A paradigm shift brought by the recognition that childhood asthma is an aggregated diagnosis that comprises several different endotypes underpinned by different pathophysiology, coupled with advances in understanding potentially important causal mechanisms, offers a real opportunity for a step change to reduce the burden of the disease on individual children, families, and society. Data-driven methodologies facilitate the discovery of "hidden" structures within "big healthcare data" to help generate new hypotheses. These findings can be translated into clinical practice by linking discovered "phenotypes" to specific mechanisms and clinical presentations. Epidemiological studies have provided important clues about mechanistic avenues that should be pursued to identify interventions to prevent the development or alter the natural history of asthma-related diseases. Findings from cohort studies followed by mechanistic studies in humans and in neonatal mouse models provided evidence that environments such as traditional farming may offer protection by modulating innate immune responses and that impaired innate immunity may increase susceptibility. The key question of which component of these exposures can be translated into interventions requires confirmation. Increasing mechanistic evidence is demonstrating that shaping the microbiome in early life may modulate immune function to confer protection. Iterative dialogue and continuous interaction between experts with different but complementary skill sets, including data scientists who generate information about the hidden structures within "big data" assets, and medical professionals, epidemiologists, basic scientists, and geneticists who provide critical clinical and mechanistic insights about the mechanisms underpinning the architecture of the heterogeneity, are keys to delivering mechanism-based stratified treatments and prevention.

Acute asthma remains an important medical emergency, the most frequent cause of acute admissions in children and a major source of morbidity for adults with asthma. In all ages with asthma, the presence of exacerbations is an important defining characteristic of asthma severity. In this review, we assess the epidemiology of acute asthma, the triggers of acute exacerbations, and the mechanisms that underlie these exacerbations. We also assess current treatments that prevent exacerbations, with an emphasis on the role of type 2 airway inflammation in the context of acute exacerbations and the novel treatments that effectively target this. Finally we review current management strategies of the exacerbations themselves.

Patients with severe uncontrolled asthma have disproportionally high morbidity and healthcare utilization as compared with their peers with well-controlled disease. Although treatment options for these patients were previously limited, with unacceptable side effects, the emergence of biologic therapies for the treatment of asthma has provided promising targeted therapy for these patients. Biologic therapies target specific inflammatory pathways involved in the pathogenesis of asthma, particularly in patients with an endotype driven by type 2 (T2) inflammation. In addition to anti-IgE therapy that has improved outcomes in allergic asthma for more than a decade, three anti-IL-5 biologics and one anti-IL-4R biologic have recently emerged as promising treatments for T2 asthma. These targeted therapies have been shown to reduce asthma exacerbations, improve lung function, reduce oral corticosteroid use, and improve quality of life in appropriately selected patients. In addition to the currently approved biologic agents, several biologics targeting upstream inflammatory mediators are in clinical trials, with possible approval on the horizon. This article reviews the mechanism of action, indications, expected benefits, and side effects of each of the currently approved biologics for severe uncontrolled asthma and discusses promising therapeutic targets for the future.

RATIONALE Asthma is heterogeneous and knowledge on exacerbation patterns is lacking. Previous studies have had a relatively short follow-up or focused on severe disease. OBJECTIVES To describe exacerbation patterns over a prolonged follow-up in a population that includes patients of all disease severity. METHODS We used electronic health care records to identify patients with asthma aged 18-55 years and their exacerbations from 2007 to 2015. A cohort with greater than or equal to 7 years of data was used to describe exacerbation patterns by asthma severity defined by medication use. Effect estimates for risk factors were calculated for sporadic (single year of exacerbations) and recurrent (>1 yr) exacerbation patterns, using logistic regression. In a nested case-control design, the association between a history of exacerbations, spanning 5 years, and a future exacerbation was examined. MEASUREMENTS AND MAIN RESULTS A total of 51,462 patients were eligible for the 7-year cohort; 64% had no exacerbations. Of those who exacerbated, 51% did so only once; exacerbation frequency increased with disease severity. Only 370 patients (0.7%) were characterized by a frequent-exacerbator phenotype (yearly exacerbations), of whom 58% had mild/moderate asthma. Exacerbation risk factors were not uniquely associated with a particular exacerbation pattern. A past exacerbation increased the risk of a future exacerbation more than all other factors, although this effect dissipated over 5 years. CONCLUSIONS During 7 years of follow-up, exacerbations occur in around one-third of patients. Of those who exacerbate, half do not do so again; the timing of future exacerbations is largely unpredictable. Just 2% exhibit a frequent-exacerbator phenotype. Past exacerbation patterns are the most informative risk factor for predicting future exacerbations.

BACKGROUND Type 2 (T2) inflammation drives airway dysfunction in many patients with asthma; yet, we lack a comprehensive understanding of the airway immune cell types and networks that sustain this inflammation. Moreover, defects in the airway immune system in patients with asthma without T2 inflammation are not established. OBJECTIVES To determine the gene networks that sustain T2 airway inflammation in T2-high asthma and to explore the gene networks that characterize T2-low asthma. METHODS Network analysis of sputum cell transcriptome expression data from 84 subjects with asthma and 27 healthy control subjects was used to identify immune cell type-enriched networks that underlie asthma subgroups. RESULTS Sputum T2 gene expression was characterized by an immune cell network derived from multiple innate immune cells, including eosinophils, mast cells/basophils, and inflammatory dendritic cells. Clustering of subjects within this network stratified subjects into T2-high and T2-low groups, but it also revealed a subgroup of T2-high subjects with uniformly higher expression of the T2 network. These "T2-ultrahigh subjects" were characterized clinically by older age and more severe airflow obstruction and pathologically by a second T2 network derived from T2-skewed, CD11b+/CD103-/IRF4+ classical dendritic cells. Subjects with T2-low asthma were differentiated from healthy control subjects by lower expression of a cytotoxic CD8+ T-cell network, which was negatively correlated with body mass index and plasma IL-6 concentrations. CONCLUSIONS Persistent airway T2 inflammation is a complex construct of innate and adaptive immunity gene expression networks that are variable across individuals with asthma and persist despite steroid treatment. Individuals with T2-low asthma exhibit an airway deficiency in cytotoxic T cells associated with obesity-driven inflammation.

