, a bacterial respiratory tract pathogen, has been associated with atherosclerosis in humans.
infection of the respiratory tracts of rabbits fed a noncholesterol diet induced changes of atherosclerosis of the aorta in 6 (26.1%) of 23 animals after a single inoculum at 3 months. Multiple inocula given three times within 6 weeks resulted in grade III atherosclerosis in 8 (34.8%) of 23 rabbits, with an additional 5 (21.7%) showing increased myxoid changes in the intima-media junction and exhibiting 8 (34.8%) focal periaortitis. Control animals inoculated with carrier broth (
= 24), HEp-2 cells (
= 12), or another respiratory pathogen,
= 32), produced no changes of atherosclerosis after 3 months. The histological changes were dissimilar (fewer foam cells) from those of rabbits fed a 0.5% cholesterol diet but were highly similar to or indistinguishable from changes in rabbits fed a 0.15% cholesterol diet (similar to that of humans). Proinflammatory cytokines and tissue growth factors were more consistently detected in cholesterol-induced aortic lesions than those induced by
. These data are compatible with de novo induction of atherogenesis by
in rabbits and suggest that
may be important in the pathogenesis of atherosclerosis in humans.