Association Between T2-related Comorbidities and Effectiveness of Biologics in Severe Asthma.

Rationale: Previous studies investigating the impact of comorbidities on the effectiveness of biologic agents have been relatively small and of short duration and have not compared classes of biologic agents. Objectives: To determine the association between type 2-related comorbidities and biologic agent effectiveness in adults with severe asthma (SA). Methods: This cohort study used International Severe Asthma Registry data from 21 countries (2017-2022) to quantify changes in four outcomes before and after biologic therapy-annual asthma exacerbation rate, FEV1% predicted, asthma control, and long-term oral corticosteroid daily dose-in patients with or without allergic rhinitis, chronic rhinosinusitis (CRS) with or without nasal polyps (NPs), NPs, or eczema/atopic dermatitis. Measurements and Main Results: Of 1,765 patients, 1,257, 421, and 87 initiated anti-IL-5/5 receptor, anti-IgE, and anti-IL-4/13 therapies, respectively. In general, pre- versus post-biologic therapy improvements were noted in all four asthma outcomes assessed, irrespective of comorbidity status. However, patients with comorbid CRS with or without NPs experienced 23% fewer exacerbations per year (95% CI, 10-35%; P < 0.001) and had 59% higher odds of better post-biologic therapy asthma control (95% CI, 26-102%; P < 0.001) than those without CRS with or without NPs. Similar estimates were noted for those with comorbid NPs: 22% fewer exacerbations and 56% higher odds of better post-biologic therapy control. Patients with SA and CRS with or without NPs had an additional FEV1% predicted improvement of 3.2% (95% CI, 1.0-5.3; P = 0.004), a trend that was also noted in those with comorbid NPs. The presence of allergic rhinitis or atopic dermatitis was not associated with post-biologic therapy effect for any outcome assessed. Conclusions: These findings highlight the importance of systematic comorbidity evaluation. The presence of CRS with or without NPs or NPs alone may be considered a predictor of the effectiveness of biologic agents in patients with SA.

Exploring Definitions and Predictors of Severe Asthma Clinical Remission Post-Biologic in Adults.

RATIONALE: There is no consensus on criteria to include in an asthma remission definition in real-life. Factors associated with achieving remission post-biologic-initiation remain poorly understood. OBJECTIVES: To quantify the proportion of adults with severe asthma achieving multi-domain-defined remission post-biologic-initiation and identify pre-biologic characteristics associated with achieving remission which may be used to predict it. METHODS: This was a longitudinal cohort study using data from 23 countries from the International Severe Asthma Registry. Four asthma outcome domains were assessed in the 1-year pre- and post-biologic-initiation. A priori-defined remission cut-offs were: 0 exacerbations/year, no long-term oral corticosteroid (LTOCS), partly/well-controlled asthma, and percent predicted forced expiratory volume in one second ≥80%. Remission was defined using 2 (exacerbations + LTOCS), 3 (+control or +lung function) and 4 of these domains. The association between pre-biologic characteristics and post-biologic remission was assessed by multivariable analysis. MEASUREMENTS AND MAIN RESULTS: 50.2%, 33.5%, 25.8% and 20.3% of patients met criteria for 2, 3 (+control), 3 (+lung function) and 4-domain-remission, respectively. The odds of achieving 4-domain remission decreased by 15% for every additional 10-years asthma duration (odds ratio: 0.85; 95% CI: 0.73, 1.00). The odds of remission increased in those with fewer exacerbations/year, lower LTOCS daily dose, better control and better lung function pre-biologic-initiation. CONCLUSIONS: One in 5 patients achieved 4-domain remission within 1-year of biologic-initiation. Patients with less severe impairment and shorter asthma duration at initiation had a greater chance of achieving remission post-biologic, indicating that biologic treatment should not be delayed if remission is the goal. This article is open access and distributed under the terms of the Creative Commons Attribution Non-Commercial No Derivatives License 4.0 (http://creativecommons.org/licenses/by-nc-nd/4.0/).

Analysis of comorbidities and multimorbidity in adult patients in the International Severe Asthma Registry.

