Rationale: HIV–tuberculosis-associated immune reconstitution inflammatory syndrome (TB-IRIS) is an immunopathological reaction to mycobacterial antigens induced by antiretroviral therapy. Prednisone reduces morbidity in TB-IRIS, but the mechanisms are unclear.
Objectives: To determine the effect of prednisone on the inflammatory response in TB-IRIS (antigen-specific effector T cells, cytokines, and chemokines).
Methods: Blood was taken from participants in a randomized placebo-controlled trial of prednisone for TB-IRIS, at 0, 2, and 4 weeks. Participants received prednisone at a dosage of 1.5 mg/kg/day for 2 weeks followed by 0.75 mg/kg/day for 2 weeks, or placebo at identical dosages.
Measurements and Main Results: Analyses included IFN-γ enzyme-linked immunospot (ELISPOT), reverse transcription-polymerase chain reaction on peripheral blood mononuclear cells after restimulation with heat-killed Mycobacterium tuberculosis, Luminex multiplex cytokine analysis of corresponding tissue culture supernatants, and Luminex multiplex cytokine analysis of serum. Fifty-eight participants with TB-IRIS (31 receiving prednisone, 27 receiving placebo) were included. In serum, significant decreases in IL-6, IL-10, IL-12 p40, tumor necrosis factor-α, IFN-γ, and IFN-γ–induced protein-10 concentrations during prednisone, but not placebo, treatment were observed. No differences in ELISPOT responses comparing prednisone and placebo groups were shown in response to ESAT-6 (early secreted antigen target-6), Acr1, Acr2, 38-kD antigen, or heat-killed H37Rv M. tuberculosis. Purified protein derivative ELISPOT responses increased over 4 weeks in the prednisone group and decreased in the placebo group (P = 0.007).
Conclusions: The beneficial effects of prednisone in TB-IRIS appear to be mediated via suppression of predominantly proinflammatory cytokine responses of innate immune origin, not via a reduction of the numbers of antigen-specific T cells in peripheral blood.
human immunodeficiency virus; tuberculosis; immune reconstitution inflammatory syndrome; glucocorticoids
Rationale: Interferon-γ (IFN-γ) release assays are widely used to diagnose latent infection with Mycobacterium tuberculosis in adults, but their performance in children remains incompletely evaluated to date.
Objectives: To investigate factors influencing results of IFN-γ release assays in children using a large European data set.
Methods: The Pediatric Tuberculosis Network European Trials group pooled and analyzed data from five sites across Europe comprising 1,128 children who were all investigated for latent tuberculosis infection by tuberculin skin test and at least one IFN-γ release assay. Multivariate analyses examined age, bacillus Calmette-Guérin (BCG) vaccination status, and sex as predictor variables of results. Subgroup analyses included children who were household contacts.
Measurements and Main Results: A total of 1,093 children had a QuantiFERON-TB Gold In-Tube assay and 382 had a T-SPOT.TB IFN-γ release assay. Age was positively correlated with a positive blood result (QuantiFERON-TB Gold In-Tube: odds ratio [OR], 1.08 per year increasing age [P < 0.0001]; T-SPOT.TB: OR, 1.14 per year increasing age [P < 0.001]). A positive QuantiFERON-TB Gold In-Tube result was shown by 5.5% of children with a tuberculin skin test result less than 5 mm, by 14.8% if less than 10 mm, and by 20.2% if less than 15 mm. Prior BCG vaccination was associated with a negative IFN-γ release assay result (QuantiFERON-TB Gold In-Tube: OR, 0.41 [P < 0.001]; T-SPOT.TB: OR, 0.41 [P < 0.001]). Young age was a predictor of indeterminate IFN-γ release assay results, but indeterminate rates were low (3.6% in children < 5 yr, 1% in children > 5 yr).
Conclusions: Our data show that BCG vaccination may be effective in protecting children against Mycobacterium tuberculosis infection. To restrict use of IFN-γ release assays to children with positive skin tests risks underestimating latent infection.
interferon-γ release tests; latent tuberculosis; BCG vaccine; pediatrics
Rationale: Lymphocytes have been shown to facilitate systemic inflammation and physiologic dysfunction in experimental models of severe sepsis. Our previous studies show that natural killer (NK) cells migrate into the peritoneal cavity during intraabdominal sepsis, but the trafficking of NKT and T lymphocytes has not been determined. The factors that regulate lymphocyte trafficking during sepsis are currently unknown.
Objectives: To ascertain the importance of CXC chemokine receptor 3 (CXCR3) as a regulator of lymphocyte trafficking during sepsis and determine the contribution of CXCR3-mediated lymphocyte trafficking to the pathogenesis of septic shock.
Methods: Lymphocyte trafficking was evaluated in control and CXCR3-deficient mice using flow cytometry during sepsis caused by cecal ligation and puncture (CLP). Survival, core temperature, cytokine production, and bacterial clearance were measured as pathobiological endpoints.
