IL-4, but not vitamin D(3), induces monoblastic cell line UG3 to differentiate into multinucleated giant cells on osteoclast lineage.
The formation of multinucleated giant cells (MGCs) from monocytes/macrophages is controlled by various cytokines, the roles of which are not fully understood. Both interleukin (IL)-4 and 1alpha,25(OH)(2) vitamin D(3) (D(3)) are known to induce MGC formation from monocytes/macrophages. D(3) is also known as a stimulator of osteoclast formation in the presence of stroma cells, and IL-4 as an inhibitor. Previously, we showed that IL-4-induced MGCs from monocytes/macrophages expressed tartrate resistant acid phosphatase (TRAP) activity and hydroxyapatite-resorptive activity in the presence of M-CSF without stroma cells. In this study, we examined the effects of D(3) and/or IL-4 on MGC formation and the characteristics of these MGCs using a monoblastic cell line (UG3), to elucidate the involvement of these factors in osteoclast development without stroma cells. D(3)-induced MGCs showed none of the markers of osteoclasts, such as TRAP activity, calcitonin receptor (cal-R) expression, hydroxyapatite-resorptive activity, and bone-resorptive activity. A low concentration of D(3) synergistically stimulated IL-4-induced TRAP-positive MGC formation, whereas a high concentration of D(3) inhibited it. When IL-4 was added on day 7 of the 2-week culture with D(3), TRAP positivity reached maximum. On the other hand, delayed addition of D(3) on day 7 of culture did not increase the TRAP positivity. Although the fusion rate increased during the first week of the 2-week culture in the presence of D(3), it increased further in the second week following the addition of IL-4 on day 7. Furthermore, IL-4-induced, or IL-4- and D(3)-induced MGCs differentiated into functional osteoclasts with bone-resorptive activity following coculture with osteoblastic cells, whereas D(3)-induced MGCs did not acquire bone-resorptive activity even after coculture with osteoblastic cells in the presence of D(3). These findings suggest that IL-4 initiates osteoclast development of UG3 cells, although stroma cells were necessary for development of functional osteoclasts. On the other hand, D(3) had only a "supportive" effect on this differentiation. IL-4 and direct contact with stroma cells may regulate different stages in the multistep process of osteoclastogenesis of UG3 cells.
Kaji
Y
Y
Department of Orthopedic Surgery, Kagawa Medical University, Kagawa, Japan.
Ikeda
K
K
Ikeda
T
T
Kawakami
K
K
Sasaki
K
K
Shindo
M
M
Hatake
K
K
Harada
M
M
Motoyoshi
K
K
Mori
S
S
Norimatsu
H
H
Takahara
J
J
D016475:3T3 Cells / Q000502:physiology; D000818:Animals; D002454:Cell Differentiation; D002460:Cell Line / Q000166:cytology / Q000187:drug effects; D002467:Cell Nucleus / Q000648:ultrastructure*; D002762:Cholecalciferol / Q000494:pharmacology*; D018920:Coculture Techniques; D004305:Dose-Response Relationship, Drug; D004338:Drug Combinations; D015726:Giant Cells / Q000166:cytology* / Q000648:ultrastructure; D006801:Humans; D015847:Interleukin-4 / Q000494:pharmacology*; D016173:Macrophage Colony-Stimulating Factor / Q000494:pharmacology; D051379:Mice; D010010:Osteoclasts / Q000166:cytology* / Q000187:drug effects / Q000502:physiology; D011994:Recombinant Proteins / Q000494:pharmacology; D017154:Stromal Cells / Q000502:physiology; D013997:Time Factors
D004338:Drug Combinations; D011994:Recombinant Proteins; D002762:Cholecalciferol; D015847:Interleukin-4; D016173:Macrophage Colony-Stimulating Factor