Pathology of small airways disease

Pulmonary Fibrosis Ferret Model Demonstrates Sustained Fibrosis, Restrictive Physiology, and Aberrant Repair

Rationale

The role of MUC5B mucin expression in IPF pathogenesis is unknown. Bleomycin-exposed rodent models do not exhibit sustained fibrosis or airway remodeling. Unlike mice, ferrets have human-like distribution of MUC5B expressing cell types and natively express the risk-conferring variant that induces high MUC5B expression in humans. We hypothesized that ferrets would consequently exhibit aberrant repair to propagate fibrosis similar to human IPF.

Methods

Bleomycin (5U/kg) or saline-control was micro-sprayed intratracheally then wild-type ferrets were evaluated through 22 wks. Clinical phenotype was assessed with lung function. Fibrosis was assessed with µCT imaging and comparative histology with Ashcroft scoring. Airway remodeling was assessed with histology and quantitative immunofluorescence.

Results

Bleomycin ferrets exhibited sustained restrictive physiology including decreased inspiratory capacity, decreased compliance, and shifted Pressure-Volume loops through 22 wks. Volumetric µCT analysis revealed increased opacification of the lung bleomycin-ferrets. Histology showed extensive fibrotic injury that matured over time and MUC5B-positive cystic structures in the distal lung suggestive of honeycombing. Bleomycin ferrets had increased proportion of small airways that were double-positive for CCSP and alpha-tubulin compared to controls, indicating an aberrant 'proximalization' repair phenotype. Notably, this aberrant repair was associated with extent of fibrotic injury at the airway level.

Conclusions

Bleomycin-exposed ferrets exhibit sustained fibrosis through 22 wks and have pathologic features of IPF not found in rodents. Ferrets exhibited proximalization of the distal airways and other pathologic features characteristic of human IPF. MUC5B expression through native cell types may play a key role in promoting airway remodeling and lung injury in IPF.

Fleischner Society: Glossary of Terms for Thoracic Imaging

Members of the Fleischner Society have compiled a glossary of terms for thoracic imaging that replaces previous glossaries published in 1984, 1996, and 2008, respectively. The impetus to update the previous version arose from multiple considerations. These include an awareness that new terms and concepts have emerged, others have become obsolete, and the usage of some terms has either changed or become inconsistent to a degree that warranted a new definition. This latest glossary is focused on terms of clinical importance and on those whose meaning may be perceived as vague or ambiguous. As with previous versions, the aim of the present glossary is to establish standardization of terminology for thoracic radiology and, thereby, to facilitate communications between radiologists and clinicians. Moreover, the present glossary aims to contribute to a more stringent use of terminology, increasingly required for structured reporting and accurate searches in large databases. Compared with the previous version, the number of images (chest radiography and CT) in the current version has substantially increased. The authors hope that this will enhance its educational and practical value. All definitions and images are hyperlinked throughout the text. Click on each figure callout to view corresponding image. © RSNA, 2024 Supplemental material is available for this article. See also the editorials by Bhalla and Powell in this issue.

Effectiveness of glycopyrronium bromide in the treatment of small airway dysfunction: A retrospective study

Objective

Glycopyrronium bromide has a quaternary ammonium structure and a low oral bioavailability, which reduces its systemic effects; it acts through a bronchodilating blockade of muscarinic receptors. The aim of this retrospective study was to analyze a possible relationship between the changes in the small airways and the efficacy of a bronchodilation with glycopyrronium bromide; exercise tolerance was also assessed, by performing the six-minute walking test.

Methods

Forty-one patients were identified (23 females/18 males; mean age 66.82 ± 9.75 years), with a normal forced expiratory volume in 1 s (FEV₁)/forced vital capacity ratio of 77.45% ± 4.86%, a reduced forced mid-expiratory flow between 25% and 75% of forced vital capacity (FEF_25-75) of 42.9% ± 10.5%, with an increased residual volume/total lung capacity ratio of 132.68% ± 6.41%, FEV₁ 1.85 ± 0.54 L, forced vital capacity 2.39 ± 0.71 L, airway resistance (sR tot) 168.18% ± 42.5%, total lung capacity 98.28% ± 8.9%, six-minute walking test distance 318.3 ± 36.6 m, modified British Medical Research Council dyspnea scale 1.48 ± 0.77. All patients were initiated with glycopyrronium bromide 50 μg/die and reassessed after 4 months.

Results

After the treatment with glycopyrronium bromide, a significant improvement was noted regarding forced vital capacity (p = 0.04), FEF_25-75 (p < 0.001), sR tot (p < 0.001), residual volume/total lung capacity ratio (p < 0.001) with reduction of dynamic hyperinflation, the significant increase of the distance covered during the six-minute walking test (p < 0.001), and modified British Medical Research Council (p < 0.001) showed enhanced exercise tolerance. FEV₁ improved, but the difference was not statistically significant.

Conclusions

Small airway dysfunction is associated with bronchodilator responsiveness. Glycopyrronium bromide has proven to be capable of inducing favorable effects on lung hyperinflation and its functional and clinical consequences, with a decrease in dyspnea and an increase in exercise capacity. The use of anticholinergic drugs is useful in the management of small airway disease.

A breath of not so fresh air…

Despite being widely used as a recreational drug, "poppers" lack a legal framework for their delivery. Their composition may vary largely. This report describes a case of severe bronchiolitis following amyl nitrite mixture inhalation. https://bit.ly/3p3S7LM.

