Role of cytokines in bone resorption

Abstract

Osteoclastic bone resorption is modulated in humans by powerful osteotropic factors which are generated in the immediate vicinity of bone resorbing surfaces. These factors are released from marrow mononuclear cells and from some bone cells, and some are actually incorporated into the noncollagenous bone matrix from where they are released when bone i s resorbed. They are likely important not only in the control of normal bone remodeling, but also in a number of disease states associated with disordered remodeling. In this review, current concepts of the effects of these factors on cells in the osteoclast lineage will be discussed. v 1993 WiIey-Liss, Inc. Key words: osteoclasts, bone resorption, cytokines, srcIn the last 20 years, it has become apparent that the process of bone resorption is regulated not only by systemic hormones such as parathyroid hormone and 1,25 dihydroxyvitamin D, but in addition by a large number of powerful osteotropic factors which are generated locally in the bone cell microenvironment. These factors probably have more important effects on osteoclast function than do the systemic hormones, whose major role is the control of extracellular fluid calcium homeostasis. Bone resorption is the process by which small packets of bone throughout the skeleton are removed by osteoclastic resorption to be later replaced by osteoblastic bone formation. Since the resorption of bone occurs in discrete packets which are geographically and chronologically separate one from another, it has always appeared likely that the primary control of this process is mediated by local factors generated in the microenvironment of each bone remodeling packet.The first observation that cytokines may stimulate osteoclastic bone resorption was made over 20 years ago, when it was demonstrated that peripheral blood leukocytes activated by antigens to which they had previously been exposed or by phytohemagglutinin released a factor into their cell culture media which stimu- lated osteoclasts to resorb bone in organ cultures of fetal rat long bones [1,21. This lymphokine, as it was thought to be at the time, was termed osteoclast activating factor, or OAF. Since that time, it has become recognized that OAF is comprised of a number of discrete peptides, some of which stimulate osteoclastic bone resorption and some of which inhibit osteoclastic bone resorption. It has also become apparent that the factors which comprise this activity may be important in the bone loss which occurs in a number of pathologic states, and particularly chronic inflammatory diseases which cause bone loss, certain neoplasms associated with bone resorption, in osteopetrosis where failure of production of cytokines is likely important, and, most importantly, in the bone loss associated with the postmenopausal state and aging, namely osteoporosis.The cytokines which are involved in osteoclastic bone resorption are produced by marrow mononuclear cells and by bone cells, and some may be even incorporated into the nonmineralized bone matrix and relea...

Lipopolysaccharide-stimulated osteoclastogenesis is mediated by tumor necrosis factor via its P55 receptor.

“…Furthermore, its recruitment is influenced by macrophage-produced proinflammatory cytokines such as TNF, interleukin-1 and -6, and GM-CSF, as well as prostaglandins of the E series (24)(25)(26)(27)(28)(29). Thus, mononuclear phagocytes serve as both osteoclast precursors and paracrine promoters of the osteoclast phenotype.…”

Tumor Necrosis Factor-α (TNF) Stimulates RANKL-induced Osteoclastogenesis via Coupling of TNF Type 1 Receptor and RANK Signaling Pathways

“…others have documented a primary role for TNF in stimulating osteoclastogenesis in vitro and in vivo (21,22,33,34). The recent discovery of RANK signaling pathway in osteoclasts and their precursors enables us to investigate the direct effect, if any, of pro-and anti-inflammatory factors on RANK-induced osteoclastogenesis.…”

Post-Extraction Remodeling of the Adult Mandible

“…However, confusion has arisen in connection with the terminology of the bone surrounding the teeth. The alveolar bone proper (the very thin cribriform plate which immediately abuts the periodontal ligament and gives rise to the radiographic appearance of the lamina dura), Atwood, 1979;Ferguson, 1991 Applegate, 1958;Sobolik, 1960, Ortman, 1962Winter et al, 1974Bergman et al, 1971Harrison, 1972 Harrison, 1972 Harrison, 1972 de Van, 1935;Winter et al, 1974Wright, 1994Watt and MacGregor, 1986Klemetti et al, 1994dTallgren, 1972Lafontant, 1979 Atwood, 1963;Persson, 1967 Atwood, 1963 de Van, 1935;Baxter, 1987 Landini, 1991 Tonna, 1976;Atwood, 1979 Atwood, 1979 Ortman, 1962 Watt and MacGregor, 1986 Sobolik, 1960 Humble, 1936;Sobolik, 1960 Atwood, 1979 Pudwill andWentz, 1975;Penhall, 1980Atwood, 1979Mundy, 1993;Klemetti, 1996Penhall, 1980Bergman et al, 1971Harrison, 1972 Henrikson and Wallenius, 1974;Ortman et al, 1989;Mohajery and Brooks, 1992;Kollerup, 1992 Ortman, 1962;Atwood, 1979;Kribbs, 1992;Hsieh et al, 1995;<...>…”