Contributions of asthma, rhinitis and IgE to exhaled nitric oxide in adolescents

Associations of Infant Colic and Excessive Crying with Atopic Outcomes in Childhood and Adolescence

OBJECTIVE

To assess the extent to which risks of atopic and respiratory conditions throughout childhood and adolescence differ by history of: 1) infant colic, characterized by apparent abdominal discomfort and unsoothable crying; 2) excessive crying without colic; or 3) neither condition.

STUDY DESIGN

Among 1,249 children participating in the prospective, unselected Project Viva cohort, we examined associations of history of infant colic or excessive crying without colic with risks of eczema, allergic rhinitis, asthma, and respiratory infections, measured in toddlerhood, early childhood, mid-childhood, early adolescence, and mid-adolescence using multinomial logistic regression models.

RESULTS

The study sample was 50% female and 71% non-Hispanic White; 26% had colic and 9% excessive crying. Children with colic (vs no colic or excessive crying) had higher risk of eczema (relative risk ratio [RRR]: 2.1, 95% CI: 1.2, 3.8), allergic rhinitis (RRR 1.6, 95% CI: 1.1, 2.4), and asthma (RRR 1.6, 95% CI: 1.1, 2.4) in mid-childhood, and higher risk of respiratory infections in toddlerhood (RRR: 1.6, 95% CI 1.2, 2.2) and mid-adolescence (RRR: 2.1, 95% CI: 1.2, 3.7). Risk of two to three concurrent atopic conditions (eczema, allergic rhinitis, and/or asthma) was nearly twice that among the colic group (vs unaffected) at all life stages. The group with excessive crying without colic did not have increased risk of atopic and respiratory outcomes.

CONCLUSIONS

Colic characterized by unsoothable crying and parent perceptions of abdominal distress may be an early marker of atopic susceptibility.

Short-term exposure to relative humidity and lung health in early adolescents

Background

Extremes in humidity can induce bronchoconstriction and trigger breathing symptoms in people with asthma. Less is known about how humidity influences measurements of lung health in children and adolescents. Our objective was to assess the extent to which short-term exposures to high and low relative humidity (RH) are associated with lung function and fractional exhaled nitric oxide (FeNO) in adolescents.

Methods

We included adolescents (mean age 13.2 y, SD: 0.9) from a northeast US prospective prebirth cohort (n = 1019). We assigned daily RH levels to geocoded participant addresses. We defined low or high RH as ≤10th or ≥90th internal percentiles, respectively, of the cohort-specific RH distribution and the reference RH as the median. We evaluated the linearity of associations of RH in the 1-7 days before assessment with forced expiratory volume in 1 s (FEV1), forced vital capacity (FVC), and FeNO using generalized additive models with penalized splines (df = 3). We log-transformed FeNO due to non-normality. For nonlinear relationships, we used distributed lag nonlinear models to explore the cumulative effects of lag 1-7 day RH on FEV1, FVC, and FeNO.

Results

Median RH was 65.6% (interquartile range [IQR] = 19.8%), 10th percentile 47.2%, 90th percentile 86.6%. Mean FeNO (SD) was 25.9ppb (26.9ppb). High (vs. median) RH was associated with 38.0% higher FeNO (95% CI = 10.3, 72.7). Exposure to low (vs. median) RH was associated with 186.2 ml lower FEV1 (95% CI = -299.2, -73.3) and -130.2 ml lower FVC (95% CI = -251.9, -8.5).

Conclusion

Short-term exposures to extremes of RH were associated with lower lung function and higher FeNO, a measure of airway inflammation, in adolescents.

