Psoriasis is a long-term skin condition that affects millions of people around the world. It often shows up as red, itchy patches covered with silvery scales. For many people, psoriasis mainly affects the skin and is uncomfortable but manageable.
However, for about 20 to 30 percent of people with psoriasis, the disease does not stop at the skin. Over time, it can develop into a much more serious condition called psoriatic arthritis, which causes painful swelling in the joints and can lead to permanent damage to bones and joints if it is not treated early.
For many years, doctors have noticed this connection between psoriasis and joint disease, but they did not fully understand why it happened to some people and not others. Two patients could have similar skin symptoms, yet only one would go on to develop joint pain and stiffness.
This mystery has been frustrating for both doctors and patients, especially because joint damage can be hard to reverse once it begins.
Now, researchers from the Department of Medicine 3 – Rheumatology and Immunology at Uniklinikum Erlangen and Friedrich-Alexander-Universität Erlangen-Nürnberg in Germany have uncovered an important part of this puzzle.
Their study, published in the journal Nature Immunology, explains which immune cells are involved and how they move from the skin to the joints.
To understand this discovery, it helps to know a little about the immune system. The immune system normally protects the body from infections and helps repair damage.
In autoimmune diseases like psoriasis, the immune system becomes overactive and attacks the body’s own tissues. In psoriasis, this attack mainly targets the skin, leading to ongoing inflammation.
The researchers found that inflammation in psoriatic skin creates special immune cells that act like early warning or “starter” cells. These cells are formed in the skin, but they do not stay there.
Instead, they can enter the bloodstream and travel to other parts of the body, including the joints. Dr. Simon Rauber, who led the research group, explained that these immune cells can move from the skin into the blood and then into the joints.
However, the study showed that simply having these immune cells arrive in the joints is not enough to cause arthritis. This was a surprising finding. Many scientists had assumed that once these cells reached the joints, inflammation would automatically follow.
Instead, the researchers discovered that what happens inside the joint itself is just as important.
Inside healthy joints, there are connective tissue cells called fibroblasts. These cells help keep the joint environment stable and balanced. They play a protective role by controlling immune activity and preventing unnecessary inflammation. In people who later develop psoriatic arthritis, this protective system does not work as well as it should.
Professor Andreas Ramming, a senior researcher involved in the study, explained that in patients who develop psoriatic arthritis, the protective function of these fibroblast cells is greatly reduced.
Because of this weakness, the immune cells that enter the joint are no longer kept under control. They begin to trigger inflammation, which leads to pain, swelling, and eventually damage to the joint structure.
This discovery helps explain why only some people with psoriasis develop joint disease. It is not just about immune cells traveling from the skin. It is also about whether the joint tissue can defend itself properly once those cells arrive.
Another important finding from the study is that these skin-derived immune cells can be detected in the blood before any joint symptoms appear.
This means doctors may one day be able to identify patients who are at high risk of developing psoriatic arthritis long before permanent damage occurs. Early detection is especially important because current treatments are much more effective at preventing damage than repairing it.
In the future, this research could lead to new treatment strategies that focus on prevention rather than damage control. Instead of waiting for joint pain to appear, doctors might target these immune cells early or strengthen the joint’s natural protective system. This could stop the disease process before arthritis begins.
The study was supported by several major research organizations, including the German Research Foundation, the European Research Council, and the Interdisciplinary Center for Clinical Research in Erlangen. Their support made it possible to explore how inflammation affects bones and joints at a deep biological level.
Overall, this research marks an important step forward in understanding psoriatic arthritis. It shows that the disease is not caused by a single factor, but by a chain of events involving the skin, the immune system, and the joints.
By identifying both the traveling immune cells and the weakened joint defenses, the study offers a clearer picture of how psoriatic arthritis develops.
In reviewing the findings, the study strongly suggests that psoriatic arthritis may be preventable in the future. If doctors can identify at-risk patients early and intervene before joint inflammation begins, long-term disability could be avoided.
While more research is still needed, this work opens the door to earlier diagnosis, better monitoring, and treatments that protect joints before lasting damage occurs.
If you care about skin health, please read studies about eating fish linked to higher risk of skin cancer, and Vitamin B3 could help prevent skin cancers.
For more health information, please see recent studies about vegetable oil linked to spread of cancer, and results showing Vitamin D could help treat skin inflammation.
Copyright © 2026 Knowridge Science Report. All rights reserved.
