Rationale

Little is known about vitamin D status and its effect on asthma pathophysiology in children with severe, therapy-resistant asthma (STRA).

Objectives

Relationships between serum vitamin D, lung function, and pathology were investigated in pediatric STRA.

Methods

Serum 25-hydroxyvitamin D [25(OH)D3] was measured in 86 children (mean age, 11.7 yr): 36 with STRA, 26 with moderate asthma (MA), and 24 without asthma (control subjects). Relationships between 25(OH)D3, the asthma control test (ACT), spirometry, corticosteroid use, and exacerbations were assessed. Twenty-two of 36 children with STRA underwent fiberoptic bronchoscopy, bronchoalveolar lavage, and endobronchial biopsy with assessment of airway inflammation and remodeling.

Measurements and Main Results

25(OH)D3 levels (median [IQR]) were significantly lower in STRA (28 [22–38] nmol/L) than in MA (42.5 [29–63] nmol/L) and control subjects (56.5 [45–67] nmol/L) (P < 0.001). There was a positive relationship between 25(OH)D3 levels and percent predicted FEV1 (r = 0.4, P < 0.001) and FVC (r = 0.3, P = 0.002) in all subjects. 25(OH)D3 levels were positively associated with ACT (r = 0.6, P < 0.001), and inversely associated with exacerbations (r=−0.6, P < 0.001) and inhaled steroid dose (r=−0.39, P = 0.001) in MA and and STRA. Airway smooth muscle (ASM) mass, but not epithelial shedding or reticular basement membrane thickness, was inversely related to 25(OH)D3 levels (r=−0.6, P = 0.008). There was a positive correlation between ASM mass and bronchodilator reversibility (r = 0.6, P = 0.009) and an inverse correlation between ASM mass and ACT (r = −0.7, P < 0.001).

Conclusions

Lower vitamin D levels in children with STRA were associated with increased ASM mass and worse asthma control and lung function. The link between vitamin D, airway structure, and function suggests vitamin D supplementation may be useful in pediatric STRA.

Rationale

IL-9 is a pleiotropic cytokine that has multiple effects on structural as well as numerous hematopoietic cells, which are central to the pathogenesis of asthma.

Objectives

The contribution of IL-9 to asthma pathogenesis has thus far been unclear, due to conflicting reports in the literature. These earlier studies focused on the role of IL-9 in acute inflammatory models; here we have investigated the effects of IL-9 blockade during chronic allergic inflammation.

Methods

Mice were exposed to either prolonged ovalbumin or house dust mite allergen challenge to induce chronic inflammation and airway remodeling.

Measurements and Main Results

We found that IL-9 governs allergen-induced mast cell (MC) numbers in the lung and has pronounced effects on chronic allergic inflammation. Anti–IL-9 antibody–treated mice were protected from airway remodeling with a concomitant reduction in mature MC numbers and activation, in addition to decreased expression of the profibrotic mediators transforming growth factor-β1, vascular endothelial growth factor, and fibroblast growth factor-2 in the lung. Airway remodeling was associated with impaired lung function in the peripheral airways and this was reversed by IL-9 neutralization. In human asthmatic lung tissue, we identified MCs as the main IL-9 receptor expressing population and found them to be sources of vascular endothelial growth factor and fibroblast growth factor-2.

Conclusions

Our data suggest an important role for an IL-9-MC axis in the pathology associated with chronic asthma and demonstrate that an impact on this axis could lead to a reduction in chronic inflammation and improved lung function in patients with asthma.

Rationale

Cystic fibrosis (CF) is characterized by bronchoalveolar neutrophilia and submucosal lymphocytosis. We hypothesized that Th17 lymphocytes are part of this submucosal infiltrate.

Objectives

Quantification and phenotyping of the lymphocytic infiltrate in the bronchial submucosa of patients with CF (n=53, of which 20 were newly diagnosed), non-CF bronchiectasis (n = 17), and healthy control subjects (n = 13).

