Feasibility, Repeatability, and Correlation to Lung Function of Phase-Resolved Functional Lung (PREFUL) MRI-derived Pulmonary Artery Pulse Wave Velocity Measurements.

BACKGROUND: Pulse wave velocity (PWV) in the pulmonary arteries (PA) is a marker of vascular stiffening. Currently, only phase-contrast (PC) MRI-based options exist to measure PA-PWV. PURPOSE: To test feasibility, repeatability, and correlation to clinical data of Phase-Resolved Functional Lung (PREFUL) MRI-based calculation of PA-PWV. STUDY TYPE: Retrospective. SUBJECTS: 79 (26 female) healthy subjects (age range 19-78), 58 (24 female) patients with chronic obstructive pulmonary disease (COPD, age range 40-77), 60 (33 female) patients with suspected pulmonary hypertension (PH, age range 28-85). SEQUENCE: 2D spoiled gradient echo, 1.5T. ASSESSMENT: PA-PWV was measured from PREFUL-derived cardiac cycles based on the determination of temporal and spatial distance between lung vasculature voxels using a simplified (sPWV) method and a more comprehensive (cPWV) method including more elaborate distance calculation. For 135 individuals, PC MRI-based PWV (PWV-QA) was measured. STATISTICAL TESTS: Intraclass-correlation-coefficient (ICC) and coefficient of variation (CoV) were used to test repeatability. Nonparametric tests were used to compare cohorts. Correlation of sPWV/cPWV, PWV-QA, forced expiratory volume in 1 sec (FEV1 ) %predicted, residual volume (RV) %predicted, age, and right heart catheterization (RHC) data were tested. Significance level α = 0.05 was used. RESULTS: sPWV and cPWV showed no significant differences between repeated measurements (P-range 0.10-0.92). CoV was generally lower than 15%. COPD and PH patients had significantly higher sPWV and cPWV than healthy subjects. Significant correlation was found between sPWV or cPWV and FEV1 %pred. (R = -0.36 and R = -0.44), but not with RHC (P-range -0.11 - 0.91) or age (P-range 0.23-0.89). Correlation to RV%pred. was significant for cPWV (R = 0.42) but not for sPWV (R = 0.34, P = 0.055). For all cohorts, sPWV and cPWV were significantly correlated with PWV-QA (R = -0.41 and R = 0.48). DATA CONCLUSION: PREFUL-derived PWV is feasible and repeatable. PWV is increased in COPD and PH patients and correlates to airway obstruction and hyperinflation. LEVEL OF EVIDENCE: 3 TECHNICAL EFFICACY: Stage 2.

Alveolar membrane and capillary function in COVID-19 convalescents: insights from chest MRI.

OBJECTIVES: To investigate potential presence and resolution of longer-term pulmonary diffusion limitation and microvascular perfusion impairment in COVID-19 convalescents. MATERIALS AND METHODS: This prospective, longitudinal study was carried out between May 2020 and April 2023. COVID-19 convalescents repeatedly and age/sex-matched healthy controls once underwent MRI including hyperpolarized 129Xe MRI. Blood samples were obtained in COVID-19 convalescents for immunophenotyping. Ratios of 129Xe in red blood cells (RBC), tissue/plasma (TP), and gas phase (GP) as well as lung surface-volume ratio were quantified and correlations with CD4+/CD8+ T cell frequencies were assessed using Pearson's correlation coefficient. Signed-rank tests were used for longitudinal and U tests for group comparisons. RESULTS: Thirty-five participants were recruited. Twenty-three COVID-19 convalescents (age 52.1 ± 19.4 years, 13 men) underwent baseline MRI 12.6 ± 4.2 weeks after symptom onset. Fourteen COVID-19 convalescents underwent follow-up MRI and 12 were included for longitudinal comparison (baseline MRI at 11.5 ± 2.7 weeks and follow-up 38.0 ± 5.5 weeks). Twelve matched controls were included for comparison. In COVID-19 convalescents, RBC-TP was increased at follow-up (p = 0.04). Baseline RBC-TP was lower in patients treated on intensive care unit (p = 0.03) and in patients with severe/critical disease (p = 0.006). RBC-TP correlated with CD4+/CD8+ T cell frequencies (R = 0.61/ - 0.60) at baseline. RBC-TP was not significantly different compared to matched controls at follow-up (p = 0.25). CONCLUSION: Impaired microvascular pulmonary perfusion and alveolar membrane function persisted 12 weeks after symptom onset and resolved within 38 weeks after COVID-19 symptom onset. CLINICAL RELEVANCE STATEMENT: 129Xe MRI shows improvement of microvascular pulmonary perfusion and alveolar membrane function between 11.5 ± 2.7 weeks and 38.0 ± 5.5 weeks after symptom onset in patients after COVID-19, returning to normal in subjects without significant prior disease. KEY POINTS: • The study aims to investigate long-term effects of COVID-19 on lung function, in particular gas uptake efficiency, and on the cardiovascular system. • In COVID-19 convalescents, the ratio of 129Xe in red blood cells/tissue plasma increased longitudinally (p = 0.04), but was not different from matched controls at follow-up (p = 0.25). • Microvascular pulmonary perfusion and alveolar membrane function are impaired 11.5 weeks after symptom onset in patients after COVID-19, returning to normal in subjects without significant prior disease at 38.0 weeks.