Characterization of Immunopathology and Small Airway Remodeling in Constrictive Bronchiolitis

Rationale: Constrictive bronchiolitis (ConB) is a relatively rare and understudied form of lung disease whose underlying immunopathology remains incompletely defined. Objectives: Our objectives were to quantify specific pathological features that differentiate ConB from other diseases that affect the small airways and to investigate the underlying immune and inflammatory phenotype present in ConB. Methods: We performed a comparative histomorphometric analysis of small airways in lung biopsy samples collected from 50 soldiers with postdeployment ConB, 8 patients with sporadic ConB, 55 patients with chronic obstructive pulmonary disease, and 25 nondiseased control subjects. We measured immune and inflammatory gene expression in lung tissue using the NanoString nCounter Immunology Panel from six control subjects, six soldiers with ConB, and six patients with sporadic ConB. Measurements and Main Results: Compared with control subjects, we found shared pathological changes in small airways from soldiers with postdeployment ConB and patients with sporadic ConB, including increased thickness of the smooth muscle layer, increased collagen deposition in the subepithelium, and lymphocyte infiltration. Using principal-component analysis, we showed that ConB pathology was clearly separable both from control lungs and from small airway disease associated with chronic obstructive pulmonary disease. NanoString gene expression analysis from lung tissue revealed T-cell activation in both groups of patients with ConB with upregulation of proinflammatory pathways, including cytokine-cytokine receptor interactions, NF-κB (nuclear factor-κB) signaling, TLR (Toll-like receptor) signaling, T-cell receptor signaling, and antigen processing and presentation. Conclusions: These findings indicate shared immunopathology among different forms of ConB and suggest that an ongoing T-helper cell type 1-type adaptive immune response underlies airway wall remodeling in ConB.

Prevalence and comorbidities of bronchiolitis in adults: A population-based study in South Korea

Bronchiolitis generally refers to inflammation and/or fibrosis of the non-cartilaginous small airways located approximately from the 8th airway generation down to the terminal and respiratory bronchioles. In contrast to young children, the frequency of small airway infection in adult bronchiolitis appears less frequent and a number of other pathophysiological conditions have been implicated in adult bronchiolitis. However, little information is available on the exact medical burden of bronchiolitis such as its prevalence and comorbidities in the adult population. The aim of this study is to elucidate the prevalence and comorbidities of bronchiolitis. We used the Korea National Health Insurance Service-National Sample Cohort, which provides data for 1,000,000 individuals out of the entire population by 2% stratified random sampling according to age, sex, residential area, and level of household income. We defined the cause of bronchiolitis other than acute infection as a patient with diagnostic code J448 or J684 and over 20 years of age who visited a clinic or hospital in South Korea. Then, 1:1 propensity score matching was performed to define a non-bronchiolitis (control) group to compare the comorbidities and mortality in the 2 groups. The overall prevalence of bronchiolitis was 688 cases/1,000,000 population during the study period (95% confidence interval, 625-751). The most common comorbid clinical condition in adults with bronchiolitis was rhinitis (52.3%), followed by bronchial asthma (52.23%), hypertension (43.69%), gastroesophageal reflux disease (30.56%), sinusitis (28.72%), diabetes (22.77%), and osteoporosis (17.85%). Other common bronchiolitis-associated comorbidities were cerebrovascular disease (16.86%), angina (14.37%), peripheral vascular disease (13.42%), congestive heart failure (11.9%), and malignancy in any organ (10.6%). Healthcare costs for bronchiolitis increased steeply during the same period. Malignancy in any organ was the leading cause of mortality in the patient group, followed by bronchiolitis itself. Further larger prospective multiethnic cohort studies should be carried out in the near future.

Clinical characteristics associated with small airways disease in systemic sclerosis

Objective:

Pulmonary manifestations of systemic sclerosis are a major cause of morbidity and mortality. Small airways disease can cause dyspnea and pulmonary function test abnormalities. We aimed to determine the prevalence of small airways disease and describe the characteristics associated with small airways disease in a cohort of systemic sclerosis patients.

Methods:

We performed a retrospective cohort study of adults with systemic sclerosis who met American College of Rheumatology/European League Against Rheumatism 2013 classification criteria and were evaluated at our institution between November 2000 and November 2015. Patients with prior lung transplantation were excluded. Small airways disease was defined as the presence of one or more of the following: airway-centered fibrosis on surgical lung biopsy, forced expiratory volume at 25–75% ⩽ 50% on pulmonary function tests, and/or high-resolution computed tomography scan of the chest with bronchiolitis, mosaic attenuation, or air trapping on expiratory views. The primary outcome was small airways disease diagnosis. We performed multivariable logistic regression to determine the association of clinical variables with small airways disease.

Results:

One-hundred thirty-six systemic sclerosis patients were included; 55 (40%) had small airways disease. Compared to those without small airways disease, a significantly greater proportion of those with small airways disease had interstitial lung disease, chronic obstructive pulmonary disease, pulmonary hypertension, and gastroesophageal reflux disease. On multivariable analysis, pulmonary hypertension (odds ratio = 2.91, 95% confidence interval = 1.11–7.65, p-value = 0.03), gastroesophageal reflux disease (odds ratio = 2.70, 95% confidence interval = 1.08–6.79, p-value = 0.034), and anti-topoisomerase I (anti-Scl-70) antibody positivity (odds ratio = 0.42, 95% confidence interval = 0.19–0.93, p-value = 0.033) were associated with diagnosis of small airways disease.

