Bronchiolar disorders

Feasibility and safety of fiber optic micro-imaging in canine peripheral airways

PURPOSE

To assess the feasibility and safety of imaging canine peripheral airways (<1 mm) with an experimental micro-imaging fiber optic bronchoscope.

METHODS

Twenty healthy dogs were scoped with a micro-imaging fiber optic bronchoscope (0.8 mm outer diameter). Images at various levels of the bronchioles, mucosal color, and tracheal secretions were recorded. The apparatus was stopped once it was difficult to insert. CT imaging was performed simultaneously to monitor progression. The safety of the device was evaluated by monitoring heart rate (HR), respiratory rate (RR), mean artery pressure (MAP), peripheral oxygen saturation (SpO2) and arterial blood gases (partial pressure of arterial carbon-dioxide, PaCO2, partial pressure of arterial oxygen, PaO2, and blood pH).

RESULTS

(1) According to the CT scan, the micro-imaging fiber was able to access the peripheral airways (<1 mm) in canines. (2) There was no significant change in the values of HR, MAP, pH and PaCO2 during the procedure (P>0.05). Comparing pre-manipulation and post-manipulation values, SpO2 (F = 13.06, P<0.05) and PaO2 (F = 3.01, P = 0.01) were decreased, whereas RR (F = 3.85, P<0.05) was elevated during the manipulation. (3) Self-limited bleeding was observed in one dog; severe bleeding or other complications did not occur.

CONCLUSION

Although the new apparatus had little effect on SpO2, PaO2 and RR, it can probe into small peripheral airways (<1 mm), which may provide a new platform for the early diagnosis of bronchiolar diseases.

Chronic follicular bronchiolitis requires antigen-specific regulatory T cell control to prevent fatal disease progression

To study regulatory T (Treg) cell control of chronic autoimmunity in a lymphoreplete host, we created and characterized a new model of autoimmune lung inflammation that targets the medium and small airways. We generated transgenic mice that express a chimeric membrane protein consisting of hen egg lysozyme and a hemoglobin epitope tag under the control of the Clara cell secretory protein promoter, which largely limited transgene expression to the respiratory bronchioles. When Clara cell secretory protein-membrane hen egg lysozyme/hemoglobin transgenic mice were crossed to N3.L2 TCR transgenic mice that recognize the hemoglobin epitope, the bigenic progeny developed dense, pseudo-follicular lymphocytic peribronchiolar infiltrates that resembled the histological pattern of follicular bronchiolitis. Aggregates of activated IFN-γ- and IL-17A-secreting CD4(+) T cells as well as B cells surrounded the airways. Lung pathology was similar in Ifng(-/-) and Il17a(-/-) mice, indicating that either cytokine is sufficient to establish chronic disease. A large number of Ag-specific Treg cells accumulated in the lesions, and Treg cell depletion in the affected mice led to an interstitial spread of the disease that ultimately proved fatal. Thus, Treg cells act to restrain autoimmune responses, resulting in an organized and controlled chronic pathological process rather than a progressive disease.

Diffuse cystic lung diseases

Diffuse cystic lung diseases are uncommon but can present a diagnostic challenge because increasing number of diseases have been associated with this presentation. Cyst in the lung is defined as a round parenchymal lucency with a well-defined thin wall (< 2 mm thickness). Focal or multifocal cystic lesions include blebs, bullae, pneumatoceles, congenital cystic lesions, traumatic lesions, and several infectious processes such as coccidioidomycosis, Pneumocystis jiroveci pneumonia, and hydatid disease. "Diffuse" distribution in the lung implies involvement of all lobes. Diffuse lung involvement with cystic lesions can be seen in pulmonary lymphangioleiomyomatosis, pulmonary Langerhans' cell histiocytosis, lymphoid interstitial pneumonia, Birt-Hogg-Dubé syndrome, amyloidosis, light chain deposition disease, honeycomb lung associated with advanced fibrosis, and several other rare causes including metastatic disease. High-resolution computed tomography of the chest helps define morphologic features of the lung lesions as well as their distribution and associated features such as intrathoracic lymphadenopathy. Correlating the tempo of the disease process and clinical context with chest imaging findings serve as important clues to defining the underlying nature of the cystic lung disease and guide diagnostic evaluation as well as management.

