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Inflammatory mediators modulate thrombin and cathepsin-G signaling in human bronchial fibroblasts by inducing expression of proteinase-activated receptor-4

Ramachandran, Rithwik; Yu Pei, X; Sadofsky, Laura; Morice, Alyn H.; Xiao, Yupei; Botham, Andrew; Cowen, Michael; Morice, Alyn; Sadofsky, Laura R.; Compton, Steven J; Compton, Steven J.


Rithwik Ramachandran

X Yu Pei

Dr Laura Sadofsky
Lecturer in Respiratory Medicine/ Academic lead for postgraduate training in HYMS

Alyn H. Morice

Yupei Xiao

Andrew Botham

Michael Cowen

Laura R. Sadofsky

Steven J Compton

Steven J. Compton


Human lung fibroblasts express proteinase-activated receptor-1 (PAR 1 ), PAR 2 and PAR 3 , but not PAR 4 . Because PAR 2 has inflammatory effects on human primary bronchial fibroblasts (HPBF), we asked 1) whether the inflammatory mediators TNF-α and LPS could modify HPBF PAR expression and 2) whether modified PAR expression altered HPBF responsiveness to PAR agonists in terms of calcium signaling and cell growth. TNF-α and LPS induced PAR 4 mRNA expression (RT-PCR) at 6 h and 24 h, respectively. TNF-α and LPS also upregulated PAR 2 mRNA expression with similar kinetics but had negligible effect on PAR 1 and PAR 3 . Flow cytometry for PAR 1 , PAR 2 , and PAR 3 also demonstrated selective PAR 2 upregulation in response to TNF-α and LPS. Intracellular calcium signaling to SLIGKV-NH2 (a selective PAR 2 -activating peptide; PAR 2 -AP) and AYPGQV-NH 2 (PAR 4 -AP) revealed that TNF-α and LPS induced maximal responses to these PAR agonists at 24 h and 48 h, respectively. Upregulation of PAR 2 by TNF-α heightened HPBF responses to trypsin, while PAR 4 induction enabled cathepsin-G-mediated calcium signaling. Cathepsin-G also disarmed PAR 1 and PAR 2 in HPBF, while tryptase disarmed PAR 2 . Induction of PAR 4 also enabled thrombin to elicit a calcium signal through both PAR 1 and PAR 4 , as determined by a desensitization assay. In cell growth assays the PAR 4 agonists cathepsin-G and AYPGQV-NH 2 reduced HPBF cell number only in TNF-α-treated HPBF. Moreover, the mitogenic effect of thrombin (a PAR 1 /PAR 4 agonist) but not the PAR 1 -AP TFLLR-NH 2 , was ablated in TNF-α-treated HPBF. These findings point to an important mechanism, whereby cellular responses to thrombin and cathepsin-G can be modified during an inflammatory response. Copyright © 2007 the American Physiological Society.


Ramachandran, R., Sadofsky, L., Xiao, Y., Botham, A., Cowen, M., Morice, A., & Compton, S. J. (2007). Inflammatory mediators modulate thrombin and cathepsin-G signaling in human bronchial fibroblasts by inducing expression of proteinase-activated receptor-4. American journal of physiology. Lung cellular and molecular physiology, 292(3), L788-L798.

Journal Article Type Article
Acceptance Date Nov 28, 2006
Online Publication Date Mar 1, 2007
Publication Date 2007-03
Print ISSN 1040-0605
Electronic ISSN 1522-1504
Publisher American Physiological Society
Peer Reviewed Peer Reviewed
Volume 292
Issue 3
Pages L788-L798
Keywords Inflammation; Fibrosis; Lung; Trypsin
Public URL