Assessing the unified airway hypothesis in children via transcriptional profiling of the airway epithelium

Multifaceted roles of mitochondria in asthma

Mitochondria are essential organelles within cells, playing various roles in numerous cellular processes, including differentiation, growth, apoptosis, energy conversion, metabolism, and cellular immunity. The phenotypic variation of mitochondria is specific to different tissues and cell types, resulting in significant differences in their function, morphology, and molecular characteristics. Asthma is a chronic, complex, and heterogeneous airway disease influenced by external factors such as environmental pollutants and allergen exposure, as well as internal factors at the tissue, cellular, and genetic levels, including lung and airway structural cells, immune cells, granulocytes, and mast cells. Therefore, a comprehensive understanding of the specific responses of mitochondria to various external environmental stimuli and internal changes are crucial for elucidating the pathogenesis of asthma. Previous research on mitochondrial-targeted therapy for asthma has primarily focused on antioxidants. Consequently, it is necessary to summarize the multifaceted roles of mitochondria in the pathogenesis of asthma to discover additional strategies targeting mitochondria in this context. In this review, our goal is to describe the changes in mitochondrial function in response to various exposure factors across different cell types and other relevant factors in the context of asthma, utilizing a new mitochondrial terminology framework that encompasses cell-dependent mitochondrial characteristics, molecular features, mitochondrial activity, function, and behavior.

Asthma development is associated with low mucosal IL-10 during viral infections in early life

BACKGROUND

Viral infection is a common trigger of severe respiratory illnesses in early life and a risk factor for later asthma development. The mechanism leading to asthma could involve an aberrant airway immune response to viral infections, but this has rarely been studied in a human setting.

OBJECTIVES

To investigate in situ virus-specific differences in upper airway immune mediator levels during viral episodes of respiratory illnesses and the association with later asthma.

METHODS

We included 493 episodes of acute respiratory illnesses in 277 children aged 0-3 years from the COPSAC2010 mother-child cohort. Levels of 18 different immune mediators were assessed in nasal epithelial lining fluid using high-sensitivity MesoScale Discovery kits and compared between children with and without viral PCR-identification in nasopharyngeal samples. Finally, we investigated whether the virus-specific immune response was associated with asthma by age 6 years.

RESULTS

Viral detection were associated with upregulation of several Type 1 and regulatory immune mediators, including IFN-ɣ, TNF-α, CCL4, CXCL10 and IL-10 and downregulation of Type 2 and Type 17 immune mediators, including CCL13, and CXCL8 (FDR <0.05). Children developing asthma had decreased levels of IL-10 (FDR <0.05) during viral episodes compared to children not developing asthma.

CONCLUSION

We described the airway immune mediator profile during viral respiratory illnesses in early life and showed that children developing asthma by age 6 years have a reduced regulatory (IL-10) immune mediator level. This provides insight into the interplay between early-life viral infections, airway immunity and asthma development.

Itaconate suppresses house dust mite-induced allergic airways disease and Th2 cell differentiation

Itaconate was initially identified as an antimicrobial compound produced by myeloid cells. Beyond its antimicrobial role, itaconate may also serve as a crucial metabolic and immune modulator. We therefore examined the roles of aconitate decarboxylase 1 (Acod1) and itaconate in house dust mite (HDM)-sensitized and -challenged mice, a model of T helper 2 (Th2)-driven allergic airways disease. HDM treatment induced lung Acod1 mRNA expression and bronchoalveolar lavage (BAL) itaconate levels in wild-type C57BL/6 mice. Acod1 knockout mice (Acod1-KO) with negligible BAL itaconate showed heightened HDM-induced type 2 cytokine expression, increased serum IgE, and enhanced recruitment of Th2 cells in the lung, indicating a shift towards a more pronounced Th2 immune response. Acod1-KO mice also showed increased eosinophilic airway inflammation and hyperresponsiveness. Experiments in chimeric mice demonstrated that bone marrow from Acod1-KO mice is sufficient to increase type 2 cytokine expression in wild-type mice, and that restitution of bone marrow from wild type mice attenuates mRNA expression of Th2 cytokines in Acod1-KO mice. Specific deletion of Acod1 in lysozyme-secreting macrophages (LysM-cre+Acod1flox/flox) recapitulated the exaggerated phenotype observed in whole-body Acod1-KO mice. Adoptive transfer of Acod1-KO bone marrow-derived macrophages also increased lung mRNA expression of Th2 cytokines. In addition, treatment of Th2-polarized CD4 cells with itaconate impeded Th2 cell differentiation, as shown by reduced expression of Gata3 and decreased release of IL-5 and IL-13. Finally, public datasets of human samples show lower Acod1 expression in subjects with allergic asthma, consistent with a protective role of itaconate in asthma pathogenesis. Together, these data suggest that itaconate plays a protective, immunomodulatory role in limiting airway type 2 inflammation after allergen challenge by attenuating T cell responses.

Transcriptomic analysis of primary nasal epithelial cells reveals altered interferon signalling in preterm birth survivors at one year of age

Introduction: Many survivors of preterm birth (<37 weeks gestation) have lifelong respiratory deficits, the drivers of which remain unknown. Influencers of pathophysiological outcomes are often detectable at the gene level and pinpointing these differences can help guide targeted research and interventions. This study provides the first transcriptomic analysis of primary nasal airway epithelial cells in survivors of preterm birth at approximately 1 year of age. Methods: Nasal airway epithelial brushings were collected, and primary cell cultures established from term (>37 weeks gestation) and very preterm participants (≤32 weeks gestation). Ex vivo RNA was collected from brushings with sufficient cell numbers and in vitro RNA was extracted from cultured cells, with bulk RNA sequencing performed on both the sample types. Differential gene expression was assessed using the limma-trend pipeline and pathway enrichment identified using Reactome and GO analysis. To corroborate gene expression data, cytokine concentrations were measured in cell culture supernatant. Results: Transcriptomic analysis to compare term and preterm cells revealed 2,321 genes differentially expressed in ex vivo samples and 865 genes differentially expressed in cultured basal cell samples. Over one third of differentially expressed genes were related to host immunity, with interferon signalling pathways dominating the pathway enrichment analysis and IRF1 identified as a hub gene. Corroboration of disrupted interferon release showed that concentrations of IFN-α2 were below measurable limits in term samples but elevated in preterm samples [19.4 (76.7) pg/ml/µg protein, p = 0.03]. IFN-γ production was significantly higher in preterm samples [3.3 (1.5) vs. 9.4 (17.7) pg/ml/µg protein; p = 0.01] as was IFN-β [7.8 (2.5) vs. 13.6 (19.5) pg/ml/µg protein, p = 0.01]. Conclusion: Host immunity may be compromised in the preterm nasal airway epithelium in early life. Altered immune responses may lead to cycles of repeated infections, causing persistent inflammation and tissue damage which can have significant impacts on long-term respiratory function.

