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Background: The most recognizable phenotype of severe asthma comprises people who are blood eosinophil and FeNO-high, driven by type-2 (T2) cytokine biology which responds to targeted biological therapies. However, in many people with severe asthma, these T2 biomarkers are suppressed but poorly controlled asthma persists. The mechanisms driving asthma in the absence of T2 biology are poorly understood. Objectives: To explore airway pathology in T2 biomarker-high and -low severe asthma. Methods: T2 biomarker-high severe asthma (T2-high, n=17) was compared to biomarker-intermediate (T2-intermediate, n=21) and biomarker-low (T2-low, n=20) severe asthma, and healthy controls (n=28). Bronchoscopy samples were processed for immunohistochemistry, and sputum for cytokines, PGD2 and LTE4 measurements. Results: Tissue eosinophil, neutrophil and mast cell counts were similar across severe asthma phenotypes and not increased when compared to healthy controls. In contrast, the remodeling features of airway smooth muscle mass and MUC5AC expression were increased in all asthma groups compared to health, but similar across asthma subgroups. Submucosal glands were increased in T2-intermediate and T2-low asthma. In spite of similar tissue cellular inflammation, sputum IL-4, IL-5, and CCL26 were increased in T2-high versus T2-low asthma, and several further T2-associated cytokines, PGD2 and LTE4, were increased in T2-high and T2-intermediate asthma compared to healthy controls. Conclusions: Eosinophilic tissue inflammation within proximal airways is suppressed in T2 biomarker-high and T2-low severe asthma, but inflammatory and structural cell activation is present, with sputum T2-associated cytokines highest in T2 biomarker-high patients. Airway remodeling persists, and may be important for residual disease expression beyond eosinophilic exacerbations.

Previous metagenomic studies in asthma have been limited by inadequate sequencing depth for species-level bacterial identification and by heterogeneity in clinical phenotyping. We hypothesize that chronic bacterial airways infection is a key “treatable trait” whose prevalence, clinical phenotype and reliable biomarkers need definition. In this study, we have applied a method for Oxford Nanopore sequencing for the unbiased metagenomic characterization of severe asthma. We optimized methods to compare performance of Illumina MiSeq, Nanopore sequencing, and RT-qPCR on total sputum DNA extracts against culture/MALDI-TOF for analysis of induced sputum samples from highly phenotyped severe asthma during clinical stability. In participants with severe asthma (n = 23) H. influenzae was commonly cultured (n = 8) and identified as the dominant bacterial species by metagenomic sequencing using an optimized method for Illumina MiSeq and Oxford Nanopore. Alongside superior operational characteristics, Oxford Nanopore achieved near complete genome coverage of H. influenzae and demonstrated a high level of agreement with Illumina MiSeq data. Clinically significant infection was confirmed with validated H. influenzae plasmid-based quantitative PCR assay. H. influenzae positive patients were found to have sputum neutrophilia and lower FeNO. In conclusion, using an optimized method of direct sequencing of induced sputum samples, H. influenzae was identified as a clinically relevant pathogen in severe asthma and was identified reliably using metagenomic sequencing. Application of these protocols in ongoing analysis of large patient cohorts will allow full characterization of this clinical phenotype.

Chronic rhinosinusitis (CRS) refers to inflammation of the nasal sinuses and mucosa, with persistence of sinus inflammation and clinical manifestations beyond 12 weeks.1 CRS affects between 6 and 12% of adults and is a cause of reduced quality of life (QoL) and high healthcare costs.2 Management consisted of topical and systemic glucocorticoids, antibiotics and often repeated sinus surgery. Over the past 20 years, biologic therapies under investigation for asthma, with overlapping nasal polyposis, have shown significant improvement in sinonasal CRS symptoms and reduced nasal polyp swelling.3 This Cochrane Corner aims to summarize the effectiveness, safety and role of biological therapy in CRS to aid clinicians in the decision-making process.

Background The antibacterial, anti-inflammatory, and antiviral properties of azithromycin suggest therapeutic potential against COVID-19. Randomised data in mild-to-moderate disease are not available. We assessed whether azithromycin is effective in reducing hospital admission in patients with mild-to-moderate COVID-19. Methods This prospective, open-label, randomised superiority trial was done at 19 hospitals in the UK. We enrolled adults aged at least 18 years presenting to hospitals with clinically diagnosed, highly probable or confirmed COVID-19 infection, with fewer than 14 days of symptoms, who were considered suitable for initial ambulatory management. Patients were randomly assigned (1:1) to azithromycin (500 mg once daily orally for 14 days) plus standard care or to standard care alone. The primary outcome was death or hospital admission from any cause over the 28 days from randomisation. The primary and safety outcomes were assessed according to the intention-to-treat principle. This trial is registered at ClinicalTrials.gov (NCT04381962) and recruitment is closed. Findings 298 participants were enrolled from June 3, 2020, to Jan 29, 2021. Three participants withdrew consent and requested removal of all data, and three further participants withdrew consent after randomisation, thus, the primary outcome was assessed in 292 participants (145 in the azithromycin group and 147 in the standard care group). The mean age of the participants was 45·9 years (SD 14·9). 15 (10%) participants in the azithromycin group and 17 (12%) in the standard care group were admitted to hospital or died during the study (adjusted OR 0·91 [95% CI 0·43–1·92], p=0·80). No serious adverse events were reported. Interpretation In patients with mild-to-moderate COVID-19 managed without hospital admission, adding azithromycin to standard care treatment did not reduce the risk of subsequent hospital admission or death. Our findings do not support the use of azithromycin in patients with mild-to-moderate COVID-19. Funding National Institute for Health Research Oxford Biomedical Research Centre, University of Oxford and Pfizer.

Objectives: This is a protocol for a Cochrane Review (intervention). The objectives are as follows:. To evaluate the effects of subcutaneous omalizumab versus placebo for asthma in adults and children.

Background: Non-suppression of fractional exhaled nitric oxide (FeNO) during remotely monitored inhaled corticosteroid (ICS) therapy is associated with persistent symptoms and blood eosinophilia. To provide mechanistic insight, we assessed sputum type 2 cytokines and chemokines before and after a FeNO suppression test. Methods: FeNO suppression was performed in 44 patients with severe asthma and FeNO > 40 ppb. FeNO was monitored for 7 days of 1000μg of fluticasone propionate delivered via an INCATM device, with clinical and sputum sampling on days 0 and 7. FeNO suppression was defined as a 42% reduction in FeNO. Sputum supernatant was analyzed in 15 paired samples by ELISA (Prostaglandin D2, Leukotriene E4) and MSD assays (IL-4,-5,-13,-25,-33, CCL26, TSLP). Results: Suppressors (n=21) vs non-suppressors had a greater drop in ACQ-5 (mean∆: -1.2 vs -0.3, p Conclusion: Failure to suppress FeNO during ICS treatment was associated with steroid-unresponsive sputum PGD2 and LTE4 levels.

Reduction of the risk of asthma attacks is a major goal of current asthma management. We propose to derive a risk scale predicting asthma attacks based on the blood eosinophil count and exhaled nitric oxide (FeNO). Biomarker-stratified trial-level attack rates were extracted and pooled from the control arms of the Novel START, CAPTAIN, QUEST, Benralizumab Phase 2b, PATHWAY, STRATOS 1–2 and DREAM trials (n=3051). These were used to derive rate ratios and the predicted asthma attack rate for different patient groups. The resultant prototype risk scale shows potential to predict asthma attacks, which may be prevented by anti-inflammatory treatment.

