Figure 6.

LPS upregulates the CCL19- and CCL21-induced osteoclast migration and bone resorption activity. (a) BMMs were pretreated with LPS (5 ng ml⁻¹) or control vehicle for 12 h and seeded in the upper chambers of transwell plates. CCL19 (10 ng ml⁻¹) or CCL21 (10 ng ml⁻¹) was added to the lower chambers. After 16 h, the cells were fixed and stained with crystal violet. The migrated cells were counted. (b) BMMs were seeded on calcium phosphate-coated plates and cultured with M-CSF (30 ng ml⁻¹) and RANKL (100 ng ml⁻¹) for 4 days. The cells were pretreated with LPS (5 ng ml⁻¹) or vehicle. After 1 day, the cells were treated with CCL19 (10 ng ml⁻¹) or CCL21 (10 ng ml⁻¹). After 2 days, calcium phosphate was stained with von Kossa reagents, and the resorbed area was quantified. (c) BMMs were placed on cover glasses and cultured with M-CSF (30 ng ml⁻¹) and RANKL (100 ng ml⁻¹) for 4 days. The cells were treated with CCL19 (10 ng ml⁻¹) or CCL21 (10 ng ml⁻¹) after 1 day of pretreatment with LPS (5 ng ml⁻¹) or control vehicle. At day 6 of the culture, the cells were fixed and incubated with rhodamine phalloidin. The actin ring density was quantified by confocal microscopy. BMM, bone marrow-derived macrophages; LPS, lipopolysaccharide.