Cheek Swab Test Could Identify Biomarkers for Rheumatoid Arthritis

In the study, researchers from Washington State University (Pullman, WA, USA) and Arthritis Northwest (Spokane, WA, USA) identified a set of epimutations in cells from women who had rheumatoid arthritis that were distinct from those without the joint-damaging autoimmune disease. Epimutations are molecular factors and processes around DNA that regulate genome activity, independent of DNA sequence. The discovery could advance treatment for rheumatoid arthritis. While current drug treatments have limited efficacy in many patients who have already developed the disease, some studies have shown that treatments begun in early stages of the disease can cause remission of symptoms. Having biomarkers could allow treatment to begin even earlier before the first signs of it start.

For the study, researchers collected buccal, or cheek, cells using a swab from two cohorts of women: a group of 26 Caucasian women and a group of 23 African-American women. In each group, about half of the women had rheumatoid arthritis with the other half serving as a control. Even though they are taken from the cheek, buccal cells allowed the researchers to conduct an epigenome-wide analysis. Translating literally as “above” the genome, an epigenome consists of chemical factors that can modify the genome and change its behavior. While not part of DNA itself, epimutations can still be passed down to subsequent generations.

In this study, the researchers found epimutations in areas called DNA methylation regions, among the women in both groups who had rheumatoid arthritis. The study was designed to see if there were differences between racial groups since African Americans have shown some signs of increased prevalence of rheumatoid arthritis. However, while some differences were noted, the researchers found a large overlap in epimutations among women with rheumatoid arthritis of both races, meaning the identified biomarkers hold a strong signal for the disease.

The findings add evidence that the disease is likely systemic, meaning it was found not just in immune system cells involved in rheumatoid arthritis development but in many different cells throughout the body. The research team also tested an immune-related monocyte cell type in blood samples from a portion of the women, but the buccal cells showed the epimutations as well, indicating that a relatively non-invasive diagnostic cheek swab test could be developed to screen for the disease.

“If we can identify these patients 10 years earlier before the disease develops, it opens up a whole arena of preventative medicine that we did not have access to before,” said Michael Skinner, a professor in WSU’s School of Biological Sciences.

Related Links:
Washington State University 
Arthritis Northwest