New research could lead to a blood test that indicates a person´s likelihood of suffering from rheumatoid arthritis (RA).
Scientists at the Kennedy Institute of Rheumatology at Oxford University found that a blood test that looks for antibodies which recognize the protein tenascin-C could reliably identify those who will contract the condition — even up to 16 years before symptoms start to show.
This is a promising new development because rheumatoid arthritis can be difficult to diagnose: many conditions cause joint stiffness and inflammation and there is no definitive test for the condition. Yet early diagnosis can make it easier to control its progression.
Reporting on the study, Oxford University said that when inflammation occurs in the body, some proteins are altered in a process called citrullination. These altered forms can prompt an immune response from the body which sees it turning antibodies on itself, causing rheumatoid arthritis.
Tests that spot antibodies to citrullinated proteins are already used to diagnose the disease. According to Oxford University, tests for individual proteins usually have a relatively low diagnostic sensitivity, but a more general test called CCP, which detects synthetic citrullinated peptides, identifies a lot more RA cases.
Lead researcher Dr. Anja Schwenzer said: “We knew that tenascin-C is found at high levels in the joints of people with RA. We decided to see if it could be citrullinated and, if so, whether it was a target for the autoantibodies that attack the body in RA. That might also indicate whether it could be used in tests to indicate the disease.
“When we looked at results from more than 2,000 patients we found that testing for antibodies that target citrullinated tenascin-C (cTNC) could diagnose RA in around 50% of cases, including some cases not identified by CCP. It also has a very low rate of false positives — it is 98% accurate at ruling out RA.”
The Kennedy Institute´s Professor Kim Midwood added: “What is particularly exciting is that when we looked at samples taken from people before their arthritis began, we could see these antibodies to cTNC up to 16 years before the disease occurred — on average the antibodies could be found seven years before the disease appeared.
“This discovery therefore gives us an additional test that can be used to increase the accuracy of the CCP assay and that can predict RA, enabling us to monitor people and spot the disease early. This early detection is key because early treatment is more effective.”