title: Cell density-dependent stimulation of PAI-1 and hyaluronan synthesis by TGF-β in orbital fibroblasts.
abstract: During the course of Graves' orbitopathy (GO), orbital fibroblasts are exposed to factors that lead to proliferation and extracellular matrix (ECM) overproduction. Increased levels of tissue plasminogen activator inhibitor type 1 (PAI-1 (SERPINE1)) might promote the accumulation of ECM components. PAI-1 expression is regulated by cell density and various cytokines and growth factors including transforming growth factorβ(TGF-β). We examined the effects of increasing cell densities and TGF-β on orbital fibroblasts obtained from GO patients and controls. Responses were evaluated by the measurement of proliferation, PAI-1 expression, and ECM production. There was an inverse correlation between cell density and the per cell production of PAI-1. GO orbital, normal orbital, and dermal fibroblasts behaved similarly in this respect. Proliferation rate also declined with increasing cell densities. Hyaluronan (HA) production was constant throughout the cell densities tested in all cell lines. In both GO and normal orbital fibroblasts, but not in dermal fibroblasts, TGF-β stimulated PAI-1 production in a cell density-dependent manner, reaching up to a five-fold increase above baseline. This has been accompanied by increased HA secretion and pericellular HA levels at high cell densities. Increasing cell density is a negative regulator of proliferation and PAI-1 secretion both in normal and GO orbital fibroblasts; these negative regulatory effects are partially reversed in the presence of TGF-β. Cell density-dependent regulation of PAI-1 expression in the orbit, together with the local cytokine environment, may have a regulatory role in the turnover of the orbital ECM and may contribute to the expansion of orbital soft tissue in GO.
authors.affiliation: Division of EndocrinologyDepartment of Internal Medicine, Faculty of Medicine, University of Debrecen, Debrecen, Hungary.
authors.forename: Erika
authors.initials: E
authors.lastname: Galgoczi
authors.affiliation: Division of EndocrinologyDepartment of Internal Medicine, Faculty of Medicine, University of Debrecen, Debrecen, Hungary.
authors.forename: Florence
authors.initials: F
authors.lastname: Jeney
authors.affiliation: Division of EndocrinologyDepartment of Internal Medicine, Faculty of Medicine, University of Debrecen, Debrecen, Hungary.
authors.forename: Annamaria
authors.initials: A
authors.lastname: Gazdag
authors.affiliation: Division of EndocrinologyDepartment of Internal Medicine, Faculty of Medicine, University of Debrecen, Debrecen, Hungary.
authors.forename: Annamaria
authors.initials: A
authors.lastname: Erdei
authors.affiliation: Division of EndocrinologyDepartment of Internal Medicine, Faculty of Medicine, University of Debrecen, Debrecen, Hungary.
authors.forename: Monika
authors.initials: M
authors.lastname: Katko
authors.affiliation: Division of EndocrinologyDepartment of Internal Medicine, Faculty of Medicine, University of Debrecen, Debrecen, Hungary.
authors.forename: Domonkos M
authors.initials: DM
authors.lastname: Nagy
authors.affiliation: Department of OphthalmologyFaculty of Medicine, University of Debrecen, Debrecen, Hungary.
authors.forename: Bernadett
authors.initials: B
authors.lastname: Ujhelyi
authors.affiliation: Department of OphthalmologyFaculty of Medicine, University of Debrecen, Debrecen, Hungary.
authors.forename: Zita
authors.initials: Z
authors.lastname: Steiber
authors.affiliation: Department of SurgeryFaculty of Medicine, University of Debrecen, Debrecen, Hungary.
authors.forename: Ferenc
authors.initials: F
authors.lastname: Gyory
authors.affiliation: Division of EndocrinologyDepartment of Internal Medicine, Faculty of Medicine, University of Debrecen, Debrecen, Hungary.
authors.forename: Eszter
authors.initials: E
authors.lastname: Berta
authors.affiliation: Division of EndocrinologyDepartment of Internal Medicine, Faculty of Medicine, University of Debrecen, Debrecen, Hungary nagy@internal.med.unideb.hu.
authors.forename: Endre V
authors.initials: EV
authors.lastname: Nagy
mesh_terms: D002452:Cell Count; D049109:Cell Proliferation; D002478:Cells, Cultured; D005347:Fibroblasts / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D049970:Graves Ophthalmopathy / Q000235:genetics / Q000378:metabolism* / Q000473:pathology*; D006801:Humans; D006820:Hyaluronic Acid / Q000096:biosynthesis*; D009915:Orbit / Q000276:immunology / Q000378:metabolism* / Q000473:pathology*; D017395:Plasminogen Activator Inhibitor 1 / Q000096:biosynthesis* / Q000235:genetics; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D011994:Recombinant Proteins / Q000494:pharmacology; D053773:Transforming Growth Factor beta1 / Q000378:metabolism* / Q000494:pharmacology
chemical_list: D017395:Plasminogen Activator Inhibitor 1; D012333:RNA, Messenger; D011994:Recombinant Proteins; C051321:SERPINE1 protein, human; C508960:TGFB1 protein, human; D053773:Transforming Growth Factor beta1; D006820:Hyaluronic Acid
keywords: Graves’ orbitopathy; PAI-1; TGF-β; cell density; hyaluronan; orbital fibroblasts