BACKGROUND: Investigation for the presence of asthma comorbidities is recommended by the Global Initiative for Asthma because their presence can complicate asthma management. OBJECTIVE: To understand the prevalence and pattern of comorbidities and multimorbidity in adults with severe asthma and their association with asthma-related outcomes. METHODS: This was a cross-sectional study using data from the International Severe Asthma Registry from 22 countries. A total of 30 comorbidities were identified and categorized a priori as any of the following: (1) potentially type 2-related comorbidities, (2) potentially oral corticosteroid (OCS)-related comorbidities, or (3) comorbidities mimicking or aggravating asthma. The association between comorbidities and asthma-related outcomes was investigated using multivariable models adjusted for country, age at enrollment, and sex (ie male or female). RESULTS: Of the 11,821 patients, 69%, 67%, and 55% had at least 1 potentially type 2-related, potentially OCS-related, or mimicking or aggravating comorbidities, respectively; 57% had 3 or more comorbidities, and 33% had comorbidities in all 3 categories. Patients with allergic rhinitis, nasal polyposis, and chronic rhinosinusitis experienced 1.12 (P = .003), 1.16 (P < .001), and 1.29 times (P < .001) more exacerbations per year, respectively, than those without. Patients with nasal polyposis and chronic rhinosinusitis were 40% and 46% more likely (P < .001), respectively, to have received long-term (LT) OCS. All assessed potential OCS-related comorbidities (except obesity) were associated with a greater likelihood of LTOCS use (odds ratios [ORs]: 1.23-2.77) and, except for dyslipidemia, with a greater likelihood of uncontrolled asthma (ORs: 1.29-1.68). All mimicking or aggravating comorbidities assessed were associated with more exacerbations (1.24-1.68 times more), all (except bronchiectasis) with increased likelihood of uncontrolled asthma (ORs: 1.57-1.81), and all (except chronic obstructive pulmonary disease) with increased likelihood of LTOCS use (ORs: 1.37-1.57). A greater number of comorbidities was associated with worse outcomes. CONCLUSION: In a global study, comorbidity or multimorbidity is reported in most adults with severe asthma and is associated with poorer asthma-related outcomes. CLINICAL TRIAL REGISTRATION: The International Severe Asthma Registry database has ethical approval from the Anonymous Data Ethics Protocols and Transparency (ADEPT) committee (ADEPT0218) and is registered with the European Union Electronic Register of Post-Authorization Studies (European Network Centres for Pharmacoepidemiology and Pharmacovigilance [ENCEPP]/DSPP/23720). The study was designed, implemented, and reported in compliance with the European Network Centres for Pharmacoepidemiology and Pharmacovigilance (ENCEPP) Code of Conduct (EMA 2014; EUPAS44024) and with all applicable local and international laws and regulations, and registered with ENCEPP (https://www.encepp.eu/encepp/viewResource.htm?id=48848). Governance was provided by ADEPT (registration number: ADEPT1121).

Comparative effectiveness of anti-IL5 and anti-IgE biologic classes in patients with severe asthma eligible for both.

BACKGROUND: Patients with severe asthma may present with characteristics representing overlapping phenotypes, making them eligible for more than one class of biologic. Our aim was to describe the profile of adult patients with severe asthma eligible for both anti-IgE and anti-IL5/5R and to compare the effectiveness of both classes of treatment in real life. METHODS: This was a prospective cohort study that included adult patients with severe asthma from 22 countries enrolled into the International Severe Asthma registry (ISAR) who were eligible for both anti-IgE and anti-IL5/5R. The effectiveness of anti-IgE and anti-IL5/5R was compared in a 1:1 matched cohort. Exacerbation rate was the primary effectiveness endpoint. Secondary endpoints included long-term-oral corticosteroid (LTOCS) use, asthma-related emergency room (ER) attendance, and hospital admissions. RESULTS: In the matched analysis (n = 350/group), the mean annualized exacerbation rate decreased by 47.1% in the anti-IL5/5R group and 38.7% in the anti-IgE group. Patients treated with anti-IL5/5R were less likely to experience a future exacerbation (adjusted IRR 0.76; 95% CI 0.64, 0.89; p < 0.001) and experienced a greater reduction in mean LTOCS dose than those treated with anti-IgE (37.44% vs. 20.55% reduction; p = 0.023). There was some evidence to suggest that patients treated with anti-IL5/5R experienced fewer asthma-related hospitalizations (IRR 0.64; 95% CI 0.38, 1.08), but not ER visits (IRR 0.94, 95% CI 0.61, 1.43). CONCLUSIONS: In real life, both anti-IgE and anti-IL5/5R improve asthma outcomes in patients eligible for both biologic classes; however, anti-IL5/5R was superior in terms of reducing asthma exacerbations and LTOCS use.

