Fig. 5
From: Therapeutic non-invasive brain treatments in Alzheimer’s disease: recent advances and challenges
Activation and polarization of microglia in AD. The M1 phenotype produces pro-inflammatory cytokines (i.e., IL-1β, TNF-α, NFκB, and IL-6), exacerbating AD progression. However, the M2 phenotype release anti-inflammatory cytokines (i.e., IL-4, IL-10, and IL-13), providing neuroprotective effects in AD. Similar to microglia, astrocytes are classified into A1 neurotoxic and A2 neurotrophic/neuroprotective phenotypes. In the early stage of AD, quiescent glial cells are activated to the A2 and M2 phenotypes and transformed into A1 and M1 phenotypes at the late stage of AD transformation