The promoter polymorphism of the IL-6 gene is associated with levels of antibodies to 60-kDa heat-shock proteins

Abstract

Elevated levels of antibodies to 60 kDa heat shock proteins are associated with severe coronary heart disease and carotid atherosclerosis. The presence of self hsp60-reacting antibodies can only be partially explained by microbial infections and induction by bacterial hsp65 proteins, since important differences (including the epitope specificity and complement activating ability) between hsp60 and hsp65 reacting antibodies have been shown. The aim of this study was to investigate the possible effects of genetic polymorphisms of different genes of proinflammatory cytokines on anti-hsp60 autoantibody levels. One hundred and seventy-six male blood donors were recruited and antibody levels to human hsp60 and Mycobacterium boris hsp65 were determined by ELISA. Also in these donors, polymorphisms of the promoter of the IL-6 gene at position -174, the biallelic base exchange of the IL-1β gene at the -511 position and the IL-1α gene at position -889 were investigated by PCR. A strong association between IL-6 -174 polymorphism and anti-hsp60 antibody levels was seen; the effect on anti-hsp65 antibody was less marked. Carriers of allele C at this position had significantly lower levels of anti-hsp60 and anti-hsp65 antibodies. A lack of associations between IL-1β and IL-1α gene polymorphisms and antibody levels was detected. This is the first study in which associations between genetic polymorphisms and autoantibody levels have been described in healthy subjects. Further studies are needed to gain insight into the detailed mechanism of how the IL-6 gene polymorphism at position -174 influences anti-hsp60 autoantibody levels.