Rationale: Pulmonary emphysema overlaps partially with spirometrically defined chronic obstructive pulmonary disease and is heritable, with moderately high familial clustering.
Objectives: To complete a genome-wide association study (GWAS) for the percentage of emphysema-like lung on computed tomography in the Multi-Ethnic Study of Atherosclerosis (MESA) Lung/SNP Health Association Resource (SHARe) Study, a large, population-based cohort in the United States.
Methods: We determined percent emphysema and upper-lower lobe ratio in emphysema defined by lung regions less than −950 HU on cardiac scans. Genetic analyses were reported combined across four race/ethnic groups: non-Hispanic white (n = 2,587), African American (n = 2,510), Hispanic (n = 2,113), and Chinese (n = 704) and stratified by race and ethnicity.
Measurements and Main Results: Among 7,914 participants, we identified regions at genome-wide significance for percent emphysema in or near SNRPF (rs7957346; P = 2.2 × 10−8) and PPT2 (rs10947233; P = 3.2 × 10−8), both of which replicated in an additional 6,023 individuals of European ancestry. Both single-nucleotide polymorphisms were previously implicated as genes influencing lung function, and analyses including lung function revealed independent associations for percent emphysema. Among Hispanics, we identified a genetic locus for upper-lower lobe ratio near the α-mannosidase–related gene MAN2B1 (rs10411619; P = 1.1 × 10−9; minor allele frequency [MAF], 4.4%). Among Chinese, we identified single-nucleotide polymorphisms associated with upper-lower lobe ratio near DHX15 (rs7698250; P = 1.8 × 10−10; MAF, 2.7%) and MGAT5B (rs7221059; P = 2.7 × 10−8; MAF, 2.6%), which acts on α-linked mannose. Among African Americans, a locus near a third α-mannosidase–related gene, MAN1C1 (rs12130495; P = 9.9 × 10−6; MAF, 13.3%) was associated with percent emphysema.
Conclusions: Our results suggest that some genes previously identified as influencing lung function are independently associated with emphysema rather than lung function, and that genes related to α-mannosidase may influence risk of emphysema.
emphysema; computed tomography; multiethnic; cohort study; genetic association
Rationale: Use of triggers for palliative care consultation has been advocated in intensive care units (ICUs) to ensure appropriate specialist involvement for patients at high risk of unmet palliative care needs. The volume of patients meeting these triggers, and thus the potential workload for providers, is unknown.
Objectives: To estimate the prevalence of ICU admissions who met criteria for palliative care consultation using different sets of triggers.
Methods: Retrospective cohort study of ICU admissions from Project IMPACT for 2001–2008. We assessed the prevalence of ICU admissions meeting one or more primary palliative care triggers, and prevalence meeting any of multiple sets of triggers.
Measurements and Main Results: Overall, 53,124 (13.8%) ICU admissions met one or more primary triggers for palliative care consultation. Variation in prevalence was minimal across different types of units (mean 13.3% in medical ICUs to 15.8% in trauma/burn ICUs; P = 0.41) and individual units (mean 13.8%, median 13.0%, interquartile range, 10.2–16.5%). A comprehensive model combining multiple sets of triggers identified a total of 75,923 (19.7%) ICU admissions requiring palliative care consultation; of them, 85.4% were captured by five triggers: (1) ICU admission after hospital stay greater than or equal to 10 days, (2) multisystem organ failure greater than or equal to three systems, (3) stage IV malignancy, (4) status post cardiac arrest, and (5) intracerebral hemorrhage requiring mechanical ventilation.
Conclusions: Approximately one in seven ICU admissions met triggers for palliative care consultation using a single set of triggers, with an upper estimate of one in five patients using multiple sets of triggers; these estimates were consistent across different types of ICUs and individual units. These results may inform staffing requirements for providers to ensure delivery of specialized palliative care to ICU patients nationally.
end-of-life care; critical care; palliative medicine
Rationale: Respiratory viral infections can result in the establishment of chronic lung diseases. Understanding the early innate immune mechanisms that participate in the development of chronic postviral lung disease may reveal new targets for therapeutic intervention. The intracellular viral sensor protein melanoma differentiation–associated protein 5 (MDA5) sustains the acute immune response to Sendai virus, a mouse pathogen that causes chronic lung inflammation, but its role in the development of postviral chronic lung disease is unknown.
