Severe asthma is a chronic disease of airway inflammation with substantial morbidity. Deficient specialized pro-resolving mediators (SPMs) are associated with persistent airway inflammation and impaired lung function in some patients with severe asthma. Resolvin D1 (RvD1) is an SPM agonist for inflammation resolution. Plasma RvD1 was measured longitudinally over 5 years in 23 severe asthma patients in the Severe Asthma Research Program (SARP) to identify relationships between clinical parameters, type 2 inflammation, and sputum gene expression. The majority of severe asthma patients had persistently low plasma RvD1; a smaller subgroup had higher RvD1 that fluctuated over time. Correlation analysis indicated a relationship between plasma RvD1 and sputum eosinophilia. A subgroup of severe asthma patients had low plasma RvD1 and high sputum eosinophils (RvD1LoSpEosHi); a separate subgroup had high plasma RvD1 and low sputum eosinophils (RvD1HiSpEosLo). The RvD1LoSpEosHi patient cluster had increased T2 inflammation, lower lung function, and more asthma exacerbations. 42 genes were differentially expressed in RvD1LoSpEosHi severe asthma sputum, including hypoxia-inducible factor 1-alpha (HIF1A). RvD1 significantly downregulated eosinophil HIF-1α expression in vitro. These findings identify a subset of severe asthma patients with low RvD1 and increased sputum eosinophilia, and RvD1 regulation of eosinophil activation ex vivo, suggesting a counter-regulatory role for this SPM in modulating eosinophilic T2 inflammation in asthma.

BACKGROUND:Wheezing lower respiratory tract illnesses are a major health concern in preschool children. We report the results of the ORBEX trial which evaluated the safety and efficacy of the bacterial lysate, OM-85, in the primary prevention of wheezing lower respiratory tract illness. METHODS:ORBEX is a parallel-arm, double-blind, placebo-controlled trial for the primary prevention of wheezing lower respiratory tract illness in young children at increased risk for asthma due to atopic dermatitis, parental asthma, or asthma in a blood sibling aged 4 years or older. Children aged 6-18 months were centrally randomly assigned (1:1) at 11 academic clinical sites with experience in recruiting young children in the USA to receive OM-85 3·5 mg or placebo orally for 10 days each month for 24 months and then followed for an additional 36 months to evaluate outcomes while they were off the study drug. Identical openable capsules were used for active drug and placebo, and staff, investigators, and participants were masked to treatment assignment. Participants received usual treatment for wheezing illness as per US guidelines. Randomisation was stratified by sex, age group, family history of asthma, and clinical site. The primary outcome was the time to first wheezing lower respiratory tract illness during the 36-month observation period off the study drug analysed in the intention-to-treat population, which included all randomly assigned participants. The trial is registered with clinicaltrials.gov, NCT02148796, and is completed. FINDINGS:Between Jan 3, 2017, and Nov 30, 2020, 984 children were screened for eligibility, 162 were excluded, and 822 were randomly assigned (411 to the OM-85 intervention group and 411 to the placebo group). 492 participants were male (59·9%) and 330 (40·1%) were female and the mean age of participants was 11·8 months (SD 3·8). 681 children completed the 24-month treatment period, and 596 children completed the 36-month observation period. 132 children experienced at least one wheezing lower respiratory tract illness during the observation period; 71 (21%) of 342 in the OM-85 group and 61 (18%) of 339 in the placebo group. There was no significant difference between OM-85 and placebo with respect to the time to first wheezing lower respiratory tract illness (log-rank test p value 0·35; hazard ratio 1·16 [95% CI 0·82-1·64]). The most frequent adverse events, fevers, coughs, and colds, did not differ between groups. INTERPRETATION:Oral administration of OM-85 in early life did not decrease the incidence of wheezing lower respiratory tract illness in this high-risk population. Bacterial lysates are not efficacious for the primary prevention of asthma-like symptoms during the preschool years. FUNDING:National Heart, Lung, and Blood Institute and OM Pharma with supplemental funding and provision of study drug and placebo from OM Pharma.