Inhaled anti-TSLP antibody fragment, ecleralimab, blocks responses to allergen in mild asthma.

BACKGROUND: Thymic stromal lymphopoietin (TSLP) is a key upstream regulator driving allergic inflammatory responses. We evaluated the efficacy and safety of ecleralimab, a potent inhaled neutralising antibody fragment against human TSLP, using allergen inhalation challenge (AIC) in subjects with mild atopic asthma. METHODS: This was a 12-week, randomised, double-blind, placebo-controlled, parallel-design, multicentre allergen bronchoprovocation study conducted at 10 centres across Canada and Germany. Subjects aged 18-60 years with stable mild atopic asthma were randomised (1:1) to receive 4 mg once-daily inhaled ecleralimab or placebo. Primary end-points were the allergen-induced change in forced expiratory volume in 1 s (FEV1) during the late asthmatic response (LAR) measured by area under the curve (AUC3-7h) and maximum percentage decrease (LAR%) on day 84, and the safety of ecleralimab. Allergen-induced early asthmatic response (EAR), sputum eosinophils and fractional exhaled nitric oxide (F ENO) were secondary and exploratory end-points. RESULTS: 28 subjects were randomised to ecleralimab (n=15) or placebo (n=13). On day 84, ecleralimab significantly attenuated LAR AUC3-7h by 64% (p=0.008), LAR% by 48% (p=0.029), and allergen-induced sputum eosinophils by 64% at 7 h (p=0.011) and by 52% at 24 h (p=0.047) post-challenge. Ecleralimab also numerically reduced EAR AUC0-2h (p=0.097) and EAR% (p=0.105). F ENO levels were significantly reduced from baseline throughout the study (p<0.05), except at 24 h post-allergen (day 43 and day 85). Overall, ecleralimab was safe and well tolerated. CONCLUSION: Ecleralimab significantly attenuated allergen-induced bronchoconstriction and airway inflammation, and was safe in subjects with mild atopic asthma.

Absolute thermometry using hyperpolarized 129 Xe free-induction decay and spin-echo chemical-shift imaging in rats.

PURPOSE: To implement and test variants of chemical shift imaging (CSI) acquiring both free induction decays (FIDs) showing all dissolved-phase compartments and spin echoes for specifically assessing 129 $$ {}^{129} $$ Xe in lipids in order to perform precise lipid-dissolved 129 $$ {}^{129} $$ Xe MR thermometry in a rat model of general hypothermia. METHODS: Imaging was performed at 2.89 T. T 2 $$ {T}_2 $$ of 129 $$ {}^{129} $$ Xe in lipids was determined in one rat by fitting exponentials to decaying signals of global spin-echo spectra. Four rats (conventional CSI) and six rats (turbo spectroscopic imaging) were scanned at three time points with core body temperature 37/34/37 ∘ $$ {}^{\circ } $$ C. Lorentzian functions were fit to spectra from regions of interest to determine the water-referenced chemical shift of lipid-dissolved 129 $$ {}^{129} $$ Xe in the abdomen. Absolute 129 $$ {}^{129} $$ Xe-derived temperature was compared to values from a rectal probe. RESULTS: Global T 2 $$ {T}_2 $$ of 129 $$ {}^{129} $$ Xe in lipids was determined as 251 . 3 ms ± 81 . 4 ms $$ 251.3\;\mathrm{ms}\pm 81.4\;\mathrm{ms} $$ . Friedman tests showed significant changes of chemical shift with time for both sequence variants and both FID and spin-echo acquisitions. Mean and SD of 129 $$ {}^{129} $$ Xe and rectal probe temperature differences were found to be - 0 . 1 5 ∘ C ± 0 . 9 3 ∘ C $$ -0.1{5}^{\circ}\mathrm{C}\pm 0.9{3}^{\circ}\mathrm{C} $$ (FID) and - 0 . 3 8 ∘ C ± 0 . 6 4 ∘ C $$ -0.3{8}^{\circ}\mathrm{C}\pm 0.6{4}^{\circ}\mathrm{C} $$ (spin echo) for conventional CSI as well as 0 . 0 3 ∘ C ± 0 . 7 7 ∘ C $$ 0.0{3}^{\circ}\mathrm{C}\pm 0.7{7}^{\circ}\mathrm{C} $$ (FID) and - 0 . 0 6 ∘ C ± 0 . 7 6 ∘ C $$ -0.0{6}^{\circ}\mathrm{C}\pm 0.7{6}^{\circ}\mathrm{C} $$ (spin echo) for turbo spectroscopic imaging. CONCLUSION: 129 $$ {}^{129} $$ Xe MRI using conventional CSI and turbo spectroscopic imaging of lipid-dissolved 129 $$ {}^{129} $$ Xe enables precise temperature measurements in the rat's abdomen using both FID and spin-echo acquisitions with acquisition of spin echoes enabling most precise temperature measurements.

Efficacy and Safety of a Drug-Free, Barrier-Forming Nasal Spray for Allergic Rhinitis: Randomized, Open-Label, Crossover Noninferiority Trial.

