Induction of creatine kinase release from cultured osteoclasts via the pharmacological action of aminobisphosphonates

Abstract

An increase of serum creatine kinase (CK) has been observed in clinical studies of nitrogen-containing aminobisphosphonates (N-BPs). Osteoclasts are thought to be the source of the CK, but there is no clear evidence for the hypothesis. In this study, CK release from rabbit osteoclasts induced by N-BPs was examined in an in vitro culture system. Rabbit bone-derived cells were cultured for 3 days on the N-BPs pretreated cortical bone slices. CK activity in the culture medium was measured at 3 days of culture. The CK activity was increased with all N-BPs at concentrations at which showed antiresorptive activity over 60% inhibition of C-terminal cross-linking telopeptide of type I collagen (CTX-1) release. The maximum induction of CK activity was 2.6 times the control level. The lowest N-BP concentration inducing CK release was 3 times lower than that required to decrease the osteoclast number. Bafilomycin A1, an inhibitor of vacuolar H+-ATPase, abrogated all N-BP actions, including CK release. Bone-derived cells except osteoclasts were insensitive to bafilomycin A1, suggesting that osteoclasts were the source of CK. Regarding the time course, CK release occurred after a 1 day lag time and increased steadily until day 3 of culture. These results show that CK release is induced by N-BPs from osteoclasts at concentrations at which N-BPs show antiresorptive activity over 60% inhibition of CTX-1 release in vitro. These findings explain the mechanism of the CK increase induced by clinical use of N-BPs.Electronic supplementary materialThe online version of this article (doi:10.1186/s40064-015-0848-3) contains supplementary material, which is available to authorized users.

Serum creatine kinase isoenzymes in children with osteogenesis imperfecta

“…Because osteoclasts are considered a major target of the pharmacologic action of BPs, and are rich of cytosolic soluble CKbb, we postulated that this finding could reflect an osteoclast dysfunction inducing CKbb release. Recently, an in vitro study using BP-stimulated rabbit osteo-clasts supported that osteoclasts are the main source of CK release from the bone, and that this phenomenon is an osteo-clast apoptosis-related event [21]. These observations support the hypothesis that BP-induced osteoclast damage could ac-count for serum Ckbb increase in our OI-treated patients, sustaining the role of serum Ckbb as a marker of osteoclast dys-function [6][7][8][9][10][11][12].…”

“…However, the rate of this increase (1.5 U/L/year) was lower than that observed during the first year of treatment (8.33 U/L/ year). In vitro, CK release from osteoclasts exposed to BPs has been shown to be dose-dependent [21]. We therefore ex-pected a linear increase in serum CKbb over the study time due to the pharmacological effect of neridronate accumulation in the bone matrix.…”

“…This finding is in contrast with the undetectable serum CKbb levels observed at this time that reflect the recovery of the antiresorptive activity of osteoclasts. However, the aforemen-tioned in vitro study shows that CK release begins to increase following BP exposure resulting in 60 % inhibition of CTx release [21]. Therefore, low-level BP exposure may occur, resulting in anti-resorptive activity not mediated by osteoclast apoptosis.…”

“…In 2004, we reported an increased serum CKbb level in 18 children with OI type 1 during the first year of treatment with neridronate [20]. Recently, BP treatment was reported to result in increased CK release from rabbit osteoclasts in vitro [21]. This result explains a possible mechanism for increased serum CK in patients treated with BPs [11,20].…”