Measurements and Main Results: This study shows that concentrations of the CXCR3 ligands CXCL9 (monokine induced by interferon γ, MIG) and CXCL10 (interferon γ–induced protein 10, IP-10) increase in plasma and the peritoneal cavity after CLP, peak at 8 hours after infection, and are higher in the peritoneal cavity than in plasma. The numbers of CXCR3+ NK cells progressively decreased in spleen after CLP with a concomitant increase within the peritoneal cavity, a pattern that was ablated in CXCR3-deficient mice. CXCR3-dependent recruitment of T cells was also evident at 16 hours after CLP. Treatment of mice with anti-CXCR3 significantly attenuated CLP-induced hypothermia, decreased systemic cytokine production, and improved survival.
Conclusions: CXCR3 regulates NK- and T-cell trafficking during sepsis and blockade of CXCR3 attenuates the pathogenesis of septic shock.
septic shock; natural killer cells; T cells; natural killer T cells
Rationale: Low blood levels of 25-hydroxyvitamin D (25[OH]D) have been associated with a higher risk of respiratory infections in general populations and higher risk of exacerbations of lung disease in people with asthma. We hypothesized that low blood levels of 25(OH)D in patients with chronic obstructive pulmonary disease (COPD) would be associated with an increased risk of acute exacerbations of COPD (AECOPD).
Objectives: To determine if baseline 25(OH)D levels relate to subsequent AECOPD in a cohort of patients at high risk for AECOPD.
Methods: Plasma 25(OH)D was measured at baseline in 973 participants on entry to a 1-year study designed to determine if daily azithromycin decreased the incidence of AECOPD. Relationships between baseline 25(OH)D and AECOPD over 1 year were analyzed with time to first AECOPD as the primary outcome and exacerbation rate as the secondary outcome.
Measurements and Main Results: In this largely white (85%) sample of North American patients with severe COPD (mean FEV1 1.12L; 40% of predicted), mean 25(OH)D was 25.7 ± 12.8 ng/ml. A total of 33.1% of participants were vitamin D insufficient (≥20 ng/ml but <30 ng/ml); 32% were vitamin D deficient (<20 ng/ml); and 8.4% had severe vitamin D deficiency (<10 ng/ml). Baseline 25(OH)D levels had no relationship to time to first AECOPD or AECOPD rates.
Conclusions: In patients with severe COPD, baseline 25(OH)D levels are not predictive of subsequent AECOPD.
Clinical trial registered with www.clinicaltrials.gov (NCT00119860).
chronic obstructive pulmonary disease; vitamin D; exacerbations
Rationale: Aeroallergen sensitization and virus-induced wheezing are risk factors for asthma development during early childhood, but the temporal developmental sequence between them is incompletely understood.
Objective: To define the developmental relationship between aeroallergen sensitization and virus-induced wheezing.
Methods: A total of 285 children at high risk for allergic disease and asthma were followed prospectively from birth. The timing and etiology of viral respiratory wheezing illnesses were determined, and aeroallergen sensitization was assessed annually for the first 6 years of life. The relationships between these events were assessed using a longitudinal multistate Markov model.
Measurements and Main Results: Children who were sensitized to aeroallergens had greater risk of developing viral wheeze than nonsensitized children (hazard ratio [HR], 1.9; 95% confidence interval [CI], 1.2–3.1). Allergic sensitization led to an increased risk of wheezing illnesses caused by human rhinovirus (HRV) but not respiratory syncytial virus. The absolute risk of sensitized children developing viral wheeze was greatest at 1 year of age; however, the relative risk was consistently increased at every age assessed. In contrast, viral wheeze did not lead to increased risk of subsequent allergic sensitization (HR, 0.76; 95% CI, 0.50–1.1).
Conclusions: Prospective, repeated characterization of a birth cohort demonstrated that allergic sensitization precedes HRV wheezing and that the converse is not true. This sequential relationship and the plausible mechanisms by which allergic sensitization can lead to more severe HRV-induced lower respiratory illnesses support a causal role for allergic sensitization in this developmental pathway. Therefore, therapeutics aimed at preventing allergic sensitization may modify virus-induced wheezing and the development of asthma.
virus; wheezing; allergic sensitization; RSV; human rhinovirus
Background: Pediatric obstructive sleep apnea (OSA) leads to multiple end-organ morbidities that are mediated by the cumulative burden of oxidative stress and inflammation. Because not all children with OSA exhibit increased systemic inflammation, genetic and environmental factors may be affecting patterns of DNA methylation in genes subserving inflammatory functions.
Methods: DNA from matched children with OSA with and without high levels of high-sensitivity C-reactive protein (hsCRP) were assessed for DNA methylation levels of 24 inflammatory-related genes. Primer-based polymerase chain reaction assays in a case-control setting involving 47 OSA cases and 31 control subjects were conducted to confirm the findings; hsCRP and myeloid-related protein (MRP) 8/14 levels were also assayed.