Methods

We measured IL-17 levels in bronchoalveolar lavage and CD4+, CD8+, and IL-17+ cell counts in endobronchial biopsies. Correlations were made with infection status and other inflammatory markers. Potential cellular sources of IL-17 were determined by double staining.

Measurements and Main Results

IL-17+ cell counts (median [interquartile range] cells/mm2) were significantly higher in patients with established CF (205 [115–551]) and non-CF bronchiectasis (245 [183–436]) than in control subjects (53 [12–82]) (P<0.01 for both). Patients with newly diagnosed CF had intermediate counts (171 [91–252]). IL-17–positive CD4+ T cells, γδT cells, natural killer T cells, and neutrophils were identified. Bronchoalveolar lavage IL-17 levels (pg/ml) were highest in established CF (14.6 [2.2–38.4]), low in newly diagnosed CF and control subjects (1.7 [1.7–1.74]; 1.7 [1.7–3]), and intermediate in non-CF bronchiectasis (9.1 [1.7–34] pg/ml) (Kruskal-Wallis P = 0.001). There was a significant correlation between IL-17 and neutrophil counts (P < 0.001, R = 0.6) as well as IL-4 (P < 0.001, R = 0.84).

Conclusions

Th17 lymphocytes are present in the airway submucosa in CF, even in a young, newly diagnosed group. Other IL-17+ cells include neutrophils, γδ T cells, and natural killer T cells.

Rationale

The current management of advanced non-small cell lung cancer (NSCLC) requires differentiation between squamous and non-squamous sub-types as well as epidermal growth factor receptor (EGFR) mutation status. Endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA) is increasingly used for the diagnosis and staging of lung cancer. However, it is unclear whether cytology specimens obtained with EBUS-TBNA are suitable for the sub-classification and genotyping of NSCLC.

Objectives

To determine whether cytology specimens obtained from EBUS-TBNA in routine practice are suitable for phenotyping and genotyping of NSCLC.

Methods

Cytological diagnoses from EBUS-TBNA were recorded from 774 patients with known or suspected lung cancer across 5 centres in the United Kingdom between 2009 and 2011.

Measurements and Main Results

The proportion of patients with a final diagnosis by EBUS-TBNA in whom subtype was classified was 77% (95% CI 73% - 80%). The rate of NSCLC not otherwise specified (NSCLC-NOS) was significantly reduced in patients who underwent immunohistochemistry (adjusted OR 0.50 95% CI 0.28 – 0.82, P=0.016). EGFR mutation analysis was possible in 107 (90%) of the 119 patients in whom mutation analysis was requested. The sensitivity, negative predictive value and diagnostic accuracy of EBUS-TBNA in patients with NSCLC was 88% (95% CI 86% - 91%), 72% (95% CI 66% - 77%) and 91% (95% CI 89% - 93%) respectively.

Conclusions

This large multi-centre pragmatic study demonstrates that cytology samples obtained from EBUS-TBNA in routine practice are suitable for sub-typing of NSCLC and EGFR mutation analysis and that use of immunohistochemistry reduces the rate of NSCLC-NOS.

Rationale

Critically ill patients are highly susceptible to hospital-acquired infection. Neutrophil function in critical illness remains poorly understood.

Objectives

To characterize and define mechanisms of peripheral blood neutrophil (PBN) dysfunction in critically ill patients. To determine whether the inflamed lung contributes additional phagocytic impairment.

Methods

Prospective collection of blood and bronchoalveolar lavage fluid from patients with suspected ventilator-associated pneumonia and from age- and sex-matched volunteers; laboratory analysis of neutrophil functions.