Background Pleural infection is a common and severe disease with high morbidity and mortality worldwide. The knowledge of pleural infection bacteriology remains incomplete, as pathogen detection methods based on culture have insufficient sensitivity and are biased to selected microbes. We designed a study with the aim to discover and investigate the total microbiome of pleural infection and assess the correlation between bacterial patterns and 1-year survival of patients. Methods We assessed 243 pleural fluid samples from the PILOT study, a prospective observational study on pleural infection, with 16S rRNA next generation sequencing. 20 pleural fluid samples from patients with pleural effusion due to a non-infectious cause and ten PCR-grade water samples were used as controls. Downstream analysis was done with the DADA2 pipeline. We applied multivariate Cox regression analyses to investigate the association between bacterial patterns and 1-year survival of patients with pleural infection. Findings Pleural infection was predominately polymicrobial (192 [79%] of 243 samples), with diverse bacterial frequencies observed in monomicrobial and polymicrobial disease and in both community-acquired and hospital-acquired infection. Mixed anaerobes and other Gram-negative bacteria predominated in community-acquired polymicrobial infection whereas Streptococcus pneumoniae prevailed in monomicrobial cases. The presence of anaerobes (hazard ratio 0·46, 95% CI 0·24–0·86, p=0·015) or bacteria of the Streptococcus anginosus group (0·43, 0·19–0·97, p=0·043) was associated with better patient survival, whereas the presence (5·80, 2·37–14·21, p Interpretation Pleural infection is a predominantly polymicrobial infection, explaining the requirement for broad spectrum antibiotic cover in most individuals. High mortality infection associated with S aureus and Enterobacteriaceae favours more aggressive, with a narrower spectrum, antibiotic strategies. Funding UK Medical Research Council, National Institute for Health Research Oxford Biomedical Research Centre, Wellcome Trust, Oxfordshire Health Services Research Committee, Chinese Academy of Medical Sciences, and John Fell Fund.

BackgroundIn people with mild asthma poor adherence to regular therapy is common and increases the risk of exacerbations, morbidity and mortality. The use of fixed-dose combination inhalers containing an inhaled corticosteroid (ICS) and a fast-acting β2-agonist (FABA) is established in moderate asthma, but they may also have potential utility in mild asthma.ObjectivesTo evaluate the efficacy and safety of single combined FABA/ICS inhaler only used as needed in people with mild asthma.Design and settingCochrane meta-analysis of available trial data.ParticipantsChildren aged 12+ and adults with mild asthma.Search methodsWe searched the Cochrane Airways Trials Register, Cochrane Central Register of Controlled Trials, MEDLINE and Embase, ClinicalTrials.gov and the WHO trials portal on 19 March 2021.InterventionsA single fixed-dose FABA/ICS inhaler used as required compared with no treatment, placebo, short-acting beta agonist (SABA) as required, regular ICS with SABA as required, regular fixed-dose combination ICS/long-acting beta agonist (LABA), or regular fixed-dose combination ICS/FABA with as required ICS/FABA.We included randomised controlled trials (RCTs) and cross-over trial. We excluded trials shorter than 12 weeks. We included full texts, abstracts and unpublished data.Data collection and analysisWe used Cochrane’s standard methodological procedures and applied the GRADE approach to assess the evidence.Main outcome measuresWe included six studies from which 9657 participants contributed to the meta-analyses. All used dry powder budesonide and formoterol as the combination inhaler. Two studies included children aged 12+ years and two studies were open-label.FABA/ICS as-required versus FABA as-requiredCompared with as-required FABA alone, as-required FABA/ICS reduced exacerbations requiring systemic steroids (OR 0.45, 95% CI 0.34 to 0.60, 2 RCTs, 2997 participants, high-certainty evidence), equivalent to 109 people out of 1000 in the FABA alone group experiencing an exacerbation requiring systemic steroids, compared with 52 (95% CI 40 to 68) out of 1000 in the FABA/ICS as-required group. FABA/ICS as required may also reduce the odds of an asthma-related hospital admission or emergency department or urgent care visit (OR 0.35, 95% CI 0.20 to 0.60, 2 RCTs, 2997 participants, low-certainty evidence). Changes in asthma control were small and less than the minimal clinically important difference (MCID). FABA/ICS as required was associated with reductions in fractional exhaled nitric oxide, probably reducing the odds of an adverse event (OR 0.82, 95% CI 0.71 to 0.95) and may reduce total systemic steroid dose (mean difference (MD) −9.90, 95% CI −19.38 to −0.42).FABA/ICS as required versus regular ICS plus FABA as requiredThere may be little or no difference in the number of people with asthma exacerbations requiring systemic steroids with FABA/ICS as required compared with regular ICS (OR 0.79, 95% CI 0.59 to 1.07, 4 RCTs, 8065 participants, low-certainty evidence), equivalent to 81 people out of 1000 in the regular ICS plus FABA group experiencing an exacerbation requiring systemic steroids, compared with 65 (95% CI 49 to 86) out of 1000 in the FABA/ICS as-required group. The odds of an asthma-related hospital admission or emergency department or urgent care visit may be reduced in those taking FABA/ICS as required (OR 0.63, 95% CI 0.44 to 0.91, 4 RCTs, 8065 participants, low-certainty evidence). Changes in asthma control were small and less than MCID. Adverse events and total systemic corticosteroid doses were similar between groups. FABA/ICS as required was likely associated with less average daily exposure to ICS than those on regular ICS (MD −154.51 mcg/day, 95% CI −207.94 to −101.09).ConclusionsFABA/ICS as required is clinically effective in adults and adolescents with mild asthma and reduced exacerbations, hospital admissions or unscheduled healthcare visits and exposure to systemic corticosteroids and probably reduces adverse events compared with FABA as required alone. FABA/ICS as required is as effective as regular ICS and reduced asthma-related hospital admissions or unscheduled healthcare visits, and average exposure to ICS, and is unlikely associated with increased adverse events.

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., In a chronic obstructive pulmonary disease (COPD) cohort (EvA, n = 283), 12 genes, whereas in asthma cohort (UBIOPRED, n = 85), 1197 genes in bronchial epithelial brushes were correlated with a blood eosinophil count. The gene CST1 was common to eosinophilic asthma and COPD and was replicated in independent cohorts. Despite shared “treatable traits” between asthma and COPD, the molecular mechanisms underlying these clinical entities are predominately different.