Conclusion:

Small airways disease is prevalent among systemic sclerosis patients; those with pulmonary hypertension or gastroesophageal reflux disease may have a higher risk of small airways disease.

Small airway disease and its predictors in patients with rheumatoid arthritis

BACKGROUND

Rheumatoid arthritis (RA) is a connective tissue disease, characterized by symmetric peripheral polyarthritis. Extra-articular disease occurs in approximately 50% of the patients with lung being a common site. The presence of functional or morphological abnormalities in small airways has recently been noted in patients with RA but its exact prevalence and clinical significance is still a subject of debate. This study was aimed to determine the prevalence of small airway disease (SAD) in patients with RA and the factors influencing it.

METHODS

Fifty consecutive patients with RA were included in this cross-sectional observational study. All patients were subjected to pulmonary function tests (PFT) including Spirometry and Forced Oscillation technique (FOT). Those with features of SAD on PFT were subjected to High-Resolution Computed Tomography (HRCT) of the chest.

RESULTS

Spirometry was suggestive of SAD in 17 patients, with 34% prevalence and FOT was abnormal in 9 patients, with 18% prevalence in the study population. Of 17 patients with SAD on spirometry, 8 (47.05%) patients showed mosaic attenuation, a sign of SAD on the HRCT chest. On univariate analysis, age, Disease Activity Score (DAS-28), joint erosions on X-ray, RF and anti-CCP were found to be associated with SAD.

CONCLUSION

SAD was present in one-third of the patients with RA, even in those with short duration of disease, low to moderate disease activity and no respiratory symptoms. It is thus inferred that the complete workup of RA patients should include pulmonary function assessment.

Pathological and clinical relevance of selective recruitment of Langerhans cells in the respiratory bronchioles of smokers

BACKGROUND

Smoking causes an influx of inflammatory cells including Langerhans cells (LCs) into the airways and lung parenchyma, thus inducing histological changes, such as emphysema and fibrosis. We examined the distribution and quantity of Langerhans cells in relation to clinical and pathological findings and explored the association between smoking and accumulation of Langerhans cells in the respiratory bronchioles.

METHODS

Fifty-three patients who underwent lung resection for primary diseases, including lung cancer, were recruited. Histological and immunohistochemistry analyses were utilized to identify CD1a-positive Langerhans cells in peripheral lung specimens separated from primary lesions. Clinical characteristics, pathological changes, and distribution of CD1a-positive Langerhans cells distribution were assessed.

RESULTS

Of the 53 patients, 35 were smokers and 18 were non-smokers. The number of Langerhans cells in the respiratory bronchioles was significantly increased in smokers as compared to that in non-smokers (p < 0.001). The number of Langerhans cells in smokers was significantly higher in patients with mild emphysema than in those without emphysema (p < 0.01). The high-LC group showed more frequent smoking-related histological changes, such as respiratory bronchiolitis, parenchymal fibrosis, accumulation of macrophages, and smoking-related interstitial fibrosis, than the low-LC group. However, there were no differences in the smoking indices and pulmonary functions of the groups.

CONCLUSIONS

Selective accumulation of Langerhans cells in the respiratory bronchioles of smokers may lead to the development of smoking-related pathological changes.

Club Cell Loss as a Feature of Bronchiolization in ILD

Background: Distal airway metaplasia may precede honeycombing in progressive fibrosing interstitial lung disease (ILD). The SCGB1A1⁺ bronchiolar-specific club cell may play a role in this aberrant regenerative process.

Objective: To assess the presence of club cells in the small airways of patients suffering from ILD.

Methods: Small airways (internal diameter <2 mm) in lung samples [surgical lung biopsy (SLB) and/or transbronchial lung cryobiopsy (TBLC)] from 14 patients suffering from ILD and 10 controls were morphologically assessed and stained for SCGB1A1. SCGB1A1 was weighted by epithelial height as a marker of airway generation (SCGB1A1/EH). Correlations between clinical, functional, and high-resolution CT (HRCT) prognostic factors and histomorphometry were assessed.

Results: Small airways from samples with ILD patterns were significantly less dense in terms of SCGB1A1⁺ cells [0.064 (0.020–0.172)] as compared to controls' sample's small airways [0.393 (0.082–0.698), p < 0.0001]. Usual interstitial pneumonia (UIP) patterns most frequently contained small airways with limited or absent SCGB1A1 expression (SCGB1A1/EH <0.025): UIP (18/33; 55%) as compared with non-UIP patterns (4/31; 13%) or controls (0/29; 0%): p < 0.0001. In addition, correlations with HRCT indicated a significant negative relationship between SCGB1A1 and bronchiectasis as a feature of bronchiolization (Rho −0.63, p < 0.001) and a positive relationship with both forced vital capacity (FVC) and Hounsfield unit (HU)-distribution pattern in kurtosis (Rho 0.38 and 0.50, respectively, both p < 0.001) as markers of fibrotic changes.

Conclusion: Compared with controls, the small airways of patients with ILD more often lack SCGB1A1, especially so in UIP. Low densities of SCGB1A1-marked cells correlate with bronchiectasis and fibrotic changes. Further research investigating SCGB1A1 staining as a pathological feature of the bronchiolization process is merited.

