Psoriatic arthritis research

Psoriatic arthritis, a chronic inflammatory disease of the joints and connective tissue, was first described in 1818 by a French physician, Baron Jean Louis Alibert, but it was not until the 1950s that it was classified as distinct from other arthritic diseases.

Psoriatic arthritis is associated with psoriasis on the skin. Approximately 10 percent to 30 percent of people with psoriasis develop psoriatic arthritis, although it often may go undiagnosed, particularly in its milder forms. It can develop at any time, but for most people it appears between the ages of 30 and 50. Psoriatic arthritis seems to affect men at a slightly higher percentage than women.

Both genetic and environmental factors seem to be associated with the development of psoriatic arthritis. The immune system plays an important role.

There are similarities in the chemical players and cytokines between rheumatoid arthritis and psoriatic arthritis such as the prominent role of TNF-alpha. However, psoriatic arthritis differs from rheumatoid arthritis in the chemicals that lead to inflammation in the synovium, a thin membrane in freely moving joints that lines the joint capsule and secretes fluid to protect the joint.

Psoriatic arthritis also differs because the initial pathology (beginning of the disease) is in the enthesis rather than in the synovium. The enthesis is where the tendons, ligaments and connective tissue (fascia) inflame where they connect to the bone. In certain cases, this inflammation may lead to calcification at the insertion site. The most commonly affected areas are the heels where the Achilles tendon and the plantar fascia insert. This can lead to pain when standing or walking.

International researchers have acknowledged these differences by forming an organization known as GRAPPA, the Group for Research and Assessment of Psoriasis and Psoriatic Arthritis. GRAPPA is working to define the tools used in measuring psoriatic arthritis treatment success, including outcome measures and international treatment guidelines. The effort and excitement surrounding psoriatic arthritis research bodes well for the community, leading to encouraging news about treatment options and more accurate assessment scores.