Figure 1.

M1/M2 microglia polarization during amyotrophic lateral sclerosis (ALS)-induced motor neuron degeneration. During ALS progression activated microglia represent a continuum between the neuroprotective M2 phenotype, which promotes tissue repair and supports neuron survival by releasing neuroprotective factors, vs. the toxic M1, which produces cytokines increasing inflammation and further supporting M1 polarization, thus contributing to neuronal death. Therapeutic approaches targeting microglia polarization and resulting in induction of the M2 phenotype are promising strategies to ameliorate local neurodegeneration and improve the clinical outcome of the disease (see Table 1 for details).