The role of OPG, RANK, RANKL in the bone metabolism, cardiovascular disease and immune system: Clinical and physiopathological implication

The bone remodelling process is characterized by alternate phases of production and resorption of the mineralized matrix, is possible by two types of cells: osteoblasts and osteoclasts. When these ones are subject to hormonal and cytokines stimulus, they express and produce a lot of proteic molecules that play an essential role in regulating the processes of activation and inhibition of osteoclastogenesis. Three molecules have been the subject of intense research in the field of bonebiochemistry: OPG, RANK and RANKL. OPG is a glycoprotein belonging to the TNFR superfamily. The importance of this molecule is confirmed by the presence of specific domains, that are essential for the osteoclastogenesis inhibition. OPG makes it by binding with RANKL. This event prevents the binding of RANKL to RANK, that is expressed in the osteoclasts, and inhibits the differentiation of pre-osteoclasts in mature osteoclast, RANKL is a peptide produced by osteoblasts cells. We review the physiopathologic implications of this molecules, and their implication in the immune and vascular system. Infact in the former it has been observed that RANKL expressed in the activated T cells, binds with RANK determining a inummomodulator final effect; in the latter it has been possible to observe that RANK and RANKL are expressed by endothelial cells, and regulate their survival.