C4A and early-onset autosomal dominant Alzheimer disease: In addition, Lian et al reported that astroglial NF-kB/C3 activation led to impaired synaptic density and dendritic morphology in brain tissue of Alzheimer’s disease (AD) patients [39], and the expressions of C3, C4 and C5 mRNA increased with age in C57BL/6 mice brain [37-39].