August 26, 2009
Immune system plays role in bone loss
U.S. researchers say immune system-based approaches may help in treating osteoporosis.
The study, published in Clinical Immunology, links bone loss to the immune system's reaction to cholesterol-related oxidation -- cell and tissue damage from exposure to free radicals. The scientists came to their conclusion by observing human T cells exposed in the laboratory to oxidized low-density lipoprotein, the
Both the resting and the activated T cells started churning out a chemical that stimulates cells whose sole purpose is to destroy bone,study leader Rita Effros of the David Geffen School of Medicine at the University of California, Los Angeles, said in a statement.
These results were repeated in an animal study comparing mice fed a high-fat diet to those eating a standard diet. After 11 months, the mice given food high in fat not only showed elevated cholesterol and thinner bones, but their T cells switched on a gene that produced a chemical called RANKL.
It's normal for our T cells to produce small amounts of RANKL during an immune response, Effros said in a statement.
But when RANKL is manufactured for long periods or at the wrong time, it results in excessive bone damage.