Causal associations between pediatric asthma and united airways disease: a two-sample Mendelian randomization analysis

Background

Prior observational research has indicated a potential link between pediatric asthma and united airways disease (UAD). However, these findings could be subject to confounding factors and reverse causation. Therefore, our study utilizes Mendelian randomization (MR) method to further investigate the causal relationship between pediatric asthma and UAD.

Methods

We conducted a comprehensive two-sample Mendelian randomization (MR) analysis to investigate the association between pediatric asthma and seven groups of UAD, including chronic sinusitis, chronic rhinitis, nasopharyngitis and pharyngitis, chronic diseases of tonsils and adenoids, chronic laryngitis and laryngotracheitis, chronic bronchitis, bronchiectasis, chronic obstructive pulmonary disease (COPD). The present study employed a range of methods for two-sample MR analysis, including inverse variance weighted (IVW), MR-Egger regression, Simple mode, weighted median, and weighted models. The conclusion of the MR analysis primarily relies on the IVW results, while other analytical methods are utilized as supplementary evidence to ensure result robustness in this MR analysis. And sensitivity analyses were conducted, including heterogeneity test, horizontal pleiotropy test, MR-PRESSO test, and leave-one-out analysis to validate the results.

Results

The results of the MR analysis indicate significant causal effects of pediatric asthma on chronic rhinitis, nasopharyngitis and pharyngitis (IVW: OR = 1.15, 95%CI: 1.05-1.26, p-value = 0.003), chronic diseases of tonsils and adenoids (IVW: OR = 1.07, 95%CI: 1.00-1.15, p-value = 0.038), chronic bronchitis (IVW: OR = 1.51, 95%CI: 1.42-1.62, p-value <0.001), bronchiectasis (IVW: OR = 1.51, 95%CI: (1.30-1.75), p-value <0.001), and COPD (IVW: OR = 1.43, 95%CI: 1.34-1.51, p-value <0.001). However, no significant causal association was observed between pediatric asthma and chronic sinusitis (IVW: OR = 1.00, 95%CI: 1.00-1.00, p-value = 0.085), chronic laryngitis and laryngotracheitis (IVW: OR = 1.05, 95%CI: 0.90-1.21, p-value = 0.558).

Conclusion

Our findings support a potential causal relationship between pediatric asthma and UAD, suggesting that pediatric asthma may be a potential risk factor for various UAD.

Proteomic and metabolomic proof of concept for unified airways in chronic rhinosinusitis and asthma

BACKGROUND

The pathogenesis of chronic rhinosinusitis with nasal polyps (CRSwNP) with comorbid asthma remains unclear.

OBJECTIVE

To assess upper and lower airway unity and identify a possible common pathogenesis in CRSwNP with asthma.

METHODS

This study analyzed the expression of proteins and metabolites in nasal lavage fluid cells (NLFCs) and induced sputum cells (ISCs). Differentially expressed proteins and their function-related metabolites in the upper and lower airways of patients having CRSwNP with or without asthma were identified; relevant signaling pathways were analyzed, and key pathway-related proteins were identified. Parallel reaction monitoring was used to verify these target proteins.

RESULTS

Protein or metabolite expression between NLFCs and ISCs was highly correlated and conservative on the basis of expression profiles and weighted gene coexpression network analysis. There were 17 differentially coexpressed proteins and their function-related 13 metabolites that were identified in the NLFCs and ISCs of CRSwNP, whereas 11 proteins and 11 metabolites were identified in CRSwNP with asthma. An asthma pathway was involved in the copathogenesis of upper and lower airways in whether CRSwNP or CRSwNP with asthma. The asthma pathway-related proteins proteoglycan 2 and eosinophil peroxidase, as the core of the protein-metabolism interaction networks between the upper and lower airways, were both highly coexpressed in NLFCs and ISCs in patients having either CRSwNP or CRSwNP with asthma by parallel reaction monitoring validation.

CONCLUSION

Proteomics and metabolomics reveal upper and lower airway unity. Asthma pathway-related proteins proteoglycan 2 and eosinophil peroxidase from the upper airway could be used to assess the potential risk of lower airway dysfunction in CRSwNP.

Airway epithelium respiratory illnesses and allergy (AERIAL) birth cohort: study protocol

Introduction

Recurrent wheezing disorders including asthma are complex and heterogeneous diseases that affect up to 30% of all children, contributing to a major burden on children, their families, and global healthcare systems. It is now recognized that a dysfunctional airway epithelium plays a central role in the pathogenesis of recurrent wheeze, although the underlying mechanisms are still not fully understood. This prospective birth cohort aims to bridge this knowledge gap by investigating the influence of intrinsic epithelial dysfunction on the risk for developing respiratory disorders and the modulation of this risk by maternal morbidities, in utero exposures, and respiratory exposures in the first year of life.

Methods

The Airway Epithelium Respiratory Illnesses and Allergy (AERIAL) study is nested within the ORIGINS Project and will monitor 400 infants from birth to 5 years. The primary outcome of the AERIAL study will be the identification of epithelial endotypes and exposure variables that influence the development of recurrent wheezing, asthma, and allergic sensitisation. Nasal respiratory epithelium at birth to 6 weeks, 1, 3, and 5 years will be analysed by bulk RNA-seq and DNA methylation sequencing. Maternal morbidities and in utero exposures will be identified on maternal history and their effects measured through transcriptomic and epigenetic analyses of the amnion and newborn epithelium. Exposures within the first year of life will be identified based on infant medical history as well as on background and symptomatic nasal sampling for viral PCR and microbiome analysis. Daily temperatures and symptoms recorded in a study-specific Smartphone App will be used to identify symptomatic respiratory illnesses.

Discussion

The AERIAL study will provide a comprehensive longitudinal assessment of factors influencing the association between epithelial dysfunction and respiratory morbidity in early life, and hopefully identify novel targets for diagnosis and early intervention.

