Rationale: Antibodies to influenza hemagglutinin
are the primary correlate of protection against infection. The strength and
persistence of this immune response influences viral evolution and consequently the
nature of influenza epidemics. However, the durability and immune determinants of
induction of humoral immunity after primary influenza infection remain unclear.
Objectives: The spread of a novel H1N1 (A[H1N1]pdm09) virus in 2009
through an unexposed population offered a natural experiment to assess the nature and
longevity of humoral immunity after a single primary influenza infection.
Methods: We followed A(H1N1)pdm09-seronegative adults through two
influenza seasons (2009–2011) as they developed A(H1N1)pdm09 influenza
infection or were vaccinated. Antibodies to A(H1N1)pdm09 virus were measured by
hemagglutination-inhibition assay in individuals with paired serum samples collected
preinfection and postinfection or vaccination to assess durability of humoral
immunity. Preexisting A(H1N1)pdm09-specific multicytokine-secreting CD4 and CD8 T
cells were quantified by multiparameter flow cytometry to test the hypothesis that
higher frequencies of CD4+ T-cell responses predict stronger antibody
induction after infection or vaccination.
Measurements and Main Results: Antibodies induced by natural infection
persisted at constant high titer for a minimum of approximately 15 months. Contrary
to our initial hypothesis, the fold increase in A(H1N1)pdm09-specific antibody titer
after infection was inversely correlated to the frequency of preexisting circulating
T cells (r = −0.4122;
P = 0.03).
Conclusions: The longevity of protective humoral immunity after
influenza infection has important implications for influenza transmission dynamics
and vaccination policy, and identification of its predictive cellular immune
correlate could guide vaccine development and evaluation.
pandemic influenza; immunology; antibodies; T cells; epidemiology
Rationale: Nocturnal asthma is a common presentation and is associated
with a more severe form of the disease. However, there are few epidemiologic studies
of nocturnal asthma, particularly in minority populations.
Objectives: To identify factors associated with nocturnal asthma,
including the contribution of self-identified race/ethnicity and genetic
Methods: The analysis included individuals from the Study for Asthma
Phenotypes and Pharmacogenomic Interactions by Race-ethnicity (SAPPHIRE) cohort.
Nocturnal asthma symptoms were assessed by questionnaire. Genome-wide genotype data
were used to estimate genetic ancestry in a subset of African American participants.
Logistic regression was used evaluate the association of various factors with
nocturnal asthma, such as self-identified race/ethnicity and genetic ancestry.
Measurement and Main Results: The study comprised 3,380 African American
and 1,818 European Americans individuals with asthma. After adjusting for other
potential explanatory variables, including controller medication use, African
Americans were more than twice as likely (odds ratio, 2.56; 95% confidence interval,
2.24–2.93) to report nocturnal asthma when compared with European American
individuals. Among the subset of African American participants with genome-wide
genotype data (n = 1,040), estimated proportion of African ancestry was also
associated with an increased risk of nocturnal asthma (P =
0.007). Differences in lung function explained a small, but statistically significant
(P = 0.02), proportion of the relationship between genetic
ancestry and nocturnal asthma symptoms.
Conclusions: Both self-identified race/ethnicity and African ancestry
appear to be independent predictors of nocturnal asthma. The mechanism by which
genetic ancestry contributes to population-level differences in nocturnal asthma
appears to be largely independent of lung function.
asthma; nocturnal symptoms; race/ethnicity; lung function; genetic ancestry
Pseudomonas aeruginosa undergoes phenotypic changes during cystic
fibrosis (CF) lung infection. Although mucoidy is traditionally associated with
transition to chronic infection, we hypothesized that additional in
vitro phenotypes correlate with this transition and contribute to
Objectives: To characterize the relationships between in vitro
P. aeruginosa phenotypes, infection stage, and clinical
Methods: A total of 649 children with CF and newly identified P.
aeruginosa were followed for a median 5.4 years during which a total of
2,594 P. aeruginosa isolates were collected. Twenty-six in
vitro bacterial phenotypes were assessed among the isolates, including
measures of motility, exoproduct production, colony morphology, growth, and
Measurements and Main Results:
P. aeruginosa phenotypes present at the time of culture were
associated with both stage of infection (new onset, intermittent, or chronic) and the
primary clinical outcome, occurrence of a pulmonary exacerbation (PE) in the
subsequent 2 years. Two in vitro P. aeruginosa phenotypes best
distinguished infection stages: pyoverdine production (31% of new-onset cultures, 48%
of intermittent, 69% of chronic) and reduced protease production (31%, 39%, and 65%,
respectively). The best P. aeruginosa phenotypic predictors of
subsequent occurrence of a PE were mucoidy (odds ratio, 1.75; 95% confidence
interval, 1.19–2.57) and reduced twitching motility (odds ratio, 1.43; 95%
confidence interval, 1.11–1.84).
