Calciﬁed Tissue International
C-X-C Motif Chemokine 12 Enhances Lipopolysaccharide-Induced
Osteoclastogenesis and Bone Resorption In Vivo
· Keisuke Kimura
· Masahiko Ishida
· Akiko Kishikawa
· Saika Ogawa
· Jiawei Qi
· Fumitoshi Ohori
· Takahiro Noguchi
· Aseel Marahleh
· Hideki Kitaura
Received: 26 March 2018 / Accepted: 24 May 2018
© Springer Science+Business Media, LLC, part of Springer Nature 2018
C-X-C motif chemokine 12 (CXCL12) belongs to the family of CXC chemokines. Lipopolysaccharide (LPS) induces inﬂam-
mation-induced osteoclastogenesis and bone resorption, and in recent years, stimulatory eﬀects of CXCL12 on bone resorp-
tion have also been reported. In the present study, we investigated the eﬀects of CXCL12 on LPS-induced osteoclastogenesis
and bone resorption. LPS was administered with or without CXCL12 onto mouse calvariae by daily subcutaneous injection.
Numbers of osteoclasts and bone resorption were signiﬁcantly elevated in mice co-administered LPS and CXCL12 compared
with mice administered LPS alone. Moreover, receptor activator of NF-kB ligand (RANKL) and tumor necrosis factor-α
(TNF-α) mRNA levels were higher in mice co-administered LPS and CXCL12 compared with mice administered LPS alone.
These in vitro results conﬁrmed a direct stimulatory eﬀect of CXCL12 on RANKL- and TNF-α-induced osteoclastogenesis.
Furthermore, TNF-α and RANKL mRNA levels were elevated in macrophages and osteoblasts, respectively, co-treated
in vitro with CXCL12 and LPS, in comparison with cells treated with LPS alone. Our results suggest that CXCL12 enhances
LPS-induced osteoclastogenesis and bone resorption in vivo through a combination of increasing LPS-induced TNF-α
production by macrophages, increasing RANKL production by osteoblasts, and direct enhancement of osteoclastogenesis.
Keywords Osteoclast · CXCL12 · LPS · Mouse
Osteoclasts play important physiological roles in bone
remodeling and play a pathological role in bone destruc-
tion, including in inﬂammatory osteolytic conditions such
as rheumatoid arthritis (RA) and periodontal disease .
Receptor activator of NF-kB ligand (RANKL) and mac-
rophage colony stimulating factor (M-CSF) are two impor-
tant cytokines required for osteoclastogenesis and osteoclast
function . Tumor necrosis factor (TNF)-α has also been
demonstrated to induce osteoclastogenesis both in vitro
[3–5] and in vivo [6, 7] independent of RANKL, although
there have been concerns regarding the in vivo relevance
of TNF-α since it cannot induce osteoclast formation in
RANK-deﬁcient mice .
Lipopolysaccharide (LPS) has been reported to induce
inﬂammation and pathological bone destruction [9, 10].
LPS also induces production of proinﬂammatory cytokines,
such as TNF-α, from macrophages and other cells at sites of
inﬂammation [11, 12]. These cytokines have been reported
to be involved in LPS-induced osteoclast formation and bone
resorption in in vivo and in vitro studies [9, 13]. In addition,
LPS stimulates osteoblasts to produce and express RANKL
Recently, chemokines have been reported to play impor-
tant roles in osteoclast formation and function [15–17].
C-X-C motif chemokine 12 (CXCL12), also known as
stromal cell-derived factor 1 (SDF1), belongs to the fam-
ily of CXC chemokines. CXCL12 is expressed mainly in
bone marrow but also in several other tissues including the
thymus, spleen, brain, lungs, liver, and kidneys [18, 19]. It
is well known that CXCL12 has strong chemotactic eﬀects
on lymphocytes [20, 21]. The presence of CXCL12 has
been associated with osteoclast progenitor cell survival,
* Hideki Kitaura
Division of Orthodontics and Dentofacial Orthopedics,
Department of Translational Medicine, Tohoku University
Graduate School of Dentistry, 4-1 Seiryo-machi, Aoba-ku,
Sendai 980-8575, Japan