Objectives: To establish the role of MDA5 in the development of chronic lung disease.
Methods: MDA5-deficient or control mice were infected with Sendai virus. The acute inflammatory response was evaluated by profiling chemokine and cytokine expression and by characterizing the composition of the cellular infiltrate. The impact of MDA5 on chronic lung pathology and function was evaluated through histological studies, degree of oxygen saturation, and responsiveness to carbachol.
Measurements and Main Results: MDA5 deficiency resulted in normal virus replication and in a distinct profile of chemokines and cytokines that associated with acute lung neutropenia and enhanced accumulation of alternatively activated macrophages. Diminished expression of neutrophil-recruiting chemokines was also observed in cells infected with influenza virus, suggesting a key role of MDA5 in driving the early accumulation of neutrophils at the infection site. The biased acute inflammatory response of MDA5-deficient mice led to an enhanced chronic lung inflammation, epithelial cell hyperplasia, airway hyperreactivity, and diminished blood oxygen saturation.
Conclusions: MDA5 modulates the development of chronic lung inflammation by regulating the early inflammatory response in the lung.
respiratory virus; chronic lung disease; innate immunity; paramyxovirus
Rationale: Children are an at-risk population for developing complications following influenza infection, but immunologic correlates of disease severity are not understood. We hypothesized that innate cellular immune responses at the site of infection would correlate with disease outcome.
Objectives: To test the immunologic basis of severe illness during natural influenza virus infection of children and adults at the site of infection.
Methods: An observational cohort study with longitudinal sampling of peripheral and mucosal sites in 84 naturally influenza-infected individuals, including infants. Cellular responses, viral loads, and cytokines were quantified from nasal lavages and blood, and correlated to clinical severity.
Measurements and Main Results: We show for the first time that although viral loads in children and adults were similar, innate responses in the airways were stronger in children and varied considerably between plasma and site of infection. Adjusting for age and viral load, an innate immune profile characterized by increased nasal lavage monocyte chemotactic protein-3, IFN-α2, and plasma IL-10 levels at enrollment predicted progression to severe disease. Increased plasma IL-10, monocyte chemotactic protein-3, and IL-6 levels predicted hospitalization. This inflammatory cytokine production correlated significantly with monocyte localization from the blood to the site of infection, with conventional monocytes positively correlating with inflammation. Increased frequencies of CD14lo monocytes were in the airways of participants with lower inflammatory cytokine levels.
Conclusions: An innate profile was identified that correlated with disease progression independent of viral dynamics and age. The airways and blood displayed dramatically different immune profiles emphasizing the importance of cellular migration and localized immune phenotypes.
natural influenza virus infection; human; cytokine; innate immune response; monocyte
Rationale: The death receptor Fas is critical for bacterial clearance and survival of mice after Pseudomonas aeruginosa infection.
Objectives: Fas ligand (FasL)–induced apoptosis is augmented by S-glutathionylation of Fas (Fas-SSG), which can be reversed by glutaredoxin-1 (Grx1). Therefore, the objective of this study was to investigate the interplay between Grx1 and Fas in regulating the clearance of P. aeruginosa infection.
Methods: Lung samples from patients with bronchopneumonia were analyzed by immunofluorescence. Primary tracheal epithelial cells, mice lacking the gene for Grx1 (Glrx1−/−), Glrx1−/− mice treated with caspase inhibitor, or transgenic mice overexpressing Grx1 in the airway epithelium were analyzed after infection with P. aeruginosa.
Measurements and Main Results: Patient lung samples positive for P. aeruginosa infection demonstrated increased Fas-SSG compared with normal lung samples. Compared with wild-type primary lung epithelial cells, infection of Glrx1−/− cells with P. aeruginosa showed enhanced caspase 8 and 3 activities and cell death in association with increases in Fas-SSG. Infection of Glrx1−/− mice with P. aeruginosa resulted in enhanced caspase activity and increased Fas-SSG as compared with wild-type littermates. Absence of Glrx1 significantly enhanced bacterial clearance, and decreased mortality postinfection with P. aeruginosa. Inhibition of caspases significantly decreased bacterial clearance postinfection with P. aeruginosa, in association with decreased Fas-SSG. In contrast, transgenic mice that overexpress Grx1 in lung epithelial cells had significantly higher lung bacterial loads, enhanced mortality, decreased caspase activation, and Fas-SSG in the lung after infection with P. aeruginosa, compared with wild-type control animals.
