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Updated: May 26, 2026
Generation of an Immortalized Murine Brain Microvascular Endothelial Cell Line as an In Vitro Blood Brain Barrier Model
Published on: August 29, 2012
Endothelial cells present an innate resistance to glucocorticoid treatment: implications for therapy of primary
Paola Koenen1, Katarzyna Barczyk, Marc Wolf
1Institute of Immunology, University of Muenster, Muenster, Germany.
Background:
In contrast to other chronic inflammatory diseases glucocorticoids alone do not maintain sufficient remission in primary vasculitis. The reasons for this therapeutic failure remain unclear.
Objectives:
To investigate the molecular effects glucocorticoids exert on endothelial cells (EC) and to elucidate the molecular pathways responsible.
Methods:
A comparative approach was used to treat human micro and macrovascular EC as well as monocytes long and short term with glucocorticoids or glucocorticoids and tumour necrosis factor alpha (TNFα). Gene expression changes were analysed applying microarray technology, sophisticated bioinformatic work-up and quantitative reverse transcription PCR. Glucocorticoid receptor translocation processes were traced by cell fractionation assays and immunofluorescence microscopy.
Results:
In EC glucocorticoids completely failed to inhibit the expression of immune response genes both after sole glucocorticoid exposure and glucocorticoid treatment of a TNFα-induced proinflammatory response. In contrast, an impressive downregulation of proinflammatory genes was seen in monocytes. The study demonstrated that the glucocorticoid receptor is comparably expressed in EC and monocytes, and demonstrated good translocation of ligand-bound glucocorticoid receptor allowing genomic glucocorticoid actions. Refined gene expression analysis showed that in EC transactivation takes place and causes glucocorticoid side effects on growth and metabolism whereas transrepression-mediated anti-inflammatory effects as in monocytes are missing. Insufficient induction of SAP30, an important constituent of the Sin3A-histone deacetylase complex, in EC suggests impairment of transrepression due to co-repressor absence.
Conclusions:
The impressive unresponsiveness of EC to anti-inflammatory glucocorticoid effects is associated with deficiencies downstream of glucocorticoid receptor translocation not affecting transactivation but transrepression. The findings provide the first molecular clues to the poor benefit of glucocorticoid treatment in patients with primary vasculitis.
Insights
Glucocorticoids fail to reduce inflammation in primary vasculitis because endothelial cells (EC) lack anti-inflammatory pathways. This unresponsiveness, linked to impaired gene regulation, explains poor treatment outcomes.
Area of Science:
- Immunology
- Molecular Biology
- Genetics
Background:
- Glucocorticoids are insufficient for primary vasculitis remission.
- The molecular basis for this therapeutic failure is unknown.
Purpose of the Study:
- Investigate glucocorticoid molecular effects on endothelial cells (EC).
- Elucidate the molecular pathways underlying glucocorticoid efficacy and failure.
Main Methods:
- Comparative treatment of human micro/macrovascular EC and monocytes with glucocorticoids +/- tumor necrosis factor alpha (TNFα).
- Gene expression analysis via microarray and qPCR.
- Glucocorticoid receptor (GR) translocation assessed by cell fractionation and immunofluorescence.
Main Results:
- Glucocorticoids failed to inhibit immune response genes in EC, unlike monocytes.
- GR expression and translocation were comparable in EC and monocytes.
- EC exhibited glucocorticoid-induced transactivation (side effects) but lacked transrepression (anti-inflammatory effects).
- Impaired transrepression in EC may stem from insufficient SAP30 induction, affecting co-repressor complex formation.
Conclusions:
- Endothelial cells (EC) show unresponsiveness to anti-inflammatory glucocorticoid effects due to downstream deficiencies in transrepression, not transactivation.
- This molecular mechanism explains the limited benefit of glucocorticoids in primary vasculitis.
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