Chlamydia pneumoniaeInfection Accelerates the Progression of Atherosclerosis in Apolipoprotein E–Deficient Mice

Accumulating evidence supports an association between Chlamydia pneumoniae infection and atherosclerosis. To determine whether there is a causal relationship, the effects of chronic infection with C. pneumoniae on the development of atherosclerosis in apolipoprotein E (apoE)-deficient mice were evaluated. Eight-week-old male apoE-deficient mice were inoculated intranasally with C. pneumoniae three times, at 8, 9, and 10 weeks of age. The combined area of atherosclerotic lesions in the lesser curvature of the aortic arch was measured en face by computer-assisted morphometry. The lesion area was 2.4-fold greater (P=.05) at 16 weeks of age and 1.6-fold greater (P=.05) at 20 weeks of age in infected mice than in control mice. There were no differences in total plasma cholesterol levels between groups. This study demonstrates that C. pneumoniae infection accelerates the progression of atherosclerosis in the aortic arch of apoE-deficient mice.