BACKGROUND:Rhinoconjunctivitis phenotypes are conventionally described on the basis of symptom severity, duration and seasonality, and aeroallergen sensitization. It is not known whether these phenotypes fully reflect the patterns of symptoms seen at a population level. OBJECTIVE:We sought to identify phenotypes of rhinoconjunctivitis on the basis of symptom intensity and seasonality using an unbiased approach and to compare their characteristics. METHODS:A cohort of children with asthma in low-income urban environments was prospectively followed with a rhinoconjunctivitis activity questionnaire, and their upper and lower airway disease was managed for 12 months with every 2-month visit based on standardized algorithms. We identified individual rhinoconjunctivitis symptom trajectories and clusters of those trajectories and compared the clusters focusing on atopic characteristics. RESULTS:Data obtained from 619 children yielded 5 symptom clusters: 2 had high symptoms (22.5%) but differed in seasonal pattern, 1 had medium symptoms (13.6%), 1 had medium nasal congestion only (20.4%), and 1 had low symptoms (43.6%). The latter was further split into 2 subgroups if nasal corticosteroids were frequently prescribed (23.6%) or not (20.0%). Seasonal variation was absent in the low symptom clusters. The number of allergic sensitizations and family history of allergic airway disease were higher in the high symptom clusters, but allergic sensitization did not explain differences in seasonality. CONCLUSIONS:This study identified rhinoconjunctivitis phenotypes that have not been previously reported and were not differentiated by demographics or by measures of atopy and type 2 inflammation. Factors beyond allergy need to be investigated to better understand the pathobiology of rhinoconjunctivitis.

The relationship between infections, immune development, and preschool recurrent wheezing and asthma is complex and multifaceted. Respiratory syncytial virus (RSV) and rhinovirus (RV) are significant early-life triggers for wheezing, with differing immunologic and genetic associations. RV, especially RV-C, has been closely linked to asthma development, particularly allergic asthma. RSV wheezing illnesses can identify susceptible children and are linked to nonallergic asthma. Ongoing studies using broader RSV prevention (vaccines, mAbs) in full-term infants may further clarify these relationships. Both RSV and RV infections are associated with changes in bacterial abundance. The timing of these changes and the bacterial strains that are altered are likely important factors in asthma development that are continually being investigated. Beyond viral triggers, asthma and recurrent wheeze in preschoolers result from a complex interplay of microbial (urban vs rural living), environmental (eg, air pollution levels and diet) and host immune factors. Strategies focusing on microbiome modulation (eg, bacterial lysate ingestion), pollution reduction, increasing biodiversity, and nutritional support (eg, vitamin D) may offer promising paths for prevention and improved management.

BACKGROUND:Early childhood wheeze is characterized by heterogeneous trajectories having differential associations with later-life asthma development. OBJECTIVE:We sought to determine how early-life wheeze trajectories impact later life asthma gene expression. METHODS:The Children's Respiratory Environmental Workgroup is a collective of 12 birth cohorts, 7 of which conducted an additional visit with a nasal lavage collected and subjected to bulk RNA-sequencing. Early-life wheeze trajectories were defined using latent class analysis of longitudinal early-life wheezing data. Weighted gene correlation network analysis was used to associate gene expression patterns and current asthma with early-life wheeze trajectories. RESULTS:We investigated 743 children (mean age, 17 ± 5.1 years; 360 [48.5%] male). Four patterns of early-life wheeze were identified: infrequent, transient, late-onset, and persistent. Early-life transient wheeze was associated with gene expression patterns related to increased antiviral response, and late-onset wheeze was associated with decreased insulin signaling and glucose metabolism. Early-life persistent wheeze was associated with gene expression modules of type 2 inflammation and epithelial development, but these modules did not distinguish those with current asthma. Children who had persistent wheeze in early life and current asthma displayed a unique increase in expression of genes enriched for neuronal processes and ciliated epithelial function compared with those without asthma. CONCLUSIONS:Early-life longitudinal wheeze trajectories are associated with specific asthma transcriptomes later in life. These data suggest that early-life asthma prevention strategies may be most beneficial when tailored to the specific wheeze pattern.

