Activation of the TGF-beta/activin-Smad2 pathway during allergic airway inflammation
2001 (English)In: American Journal of Respiratory Cell and Molecular Biology, ISSN 1044-1549, E-ISSN 1535-4989, Vol. 25, no 1, 60-68 p.Article in journal (Refereed) Published
Changes in the levels of transforming growth factor (TGF)-beta cytokines or receptors observed during the progression of several inflammatory and fibrotic disorders have been used to implicate these cytokines in the pathophysiology of these diseases. Although correlative, these studies were inconclusive because they were unable to demonstrate actual continuous TGF-beta-mediated signaling in the involved tissues. We reasoned that the phosphorylation state and subcellular localization of Smad2, the intracellular effector of TGF-beta/activin-mediated signaling, could be used as a marker of active signaling mediated by these cytokines in situ. We therefore used an experimental model of ovalbumin-induced allergic airway inflammation and were able to demonstrate a dramatic increase in the numbers of bronchial epithelial, alveolar, and infiltrating inflammatory cells expressing nuclear phosphorylated Smad2 within the allergen-challenged lungs. This was accompanied by strong upregulation of the activin receptor ALK-4/ActR-IB and redistribution of the TGF-beta responsive ALK-5/TbetaR-I. Although levels of TGF-beta1, TGF-beta2, and TGF-beta3 messenger RNA (mRNA) were marginally altered, the level of activin mRNA was strongly upregulated during the inflammatory response. Our data illustrate the usefulness of antiphosphorylated Smad antibodies in demonstrating active TGF- beta/activin-mediated signaling in vivo and strongly suggest that activin/Smad-mediated signaling could be a critical contributor in the pathophysiology of allergic pulmonary diseases.
Place, publisher, year, edition, pages
2001. Vol. 25, no 1, 60-68 p.
Activins, Animals, Base Sequence, Blotting; Western, Bronchitis/etiology/*metabolism, DNA Primers, DNA-Binding Proteins/*metabolism, Female, Hypersensitivity/complications/*metabolism, Immunohistochemistry, Inhibins/*metabolism, Mice, Mice; Inbred BALB C, Phosphorylation, Protein Transport, Research Support; Non-U.S. Gov't, Reverse Transcriptase Polymerase Chain Reaction, Signal Transduction, Trans-Activators/*metabolism, Transforming Growth Factor beta/*metabolism
Medical and Health Sciences
IdentifiersURN: urn:nbn:se:uu:diva-73345DOI: 10.1165/ajrcmb.25.1.4396PubMedID: 11472976OAI: oai:DiVA.org:uu-73345DiVA: diva2:101255