Measurements and Main Results: Forkhead box P3 (FOXP3) and interferon regulatory factor 1 (IRF1) showed higher methylation in six children with OSA and high hsCRP levels compared with matched children with OSA and low hsCRP levels (P < 0.05). In the case-control cohort, children with OSA and high CRP levels had higher log FOXP3 DNA methylation levels compared with children with OSA and low CRP levels and control subjects. IRF1 did not exhibit significant differences. FOXP3 DNA methylation levels correlated with hsCRP and MRP 8/14 levels and with apnea-hypopnea index (AHI), BMI z score, and apolipoprotein B levels. A stepwise multiple regression model showed that AHI was independently associated with FOXP3 DNA methylation levels (P < 0.03).
Conclusions: The FOXP3 gene, which regulates expression of T regulatory lymphocytes, is more likely to display increased methylation among children with OSA who exhibit increased systemic inflammatory responses. Thus, epigenetic modifications may constitute an important determinant of inflammatory phenotype in OSA, and FOXP3 DNA methylation levels may provide a potential biomarker for end-organ vulnerability.
obstructive sleep apnea; epigenetics; DNA methylation; T regulatory lymphocytes; inflammation
Rationale: Controversy persists regarding the presence and importance of hypoglossal nerve dysfunction in obstructive sleep apnea (OSA).
Objectives: We assessed quantitative parameters related to motor unit potential (MUP) morphology derived from electromyographic (EMG) signals in patients with OSA versus control subjects and hypothesized that signs of neurogenic remodeling would be present in the patients with OSA.
Methods: Participants underwent diagnostic sleep studies to obtain apnea–hypopnea indices. Muscle activity was detected with 50-mm concentric needle electrodes. The concentric needle was positioned at more than 10 independent sites per subject, after the local anatomy of the upper airway musculature was examined by ultrasonography. All activity was quantified with subjects awake, during supine eupneic breathing while wearing a nasal mask connected to a pneumotachograph. Genioglossus EMG signals were analyzed offline by automated software (DQEMG), which extracted motor unit potential trains (MUPTs) contributed by individual motor units from the composite EMG signals. Quantitative measurements of MUP templates, including duration, peak-to-peak amplitude, area, area-to-amplitude ratio, and size index, were compared between the untreated patients with OSA and healthy control subjects.
Measurements and Main Results: A total of 1,655 MUPTs from patients with OSA (n = 17; AHI, 55 ± 6/h) and control subjects (n = 14; AHI, 4 ± 1/h) were extracted from the genioglossus muscle EMG signals. MUP peak-to-peak amplitudes in the patients with OSA were not different compared with the control subjects (397.5 ± 9.0 vs. 382.5 ± 10.0 μV). However, the MUPs of the patients with OSA were longer in duration (11.5 ± 0.1 vs. 10.3 ± 0.1 ms; P < 0.001) and had a larger size index (4.09 ± 0.02 vs. 3.92 ± 0.02; P < 0.001) compared with control subjects.
Conclusions: These results confirm and quantify the extent and existence of structural neural remodeling in OSA.
motor unit; respiration; tongue; genioglossus; respiratory
This perspective highlights advances in the understanding of the role of cellular metabolism in the pathogenesis of pulmonary hypertension. Insights gained in the past 20 years have revealed several similarities between the cellular processes underlying the pulmonary vascular remodeling in pulmonary hypertension and those seen in cancer processes. In line with these insights, there is increasing recognition that abnormal cellular metabolism, notably of aerobic glycolysis (the “Warburg effect”), the potential involvement of hypoxia-inducible factor in this process, and alterations in mitochondrial function, are key elements in the pathogenesis of this disease. The glycolytic shift may underlie the resistance to apoptosis and increased vascular cell proliferation, which are hallmarks of pulmonary hypertension. These investigations have led to novel approaches in the diagnosis and therapy of pulmonary hypertension.
glycolytic shift; hypoxia-inducible factor; fatty acid oxidation; right ventricular hypertrophy; pulmonary hypertension
Rationale: Patients with isolated mediastinal lymphadenopathy (IML) are a common presentation to physicians, and mediastinoscopy is traditionally considered the “gold standard” investigation when a pathological diagnosis is required. Endobronchial ultrasound–guided transbronchial needle aspiration (EBUS-TBNA) is established as an alternative to mediastinoscopy in patients with lung cancer.
Objective: To determine the efficacy and health care costs of EBUS-TBNA as an alternative initial investigation to mediastinoscopy in patients with isolated IML.
Methods: Prospective multicenter single-arm clinical trial of 77 consecutive patients with IML from 5 centers between April 2009 and March 2011. All patients underwent EBUS-TBNA. If EBUS-TBNA did not provide a diagnosis, then participants underwent mediastinoscopy.
Measurements and Main Results: EBUS-TBNA prevented 87% of mediastinoscopies (95% confidence interval [CI], 77–94%; P < 0.001) but failed to provide a diagnosis in 10 patients (13%), all of whom underwent mediastinoscopy. The sensitivity and negative predictive value of EBUS-TBNA in patients with IML were 92% (95% CI, 83–95%) and 40% (95% CI, 12–74%), respectively. One patient developed a lower respiratory tract infection after EBUS-TBNA, requiring inpatient admission. The cost of the EBUS-TBNA procedure per patient was £1,382 ($2,190). The mean cost of the EBUS-TBNA strategy was £1,892 ($2,998) per patient, whereas a strategy of mediastinoscopy alone was significantly more costly at £3,228 ($5,115) per patient (P < 0.001). The EBUS-TBNA strategy is less costly than mediastinoscopy if the cost per EBUS-TBNA procedure is less than £2,718 ($4,307) per patient.