Background Asthma affects 350 million people worldwide including 45% to 70% with mild disease. Treatment is mainly with inhalers containing beta₂‐agonists, typically taken as required to relieve bronchospasm, and inhaled corticosteroids (ICS) as regular preventive therapy. Poor adherence to regular therapy is common and increases the risk of exacerbations, morbidity and mortality. Fixed‐dose combination inhalers containing both a steroid and a fast‐acting beta₂‐agonist (FABA) in the same device simplify inhalers regimens and ensure symptomatic relief is accompanied by preventative therapy. Their use is established in moderate asthma, but they may also have potential utility in mild asthma. Objectives To evaluate the efficacy and safety of single combined (fast‐onset beta₂‐agonist plus an inhaled corticosteroid (ICS)) inhaler only used as needed in people with mild asthma. Search methods We searched the Cochrane Airways Trials Register, Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE and Embase, ClinicalTrials.gov and the World Health Organization (WHO) trials portal. We contacted trial authors for further information and requested details regarding the possibility of unpublished trials. The most recent search was conducted on 19 March 2021. Selection criteria We included randomised controlled trials (RCTs) and cross‐over trials with at least one week washout period. We included studies of a single fixed‐dose FABA/ICS inhaler used as required compared with no treatment, placebo, short‐acting beta agonist (SABA) as required, regular ICS with SABA as required, regular fixed‐dose combination ICS/long‐acting beta agonist (LABA), or regular fixed‐dose combination ICS/FABA with as required ICS/FABA. We planned to include cluster‐randomised trials if the data had been or could be adjusted for clustering. We excluded trials shorter than 12 weeks. We included full texts, abstracts and unpublished data. Data collection and analysis Two review authors independently extracted data. We analysed dichotomous data as odds ratios (OR) or rate ratios (RR) and continuous data as mean difference (MD). We reported 95% confidence intervals (CIs). We used Cochrane's standard methodological procedures of meta‐analysis. We applied the GRADE approach to summarise results and to assess the overall certainty of evidence. Primary outcomes were exacerbations requiring systemic steroids, hospital admissions/emergency department or urgent care visits for asthma, and measures of asthma control. Main results We included six studies of which five contributed results to the meta‐analyses. All five used budesonide 200 μg and formoterol 6 μg in a dry powder formulation as the combination inhaler. Comparator fast‐acting bronchodilators included terbutaline and formoterol. Two studies included children aged 12+ and adults; two studies were open‐label. A total of 9657 participants were included, with a mean age of 36 to 43 years. 2.3% to 11% were current smokers. FABA / ICS as required versus FABA as required Compared with as‐required FABA alone, as‐required FABA/ICS reduced exacerbations requiring systemic steroids (OR 0.45, 95% CI 0.34 to 0.60, 2 RCTs, 2997 participants, high‐certainty evidence), equivalent to 109 people out of 1000 in the FABA alone group experiencing an exacerbation requiring systemic steroids, compared to 52 (95% CI 40 to 68) out of 1000 in the FABA/ICS as‐required group. FABA/ICS as required may also reduce the odds of an asthma‐related hospital admission or emergency department or urgent care visit (OR 0.35, 95% CI 0.20 to 0.60, 2 RCTs, 2997 participants, low‐certainty evidence). Compared with as‐required FABA alone, any changes in asthma control or spirometry, though favouring as‐required FABA/ICS, were small and less than the minimal clinically‐important differences. We did not find evidence of differences in asthma‐associated quality of life or mortality. For other secondary outcomes FABA/ICS as required was associated with reductions in fractional exhaled nitric oxide, probably reduces the odds of an adverse event (OR 0.82, 95% CI 0.71 to 0.95, 2 RCTs, 3002 participants, moderate‐certainty evidence) and may reduce total systemic steroid dose (MD ‐9.90, 95% CI ‐19.38 to ‐0.42, 1 RCT, 443 participants, low‐certainty evidence), and with an increase in the daily inhaled steroid dose (MD 77 μg beclomethasone equiv./day, 95% CI 69 to 84, 2 RCTs, 2554 participants, moderate‐certainty evidence). FABA/ICS as required versus regular ICS plus FABA as required There may be little or no difference in the number of people with asthma exacerbations requiring systemic steroid with FABA/ICS as required compared with regular ICS (OR 0.79, 95% CI 0.59 to 1.07, 4 RCTs, 8065 participants, low‐certainty evidence), equivalent to 81 people out of 1000 in the regular ICS plus FABA group experiencing an exacerbation requiring systemic steroids, compared to 65 (95% CI 49 to 86) out of 1000 FABA/ICS as required group. The odds of an asthma‐related hospital admission or emergency department or urgent care visit may be reduced in those taking FABA/ICS as required (OR 0.63, 95% CI 0.44 to 0.91, 4 RCTs, 8065 participants, low‐certainty evidence). Compared with regular ICS, any changes in asthma control, spirometry, peak flow rates (PFR), or asthma‐associated quality of life, though favouring regular ICS, were small and less than the minimal clinically important differences (MCID). Adverse events, serious adverse events, total systemic corticosteroid dose and mortality were similar between groups, although deaths were rare, so confidence intervals for this analysis were wide. We found moderate‐certainty evidence from four trials involving 7180 participants that FABA/ICS as required was likely associated with less average daily exposure to inhaled corticosteroids than those on regular ICS (MD ‐154.51 μg/day, 95% CI ‐207.94 to ‐101.09). Authors' conclusions We found FABA/ICS as required is clinically effective in adults and adolescents with mild asthma. Their use instead of FABA as required alone reduced exacerbations, hospital admissions or unscheduled healthcare visits and exposure to systemic corticosteroids and probably reduces adverse events. FABA/ICS as required is as effective as regular ICS and reduced asthma‐related hospital admissions or unscheduled healthcare visits, and average exposure to ICS, and is unlikely to be associated with an increase in adverse events. Further research is needed to explore use of FABA/ICS as required in children under 12 years of age, use of other FABA/ICS preparations, and long‐term outcomes beyond 52 weeks.

BackgroundThe antibacterial, anti-inflammatory and antiviral properties of azithromycin suggest therapeutic potential against COVID-19. Randomised data in mild-moderate disease are lacking. We assessed whether azithromycin is effective in reducing hospitalisation in patients with mild-moderate COVID-19.MethodsThis open-label, randomised superiority clinical trial at 19 centres in the United Kingdom enrolled adults, ≥18 years, presenting to hospitals with clinically-diagnosed highly-probable or confirmed COVID-19 infection, with NCT04381962, Study closed.Findings298 participants were enrolled from 3rd June 2020 to 29th January 2021. The primary outcome was assessed in 292 participants. The primary endpoint was not significantly different between the azithromycin and control groups (Adjusted OR 0·91 [95% CI 0·43-1·92], p=0·80). Rates of respiratory failure, progression to pneumonia, all-cause mortality, and adverse events, including serious cardiovascular events, were not significantly different between groups.InterpretationIn patients with mild-moderate COVID-19 managed without hospital admission, adding azithromycin to standard care treatment did not reduce the risk of subsequent hospitalisation or death. Our findings do not support the use of azithromycin in patients with mild-moderate COVID-19.FundingNIHR Oxford BRC, University of Oxford and Pfizer Inc.Research in contextEvidence before this studyWe searched MEDLINE and the Cochrane Central register of Controlled Trials (CENTRAL) with the terms (“azithromycin”) AND (“COVID” OR “COVID-19”) AND (“clinical trials”), until March 25, 2021, with no language restrictions. We identified 42 studies, among which there were four completed randomised trials of azithromycin (with or without hydroxychloroquine) in hospitalised patients with severe disease, and three completed randomised trials of azithromycin in mild COVID-19 in primary care. The four trials in hospitalised patients randomised 8,988 participants to azithromycin or standard care or hydroxychloroquine and found no evidence of a difference in mortality, duration of hospital stay or peak disease severity. Of the three trials in primary care, these randomised participants with early disease to 3 or 5 days of therapy, of which only one assessed azithromycin as standalone therapy. This large, adaptive platform trial in the UK randomised 540 participants in primary care to 3 days treatment with azithromycin versus 875 to standard care alone and found no meaningful difference in time to first reported recovery, or of rates of hospitalisation (3% versus 3%) and there were no deaths. We did not identify any randomised trials in patients with COVID-19 managed in ambulatory care.Added value of this studyThe ATOMIC2 trial was uniquely-designed to assess azithromycin as a standalone therapy in those with mild-moderately COVID-19 presenting to emergency care, but assessed as appropriate for initial ambulatory management without hospital admission. ATOMIC2 also uniquely assessed high-dose, long-duration treatment to investigate the efficacy of putative anti-inflammatory effects. We found that azithromycin 500 mg daily for 14 days did not reduce the proportion of participants who died or required hospital admission from any cause over the 28 days from randomisation.Implications of all the available evidenceOur findings, taken together with existing data, suggest there is no evidence that azithromycin reduces hospitalisation, respiratory failure or death compared with standard care, either in early disease in the community, or those hospitalised with severe disease, or in those with moderate disease managed on an ambulatory pathway.

COVID-19, caused by the novel coronavirus SARS-CoV-2, is a global health issue with more than 2 million fatalities to date. Viral replication is shaped by the cellular microenvironment and one important factor to consider is oxygen tension, where hypoxia inducible factor (HIF) regulates transcriptional responses to hypoxia. SARS-CoV-2 primarily infects cells of the respiratory tract, entering via its Spike glycoprotein binding to angiotensin-converting enzyme (ACE2). We demonstrate that hypoxia and the HIF prolyl hydroxylase inhibitor Roxadustat reduce ACE2 expression and inhibit SARS-CoV-2 entry and replication in lung epithelial cells via a HIF-1α dependent pathway. Hypoxia and Roxadustat inhibit SARS-CoV-2 RNA replication showing that post-entry steps in the viral life cycle are oxygen-sensitive. This study highlights the importance of HIF signalling in regulating multiple aspects of SARS-CoV-2 infection and raises the potential use of HIF prolyl hydroxylase inhibitors in the prevention or treatment of COVID-19., Graphical Abstract, Wing et al. demonstrate that key aspects of the SARS-CoV-2 life cycle are dependent on cellular oxygen tension. Activation of the cellular oxygen sensing pathway inhibits SARS-CoV-2 infection, highlighting a key cellular pathway that could be exploited as a potential therapeutic avenue for COVID-19.

