No abstract

Obesity induces a low-grade systemic chronic inflammatory condition for which macrophages are responsible. We hypothesized that obesity affects osteoclastogenesis by acting on bone marrow-derived macrophages (BMM). Male mice were fed a high-fat diet (45% of energy) or a standard diet (10% of energy) for 13 wk. We found that the density of the femurs of obese mice was significantly lower than that of the femurs of lean mice. Osteoclastogenesis was enhanced in the BMM from obese mice. Lower levels of interleukin (IL)-10 were generated by the BMM from obese mice than by those from lean mice upon stimulation of receptor activator of nuclear factor-kappaB ligand. Neutralization of IL-10 in the BMM from obese mice was not as effective in increasing osteoclast (OC) formation as that in those from lean mice. Exogenous IL-10 inhibited OC formation more strongly in the BMM from obese mice than those from lean mice. The elevated level of OC formation in the BMM from obese mice may thus be due to in part to the lower level of IL-10, a negative regulator of osteoclastogenesis. Our results suggest that obesity is associated with bone loss via enhanced osteoclastogenesis due to reduced IL-10 production by the BMM from obese mice.

The oral administration of extracts of young radishes cultivated with sulfur after intravenous tumor cell injection achieved a marked reduction of pulmonary colonization in mice. Treatment of the mice with extracts of young radish cultivated with sulfur did not show any increase in the number of CD8+ or NK T cells in the spleen, indicating no influence on host immunity. Sulforaphane, which could be a candidate for an active compound from young radishes cultivated with sulfur, inhibited cell growth of B16-F10 melanoma cells. In addition, extracts of the young radish cultivated with sulfur-fed group showed enhanced quinine reductase (QR) activities in the liver and lung and a slight increase of glutathione S-transferase (GST) activity in the liver. These results suggested that the administration of extracts of young radishes cultivated with sulfur suppressed pulmonary tumorigenesis, possibly due to increased activity of detoxification enzymes in the liver and lung, and partly due to cell cytotoxicity.