Autocrine regulation of osteoclast formation and bone resorption by IL-1 alpha and TNF alpha.
Bone resorption is regulated by the cytokines within marrow cells that mediate osteoclast formation and activation. IL-1 and TNF induce bone resorption by stimulating the production of osteoclast-like multinucleated cells and by increasing the bone-resorbing activity of formed osteoclasts. This study was designed to detect IL-1 and TNF in osteoclasts in vitro and to determine whether these cytokines up-regulate osteoclast differentiation and bone resorption. The production of IL-1 alpha, -beta, and TNF alpha, beta in osteoclasts was examined immunohistochemically and by in situ hybridization. In the co-culture of C57BL/6N mouse bone marrow and MC3T3-G2/PA6 cells, a colony of osteoclasts formed, and IL-1 alpha and TNF alpha were detected. However, IL-1 beta and TNF beta were not detected. To investigate the role of IL-1 alpha and TNF alpha from osteoclasts, we enumerated TRAP-positive cells and measured the resorption pit areas in the presence of antibodies against IL-1 alpha and TNF alpha. The addition of antibodies against IL-1 alpha and TNF alpha to the co-culture system decreased the number of TRAP-positive colonies at seven days after incubation (anti-IL-1 alpha, 25.0 +/- 2.3%; anti-TNF alpha, 41.7 +/- 3.7%; anti-IL-1 alpha + anti-TNF alpha, 40.5 +/- 1.3%; and control, 100%), and the ratio of mononuclear to multinuclear cells had changed (anti-IL-1 alpha, 90:10; anti-TNF alpha, 75:25; anti-IL-1 alpha+ anti-TNF alpha, 88:12; and control, 60:40). The total pit areas per dentin slice also decreased with the addition of antibodies (anti-IL-1 alpha, 28,828; anti-TNF alpha, 49,249; anti-IL-1 alpha + anti-TNF alpha, 30,685; and control, 303,139 mm2). These results suggest that local production of IL-1 alpha and TNF alpha by osteoclasts is an important mechanism for regulating the osteoclast differentiation and bone resorptive process.
Tani-Ishii
N
N
Department of Operative Dentistry and Endodontics, Kanagawa Dental College, Yokosuka, Japan.
Tsunoda
A
A
Teranaka
T
T
Umemoto
T
T
D000135:Acid Phosphatase / Q000378:metabolism; D000818:Animals; D015415:Biomarkers; D001854:Bone Marrow Cells / Q000166:cytology / Q000502:physiology; D001862:Bone Resorption / Q000473:pathology / Q000503:physiopathology*; D002454:Cell Differentiation / Q000502:physiology; D002460:Cell Line; D002478:Cells, Cultured; D018920:Coculture Techniques; D005260:Female; D007150:Immunohistochemistry; D017403:In Situ Hybridization / Q000379:methods; D007375:Interleukin-1 / Q000502:physiology*; D007527:Isoenzymes / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D010010:Osteoclasts / Q000166:cytology / Q000502:physiology*; D000071681:Tartrate-Resistant Acid Phosphatase; D014409:Tumor Necrosis Factor-alpha / Q000502:physiology*; D015854:Up-Regulation / Q000502:physiology
D015415:Biomarkers; D007375:Interleukin-1; D007527:Isoenzymes; D014409:Tumor Necrosis Factor-alpha; D000135:Acid Phosphatase; C000605511:Acp5 protein, mouse; D000071681:Tartrate-Resistant Acid Phosphatase