RATIONALE Reslizumab is a humanized anti-IL-5 monoclonal antibody used as add-on maintenance treatment for patients with uncontrolled eosinophilic asthma. OBJECTIVES To predict response and nonresponse to intravenous reslizumab at 52 weeks with an algorithm we developed based on clinical indicators from pivotal clinical trials. METHODS Patients aged 18 years and older who met Global Initiative for Asthma 4 or 5 criteria and received intravenous reslizumab (n = 321) in two trials ( www.clinicaltrials.gov identifiers, NCT01287039 and NCT01285323) were selected as the data source. A mathematical model was constructed that was based on change from baseline to 16 weeks in Asthma Control Questionnaire and Asthma Quality of Life Questionnaire scores and FEV1, and number of clinical asthma exacerbations during the year before enrollment and in the first 16 weeks of treatment, and these measures were evaluated for their ability to predict the outcome at 52 weeks: responder, nonresponder, or indeterminate. MEASUREMENTS AND MAIN RESULTS The algorithm predicted that 276 patients would be classified as responders; in 248 (89.9%), the prediction was correct. In comparison, 26 patients were predicted to be nonresponders; 50.0% of these predictions were correct. Nineteen patients were classified as indeterminate. The algorithm had 95.4-95.5% sensitivity and 40.6-54.1% specificity. Jackknife and cross-study validation confirmed the robustness of the algorithm. CONCLUSIONS Our algorithm enabled prediction at 16 weeks of treatment of the response to intravenous reslizumab treatment at 52 weeks, but it was not suitable for predicting nonresponse. A positive score at 16 weeks should encourage continued treatment, and a negative score should prompt close monitoring to determine whether discontinuation is warranted.

RATIONALE Poor adherence is common in difficult-to-control asthma. Distinguishing patients with difficult-to-control asthma who respond to inhaled corticosteroids (ICS) from refractory asthma is an important clinical challenge. OBJECTIVES Suppression of fractional exhaled nitric oxide (FeNO) with directly observed ICS therapy over 7 days can identify nonadherence to ICS treatment in difficult-to-control asthma. We examined the feasibility and utility of FeNO suppression testing in routine clinical care within UK severe asthma centers using remote monitoring technologies. METHODS A web-based interface with integrated remote monitoring technology was developed to deliver FeNO suppression testing. We examined the utility of FeNO suppression testing to demonstrate ICS responsiveness and clinical benefit on electronically monitored treatment with standard high-dose ICS and long-acting β2-agonist treatment. MEASUREMENTS AND MAIN RESULTS Clinical response was assessed using the Asthma Control Questionnaire-5, spirometry, and biomarker measurements (FeNO and peripheral blood eosinophil count). Of 250 subjects, 201 completed the test with 130 positive suppression tests. Compared with a negative suppression test, a positive test identified a FeNO-low population when adherent with ICS/long-acting β2-agonist (median, 26 ppb [interquartile range, 16-36 ppb] vs. 43 ppb [interquartile range, 38-73 ppb]) with significantly greater FEV1% (mean, 88.2 ± 16.4 vs. 74.1 ± 20.9; P < 0.01). Asthma Control Questionnaire-5 improved significantly in both groups (positive test: mean difference, -1.2; 95% confidence interval, -0.9 to -1.5; negative test: mean difference, -0.9; 95% confidence interval, -0.4 to -1.3). CONCLUSIONS Remote FeNO suppression testing is an effective means of identifying nonadherence to ICS in subjects with difficult-to-control asthma and the substantial population of subjects who derive important clinical benefits from optimized ICS/long-acting β2-agonist treatment.

RATIONALE Accumulation of B cells and lymphoid follicles (LFs) has been described in chronic obstructive pulmonary disease (COPD) airways, but the functional status of lung B cells remains poorly known. OBJECTIVES To characterize LFs for expression of IgA, the main mucosal antibody. METHODS The presence of B cells and LFs, including intrafollicular IgA expression, were determined in the lung from patients with COPD (n = 37) versus control subjects (n = 34) by immunohistochemistry. We also evaluated follicular IgA responses in the lungs from mice infected with Pseudomonas aeruginosa (PAO1) (n = 10 per group) and in smoking mice. MEASUREMENTS AND MAIN RESULTS Whereas in smokers B-cell numbers slightly increased, robust increases in B-cell and LF numbers (mainly in distal airways) were only observed in severe COPD. Most follicular B cells were IgM+ (70-80%), but IgA+ (and not IgG+) B-cell numbers were increased in LFs from severe COPD compared with control subjects (twofold, 44.7% vs. 25.2%), and this was significant in distal but not proximal airways. Follicular IgA response was also observed in PAO1-infected mouse lungs, but not after smoke exposure. Moreover, follicular IgA expression associated with expression of IL-21, which was very potent to activate immunoglobulin production in vitro. CONCLUSIONS This study shows that IgA production occurs in peribronchiolar LFs from severe COPD, where IL-21-producing T cells are present, and presumably represents a feature of exacerbated mucosal adaptive immune responses against microbial and/or self-antigens.