Long-Term Exposure to Nitrogen Dioxide and Ozone and Respiratory Health in Children

Rationale: Further evaluation of the impact of long-term exposure to the gaseous air pollutants nitrogen dioxide (NO2) and ozone (O3) on child lung function and of NO2 or O3 on eosinophilic airway inflammation is needed. Objectives: To determine whether NO2 and O3 are associated with lung function and fractional exhaled nitric oxide (FeNO) in children. Methods: We measured lung function (forced expiratory volume in 1 second [FEV1] and forced vital capacity [FVC]) at midchildhood (mean age, 7.9 yr; n = 703), early teens (13.2 yr; n = 976), and midteens (17.6 yr; n = 624) study visits, and FeNO at the early and midteens study visits in Project Viva, a cohort of mother-child pairs in the Boston area. Long-term exposure to NO2 and O3 was estimated at the home address using geospatial models. We examined associations of home address NO2 and O3 exposure and proximity to roadway with lung function and FeNO using linear regression models, adjusting for age, sex, height, weight, season, relative humidity, temperature, parental smoking, and measures of socioeconomic status. We examined for effect modification of the midteen associations by blood eosinophil concentration, physical activity, aeroallergen sensitization, and parental atopy. Results: Median exposure to NO2 was 33.1 ppb (interquartile range [IQR], 10.4 ppb) and to O3 was 35.3 ppb (IQR, 3.4) in the first year of life. Exposure to NO2 was associated with lower FEV1 and FVC across all age groups and exposure time intervals: For example, an IQR increment of NO2 exposure from birth through the early teen visit was associated with 189.9 ml lower FEV1 (95% confidence interval, -273.3, -106.5) at the midteen visit. Lifetime NO2 exposure at was associated with higher FeNO at the early teen visit: for example, 16.2% higher FeNO (95% confidence interval, 7.1-26.4%) per IQR of lifetime NO2 through the early teen visit. O3 exposure was not associated with lung function or FeNO. Aeroallergen sensitization (measured in a subset of participants) modified associations of NO2 and O3 with FeNO. Conclusions: Exposure to NO2 was associated with lower lung function and higher FeNO among generally healthy children and teenagers. Because NO2 exposure levels were within the annual U.S. Environmental Protection Agency standard, these findings suggest a need to reduce exposure to this pollutant to optimize child respiratory health.

Acute exposure to pollen and airway inflammation in adolescents

INTRODUCTION

Pollen exposure is known to exacerbate allergic asthma and allergic rhinitis symptoms, yet few studies have investigated if exposure to pollen affects lung function or airway inflammation in healthy children.

METHODS

We evaluated the extent to which higher pollen exposure was associated with differences in airway inflammation and lung function among 490 early adolescent participants (mean age of 12.9 years) in Project Viva, a prebirth cohort based in Massachusetts. We obtained regional daily total pollen counts, including tree, grass, and weed pollen, from a Rotorod pollen counter. We evaluated associations of 3- and 7-day moving averages of pollen with fractional exhaled nitric oxide (FeNO) and lung function using linear regression models and evaluated the linearity of associations with penalized splines. We tested if associations of pollen with FeNO and lung function were modified by current asthma diagnosis, history of allergic rhinitis, aeroallergen sensitivity, temperature, precipitation, and air pollution.

RESULTS

Three- and 7-day median pollen concentrations were 19.0 grains/m3 (IQR: 73.4) and 20.9 grains/m3 (IQR: 89.7). In main models, higher concentrations of total pollen over the preceding 3 and 7 days were associated with a 4.6% (95% CI: 0.1,9.2) and 7.4% (95% CI: 0.9,14.3) higher FeNO per IQR of pollen, respectively. We did not find associations of pollen with lung function in main models. Asthma, allergic rhinitis, precipitation, and air pollution (nitrogen dioxide and ozone) modified associations of pollen with lung function (Pinteraction < 0.1), while temperature, sex, and aeroallergen sensitization did not.

CONCLUSION

Short-term exposure to pollen was associated with higher FeNO in early adolescents, even in the absence of allergic sensitization and asthma.

Clinical Applications of Nasal Nitric Oxide in Allergic Rhinitis: A Review of the Literature

Allergic rhinitis, a common allergic disease affecting a significant number of individuals worldwide, is observed in 25% of children and 40% of adults, with its highest occurrence between the ages of 20 and 40. Its pathogenesis, like other allergic diseases, involves innate and adaptive immune responses, characterized by immunologic hypersensitivity to environmental substances. This response is mediated by type 2 immunity. Within type 2 allergic diseases, certain molecules have been identified as clinical biomarkers that contribute to diagnosis, prognosis, and therapy monitoring. Among these biomarkers, nitric oxide has shown to play a key role in various physiological and pathological processes, including neurotransmission, immunity, inflammation, regulation of mucus and cilia, inhibition of microorganisms, and tumor cell growth. Therefore, measurement of nasal nitric oxide has been proposed as an objective method for monitoring airway obstruction and inflammation in different settings (community, hospital, rehabilitation) and in various clinical conditions, including upper airways diseases of the nose and paranasal sinuses. The purpose of this review is to analyze the potential mechanisms contributing to the production of nasal nitric oxide in allergic rhinitis and other related health issues. Additionally, this review aims to identify potential implications for future research, treatment strategies, and long-term management of symptoms.