Conclusions: EBUS-TBNA is a safe, highly sensitive, and cost-saving initial investigation in patients with IML.
Clinical trial registered with ClinicalTrials.gov (NCT00932854).
endobronchial ultrasound; mediastinal lymphadenopathy; sarcoidosis; tuberculosis; lymphoma
Rationale: The patterns and outcomes of noninvasive, positive-pressure ventilation (NIPPV) use in patients hospitalized for acute exacerbations of chronic obstructive pulmonary disease (COPD) nationwide are unknown.
Objectives: To determine the prevalence and trends of noninvasive ventilation for acute COPD.
Methods: We used data from the Healthcare Cost and Utilization Project's Nationwide Inpatient Sample to assess the pattern and outcomes of NIPPV use for acute exacerbations of COPD from 1998 to 2008.
Measurements and Main Results: An estimated 7,511,267 admissions for acute exacerbations occurred from 1998 to 2008. There was a 462% increase in NIPPV use (from 1.0 to 4.5% of all admissions) and a 42% decline in invasive mechanical ventilation (IMV) use (from 6.0 to 3.5% of all admissions) during these years. This was accompanied by an increase in the size of a small cohort of patients requiring transition from NIPPV to IMV. In-hospital mortality in this group appeared to be worsening over time. By 2008, these patients had a high mortality rate (29.3%), which represented 61% higher odds of death compared with patients directly placed on IMV (95% confidence interval, 24–109%) and 677% greater odds of death compared with patients treated with NIPPV alone (95% confidence interval, 475–948%). With the exception of patients transitioned from NIPPV to IMV, in-hospital outcomes were favorable and improved steadily year by year.
Conclusions: The use of NIPPV has increased significantly over time among patients hospitalized for acute exacerbations of COPD, whereas the need for intubation and in-hospital mortality has declined. However, the rising mortality rate in a small but expanding group of patients requiring invasive mechanical ventilation after treatment with noninvasive ventilation needs further investigation.
COPD; positive-pressure ventilation; artificial respiration; epidemiology
Vitamin D deficiency and asthma are common conditions that share risk factors such as African American ethnicity, inner-city residence, and obesity. This review provides a critical examination of current experimental and epidemiologic evidence of a causal association between vitamin D status and asthma or asthma morbidity, including potential protective mechanisms such as antiviral effects and enhanced steroid responsiveness. Because most published epidemiologic studies of vitamin D and asthma or asthma morbidity are observational, a recommendation for or against vitamin D supplementation as preventive or secondary treatment for asthma is not advisable and must await results of ongoing clinical trials. Should these trials confirm a beneficial effect of vitamin D, others will be needed to assess the role of vitamin D supplementation to prevent or treat asthma in different groups such as infants, children of school age, and ethnic minorities.
vitamin D; asthma; asthma morbidity
Rationale: The immunologic events surrounding primary Mycobacterium tuberculosis infection and development of tuberculosis remain controversial. Young children who develop tuberculosis do so quickly after first exposure, thus permitting study of immune response to primary infection and disease. We hypothesized that M. tuberculosis–specific CD8+ T cells are generated in response to high bacillary loads occurring during tuberculosis.
Objectives: To determine if M. tuberculosis–specific T cells are generated among healthy children exposed to M. tuberculosis and children with tuberculosis.
Methods: Enzyme-linked immunosorbent spot assays were used to measure IFN-γ production in response to M. tuberculosis–specific proteins ESAT-6/CFP-10 by peripheral blood mononuclear cells and CD8+ T cells isolated from Ugandan children hospitalized with tuberculosis (n = 96) or healthy tuberculosis contacts (n = 62).
Measurements and Main Results: The proportion of positive CD8+ T-cell assays and magnitude of CD8+ T-cell responses were significantly greater among young (<5 yr) tuberculosis cases compared with young contacts (P = 0.02, Fisher exact test, P = 0.01, Wilcoxon rank-sum, respectively). M. tuberculosis–specific T-cell responses measured in peripheral blood mononuclear cells were equivalent between groups.
Conclusions: Among young children, M. tuberculosis–specific CD8+ T cells develop in response to high bacillary loads, as occurs during tuberculosis, and are unlikely to be found after M. tuberculosis exposure. T-cell responses measured in peripheral blood mononuclear cells are generated after M. tuberculosis exposure alone, and thus cannot distinguish exposure from disease. In young children, IFN-γ–producing M. tuberculosis–specific CD8+ T cells provide an immunologic signature of primary M. tuberculosis infection resulting in disease.
Mycobacterium tuberculosis; infant; child; CD8-positive T lymphocytes; enzyme-linked immunosorbent spot
Rationale: Academic success involves the ability to use cognitive skills in a school environment. Poor academic performance has been linked to disrupted sleep associated with sleep-disordered breathing (SDB). In parallel, poor sleep is associated with increased risk for obesity, and weight management problems have been linked to executive dysfunction, suggesting that interactions may be operational between SDB and obesity to adversely affect neurocognitive outcomes.