Measurements and Main Results

Seventy-two patients and 21 volunteers were included. Phagocytic capacity of PBNs was 36% lower in patients than in volunteers (P < 0.0001). From several biologically plausible candidates only activated complement was significantly associated with impaired PBN phagocytosis (P < 0.0001). Phagocytosis was negatively correlated with serum C3a and positively correlated with expression of C5a receptor type 1 (CD88) on PBNs. C5a recapitulated impaired PBN phagocytosis and significantly down-regulated CD88 expression in vitro. C5a-mediated phagocytic impairment was prevented by blocking either CD88 or phosphoinositide 3-kinase, and completely reversed by granulocyte-macrophage colony-stimulating factor. C5a also impaired killing of Pseudomonas aeruginosa by, and migration of, PBNs, indicating that effects were not restricted to phagocytosis. Bronchoalveolar lavage fluid leukocytes from patients also demonstrated significantly impaired function, and lavage supernatant reduced phagocytosis in healthy neutrophils by 43% (P = 0.0001). However, lavage fluid did not affect CD88 expression and lavage-mediated impairment of phagocytosis was not blocked by anti-CD88 antibody.

Conclusions

Critically ill patients have significant dysfunction of PBNs, which is mediated predominantly by activated complement. Further, profound complement-independent neutrophil dysfunction occurs in the inflamed lung.

Rationale

Uteroglobin-related protein (UGRP) 1, which is highly expressed in the epithelial cells of the airways, has been suggested to play a role in lung inflammation.

Objectives

The aim of study was to understand the effect of overexpressed UGRP1 on lung inflammation in a mouse model of allergic airway inflammation.

Methods

Ovalbumin-sensitized and -challenged mice, a model for allergic airway inflammation, were used in conjunction with recombinant adenovirus expressing UGRP1.

Measurements and Main Results

We demonstrated that intranasal administration of adeno-UGRP1 successfully delivered UGRP1 to the epithelial cells of airways and markedly reduced the number of infiltrating inflammatory cells, particularly eosinophils, in lung tissue as well as the level of proinflammatory cytokines such as interleukin (IL)-4, IL-5, and IL-13 in bronchoalveolar lavage fluids. The healed phase of inflammation was clearly seen in the peripheral areas of adeno-UGRP1–treated mouse lungs.

Conclusion

These results demonstrate that UGRP1 can suppress inflammation in the mouse model of allergic airway inflammation. Based on this result, we propose UGRP1 as a novel therapeutic candidate for treating lung inflammation such as is found in asthma.

Rationale: Acute exposure to chlorine gas results in respiratory impairment, but few data are available on the pathobiology of the underlying lung damage. Objectives: To assess lung function and potential lung damage pathways in the acute phase and longitudinally over a 15-month follow-up after chlorine exposure. Methods: Ten previously-healthy children were accidentally exposed to chlorine gas at a swimming pool due an erroneous servicing procedure. Exhaled nitric oxide (FENO), exhaled breath condensate (EBC) compounds and serum Clara cell protein (CC16) were repeatedly measured. Main results: In the acute phase, all patients had respiratory distress (one child required mechanical ventilation) and reduced lung function (median and IQR: FVC 51% pred. [43-60], FEV1 51% pred. [46-60]). This was accompanied by low FENO (4.7 [3.9-7.9] ppb), high EBC leukotriene B4 (LTB-4) levels (24.4 [22.5-24.9] pg/mL) and increased serum CC16 levels (mean ± SE 23.4 ± 2.5 μg/L). Lung function returned to normal in 15 days (FVC 97% pred. [82-108] and FEV1 92% pred. [77-102]). FENO reached normal values after 2 months (12.6 [11.4-15] ppb), while LTB-4 levels were still increased (12 [9.3-17.1] pg/mL). Conclusion: Children acutely exposed to chlorine in a swimming pool presented a substantial lung function impairment associated with biochemical exhaled breath alterations, mainly represented by an increase in LTB-4 and a reduction in FENO. While lung function and FENO improved within a few weeks, the increased levels of exhaled LTB-4 persisted for several months.

