INTERLEUKIN-1 AND BONE METABOLISM - A REVIEW

THIS REVIEW DISCUSSES the effects of interleukin-1 (IL-1) on bone meta bolism and the evidence implicating IL-1 in periodontal disease. IL-1 is a potent cytokine with significant effects on the metabolism of man y tissues, including bone. Several in vitro and in vivo studies have e stablished the potent bone-resorbing effect of IL-1. Studies have indi cated that IL-1 inhibits bone formation, although it can stimulate for mation under certain conditions. Osteoblastic cells are the bone cells expressing IL-1 receptors and responding to IL-1. IL-1 effects on ost eoblastic cells include stimulation of prostaglandin formation and mod ulation of gene expression of several proteins (cytokines, enzymes, en zyme inhibitors, matrix proteins, etc.) Osteoblastic cells also produc e IL-1, suggesting an autocrine/paracrine function of IL-1 in bone. IL -1 has been shown to interact with other osteotropic factors, both sys temic and local. These interactions modulate the effects of IL-1 on bo ne. The IL-1 effects on bone metabolism, along with other observations , suggest that IL-1 may be involved in the pathogenesis of bone diseas es. Evidence from in vivo and in vitro studies suggests that IL-1 is a n important factor in periodontal tissue breakdown. The ability of per iodontopathic bacteria to stimulate IL-1 production, the detection of elevated IL-1 levels in periodontally-diseased tissues, and the effect s of IL-1 on cells of the periodontium provide a plausible sequence of events in the pathogenesis of periodontal disease. Finally, therapeut ic modalities aimed to control the actions of IL-1 are also discussed.