Amino acid regions 357-368 and 418-427 of Streptococcus pyogenes 60kDa heat shock protein are recognized by antibodies from glaucomatous patient sera

Abstract

Heat shock protein 60kDa (HSP60) could be involved in glaucoma because its expression in optical nerve, and autoantibodies to HSP60 have been found in glaucomatous patients; however, HSP60 antigenic sites recognized by glaucomatous patients are unknown. Therefore, in this work, the antibody levels in the sera of glaucoma patients, and HSP60 antigenic sites were determined. Analysis by the Hopp and Woods method with GENE 2.2 software identified the possible antigenic sites in the amino acid regions 200-213, 226-237, 278-290, 357-368 and 418-427 of Streptococcus pyogenes HSP60 (HSP60Sp). According to these, polypeptides were generated truncating the hsp60Sp gene by PCR. Antibody levels to HSP60Sp and the generated polypeptides were measured by ELISA in serum of glaucomatous patients and in healthy subjects. Glaucomatous patients showed higher antibody levels to rHSP60Sp (p=0.002) than healthy subjects. We found that the high anti-rHSP60Sp antibody levels are associated with the disease (OR=5.2; IC95% of 1.6-16.7; p<0.05). Here we report that amino acid regions 357-368 and 418-427 of HSP60Sp are the main antigenic sites, because when they are absent the level of anti-HSP60 antibodies decreased around 80%. These results suggest that the regions 357-368 and 418-427 of HSP60Sp could be associated with glaucoma.