Conclusions: In this large epidemiologic study of CF P.
aeruginosa adaptation, P. aeruginosa isolates exhibited
two in vitro phenotypes that best distinguished early and later
infection stages. Among the many phenotypes tested, mucoidy and reduced twitching
best predicted subsequent PE. These phenotypes indicate potentially useful prognostic
markers of transition to chronic infection and advancing lung disease.
epidemiology; risk factors; exacerbation; pulmonary function; mucoid Pseudomonas aeruginosa
Rationale: Cathepsin S (CTSS) activity is increased in bronchoalveolar
lavage (BAL) fluid from patients with cystic fibrosis (CF). This activity contributes
to lung inflammation via degradation of antimicrobial proteins, such as lactoferrin
and members of the β-defensin family.
Objectives: In this study, we investigated the hypothesis that airway
epithelial cells are a source of CTSS, and mechanisms underlying CTSS expression in
the CF lung.
Methods: Protease activity was determined using fluorogenic activity
assays. Protein and mRNA expression were analyzed by ELISA, Western blotting, and
reverse-transcriptase polymerase chain reaction.
Measurements and Main Results: In contrast to neutrophil elastase, CTSS
activity was detectable in 100% of CF BAL fluid samples from patients without
Pseudomonas aeruginosa infection. In this study, we identified
epithelial cells as a source of pulmonary CTSS activity with the demonstration that
CF airway epithelial cells express and secrete significantly more CTSS than non-CF
control cells in the absence of proinflammatory stimulation. Furthermore, levels of
the transcription factor IRF-1 correlated with increased levels of its target gene
CTSS. We discovered that miR-31, which is decreased in the CF airways, regulates
IRF-1 in CF epithelial cells. Treating CF bronchial epithelial cells with a miR-31
mimic decreased IRF-1 protein levels with concomitant knockdown of CTSS expression
Conclusions: The miR-31/IRF-1/CTSS pathway may play a functional role in
the pathogenesis of CF lung disease and may open up new avenues for exploration in
the search for an effective therapeutic target.
protease; microRNA; cystic fibrosis; epithelium
Rationale: Wnt/β-catenin signaling has been implicated in lung
fibrosis, but how this occurs and whether expression changes in Wnt pathway
components predict disease progression is unknown.
Objectives: To determine whether the Wnt coreceptor Lrp5 drives
pulmonary fibrosis in mice and is predictive of disease severity in humans.
Methods: We examined mice with impaired Wnt signaling caused by loss of
the Wnt coreceptor Lrp5 in models of lung fibrosis induced by
bleomycin or an adenovirus encoding an active form of transforming growth factor
(TGF)-β. We also analyzed gene expression in peripheral blood mononuclear cells
(PBMC) from patients with idiopathic pulmonary fibrosis (IPF).
Measurements and Main Results: In patients with IPF, analysis of
peripheral blood mononuclear cells revealed that elevation of positive regulators,
Lrp5 and 6, was independently associated with
disease progression. LRP5 was also associated with disease severity
at presentation in an additional cohort of patients with IPF. Lrp5
null mice were protected against bleomycin-induced pulmonary fibrosis, an effect that
was phenocopied by direct inhibition of β-catenin signaling by the small
molecular inhibitor of β-catenin responsive transcription. Transplantation of
Lrp5 null bone marrow cells into wild-type mice did not limit
fibrosis. Instead, Lrp5 loss was associated with reduced TGF-β
production by alveolar type 2 cells and leukocytes. Consistent with a role of Lrp5 in
the activation of TGF-β, Lrp5 null mice were not protected
against lung fibrosis induced by TGF-β.