Exploring intrinsic variability between cultured nasal and bronchial epithelia in cystic fibrosis

The nasal and bronchial epithelium are unified parts of the respiratory tract that are affected in the monogenic disorder cystic fibrosis (CF). Recent studies have uncovered that nasal and bronchial tissues exhibit intrinsic variability, including differences in mucociliary cell composition and expression of unique transcriptional regulatory proteins which relate to germ layer origin. In the present study, we explored whether intrinsic differences between nasal and bronchial epithelial cells persist in cell cultures and affect epithelial cell functioning in CF. Comparison of air-liquid interface (ALI) differentiated epithelial cells from subjects with CF revealed distinct mucociliary differentiation states of nasal and bronchial cultures. Moreover, using RNA sequencing we identified cell type-specific signature transcription factors in differentiated nasal and bronchial epithelial cells, some of which were already poised for expression in basal progenitor cells as evidenced by ATAC sequencing. Analysis of differentiated nasal and bronchial epithelial 3D organoids revealed distinct capacities for fluid secretion, which was linked to differences in ciliated cell differentiation. In conclusion, we show that unique phenotypical and functional features of nasal and bronchial epithelial cells persist in cell culture models, which can be further used to investigate the effects of tissue-specific features on upper and lower respiratory disease development in CF.

The Unified Airway Hypothesis: Evidence From Specific Intervention With Anti-IL-5 Biologic Therapy

The unified airway hypothesis proposes that upper and lower airway diseases reflect a single pathological process manifesting in different locations within the airway. Functional, epidemiological, and pathological evidence has supported this well-established hypothesis for some time. However, literature on the pathobiologic roles/therapeutic targeting of eosinophils and IL-5 in upper and lower airway diseases (including asthma, chronic rhinosinusitis with nasal polyps [CRSwNP], and nonsteroidal anti-inflammatory drug-exacerbated respiratory disease) has recently emerged. This narrative review revisits the unified airway hypothesis by searching the scientific literature for recent learnings and clinical trial/real-world data that provide a novel perspective on its relevance for clinicians. According to the available literature, eosinophils and IL-5 have important pathophysiological roles in both the upper and lower airways, although the impact of eosinophils and IL-5 may vary in asthma and CRSwNP. Some differential effects of anti-IL-5 and anti-IL-5-receptor therapies in CRSwNP have been observed, requiring further investigation. However, pharmaceutical targeting of eosinophils and IL-5 in patients with upper, lower, and comorbid upper and lower airway inflammation has led to clinical benefit, supporting the hypothesis that these are linked conditions manifesting in different locations. Consideration of this approach may improve patient care and aid clinical decision making.

Airway transcriptome networks identify susceptibility to frequent asthma exacerbations in children

BACKGROUND

Frequent asthma exacerbators, defined as those experiencing more than 1 hospitalization in a year for an asthma exacerbation, represent an important subgroup of individuals with asthma. However, this group remains poorly defined and understudied in children.

OBJECTIVE

Our aim was to determine the molecular mechanisms underlying asthma pathogenesis and exacerbation frequency.

METHODS

We performed RNA sequencing of upper airway cells from both frequent and nonfrequent exacerbators enrolled in the Ohio Pediatric Asthma Repository.

RESULTS

Through molecular network analysis, we found that nonfrequent exacerbators display an increase in modules enriched for immune system processes, including type 2 inflammation and response to infection. In contrast, frequent exacerbators showed expression of modules enriched for nervous system processes, such as synaptic formation and axonal outgrowth.

CONCLUSION

These data suggest that the upper airway of frequent exacerbators undergoes peripheral nervous system remodeling, representing a novel mechanism underlying pediatric asthma exacerbation.

A Nasal Inflammatory Cytokine Signature Is Associated with Early Graft-versus-Host Disease of the Lung after Allogeneic Hematopoietic Cell Transplantation: Proof of Concept

Respiratory inflammation in bronchiolitis obliterans syndrome (BOS) after hematopoietic cell transplantation (HCT) is poorly understood. Clinical criteria for early-stage BOS (stage 0p) often capture HCT recipients without BOS. Measuring respiratory tract inflammation may help identify BOS, particularly early BOS. We conducted a prospective observational study in HCT recipients with new-onset BOS (n = 14), BOS stage 0p (n = 10), and recipients without lung impairment with (n = 3) or without (n = 8) chronic graft-versus-host disease and measured nasal inflammation using nasosorption at enrollment and then every 3 mo for 1 y. We divided BOS stage 0p into impairment that did not return to baseline values (preBOS, n = 6), or transient impairment (n = 4). We tested eluted nasal mucosal lining fluid from nasosorption matrices for inflammatory chemokines and cytokines using multiplex magnetic bead immunoassays. We analyzed between-group differences using the Kruskal-Wallis method, adjusting for multiple comparisons. We found increased nasal inflammation in preBOS and therefore directly compared patients with preBOS to those with transient impairment, as this would be of greatest diagnostic relevance. After adjusting for multiple corrections, we found significant increases in growth factors (FGF2, TGF-α, GM-CSF, VEGF), macrophage activation (CCL4, TNF-α, IL-6), neutrophil activation (CXCL2, IL-8), T cell activation (CD40 ligand, IL-2, IL-12p70, IL-15), type 2 inflammation (eotaxin, IL-4, IL-13), type 17 inflammation (IL-17A), dendritic maturation (FLT3 ligand, IL-7), and counterregulatory molecules (PD-L1, IL-1 receptor antagonist, IL-10) in preBOS patients compared to transient impairment. These differences waned over time. In conclusion, a transient multifaceted nasal inflammatory response is associated with preBOS. Our findings require validation in larger longitudinal cohorts.

Airway Epithelium Respiratory Illnesses and Allergy (AERIAL) birth cohort: study protocol

Introduction

Recurrent wheezing disorders including asthma are complex and heterogeneous diseases that affect up to 30% of all children, contributing to a major burden on children, their families, and global healthcare systems. It is now recognized that a dysfunctional airway epithelium plays a central role in the pathogenesis of recurrent wheeze, although the underlying mechanisms are still not fully understood. This prospective birth cohort aims to bridge this knowledge gap by investigating the influence of intrinsic epithelial dysfunction on the risk for developing respiratory disorders and the modulation of this risk by maternal morbidities, in utero exposures, and respiratory exposures in the first year of life.

Methods and Analysis

The Airway Epithelium Respiratory Illnesses and Allergy (AERIAL) study is nested within the ORIGINS Project and will monitor 400 infants from birth to five years. The primary outcome of the AERIAL study will be the identification of epithelial endotypes and exposure variables that influence the development of recurrent wheezing, asthma, and allergic sensitisation. Nasal respiratory epithelium at birth to six weeks, one, three, and five years will be analysed by bulk RNA-seq and DNA methylation sequencing. Maternal morbidities and in utero exposures will be identified on maternal history and their effects measured through transcriptomic and epigenetic analyses of the amnion and newborn epithelium. Exposures within the first year of life will be identified based on infant medical history as well as on background and symptomatic nasal sampling for viral PCR and microbiome analysis. Daily temperatures and symptoms recorded in a study-specific Smartphone App will be used to identify symptomatic respiratory illnesses.