INTRODUCTION: Symptoms of allergic rhinitis can be reduced by nonpharmacological nasal sprays that create a barrier between allergens and the nasal mucosa. A new nasal spray (AM-301) containing the clay mineral bentonite was tested for its ability to reduce symptoms of grass pollen. METHODS: This open-label, crossover, noninferiority trial compared the efficacy and safety of AM-301 to that of hydroxypropyl methylcellulose (HPMC; Nasaleze® Allergy Blocker), an established barrier method. Adults with seasonal allergic rhinitis were exposed to Dactylis glomerata pollen, in a controlled setting, the Fraunhofer allergen challenge chamber, first without protection and then protected by HPMC or AM-301 (7 days apart). Efficacy was assessed from total nasal symptom score (TNSS), nasal secretion weight, and subjective rating. The primary endpoint was the difference, between AM-301 and HPMC, in least square mean change in TNSS over a 4-h exposure to allergen. RESULTS: The study enrolled 36 persons, and 35 completed all study visits. The mean TNSS was 5.91 (SD = 1.45) during unprotected exposure, 5.20 (SD = 1.70) during protection with HPMC, and 4.82 (SD = 1.74) during protection with AM-301. The difference in least square means between the two treatments was -0.39 (95% CI: -0.89 to 0.10), establishing the noninferiority of AM-301. No difference in mean weight of nasal secretions was observed between the treatments. Efficacy was rated as good or very good for AM-301 by 31% and for HPMC by 14% of subjects. Sixteen subjects reported adverse events with a relationship to AM-301 or HPMC; most adverse events were mild, and none was serious. DISCUSSION/CONCLUSION: AM-301 demonstrated noninferiority toward HPMC in the primary endpoint and was perceived better in subjective secondary endpoints. Both barrier-forming products had a persisting protective effect over 4 h and were safe.

Sodium Chloride versus Lactose as a Carrier for House Dust Mite Allergen in Allergen Chamber Studies: A Clinical Study to Assess Noninferiority.

INTRODUCTION: In the Fraunhofer allergen challenge chamber (ACC), a standardized, universal, good manufacturing practice-conforming technology using a spray dried solution of lactose (L) and allergen extract has been established. In this study, we investigated the noninferiority of hypertonic sodium chloride (S) versus L as a carrier for house dust mite (HDM) allergen to simplify manufacturing, reduce costs, and allow for wider use. METHODS: Using a participant-blinded, sham exposure-controlled, single-arm, sequential intervention study, we challenged adults with HDM allergic rhinitis five times in the ACC. Participants were first exposed to S, L, and clean air (block 1), followed by S + HDM and L + HDM (block 2). Primary endpoints were mean total nasal symptom score (TNSS) and mean nasal secretion weight. RESULTS: 19 participants were enrolled in the study (10 females; mean age 32 years [22-49], 4 with mild allergic asthma). The safety profile of S + HDM and L + HDM was similar; eight participants experienced mild procedure-related adverse events including tiredness, cough, and dyspnea. Due to dropouts, 13 participants completed the study and were evaluated. Mean TNSS and nasal secretion were as follows: S 0.98, 0.28 g; L 1.1, 0.20 g; clean air 1.1, 0.23 g; S + HDM 5.7, 4.8 g; L + HDM 5.1, 5.1 g. Separate block 1/block 2 MANOVAs with TNSS and nasal secretion as dependent variables revealed no significant differences between the carriers, neither alone and compared with clean air (p = 0.2059, Wilk's λ = 0.78) nor combined with HDM (p = 0.3474, Wilk's λ = 0.89). Noninferiority of S was established using a meta-analysis-based minimal clinical important difference of -0.55: mean TNSS difference between S + HDM and L + HDM was 0.62 (90% CI: -0.51 to 1.74). CONCLUSION: S as an HDM carrier was safe and well tolerated. It was noninferior to L which makes it an adequate and easy-to-use carrier substitute.

The effect of bradykinin 1 receptor antagonist BI 1026706 on pulmonary inflammation after segmental lipopolysaccharide challenge in healthy smokers.