The COVID-19 pandemic, caused by SARS-CoV-2 coronavirus, is a global health issue with unprecedented challenges for public health. SARS-CoV-2 primarily infects cells of the respiratory tract via Spike glycoprotein binding to angiotensin-converting enzyme (ACE2). Circadian rhythms coordinate an organism’s response to its environment and can regulate host susceptibility to virus infection. We demonstrate that silencing the circadian regulator Bmal1 or treating lung epithelial cells with the REV-ERB agonist SR9009 reduce ACE2 expression and inhibit SARS-CoV-2 entry and replication. Importantly, treating infected cells with SR9009 limits SARS-CoV-2 replication and secretion of infectious particles, showing that post-entry steps in the viral life cycle are influenced by the circadian system. Transcriptome analysis revealed that Bmal1 silencing induced interferon stimulated gene transcripts in Calu-3 lung epithelial cells, providing a mechanism for the circadian pathway to limit SARS-CoV-2 infection. Our study highlights alternative approaches to understand and improve therapeutic targeting of SARS-CoV-2., Graphical Abstract

Background: The antibacterial, anti-inflammatory and antiviral properties of azithromycin suggest therapeutic potential against COVID-19. Randomised data in mild-moderate disease are lacking. We assessed whether azithromycin is effective in reducing hospitalisation in patients with mild-moderate COVID-19. Methods: This open-label, randomised superiority clinical trial at 19 centres in the United Kingdom enrolled adults, ≥18 years, presenting to hospitals with clinically-diagnosed highly-probable or confirmed COVID-19 infection, with

Vaccines get a help-MAIT Mucosal-associated invariant T (MAIT) cells are a T cell subset important for mucosal homeostasis. These cells recognize derivatives of microbiota-derived vitamin B2 precursors but can also be activated by certain cytokines in the context of viral infections. Provine et al. report that a leading adenoviral vector vaccine, ChAdOx1, activated MAIT cells in immunized mice (see the Perspective by Juno and O'Connor). This activation required interferon-α produced by plasmacytoid dendritic cells as well as monocyte-derived interleukin-18 and tumor necrosis factor. MAIT cell activation positively correlated with vaccine-mediated T cell responses in human subjects, and mice deficient in MAIT cells showed impaired CD8 + T cell immunity to target antigens after vaccination. This work suggests an additional pathway that could be exploited to enhance the efficacy of vaccines. Science , this issue p. 521 ; see also p. 460

Summary Azithromycin (AZM) is a synthetic macrolide antibiotic effective against a broad range of bacterial and mycobacterial infections. Due to an additional range of anti‐viral and anti‐inflammatory properties, it has been given to patients with the coronaviruses SARS‐CoV or MERS‐CoV. It is now being investigated as a potential candidate treatment for SARS‐CoV‐2 having been identified as a candidate therapeutic for this virus by both in vitro and in silico drug screens. To date there are no randomised trial data on its use in any novel coronavirus infection, although a large number of trials are currently in progress. In this review, we summarise data from in vitro, murine and human clinical studies on the anti‐viral and anti‐inflammatory properties of macrolides, particularly AZM. AZM reduces in vitro replication of several classes of viruses including rhinovirus, influenza A, Zika virus, Ebola, enteroviruses and coronaviruses, via several mechanisms. AZM enhances expression of anti‐viral pattern recognition receptors and induction of anti‐viral type I and III interferon responses. Of relevance to severe coronavirus‐19 disease (COVID‐19), which is characterised by an over‐exuberant innate inflammatory response, AZM also has anti‐inflammatory properties including suppression of IL‐1beta, IL‐2, TNF and GM‐CSF. AZM inhibits T cells by inhibiting calcineurin signalling, mammalian target of rapamycin activity and NFκB activation. AZM particularly targets granulocytes where it concentrates markedly in lysosomes, particularly affecting accumulation, adhesion, degranulation and apoptosis of neutrophils. Given its proven safety, affordability and global availability, tempered by significant concerns about antimicrobial stewardship, there is an urgent mandate to perform well‐designed and conducted randomised clinical trials.

This is part 3.6 of the "Study of MAIT Cell Activation in Viral Infections In Vivo" collection of protocols. Collection Abstract: MAIT cells are abundant, highly evolutionarily conserved innate-like lymphocytes expressing a semi-invariant T cell receptor (TCR), which recognizes microbially derived small intermediate molecules from the riboflavin biosynthetic pathway. However, in addition to their TCR-mediated functions they can also be activated in a TCR-independent manner via cytokines including IL-12, -15, -18, and type I interferon. Emerging data suggest that they are expanded and activated by a range of viral infections, and significantly that they can contribute to a protective anti-viral response. Here we describe methods used to investigate these anti-viral functions in vivo in murine models. To overcome the technical challenge that MAIT cells are rare in specific pathogen-free laboratory mice, we describe how pulmonary MAIT cells can be expanded using intranasal bacterial infection or a combination of synthetic MAIT cell antigen and TLR agonists. We also describe protocols for adoptive transfer of MAIT cells, methods for lung homogenization for plaque assays, and surface and intracellular cytokine staining to determine MAIT cell activation. Abstract: Viral plaque assays are used to determine influenza viral titers. A diluted solution of egg-adapted Influenza A viruses/lung-infected tissue homogenates are applied to a six-well tissue culture dish containing a monolayer of Madin-Darby canine kidney (MDCK) cells. The infected MDCK cells grow under a semisolid overlay medium (agar) containing trypsin. A plaque is produced when a virus particle infects a cell, replicates, and then kills the cell. This process can be repeated several times as surrounding cells can be infected by newly replicated virus and killed. When visualized by eye, plaques appear as white spots. The assay is measured in PFU/mL.

This is part 3.4 of the "Study of MAIT Cell Activation in Viral Infections In Vivo" collection of protocols. Collection Abstract: MAIT cells are abundant, highly evolutionarily conserved innate-like lymphocytes expressing a semi-invariant T cell receptor (TCR), which recognizes microbially derived small intermediate molecules from the riboflavin biosynthetic pathway. However, in addition to their TCR-mediated functions they can also be activated in a TCR-independent manner via cytokines including IL-12, -15, -18, and type I interferon. Emerging data suggest that they are expanded and activated by a range of viral infections, and significantly that they can contribute to a protective anti-viral response. Here we describe methods used to investigate these anti-viral functions in vivo in murine models. To overcome the technical challenge that MAIT cells are rare in specific pathogen-free laboratory mice, we describe how pulmonary MAIT cells can be expanded using intranasal bacterial infection or a combination of synthetic MAIT cell antigen and TLR agonists. We also describe protocols for adoptive transfer of MAIT cells, methods for lung homogenization for plaque assays, and surface and intracellular cytokine staining to determine MAIT cell activation.

This is part 3.5 of the "Study of MAIT Cell Activation in Viral Infections In Vivo" collection of protocols. Collection Abstract: MAIT cells are abundant, highly evolutionarily conserved innate-like lymphocytes expressing a semi-invariant T cell receptor (TCR), which recognizes microbially derived small intermediate molecules from the riboflavin biosynthetic pathway. However, in addition to their TCR-mediated functions they can also be activated in a TCR-independent manner via cytokines including IL-12, -15, -18, and type I interferon. Emerging data suggest that they are expanded and activated by a range of viral infections, and significantly that they can contribute to a protective anti-viral response. Here we describe methods used to investigate these anti-viral functions in vivo in murine models. To overcome the technical challenge that MAIT cells are rare in specific pathogen-free laboratory mice, we describe how pulmonary MAIT cells can be expanded using intranasal bacterial infection or a combination of synthetic MAIT cell antigen and TLR agonists. We also describe protocols for adoptive transfer of MAIT cells, methods for lung homogenization for plaque assays, and surface and intracellular cytokine staining to determine MAIT cell activation.

