Interleukin-1alpha regulates Thy-1 expression on rat vascular endothelial cells

Area of Science:

• Endothelial Cell Biology
• Immunology
• Vascular Biology

Background:

• Thy-1 is a surface molecule on rat endothelium that regulates vascular permeability during inflammation.
• Thy-1 is not expressed in vivo in the rat inferior vena cava (IVC) but is expressed in cultured IVC endothelial cells.
• This suggests Thy-1 expression is acquired in vitro, potentially via autoactivation by cytokine-like substances.

Purpose of the Study:

• To investigate the role of Interleukin-1alpha (IL-1α) in the induction of Thy-1 expression on rat endothelial cells (REC).
• To determine if IL-1α regulates Thy-1 expression in vitro and in vivo.

Main Methods:

• Enzyme-linked immunosorbent assay (ELISA) to detect cytokines in REC culture supernatants.
• In vitro experiments involving addition of exogenous IL-1α, inhibition of protein kinase C, and depletion of IL-1α activity.
• In vivo experiments involving injection of recombinant IL-1α into rat subcutis.

Main Results:

• IL-1α, but not TNF-α or IFN-γ, was detected in REC culture supernatants.
• REC production of IL-1α showed autocrine regulation.
• Thy-1 expression on REC was partially mediated by IL-1α and could be reduced by inhibiting protein kinase C or depleting IL-1α.
• Thy-1 expression was induced on rat vascular endothelium in vivo following IL-1α injection.

Conclusions:

• IL-1α is a key regulator for the induction of Thy-1 expression on REC, both in vitro and in vivo.
• This mechanism contributes to the regulation of vascular permeability at sites of inflammation.