Chlamydia pneumoniae Growth Inhibition in Cells by the Steroid Receptor Antagonist RU486 (Mifepristone)
Effect of RU486 on C. pneumoniae growth in cells.
In order to determine the effect of RU486 on C. pneumoniae growth in cells, the bacterial growth in HEp-2 cells in the presence or the absence of RU486 was assessed by the IFU assay. As shown in Fig. Fig.1,1, treatment of C. pneumoniae-infected cells with RU486 resulted in a significant decrease in C. pneumoniae growth at 72 h after infection. The inhibition of the bacterial growth by RU486 was dose dependent, and the lowest concentration required for significant inhibition was 0.2 μM. When a higher concentration, such as 20 μM, was used for treatment of the cells, no infective chlamydial organisms were observed but obvious cytotoxicity to the HEp-2 cells was observed (data not shown). Therefore, concentrations up to 2 μM of RU486 were selected for use in the following experiments. A time course analysis with 2 μM of RU486 also showed that the drug immediately acted on bacterial replication at 24 h after infection and continuously inhibited bacterial growth for up to 72 h after infection (Fig. (Fig.22).
In conclusion, the steroid receptor antagonist RU486 inhibits C. pneumoniae growth in epithelial HEp-2 cells by directly binding to the bacteria. Even though the mechanism of inhibition is not clear, this novel mechanism of regulation of C. pneumoniae growth in cells by RU486 might be useful for obtaining an understanding of the complicated aspects of C. pneumoniae infection. Moreover, it might also be helpful in the development of a novel type of antimicrobial agent that inhibits C. pneumoniae growth in host cells.
Did anibody try mifepriston? It is for sale in drug stores
20 μM is 20 mg? who knows?