BACKGROUND: Bradykinin 1 receptor (B1R) signalling pathways may be involved in the inflammatory pathophysiology of chronic obstructive pulmonary disease (COPD). B1R signalling is induced by inflammatory stimuli or tissue injury and leads to activation and increased migration of pro-inflammatory cells. Lipopolysaccharide (LPS) lung challenge in man is an experimental method of exploring inflammation in the lung whereby interference in these pathways can help to assess pharmacologic interventions in COPD. BI 1026706, a potent B1R antagonist, was hypothesized to reduce the inflammatory activity after segmental lipopolysaccharide (LPS) challenge in humans due to decreased pulmonary cell influx. METHODS: In a monocentric, randomized, double-blind, placebo-controlled, parallel-group, phase I trial, 57 healthy, smoking subjects were treated for 28 days with either oral BI 1026706 100 mg bid or placebo. At day 21, turbo-inversion recovery magnitude magnetic resonance imaging (TIRM MRI) was performed. On the last day of treatment, pre-challenge bronchoalveolar lavage fluid (BAL) and biopsies were sampled, followed by segmental LPS challenge (40 endotoxin units/kg body weight) and saline control instillation in different lung lobes. Twenty-four hours later, TIRM MRI was performed, then BAL and biopsies were collected from the challenged segments. In BAL samples, cells were differentiated for neutrophil numbers as the primary endpoint. Other endpoints included assessment of safety, biomarkers in BAL (e.g. interleukin-8 [IL-8], albumin and total protein), B1R expression in lung biopsies and TIRM score by MRI as a measure for the extent of pulmonary oedema. RESULTS: After LPS, but not after saline, high numbers of inflammatory cells, predominantly neutrophils were observed in the airways. IL-8, albumin and total protein were also increased in BAL samples after LPS challenge as compared with saline control. There were no significant differences in cells or other biomarkers from BAL in volunteers treated with BI 1026706 compared with those treated with placebo. Unexpectedly, neutrophil numbers in BAL were 30% higher and MRI-derived extent of oedema was significantly higher with BI 1026706 treatment compared with placebo, 24 h after LPS challenge. Adverse events were mainly mild to moderate and not different between treatment groups. CONCLUSIONS: Treatment with BI 1026706 for four weeks was safe and well-tolerated in healthy smoking subjects. BI 1026706 100 mg bid did not provide evidence for anti-inflammatory effects in the human bronchial LPS challenge model. TRIAL REGISTRATION: The study was registered on January 14, 2016 at ClinicalTrials.gov (NCT02657408).

Ultrastructural analysis of the intracellular surfactant in lungs of healthy and ovalbumin sensitized and challenged Brown Norway rats.

Introduction: In human and experimentally induced asthma, a dysfunction of the intra-alveolar-surface active agent (surfactant) has been demonstrated. Type II alveolar epithelial cells (AEII) synthesize, secrete and recycle surfactant. Prior to secretion, intracellular surfactant is stored in specific secretory organelles of AEII. The lamellar bodies (Lb) represent its ultrastructural correlate. The aim of this study was to investigate whether disturbances of the intra-alveolar surfactant are accompanied by alterations in the intracellular surfactant.Material and Methods: Brown-Norway rats were sensitized twice with ovalbumin (OVA) and heat killed Bordetella pertussis bacilli. During airway challenge, an aerosol of 5% ovalbumin/saline solution (0.25 l/min) was nebulized. 24 h after airway challenge, lungs were fixed by vascular perfusion. AEII and their Lb were characterized stereologically by light and electron microscopy.Results: In both groups, AEII were structurally intact. The number of AEII per lung and their number-weighted mean volume did not differ (controls: 49 × 106, 393 µm3; asthmatics: 44 × 106, 390 µm3). A mean of 90 Lb in AEII of asthmatics and of 93 Lb in AEII of controls were evaluated. The Lb mean total volume was 59 µm in asthmatics and 68 µm in controls. Values of both parameters did not reach significance. Also, the size distribution and mean volume of Lb was not influenced by asthma induction, because the volume weighted mean volume of Lb (2.18 µm in asthmatics compared to 1.87 µm in controls) and the numerical weighted mean volume (0.96 µm in asthmatics and 0.75 µm in controls) were comparable in both groups.Conclusion: The obtained results suggest that asthma-induced surfactant dysfunction is not related to disturbances in the intracellular surfactant´s ultrastructural correlates.

Exhaled breath particles as a novel tool to study lipid composition of epithelial lining fluid from the distal lung.

BACKGROUND: Surfactant phospholipid (PL) composition plays an important role in lung diseases. We compared the PL composition of non-invasively collected exhaled breath particles (PEx) with bronchoalveolar lavage (BAL) and induced sputum (ISP) at baseline and following endotoxin (LPS) challenges. METHODS: PEx and BAL were collected from ten healthy nonsmoking participants before and after segmental LPS challenge. Four weeks later, PEx and ISP were sampled in the week before and after a whole lung LPS inhalation challenge. PL composition was analysed using mass spectrometry. RESULTS: The overall PL composition of BAL, ISP and PEx was similar, with PC(32:0) and PC(34:1) representing the largest fractions in all three sample types (baseline PC(32:0) geometric mean mol%: 52.1, 56.9, and 51.7, PC(34:1) mol%: 11.7, 11.9 and 11.4, respectively). Despite this similarity, PEx PL composition was more closely related to BAL than to ISP. For most lipids comparable inter-individual differences in BAL, ISP, and PEx were found. PL composition of PEx was repeatable. The most pronounced increase following segmental LPS challenge was detected for SM(d34:1) in BAL (0.24 to 0.52 mol%) and following inhalation LPS challenge in ISP (0.45 to 0.68 mol%). An increase of SM(d34:1) following segmental LPS challenge was also detectable in PEx (0.099 to 0.103 mol%). The inhalation challenge did not change PL composition of PEx. CONCLUSION: Our data supports the peripheral origin of PEx. The lack of PL changes in PEx after inhalation challenge might to be due to the overall weaker response of inhaled LPS which primarily affects the larger airways. Compared with BAL, which always contains lining fluid from both peripheral lung and central airways, PEx analysis might add value as a selective and non-invasive method to investigate peripheral airway PL composition. TRIAL REGISTRATION: NCT03044327, first posted 07/02/2017.

Examining lung microstructure using 19 F MR diffusion imaging in COPD patients.

