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(Stroke. 2002;33:1474.)
© 2002 American Heart Association, Inc.

Original Contributions

Chlamydia pneumoniae Seropositivity Is Associated With Increased Plasma Levels of Soluble Cellular Adhesion Molecules in Community-Dwelling Subjects

The Shimanami Health Promoting Program (J-SHIPP) Study

Katsuhiko Kohara, MD; Yasuharu Tabara, PhD; Yoshikuni Yamamoto, MD; Michiya Igase, MD Tetsuro Miki, MD

From the Department of Geriatric Medicine, Ehime University School of Medicine, Ehime University, Japan.

Correspondence to Katsuhiko Kohara, MD, Department of Geriatric Medicine, Ehime University School of Medicine, Ehime University, Shigenobu-cho, Onsen-gun, Ehime 791-0295, Japan. E-mail koharak{at}m.ehime-u.ac.jp

Background and Purpose— In vitro studies have demonstrated that Chlamydia pneumoniae infection of the endothelium increases the expression of adhesion molecules and chemokines, indicating that C pneumoniae infection affects the adhesion and recruitment of leukocytes to the endothelium, which is believed to be involved in the initial steps of atherosclerosis. However, whether chronic C pneumoniae infection increases these molecules in vivo has not been elucidated.

Methods— The association between C pneumoniae seropositivity and plasma concentrations of soluble adhesion molecules and a chemokine was investigated in 200 community-dwelling residents free from cardiovascular diseases and medication. Plasma levels of IgA and IgG antibodies to C pneumoniae were measured by enzyme-linked immunosorbent assay. Indices of IgG and IgA antibodies were determined as the ratio to the standardized positive control. The subjects were divided into 3 groups according to the indices of antibodies: C pneumoniae seronegative (n=57, IgA<1.0 and IgG<1.0), C pneumoniae intermediate (n=81, 1.0IgA1.1 or 1.0IgG1.1), and C pneumoniae seropositive (n=62, IgA>1.1 and IgG>1.1). Plasma concentrations of soluble forms of intercellular adhesion molecule-1 (ICAM-1), vascular cellular adhesion molecule-1, and monocyte chemoattractant protein-1 were determined by enzyme-linked immunosorbent assay.

Results— Plasma concentrations of ICAM-1 (392±118, 398±94, 470±154 ng/mL, P=0.0004) and vascular cellular adhesion molecule-1 (402±146, 419±130, 472±181 ng/mL, P=0.03) were significantly different among the C pneumoniae seronegative, intermediate, and seropositive groups respectively. However, plasma monocyte chemoattractant protein-1 was not significantly different among the 3 groups. Stepwise regression analysis showed that plasma concentration of ICAM-1 was significantly associated with C pneumoniae seropositivity, independent of other known risk factors for atherosclerosis and carotid intima-media thickness.

Conclusion— These findings indicate that C pneumoniae seropositivity is associated with higher plasma concentrations of soluble forms of adhesion molecules in the general population. The increase in circulating adhesion molecules may underlie the mechanisms linking C pneumoniae infection and atherosclerosis in vivo.

Key Words: atherosclerosis • Chlamydia pneumoniae • intercellular adhesion molecule-1 • monocyte chemoattractant protein-1 • vascular cellular adhesion molecule-1