[Environmental causes of the distal airways disease. Hypersensitivity pneumonitis and rare causes]

Hypersensitivity pneumonitis is one of the most frequent causes of distal airways disease. It is associated with inflammation of the bronchioles, predominantly by lymphocytic infiltrates, and with granuloma formation causing bronchial obstruction. This inflammation explains the clinical manifestations and the airways obstruction seen on pulmonary function tests, most often in the distal airways but proximal in almost 20%. CT scan abnormalities reflect the lymphocytic infiltrates and air trapping and, in some cases, the presence of emphysema. Bronchiolitis induced by chronic inhalation of mineral particles or acute inhalation of toxic gases (such as NO2) are other examples of small airways damage due to environmental exposure. The pathophysiological mechanisms are different and bronchiolar damage is either exclusive or predominant. Bronchiolitis induced by tobacco smoke exposure, usually classified as interstitial pneumonitis, is easily diagnosed thanks to broncho-alveolar lavage. Its prognosis is linked to the other consequences of tobacco smoke exposure including respiratory insufficiency. Finally, the complex lung exposure observed in some rare cases (such as the World Trade Center fire or during wars) may lead to a less characteristic pattern of small airways disease.

[The small airways: normal histology and the main histopathological lesions]

Lesions of the small airway are observed in a wide variety of pulmonary conditions, most of which are due to infection, tobacco and connective tissue diseases. They are sometimes isolated or, more often, associated with involvement of other pulmonary structures such as the bronchi, the lung parenchyma and the pleura. The pathological spectrum of the bronchiolar response to injury is relatively limited. Thus, the same lesion is observed in various clinical settings. There is no correlation between the severity of the small airway involvement seen by the pathologist and the clinical and functional manifestations of bronchiolitis. The causes of bronchiolitis may be classified on a clinical basis, on aetiology or on histological appearance, yet no single classification appears to be suitable. An integrated clinical, radiological, functional and histological approach is needed. As they are seen by the pathologist microscopically, small airway lesions may be subdivided into three categories: (1) simple nonspecific lesions (bronchiolitis - cellular, follicular, granulomatous, obliterative, constrictive) that are never exclusively related to one clinical picture, (2) or displaying a more specific pattern like the respiratory bronchiolitis of the smoker or the histolgical changes of asthma, (3) bronchiolar lesions in conditions described as "interstitial", predominantly centrilobular, involving the small airways and the lung parenchyma, and visible radiologically. After recalling the normal histological appearances of the bronchioles, this review describes the diversity of the histopathological lesions of the small airways.

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.

A practical approach to high-resolution CT of diffuse lung disease

Diffuse lung disease presents a variety of high-resolution CT findings reflecting its complex pathology, and provides diagnostic challenge to radiologists. Frequent modification of detailed pathological classification makes it difficult to keep up with the latest understanding. In this review, we describe a practical approach to high-resolution CT diagnosis of diffuse lung disease, emphasizing (1) analysis of "distribution" of the abnormalities, (2) interpretation of "pattern" in relation to distribution, (3) utilization of associated imaging findings and clinical information, and (4) chronicity of the findings. This practical approach will help radiologists establish a way to interpret high-resolution CT, leading to pin-point diagnosis or narrower differential diagnoses of diffuse lung diseases.

Follicular bronchiolitis: A rare cause of persistent atelectasis in children

Although atelectasis is common in children, its persistence or refractoriness to treatment should lead prompt evaluation to identify causal mechanism. We describe the case of a child presenting in first year of life with persistent left upper lobe atelectasis, recurrent wheezing and respiratory infections refractory to medical therapy, submitted to partial lobectomy when he was 3 years old age. Histopathological examination revealed follicular bronchiolitis. Systemic underlying diseases were excluded. Clinical improvement was initially achieved using inhaled corticosteroids, but oral therapy was needed due to clinical relapse, with favorable response.

Follicular bronchiolitis, a rare pulmonary primary lymphoid lesion, consists of numerous reactive lymphoid follicles in a peribonchiolar distribution. Its precise cause is unknown, particularly in children, in which few cases have been reported. Treatment usually includes steroids and prognosis is generally good.

[Post-infectious bronchiolitis obliterans]

Post-infectious bronchiolitis obliterans (BO) is characterized by inflammatory and fibrotic lesions of small airways following a pulmonary infection and leading to some degree of airway obstruction. It represents a rare cause of chronic obstructive pulmonary disease, and is probably underestimated, especially when the lesions affect small areas of the lungs. The clinical features differ between children and adults. In children, adenovirus is the most frequently involved infectious agent, especially the more virulent serotypes 3, 7 and 21. The clinical and radiological signs vary widely and the functional outcome depends on the extent of the lung injury. The diagnosis is based on the medical history, the CT-scan and functional data. The treatment is symptomatic. The most severe forms may result in chronic respiratory insufficiency. In adults, the frequency of obstructive injuries of the small airways in the context of lung infection is unclear. Parenchymal lesions are often present, resulting in BO with organizing pneumonia. These lesions alter the clinical presentation and the radiographic features of the initial infectious disease and often prove difficult to diagnose and manage. Several authors have published clinical cases describing presumed efficacy of systemic corticosteroids but the data are scarce.

