IL-1ß differently stimulates proliferation and multinucleation of distinct mouse bone marrow osteoclast precursor subsets.

ABSTRACT

Osteoclasts are bone-resorbing cells and targets for treating bone diseases. Previously, we reported that distinct murine osteoclast precursor subsets, such as early blasts (CD31(hi) Ly-6C(-)), myeloid blasts (CD31(+) Ly-6C(+)), and monocytes (CD31(-) Ly-6C(hi)), respond differently to the osteoclastogenesis-inducing cytokines, macrophage colony-stimulating factor, and receptor activator for nuclear factor κB ligand. It is unknown, however, how these cell types respond to the osteoclast-stimulating inflammatory cytokine interleukin 1ß. This study aims to investigate the effect of interleukin 1ß on osteoclastogenesis derived from different mouse bone marrow precursors. Early blasts, myeloid blasts, and monocytes were sorted from mouse bone marrow cells using flow cytometry. Cells were cultured on plastic or on bone slices in the presence of macrophage colony-stimulating factor and receptor activator for nuclear factor κB ligand, without or with interleukin 1ß (0.1-10 ng/ml). We found that interleukin 1ß stimulated multinucleation and bone resorption of osteoclasts derived from the 3 precursors at different rates. The most large osteoclasts (>20 nuclei) and highest level of bone resorption (16.3%) was by myeloid blast-derived osteoclasts. Interleukin 1ß particularly accelerated proliferation of early blasts and the most small osteoclasts (3-5 nuclei) formed on plastic. Life span varied among osteoclasts derived from different precursors large osteoclasts (>2400 µm(2)) formed most rapidly (75 h) from myeloid blasts but had a short life span (30 h). Monocytes needed the longest time (95 h) for the generation of such large osteoclasts, but these cells had a longer life span (50 h). Our results indicate that the different bone marrow osteoclast precursors are differently stimulated by interleukin 1ß with respect to proliferation, multinucleation, life span, and bone resorption.