title: IFN-γ and TNF-α synergize to inhibit CTGF expression in human lung endothelial cells.
abstract: Connective tissue growth factor (CTGF/CCN2) is an angiogenetic and profibrotic factor, acting downstream of TGF-β, involved in both airway- and vascular remodeling. While the T-helper 1 (Th1) cytokine interferon-gamma (IFN-γ) is well characterized as immune-modulatory and anti-fibrotic cytokine, the role of IFN-γ in lung endothelial cells (LEC) is less defined. Tumour necrosis factor alpha (TNF-α) is another mediator that drives vascular remodeling in inflammation by influencing CTGF expression. In the present study we investigated the influence of IFN-γ and TNF-α on CTGF expression in human LEC (HPMEC-ST1.6R) and the effect of CTGF knock down on human LEC. IFN-γ and TNF-α down-regulated CTGF in human LEC at the promoter-, transcriptional- and translational-level in a dose- and time-dependent manner. The inhibitory effect of IFN-γ on CTGF-expression could be almost completely compensated by the Jak inhibitor AG-490, showing the involvement of the Jak-Stat signaling pathway. Besides the inhibitory effect of IFN-γ and TNF-α alone on CTGF expression and LEC proliferation, these cytokines had an additive inhibitory effect on proliferation as well as on CTGF expression when administered together. To study the functional role of CTGF in LEC, endogenous CTGF expression was down-regulated by a lentiviral system. CTGF silencing in LEC by transduction of CTGF shRNA reduced cell proliferation, but did not influence the anti-proliferative effect of IFN-γ and TNF-α. In conclusion, our data demonstrated that CTGF was negatively regulated by IFN-γ in LEC in a Jak/Stat signaling pathway-dependent manner. In addition, an additive effect of IFN-γ and TNF-α on inhibition of CTGF expression and cell proliferation could be found. The inverse correlation between IFN-γ and CTGF expression in LEC could mean that screwing the Th2 response to a Th1 response with an additional IFN-γ production might be beneficial to avoid airway remodeling in asthma.
authors.affiliation: Orthopedic Center for Musculoskeletal Research, Molecular Orthopedics, University of Würzburg, Würzburg, Germany.
authors.forename: Roderich
authors.initials: R
authors.lastname: Laug
authors.forename: Markus
authors.initials: M
authors.lastname: Fehrholz
authors.forename: Norbert
authors.initials: N
authors.lastname: Schütze
authors.forename: Boris W
authors.initials: BW
authors.lastname: Kramer
authors.forename: Vera
authors.initials: V
authors.lastname: Krump-Konvalinkova
authors.forename: Christian P
authors.initials: CP
authors.lastname: Speer
authors.forename: Steffen
authors.initials: S
authors.lastname: Kunzmann
mesh_terms: D015153:Blotting, Western; D002460:Cell Line; D049109:Cell Proliferation / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D055513:Connective Tissue Growth Factor / Q000235:genetics / Q000378:metabolism* / Q000494:pharmacology; D042783:Endothelial Cells / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D006801:Humans; D007371:Interferon-gamma / Q000494:pharmacology*; D008168:Lung / Q000166:cytology*; D060888:Real-Time Polymerase Chain Reaction; D011994:Recombinant Proteins / Q000494:pharmacology; D015398:Signal Transduction / Q000187:drug effects; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology*
chemical_list: D011994:Recombinant Proteins; D014409:Tumor Necrosis Factor-alpha; D055513:Connective Tissue Growth Factor; D007371:Interferon-gamma