Scientists Explore Why Some Psoriasis Patients Suffer Joint Damage

Jun. 22, 2010
Cellular Markers Might Suggest who is at Greatest Risk for Psoriatic Arthritis
Christopher Ritchlin, M.D., M.P.H.

A new grant from the National Psoriasis Foundation could help University of Rochester Medical Center (URMC) scientists find ways to forecast which patients with the red, flaky skin disorder are most likely to suffer from an arthritic disease that sometimes follows. 

“One in five patients with psoriasis is at risk for bone destruction, too,” said grant recipient Christopher Ritchlin, M.D., M.P.H., a professor of Medicine at URMC. “With this funding, we hope to glean insights into the psoriasis-arthritis connection, so that we can one day identify patients who are most at risk for joint damage and start them on more aggressive therapies.”

Psoriasis, which affects an estimated 7.5 million Americans, occurs when the immune system sends out faulty signals, ultimately accelerating skin cells’ growth cycles. The result is raised, ruby patches of skin, or silvery colored scales from dead skin pile-up. While psoriasis is not contagious, it’s been linked with a number of other serious health issues, like diabetes and heart disease; its unpleasant appearance can stir up social stigmas, too, sometimes injuring self-esteem, leading to isolation and depression.

Photo courtesy of the NIH image bank

With the $200,000 grant, Ritchlin and colleagues plan to spend two years following between 60 and 100 patients with both psoriasis and psoriatic arthritis. Over that time, they’ll track how popular medications (like methotrexate and newer anti-TNF drugs) affect participants’ levels of DC-STAMP – a molecule that plays a role in autoimmunity and the formation of osteoclasts, or bone-absorbing cells. Ritchlin’s team, in concert with URMC professor of Orthopedics Edward Schwarz, Ph.D., was the first ever to implicate DC-STAMP as a potential biomarker for any form of arthritis, igniting a blaze of similar research in the field.

“We’re eager to find if measuring the level of a molecule like DC-STAMP could clue us in, perhaps years before onset, that a patient is likely going to suffer psoriatic arthritis,” Ritchlin said.  

The more he and other researchers understand DC-STAMP and how it influences arthritic disease, the better, he said.

“Markers don’t have to be perfect predictors to be helpful in the clinic,” he explained. “For instance, 20 percent of patients with rheumatoid arthritis still test negative for the marker, rheumatoid factor. It’s not foolproof. But even if we had that kind of predictive power for psoriatic arthritis, dermatologists would be able to partner better with rheumatologists to settle on which patients were candidates for aggressive medications earlier on in the disease.”Current therapies for psoriatic arthritis are very effective – perhaps even what some would consider miraculous, Ritchlin noted.

“Still, these medicines aren’t without risk and side effects, so you don’t want to prescribe them to all psoriasis patients across the board,” he said. “That’s why a marker is so important. You’d want to be able to parse out the people at biggest risk for future joint damage, and you’d want to do this early, because the therapies don’t reverse damage – they simply keep it from worsening.”

In addition to his work with DC-STAMP, Ritchlin and other members of the research team (including Schwarz, Francisco Tausk, M.D., Grace Chiu, Ph.D, Beth Marston, M.D., Ralf Thiele, M.D., Vaseem Chengazi, M.D., Johnny Monu, M.D., Sharon Moorehead and Rick Barrett) are studying another possible marker: the molecule CD-16, which some scientists think also plays a role in the process by which bone-dissolving cells are born. Since psoriatic arthritis can rear its head years, even a decade after the onset of psoriasis, his team is currently following patients who have had psoriasis for seven years or more, but not psoriatic arthritis. The hope is that they will observe onset of joint inflammation in patients as it happens, employing blood tests and imaging scans to track how these potential markers fluctuate in real-time. The study is funded by a $350,000 grant from California-based Amgen, a human therapeutics company that produces anti-TNF drugs.

In addition to seeing patients and conducting research, Ritchlin heads up one of the six sites comprising the International Psoriatic Arthritis (IPART) database. Funded by the Canadian Institutes of Health Research, the registry pools data from nearly 4,000 psoriasis patients across Canada and the U.S. The registry dovetails neatly with clinical efforts underway in URMC’s dedicated Psoriasis Center – one of the few recognized psoriasis centers nationwide, with a unique multidisciplinary approach that not only focuses on skin lesions, but also the joint pain of and psychological components of the disease.

To learn more about the Psoriasis Center, call (585) 487-1440.

Ritchlin has served as a consultant to Amgen, Wyeth, Abbott, Roche, Calcimedica, Centocor and Bristol-Myers Squibb, and has received research funding from Centocor, Abbott, Roche, Calcimedica, Amgen and Bristol-Myers Squibb.