Aqueous fraction of Sauropus androgynus might be responsible for bronchiolitis obliterans

BACKGROUND AND OBJECTIVE

Bronchiolitis obliterans (BO) has been reported to develop following ingestion of Sauropus androgynus (SA), a leafy shrub distributed in Southeast Asia. Little is known about direct effects of SA on airway resident cells or haematopoietic cells in vitro. Identification of the SA component responsible for the development of BO would be an important key to elucidate its mechanism. We sought to elucidate the direct effects of SA on airway resident cells or haematopoietic cells and identify the SA element responsible for the pathogenesis of BO.

METHODS

SA dry powder was partitioned into fractions by solvent extraction. Human and murine monocytic cells, epithelial cells and endothelial cells were cultured with SA solution or fractions eluted from SA. We also investigated the effect of SA in vivo using a murine BO syndrome (BOS) model.

RESULTS

The aqueous fraction of SA induced significant increases of inflammatory cytokine and chemokine production from monocytic lineage cells. This fraction also induced significant apoptosis of endothelial cells and enhanced intraluminal obstructive fibrosis in allogeneic trachea allograft in the murine BOS model. We found individual differences in tumour necrosis factor α (TNF-α) production from monocytes of healthy controls stimulated by this aqueous fraction of SA, whereas it induced high-level TNF-α production from monocytes of patients with SA-induced BO.

CONCLUSIONS

These results suggest that an aqueous fraction of SA may be responsible for the pathogenesis of BO.

Histopathological analogies in chronic pulmonary lesions between cattle and humans: basis for an alternative animal model

Most of the natural cases of pneumonia in feedlot cattle are characterized by a longer clinical course due to chronic lung lesions. Microscopically, these lesions include interstitial fibroplasia, bronchitis, bronchiectasis, bronchiolitis obliterans, and epithelial metaplasia of the airways. Herein, the aim was to review, under a medical perspective, the pathologic mechanisms operating in these chronic pneumonic lesions in calves. Based on the similarities of these changes to those reported in bronchiolitis obliterans/organising pneumonia (BO/OP) and chronic obstructive pulmonary disease (COPD) in human beings, calves are proposed as an alternative animal model.

Acute fibrinous and organising pneumonia

Acute fibrinous and organising pneumonia (AFOP) was recently described as an unusual pattern of diffuse lung disease. Particular characteristics make the differential diagnosis with the well recognised clinical patterns of diffuse alveolar damage, cryptogenic organising pneumonia or eosinophilic pneumonia. The lack of hyaline membranes, the presence of intra-alveolar fibrin, absence of noticeable eosinophils and patchy distribution suggests that AFOP define a distinct histological pattern. The authors describe the case of a woman diagnosed with AFOP after surgical lung biopsy, in association with primary biliary cirrhosis. The patient presented dyspnoea, fatigue, dry cough and thoracic pain. The CT scan showed bilateral patchy infiltrates predominantly in the lower lobes. Flexible bronchoscopy and subsidiary techniques were inconclusive and biopsy through video-assisted thoracoscopic surgery led to anatomopathological diagnosis of AFOP. The patient is having a good clinical response to prednisone.

Irritant-induced airway disorders

Thousands of persons experience accidental high-level irritant exposures each year but most recover and few die. Irritants function differently than allergens because their actions proceed nonspecifically and by nonimmunologic mechanisms. For some individuals, the consequence of a single massive exposure to an irritant, gas, vapor or fume is persistent airway hyperresponsiveness and the clinical picture of asthma, referred to as reactive airways dysfunction syndrome (RADS). Repeated irritant exposures may lead to chronic cough and continual airway hyperresponsiveness. Cases of asthma attributed to repeated irritant-exposures may be the result of genetic and/or host factors.

Clinical assessment of occupational asthma and its differential diagnosis

Occupational asthma (OA) is defined as asthma caused by sources and conditions attributable to a particular occupational environment and not to stimuli encountered outside the workplace. Two types of OA are distinguished based on their appearance after a latency period or not. The most frequent type appears after a latency period leading to sensitization; the clinical assessment of this type of OA is the topic of this review. The differential diagnosis of OA is also reviewed, including work-exacerbated asthma, eosinophilic bronchitis, hyperventilation syndrome, vocal cord dysfunction, bronchiolitis, and other causes of dyspnea or cough.

