthma symptoms in children. Almost half of the children and adolescents presenting with symptoms had experienced more than four episodes per year. However, less than 50% of children and adolescents with asthma symptoms had been diagnosed with this disorder, suggesting under-diagnosis.