BACKGROUND:In the ASPEN trial (NCT04594369), brensocatib 10 mg and 25 mg significantly reduced the burden of pulmonary exacerbations (annualized rate [primary endpoint], time to first, proportion exacerbation-free) over 52 weeks vs placebo in patients with bronchiectasis; brensocatib 25 mg significantly reduced lung function decline and nominally significantly improved patient-reported symptoms. Here we report efficacy and safety for Japanese patients. METHODS:Adults with bronchiectasis with ≥2 exacerbations in the 12 months before screening were randomized to once-daily brensocatib (10 mg or 25 mg) or placebo for 52 weeks. Endpoints included annualized exacerbation rate, time to first exacerbation, proportion remaining exacerbation-free, change from baseline in lung function, severe exacerbation rate, and change from baseline in patient-reported symptoms. RESULTS:Baseline characteristics of Japanese patients (n = 87) were generally consistent across groups. Brensocatib 10 mg and 25 mg reduced the annualized exacerbation rate vs placebo (rate ratio, 0.37 [95 % CI, 0.16-0.87]; 0.32 [0.14-0.75]), prolonged time to first exacerbation, and increased odds of remaining exacerbation-free. The annualized severe exacerbation rate was lower with brensocatib 10 mg and 25 mg vs placebo (rate ratio, 0.11 [0.01-1.04]; 0.30 [0.06-1.62]). Brensocatib, particularly at the 25 mg dose, also reduced lung function decline vs placebo (LS mean difference: forced expiratory volume in 1 s, 97 mL [95 % CI, 32-162]; forced vital capacity, 164 mL [84-244]) and improved patient-reported symptoms. Adverse events were similar across groups. CONCLUSIONS:Consistent with overall ASPEN results, brensocatib 10 mg and 25 mg reduced exacerbation frequency vs placebo in Japanese patients with bronchiectasis. Lung function, patient-reported symptoms, and safety data were consistent with overall ASPEN trial results. CLINICAL TRIAL REGISTRATION:NCT04594369.

BACKGROUND:Rhinoviruses (RV) are the most common respiratory viruses globally and a major cause of airway symptoms in children and individuals with asthma. Although more than 170 RV types exist across 3 species (RV-A, RV-B, RV-C), type-specific circulation patterns and age-related prevalence remain poorly defined. OBJECTIVE:We characterized long-term circulation patterns, age-specific prevalence, and host genetic associations of RV types using a large pediatric dataset. METHODS:We retrospectively analyzed 12,697 RV infections identified by PCR and partial sequencing from 11,960 nasal samples collected between 1997 and 2025 across 20 pediatric populations in Finland, Australia, and the United States, including 10 National Institutes of Health ECHO cohort sites. RV types were classified by species, and host CDHR3 rs6967330 genotype, which impacts RV-C receptor binding, was available for a subset. Temporal stability, phylogenetic clustering, and detection frequency by age were assessed by stream graph visualization, slope modeling, and Spearman correlation. RESULTS:RV type circulation was remarkably stable over 3 decades; 97% of types had slope estimates whose 95% confidence intervals included zero, indicating no significant temporal change. Commonly detected types did not consistently cluster phylogenetically, suggesting that capsid sequence similarity does not fully explain fitness. Certain types (eg, A36, A101, C15) were prevalent across all pediatric age groups, whereas others (eg, C2, C40, A78, A12) were more frequent in younger children. The CDHR3 rs6967330-A risk allele was associated with increased overall RV-C infection but it did not alter the distribution of common versus rare RV-C types. CONCLUSION:RV type prevalence and age-specific patterns have remained stable for decades, supporting targeted interventions focused on consistently circulating types and those most common in young children.