Bronchial and bronchiolar fibrosis in rats exposed to 2,3-pentanedione vapors: implications for bronchiolitis obliterans in humans

2,3-Pentanedione (PD) is a component of artificial butter flavorings. The use of PD is increasing since diacetyl, a major butter flavorant, was associated with bronchiolitis obliterans (BO) in workers and has been removed from many products. Because the toxicity of inhaled PD is unknown, these studies were conducted to characterize the toxicity of inhaled PD across a range of concentrations in rodents. Male and female Wistar-Han rats and B6C3F1 mice were exposed to 0, 50, 100, or 200 ppm PD 6 h/d, 5 d/wk for up to 2 wk. Bronchoalveolar lavage fluid (BALF) was collected after 1, 3, 5, and 10 exposures, and histopathology was evaluated after 12 exposures. MCP-1, MCP-3, CRP, FGF-9, fibrinogen, and OSM were increased 2- to 9-fold in BALF of rats exposed for 5 and 10 days to 200 ppm. In mice, only fibrinogen was increased after 5 exposures to 200 ppm. The epithelium lining the respiratory tract was the site of toxicity in all mice and rats exposed to 200 ppm. Significantly, PD also caused both intraluminal and intramural fibrotic airway lesions in rats. The histopathological and biological changes observed in rats raise concerns that PD inhalation may cause BO in exposed humans.

Drug-induced interstitial lung disease in tyrosine kinase inhibitor therapy for non-small cell lung cancer: a review on current insight

PURPOSE

With recent advances in targeted therapy such as tyrosine kinase inhibitor (TKI) therapy for non-small cell lung cancer (NSCLC), pulmonary toxicity has emerged as a problem. The recognition of common CT findings and patterns of TKI-induced interstitial lung disease (ILD) is mandatory for achieving a timely diagnosis and for the appropriate management of this condition. Therefore, familiarity with this complicating ILD is crucial.

METHODS

We reviewed all published literature in the English language regarding the ILD among NSCLC patients receiving TKIs.

RESULTS

The previous reports focused on the incidence, mortality rate, and risk factors of TKI-induced ILDs. This review elaborates on the diverse CT findings and predominant patterns of ILDs associated with TKI therapy. Emphases will be given on the role of CT, in particular, for the diagnosis of the subacute or chronic appearance of ILDs. This review also offers information about the pathogenesis and risk factor for the development of TKI-induced ILD. Representative cases will be presented as a pictorial review.

CONCLUSIONS

It is important to recognize the various patterns of TKI-induced ILDs, which increase in incidence with the introduction of diverse types of molecularly targeted agents. Poor prognoses are expected when there is a short interval from the initiation of target therapy to the onset of ILD, acute interstitial pneumonia pattern of ILD, and preexisting pulmonary fibrosis.

The evolving spectrum of pulmonary disease in responders to the World Trade Center tragedy

On September 11, 2001, events at the World Trade Center (WTC) exposed residents ofNew York City to WTC dust and products of combustion and pyrolysis. The majority ofWTC-exposed fire department rescue workers experienced a substantial decline in airflowover the first 12 months post-9/11, in addition to the normal age-related declinethat affected all responders, followed by a persistent plateau in pulmonary function inthe 6 years thereafter. The spectrum of the resulting pulmonary diseases consists ofchronic inflammation, characterized by airflow obstruction, and expressing itself indifferent ways in large and small airways. These conditions include irritant-inducedasthma, non-specific chronic bronchitis, aggravated pre-existing obstructive lung disease(asthma or COPD), and bronchiolitis. Conditions concomitant with airwaysobstruction, particularly chronic rhinosinusitis and upper airway disease, and gastroesophagealreflux, have been prominent in this population. Less common have beenreports of sarcoidosis or interstitial pulmonary fibrosis. Pulmonary fibrosis and bronchiolitisare generally characterized by long latency, relatively slow progression, and asilent period with respect to pulmonary function during its evolution. For these reasons,the incidence of these outcomes may be underestimated and may increase overtime. The spectrum of chronic obstructive airways disease is broad in this populationand may importantly include involvement at the bronchiolar level, manifested as smallairways disease. Protocols that go beyond conventional screening pulmonary functiontesting and imaging may be necessary to identify these diseases in order to understandthe underlying pathologic processes so that treatment can be most effective.

