Cadherin-11 mRNA transcripts are frequently found in rheumatoid arthritis peripheral blood and correlate with established polyarthritis

Rheumatoid arthritis (RA) synovial fibroblasts hyperexpress the mesenchymal cadherin-11, which is involved also in tumor invasion/metastasis, whereas anti-cadherin-11 therapeutics prevent and reduce experimental arthritis. To test the hypothesis that cadherin-11 is aberrantly expressed in RA peripheral blood, 100 patients (15 studied serially) and 70 healthy controls were analyzed by real-time reverse transcription-PCR. Cadherin-11 mRNA transcripts were detected in 69.2% of moderately/severely active RA, versus 31.8% of remaining patients (p = 0.001), versus 17.1% of controls (p < 0.0001). Notably, cadherin-11 positivity correlated significantly and independently only with established (> 1 year) polyarthritis (> 4 swollen tender joints), by multivariate logistic regression analysis including various possible clinical/laboratory factors. Rare cells of undefined nature, detected by flow cytometry following CD45(−) enrichment, strongly expressed surface cadherin-11 (estimated 10–50 cells/ml of blood) in 5/6 patients with polyarticular established disease versus 1/6 patients with early RA. Studies on the potential pathogenic role of circulating cells expressing cadherin-11 in RA are warranted.