Identification of candidate microbial sequences from inflammatory lesion of giant cell arteritis.

Giant cell arteritis (GCA) is a granulomatous inflammatory disease of medium and large arteries which is prevalent in the elderly population. The etiology of GCA is unknown, although the immunologic features suggest the possible presence of a microorganism. Our group has examined whether microbial DNA fragments were present at GCA lesions and whether such microbial fragments could be associated with disease pathogenesis. Initial identification of microbial sequences was performed using genomic representational difference analysis (RDA). Laser dissecting microscopy was used to isolate cells from GCA lesions and adjacent uninvolved temporal artery. Using genomic RDA, we isolated 10 gene fragments; three of these sequences had high homology with prokaryotic genes and were considered high-priority candidates for further study. An examination of serum from GCA(+) individuals (in contrast to healthy age-matched controls) showed the presence of IgG which recognized in vitro translated proteins from these clones.