The study's senior author was Roberto Pacifici, MD, Herndon professor of medicine and director of the Division of Endocrinology at Emory University School of Medicine. Lead author was Emory research associate Yuhao Gao, PhD.
Previous research has shown that bone loss due to estrogen deficiency is caused by the overexpansion of immune T cells. T cells are known to produce a protein called tumor necrosis factor (TNF), which increases the formation of osteoclasts in rodents and humans. Osteoclasts are cells that help cause the absorption and removal of bone.
In research published in PNAS in August 2003, Dr. Pacifici and his colleagues demonstrated that estrogen deficiency leads to the expression of the immune regulatory protein interferon gamma (IFN-g), which in turn stimulates a protein called class II transactivator (CIITA). They found that increased expression of CIITA leads to expanded antigen presentation by macrophages (immune cells that alert T cells to the presence of invading organisms) and in turn to enhanced T cell activation in the bone marrow and extended T-cell lifespan.
The investigators' new research traces another step in the "upstream" pathway leading to estrogen's effect on bone. In order to model postmenopausal estroge
Contact: Holly Korschun
Emory University Health Sciences Center