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Pro‐fibrotic processes in human lung fibroblasts are driven by an autocrine/paracrine endothelinergic system
Author(s) -
Ahmedat AS,
Warnken M,
Seemann WK,
Mohr K,
Kostenis E,
Juergens UR,
Racké K
Publication year - 2013
Publication title -
british journal of pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.432
H-Index - 211
eISSN - 1476-5381
pISSN - 0007-1188
DOI - 10.1111/j.1476-5381.2012.02190.x
Subject(s) - autocrine signalling , paracrine signalling , receptor , pertussis toxin , mapk/erk pathway , biology , microbiology and biotechnology , signal transduction , endocrinology , medicine , chemistry , g protein , biochemistry
Background and Purpose Since endothelin ( ET ) may act as pro‐fibrotic mediator, expression and release of ET isoforms, their receptors and potential pro‐fibrotic ET effects were studied in human lung fibroblasts. Experimental Approach MRC ‐5 and primary human lung fibroblasts ( phLFb ) were cultured. Expression of prepro‐ ET isoforms was determined by qPCR and release of ET ‐1 by elisa . ET receptor function was analysed by real‐time measurement of dynamic mass redistribution ( DMR ). Incorporation of [ 3 H ]‐thymidine was determined as measure of proliferation and that of [ 3 H ]‐proline for collagen synthesis. Phospho‐p42/44 MAP kinase was determined by Western blot. Key Results ET ‐1 is the predominant ET in human lung fibroblasts ( hLF ), and TGF ‐β caused a further, selective and sustained up‐regulation of ET ‐1 resulting in increased extracellular ET ‐1 accumulation. hLFb express mRNA encoding ET ‐A and ET ‐ B receptors. Expression of both receptors was confirmed at protein level. ET ‐1 induced marked DMR signals, an effect that involved ET ‐A and ET ‐ B receptors. Stimulatory effects of ET ‐1 on hLFb proliferation and collagen synthesis were mediated exclusively via ET ‐A receptors. ET ‐1, again via ET ‐ A receptors, induced rapid activation of ERK MAPK , shown to be a crucial cellular signal in ET ‐1‐induced collagen synthesis. ET ‐1‐induced activation of ERK and collagen synthesis was, in contrast to corresponding effect of a muscarinic agonist, largely insensitive to pertussis toxin. Conclusions and Implications hLFb are endowed with all elements necessary to build a functional autocrine/paracrine endothelinergic system, which appears to drive pro‐fibrotic airway and lung remodelling processes, effects for which only ET ‐ A , but not ET ‐ B receptors appear to be of significance.