C5 and Alzheimer disease: Complement inhibition has proved effective in several mouse AD models: inhibition of MAC assembly reduced synapse loss [31,78,108,235]; blocking C5aR1 with the antagonist PMX53 prevented C5a-mediated neuronal death [236,237] and reduced amyloid, microglial activation and inflammation in Tg2576 and 3xTg AD mice [84,117]; C5aR1-antagonist EP67 reduced amyloid load and synapse loss in 5xFAD mice [238].