Conclusions: These results suggest that S-glutathionylation of Fas within the lung epithelium enhances epithelial apoptosis and promotes clearance of P. aeruginosa and that glutaredoxin-1 impairs bacterial clearance and increases the severity of pneumonia in association with deglutathionylation of Fas.
Pseudomonas; glutaredoxin-1; protein S-glutathionylation; Fas; apoptosis
Rationale: Asthma is prospectively associated with
age-related chronic diseases and mortality, suggesting the hypothesis that asthma may
relate to a general, multisystem phenotype of accelerated aging.
Objectives: To test whether chronic asthma is associated with a proposed
biomarker of accelerated aging, leukocyte telomere length.
Methods: Asthma was ascertained prospectively in the Dunedin
Multidisciplinary Health and Development Study cohort (n = 1,037) at nine
in-person assessments spanning ages 9–38 years. Leukocyte telomere length was
measured at ages 26 and 38 years. Asthma was classified as life-course-persistent,
childhood-onset not meeting criteria for persistence, and adolescent/adult-onset. We
tested associations between asthma and leukocyte telomere length using regression
models. We tested for confounding of asthma-leukocyte telomere length associations
using covariate adjustment. We tested serum C-reactive protein and white blood cell
counts as potential mediators of asthma-leukocyte telomere length associations.
Measurements and Main Results: Study members with life-course-persistent
asthma had shorter leukocyte telomere length as compared with sex- and age-matched
peers with no reported asthma. In contrast, leukocyte telomere length in study
members with childhood-onset and adolescent/adult-onset asthma was not different from
leukocyte telomere length in peers with no reported asthma. Adjustment for life
histories of obesity and smoking did not change results. Study members with
life-course-persistent asthma had elevated blood eosinophil counts. Blood eosinophil
count mediated 29% of the life-course-persistent asthma-leukocyte telomere length
Conclusions: Life-course-persistent asthma is related to a proposed
biomarker of accelerated aging, possibly via systemic eosinophilic inflammation. Life
histories of asthma can inform studies of aging.
asthma; telomere; aging; longitudinal; developmental phenotype
Rationale: The incidence of pulmonary arterial hypertension is greater in women, suggesting estrogens may play a role in the disease pathogenesis. Experimentally, in males, exogenously administered estrogen can protect against pulmonary hypertension (PH). However, in models that display female susceptibility, estrogens may play a causative role.
Objectives: To clarify the influence of endogenous estrogen and sex in PH and assess the therapeutic potential of a clinically available aromatase inhibitor.
Methods: We interrogated the effect of reduced endogenous estrogen in males and females using the aromatase inhibitor, anastrozole, in two models of PH: the hypoxic mouse and Sugen 5416/hypoxic rat. We also determined the effects of sex on pulmonary expression of aromatase in these models and in lungs from patients with pulmonary arterial hypertension.
Measurements and Main Results: Anastrozole attenuated PH in both models studied, but only in females. To verify this effect was caused by reduced estrogenic activity we confirmed that in hypoxic mice inhibition of estrogen receptor α also has a therapeutic effect specifically in females. Female rodent lung displays increased aromatase and decreased bone morphogenetic protein receptor 2 and Id1 expression compared with male. Anastrozole treatment reversed the impaired bone morphogenetic protein receptor 2 pathway in females. Increased aromatase expression was also detected in female human pulmonary artery smooth muscle cells compared with male.
Conclusions: The unique phenotype of female pulmonary arteries facilitates the therapeutic effects of anastrozole in experimental PH confirming a role for endogenous estrogen in the disease pathogenesis in females and suggests aromatase inhibitors may have therapeutic potential.
pulmonary hypertension; estrogen; sex
Background: Current classification of pulmonary hypertension (PH) is based on a relatively simple combination of patient characteristics and hemodynamics. This limits customization of treatment, and lacks the clarity of a more granular identification based on individual patient phenotypes. Rapid advances in mechanistic understanding of the disease, improved imaging methods, and innovative biomarkers now provide an opportunity to define PH phenotypes on the basis of biomarkers, advanced imaging, and pathobiology. This document organizes our current understanding of PH phenotypes and identifies gaps in our knowledge.
