Daily Respiratory Research Analysis
Three impactful respiratory studies stood out: a mechanistic eLife study demonstrates that multimeric secretory nasal IgA—generated by intranasal immunization—can confer protection against SARS‑CoV‑2 even when the monomer is non‑neutralizing; a JCI Insight cohort maps exercise stage–specific transpulmonary metabolite handling in CTD‑associated pulmonary hypertension; and a JAMA Network Open multicenter surveillance analysis clarifies severity patterns and risk factors in pediatric EV‑D68 respira
Summary
Three impactful respiratory studies stood out: a mechanistic eLife study demonstrates that multimeric secretory nasal IgA—generated by intranasal immunization—can confer protection against SARS‑CoV‑2 even when the monomer is non‑neutralizing; a JCI Insight cohort maps exercise stage–specific transpulmonary metabolite handling in CTD‑associated pulmonary hypertension; and a JAMA Network Open multicenter surveillance analysis clarifies severity patterns and risk factors in pediatric EV‑D68 respiratory illness across the US.
Research Themes
- Mucosal immunity and intranasal vaccination (secretory IgA function)
- Pulmonary vascular metabolism and exercise physiology in CTD-PAH
- Pediatric respiratory virus epidemiology and risk stratification (EV-D68)
Selected Articles
1. Comprehensive analysis of nasal IgA antibodies induced by intranasal administration of the SARS-CoV-2 spike protein.
Using monoclonal antibodies derived from intranasally immunized mice, the authors show that multimeric secretory IgA at the nasal mucosa can confer protection against SARS‑CoV‑2 even when the corresponding monomeric IgA is non-neutralizing. Prophylactic intranasal administration of multimeric secretory IgA reduced infection-induced weight loss in hamsters, establishing a mechanistic basis for nasal vaccine efficacy.
Impact: This is the first monoclonal-level demonstration of nasal secretory IgA function and shows that multimerization can convert non-neutralizing IgA into protective immunity at the site of viral entry, directly informing intranasal vaccine design.
Clinical Implications: Supports intranasal vaccine strategies and suggests that eliciting multimeric secretory IgA may provide mucosal protection even when serum neutralization is modest. Passive mucosal immunoprophylaxis with multimeric sIgA could be explored for high-risk exposure settings.
Key Findings
- Generated 99 nasal monoclonal IgA clones and 114 nonmucosal IgA/IgG clones from intranasally immunized mice.
- Lineage relationships indicate nonmucosal IgA plasma cells derive from B cells stimulated at the nasal mucosa.
- Multimeric secretory IgA conferred protection even when the corresponding monomeric IgA lacked neutralizing activity; ~70% of nasal IgA repertoire is non-neutralizing as monomers.
- Intranasal prophylaxis with multimeric secretory IgA reduced infection-induced weight loss in a hamster model.
Methodological Strengths
- Comprehensive monoclonal antibody panel from mucosal and nonmucosal compartments with epitope-resolved functional assays (binding, ACE2 blockade, neutralization).
- In vivo validation via intranasal prophylactic delivery in a hamster infection model.
Limitations
- Preclinical murine and hamster models; human clinical efficacy and durability not assessed.
- Breadth against antigenic variants and safety of repeated intranasal sIgA administration require further study.
Future Directions: Translate to human intranasal vaccine trials focusing on inducing multimeric sIgA; evaluate passive intranasal sIgA as post-exposure prophylaxis; map epitope-specific multimerization effects across variants.
Intranasal vaccination is an attractive strategy for preventing COVID-19 disease as it stimulates the production of multimeric secretory immunoglobulin A (IgA), the predominant antibody isotype in the mucosal immune system, at the target site of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) entry. Currently, intranasal vaccine efficacy is evaluated based on the measurement of polyclonal antibody titers in nasal lavage fluid. However, how individual multimeric secretory IgA protects the mucosa from SARS-CoV-2 infection remains to be elucidated. To understand the precise contribution and molecular nature of multimeric secretory IgA induced by intranasal vaccines, we developed 99 monoclonal IgA clones from nasal mucosa and 114 monoclonal IgA or IgG clones from nonmucosal tissues of mice that were intranasally immunized with the SARS-CoV-2 spike protein. The nonmucosal IgA clones exhibited shared origins and common and unique somatic mutations with the related nasal IgA clones, indicating that the antigen-specific plasma cells in the nonmucosal tissues originated from B cells stimulated at the nasal mucosa. Comparing the spike protein binding reactivity, angiotensin-converting enzyme-2-blocking, and in vitro SARS-CoV-2 virus neutralization of monomeric and multimeric secretory IgA pairs recognizing different epitopes showed that even non-neutralizing monomeric IgAs, which represent 70% of the nasal IgA repertoire, can protect against SARS-CoV-2 infection when expressed as multimeric secretory IgAs. We also demonstrated that the intranasal administration of multimeric secretory IgA delivered as prophylaxis in the hamster model reduced infection-induced weight loss. Our investigation is the first to demonstrate the function of nasal IgA at the monoclonal level, showing that nasal immunization can provide effective immunity against SARS-CoV-2 by inducing multimeric secretory IgAs at the target site of the virus infection.
