Nuclear translocation of HIF-1α induced by influenza A (H1N1) infection is critical to the production of proinflammatory cytokines

Emerg Microbes Infect. 2017 May 24;6(5):e39. doi: 10.1038/emi.2017.21.

Abstract

Infection with the influenza A (H1N1) virus is a major challenge for public health because it can cause severe morbidity and even mortality in humans. The over-secretion of inflammatory cytokines (cytokine storm) is considered to be a key contributor to the severe pneumonia caused by H1N1 infection. It has been reported that hypoxia-inducible factor 1-alpha (HIF-1α) is associated with the production of proinflammatory molecules, but whether HIF-1α participates in the acute inflammatory responses against H1N1 infection is still unclear. To investigate the role of HIF-1α in H1N1 infection, the expression and nuclear translocation of HIF-1α in A549 and THP-1 cell lines infected with H1N1 virus were observed. The results showed that without altering the intracellular mRNA or protein expression of HIF-1α, H1N1 infection only induced nuclear translocation of HIF-1α under normal oxygen concentrations. The use of 2-methoxyestradiol (2ME2), a HIF-1α inhibitor that blocks HIF-1α nuclear accumulation, in H1N1-infected cells decreased the mRNA and protein expression of tumor necrosis factor-alpha (TNF-α) and interleukin (IL)-6 and increased the levels of IL-10. In contrast, H1N1-infected cells under hypoxic conditions had increased HIF-1α nuclear accumulation, increased expression of TNF-α and IL-6 and decreased levels of IL-10. In conclusion, our data implied that in vitro H1N1 infection induced nuclear translocation of HIF-1α without altering the expression of HIF-1α, which may promote the secretion of proinflammatory cytokines during H1N1 infection.

MeSH terms

  • 2-Methoxyestradiol
  • A549 Cells
  • Active Transport, Cell Nucleus*
  • Cell Hypoxia
  • Cell Nucleus / metabolism*
  • Cytokines / biosynthesis*
  • Cytokines / immunology*
  • Estradiol / analogs & derivatives
  • Estradiol / pharmacology
  • Gene Expression Regulation
  • Humans
  • Hypoxia-Inducible Factor 1, alpha Subunit / genetics
  • Hypoxia-Inducible Factor 1, alpha Subunit / metabolism*
  • Inflammation
  • Influenza A Virus, H1N1 Subtype / drug effects
  • Influenza A Virus, H1N1 Subtype / genetics
  • Influenza A Virus, H1N1 Subtype / immunology*
  • Interleukin-10 / genetics
  • Interleukin-10 / immunology
  • Interleukin-6 / genetics
  • Interleukin-6 / immunology
  • Monocytes / immunology
  • Monocytes / virology
  • Oxygen / metabolism
  • RNA, Messenger
  • THP-1 Cells
  • Tumor Necrosis Factor-alpha / genetics
  • Tumor Necrosis Factor-alpha / immunology

Substances

  • Cytokines
  • Hypoxia-Inducible Factor 1, alpha Subunit
  • IL10 protein, human
  • IL6 protein, human
  • Interleukin-6
  • RNA, Messenger
  • Tumor Necrosis Factor-alpha
  • Interleukin-10
  • Estradiol
  • 2-Methoxyestradiol
  • Oxygen