[Imaging techniques in the examination of the distal airways: asthma and COPD]

Imaging techniques are highly useful diagnostic tools to study small airway diseases. Despite their differences, from a clinical pathological perspective, these diseases show similar radiological manifestations. High-resolution computed tomography (CT) is the technique of choice to study diffuse diseases and those of the small airways; the slices obtained in expiratory high-resolution CT scan should form part of the study protocol of small airway diseases. Based on the findings of high-resolution CT, small airway diseases can be divided into two large groups: (a) those presenting direct morphological signs of bronchiolar involvement, and (b) those showing indirect signs of bronchiolar involvement (air trapping/mosaic pattern). High-resolution CT is highly useful to study the complications of asthma (allergic bronchopulmonary aspergillosis) and to evaluate clinically similar processes, such as hypersensitivity pneumonitis. In asthmatic patients, multi-detector CT (MDTC) allows clinical symptoms, thickening of the airway wall and the degree of airflow obstruction to be directly correlated. MDTC is also useful for quantitative evaluation of the degree of air trapping in patients with emphysema. Magnetic resonance imaging after inhalation of distinct gases, such as (3)He and xenon-129 and dual-energy CT are also useful imaging techniques in the direct or indirect evaluation of the degree of airflow obstruction (air trapping).

Severe airway epithelial injury, aberrant repair and bronchiolitis obliterans develops after diacetyl instillation in rats

BACKGROUND

Bronchiolitis obliterans (BO) is a fibrotic lung disease that occurs in a variety of clinical settings, including toxin exposures, autoimmunity and lung or bone marrow transplant. Despite its increasing clinical importance, little is known regarding the underlying disease mechanisms due to a lack of adequate small animal BO models. Recent epidemiological studies have implicated exposure to diacetyl (DA), a volatile component of artificial butter flavoring, as a cause of BO in otherwise healthy factory workers. Our overall hypothesis is that DA induces severe epithelial injury and aberrant repair that leads to the development of BO. Therefore, the objectives of this study were 1) to determine if DA, delivered by intratracheal instillation (ITI), would lead to the development of BO in rats and 2) to characterize epithelial regeneration and matrix repair after ITI of DA.

METHODS AND MAIN RESULTS

Male Sprague-Dawley rats were treated with a single dose of DA (125 mg/kg) or sterile water (vehicle control) by ITI. Instilled DA resulted in airway specific injury, followed by rapid epithelial regeneration, and extensive intraluminal airway fibrosis characteristic of BO. Increased airway resistance and lung fluid neutrophilia occurred with the development of BO, similar to human disease. Despite rapid epithelial regeneration after DA treatment, expression of the normal phenotypic markers, Clara cell secretory protein and acetylated tubulin, were diminished. In contrast, expression of the matrix component Tenascin C was significantly increased, particularly evident within the BO lesions.

CONCLUSIONS

We have established that ITI of DA results in BO, creating a novel chemical-induced animal model that replicates histological, biological and physiological features of the human disease. Furthermore, we demonstrate that dysregulated epithelial repair and excessive matrix Tenacin C deposition occur in BO, providing new insights into potential disease mechanisms and therapeutic targets.

The lung in rheumatoid arthritis

Rheumatoid arthritis (RA) is a common inflammatory disease, affecting about 1% of the population. Although a major portion of the disease burden including excess mortality is due to its extra-articular manifestations, the prevalence of RA-associated lung disease is increasing. RA can affect the lung parenchyma, airways, and the pleura; and pulmonary complications are directly responsible for 10 to 20% of all mortality. Even though pulmonary infection and drug toxicity are frequent complications of RA, lung disease directly associated with the underlying RA is more common. The prevalence of a particular complication varies based on the characteristics of the population studied, the definition of lung disease used, and the sensitivity of the clinical investigations employed. An overview of lung disease associated with RA is presented here with an emphasis on parenchymal lung disease, pleural effusion, and airway involvement.

The role of chemokines in migration of metastatic-like lymphangioleiomyomatosis cells

Lymphangioleiomyomatosis (LAM), a rare cystic lung disease with multi-organ involvement, occurs primarily in women of childbearing age. LAM can present sporadically or in association with tuberous sclerosis complex (TSC). Loss of lung function in patients with LAM can be attributed to the dysregulated growth of LAM cells, with dysfunctional TSC1 or TSC2 genes, which encode hamartin and tuberin, respectively, leading to hyperactivation of the mammalian target of rapamycin (mTOR). LAM cells are smooth muscle-like cells that express melanoma antigens such as gp100, a splice variant of the Pmel17 gene. Tuberin and hamartin form heterodimers that act as negative regulators of mTOR. Lack of TSC2 function, as occurs in LAM cells, leads to the production of the chemokine CCL2/monocyte chemotactic protein 1 (MCP-1), which increases LAM cell mobility. Although many chemokines and their receptors could influence LAM cell mobilization, we propose that a positive-feedback loop is generated when dysfunctional TSC2 is present in LAM cells. We identified a group of chemokine receptors that is expressed in LAM cells and differs from those on smooth muscle and melanoma cells (Malme-3M). Chemokines have been implicated in tumor metastasis, and our data suggest a role for chemokines in LAM cell mobilization and thereby in the pathogenesis of LAM.