Exposure to household dust, allergens, and endotoxin and allergy-related outcomes alternation in the general U.S. population

It has been widely reported that the general population was at an increased risk of allergy diseases, which probably be related with household allergens exposure. However, the difference of local and systemic allergic reactions exposure to allergens has not been reported in the general population previously. The data of 1094 U.S. adults from the National Health and Nutrition Examination Survey (NHANES) 2005-2006 data bank were analyzed. Dust, allergens (Bia g 1, Bia g 2, Can f 1, Feld 1, Derp 1, Mus m 1, Rat n 1, Alternaria alternate, and Aspergillus fumigatus), and endotoxin, were measured to estimate sensitizing source exposure. And allergy-related outcomes indicators including hay fever, sneezing, allergic rhinitis (AR), immunoglobulin E (IgE), and allergic sensitization, were evaluzted to estimate local and systemic allergic reactions. Multiple linear regression and logistic regression models were used to examine the associations of sensitizer and allergy-related outcomes. The mean or median concentration of dust and endotoxin were 0.66 g and 12.98 EU/mg dust. The Derp 1, Mus m 1, Rat n 1, Alternaria alternate, and Aspergillus fumigatus were the main allergens in the dust, with the concentrations of 30.66 ng/g dust, 30.73 ng/g dust, 5.94 ng/g dust, 5.20 ng/g dust, and 207.68 μg/g dust, respectively. The prevalence of AR was 34.2% among the general population. After controlling for sociodemographic factors, we found that the allergens, such as Can f 1 and Feld 1, were positively associated with AR. The prevalence of allergic sensitization was about 20%. Dust and endotoxin were found positively associated with allergic sensitization, while Bia g 2, Rat n 1, Alternaria alternate, and Aspergillus fumigatus were inversely associated with that. Dust and endotoxin probably be associated with higher risk of local allergic reactions, while some allergens, such as Bia g 2, Rat n 1, Alternaria alternate, and Aspergillus fumigatus probably be associated with lower risk of systemic allergic reactions.

Precipitation and Adolescent Respiratory Health in the Northeast United States

Rationale: With more frequent and intense precipitation events across the globe due to a changing climate, there is a need to understand the relationship between precipitation and respiratory health. Precipitation may trigger asthma exacerbations, but little is known about how precipitation affects lung function and airway inflammation in early adolescents. Objectives: To determine if short-term precipitation exposure is associated with lung function and airway inflammation in early adolescents and if ever having a diagnosis of asthma modifies associations of precipitation with lung function and airway inflammation. Methods: In a prospective prebirth cohort, Project Viva, that included 1,019 early adolescents born in the northeastern United States, we evaluated associations of 1-, 2-, 3-, and 7-day moving averages of precipitation in the preceding week and forced expiratory volume in 1 second, forced vital capacity, and fractional exhaled nitric oxide (FeNO) using linear regression. We used log-transformed FeNO with effect estimates presented as percentage change. We adjusted for maternal education and household income at enrollment; any smoking in the home in early adolescence; child sex, race/ethnicity, and ever asthma diagnosis; and age, height, weight, date, and season (as sine and cosine functions of visit date) at the early adolescent visit and moving averages for mean daily temperature (same time window as exposure). Results: In fully adjusted linear models, 3- and 7-day moving averages for precipitation were positively associated with FeNO but not lung function. Every 2-mm increase in the 7-day moving average for precipitation was associated with a 4.0% (95% confidence interval, 1.1, 6.9) higher FeNO. There was evidence of effect modification by asthma status: Precipitation was associated with lower forced vital capacity and higher FeNO among adolescents with asthma. We also found that outdoor aeroallergen sensitization (immunoglobulin E against common ragweed, oak, ryegrass, or silver birch) modified associations of precipitation with FeNO, with higher FeNO in sensitized adolescents compared with nonsensitized adolescents. The associations of precipitation with FeNO were not explained by relative humidity or air pollution exposure. Conclusions: We found that greater short-term precipitation may trigger airway inflammation in adolescents, particularly among those with asthma.

