Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 6/1/2005
Publication Date: 12/15/2005
Citation: Nielsen, F.H. 2005. Effect of dietary silicon on bone turnover and the inflammatory response may be through an immune response involving osteopontin [abstract]. Journal of Dairy Science. 83(Suppl. 1):333.
Technical Abstract: Physiological concentrations of silicon (Si) have been shown to affect cellular immune function in cultured lymphocytes. Thus, experiments were performed with rats to determine whether (Si) deprivation influences bone turnover and the inflammatory response by altering circulating cytokines and blood cells involved in immune function. Osteopontin received particular attention because rats deficient in this cytokine are protected from ovariectomy-induced bone loss, show abnormal wound repair, and accumulate fewer inflammatory cells after injection of collagen. Plasma osteopontin was higher in (Si)-supplemented (35 mg/kg diet as either arginine silicate inositol or metasilcate) than (Si)-deprived (about 2 mg/kg diet) rats, which may explain why (Si)-supplemented animals show greater ovariectomy-induced changes in bone turnover indices including increased deoxypyridinoline excretion. In collagen-induced inflammation, the number of neutrophils was higher and number of lymphocytes was lower in (Si)-supplemented than (Si)-deprived rats. The change in immune cell numbers may have been the result of altered recruitment and inflammatory cell accumulation (for which osteopontin is critical) in swollen joints induced by the collagen injection. The (Si)-supplemented rats also excreted increased amounts of deoxypyridinoline in urine. The findings suggest that (Si) has an in vivo physiological role that affects the expression or function of the pivotal cytokine osteopontin involved in cellular immune response and bone turnover. (Supported in part by Nutrition 21, Inc., Purchase, NY)