Chlamydial LPS and high-sensitivity CRP levels in serum are associated with an elevated body mass index in patients with cardiovascular disease.

Objective: Seropositivity for Chlamydia pneumoniae has been associated with an elevated body mass index (BMI). Our aim was to study if serum chlamydial lipopolysaccharide (cLPS), C. pneumoniae antibodies and high-sensitivity C-reactive protein (hsCRP) levels are associated with BMI.

Patients And Methods: The study population consisted of 174 patients with symptomatic carotid stenosis, abdominal aortic aneurysm or occlusive aortic disease. Information on BMI, diabetes, smoking, hypercholesterolemia, and statin medication was available. Serum C. pneumoniae IgG and IgA antibodies, cLPS, hsCRP and total endotoxin activity (totLPS) were measured.

Results: BMI correlated with cLPS (r = 0.197; P < 0.01) and with hsCRP (rho = 0.195; P < 0.01); in addition, there was a positive correlation between cLPS and hsCRP (rho = 0.499; P < 0.01). A trend of an increasing proportion of C. pneumoniae IgG positivity (titre > or = 64; P = 0.018) and higher serum cLPS (P = 0.01) and hsCRP (P = 0.01) concentrations was observed across the BMI groups (BMI < or = 24.9 kg/m(2), BMI = 25.0-29.9 kg/m(2), and BMI > or = 30.0 kg/m(2)). Among the three BMI groups, 24.6%, 38.8%, and 48.3% were C. pneumoniae IgG-positive and the median (IQR) cLPS concentrations (ng/ml) of the groups were: 92.6 (50.8-167.0), 128.9 (76.4-163.9), and 146.4 (105.8-175.8), respectively. The median (IQR) hsCRP (mg/l) concentrations of the groups were: 1.70 (0.70-3.05) 1.70 (0.80-5.20), and 3.40 (1.45-8.55), respectively. These associations remained statistically significant in a multivariate analysis.

Conclusions: Elevated serum cLPS levels were associated with an elevated BMI. This is a novel finding and it strengthens the link between chlamydial infection and obesity. A lack of association between totLPS and BMI suggests that the association between infection and an elevated BMI may be specific to certain pathogens.