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). The gene discussed is C5AR1; the disease is early-onset autosomal dominant Alzheimer disease.