Objectives: To test whether mediator relationships exist between body weight, SDB, and cognition.
Methods: Structural equation modeling was conducted on data from 351 children in a community-based cohort assessed with the core subtests of the Differential Abilities Scales after an overnight polysomnogram. Body mass index, apnea–hypopnea index, and cognitive abilities were modeled as latent constructs.
Measurements and Main Results: In a sample of predominantly white children 6 to 10 years of age, SDB amplified the adverse cognitive and weight outcomes by 0.55- to 0.46-fold, respectively. Weight amplified the risk by 0.39- to 0.40-fold for SDB and cognitive outcomes, respectively. Poor ability to perform complex mental processing functions increased the risk of adverse weight and SDB outcomes by 2.9- and 7.9-fold, respectively.
Conclusions: Cognitive functioning in children is adversely affected by frequent health-related problems, such as obesity and SDB. Furthermore, poorer integrative mental processing may place a child at a bigger risk for adverse health outcomes.
sleep-disordered breathing; weight; BMI; cognition; verbal abilities
Rationale: Diesel exhaust enhances allergic inflammation, and pollutants are associated with heightened susceptibility to viral respiratory infections. The effects of combined diesel and virus exposure in humans are unknown.
Objectives: Test whether acute exposure to diesel modifies inflammatory responses to influenza virus in normal humans and those with allergies.
Methods: We conducted a double-blind, randomized, placebo-controlled study of nasal responses to live attenuated influenza virus in normal volunteers and those with allergic rhinitis exposed to diesel (100 μg/m3) or clean air for 2 hours, followed by standard dose of virus and serial nasal lavages. Endpoints were inflammatory mediators (ELISA) and virus quantity (quantitative reverse-transcriptase polymerase chain reaction). To test for exposure effect, we used multiple regression with exposure group (diesel vs. air) as the main explanatory variable and allergic status as an additional factor.
Measurements and Main Results: Baseline levels of mediators did not differ among groups. For most postvirus nasal cytokine responses, there was no significant diesel effect, and no significant interaction with allergy. However, diesel was associated with significantly increased IFN-γ responses (P = 0.02), with no interaction with allergy in the regression model. Eotaxin-1 (P = 0.01), eosinophil cationic protein (P < 0.01), and influenza RNA sequences in nasal cells (P = 0.03) were significantly increased with diesel exposure, linked to allergy.
Conclusions: Short-term exposure to diesel exhaust leads to increased eosinophil activation and increased virus quantity after virus inoculation in those with allergic rhinitis. This is consistent with previous literature suggesting a diesel “adjuvant” effect promoting allergic inflammation, and our data further suggest this change may be associated with reduced virus clearance.
Clinical trial registered with www.clinicaltrials.gov (NCT00617110).
diesel; influenza; eosinophil cationic protein; eotaxin-1; interferon-γ
Rationale: Fosfomycin/tobramycin for inhalation (FTI), a unique, broad-spectrum antibiotic combination, may have therapeutic potential for patients with cystic fibrosis (CF).
Objectives: To evaluate safety and efficacy of FTI (160/40 mg or 80/20 mg), administered twice daily for 28 days versus placebo, in patients greater than or equal to 18 years of age, with CF, chronic Pseudomonas aeruginosa (PA) airway infection, and FEV1 greater than or equal to 25% and less than or equal to 75% predicted.
Methods: This double-blind, placebo-controlled, multicenter study assessed whether FTI/placebo maintained FEV1 % predicted improvements achieved following a 28-day, open-label, run-in course of aztreonam for inhalation solution (AZLI).
Measurements and Main Results: A total of 119 patients were randomized to FTI (160/40 mg: n = 41; 80/20 mg: n = 38) or placebo (n = 40). Mean age was 32 years and mean FEV1 was 49% predicted at screening. Relative improvements in FEV1 % predicted achieved by the AZLI run-in were maintained in FTI groups compared with placebo (160/40 mg vs. placebo: 6.2% treatment difference favoring FTI, P = 0.002 [primary endpoint]; 80/20 mg vs. placebo: 7.5% treatment difference favoring FTI, P < 0.001). The treatment effect on mean PA sputum density was statistically significant for the FTI 80/20 mg group versus placebo (−1.04 log10
PA colony-forming units/g sputum difference, favoring FTI; P = 0.01). Adverse events, primarily cough, were consistent with CF disease. Respiratory events, including dyspnea and wheezing, were less common with FTI 80/20 mg than FTI 160/40 mg. No clinically significant differences between groups were reported for laboratory values.
Conclusions: FTI maintained the substantial improvements in FEV1 % predicted achieved during the AZLI run-in and was well tolerated. FTI is a promising antipseudomonal therapy for patients with CF.
Pseudomonas aeruginosa; fosfomycin; tobramycin; inhaled antibiotics; FTI
Rationale: Donor mesenchymal stromal/stem cell (MSC) expansion and fibrotic differentiation is associated with development of bronchiolitis obliterans syndrome (BOS) in human lung allografts. However, the regulators of fibrotic differentiation of these resident mesenchymal cells are not well understood.
