PPARγ ligand ciglitazone inhibits TNFα-induced ICAM-1 in human airway smooth muscle cells

Chien Da Huang, Te Chih Hsiung, Shu Chuan Ho, Kang Yun Lee, Yao Fei Chan, Li Wei Kuo, Shu Min Lin, Chun Hua Wang, Horng Chyuan Lin, Han Pin Kuo

Research output: Contribution to journalArticle

6 Citations (Scopus)

Abstract

Background: Modification of human airway smooth muscle (ASM) function by proinflammatory cytokines has been regarded as a potential mechanism underlying bronchial hyperresponsiveness in asthma. Human ASM cells express intercellular adhesion molecule (ICAM)-1 in response to cytokines. Synthetic ligands for peroxisome proliferator-activated receptor (PPAR)γ reportedly possess anti-inflammatory and immunomodulatory properties. In this study, we examined whether ciglitazone, a synthetic PPARγ ligand, can modulate the basal and tumor necrosis factor (TNF)α-induced ICAM1 gene expression in human ASM cells. Methods: Human ASM cells were treated with TNFα. ICAM-1 expression was assessed by flow cytometry and reverse transcriptase-polymerase chain reaction (RT-PCR) analysis. PPARγ activity was inhibited by target-specific small interfering (si) RNA targeting PPARγ and GW9662, a PPARγ antagonist. Activity of nuclear factor (NF)-κB was assessed by using immunoblot analysis, immune-confocal images, and electrophoretic mobility shift assay (EMSA). Results: By flow cytometry, ciglitazone alone had no effect on ICAM-1 expression in ASM cells, but inhibited ICAM-1 expression in response to TNFα (10 ng/ml) in a dose-dependent manner (1-10 μM). It also inhibited TNFα-induced ICAM1 gene expression by RT-PCR analysis. Knockdown of PPARγ gene by target-specific siRNA targeting PPARγ enhanced ICAM-1 expression and the inhibitory effect of ciglitazone on TNFα-induced ICAM-1 expression was reversed by PPARγ siRNA and GW9662. SN-50 (10 μg/ml), an inhibitor for nuclear translocation of NF-κB, inhibited TNFα-induced ICAM-1 expression. Ciglitazone did not prevent TNFα-induced degradation of the cytosolic inhibitor of NF-κB (IκB), but inhibited the nuclear translocation of p65 induced by TNFα and suppressed the NF-κB/DNA binding activity. Conclusion: These findings suggest that ciglitazone inhibits TNFα-induced ICAM1 gene expression in human ASM cells through the ligand-dependent PPARγ activation and NF-κB-dependent pathway.

Original languageEnglish
Pages (from-to)191-198
Number of pages8
JournalBiomedical Journal
Volume37
Issue number4
DOIs
Publication statusPublished - 2014

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Keywords

  • airway inflammation
  • airway smooth muscle
  • ICAM-1
  • NF-κB
  • PPARγ

ASJC Scopus subject areas

  • Medicine(all)

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