Taiwanese research team finds new key to treating osteoporosis

2011/10/07  Taipei, Oct. 7 (CNA) A National Cheng Kung University (NCKU) research team has identified a protein that it described as a key to treating osteoporosis, a disease that lowers a person's bone density, the southern Taiwan university said Friday. Chang Ming-shi, a professor at NCKU's Department of Biochemistry and Molecular Biology, said the protein, called interleukin (IL)-20, is found in higher than normal amounts in the blood of osteoporosis patients, suggesting that IL-20 is involved in the progression of the disease. The professor described the finding as a "revolutionary discovery" because the association between IL-20 -- which is secreted by the immune system -- and osteoporosis had never been explored. According to Chang, there are two types of bone cells -- osteoclasts and osteoblasts -- and bone mineral density is determined by the balance between the two. Osteoclasts promote a decrease in bone mass and osteoblasts form bone. Osteoporosis results when osteoclasts break down bones faster than osteoblasts can rebuild them. Chang and her team found that IL-20 stimulates the formation of osteoclasts by increasing the amount of two proteins -- RANK on osteoclasts and RANKL on osteoblasts -- that are instrumental in bone metabolism and in activating osteoclasts. In a cell-based test, the team found that IL-20 completely inhibited the formation of osteoclasts from stem cells. The team then did an experiment on mice showing symptoms of osteoporosis. After the IL-20 antibody was injected into the mice, their bone mineral density increased and they were protected from the low bone density affliction. Chang said the results indicate that IL-20 is a novel target for the treatment of osteoporosis and that the IL-20 antibody could result in a potent anti-osteoporosis drug. She said there is already an anti-osteoporosis drug on the market approved by the U.S. Food and Drug Administration, called denosumab, that is an anti-RANKL antibody. But a drug based on the IL-20 antibody would go beyond that, she said. "The IL-20 antibody not only blocks the production of IL-20 but also the protein RANKL," Chang said. "If further developed into a therapeutic drug, the IL-20 antibody should have many advantages over denosumab." According to the professor, a new drug based on the discovery can be marketed in six to 10 years. The discovery was published in the Journal of Experimental Medicine, a noted international magazine in the field, in September and has drawn widespread attention in the academic community and the biotechnology industry, Chang said. The chief editor of Nature Reviews wrote a research highlight in the September issue of Nature Reviews Rheumatology commenting on the finding while the Science-Business eXchange published a cover story reporting on the discovery in the same month.