Conclusions: We show that the Wnt coreceptor, Lrp5, is a genetic driver
of lung fibrosis in mice and a marker of disease progression and severity in humans
with IPF. Evidence that TGF-β signaling can override a loss in Lrp5 has
implications for patient selection and timing of Wnt pathway inhibitors in lung
lung fibrosis; Wnt/β-catenin signaling; peripheral blood mononuclear cell
Rationale: Ivacaftor is a cystic fibrosis transmembrane conductance
regulator (CFTR) potentiator recently approved for patients with CF age 6 and older
with the G551D mutation.
Objectives: To evaluate ivacaftor in a postapproval setting and
determine mechanism of action and response of clinically relevant markers.
Methods: We conducted a longitudinal cohort study in 2012–2013 in
G551D CF patients age 6 and older with no prior exposure to ivacaftor. Study
assessments were performed at baseline, 1, 3, and 6 months after ivacaftor
initiation. Substudies evaluated mucociliary clearance, β-adrenergic sweat
secretion rate, gastrointestinal pH, and sputum inflammation and microbiology
Measurements and Main Results: A total of 151 of 153 subjects were
prescribed ivacaftor and 88% completed the study through 6 months. FEV1 %
predicted improved from baseline to 6 months (mean absolute change, 6.7%;
P < 0.001). Similarly, body mass index improved from
baseline to 6 months (mean change, 0.8 kg/m2; P <
0.001). Sweat chloride decreased from baseline to 6 months (mean change, −53.8
mmol/L; 95% confidence interval, −57.7 to −49.9; P
< 0.001), reflecting augmented CFTR function. There was significant improvement
in hospitalization rate (P < 0.001) and Pseudomonas
aeruginosa burden (P < 0.01). Significant
improvements in mucociliary clearance (P < 0.001),
gastrointestinal pH (P = 0.001), and microbiome were also
observed, providing clinical mechanisms underlying the therapeutic benefit of
Conclusions: Significant clinical and physiologic improvements were
observed on initiation of ivacaftor in a broad patient population, including reduced
infection with P. aeruginosa. Biomarker studies substantially
improve the understanding of the mechanistic consequences of CFTR modulation on
pulmonary and gastrointestinal physiology.
cystic fibrosis; CFTR modulator; ivacaftor; Pseudomonas aeruginosa; pH
Rationale: HIV-1–induced interstitial pneumonitis (IP) is a serious complication of HIV-1 infection, characterized by inflammation and cellular infiltration in lungs, often leading to respiratory failure and death. The barrier function of the pulmonary endothelium is caused in part by tight junction (TJ) proteins, such as claudin-5. Peroxisome proliferator–activated receptor (PPAR)-γ is expressed in lung tissues and regulates inflammation. We hypothesize that HIV-1 induces vascular lung injury, and HIV-1–mediated damage of the pulmonary endothelium and IP is associated with dysregulation of PPAR-γ.
Objectives: Investigate the effects of HIV-1 infection on the pulmonary microvasculature and the modulatory effects of the PPAR-γ ligands.
Methods: Using human lung tissues, we demonstrated down-regulation of claudin-5 (marker of pulmonary barrier integrity), down-regulation of PPAR-γ transcription, and expression in lung tissues of HIV-1–infected humans with IP.
Measurements and Main Results: Human lung microvascular endothelial cells expressed the TJ proteins claudin-5, ZO-1, and ZO-2; HIV-1 decreased TJ proteins expression and induced nuclear factor-κB promoter activity, which was reversed by PPAR-γ agonist. Using two murine HIV/AIDS models, we demonstrated decreased claudin-5 expression and increased macrophage infiltration in the lungs of HIV-1–infected animals. Activation of PPAR-γ prevented HIV-1–induced claudin-5 down-regulation and significantly reduced viremia and pulmonary macrophage infiltration.
