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Stimulus-specific inhibition of intracellular adhesion molecule-1 gene expression by TGF-beta

P Shrikant1, S J Lee, I Kalvakolanu

  • 1Department of Cell Biology, University of Alabama at Birmingham 35294, USA.

Journal of Immunology (Baltimore, Md. : 1950)
|July 15, 1996
PubMed

Insights

Transforming growth factor-beta (TGF-β) selectively suppresses intercellular adhesion molecule-1 (ICAM-1) in astrocytes and microglia. This immunosuppressive cytokine inhibits ICAM-1 induction by TNF-α and IL-1β, but not by IFN-γ.

Area of Science:

  • Neuroimmunology
  • Cellular and Molecular Neuroscience

Background:

  • Astrocytes and microglia are key glial immune cells in the central nervous system.
  • Intercellular adhesion molecule-1 (ICAM-1) is crucial for immune cell trafficking and T-cell activation.
  • ICAM-1 expression in glial cells can be induced by various inflammatory stimuli.

Purpose of the Study:

  • To investigate the role of the immunosuppressive cytokine TGF-β in regulating ICAM-1 expression in astrocytes and microglia.
  • To determine the stimulus-specific effects of TGF-β on ICAM-1 induction in glial cells.

Main Methods:

  • Treatment of primary astrocytes and microglia with various cytokines (TNF-α, IL-1β, IFN-γ) and lipopolysaccharide (LPS).
  • Assessment of ICAM-1 mRNA and protein expression levels.
  • Evaluation of TGF-β's inhibitory effects on ICAM-1 induction and its mechanism of action (transcriptional level).

Main Results:

  • TGF-β alone had minimal effect on constitutive ICAM-1 expression.
  • TGF-β significantly inhibited TNF-α- and IL-1β-induced ICAM-1 mRNA and protein expression in astrocytes.
  • TGF-β did not affect IFN-γ- or IFN-γ/LPS-induced ICAM-1 expression in astrocytes or microglia.
  • The inhibitory effect of TGF-β on TNF-α/IL-1β-induced ICAM-1 was mediated at the transcriptional level.

Conclusions:

  • TGF-β suppresses ICAM-1 expression in glial cells in a stimulus-dependent manner.
  • TGF-β specifically inhibits ICAM-1 induction by TNF-α and IL-1β, suggesting a targeted immunomodulatory role.
  • These findings highlight the complex regulation of glial immune responses by cytokines like TGF-β.

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