C5 and Alzheimer disease: Therefore, we assessed if C5a‐C5aR1 signaling could influence synaptic engulfment by astrocytes, applying our two different approaches, the genetic deletion of C5aR1 in the Arctic mouse model of AD (Supp Figure S1A) as well as the pharmacological inhibition of C5aR1 in the Tg2576 model of AD (Supp Figure S1B), where microglial ingestion of VGlut1 was not suppressed in CA1, while total VGlut1‐PSD95 puncta was protected (Figure 5B‐C).