Purpose of review: We reviewed the current literature on the roles of the Wnt antagonists sclerostin (Sost) and sclerostin-containing domain protein 1 (Sostdc1) on bone homeostasis, the relationship of the hypoxia-inducible factor (Hif) and von Hippel-Lindau (Vhl) pathways on Sost expression, and how changes in bone induced by depletion of Sost, Sostdc1, and Vhl affect hematopoietic cells.
Recent findings: B cell development is adversely affected in Sost-knockout mice and is more severely affected in Vhl-knockout mice. Inflammation in the Sost-/- bone microenvironment could alter hematopoietic stem cell behavior. Sostdc1-/- mice display defects in natural killer cell development and cytotoxicity. Depletion of Sost and Sostdc1 have effects on immune cell function that warrant investigation in patients receiving Wnt antagonist-depleting therapies for treatment of bone diseases. Additional clinical applications for manipulation of Wnt antagonists include cancer immunotherapies, stem cell transplantation, and directed differentiation to immune lineages.
Keywords: Cell differentiation; Hematopoiesis; Immunology; Osteoimmunology; Wnt; Wnt antagonists.