Rationale: The club cell secretory protein (CC16), encoded by the SCGB1A1 gene, has an anti-inflammatory role in airways diseases, including asthma (Li, AJRCCM 2023; Voraphani, AJRCCM 2023). We hypothesize that additional pathway genes regulated or co-expressed with CC16 have cumulative effects on asthma severity outcomes by modulating airway inflammation and maintaining lung homeostasis. Methods: As published previously, four genes were downregulated in CC16 knockout experiments and correlated with CC16 levels: BPIFA1, SFTPD, LTF, and LYZ (Iannuzo, Front. Immunol 2023). We developed a four-gene biomarker score in 94 patients with asthma from the NHLBI-sponsored Severe Asthma Research Program (SARP3) who underwent research bronchoscopy for lower airway epithelial brushings, RNA isolation, and bulk RNA sequencing. We log-transformed the raw values of each transcript; obtained standardized residuals from regression models that included sex, age, and batch effects; and summed the standardized residuals of all four proteins to estimate a standardized sum score (Zhai, JACI Allergy 2024). Logistic regression models tested the four-gene score, three-gene score without LTF, and individual transcripts for associations with exacerbations during 12-month follow-up and zero-inflated negative binomial regression for number of exacerbations. Results: 30.85% percent of 94 patients experienced at least one exacerbation at the end of follow-up. The CC16-associated four-gene biomarker score showed protective effects on asthma exacerbation risk with a 54% percent reduction in exacerbation risk for every one-fold higher score (OR=0.46, 95% CI: 0.27-0.78, p =0.0040, Figure 1). Transcript expression of BPIFA1 (OR=0.87, 95% CI:0.66-1.16, p=0.337), SFTPD (OR=0.33, 95% CI:0.04-2.52, p=0.283), LYZ (OR=0.62, 95%CI:0.28-1.39, p=0.248), and LTF (OR=0.36, 95% CI:0.18-0.74, p=0.0053) all indicated protective directionality with respect to exacerbation risk. However, only LTF demonstrated a statistically significant association. When we excluded LTF, the remaining three-gene score showed a trend toward association with risk (OR=0.64, 95% CI:0.40-1.03, p=0.068) and was significantly associated with number of exacerbations (RR=0.49, 95% CI:0.26-0.95, p=0.034). Compared to LTF alone (OR=0.48, PPV=0.50, NPV=0.71, Sensitivity=0.14, AUC=0.65), the combined four-gene score (OR=0.46, PPV=0.60, NPV= 0.73, Sensitivity=0.21, AUC=0.68) showed improved predictive performance. Conclusions: We identified a CC16-associated transcriptomic predictive score for asthma exacerbations, with LTF showing the strongest effect. Although the other three genes showed individually weak and non-significant associations with exacerbations, the three gene score was significant for number of exacerbations.We demonstrate the potential of this transcriptomic score as a predictive biomarker for asthma severity-related outcomes. Further research investigating these genes and their interaction with other CC16-associated immune pathways could provide insight into therapeutic targets.

Rationale: We previously derived three asthma phenotypes from clinical data, quantitative computed tomography (qCT), and computational fluid dynamics (CFD)-incorporated cluster analysis: old, obese, and intermediate groups (AJRCCM 2024;209:A2776). The obese asthma cluster demonstrated worse asthma control test (ACT) and asthma quality of life (AQLQ). We hypothesize that obese asthmatics may experience greater aerodynamic force and pressure in airways, which contribute to poorer asthma control in the setting of less mucus plugging. Methods: Inspiratory and expiratory CTs, clinical data, and mucus plug scores were collected from 172 asthma patients in SARP III. For 97 subjects with high-quality image segmentation, we used CFD airflow simulations of breathing (tidal volume: 6 ml/kg) to compute air flowrate and pressure in individual branches throughout the entire conducting airways. Average aerodynamic force applied around segmental branches were analyzed from pressure and cross-sectional area of each branch at airway generation 3-6. To discriminate effects of obesity and aging, 172 patients were classified into four groups based on age (>65 years old) and obesity (BMI>30). Kruskal-Wallis with Dunn's test and Spearman correlation analysis were used, with statistical significance by p<0.05. Results: CFD-derived peak expiratory aerodynamic force and air pressure around segmental airways were greater in the obese cluster (105±40 µN, 22.7±9.2 Pa, p<0.001 for all) than those in the others (old: 43±13 µN, 8.5±2.8 Pa; intermediate: 37±15 µN, 7.3±3.2 Pa), where force was highly associated with BMI (r=0.81, p<0.001). The obese cluster had higher flowrate (0.004±0.001 L/s, p<0.001) than the others (old: 0.003±0.001 L/s; intermediate: 0.002±0.001 L/s) but did not exhibit different airway luminal area. Greater force and pressure were associated with worse ACT (force r=-0.34, p<0.001; pressure r=0.35, p<0.001) and AQLQ scores (force r=-0.32, p=0.001; pressure r=-0.30, p=0.003). Elderly obese asthmatics had less mucus plugging (1.25±2.2, p=0.004), less functional small airway disease percentage (fSAD%, 7.1±9.0%, p=0.002), and higher post-bronchodilator FEV1/FVC (89.5±12.2%, p=0.004) than the elderly non-obese group (mucus score=9.3±7.2, fSAD%=22.1±18.0%, FEV1/FVC=71.5±7.3%), without significant difference from non-elderly obese asthmatics. Conclusion: qCT-CFD analysis showed that obese patients with asthma may experience higher aerodynamic force and pressure during normal breathing than nonobese asthmatics. This may contribute to greater remodeling and healthcare utilization despite preserved lung function and less mucus plugging in elderly obese asthmatics than in elderly nonobese asthmatics.