Respiratory Health after Military Service in Southwest Asia and Afghanistan. An Official American Thoracic Society Workshop Report

Since 2001, more than 2.7 million U.S. military personnel have been deployed in support of operations in Southwest Asia and Afghanistan. Land-based personnel experienced elevated exposures to particulate matter and other inhalational exposures from multiple sources, including desert dust, burn pit combustion, and other industrial, mobile, or military sources. A workshop conducted at the 2018 American Thoracic Society International Conference had the goals of: 1) identifying key studies assessing postdeployment respiratory health, 2) describing emerging research, and 3) highlighting knowledge gaps. The workshop reviewed epidemiologic studies that demonstrated more frequent encounters for respiratory symptoms postdeployment compared with nondeployers and for airway disease, predominantly asthma, as well as case series describing postdeployment dyspnea, asthma, and a range of other respiratory tract findings. On the basis of particulate matter effects in other populations, it also is possible that deployers experienced reductions in pulmonary function as a result of such exposure. The workshop also gave particular attention to constrictive bronchiolitis, which has been reported in lung biopsies of selected deployers. Workshop participants had heterogeneous views regarding the definition and frequency of constrictive bronchiolitis and other small airway pathologic findings in deployed populations. The workshop concluded that the relationship of airway disease, including constrictive bronchiolitis, to exposures experienced during deployment remains to be better defined. Future clinical and epidemiologic research efforts should address better characterization of deployment exposures; carry out longitudinal assessment of potentially related adverse health conditions, including lung function and other physiologic changes; and use rigorous histologic, exposure, and clinical characterization of patients with respiratory tract abnormalities.

Occupational exposures in constrictive bronchiolitis

Bronchiolitis obliterans is a clinical entity which results from a variety of etiologies and has a detrimental impact on patients' quality of life when it remains undiagnosed and untreated. Due to its non-pathognomic clinical symptoms and signs, physicians often proceed to radiological examination, especially with high resolution chest tomography. Histological examination reveals constrictive bronchiolitis, the pathological definition of bronchiolitis obliterans. Due to an almost normal aspect of the lung parenchyma this condition can be missed. However, its recognition and the identification of a possible exposure are important for removing the patient from the incriminating agent. We present a case of constrictive bronchiolitis in a metal-cutting worker, highlighting the principal findings of this disease.

Recent advances in the understanding of bronchiolitis in adults

Bronchiolitis is injury to the bronchioles (small airways with a diameter of 2 mm or less) resulting in inflammation and/or fibrosis. Bronchioles can be involved in pathologic processes that involve predominantly the lung parenchyma or large airways, but, in some diseases, bronchioles are the main site of injury ("primary bronchiolitis"). Acute bronchiolitis caused by viruses is responsible for most cases of bronchiolitis in infants and children. In adults, however, there is a wide spectrum of bronchiolar disorders and most are chronic. Many forms of bronchiolitis have been described in the literature, and the terminology in this regard remains confusing. In clinical practice, a classification scheme based on the underlying histopathologic pattern (correlates with presenting radiologic abnormalities) facilitates the recognition of bronchiolitis and the search for the inciting cause of the lung injury. Respiratory bronchiolitis is the most common form of bronchiolitis in adults and is usually related to cigarette smoking. Currently, the diagnosis of respiratory bronchiolitis is generally achieved based on the clinical context (smoking history) and chest CT findings. Constrictive (obliterative) bronchiolitis is associated with airflow obstruction and is seen in various clinical contexts including environmental/occupational inhalation exposures, transplant recipients (bronchiolitis obliterans syndrome), and many others. Diffuse idiopathic pulmonary neuroendocrine cell hyperplasia (DIPNECH) is increasingly recognized and can be associated with progressive airflow obstruction related to constrictive bronchiolitis ("DIPNECH syndrome"). Diffuse aspiration bronchiolitis is a form of aspiration-related lung disease that is often unsuspected and confused for interstitial lung disease. Novel forms of bronchiolitis have been described, including lymphocytic bronchiolitis and alveolar ductitis with emphysema recently described in employees at a manufacturing facility for industrial machines. Bronchiolitis is also a component of vaping-related lung injury encountered in the recent outbreak.

Regional differences in airway susceptibility to cigarette smoke: An investigational case study of epithelial function and gene alterations inin vitroairway epithelial three-dimensional cultures

Cigarette smoke (CS) is a risk factor contributing to lung remodeling in chronic obstructive pulmonary disease (COPD). COPD is a heterogeneous disease because many factors contribute in varying degrees to the resulting airflow limitations in different regions of the respiratory tract. This heterogeneity makes it difficult to understand mechanisms behind COPD development. In the current study, we investigate the regional heterogeneity of the acute response to CS exposure between large and small airways using in vitro three-dimensional (3D) cultures. We used two in vitro 3D human airway epithelial tissues from large and small airway epithelial cells, namely, MucilAir™ and SmallAir™, respectively, which were derived from the same single healthy donor to eliminate donor differences. Impaired epithelial functions and altered gene expression were observed in SmallAir™ exposed to CS at the lower dose and earlier period following the last exposure compared with MucilAir™. In addition, severe damage in SmallAir™ was retained for a longer duration than MucilAir™. Transcriptomic analysis showed that although well-known CS-inducible biological processes (i.e. inflammation, cell fate, and metabolism) were disturbed with consistent activity in both tissues exposed to CS, we elucidated distinctively regulated genes in only MucilAir™ and SmallAir™, which were mostly related to catalytic and transporter activities. Our findings suggest that CS exposure elicited epithelial dysfunction through almost the same perturbed pathways in both airways; however, they expressed different genes related to metabolic and transporter activities in response to CS exposure which may contribute to cytotoxic heterogeneity to the response to CS in the respiratory tract.

