title: CXCL8 and CCL20 Enhance Osteoclastogenesis via Modulation of Cytokine Production by Human Primary Osteoblasts.
abstract: Generalized osteoporosis is common in patients with inflammatory diseases, possibly because of circulating inflammatory factors that affect osteoblast and osteoclast formation and activity. Serum levels of the inflammatory factors CXCL8 and CCL20 are elevated in rheumatoid arthritis, but whether these factors affect bone metabolism is unknown. We hypothesized that CXCL8 and CCL20 decrease osteoblast proliferation and differentiation, and enhance osteoblast-mediated osteoclast formation and activity. Human primary osteoblasts were cultured with or without CXCL8 (2-200 pg/ml) or CCL20 (5-500 pg/ml) for 14 days. Osteoblast proliferation and gene expression of matrix proteins and cytokines were analyzed. Osteoclast precursors were cultured with CXCL8 (200 pg/ml) and CCL20 (500 pg/ml), or with conditioned medium (CM) from CXCL8 and CCL20-treated osteoblasts with or without IL-6 inhibitor. After 3 weeks osteoclast formation and activity were determined. CXCL8 (200 pg/ml) and CCL20 (500 pg/ml) enhanced mRNA expression of KI67 (2.5-2.7-fold), ALP (1.6-1.7-fold), and IL-6 protein production (1.3-1.6-fold) by osteoblasts. CXCL8-CM enhanced the number of osteoclasts with 3-5 nuclei (1.7-fold), and with >5 nuclei (3-fold). CCL20-CM enhanced the number of osteoclasts with 3-5 nuclei (1.3-fold), and with >5 nuclei (2.8-fold). IL-6 inhibition reduced the stimulatory effect of CXCL8-CM and CCL20-CM on formation of osteoclasts. In conclusion, CXCL8 and CCL20 did not decrease osteoblast proliferation or gene expression of matrix proteins. CXCL8 and CCL20 did not directly affect osteoclastogenesis. However, CXCL8 and CCL20 enhanced osteoblast-mediated osteoclastogenesis, partly via IL-6 production, suggesting that CXCL8 and CCL20 may contribute to osteoporosis in rheumatoid arthritis by affecting bone cell communication.
authors.affiliation: Department of Oral Cell Biology, Academic Centre for Dentistry Amsterdam (ACTA), University of Amsterdam and VU University Amsterdam, MOVE Research Institute Amsterdam, Amsterdam, The Netherlands; Skeletal Biology and Engineering Research Center, KU Leuven, Leuven, Belgium.
authors.forename: Janak L
authors.initials: JL
authors.lastname: Pathak
authors.affiliation: Department of Oral Cell Biology, Academic Centre for Dentistry Amsterdam (ACTA), University of Amsterdam and VU University Amsterdam, MOVE Research Institute Amsterdam, Amsterdam, The Netherlands.
authors.forename: Astrid D
authors.initials: AD
authors.lastname: Bakker
authors.affiliation: Skeletal Biology and Engineering Research Center, KU Leuven, Leuven, Belgium.
authors.forename: Patrick
authors.initials: P
authors.lastname: Verschueren
authors.affiliation: Department of Rheumatology, VU University Medical Center, MOVE Research Institute Amsterdam, Amsterdam, The Netherlands.
authors.forename: Willem F
authors.initials: WF
authors.lastname: Lems
authors.affiliation: Skeletal Biology and Engineering Research Center, KU Leuven, Leuven, Belgium.
authors.forename: Frank P
authors.initials: FP
authors.lastname: Luyten
authors.affiliation: Department of Oral Cell Biology, Academic Centre for Dentistry Amsterdam (ACTA), University of Amsterdam and VU University Amsterdam, MOVE Research Institute Amsterdam, Amsterdam, The Netherlands.
authors.forename: Jenneke
authors.initials: J
authors.lastname: Klein-Nulend
authors.affiliation: Department of Clinical Chemistry, VU University Medical Center, MOVE Research Institute Amsterdam, Amsterdam, The Netherlands.
authors.forename: Nathalie
authors.initials: N
authors.lastname: Bravenboer
mesh_terms: D000368:Aged; D001172:Arthritis, Rheumatoid / Q000150:complications / Q000503:physiopathology*; D016723:Bone Remodeling / Q000187:drug effects; D001862:Bone Resorption / Q000503:physiopathology; D002454:Cell Differentiation / Q000187:drug effects; D002455:Cell Division / Q000187:drug effects; D002478:Cells, Cultured; D054418:Chemokine CCL20 / Q000494:pharmacology / Q000502:physiology*; D017077:Culture Media, Conditioned / Q000494:pharmacology; D016207:Cytokines / Q000378:metabolism*; D016326:Extracellular Matrix Proteins / Q000096:biosynthesis / Q000235:genetics; D005260:Female; D005786:Gene Expression Regulation / Q000187:drug effects; D006801:Humans; D015850:Interleukin-6 / Q000096:biosynthesis / Q000235:genetics; D016209:Interleukin-8 / Q000494:pharmacology / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D010006:Osteoblasts / Q000187:drug effects* / Q000378:metabolism; D010010:Osteoclasts / Q000166:cytology*; D010024:Osteoporosis / Q000209:etiology / Q000503:physiopathology; D054399:Receptors, CCR6 / Q000378:metabolism; D023062:Receptors, Interleukin-8A / Q000378:metabolism; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology; D000093242:Interleukin-6 Inhibitors
chemical_list: D054418:Chemokine CCL20; D017077:Culture Media, Conditioned; D016207:Cytokines; D016326:Extracellular Matrix Proteins; D015850:Interleukin-6; D016209:Interleukin-8; D054399:Receptors, CCR6; D023062:Receptors, Interleukin-8A; D014409:Tumor Necrosis Factor-alpha; D000093242:Interleukin-6 Inhibitors; C108355:CCL20 protein, human; C106311:CCR6 protein, human; C508606:CXCL8 protein, human; C508600:IL6 protein, human