IL-6 mediates the effects of IL-1 or TNF, but not PTHrP or 1,25(OH)2D3, on osteoclast-like cell formation in normal human bone marrow cultures.
A potent interleukin-6 (IL-6) antagonist (Sant 5), which binds tightly to the IL-6alpha receptor but has impaired gp130 heterodimerization, has been developed recently by site-directed mutagenesis of human IL-6. We report here that Sant 5 inhibits IL-6-stimulated osteoclast-like multinucleated cell (MNC) formation in human marrow cultures but also inhibits the stimulatory effects of IL-1 or tumor necrosis factor alpha (TNF-alpha in these cultures. We further show that a neutralizing antibody to IL-6 also inhibits the stimulatory effects of IL-1 or TNF-alpha in these cultures. In contrast, Sant 5 had no effect on parathyroid hormone related protein (PTHrP) or 1,25-dihydroxyvitamin D3 stimulated MNC formation in human marrow cultures. Transfection of a human marrow stromal cell line, which normally induces osteoclast formation through production of IL-6, with the Sant 5 cDNA driven by a cytomegalovirus (CMV) promoter blocked the capacity of these cells to stimulate osteoclast-like cell formation. These Sant 5 transfected cells and conditioned media from these cells also inhibited the stimulatory effects of the parent cell line on MNC formation. These data suggest that IL-6 mediates the effects of IL-1 and TNF on human osteoclast formation, but in contrast to murine systems, does not mediate the effects of PTHrP. These data further demonstrate that stromal cells transfected with the Sant 5 cDNA can constitutively produce high levels of the IL-6 antagonist and inhibit osteoclast formation in vitro.
Devlin
R D
RD
Department of Medicine/Hematology, University of Texas Health Science Center, San Antonio, USA.
Reddy
S V
SV
Savino
R
R
Ciliberto
G
G
Roodman
G D
GD
D000911:Antibodies, Monoclonal; D001854:Bone Marrow Cells / Q000187:drug effects*; D002117:Calcitriol / Q000494:pharmacology*; D002478:Cells, Cultured; D018920:Coculture Techniques; D016207:Cytokines / Q000096:biosynthesis; D003587:Cytomegalovirus / Q000235:genetics; D018076:DNA, Complementary / Q000235:genetics; D015726:Giant Cells / Q000187:drug effects; D006801:Humans; D007375:Interleukin-1 / Q000494:pharmacology*; D015850:Interleukin-6 / Q000032:analysis; D010010:Osteoclasts / Q000187:drug effects*; D044162:Parathyroid Hormone-Related Protein; D011401:Promoter Regions, Genetic; D011506:Proteins / Q000494:pharmacology*; D017154:Stromal Cells / Q000187:drug effects; D014162:Transfection; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology*; D000093242:Interleukin-6 Inhibitors
D000911:Antibodies, Monoclonal; D002117:Calcitriol; D016207:Cytokines; D018076:DNA, Complementary; D007375:Interleukin-1; D015850:Interleukin-6; D044162:Parathyroid Hormone-Related Protein; D011506:Proteins; D014409:Tumor Necrosis Factor-alpha; D000093242:Interleukin-6 Inhibitors; C470121:PTHLH protein, human