Osteoporosis, inflammation and ageing

Osteoporosis is substantially an age-related condition characterized by low bone mass and increased bone fragility, putting the patients at risk of fractures, which are major causes of morbidity and mortality in older people. Although ageing and estrogen deficiency are probably the 2 most important risk factors, osteoporosis can occur in any age of life. There are a large number of risk factors for the development of senile osteoporosis. Osteoporosis is currently attributed to various endocrine, metabolic and mechanical factors. However, recent discoveries suggest that these risk factors could exert their effects through immunologically mediated modulation of bone remodelling. Emerging clinical and molecular evidences suggest that inflammation exerts significant influence on bone turnover, inducing osteoporosis. Currently, growing understanding of bone physiology suggests that factors involved in inflammation are linked with those critical for bone remodelling process. Numerous proinflammatory cytokines have been implicated in the regulation of osteoblasts and osteoclasts, and a shift towards an activated immune profile has been hypothesized as important risk factor. Chronic inflammation and the immune system remodelling characteristic of ageing may be determinant pathogenetic factors. Inflamm-ageing itself plays a role in bone remodelling through proinflammatory cytokines, together with other more recently discovered immunological mediators and transcription factors. Senile osteoporosis is an example of the central role of immune-mediated inflammation in determining bone resorption.