Angiopoietin-like 4 protects against endothelial dysfunction during bacterial sepsis.

Loss of endothelial integrity and vascular leakage are central features of sepsis pathogenesis; however, no effective therapeutic mechanisms for preserving endothelial integrity are available. Here we show that, compared to dermal microvessels, brain microvessels resist infection by Neisseria meningitidis, a bacterial pathogen that causes sepsis and meningitis. By comparing the transcriptional responses to infection in dermal and brain endothelial cells, we identified angiopoietin-like 4 as a key factor produced by the brain endothelium that preserves blood-brain barrier integrity during bacterial sepsis. Conversely, angiopoietin-like 4 is produced at lower levels in the peripheral endothelium. Treatment with recombinant angiopoietin-like 4 reduced vascular leakage, organ failure and death in mouse models of lethal sepsis and N. meningitidis infection. Protection was conferred by a previously uncharacterized domain of angiopoietin-like 4, through binding to the heparan proteoglycan, syndecan-4. These findings reveal a potential strategy to prevent endothelial dysfunction and improve outcomes in patients with sepsis.