Serial fractional exhaled nitric oxide measurements at and off work may help to identify immunologic occupational asthma in cases with complex exposures

Serial measurements of fractional exhaled nitric oxide (FeNO) at home and at work have been described to provide complementary information for the diagnosis of occupational asthma (OA) when specific inhalation challenge (SIC) is missing or doubtful. We describe two cases in which serial FeNO measurements enabled the detection of probable OA after complex exposures. A 25-year-old industrial painter with exposure to a variety of paints suffered from work-related airway symptoms for five years. Lung function was normal, and he was not atopic. SIC with hexamethylene diisocyanate was negative. A 47-year-old sign maker (screen printing, foils) suffering from work-related dyspnoea for seven years. Moderate airway obstruction, but no atopy was detectable. Due to the complex exposures SIC was not performed. Both patients performed FeNO measurements once daily during a 2-week-holiday and a subsequent 2-week-work period. In both cases elevated baseline FeNO decreased to normal (25 ppb) during holidays and increased after resuming work (case 1: 125 ppb, case 2: 45 ppb).

Precision Medicine and Childhood Asthma: A Guide for the Unwary

Many thousands of articles relating to asthma appear in medical and scientific journals each year, yet there is still no consensus as to how the condition should be defined. Some argue that the condition does not exist as an entity and that the term should be discarded. The key feature that distinguishes it from other respiratory diseases is that airway smooth muscles, which normally vary little in length, have lost their stable configuration and shorten excessively in response to a wide range of stimuli. The lungs' and airways' limited repertoire of responses results in patients with very different pathologies experiencing very similar symptoms and signs. In the absence of objective verification of airway smooth muscle (ASM) lability, over and underdiagnosis are all too common. Allergic inflammation can exacerbate symptoms but given that worldwide most asthmatics are not atopic, these are two discrete conditions. Comorbidities are common and are often responsible for symptoms attributed to asthma. Common amongst these are a chronic bacterial dysbiosis and dysfunctional breathing. For progress to be made in areas of therapy, diagnosis, monitoring and prevention, it is essential that a diagnosis of asthma is confirmed by objective tests and that all co-morbidities are accurately detailed.

Use of computational fluid dynamics (CFD) to model observed nasal nitric oxide levels in human subjects

BACKGROUND

Upper airway nitric oxide (NO) is physiologically important in airway regulation and defense, and nasal NO (nNO) levels typically exceed those in exhaled breath (fractional exhaled NO [FeNO]). Elevated concentrations of NO sampled from the nose, in turn, reflect even higher concentrations in the paranasal sinuses, suggesting a "reservoir" role for the latter. However, the dynamics of NO flux within the sinonasal compartment are poorly understood.

METHODS

Data from 10 human subjects who had previously undergone both real-time nNO sampling and computed tomography (CT) scanning of the sinuses were analyzed using computational fluid dynamics (CFD) methods. Modeled and observed nNO values during the initial 2-s transient ("spike") during nasal exhalation were then compared.

RESULTS

Examining the initial 2-s transient spike for each subject (as well as the pooled group), there was a statistically significant correlation between modeled and observed nNO levels, with r values ranging from 0.43 to 0.89 (p values ranging from <0.05 to <0.0001). Model performance varied between subjects, with weaker correlations evident in those with high background (FeNO) levels. In addition, the CFD simulation suggests that ethmoid sinuses (>60%) and diffusion process (>54%) contributed most to total nasal NO emissions.

CONCLUSION

Analysis of this dataset confirms that CFD is a valuable modeling tool for nNO dynamics, and highlights the importance of the ethmoid sinuses, as well as the role of diffusion as an initiating step in sinonasal NO flux. Future model iterations may apply more generally if baseline FeNO is taken into account.