Medical researchers at the University of Bonn, working in collaboration with scientists from Israel, the USA and Britain, have identified a previously unknown regulatory mechanism in the process of bone loss. Their findings could open up new approaches to the treatment of osteoporosis. More than four million people, predominantly women, are estimated to suffer from this distressing illness in Germany alone. In recognition of the importance of her results, Dr. Meliha Karsak from the Bonn-based Life & Brain Center has recently been awarded the Osteology Prize of the German Society for Endocrinology, which entails a cash award of 8,000 euros. Her study will now be published in the renowned "Proceedings of the National Academy of Sciences" (PNAS).

But how far can these results be applied to human beings? To answer this question, Dr. Karsak turned to a team of scientists working in France who had access to genetic samples from more than 160 female osteoporosis patients and 240 healthy women. This line of enquiry proved a complete success: "We found that a specific variant of the CB2 gene occurs more frequently among the patients than among the healthy control group," says Dr. Karsak. Individuals who carry this defect in their genetic make-up are not destined to have problems. However, as she points out, "Women with this mutation have a three-fold higher risk of osteoporosis."

The results show not only that the CB2 receptor is essential for the maintenance of a normal bone mass; they also open up completely new possibilities for therapy: "In many women with osteoporosis the CB2 receptor functions, so in their cases the disease has other causes. For them we could consider stimulating the receptor through medication and in this way slow down their bone loss." The possibility that this approach can work has been demonstrated by the experiments on mice without ovaries.

The findings hold out hope for women with a CB2 defect, too. First, it is easy to identify whether a woman is carrying the relevant mutation, so the results promise improved and faster diagnosis. Second, they have drawn attention to a previously unknown regulatory mechanism, making it a focus of osteoporosis research. Here lies the chance of developing new medicines in the long-term.

uni-bonn.de