Overexpression of transforming growth factor (TGF)-beta1 and TGF-beta3 genes in lung of toxic-inhaled patients

Iraq frequently used toxic inhalants during the war with Iran, exposing over 100,000 people to chemical reagents. Bronchiolitis obliterans (BO) is a major pulmonary disease caused by exposure to harmful gases. Recently defect in clearance of apoptotic cells (efferocytosis) has been suggested as a mechanism that leads to several lung diseases. Transforming growth factor (TGF)-beta, a cytokine produced by efferocytotic macrophages, suppresses the inflammation and enhances the regeneration of tissue. In this study, the authors compared the expression of these 3 isoforms of TGF-beta at mRNA level in lung biopsies of Iranian victims of chemical gases with lung biopsies of control healthy volunteers. Semiquantitative reverse transcriptase-polymerase chain reaction (RT-PCR) technique was used to examine the expression level of TGF-beta isoforms using glyceraldehyde 3-phosphate dehydrogenase (GAPDH) gene as an internal control. The results indicated that that levels of TGF-beta1 and TGF-beta3 mRNAs were significantly higher in chemical gas-injured patients than noninjured group (P < .05). Therefore, the authors speculate that TGF-beta1 and TGFbeta3, but not TGF-beta2, secretion is a result of efficient efferocytosis in chemically injured patients, playing a protective role by improving airway remodeling and lung homeostasis in this group. These properties of TGF-beta are consistent with long-time survival of chemical-injured people suffering from BO.

Multidetector high-resolution computed tomography of the lungs: protocols and applications

Advances in computed tomography (CT) scanner technology have made isotropic volumetric, multiplanar high-resolution lung imaging possible in a single breath-hold, a significant advance over the incremental high-resolution CT (HRCT) technique in which noncontiguous images sampled the lung, but lacked anatomic continuity. HRCT of the lungs is an established imaging technique for the diagnosis and management of interstitial lung disease, emphysema, and small airway disease, providing a noninvasive detailed evaluation of the lung parenchyma, and providing information about the lungs as a whole and focally. In addition to having a high degree of specificity for diagnosing conditions such as emphysema, sarcoidosis, usual interstitial pneumonitis, Langerhans cell histiocytosis, and small airway disease, there is a growing body of medical evidence to support the use of HRCT findings or diagnosis to predict patient prognosis. In this article, we review the technique, advantages, and clinical applications of the current HRCT technique.

Pathology of small airways disease

CONTEXT

The term small airways disease encompasses a generally poorly understood group of lung diseases that may arise primarily within the small airways or secondarily from diseases primarily affecting the bronchi or lung parenchyma. Their histology may be confusing; however, because treatments and prognoses vary, correct pathologic diagnosis is important.

OBJECTIVE

To present a nonexhaustive review of the pathology of primary and secondary small airways diseases, including small airways disease related to tobacco; to various other exposures, including mineral dusts; to diseases involving other areas of the lung with secondary bronchiolar involvement; and to recently described bronchiolitic disorders.

DATA SOURCES

Current literature is reviewed.

CONCLUSIONS

Small airways diseases include a wide variety of diseases of which the pathologist must consider. Uncommon conditions such as diffuse idiopathic neuroendocrine cell hyperplasia and diffuse panbronchiolitis may show relatively specific diagnostic features histologically; however, most small airways diseases exhibit nonspecific histologic features. Conditions not considered primary pulmonary diseases, such as collagen vascular diseases, bone marrow transplantation, and inflammatory bowel disease, must also be considered in patients with small airways changes histologically. Clinical and radiologic correlation is important for obtaining the best possible diagnosis.

