Radiation Induced TLR-8 Expression and TGF-β/TNF-α Production in BV2 Microglial Cells

Objective: To observe the radiation-induced TLR-8 mRNA expression and production of proinflammatory cytokines in BV2 microglial cells. Methods: TLR-8 mRNA expression and distribution in BV-2 cells was analyzed by fluorescent quantitative PCR and flow measurement at different time point (1, 3, 6, 12, 24, 48 and 72 h) after a single 16 Gy dose of radiation, or at 24 h after various doses of radiation (2, 5, 10, 16, 20, 30 and 40 Gy).. ELISA was used to determinate the concentration of TNF-alpha and TGF-beta in the supernatant of BV-2 cells. Results: The expression of TLR-8 mRNA in BV2 microglia cells was 0.000639 +/- 0.00016, with 41.98% in the membrane and 32.08% in the cell. After 16 Gy radiation, the TLR-8 mRNA expression increased at 1h after radiation, with peak at 24 h. TLR-8 mRNA increased after 2 Gy radiation, and the value increased to top at 16 Gy. There was a steady increase in the concentration of TGF-beta in the supernatant of BV2 microglial cells 48 h later. A slight effect on TNF-alpha was also found. Conclusion: The data suggests that TLR-8-induced activation of microglia and the release of TGF-beta might be responsible for brain injury induced by radiation