FAM13A as potential therapeutic target in modulating TGF-ß-induced airway tissue remodeling in COPD.

Genome-wide association studies have shown that a gene variant in the Family with sequence similarity 13, member A (FAM13A) is strongly associated with reduced lung function and the appearance of respiratory symptoms in patients with chronic obstructive pulmonary disease (COPD). A key player in smoking-induced tissue injury and airway remodeling is the transforming growth factor-ß1 (TGF-ß1). To determine the role of FAM13A in TGF-ß1 signaling, FAM13A-/- airway epithelial cells were generated using CRISPR-Cas9, whereas overexpression of FAM13A was achieved using lipid nanoparticles. Wild-type (WT) and FAM13A-/- cells were treated with TGF-ß1, followed by gene and/or protein expression analyses. FAM13A-/- cells augmented TGF-ß1-induced increase in collagen type 1 (COL1A1), matrix metalloproteinase 2 (MMP2), expression compared with WT cells. This effect was mediated by an increase in ß-catenin (CTNNB1) expression in FAM13A-/- cells compared with WT cells after TGF-ß1 treatment. FAM13A overexpression was partially protective from TGF-ß1-induced COL1A1 expression. Finally, we showed that airway epithelial-specific FAM13A protein expression is significantly increased in patients with severe COPD compared with control nonsmokers, and negatively correlated with lung function. In contrast, ß-catenin (CTNNB1), which has previously been linked to be regulated by FAM13A, is decreased in the airway epithelium of smokers with COPD compared with non-COPD subjects. Together, our data showed that FAM13A may be protective from TGF-ß1-induced fibrotic response in the airway epithelium via sequestering CTNNB1 from its regulation on downstream targets. Therapeutic increase in FAM13A expression in the airway epithelium of smokers at risk for COPD, and those with mild COPD, may reduce the extent of airway tissue remodeling.

Olodaterol exerts anti-inflammatory effects on COPD airway epithelial cells.

BACKGROUND: Airway inflammation is a key feature of chronic obstructive pulmonary disease (COPD) and inhaled corticosteroids (ICS) remain the main treatment for airway inflammation. Studies have noted the increased efficacy of ICS and long-acting beta 2 agonist (LABA) combination therapy in controlling exacerbations and improving airway inflammation than either monotherapy. Further studies have suggested that LABAs may have inherent anti-inflammatory potential, but this has not been well-studied. OBJECTIVE: We hypothesize that the LABA olodaterol can inhibit airway inflammation resulting from exposure to respiratory syncytial virus (RSV) via its binding receptor, the ß2-adrenergic receptor. METHODS: Human bronchial epithelial brushing from patients with and without COPD were cultured into air-liquid interface (ALI) cultures and treated with or without olodaterol and RSV infection to examine the effect on markers of inflammation including interleukin-8 (IL-8) and mucus secretion. The cell line NCI-H292 was utilized for gene silencing of the ß2-adrenergic receptor via siRNA as well as receptor blocking via ICI 118,551 and butaxamine. RESULTS: At baseline, COPD-ALIs produced greater amounts of IL-8 than control ALIs. Olodaterol reduced RSV-mediated IL-8 secretion in both COPD and control ALIs and also significantly reduced Muc5AC staining in COPD-ALIs infected with RSV. A non-significant reduction was seen in control ALIs. Gene silencing of the ß2-adrenergic receptor in NCI-H292 negated the ability of olodaterol to inhibit IL-8 secretion from both RSV infection and lipopolysaccharide stimulus, as did blocking of the receptor with ICI 118,551 and butaxamine. CONCLUSIONS: Olodaterol exhibits inherent anti-inflammatory properties on the airway epithelium, in addition to its bronchodilation properties, that is mediated through the ß2-adrenergic receptor and independent of ICS usage.