Conclusions: HIV-induced IP is associated with injury to the lung vascular endothelium, with decreased TJ and PPAR-γ expression, and increased pulmonary macrophage infiltration. PPAR-γ ligands abrogated these effects. Thus, regulation of PPAR-γ can be a therapeutic approach against HIV-1–induced vascular damage and IP in infected humans. Removal of Expression of Concern: Issues leading to the previous expression of concern for this article have been resolved after further revisions and editorial review. No further concerns exist.
pulmonary endothelium; tight junction proteins; HIV/AIDS; macrophages; PBMC
Rationale: Previous studies from our laboratory have shown that
peripheral blood mononuclear cells (PBMCs) from patients with chronic obstructive
pulmonary disease (COPD) prone to exacerbations with nontypeable Haemophilus
influenzae have impaired responses to lipoprotein P6. We hypothesized
that an underlying immunosuppressive network could be responsible for the defective
antibacterial immunity observed in these patients. We evaluated T regulatory cells
(Tregs), myeloid-derived suppressor cells (MDSC), and exhausted T effector cells
(programmed death 1 [PD-1]+) in patients with COPD, because these
cells are known to play a pivotal role in suppressing immune responses.
Objectives: We performed an in-depth characterization of Tregs, T
effector cells, and MDSC in COPD and correlated their levels and function with
Methods: Treg, effector T cell, and MDSC frequency from patients with
COPD and healthy subjects’ PBMCs were analyzed by flow cytometry. Treg
immunosuppressive capacity was measured by in vitro suppression
assay. The frequency of interferon-γ producing T cells and T-cell proliferation
were measured after blocking CTLA-4 and PD-1. Plasma proinflammatory and
immunosuppressive cytokine levels were measured.
Measurements and Main Results: Significantly increased levels of Tregs,
MDSC, and PD-1+ exhausted effector T cells were present in patients
with COPD compared with healthy subjects. Tregs from patients with COPD suppressed
P6-specific T-cell proliferation to a greater extent than Tregs from healthy
subjects. Plasma levels of Treg-generated cytokines, IL-10, and transforming growth
factor-β were elevated. Blockade of CTLA-4 resulted in significant augmentation
of T-cell IFN-γ production in patients with COPD.
Conclusions: Functionally suppressive Tregs, MDSCs, and exhausted
PD-1+ T cells contribute to effector T-cell dysfunction in
Foxp3+ Tregs; myeloid-derived suppressor cells; cytokines; lung function; T effector cells
Rationale: Chronic neutrophilic inflammation is a hallmark in the
pathogenesis of chronic obstructive pulmonary disease (COPD) and persists after
cigarette smoking has stopped. Mechanisms involved in this ongoing inflammatory
response have not been delineated.
Objectives: We investigated changes to the leukotriene A4
hydrolase (LTA4H)–proline-glycine-proline (PGP) pathway and chronic
inflammation in the development of COPD.
Methods: A/J mice were exposed to air or cigarette smoke for 22 weeks
followed by bronchoalveolar lavage and lung and cardiac tissue analysis. Two human
cohorts were used to analyze changes to the LTA4H–PGP pathway in
never smokers, control smokers, COPD smokers, and COPD former smokers. PGP/AcPGP and
LTA4H aminopeptidase activity were detected by mass spectroscopy,
LTA4H amounts were detected by ELISA, and acrolein was detected by
Measurements and Main Results: Mice exposed to cigarette smoke developed
emphysema with increased PGP, neutrophilic inflammation, and selective inhibition of
LTA4H aminopeptidase, which ordinarily degrades PGP. We recapitulated
these findings in smokers with and without COPD. PGP and AcPGP are closely associated
with cigarette smoke use. Once chronic inflammation is established, changes to
LTA4H aminopeptidase remain, even in the absence of ongoing cigarette
use. Acrolein modifies LTA4H and inhibits aminopeptidase activity to the
same extent as cigarette smoke.
Conclusions: These results demonstrate a novel pathway of aberrant
regulation of PGP/AcPGP, suggesting this inflammatory pathway may be intimately
involved in disease progression in the absence of ongoing cigarette smoke exposure.
We highlight a mechanism by which acrolein potentiates neutrophilic inflammation
through selective inhibition of LTA4H aminopeptidase activity.
Clinical trial registered with www.clinicaltrials.gov (NCT
COPD; inflammation; PGP; leukotriene A4 hydrolase; acrolein
Research in pulmonary transplantation is actively evolving in quality and scope to meet the challenges of a growing population of lung allograft recipients. In 2013, research groups leveraged large publicly available datasets in addition to multicenter research networks and single-center studies to make significant contributions to our knowledge and clinical care in the areas of donor use, clinical transplant outcomes, mechanisms of rejection, infectious complications, and chronic allograft dysfunction.
lung transplantation; donor; rejection; infection; bronchiolitis obliterans syndrome
Rationale: Hospitalizations for severe sepsis are common, and a growing
number of patients survive to hospital discharge. Nonetheless, little is known about
survivors’ post-discharge healthcare use.