RATIONALE Polymorphisms on chromosome 17q21 confer the major genetic susceptibility to childhood-onset asthma. Risk alleles positively correlate with ORMDL3 (orosomucoid-like 3) expression. The locus influences disease severity and the frequency of human rhinovirus (HRV)-initiated exacerbations. ORMDL3 is known to regulate sphingolipid synthesis by binding serine palmitoyltransferase, but its role in inflammation is incompletely understood. OBJECTIVES To investigate the role of ORMDL3 in cellular inflammation. METHODS We modeled a time series of IL1B-induced inflammation in A549 cells, using cytokine production as outputs and testing effects of ORMDL3 siRNA knockdown, ORMDL3 overexpression, and the serine palmitoyltransferase inhibitor myriocin. We replicated selected findings in normal human bronchial epithelial cells. Cytokine and metabolite levels were analyzed by analysis of variance. Transcript abundances were analyzed by group means parameterization, controlling the false discovery rate below 0.05. MEASUREMENTS AND MAIN RESULTS Silencing ORMDL3 led to steroid-independent reduction of IL6 and IL8 release and reduced endoplasmic reticulum stress after IL1B stimulation. Overexpression and myriocin conversely augmented cytokine release. Knockdown reduced expression of genes regulating host-pathogen interactions, stress responses, and ubiquitination: in particular, ORMDL3 knockdown strongly reduced expression of the HRV receptor ICAM1. Silencing led to changes in levels of transcripts and metabolites integral to glycolysis. Increased levels of ceramides and the immune mediator sphingosine-1-phosphate were also observed. CONCLUSIONS The results show ORMDL3 has pleiotropic effects during cellular inflammation, consistent with its substantial genetic influence on childhood asthma. Actions on ICAM1 provide a mechanism for the locus to confer susceptibility to HRV-induced asthma.

RATIONALE Bronchial epithelial cell damage occurs in patients with bronchial asthma. Ezrin, a membrane-cytoskeleton protein, maintains cellular morphology and intercellular adhesion and protects the barrier function of epithelial cells. OBJECTIVES To study the role of ezrin in bronchial epithelial cells injury and correlate its expression with asthma severity. METHODS Levels of ezrin were measured in exhaled breath condensate (EBC) and serum in patients with asthma and BAL fluid (BALF) from a mouse model of asthma by ELISA. The regulation of IL-13 on ezrin protein levels was studied in primary bronchial epithelial cells. Ezrin knockdown using shRNA was studied in human bronchial epithelial 16HBE cells. MEASUREMENTS AND MAIN RESULTS Ezrin levels were decreased in asthmatic EBC (92.7 ± 34.99 vs. 150.5 ± 10.22 pg/ml, P < 0.0001) and serum (700.7 ± 55.59 vs. 279.2 ± 25.83 pg/ml, P < 0.0001) compared with normal subjects. Levels were much lower in uncontrolled (P < 0.001) and partly controlled patients (P < 0.01) compared with well-controlled subjects. EBC and serum ezrin levels correlated with lung function in patients with asthma and serum ezrin levels were negatively correlated with serum IL-13 and periostin. IL-13-induced downregulation of ezrin expression in primary bronchial epithelial cells was significantly attenuated by the Janus tyrosine kinase 2 inhibitor, TG101348. Ezrin knockdown changed 16HBE cell morphology, enlarged intercellular spaces, and increased their permeability. Ezrin expression was decreased in the lung tissue and BALF of "asthmatic" mice and negatively correlated with BALF IL-13 level. CONCLUSIONS Ezrin downregulation is associated with IL-13-induced epithelial damage and might be a potential biomarker of asthma control.

Critical care medicine is far from the first medical field to come to mind when humanitarian action is mentioned, yet both critical care and humanitarian action share a fundamental purpose to save the lives and ease the suffering of people caught in acute crises. Critically ill children and adults will be present regardless of resource limitations and irrespective of geography, regional or cultural contexts, insecurity, or socioeconomic status, and they may be even more prevalent in a humanitarian crisis. Critical care is not limited to the walls of a hospital, and all hospitals will have critically ill patients regardless of designating a specific ward an ICU. Regular and consistent consideration of critical care principles in humanitarian settings provides crucial guidance to intensivists and nonintensivists alike. A multidisciplinary, systematic approach to patient care that encourages critical thinking, checklists that encourage communication among team members, and context-specific critical care rapid response teams are examples of critical care constructs that can provide high-quality critical care in all environments. Promoting critical care principles conveys the message that critical care is an integral part of health care and should be accessible to all, no matter the setting. These principles can be effectively adopted in humanitarian settings by normalizing them to everyday clinical practice. Equally, core humanitarian principles-dignity, accountability, impartiality, neutrality-can be applied to critical care. Applying principles of critical care in a context-specific manner and applying humanitarian principles to critical care can improve the quality of patient care and transcend barriers to resource limitations.

RATIONALE Noninvasive diagnostic multiplex molecular tests may enable the early identification and treatment of viral infections in critically ill immunocompromised patients. OBJECTIVES To assess the association between viral detection in nasopharyngeal swabs and ICU mortality in critically ill hematology patients. METHODS This was a post hoc analysis of a prospective cohort of critically ill hematology patients admitted to 17 ICUs. Nasal swabs sampled and frozen at ICU admission were tested using a multiplex PCR assay. Predictors of ICU mortality and assay positivity were identified. MEASUREMENTS AND MAIN RESULTS Of the 747 patients (447 with acute respiratory failure [ARF]), 21.3% had a virus detected (56.4% rhinovirus/enterovirus and 30.7% influenza/parainfluenza/respiratory syncytial viruses). Overall ICU and hospital mortality rates were 26% and 37%, respectively. Assay positivity was associated with lymphoproliferative disorders, hematopoietic stem cell transplantation, treatment with steroids or other immunosuppressants, ARF (25.5% vs. 16.3%; P = 0.004), and death in the ICU (28.9% vs. 19.3%; P = 0.008). The association with ICU mortality was significant for all viruses and was strongest for influenza/parainfluenza/respiratory syncytial viruses. In patients with ARF, detection of any respiratory virus was independently associated with ICU mortality (odds ratio, 2.07; 95% confidence interval, 1.22-3.50). CONCLUSIONS Respiratory virus detection in the upper airway by multiplex PCR assay is common in critically ill hematology patients. In patients with ARF, respiratory virus detection was independently associated with ICU mortality. Multiplex PCR assay may prove helpful for the risk stratification of hematology patients with ARF. Studies to understand whether respiratory tract viruses play a causal role in outcomes are warranted.

