C5AR2 and early-onset autosomal dominant Alzheimer disease: C5a–C5aR2/C5L2 interaction in astrocytes plays a role in astrocyte-mediated neuroinflammation (289). However, C5L2 exerts neuroprotection in traumatic brain injury (TBI) and chronic neurodegenerative diseases, such as Alzheimer’s disease (AD) (292, 293).