IL-4Rα blockade reduces influenza-associated morbidity in a murine model of allergic asthma.

BACKGROUND: Asthma was identified as the most common comorbidity in hospitalized patients during the 2009 H1N1 influenza pandemic. We determined using a murine model of allergic asthma whether these mice experienced increased morbidity from pandemic H1N1 (pH1N1) viral infection and whether blockade of interleukin-4 receptor α (IL-4Rα), a critical mediator of Th2 signalling, improved their outcomes. METHODS: Male BALB/c mice were intranasally sensitized with house dust mite antigen (Der p 1) for 2 weeks; the mice were then inoculated intranasally with a single dose of pandemic H1N1 (pH1N1). The mice were administered intraperitoneally anti-IL-4Rα through either a prophylactic or a therapeutic treatment strategy. RESULTS: Infection with pH1N1 of mice sensitized to house dust mite (HDM) led to a 24% loss in weight by day 7 of infection (versus 14% in non-sensitized mice; p < .05). This was accompanied by increased viral load in the airways and a dampened anti-viral host responses to the infection. Treatment of HDM sensitized mice with a monoclonal antibody against IL-4Rα prior to or following pH1N1 infection prevented the excess weight loss, reduced the viral load in the lungs and ameliorated airway eosinophilia and systemic inflammation related to the pH1N1 infection. CONCLUSION: Together, these data implicate allergic asthma as a significant risk factor for H1N1-related morbidity and reveal a potential therapeutic role for IL-4Rα signalling blockade in reducing the severity of influenza infection in those with allergic airway disease.

Structural and functional variations in human bronchial epithelial cells cultured in air-liquid interface using different growth media.

The human bronchial epithelium is an important barrier tissue that is damaged or pathologically altered in various acute and chronic respiratory conditions. To represent the epithelial component of respiratory disease, it is essential to use a physiologically relevant model of this tissue. The human bronchial epithelium is a highly organized tissue consisting of a number of specialized cell types. Primary human bronchial epithelial cells (HBEC) can be differentiated into a mucociliated tissue in air-liquid interface (ALI) cultures using appropriately supplemented media under optimized growth conditions. We compared the histology, ciliary length, and function, diffusion, and barrier properties of HBEC from donors with no respiratory disease grown in two different media, PneumaCult-ALI or Bronchial Epithelial Differentiation Medium (BEDM). In the former group, HBEC have a more physiological pseudostratified morphology and mucociliary differentiation, including increased epithelial thickness, intracellular expression of airway-specific mucin protein MUC5AC, and total expression of cilia basal-body protein compared with cells from the same donor grown in the other medium. Baseline expression levels of inflammatory mediators, thymic stromal lymphopoietin (TSLP), soluble ST2, and eotaxin-3 were lower in PneumaCult-ALI. Additionally, the physiological cilia beat frequency and electrical barrier properties with transepithelial electrical resistance were significantly different between the two groups. Our study has shown that these primary cell cultures from the same donor grown in the two media possess variable structural and functional characteristics. Therefore, it is important to objectively validate primary epithelial cell cultures before experimentation to ensure they are appropriate to answer a specific scientific question.

IL-13 signaling through IL-13 receptor α2 mediates airway epithelial wound repair.

Asthma is an airway inflammatory disease characterized by epithelial barrier dysfunction and airway remodeling. Interleukin-13 (IL-13) is a pleiotropic cytokine shown to contribute to features of airway remodeling. We have previously demonstrated that IL-13 is an important mediator of normal airway epithelial repair and health. The role of IL-13 signaling via its receptor subunits (IL-13Rα1/IL-4Rα and IL-13Rα2) in airway epithelial repair and restoration of intact barrier function is not well understood and was investigated in this study using in vitro models. The blocking of IL-13 signaling via IL-13Rα2 significantly reduced airway epithelial repair by 24 h post-mechanical wounding in 1HAEo- cells. Expression and release of repair-mediating growth factor, heparin-binding epidermal growth factor (EGF)-like growth factor (HB-EGF), and subsequent activation of EGF receptor (EGFR) were also significantly reduced in response to wounding when IL-13Rα2 was blocked. Our data support that IL-13 signals via IL-13Rα2 to mediate normal airway epithelial repair via HB-EGF-dependent activation of EGFR. In human donor lung tissues, we observed that airway epithelium of asthmatics expressed significantly decreased levels of IL-13Rα2 and increased levels of IL-13Rα1 compared with nonasthmatics. Dysregulated expression of IL-13 receptor subunits in the airways of asthmatics may thus contribute to the epithelial barrier dysfunction observed in asthma.-Yang, S. J., Allahverdian, S., Saunders, A. D. R., Liu, E., Dorscheid, D. R. IL-13 signaling through IL-13 receptor α2 mediates airway epithelial wound repair.