Objectives: To measure inpatient healthcare use of severe sepsis
survivors compared with patients’ own presepsis resource use and the resource
use of survivors of otherwise similar nonsepsis hospitalizations.
Methods: This is an observational cohort study of survivors of severe
sepsis and nonsepsis hospitalizations identified from participants in the Health and
Retirement Study with linked Medicare claims, 1998–2005. We matched severe
sepsis and nonsepsis hospitalizations by demographics, comorbidity burden, premorbid
disability, hospitalization length, and intensive care use.
Measurements and Main Results: Using Medicare claims, we measured
patients’ use of inpatient facilities (hospitals, long-term acute care
hospitals, and skilled nursing facilities) in the 2 years surrounding
hospitalization. Severe sepsis survivors spent more days (median, 16 [interquartile
range, 3–45] vs. 7 [0–29]; P < 0.001) and a
higher proportion of days alive (median, 9.6% [interquartile range, 1.4–33.8%]
vs. 1.9% [0.0–7.9%]; P < 0.001) admitted to facilities
in the year after hospitalization, compared with the year prior. The increase in
facility-days was similar for nonsepsis hospitalizations. However, the severe sepsis
cohort experienced greater post-discharge mortality (44.2% [95% confidence interval,
41.3–47.2%] vs. 31.4% [95% confidence interval, 28.6–34.2%] at 1 year),
a steeper decline in days spent at home (difference-in-differences, −38.6 d
[95% confidence interval, −50.9 to 26.3]; P < 0.001),
and a greater increase in the proportion of days alive spent in a facility
(difference-in-differences, 5.4% [95% confidence interval, 2.8–8.1%];
P < 0.001).
Conclusions: Healthcare use is markedly elevated after severe sepsis,
and post-discharge management may be an opportunity to reduce resource use.
patient outcomes assessment; hospitalization; patient readmission; skilled nursing facility; healthcare facilities
Rationale: Whether allergic airway inflammation mediates the association between overweight or obesity and childhood asthma is unknown.
Objectives: To examine adiposity, asthma, and fractional exhaled nitric oxide (FeNO) in U.S. children.
Methods: Cross-sectional study of indicators of adiposity or obesity, FeNO (a biomarker of eosinophilic airway inflammation), and asthma in 2,681 children aged 6–17 years in the 2007–2010 National Health and Nutrition Examination Survey. Adiposity measures included body mass index (BMI), percent body fat (PBF), and waist circumference (WC).
Measurements and Main Results: BMI, PBF, and WC were associated with asthma among children with low FeNO (odds ratio, 1.54–1.68; P < 0.01), but not among children with increased FeNO. Among children without asthma, BMI, PBF, and WC were associated with higher FEV1 and FVC, and lower FEV1/FVC. Among children with asthma and a high FeNO, all adiposity indicators were associated with decreased FEV1/FVC (β = −1.5% to −1.7% per z score) but not with FEV1 or FVC. Higher BMI or PBF was associated with worse asthma severity or control in children with asthma and increased FeNO, but not in children with asthma and low FeNO. Similar results were obtained in a secondary multivariate analysis of overweight or obesity (defined as BMI ≥85th percentile) and asthma or indicators of asthma severity or control, stratified by FeNO level.
Conclusions: Adiposity indicators are associated with asthma in children with low FeNO. Among children with asthma, adiposity indicators are associated with worse asthma severity or control in those with high FeNO.
asthma; airway inflammation; adiposity; obesity; NHANES
Rationale: Marked socioeconomic health-care disparities are recognized
in India, but lung health inequalities between urban and rural children have not been
Objectives: We investigated whether differences exist in spirometric
pulmonary function in healthy children across the Indian urban–rural continuum
and compared results with those from Indian children living in the UK.