Background: Asthma pathophysiology is associated with mitochondrial dysfunction. Mitochondrial DNA copy number (mtDNA-CN) has been used as a proxy of mitochondrial function, with lower levels indicating mitochondrial dysfunction in population studies of cardiovascular diseases and cancers. Objectives: We investigated whether lower levels of mtDNA-CN are associated with asthma diagnosis, severity, and exacerbations. Methods: mtDNA-CN is evaluated in blood from 2 cohorts: UK Biobank (UKB) (asthma, n = 39,147; no asthma, n = 302,302) and Severe Asthma Research Program (SARP) (asthma, n = 1283; nonsevere asthma, n = 703). Results: Individuals with asthma have lower mtDNA-CN compared to individuals without asthma in UKB (beta,-0.006 [95% confidence interval,-0.008 to-0.003], P = 6.23 x 10-6). Lower mtDNA-CN is associated with asthma prevalence, but not severity in UKB or SARP. mtDNA-CN declines with age but is lower in individuals with asthma than in individuals without asthma at all ages. In a 1-year longitudinal study in SARP, mtDNA-CN was associated with risk of exacerbation; those with highest mtDNA-CN had the lowest risk of exacerbation (odds ratio 0.333 [95% confidence interval, 0.173 to 0.542], P = .001). Biomarkers of inflammation and oxidative stress are higher in individuals with asthma than without asthma, but the lower mtDNA-CN in asthma is independent of general inflammation or oxidative stress. Mendelian randomization studies suggest a potential causal relationship between asthma-associated genetic variants and mtDNA-CN. Conclusion: mtDNA-CN is lower in asthma than in no asthma and is associated with exacerbations. Low mtDNA-CN in asthma is not mediated through inflammation but is associated with a genetic predisposition to asthma. (J Allergy Clin Immunol 2025;155:1224-35.)

Rationale: A subset of patients with asthma have airway pathology characterized by a thickened subepithelial basement membrane zone ("BMZ-thick asthma"). Objectives: To characterize the clinical features of BMZ-thick asthma and to determine if BMZ thickness accompanies specific patterns of inflammation in the airway epithelium. Methods: Design-based stereology was used to quantify BMZ thickness in endobronchial biopsy tissue sections from 109 patients with asthma and 41 healthy control subjects from SARP (Severe Asthma Research Program)-3, whose participants had undergone spirometry and gene expression profiling in airway epithelial brushings. Measurements and Main Results: The upper 90th-percentile value for BMZ thickness in the healthy cohort was 2.9 μM, and 35% of the asthma cohort had values above this upper limit. Compared with patients with BMZ-thin asthma, patients with BMZ-thick asthma were younger and had higher blood eosinophil numbers and serum immunoglobulin E concentrations that were specific to animal proteins. Mean prebronchodilator FEV1 was significantly lower in patients with BMZ-thick asthma than in those with BMZ-thin asthma, but postbronchodilator FEV1 was not. Upregulation of genes signifying IL-13 activation and the presence of mast cells were evident in epithelial brushings in patients with BMZ-thick asthma, but gene signatures for activation by IFN-γ or IL-17 were not. Conclusions: A thickened BMZ marks a subset of younger patients with asthma characterized by higher immunoglobulin E concentrations to animal aeroallergens and by increased bronchomotor tone occurring in the context of airway epithelial cells activated by IL-13 and infiltrated by mast cells.