Objectives: This study examines the role of endogenous and exogenous prostaglandin (PG)E2 as a modulator of fibrotic differentiation of human lung allograft-derived MSCs.
Methods: Effect of PGE2 on proliferation, collagen secretion, and α-smooth muscle actin (α-SMA) expression was assessed in lung-resident MSCs (LR-MSCs) derived from patients with and without BOS. The response pathway involved was elucidated by use of specific agonists and antagonists.
Measurement and Main Results: PGE2 treatment of LR-MSCs derived from normal lung allografts significantly inhibited their proliferation, collagen secretion, and α-SMA expression. On the basis of pharmacologic and small-interfering RNA approaches, a PGE2/E prostanoid (EP)2/adenylate cyclase pathway was implicated in these suppressive effects. Stimulation of endogenous PGE2 secretion by IL-1β was associated with amelioration of their myofibroblast differentiation in vitro, whereas its inhibition by indomethacin augmented α-SMA expression. LR-MSCs from patients with BOS secreted significantly less PGE2 than non-BOS LR-MSCs. Furthermore, BOS LR-MSCs were found to be defective in their ability to induce cyclooxygenase-2, and therefore unable to up-regulate PGE2 synthesis in response to IL-1β. BOS LR-MSCs also demonstrated resistance to the inhibitory actions of PGE2 in association with a reduction in the EP2/EP1 ratio.
Conclusions: These data identify the PGE2 axis as an important autocrine–paracrine brake on fibrotic differentiation of LR-MSCs, a failure of which is associated with BOS.
mesenchymal stem cell; bronchiolitis obliterans syndrome; lung transplant; prostaglandin E2
Rationale: Idiopathic pulmonary fibrosis (IPF) is a lethal lung disease of unknown etiology with a variable and unpredictable course.
Objectives: The aim of this study was to identify and validate plasma proteins that are predictive of outcome in IPF.
Methods: Plasma samples were available for 241 patients with IPF (140 derivation and 101 validation). In the derivation cohort, concentrations of 92 proteins were analyzed using a multiplex bead-based immunoassay and concentrations of matrix metalloproteinase (MMP)-7, MMP-1, and surfactant protein D were assessed by ELISA. In the validation cohort concentrations of intercellular adhesion molecule (ICAM)-1, IL-8, and vascular cell adhesion molecule (VCAM)-1 were assessed by bead-based multiplex assay, and S100A12 and MMP-7 by ELISA. Associations of biomarkers with mortality, transplant-free survival, and disease progression were tested in the derivation and validation cohorts using nonparametric methods of survival analysis and the Cox proportional hazards model, and an integrated risk prediction score was derived and tested.
Measurements and Main Results: High concentrations of MMP-7, ICAM-1, IL-8, VCAM-1, and S100A12 predicted poor overall survival, poor transplant-free survival, and poor progression-free survival in the derivation cohort. In the independent validation cohort high concentrations of all five were predictive of poor transplant-free survival; MMP-7, ICAM-1, and IL-8 of overall survival; and ICAM-1 of poor progression-free survival. The personal clinical and molecular mortality prediction index derived in the derivation cohort was highly predictive of mortality in the validation cohort.
Conclusions: Our results suggest that plasma proteins should be evaluated as a tool for prognosis determination in prioritization of patients for lung transplantation and stratification in drug studies.
MMP-7; adhesion molecules; biomarkers; personalized medicine; mortality prediction
Rationale: As computed tomography (CT) screening for lung cancer becomes more widespread, volumetric analyses, including doubling times, of CT-screen detected lung nodules and lung cancers may provide useful information in the follow-up and management of CT-detected lung nodules and cancers.
Objectives: To analyze doubling times in CT screen detected lung cancers and compare prevalent and nonprevalent cancers and different cell types on non small cell lung cancer.
Methods: We performed volumetric and doubling time analysis on 63 non–small cell lung cancers detected as part of the Pittsburgh Lung Screening Study using a commercially available VITREA 2 workstation and VITREA VITAL nodule segmentation software.
Measurements and Main Results: Doubling times (DT) were divided into three groups: rapid (DT < 183 d), typical (DT 183–365 d), and slow (DT > 365 d). Adenocarcinoma/bronchioloalveolar carcinoma comprised 86.7% of the slow DT group compared with 20% of the rapid DT group. Conversely, squamous cell cancer comprised 60% of the rapid DT group compared with 3.3% of the slow DT group. Twenty-eight of 42 (67%) prevalent and 2 of 21 (10%) nonprevalent cancers were in the slow DT group (P < 0.0001; Fisher's exact test). Twenty-four of 32 (75%) prevalent and 1 of 11 (9%) nonprevalent adenocarcinomas were in the slow DT group (P < 0.0002; Fisher's exact test).
