title: Interleukin-4 inhibits human smooth muscle cell proliferation.
abstract: Although proliferation of smooth muscle cells is a key event in the pathogenesis of atherosclerosis, the signals which regulate this proliferation are not fully understood. It is likely that proliferation is regulated by cytokines released by cells found in the plaque, such as T cells. In this study we report that the T cell-derived cytokine, interleukin-4 (IL-4), can inhibit proliferation of cultured human umbilical artery smooth muscle cells. Maximum inhibitory effect was achieved at IL-4 concentrations of 20 U/ml or greater. In addition, the data showed that IL-4 acted early in the G1 phase of the cell cycle, thereby preventing cells from entering S phase. The mechanism of IL-4 inhibition did not appear to involve stimulation of prostanoid synthesis since similar data were obtained when experiments were performed in the presence of a cyclooxygenase inhibitor. We propose that IL-4 may act as a protective factor released by T-cells in an atherosclerotic lesion in order to minimise the size of the plaque.
authors.affiliation: Department of Medicine, University of Melbourne, Royal Melbourne Hospital, Parkville, Victoria, Australia.
authors.forename: P K
authors.initials: PK
authors.lastname: Vadiveloo
authors.forename: H R
authors.initials: HR
authors.lastname: Stanton
authors.forename: F W
authors.initials: FW
authors.lastname: Cochran
authors.forename: J A
authors.initials: JA
authors.lastname: Hamilton
mesh_terms: D002453:Cell Cycle / Q000187:drug effects; D002455:Cell Division / Q000187:drug effects; D002478:Cells, Cultured; D004261:DNA Replication / Q000187:drug effects; D003864:Depression, Chemical; D006493:Heparin / Q000494:pharmacology; D006801:Humans; D007213:Indomethacin / Q000494:pharmacology; D015847:Interleukin-4 / Q000494:pharmacology*; D015850:Interleukin-6 / Q000494:pharmacology; D009131:Muscle, Smooth, Vascular / Q000187:drug effects*; D011994:Recombinant Proteins / Q000494:pharmacology; D016176:T-Lymphocyte Subsets / Q000502:physiology; D014469:Umbilical Arteries
chemical_list: D015850:Interleukin-6; D011994:Recombinant Proteins; D015847:Interleukin-4; D006493:Heparin; D007213:Indomethacin