Ethics and Dissemination

Ethical approval has been obtained from Ramsey Health Care HREC WA-SA (#1908). Results will be disseminated through open-access peer-reviewed manuscripts, conference presentations, and through different media channels to consumers, ORIGINS families, and the wider community.

Network analyses of upper and lower airway transcriptomes identify shared mechanisms among children with recurrent wheezing and school-age asthma

Background

Predicting which preschool children with recurrent wheezing (RW) will develop school-age asthma (SA) is difficult, highlighting the critical need to clarify the pathogenesis of RW and the mechanistic relationship between RW and SA. Despite shared environmental exposures and genetic determinants, RW and SA are usually studied in isolation. Based on network analysis of nasal and tracheal transcriptomes, we aimed to identify convergent transcriptomic mechanisms in RW and SA.

Methods

RNA-sequencing data from nasal and tracheal brushing samples were acquired from the Gene Expression Omnibus. Combined with single-cell transcriptome data, cell deconvolution was used to infer the composition of 18 cellular components within the airway. Consensus weighted gene co-expression network analysis was performed to identify consensus modules closely related to both RW and SA. Shared pathways underlying consensus modules between RW and SA were explored by enrichment analysis. Hub genes between RW and SA were identified using machine learning strategies and validated using external datasets and quantitative reverse transcription-polymerase chain reaction (qRT-PCR). Finally, the potential value of hub genes in defining RW subsets was determined using nasal and tracheal transcriptome data.

Results

Co-expression network analysis revealed similarities in the transcriptional networks of RW and SA in the upper and lower airways. Cell deconvolution analysis revealed an increase in mast cell fraction but decrease in club cell fraction in both RW and SA airways compared to controls. Consensus network analysis identified two consensus modules highly associated with both RW and SA. Enrichment analysis of the two consensus modules indicated that fatty acid metabolism-related pathways were shared key signals between RW and SA. Furthermore, machine learning strategies identified five hub genes, i.e., CST1, CST2, CST4, POSTN, and NRTK2, with the up-regulated hub genes in RW and SA validated using three independent external datasets and qRT-PCR. The gene signatures of the five hub genes could potentially be used to determine type 2 (T2)-high and T2-low subsets in preschoolers with RW.

Conclusions

These findings improve our understanding of the molecular pathogenesis of RW and provide a rationale for future exploration of the mechanistic relationship between RW and SA.

Multi-omic association study identifies DNA methylation-mediated genotype and smoking exposure effects on lung function in children living in urban settings

Impaired lung function in early life is associated with the subsequent development of chronic respiratory disease. Most genetic associations with lung function have been identified in adults of European descent and therefore may not represent those most relevant to pediatric populations and populations of different ancestries. In this study, we performed genome-wide association analyses of lung function in a multiethnic cohort of children (n = 1,035) living in low-income urban neighborhoods. We identified one novel locus at the TDRD9 gene in chromosome 14q32.33 associated with percent predicted forced expiratory volume in one second (FEV1) (p = 2.4x10-9; βz = -0.31, 95% CI = -0.41- -0.21). Mendelian randomization and mediation analyses revealed that this genetic effect on FEV1 was partially mediated by DNA methylation levels at this locus in airway epithelial cells, which were also associated with environmental tobacco smoke exposure (p = 0.015). Promoter-enhancer interactions in airway epithelial cells revealed chromatin interaction loops between FEV1-associated variants in TDRD9 and the promoter region of the PPP1R13B gene, a stimulator of p53-mediated apoptosis. Expression of PPP1R13B in airway epithelial cells was significantly associated the FEV1 risk alleles (p = 1.3x10-5; β = 0.12, 95% CI = 0.06-0.17). These combined results highlight a potential novel mechanism for reduced lung function in urban youth resulting from both genetics and smoking exposure.

Transcriptomic analysis identified SLC40A1 as a key iron metabolism-related gene in airway macrophages in childhood allergic asthma

Introduction: Asthma is the most common chronic condition in children, with allergic asthma being the most common phenotype, accounting for approximately 80% of cases. Growing evidence suggests that disruption of iron homeostasis and iron regulatory molecules may be associated with childhood allergic asthma. However, the underlying molecular mechanism remains unclear. Methods: Three childhood asthma gene expression datasets were analyzed to detect aberrant expression profiles of iron metabolism-related genes in the airways of children with allergic asthma. Common iron metabolism-related differentially expressed genes (DEGs) across the three datasets were identified and were subjected to functional enrichment analysis. Possible correlations between key iron metabolism-related DEGs and type 2 airway inflammatory genes were investigated. Single-cell transcriptome analysis further identified major airway cell subpopulations driving key gene expression. Key iron metabolism-related gene SLC40A1 was validated in bronchoalveolar lavage (BAL) cells from childhood asthmatics with control individuals by quantitative reverse transcription-polymerase chain reaction (qRT-PCR) and immunofluorescence. The intracellular iron content in BAL cells was assessed by Perls iron staining and the iron levels in BAL supernatant was measured by iron assay to assess airway iron metabolism status in childhood asthmatics. Results: Five common iron metabolism-related DEGs were identified, which were functionally related to iron homeostasis. Among these genes, downregulated SLC40A1 was strongly correlated with type 2 airway inflammatory markers and the gene signature of SLC40A1 could potentially be used to determine type 2-high and type 2-low subsets in childhood allergic asthmatics. Further single-cell transcriptomic analysis identified airway macrophages driving SLC40A1 expression. Immunofluorescence staining revealed colocalization of FPN (encoded by SLC40A1) and macrophage marker CD68. Down-regulation of SLC40A1 (FPN) was validated by qRT-PCR and immunofluorescence analysis. Results further indicated reduced iron levels in the BAL fluid, but increased iron accumulation in BAL cells in childhood allergic asthma patients. Furthermore, decreased expression of SLC40A1 was closely correlated with reduced iron levels in the airways of children with allergic asthma. Discussion: Overall, these findings reveal the potential role of the iron metabolism-related gene SLC40A1 in the pathogenesis of childhood allergic asthma.

