Although the reviews of neuroinflammation and AD are abundant and comprehensive (for more detail, we recommend Ref; Josef Karkos, 2003; Heppner Frank et al., 2015; Ransohoff, 2016; Cuello, 2017), we will focus on the relationship between microglia and neuroinflammation because microglia harbor the majority of CCR5 in the CNS. The gene discussed is CCR5; the disease is Alzheimer disease.