Rationale: Race-based estimates of pulmonary function in children could influence the evaluation of asthma in children from racial and ethnic minoritized backgrounds. Objectives: To determine if race-neutral (Global Lung Function Initiative [GLI]-Global) versus race-specific (GLI-Race-Specific) reference equations differentially impact spirometry evaluation of childhood asthma. Methods: The analysis included 8,719 children aged 5 to <12 years from 27 cohorts across the United States grouped by parent-reported race and ethnicity. We analyzed how the equations affected FEV1, FVC, and FEV1/FVC z-scores. We used multivariable logistic models to evaluate associations between z-scores calculated with different equations and asthma diagnosis, emergency department visits, and hospitalization. Measurements and Main Results: For Black children, the GLI-Global versus GLI-Race-Specific equations estimated significantly lower z-scores for FEV1 and FVC but similar values for FEV1/FVC, thus increasing the proportion of children classified with low FEV1 by 14%. Although both equations yielded strong inverse relationships between FEV1 and FEV1/FVC z-scores and asthma outcomes, these relationships varied across racial and ethnic groups (P < 0.05). For any given FEV1 or FEV1/FVC z-score, asthma diagnosis and emergency department visits were higher among Black and Hispanic than among White children (P < 0.05). For FEV1, GLI-Global equations estimated asthma outcomes that were more uniform across racial and ethnic groups. Conclusions: Parent-reported race and ethnicity influenced relationships between lung function and asthma outcomes. Our data show no advantage to race-specific equations for evaluating childhood asthma, and the potential for race-specific equations to obscure lung impairment in disadvantaged children strongly supports using race-neutral equations.

This study examined whether SNPs at the 17q12-q21 locus that are associated with childhood asthma are also associated with severe respiratory syncytial virus (RSV) infection and viral load. We conducted a candidate SNP association study in the subset of RSV-infected infants who were parent-identified as White (n = 159) in the INSPIRE cohort. Nine SNPs at the 17q12-q21 locus were genotyped. We used an additive model to evaluate each SNP’s association with RSV infection severity and viral load. Replication of significant associations was tested in the TCRI cohort: infants with severe RSV illness. In INSPIRE, an SNP rs8069202-G in the GSDMA gene was associated with increased RSV viral load (and marginally associated with RSV severity). SNP rs2941504, in the PGAP3 gene, was associated with a reduced risk of RSV severity. All significant associations were directionally replicated in the TCRI cohort but were insignificant at a p-value < 0.05. The association of a SNP in GSDMA with RSV viral load and RSV infection severity suggests that GSDMA may be contributing to both severe RSV infection and asthma development. On the other hand, the association between an SNP in PGAP3 and reduced RSV infection severity suggests distinct pathways link PGAP3 to these two respiratory outcomes.

Childhood allergic diseases and asthma have their origins in early life, and allergen exposures during this period could be a critical determinant of the progression to tolerance versus disease. Mechanisms for sensitization may be different but overlapping for food and aeroallergen sensitization in children. This suggests differences in how exposure to food and aeroallergens influence allergic sensitization. For food allergy, introducing foods such as peanut and egg proteins into the diet at an early age reduces the risk of peanut and egg allergy, respectively, across a broad demographic, whereas evidence is less established for other foods. The relationship between allergen exposure and sensitization to aeroallergens is more complex but critical, given the close relationship between specific immunoglobulin E and respiratory disease. Several factors could mediate the progression from allergen exposure and allergic sensitization versus tolerance, including epithelial barrier function and altered immune development at the skin and mucosal surfaces, exposure to irritants and pollutants, and genetic susceptibility. Collectively, the current evidence base provides a compelling rationale for the primary prevention of food allergy by introducing common allergens such as peanut and egg early. In contrast, primary prevention of aeroallergen sensitization is more complex and perhaps more challenging to achieve by manipulating allergen exposures. Even so, recent advances in understanding how the microbiome and environmental toxins and irritants modulate the mucosal immune response have identified potential new strategies for primary prevention of food and aeroallergen sensitization.

The development of the airway epithelium in asthma is unclear. We characterized nasal airway epithelial cell (NAEC) developmental phenotypes from children aged 2 to 3 years in an a priori designed nested birth cohort from four mutually exclusive groups of wheezers/nonwheezers and respiratory syncytial virus (RSV)-infected/uninfected in the first year of life. NAECs were differentiated, followed by single-cell RNA sequencing analysis and in vitro RSV infection. Gene expression of NAECs from children with a wheeze phenotype indicated abnormal differentiation and basal cell activation of developmental pathways, plasticity in precursor differentiation, delayed onset of maturation, increased diversity of RSV receptors, and blunted antiviral immune responses to in vitro RSV infection. The most marked changes in differentiation were observed in NAECs from children with both wheeze and RSV in the first year of life. Together, this suggests that airway epithelium in children with wheeze is developmentally reprogrammed and characterized by increased barrier permeability, decreased antiviral response, and altered RSV receptor expression.