RATIONALE There is wide variability in mechanical ventilation settings during extracorporeal membrane oxygenation (ECMO) in patients with acute respiratory distress syndrome. Although lung rest is recommended to prevent further injury, there is no evidence to support it. OBJECTIVES To determine whether near-apneic ventilation decreases lung injury in a pig model of acute respiratory distress syndrome supported with ECMO. METHODS Pigs (26-36 kg; n = 24) were anesthetized and connected to mechanical ventilation. In 18 animals lung injury was induced by a double-hit consisting of repeated saline lavages followed by 2 hours of injurious ventilation. Then, animals were connected to high-flow venovenous ECMO, and randomized into three groups: 1) nonprotective (positive end-expiratory pressure [PEEP], 5 cm H2O; Vt, 10 ml/kg; respiratory rate, 20 bpm), 2) conventional-protective (PEEP, 10 cm H2O; Vt, 6 ml/kg; respiratory rate, 20 bpm), and 3) near-apneic (PEEP, 10 cm H2O; driving pressure, 10 cm H2O; respiratory rate, 5 bpm). Six other pigs were used as sham. All groups were maintained during the 24-hour study period. MEASUREMENTS AND MAIN RESULTS Minute ventilation and mechanical power were lower in the near-apneic group, but no differences were observed in oxygenation or compliance. Lung histology revealed less injury in the near-apneic group. Extensive immunohistochemical staining for myofibroblasts and procollagen III was observed in the nonprotective group, with the near-apneic group exhibiting the least alterations. Near-apneic group showed significantly less matrix metalloproteinase-2 and -9 activity. Histologic lung injury and fibroproliferation scores were positively correlated with driving pressure and mechanical power. CONCLUSIONS In an acute respiratory distress syndrome model supported with ECMO, near-apneic ventilation decreased histologic lung injury and matrix metalloproteinase activity, and prevented the expression of myofibroblast markers.

RATIONALE Omega-3 polyunsaturated fatty acids (n-3 PUFAs) have anti-inflammatory properties that could benefit adults with comprised pulmonary health. OBJECTIVE To investigate n-3 PUFA associations with spirometric measures of pulmonary function tests (PFTs) and determine underlying genetic susceptibility. METHODS Associations of n-3 PUFA biomarkers (α-linolenic acid, eicosapentaenoic acid, docosapentaenoic acid [DPA], and docosahexaenoic acid [DHA]) were evaluated with PFTs (FEV1, FVC, and FEV1/FVC) in meta-analyses across seven cohorts from the Cohorts for Heart and Aging Research in Genomic Epidemiology Consortium (N = 16,134 of European or African ancestry). PFT-associated n-3 PUFAs were carried forward to genome-wide interaction analyses in the four largest cohorts (N = 11,962) and replicated in one cohort (N = 1,687). Cohort-specific results were combined using joint 2 degree-of-freedom (2df) meta-analyses of SNP associations and their interactions with n-3 PUFAs. RESULTS DPA and DHA were positively associated with FEV1 and FVC (P < 0.025), with evidence for effect modification by smoking and by sex. Genome-wide analyses identified a novel association of rs11693320-an intronic DPP10 SNP-with FVC when incorporating an interaction with DHA, and the finding was replicated (P2df = 9.4 × 10-9 across discovery and replication cohorts). The rs11693320-A allele (frequency, ∼80%) was associated with lower FVC (PSNP = 2.1 × 10-9; βSNP = -161.0 ml), and the association was attenuated by higher DHA levels (PSNP×DHA interaction = 2.1 × 10-7; βSNP×DHA interaction = 36.2 ml). CONCLUSIONS We corroborated beneficial effects of n-3 PUFAs on pulmonary function. By modeling genome-wide n-3 PUFA interactions, we identified a novel DPP10 SNP association with FVC that was not detectable in much larger studies ignoring this interaction.

RATIONALE The recommended tuberculosis (TB) intensified case finding (ICF) algorithm for people living with HIV (symptom-based screening followed by Xpert MTB/RIF [Xpert] testing) is insufficiently sensitive and results in unnecessary Xpert testing. OBJECTIVES To evaluate whether novel ICF algorithms combining C-reactive protein (CRP)-based screening with urine Determine TB-LAM (TB-LAM), sputum Xpert, and/or sputum culture could improve ICF yield and efficiency. METHODS We compared the yield and efficiency of novel ICF algorithms inclusive of point-of-care CRP-based TB screening and confirmatory testing with urine TB-LAM (if CD4 count ≤100 cells/μl), sputum Xpert, and/or a single sputum culture among consecutive people living with HIV with CD4 counts less than or equal to 350 cells/μl initiating antiretroviral therapy in Uganda. MEASUREMENTS AND MAIN RESULTS Of 1,245 people living with HIV, 203 (16%) had culture-confirmed TB including 101 (49%) patients with CD4 counts less than or equal to 100 cells/μl. Compared with the current ICF algorithm, point-of-care CRP-based TB screening followed by Xpert testing had similar yield (56% [95% confidence interval, 49-63] vs. 59% [95% confidence interval, 51-65]) but consumed less than half as many Xpert assays per TB case detected (9 vs. 4). Addition of TB-LAM did not significantly increase diagnostic yield relative to the current ICF algorithm but provided same-day diagnosis for 26% of TB patients with advanced HIV. Addition of a single culture to TB-LAM and Xpert substantially improved ICF yield, identifying 78% of all TB cases. CONCLUSIONS Point-of-care CRP-based screening can improve ICF efficiency among people living with HIV. Addition of TB-LAM and a single culture to Xpert confirmatory testing could enable HIV programs to increase the speed of TB diagnosis and ICF yield.