Rationale: In 2023, the American Thoracic Society recommended a transition to race-neutral lung function interpretation, citing evidence of under-estimated disease severity in Black populations. Findings from other respiratory conditions suggest race-neutral interpretation may improve the correlation between lung function and self-reported symptom burden. In the United States, Black patients are over-represented among those with severe asthma, but the impact of the transition in this disease is presently unknown. Methods: We analyzed baseline data from Black and White participants the Severe Asthma Research Program (SARP) III cohort, enrolled from 2012-2015. Spirometry was converted from the Global Lung Initiative (GLI) 2012 equations, which are race-based, to the GLI-Global race-neutral equations. We calculated the proportion of participants who had their asthma control reclassified under the race-neutral equations, using previous SARP definitions of FEV1<80% of FEV1/FVC

BACKGROUND:α1-Antitrypsin deficiency is caused by rare pathogenic variants in SERPINA1, the strongest genetic risk factor for chronic obstructive pulmonary disease. Few studies have evaluated the effects of SERPINA1 variation on asthma severity accounting for critical gene-by-environment interactions with smoking. OBJECTIVE:To characterize the influence of SERPINA1 variation on asthma severity. METHODS:DNA samples from 847 non-Hispanic White and 446 African American participants from the Severe Asthma Research Program underwent SERPINA1 resequencing to identify rare variants. An independent population of 1955 individuals with asthma and α1-antitrypsin concentrations from a Cleveland Clinic Health System (CCHS) database were evaluated for severity measures. RESULTS:In White participants, a history of minimum smoking significantly interacted with SERPINA1 low-to-rare frequency variation to determine risk for asthma-related health care utilization. This was attributed to protease inhibitor type Z heterozygotes (MZ, N = 11), who had a higher frequency of emergency department (ED) visits (6 [54.5%] MZ heterozygotes, odds ratio [OR] = 7.60, 95% confidence interval [CI] = 1.71-39.7, P = .010), hospitalization (5 [45.5%], OR = 16.1, 95% CI = 2.64-150.4, P = .0050) in the past year, and lifetime intensive care unit (ICU) admissions (6 [54.5%], OR = 12.5, 95% CI = 2.44-75.6, P = .0032) compared with 146 individuals without SERPINA1 variants (30 [20.5%] reporting ED visits, 17 [11.6%] hospitalization, and 15 [10.3%] ICU admission). SERPINA1 variant-by-ever smoking interactions in African American participants for ED visits (P = .069) were related to 4 of 6 compound heterozygotes reporting an ED visit. In CCHS, α1-antitrypsin concentrations were inversely associated with moderate-to-severe asthma risk (OR = 0.97 per 10 mg/dL increase in α1-antitrypsin, 95% CI = 0.94-0.99, P = .010) and exacerbations (OR = 0.84 per 10 mg/dL, 95% CI = 0.76-0.94, P = .002). CONCLUSIONS:SERPINA1 variation and α1-antitrypsin concentrations impact asthma severity through gene-environment interactions with minimum smoking.