Organotypic sinonasal airway culture systems are predictive of the mucociliary phenotype produced by bronchial airway epithelial cells

Differentiated air-liquid interface models are the current standard to assess the mucociliary phenotype using clinically-derived samples in a controlled environment. However, obtaining basal progenitor airway epithelial cells (AEC) from the lungs is invasive and resource-intensive. Hence, we applied a tissue engineering approach to generate organotypic sinonasal AEC (nAEC) epithelia to determine whether they are predictive of bronchial AEC (bAEC) models. Basal progenitor AEC were isolated from healthy participants using a cytological brushing method and differentiated into epithelia on transwells until the mucociliary phenotype was observed. Tissue architecture was assessed using H&E and alcian blue/Verhoeff-Van Gieson staining, immunofluorescence (for cilia via acetylated α-tubulin labelling) and scanning electron microscopy. Differentiation and the formation of tight-junctions were monitored over the culture period (day 1-32) by quantifying trans-epithelial electrical resistance. End point (day 32) tight junction protein expression was assessed using Western blot analysis of ZO-1, Occludin-1 and Claudin-1. Reverse transcription qPCR-array was used to assess immunomodulatory and autophagy-specific transcript profiles. All outcome measures were assessed using R-statistical software. Mucociliary architecture was comparable for nAEC and bAEC-derived cultures, e.g. cell density P = 0.55, epithelial height P = 0.88 and cilia abundance P = 0.41. Trans-epithelial electrical resistance measures were distinct from day 1-14, converged over days 16-32, and were statistically similar over the entire culture period (global P < 0.001). This agreed with end-point (day 32) measures of tight junction protein abundance which were non-significant for each analyte (P > 0.05). Transcript analysis for inflammatory markers demonstrated significant variation between nAEC and bAEC epithelial cultures, and favoured increased abundance in the nAEC model (e.g. TGFβ and IL-1β; P < 0.05). Conversely, the abundance of autophagy-related transcripts were comparable and the range of outcome measures for either model exhibited a considerably more confined uncertainty distribution than those observed for the inflammatory markers. Organotypic air-liquid interface models of nAEC are predictive of outcomes related to barrier function, mucociliary architecture and autophagy gene activity in corresponding bAEC models. However, inflammatory markers exhibited wide variation which may be explained by the sentinel immunological surveillance role of the sinonasal epithelium.

Mepolizumab for urban children with exacerbation-prone eosinophilic asthma in the USA (MUPPITS-2): a randomised, double-blind, placebo-controlled, parallel-group trial

BACKGROUND

Black and Hispanic children living in urban environments in the USA have an excess burden of morbidity and mortality from asthma. Therapies directed at the eosinophilic phenotype reduce asthma exacerbations in adults, but few data are available in children and diverse populations. Furthermore, the molecular mechanisms that underlie exacerbations either being prevented by, or persisting despite, immune-based therapies are not well understood. We aimed to determine whether mepolizumab, added to guidelines-based care, reduced the number of asthma exacerbations during a 52-week period compared with guidelines-based care alone.

METHODS

This is a randomised, double-blind, placebo-controlled, parallel-group trial done at nine urban medical centres in the USA. Children and adolescents aged 6-17 years, who lived in socioeconomically disadvantaged neighbourhoods and had exacerbation-prone asthma (defined as ≥two exacerbations in the previous year) and blood eosinophils of at least 150 cells per μL were randomly assigned 1:1 to mepolizumab (6-11 years: 40 mg; 12-17 years: 100 mg) or placebo injections once every 4 weeks, plus guideline-based care, for 52 weeks. Randomisation was done using a validated automated system. Participants, investigators, and the research staff who collected outcome measures remained masked to group assignments. The primary outcome was the number of asthma exacerbations that were treated with systemic corticosteroids during 52 weeks in the intention-to-treat population. The mechanisms of treatment response were assessed by study investigators using nasal transcriptomic modular analysis. Safety was assessed in the intention-to-treat population. This trial is registered with ClinicalTrials.gov, NCT03292588.

FINDINGS

Between Nov 1, 2017, and Mar 12, 2020, we recruited 585 children and adolescents. We screened 390 individuals, of whom 335 met the inclusion criteria and were enrolled. 290 met the randomisation criteria, were randomly assigned to mepolizumab (n=146) or placebo (n=144), and were included in the intention-to-treat analysis. 248 completed the study. The mean number of asthma exacerbations within the 52-week study period was 0·96 (95% CI 0·78-1·17) with mepolizumab and 1·30 (1·08-1·57) with placebo (rate ratio 0·73; 0·56-0·96; p=0·027). Treatment-emergent adverse events occurred in 42 (29%) of 146 participants in the mepolizumab group versus 16 (11%) of 144 participants in the placebo group. No deaths were attributed to mepolizumab.

INTERPRETATION

Phenotype-directed therapy with mepolizumab in urban children with exacerbation-prone eosinophilic asthma reduced the number of exacerbations.

FUNDING

US National Institute of Allergy and Infectious Diseases and GlaxoSmithKline.

Fractional Exhaled Nitric Oxide as a Marker of Mucosal Inflammation in Chronic Rhinosinusitis

BACKGROUND

Fractional exhaled nitric oxide (FeNO) is a cost-effective, noninvasive point-of-care test that has proven valuable in identifying patients with lower airway inflammation and predicting the likelihood of responsiveness to inhaled corticosteroid therapy in asthma. The utility of FeNO in upper airway disease, specifically in CRS, remains to be determined.

OBJECTIVE

The goal of this study was to test whether FeNO could serve as a noninvasive marker of sinonasal mucosal inflammation in CRS patients.

METHODS

FeNO was obtained using a nitric oxide analyzer (NIOX VERO) as well as nasal mucus, the 22-item Sinonasal Outcome Test (SNOT-22), University of Pennsylvania Smell Identification Test (UPSIT), and Lund-Kennedy endoscopic scores concurrently in 112 CRS patients. Nasal mucus was analyzed for cytokine expression using solid-phase sandwich ELISA. Linear regression with Spearman correlation coefficient was used to determine strength of relationship between variables.

RESULTS

CRS patients showed elevated FeNO levels with asthma (47.12 ± 5.21 ppb) or without asthma (43.24 ± 9.810 ppb). Elevated FeNO levels correlated with sinonasal mucosal inflammation, as determined by increased levels of CCL26 and TNFα in nasal mucus obtained from CRS patients. Furthermore, elevated FeNO levels selectively correlated with worsened SNOT-22 nasal symptoms (P = 0.03) and Lund-Kennedy endoscopic scores (P = 0.007), but did not correlate with UPSIT scores.