RATIONALE Eosinophils drive pathophysiology in stable and exacerbating eosinophilic asthma, and therefore treatment is focused on the reduction of eosinophil numbers. Mepolizumab, a humanized monoclonal antibody that neutralizes IL-5 and efficiently attenuates eosinophils, proved clinically effective in severe eosinophilic asthma but not in mild asthma. OBJECTIVES To study the effect of mepolizumab on virus-induced immune responses in mild asthma. METHODS Patients with mild asthma, steroid-naive and randomized for eosinophil numbers, received 750 mg mepolizumab intravenously in a placebo-controlled double-blind trial, 2 weeks after which patients were challenged with rhinovirus (RV) 16. FEV1, FVC, fractional exhaled nitric oxide, symptom scores (asthma control score), viral load (PCR), eosinophil numbers, humoral (luminex, ELISA), and cellular (flow cytometry) immune parameters in blood, BAL fluid, and sputum, before and after mepolizumab and RV16, were assessed. MEASUREMENTS AND MAIN RESULTS Mepolizumab attenuated baseline blood eosinophils and their activation, attenuated trendwise sputum eosinophils, and enhanced circulating natural killer cells. Mepolizumab did not affect FEV1, FVC, and fractional exhaled nitric oxide, neither at baseline nor after RV16. On RV16 challenge mepolizumab did not prevent eosinophil activation but did enhance local B lymphocytes and macrophages and reduce neutrophils and their activation. Mepolizumab also enhanced secretory IgA and reduced tryptase in BAL fluid. Finally, mepolizumab affected particularly RV16-induced macrophage inflammatory protein-3a, vascular endothelial growth factor-A, and IL-1RA production in BAL fluid. CONCLUSIONS Mepolizumab failed to prevent activation of remaining eosinophils and changed RV16-induced immune responses in mild asthma. Although these latter effects likely are caused by attenuated eosinophil numbers, we cannot exclude a role for basophils. Clinical trial registered with www.clinicaltrials.gov (NCT 01520051).

BACKGROUND This document provides clinical recommendations for the diagnosis of idiopathic pulmonary fibrosis (IPF). It represents a collaborative effort between the American Thoracic Society, European Respiratory Society, Japanese Respiratory Society, and Latin American Thoracic Society. METHODS The evidence syntheses were discussed and recommendations formulated by a multidisciplinary committee of IPF experts. The evidence was appraised and recommendations were formulated, written, and graded using the Grading of Recommendations, Assessment, Development, and Evaluation approach. RESULTS The guideline panel updated the diagnostic criteria for IPF. Previously defined patterns of usual interstitial pneumonia (UIP) were refined to patterns of UIP, probable UIP, indeterminate, and alternate diagnosis. For patients with newly detected interstitial lung disease (ILD) who have a high-resolution computed tomography scan pattern of probable UIP, indeterminate, or an alternative diagnosis, conditional recommendations were made for performing BAL and surgical lung biopsy; because of lack of evidence, no recommendation was made for or against performing transbronchial lung biopsy or lung cryobiopsy. In contrast, for patients with newly detected ILD who have a high-resolution computed tomography scan pattern of UIP, strong recommendations were made against performing surgical lung biopsy, transbronchial lung biopsy, and lung cryobiopsy, and a conditional recommendation was made against performing BAL. Additional recommendations included a conditional recommendation for multidisciplinary discussion and a strong recommendation against measurement of serum biomarkers for the sole purpose of distinguishing IPF from other ILDs. CONCLUSIONS The guideline panel provided recommendations related to the diagnosis of IPF.

RATIONALE Epidemiologic research strongly supports an association between air pollution and chronic obstructive pulmonary disease exacerbations. Numerous mechanisms may underlie any association because pollutants are toxic to pulmonary cells and may increase susceptibility to respiratory infections. The relationship between ambient pollution and exacerbation etiology has not been studied. OBJECTIVES To evaluate the characteristics of pollution-associated exacerbations and whether the association is specific to exacerbations of infective or noninfective etiology. METHODS We analyzed the effect of preceding ambient particulate matter less than or equal to 10 μm in aerodynamic diameter, oxides of nitrogen (NOx), and ozone on characterized chronic obstructive pulmonary disease exacerbations in a regression model adjusted for temperature, seasonality, and long-term trend. We specifically examined associations with exacerbations of suspected viral and/or bacterial, or noninfective etiology. For the associations identified we further examined the characteristics of pollution-associated exacerbations. MEASUREMENTS AND MAIN RESULTS A total of 4,173 exacerbations occurred over the 20-year study period. Higher ambient NOx was consistently associated with increased viral-type exacerbations at 2-4 days lag (P = 0.010). Recovery for viral-type exacerbations after higher ambient NOx was significantly prolonged. These findings were consistent in the subset of 2,841 exacerbations treated with oral corticosteroids or antibiotics, with recovery 1.29 (95% confidence interval, 1.17-1.42; P < 0.001) times longer with viral-type exacerbations of onset 3 days after above- versus below-median ambient NOx. A likely bimodal association of particulate matter less than or equal to 10 μm in aerodynamic diameter with infective exacerbations was also evident and supported by a daily time-series analysis. CONCLUSIONS Higher levels of ambient NOx are associated with prolonged exacerbations of likely viral etiology, supporting toxicologic effects of air pollution that increase susceptibility to, and severity of, infection.