Methods: A multidisciplinary committee with expertise in clinical care (pulmonary, cardiology, pediatrics, and pathology), clinical research, and/or basic science in the areas of PH identified important questions and reviewed and synthesized the literature.
Results: This document describes selected PH phenotypes and serves as an initial platform to define additional relevant phenotypes as new knowledge is generated. The biggest gaps in our knowledge stem from the fact that our present understanding of PH phenotypes has not come from any particularly organized effort to identify such phenotypes, but rather from reinterpreting studies and reports that were designed and performed for other purposes.
Conclusions: Accurate phenotyping of PH can be used in research studies to increase the homogeneity of study cohorts. Once the ability of the phenotypes to predict outcomes has been validated, phenotyping may also be useful for determining prognosis and guiding treatment. This important next step in PH patient care can optimally be addressed through a consortium of study sites with well-defined goals, tasks, and structure. Planning and support for this could include the National Institutes of Health and the U.S. Food and Drug Administration, with industry and foundation partnerships.
biomarkers; consortium; metabolism; pathobiology; pulmonary circulation
Rationale: In patients with pulmonary alveolar proteinosis (PAP) syndrome, disruption of granulocyte/macrophage colony–stimulating factor (GM-CSF) signaling is associated with pathogenic surfactant accumulation from impaired clearance in alveolar macrophages.
Objectives: The aim of this study was to overcome these barriers by using monocyte-derived induced pluripotent stem (iPS) cells to recapitulate disease-specific and normal macrophages.
Methods: We created iPS cells from two children with hereditary PAP (hPAP) caused by recessive CSF2RAR217X mutations and three normal people, differentiated them into macrophages (hPAP-iPS-Mφs and NL-iPS-Mφs, respectively), and evaluated macrophage functions with and without gene-correction to restore GM-CSF signaling in hPAP-iPS-Mφs.
Measurements and Main Results: Both hPAP and normal iPS cells had human embryonic stem cell–like morphology, expressed pluripotency markers, formed teratomas in vivo, had a normal karyotype, retained and expressed mutant or normal CSF2RA genes, respectively, and could be differentiated into macrophages with the typical morphology and phenotypic markers. Compared with normal, hPAP-iPS-Mφs had impaired GM-CSF receptor signaling and reduced GM-CSF–dependent gene expression, GM-CSF– but not M-CSF–dependent cell proliferation, surfactant clearance, and proinflammatory cytokine secretion. Restoration of GM-CSF receptor signaling corrected the surfactant clearance abnormality in hPAP-iPS-Mφs.
Conclusions: We used patient-specific iPS cells to accurately reproduce the molecular and cellular defects of alveolar macrophages that drive the pathogenesis of PAP in more than 90% of patients. These results demonstrate the critical role of GM-CSF signaling in surfactant homeostasis and PAP pathogenesis in humans and have therapeutic implications for hPAP.
alveolar macrophage; receptor; genetic disease; granulocyte-macrophage colony–stimulating factor; surfactant
The median survival of patients with idiopathic pulmonary fibrosis (IPF) continues to be approximately 3 years from the time of diagnosis, underscoring the lack of effective medical therapies for this disease. In the United States alone, approximately 40,000 patients die of this disease annually. In November 2012, the NHLBI held a workshop aimed at coordinating research efforts and accelerating the development of IPF therapies. Basic, translational, and clinical researchers gathered with representatives from the NHLBI, patient advocacy groups, pharmaceutical companies, and the U.S. Food and Drug Administration to review the current state of IPF research and identify priority areas, opportunities for collaborations, and directions for future research. The workshop was organized into groups that were tasked with assessing and making recommendations to promote progress in one of the following six critical areas of research: (1) biology of alveolar epithelial injury and aberrant repair; (2) role of extracellular matrix; (3) preclinical modeling; (4) role of inflammation and immunity; (5) genetic, epigenetic, and environmental determinants; (6) translation of discoveries into diagnostics and therapeutics. The workshop recommendations provide a basis for directing future research and strategic planning by scientific, professional, and patient communities and the NHLBI.
idiopathic pulmonary fibrosis; alveolar epithelial cells; extracellular matrix; interstitial lung disease; inflammation
Rationale: Emerging evidence suggests a restrictive phenotype of chronic lung allograft dysfunction (CLAD) exists; however, the optimal approach to its diagnosis and clinical significance is uncertain.
