Eosinophil chemotactic factor-L (ECF-L) enhances osteoclast formation by increasing in osteoclast precursors expression of LFA-1 and ICAM-1.
ECF-L is a novel autocrine stimulator of osteoclast (OCL) formation that enhances the effects of 1,25-(OH)2D3 and RANK ligand (RANKL) and is increased in inflammatory conditions such as rheumatoid arthritis. ECF-L acts at the later stages of OCL formation and does not increase RANKL expression. Thus, its mechanism of action is unclear. Therefore, RAW 264.7 cells and M-CSF-dependent murine bone marrow macrophage (MDBM) cells were treated with RANKL and/or with recombinant ECF-L expressed as a Fc fusion protein (ECF-L-Fc) to determine their effects on NF-kappaB, AP-1 and JNK activity, and on the expression of the adhesion molecules that have been implicated in OCL formation. These parameters were measured by semiquantitative and PCR and Western blot analysis. In addition, the role of ICAM-1 was further assessed by treating normal mouse marrow cultures with ECF-L-Fc and 10(-10) M 1,25-(OH)2D3 in the presence or absence of a blocking ICAM-1 antibody or treating marrow cultures from ICAM-1 knockout mice with ECF-L and 1,25-(OH)2D3. ECF-L-Fc by itself only modestly increased NF-kappaB binding and JNK activity in RAW 264.7 cells, which was further enhanced by RANKL. In contrast, ECF-L-Fc increased LFA-1alpha and ICAM-1 mRNA levels 1.8-fold in mouse marrow cultures, and anti-ICAM-1 almost completely inhibited OCL formation induced by 10(-10) M 1,25-(OH)2D3 and ECF-L. Furthermore, ECF-L did not increase OCL formation in marrow cultures from ICAM-1 knockout mice. Taken together, these results demonstrate that ECF-L enhances RANKL and 1,25-(OH)2D3-induced OCL formation by increasing adhesive interactions between OCL precursors through increased expression of ICAM-1 and LFA-1.
Garcia-Palacios
Veronica
V
Department of Medicine, Division of Hematology-Oncology, University of Pittsburgh, Pittsburgh, PA, USA.
Chung
Ho Yeon
HY
Choi
Sun Jin
SJ
Sarmasik
Aliye
A
Kurihara
Noriyoshi
N
Lee
Jun Won
JW
Galson
Deborah L
DL
Collins
Robert
R
Roodman
G David
GD
D000818:Animals; D001853:Bone Marrow / Q000378:metabolism; D002117:Calcitriol / Q000494:pharmacology; D002454:Cell Differentiation; D002478:Cells, Cultured; D018925:Chemokines / Q000494:pharmacology / Q000502:physiology*; D002631:Chemotactic Factors, Eosinophil / Q000494:pharmacology / Q000502:physiology*; D004789:Enzyme Activation; D005786:Gene Expression Regulation; D018799:Intercellular Adhesion Molecule-1 / Q000096:biosynthesis*; D016169:Lymphocyte Function-Associated Antigen-1 / Q000096:biosynthesis*; D048670:MAP Kinase Kinase 4 / Q000502:physiology; D051379:Mice; D018345:Mice, Knockout; D016328:NF-kappa B / Q000502:physiology; D010010:Osteoclasts / Q000166:cytology / Q000378:metabolism / Q000502:physiology*; D053245:RANK Ligand / Q000494:pharmacology; D011993:Recombinant Fusion Proteins / Q000494:pharmacology; D013234:Stem Cells / Q000166:cytology / Q000378:metabolism / Q000502:physiology*; D018808:Transcription Factor AP-1 / Q000502:physiology
D018925:Chemokines; D002631:Chemotactic Factors, Eosinophil; D016169:Lymphocyte Function-Associated Antigen-1; D016328:NF-kappa B; D053245:RANK Ligand; D011993:Recombinant Fusion Proteins; D018808:Transcription Factor AP-1; C482719:eosinophil chemotactic factor-L, mouse; D018799:Intercellular Adhesion Molecule-1; D048670:MAP Kinase Kinase 4; D002117:Calcitriol