Broader Context
The period was a fruitful one for psoriatic arthritis more broadly. Earlier evidence provided by Moll and others had suggested a genetic contribution to the disease that was likely multifactorial in nature.1
In another 1973 paper, Moll and Wright published a family study of over 100 probands with psoriatic arthritis and over 300 of their relatives.10 The results bolstered their earlier conclusion that psoriatic arthritis is a disease in and of itself, and confirmed previous reported linkages between psoriatic arthritis and ankylosing spondylitis. It also suggested genetic factors were involved in the disease etiology.
Notes Dr. Ritchlin, “They were among the first to report that this is a highly familial, inherited disease.”
“What is really interesting is that in 1973, the year both [Moll and Wright] papers came out, a group at UCLA reported the HLA-B27 association with ankylosing spondylitis in the New England Journal of Medicine,” Dr. Ritchlin continues.11 “This was really a banner year for spondyloarthropathies. That paper came out, and then a second paper on HLA-B27 came out from a group in England on ankylosing spondylitis.”12 These key papers helped further establish the genetic nature of the disease underlying its distinctive pathophysiological nature.
Moll and Wright’s major contributions extended beyond psoriatic arthritis into other forms of seronegative arthritis. In 1974, the pair published another seminal paper, this one describing the seronegative arthritis group and systematically itemizing their similarities and distinctions: “Associations Between Ankylosing Spondylitis, Psoriatic Arthritis, Reiter’s Disease, the Intestinal Arthropathies, and Behçet’s Syndrome.”13 Here they identified “an interesting group of non-rheumatoid disorders in which striking clinical and familial inter-relationships can be demonstrated.”
As Dr. Ritchlin relates, “Moll and Wright worked together for quite a long time. I would say this is an apogee of their work, this paper on psoriatic arthritis and the one on the family of spondyloarthropathies published the following year. These two years were really incredibly important in terms of unveiling the group of spondyloarthropathies and their clinical and genetic similarities.”
Gradual Recognition
Although Moll and Wright’s paper helped solidify the concept of psoriatic arthritis in the medical literature, some hesitancy persisted. This remaining resistance impeded future research and slowed the progression of knowledge about the disease. At the time, much less research was being performed on psoriatic arthritis than on other arthropathies, especially rheumatoid arthritis and ankylosing spondylitis.14
For example, in the mid-1970s, Dr. Espinoza and colleagues attempted but failed to obtain research funding for psoriatic arthritis from both the Canadian Rheumatology Society and the U.S. National Institutes of Health. Dr. Espinoza says, “According to grant reviewers, the main reason given for rejection was that psoriatic arthritis was not considered a distinct disorder and that most likely it was rheumatoid arthritis in patients with psoriasis.” He adds that Moll and Wright’s 1973 paper and later publications building on this work helped provide the evidence to eventually dispel that belief.
But this transition took time. Dr. Ritchlin describes the research in psoriatic arthritis he began in 1992. “There was little research going on in the field at that time, so we’re talking 20 years later. It was still pretty much a wide-open territory. It wasn’t until the late ’90s or early 2000s that things started to take off. That’s when we recognized that tumor necrosis factor was important in this disease, and we saw the first phase 2 trials showing it was very effective in psoriatic arthritis. Now it’s very clear that these diseases are very different from both the mechanistic and therapeutic point of view.”