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Published in Nature Communications, the study represents the largest and most comprehensive molecular analysis of osteoarthritis tissue to date. The findings provide a long-awaited answer to a fundamental question that has challenged the OA field for decades and opens the door to more targeted and effective treatments for millions of people living with OA.
The STEpUP OA (Synovial fluid To detect Endotypes by Unbiased Proteomics in OA) project brought together scientists from Europe, Canada, and the UK, and includes a number of industry and charity partners. Researchers analysed synovial fluid – the lubricating fluid in the knee joint – from more than 1,300 people with established knee OA, using a cutting-edge proteomics platform (SomaScan v4.1, SomaLogic) that measured over 7,000 proteins per sample.
By comparing molecular patterns in these samples, the team sought to answer a crucial question: is OA really "one disease," or are there multiple distinct subtypes (endotypes), each requiring its own treatment approach?
Professor Tonia Vincent, lead investigator and Director of the Arthritis UK Centre for OA Pathogenesis at the Kennedy Institute of Rheumatology (KIR), said: 'For decades, the field has debated whether OA is really a group of separate diseases, perhaps explaining why so many clinical trials have failed. We revealed no evidence of distinct disease subtypes, instead, we've demonstrated that at the molecular level OA is a single disease with a common set of "core" pathways, mostly related to tissue injury and repair.'