Pro-inflammatory Cytokine GM-CSF Improves Learning/Memory and Brain Pathology in Dp16 Down Syndrome Mice and Improves Learning/Memory in Wild-Type Mice

Down syndrome (DS) is characterized by chronic neuroinflammation, peripheral inflammation, astrogliosis, imbalanced excitatory/inhibitory neuronal function, and cognitive deficits in both humans and mouse models. Suppression of inflammation has been proposed as a therapeutic approach to treating DS co-morbidities, including intellectual disability (DS/ID). Conversely, we discovered previously that treatment with the pro-inflammatory cytokine granulocyte-macrophage colony-stimulating factor (GM-CSF) improved cognition and reduced biomarkers of brain pathology in humans with Alzheimers disease (AD), another inflammatory disorder, and in a mouse model of AD. To investigate the effects of GM-CSF treatment on DS/ID, we assessed behavior and brain pathology in 12-14 month-old DS mice (Dp[16]1Yey) and their wild-type (WT) littermates, neither of which develop amyloid, and found that GM-CSF treatment improved performance in the radial arm water maze in both Dp16 and WT mice compared to placebo. Dp16 mice also showed abnormal astrocyte morphology and aggregation and fewer calretinin-positive interneurons, both of which were improved by GM-CSF treatment. These findings suggest that stimulating and/or modulating inflammation and the innate immune system with GM-CSF treatment may enhance cognition in both people with DS/ID and in the typical aging population.