Objectives: To evaluate the hypothesis that spirometric indices more suggestive of a restrictive ventilatory defect, such as loss of FVC, identify patients with distinct clinical, radiographic, and pathologic features, including worse survival.
Methods: Retrospective, single-center analysis of 566 consecutive first bilateral lung recipients transplanted over a 12-year period. A total of 216 patients developed CLAD during follow-up. CLAD was categorized at its onset into discrete physiologic groups based on spirometric criteria. Imaging and histologic studies were reviewed when available. Survival after CLAD diagnosis was assessed using Kaplan-Meier and Cox proportional hazards models.
Measurements and Main Results: Among patients with CLAD, 30% demonstrated an FVC decrement at its onset. These patients were more likely to be female, have radiographic alveolar or interstitial changes, and histologic findings of interstitial fibrosis. Patients with FVC decline at CLAD onset had significantly worse survival after CLAD when compared with those with preserved FVC (P < 0.0001; 3-yr survival estimates 9% vs. 48%, respectively). The deleterious impact of CLAD accompanied by FVC loss on post-CLAD survival persisted in a multivariable model including baseline demographic and clinical factors (P < 0.0001; adjusted hazard ratio, 2.73; 95% confidence interval, 1.86–4.04).
Conclusions: At CLAD onset, a subset of patients demonstrating physiology more suggestive of restriction experience worse clinical outcomes. Further study of the biologic mechanisms underlying CLAD phenotypes is critical to improving long-term survival after lung transplantation.
lung transplantation; spirometry; chronic lung allograft dysfunction; bronchiolitis obliterans syndrome
Rationale: Respiratory syncytial virus (RSV) and Streptococcus pneumoniae are major respiratory pathogens. Coinfection with RSV and S. pneumoniae is associated with severe and often fatal pneumonia but the molecular basis for this remains unclear.
Objectives: To determine if interaction between RSV and pneumococci enhances pneumococcal virulence.
Methods: We used confocal microscopy and Western blot to identify the receptors involved in direct binding of RSV and pneumococci, the effects of which were studied in both in vivo and in vitro models of infection. Human ciliated respiratory epithelial cell cultures were infected with RSV for 72 hours and then challenged with pneumococci. Pneumococci were collected after 2 hours exposure and changes in gene expression determined using quantitative real-time polymerase chain reaction.
Measurements and Main Results: Following incubation with RSV or purified G protein, pneumococci demonstrated a significant increase in the inflammatory response and bacterial adherence to human ciliated epithelial cultures and markedly increased virulence in a pneumonia model in mice. This was associated with extensive changes in the pneumococcal transcriptome and significant up-regulation in the expression of key pneumococcal virulence genes, including the gene for the pneumococcal toxin, pneumolysin. We show that mechanistically this is caused by RSV G glycoprotein binding penicillin binding protein 1a.
Conclusions: The direct interaction between a respiratory virus protein and the pneumococcus resulting in increased bacterial virulence and worsening disease outcome is a new paradigm in respiratory infection.
respiratory syncytial virus; pneumococcus; cilia; virulence; G protein
Ex vivo, bronchial epithelial cells from people with asthma are more
susceptible to rhinovirus infection caused by deficient induction of the antiviral
protein, IFN-β. Exogenous IFN-β restores antiviral activity.
Objectives: To compare the efficacy and safety of inhaled IFN-β
with placebo administered to people with asthma after onset of cold symptoms to
prevent or attenuate asthma symptoms caused by respiratory viruses.
Methods: A total of 147 people with asthma on inhaled corticosteroids
(British Thoracic Society Steps 2–5), with a history of virus-associated
exacerbations, were randomized to 14-day treatment with inhaled IFN-β (n =
72) or placebo (n = 75) within 24 hours of developing cold symptoms and were
assessed clinically, with relevant samples collected to assess virus infection and
Measurements and Main Results: A total of 91% of randomized patients
developed a defined cold. In this modified intention-to-treat population, asthma
symptoms did not get clinically significantly worse (mean change in six-item Asthma
Control Questionnaire <0.5) and IFN-β treatment had no significant effect
on this primary endpoint, although it enhanced morning peak expiratory flow recovery
(P = 0.033), reduced the need for additional treatment, and
boosted innate immunity as assessed by blood and sputum biomarkers. In an exploratory
analysis of the subset of more difficult-to-treat, Step 4-5 people with asthma (n
= 27 IFN-β; n = 31 placebo), Asthma Control Questionnaire-6 increased
significantly on placebo; this was prevented by IFN-β (P
Conclusions: Although the trial did not meet its primary endpoint, it
suggests that inhaled IFN-β is a potential treatment for virus-induced
deteriorations of asthma in difficult-to-treat people with asthma and supports the
need for further, adequately powered, trials in this population.
