Post-menopausal osteoporosis: is it an autoimmune disease?
Recent studies have suggested a possible role of T-cells and tumor necrosis factor-alpha (TNF-alpha) in the pathogenesis of bone loss which occurs in systemic inflammatory diseases. The relevance of T-cells activity in bone loss due to estrogen deficiency has been investigated in recent years by Dr. Pacifici's group. They have shown that the increased presence of TNF-alpha producing T-cells is essential for the changes in bone metabolism during estrogen deficiency. Lack of estrogen increases interferon-y (INF-y) production by helper T-cells, which through complex class II an increased expression of major histocompatibility complex class II (MCHII) on antigen presenting cells, enhances the activation and proliferation of TNF-alpha producing T-cells. The protective role of estrogen on bone loss is mediated by type beta transforming growth factor (TGF-beta), which blocks T-cell activation and T-cell TNF-alpha production by repressing antigen presentation.
Ambrogini
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Department of Endocrinology and Metabolism, University of Pisa, Pisa Italy.
Toraldo
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Marcocci
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C
D000368:Aged; D000369:Aged, 80 and over; D000818:Animals; D001327:Autoimmune Diseases / Q000276:immunology* / Q000503:physiopathology; D001842:Bone and Bones / Q000378:metabolism; D004195:Disease Models, Animal; D004967:Estrogens / Q000172:deficiency / Q000502:physiology; D005260:Female; D000949:Histocompatibility Antigens Class II / Q000276:immunology / Q000502:physiology; D006801:Humans; D008213:Lymphocyte Activation; D008285:Major Histocompatibility Complex; D008875:Middle Aged; D015663:Osteoporosis, Postmenopausal / Q000276:immunology* / Q000503:physiopathology; D013601:T-Lymphocytes / Q000276:immunology* / Q000502:physiology; D016212:Transforming Growth Factor beta / Q000378:metabolism; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism
D004967:Estrogens; D000949:Histocompatibility Antigens Class II; D016212:Transforming Growth Factor beta; D014409:Tumor Necrosis Factor-alpha