Abstract | BACKGROUND: The mechanisms during the initial phase of oxygen toxicity leading to pulmonary tissue damage are incompletely known. Increase of tumour necrosis factor alpha ( TNFalpha) represents one of the first pulmonary responses to hyperoxia. We hypothesised that, in the initial phase of hyperoxia, TNFalpha activates the caspase cascade in type II pneumocytes (TIIcells). METHODS: Lung sections or freshly isolated TIIcells of control and hyperoxic treated rats (48 hrs) were used for the determination of TNFalpha (ELISA), TNF-receptor 1 (Western blot) and activity of caspases 8, 3, and 9 (colorimetrically). NF-kappaB activation was determined by EMSA, by increase of the p65 subunit in the nuclear fraction, and by immunocytochemistry using a monoclonal anti- NF-kappaB-antibody which selectively stained the activated, nuclear form of NF-kappa B. Apoptotic markers in lung tissue sections (TUNEL) and in TIIcells (cell death detection ELISA, Bax, Bcl-2, mitochondrial membrane potential, and late and early apoptotic cells) were measured using commercially available kits. RESULTS: CONCLUSION: In the initiation phase of pulmonary oxygen toxicity, an increase of TNFalpha and its receptor TNFR1 leads to the activation of caspase 8 and 3 in TIIcells. Together with the hyperoxic induced increase of Bax and the decrease of the mitochondrial membrane potential, activation of caspase 3 can be seen as sensitisation for apoptosis. Eliminating the TNFalpha effect in vivo by anti- TNFalpha antibodies prevents the pro-apoptotic sensitisation of TIIcells.
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Authors | Florian Guthmann, Heide Wissel, Christian Schachtrup, Angelika Tölle, Mario Rüdiger, Friedrich Spener, Bernd Rüstow |
Journal | Respiratory research
(Respir Res)
Vol. 6
Pg. 10
(Jan 21 2005)
ISSN: 1465-993X [Electronic] England |
PMID | 15663790
(Publication Type: Journal Article)
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Chemical References |
- Cytokines
- Tumor Necrosis Factor-alpha
- Casp3 protein, rat
- Casp8 protein, rat
- Caspase 3
- Caspase 8
- Caspases
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Topics |
- Animals
- Caspase 3
- Caspase 8
- Caspases
(metabolism)
- Cells, Cultured
- Cytokines
(metabolism)
- Enzyme Activation
- Hyperoxia
(metabolism)
- Lung
(metabolism)
- Oxidative Stress
- Rats
- Rats, Wistar
- Tumor Necrosis Factor-alpha
(metabolism)
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