Psoriatic arthritis is a chronic inflammatory disease that causes pain and inflammation in the joints and the areas where ligaments and tendons connect to bone. About 30% of people living with psoriasis develop psoriatic arthritis.

Experts’ understanding of the causes of this disease and how best to treat it is continually growing. This article provides a summary of new and ongoing research into psoriatic arthritis.

Many types of cells release small proteins called cytokines, which regulate how cells communicate with each other. Research indicates that cytokines of the interleukin-17 (IL-17) family play a vital role in controlling infections. However, having too many IL-17 cytokines contributes to the development of several autoimmune diseases, including psoriasis and psoriatic arthritis.

Advancements in knowledge about these cytokines have led to new medications that target these pathways, including IL-17, IL-23, and IL-23/IL-17 inhibitors. Research is ongoing.

A 2020 study concluded that IL-17A inhibitors help prevent inflammation and new bone growth in people with spondyloarthritis. This umbrella term refers to several forms of arthritis, including psoriatic arthritis.

The study’s findings may be particularly helpful for people living with spondylitis. This type of psoriatic arthritis can cause bone fusion in the spine that leads to loss of mobility.

Other research has identified IL-23 as another important cytokine to target with medication. The IL-23 cytokine helps regulate the body’s levels of IL-17.

Targeting IL-23 with medications such as IL-23 inhibitors can help reduce IL-17 levels, potentially improving treatment outcomes for people with psoriasis and psoriatic arthritis.

Several types of IL-23 inhibitors exist. A recent phase 3 clinical study concluded that guselkumab, a type of IL-23 inhibitor that the Food and Drug Administration (FDA) have approved to treat plaque psoriasis, may be an effective treatment for some people with psoriatic arthritis.

Researchers are just beginning to scratch the surface of the genetics of psoriatic arthritis, according to a 2019 report. More knowledge could change how the medical community views and treats the disease.

Estimates suggest that 30–55% of all people with psoriatic arthritis have a parent, sibling, or child with the disease. This recurrence within families indicates that genetics play a significant role in the development of psoriatic arthritis.

Close to one-third of those living with psoriasis also have psoriatic arthritis. Currently, researchers understand the genetic basis for psoriasis better than that for psoriatic arthritis.

They have identified more than 60 genetic signals that play a role in psoriasis but only about 20 signals that contribute to psoriatic arthritis. Part of the reason for this is that researchers have not tested and analyzed as many psoriatic arthritis samples.

Not everyone with psoriasis or psoriatic arthritis has the same combination of genes that leads them to develop these conditions. There is a need for genome-wide studies on people with psoriatic arthritis to help scientists better understand the role of genetics in this disease.

Understanding which genes play a role in the disease’s signaling pathways can help scientists discover more effective targeted treatments. The hope is that they will eventually develop treatment plans that are unique to a person’s genetic makeup.

Researchers continue to explore new treatments to reduce the severity of psoriatic arthritis symptoms and slow the progression of the disease.

New JAK inhibitor

Janus kinase (JAK) inhibitors are a type of disease-modifying antirheumatic drug that doctors use to treat inflammatory diseases, including psoriatic arthritis. The FDA have approved the JAK inhibitor upadacitinib for rheumatoid arthritis. New research suggests that it shows promise in treating some people with psoriatic arthritis.

In a recent study, researchers found that people with psoriatic arthritis who used upadacitinib showed improvements in their symptoms. The study participants had shown intolerance or no improvement when using biologic medications.

New TK2 inhibitor

Tyrosine kinase 2 (TK2) inhibitors help block cytokines that play a role in psoriatic arthritis. Deucravacitinib is a type of oral TK2 inhibitor that the FDA have not yet approved.

At the 2020 meeting of the American College of Rheumatology, researchers presented the abstract of a study that found that deucravacitinib was a generally safe and effective treatment for people with psoriatic arthritis. Further research is underway.

Research has shown that people with psoriatic arthritis have a 43% higher risk of heart disease compared with the general population. Experts believe that this is due not only to the disease itself but also to increased rates of inflammation, diabetes, and obesity.

Many people with psoriatic arthritis who develop clogged arteries do not have any symptoms of heart disease. Detecting heart disease risk earlier could improve outcomes.

Another study abstract that featured at the ACR’s 2020 annual meeting reported on the use of ultrasound to measure the thickness of the carotid artery in people with and without psoriatic arthritis. The study showed that people with psoriatic arthritis were significantly more likely to have a thickened carotid artery than the general population, which suggests an increased risk for heart disease.

The researchers concluded that because people with psoriatic arthritis have a higher risk of heart disease, doctors should regularly monitor their patients with this noninvasive ultrasound technique.

Research into the causes, risks, and treatment of psoriatic arthritis is ongoing. Various targeted treatments, including IL-17, IL-23, JAK, and TK2 inhibitors, show promise in treating psoriatic arthritis. Researchers are also investigating the role of genetics in psoriatic arthritis and looking at markers for heart disease risk.

New discoveries will help shape future treatment options. Anyone with psoriatic arthritis who wishes to get involved in clinical studies should talk with their doctor about available opportunities that may be suitable for them.