PURPOSE: To examine the time-dependent diffusion of fluorinated (19 F) gas in human lungs for determination of surface-to-volume ratio in comparison to results from hyperpolarized 129 Xe and lung function testing in healthy volunteers and patients with chronic obstructive pulmonary disease. METHODS: Diffusion of fluorinated gas in the short-time regime was measured using multiple gradient-echo sequences with a single pair of trapezoidal gradient pulses. Pulmonary surface-to-volume ratio was calculated using a first-order approximation of the time-dependent diffusion in a study with 20 healthy volunteers and 22 patients with chronic obstructive pulmonary disease. The repeatability after 7 days as well as the correlation with hyperpolarized 129 Xe diffusion MRI and lung function testing was analyzed. RESULTS: Using 19 F diffusion MRI, the median surface-to-volume ratio is significantly decreased in chronic obstructive pulmonary disease patients (S/V = 126 cm-1 [87-144 cm-1 ]) compared with healthy volunteers (S/V = 164 cm-1 [160-84 cm-1 ], p < 0.0001). No significant difference was found between measurements within 7 days for healthy (p = 0.88, median coefficient of variation = 4.3%) and diseased subjects (p = 0.58, median coefficient of variation= 6.7%). Linear correlations were found with S/V from 129 Xe diffusion MRI (r = 0.85, p = 0.001) and the forced expiratory volume in 1 second (r = 0.68, p < 0.0001). CONCLUSION: Examination of lung microstructure using time-dependent diffusion measurement of inhaled 19 F is feasible, repeatable, and correlates with established measurements.

Basophil activation test: Assay precision and BI 1002494 SYK inhibition in healthy and mild asthmatics.

BACKGROUND: Application of basophil activation test (BAT) in clinical trials requires assay validity. Whether assay variability differs between healthy and asthmatic subjects is mostly unknown. This study compares basophil stimulation using blood from healthy and asthmatic subjects with or without inhibition of spleen tyrosine kinase (SYK). METHODS: Whole blood of healthy and mild asthmatic subjects was stimulated with anti-dinitrophenyl (DNP) IgE/DNP bovine serum albumin and anti-IgE. Basophil activation was detected by CD63 and CD203c expression. CD63 expression levels were compared with serum IgE levels. Three operators repeated experiments with three subjects each from both groups at 3 days to observe assay precision. The effect of the SYK inhibitor BI 1002494 was assessed in BAT for both healthy and asthmatic subjects. RESULTS: BAT was reproducible in both groups. Acceptance criteria of <25% CV were mostly fulfilled. Stimulation with anti-DNP (p < 0.001, r = -0.80) but not anti-IgE (p = 0.74, r = 0.05) was related to serum IgE with levels > 200 IU/ml limiting anti-DNP stimulation. BI 1002494 IC50 values were 497 nM and 1080 nM in healthy and 287 nM and 683 nM in asthmatics for anti-DNP and anti-IgE stimulation, respectively. CONCLUSION: BAT, performed with blood from healthy or asthmatic subjects, is a robust test for the measurement of a physiological response in clinical trials. Blood from asthmatic donors with serum IgE > 200 IU/ml is less feasible when using anti-DNP stimulation. SYK inhibition was not affected by disease status.

Quantitative analysis of endotoxin-induced inflammation in human lung cells by Chipcytometry.

Chipcytometry is a tool that uses iterative staining cycles with multiple antibodies for a detailed characterization of cells. Cell recognition is based on morphological features. Cells fixed on microfluidic chips can be stored and shipped enabling a centralized analysis, which is important for assessments in multi-center clinical trials. The method was initially implemented for the analysis of cells from peripheral blood. We adapted it to more heterogeneous human lung cells from bronchoalveolar lavage (BAL) fluid and induced sputum (IS). We aimed to assess the performance of Chipcytometry to detect and quantify the endotoxin induced inflammatory response in healthy subjects. BAL and IS samples of 10 healthy subjects were collected prior to and following segmental and inhaled endotoxin challenge. Samples were analyzed by Chipcytometry and were compared with flow cytometry, and differential cell count (DCC). Chipcytometry clearly detected the endotoxin induced inflammatory response which was characterized by a massive increase of neutrophils (BAL: 2.5% to 54.7%; IS: 40.5% to 71.1%) and monocytes (BAL: 7.7% to 24.7%; IS: 8.0% to 14.5%). While some differences between detection methods exist, the overall results were comparable. The ability of Chipcytometry to verify fluorescent signals with morphological features improved the precision of rare cell analysis such as of induced sputum lymphocytes. In conclusion, Chipcytometry enables the quantitative analysis of cells from BAL fluid and IS. Advantages over DCC and flow cytometry include the storage of cells on chips, the ability for re-analysis and the mapping of surface marker binding to morphological information. It therefore appears to be a promising method for use in clinical respiratory drug development.

Prostaglandin D2 metabolites activate asthmatic patient-derived type 2 innate lymphoid cells and eosinophils via the DP2 receptor.

