Frequency of apolipoprotein E (APOE) allele types in patients with Chlamydia-associated arthritis and other arthritides

Genetic background is important in determining whether certain infecting ba cteria disseminate to the joint and cause arthritis. We assessed whether AP OE genotype is associated with the presence of DNA from Chlamydia or other bacteria in synovial tissues of patients with various arthritides. Nucleic acids from synovial tissues of 135 patients were screened by PCR for DNA fr om Chlamydia trachomatis, C. pneumoniae and other bacteria (pan-bacteria). APOE genotype was determined by a PCR-based method for all patients in each of four resulting groups comprised of about 35 individuals each, positive for C. trachomatis only, C. pneumoniae only, other bacteria, or no bacteria . RT-PCR was used to assess synovial APOE expression. The latter assays con firmed that APOE mRNA is present in synovial tissue. Determination of APOE genotype showed that patients PCR-negative in all assays, and those positiv e in the C. trachomatis- and pan-bacteria- (excluding Chlamydia) directed a ssays, had distributions of the APOE epsilon 2, epsilon 3 and epsilon 4 all eles mirroring;those of the general population (i.e, about 8%, 79% and 13%, respectively). In contrast, 68% of patients with C. pneumoniae DNA in syno vium possessed a copy of the epsilon 4 allele. These results indicate that no association exists between APOE genotype and synovial presence of C. tra chomatis or other bacteria. However, individuals bearing at least one copy of the APOE epsilon 4 allele may be at increased risk for synovial infectio n by C. pneumoniae. (C) 1999 Academic Press.