The spectrum of nonasthmatic inflammatory airway diseases in adults

When the airways are overwhelmed by noxious particles, gases, or microorganisms, inflammatory and immune responses occur that may cause permanent structural changes. One consequence may be an overproduction of mucus and this may overwhelm mucociliary clearance mechanisms and cause a chronic cough phlegm syndrome. The expectorated mucus is usually clear or white (mucoid) but when it becomes infected, the mucus may become purulent and have a yellow or green color. Diseases associated with chronic productive cough discussed in this article include chronic bronchitis, bronchiectasis, and infectious and noninfectious bronchiolitis and their diagnosis and treatment.

Bronchiolar disorders: a clinical-radiological diagnostic algorithm

Bronchiolar disorders are generally difficult to diagnose because most patients present with nonspecific respiratory symptoms of variable duration and severity. A detailed clinical history may point toward a specific diagnosis. Pertinent clinical questions include history of smoking, collagen vascular disease, inhalational injury, medication usage, and organ transplant. It is important also to evaluate possible systemic and pulmonary signs of infection, evidence of air trapping, and high-pitched expiratory wheezing, which may suggest small airways involvement. In this context, pulmonary function tests and plain chest radiographs may demonstrate abnormalities; however, they rarely prove sufficiently specific to obviate bronchoscopic or surgical biopsy. Given these limitations, in our experience, high-resolution CT (HRCT) scanning of the chest often proves to be the most important diagnostic tool to guide diagnosis in these difficult cases, because different subtypes of bronchiolar disorders may present with characteristic image findings. Three distinct HRCT patterns in particular are of value in assisting differential diagnosis. A tree-in-bud pattern of well-defined nodules is seen primarily as a result of infectious processes. Ill-defined centrilobular ground-glass nodules point toward respiratory bronchiolitis when localized in upper lobes in smokers or subacute hypersensitivity pneumonitis when more diffuse. Finally, a pattern of mosaic attenuation, especially when seen on expiratory images, is consistent with air-trapping characteristic of bronchiolitis obliterans or constrictive bronchiolitis. Based on an appreciation of the critical role played by HRCT scanning, this article provides clinicians with a practical algorithmic approach to the diagnosis of bronchiolar disorders.

Mycoplasma pneumoniae bronchiolitis in adults: clinicoradiologic features and clinical course

The clinicoradiologic features of Mycoplasma pneumoniae bronchiolitis in adults remain unclear. 29 patients with M. pneumoniae infection were collected and classified by computed tomographic findings (bronchiolitis (n=8) and pneumonia (n=21)). M. pneumoniae bronchiolitis is not rare in adults and is clinically similar to M. pneumoniae pneumonia, despite radiographic differences.

Small Airways Disease

Small airways diseases are best defined pathologically as a diverse group of conditions that primarily involve bronchioles and acartilagenous airways 2 mm or less in diameter, which include membranous bronchioles, respiratory bronchioles, and alveolar ducts. Small airways can be involved with disease primarily or secondarily. The concept of small airways disease varies among specialties, with clinicians generally considering them in terms of terminal airway changes causing airflow obstruction, radiologists considering them in the context of direct signs and indirect signs identified on high-resolution computed tomography scans, and pathologists evaluating them based entirely or almost entirely on the histologic changes present in the bronchioles, with or without associated changes involving bronchi and alveoli. The histologic features of small airways diseases may be confusing because they overlap. There may be incomplete assessment of the histologic process with limited biopsy. Other disease processes may occur along with a small airways disease, and may obscure or confound its histologic features. This article focuses on the histologic changes diagnostic of a variety of primary and secondary small airways diseases. Because the histologic features involve bronchioles, gross findings are often minimal and/or nonspecific. The article provides a nonexhaustive examination of conditions and diseases involving the small airways, focusing on the microscopic features, with emphasis on the limitations of histologic diagnosis and differential diagnosis.

Quantitative assessment of lung using hyperpolarized magnetic resonance imaging

Improvements in the quantitative assessment of structure, function, and metabolic activity in the lung, combined with improvements in the spatial resolution of those assessments, enhance the diagnosis and evaluation of pulmonary disorders. Radiologic methods are among the most attractive techniques for the comprehensive assessment of the lung, as they allow quantitative assessment of this organ through measurements of a number of structural, functional, and metabolic parameters. Hyperpolarized nuclei magnetic resonance imaging (MRI) has opened up new territories for the quantitative assessment of lung function and structure with an unprecedented spatial resolution and sensitivity. This review article presents a survey of recent developments in the field of pulmonary imaging using hyperpolarized nuclei MRI for quantitative imaging of different aspects of the lung, as well as preclinical applications of these techniques to diagnose and evaluate specific pulmonary diseases. After presenting a brief overview of various hyperpolarization techniques, this survey divides the research activities of the field into four broad areas: lung microstructure, ventilation, oxygenation, and perfusion. Finally, it discusses the challenges currently faced by researchers in this field to translate this rich body of methodology into wider-scale clinical applications.