Asthma morbidity significantly affects children of all racial backgrounds; however, African American children experience a greater disease burden than children from other racial groups. Despite the known influence of air pollution on asthma outcomes, its role in the efficacy of asthma treatments remains underexplored. To examine how exposure to particulate matter (PM2.5), nitrogen dioxide (NO2), and ozone (O3) influenced treatment outcomes in the NIH AsthmaNet Best African American Response to Asthma Drugs (BARD) trial. The BARD trial randomized 224 African American children to four asthma treatments consisting of inhaled corticosteroids (ICS) and long-acting beta antagonists (LABA) administered in a randomized crossover fashion. Treatment efficacy was assessed by the frequency of asthma exacerbations, percent predicted FEV1 (%PFEV1), and annualized asthma control days. Residential exposures to PM2.5, NO2, and O3 were estimated using a validated spatiotemporal model. Mixed effects models were used to evaluate the interaction between pollution exposure and treatment efficacy, adjusting for age, household triggers and trial site. PM2.5, NO2, and O3 exposures ranged substantially across participants: from 2.28 - 15.3 μg/m3, 2.34 - 63.7 ppm, and 2.57 - 23.7 ppb, respectively. NO2 and PM2.5 exposures were not associated with increased exacerbations post-treatment (p for interaction = 0.15 and 0.08, respectively). However, NO2 exposure significantly modified the effect of high-dose ICS+LABA therapy on lung function. Children with below median NO2 exposures while on ICS + LABA had a reduction of 5.86 (1.16, 10.56) in %PFEV1 compared to those with above-median NO2 exposures. Residential high NO2 exposure may significantly attenuate the efficacy of ICS+LABA therapy on lung function in African American children. These findings suggest the need to consider environmental factors in clinical trials and asthma management strategies.

Rationale: Thymic stromal lymphopoietin (TSLP) is an alarmin whose activity regulates type 2 immune responses in asthma. Tezepelumab, which inhibits TSLP, is associated with a reduction in airway mucus plugs in asthma patients1, but it is not known how airway TSLP levels relate to measures of airway mucus plugging and air trapping. Methods: Using a V-Plex immunoassay (Meso Scale Discovery, ACRO Biosystems), we measured TSLP protein levels in sputum samples from 412 participants in the Severe Asthma Research Program (SARP)-3 and from 104 health controls. Deep phenotyping of SARP-3 participants includes measures of mucus plugging and of air trapping (AT) in computed tomography (CT) lung scans and of gene expression in cells in induced sputum. Results: The upper 95th percentile value of TSLP in sputum in health (1.5pg/mL) was used to divide asthma patients into TSLP-high and -low subgroups. Compared to TSLP-low asthma patients, TSLP-high asthma was significantly associated with higher gene expression for MUC5AC and lower expression for MUC5B in sputum (Panels A and B). In addition, TSLP-high asthma was significantly associated with higher mucus plug score on CT lung images (Panel C) and sputum TSLP levels in the high mucus plug subgroup (segment score ≥4) were significantly higher than in the zero-mucus plug subgroup (Panel D). Furthermore, TSLP-high asthma associated with AT, as evidenced by higher values for LAA856% (low attenuation areas less than -856 Hounsfield units) and for the AT segment score (Panels E and F). Conclusion: Patients with TSLP-high asthma, as defined by TSLP protein levels in sputum, have higher mucus plug scores and increased air trapping. 1. Nordenmark L et al. NEJM Evid 2023. DOI: 10.1056/EVIDoa2300135

Asthma is a heterogeneous disease with variable presentation and characteristics. There is a critical need to identify underlying molecular endotypes of asthma. We performed the largest transcriptomic analysis of 808 bronchial epithelial cell samples across 11 independent cohorts, including 3 cohorts from the Severe Asthma Research Program. Using seven datasets (218 patients with asthma, 148 healthy control subjects) as discovery cohorts, we identified 505 differentially expressed genes, which we validated in the remaining four datasets. Unsupervised clustering using the 505 differentially expressed genes identified four reproducible clusters of patients with asthma across all datasets, corresponding to healthy control subjects, patients with mild/moderate asthma, and patients with severe asthma with significant differences in several clinical markers of severity, including pulmonary function, Type 2 inflammation, fractional exhaled nitric oxide, and maximum bronchodilator reversibility. Importantly, we found the same clusters in pediatric patients using nasal lavage fluid cells, demonstrating the gene signature and clusters are not confounded by age and are conserved in both lower and upper airways. The four asthma clusters may represent a unifying framework for understanding the molecular heterogeneity of asthma. Further study could potentially enable a precision medicine approach of matching therapies with patients with asthma most likely to benefit.

