Aryl hydrocarbon receptor–ligand axis mediates pulmonary fibroblast migration and differentiation through increased arachidonic acid metabolism

Hsiang Han Su, Hsin Ting Lin, Jau Ling Suen, Chau Chyun Sheu, Kazunari K. Yokoyama, Shau Ku Huang, Chih Mei Cheng

Research output: Contribution to journalArticle

14 Citations (Scopus)

Abstract

Pulmonary fibroblast migration and differentiation are critical events in fibrogenesis; meanwhile, fibrosis characterizes the pathology of many respiratory diseases. The role of aryl hydrocarbon receptor (AhR), a unique cellular chemical sensor, has been suggested in tissue fibrosis, but the mechanisms through which the AhR-ligand axis influences the fibrotic process remain undefined. In this study, the potential impact of the AhR-ligand axis on pulmonary fibroblast migration and differentiation was analyzed using human primary lung fibroblasts HFL-1 and CCL-202 cells. Boyden chamber-based cell migration assay showed that activated AhR in HFL-1cells significantly enhanced cell migration in response to 2, 3, 7, 8-tetrachlorodibenzo-p-dioxin (TCDD), and a known AhR antagonist, CH223191, inhibited its migratory activity. Furthermore, the calcium mobilization and subsequent upregulated expression of arachidonic acid metabolizing enzymes, including cyclooxygenase2 (COX-2) and 5-lipoxygenase (5-LOX), were observed in TCDD-treated HFL-1 cells, concomitant with elevated levels of prostaglandin E2 (PGE2) and leukotriene B4 (LTB4) secretion. Also, significantly increased expression of α-smooth muscle actin α-SMA), a fibroblast differentiation marker, was also noted in TCDD-treated HFL-1 cells (p < 0.05), resulting in a dynamic change in cytoskeleton protein levels and an increase in the nuclear translocation of the myocardin-related transcription factor. Moreover, the enhanced levels of α-SMA expression and fibroblast migration induced by TCDD, PGE2 and LTB4 were abrogated by selective inhibitors for COX-2 and 5-LOX. Knockdown of AhR by siRNA completely diminished intracellular calcium uptake and reduced α-SMA protein verified by promoter-reporter assays and chromatin immunoprecipitation. Taken together, our results suggested the importance of the AhR-ligand axis in fibroblast migration and differentiation through its capacity in enhancing arachidonic acid metabolism.

Original languageEnglish
Pages (from-to)116-126
Number of pages11
JournalToxicology
Volume370
DOIs
Publication statusPublished - Aug 31 2016
Externally publishedYes

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Keywords

  • Alpha-SMA
  • Arachidonic acid
  • Aryl hydrocarbon receptor
  • Fibrosis
  • Myocardin-related transcription factor

ASJC Scopus subject areas

  • Toxicology

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