A pilot randomized controlled trial on the impact of text messaging check-ins and a web-based asthma action plan versus a written action plan on asthma exacerbations.

OBJECTIVE: We compared electronic asthma action plans (eAAP) supported by automated text messaging service (SMS) with written asthma action plans (AAP) on assessing acceptability and asthma control improvement. We hypothesized that the patients in eAAP group would have more improvements in their quality of life, asthma control and decreased asthma exacerbations. METHODS: Patients with physician-diagnosed asthma having at least one asthma exacerbation in the previous 12 months were recruited. Participants received individualized action plans and were randomly assigned into either the intervention (eAAP) or control (AAP) group. Intervention participants received weekly SMS, triggering assessment of asthma control and viewing their eAAP. We assessed applicability of Telehealth platform on asthma exacerbations, asthma control, and quality of life over a 12-month period. RESULTS: 106 patients were enrolled (eAAP = 52, AAP = 54). The cumulative response rate to all weekly SMS check-ins was 68.4%. Overall, 28% of patients checked into their eAAP during the intervention period. There were fewer exacerbations in the eAAP group (18%) compared to the AAP group (RR = 0.82 [95%CI 0.49, 1.36]), (P = 0.44). The mean scores for asthma control and quality of life were higher in the eAAP group compared to the AAP group by 4% (RR = 1.04 [95%CI 0.83, 1.30]), (P = 0.73) and 5.5% (RR = 1.06 [95%CI 0.87, 1.28]), (P = 0.59), respectively, but were not statistically significant. CONCLUSIONS: We demonstrated that the eAAP presented improved asthma control outcomes, but as expected the sample size was inadequate to show a significant difference, but based on this pilot study we plan a larger appropriately powered randomized controlled trial (RCT).

Gene expression analysis in asthma using a targeted multiplex array.

BACKGROUND: Gene expression changes in the structural cells of the airways are thought to play a role in the development of asthma and airway hyperresponsiveness. This includes changes to smooth muscle contractile machinery and epithelial barrier integrity genes. We used a targeted gene expression arrays to identify changes in the expression and co-expression of genes important in asthma pathology. METHODS: RNA was isolated from the airways of donor lungs from 12 patients with asthma (8 fatal) and 12 non-asthmatics controls and analyzed using a multiplexed, hypothesis-directed platform to detect differences in gene expression. Genes were grouped according to their role in airway dysfunction: airway smooth muscle contraction, cytoskeleton structure and regulation, epithelial barrier function, innate and adaptive immunity, fibrosis and remodeling, and epigenetics. RESULTS: Differential gene expression and gene co-expression analyses were used to identify disease associated changes in the airways of asthmatics. There was significantly decreased abundance of integrin beta 6 and Ras-Related C3 Botulinum Toxin Substrate 1 (RAC1) in the airways of asthmatics, genes which are known to play an important role in barrier function. Significantly elevated levels of Collagen Type 1 Alpha 1 (COL1A1) and COL3A1 which have been shown to modulate cell proliferation and inflammation, were found in asthmatic airways. Additionally, we identified patterns of differentially co-expressed genes related to pathways involved in virus recognition and regulation of interferon production. 7 of 8 pairs of differentially co-expressed genes were found to contain CCCTC-binding factor (CTCF) motifs in their upstream promoters. CONCLUSIONS: Changes in the abundance of genes involved in cell-cell and cell-matrix interactions could play an important role in regulating inflammation and remodeling in asthma. Additionally, our results suggest that alterations to the binding site of the transcriptional regulator CTCF could drive changes in gene expression in asthmatic airways. Several asthma susceptibility loci are known to contain CTCF motifs and so understanding the role of this transcription factor may expand our understanding of asthma pathophysiology and therapeutic options.

