Brain endothelial dysfunction in cerebral adrenoleukodystrophy.

Area of Science:

• Neuroscience
• Genetics
• Cell Biology

Background:

• X-linked adrenoleukodystrophy (X-ALD) is a genetic disorder caused by ABCD1 gene mutations, leading to very long-chain fatty acid accumulation.
• Cerebral X-ALD, the most severe neurological form, involves progressive inflammatory demyelination and blood-brain barrier (BBB) dysfunction.

Purpose of the Study:

• To investigate the role of ABCD1 in brain endothelial cells and its contribution to BBB dysfunction in cerebral X-ALD.
• To identify molecular mechanisms linking ABCD1 deficiency to inflammatory demyelination and leukocyte trafficking.

Main Methods:

• Studied ABCD1 expression in human brain microvascular endothelial cells (hBMECs).
• Silenced ABCD1 in hBMECs to assess very long-chain fatty acid accumulation, adhesion molecule expression, and tight junction protein changes.
• Utilized PCR-array screening to identify downstream molecular targets of ABCD1 deficiency.
• Investigated the role of c-MYC in mediating ABCD1 deficiency effects.

Main Results:

• ABCD1 is highly expressed in hBMECs, crucial for maintaining BBB integrity.
• ABCD1 silencing in hBMECs caused early upregulation of adhesion molecules (ICAM1) and reduced tight junction proteins (CLDN5), preceding fatty acid accumulation.
• Monocyte adhesion and transmigration across the endothelium increased following ABCD1 silencing.
• ABCD1 silencing led to downregulation of the transcription factor c-MYC (MYC) in hBMECs.
• MYC silencing mimicked ABCD1 silencing effects on CLDN5 and ICAM1, suggesting c-MYC mediates these changes.

Conclusions:

• ABCD1 deficiency in brain endothelial cells induces BBB alterations through c-MYC-dependent pathways.
• These endothelial changes contribute to increased leukocyte trafficking across the BBB in cerebral X-ALD.
• Targeting c-MYC or related pathways may offer therapeutic strategies for cerebral X-ALD.