Circulating Human Heat Shock Protein 60 in the Plasma of British Civil Servants

Abstract

Background — The Whitehall cohort studies (I and II) of British civil servants have identified sociodemographic, psychosocial, and biological risk factors for coronary heart disease (CHD). To identify mechanisms responsible for susceptibility to CHD, specific biological markers of stress are increasingly being measured. One marker linked to susceptibility to CHD is heat shock protein (Hsp) 60. Methods and Results — Blood was taken from 229 civil servants (126 men and 103 women) in the Whitehall II cohort drawn equally from the range of employment grades. Plasma was assayed for levels of Hsp60, tumor necrosis factor α (TNFα), C-reactive protein, von Willebrand factor, high density lipoprotein (HDL), total cholesterol, and total/HDL ratio. Psychosocial measures included socioeconomic status, psychological distress, and social isolation. The majority of the participants had Hsp60 in their plasma, and ≈20% had >1000 ng/mL of this protein (a concentration likely to induce biological effects). A positive association between plasma Hsp60 and TNFα and a negative association with von Willebrand factor was found. There was also a significant association between elevated Hsp60 levels, low socioeconomic status, and social isolation, together with an association with psychological distress in women. Conclusions — The majority of participants exhibited Hsp60 in their plasma, and there was evidence of an association between levels of this stress protein and the proinflammatory cytokine, TNFα, and with various psychosocial measures.