Importance:While biologic therapies targeting type 2 (T2) inflammation reduce acute exacerbation rates in children with asthma and T2 inflammation, exacerbations still occur, and the underlying molecular mechanisms are poorly defined. Objective:To identify multiple distinct molecular mechanisms implicated in asthma exacerbations by characterizing respiratory illnesses among urban children with eosinophilic asthma enrolled in a clinical trial comparing treatment with mepolizumab vs placebo. Design, Setting, and Participants:This is a secondary analysis of the Mechanisms Underlying Asthma Exacerbations Prevented and Persistent With Immune-Based Therapy: A Systems Approach Phase 2 (MUPPITS-2) double-blind, placebo-controlled, parallel-group, randomized clinical trial comparing treatment with mepolizumab vs placebo among children with exacerbation-prone asthma in low-income urban centers in 9 US cities. Data analysis was performed from September 2022 to April 2025. Intervention:Participants were randomized to receive either mepolizumab (aged 6-11 years: 40 mg; aged 12-17 years: 100 mg) or matching placebo by subcutaneous injection once every 4 weeks for 52 weeks. Main Outcomes and Measures:The primary measurement was a transcriptomic modular analysis by RNA sequencing of nasal samples obtained during acute respiratory illnesses. Associations among upper airway transcriptional signatures, the clinical outcome of respiratory illnesses, and pulmonary functions were investigated. Results:Of the 290 participants enrolled in the MUPPITS-2 trial, 108 participants (median [IQR] age, 10.0 [9.0-13.0] years; 48 [44%] female) were sampled during 176 acute respiratory illness events. During illness events resulting in asthma exacerbations, children receiving mepolizumab demonstrated decreased expression of an eosinophil-associated module associated with T2 inflammation (log2 fold change [FC] estimate, -0.60; false discovery rate [FDR] < .05) but increased expression of gene modules associated with epithelial and macrophage inflammatory pathways relative to children receiving placebo (log2 FC estimates, 0.22-0.85; FDR < .05). Both groups showed higher expression of mucus secretion and cellular stress response pathways during exacerbations relative to nonexacerbation illnesses. The mepolizumab group demonstrated upregulation of epithelial inflammatory pathways in exacerbations irrespective of a respiratory virus, while macrophage pathways contributed specifically to viral exacerbations. Three distinct, semiorthogonal inflammatory axes were shown to underlie the majority of the heterogeneity among exacerbations in the 2 groups. Conclusions and Relevance:The study's findings implicate multiple alternative inflammatory pathways associated with the epithelium and macrophages, as well as mucus hypersecretion, as mechanisms of residual acute exacerbations in children receiving mepolizumab. Further, they indicate that multiple distinct inflammatory axes can independently contribute to asthma exacerbations. Trial Registration:ClinicalTrials.gov Identifier: NCT03292588.

Rationale: Allergic airway inflammation can increase susceptibility to viral illnesses and asthma exacerbations; however, the mechanisms by which T2 inflammation increases susceptibility to respiratory viruses have not been established. To test the hypothesis that T2 inflammation impairs antiviral immune responses, differentiated human airway epithelial cells were treated with IL-13, to measure the effects of allergic inflammation on rhinovirus (RV, a well-known cause of wheezing children) replication and antiviral responses, which were assessed by bulk RNA sequencing (bulk RNA-seq) and single-cell RNA sequencing (scRNA-seq). Methods: Low-dose IL-13 (1 ng/mL) was added to fully differentiated bronchial epithelial cells from lung transplantation donors in an air-liquid interface culture system to model T2 allergic inflammation, with comparison to cells not treated with IL-13. The epithelial cells were then inoculated with low-dose RV-C (103 plaque-forming unit-equivalents) to observe the effects of T2 inflammation on virus replication and spread. IL-13 treatments were maintained during the infection process. RV-C infected samples were collected every 15-16 hours to reflect successive RV replication cycles. qPCR-measured viral replication, bulk RNA-seq (n=4, including the donor cells used in scRNA-seq) analyzed gene expression, and scRNA-seq (n=1) was used to assess gene expression data to cell type. Results: IL-13 treatment (without viral infection) downregulated some immune response-related genes, such as C3 and C4B (complement components) and S100A8 and S100A9 (markers of inflammation). IL-13 did not change expression of the RV-C receptor (CDHR3) expression, STAT1 or interferon genes. At 48 hours post-inoculation (about three replication cycles), IL-13 treatment significantly increased RV replication compared to cells not treated with IL-13 (1.1x108 vs. 7.6x106 equivalent plaque forming unit (ePFU), p = 0.024), an enhancing effect confirmed by both bulk RNA-seq and scRNA-seq analyses. After RV-C infection, IL-13 did not affect the expression of genes that detect viral RNA detection (e.g., RIG-I, IFIH1, TLR3, TLR7). However, IL-13 treatment increased RV-induced STAT1 (2.4x104 vs. 1.4x104 transcript per million (TPM), p=0.002) and interferon-lambda 3 responses (2.0x102 vs. 2.3 TPM, p<0.0001) 48 hrs after inoculation. Conclusions: In cultured human bronchial epithelial cells, the T2 cytokine IL-13 increased RV-C replication. At baseline or during the early stages of infection, IL-13 treatment did not modify CDHR3 receptor expression or key antiviral molecules, but increased viral replication and associated interferon responses after a few replication cycles. These results suggest that IL-13 could promote virus spread during successive replication cycles in airway epithelial cells.

