Granulocyte-Macrophage Colony Stimulating Factor Exerts Protective and Immunomodulatory Effects in Cortical Trauma

•GM-CSF treatment after CCI-induced brain injury induces immunomodulatory and neuroprotective responses.•GM-CSF treatment after CCI-induced brain injury increases peripheral Treg frequencies in periphery.•GM-CSF treatment after CCI-induced brain injury diminishes reactive microglial responses.•GM-CSF treatment after CCI-induced brain injury increased integrity of neuronal architecture.•GM-CSF treatment after CCI-induced brain injury diminishes lesion volumes with increased cortical tissue sparing.

Neurodegeneration after traumatic brain injury is facilitated by innate and adaptive immunity and can be harnessed to affect brain repair. In mice subjected to controlled cortical impact (CCI), we show that treatment with granulocyte macrophage colony stimulating factor (GM-CSF) affects regulatory T cell numbers in the cervical lymph nodes coincident with decreased lesion volumes and increased cortical tissue sparing. This paralleled increases in neurofilament and diminished reactive microglial staining. Transcriptomic analysis showed that GM-CSF induces robust immune neuroprotective responses seven days following CCI. Together, these results support the therapeutic potential of GM-CSF for TBI.