BACKGROUND: Prostaglandin D2 (PGD2) signaling via prostaglandin D2 receptor 2 (DP2) contributes to atopic and non-atopic asthma. Inhibiting DP2 has shown therapeutic benefit in certain subsets of asthma patients, improving eosinophilic airway inflammation. PGD2 metabolites prolong the inflammatory response in asthmatic patients via DP2 signaling. The role of PGD2 metabolites on eosinophil and ILC2 activity is not fully understood. METHODS: Eosinophils and ILC2s were isolated from peripheral blood of atopic asthmatic patients. Eosinophil shape change, ILC2 migration and IL-5/IL-13 cytokine secretion were measured after stimulation with seven PGD2 metabolites in presence or absence of the selective DP2 antagonist fevipiprant. RESULTS: Selected metabolites induced eosinophil shape change with similar nanomolar potencies except for 9α,11ß-PGF2. Maximal values in forward scatter of eosinophils were comparable between metabolites. ILC2s migrated dose-dependently in the presence of selected metabolites except for 9α,11ß-PGF2 with EC50 values ranging from 17.4 to 91.7 nM. Compared to PGD2, the absolute cell migration was enhanced in the presence of Δ12-PGD2, 15-deoxy-Δ12,14-PGD2, PGJ2, Δ12-PGJ2 and 15-deoxy-Δ12,14-PGJ2. ILC2 cytokine production was dose dependent as well but with an average sixfold reduced potency compared to cell migration (IL-5 range 108.1 to 526.9 nM, IL-13 range: 125.2 to 788.3 nM). Compared to PGD2, the absolute cytokine secretion was reduced in the presence of most metabolites. Fevipiprant dose-dependently inhibited eosinophil shape change, ILC2 migration and ILC2 cytokine secretion with (sub)-nanomolar potencies. CONCLUSION: Prostaglandin D2 metabolites initiate ILC2 migration and IL-5 and IL-13 cytokine secretion in a DP2 dependent manner. Our data indicate that metabolites may be important for in vivo eosinophil activation and ILC2 migration and to a lesser extent for ILC2 cytokine secretion.

Technical standards in allergen exposure chambers worldwide - an EAACI Task Force Report.

Allergen exposure chambers (AECs) can be used for controlled exposure to allergenic and non-allergenic airborne particles in an enclosed environment, in order to (i) characterize the pathological features of respiratory diseases and (ii) contribute to and accelerate the clinical development of pharmacological treatments and allergen immunotherapy for allergic disease of the respiratory tract (such as allergic rhinitis, allergic rhinoconjunctivitis, and allergic asthma). In the guidelines of the European Medicines Agency for the clinical development of products for allergen immunotherapy (AIT), the role of AECs in determining primary endpoints in dose-finding Phase II trials is emphasized. Although methodologically insulated from the variability of natural pollen exposure, chamber models remain confined to supporting secondary, rather than primary, endpoints in Phase III registration trials. The need for further validation in comparison with field exposure is clearly mandated. On this basis, the European Academy of Allergy and Clinical Immunology (EAACI) initiated a Task Force in 2015 charged to gain a better understanding of how AECs can generate knowledge about respiratory allergies and can contribute to the clinical development of treatments. Researchers working with AECs worldwide were asked to provide technical information in eight sections: (i) dimensions and structure of the AEC, (ii) AEC staff, (iii) airflow, air processing, and operating conditions, (iv) particle dispersal, (v) pollen/particle counting, (vi) safety and non-contamination measures, (vii) procedures for symptom assessments, (viii) tested allergens/substances and validation procedures. On this basis, a minimal set of technical requirements for AECs applied to the field of allergology is proposed.

Repeatability of Phase-Resolved Functional Lung (PREFUL)-MRI Ventilation and Perfusion Parameters in Healthy Subjects and COPD Patients.

BACKGROUND: Free-breathing phase-resolved functional lung (PREFUL)-MRI may be useful for treatment monitoring in chronic obstructive pulmonary disease (COPD) patients with dyspnea. PREFUL test-retest reliability is essential for clinical application. PURPOSE: To measure the repeatability of PREFUL-MRI ventilation (V) and perfusion (Q) parameters. STUDY TYPE: Retrospective and prospective. POPULATION: A total of 28 COPD patients and 57 healthy subjects. FIELD STRENGTH/SEQUENCE: 1.5T MRI/2D spoiled gradient echo imaging. ASSESSMENT: V and Q lung parameter maps based on three coronal slices were obtained at baseline and after 14 days (COPD patients) or after a short pause outside the scanner (healthy subjects). Regional ventilation (RVent) and imaging flow volume loops by cross-correlation (ccVent) were quantified. Q was normalized to the signal of the main pulmonary artery (QN ) and quantified (QQuant ). Pulmonary pulse wave transit time (pPTT), voxel-by-voxel (regional), and whole lung (global) ventilation defect percentage based on RVent (VDPRVent ) and ccVent (VDPccVent ), perfusion defect percentage (QDP), and ventilation/perfusion match based on RVent (VQMRVent ) and ccVent (VQMccVent ) were calculated. STATISTICAL TESTS: Regional V and Q were analyzed globally for each subject. Each parameter's median of scans 1 and 2 were assessed by Wilcoxon sign rank test. A parameter's repeatability was analyzed by Bland-Altman analyses, coefficients of variation, intraclass correlation coefficients (ICC), and power calculations. The regional voxel repeatability was examined by calculating the Sørensen-Dice coefficient. RESULTS: There was no bias and no significant differences between the first and second MRI for any parameters (P > 0.05). Coefficient of variation ranged from 2.26% (ccVent) to 19.31% (QDP), ICC from 0.93 (QDP) to 0.60 (pPTT), the smallest detectable difference was 0.002 ccVent. Regional comparison showed the highest overlap (84%) in VDPRVent in healthy voxels and the lowest (53%) in VDPccVent defect voxels. DATA CONCLUSION: V and Q PREFUL-MRI parameters were repeatable over two scan sessions in both healthy controls and COPD patients. LEVEL OF EVIDENCE: 2 TECHNICAL EFFICACY STAGE: 2.