2. Physiologic relevance of the transpulmonary metabolome in connective tissue disease-associated pulmonary vascular disease.
In 63 CTD patients undergoing exercise right heart catheterization, simultaneous pulmonary and systemic arterial sampling revealed exercise stage–specific transpulmonary metabolite gradients. Uptake/excretion patterns of acylcarnitines, glycolytic intermediates (including lactate), and tryptophan catabolites correlated with hemodynamics—particularly during free-wheeling—implicating dynamic pulmonary vascular metabolism in CTD-PAH pathogenesis.
Impact: Provides the first exercise stage–resolved map of transpulmonary metabolism in CTD-PAH using invasive physiology and metabolomics, linking metabolite handling to hemodynamics and identifying potential metabolic targets.
Clinical Implications: Suggests timing-sensitive metabolic interventions (e.g., targeting glycolysis, fatty acid oxidation, or tryptophan pathways) and supports incorporating physiologic stress testing when evaluating metabolic therapies in PAH.
Key Findings
- Identified distinct uptake/excretion of metabolites across the pulmonary vascular bed using simultaneous pulmonary and radial arterial sampling during staged exercise.
- Exercise stage–specific metabolite handling with strongest correlations to hemodynamics during resistance-free wheeling.
- At peak exercise, patients with more advanced disease exhibited net transpulmonary lactate uptake, highlighting glycolytic relevance.
- Demonstrated physiologic significance of acylcarnitines, glycolytic intermediates, and tryptophan catabolites implicated by prior models.
Methodological Strengths
- Prospective invasive physiology with simultaneous dual-site arterial sampling across multiple exercise stages.
- Mass spectrometry–based metabolomics with correlations to hemodynamic endpoints.
Limitations
- Single-disease context (CTD-associated PAH) and modest sample size; generalizability to idiopathic PAH or other PH groups requires validation.
- Observational design precludes causal inference; no interventional metabolic modulation tested.
Future Directions: Validate findings in larger, multi-etiology PH cohorts; integrate exercise metabolomics with imaging and right ventricular function; test timed metabolic interventions guided by physiologic stress.
Pathologic implications of dysregulated pulmonary vascular metabolism to pulmonary arterial hypertension (PAH) are increasingly recognized, but their clinical applications have been limited. We hypothesized that metabolite quantification across the pulmonary vascular bed in connective tissue disease-associated (CTD-associated) PAH would identify transpulmonary gradients of pathobiologically relevant metabolites, in an exercise stage-specific manner. Sixty-three CTD patients with established or suspected PAH underwent exercise right heart catheterization. Using mass spectrometry-based metabolomics, metabolites were quantified in plasma samples simultaneously collected from the pulmonary and radial arteries at baseline and during resistance-free wheeling, peak exercise, and recovery. We identified uptake and excretion of metabolites across the pulmonary vascular bed, unique and distinct from single vascular site analysis. We demonstrated the physiological relevance of metabolites previously shown to promote disease in animal models and end-stage human lung tissues, including acylcarnitines, glycolytic intermediates, and tryptophan catabolites. Notably, pulmonary vascular metabolite handling was exercise stage specific. Transpulmonary metabolite gradients correlated with hemodynamic endpoints largely during free-wheeling. Glycolytic intermediates demonstrated physiologic significance at peak exercise, including net uptake of lactate in those with more advanced disease. Contribution of pulmonary vascular metabolism to CTD-PAH pathogenesis and therapeutic candidacy of metabolism modulation must be considered in the context of physiologic stress.