CONCLUSIONS

FeNO levels correlated with increased sinonasal mucosal inflammation and symptom severity in CRS regardless of asthma status. FeNO measurements may serve as a quick and noninvasive marker in evaluating CRS patients.

Development and validation of an RNA-seq-based transcriptomic risk score for asthma

Recent progress in RNA sequencing (RNA-seq) allows us to explore whole-genome gene expression profiles and to develop predictive model for disease risk. The objective of this study was to develop and validate an RNA-seq-based transcriptomic risk score (RSRS) for disease risk prediction that can simultaneously accommodate demographic information. We analyzed RNA-seq gene expression data from 441 asthmatic and 254 non-asthmatic samples. Logistic least absolute shrinkage and selection operator (Lasso) regression analysis in the training set identified 73 differentially expressed genes (DEG) to form a weighted RSRS that discriminated asthmatics from healthy subjects with area under the curve (AUC) of 0.80 in the testing set after adjustment for age and gender. The 73-gene RSRS was validated in three independent RNA-seq datasets and achieved AUCs of 0.70, 0.77 and 0.60, respectively. To explore their biological and molecular functions in asthma phenotype, we examined the 73 genes by enrichment pathway analysis and found that these genes were significantly (p < 0.0001) enriched for DNA replication, recombination, and repair, cell-to-cell signaling and interaction, and eumelanin biosynthesis and developmental disorder. Further in-silico analyses of the 73 genes using Connectivity map shows that drugs (mepacrine, dactolisib) and genetic perturbagens (PAK1, GSR, RBM15 and TNFRSF12A) were identified and could potentially be repurposed for treating asthma. These findings show the promise for RNA-seq risk scores to stratify and predict disease risk.

Viral Induced Effects on a Vulnerable Epithelium; Lessons Learned From Paediatric Asthma and Eosinophilic Oesophagitis

The epithelium is integral to the protection of many different biological systems and for the maintenance of biochemical homeostasis. Emerging evidence suggests that particular children have epithelial vulnerabilities leading to dysregulated barrier function and integrity, that resultantly contributes to disease pathogenesis. These epithelial vulnerabilities likely develop in utero or in early life due to various genetic, epigenetic and environmental factors. Although various epithelia are uniquely structured with specific function, prevalent allergic-type epithelial diseases in children potentially have common or parallel disease processes. These include inflammation and immune response dysregulation stemming from atypical epithelial barrier function and integrity. Two diseases where aetiology and pathogenesis are potentially linked to epithelial vulnerabilities include Paediatric Asthma and Eosinophilic Oesophagitis (EoE). For example, rhinovirus C (RV-C) is a known risk factor for paediatric asthma development and is known to disrupt respiratory epithelial barrier function causing acute inflammation. In addition, EoE, a prevalent atopic condition of the oesophageal epithelium, is characterised by similar innate immune and epithelial responses to viral injury. This review examines the current literature and identifies the gaps in the field defining viral-induced effects on a vulnerable respiratory epithelium and resulting chronic inflammation, drawing from knowledge generated in acute wheezing illness, paediatric asthma and EoE. Besides highlighting the importance of epithelial structure and barrier function in allergic disease pathogenesis regardless of specific epithelial sub-types, this review focuses on the importance of examining other parallel allergic-type disease processes that may uncover commonalities driving disease pathogenesis. This in turn may be beneficial in the development of common therapeutics for current clinical management and disease prevention in the future.

Lower respiratory tract infections in early life are associated with obstructive sleep apnea diagnosis during childhood in a large birth cohort

STUDY OBJECTIVES

Several birth cohorts have defined the pivotal role of early lower respiratory tract infections (LRTI) in the inception of pediatric respiratory conditions. However, the association between early LRTI and the development of obstructive sleep apnea (OSA) in children has not been established.

METHODS

To investigate whether early LRTIs increase the risk of pediatric OSA, we analyzed clinical data in children followed during the first 5 years in the Boston Birth Cohort (n = 3114). Kaplan-Meier survival estimates and Cox proportional hazards models adjusted by pertinent covariates were used to evaluate the risk of OSA by the age of 5 years between children with LRTI during the first 2 years of life in comparison to those without LRTI during this period.

RESULTS

Early life LRTI increased the risk of pediatric OSA independently of other pertinent covariates and risk factors (hazard ratio, 1.53; 95% CI, 1.15 to 2.05). Importantly, the association between LRTI and pediatric OSA was limited to LRTIs occurring during the first 2 years of life. Complementarily to this finding, we observed that children who had severe respiratory syncytial virus bronchiolitis during infancy had two times higher odds of OSA at 5 years in comparison with children without this exposure (odds ratio, 2.09; 95% CI, 1.12 to 3.88).

CONCLUSIONS

Children with severe LRTIs in early life have significantly increased risk of developing OSA during the first 5 years of life. Our results offer a new paradigm for investigating novel mechanisms and interventions targeting the early pathogenesis of OSA in the pediatric population.

Dysregulated Notch Signaling in the Airway Epithelium of Children with Wheeze

The airway epithelium of children with wheeze is characterized by defective repair that contributes to disease pathobiology. Dysregulation of developmental processes controlled by Notch has been identified in chronic asthma. However, its role in airway epithelial cells of young children with wheeze, particularly during repair, is yet to be determined. We hypothesized that Notch is dysregulated in primary airway epithelial cells (pAEC) of children with wheeze contributing to defective repair. This study investigated transcriptional and protein expression and function of Notch in pAEC isolated from children with and without wheeze. Primary AEC of children with and without wheeze were found to express all known Notch receptors and ligands, although pAEC from children with wheeze expressed significantly lower NOTCH2 (10-fold, p = 0.004) and higher JAG1 (3.5-fold, p = 0.002) mRNA levels. These dysregulations were maintained in vitro and cultures from children with wheeze displayed altered kinetics of both NOTCH2 and JAG1 expression during repair. Following Notch signaling inhibition, pAEC from children without wheeze failed to repair (wound closure rate of 76.9 ± 3.2%). Overexpression of NOTCH2 in pAEC from children with wheeze failed to rescue epithelial repair following wounding. This study illustrates the involvement of the Notch pathway in airway epithelial wound repair in health and disease, where its dysregulation may contribute to asthma development.

Endotype of allergic asthma with airway obstruction in urban children

BACKGROUND

Black and Hispanic children growing up in disadvantaged urban neighborhoods have the highest rates of asthma and related morbidity in the United States.

OBJECTIVES

This study sought to identify specific respiratory phenotypes of health and disease in this population, associations with early life exposures, and molecular patterns of gene expression in nasal epithelial cells that underlie clinical disease.