Flow Volume Loop and Regional Ventilation Assessment Using Phase-Resolved Functional Lung (PREFUL) MRI: Comparison With 129 Xenon Ventilation MRI and Lung Function Testing.

BACKGROUND: Regional flow volume loop ventilation-weighted noncontrast-enhanced proton lung MRI in free breathing has emerged as a novel technique for assessment of regional lung ventilation, but has yet not been validated with 129 Xenon MRI (129 Xe-MRI), a direct visualization of ventilation in healthy volunteers, cystic fibrosis (CF), and chronic obstructive pulmonary disease (COPD) patients. PURPOSE: To compare regional ventilation and regional flow volume loops measured by noncontrast-enhanced ventilation-weighted phase-resolved functional lung MRI (PREFUL-MRI) with 129 Xe-MRI ventilation imaging and with lung function test parameters. STUDY TYPE: Retrospective study. POPULATION: Twenty patients with COPD, eight patients with CF, and six healthy volunteers. FIELD STRENGTH/SEQUENCE: PREFUL and 129 Xe-MRI gradient echo sequences were acquired at 1.5T. ASSESSMENT: Coronal slices of PREFUL-MRI (free breathing) and 129 Xe-MRI (single breath-hold) were acquired on the same day, matched by their ventrodorsal position and coregistered for evaluation. Ventilation defect percentage (VDP) was calculated based on regional ventilation (RV), regional flow volume loops (RFVL), or 129 Xe-MRI with two different threshold methods. A combined VDP was calculated for RV and RFVL. Additionally, lung function testing was performed (such as the forced expiratory volume in 1 second [FEV1 ]) was used. STATISTICAL TESTS: The obtained parameters were compared using Wilcoxon tests, correlated using Spearman's correlation coefficient (r), and agreement between PREFUL and 129 Xe-MRI parameters was assessed using Bland-Altman analysis and Dice coefficients. RESULTS: VDP measured by PREFUL and 129 Xe were significantly correlated with both thresholding techniques (r = 0.62-0.69, P < 0.05 for all) and with lung function test parameters. Combined RV and RFVL PREFUL defect maps correlated with lung function testing (eg, with FEV1 r = -0.87 P < 0.05), and showed better regional agreement to 129 Xe-MRI ventilation defects (Dice coefficient defect 0.413) with significantly higher VDP values (10.2 ± 27.3, P = 0.04) than either PREFUL defect map alone. DATA CONCLUSION: Combined RV and RFVL PREFUL defect maps likely increase sensitivity to mild airway obstruction with increased VDP values compared to 129 Xe-MRI, and correlate strongly with lung function test parameters. LEVEL OF EVIDENCE: 3 TECHNICAL EFFICACY STAGE: 2.

Investigating short-time diffusion of hyperpolarized 129 Xe in lung air spaces and tissue: A feasibility study in chronic obstructive pulmonary disease patients.

PURPOSE: To investigate the diffusion of hyperpolarized 129 Xe in air spaces at short-time scales for determination of lung surface-to-gas-volume ratio in comparison to results from chemical shift saturation recovery, CT, and established clinical measures. METHODS: A pulse sequence for measurement of time-dependent diffusion of 129 Xe in air spaces at short diffusion times was developed. Gas uptake into lung tissue was measured in the same breathhold using chemical shift saturation recovery spectroscopy in the short-time regime. The potential to obtain the surface-to-gas-volume ratio using a first-order and second-order approximation of the short-time expansion of time-dependent diffusion according to Mitra et al11 and its diagnostic relevance were tested in a study with 9 chronic obstructive pulmonary diseases patients. RESULTS: Surface-to-gas-volume ratios obtained from time-dependent diffusion were correlated with results from chemical shift saturation recovery, r = 0.840, P = .005 (first-order fits), and r = 0.923, P < .001 (second-order fits), and from CT results for second-order fits, r = 0.729, P = .026. Group means ± SD were 75.0 ± 15.5 cm-1 (first-order fits) and 122.3 ± 32.8 cm-1 (second-order fits) for time-dependent diffusion, 125.9 ± 43.3 cm-1 for chemical shift saturation recovery, and 159.5 ± 50.9 cm-1 for CT. Surface-to-gas-volume ratios from time-dependent diffusion with first-order fits correlated significantly with carbon monoxide diffusing capacity as percent of prediction, r = 0.724, P = .028. CONCLUSION: Time-dependent diffusion measurements of 129 Xe at short-time scales down to ~1 ms are feasible in chronic obstructive pulmonary patients and provide clinically relevant information on lung microstructure.

