Chlamydia pneumoniae seropositivity and cardiovascular risk factors: The InCHIANTI study

Objectives: To assess the prevalence of Chlamydia pneumoniae (CP) seropositivity and test the hypothesis that CP infection (CPI) is associated with cardiovascular (CV) risk factors and levels of inflammatory biomarkers. Design: Cross-sectional survey. Setting: Representative sample of the residents of Greve in Chianti and Bagno a Ripoli, two small towns located in the Chianti geographic area (Tuscany, Italy). Participants: A total of 1,304 (age-range: 20-103, 79% agedgreater than or equal to65) participants of the InCHIANTI study. Measurements: CP seropositivity was assessed using immunofluorescence. Previous CPI was defined as immunoglobulin (Ig) G greater than or equal to1/16 and <1/256, and recent CPI was defined as IgG greater than or equal to1/512 or IgM greater than or equal to1/16. Inflammatory markers included interleukin (IL)-6, soluble IL-6 receptor (sIL-6r), tumor necrosis factor-alpha (TNF-alpha), IL-1beta, IL-1 receptor antagonist (IL-1ra), iron, ferritin, and C-reactive protein (CRP). CV risk factors included smoking, body mass index (BMI), lipid profile, and hypertension. Results: The prevalence of CP seropositivity was 75%, increased with age, and was higher in men than in women (P<.01). CPI was not associated with IL-1beta, IL-1ra, iron, ferritin, CRP, BMI, lipids, and smoking. After adjusting for age and sex, previous or recent CPI was associated with higher TNF-alpha (P<.01), IL-6 (P<.03), sIL-6R (P<.01), and hypertension (P<.02). In additional age and sex-adjusted models, the associations between CPI and TNF-alpha, IL-6, sIL-6r, and hypertension appeared to be mutually independent. Conclusion: CP seropositivity is highly prevalent in the older population and is a significant, independent correlate of hypertension and circulating levels of TNF-alpha, IL-6, and sIL-6r.