IL-4, but not vitamin D3, induces monoblastic cell line UG3 to differentiate into multinucleated giant cells on osteoclast lineage

Abstract

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.

Activated macrophages for treating skin ulceration: gene expression in human monocytes after hypo-osmotic shock

“…However, the calcitonin receptor protein is usually expressed on osteoclasts, rather than monocytes/macrophages [27]. Moreover, IL‐4, as well as other cytokines such as IL‐1α, which were also found to be induced in a very significant way in our study, were associated with osteoclast formation in a monoblastic cell line [28,29]. It will be interesting, therefore, to study whether osteoclast activation can also be induced by the hypo‐osmotic shock protocol. The third group includes genes associated with neuronal development and function.…”

Feasibility of Cell Lines for In Vitro Co-Cultures Models for Bone Metabolism

“…While there are several publications that generate osteoclasts from the murine macrophage cell lines RAW264.7 [165,[174][175][176][177][178][179][180][181][182] and J774 [183][184][185][186][187], little is known about the osteoclast differentiation potential of human myeloid cell lines. There are few reports describing osteoclast features in differentiated human myeloid THP-1 cells [188], U937 [183,189], HL-60 cells [190,191], UG-3 [192], ML-2, or Mono Mac 6. Despite likely species-specific differences, the use of murine macrophage cell lines in a co-culture for bone metabolism also bares advantages.…”

“…Added osteogenic cells then have to provide a sufficient amount of CCL-2, M-CSF and RANKL to induce cell fusion and osteoclastogenesis [160,161]. Their effect may be even enhanced in the presence of IL-4 and/or vitamin D 3 [192], which is of advantage when replacing dexamethasone by cholecalciferol in the co-culture medium as suggested before [131,158]. To efficiently respond to these stimuli, the osteoclast precursor cells have to express the relevant receptors, e.g.…”