Figure 2.

Cross-regulation between astrocytes and microglia by galectin-1 and galectin-3. Neuroprotective astrocytes secrete galectin-1 to inhibit the neurotoxic activation of microglia. The secreted galectin-1 binds with CD45 on the microglia surface, suppresses NF-κB activation and promotes the polarization of neuroprotective microglia (Starossom et al., 2012). Neurotoxic microglia express various types of lectins. In particular, the up-regulated galectin-3 promotes inflammation response through NF-κB activation (Boza-Serrano et al., 2014). These microglial cells secrete inflammatory cytokines (TNFα) and complements that trigger the activation of neurotoxic astrocytes (Liddelow et al., 2017). Gal, galectin; Sig, Siglec.