The pathology of small airways disease in COPD: historical aspects and future directions

Small airways disease (SAD) is a cardinal feature of chronic obstructive pulmonary disease (COPD) first recognized in the nineteenth century. The diverse histopathological features associated with SAD underpin the heterogeneous nature of COPD. Our understanding of the key molecular mechanisms which drive the pathological changes are not complete. In this article we will provide a historical overview of key histopathological studies which have helped shape our understanding of SAD and discuss the hallmark features of airway remodelling, mucous plugging and inflammation. We focus on the relationship between SAD and emphysema, SAD in the early stages of COPD, and the mechanisms which cause SAD progression, including bacterial colonization and exacerbations. We discuss the need to specifically target SAD to attenuate the progression of COPD.

Clinico- pathologic presentation of hypersensitivity pneumonitis in Egyptian patients: a multidisciplinary study

BACKGROUND

Hypersensitivity pneumonitis (HP) is a common diffuse parenchymal lung disease in Egypt which can be difficult to recognize due to the dynamic symptoms & associated environmental factors.

METHODS

Forty-three Egyptian patients were enrolled in this study, presenting with dyspnea and cough, predominant ground-glass opacity (GGO) in high-resolution computed tomography (HRCT) where lung biopsy was needed to establish the diagnosis.

RESULTS

The age range was 15 to 60 years. Females represented 90.7% (39 patients) while 9.3% (4 patients) of our patients were males. History of contact with birds was detected in 9 (20.9%) patients. Most of our patients (60.5%) didn't have exposure history, and only 8 patients (18.6%) were living in geographic areas in Egypt that are known for the exposure to environmental etiologic factors (cane sugar exhaust fumes). The most common HRCT pattern was GGO with mosaic parenchyma in 18 patients (41.86%), followed by GGO with centrilobular nodules in 9 patients (20.93%), then isolated diffuse GGO in 5 patients (11.62%), GGO with traction bronchiectasis in 4 patients (9.3%), GGO with consolidation in 3 patients (6.97%), GGO with reticulations in 2 patients (4.65%), and GGO with cysts in 2 patients (4.65%). The most common histologic finding was isolated multinucleated giant cells in 38 patients (88.3%) commonly found in airspaces (24 patients) and less commonly in the interstitium (14 patients), followed by interstitial pneumonia and cellular bronchiolitis in 36 patients (83.7% each), interstitial ill-formed non-necrotizing granulomas in 12 patients (27.9%), fibrosis in 10 patients (23.2%), and organizing pneumonia pattern in 4 patients (9.3%).

CONCLUSION

The diagnosis of HP presenting with predominant GGO pattern in HRCT requires a close interaction among clinicians, radiologists, and pathologists. Some environmental and household factors may be underestimated as etiologic factors. Further environmental and genetic studies are needed especially in patients with negative exposure history.

Establishment and characterization of an in vitro human small airway model (SmallAir™)

We report here the establishment and characterization of an in vitro human small airway model (SmallAir™). The epithelial cells were isolated from the distal lungs by enzymatic digestion. After amplification, the cells were seeded on the microporous membrane of Transwell inserts. Once confluent, the cultures were switched to air-liquid interface. After 3weeks of culture, the epithelium became fully differentiated, with morphology of columnar epithelium, and a thickness of 10-15μm. Most significantly, CC-10, a specific marker of Club cells, was highly expressed in SmallAir™. CC-10 was detected by both immune-cytochemistry and Western Blot. As expected, SmallAir™ contained few Muc5-Ac positive cells (goblet cells). In contrast, CC-10 was not detected in MucilAir™, an in vitro model of the human nasal and bronchial epithelial model. Instead, Muc5-Ac was highly expressed in MucilAir™. However, both MucilAir™ and SmallAir™ contain basal cells and ciliated cells, showing cilia beating and mucociliary clearance. Clearly, MucilAir™ and SmallAir™ are two distinct airway epithelial models.

Follicular Bronchiolitis in a Nigerian Female Child: A Case Report and Review of the Literature

Small airways diseases are not uncommon in childhood. They account for about 28.4% of hospital admissions for lower respiratory tract infections in South West Nigeria, most of which are due to respiratory syncytial virus (RSV) infection. Noninfectious causes of small airways diseases, on the other hand, are poorly recognized and rarely feature in the differential diagnoses of chronic/recurrent lower respiratory tract disease in our environment. We present a case of follicular bronchiolitis in a 2.5-year-old Nigerian female who had left upper lobectomy on account of recurrent cough and progressive shortness of breath.

Should lung biopsies be performed in patients with severe asthma?

