PROJECT SUMMARY The goal of this application is to evaluate the role of tissue nonspecific alkaline phosphatase activity in cerebral microvessels as a therapeutic target to protect against sepsis-associated neurological impairment. Sepsis is defined as a dysregulated host response to infection that results in multi-organ dysfunction. One organ that is commonly affected in sepsis is the brain. Acute brain dysfunction observed in sepsis patients frequently results in chronic functional and cognitive neurological deficits in sepsis survivors. However, therapeutic approaches to prevent or ameliorate sepsis-associated neurological deficits are limited. Preliminary data from our laboratory demonstrates that TNAP, an enzyme that is highly enriched in cerebral microvessels, may reduce neurological deficits by protecting against the loss of blood-brain barrier (BBB) integrity. We have shown the loss of TNAP activity in cerebral microvessels is coupled with increased vascular permeability, increased leukocyte infiltration into the brain, loss of junctional proteins, and sustained glial activation. The loss of BBB integrity is one of the key events in the pathophysiology of sepsis that is thought to initiate subsequent neuroinflammatory events which result sepsis-associated neurological deficits. In addition, a stable, recombinant alkaline phosphatase (recAP) is currently in clinical trials for treatment of acute kidney injury in sepsis. Taken together, this evidence suggests that recAP may protect against chronic functional and cognitive deficits in sepsis survivors. This application will investigate the central hypothesis that administration of recAP protects against sepsis-associated neurological impairment by protecting BBB integrity and preventing functional and cognitive deficits. To test this, we will use an established preclinical model of experimental sepsis, cecal ligation and puncture (CLP), to determine the optimal therapeutic dose of recAP that will suppress functional and cognitive deficits and prevent the loss of BBB integrity. Male and female mice (8-10 months old) will be subjected to sham- or CLP- surgery and randomly allocated to vehicle or recAP treatment; this will be followed by behavioral testing and subsequent assessment of BBB integrity after 7 days or 28 days. Aim 1 will evaluate recAP as a potential therapeutic strategy to prevent sepsis-associated functional and cognitive deficits. Functional deficits to be assessed are spontaneous and evoked locomotion, gait impairment, and nociception, while cognitive testing will assess associative and reference memory deficits. Aim 2 will determine the ability of recAP to preserve BBB integrity in sepsis. Vessel permeability, junctional proteins, actin cytoskeleton remodeling, and glial activation will be quantified in cortex and hippocampus. The expected outcomes of this exploratory application will provide a foundation for future mechanistic preclinical studies of a novel therapeutic target (TNAP) and a novel therapeutic drug (recAP) to improve neurological outcomes in sepsis.

PROJECT NARRATIVE Sepsis is life-threatening disorder caused by an unregulated systemic response to an infection. Sepsis survivors often experience chronic functional and cognitive deficits, yet there no targeted therapies to prevent the onset, progression, or severity of these symptoms. This proposal will test whether a protein that resides on brain microvessels is a viable therapeutic target to prevent chronic neurological impairment in sepsis survivors.