Notably, IL‐3 significantly increased Ccl2 levels in AAV‐hα‐Syn mice and hα‐Syn fibril‐treated primary microglia (Figure 4I,J), which was consistent with IL‐3′s effects in an AD mouse model.[8] Moreover, we found that IL‐3 increased the signal of CCR2 in microglia in the SNpc of AAV‐hα‐Syn mice (Figure 4K), suggesting that CCR2 is critical for IL‐3 activation of microglial IL‐3Rα. Here, IL3 is linked to Alzheimer disease.