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Vitamin A differentially regulates cytokine expression in respiratory epithelial and macrophage cell lines

Rhiannon R Penkert1, Bart G Jones1, Hans Häcker1

  • 1Department of Infectious Diseases, St. Jude Children's Research Hospital, 262 Danny Thomas Place, Memphis, TN 38105, USA.

Cytokine
|December 13, 2016
PubMed

Insights

Vitamin A metabolite retinoic acid affects respiratory cells differently. It downregulates IL-6 in epithelial cells but upregulates it in macrophages, impacting immune responses and explaining past study contradictions.

Area of Science:

  • Immunology
  • Nutritional Science
  • Cell Biology

Background:

  • Vitamin A is crucial for children's respiratory health and immune function.
  • Vitamin A's effects on immune responses, like IL-6 regulation, appear contradictory in different contexts.
  • Retinoic acid (RA), a vitamin A metabolite, is investigated for its role in immune modulation.

Purpose of the Study:

  • To investigate the cell-specific effects of retinoic acid (RA) on respiratory tract epithelial cells (LETs) and macrophages (MACs).
  • To resolve apparent contradictions in how vitamin A influences immune responses, particularly IL-6 production.
  • To understand the impact of RA on immune cell signaling pathways relevant to respiratory infections.

Main Methods:

  • Utilized cell line models of respiratory tract epithelial cells (LETs) and macrophages (MACs).
  • Exposed cell lines to lipopolysaccharide (LPS) or Sendai virus to mimic respiratory pathogen exposure.
  • Analyzed the effects of retinoic acid (RA) on gene and protein expression, including IL-6, MCP-1, GMCSF, IL-10, and RARβ transcripts.

Main Results:

  • Retinoic acid (RA) downregulated IL-6 in epithelial cells (LETs) but upregulated it in macrophages (MACs) upon stimulation.
  • RA increased transcript levels of MCP-1, GMCSF, and IL-10 specifically in macrophages.
  • RA upregulated RARβ transcripts in epithelial cells, suggesting cell-specific metabolic regulation.

Conclusions:

  • The effects of retinoic acid on immune responses are highly dependent on the target cell type.
  • Cell-specific effects of RA help explain discrepancies in previous vitamin A research.
  • Clinical trials involving vitamin A supplementation should consider these cell-specific immune modulations.

Keywords:
Epithelial cellIL-6MacrophageRespiratory tractVitamin A

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