A microglial cell is both a glial cell of the central nervous system and a mononuclear phagocyte, which belongs to the haematopoietic system and is involved in inflammatory and immune responses. As such, microglia face a challenging task. The neurons of the central nervous system cannot divide and be replenished, and therefore need to be protected against pathogens, which is a key role of the immune system, but without collateral damage. In addition, after physical injury, neural cells need restorative support, which is provided by inflammatory responses. Excessive or chronic inflammatory responses can, however, be harmful. How microglia balance these demands, and how their behaviour can be modified to ameliorate disorders of the central nervous system, is becoming clear.
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Work in our laboratories was supported by research grants from the US National Institutes of Health/National Institute of Neurological Diseases and Stroke (to R.M.R.), by research grants and fellowships from the US National MS Society (to R.M.R. and A.E.C.) and by the Williams Family Foundation for MS Research (to R.M.R.).
The authors declare no competing financial interests.
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Ransohoff, R., Cardona, A. The myeloid cells of the central nervous system parenchyma. Nature 468, 253–262 (2010) doi:10.1038/nature09615
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