RATIONALE Noncommunicable respiratory diseases and exposure to air pollution are thought to be important contributors to morbidity and mortality in sub-Saharan African adults. OBJECTIVES We set out to explore the prevalence and determinants of noncommunicable respiratory disease among adults living in Chikhwawa District, Malawi. METHODS We performed a cross-sectional study among adults in communities participating in a randomized controlled trial of a cleaner-burning biomass-fueled cookstove intervention (CAPS [Cooking and Pneumonia Study]) in rural Malawi. We assessed chronic respiratory symptoms, spirometric abnormalities, and personal exposure to air pollution (particulate matter <2.5 μm in aerodynamic diameter [PM2.5] and carbon monoxide [CO]). Weighted prevalence estimates were calculated; multivariable and intention-to-treat analyses were done. MEASUREMENTS AND MAIN RESULTS One thousand four hundred eighty-one participants (mean [SD] age, 43.8 [17.8] yr; 57% female) were recruited. The prevalence of chronic respiratory symptoms, spirometric obstruction, and restriction were 13.6% (95% confidence interval [CI], 11.9-15.4), 8.7% (95% CI, 7.0-10.7), and 34.8% (95% CI, 31.7-38.0), respectively. Median 48-hour personal PM2.5 and CO exposures were 71.0 μg/m3 (interquartile range [IQR], 44.6-119.2) and 1.23 ppm (IQR, 0.79-1.93), respectively. Chronic respiratory symptoms were associated with current/ex-smoking (odds ratio [OR], 1.59; 95% CI, 1.05-2.39), previous tuberculosis (OR, 2.50; 95% CI, 1.04-15.58), and CO exposure (OR, 1.46; 95% CI, 1.04-2.05). Exposure to PM2.5 was not associated with any demographic, clinical, or spirometric characteristics. There was no effect of the CAPS intervention on any of the secondary trial outcomes. CONCLUSIONS The burden of chronic respiratory symptoms, abnormal spirometry, and air pollution exposures in adults in rural Malawi is of considerable potential public health importance. We found little evidence that air pollution exposures were associated with chronic respiratory symptoms or spirometric abnormalities and no evidence that the CAPS intervention had effects on the secondary trial outcomes. More effective prevention and control strategies for noncommunicable respiratory disease in sub-Saharan Africa are needed. Clinical trial registered with www.isrctn.com (ISRCTN 59448623).

RATIONALE Idiopathic pulmonary fibrosis (IPF) is a fatal disease with a variable and unpredictable course. OBJECTIVES To determine whether BAL cell gene expression is predictive of survival in IPF. METHODS This retrospective study analyzed the BAL transcriptome of three independent IPF cohorts: Freiburg (Germany), Siena (Italy), and Leuven (Belgium) including 212 patients. BAL cells from 20 healthy volunteers, 26 patients with sarcoidosis stage III and IV, and 29 patients with chronic obstructive pulmonary disease were used as control subjects. Survival analysis was performed by Cox models and component-wise boosting. Presence of airway basal cells was tested by immunohistochemistry and flow cytometry. MEASUREMENTS AND MAIN RESULTS A total of 1,582 genes were predictive of mortality in the IPF derivation cohort in univariate analyses adjusted for age and sex at false discovery rate less than 0.05. A nine-gene signature, derived from the discovery cohort (Freiburg), performed well in both replication cohorts, Siena (P < 0.0032) and Leuven (P = 0.0033). nCounter expression analysis confirmed the array results (P < 0.0001). The genes associated with mortality in BAL cells were significantly enriched for genes expressed in airway basal cells. Further analyses by gene expression, flow cytometry, and immunohistochemistry showed an increase in airway basal cells in BAL and tissues of IPF compared with control subjects, but not in chronic obstructive pulmonary disease or sarcoidosis. CONCLUSIONS Our results identify and validate a BAL signature that predicts mortality in IPF and improves the accuracy of outcome prediction based on clinical parameters. The BAL signature associated with mortality unmasks a potential role for airway basal cells in IPF.

RATIONALE Ventilator management in acute respiratory distress syndrome usually focuses on setting parameters, but events occurring at ventilator disconnection are not well understood. OBJECTIVES To determine if abrupt deflation after sustained inflation causes lung injury. METHODS Male Sprague-Dawley rats were ventilated (low Vt, 6 ml/kg) and randomized to control (n = 6; positive end-expiratory pressure [PEEP], 3 cm H2O; 100 min) or intervention (n = 6; PEEP, 3-11 cm H2O over 70 min; abrupt deflation to zero PEEP; ventilation for 30 min). Lung function and injury was assessed, scanning electron microscopy performed, and microvascular leak timed by Evans blue dye (n = 4/group at 0, 2, 5, 10, and 20 min after deflation). Hemodynamic assessment included systemic arterial pressure (n = 6), echocardiography (n = 4), and right (n = 6) and left ventricular pressures (n = 6). MEASUREMENTS AND MAIN RESULTS Abrupt deflation after sustained inflation (vs. control) caused acute lung dysfunction (compliance 0.48 ± 1.0 vs. 0.82 ± 0.2 m/cm H2O, oxygen saturation as measured by pulse oximetry 67 ± 23.5 vs. 91 ± 4.4%; P < 0.05) and injury (wet/dry ratio 6.1 ± 0.6 vs. 4.6 ± 0.4; P < 0.01). Vascular leak was absent before deflation and maximal 5-10 minutes thereafter; injury was predominantly endothelial. At deflation, left ventricular preload, systemic blood pressure, and left ventricular end-diastolic pressure increased precipitously in proportion to the degree of injury. Injury caused later right ventricular failure. Sodium nitroprusside prevented the increase in systemic blood pressure and left ventricular end-diastolic pressure associated with deflation, and prevented injury. Injury did not occur with gradual deflation. CONCLUSIONS Abrupt deflation after sustained inflation can cause acute lung injury. It seems to be mediated by acute left ventricular decompensation (caused by increased left ventricular preload and afterload) that elevates pulmonary microvascular pressure; this directly injures the endothelium and causes edema, which is potentiated by the surge in pulmonary perfusion.

