title: Immunology of Osteoporosis: A Mini-Review.
abstract: Osteoporosis is a major cause of fractures and associated morbidity in the aged population. The pathogenesis of osteoporosis is multifactorial; whereas traditional pathophysiological concepts emphasize endocrine mechanisms, it has been recognized that also components of the immune system have a significant impact on bone. Since 2000, when the term 'osteoimmunology' was coined, novel insights into the role of inflammatory cytokines by influencing the fine-tuned balance between bone resorption and bone formation have helped to explain the occurrence of osteoporosis in conjunction with chronic inflammatory reactions. Moreover, the phenomenon of a low-grade, chronic, systemic inflammatory state associated with aging has been defined as 'inflamm-aging' by Claudio Franceschi and has been linked to age-related diseases such as osteoporosis. Given the tight anatomical and physiological coexistence of B cells and the bone-forming units in the bone marrow, a role of B cells in osteoimmunological interactions has long been suspected. Recent findings of B cells as active regulators of the RANK/RANKL/OPG axis, of altered RANKL/OPG production by B cells in HIV-associated bone loss or of a modulated expression of genes linked to B-cell biology in response to estrogen deficiency support this assumption. Furthermore, oxidative stress and the generation of advanced glycation end products have emerged as links between inflammation and bone destruction.
authors.affiliation: Department of Pathophysiology and Allergy Research, Center for Pathophysiology, Infectiology and Immunology, Medical University Vienna, Vienna, Austria.
authors.forename: Peter
authors.initials: P
authors.lastname: Pietschmann
authors.forename: Diana
authors.initials: D
authors.lastname: Mechtcheriakova
authors.forename: Anastasia
authors.initials: A
authors.lastname: Meshcheryakova
authors.forename: Ursula
authors.initials: U
authors.lastname: Föger-Samwald
authors.forename: Isabella
authors.initials: I
authors.lastname: Ellinger
mesh_terms: D001402:B-Lymphocytes / Q000276:immunology*; D003564:Cytidine Deaminase / Q000276:immunology; D017127:Glycation End Products, Advanced / Q000276:immunology; D006801:Humans; D007249:Inflammation / Q000276:immunology; D010024:Osteoporosis / Q000276:immunology*; D053244:Osteoprotegerin / Q000276:immunology*; D018384:Oxidative Stress / Q000276:immunology; D053245:RANK Ligand / Q000276:immunology*; D053246:Receptor Activator of Nuclear Factor-kappa B / Q000276:immunology*
chemical_list: D017127:Glycation End Products, Advanced; D053244:Osteoprotegerin; D053245:RANK Ligand; D053246:Receptor Activator of Nuclear Factor-kappa B; D003564:Cytidine Deaminase