[Lung diseases and gastro-oesophageal reflux disease]

Gastro -oesophageal Reflux Disease is a consequence of pathological reflux from stomach to oesophagus. Whenever the refluxed contents extended beyond the oesophagus itself, is called Extraoesophageal Reflux Disease. The author proposes a review about pulmonary disorders and gastroesophageal reflux. Previously, it is evaluated in an abridged way, the concepts of each diseases and after that, in a systematic form, it is discussed the prevalence of gastro -oesophageal reflux in lung diseases, all the mechanisms studies and the impact of gastro -oesophageal treatment on lung disorders. The author concludes that is undeniable the link between Gastro -oesophageal reflux and lung diseases and further reaserch is mandatory in order to corroborate this association.

Bronchiolitis obliterans organizing pneumonia

Bronchiolitis obliterans organizing pneumonia (BOOP) is a diffuse infiltrative pulmonary disorder that has an insidious onset. The patient often presents with flu-like symptoms and radiological findings showing bilateral patchy infiltrates. Histological features show fibromyxoid connective tissue plugs that are evenly spaced in small distal airways and alveolar spaces. Treatment for BOOP is corticosteroid therapy. Critical care nurses must be cognizant of BOOP as a differential diagnosis for patients for whom antibiotic therapy has not resolved symptoms.

Diffuse panbronchiolitis: not just an Asian disease: Australian case series and review of the literature

Diffuse panbronchiolitis is a disease of obscure aetiology that is traditionally associated with Asian ethnicity. We propose that this disease also occurs in Caucasians and the incidence in this population is greater than currently recognised. We further propose that high resolution computed tomography (HRCT) and response to macrolide therapy should be relied upon to make this diagnosis without verification by lung biopsy. In most circumstances, obtaining a biopsy for histopathology is not practical, and the disease may then be mistaken for other more common airway diseases. Accuracy of diagnosis is important as untreated disease is associated with a poor prognosis, and effective treatment is available. We report four out of a series of cases as evidence that DPB is in fact more common in the Western population than is currently understood.

Saber-sheath trachea in a patient with bronchiolitis obliterans syndrome after lung transplantation

Chronic rejection remains a major source of morbidity and mortality following lung transplantation. The clinical characteristics of chronic rejection involves bronchiolitis obliterans syndrome (BOS), which leads to progressive airway obstruction. Changes in intrathoracic tracheal dimensions and shape are commonly present in the setting of airway obstruction, leading to the narrowing of the intrathoracic trachea in the coronal plane with anteroposterior lengthening characteristic of the saber-sheath trachea deformity. We present a 64-year-old man who underwent left lung transplantation for idiopathic pulmonary fibrosis who later developed saber-sheath trachea as a result of chronic airway obstruction due to BOS.

Structural and functional abnormalities in lungs in patients with achalasia

Dilatation and oesophageal body aperistalsis in achalasia can lead to stasis which in turn can induce repeated microaspiration. It is therefore conceivable that patients with achalasia may also have abnormalities in lungs secondary to repeated episodes of microaspiration. There is a lack of systematic study on involvement of lungs in patients with achalasia. Thirty patients with achalasia underwent pulmonary function tests (spirometry, and carbon mono-oxide diffusion capacity) and high resolution computerized tomography (HRCT) of the chest. The mean age of patients and mean duration of disease were 33.5 +/- 10.9 years and 28.1 +/- 27.3 months respectively. Regurgitation was present in 22 (73.3%) of them. Respiratory symptoms in them were dry cough in 17 (56.6%), and chest pain in 18 (60%). The oesophagus was dilated in 26 (86.6%) and 13 (43.3%) had residue in oesophagus. Sixteen (53.3%) patients had either anatomical changes as seen on HRCT or functional changes as observed on pulmonary function tests. Of those with functional abnormalities, five (16.6%) and one (3.3%) had restrictive and obstructive airways disease respectively. While evidence of tracheo-bronchial compression by dilated oesophagus was present in eight (26.6%), 10 (33.3%) patients had parenchymal lung disease [nodular opacities in five (16.6%), ground glass appearance six (20%), patchy pulmonary fibrosis five (16.6%), air trapping two (6.6%), consolidation and bronchiectasis one (3.3%) each]. There was a significant association between presence of regurgitation and dilatation of oesophagus (P = 0.032). More than half (53.3%) of patients with achalasia have structural and/or functional abnormalities in lungs.