Autoimmunity to human heat shock protein 60, Chlamydia pneumoniae infection, and inflammation in predicting coronary risk.

ABSTRACT

Heat shock protein 60 (Hsp60) and Chlamydia pneumoniae infection have both been associated with cardiovascular diseases. Our aim was to study the role of Hsp60 antibodies as coronary risk predictors and their association with C pneumoniae infection and inflammation. This was a prospective, nested, case-control study. The cases consisted of 239 middle-aged Finnish men who developed myocardial infarction or coronary death during the follow-up. Baseline levels of IgA and IgG antibodies to human-specific and C pneumoniae-specific Hsp60 were measured by enzyme immunoassay. Human Hsp60 IgA, but not IgG or C pneumoniae Hsp60, antibodies were a significant risk factor for coronary events (odds ratio 2.0, 95% CI 1.1 to 3.6, when the fourth and first quartiles are compared). When an elevated human Hsp60 IgA antibody level (above the second quartile) was present simultaneously with a high C pneumoniae IgA antibody level (the third quartile) and an elevated C-reactive protein level (the second quartile), compared with all factors at low levels, the risk was 7.0 (95% CI 2.6 to 19.1) without adjustment and 5.0 (95% CI 1.8 to 14.2) when adjustment was made for age and smoking. In conclusion, an elevated human Hsp60 IgA antibody level was a risk factor for coronary events, especially when it was present together with C pneumoniae infection and inflammation.