Asthma, and severe asthma, in particular, is increasingly recognised as a heterogeneous disease. Identifying these different phenotypes of asthma and assigning patients to phenotype-specific treatments is one of the current conundrums in respiratory medicine. Any diagnostic procedure in severe asthma (or any disease) should have two aims: 1) better understanding or identifying the diagnosis, and 2) providing information on the heterogeneity of asthma phenotypes to guide therapy with the objective of improving outcomes. Lung biopsies can target the large and small airways as well as the lung parenchyma. All compartments are affected in severe asthma; however, knowledge on the distal lung is limited. At this point, it remains uncertain whether lung specimens routinely add diagnostic information that is unable to be obtained otherwise. Indeed, whether a lung biopsy is indicated in the workup of a patient with severe asthma remains an individual decision. It is hoped this review will support rational decision-making and provide a detailed synopsis of the varied histopathological features seen in biopsies of patients with a diagnosis of severe asthma. Due to limited data on this topic this review is primarily based on opinion with recommendations arising primarily from the personal experience of the authors.

The relation between CT findings and sputum microbiology studies in active pulmonary tuberculosis

PURPOSE

To evaluate whether CT findings suggesting active pulmonary tuberculosis correlate with sputum microbiological studies, and to determine whether CT could predict infectivity.

MATERIALS AND METHODS

Total 108 patients with active pulmonary tuberculosis were enrolled. We reviewed CT findings and sputum microbiological studies. Then, we analyzed the statistical difference in CT findings between the positive and negative groups of each sputum microbiological study (AFB smear, PCR, and culture). Also, we divided the patients into five groups according to sputum AFB smear grade and analyzed linear trends of CT findings between the five groups.

RESULTS

Both frequencies and extents of centrilobular micronodules (63% vs 38%, p=0.011 for frequency; 1.6 ± 1.6 vs 0.6 ± 1.1, p=0.001 for extent), tree-in-bud opacities (63% vs 33%, p=0.002; 1.6 ± 1.6 vs 0.5 ± 0.9, p<0.001, respectively), consolidation (98% vs 81%, p=0.003; 2.7 ± 1.5 vs 1.3 ± 1.1, p<0.001, respectively), and cavitation (86% vs 33%, p<0.001; 1.5 ± 1.2 vs 0.4 ± 0.7, p<0.001, respectively), were significantly increased in the sputum AFB-positive group than in the negative group. These four CT findings were increase in frequency and extent in the sputum PCR-positive group with or without statistical significance. They did not show significant differences between the sputum culture-positive and negative groups. As the AFB smear grade increased, frequencies and extents of centrilobular micronodules, tree-in-bud, consolidation, and cavitation also increased.

CONCLUSION

CT features representing active tuberculosis-centrilobular nodules, tree-in-bud, consolidation, and, cavitation-strongly correlate with the positivity and grading of AFB smear.

Imaging of small airways and emphysema

High-resolution chest computed tomography (CT) is one of the most useful techniques available for imaging bronchiolitis because it shows highly specific direct and indirect imaging signs. The distribution and combination of these various signs can further classify bronchiolitis as either cellular/inflammatory or fibrotic/constrictive. Emphysema is characterized by destruction of the airspaces, and a brief discussion of imaging findings of this class of disease is also included. Typical CT findings include destruction of airspace, attenuated vasculatures, and hyperlucent as well as hyperinflated lungs.

Severe airflow obstruction in a patient with ulcerative colitis and toxic epidermal necrolysis: A case report

Bronchiolitis is a rare condition mainly affecting the intralobular conducting and transitional small airways. The present study describes a case of severe airflow limitation in a patient with ulcerative colitis who developed toxic epidermal necrolysis following mesalazine therapy. Forced expiratory volume in one second was decreased and a flow-volume curve showed airflow limitation, but the single-breath diffusing capacity of the lung for carbon monoxide (DL_CO) and DL_CO divided by alveolar volume (DL_CO/VA) were not decreased. This rare clinical condition should be considered as a differential diagnosis for subjects presenting with sub-acutely developed airflow obstruction if the findings in chest computed tomography scans demonstrate hyperinflation but few low-attenuation areas. Relatively well-preserved DL_CO and DL_CO/VA provide a clue to establishing the correct diagnosis.

Clinicoradiologic evidence of pulmonary lymphatic spread in adult patients with tuberculosis

OBJECTIVE

The purpose of this study is to evaluate the prevalence and clinicoradiologic characteristics of pulmonary tuberculosis with lymphatic involvement.

MATERIALS AND METHODS

A total of 126 adults with active tuberculosis who underwent CT were enrolled. A retrospective investigation of CT images focused on the presence of perilymphatic micronodules, as well as other CT features of active tuberculosis. We selected two groups of patients with micronodules according to distribution (perilymphatic vs centrilobular). We compared clinical and CT findings between the two groups.

RESULTS

Fifteen patients were excluded because of coexisting pulmonary disease. Among 111 patients, the prevalence of perilymphatic micronodules, galaxy or cluster signs, and interlobular septal thickening was 64 (58%), 18 (16%), and 30 (27%), respectively. Of 106 patients with micronodules, 37 and 40 were classified into the perilymphatic and centrilobular groups, respectively. Compared with the centrilobular group, the perilymphatic group had statistically significantly lower frequencies of positive acid-fast bacilli smears (32% vs 70%), consolidation (70% vs 98%), and cavitation (30% vs 60%). However, frequencies of interlobular septal thickening (41% vs 18%), galaxy or cluster signs (30% vs 0%), and pleural effusion (43% vs 20%) were statistically significantly higher in the perilymphatic group.