Expression of surfactant protein D in airways of asthmatics and interleukin-13 modulation of surfactant protein D in human models of airway epithelium.

BACKGROUND: Surfactant protein D (SP-D), a pattern recognition molecule, has been shown to play roles in host defense such as opsonisation, aggregation of pathogens, and modulation of the inflammatory response. In light of infection-induced exacerbations and damage to the airway epithelium from inflammation, these functions of SP-D make it relevant in the development and pathogenesis of asthma. METHODS: Expression of SP-D was examined in human airway sections and primary airway epithelial cells (AEC) grown in air-liquid interface (ALI) cultures and comparisons were made between those from asthmatic and non-asthmatic donors. ALI cultures of AEC from non-asthmatic donors were examined for SP-D, Mucin 5AC, and cytokeratin-5 expression at different stages of differentiation. Interleukin-13 (IL-13) treatment of airway epithelium and its effect on SP-D expression was studied using ALI and monolayer cultures of primary AEC from non-asthmatic and asthmatic donors. RESULTS: Airway epithelium of asthmatics, compared to that of non-asthmatics, expressed increased levels of SP-D as demonstrated in airway tissue sections (fraction of epithelium 0.66 ± 0.026 vs. 0.50 ± 0.043, p = 0.004) and ALI cultures (fraction of epithelium 0.50 ± 0.08 vs. 0.25 ± 0.07). SP-D expression decreased as ALI cultures differentiated from 7 days to 21 days (fraction of epithelium 0.62 ± 0.04 to 0.23 ± 0.03, p = 0.004). Treatment with IL-13 decreased SP-D expression in both ALI cultures (fraction of epithelium 0.21 ± 0.06 vs. 0.62 ± 0.04, p = 0.0005) and monolayer cultures (protein expression fold change 0.62 ± 0.05) of non-asthmatic AEC; however, IL-13 had no significant effect on SP-D expression in monolayer cultures of asthmatic AEC. Experiments with non-asthmatic monolayer cultures indicate IL-13 exert its effect on SP-D through the IL-13 receptor alpha1 and transcription factor STAT6. CONCLUSIONS: SP-D is expressed differently in airways of asthmatics relative to that of non-asthmatics. This can have implications on the increased susceptibility to infections and altered inflammatory response in asthmatic patients. Future functional studies on the role of SP-D in asthma can provide better insight into defects in the structure and regulation of SP-D.

Urban particulate matter increases human airway epithelial cell IL-1ß secretion following scratch wounding and H1N1 influenza A exposure in vitro.

PURPOSE: The airway epithelium represents the first line of defense against inhaled environmental insults including air pollution, allergens, and viruses. Epidemiological and experimental evidence has suggested a link between air pollution exposure and the symptoms associated with respiratory viral infections. We hypothesized that multiple insults integrated by the airway epithelium NLRP3 inflammasome would result in augmented IL-1ß release and downstream cytokine production following respiratory virus exposure. MATERIALS AND METHODS: We performed in vitro experiments with a human airway epithelial cell line (HBEC-6KT) that involved isolated or combination exposure to mechanical wounding, PM10, house dust mite, influenza A virus, and respiratory syncytial virus. We performed confocal microscopy to image the localization of PM10 within HBEC-6KT and ELISAs to measure soluble mediator production. RESULTS: Airway epithelial cells secrete IL-1ß in a time-dependent fashion that is associated with internalization of PM10 particles. PM10 exposure primes human airway epithelial cells to subsequent models of cell damage and influenza A virus exposure. Prior PM10 exposure had no effect on IL-1ß responses to RSV exposure. Finally we demonstrate that PM10-priming of human airway epithelial cell IL-1ß and GM-CSF responses to influenza A exposure are sensitive to NLRP3 inflammasome inhibition. CONCLUSIONS: Our results suggest the NLRP3 inflammasome may contribute to exaggerated immune responses to influenza A virus following periods of poor air quality. Intervention strategies targeting the NLRP3 inflammasome in at risk individuals may restrict poor air quality priming of mucosal immune responses that result from subsequent viral exposures.

