C5AR1 and Alzheimer disease: Administering a C5aR1 antagonist (cyclic hexapeptide, PMX205) orally for 2–3 months led to a ∼55% reduction in fibrillar and total amyloid deposits in the 12- to 15-month-old Tg2576 mouse model of AD; CD45 and GFAP-reactive areas were also decreased, suggesting fewer activated microglia and astrocytes in this mouse model [66].