Letter to the editor: indacaterol/glycopyrronium/mometasone furoate compared with salmeterol/fluticasone propionate in patients with asthma: a randomized controlled cross-over study.

Indacaterol (IND; 150 µg), glycopyrronium (GLY; 50 µg) and mometasone furoate (MF; 160 µg [high-dose ICS] and 80 µg [medium-dose ICS]) have been formulated as a once-daily (o.d.) fixed-dose combination treatment delivered via the Breezhaler® device for the treatment of patients with asthma. In this randomized (n = 116), double-blind, double-dummy, active comparator-controlled, three-period cross-over study we evaluated the benefit of o.d. IND/GLY/MF versus twice daily (b.i.d.) salmeterol/fluticasone propionate combination (SFC; 50/500 µg; high-dose ICS) treatment (NCT03063086). Overall, 107 patients completed the study. The study met its primary objective by demonstrating superiority of o.d. IND/GLY/MF at medium and high-dose ICS over b.i.d. SFC (high-dose ICS) in peak FEV1 after 21 days of treatment (+ 172 mL with high-dose and + 159 mL with medium-dose IND/GLY/MF versus SFC, p < 0.0001 for each comparison). We also observed that a higher percentage of patients did not need rescue medicine with IND/GLY/MF (high-dose ICS, 58%; medium-dose ICS, 52%) compared with SFC (45%) during the last week of each treatment period. Study treatments were well-tolerated with no relevant differences in tolerability between both IND/GLY/MF doses and SFC. In conclusion, both doses of IND/GLY/MF provided superior lung function benefits compared with twice-daily, standard-of-care SFC at the highest approved dose. TRIAL REGISTRATION: ClinicalTrials.gov, (Identifier: NCT03063086), EudraCT start date: May 11, 2017; First patient first visit / study initiation date: May 31, 2017.

Blood eosinophil count and airway epithelial transcriptome relationships in COPD versus asthma.

BACKGROUND: Whether the clinical or pathophysiologic significance of the "treatable trait" high blood eosinophil count in COPD is the same as for asthma remains controversial. We sought to determine the relationship between the blood eosinophil count, clinical characteristics and gene expression from bronchial brushings in COPD and asthma. METHODS: Subjects were recruited into a COPD (emphysema versus airway disease [EvA]) or asthma cohort (Unbiased BIOmarkers in PREDiction of respiratory disease outcomes, U-BIOPRED). We determined gene expression using RNAseq in EvA (n = 283) and Affymetrix microarrays in U-BIOPRED (n = 85). We ran linear regression analysis of the bronchial brushings transcriptional signal versus blood eosinophil counts as well as differential expression using a blood eosinophil > 200 cells/µL as a cut-off. The false discovery rate was controlled at 1% (with continuous values) and 5% (with dichotomized values). RESULTS: There were no differences in age, gender, lung function, exercise capacity and quantitative computed tomography between eosinophilic versus noneosinophilic COPD cases. Total serum IgE was increased in eosinophilic asthma and COPD. In EvA, there were 12 genes with a statistically significant positive association with the linear blood eosinophil count, whereas in U-BIOPRED, 1197 genes showed significant associations (266 positive and 931 negative). The transcriptome showed little overlap between genes and pathways associated with blood eosinophil counts in asthma versus COPD. Only CST1 was common to eosinophilic asthma and COPD and was replicated in independent cohorts. CONCLUSION: Despite shared "treatable traits" between asthma and COPD, the molecular mechanisms underlying these clinical entities are predominately different.

The Effect of a Thixotropic Nasal Gel on Nasal Symptoms and Inflammatory Biomarkers in Seasonal Allergic Rhinitis.

BACKGROUND: Drug-free viscous nasal applications have been shown to reduce nasal symptoms in individuals with seasonal allergic rhinitis (SAR). Nascum®-Plus (NP), a commercially available thixotropic gel, has been designed to reduce dryness and soreness of the nasal mucosa and prevent the absorption of small particles. OBJECTIVES: The aim of this study was to assess the efficacy of single-dose NP in treating nasal symptoms and secretion during challenge in an allergen challenge chamber (ACC). Furthermore, the effect of this treatment on biomarkers and immune cells of the allergic cascade were measured. METHODS: This open-label, cross-over, sequence-randomized, monocentric trial randomized 18 adults with SAR and a positive skin prick test reaction to Dactylis glomerata pollen to receive NP or no treatment during two 4-h ACC sessions 3 weeks apart. On Day 1, 9 subjects were challenged for 4 h with treatment, the other 9 without treatment, and vice versa on Day 22. Nasal lavage fluid and nasal filter eluate samples were obtained pre, 2, and 18 h post challenge in the ACC. RESULTS: NP significantly reduced nasal symptoms, assessed by total nasal symptom score (p < 0.001), and minimized nasal secretion (p = 0.047), while no significant effect on biomarkers and immune cells in the nasal fluid was observed. The treatment was safe and well-tolerated. CONCLUSIONS: The physical barrier built by NP nasal gel can be safely applied in patients with allergic rhinitis. It reduces allergic nasal symptoms and secretion, but application of a single dose does not affect local inflammatory biomarkers.