Rationale: ABCA3 is a member of the ATP-binding cassette family of proteins that mediate the translocation of a wide variety of substrates, including lipids, across cellular membranes. Mutations in the gene encoding ABCA3 were recently identified in full-term neonates with fatal surfactant deficiency.

Objective: To test the hypothesis that ABCA3 mutations are not always associated with fatal neonatal lung disease but are a cause of pediatric interstitial lung disease.

Methods: DNA samples were obtained from 195 children with chronic lung disease of unknown etiology. The 30 coding exons of the ABCA3 gene were sequenced in four unrelated children with a referring diagnosis of desquamative interstitial pneumonitis and who were older than 10 years at the time of enrollment.

Results: Three of four patients (ages 16, 23, and 11 years) with desquamative interstitial pneumonitis had ABCA3 mutations identified on both alleles. All three had the same missense mutation (E292V) and a second unique mutation. The E292V mutation was not found on 200 control alleles from adults without lung disease, but seven additional patients of the remaining study patients had the E292V mutation on one allele. Immunohistochemical analysis of surfactant protein expression in three patients revealed a specific staining pattern for surfactant protein-B, which was the same pattern observed in several infants with fatal lung disease due to ABCA3 mutations.

Conclusion: ABCA3 mutations cause some types of interstitial lung disease in pediatric patients.

Rationale: Myofibroblasts are primary effector cells in idiopathic pulmonary fibrosis. Defining mechanisms of myofibroblast differentiation may be critical to the development of novel therapeutic agents. Objective: To show that myofibroblast differentiation is regulated by phosphatase and tensin homologue deleted on chromosome 10 (PTEN) activity in vivo and to identify a potential mechanism by which this occurs. Methods: We utilized tissue sections of surgical lung biopsies from patients with idiopathic pulmonary fibrosis to localize expression of PTEN and α-SMA. We utilized cell culture of pten-/- and wild-type fibroblasts as well as adenoviral strategies and pharmacologic inhibitors to determine the mechanism by which PTEN inhibits α-SMA, fibroblast proliferation, and collagen production. Results: In human lung specimens of idiopathic pulmonary fibrosis, myofibroblasts within fibroblastic foci demonstrate diminished PTEN expression. Further, inhibition of PTEN in mice worsened bleomycin-induced fibrosis. In pten-/- fibroblasts, and in normal fibroblasts in which PTEN is inhibited, α-SMA, proliferation, and collagen production is upregulated. Addition of transforming growth factor-β to wild-type cells, but not pten-/- cells, results in increased α-SMA expression in a time-dependent fashion. In pten-/- cells, reconstitution of PTEN decreases α-SMA expression, proliferation, and collagen production, whereas overexpression of PTEN in wild-type cells inhibits transforming growth factor-β-induced myofibroblast differentiation. Both the protein and lipid phosphatase actions of PTEN are capable of modulating the myofibroblast phenotype. Conclusions: The results indicate that in idiopathic pulmonary fibrosis, myofibroblasts have diminished PTEN expression. Inhibition of PTEN in vivo promotes fibrosis, and PTEN inhibits myofibroblast differentiation in vitro.

Rationale

Using principal components analysis to examine dietary patterns complements the evaluation of individual food and nutrient intake in relation to health outcomes, but has not yet been applied to nonmalignant respiratory disease or symptoms.

Objective

To examine the relation between patterns of dietary intake at baseline and new-onset of persistent cough with phlegm in a population-based cohort of Singapore Chinese.

Methods

A 165-item validated food frequency questionnaire was administered in-person at baseline in 1993. We identified 623 cases of incident cough with phlegm among 52,325 subjects by telephone interview from 1999 through 2004. We identified two distinct food patterns: a “meat-dim sum” pattern characterized by pork and chicken dim sum foods and noodle dishes, and a “vegetable-fruit-soy” pattern characterized by vegetables, fruit and soyfood items.

