The microglia database (http://research-pub.gene.com/BrainMyeloidLandscape) has shown that in Alzheimer’s disease (AD) and Huntington’s disease (HD) patients and murine neurodegenerative models (APP/PS1 and PS2/APP), microglia do not upregulate IDO-1, but the microglia in glioblastoma, murine ischemia, cuprizone and LPS models exhibited upregulated IDO-1 [18]. Here, APP is linked to Huntington disease.