Effects of antiasthma drugs on the growth of Chlamydophila pneumoniae in HEp-2 cells.

A possible link between Chlamydophila pneumoniae infection and adult-onset asthma has been raised recently. To obtain further insight into the association of C. pneumoniae with asthma, we assessed the effects of antiasthma drugs commonly used in Japan on the growth of C. pneumoniae in HEp-2 cells. The growth was enhanced two times by inhalant glucocorticoids, such as fluticasone propionate and beclomethasone, as well as hydrocortisone succinate. Unexpectedly, two nonsteroidal antiasthma drugs, tranilast and seratrodast, an adenine nucleotide-lowering agent and a thromboxane A(2) receptor antagonist, respectively, were shown to inhibit chlamydial growth in vitro. The minimum inhibitory concentration and minimum chlamydicidal concentration were both 64 micrograms/ml, which are comparable to the peak serum levels achievable by a therapeutic dosage. These results suggest that some antiasthma drugs may affect the therapeutic outcome of C. pneumoniae-associated bronchial asthma by their effects on C. pneumoniae.