TGFβ1 induces IL-6 and inhibits IL-8 release in human bronchial epithelial cells: the role of Smad2/3.

Abstract

Human bronchial epithelial (HBE) cells contribute to asthmatic airway inflammation by secreting cytokines, chemokines, and growth factors, including interleukin (IL)-6, IL-8 and transforming growth factor (TGF) β1, all of which are elevated in asthmatic airways. This study examines the signaling pathways leading to TGFβ1 induced IL-6 and IL-8 in primary HBE cells from asthmatic and non-asthmatic volunteers. HBE cells were stimulated with TGFβ1 in the presence or absence of signaling inhibitors. IL-6 and IL-8 protein and mRNA were measured by ELISA and real-time PCR respectively, and cell signaling kinases by Western blot. TGFβ1 increased IL-6, but inhibited IL-8 production in both asthmatic and non-asthmatic cells; however, TGF induced significantly more IL-6 in asthmatic cells. Inhibition of JNK MAP kinase partially reduced TGFβ1 induced IL-6 in both cell groups. TGFβ1 induced Smad2 phosphorylation, and blockade of Smad2/3 prevented both the TGFβ1 modulated IL-6 increase and the decrease in IL-8 production in asthmatic and non-asthmatic cells. Inhibition of Smad2/3 also increased basal IL-8 release in asthmatic cells but not in non-asthmatic cells. Using CHIP assays we demonstrated that activated Smad2 bound to the IL-6, but not the IL-8 promoter region. We conclude that the Smad2/3 pathway is the predominant TGFβ1 signaling pathway in HBE cells, and this is altered in asthmatic bronchial epithelial cells. Understanding the mechanism of aberrant pro-inflammatory cytokine production in asthmatic airways will allow the development of alternative ways to control airway inflammation.

• Authors: Qi Ge, Lyn M Moir, Judith L Black, Brian G Oliver, Janette K Burgess
• Journal: Journal of cellular physiology (J Cell Physiol) Vol. 225 Issue 3 Pg. 846-54 (Nov 2010) ISSN: 1097-4652 [Electronic] United States
• PMID: 20607798 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)
• Copyright: © 2010 Wiley-Liss, Inc.

Chemical References

• CXCL8 protein, human
• IL6 protein, human
• Inflammation Mediators
• Interleukin-6
• Interleukin-8
• Protein Kinase Inhibitors
• RNA, Messenger
• SMAD2 protein, human
• SMAD3 protein, human
• Smad2 Protein
• Smad3 Protein
• Transforming Growth Factor beta1
• JNK Mitogen-Activated Protein Kinases

Topics

• Adolescent
• Adult
• Aged
• Asthma (immunology, metabolism)
• Binding Sites
• Blotting, Western
• Bronchi (drug effects, immunology, metabolism)
• Case-Control Studies
• Cells, Cultured
• Chromatin Immunoprecipitation
• Down-Regulation
• Enzyme-Linked Immunosorbent Assay
• Epithelial Cells (drug effects, immunology, metabolism)
• Female
• Humans
• Inflammation Mediators (metabolism)
• Interleukin-6 (genetics, metabolism)
• Interleukin-8 (genetics, metabolism)
• JNK Mitogen-Activated Protein Kinases (antagonists & inhibitors, metabolism)
• Male
• Middle Aged
• Phosphorylation
• Polymerase Chain Reaction
• Promoter Regions, Genetic
• Protein Kinase Inhibitors (pharmacology)
• RNA, Messenger (metabolism)
• Respiratory Mucosa (drug effects, immunology, metabolism)
• Signal Transduction
• Smad2 Protein (antagonists & inhibitors, metabolism)
• Smad3 Protein (antagonists & inhibitors, metabolism)
• Transforming Growth Factor beta1 (metabolism)
• Up-Regulation
• Young Adult