BACKGROUND:A 2021 meta-analysis of 37 randomised controlled trials (RCTs) of vitamin D supplementation for prevention of acute respiratory infections (ARIs) revealed a statistically significant protective effect of the intervention (odds ratio [OR] 0·92 [95% CI 0·86 to 0·99]). Since then, six eligible RCTs have been completed, including one large trial (n=15 804). We aimed to re-examine the link between vitamin D supplementation and prevention of ARIs. METHODS:Updated systematic review and meta-analysis of data from RCTs of vitamin D for ARI prevention using a random effects model. Subgroup analyses were done to determine whether effects of vitamin D on risk of ARI varied according to baseline 25-hydroxyvitamin D (25[OH]D) concentration, dosing regimen, or age. We searched MEDLINE, EMBASE, the Cochrane Central Register of Controlled Trials, Web of Science, and the ClinicalTrials.gov between May 1, 2020 (end-date of search of our previous meta-analysis) and April 30, 2024. No language restrictions were imposed. Double-blind RCTs supplementing vitamin D for any duration, with placebo or lower-dose vitamin D control, were eligible if approved by a Research Ethics Committee and if ARI incidence was collected prospectively and pre-specified as an efficacy outcome. Aggregate data, stratified by baseline 25(OH)D concentration and age, were obtained from study authors. The study was registered with PROSPERO (no. CRD42024527191). FINDINGS:We identified six new RCTs (19 337 participants). Data were obtained for 16 085 (83·2%) participants in three new RCTs and combined with data from 48 488 participants in 43 RCTs identified in our previous meta-analysis. For the primary comparison of any vitamin D versus placebo, the intervention did not statistically significantly affect overall ARI risk (OR 0·94 [95% CI 0·88-1·00], p=0·057; 40 studies; 61 589 participants; I2=26·4%). Pre-specified subgroup analysis did not reveal evidence of effect modification by age, baseline vitamin D status, dosing frequency, or dose size. Vitamin D did not influence the proportion of participants experiencing at least one serious adverse event (OR 0·96 [95% CI 0·90-1·04]; 38 studies; I2=0·0%). A funnel plot showed left-sided asymmetry (p=0·0020, Egger's test). INTERPRETATION:This updated meta-analysis yielded a similar point estimate for the overall effect of vitamin D supplementation on ARI risk to that obtained previously, but the 95% CI for this effect estimate now includes 1·00, indicating no statistically significant protection. FUNDING:None.

Rationale: Corticosteroid-responsive type 2 (T2) inflammation underlies the T2-high asthma endotype. However, we hypothesized that type 1 (T1) inflammation, possibly related to viral infection, may also influence corticosteroid response. Objectives: To determine the frequency and within-patient variability of T1-high, T2-high, and T1/T2-high asthma endotypes and whether virally influenced T1-high disease influences corticosteroid response in asthma. Methods: Patients in SARP-3 (Severe Asthma Research Program-3) had sputum collected at baseline, after intramuscular (triamcinolone acetonide) corticosteroid treatment, and at 1- and 3-year follow-ups. Sputum cell RNA was used for whole-transcriptome gene network and viral metagenomic analyses. We then profiled patients as highly expressing T1 and/or T2 gene networks and established the influence of these endotypes on corticosteroid responsiveness and the likelihood of viral transcript detection in the airways. Measurements and Main Results: We found that 22% and 35% of patients with asthma highly expressed T1 and T2 network genes, respectively, and that 8.5% highly expressed both networks. Asthma severity outcomes were worse in T2-high compared with T1-high asthma and most severe in the T1-high/ T2-high subgroup. Corticosteroid treatment strongly suppressed T2 but poorly suppressed T1 gene expression, and corticosteroidassociated improvements in FEV1 occurred only in patients with T1-low/T2-high disease and not in patients with T1-high/T2-high disease. Viral metagenomic analyses uncovered that 24% of asthma sputum samples tested positive for a respiratory virus, and high viral carriage was associated with 14-fold increased risk of T1-high disease. Conclusions: Airway T1 immune responses are relatively common in asthma, are largely corticosteroid resistant, and are associated with subclinical viral infection.