Main Results

The meat-dim sum pattern was positively associated with new-onset cough with phlegm (odds ratio=1.43; 95% confidence interval: 1.08, 1.89; comparing fourth to first quartile, P for trend=0.02,), after adjustment for age, gender, total energy intake, smoking, education and non-starch polysaccharide intake, a protective factor for cough with phlegm in this cohort. Weaker associations were seen for more chronic symptoms and for incident asthma. A weak inverse association for the vegetable-fruit-soy pattern disappeared after adjustment for non-starch polysaccharide intake.

Conclusion

A diet rich in meats, sodium plus refined carbohydrates may increase risk of developing cough with phlegm, independently of the apparent beneficial effects of a diet high in non-starch polysaccharides in this Singapore Chinese cohort.

Background: While research has shown that early life exposure to household endotoxin protects against development of allergies, studies are less clear on the relationship between household endotoxin exposure and prevalence of wheezing and asthma. We assayed 2552 house dust samples in a representative nationwide sample to explore relationships between endotoxin exposures and risk factors for asthma, asthma symptoms and medication use.

Methods: House dust was vacuum-sampled from five locations within homes and assayed for endotoxin. Health, demographic and housing information was assessed through questionnaire and on-site evaluation of 2456 residents of 831 homes selected to represent the demographics of the U.S.

Results: Endotoxin concentration (EU/mg) and load (EU/m2) were highly correlated (r=0.73-0.79). Geometric mean endotoxin concentrations were (in EU/mg): bedroom floors: 35.3 (5th-95thpercentile: 5.0-260); bedding: 18.7 (2.0-142); family room floors: 63.9 (11.5-331); sofas: 44.8 (6.4-240); kitchen floors: 80.5 (9.8-512). Multivariate analysis demonstrated significant relationships between increasing endotoxin levels and diagnosed asthma, asthma symptoms in the past year, current use of asthma medications, and wheezing among residents of the homes. These relationships were strongest for bedroom floor and bedding dust and were observed in adults only. Modeling the joint effect of bedding and bedroom floor endotoxin on recent asthma symptoms yielded an adjusted odds ratio of 2.83 (95%CI: 1.01-7.87). When stratified by allergy status, allergic subjects with higher endotoxin exposure were no more likely to have diagnosed asthma or asthma symptoms than non-allergic subjects.

Conclusion: This study demonstrates that household endotoxin exposure is a significant risk factor for increased asthma prevalence.

Rationale

Hyperoxic ventilation in the management of persistent pulmonary hypertension of the newborn (PPHN) can result in the formation of reactive oxygen species, such as superoxide anions, which can inactivate nitric oxide (NO) and cause vasoconstriction and oxidation.

Objective

To compare the effect of intratracheal recombinant human superoxide dismutase (rhSOD) and/or inhaled NO (iNO) on systemic oxygenation, contractility of pulmonary arteries (PAs), and lung reactive oxygen species (isoprostane, 3-nitrotyrosine) levels in neonatal lambs with PPHN.

Methods

Six newborn lambs with PPHN (induced by antenatal ductal ligation) were killed at birth. Twenty-six PPHN lambs were ventilated for 24 h with 100% O2 alone (n = 6) or O2 combined with rhSOD (5 mg/kg intratracheally) at birth (n = 4), rhSOD at 4 h of age (n = 5), iNO (20 ppm, n = 5), or rhSOD + iNO (n = 6). Contraction responses of fifth-generation PAs to norepinephrine and KCl, lung isoprostane levels, and 3-nitrotyrosine fluorescent intensity were measured.

Results

Systemic oxygenation was impaired in PPHN lambs and significantly improved (up to threefold) in both rhSOD groups with or without iNO. Oxygenation improved more rapidly with the combination of rhSOD + iNO compared with either intervention alone. Norepinephrine- and KCl-induced contractions and lung isoprostane levels were significantly increased by 100% O2 compared with nonventilated newborn lambs with PPHN. Both rhSOD and iNO mitigated the increased PA contraction response and lung isoprostane levels. Intratracheal rhSOD decreased the enhanced lung 3-nitrotyrosine fluorescence observed with iNO therapy.