Clinical trial registered with www.clinicaltrials.gov (NCT
innate immunity; treatment; respiratory virus
Rationale: Pulmonary hypertension (PH) associated with fibrotic
idiopathic interstitial pneumonia (IIP; idiopathic pulmonary fibrosis and nonspecific
interstitial pneumonia) confers important additional morbidity and mortality.
Objectives: To evaluate the safety and clinical efficacy of the dual
endothelin-1 receptor antagonist bosentan in this patient group.
Methods: In a randomized, double-blind, placebo-controlled study, 60
patients with fibrotic IIP and right heart catheter confirmed PH were randomized 2:1
to bosentan (n = 40) or placebo (n = 20). The primary study endpoint was a
fall from baseline pulmonary vascular resistance index (PVRi) of 20% or more over 16
Measurements and Main Results: Sixty patients (42 men; mean age, 66.6
± 9.2 yr), with a mean pulmonary artery pressure of 36.0 (± 8.9) mm Hg,
PVRi 13.0 (± 6.7) Wood Units/m2 and reduced cardiac index of 2.21
(± 0.5) L/min/m2 were recruited to the study. Accounting for deaths
and withdrawals, paired right heart catheter data were available for analysis in 39
patients (bosentan = 25, placebo = 14). No difference in the primary
outcome was detected, with seven (28.0%) patients receiving bosentan, and four
(28.6%) receiving placebo achieving a reduction in PVRi of greater than or equal to
20% (P = 0.97) at 16 weeks. There was no change in functional
capacity or symptoms between the two groups at 16 weeks, nor any difference in rates
of serious adverse events or deaths (three deaths in each group).
Conclusions: This study shows no difference in invasive pulmonary
hemodynamics, functional capacity, or symptoms between the bosentan and placebo
groups over 16 weeks. Our data do not support the use of the dual endothelin-1
receptor antagonist, bosentan, in patients with PH and fibrotic IIP.
Clinical trial registered with www.clinicaltrials.gov (NCT
hypertension; pulmonary; interstitial lung diseases; clinical trial
Rationale: Intermittent stimulation of the respiratory system with hypoxia causes persistent increases in respiratory motor output (i.e., long-term facilitation) in animals with spinal cord injury. This paradigm, therefore, has been touted as a potential respiratory rehabilitation strategy.
Objectives: To determine whether acute (daily) exposure to intermittent hypoxia can also evoke long-term facilitation of ventilation after chronic spinal cord injury in humans, and whether repeated daily exposure to intermittent hypoxia enhances the magnitude of this response.
Methods: Eight individuals with incomplete spinal cord injury (>1 yr; cervical [n = 6], thoracic [n = 2]) were exposed to intermittent hypoxia (eight 2-min intervals of 8% oxygen) for 10 days. During all exposures, end-tidal carbon dioxide levels were maintained, on average, 2 mm Hg above resting values. Minute ventilation, tidal volume, and breathing frequency were measured before (baseline), during, and 30 minutes after intermittent hypoxia. Sham protocols consisted of exposure to room air and were administered to a subset of the participants (n = 4).
Measurements and Main Results: Minute ventilation increased significantly for 30 minutes after acute exposure to intermittent hypoxia (P < 0.001), but not after sham exposure. However, the magnitude of ventilatory long-term facilitation was not enhanced over 10 days of intermittent hypoxia exposures.
Conclusions: Ventilatory long-term facilitation can be evoked by brief periods of hypoxia in humans with chronic spinal cord injury. Thus, intermittent hypoxia may represent a strategy for inducing respiratory neuroplasticity after declines in respiratory function that are related to neurological impairment.
