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Acute and chronic human adenovirus pneumonia: cellular and extracellular matrix components
F C Rosman1, A S Mistchenko, H S Ladenheim
1Departamento de Patologia, Instituto Oswaldo Cruz, FIOCRUZ, Rio de Janeiro, Brazil.
Abstract:
We present a comparative histopathological study of both acute and chronic human adenovirus pneumonia, with reference to the cellular and extracellular matrix components. Seventeen lungs from autopsied patients whose ages ranged from 2 to 60 months were studied. Adenovirus types 1, 2, 3, 5, and 7 were isolated from 15 patients with acute lung disease, and types 2 and 7 were isolated from the other two patients with chronic pulmonary illness. The results indicated the occurrence of two basic patterns of adenovirus interstitial pneumonia (1) classic pattern (acute), characterized by necrosis and degeneration and many type II pneumocytes with intranuclear inclusion bodies, which were positive for adenovirus DNA by in situ hybridization, and (2) proliferative or proliferative-productive pattern (chronic), which presented with diffuse pulmonary fibrosis and the interstitial proliferation of fibroblast-like cells, compatible with myofibroblasts (positive for vimentin and alpha smooth muscle actin), and increase in collagen types I and III, elastic fibers, and proteoglycans. Alveolar collapse appears to be an important pathogenetic mechanism in the development of this pattern.
Insights
Human adenovirus pneumonia presents two distinct histopathological patterns: acute, marked by cell damage and inclusion bodies, and chronic, characterized by pulmonary fibrosis and myofibroblast proliferation. Both patterns involve specific cellular and extracellular matrix changes.
Area of Science:
- Pulmonary Pathology
- Virology
- Histopathology
Background:
- Human adenovirus pneumonia is a significant cause of respiratory illness in infants and young children.
- Understanding the distinct histopathological features of acute and chronic adenovirus pneumonia is crucial for diagnosis and management.
Purpose of the Study:
- To comparatively analyze the histopathological characteristics of acute and chronic human adenovirus pneumonia.
- To investigate the roles of cellular and extracellular matrix components in adenovirus-induced lung injury.
Main Methods:
- Histopathological examination of lung tissue from 17 autopsied patients (2-60 months old).
- Isolation of adenovirus types from patient samples.
- In situ hybridization for adenovirus DNA detection.
- Immunohistochemical staining for vimentin and alpha smooth muscle actin.
- Assessment of collagen types I and III, elastic fibers, and proteoglycans.
Main Results:
- Two distinct patterns identified: classic (acute) with necrosis, degeneration, and type II pneumocytes; and proliferative (chronic) with diffuse pulmonary fibrosis.
- Acute pattern showed intranuclear inclusion bodies positive for adenovirus DNA.
- Chronic pattern exhibited interstitial proliferation of myofibroblasts and increased collagen, elastic fibers, and proteoglycans.
- Alveolar collapse was noted as a key pathogenetic mechanism in the chronic pattern.
Conclusions:
- Human adenovirus pneumonia exhibits distinct acute and chronic histopathological patterns.
- The chronic pattern is characterized by significant pulmonary fibrosis and myofibroblast activity.
- Alveolar collapse plays a critical role in the pathogenesis of chronic adenovirus pneumonia.