CONCLUSION

CT findings representing pulmonary perilymphatic involvement are relatively common in adults with tuberculosis. These findings may represent lymphatic spread of tuberculosis and provide an explanation for the unusual CT features of pulmonary tuberculosis mimicking sarcoidosis and the low detection of Mycobacterium tuberculosis in patients with micronodules.

Humidifier disinfectant-associated children's interstitial lung disease

RATIONALE

Beginning in 2006, epidemics of a fatal lung injury of unknown cause in children were observed in Korea every spring. A recent study demonstrated that this type of children's interstitial lung disease (chILD) is associated with humidifier disinfectant use.

OBJECTIVES

To determine the clinical characteristics of this type of chILD and to assess whether the nationwide suspension of humidifier disinfectant sales in the autumn of 2011 affected its incidence.

METHODS

The clinical characteristics of suspected cases between 2006 and 2011 were determined by a nationwide retrospective study. The potential causal relationship with humidifier disinfectants was examined by a prospective surveillance study after humidifier disinfectant sales were suspended.

MEASUREMENTS AND MAIN RESULTS

In total, 138 children were diagnosed with this type of chILD, which was characterized by rapid progression, high mortality, predominance in the spring season, and a familial tendency. The annual incidence increased in 2011 and then dropped to zero in 2012. The children were on average 30.4 months old. The most frequent symptoms at admission were cough and dyspnea. As the disease progressed, the typical complication was spontaneous air leak. Eighty children (58%) died. Two years after humidifier disinfectant-sale suspension, no more new cases were found.

CONCLUSIONS

This study suggests that humidifier disinfectant inhalation causes an idiopathic type of chILD that is characterized by spontaneous air leak, rapid progression, lack of response to treatment, and high mortality. Further safety studies must be performed on common environmental compounds, particularly those that enter the human body by an unusual route.

Suctioning and length of stay in infants hospitalized with bronchiolitis

IMPORTANCE

Hospitalizations of infants for bronchiolitis are common and costly. Despite the high incidence and resource burden of bronchiolitis, the mainstay of treatment remains supportive care, which frequently includes nasal suctioning.

OBJECTIVE

To examine the association between suctioning device type and suctioning lapses greater than 4 hours within the first 24 hours after hospital admission on length of stay (LOS) in infants with bronchiolitis.

DESIGN

Retrospective cohort study. Data were extracted from the electronic health record.

SETTING

Main hospital and satellite facility of a large quaternary care children's hospital from January 10, 2010, through April 30, 2011.

PARTICIPANTS

A total of 740 infants aged 2 to 12 months and hospitalized with bronchiolitis.

MAIN OUTCOME MEASURE

Hospital LOS.

RESULTS

In the multivariable model adjusted for inverse weighting for propensity to receive deep suctioning, increased deep suction as a percentage of suction events was associated with increased LOS with a geometric mean of 1.75 days (95% CI, 1.56-1.95 days) in patients with no deep suction and 2.35 days (2.10-2.62 days) in patients with more than 60% deep suction. An increased number of suctioning lapses was also associated with increased LOS in a dose-dependent manner with a geometric mean of 1.62 days (95% CI, 1.43-1.83 days) in patients with no lapses and 2.64 days (2.30-3.04 days) in patients with 3 or 4 lapses.

CONCLUSIONS AND RELEVANCE

For patients admitted with bronchiolitis, the use of deep suctioning in the first 24 hours after admission and lapses greater than 4 hours between suctioning events were associated with longer LOS.

FEV1 over time in patients with connective tissue disease-related bronchiolitis

BACKGROUND

Fibrosis or inflammation of the bronchioles is a well-known manifestation of connective tissue disease (CTD). However, the natural history of CTD-related bronchiolitis is largely unknown.

METHODS

We analyzed consecutive patients evaluated at National Jewish Health (Denver, CO) from 1998 to 2008 with CTD and surgical lung biopsy-confirmed bronchiolitis. Linear mixed effects models were used to estimate the longitudinal postbronchodilator FEV1 %predicted (%pred) course and differences between subjects with or without constrictive bronchiolitis (CB).

RESULTS

Of 28 subjects with a mean age of 53 ± 9 years, fourteen (50%) had CB. The most common CTD diagnosis was rheumatoid arthritis (n = 14; 50%). There were no significant differences in demographics, smoking status, underlying CTD diagnoses, 6-min walk distance, dyspnea score or drug therapy between subjects with CB and those with cellular bronchiolitis. Three subjects with CB (11%) and four with cellular bronchiolitis (14%) died. Compared with subjects with CB, those with cellular bronchiolitis had higher mean FEV1 %pred at all times. There were no significant differences in FEV1 %pred slope within- or between-groups (CB vs. cellular bronchiolitis) preceding surgical lung biopsy or afterward.

CONCLUSION

Subjects with CTD-related CB had lower FEV1 %pred values than those with CTD-related cellular bronchiolitis at all time points, but FEV1 %pred remained stable over time in both groups regardless of therapy received.

