Role of alfacalcidiol on bone quality and immunomodulation in autoimmune disease and organ transplantation.
In autoimmune diseases, as well as in organ transplantation, corticosteroids are often an obligatory part of the treatment regimen. The deleterious effect of corticosteroids on bone metabolism is well known, although still controversial [1-3]. It is easier to maintain bone mass than to restore it. Although the treatment of choice for prevention of bone loss is hormone replacement therapy, it cannot always be applied, and for many reasons compliance is low over the world. Alternative strategies to prevent bone loss are now tried out in many centers. Calcitonin and bisphosphonates are well-known antiresorbing drugs, but costs and long-term efficiency for calcitonin and fear for bone toxicity for the bisphosphonates limits their use for prevention. An attractive strategy to prevent osteoporosis is the treatment with alfacalcidiol because it is a natural product with important effects on bone metabolism in physiological and pharmacological dosages. Calcium absorption from the gut and mineralization of the bone matrix are optimalized by alfacalcidiol. The purpose of this paper is to report on our experience with alfacalcidiol concerning bone mass and quality in corticosteroid-induced osteoporosis in experimental animals and on long-term bone quality in autoimmune diseases and organ transplantation. We have studied the effects of alfacalcidiol on bone mass and quality in ovariectomized animals with and without corticosteroids. In these fundamental studies we have found that alfacalcidiol had a profound protective and curative effect not only on bone mass but also on bone quality as tested by mechanical testing, namely, impact torsional loading test of whole bones. The combination of alfacalcidiol with estrogens was less effective than alfacalcidiol, but more effective than estrogens alone [4-6] (Fig. 1).
Dequeker
J
J
Arthritis and Metabolic Bone Disease Research Unit, University Hospitals, K.U.Leuven, Weligerveld 1, B-3212 Pellenberg, Belgium.
Van Cleemput
J
J
Declerck
K
K
Mbuyi-Muamba
J M
JM
D001327:Autoimmune Diseases; D001862:Bone Resorption / Q000517:prevention & control*; D002112:Calcifediol / Q000627:therapeutic use*; D006801:Humans; D016377:Organ Transplantation
D002112:Calcifediol