Flotillin acts as a regulatory cellular barrier against invasion by Escherichia coli K1

Loss of flotillin 1 in human brain microvascular endothelial cells markedly increases invasion by Escherichia coli K1, while flotillin overexpression suppresses invasion via the sphingosine/EGFR axis.

• Why it matters: Neonatal meningitis pathogens must cross the blood-brain barrier, yet how sphingosine kinase–EGFR signalling is coupled to membrane organisation to restrain bacterial entry remains unclear.
• What they did: The study tested flotillin 1 loss or overexpression in endothelial cells and used siRNA or pharmacological inhibition of sphingosine kinases, plus cholesterol dependence and a neonatal mouse infection model.
• The result: In mice, flotillin 1 knockout animals had lower bacteraemia but equivalent brain bacterial burdens, implying flotillin 1 restrains blood-brain barrier penetration by E. coli K1.