METHODS

The study population consisted of 442 high-risk urban children who had repeated assessments of wheezing, allergen-specific IgE, and lung function through 10 years of age. Phenotypes were identified by developing temporal trajectories for these data, and then compared to early life exposures and patterns of nasal epithelial gene expression at 11 years of age.

RESULTS

Of the 6 identified respiratory phenotypes, a high wheeze, high atopy, low lung function group had the greatest respiratory morbidity. In early life, this group had low exposure to common allergens and high exposure to ergosterol in house dust. While all high-atopy groups were associated with increased expression of a type-2 inflammation gene module in nasal epithelial samples, an epithelium IL-13 response module tracked closely with impaired lung function, and a MUC5AC hypersecretion module was uniquely upregulated in the high wheeze, high atopy, low lung function group. In contrast, a medium wheeze, low atopy group showed altered expression of modules of epithelial integrity, epithelial injury, and antioxidant pathways.

CONCLUSIONS

In the first decade of life, high-risk urban children develop distinct phenotypes of respiratory health versus disease that link early life environmental exposures to childhood allergic sensitization and asthma. Moreover, unique patterns of airway gene expression demonstrate how specific molecular pathways underlie distinct respiratory phenotypes, including allergic and nonallergic asthma.

Advances in asthma: New understandings of asthma's natural history, risk factors, underlying mechanisms, and clinical management

The last 2 years yielded a proliferation of high-quality asthma research. These include new understandings of the incidence and natural history of asthma, findings on the effects of exposure to air pollution, allergens, and intake of acetaminophen, soy isoflavones, and polyunsaturated fatty acids, and exposure to microbial products. The past 2 years have benefited from great strides in determining potential mechanisms of asthma development and asthma exacerbations. These novel understandings led to identification and development of exciting new avenues for potential therapeutic intervention. Finally, there has been significant progress made in the development of tools to facilitate the diagnosis of asthma and measurement of airway physiology and in precision diagnostic approaches. Asthma guidelines were updated and new insights into the pharmacologic management of patients, including biologics, were reported. We review the most notable advances in the natural history of asthma, risk factors for the development of asthma, underlying mechanisms, diagnostic approaches, and treatments. Although greater knowledge of the mechanisms underlying responses and nonresponses to novel therapeutics and across asthma phenotypes would be beneficial, the progress over just the past 2 years has been immense and impactful.

Increased MMP12 mRNA expression in induced sputum was correlated with airway eosinophilic inflammation in asthma patients: evidence from bioinformatic analysis and experiment verification

BACKGROUND

Asthma is a common chronic airway inflammatory disease worldwide. Studies on gene expression profiles in induced sputum may provide noninvasive diagnostic biomarkers and therapeutic targets for asthma.

OBJECTIVE

To investigate mRNA expression of MMP12 in induced sputum and its relationship with asthma airway eosinophilic inflammation.

METHODS

GSE76262 dataset was analyzed using R software, weighted gene coexpression network analysis (WGCNA), and protein-protein interaction (PPI) network construction. The top ten hub genes were screened with Cytoscape software (version 3.8.4). We then verified the mRNA expression of MMP12 in two other datasets (GSE137268 and GSE74075) via ROC curve estimates and our induced sputum samples using real-time quantitative reverse transcription polymerase chain reaction (qRT-PCR). Finally, we explored the correlation between MMP12 with asthmatic eosinophilic-related indicators.

RESULTS

We obtained the top ten hub genes, namely, CCL17, CCL2, CSF1, CCL22, CCR3, CD69, FCGR2B, CD1C, CD1E, and MMP12 via expression profile screening and validation on the GSE76262 dataset. MMP12 was selected as the candidate gene through further validation on GSE137268 and GSE74075 datasets. Finally, we demonstrated that the mRNA expression of MMP12 is significantly upregulated in induced sputum of asthmatic patients (p<0.05) and significantly correlated with eosinophilic-related indicators (p<0.05). These findings indicated that MMP12 can act as a diagnostic biomarker for asthma.

CONCLUSION

Our study successfully identified and demonstrated that MMP12 is a potential diagnostic biomarker for asthma due to its high expression and association with eosinophilic-related indicators. The results of this study can provide novel insights into asthmatic diagnosis and therapy in the future.

Nasal airway epithelial repair after very preterm birth

Preterm birth rates are increasing and now account for >11% of global births. Simultaneously, advances in neonatal care have led to increased survival of lower gestation neonates. A complication of preterm birth, and the biggest determinant of survival, is lung and airway immaturity. After preterm birth, the immature respiratory system is exposed to pro-inflammatory stimuli like injury from resuscitation and oxygen toxicity. The airway epithelium, the physical barrier between insults and the airways, is particularly vulnerable to injury. If epithelial barrier integrity cannot be restored rapidly following damage (i.e. via aberrant repair), the respiratory system is left unprotected, increasing the risk of infection, inflammation and tissue damage. Altered epithelial repair may play an important role in the ongoing respiratory health problems experienced by preterm survivors, including severe respiratory infections throughout early life, or low and declining lung function [1–3]. Deficits are further exacerbated in those with bronchopulmonary dysplasia (BPD). The mechanisms contributing to ongoing respiratory problems are currently unknown, although probably begin in early life. Until now, understanding the role of the preterm epithelial barrier has been limited by a lack of appropriate cellular models. Our study aimed to assess the reparative capacity of the airway epithelium in survivors of preterm birth and its association with early life outcomes, with the hypothesis that preterm airway epithelial cells have an abnormal repair mechanism.

Nasal epithelialcells from very preterm infants have a functional defect in their ability to repair beyond the first year of life, and failed repair may be associated with antenatal steroid exposurehttps://bit.ly/39OFJs7

Nasal upregulation of CST1 in dog-sensitised children with severe allergic airway disease

Background

The clinical presentation of children sensitised to dog dander varies from asymptomatic to severe allergic airway disease, but the genetic mechanisms underlying these differences are not clear. The objective of the present study was to investigate nasal transcriptomic profiles associated with dog dander sensitisation in school children and to reveal clinical symptoms related with these profiles.

Methods

RNA was extracted from nasal epithelial cell brushings of children sensitised to dog dander and healthy controls. Blood sample analyses included IgE against dog dander, dog allergen molecules, other airborne and food allergens, basophil activation and white blood cell counts. Clinical history of asthma and rhinitis was recorded, and lung function was assessed (spirometry, methacholine provocation and exhaled nitric oxide fraction).