MAIT cells are abundant, highly evolutionarily conserved innate-like lymphocytes expressing a semi-invariant T cell receptor (TCR), which recognizes microbially derived small intermediate molecules from the riboflavin biosynthetic pathway. However, in addition to their TCR-mediated functions they can also be activated in a TCR-independent manner via cytokines including IL-12, -15, -18, and type I interferon. Emerging data suggest that they are expanded and activated by a range of viral infections, and significantly that they can contribute to a protective anti-viral response. Here we describe methods used to investigate these anti-viral functions in vivo in murine models. To overcome the technical challenge that MAIT cells are rare in specific pathogen-free laboratory mice, we describe how pulmonary MAIT cells can be expanded using intranasal bacterial infection or a combination of synthetic MAIT cell antigen and TLR agonists. We also describe protocols for adoptive transfer of MAIT cells, methods for lung homogenization for plaque assays, and surface and intracellular cytokine staining to determine MAIT cell activation.

This is part 3.2 of the "Study of MAIT Cell Activation in Viral Infections In Vivo" collection of protocols. Collection Abstract: MAIT cells are abundant, highly evolutionarily conserved innate-like lymphocytes expressing a semi-invariant T cell receptor (TCR), which recognizes microbially derived small intermediate molecules from the riboflavin biosynthetic pathway. However, in addition to their TCR-mediated functions they can also be activated in a TCR-independent manner via cytokines including IL-12, -15, -18, and type I interferon. Emerging data suggest that they are expanded and activated by a range of viral infections, and significantly that they can contribute to a protective anti-viral response. Here we describe methods used to investigate these anti-viral functions in vivo in murine models. To overcome the technical challenge that MAIT cells are rare in specific pathogen-free laboratory mice, we describe how pulmonary MAIT cells can be expanded using intranasal bacterial infection or a combination of synthetic MAIT cell antigen and TLR agonists. We also describe protocols for adoptive transfer of MAIT cells, methods for lung homogenization for plaque assays, and surface and intracellular cytokine staining to determine MAIT cell activation.

This is part 3.3 of the "Study of MAIT Cell Activation in Viral Infections In Vivo" collection of protocols. Collection Abstract: MAIT cells are abundant, highly evolutionarily conserved innate-like lymphocytes expressing a semi-invariant T cell receptor (TCR), which recognizes microbially derived small intermediate molecules from the riboflavin biosynthetic pathway. However, in addition to their TCR-mediated functions they can also be activated in a TCR-independent manner via cytokines including IL-12, -15, -18, and type I interferon. Emerging data suggest that they are expanded and activated by a range of viral infections, and significantly that they can contribute to a protective anti-viral response. Here we describe methods used to investigate these anti-viral functions in vivo in murine models. To overcome the technical challenge that MAIT cells are rare in specific pathogen-free laboratory mice, we describe how pulmonary MAIT cells can be expanded using intranasal bacterial infection or a combination of synthetic MAIT cell antigen and TLR agonists. We also describe protocols for adoptive transfer of MAIT cells, methods for lung homogenization for plaque assays, and surface and intracellular cytokine staining to determine MAIT cell activation.

Sensing of influenza A virus (IAV) infection by pattern recognition receptors can occur by either direct infection of lung epithelial cells or uptake of virus-infected cells by innate cells such as dendritic cells/monocytes. This triggers a series of downstream events including activation of the inflammasome, the production of cytokines, chemokines, and the upregulation of stress-induced ligands that can lead to the activation of innate cells. These cells include innate lymphocytes such as MAIT, NKT, NK, and γδ T cells. Here we describe a method used to allow activation of human innate lymphocytes in co-culture with an IAV-infected human lung epithelial cell line (A549) to measure ex vivo effector functions (TNF and IFNγ) in a mixed culture environment. We describe (1) infection of the human lung epithelial cell line, (2) co-culture with PBMC, and (3) measurement of activation using intracellular cytokine staining.

This is part 3.1 of the "Study of MAIT Cell Activation in Viral Infections In Vivo" collection of protocols. Collection Abstract: MAIT cells are abundant, highly evolutionarily conserved innate-like lymphocytes expressing a semi-invariant T cell receptor (TCR), which recognizes microbially derived small intermediate molecules from the riboflavin biosynthetic pathway. However, in addition to their TCR-mediated functions they can also be activated in a TCR-independent manner via cytokines including IL-12, -15, -18, and type I interferon. Emerging data suggest that they are expanded and activated by a range of viral infections, and significantly that they can contribute to a protective anti-viral response. Here we describe methods used to investigate these anti-viral functions in vivo in murine models. To overcome the technical challenge that MAIT cells are rare in specific pathogen-free laboratory mice, we describe how pulmonary MAIT cells can be expanded using intranasal bacterial infection or a combination of synthetic MAIT cell antigen and TLR agonists. We also describe protocols for adoptive transfer of MAIT cells, methods for lung homogenization for plaque assays, and surface and intracellular cytokine staining to determine MAIT cell activation. Abstract: MAIT cells are rare in specific pathogen-free mice [6], typically comprising about 1 x 104 recoverable pulmonary MAIT cells in an infection-naive adult C57BL/6 mouse. Therefore, for adoptive transfer experiments, the MAIT cell population should first be expanded using intranasal infection [15] or immunization (5-OP-RU with TLR agonists) [3, 15] (see Note 5). When planning the adoptive transfer experiment, estimate that one S. Typhimurium BRD509-infected mouse will yield 1–2 x 106 sorted MAITcells, which are enough for 10–20 recipient mice (105 MAIT cells/RAG2–/–γC–/– mouse in this case). Infect donor mice 7 days earlier than the adoptive transfer.

Background: Prednisolone is widely used to treat acute exacerbations of airway disease. There is evidence that they act by depleting circulating eosinophils within hours of the first dose. Potentially the anti-IL-5 biologics may be a safer and longer-lasting alternative, although whether they deplete blood eosinophils as quickly as prednisolone is unclear. Methods: We assessed blood eosinophil counts at baseline and, 2, 4, 6, 8, 24 and 96 h, or until blood eosinophils Results: Groups did not differ significantly in demographics, inhaled corticosteroid dose, lung function and baseline blood eosinophil count. The mean(SD) time for blood eosinophil level to decrease 50% from baseline was 25.8(14.3), 1.7(0.7) and 2.5(0.4) hours on mepolizumab, benralizumab and prednisolone respectively (p≤0.001 for both benralizumab and prednisolone compared to mepolizumab) (Fig. 1). Conclusion: Benralizumab depletes blood eosinophils as rapidly as prednisolone and may therefore be an alternative treatment for acute eosinophilic asthma exacerbations. Larger studies comparing this approach to current treatment are awaited.

