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.
OBJECTIVE
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, 1.0< or =IgA> or =1.1 or 1.0< or =IgG> or =1.1), 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.


CONCLUSIONS
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.
Kohara
Katsuhiko
K
Department of Geriatric Medicine, Ehime University School of Medicine, Ehime University, Japan. koharak@m.ehime-u.ac.jp
Tabara
Yasuharu
Y
Yamamoto
Yoshikuni
Y
Igase
Michiya
M
Miki
Tetsuro
T
D000368:Aged; D000907:Antibodies, Bacterial / Q000097:blood; D002339:Carotid Arteries / Q000000981:diagnostic imaging; D018932:Chemokine CCL2 / Q000097:blood; D023521:Chlamydophila Infections / Q000097:blood* / Q000453:epidemiology* / Q000276:immunology; D016993:Chlamydophila pneumoniae / Q000276:immunology*; D003710:Demography; D005260:Female; D006801:Humans; D007070:Immunoglobulin A / Q000097:blood; D007074:Immunoglobulin G / Q000097:blood; D018799:Intercellular Adhesion Molecule-1 / Q000097:blood*; D007564:Japan / Q000453:epidemiology; D008137:Longitudinal Studies; D008297:Male; D012044:Regression Analysis; D012111:Residence Characteristics; D012307:Risk Factors; D016036:Seroepidemiologic Studies; D014463:Ultrasonography; D019010:Vascular Cell Adhesion Molecule-1 / Q000097:blood*
D000907:Antibodies, Bacterial; D018932:Chemokine CCL2; D007070:Immunoglobulin A; D007074:Immunoglobulin G; D019010:Vascular Cell Adhesion Molecule-1; D018799:Intercellular Adhesion Molecule-1