Conclusions: Volumetric analysis of CT-detected lung cancers is particularly useful in AC/BAC. Prevalent cancers have a significantly slower DT than nonprevalent cancers and a higher percentage of adenocarcinoma/bronchioloalveolar carcinoma. These results should affect the management of indeterminant lung nodules detected on screening CT scans.
lung cancer; doubling times; lung cancer screening
Rationale: Sepsis and acute lung injury (ALI) have devastatingly high mortality rates. Both are associated with increased vascular leak, a process regulated by complex molecular mechanisms.
Objectives: We hypothesized that integrin αvβ3 could be an important determinant of vascular leak and endothelial permeability in sepsis and ALI.
Methods: β3 subunit knockout mice were tested for lung vascular leak after endotracheal LPS, and systemic vascular leak and mortality after intraperitoneal LPS and cecal ligation and puncture. Possible contributory effects of β3 deficiency in platelets and other hematopoietic cells were excluded by bone marrow reconstitution experiments. Endothelial cells treated with αvβ3 antibodies were evaluated for sphingosine-1 phosphate (S1P)–mediated alterations in barrier function, cytoskeletal arrangement, and integrin localization.
Measurements and Main Results: β3 knockout mice had increased vascular leak and pulmonary edema formation after endotracheal LPS, and increased vascular leak and mortality after intraperitoneal LPS and cecal ligation and puncture. In endothelial cells, αvβ3 antibodies inhibited barrier-enhancing and cortical actin responses to S1P. Furthermore, S1P induced translocation of αvβ3 from discrete focal adhesions to cortically distributed sites through Gi- and Rac1-mediated pathways. Cortical αvβ3 localization after S1P was decreased by αvβ3 antibodies, suggesting that ligation of the αvβ3 with its extracellular matrix ligands is required to stabilize cortical αvβ3 focal adhesions.
Conclusions: Our studies identify a novel mechanism by which αvβ3 mitigates increased vascular leak, a pathophysiologic function central to sepsis and ALI. These studies suggest that drugs designed to block αvβ3 may have the unexpected side effect of intensifying sepsis- and ALI-associated vascular endothelial leak.
vascular endothelium; sepsis; acute lung injury; integrin
Background: Research in critical care extends from the bench to the bedside, involving multiple departments, specialties, and funding organizations. Because of this diversity, it has been difficult for all stakeholders to collectively identify challenges and establish priorities.
Objective: To define a comprehensive agenda for critical care research using input from a broad range of stakeholders to serve as a blueprint for future initiatives.
Methods: The Critical Care Societies Collaborative (CCSC), consisting of the leadership of the American Association of Critical-Care Nurses (AACN), the American College of Chest Physicians (ACCP), the American Thoracic Society (ATS), and the Society of Critical Care Medicine (SCCM), joined the U.S. Critical Illness and Injury Trials Group (USCIITG) in forming a task force to define a comprehensive critical care research agenda. This group of 25 identified experts was divided into subgroups to address basic, translational, clinical, implementation, and educational research. The subgroups met via conference calls, and the entire task force met in person for a 2-day session. The result was a detailed discussion of the research priorities that served as the basis for this report.
Results: The task force identified challenges, specific priority areas, and recommendations for process improvements to support critical care research. Additionally, four overarching themes emerged: (1) the traditional “silo-ed” approach to critical care research is counterproductive and should be modified; (2) an approach that more effectively links areas of research (i.e., basic and translational research, or clinical research and implementation) should be embraced; (3) future approaches to human research should account for disease complexity and patient heterogeneity; and (4) an enhanced infrastructure for critical care research is essential for future success.
Conclusions: This document contains the themes/recommendations developed by a large, multiprofessional cross-section of critical care scientists, clinicians, and educators. It provides a unique framework for future research in critical care medicine.
Rationale: The National Quality Forum recently endorsed in-hospital mortality and intensive care unit length of stay (LOS) as quality indicators for patients in the intensive care unit. These measures may be affected by transferring patients to long-term acute care hospitals (LTACs).
Objectives: To quantify the implications of LTAC transfer practices on variation in mortality index and LOS index for patients in academic medical centers.
Methods: We used a cross-sectional study design using data reported to the University HealthSystem Consortium from 2008–2009. Data were from patients who were mechanically ventilated for more than 96 hours.
Measurements and Main Results: Using linear regression, we measured the association between mortality index and LTAC transfer rate, with the hospital as the unit of analysis. Similar analyses were conducted for LOS index and cost index. A total of 137 hospitals were analyzed, averaging 534 transfers to LTAC per hospital during the study period. Mean ± SD in-hospital mortality was 24 ± 6.4%, and observed LOS was 30.4 ± 8.2 days. The mean LTAC transfer rate was 15.7 ± 13.7%. Linear regression demonstrated a significant correlation between transfer rate and mortality index (R2 = 0.14; P < 0.0001) and LOS index (R2 = 0.43; P < 0.0001).
Conclusions: LTAC hospital transfer rate has a significant impact on reported mortality and LOS indices for patients requiring prolonged acute mechanical ventilation. This is an example of factors unrelated to quality of medical care or illness severity that must be considered when interpreting mortality and LOS as quality indicators.
