Fig. 2

Proposed signals associated with microglia and astrocytes. The pro-inflammatory microglia are activated by IFNs and LPS via the activation of NFκB and STAT1, and then release IL-1β, IL-12, IL-23, SOC3, CXCLs, CCLs, NO, TNF-α, and IL-6. The neuroprotective microglia are promoted by IL-4, IL-13, IL-10, and TGF-β via the activation of STAT3 and STAT6. The M2 microglia enhance the neurotrophic factor (IGF-1), FIZZ1, CD206, Arg1, Ym1, Chi3l3, Fzd1, IL-13, IL-10, IL-4, and TGF-β. The activation of NFκB induces pro-inflammatory astrocytes. The pro-inflammatory astrocytes are affected by IL-1β, IFN-γ, LPS, TNF-α, and IL-6, and they produce IL-1α, C1q, GM-CSF, CXCLs, CCLS, TNF-α, IL-6, and NO. The activation of STAT3 induces neuroprotective astrocytes. The neuroprotective astrocytes interact with anti-inflammatory cytokines such as IL-13, IL-10, TGF-β, and IL-4; IL-4 and TGF-β coordinate to promote protective effects, and IL-4 suppresses TNF-α, IL-6, and NO. CCL: C-C-motif chemokine ligand; CXCL: C-X-C motif chemokine ligand; GM-CSF: granulocyte-macrophage colony-stimulating factor; IFN-γ: interferon γ; IL: interleukin; LPS: lipopolysaccharide; NFκB: nuclear factor κB; NO: nitric oxide; STAT: signal transducers and activators of transcription; TNFα: tumor necrosis factor α