Tussilagone promotes osteoclast apoptosis and prevents estrogen deficiency-induced osteoporosis in mice

Osteoporosis is a degenerative disease characterized by reduced bone mass, in which deregulated bone remodeling by osteoclasts and osteoblasts is a main pathogenesis. Although recently tussilagone, a major active component of flower buds of Tussilago farfara, has been shown to inhibit osteoclastogenesis, its effect on estrogen deficiency-induced osteoporosis remains unknown. This study examined the effect of tussilagone on bone loss in ovariectomized mice and further explored its impact on osteoclast apoptosis and osteoblast formation in addition to osteoclastogenesis. Tussilagone suppression of osteoclastogenesis was confirmed in bone marrow derived macrophages, which was observed with the 1/10 concentration of that of the previous study. As demonstrated by ApoPercentage dye staining and Western blotting, tussilagone enhanced apoptosis in differentiated osteoclasts by increasing estrogen receptor α and Fas ligand expression. On the contrary, either osteoblast differentiation or mineralization was not affected by tussilagone. Lastly, administering tussilagone to mice for 6 weeks prevented trabecular microarchitecture impairment in ovariectomized mice compared to vehicle control groups. These findings suggest that tussilagone or Tussilago farfara prevents osteoporotic bone loss by suppressing osteoclast differentiation and inducing osteoclast apoptosis, and that it may therefore offer a possible remedy against resorptive bone diseases.