The NKCC1 ion transporter contributes to the pathophysiology of common neurological disorders, but its function in microglia, the main inflammatory cells of the brain, has not been studied to date. Therefore, we generated a novel transgenic mouse line in which microglial NKCC1 was deleted. We show that microglial NKCC1 shapes both baseline and reactive microglia morphology and inflammatory responses. As opposed to systemic NKCC1 blockade, which decreased intracortical lipopolysaccharide (LPS)-induced cytokine levels, neuroinflammation was potentiated by both intracortically administered bumetanide and in the absence of microglial NKCC1, suggesting a considerable role for microglia to influence central NKCC1 actions. Correspondingly, microglial NKCC1 KO animals exposed to experimental stroke showed significantly increased brain injury, inflammation, cerebral edema and worse neurological outcome. Thus, NKCC1 emerges as an important player to shape microglial responses and brain inflammation after CNS injury, which is likely to be relevant for common neurological disorders.
bioRxiv Subject Collection: Neuroscience