3. Enterovirus D68-Associated Respiratory Illness in Children.
Across 976 pediatric EV‑D68 cases in a multicenter US surveillance network, half of hospitalized children had no underlying conditions; asthma history was common but not independently associated with oxygen or ICU needs. Non-asthma comorbidities significantly increased odds of supplemental oxygen and intensive care, underscoring risk beyond classic asthma/RAD groups.
Impact: Provides contemporary, multisite, active surveillance data clarifying severity distributions and risk factors in pediatric EV‑D68 respiratory illness, informing triage and hospital preparedness.
Clinical Implications: Non-asthma comorbidities should trigger heightened monitoring and early escalation plans in EV‑D68–positive hospitalized children; age and asthma/RAD alone should not be used to triage severity.
Key Findings
- Identified 976 EV‑D68–positive pediatric cases across 7 US centers (most in 2018 and 2022).
- Among 856 without viral codetection, 536 were hospitalized; 50% had no reported underlying conditions.
- Non-asthma comorbidities increased odds of supplemental oxygen (aOR 2.72) and ICU admission (aOR 3.09).
- Neither age nor asthma/RAD history was associated with oxygen receipt or ICU admission.
Methodological Strengths
- Active, prospective, population-based multisite surveillance across ED and inpatient settings.
- Multivariable regression focusing on a clean subset without viral codetection.
Limitations
- Cross-sectional analysis during defined testing windows; cannot infer causal pathways.
- Findings limited to medically attended cases; community burden and long-term outcomes not captured.
Future Directions: Expand to continuous surveillance with genomic tracking; evaluate long-term pulmonary sequelae; develop risk prediction tools incorporating comorbidity profiles.
IMPORTANCE: Enterovirus D68 (EV-D68) typically causes mild to severe acute respiratory illness (ARI). Testing and surveillance for EV-D68 in the US are limited, and important epidemiologic gaps remain. OBJECTIVE: To characterize the epidemiology and clinical severity of EV-D68 among US children seeking care for ARI from 2017 to 2022, using a multisite, active, systematic surveillance network. DESIGN, SETTING, AND PARTICIPANTS: This cross-sectional study collected data from the New Vaccine Surveillance Network, an active, prospective, population-based surveillance system of emergency departments (EDs) and hospitals at 7 US academic medical centers. Children with ARI and EV-D68-positive results were enrolled during platform-wide EV-D68 testing periods (July to October 2017, July to November 2018, July to November 2020, and July 2021 to December 2022). Included children were aged younger than 18 years, reported 1 or more qualifying ARI symptoms, with a symptom duration less than 14 days at enrollment. Data were analyzed from in October 2024. EXPOSURES: Laboratory-confirmed EV-D68 infection, including overall infections or those without viral codetection. MAIN OUTCOMES AND MEASURES: Trends and characteristics of EV-D68, including demographics, underlying conditions, and clinical severity by health care setting, were explored. Among hospitalized children with EV-D68-positive results without viral codetection, multivariable logistic regression was used to examine factors associated with receipt of (1) supplemental oxygen or (2) intensive care. RESULTS: From 2017 to 2022, 976 children with EV-D68-positive results were identified (median [IQR] age, 47 [18-63] months; 391 [40.1%] female); most were enrolled in 2018 (382 children) and 2022 (533 children). Among these, 856 had no viral codetection, of which 320 were discharged home from the ED (median [IQR] age, 33 [16-59] months; 180 male [56.3%]; 237 [74.1%] with no reported underlying conditions) and 536 were hospitalized (median [IQR] age, 40 [19-69] months; 330 male [61.6%]; 268 [50.0%] with no reported underlying conditions). Among those hospitalized, 199 (37.1%) reported a history of asthma or reactive airway disease (RAD) and 77 (14.4%) reported a condition other than asthma or RAD. Having an underlying condition other than asthma or RAD was associated with increased odds of receiving supplemental oxygen (adjusted odds ratio, 2.72; 95% CI, 1.43-5.18) or intensive care admission (adjusted odds ratio, 3.09; 95% CI, 1.72-5.56); neither age group nor history of asthma or RAD were associated with oxygen receipt or intensive care admission. CONCLUSIONS AND RELEVANCE: In this cross-sectional study of children with medically attended EV-D68 infections, EV-D68 was associated with severe disease in otherwise healthy children of all ages, and children with nonasthma or RAD comorbidities were at higher risk for severe outcomes when hospitalized.