Interleukin-6 expression and histomorphometry of bones from mice deficient in receptors for interleukin-1 or tumor necrosis factor.
We examined the roles of interleukin-1 Type I receptor (IL-1R1) and tumor necrosis factor receptor 1 (TNFR1) in bone metabolism using mice rendered deficient in these receptors by gene targeting. Sections of decalcified paraffin-embedded calvariae and humeri from 11- to 12-week-old mice deficient in IL-1 Type I receptor (IL-1R1-/-) or TNF receptor 1 (TNFR1-/-) were examined by histomorphometry. Wild-type mice (C57BL/6J x 129/J, WILD) served as controls. Interleukin-6 (IL-6) production in primary osteoblastic and bone marrow stromal cell cultures in response to parathyroid hormone (PTH, 100 ng/ml), IL-1 alpha (10 ng/ml), and TNF-alpha (10 ng/ml) was also examined. IL-1R1-/- and TNFR1-/- mice were viable and appeared phenotypically normal. However, the body weights of the IL-1R1-/- mice were 30% less than WILD, while the TNFR1-/- mice weighed 30% more than WILD mice of equivalent age. Calvariae and humeri of IL-1R1-/- and TNFR1-/- mice were normal with respect to trabecular bone volume, osteoclast number, osteoclast surface, growth plate widths, and cortical thickness. Receptor deficiency was confirmed by determining the ability of PTH, IL-1 alpha, and TNF-alpha to stimulate IL-6 in the media of primary calvaria-derived osteoblastic cell cultures from CD-1 and cytokine receptor-deficient mice. After 24 h of treatment, IL-1 alpha and TNF-alpha did not stimulate IL-6 production in osteoblasts from IL-1R1-/- and TNFR1-/- mice, respectively. In contrast, PTH increased IL-6 levels in the cells from all mice. IL-6 protein levels in bone marrow supernatants and conditioned media from untreated bone marrow stromal cells were undetectable in WILD, IL-1R1-/-, and TNFR1-/- mice. PTH, IL-1 alpha and TNF-alpha increased IL-6 mRNA and protein production in the WILD bone marrow stromal cells. In contrast, PTH and TNF-alpha increased IL-6 mRNA and protein levels in IL-1R1-/- bone marrow stromal cells while IL-1 alpha had no effect. These findings demonstrate that normal bone development in mice can occur in the absence of IL-1R1 or TNFR1 expression.
Department of Veterans Affairs Medical Center, Newington, Connecticut, USA.
S J
SJ
Vargas
A
A
Naprta
M
M
Glaccum
S K
SK
Lee
J
J
Kalinowski
J A
JA
Lorenzo
D000818:Animals; D001853:Bone Marrow / Q000378:metabolism; D001854:Bone Marrow Cells; D001842:Bone and Bones / Q000166:cytology / Q000378:metabolism*; D006811:Humerus / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D007375:Interleukin-1 / Q000494:pharmacology; D015850:Interleukin-6 / Q000096:biosynthesis*; D051379:Mice; D008815:Mice, Inbred Strains; D010006:Osteoblasts / Q000378:metabolism; D010281:Parathyroid Hormone / Q000494:pharmacology; D017472:Receptors, Interleukin-1 / Q000172:deficiency* / Q000502:physiology; D018124:Receptors, Tumor Necrosis Factor / Q000172:deficiency* / Q000502:physiology; D012886:Skull / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D017154:Stromal Cells / Q000378:metabolism; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology
D007375:Interleukin-1; D015850:Interleukin-6; D010281:Parathyroid Hormone; D017472:Receptors, Interleukin-1; D018124:Receptors, Tumor Necrosis Factor; D014409:Tumor Necrosis Factor-alpha