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Apoptosis and Fas/Fas ligand mRNA expression in acute immune complex alveolitis in mice
Y Nomoto1, K Kuwano, N Hagimoto
1Research Institute for Diseases of the Chest, Faculty of Medicine, Kyushu University, Fukuoka, Japan.
Abstract:
Deoxyribonucleic acid (DNA) strand breaks as a characteristic of apoptosis, and Fas antigen (Fas)/Fas ligand (FasL) expression may participate in acute immune complex alveolitis in mice. Male Institute for Cancer Research (ICR) mice were injected intravenously with immunoglobulin G (IgG) antibodies against ovalbumin and inhaled an aerosolized oval albumin (OA) solution. They were killed at 4, 6, 12, 24, 48 h and 7 days after aerosolization. We assessed DNA fragmentation by agarose gel electrophoresis and terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate biotin nick end-labelling (TUNEL). The expression of Fas and FasL messenger ribonucleic acid (mRNA) in lung tissues was assessed by reverse transcriptase (RT) polymerase chain reaction, and by in situ hybridization (ISH) to localize Fas mRNA, and RT in situ polymerase chain reaction to localize FasL mRNA. The fragmentation of DNA extracted from lung tissue was found 6-24 h after OA inhalation. TUNEL detected positive signals in bronchial and alveolar epithelial, endothelial and inflammatory cells in the lung tissue. These positive signals had disappeared 7 days after OA inhalation. TUNEL also detected positive signals in apoptotic neutrophils in bronchoalveolar lavage fluid at 6-12 h. Fas mRNA was expressed in the alveolar epithelial and inflammatory cells, while the expression of FasL mRNA appeared to be upregulated in infiltrating inflammatory cells at 6-24 h. These results suggest that apoptosis may be associated with the resolution of inflammation and with tissue repair and also suggest the involvement of the Fas antigen/Fas ligand pathway in acute immune complex alveolitis in mice.
Insights
Apoptosis, marked by DNA breaks, and Fas/FasL expression are involved in acute immune complex alveolitis in mice. This suggests apoptosis aids inflammation resolution and tissue repair via the Fas pathway.
Area of Science:
- Immunology
- Cell Biology
- Pathology
Background:
- Acute immune complex alveolitis is an inflammatory lung condition.
- Apoptosis (programmed cell death) and the Fas/FasL pathway are implicated in immune responses.
Purpose of the Study:
- To investigate the role of apoptosis and Fas/FasL expression in a mouse model of acute immune complex alveolitis.
Main Methods:
- Mice were induced with immune complex alveolitis using ovalbumin (OA) and IgG antibodies.
- DNA fragmentation was assessed using gel electrophoresis and TUNEL assay.
- Fas and FasL mRNA expression was analyzed via RT-PCR, ISH, and RT-ISh.
Main Results:
- DNA fragmentation was observed between 6-24 hours post-OA inhalation.
- TUNEL assay detected apoptotic cells in lung tissue and bronchoalveolar lavage fluid.
- Fas mRNA was expressed in lung cells, and FasL mRNA was upregulated in inflammatory cells.
Conclusions:
- Apoptosis is associated with the resolution of inflammation and tissue repair in acute immune complex alveolitis.
- The Fas antigen/Fas ligand pathway plays a role in this inflammatory process.