Figure 1.

Potential impact of LPS on retinal ganglion cell death: impaired gut microbiota leads to translocation of proinflammatory signaling including bacterial LPS into systemic circulation. LPS induces an upregulation of TLR4 and the complement system in the retina. Microglia are among the first cells to be activated via TLR4, which in turn triggers the release of inflammatory cytokines activating apoptotic pathways leading to retinal ganglion cell death. IL-1β = interleukin 1β; IL-6 = interleukin 6; LPS = lipopolysaccharide; MMPs = matrix metalloproteinases; TLR4 = Toll-like receptor 4; TNF-α = tumor necrosis factor-α.