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Superoxide dismutase 3 as an inflammatory suppressor in A549 cells infected with Mycoplasma pneumoniae
Jia-Yuan Jin1, Y E Chen, Xing-You Wang
1Department of Pharmacy, Puxing Community Health Service Center, 250 Gui Chang Road, Pudong New District, Shanghai 200129, People's Republic of China.
Abstract:
Herein, we found that serum concentration of superoxide dismutase 3 (SOD3) was significantly reduced in children with mycoplasma pneumonia (MP) infection. To study the roles of SOD3 in inflammatory regulation of MP infection, human A549 type II alveolar epithelial cells were stimulated with 107 CCU/ml of MP to build MP infection in vitro. Secretion of pro-inflammatory cytokine interleukin (IL)-8 and tumor necrosis factor (TNF)-α were measured via enzyme-linked immunosorbent assay (ELISA) to assess the inflammatory response of A549 cells. Levofloxacin (LVFX) was used as an anti-inflammatory drug while recombinant TNF-α was used as an inflammatory promotor in MP-infected cells. Transcriptional activity of nuclear factor (NF)-κB was assessed by detecting protein levels of nuclear NF-κB and cytoplasm NF-κB using Western blot analysis. Our data suggested that the expression of SOD3 mRNA and protein, as well as content of SOD3 in cultured supernatant, were time-dependently inhibited in MP-infected A549 cells. However, lentiviruses-mediated SOD3 overexpression alleviated inflammatory response of MP-infected A549 cells, and prevented the unclear translocation of NF-κB, as evidenced by obviously reducing the production of IL-8 and TNF-α in cell cultured supernatant, as well as decreasing nuclear NF-κB while increasing cytoplasm NF-κB. Inspiringly, SOD3 overexpression induced anti-inflammatory effect and the inactivation of NF-κB was similar to that of 2 lg/ml of LVFX, but reversed by additional TNF-α treatment. Therefore, we can conclude that transcriptional activity of NF-jB was the underlying mechanism, by which SOD3 regulated inflammatory response in MP infection in vitro.
Insights
Superoxide dismutase 3 (SOD3) levels decrease during mycoplasma pneumonia (MP) infection. Restoring SOD3 in lung cells reduces inflammation by inhibiting nuclear factor-kappa B (NF-κB) activation.
Area of Science:
- Pulmonary Medicine
- Cell Biology
- Immunology
Background:
- Mycoplasma pneumonia (MP) infection is a common cause of respiratory illness in children.
- Serum concentrations of superoxide dismutase 3 (SOD3) are reduced in children with MP infection.
- The role of SOD3 in regulating inflammation during MP infection requires further elucidation.
Purpose of the Study:
- To investigate the role of SOD3 in the inflammatory response to MP infection in human A549 alveolar epithelial cells.
- To determine the effect of SOD3 modulation on pro-inflammatory cytokine production and NF-κB activation.
- To explore the underlying mechanisms of SOD3-mediated anti-inflammatory effects in MP infection.
Main Methods:
- Human A549 cells were infected with MP (10^7 CCU/ml) in vitro.
- Pro-inflammatory cytokines (IL-8, TNF-α) were measured using ELISA.
- NF-κB transcriptional activity was assessed via Western blot analysis of nuclear and cytoplasmic NF-κB.
- SOD3 expression was modulated using lentiviral vectors.
Main Results:
- MP infection time-dependently inhibited SOD3 expression (mRNA, protein, and secretion) in A549 cells.
- SOD3 overexpression alleviated MP-induced inflammation, reducing IL-8 and TNF-α levels.
- SOD3 overexpression prevented NF-κB translocation to the nucleus, decreasing nuclear NF-κB and increasing cytoplasmic NF-κB.
- The anti-inflammatory effect of SOD3 overexpression mimicked levofloxacin and was reversed by TNF-α.
Conclusions:
- SOD3 plays a protective role against MP-induced inflammation in alveolar epithelial cells.
- SOD3 exerts its anti-inflammatory effects by inhibiting NF-κB transcriptional activity.
- Modulating SOD3 levels represents a potential therapeutic strategy for MP-related lung inflammation.
