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Rheumatoid arthritis may differ by location
Researchers recently discovered that cellular differences in joints are associated with joint-specific differences in rheumatoid arthritis.
Investigators Wei Wang, PhD, and Gary S. Firestein, MD, both of the University of California, San Diego School of Medicine, and colleagues examined epigenetic patterns in fibroblast-like synoviocytes (FLS) — a specialized cell type that coats the inside of joints.
"We hypothesized that changes in epigenetic modifications and gene expression between FLS in different joints might potentially contribute to differences in synovial inflammation and responses to clinical treatment," Wang, professor in the departments of chemistry and biochemistry, and cellular and molecular medicine, said in a press release.
Gary S. Firestein
Results of the study determined that the fundamental process of DNA methylation varies between FLS of the knees and hips in patients with rheumatoid arthritis (RA).
"We showed that the epigenetic marks vary from joint to joint in diseases like [RA]," said Firestein, director of the Clinical and Translational Research Institute at UC San Diego School of Medicine. "Even more importantly, the differences involved key genes and pathways that are designed to be blocked by new RA treatments. This might provide an explanation as to why some joints improve while others do not, even though they are exposed to the same drug."
The discovery offers a new foundation for the treatment of all ailing joints, according to the researchers.
Firestein concluded that the research "opens up the potential for precision medicine approaches that allow us to target all of the joints, not just a subset. It has broad implications for how we evaluate new drugs in clinical trials as well."
Disclosure: The researchers report no relevant financial disclosures.
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Ai R, et al. Nat Commun. 2016;doi:10.1038/ncomms11849.