Background Overweight/obesity is a risk factor for asthma, particularly in under-resourced children, and contributes to higher disease burden. Type 2 (T2) inflammation, a key characteristic of asthma endotypes, has been inconsistently associated with burden of obesity-related asthma, which may be due to limited overlap between different T2 features, including elevated total serum IgE level, eosinophilia, and allergen sensitization. Objective To investigate the effects of different T2 features on association of overweight/obesity with asthma burden in under-resourced children. Methods Among 2160 children aged 6 to 20 years from 4 Inner-City Asthma Consortium cohorts, the association of overweight/obesity with asthma burden (unscheduled visits, hospitalizations, exacerbations, asthma control, and pulmonary function) and the effect of T2 features (total IgE level higher than age-specific cutoffs, total eosinophils > 300 cells/µL, or sensitization to ≥2 allergens) on the association were investigated. Results The odds (odds ratio [95% CI]) of unscheduled visits were higher among those with overweight/obesity (1.35 [1.04-1.75]) and allergen sensitization (1.35 [1.02-1.80]), hospitalizations were higher among those with elevated total IgE level (2.17 [1.27-3.69]) and eosinophilia (2.80 [1.56-5.21]), and poor asthma control was higher among those with elevated total IgE level (1.27 [1.09-1.41]). Overweight/obesity and all T2 features were associated with lower forced expiratory volume in 1 second/forced vital capacity ratio. There was no synergistic or clinically significant mediating influence of any of T2 features on the association of overweight/obesity with asthma burden. Conclusion Among under-resourced children with asthma, overweight/obesity and T2 inflammation are largely independently associated with unscheduled visits and pulmonary function deficits. T2 inflammation, but not overweight/obesity, is associated with poor control and hospitalizations.

BACKGROUND:Early-life environmental exposures influence the incidence of allergic diseases and asthma, possibly by modifying immune development. Exposure to selected indoor aeroallergens has been associated with reduced wheezing and childhood asthma. OBJECTIVES:We sought to determine whether allergen exposure in early life promotes immune development and reduces asthma risk. METHODS:From birth through age 7, we measured cytokine responses of peripheral blood mononuclear cells from 442 children in the Urban Environment and Childhood Asthma study. We then compared allergen and endotoxin levels in house dust collected in the first 3 years to cytokine responses, atopy and longitudinal allergic sensitization trajectories, and asthma (age 7). RESULTS:Cord blood cytokine responses had unique features but were poorly predictive of subsequent responses. Early cockroach, mouse, and cat allergen exposures were significantly associated with selected IFN-α, IL-12p40, and TNF responses to innate stimuli, mitogen-induced IFN-γ (cockroach and mouse), and dust mite-induced IFN-γ (mouse) at age 7. Early onset of aeroallergic sensitization was positively associated with allergen-induced type 2 responses that started at ages 1-3 years and intensified at ages 5-7. In logistic regression models, cytokine responses modestly predicted atopy but not asthma (AUROC 0.69 ± 0.14 and 0.57 ± 0.08, respectively). CONCLUSIONS:Associations between preschool aeroallergen exposures and cytokine responses through age 7 years suggest a possible role in modifying systemic immune development. Progressively increasing aeroallergen-induced type 2 responses were associated with early-onset allergic sensitization. In contrast, asthma at age 7 was not associated with distinct cytokine responses, perhaps reflecting the multiple inflammatory mechanisms related to early-onset childhood asthma.