Methods: Indian children aged 5 to 12 years were recruited from Indian
urban, semiurban, and rural schools, and as part of the Size and Lung Function in
Children study, London. Anthropometric and spirometric assessments were
Measurements and Main Results: Acceptable spirometric data were obtained
from 728 (58% boys) children in India and 311 (50% boys) UK-Indian children. As an
entire group, the India-resident children had significantly lower z
FEV1 and z FVC than UK-Indian children
(P < 0.0005), when expressed using Global Lung
Function Initiative–2012 equations. However, when India-resident children were
categorized according to residence, there were no differences in z
FEV1 and z FVC between Indian-urban and UK-Indian
children. There were, however, significant reductions of ∼0.5
z scores and 0.9 z scores in both
FEV1 and FVC (with no difference in FEV1/FVC) in
Indian-semiurban and Indian-rural children, respectively, when compared with
Indian-urban children (P < 0.0005).
z Body mass index, socioeconomic circumstances, tobacco, and
biomass exposure were individually significantly associated with z
FEV1 and z FVC
(P < 0.0005).
Conclusions: The presence of an urban–rural continuum of lung
function within a specific ethnic group emphasizes the impact of environmental
factors on lung growth in emerging nations such as India, which must be taken into
account when developing ethnic-specific reference values or designing studies to
optimize lung health.
children; urban; rural; socioeconomic circumstances; ethnic differences in lung function
Rationale: Guidelines recommend routine nucleic-acid amplification testing in patients with presumed tuberculosis (TB), but these tests have not been widely adopted. GeneXpert MTB/RIF (Xpert), a novel, semiautomated TB nucleic-acid amplification test, has renewed interest in this technology, but data from low-burden countries are limited.
Objectives: We sought to estimate Xpert’s potential clinical and public health impact on empiric treatment, contact investigation, and housing in patients undergoing TB evaluation.
Methods: We performed a prospective, cross-sectional study with 2-month follow-up comparing Xpert with standard strategies for evaluating outpatients for active pulmonary TB at the San Francisco Department of Public Health TB Clinic between May 2010 and June 2011. We calculated the diagnostic accuracy of standard algorithms for initial empiric TB treatment, contact investigation, and housing in reference to three Mycobacterium tuberculosis sputum cultures, as compared with that of a single sputum Xpert test. We estimated the incremental diagnostic value of Xpert, and the hypothetical reductions in unnecessary treatment, contact investigation, and housing if Xpert were adopted to guide management decisions.
Measurements and Main Results: A total of 156 patients underwent Xpert testing. Fifty-nine (38%) received empiric TB treatment. Thirteen (8%) had culture-positive TB. Xpert-guided management would have hypothetically decreased overtreatment by 94%, eliminating a median of 44 overtreatment days (interquartile range, 43–47) per patient and 2,169 total overtreatment days (95% confidence interval, 1,938–2,400) annually, without reducing early detection of TB patients. We projected similar benefits for contact investigation and housing.
Conclusions: Xpert could greatly reduce the frequency and impact of unnecessary empiric treatment, contact investigation, and housing, providing substantial patient and programmatic benefits if used in management decisions.
tuberculosis; diagnosis; health care quality assurance; operations research; public health
Lower respiratory tract infections (LRTIs) are a persistent and pervasive public health problem worldwide. Pneumonia and other LRTIs will be among the leading causes of death in adults, and pneumonia is the single largest cause of death in children. LRTIs are also an important cause of acute lung injury and acute exacerbations of chronic obstructive pulmonary disease. Because innate immunity is the first line of defense against pathogens, understanding the role of innate immunity in the pulmonary system is of paramount importance. Pattern recognition molecules (PRMs) that recognize microbial-associated molecular patterns are an integral component of the innate immune system and are located in both cell membranes and cytosol. Toll-like receptors and nucleotide-binding oligomerization domain–like receptors (NLRs) are the major sensors at the forefront of pathogen recognition. Although Toll-like receptors have been extensively studied in host immunity, NLRs have diverse and important roles in immune and inflammatory responses, ranging from antimicrobial properties to adaptive immune responses. The lung contains NLR-expressing immune cells such as leukocytes and nonimmune cells such as epithelial cells that are in constant and close contact with invading microbes. This pulmonary perspective addresses our current understanding of the structure and function of NLR family members, highlighting advances and gaps in knowledge, with a specific focus on immune responses in the respiratory tract during bacterial infection. Further advances in exploring cellular and molecular responses to bacterial pathogens are critical to develop improved strategies to treat and prevent devastating infectious diseases of the lung.
lung; bacterial infection; nucleotide-binding oligomerization domain–like receptors; inflammasome