Chlamydia pneumoniae antibodies associated with altered serum lipid profile.

Chronic Chlamydia pneumoniae infection has been associated with atherosclerosis by seroepidemiological studies. Further, acute bacterial infections are known to influence lipid metabolism. To clarify the possible pathogenetic mechanisms of this association, we studied serum lipids and the C. pneumoniae IgG antibody titers of 1,053 males who participated in the reindeer herders health survey in Northern Finland in 1986-1989. The mean age of the study group was 47 years (range 20-87). When comparing nonsmoking C. pneumoniae antibody-positive (IgG > or = 32) subjects to those with no antibodies, the age-adjusted mean concentration of triglycerides was increased (1.34 vs. 1.04 mmol/l; p = 0.03) and high-density lipoprotein (HDL) was decreased (1.24 vs. 1.35 mmol/l; p < 0.001). HDL:total cholesterol ratio was also decreased (0.20 vs. 0.23; p = 0.01). In smokers changes were very similar, but not statistically significant. Thus, C. pneumoniae antibodies seem to correlate with an altered serum lipid profile considered to increase the risk of atherosclerosis. This finding supports the proposal that infections, in this case C. pneumoniae infection, may play a role in the pathogenesis of atherosclerosis.