Molecular and Functional Alterations in the Cerebral Microvasculature in an Optimized Mouse Model of Sepsis-Associated Cognitive Dysfunction

Systemic inflammation has been implicated in the development and progression of neurodegenerative conditions such as cognitive impairment and dementia. Recent clinical studies indicate an association between sepsis, endothelial dysfunction, and cognitive decline. However, the investigations of the role and therapeutic potential of the cerebral microvasculature in sepsis-induced cognitive dysfunction have been limited by the lack of standardized experimental models for evaluating the alterations in the cerebral microvasculature and cognition induced by the systemic inflammatory response. Herein, we validated a mouse model of endotoxemia that recapitulates key pathophysiology related to sepsis-induced cognitive dysfunction, including the induction of an acute systemic hyperinflammatory response, blood-brain barrier (BBB) leakage, neurovascular inflammation, and memory impairment after recovery from the systemic inflammation. In the acute phase, we identified novel molecular (e.g., upregulation of plasmalemma vesicle-associated protein, PLVAP, a driver of endothelial permeability, and the procoagulant plasminogen activator inhibitor-1, PAI-1) and functional perturbations (i.e., albumin and small-molecule BBB leakage) in the cerebral microvasculature along with neuroinflammation. Remarkably, small-molecule BBB permeability, elevated levels of PAI-1, intra-/perivascular fibrin/fibrinogen deposition, and microglial activation persisted 1 month after recovery from sepsis. We also highlight molecular neuronal alterations of potential clinical relevance following systemic inflammation including changes in neurofilament phosphorylation and decreases in postsynaptic density protein 95 and brain-derived neurotrophic factor, suggesting diffuse axonal injury, synapse degeneration, and impaired neurotrophism. Our study serves as a standardized mouse model to support future mechanistic studies of sepsis-associated cognitive dysfunction and to identify novel endothelial therapeutic targets for this devastating condition.