Asthma is diagnosed on the basis of respiratory symptoms of wheeze, cough, chest tightness, and/or dyspnea together with physiologic evidence of variable expiratory airflow limitation. The prevalence of asthma varies widely around the world, ranging from 0.2% to 21.0% in adults and from 2.8% to 37.6% in 6- to 7-year-old children. Population-based studies in children, adults, and the elderly suggest that from 20% to 70% of people with asthma in the community remain undiagnosed and hence untreated. Underdiagnosis of asthma has been found to be associated with underreporting of respiratory symptoms by patients to physicians as well as poor socioeconomic status. On the opposite side of the spectrum, studies of patients with physician-diagnosed asthma suggest that 30-35% of adults and children diagnosed with asthma do not have current asthma, suggesting that asthma is also overdiagnosed in the community. Overdiagnosis of current asthma can occur because of physicians' failure to confirm variable airflow limitation at the time of diagnosis or when sustained clinical remission of disease goes unrecognized. In this review, we define under- and overdiagnosis and explore the prevalence and burden of under- and overdiagnosis of asthma both in patients and within healthcare systems. We further describe potential solutions to prevent under- and overdiagnosis of asthma.

RATIONALE In 2013, the New York State Department of Health (NYSDOH) began a mandatory state-wide initiative to improve early recognition and treatment of severe sepsis and septic shock. OBJECTIVES This study examines protocol initiation, 3-hour and 6-hour sepsis bundle completion, and risk-adjusted hospital mortality among adult patients with severe sepsis and septic shock. METHODS Cohort analysis included all patients from all 185 hospitals in New York State reported to the NYSDOH from April 1, 2014, to June 30, 2016. A total of 113,380 cases were submitted to NYSDOH, of which 91,357 hospitalizations from 183 hospitals met study inclusion criteria. NYSDOH required all hospitals to submit and follow evidence-informed protocols (including elements of 3-h and 6-h sepsis bundles: lactate measurement, early blood cultures and antibiotic administration, fluids, and vasopressors) for early identification and treatment of severe sepsis or septic shock. MEASUREMENTS AND MAIN RESULTS Compliance with elements of the sepsis bundles and risk-adjusted mortality were studied. Of 91,357 patients, 74,293 (81.3%) had the sepsis protocol initiated. Among these individuals, 3-hour bundle compliance increased from 53.4% to 64.7% during the study period (P < 0.001), whereas among those eligible for the 6-hour bundle (n = 35,307) compliance increased from 23.9% to 30.8% (P < 0.001). Risk-adjusted mortality decreased from 28.8% to 24.4% (P < 0.001) in patients among whom a sepsis protocol was initiated. Greater hospital compliance with 3-hour and 6-hour bundles was associated with shorter length of stay and lower risk and reliability-adjusted mortality. CONCLUSIONS New York's statewide initiative increased compliance with sepsis-performance measures. Risk-adjusted sepsis mortality decreased during the initiative and was associated with increased hospital-level compliance.

RATIONALE Obesity is a major risk factor for obstructive sleep apnea. Although greater dimensional changes in the upper airway during wake respiration have been noted in patients with apnea compared with control subjects, whether these differences remain in the presence of obesity is unknown. OBJECTIVES To evaluate upper airway anatomic characteristics and airway compliance (distensibility) in obese subjects with obstructive sleep apnea compared with obese control subjects. METHODS Dynamic magnetic resonance imaging was performed in 157 obese subjects with apnea and 46 obese control subjects during wakefulness in the midsagittal and three axial upper airway regions (retropalatal, retroglossal, epiglottal). Differences in measurements between subjects with apnea and control subjects, and correlations with apnea-hypopnea index among subjects with apnea, were examined. MEASUREMENTS AND MAIN RESULTS Measurements included airway areas and linear dimensions. Subject-specific coefficients of variation were calculated to examine variability in airway size. Controlling for covariates, the retropalatal area during respiration was significantly smaller in subjects with apnea than control subjects, based on the average (P = 0.003), maximum (P = 0.004), and minimum (P = 0.001) airway area. Airway narrowing was observed in anteroposterior and lateral dimensions (adjusted P < 0.05). Results were similar in an age, sex, and body mass index-matched subsample. There were significant correlations between apnea-hypopnea index and dynamic measures of airway caliber in the retropalatal and retroglossal regions among subjects with apnea. CONCLUSIONS Upper airway caliber during respiration was significantly narrower in obese subjects with apnea than obese control subjects in the retropalatal region. These findings provide further evidence that retropalatal airway narrowing plays an important role in the pathogenesis of obstructive sleep apnea in obese subjects.

RATIONALE Pulmonary arterial hypertension (PAH) is a devastating disease characterized by progressive vasoconstriction and obliterative vascular remodeling that leads to right heart failure (RHF) and death. Current therapies do not target vascular remodeling and RHF, and result in only modest improvement of morbidity and mortality. OBJECTIVES To determine whether targeting HIF-2α (hypoxia-inducible factor-2α) with a HIF-2α-selective inhibitor could reverse PAH and RHF in various rodent PAH models. METHODS HIF-2α and its downstream genes were evaluated in lung samples and pulmonary arterial endothelial cells and smooth muscle cells from patients with idiopathic PAH as well as various rodent PAH models. A HIF-2α-selective inhibitor was used in human lung microvascular endothelial cells and in Egln1Tie2Cre mice, and in Sugen 5416/hypoxia- or monocrotaline-exposed rats. MEASUREMENTS AND MAIN RESULTS Upregulation of HIF-2α and its target genes was observed in lung tissues and isolated pulmonary arterial endothelial cells from patients with idiopathic PAH and three distinct rodent PAH models. Pharmacological inhibition of HIF-2α by the HIF-2α translation inhibitor C76 (compound 76) reduced right ventricular systolic pressure and right ventricular hypertrophy and inhibited RHF and fibrosis as well as obliterative pulmonary vascular remodeling in Egln1Tie2Cre mice and Sugen 5416/hypoxia PAH rats. Treatment of monocrotaline-exposed PAH rats with C76 also reversed right ventricular systolic pressure, right ventricular hypertrophy, and pulmonary vascular remodeling; prevented RHF; and promoted survival. CONCLUSIONS These findings demonstrate that pharmacological inhibition of HIF-2α is a promising novel therapeutic strategy for the treatment of severe vascular remodeling and right heart failure in patients with PAH.

