25-hydroxycholesterol promotes brain endothelial dysfunction by remodelling cholesterol metabolism

The antiviral enzyme cholesterol 25-hydroxylase (CH25H) and its metabolite 25-hydroxycholesterol (25HC), which modulates cholesterol metabolism during infection, have been previously associated with vascular pathology. Viral infections have been linked to risk of intracerebral haemorrhage (ICH) but the molecular mechanisms leading to brain vessel rupture via antiviral responses remain unknown. We hypothesised that the CH25H/25HC pathway may impact neuroendothelial integrity in the context of infection-associated ICH. Here, using a SARS-CoV-2-spike-induced zebrafish ICH model and foetal human SARS-CoV-2-associated cortical tissue containing microbleeds, we identified an upregulation of CH25H in infection-associated cerebral haemorrhage. Using zebrafish ICH models and human brain endothelial cells, we asked whether 25HC may promote neurovascular dysfunction by modulating cholesterol metabolism. We found that 25HC and pharmacological inhibition of HMGCR by atorvastatin interacted to exacerbate brain bleeding in zebrafish larvae and in vitro brain endothelial dysfunction. In vitro 25HC-induced dysfunction was also rescued by cholesterol supplementation. These results demonstrate that the antiviral factor 25HC can dysregulate brain endothelial function by remodelling cholesterol metabolism. We propose that the CH25H/25HC pathway represents an important component in the pathophysiology of brain vessel dysfunction associated with infection and cholesterol dysregulation in the context of ICH. Summary StatementThe antiviral metabolite 25-hydroxycholesterol dysregulates brain endothelial function by remodelling cholesterol metabolism, thereby providing a mechanistic link between viral infection and brain endothelial dysfunction in conditions such as intracerebral haemorrhage.