c-Jun N-terminal kinase and Akt signalling pathways regulating tumour necrosis factor-α-induced interleukin-32 expression in human lung fibroblasts: implications in airway inflammation

Immunology. 2015 Feb;144(2):282-90. doi: 10.1111/imm.12374.

Abstract

Airway inflammatory diseases such as chronic obstructive pulmonary disease (COPD) and asthma are associated with elevated expression of interleukin-32 (IL-32), a recently described cytokine that appears to play a critical role in inflammation. However, so far, the regulation of pulmonary IL-32 production has not been fully established. We examined the expression of IL-32 by tumour necrosis factor-α (TNF-α) in primary human lung fibroblasts. Human lung fibroblasts were cultured in the presence or absence of TNF-α and/or other cytokines/Toll-like receptor (TLR) ligands or various signalling molecule inhibitors to analyse the expression of IL-32 by quantitative RT-PCR and ELISA. Next, activation of Akt and c-Jun N-terminal kinase (JNK) signalling pathways was investigated by Western blot. Interleukin-32 mRNA of four spliced isoforms (α, β, γ and δ) was up-regulated upon TNF-α stimulation, which was associated with a significant IL-32 protein release from TNF-α-activated human lung fibroblasts. The combination of interferon-γ and TNF-α induced enhanced IL-32 release in human lung fibroblasts, whereas IL-4, IL-17A, IL-27 and TLR ligands did not alter IL-32 release in human lung fibroblasts either alone, or in combination with TNF-α. Furthermore, the activation of Akt and JNK pathways regulated TNF-α-induced IL-32 expression in human lung fibroblasts, and inhibition of the Akt and JNK pathways was able to suppress the increased release of IL-32 to nearly the basal level. These data suggest that TNF-α may be involved in airway inflammation via the induction of IL-32 by activating Akt and JNK signalling pathways. Therefore, the TNF-α/IL-32 axis may be a potential therapeutic target for airway inflammatory diseases.

Keywords: cytokines; fibroblasts; inflammation.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Asthma / immunology
  • Cells, Cultured
  • Fibroblasts / cytology
  • Humans
  • Inflammation / immunology*
  • Interferon-gamma / pharmacology
  • Interleukin-17 / pharmacology
  • Interleukin-4 / pharmacology
  • Interleukins / biosynthesis
  • Interleukins / genetics*
  • Interleukins / pharmacology
  • JNK Mitogen-Activated Protein Kinases / antagonists & inhibitors*
  • Lung / cytology
  • Protein Isoforms / genetics
  • Proto-Oncogene Proteins c-akt / antagonists & inhibitors*
  • Pulmonary Disease, Chronic Obstructive / immunology
  • RNA, Messenger / biosynthesis
  • Recombinant Proteins / pharmacology
  • Toll-Like Receptors / metabolism
  • Tumor Necrosis Factor-alpha / pharmacology*
  • Up-Regulation

Substances

  • IL17A protein, human
  • IL27 protein, human
  • IL32 protein, human
  • IL4 protein, human
  • Interleukin-17
  • Interleukins
  • Protein Isoforms
  • RNA, Messenger
  • Recombinant Proteins
  • Toll-Like Receptors
  • Tumor Necrosis Factor-alpha
  • Interleukin-4
  • Interferon-gamma
  • Proto-Oncogene Proteins c-akt
  • JNK Mitogen-Activated Protein Kinases