Results

The most overexpressed gene in children sensitised to dog dander compared to healthy controls was CST1, coding for Cystatin 1. A cluster of these children with enhanced CST1 expression showed lower forced expiratory volume in 1 s, increased bronchial hyperreactivity, pronounced eosinophilia and higher basophil allergen threshold sensitivity compared with other children sensitised to dog dander. In addition, multi-sensitisation to lipocalins was more common in this group.

Conclusions

Overexpression of CST1 is associated with more severe allergic airway disease in children sensitised to dog dander. CST1 is thus a possible biomarker of the severity of allergic airway disease and a possible therapeutic target for the future treatment of airborne allergy.

Airway Remodeling Factors During Early-Life Rhinovirus Infection and the Effect of Premature Birth

Background: Early rhinovirus (RV) infection is a strong risk factor for asthma development. Airway remodeling factors play a key role in the progression of the asthmatic condition. We hypothesized that RV infection in young children elicits the secretion of growth factors implicated in airway remodeling and asthma progression. Methods: We examined the nasal airway production of remodeling factors in children ( ≤ 2 years old) hospitalized due to PCR-confirmed RV infection. Airway remodeling proteins included: MMP-1, MMP-2, MMP-7, MMP-9, MMP-10, TIMP-1, TIMP-2, EGF, Angiopoietin-2, G-CSF, BMP-9, Endoglin, Endothelin-1, Leptin, FGF-1, Follistatin, HGF, HB-EGF, PLGF, VEGF-A, VEGF-C, VEGF-D, FGF-2, TGF-β1, TGF-β2, TGF-β3, PDGF AA, PDGF BB, SPARC, Periostin, OPN, and TGF-α. Results: A total of 43 young children comprising RV cases (n = 26) and uninfected controls (n = 17) were included. Early RV infection was linked to (1) enhanced production of several remodeling factors (e.g., HGF, TGFα), (2) lower MMP-9/TIMP-2 and MMP-2/TIMP-2 ratios, and (3) increased MMP-10/TIMP-1 ratios. We also found that relative to term infants, severely premature children had reduced MMP-9/TIMP-2 ratios at baseline. Conclusion: RV infection in young children elicits the airway secretion of growth factors implicated in angiogenesis, fibrosis, and extracellular matrix deposition. Our results highlight the potential of investigating virus-induced airway remodeling growth factors during early infancy to monitor and potentially prevent chronic progression of respiratory disorders in all ages.

Novel Antioxidant Therapy with the Immediate Precursor to Glutathione, γ-Glutamylcysteine (GGC), Ameliorates LPS-Induced Cellular Stress in In Vitro 3D-Differentiated Airway Model from Primary Cystic Fibrosis Human Bronchial Cells

Systemic glutathione deficiency, inflammation, and oxidative stress are hallmarks of cystic fibrosis (CF), an inherited disease that causes persistent lung infections and severe damage to the respiratory system and many of the body organs. Improvements to current antioxidant therapeutic strategies are needed. The dietary supplement, γ-glutamylcysteine (GGC), which is the immediate precursor to glutathione, rapidly boosts cellular glutathione levels following a single dose in healthy individuals. Efficacy of GGC against oxidative stress induced by Pseudomonas aeruginosa, which is a common and chronic pathogen infecting lungs of CF patients, remains unassessed. Primary mucocilliary differentiated airway (bronchial and/or nasal) epithelial cells were created from four individuals with CF. Airway oxidative stress and inflammation was induced by P. aeruginosa lipopolysaccharide (LPS). Parameters including global proteomics alterations, cell redox state (glutathione, oxidative stress), pro-inflammatory mediators (IL-8, IDO-1), and cellular health (membrane integrity, stress granule formation, cell metabolic viability) were assayed under six experimental conditions: (1) Mock, (2) LPS-challenged (3) therapeutic, (4) prophylactic (5) therapeutic and prophylactic and (6) GGC alone. Proteomic analysis identified perturbation of several pathways related to cellular respiration and stress responses upon LPS challenge. Most of these were resolved when cells were treated with GGC. While GGC did not resolve LPS-induced IL-8 and IDO-1 activity, it effectively attenuated LPS-induced oxidative stress and stress granule formation, while significantly increasing total intracellular glutathione levels, metabolic viability and improving epithelial cell barrier integrity. Both therapeutic and prophylactic treatments were successful. Together, these findings indicate that GGC has therapeutic potential for treatment and prevention of oxidative stress-related damage to airways in cystic fibrosis.

Effect of monoclonal antibody drug therapy on mucosal biomarkers in airway disease: A systematic review

BACKGROUND

Monoclonal antibody therapies have a growing role in treating refractory airway disease.

OBJECTIVE

The review aimed to summarize the response of respiratory mucosa to monoclonal antibody treatments in inflammatory airway conditions.

DESIGN

We conducted a systematic review including risk of bias assessment.

DATA SOURCES

MEDLINE, EMBASE and PubMed from 1 January 2000 to 16 November 2019 were searched.

ELIGIBILITY CRITERIA

Eligible studies assessed the immunological and histological response of airway mucosa to monoclonal antibody therapy compared with baseline or a comparison group in patients with respiratory diseases (asthma, chronic rhinosinusitis and allergic rhinitis). Any prospective interventional studies, including randomized controlled trials (RCTs) and single-arm trials, were eligible.

RESULTS

There were 4195 articles screened, and full-text analysis produced n = 11 studies with extractable data. Nine were RCTs, and two were single-arm trials. These studies focused on asthma (n = 9 articles), chronic rhinosinusitis (n = 1) and allergic rhinitis (n = 1). Five monoclonal antibody drugs were assessed (omalizumab, mepolizumab, dupilumab, benralizumab and tralokinumab). Risk of bias was low (n = 6) or unclear (n = 3) in the RCTs and moderate in the single-arm trials. Omalizumab reduced the mucosal concentration of its target, IgE. Dupilumab reduced the concentration of one of its targets, IL-13, but not IL-4. Omalizumab, mepolizumab and benralizumab reduced tissue eosinophil cell density. Dupilumab decreased mucosal eosinophil granule proteins. Tralokinumab did not affect airway mucosa.

CONCLUSIONS

Knowledge of the expected biological response of monoclonal antibody therapy on biomarkers in disease tissue provides an important supplement to data about clinical outcomes. An understanding of the biological effect is essential to identify likely responders, reasons for treatment failure and necessary adjustments to monoclonal antibody treatment. Further investigation into the effect of monoclonal antibody therapy on disease mucosa and more precise endotyping are required to move closer to achieving personalized medicine.