Osteocyte apoptosis regulates osteoclast precursor adhesion via osteocytic IL-6 secretion and endothelial ICAM-1 expression

► Osteocyte apoptosis promotes osteoclast precursor adhesion to endothelial cells. ► Osteocyte apoptosis induces increased ICAM-1 expression in endothelial cells. ► Blocking ICAM-1 abolishes apoptosis-induced osteoclast precursor adhesion. ► Apoptotic osteocyte culture contains more IL-6 and sIL-6R than non-apoptotic culture. ► Both IL-6 and sIL-6R are required for endothelial activation.