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Updated: Jul 13, 2026
A Silicosis Mouse Model Established by Repeated Inhalation of Crystalline Silica Dust
Published on: January 6, 2023
Antigen-presenting cell population dynamics during murine silicosis
Celine A Beamer1, Andrij Holian
1Center for Environmental Health Sciences, Department of Biomedical and Pharmaceutical Sciences, School of Pharmacy and Allied Health Sciences, University of Montana, Missoula, Montana 59812, USA. celine.beamer@umontana.edu
Abstract:
Silicosis is an occupational lung disease resulting from the inhalation of silica particles over prolonged periods of time, which causes chronic inflammation and progressive pulmonary fibrosis. Alveolar macrophages (AM) are critical effector cells, while less is known about the role and function of pulmonary dendritic cells (DC) in silicosis. We hypothesize that a balance exists between the suppressive nature of AM and the stimulatory capacity of DC to regulate lung immunity, and that this equilibrium may be overcome by silica exposure in vivo. Our results demonstrate that in response to silica exposure, both the percent and absolute number of AM significantly decreased over time, with a concomitant significant increase in DC. Both AM and DC exhibited cellular activation in response to silica, indicated by increased expression of cell surface markers. In the absence of silica-induced AM apoptosis (TNFR 1/2-null and Gld mice), no change was observed in the percent or absolute number of either cell type. Furthermore, bone marrow-derived DC, but not bone marrow-derived macrophages, migrated from the alveoli into the lung parenchyma in response to silica, resulting in significantly increased numbers of activated T lymphocytes. Collectively, the results demonstrate that AM and DC are distinct antigen-presenting cells within the respiratory tract that respond to silica exposure in vivo in unique ways, with significant implications for immune reactivity of the lung in response to environmental pathogens.
Insights
Silica exposure decreases alveolar macrophages (AM) and increases dendritic cells (DC) in the lungs. These distinct immune cells activate differently, impacting lung immunity and T cell responses in silicosis.
Area of Science:
- Immunology
- Pulmonology
- Occupational Health
Background:
- Silicosis is a lung disease caused by silica inhalation, leading to inflammation and fibrosis.
- Alveolar macrophages (AM) are key in silicosis, but pulmonary dendritic cell (DC) roles are less understood.
- A balance between AM suppression and DC stimulation may regulate lung immunity, potentially disrupted by silica.
Purpose of the Study:
- To investigate the distinct roles of AM and DC in the immune response to silica exposure.
- To test the hypothesis that silica disrupts the balance between AM and DC functions in the lungs.
Main Methods:
- Quantification and characterization of AM and DC populations in silica-exposed mice.
- Assessment of cellular activation markers on AM and DC.
- Evaluation of T lymphocyte activation and migration patterns in response to silica.
Main Results:
- Silica exposure significantly reduced AM numbers while increasing DC numbers.
- Both AM and DC showed increased activation markers post-silica exposure.
- DC, but not macrophages, migrated into lung parenchyma, increasing activated T lymphocytes.
Conclusions:
- AM and DC are distinct antigen-presenting cells in the respiratory tract with unique responses to silica.
- Silica exposure alters the balance of immune cells in the lung, affecting immune reactivity.
- These findings have implications for understanding lung immune responses to environmental pathogens.
