Chlamydia pneumoniae Decreases Smooth Muscle Cell Proliferation through Induction of Prostaglandin E ₂ Synthesis

Chlamydia pneumoniae may modulate the proliferation of smooth muscle cells (SMC) in atherosclerotic plaques. Conditioned medium from C. pneumoniae- infected SMC decreased the proliferation of uninfected SMC. Treatment of infected cells with the cyclooxygenase-2 inhibitor NS-398 { N -[2-(cyclohexyloxy)-4-nitrophenyl]-methanesulfonamide} suppressed the up-regulation of prostaglandin E 2 (PGE 2 ) and abolished the antimitogenic effect of conditioned medium, suggesting that C. pneumoniae can decrease SMC proliferation via stimulation of PGE 2 synthesis.