Conclusion

Intratracheal rhSOD and/or iNO rapidly increase oxygenation and reduce both vasoconstriction and oxidation in newborn lambs with PPHN. This has important implications for clinical trials of rhSOD and iNO in newborn infants with PPHN.

Rationale

Airway hyperresponsiveness is a critical feature of asthma. Substantial epidemiologic evidence supports a role for female sex hormones in modulating lung function and airway hyperresponsiveness in humans.

Objectives

To examine the role of estrogen receptors in modulating lung function and airway responsiveness using estrogen receptor–deficient mice.

Methods

Lung function was assessed by a combination of whole-body barometric plethysmography, invasive measurement of airway resistance, and isometric force measurements in isolated bronchial rings. M2 muscarinic receptor expression was assessed by Western blotting, and function was assessed by electrical field stimulation of tracheas in the presence/absence of gallamine. Allergic airway disease was examined after ovalbumin sensitization and exposure.

Measurements and Main Results

Estrogen receptor-α knockout mice exhibit a variety of lung function abnormalities and have enhanced airway responsiveness to inhaled methacholine and serotonin under basal conditions. This is associated with reduced M2 muscarinic receptor expression and function in the lungs. Absence of estrogen receptor-α also leads to increased airway responsiveness without increased inflammation after allergen sensitization and challenge.

Conclusions

These data suggest that estrogen receptor-α is a critical regulator of airway hyperresponsiveness in mice.

Rationale

Exercise-induced bronchoconstriction (EIB) is a highly prevalent condition with unclear pathogenesis. Two competing theories of the pathogenesis of EIB differ regarding the inflammatory basis of this condition.

Objectives

Our goals were to establish whether epithelial cell and mast cell activation with release of inflammatory mediators occurs during EIB and how histamine and cysteinyl leukotriene antagonists alter the airway events occurring during EIB.

Methods

Induced sputum was used to measure mast cell mediators and eicosanoids at baseline and 30 minutes after exercise challenge in 25 individuals with asthma with EIB. In a randomized, double-blind crossover study, the cysteinyl leukotriene antagonist montelukast and antihistamine loratadine or two matched placebos were administered for two doses before exercise challenge.

Main Results

The percentage of columnar epithelial cells in induced sputum at baseline was associated with the severity of EIB. After exercise challenge, histamine, tryptase, and cysteinyl leukotrienes significantly increased and prostaglandin E2 and thromboxane B2 significantly decreased in the airways, and there was an increase in columnar epithelial cells in the airways. The concentration of columnar epithelial cells was associated with the levels of histamine and cysteinyl leukotrienes in the airways. Treatment with montelukast and loratadine inhibited the release of cysteinyl leukotrienes and histamine into the airways, but did not inhibit the release of columnar epithelial cells into the airways.

Conclusions

These data indicate that epithelial cells, mast cell mediators, and eicosanoids are released into the airways during EIB, supporting an inflammatory basis for EIB.

Rationale

Urban African-American youth, aged 15–19 years, have asthma fatality rates that are higher than in whites and younger children, yet few programs target this population. Traditionally, urban youth are believed to be difficult to engage in health-related programs, both in terms of connecting and convincing.

Objectives

Develop and evaluate a multimedia, web-based asthma management program to specifically target urban high school students. The program uses “tailoring,” in conjunction with theory-based models, to alter behavior through individualized health messages based on the user’s beliefs, attitudes, and personal barriers to change.

Methods

High school students reporting asthma symptoms were randomized to receive the tailored program (treatment) or to access generic asthma websites (control). The program was made available on school computers.