Exploring Definitions and Predictors of Response to Biologics for Severe Asthma.

BACKGROUND: Biologic effectiveness is often assessed as response, a term that eludes consistent definition. Identifying those most likely to respond in real-life has proven challenging. OBJECTIVE: To explore definitions of biologic responders in adults with severe asthma and investigate patient characteristics associated with biologic response. METHODS: This was a longitudinal cohort study using data from 21 countries, which shared data with the International Severe Asthma Registry. Changes in four asthma outcome domains were assessed in the 1-year period before and after biologic initiation in patients with a predefined level of prebiologic impairment. Responder cutoffs were 50% or greater reduction in exacerbation rate, 50% or greater reduction in long-term oral corticosteroid daily dose, improvement in one or more category in asthma control, and 100 mL or greater improvement in FEV1. Responders were defined using single and multiple domains. The association between prebiologic characteristics and postbiologic initiation response was examined by multivariable analysis. RESULTS: A total of 2,210 patients were included. Responder rate ranged from 80.7% (n = 566 of 701) for exacerbation response to 10.6% (n = 9 of 85) for a four-domain response. Many responders still exhibited significant impairment after biologic initiation: 46.7% (n = 206 of 441) of asthma control responders with uncontrolled asthma before the biologic still had incompletely controlled disease postbiologic initiation. Predictors of response were outcome-dependent. Lung function responders were more likely to have higher prebiologic FeNO (odds ratio = 1.20 for every 25-parts per billion increase), and shorter asthma duration (odds ratio = 0.81 for every 10-year increase in duration). Higher blood eosinophil count and the presence of type 2-related comorbidities were positively associated with higher odds of meeting long-term oral corticosteroid, control, and lung function responder criteria. CONCLUSIONS: Our findings underscore the multimodal nature of response, showing that many responders experience residual symptoms after biologic initiation and that predictors of response vary according to the outcome assessed.

Formation of a stable mimic of ambient particulate matter containing viable infectious respiratory syncytial virus and its dry-deposition directly onto cell cultures.

Epidemiological associations of worse respiratory outcomes from combined exposure to ambient particulate matter (PM) and respiratory viral infection suggest possible interactions between PM and viruses. To characterize outcomes of such exposures, we developed an in vitro mimic of the in vivo event of exposure to PM contaminated with respiratory syncytial virus (RSV). Concentration of infectious RSV stocks and a particle levitation apparatus were the foundations of the methodology developed to generate specific numbers of PM mimics (PM(Mimics)) of known composition for dry, direct deposition onto airway epithelial cell cultures. Three types of PM(Mimics) were generated for this study: (i) carbon alone (P(C)), (ii) carbon and infectious RSV (P(C+RSV)), and (iii) aerosols consisting of RSV (A(RSV)). P(C+RSV) were stable in solution and harbored infectious RSV for up to 6 months. Unlike A(RSV) infection, P(C+RSV) infection was found to be dynamin dependent and to cause lysosomal rupture. Cells dosed with PM(Mimics) comprised of RSV (A(RSV)), carbon (P(C)), or RSV and carbon (P(C+RSV)) responded differentially as exemplified by the secretion patterns of IL-6 and IL-8. Upon infection, and prior to lung cell death due to viral infection, regression analysis of these two mediators in response to incubation with A(RSV), P(C), or P(C+RSV) yielded higher concentrations upon infection with the latter and at earlier time points than the other PM(Mimics). In conclusion, this experimental platform provides an approach to study the combined effects of PM-viral interactions and airway epithelial exposures in the pathogenesis of respiratory diseases involving inhalation of environmental agents.

Airway Epithelial-Derived Immune Mediators in COVID-19.

