The atherogenic effects of chlamydia are dependent on serum cholesterol and specific to Chlamydia pneumoniae
He Hu, Grant N. Pierce, Guangming Zhong
He Hu, Grant N. Pierce, Guangming Zhong
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The atherogenic effects of chlamydia are dependent on serum cholesterol and specific to Chlamydia pneumoniae

Abstract

Epidemiological investigations have linked Chlamydia pneumoniae infection to atherosclerosis. It is not clear, however, whether C. pneumoniae infection plays a causal role in the development of atherosclerosis. Mice with low-density lipoprotein receptor deficiency were induced to develop atherosclerotic lesions in aorta with a cholesterol-enriched diet that increased serum cholesterol by two- to threefold. Using this mouse model, we found that the chlamydial infection alone with either the C. pneumoniae AR39 or the C. trachomatis MoPn strain failed to induce any significant atherosclerotic lesions in aorta over a period of nine months. However, in the presence of a high-cholesterol diet, infection with the C. pneumoniae AR39 strain significantly exacerbated the hypercholesterolemia-induced atherosclerosis, demonstrating that a hypercholesterolemic condition is required for the C. pneumoniae to aggravate the development of atherosclerosis. Although both AR39 and MoPn antigens were detected in aorta of mice infected with the corresponding strains, only mice infected with the C. pneumoniae strain AR39 displayed enhanced atherosclerotic lesions, suggesting that the C. pneumoniae species may possess a unique atherogenic property. This study may provide a model for further understanding the mechanisms of C. pneumoniae atherogenesis and evaluating chlamydial intervention strategies for preventing the advancement of atherosclerotic lesions enhanced by C. pneumoniae infection.

Authors

He Hu, Grant N. Pierce, Guangming Zhong

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Representative images of mouse aortic luminal surface (top) and aorta ar...
Representative images of mouse aortic luminal surface (top) and aorta arch cross-sections (bottom) after hematoxylin and eosin staining. Aorta from six groups of mice were isolated for luminal surface lesion observation without any prior staining (panels a–f). The luminal surface of each entire aorta from aorta arch (left) to the bifurcation (right) was shown. The light-colored atherosclerotic lesions were readily noticeable in aorta from mice fed with a high-cholesterol diet (panels b, d, and f) but not in those of mice fed with a normal food diet (panels a, c, and e). Some of the lesions were further stained with Sudan red for verifying the lipid content (data not shown) after acquiring the images. The aortic arch portions of the samples just described were used to make sections for hematoxylin and eosin staining (panels g –l) for evaluating lesion severity. The pictures were taken with a Zeiss microscope using a 20× objective lens.