Clinical and radiologic manifestations of hypersensitivity pneumonitis

An animal model of autoimmune emphysema

Although cigarette smoking is implicated in the pathogenesis of emphysema, the precise mechanisms of chronic progressive alveolar septal destruction are not well understood. We show, in a novel animal model, that immunocompetent, but not athymic, nude rats injected intraperitoneally with xenogeneic endothelial cells (ECs) produce antibodies against ECs and develop emphysema. Immunization with ECs also leads to alveolar septal cell apoptosis and activation of matrix metalloproteases MMP-9 and MMP-2. Anti-EC antibodies cause EC apoptosis in vitro and emphysema in passively immunized mice. Moreover, immunization also causes accumulation of CD4+ T cells in the lung. Adoptive transfer of pathogenic, spleen-derived CD4+ cells into naive immunocompetent animal also results in emphysema. This study shows for the first time that humoral- and CD4+ cell-dependent mechanisms are sufficient to trigger the development of emphysema, suggesting that alveolar septal cell destruction might result from immune mechanisms.

Hypersensitivity pneumonitis: a multifaceted deceiving disorder

Hypersensitivity pneumonitis (HP) represents a group of immunologically mediated lung disorders provoked by recurrent exposure to various environmental agents. HP is multifaceted and may mimic almost any interstitial lung disease, some infectious diseases,and even bronchiolar disorders. In the absence of a diagnostic gold standard,diagnosis of HP requires a combination of clinical, environmental, radiologic, physiologic,and pathologic findings that represent a diagnostic challenge for clinicians and-in the chronic form-even for experienced pathologists. Therapeutic approach includes avoiding further exposure and, depending on the clinical form, the administration of a course of prednisone. New anti-inflammatory, immunoregulatory, and antifibrotic drugs are urgently needed for this and other interstitial lung diseases.

Imaging of interstitial lung disease

This article provides a comprehensive summary of typical imaging features of common interstitial lung diseases with an emphasis on high-resolution computed tomography (HRCT). The classification of interstitial lung disease that is used is in accordance with the consensus statement of the American Thoracic Society. The secondary pulmonary lobule is the basic anatomic unit that is used for standard description of findings on HRCT. Sarcoidosis, Langerhans' cell histiocytosis, lymphangioleiomyomatosis, collagen vascular diseases, and hypersensitivity pneumonitis are some of the common interstitial lung diseases that are addressed.

Airway-centered interstitial fibrosis: a distinct form of aggressive diffuse lung disease

We describe 12 patients with a form of interstitial lung disease characterized pathologically by small airway-centered interstitial fibrosis and metaplastic bronchiolar epithelium extending around and often linking fibrotic and sometimes heavily muscularized bronchioles. Clinically, patients presented with chronic cough and progressive dyspnea. One was a current light smoker and two were ex-smokers. In 8 patients, a history of possible inhalational exposures, including wood smoke, birds, cotton, pasture, chalk dust, agrochemical compounds, and cocaine use, was elicited. Pulmonary function tests showed moderate to severe physiologic abnormalities, in most instances indicating a restrictive lung disease with decreased peripheral flow rates. Chest radiographs revealed predominantly diffuse reticulonodular infiltrates in the central lung fields, with thickening of the bronchial walls and decreased lung volumes. Chest computed tomography demonstrated peribronchovascular fibrosis and interstitial thickening. Bronchoalveolar lavage showed a mild increase in lymphocytes in 4 subjects. Patients were treated with corticosteroids and bronchodilators. Follow-up data were available in 10 patients. In 5 patients, the disease progressed and 4 of them died. Two patients remained stable and 3 improved or healed. We propose that these findings represent a distinct airway-centered disease that mostly behaves as an interstitial lung disease and may exhibit a poor outcome.

Toxicology of nasal irritants

The upper airway, including nasal cavities, naso-, oro-, and hypopharynx, is the portal of entry for air pollutants. Upper airway (as well as eye) irritation figures prominently in symptom reporting in so-called problem buildings and with exposure to environmental tobacco smoke. Large particles and water-soluble gases and vapors are likely to have their initial irritant effects in the mucous membranes of the upper airway and eyes, giving warning to the exposed individual to minimize further exposure. The spectrum of irritant-related upper airway health effects is reviewed in this article.