Background: Pleural infection (PI) is a common and complex disease which can be life threatening for immunocompromised and elderly populations. Prior antibiotic use and special bacterial nutritional requirements hamper the accuracy of bacterial identification using current clinical culture-based techniques. Consequently, PI microbiology remains unclear. Next generation sequencing (NGS) has the potential to improve identification of the total bacterial population of a complex sample. Aim: To discover and characterise the microbial patterns of PI using NGS and bioinformatics techniques. Methods: Pleural fluid samples from the “Pleural Infection Longitudinal Outcome Study” (PILOT, ISRCTN50236700, n=243) underwent bacterial DNA extraction followed by 16S rRNA NGS using Illumina MiSeq. Data were analysed with DADA2 and Phyloseq R packages. Results: Analysis showed diverse microbiological patterns for PI as 391 different pathogens were identified up to the genus level. 131 (54%) samples had one pathogen with relative abundance over 50% and 89 (36%) samples had at least three pathogens with relative abundance over 10%, suggesting a polymicrobial infection. Streptococcus pneumoniae was detected in 40 (16%) and Staphylococcus aureus in 20 (8%) samples. Discussion: We established a methodology to extract bacterial DNA from patients with PI and used it as a template to apply NGS. 16S rRNA gene NGS provides a robust method to investigate the bacteriological patterns in pleural fluid of patients with PI. Funding: National Institute for Health Research, Oxford Biomedical Research Centre

Intro: Prior metagenomic studies in asthma are limited by inconsistent clinical phenotyping and inadequate sequencing depth for species-level bacterial identification. We hypothesise chronic bacterial infection is i) a ‘treatable trait’ whose prevalence, clinical phenotype and reliable biomarkers need definition and ii) is best characterised using Nanopore sequencing. Aims/Methods: To compare performance of Illumina MiSeq, Nanopore sequencing, and RT-qPCR on total DNA extracts against culture/MALDI-TOF for analysis of induced sputum samples from well-phenotyped severe asthma. Results: In 23 patients with with severe asthma Haemophilus influenzae was commonly cultured (n=8/23), and identified as the dominant bacterial species by metagenomic sequencing using MiSeq and Nanopore. Nanopore provided superior operational characterisitics and longer read lengths allowing whole bacterial genome reconstruction and greater resolution between species. Clinically significant infection was confirmed with validated H.inf plasmid-based RT-qPCR assay. H.inf culture positive patients had sputum neutrophilia and lower FeNO. Conclusions:H.inf is a clinically-relevant pathogen in severe ashma and is identified reliably using molecular microbiological methods. Application of these optimised protocols in ongoing analysis of 3 large patient cohorts is allowing full characterisation of this clinical phenotype.

Background Azithromycin is an orally active synthetic macrolide antibiotic with a wide range of anti-bacterial, anti-inflammatory and antiviral properties. It is a safe, inexpensive, generic licenced drug available worldwide and manufactured to scale and is a potential candidate therapy for pandemic coronavirus disease 2019 (COVID-19). Azithromycin was widely used to treat severe SARS-CoV and MERS-CoV, but to date, no randomised data are available in any coronavirus infections. Other ongoing trials are exploring short courses of azithromycin either in early disease, within the first 7 days of symptoms, when azithromycin’s antiviral properties may be important, or late in disease when anti-bacterial properties may reduce the risk of secondary bacterial infection. However, the molecule’s anti-inflammatory properties, including suppression of pulmonary macrophage-derived pro-inflammatory cytokines such as interleukins-1β, -6, -8, and -18 and cytokines G-CSF and GM-CSF may provide a distinct therapeutic benefit if given in as a prolonged course during the period of progression from moderate to severe disease. Methods ATOMIC2 is a phase II/III, multi-centre, prospective, open-label, two-arm randomised superiority clinical trial of azithromycin versus standard care for adults presenting to hospital with COVID-19 symptoms who are not admitted at initial presentation. We will enrol adults, ≥ 18 years of age assessed in acute hospitals in the UK with clinical diagnosis of COVID-19 infection where management on an ambulatory care pathway is deemed appropriate. Participants will be randomised in a 1:1 ratio to usual care or to azithromycin 500 mg orally daily for 14 days with telephone follow-up at days 14 and 28. The primary objective is to compare the proportion with either death or respiratory failure requiring invasive or non-invasive mechanical ventilation over 28 days from randomisation. Secondary objectives include mortality/respiratory failure in those with a PCR-confirmed diagnosis; all-cause mortality; progression to pneumonia; progression to severe pneumonia; peak severity of illness and mechanistic analysis of blood and nasal biomarkers. Discussion This trial will determine the clinical utility of azithromycin in patients with moderately severe, clinically diagnosed COVID-19 and could be rapidly applicable worldwide. Trial registration ClinicalTrials.gov NCT04381962. Registered on 11 May 2020. EudraCT identifier 2020-001740-26. Opened for accrual on 29 May 2020.

To-date, there has not been a clear signal suggesting that asthma or treatment with inhaled steroids are a risk factor for severe COVID-19 disease. We have therefore explored ACE2 receptor mRNA expression, and co-factors for Sars-CoV-2 infectivity (TMPRSS2 and furin) in bronchial brushes and biopsies from people with asthma and healthy controls, and looked for relationships between asthma severity, Th2- and IL-17 dependent gene signatures, and clinical demographics (age, sex). We have looked at a cohort of 356 research participants from previously described studies. The only significant association was a positive correlation between ACE2 and IL-17-dependent gene expression, and an inverse correlation between ACE2 and Th2-cytokine-dependent gene expression. These data suggest that differences in ACE2, TMPRSS2 and furin epithelial and airway gene expression are unlikely to confer enhanced COVID-19 pneumonia risk in patients with asthma across all treatment intensities and severity., Expression of mRNA for ACE2, the Sars-CoV-2 receptor, is similar in the lower airways of healthy controls and people with mild-severe asthma. Altered ACE2 expression is unlikely to confer enhanced COVID-19 pneumonia risk in asthma.

Monoclonal antibodies targeting IgE or the type-2 cytokines interleukin (IL)-4, IL-5 and IL-13 are proving highly effective in reducing exacerbations and symptoms in people with severe allergic and eosinophilic asthma, respectively. However, these therapies are not appropriate for 30–50% of patients in severe asthma clinics who present with non-allergic, non-eosinophilic, “type-2 low” asthma. These patients constitute an important and common clinical asthma phenotype, driven by distinct, yet poorly understood pathobiological mechanisms. In this review we describe the heterogeneity and clinical characteristics of type-2 low asthma and summarise current knowledge on the underlying pathobiological mechanisms, which includes neutrophilic airway inflammation often associated with smoking, obesity and occupational exposures and may be driven by persistent bacterial infections and by activation of a recently described IL-6 pathway. We review the evidence base underlying existing treatment options for specific treatable traits that can be identified and addressed. We focus particularly on severe asthma as opposed to difficult-to-treat asthma, on emerging data on the identification of airway bacterial infection, on the increasing evidence base for the use of long-term low-dose macrolides, a critical appraisal of bronchial thermoplasty, and evidence for the use of biologics in type-2 low disease. Finally, we review ongoing research into other pathways including tumour necrosis factor, IL-17, resolvins, apolipoproteins, type I interferons, IL-6 and mast cells. We suggest that type-2 low disease frequently presents opportunities for identification and treatment of tractable clinical problems; it is currently a rapidly evolving field with potential for the development of novel targeted therapeutics.

Mucosal associated invariant T (MAIT) cells are striking in their abundance and their strict conservation across 150 million years of mammalian evolution, implying they must fulfil critical immunological function(s). MAIT cells are defined by their expression of a semi-invariant αβ TCR which recognises biosynthetic derivatives of riboflavin synthesis presented on MR1. Initial studies focused on their role in detecting predominantly intracellular bacterial and mycobacterial infections. However, it is now recognised that there are several modes of MAIT cell activation and these are related to activation of distinct transcriptional programmes, each associated with distinct functional roles. In this minireview, we summarise current knowledge from human and animal studies of MAIT cell activation induced 1) in an MR1-TCR dependent manner in the context of inflammatory danger signals and associated with antibacterial host defence; 2) in an MR1-TCR independent manner by the cytokines interleukin(IL)-12 / -15 / -18 and type I interferon, which is associated with antiviral responses; and 3) a recently-described TCR-dependent ‘tissue repair’ programme which is associated with accelerated wound healing in the context of commensal microbiota. Because of this capability for diverse functional responses in diverse immunological contexts, these intriguing cells now appear to be multifunctional effectors central to the interface of innate and adaptive immunity.

Coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection is a new rapidly spreading infectious disease. Current guidance from the World Health Organization (WHO) highlights asthmatics as a high-risk group for severe illness from COVID-19. Viruses are common triggers of asthma exacerbations and the current SARS-CoV-2 pandemic raises several questions regarding the optimum management strategies. Here, we discuss the contentious issue of whether the mainstay therapy systemic corticosteroids should be used in the routine management of COVID-19-associated asthma exacerbations. Recent guidance from the WHO has advised against the use of corticosteroids if COVID-19 is suspected due to concerns that these agents may impair protective innate antiviral immune responses. This may not be appropriate in the unique case of asthma exacerbation, a syndrome associated with augmented type 2 inflammation, a disease feature that is known to directly inhibit antiviral immunity. Corticosteroids, through their suppressive effects on type 2 inflammation, are thus likely to restore impaired antiviral immunity in asthma and, in contrast to non-asthmatic subjects, have beneficial clinical effects in the context of SARS-CoV-2 infection.

While there now exist effective treatments for type 2 high, eosinophilic asthma, there are no specific therapies for 40–50% of people with asthma with other phenotypes, which result from poorly understood underlying pathological mechanisms. One such pathology is neutrophilic inflammation, which has been associated with interleukin (IL)-17 family cytokines. Human genetic studies identified IL-17 polymorphisms associated with asthma; in murine models of allergic airways disease, IL-17A contributes to airway hyperresponsiveness, and in humans, elevated airway IL-17A levels are repeatedly observed in severe asthma. However, the directionality of this association is unknown, and the assumption that IL-17 cytokines drive disease pathology remains speculative. Here, we explore the evidence underlying the relationship between IL-17 and asthma, we review lessons learned from investigating IL-17 in other inflammatory diseases, and discuss the possibility that IL-17 may even be protective in asthma rather than pathogenic. We also critically examine the newly proposed paradigm of a reciprocal relationship between type 2 and type 17 airways inflammation. In summary, we suggest an association between IL-17 and asthma, but research is needed examining the diverse functions of these cytokines, their longitudinal stability, their response to clinical interventions, and for mechanistic studies determining whether they are protective or pathogenic., IL-17 cytokines have been implicated in neutrophilic asthma by genetic, murine and human data. Here, previous studies are critiqued and the assumption their dominant role is pathogenic rather than protective of airway epithelial barrier integrity is challenged. http://bit.ly/3axB4Zs

Rationale: On November 21, 2016 in Australia, a major thunderstorm-asthma epidemic struck Melbourne with an unprecedented number of emergency presentations, hospital admissions and fatalities. Objectives: We identified affected patients who presented to The Royal Melbourne Hospital, an adult tertiary center in North-West Melbourne. We aimed to characterize individual patient factors associated with hospital admission and identify biomarkers in patient subgroups that are at risk of being severely affected by thunderstorm-asthma. Methods: Cross-sectional, retrospective analysis of demographics of 240 patients presenting to The Royal Melbourne Hospital on November 21 to 22, 2016 post thunderstorm-asthma event and clinical characteristics of 70 of those patients who subsequently attended an outpatient clinic review. Results: Patients were generally young adults (mean age 35 years), with seasonal rhinitis (96%) and universally (100%) sensitized to ryegrass pollen. Forty-four patients (63%) had a known diagnosis of asthma while 20% reported no previous diagnosis but had symptoms consistent with asthma. Patient characteristics associated with hospitalization were: uncontrolled asthma symptoms in the month before the thunderstorm-asthma event, symptomatic allergic rhinitis, high blood eosinophilia and lower lung function. Conclusion: Thunderstorm-asthma affects people with seasonal rhinitis, ryegrass sensitization and can occur without prior history of asthma, with dramatic potential to inundate a healthcare system. Our data suggests that hospitalization, and thus a more severe thunderstorm-asthma exacerbation, was associated with a known history of asthma, prior uncontrolled asthma symptoms, allergic rhinitis, high eosinophil count and lower lung function. These factors may inform strategies to identify those most at risk of thunderstorm-asthma.

COVID-19, caused by the novel coronavirus SARS-CoV-2, is a global health issue with more than 1 million fatalities to date. Understanding how host factors modify the viral life cycle could inform susceptibility to viral infection and the design of new therapies. Viral replication is shaped by the cellular microenvironment and one important factor is local oxygen tension, where hypoxia inducible factor (HIF) regulates transcriptional responses to hypoxia. SARS-CoV-2 primarily infects cells of the respiratory tract, entering via its Spike glycoprotein binding to angiotensin-converting enzyme (ACE2). We demonstrate that hypoxia and the HIF prolyl hydroxylase inhibitor Roxadustat (FG-4592) reduce ACE2 expression and inhibit SARS-CoV-2 entry and replication in lung epithelial cells via a HIF-1α dependent signalling pathway. Further, hypoxia and Roxadustat inhibit viral replication in SARS-CoV-2 infected cells, showing that post-entry steps in the viral life cycle are oxygen-sensitive. This study highlights the importance of hypoxia and HIF signalling in regulating multiple aspects of SARS-CoV-2 infection and raises the potential use of HIF prolyl hydroxylase inhibitors in the prevention and/or treatment of COVID-19. Funding: The McKeating laboratory is funded by a Wellcome Investigator Award (IA) 200838/Z/16/Z, UK Medical Research Council (MRC) project grant MR/R022011/1 and Chinese Academy of Medical Sciences (CAMS) Innovation Fund for Medical Science (CIFMS), China (grant number: 2018-I2M-2-002). The Ratcliffe laboratory is funded by the Oxford Branch of the Ludwig Institute for Cancer Research; Wellcome IA 106241/Z/14/Z; the Francis Crick Institute, which receives core funding from Cancer Research UK (FC001501), UK MRC (FC001501) and Wellcome (FC001501); the Paradifference Foundation. PJR, EJH and TB are additionally funded by the COVID-19 Research Response Fund, University of Oxford. SK is funded by the Clarendon Scholarships Fund and the Christopher Welch Trust. The Davis laboratory is funded by Wellcome IA 209412/Z/17/Z and Wellcome Strategic Awards 091911/B/10/Z and 107457/Z/15/Z. JYL is funded by the Medial Sciences Graduate Studentship, University of Oxford. The Hinks laboratory is funded by grants from the Wellcome (104553/z/14/z, 211050/Z/18/z) and the National Institute for Health Research (NIHR) Oxford Biomedical Research Centre; the views expressed are those of the authors and not those of the NHS or NIHR. Conflict of Interest: EJH is employed under the Cambridge Experimental Medicine Initiative, which is partly funded by AstraZeneca although they have not been involved in this project. The other authors declare no financial interests. Ethical Approval: The study was reviewed by the Oxford Research Ethics Committee B (18/SC/0361).

MAIT cells are abundant, highly evolutionarily conserved innate-like lymphocytes expressing a semi-invariant T cell receptor (TCR), which recognizes microbially derived small intermediate molecules from the riboflavin biosynthetic pathway. However, in addition to their TCR-mediated functions they can also be activated in a TCR-independent manner via cytokines including IL-12, -15, -18, and type I interferon. Emerging data suggest that they are expanded and activated by a range of viral infections, and significantly that they can contribute to a protective anti-viral response. Here we describe methods used to investigate these anti-viral functions in vivo in murine models. To overcome the technical challenge that MAIT cells are rare in specific pathogen-free laboratory mice, we describe how pulmonary MAIT cells can be expanded using intranasal bacterial infection or a combination of synthetic MAIT cell antigen and TLR agonists. We also describe protocols for adoptive transfer of MAIT cells, methods for lung homogenization for plaque assays, and surface and intracellular cytokine staining to determine MAIT cell activation.

