Down-regulating nuclear factor of activated T cells 1 alleviates cognitive deficits in a mouse model of sepsis-associated encephalopathy, possibly by stimulating hippocampal neurogenesis

Sepsis-associated encephalopathy (SAE) is a common complication of sepsis, and has been associated with increased morbidity and mortality. Nuclear factor of activated T cells (NFATs) 1, a transcriptional factor that regulates T cell development, activation and differentiation, has been implicated in neuronal plasticity. Here we examined the potential role of NFAT1 in sepsis-associated encephalopathy in mice. Adult male C57BL/6J mice received intracerebroventricular injections of short interfering RNA against NFAT1 or sex-determining region Y-box 2 (SOX2), or a scrambled control siRNA prior to cecal ligation and perforation (CLP). A group of mice receiving sham surgery were included as an additional control. CLP increased escape latency and decreased the number of crossings into, and total time spent within, the target quadrant in the Morris water maze test. CLP also decreased the freezing time in context-dependent, but not context-independent, fear conditioning test. Knockdown of either NFAT1 or SOX2 attenuated these behavioral deficits. NFAT1 knockdown also attenuated CLP-induced upregulation of SOX2, increased the numbers of nestin-positive cells and newborn astrocytes, reduced the number of immature newborn neurons, and promoted the G1 to S transition of neural stem cells in hippocampus. These findings suggest that NFAT1 may contribute to sepsis-induced behavioral deficits, possibly by promoting SOX2 signaling and neurogenesis.