Aims: Evidence is accumulating to support the hypothesis that the release of heat shock protein (Hsp)60 into the circulation is associated with the development of coronary heart disease (CHD). As diabetes is a risk factor for CHD, it was of interest to determine Hsp60 blood levels in a cross-sectional cohort of diabetic patients, some of whom had cardiovascular disease, and relate levels to relevant biochemical markers.
Methods and results: A total of 855 patients with T1DM or T2DM, recruited as part of the UCL Diabetes and Cardiovascular disease Study (UDACS), were assayed for plasma levels of Hsp60. Immunoreactive Hsp60 was detected in 54% of the samples, with 26% having plasma levels > 1 microg/mL. Levels of Hsp60 were higher in Caucasians than in other ethnic groupings, with 56.5% of Caucasian subjects, 37.5% of African-Caribbean subjects, and 47.1% of Indian subjects having detectable levels (P = 0.007), and with a higher proportion of non-smokers having detectable Hsp60 levels than smokers (54.9 vs. 43.5%, P = 0.01). Of note was the finding of an association between higher mean plasma levels of Hsp60 in subjects with clinically manifest cardiovascular disease and those with a history of myocardial infarction having an adjusted odds ratio of having detectable Hsp60 of 2.17 (CI 1.26-3.73).
Conclusion: This is the first report of circulating Hsp60 levels in diabetic patients, which suggests that this secreted mitochondrial cell stress protein may be playing an unexpected role in the cardiovascular pathology associated with diabetes.