Measurements and Main Results

Functional status and medical care use were measured at study initiation and 12 months postbaseline, as were selected management behaviors. The intervention period was 180 days (calculated from baseline). A total of 314 students were randomized (98% African American, 49% Medicaid enrollees; mean age, 15.2 yr). At 12 months, treatment students reported fewer symptom-days, symptom-nights, school days missed, restricted-activity days, and hospitalizations for asthma when compared with control students; adjusted relative risk and 95% confidence intervals were as follows: 0.5 (0.4–0.8), p = 0.003; 0.4 (0.2–0.8), p = 0.009; 0.3 (0.1–0.7), p = 0.006; 0.5 (0.3–0.8), p = 0.02; and 0.2 (0.2–0.9), p = 0.01, respectively. Positive behaviors were more frequently noted among treatment students compared with control students. Cost estimates for program delivery were $6.66 per participating treatment group student.

Conclusions

A web-based, tailored approach to changing negative asthma management behaviors is economical, feasible, and effective in improving asthma outcomes in a traditionally hard-to-reach population.

Rationale

Recent studies have demonstrated that intermittent administration of rifamycin-based regimens results in higher rates of tuberculosis relapse and treatment failure compared with daily therapy. Twice-weekly treatment with rifampin, isoniazid, and pyrazinamide may be improved by increasing Mycobacterium tuberculosis exposure to rifamycin by substituting rifapentine for rifampin.

Methods

To test this hypothesis, we compared the activities of standard daily and twice-weekly rifampin plus isoniazid-based regimens to those of twice-weekly rifapentine plus isoniazid- or moxifloxacin-containing regimens in the murine model of tuberculosis. Relapse rates were assessed after 4, 5, and 6 mo of treatment to assess stable cure. Single- and multiple-dose pharmacokinetics of rifampin and rifapentine were also determined.

Results

After 2 mo of treatment, twice-weekly therapy with rifapentine (15 or 20 mg/kg), moxifloxacin, and pyrazinamide was significantly more active than standard daily or twice-weekly therapy with rifampin, isoniazid, and pyrazinamide. Stable cure was achieved after 4 mo of twice-weekly rifapentine plus isoniazid- or moxifloxacin-containing therapy, but only after 6 mo of standard daily therapy. Twice-weekly rifapentine (15 mg/kg) displayed more favorable pharmacodynamics than did daily rifampin (10 mg/kg).

Conclusions

By virtue of the enhanced rifamycin exposure, twice-weekly regimens containing rifapentine (15 or 20 mg/kg) may permit shortening the current treatment duration by 2 mo. Such regimens warrant clinical investigation.

Rationale

Priorities for developing improved regimens for treatment of latent tuberculosis (TB) infection include (1) developing shorter and/or more intermittently administered regimens that are easier to supervise and (2) developing and evaluating regimens that are active against multidrug-resistant organisms.

Objectives and Methods

By using a previously validated murine model that involves immunizing mice with Mycobacterium bovis bacillus Calmette-Guérin to augment host immunity before infection with virulent Mycobacterium tuberculosis, we evaluated new treatment regimens including rifapentine and moxifloxacin, and assessed the potential of the Mycobacterium leprae heat shock protein-65 DNA vaccine to augment the activity of moxifloxacin.

Measurements

Quantitative spleen colony-forming unit counts, and the proportion of mice with culture-positive relapse after treatment, were determined.

Main Results

Three-month, once-weekly regimens of rifapentine combined with either isoniazid or moxifloxacin were as active as daily isoniazid for 6–9 mo. Six-month daily combinations of moxifloxacin with pyrazinamide, ethionamide, or ethambutol were more active than pyrazinamide plus ethambutol, a regimen recommended for latent TB infection after exposure to multidrug-resistant TB. The combination of moxifloxacin with the experimental nitroimidazopyran PA-824 was especially active. Finally, the heat shock protein-65 DNA vaccine had no effect on colony-forming unit counts when given alone, but augmented the bactericidal activity of moxifloxacin.

