NATURALLY-OCCURRING INFLAMMATORY ARTHRITIS OF THE SPONDYLOARTHROPATHYVARIETY IN CAYO-SANTIAGO RHESUS MACAQUES (MACACA-MULATTA)

Objective: The establishment of an animal model is a major priority in the battle to control inflammatory arthritis. Exploration to date has not yet identified a viable model for rheumatoid arthritis (RA), whil e artificial (e.g., collagen-induced) models do not seem to accurately represent RA. They, at least superficially, resemble human spondyloar thropathy. This study assesses the evidence for a common naturally-occ urring spondyloarthropathy in a colony of free-ranging rhesus macaques . Methods: Skeletal elements of 275 Macaca mulatta of known age and tr oop affiliation from the Cayo Santiago colony [Caribbean Primate Resea rch Center (CPRC)] were surveyed for the presence of spondyloarthropat hy and osteoarthritis. fisher exact tests established the independence of each pathological condition, age, sex, troop and specific joint. R esults: Spondyloarthropathy was evident in 10% of females and 7% of ma les. In surviving troops, its frequency in 82 animals over 8 years of age was 20%. The skeletal distribution of spondyloarthropathy was inde pendent of troop membership. Osteoarthritis affected 20% of females an d 4% of males and was independent of their troop. Significant differen ces in the frequencies of specific joint involvement were found when t he natural model, particularly in the polyarticular subgroup, was comp ared to the collagen-induced model. Conclusions: Naturally-occurring s pondyloarthropathy afflicts 20% of susceptible-aged individuals in sur viving macaque troops a the CPRC. This phenomenon appears to present a unique natural model for the characterization of the genetic, immunol ogical and environment contributions to this disease, which afflicts 0 .5 - 5% of the human population. This natural model would appear to su pplant the need for the collagen-induced large animal model.