RATIONALE Epidemiologic studies have demonstrated that exposure to particulate matter ambient pollution has adverse effects on lung health, exacerbated by cigarette smoking. Particulate matter less than or equal to 2.5 μm in aerodynamic diameter (PM2.5) is among the most harmful urban pollutants and is closely linked to respiratory disease. OBJECTIVES Based on the knowledge that the small airway epithelium (SAE) plays a central role in the pathogenesis of smoking-related lung disease, we hypothesized that elevated PM2.5 levels are associated with dysregulation of SAE gene expression, which may contribute to the development of respiratory disease. METHODS From 2009 to 2012, healthy nonsmoker (n = 29) and smoker (n = 129) residents of New York City underwent bronchoscopy with SAE brushing (2.6 ± 1.3 samples/subject; total of 405 samples). SAE gene expression was assessed by Affymetrix HG-U133 Plus 2.0 microarray. New York City PM2.5 levels (Environmental Protection Agency data) were averaged for the 30 days before bronchoscopy. A linear mixed model was used to assess PM2.5-related gene dysregulation accounting for multiple clinical and methodologic variables. MEASUREMENTS AND MAIN RESULTS Thirty-day mean PM2.5 levels varied from 6.2 to 18 μg/m3. In nonsmokers, there was no dysregulation of SAE gene expression associated with ambient PM2.5 levels. In marked contrast, n = 219 genes were significantly dysregulated in association with PM2.5 levels in the SAE of smokers. Many of these genes relate to cell growth and transcription regulation. Interestingly, 11% of genes were mitochondria associated. CONCLUSIONS PM2.5 exposure contributes to significant dysregulation of the SAE transcriptome of smokers, linking pollution and airway epithelial biology in the risk of development of respiratory disease in susceptible individuals.

RATIONALE Little is known about human club cells, dome-shaped cells with dense cytoplasmic granules and microvilli that represent the major secretory cells of the human small airways (at least sixth-generation bronchi). OBJECTIVES To define the ontogeny and biology of the human small airway epithelium club cell. METHODS The small airway epithelium was sampled from the normal human lung by bronchoscopy and brushing. Single-cell transcriptome analysis and air-liquid interface culture were used to assess club cell ontogeny and biology. MEASUREMENTS AND MAIN RESULTS We identified the club cell population by unbiased clustering using single-cell transcriptome sequencing. Principal component gradient analysis uncovered an ontologic link between KRT5 (keratin 5)+ basal cells and SCGB1A1 (secretoglobin family 1A member 1)+ club cells, a hypothesis verified by demonstrating in vitro that a pure population of human KRT5+ SCGB1A1- small airway epithelial basal cells differentiate into SCGB1A1+KRT5- club cells on air-liquid interface culture. Using SCGB1A1 as the marker of club cells, the single-cell analysis identified novel roles for these cells in host defense, xenobiotic metabolism, antiprotease, physical barrier function, monogenic lung disorders, and receptors for human viruses. CONCLUSIONS These observations provide novel insights into the molecular phenotype and biologic functions of the human club cell population and identify basal cells as the human progenitor cells for club cells.

RATIONALE Increasing awareness of the prevalence and significance of Preserved Ratio Impaired Spirometry (PRISm), alternatively known as restrictive or Global Initiative for Chronic Obstructive Lung Disease (GOLD)-unclassified spirometry, has expanded the body of knowledge on cross-sectional risk factors. However, longitudinal studies of PRISm remain limited. OBJECTIVES To examine longitudinal patterns of change in lung function, radiographic characteristics, and mortality of current and former smokers with PRISm. METHODS Current and former smokers, aged 45 to 80 years, were enrolled in COPDGene (phase 1, 2008-2011) and returned for a 5-year follow-up (phase 2, 2012-2016). Subjects completed questionnaires, spirometry, chest computed tomography scans, and 6-minute-walk tests at both study visits. Baseline characteristics, longitudinal change in lung function, and mortality were assessed by post-bronchodilator lung function categories: PRISm (FEV1/FVC < 0.7 and FEV1 < 80%), GOLD0 (FEV1/FVC > 0.7 and FEV1 > 80%), and GOLD1-4 (FEV1/FVC < 0.7). MEASUREMENTS AND MAIN RESULTS Although the prevalence of PRISm was consistent (12.4-12.5%) at phases 1 and 2, subjects with PRISm exhibited substantial rates of transition to and from other lung function categories. Among subjects with PRISm at phase 1, 22.2% transitioned to GOLD0 and 25.1% progressed to GOLD1-4 at phase 2. Subjects with PRISm at both phase 1 and phase 2 had reduced rates of FEV1 decline (-27.3 ± 42.1 vs. -33.0 ± 41.7 ml/yr) and comparable proportions of normal computed tomography scans (51% vs. 52.7%) relative to subjects with stable GOLD0 spirometry. In contrast, incident PRISm exhibited accelerated rates of lung function decline. Subjects with PRISm at phase 1 had higher mortality rates relative to GOLD0 and lower rates relative to the GOLD1-4 group. CONCLUSIONS PRISm is highly prevalent, is associated with increased mortality, and represents a transitional state for significant subgroups of subjects. Additional studies to characterize longitudinal progression in PRISm are warranted.