Donepezil prevents RANK-induced bone loss via inhibition of osteoclast differentiation by downregulating acetylcholinesterase

Abstract

ObjectiveDonepezil, an inhibitor of acetylcholinesterase (AChE) targeting the brain, is a common medication for Alzheimer's disease. Interestingly, a recent clinical study found that administration of this agent is associated with lower risk of hip fracture independently of falling, suggesting its direct effect on bone tissues as well. AChE has been reported to be involved in osteoblast function, but the role of AChE on osteoclastogenesis still remains unclear. We analyzed the effect of AChE and donepezil on osteoclastogenesis in vivo and in vitro.MethodsCell-based assays were conducted using osteoclasts generated in cultures of murine bone marrow macrophages (BMMs) with receptor activator of nuclear factor-kappa B ligand (RANKL). The effect of donepezil was also determined in vivo using a mouse model of RANKL-induced bone loss.ResultsRecombinant AChE in BMMs cultured with RANKL further promoted RANKL-induced tartrate-resistant acid phosphatase (TRAP)-positive osteoclast differentiation. RANKL also upregulated AChE expression in BMMs. RNA interference-mediated knockdown of AChE significantly inhibited RANKL-induced osteoclast differentiation and suppressed gene expression specific for osteoclasts. AChE upregulated expression of RANK, the receptor of RANKL, in BMMs. Donepezil decreased cathepsin K expression in BMMs and the resorptive function of osteoclasts on dentine slices. Donepezil decreased RANK expression in BMMs, resulting in the inhibition of osteoclast differentiation with downregulation of c-Fos and upregulation of Id2. Moreover, administration of donepezil prevented RANKL-induced bone loss in vivo, which was associated with the inhibition of bone resorption by osteoclasts.ConclusionsAChE promotes osteoclast differentiation in vitro. Donepezil inhibits osteoclast function in vitro and prevents bone loss by suppressing bone resorption in vivo, suggesting the possibility that donepezil reduces fracture risk in patients with Alzheimer's disease.

Acetylcholinesterase Inhibitors Are Associated with Reduced Fracture Risk among Older Veterans with Dementia

“…Evidence suggesting a benefit of AChEI use on bone health has slowly emerged . Bone homeostasis is regulated by local autocrine and paracrine mechanisms and neuronal signals from the autonomic nervous system; similarly, the autonomic nervous system is also implicated in dementia .…”

“…Evidence suggesting a benefit of AChEI use on bone health has slowly emerged. (11,13,14,22) Bone homeostasis is regulated by local autocrine and paracrine mechanisms and neuronal signals from the autonomic nervous system; similarly, the autonomic nervous system is also implicated in dementia. (23) Preclinical studies on bone remodeling have shown cholinergic activity induces bone mass accrual by stimulating osteoblast proliferation via muscarinic receptors, and apoptosis in osteoclasts via nicotinic receptors, (24)(25)(26)(27)(28) whereas adrenergic stimulations promote osteoclast formation and bone resorption via beta adrenergic receptors.…”

“…Acetylcholinesterase inhibitors (AChEIs) such as donepezil are approved by the United States Food and Drug Administration (USFDA) for the treatment of AD, and have clinical trial data supporting their use in vascular dementia and Parkinson's disease . in vivo studies show increase in overall bone mass and whole‐body energy among donepezil‐treated mice, possibly by inhibiting receptor activator of NF‐κB ligand (RANKL)‐induced osteoclast differentiation . Studies in human subjects have been very few but suggest that AChEIs may confer protection against fractures, accelerate bone healing, and reduce both fracture complications and all‐cause mortality post‐hip fracture .…”

“…(7)(8)(9) in vivo studies show increase in overall bone mass and whole-body energy among donepezil-treated mice, (10) possibly by inhibiting receptor activator of NF-κB ligand (RANKL)-induced osteoclast differentiation. (11) Studies in human subjects have been very few but suggest that AChEIs may confer protection against fractures, accelerate bone healing, and reduce both fracture complications and all-cause mortality post-hip fracture. (12)(13)(14) Concerns about small sample sizes and risk of bias have limited the application and generalizability of these initial studies.…”

Rps27a might act as a controller of microglia activation in triggering neurodegenerative diseases

“…Previous studies reported that the oncostatin M receptor signaling pathway, which is associated with NDDs [ 44 , 45 ], stimulates osteoclast differentiation [ 46 , 47 ]. On the other hand, Sato and colleagues pointed out donepezil, a typical drug for Alzheimer’s disease [ 48 ], inhibits osteoclast differentiation by down regulating acetyl cholinesterase [ 49 ]. In addition, ROS are involved in Alzheimer’s disease as well as the osteoclasts differentiation pathway.…”