The airway epithelium, which lines the conducting airways, is central to the defense of the lungs against inhaled particulate matter and pathogens such as SARS-CoV-2, the virus that causes COVID-19. Recognition of pathogens results in the activation of an innate and intermediate immune response which involves the release of cytokines and chemokines by the airway epithelium. This response can inhibit further viral invasion and influence adaptive immunity. However, severe COVID-19 is characterized by a hyper-inflammatory response which can give rise to clinical presentations including lung injury and lead to acute respiratory distress syndrome, viral pneumonia, coagulopathy, and multi-system organ failure. In response to SARS-CoV-2 infection, the airway epithelium can mount a maladaptive immune response which can delay viral clearance, perpetuate excessive inflammation, and contribute to the pathogenesis of severe COVID-19. In this article, we will review the barrier and immune functions of the airway epithelium, how SARS-CoV-2 can interact with the epithelium, and epithelial-derived cytokines and chemokines and their roles in COVID-19 and as biomarkers. Finally, we will discuss these immune mediators and their potential as therapeutic targets in COVID-19.

Guidance for Administering Biologics for Severe Asthma and Allergic Conditions.

Asthma is a common respiratory disorder in Canada for which biologics may be prescribed for poorly controlled illness. Treatment with biologics, however, is sometimes inappropriately discontinued due to misconceptions regarding their potential immunologic effects, and concerns surrounding their continued use in severe asthma during the COVID-19 pandemic continue to propagate. Biologics can still be administered in a majority of health and treatment conditions. With regard to cardiac-related issues such as hypertension or cardiovascular disease (CVD), there is no solid evidence that suggests biologics should be withheld, as the benefits of treatment outweigh the risks. Asthmatic patients on biologic treatment should also continue treatment if they have, or are currently being treated for, a respiratory infection, including COVID-19. Evidence also indicates the importance of maintaining asthma control to reduce the risk of severe COVID-19 infection. Biologic treatment can be administered in severe asthmatic patients with bronchiectasis, though further evidence is needed to better understand the benefits. Biologic treatment should be continued postsurgery to reduce postoperative respiratory complications, as well as throughout the course of pregnancy. Regarding concerns over vaccine administration, nearly all vaccines can be given without interruption of biologic treatment in patients with severe asthma or allergic conditions. Appropriate screening for respiratory illnesses, such as COVID-19, continues to be warranted in clinical practices to reduce the risk of transmission. As recommendations from public health and regulatory agencies have been lacking, this guidance document addresses the administration of biologics in different health circumstances and respiratory illness screening during the COVID-19 pandemic.

Hedgehog Signaling as a Therapeutic Target for Airway Remodeling and Inflammation in Allergic Asthma.

Genome-wide association studies (GWAS) have shown that variants of patched homolog 1 (PTCH1) are associated with lung function abnormalities in the general population. It has also been shown that sonic hedgehog (SHH), an important ligand for PTCH1, is upregulated in the airway epithelium of patients with asthma and is suggested to be involved in airway remodeling. The contribution of hedgehog signaling to airway remodeling and inflammation in asthma is poorly described. To determine the biological role of hedgehog signaling-associated genes in asthma, gene silencing, over-expression, and pharmacologic inhibition studies were conducted after stimulating human airway epithelial cells or not with transforming growth factor ß1 (TGFß1), an important fibrotic mediator in asthmatic airway remodeling that also interacts with SHH pathway. TGFß1 increased hedgehog-signaling-related gene expression including SHH, GLI1 and GLI2. Knockdown of PTCH1 or SMO with siRNA, or use of hedgehog signaling inhibitors, consistently attenuated COL1A1 expression induced by TGFß1 stimulation. In contrast, Ptch1 over-expression augmented TGFß1-induced an increase in COL1A1 and MMP2 gene expression. We also showed an increase in hedgehog-signaling-related gene expression in primary airway epithelial cells from controls and asthmatics at different stages of cellular differentiation. GANT61, an inhibitor of GLI1/2, attenuated TGFß1-induced increase in COL1A1 protein expression in primary airway epithelial cells differentiated in air-liquid interface. Finally, to model airway tissue remodeling in vivo, C57BL/6 wildtype (WT) and Ptch1+/- mice were intranasally challenged with house dust mite (HDM) or phosphate-buffered saline (PBS) control. Ptch1+/- mice showed reduced sub-epithelial collagen expression and serum inflammatory proteins compared to WT mice in response to HDM challenge. In conclusion, TGFß1-induced airway remodeling is partially mediated through the hedgehog signaling pathway via the PTCH1-SMO-GLI axis. The Hedgehog signaling pathway is a promising new potential therapeutic target to alleviate airway tissue remodeling in patients with allergic airways disease.