Clinical trial registered with www.clinicaltrials.gov (NCT01272011).
intermittent hypoxia; respiration; plasticity
Rationale: IL-4Rα, the common receptor component for IL-4 and IL-13, plays a critical role in IL-4– and IL-13–mediated signaling pathways that regulate airway inflammation and remodeling. However, the regulatory mechanisms underlying IL-4Rα turnover and its signal termination remain elusive.
Objectives: To evaluate the role of STUB1 (STIP1 homology and U-Box containing protein 1) in regulating IL-4R signaling in airway inflammation.
Methods: The roles of STUB1 in IL-4Rα degradation and its signaling were investigated by immunoblot, immunoprecipitation, and flow cytometry. The involvement of STUB1 in airway inflammation was determined in vivo by measuring lung inflammatory cells infiltration, mucus production, serum lgE levels, and alveolar macrophage M2 activation in STUB1−/− mice. STUB1 expression was evaluated in airway epithelium of patients with asthma and lung tissues of subjects with chronic obstructive pulmonary disease.
Measurements and Main Results: STUB1 interacted with IL-4Rα and targeted it for ubiquitination-mediated proteasomal degradation, terminating IL-4 or IL-13 signaling. STUB1 knockout cells showed increased levels of IL-4Rα and sustained STAT6 activation, whereas STUB1 overexpression reduced IL-4Rα levels. Mice deficient in STUB1 had spontaneous airway inflammation, alternative M2 activation of alveolar macrophage, and increased serum IgE. STUB1 levels were increased in airways of subjects with asthma or chronic obstructive pulmonary disease, suggesting that up-regulation of STUB1 might be an important feedback mechanism to dampen IL-4R signaling in airway inflammation.
Conclusions: Our study identified a previously uncharacterized role for STUB1 in regulating IL-4R signaling, which might provide a new strategy for attenuating airway inflammation.
IL-4R signaling; STUB1; airway inflammation
Recent discoveries indicate that disorders of protein folding and degradation play a particularly important role in the development of lung diseases and their associated complications. The overarching purpose of the National Heart, Lung, and Blood Institute workshop on “Malformed Protein Structure and Proteostasis in Lung Diseases” was to identify mechanistic and clinical research opportunities indicated by these recent discoveries in proteostasis science that will advance our molecular understanding of lung pathobiology and facilitate the development of new diagnostic and therapeutic strategies for the prevention and treatment of lung disease. The workshop's discussion focused on identifying gaps in scientific knowledge with respect to proteostasis and lung disease, discussing new research advances and opportunities in protein folding science, and highlighting novel technologies with potential therapeutic applications for diagnosis and treatment.
protein misfolding; post-translational processing; proteosome; ubiquitination; pulmonary health
Rationale: Current guidelines limit latent tuberculosis infection (LTBI)
evaluation to persons in the United States less than or equal to 5 years based on the
assumption that high TB rates among recent entrants are attributable to high LTBI
reactivation risk, which declines over time. We hypothesized that high postarrival TB
rates may instead be caused by imported active TB.
Objectives: Estimate reactivation and imported TB in an immigrant
Methods: We linked preimmigration records from a cohort of
California-bound Filipino immigrants during 2001–2010 with subsequent TB
reports. TB was likely LTBI reactivation if the immigrant had no evidence of active
TB at preimmigration examination, likely imported if preimmigration radiograph was
abnormal and TB was reported less than or equal to 6 months after arrival, and likely
reactivation of inactive TB if radiograph was abnormal but TB was reported more than
6 months after arrival.
Measurements and Main Results: Among 123,114 immigrants, 793 TB cases
were reported. Within 1 year of preimmigration examination, 85% of TB was imported; 6
and 9% were reactivation of LTBI and inactive TB, respectively. Conversely, during
Years 2–9 after U.S. entry, 76 and 24% were reactivation of LTBI and inactive
TB, respectively. The rate of LTBI reactivation (32 per 100,000) did not decline
during Years 1–9.
Conclusions: High postarrival TB rates were caused by detection of
imported TB through active postarrival surveillance. Among immigrants without active
TB at baseline, reported TB did not decline over 9 years, indicating sustained high
risk of LTBI reactivation. Revised guidelines should support LTBI screening and
treatment more than 5 years after U.S. arrival.
United States; epidemiology; emigrants and immigrants; guideline; public health