Selective cyclooxygenase inhibitors prevent the growth of Chlamydia pneumoniae in HL cells

The effects of the selective cyclooxygenase (COX) inhibitors SC-560 and PTPBS were studied in Chlamydia pneumoniae-infected HL cell cultures. Chlamydia pneumoniae growth and viability were assessed by quantifying inclusions and re-passages. COX-1 and COX-2 mRNA expression in HL cells during chlamydial infection was quantified with real-time polymerase chain reaction. SC-560 (10 μg/mL) and PTPBS (18 μg/mL) completely inhibited the growth of C. pneumoniae and the effect was dose-dependent between 4–9 μg/mL and 2–16 μg/mL, respectively. Inclusion size was reduced from 11.5 ± 1.3 μm to 1.9 ± 0.7 μm in the presence of the drugs. Removing the drugs returned the size to normal and increased the number of inclusions. Selective COX inhibitors appear to have a chlamydiostatic but not chlamydiacidic effect; they inhibit the growth of C. pneumoniae in vitro but do not prevent infection or eradicate C. pneumoniae from host cells.