To improve quality of life we need to get to grips with the minute intricacies of psoriatic arthritis, reports Dr Ryan Malcolm Hum

Psoriatic arthritis is one of the most common types of inflammatory arthritis after rheumatoid arthritis. It can cause joint pain, swelling and stiffness and affects about 25% of people who have psoriasis. Psoriasis and psoriatic arthritis are both autoimmune conditions caused by a fault in the immune system which makes it attack healthy parts of the body, causing inflammation.

The complex nature of psoriatic arthritis often leads to misdiagnosis, as symptoms are similar to those of other conditions. Such diagnostic challenges can impede timely intervention, contributing to poor outcomes.

To improve outcomes for people with psoriatic arthritis we need to understand the condition’s unique characteristics by using new technology to make detailed assessments of what happens in the blood, synovial fluid, and synovial tissue.

Challenges

We have more treatments than ever before for psoriatic arthritis, including tablets known as JAK inhibitors, and injections which target specific molecules that are involved in psoriatic arthritis. Yet people still experience lower quality of life and suffer from poor health, which can reduce life expectancy. This is partly because psoriatic arthritis is considered through the same lens as rheumatoid arthritis by many doctors and researchers.

Joint counts, where doctors examine the joints by feeling for swelling and squeezing the joints to see if they are tender, are great at monitoring disease in rheumatoid arthritis where hands and wrists are affected. However, we know that psoriatic arthritis more often affects large joints which are not measured in some of the standard assessments used commonly in clinic.

Psoriatic arthritis is also distinct from rheumatoid arthritis as it is associated with skin, eye, gastrointestinal, spine and tendon involvement. To better serve our patients with psoriatic arthritis we need to understand what is going on in the blood and in the joints in psoriatic arthritis, and how this differs to rheumatoid arthritis.

Ultrasound

As joint counts can underestimate disease severity in psoriatic arthritis, we use ultrasound scanning of the joints to get an accurate idea of which joints are inflamed as part of our research studies. It takes about an hour to scan the hands, wrists, elbows, knees, ankles and toes.

Patients in our study undergo ultrasound scanning to characterise disease activity. They generously donate blood samples, fluid taken from the joints using a needle, and samples of joint tissue. Katarzyna Lachawiec is one of our inspirational study patients who still had active disease despite treatment.

Using advanced technologies, we isolate the cells and characterise how they look and behave. As we have cells from three different places, we hope to see how cells move and change from the bloodstream to the joint fluid and then eventually into the joint tissue to cause inflammation. If we can understand this process, we might be able to develop better drugs and treatments to fix or block these disease-causing pathways so that the inflammation in psoriatic arthritis becomes completely controlled (remission).

Synovial biopsies

We know from previous studies in rheumatoid arthritis that looking at cells in the blood only gives us a snapshot of what is happening. To be able to see what happens in the joint itself we can take samples of joint fluid in clinic by inserting a small needle through the skin into the joint. Looking at the cells in the joint fluid and the blood gives us an even better picture of what is happening.

Finally, to see what is happening in the inflamed joint tissue, we can now do ultrasound-guided synovial biopsies using special biopsy needles. Prof Pauline Ho from Manchester Royal Infirmary, part of Manchester University NHS Foundation Trust, has pioneered this technique and is now a leader in performing synovial biopsies for research purposes.

Single cell technologies

New genomic technologies now allow us to look at individual cells from patients at an affordable cost. Using these state-of-the-art technologies we can identify different cell types, see what cells are doing, how they interact, develop and travel.

We are examining the blood, synovial fluid and synovial tissue from people with psoriatic arthritis and comparing this to people with rheumatoid arthritis who have active disease detected on ultrasound scanning of 66 joints. This is thanks to funding from the National Institute for Health and Care Research Manchester Biomedical Research Centre, the British Society for Rheumatology, and the British Psoriatic Arthritis Consortium.

By understanding which cells cause problems and disease we hope to be able to discover and develop better treatments, and improved ways of monitoring disease activity and remission. The outcome will be better quality of life for people with psoriatic arthritis.

PS Did you know that Arthritis Digest Magazine is labelled the best UK Arthritis blog from thousands of blogs on the web ranked by traffic, social media followers, domain authority & freshness?

Dr Ryan Malcolm Hum is a Specialist Registrar in Rheumatology & Honorary Academic Clinical Fellow at the Manchester University NHS Foundation Trust and The University of Manchester and Trainee Representative for the British Psoriatic Arthritis Consortium