title: IL-4 suppresses osteoclast development and mature osteoclast function by a STAT6-dependent mechanism: irreversible inhibition of the differentiation program activated by RANKL.
abstract: Numerous reports have described the effects of interleukin-4 (IL-4) on bone biology. Previous studies, performed using complex coculture systems, demonstrated the effects of IL-4 on osteoblasts and osteoclasts. To directly test the effect of IL-4 on osteoclasts, we took advantage of a simplified system using recombinant receptor activator of nuclear factor kappaB ligand (RANKL) as the osteoclast differentiation factor. We analyzed the ability of IL-4 to directly regulate osteoclast differentiation and mature osteoclast function. We found that IL-4 inhibited the differentiation of osteoclasts from bone marrow precursors in an irreversible manner and also inhibited the resorptive capacity of mature osteoclasts. In the presence of IL-4, we detected the appearance of tartrate-resistant acid phosphatase (TRAP)-negative multinucleated giant (MNG) cells. Both IL-4 effects were dependent on signal transducer and activator of transcription 6 (STAT6). We found that IL-4 suppresses RANK mRNA expression in the developing precursor cells. When RANK was ectopically expressed under the cytomegalovirus (CMV) promoter in RAW264.7 macrophages, IL-4 treatment did not inhibit osteoclast development. Furthermore, when osteoclastogenesis was induced independently of RANKL by using tumor necrosis factor-alpha (TNF-alpha), IL-4 inhibited osteoclast differentiation through a STAT6-dependent mechanism. These results suggest that IL-4 regulates osteoclast development by regulating gene expression, including RANK. We propose that IL-4 irreversibly regulates the lineage commitment of precursor cells by regulating gene expression, resulting in the suppression of osteoclast development and the generation of MNG cells as an alternative pathway of differentiation.
authors.affiliation: Department of Hematopoiesis, Jerome H. Holland Laboratory for the Biomedical Sciences, American Red Cross, 15601 Crabbs Branch Way, Rockville, MD 20855, USA.
authors.forename: Jose L
authors.initials: JL
authors.lastname: Moreno
authors.forename: Michele
authors.initials: M
authors.lastname: Kaczmarek
authors.forename: Achsah D
authors.initials: AD
authors.lastname: Keegan
authors.forename: Mehrdad
authors.initials: M
authors.lastname: Tondravi
mesh_terms: D001854:Bone Marrow Cells / Q000166:cytology / Q000187:drug effects; D002352:Carrier Proteins / Q000502:physiology; D002454:Cell Differentiation / Q000187:drug effects; D019070:Cell Lineage / Q000187:drug effects; D005786:Gene Expression Regulation / Q000187:drug effects; D006023:Glycoproteins / Q000235:genetics; D006801:Humans; D015847:Interleukin-4 / Q000494:pharmacology*; D008562:Membrane Glycoproteins / Q000502:physiology; D010010:Osteoclasts / Q000166:cytology / Q000187:drug effects*; D053244:Osteoprotegerin; D053245:RANK Ligand; D012333:RNA, Messenger / Q000096:biosynthesis / Q000187:drug effects; D053246:Receptor Activator of Nuclear Factor-kappa B; D018160:Receptors, Cytoplasmic and Nuclear / Q000235:genetics; D018124:Receptors, Tumor Necrosis Factor; D050800:STAT6 Transcription Factor; D015534:Trans-Activators / Q000502:physiology*; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology
chemical_list: D002352:Carrier Proteins; D006023:Glycoproteins; D008562:Membrane Glycoproteins; D053244:Osteoprotegerin; D053245:RANK Ligand; D012333:RNA, Messenger; D053246:Receptor Activator of Nuclear Factor-kappa B; D018160:Receptors, Cytoplasmic and Nuclear; D018124:Receptors, Tumor Necrosis Factor; D050800:STAT6 Transcription Factor; C494101:STAT6 protein, human; C505686:TNFRSF11A protein, human; C506030:TNFRSF11B protein, human; C505688:TNFSF11 protein, human; D015534:Trans-Activators; D014409:Tumor Necrosis Factor-alpha; D015847:Interleukin-4