Conclusions

Together, these findings suggest that rifapentine, moxifloxacin, and, perhaps, therapeutic DNA vaccination have the potential to improve on the current treatment of latent TB infection.

Florida red tide brevetoxins are sodium channel neurotoxins produced by the dinoflagellate Karenia brevis. When aerosolized, the toxin causes airway symptoms in normal individuals and patients with airway disease, but systematic exposures to define the pulmonary consequences and putative mechanisms are lacking. Here we report the effects of airway challenges with lysed cultures of Karenia brevis (crude brevetoxin), pure brevetoxin-2, brevetoxin-3, and brevetoxin-tbm (brevetoxin-2 minus the side chain) on pulmonary resistance and tracheal mucus velocity, a marker of mucociliary clearance, in allergic and nonallergic sheep. Picogram concentrations of toxin caused bronchoconstriction in both groups of sheep. Brevetoxin-tbm was the least potent, indicating the importance of the side chain for maximum effect. Both histamine H1– and cholinergic-mediated pathways contributed to the bronchoconstriction. A synthetic antagonist, β-naphthoyl-brevetoxin-3, and brevenal, a natural antagonist, inhibited the bronchoconstriction. Only crude brevetoxin and brevetoxin-3 decreased tracheal mucus velocity; both antagonists prevented this. More importantly, picomolar concentrations of the antagonists alone improved tracheal mucus velocity to the degree seen with mM concentrations of the sodium channel blocker amiloride. Thus, Karenia brevis, in addition to producing toxins that adversely affect the airways, may be a source of agents for treating mucociliary dysfunction.

The natural history of idiopathic pulmonary fibrosis (IPF) has been characterized as a steady, predictable decline in lung function over time. Recent evidence suggests that some patients may experience a more precipitous course, with periods of relative stability followed by acute deteriorations in respiratory status. Many of these acute deteriorations are of unknown etiology and have been termed acute exacerbations of IPF. This perspective is the result of an international effort to summarize the current state of knowledge regarding acute exacerbations of IPF. Acute exacerbations of IPF are defined as acute, clinically significant deteriorations of unidentifiable cause in patients with underlying IPF. Proposed diagnostic criteria include subjective worsening over 30 days or less, new bilateral radiographic opacities, and the absence of infection or another identifiable etiology. The potential pathobiological roles of infection, disordered cell biology, coagulation, and genetics are discussed, and future research directions are proposed.

Idiopathic pulmonary fibrosis is a disease that is characterized by fibroblast accumulation and activation in the distal airspaces of the lung. We hypothesized that fibrotic lung fibroblasts migrate/invade across basement membranes by integrin-mediated mechanisms as a means of entering alveoli. We demonstrate that in lung fibroblasts derived from patients with idiopathic pulmonary fibrosis, fibronectin signaling is both necessary and sufficient for basement membrane migration/invasion across basement membranes. This effect is mediated through the α5β1 integrin because blockade of fibronectin-α5 integrin ligation attenuated this response. In contrast, ligation of α4β1 integrin inhibits basement membrane invasion by normal lung fibroblasts but not by fibrotic lung fibroblasts. This phenotypic difference is not related to surface expression of the α4β1 integrin, as demonstrated by flow cytometry. In normal lung fibroblasts but not in fibrotic lung fibroblasts, we show that ligation of α4β1 integrin induces a significant increase in phosphatase and tensin homologue deleted on chromosome 10 (PTEN) activity. Fibrotic lung fibroblasts express constitutively less PTEN mRNA and protein as well as phosphatase activity in comparison to normal lung fibroblasts. Together, these data suggest that a loss of α4β1 signaling via PTEN confers a migratory/invasive phenotype to fibrotic lung fibroblasts. Furthermore, this study implicates a loss of PTEN function in the pathophysiology of idiopathic pulmonary fibrosis.