CCAAT/enhancer binding protein-α regulates the protease/antiprotease balance required for bronchiolar epithelium regeneration

Many transcription factors that regulate lung morphogenesis during development are reactivated to mediate repairs of the injured adult lung. We hypothesized that CCAAT/enhancer binding protein-α (C/EBPα), a transcription factor critical for perinatal lung maturation, regulates genes required for the normal repair of the bronchiolar epithelium after injury. Transgenic Cebpα(Δ/Δ) mice, in which Cebpa was conditionally deleted from Clara cells and Type II cells after birth, were used in this study. Airway injury was induced in mice by the intraperitoneal administration of naphthalene to ablate bronchiolar epithelial cells. Although the deletion of C/EBPα did not influence lung structure and function under unstressed conditions, C/EBPα was required for the normal repair of terminal bronchiolar epithelium after naphthalene injury. To identify cellular processes that are influenced by C/EBPα during repair, mRNA microarray was performed on terminal bronchiolar epithelial cells isolated by laser-capture microdissection. Normal repair of the terminal bronchiolar epithelium was highly associated with the mRNAs regulating antiprotease activities, and their induction required C/EBPα. The defective deposition of fibronectin in Cebpα(Δ/Δ) mice was associated with increased protease activity and delayed differentiation of FoxJ1-expressing ciliated cells. The fibronectin and ciliated cells were restored by the intratracheal treatment of Cebpα(Δ/Δ) mice with the serine protease inhibitor. In conclusion, C/EBPα regulates the expression of serine protease inhibitors that are required for the normal increase of fibronectin and the restoration of ciliated cells after injury. Treatment with serine protease inhibitor may aid in the recovery of injured bronchiolar epithelial cells, and prevent common chronic lung diseases.

Bronchiolitis and bronchial disorders in interstitial lung disease

PURPOSE OF REVIEW

Bronchial and bronchiolar abnormalities in interstitial lung diseases (ILDs) are an issue often underestimated. However, new interstitial patterns with bronchiolar involvement are being described and the concept is still evolving. The scope of this review is to introduce a comprehensive approach to airway disorders in the context of ILDs, mainly from a pathologic perspective.

RECENT FINDINGS

Recent studies have revealed significant inflammatory and structural alterations at the level of small airways in idiopathic interstitial pneumonias, which may participate in the lung-remodeling pathogenetic process. A suggested pathogenetic role of cigarette smoking for lung-remodeling in smoking-related ILDs is further investigated, and unclassified fibrosis as a prominent feature in lung biopsy specimens of smokers has been established. New targeted therapies for lymphangioleiomyomatosis based on molecular and biologic properties of the disease are currently undergoing clinical trials. Combined pharmaceutical and interventional therapeutic regimens are of growing concern for refractory airway lesions in sarcoidosis. The application of volumetric high-resolution computed tomography (HRCT) chest scanning with acquisition of expiratory images provides valuable information about the involvement of small airways in ILDs.

SUMMARY

The imaging and pathologic focus on airway abnormalities in ILDs make them an integral part of their pathology with a significant pathogenetic role in interstitial processes and variable contribution to the functional status of patients.

Macropinocytosis of extracellular glutathione ameliorates tumor necrosis factor α release in activated macrophages

A number of inflammatory lung diseases have abnormally low glutathione (GSH) levels in the airway fluids. Lung macrophages are common mediators of inflammation, make up the majority of cells that are found in the airway epithelial lining fluid (ELF), and are commonly elevated in many lung diseases. Several animal models with altered ELF GSH levels are associated with similar alterations in the intracellular GSH levels of bronchoalveolar lavage (BAL) cells. The possible mechanisms and outcomes for this association between ELF GSH levels and intracellular BAL cell GSH are unknown. To investigate these issues, macrophages were grown in media supplemented with 500 µM GSH. GSH supplementation resulted in a 2–3 fold increase in macrophage intracellular GSH levels. The increase in macrophage intracellular GSH levels was associated with a significant reduction in NF-κB nuclear translocation and tumor necrosis factor α (TNFα) release upon LPS stimulation. Furthermore, co-treatment of macrophages with GSH and inhibitors of GSH breakdown or synthesis did not block GSH accumulation. In contrast, treatment with cytochalasin D, an inhibitor of actin dependent endocytosis, and amiloride, an inhibitor of macropinocytosis blocked, at least in part, GSH uptake. Furthermore, using two cigarette smoke exposure paradigms that result in two different GSH levels in the ELF and thus in the BAL cells resulted in modulation of cytokine release when stimulated with LPS ex vivo. These data suggest that macrophages are able to utilize extracellular GSH which can then modulate inflammatory signaling in response to proinflammatory stimuli. This data also suggests the lung can modulate inflammatory responses triggered by proinflammatory stimuli by altering ELF GSH levels and may help explain the dysregulated inflammation associated with lung diseases that have low ELF GSH levels.

Smoking-related Small airway disease--a review and update

The term "small airway disease" has been used in reference to abnormalities occurring secondary to cigarette smoking in the context of chronic obstructive pulmonary disease (COPD), and the small airways are the major site of obstruction in patients with COPD. The histologic features associated with smoking-related small airway disease are largely nonspecific and overlap with those of other bronchiolitides. The pathogenesis of smoking-related small airway disease is poorly understood; however, insights into the development of airway remodeling and matrix production continue to evolve. The aim of this article will be to review the histologic findings and pathogenesis of smoking-related small airway disease in the context of COPD, and review other small airway disorders affecting cigarette smokers, namely respiratory bronchiolitis and Langerhans cell histiocytosis, and a newly described entity of respiratory bronchiolitis with fibrosis and associated issues with this entity.