Article
The role of osteoprotegerin (OPG) in patients requiring surgery for coronary heart disease
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Authors
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Daniela Malliga
- Universitätsklinik für Chirurgie, Klinische Abteilung für Herzchirurgie, Graz
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Birgit Zirngast
- Universitätsklinik für Chirurgie, Klinische Abteilung für Herzchirurgie, Graz
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Ameli Yates
- Universitätsklinik für Chirurgie, Klinische Abteilung für Herzchirurgie, Graz
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Drago Dacar
- Universitätsklinik für Chirurgie, Klinische Abteilung für Herzchirurgie, Graz
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Karin Amrein
- Department of Internal Medicine, Division of Endocrinology and Metabolism, Graz
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Astrid Fahrleitner-Pammer
- Department of Internal Medicine, Division of Endocrinology and Metabolism, Graz
| Published: | April 26, 2013 |
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Outline
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Introduction: Osteoprotegerin (OPG) is membrane bound in the immune system but can also be produced and secreted almost everywhere in the organism, so that it is mainly available in soluble form. So far, the OPG/RANKL/RANK system has been most intensively studied in bone. The binding of RANKL on its receptor RANK, which is expressed by osteoclasts, activates a number of osteoclastic cell functions. OPG also has a key function in the vascular system. Patients with coronary heart disease (CAD) have elevated OPG serum levels, probably as a sign of ischemic or inflammatory endothelial damage. Elevated OPG levels were also found in patients with advanced heart failure, whereby OPG correlated with pro BNP (brain natriuretic peptide) and was a predictor for cardiovascular morbidity and mortality.
Material and methods: Our prospective cohort study will include 150 men (75 patients requiring surgery for CAD and a control group without coronary heart disease). The primary endpoints are the differences between the two groups in serum levels of OPG and RANKL, markers of bone metabolism (osteocalcin [OC], crosslaps [CTX], tartrate resistant acid phosphatase (TRAP5b), 25 (OH) vitamin D [Vit D], 1.25(OH) vitamin D, parathormone [iPTH], lipid, inflammatory and endocrine parameters related to vascular damage (e.g. aldosterone, renin and cortisol) and bone mineral density. Metabolomic based biomarkers will be evaluated to explore the mechanisms behind OPG-RANKL linked CVD damage. In the patients further studies of the mRNA expression of OPG, RANKL, TRAP5b, arginine:glycine amidinotransferase (AGAT) and osteocalcin in bone (sternum sliver) and vascular wall (aorta, internal thoracic artery and the great saphenous vein) will be performed.
Conclusion: CAD and osteoporosis are increasingly prevalent diseases that overlap. In both entities, OPG plays a role not only in pathogenesis but also as an outcome predictor. We aim to study the relevance of OPG concentration not only in serum but also in the vessel wall and bone.
