Protein level may serve as predictor of severe osteoarthritis

1st on the web (July 31, 2009)

A group of German, Austrian and Italian researchers reported this week that vascular cell adhesion molecule-1 (VCAM-1) is a strong predictor of hip and knee joint replacement due to severe osteoarthritis (OA).

The study appears in the August issue of Arthritis & Rheumatism.

Led by Georg Schett, MD, of the University of Erlangen-Nuremberg in Erlangen, Germany, the study involved 912 otherwise healthy individuals in Bruneck, Italy, 60 of whom underwent hip or knee replacement surgery due to severe OA in a 15-year follow-up period.
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Subjects underwent a baseline exam in 1990, and investigators performed follow-up exams every 5 years until 2005, according to a press release. They also analyzed blood samples for VCAM-1, a sialoglycoprotein (a combination sugar and protein) expressed on cells in the cartilage and connective tissue.

The results showed that VCAM-1 levels were substantially elevated in the 60 individuals who underwent joint replacement, with the highest baseline levels seen in those who underwent bilateral joint replacement, according to the press release.

“The level of VCAM-1 emerged as a significant predictor of the risk of joint replacement due to severe OA, equaling or even surpassing the effects of age,” the authors said in the press release. They also noted that inclusion of VCAM-1 levels in risk prediction models resulted in a more accurate classification of individuals.

VCAM-1 promotes leukocyte adhesion and homing to sites of inflammation, according to the press release. In chondrocytes, VCAM-1 expression is induced by inflammatory cytokines (ie, proteins released by immune system cells).

The authors suggest that increased VCAM-1 levels may mirror active cartilage damage or an inflammatory component in OA. Since it mediates the interaction of chondrocytes with immune cells, VCAM-1 may also contribute to immune-mediated cartilage damage, according to the press release.

Establishing laboratory biomarkers of severe OA is important for a number of reasons. The standard risk factors of age and weight are not enough for accurate risk prediction, and since OA is a highly prevalent disease, it would be helpful to accurately identify those at greater risk of developing rapid progression or severe disease, the researchers reported.

Early diagnosis would also be beneficial because the disease is present before clinical symptoms are present. Finally, improved prediction of severe OA would help identify patients for treatment interventions such as aerobic exercise, strength training and weight loss and might also help tailor therapeutic measures, according to the release.

“Further clarification of the mechanism underlying the association between VCAM-1 level and OA may well contribute to a better understanding of disease etiology,” the authors said in the press release, adding that application of their findings in routine clinical practice would require further studies to duplicate the results.

Reference:

* Schett G, Kiechl S, Bonora E, et al. Vascular cell adhesion molecule 1 as a predictor of severe osteoarthritis of the hip and knee joints. Arthritis Rheum. 60;8:2381-2389.