title: Interleukin-13 inhibits cell proliferation and stimulates interleukin-6 formation in isolated human osteoblasts.
abstract: Interleukin-13 (IL-13) is a recently identified cytokine that is secreted by activated T cells and regulates inflammatory responses. We have investigated the effects of IL-13 on isolated human osteoblast-like cells (hOB). IL-13 dose-dependently (1-100 pmol/L) reduced the incorporation rate of [3H]thymidine in hOB cells by more than 50%. Using a cell metabolic assay as well as direct cell counting, we found that treatment with IL-13 lead to a decrease in hOB cell number. The effect was both time and dose dependent, and after 12 days of culture, treatment with IL-13 (0.1 nmol/L) caused a 70% decrease in the number of cells. Also, IL-13 increased the levels of IL-6 messenger ribonucleic acid in hOBs, as measured by ribonuclease protection assay, and stimulated secretion of IL-6 into culture supernatants. In conclusion, IL-13 inhibits cell proliferation and increases IL-6 formation in human osteoblasts. Our findings suggest that IL-13 may cause bone loss due to impaired osteoblastic growth and IL-6-induced osteoclast recruitment.
authors.affiliation: Department of Orthopedic Surgery, University of Uppsala, Sweden. anders.frost@ortopedi.uu.se
authors.forename: A
authors.initials: A
authors.lastname: Frost
authors.forename: K B
authors.initials: KB
authors.lastname: Jonsson
authors.forename: H
authors.initials: H
authors.lastname: Brändström
authors.forename: C
authors.initials: C
authors.lastname: Ohlsson
authors.forename: S
authors.initials: S
authors.lastname: Ljunghall
authors.forename: O
authors.initials: O
authors.lastname: Ljunggren
mesh_terms: D002455:Cell Division; D004247:DNA / Q000096:biosynthesis; D006801:Humans; D018793:Interleukin-13 / Q000494:pharmacology*; D015850:Interleukin-6 / Q000096:biosynthesis* / Q000235:genetics / Q000378:metabolism; D007700:Kinetics; D010006:Osteoblasts / Q000166:cytology* / Q000378:metabolism*; D012516:Osteosarcoma; D012333:RNA, Messenger / Q000378:metabolism; D014407:Tumor Cells, Cultured
chemical_list: D018793:Interleukin-13; D015850:Interleukin-6; D012333:RNA, Messenger; D004247:DNA