National Quality Forum; American Thoracic Society; quality improvement
Rationale: Exacerbations of chronic obstructive pulmonary disease (COPD) and responses to treatment are heterogeneous.
Objectives: Investigate the usefulness of blood eosinophils to direct corticosteroid therapy during exacerbations.
Methods: Subjects with COPD exacerbations were entered into a randomized biomarker-directed double-blind corticosteroid versus standard therapy study. Subjects in the standard arm received prednisolone for 2 weeks, whereas in the biomarker-directed arm, prednisolone or matching placebo was given according to the blood eosinophil count biomarker. Both study groups received antibiotics. Blood eosinophils were measured in the biomarker-directed and standard therapy arms to define biomarker-positive and -negative exacerbations (blood eosinophil count > and ≤ 2%, respectively). The primary outcome was to determine noninferiority in health status using the chronic respiratory questionnaire (CRQ) and in the proportion of exacerbations associated with a treatment failure between subjects allocated to the biomarker-directed and standard therapy arms.
Measurements and Main Results: There were 86 and 80 exacerbations in the biomarker-directed and standard treatment groups, respectively. In the biomarker-directed group, 49% of the exacerbations were not treated with prednisolone. CRQ improvement after treatment in the standard and biomarker-directed therapy groups was similar (0.8 vs. 1.1; mean difference, 0.3; 95% confidence interval, 0.0–0.6; P = 0.05). There was a greater improvement in CRQ in biomarker-negative exacerbations given placebo compared with those given prednisolone (mean difference, 0.45; 95% confidence interval, 0.01–0.90; P = 0.04). In biomarker-negative exacerbations, treatment failures occurred in 15% given prednisolone and 2% of those given placebo (P = 0.04).
Conclusions: The peripheral blood eosinophil count is a promising biomarker to direct corticosteroid therapy during COPD exacerbations, but larger studies are required.
Clinical trial registered with www.controlled-trials.com (ISRCTN92422949).
chronic obstructive pulmonary disease; exacerbations; prednisolone; infection; eosinophils
Rationale: Gastroesophageal reflux (GER) is highly prevalent in patients with idiopathic pulmonary fibrosis (IPF). Chronic microaspiration secondary to GER may play a role in the pathogenesis and natural history of IPF.
Objectives: To investigate the relationship between GER-related variables and survival time in patients with IPF.
Methods: Regression analysis was used to investigate the relationship between GER-related variables and survival time in a retrospectively identified cohort of patients with well-characterized IPF from two academic medical centers.
Measurements and Main Results: Two hundred four patients were identified for inclusion. GER-related variables were common in this cohort: reported symptoms of GER (34%), a history of GER disease (45%), reported use of GER medications (47%), and Nissen fundoplication (5%). These GER-related variables were significantly associated with longer survival time on unadjusted analysis. After adjustment, the use of GER medications was an independent predictor of longer survival time. In addition, the use of gastroesophageal reflux medications was associated with a lower radiologic fibrosis score. These findings were present regardless of center.
Conclusions: The reported use of GER medications is associated with decreased radiologic fibrosis and is an independent predictor of longer survival time in patients with IPF. These findings further support the hypothesis that GER and chronic microaspiration may play important roles in the pathobiology of IPF.
pulmonary fibrosis; respiratory aspiration; idiopathic interstitial pneumonia; survival
Rationale: Heritable pulmonary arterial hypertension (HPAH) is primarily caused by mutations of the bone morphogenetic protein (BMP) type-II receptor (BMPR2). Recent identification of mutations in the downstream mediator Smad-8 (gene, SMAD9) was surprising, because loss of Smad-8 function in canonical BMP signaling is largely compensated by Smad-1 and -5. We therefore hypothesized that noncanonical pathways may play an important role in PAH.
Objectives: To determine whether HPAH mutations disrupt noncanonical Smad-mediated microRNA (miR) processing.
Methods: Expression of miR-21, miR-27a, and miR-100 was studied in pulmonary artery endothelial (PAEC) and pulmonary artery smooth muscle cells (PASMC) from explant lungs of patients with PAH.
Measurements and Main Results: SMAD9 mutation completely abrogated miR induction, whereas canonical signaling was only reduced by one-third. miR-21 levels actually decreased, suggesting that residual canonical signaling uses up or degrades existing miR-21. BMPR2 mutations also led to loss of miR induction in two of three cases. HPAH cells proliferated faster than other PAH or controls. miR-21 and miR-27a each showed antiproliferative effects in PAEC and PASMC, and PAEC growth rate after BMP treatment correlated strongly with miR-21 fold-change. Overexpression of SMAD9 corrected miR processing and reversed the hyperproliferative phenotype.
Conclusions: HPAH-associated mutations engender a primary defect in noncanonical miR processing, whereas canonical BMP signaling is partially maintained. Smad-8 is essential for this miR pathway and its loss was not complemented by Smad-1 and -5; this may represent the first nonredundant role for Smad-8. Induction of miR-21 and miR-27a may be a critical component of BMP-induced growth suppression, loss of which likely contributes to vascular cell proliferation in HPAH.
bone morphogenetic protein signaling; mutation; endothelium; smooth muscle