Sensing of influenza A virus (IAV) infection by pattern recognition receptors can occur by either direct infection of lung epithelial cells or uptake of virus-infected cells by innate cells such as dendritic cells/monocytes. This triggers a series of downstream events including activation of the inflammasome, the production of cytokines, chemokines, and the upregulation of stress-induced ligands that can lead to the activation of innate cells. These cells include innate lymphocytes such as MAIT, NKT, NK, and γδ T cells. Here we describe a method used to allow activation of human innate lymphocytes in co-culture with an IAV-infected human lung epithelial cell line (A549) to measure ex vivo effector functions (TNF and IFNγ) in a mixed culture environment. We describe (1) infection of the human lung epithelial cell line, (2) co-culture with PBMC, and (3) measurement of activation using intracellular cytokine staining.

Asthma arises from the complex interplay of inflammatory pathways in diverse cell types and tissues. We sought to undertake a comprehensive transcriptomic assessment of the epithelium and airway T cells that remain understudied in asthma and investigate interactions between multiple cells and tissues. Epithelial brushings and flow-sorted CD3+ T cells from sputum and BAL were obtained from healthy subjects (n = 19) and patients with asthma (mild, moderate, and severe asthma; n = 46). Gene expression was assessed using Affymetrix HT HG-U133+ PM GeneChips, and results were validated by real-time quantitative PCR. In the epithelium, IL-13 response genes (POSTN, SERPINB2, and CLCA1), mast cell mediators (CPA3 and TPSAB1), inducible nitric oxide synthase, and cystatins (CST1, CST2, and CST4) were upregulated in mild asthma, but, except for cystatins, were suppressed by corticosteroids in moderate asthma. In severe asthma—with predominantly neutrophilic phenotype—several distinct processes were upregulated, including neutrophilia (TCN1 and MMP9), mucins, and oxidative stress responses. The majority of the disease signature was evident in sputum T cells in severe asthma, where 267 genes were differentially regulated compared with health, highlighting compartmentalization of inflammation. This signature included IL-17–inducible chemokines (CXCL1, CXCL2, CXCL3, IL8, and CSF3) and chemoattractants for neutrophils (IL8, CCL3, and LGALS3), T cells, and monocytes. A protein interaction network in severe asthma highlighted signatures of responses to bacterial infections across tissues (CEACAM5, CD14, and TLR2), including Toll-like receptor signaling. In conclusion, the activation of innate immune pathways in the airways suggests that activated T cells may be driving neutrophilic inflammation and steroid-insensitive IL-17 response in severe asthma.

Coal workers' pneumoconiosis (CWP), as part of the spectrum of coal mine dust lung disease (CMDLD), is a preventable but incurable lung disease that can be complicated by respiratory failure and death. Recent increases in coal production from the financial incentive of economic growth lead to higher respirable coal and quartz dust levels, often associated with mechanization of longwall coal mining. In Australia, the observed increase in the number of new CWP diagnoses since the year 2000 has necessitated a review of recommended respirable dust exposure limits, where exposure limits and monitoring protocols should ideally be standardized. Evidence that considers the regulation of engineering dust controls in the mines is lacking even in high-income countries, despite this being the primary preventative measure. Also, it is a global public health priority for at-risk miners to be systemically screened to detect early changes of CWP and to include confirmed patients within a central registry; a task limited by financial constraints in less developed countries. Characteristic X-ray changes are usually categorized using the International Labour Office classification, although future evaluation by low-dose HRCT) chest scanning may allow for CWP detection and thus avoidance of further exposure, at an earlier stage. Preclinical animal and human organoid-based models are required to explore potential re-purposing of anti-fibrotic and related agents with potential efficacy. Epidemiological patterns and the assessment of molecular and genetic biomarkers may further enhance our capacity to identify susceptible individuals to the inhalation of coal dust in the modern era.

The complexity of asthma is underscored by the number of cell types and mediators implicated in the pathogenesis of this heterogeneous syndrome. Type 2 CD4+ T-cells (Th2) and more recently, type 2 innate lymphoid cells dominate current descriptions of asthma pathogenesis. However, another important source of these type 2 cytokines, especially interleukin (IL)-5 and IL-13, are CD8+ T-cells, which are increasingly proposed to play an important role in asthma pathogenesis, because they are abundant and are comparatively insensitive to corticosteroids. Many common triggers of asthma exacerbations are mediated via corticosteroid-resistant pathways involving neutrophils and CD8+ T-cells. Extensive murine data reveal the plasticity of CD8+ T-cells and their capacity to enhance airway inflammation and airway dysfunction. In humans, Tc2 cells are predominant in fatal asthma, while in stable state, severe eosinophilic asthma is associated with greater numbers of Tc2 than Th2 cells in blood, bronchoalveolar lavage fluid and bronchial biopsies. Tc2 cells strongly express CRTH2, the receptor for prostaglandin D2, the cysteinyl leukotriene receptor 1 and the leukotriene B4 receptor. When activated, these elicit Tc2 cell chemotaxis and production of chemokines and type 2 and other cytokines, resulting directly or indirectly in eosinophil recruitment and survival. These factors position CD8+ Tc2 cells as important and underappreciated effector cells contributing to asthma pathogenesis. Here, we review recent advances and new insights in understanding the pro-asthmatic functions of CD8+ T-cells in eosinophilic asthma, especially corticosteroid-resistant asthma, and the molecular mechanisms underlying their pathologic effector function.

Introduction: CRTH2 antagonists are a promising therapy for T2-high disorders, particularly uncontrolled eosinophilic asthma. Biomarkers to identify patients likely to respond to treatment would be a useful advance. We set out to investigate the relationship between the effect of 12 weeks’ treatment with the CRTH2 antagonist timapiprant on the induced sputum eosinophil count and a range of blood and sputum biomarkers. Methods and Materials: Peripheral blood and induced sputum samples were collected from 20 patients with severe eosinophilic asthma at baseline and 12 weeks after oral treatment with 50 mg timapiprant daily. Immune cell counts in blood were determined with flow cytometry. Cell numbers in sputum were determined by slide counting. Correlations were assessed non-parametrically using Prism 7. Results: Timapiprant treatment reduced the geometric mean sputum eosinophils from 11% to 2.5% (Fold reduction 4.5; 95% CI 1.9 to 9.7; p=0.001). Baseline blood total CRTH2+ cells (r=0.75; p Conclusion: High levels of blood total CRTH2+ cells, eosinophils, basophils, Tc2 cells, and sputum eosinophils are associated with the anti-inflammatory effect of timapiprant treatment and could be potential predictive biomarkers of response.

Introduction: Prostaglandin D2 acting via the DP2 receptor plays an important role in the pathogenesis of the steroid-resistant airway inflammation in severe eosinophilic asthma. We tested this hypothesis in a randomised, placebo-controlled, double-blind, parallel group proof of concept study of the effects of the DP2 antagonist timapiprant (OC459) on sputum eosinophil counts in patients with severe eosinophilic asthma. Methods: Patients meeting the ERS/ATS criteria for severe asthma, prior evidence of eosinophilic airway inflammation and screening sputum eosinophil count >3% were randomised to timapiprant 50 mg or placebo once daily for 12 weeks. Induced sputum eosinophil counts, lung function parameters, symptoms and quality of life were assessed at baseline and at 4, 8 and 12 weeks. Results: 68 patients were screened and 40 randomised. The geometric mean induced sputum eosinophil count reduced from 11.0% at baseline to 2.5% at 12 weeks with timapiprant (n=20) and from 10.7% to 6.2% with placebo (n=19). A 2.3-fold reduction (p=0.151) in sputum eosinophil level at week 12 for timapiprant compared to placebo was observed. The difference between groups for change from baseline in pre-bronchodilator FEV1 at week 12 was 127 ml (95% CI: -77 to 330 ml; p=0.214). The safety profile of timapiprant was comparable to that of placebo. Conclusions: Treatment for 12 weeks with timapiprant in severe eosinophilic asthma patients was associated with an evident reduction of airway eosinophilic inflammation and an increase in FEV1 (although not statistically significant due to the limited sample size). Studies in larger population are needed to confirm these effects.