Wednesday, November 28, 2012

Alterations in bone metabolism and HLA B27

S. Schmidt and colleagues presented a study on HLA B27 as a possible risk marker for altered bone metabolism in patients with spondyloarthritis and uveitis without spondyloarthritis as well as healthy carriers of HLA B27. The Wnt antagonists dickkopf 1 (DKK1) and sclerostin were measured. The authors didn’t speculate on osteoporosis, which could be interesting as the levels of healthy carriers are also alterated. Wikipedia: “Currently an anti-sclerostin antibody for the treatment of osteoporosis is being co-developed by Amgen and UCB.” (Paszty C, Turner CH, Robinson MK (September 2010). "Sclerostin: a gem from the genome leads to bone-building antibodies". J. Bone Miner. Res. 25 (9): 1897–904. doi:10.1002/jbmr.161. PMID 20564241) The autors concluded: „These data suggest that alterations in bone metabolism even occur in the absence of clinical SPA and are associated with HLA-B27 carriage.” I think that there is potential for new developments as well as a need to further evaluate these biomarkers in ankylosing spondylitis.

Abstract No. 594
Evidence of Human Leucozyte Antigen-B27 in Healthy Individuals and Patients with Uveitis Is a Risk Factor for Alterations in Bone Metabolism.
Sarah Schmidt1, Stephanie Finzel1, Jürgen Rech1, Matthias Englbrecht1, Silke Winkler1, Isabel Schmidt1, Roula Said-Nahal2, Maxime A. Breban2 and Georg A. Schett3.
1University of Erlangen-Nuremberg, Erlangen, Germany, 2Ambroise Pare’ Hospital (AP-HP), and Versailles Saint Quentin en Yvelines University, Boulogne-Billancourt, France, 3Department of Internal Medicine III and Institute for Clinical Immunology, University of Erlangen-Nuremberg, Erlangen, Germany
Conclusion: HLA-B27 positivity is associated with low levels of DKK1 and sclerostin independent from the presence of clinical symptoms of SPA. Both HLA-B27 healthy carriers as well as HLA-B27 associated uveitis without SPA Sunday, show lower levels of these two Wnt antagonists than normal HLA-B27 negative controls. These data suggest that alterations in bone metabolism even occur in the absence of clinical SPA and are associated with HLA-B27 carriage.

In the meantime Gamsjaeger and colleagues tested transgenic HLA B27 rats, which have a lower mineral/matrix ratio, higher relative proteoglycan, advanced glycation end content and pyridinoline/divalent collagen cross-link ratio, when compared with wild type animals. Therefore they conclude, that this model could be a useful for studies on the pathophysiology of spondyloarthropathy and of pharmacological intervention. 


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